Scientific Articles

By selecting a field of Application
By selecting a product
By typing in your keyword : (Keyword can be a particular word, an author, a journal, etc.)
166 articles found

HE009 – Hypercrosslinked polyanilines with nanoporous structure and high surface area: potential adsorbents for hydrogen storage

A method for the preparation of an entirely new type of nanoporous material, hypercrosslinked polyaniline, with permanent porous structure and specific surface areas exceeding 630 m2 g21 has been developed. The hypercrosslinking reaction was carried out with commercial polyaniline and diiodoalkanes or paraformaldehyde using both conventional and microwave assisted processes. Polyaniline swollen in an organic solvent was hypercrosslinked to form a rigid, mesh-like structure with permanent porosity and a high surface area. The resulting materials were characterized using infrared spectroscopy and elemental analysis. Porous properties were determined by means of scanning electron microscopy as well as nitrogen and hydrogen adsorption. Short crosslinks such as those formed using paraformaldehyde and diiodomethane led to materials with the highest surface areas. Surface area also increased with the concentration of polyaniline in solution used during preparation. The hydrogen storage capacities of these materials were also tested and a capacity of 2.2 wt% at 77 K and 3.0 MPa was found for the best adsorbent. Hypercrosslinked polyanilines exhibit a remarkably high affinity for hydrogen, which results in enthalpies of adsorption as high as 9.3 kJ mol21 (exothermic), in sharp contrast with hypercrosslinked polystyrenes and metal–organic frameworks for which significantly lower enthalpies of adsorption, typically in the range of 4–7 kJ mol21, are measured.
Jonathan Germain, Jean M. J. Fréchet and Frantisek Svec, J. Mater. Chem., 2007, 17, 4989–4997

HE0086 – Volumetric hydrogen sorption measurements e Uncertainty error analysis and the importance of thermal equilibration time

The design of a volumetric measurement apparatus is studied by means of an uncertainty analysis to provide guidelines for optimum hydrogen sorption measurements. The reservoir volume should be as small as possible (i.e., 10 cc) to minimize the uncertainty. In addition, the sample mass loading has a profound effect on the uncertainty and the optimum loading is a function of the sample's intrinsic storage capacity. In general, the higher the sample mass loading the lower the uncertainty, regardless of any other parameter. In cases where the material to be tested is not available in gram quantities, the use of high accuracy pressure and temperature transducers significantly mitigates the uncertainty in the sample's hydrogen uptake. Above all, the thermal equilibration time is an important parameter for high accuracy measurements and needs to be taken into consideration at the start of the measurements. Based on a computational analysis, a 5 min wait time is required for achieving thermal equilibrium when the instrument enclosure temperature is different than the ambient temperature.
Dervis Emre Demirocak, Sesha S. Srinivasan, Manoj K. Ram, D. Yogi Goswami, Elias K. Stefanakos, International Journal of Hydrogen Energy 38 (2013) 1469-1477

HE0085 – Reversible hydrogen storage in the Li-Mg-N-H system. The effects of Ru doped single walled carbon nanotubes on NH3 emission and kinetics

In this study, the LiNH2?MgH2 (2:1.1) complex hydride system (Li?Mg?N?H is investigated in terms of hydrogen ab/desorption kinetics and the concomitant NH3 emission levels. By selecting more intense ball milling parameters, the hydrogen ab/desorption kinetics were improved and the NH3 emission reduced. However, it is shown that NH3 emission cannot be completely eliminated during ball milling. Single walled carbon nanotubes (SWCNTs) and 20 wt.% Ru doped SWCNTs are utilized as catalysts to study their effects on NH3 emission and kinetics characteristics of the Li?Mg?N?H system. The SWCNT doped sample did not show any kinetics improvement, whereas the SWCNT-20Ru doped sample showed similar kinetics performance as that of the base sample. More importantly, the presence of SWCNT increased the NH3 emission as compared to the base sample. On the other hand, SWCNT-20Ru doping reduced the NH3 emission compared to the SWCNT doping, but did not eliminate it completely. As revealed from the mass spectrometry signals, the SWCNT-20Ru catalyst starts to decompose NH3 at a temperature as low as 200 °C.
Dervis Emre Demirocak, Sesha S. Srinivasan, Manoj K. Ram, John N. Kuhn, Ranjani Muralidharan, Xiao Li, D. Yogi Goswami, Elias K. Stefanakos, International Journal of Hydrogen Energy 38 (2013) 10039-10049

HE0084 – Remarkable irreversible and reversible dehydrogenation of LiBH4 by doping with nanosized cobalt metalloid compounds

Nanosized cobalt sulfide and cobalt boride were synthesized and doped into LiBH4 to improve the dehydrogenation properties of this important candidate for hydrogen storage. With respect to CoSx doping, the dehydrogenation temperature (peak temperature observed by mass spectrometry) of pristine LiBH4 can be reduced from 440 °C to 175 °C with a maximum capacity of 6.7 wt% at 50% doping. Unfortunately, B2H6 is liberated and the process is not reversible because the CoSx dopant reacts with LiBH4 to form more stable compounds. By changing CoSx to CoBx, a reversible dehydrogenation was realized with greatly improved reversibility. The dehydrogenation temperature was reduced to 350 °C with a maximum capacity of 8.4 wt% at 50% doping amount. It is very significant that CoBx is stable and the release of B2H6 is eliminated. A reversible hydrogen desorption of about 5.3 wt% can be achieved with a LiBH4 + 50% CoBx mixture under a mild rehydrogenation condition of 400 °C at 10 MPa H2. It is obvious that CoSx acts as a reactant even though the dehydrogenation is greatly enhanced, while CoBx behaves as a catalyst significantly promoting the dehydrogenation and reversibility of LiBH4.
Weitong Cai, Hui Wang, Lifang Jiao, Yijing Wang, Min Zhu, International Journal of Hydrogen Energy 38 (2013) 3304-3312

HE0083 – Muon spin relaxation reveals the hydrogen storage mechanism in light alkali metal fullerides

We report a muon spin relaxation investigation of Li6C60 and Na10C60 fullerides, which have been recently demonstrated to be efficient and reversible H2 absorbers above 570 K. We prove that, differently from other fullerides, a sizeable fraction of implanted muons form C60 muonium adduct radicals, with hyperfine coupling depending on the C60 hydrogen coverage. Surprisingly, the fraction of radicals was found to increase up to 65% when lowering T to 5 K in Na10C60Hy. This indicates that hydrogen interaction in these systems is enhanced even at cryogenic temperatures, while the high T needed for hydrogen absorption is only required to overcome the H2 dissociation barrier mediated by alkali metals.
M. Aramini, M. Gaboardi, G. Vlahopoulou, D. Pontiroli, C. Cavallari, C. Milanese, M. Ricco, Carbon 67 (2014) 92-97

HE0082 – Catalysis and evolution on cycling of nanostructured magnesium multilayer thin films

This paper explores the hydrogen cycling properties of Mg/Cr and Mg/V multilayer thin films and studies the effect of chromium and vanadium transition metal catalysts on the cycling properties of thick magnesium coatings. Two transition-metal catalysed magnesium-based multilayer PVD coatings are compared with a non-catalysed magnesium control sample. The (micro-)structural evolution of the thin film coatings into fine, flakey powders is studied in-depth using XRD, SEM and TEM and the hydrogen storage properties of all three materials are assessed using volumetric, gravimetric and calorimetric methods focussing on the effect of the microstructure and composition of the coatings on the hydrogen storage kinetics. It was found that the chromium-catalysed coating had the most favourable hydrogen storage kinetics with an activation energy for the dehydrogenation reaction of 65.7 ± 2.5 kJ mol?1 and a hydrogen capacity of 6.1 ± 0.3 wt%. The mechanism of the dehydrogenation reaction of the catalysed samples was studied using the CV and JMAK kinetic models and it was found that the catalyst material influenced not only the hydrogen storage kinetics but also the mechanism of the reaction
Christopher M.P. Fry, David M. Grant, Gavin S. Walker, International Journal of Hydrogen Energy (2013) 1-12

HE0081 – Ammonia-free infiltration of NaBH4 into highly-ordered mesoporous silica and carbon matrices for hydrogen storage

In this work we focused on nanoconfinement of NaBH4 into highly-ordered Si-based mesoporous scaffold and its carbon replica by ammonia-free wet chemical impregnation. Structural and morphological characterization, performed by X-ray diffraction and transmission electron microscopy enabled us to confirm the effectiveness infiltration procedure. Desorption properties tested by temperature programmed desorption analyses highlighted a noticeable shift towards lower temperature compared to both bulk material and samples of similar systems referred to in the bibliographical data.
F. Peru, S. Garroni, R. Campesi, C. Milanese, A. Marini, E. Pellicer, M.D. Baró, G. Mulas, Journal of Alloys and Compounds 580 (2013) S309–S312

HE0080 – Structural evolution upon decomposition of the LiAlH4+LiBH4 system

In the present work we focus the attention on the phase structural transformations occurring upon the desorption process of the LiBH4 + LiAlH4 system. This study is conducted by means of manometric–calorimetric, in situ Synchrotron Radiation Powder X-ray Diffraction (SR-PXD) and exsitu Solid State Magic Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR) measurements. The desorption reaction is characterized by two main dehydrogenation steps starting at 320 and 380 °C, respectively. The first step corresponds to the decomposition of LiAlH4 into Al and H2via the formation of Li3AlH6 whereas the second one refers to the dehydrogenation of LiBH4 (molten state). In the range 328–380 °C, the molten LiBH4 reacts with metallic Al releasing hydrogen and forming an unidentified phase which appears to be an important intermediate for the desorption mechanism of LiBH4–Al-based systems. Interestingly, NMR studies indicate that the unknown intermediate is stable up to 400 °C and it is mainly composed of Li, B, Al and H. In addition, the NMR measurements of the annealed powders (400 °C) confirm that the desorption reaction of the LiBH4 + Al system proceeds via an amorphous boron compound
S. Soru, A. Taras, C. Pistidda, C. Milanese, C. Bonatto Minella, E. Masolo, P. Nolis, M. D. Baró, A. Marini, M. Tolkiehn, M. Dornheim, S. Enzo, G. Mulas, S. Garroni, Journal of Alloys and Compounds (2013)

HE008 – Hydrogen storage behavior of ZrNi 70/30 and ZrNi 30/70 composites

The Zr–Ni compositional alloys, namely (i) ZrNi 70/30 and (ii) ZrNi 30/70 (both by weight) have been investigated for the reversible hydrogenation behavior. These composites show Zr–Ni intermetallic multi-phase formation as explored by X-ray diffraction studies. The sorption kinetics of ZrNi 70/30 seems much faster (?3–4 times) than that of ZrNi 30/70 alloys. The initial desorption rate increasing with an increase in temperature. A well-defined plateau region was obtained for the ZrNi 70/30 with an equilibrium pressure range from <1 bar (300 ?C) to 10 bars (390 ?C). For ZrNi 30/70, the sloppy plateau region extends to higher equilibrium pressures. It is estimated that the total effective hydrogen concentration for ZrNi 70/30 (?1.0 wt.%) is at least 2 times that of ZrNi 30/70 (?0.5 wt.%) composites. From the PCT isotherms, the enthalpy of reaction ( H) has been calculated to be ?39 kJ/mol H2 for the ZrNi 70/30. The surface morphologies of the hydrogenated materials exhibit the presence of cracks and particle size pulverization in comparison to the pristine alloys
Diego Escobar, Sesha Srinivasan, Yogi Goswami, Elias Stefanakos, Journal of Alloys and Compounds 458 (2008) 223–230

HE0079 – In situ synchrotron radiation powder X-ray diffraction study of the 2LiNH2 + LiH + KBH4 system

In the present work we focus on the 2LiNH2 + KBH4 + LiH system: the phase-structural transformations occurring during the desorption process on the powder mixture are described by in situ synchrotron radiation powder X-ray diffraction (SR-PXD), high-pressure differential scanning calorimetry and manometric measurements. It is observed that LiNH2 transforms into Li2NH during heating, at about 160 °C, while the reflections related to KBH4 disappeared at 380 °C. At higher temperature, the formation of Li3BN2 is detected, together with an evident increase of the background, ascribable to the presence of a further phase in the molten state. Patterns at room temperature, after cooling down the sample, confirm the presence of Li3BN2 and KH as reported in the theoretical study. For the as prepared mixture it is possible to achieve the theoretical hydrogen gravimetric capacity of 7.4 wt%.
Maddalena Sale, Claudio Pistidda, Alessandro Taras, Emilio Napolitano, Chiara Milanese, Fahim Karimi, Martin Dornheim, Sebastiano Garroni, Stefano Enzo, Gabriele Mulas, Journal of Alloys and Compounds 580 (2013) S278–S281

HE0078 – Catalysis and hydrolysis properties of perovskite hydride NaMgH3

The addition of NaH by ball milling is shown to greatly improve the hydrogen storage properties and the hydrolysis properties of MgH2, which is related to the formation of ternary hydride NaMgH3 with specific perovskite structure. The MgH2–10%NaH mixture exhibits better hydriding and dehydriding kinetics than the MgH2–10%LiH mixture, in which the LiMgH3 with perovskite structure could not be formed. The catalytic role of NaMgH3 is attributed to fast hydrogen mobility in the perovskite structure, which provides fast hydrogen diffusion pathways for the hydriding and dehydriding of MgH2. The NaMgH3 also shows fast hydrolysis reaction kinetics without any passivation. Our work shows that such perovskite-type hydride demonstrates great potential as efficient catalysts for the high-capacity hydrides for whether reversible or irreversible hydrogen storage.
H. Wang, J. Zhang, J.W. Liu, L.Z. Ouyang, M. Zhu, Journal of Alloys and Compounds 580 (2013) S197–S201

HE0077 – Surface properties of V40(TiCr)51Fe8Mn alloy during hydrogenation/dehydrogenation cycles

The bcc alloy V40(TiCr)51Fe8Mn shows a high reversible hydrogen capacity of 2.22 mass% at room temperature and is therefore expected to be applied as a hydrogen storage material. During the first 10 hydrogenation/dehydrogenation cycles, the capacity decreases markedly from 2.22 to 1.86 mass%. Possible reasons are both internal (including lattice variation, strain, phase transformation, phase disproportion, etc.) and external factors (poisoning by impurities in the gas after decades of cycles mainly). In this work, the surface properties of the V40(TiCr)51Fe8Mn alloy during 20 hydrogenation/dehydrogenation cycles were investigated by XPS analysis. During hydrogenation/dehydrogenation cycles, the surface becomes oxidized. Particular oxides were known to block hydrogen uptake and might thus be responsible for the capacity decay. It was found that Cr is enriched at the surface. Dense and passive chromia forms thereafter around alloy particles and hinder further oxidation and therefore stops further degradation of the hydrogen capacity of the alloy.
Chaoling Wu, Andreas Borgschulte, Urs Frischknecht, Yigang Yan, Fei Yang, Linshan Luo, Yungui Chen, Andreas Züttel, Journal of Alloys and Compounds 580 (2013) S156–S158

HE0076 – New directions for hydrogen storage: sulphur destabilised sodium aluminium hydride

Aluminium sulphide (Al2S3) is predicted to effectively destabilise sodium aluminium hydride (NaAlH4) in a single-step endothermic hydrogen release reaction. The experimental results show unexpectedly complex desorption processes and a range of new sulphur containing hydrogen storage materials have been observed. The NaAlH4–Al2S3 system releases a total of 4.9 wt% of H2 that begins below 100 °C without the need for a catalyst. Characterisation via temperature programmed desorption, in situ synchrotron powder X-ray diffraction, ex situ x-ray diffraction, ex situ Fourier transform infrared spectroscopy and hydrogen sorption measurements reveal complex decomposition processes that involve multiple new sulphur-containing hydride compounds. The system shows partial H2 reversibility, without the need for a catalyst, with a stable H2 capacity of 1.6 wt% over 15 cycles in the temperature range of 200 °C to 300 °C. This absorption capacity is limited by the need for high H2 pressures (>280 bar) to drive the absorption process at the high temperatures required for reasonable absorption kinetics. The large number of new phases discovered in this system suggests that destabilisation of complex hydrides with metal sulphides is a novel but unexplored research avenue for hydrogen storage materials.
Drew A. Sheppard, Lars H. Jepsen, Torben R. Jensen, Mark Paskeviciusa, Craig E. Buckley, J. Mater. Chem. A, 2013, 1, 12775

HE0075 – Affects of mechanical milling and metal oxide additives on sorption kinetics of 1:1 LiNH2/MgH2 mixture

The destabilized complex hydride system composed of LiNH2:MgH2 (1:1 molar ratio) is one of the leading candidates of hydrogen storage with a reversible hydrogen storage capacity of 8.1 wt%. A low sorption enthalpy of ~32 kJ/mole H2 was first predicted by Alapati et al. utilizing first principle density function theory (DFT) calculations and has been subsequently confirmed empirically by Lu et al. through differential thermal analysis (DTA). This enthalpy suggests that favorable sorption kinetics should be obtainable at temperatures in the range of 160 °C to 200 °C. Preliminary experiments reported in the literature indicate that sorption kinetics are substantially lower than expected in this temperature range despite favorable thermodynamics. Systematic isothermal and isobaric sorption experiments were performed using a Sievert’s apparatus to form a baseline data set by which to compare kinetic results over the pressure and temperature range anticipated for use of this material as a hydrogen storage media. Various material preparation methods and compositional modifications were performed in attempts to increase the kinetics while lowering the sorption temperatures. This paper outlines the results of these systematic tests and describes a number of beneficial additions which influence kinetics as well as NH3 formation
Donald L. Anton, Christine J. Price, Joshua Gray,Energies 2011, 4(5), 826-844

HE0074 – The Affects of Halide Modifiers on the Sorption Kinetics of the Li-Mg-N-H System

In this present work, the affects of different transition metal halides (TiCl3, VCl3, ScCl3 and NiCl2) on the sorption properties of the 1:1 molar ratio of LiNH2 to MgH2 are investigated. The modified mixtures were found to contain LiNH2, MgH2 and LiCl. TGA results showed that the hydrogen desorption temperature was reduced with the modifier addition in this order: TiCl3>ScCl3>VCl3>NiCl2. Ammonia release was not significantly reduced resulting in a weight loss greater than the theoretical hydrogen storage capacity of the material. The isothermal sorption kinetics of the modified systems showed little improvement after the first dehydrogenation cycle over the unmodified system but showed drastic improvement in rehydrogenation cycles. XRD and Raman spectroscopy identified the cycled material to be composed of LiH, MgH2, Mg(NH2)2 and Mg3N2.
Christine J. Erdy-Price, Joshua R. Gray, Robert J. Lascola, Donald L Anton, Publication of Savannah River National Laboratory

HE0073 – Nanoconfined 2LiBH4-MgH2-TiCl3 in carbon aerogel scaffold for reversible hydrogen storage

Nanoconfinement of 2LiBH4–MgH2–TiCl3 in resorcinol–formaldehyde carbon aerogel scaffold (RF–CAS) for reversible hydrogen storage applications is proposed. RF–CAS is encapsulated with approximately 1.6 wt. % TiCl3 by solution impregnation technique, and it is further nanoconfined with bulk 2LiBH4–MgH2 via melt infiltration. Faster dehydrogenation kinetics is obtained after TiCl3 impregnation, for example, nanoconfined 2LiBH4–MgH2–TiCl3 requires ?1 and 4.5 h, respectively, to release 95% of the total hydrogen content during the 1st and 2nd cycles, while nanoconfined 2LiBH4–MgH2 (?2.5 and 7 h, respectively) and bulk material (?23 and 22 h, respectively) take considerably longer. Moreover, 95–98.6% of the theoretical H2 storage capacity (3.6–3.75 wt. % H2) is reproduced after four hydrogen release and uptake cycles of the nanoconfined 2LiBH4–MgH2–TiCl3. The reversibility of this hydrogen storage material is confirmed by the formation of LiBH4 and MgH2 after rehydrogenation using FTIR and SR-PXD techniques, respectively
Rapee Gosalawit-Utke, Chiara Milanese, Payam Javadian, Julian Jepsen, Daniel Laipple, Fahim Karmi, Julian Puszkiel, Torben R. Jensen, Amedeo Marini, Thomas Klassen, Martin Dornheim, International journal of hydrogen energy 38 (2013) 3275-3282

HE0072 – Structure and hydrogen storage properties of the hexagonal Laves phase Sc(Al1 xNix)2

The crystal structures of hydrogenated and unhydrogenated Sc(Al1?xNix)2 Laves phases have been studied by combining several diffraction techniques and it is shown that hydrogen is situated interstitially in the A2B2-sites, which have the maximum number of scandium neighbours. The hydrogen absorption/desorption behaviour has also been investigated. It is shown that a solid solution of hydrogen forms in the mother compound. The hydrogen storage capacity exceeds 1.7 H/f.u. at 374 K, and the activation energy of hydrogen desorption was determined to 4.6 kJ/mol H2. It is shown that these compounds share the same local coordination as Frank–Kasper-type approximants and quasicrystals, which opens up the possibility of finding many new hydride phases with these types of crystal structures
Martin Sahlberg, Jonas Angström, Claudia Zlote, Premysl Beran, Michel Latroche, Cesar Pay Gomez, Journal of Solid State Chemistry 196 (2012) 132–137

HE0071 – Fully reversible hydrogen absorption and desorption reactions with Sc(Al1 xMgx), x¼0.0, 0.15,0.20

The hydrogen storage properties of Sc(Al1?xMgx), x=0.0, 0.15, 0.20, have been studied by X-ray powder diffraction, thermal desorption spectroscopy, pressure-composition-isotherms and scanning electron microscopy techniques. Hydrogen is absorbed from the gas phase at 70 kPa and 400 °C under the formation of ScH2 and aluminium with magnesium in solid solution. The reaction is fully reversible in vacuum at 500 °C and shows the hydrogenation–disproportionation–desorption-recombination (HDDR) behaviour. The activation energy of desorption was determined by the Kissinger method to 185 kJ/mol. The material is stable up to at least six absorption–desorption cycles and there is no change in particle size during cycling.
Martin Sahlberg, Claudia Zlote, Michel Latroche, Yvonne Andersson, Journal of Solid State Chemistry 184 (2011) 104–108

HE0070 – Ball-milling and AlB2 addition effects on the hydrogen sorption properties of the CaH2 + MgB2 system

Among the borohydrides proposed for solid state hydrogen storage, Ca(BH4)2 is particularly interesting because of its favourable thermodynamics and relatively cheap price. Composite systems, where other species are present in addition to the borohydride, show some advantages in hydrogen sorption properties with respect to the borohydrides alone, despite a reduction of the theoretical storage capacity. We have investigated the milling time influence on the sorption properties of the CaH2 + MgB2 system from which Ca(BH4)2 and MgH2 can be synthesized by hydrogen absorption process. Manometric and calorimetric measurements showed better kinetics for long time milled samples. We found that the total substitution of MgB2 with AlB2 in the starting material can improve the sorption properties significantly, while the co-existence of both magnesium and aluminum borides in the starting mixture did not cause any improvement. Rietveld refinements of the X-ray powder diffraction spectra were used to confirm the hypothesized reactions
B. Schiavo, A. Girella, F. Agresti, G. Capurso, C. Milanese, Journal of Alloys and Compounds 509S (2011) S714– S718

HE007 – Polyaniline-based nanocomposite materials for hydrogen storage

Nanomaterials have diverse tunable physical properties as a function of their size and shape due to strong quantum confinement effect and large surface to volume ratio. On basis of these facts, nanocomposite materials can be considered as strong candidates for hydrogen storage. In the present work, we report a novel conducting polymeric nanocomposite material for hydrogen storage. Conducting polymer-based nanocomposites were modified using carbon nanotubes as filler material. This further increased the porous structure of the nanocomposite and the number of binding sites, which in turn enhances the hydrogen storage capacity. Additionally, fine aluminum powder was added to the polymeric nanocomposite, which further increased the hydrogen sorption of the material. The modified conducting polymeric nanocomposites were characterized with various analytical techniques including FTIR, DSC, TGA and SEM. Adsorption and desorption experiments are conducted using a Sieverts-type volumetric PCT instrument. Further experiments are in progress to understand the hydrogen storage mechanism in the proposed conducting polymer nanocomposites.
Michael Ulrich Jurczyk, Ashok Kumar, Sesha Srinivasan, Elias Stefanakos, International Journal of Hydrogen Energy 32 (2007) 1010 – 1015

HE0069 – Chloride substitution in sodium borohydride

The dissolution of sodium chloride and sodium borohydride into each other resulting in formation of solid solutions of composition Na(BH4)1?xClx is studied. The dissolution reaction is facilitated by two methods: ball milling or combination of ball milling and annealing at 300 °C for three days of NaBH4–NaCl samples in molar ratios of 0.5:0.5 and 0.75:0.25. The degree of dissolution is studied by Rietveld refinement of synchrotron radiation powder X-ray diffraction (SR-PXD) data. The results show that dissolution of 10 mol% NaCl into NaBH4, forming Na(BH4)0.9Cl0.1, takes place during ball milling. A higher degree of dissolution of NaCl in NaBH4 is obtained by annealing resulting in solid solutions containing up to 57 mol% NaCl, i.e. Na(BH4)0.43Cl0.57. In addition, annealing results in dissolution of 10–20 mol% NaBH4 into NaCl. The mechanism of the dissolution during annealing and the decomposition pathway of the solid solutions are studied by in situ SR-PXD. Furthermore, the stability upon hydrogen release and uptake were studied by Sieverts measurements.
Dorthe B. Ravnsbæk,Line H. Rude,Torben R. Jensen, Journal of Solid State Chemistry 184(2011)1858–1866

HE0068 – An experimental investigation on the poor hydrogen sorption properties of nano-structured LaNi5 prepared by ball-milling

Nano-structured LaNi5 hydrogen storage materials prepared by ball-milling is analysed using differential scanning calorimetry (DSC) and x-ray photoelectron spectroscopy (XPS). DSC results indicate a partial elimination of defects at 500 °C in a more efficient way for the short-time ball-milled powders compared to the long-time ball-milled ones. XPS results show almost no change in the core-level electronic structure for La and Ni of LaNi5 in the bulk and the nano-structured forms, but gives an indication that the self-restoring mechanism of the active surface observed in the bulk sample (Siegmann et al. Phys. Rev. Lett. 40, 972) may not be occurring in the nano-powders. Results from the X-ray diffraction and the local structural studies together with the above observations suggest that the reduced unit-cell volume and the enhanced atomic disorder in the nano-structured LaNi5 cause a larger energy barrier for the hydrogen sorption reactions of the long-time ball-milled samples.
B. Joseph, B. Schiavo, G. D’Al? Staiti, B.R. Sekhar, International journal of hydrogen energy 36 (2011) 7914-7919

HE0067 – Hydrogen Adsorption in Zeolite Studied with Sievert and Thermogravimetric Methods

Natural clinoptilolite (mixture from clinoptilolite, quartz and muscovite) is activated with palladium and tested for hydrogen adsorption capability at temperatures RT - 200°C. Thermogravimetric and volumetric methods showed that zeolite activated with palladium (1.25%wt) shows markedly high hydrogen adsorption capacity - up to 3 wt%. Lower amount of adsorbed hydrogen (~1.5 wt%) was found for raw zeolite and activated with higher amount of palladium sample. Hypothesis is proposed that the heating of zeolite in argon atmosphere forms and activates the pore structure in zeolite material, where hydrogen encapsulation (trapping) is believed to occur when cooling down to room temperature. An effect of catalyst (Pd) on hydrogen sorption capability is explained by spillover phenomena were less-porous fractions of natural clinoptilolite sample (quartz and muscovite) are involved.
P. Lesnicenoks, A Sivars, L Grinberga, J Kleperis, IOP Conf.Series : Materials Science and Engineering 38 (2012) 012060

HE0066 – Increased volumetric hydrogen uptake of MOF-5 by powder densification

The metal-organic framework MOF-5 has attracted significant attention due to its ability to store large quantities of H2 by mass, up to 10 wt.% absolute at 70 bar and 77 K. On the other hand, since MOF-5 is typically obtained as a bulk powder, it exhibits a low volumetric density and poor thermal conductivity—both of which are undesirable characteristics for a hydrogen storage material. Here we explore the extent to which powder densification can overcome these deficiencies, as well as characterize the impact of densification on crystallinity, pore volume, surface area, and crush strength. MOF-5 powder was processed into cylindrical tablets with densities up to 1.6 g/cm3 by mechanical compaction. We find that optimal hydrogen storage properties are achieved for ? ? 0.5 g/cm3, yielding a 350% increase in volumetric H2 density with only a modest 15% reduction in gravimetric H2 excess in comparison to the powder. Higher densities result in larger reductions in gravimetric excess. Total pore volume and surface area decrease commensurately with the gravimetric capacity, and are linked to an incipient amorphization transformation. Nevertheless, a large fraction of MOF-5 crystallinity remains intact in densities up to 0.75 g/cm3, as confirmed from powder XRD. Predictably, the radial crush strength of the pellets is enhanced by densification, increasing by a factor of 4.3 between a density of 0.4 g/cm3 and 0.6 g/cm3. Thermal conductivity increases slightly with tablet density, but remains below the single crystal value.
J.J. Purewal, D. Liu, J. Yang, A. Sudik, D.J. Siegel, S. Maurer, U. Müller, International journal of hydrogen energy 37 (2012) 2723-2727

HE0065 – The effects of halide modifiers on the sorption kinetics of the Li-Mg-N-H System

The effects of different transition metal halides (TiCl3, VCl3, ScCl3 and NiCl2) on the sorption properties of the 1:1 molar ratio of LiNH2 to MgH2 are investigated. The modified mixtures were found to contain LiNH2, MgH2 and LiCl. TGA results showed that the hydrogen desorption temperature was reduced with the modifier addition in this order: TiCl3 > ScCl3 > VCl3 > NiCl2. Ammonia release was not significantly reduced resulting in a weight loss greater than the theoretical hydrogen storage capacity of the material. The isothermal sorption kinetics of the modified systems showed little improvement after the first dehydrogenation cycle over the unmodified system but showed drastic improvement in rehydrogenation cycles. X-ray diffraction and Raman spectroscopy identified the cycled material to be composed of LiH, MgH2, Mg(NH2)2 and Mg3N2
Christine Price, Joshua Gray, Robert Lascola Jr., Donald L. Anton, International journal of hydrogen energy 37 (2012) 2742-2749

HE0064 – Kinetic and thermodynamic studies of hydrogen adsorption on titanate nanotubes decorated with a Prussian blue analogue

In this paper, the kinetic and thermodynamic hydrogen adsorption characteristics of a novel composite comprising TiNT decorated with the Prussian blue analogue Cd3FeIII are investigated at high pressures and different temperatures. It is shown that boundary-layer (film) diffusion does not play a limiting role in the mass transport of hydrogen inside the composite material. The diffusion coefficient and time constant at different temperatures and pressures are calculated using an intra-particle diffusion model. The results suggest that molecular diffusion dominates Knudsen diffusion in the composite material. There are clear improvements in the mass transport characteristics compared to bulk Cd3FeIII. The Gibb's free energy is estimated by fitting isotherm equilibrium data to the Dubinin–Astakhov model and is used to calculate the enthalpy and the entropy of adsorption. The calculated value of enthalpy is characteristic of a physisorption process and is considerably higher than the activation energy for intraparticle diffusion, suggesting that the rate-limiting step of hydrogen is not mass transport to the adsorption sites.
B. Zamora, A.A. Al-Hajjaja, A.A. Shahc, D.V. Bavykina, E. Reguerab, International Journal of Hydrogen Energy, Volume 38, Issue 15, 20 May 2013, Pages 6406–6416

HE0063 – Enhanced dehydrogenation properties of LiBH4 compositing with hydrogenated magnesium-rare earth compounds

LiBH4 is regarded as a promising hydrogen storage material due to its high hydrogen density. In this study, the dehydrogenation properties of LiBH4 were remarkably enhanced by doping hydrogenated Mg3RE compounds (RE denotes La, Ce, Nd rare earth metals), which are composed of nanostructured MgH2 and REH2+x (denoted as H ? Mg3RE). For the LiBH4 + H ? Mg3La mixture, the component LiBH4 desorbed 6 wt.% hydrogen even at a relatively low temperature of 340 °C, far lower than the desorption temperature of pure LiBH4 or the 2LiBH4 + MgH2 system. This kinetic improvement is attributed to the hydrogen exchange mechanism between the H ? Mg3La and LiBH4, in the sense that the decomposition of MgH2 and LaH2+x catalyzed the dehydrogenation of LiBH4 through hydrogen exchange effect rather than mutual chemical reaction requiring higher temperature and hydrogen pressure. However, prior to fast hydrogen release, the hydrogen exchange effect suppressed the dehydriding of MgH2 and elevated its desorption temperature. It is expected to strengthen the hydrogen exchange effect by compositing the LiBH4 with other nanosized metal hydrides and to obtain better dehydrogenation properties
C. Luo, H. Wang, T. Sun, M. Zhu, International journal of hydrogen energy 37 (2012) 13446-13451

HE0062 – Hydrogen storage in 2NaBH4 + MgH2 mixtures: Destabilization by additives and nanoconfinement

We focus on the H2 desorption properties of the 2NaBH4 + MgH2 system destabilized by different methods. Nanostructured powder mixtures were prepared by ball milling the starting hydrides and nanoconfined reactive composites were obtained by melting infiltration of the hydrides into a Si-based SBA-15 support. NbF5 was tested as catalyst in both the preparations. Structural characterization by X Ray Diffraction and Transmission Electron Microscopy allowed evaluating the successful synthesis of SBA15 matrix, the microstructural features of ball milled and nanoconfined hydrides as well as the success of infiltration process. The evaluation of the sorption properties, by manometric Sievert-type apparatus and thermal desorption spectroscopy, revealed the efficiency of the hydride destabilization, obtained by the different routes, in decreasing the hydrogen release temperature and improving desorption kinetics.
G. Mulas, R. Campesi, S. Garroni, E. Napolitano, C. Milanese, F. Dolci, E. Pellicer, D. Baró, A. Marini, Journal of Alloys and Compounds 536S (2012) S236– S240

HE0061 – Influence of the substitution of V by Nb in the structure and properties of hydrogen absorption/desorption of TiCr1.1V0.9 alloy

The partial substitution of V by Nb in the TiCr1.1V0.9 alloy was performed generating four different compounds. The thermal stability, the hydrogen storage capacity as well as the kinetics of absorption/desorption were studied. It was observed that the addition of Nb decreases the hydrogen absorption capacity from 3.6 wt% to 2.5 wt%, but it increases the kinetic. The desorption performance improves above 373 K.
A. Martínez, D.S. dos Santos, Journal of Alloys and Compounds 536S (2012) S231– S235

HE006 – LaMg2PdH7, a new complex metal hydride containing tetrahedral [PdH4]4? anions

Hydrogenation of the intermetallic compound LaMg2Pd at 200 ?C and 10 bar leads to a complex metal hydride of composition LaMg2PdH7. Its structure has orthorhombic symmetry and displays tetrahedral [PdH4]4? anions. The Pd–H bond distances as measured on the deuteride range from 1.71 to 1.78 °A and the H–Pd–H bond angles from 95? to 122?. Three additional hydride anions H? occupy La2Mg2-type interstices having tetrahedral metal configurations. Band structure calculations suggest the hydride to be non-metallic and to have a band gap of ?1.0 eV. The compound desorbs hydrogen at 125 ?C yielding a pressure of more than 1 bar absolute.
K. Yvon, J.-Ph. Rapin , N. Penin, Zhu Mab, M.Y. Choub, Journal of Alloys and Compounds 446–447 (2007) 34–38

HE0059 – Sorption of hydrogen onto titanate nanotubes decorated with a nanostructured Cd3[Fe(CN)6]2 Prussian Blue analogue

Nanostructured films of cadmium hexacyanoferrate (III), Cd3[Fe(CN)6]2 have been deposited on the surface of titanate nanotubes (TiNT) by ion exchange with CdSO4, followed by reaction with K3[Fe(CN)6] in an aqueous suspension. The composite demonstrates a significantly higher hydrogen storage uptake than pure Cd3[Fe(CN)6]2 and TiNT. At a temperature of 77 K and a pressure 100 bar, the hydrogen uptake for the composite is approximately 12.5 wt %, whereas only 4.5 wt % and 4 wt % are achieved for the TiNT and Cd3[Fe(CN)6]2 respectively. Electron microscopy and infrared spectroscopy show that Cd3[Fe(CN)6]2 is uniformly distributed on the surface of the nanotubes forming a discontinuous nanostructured film with a well developed interface, which allows efficient interaction with the support. The possible reasons for the high uptake of hydrogen in the composite are discussed
A.A. Al-Hajjaj, B. Zamora, D.V. Bavykin, A.A. Shah, F.C. Walsh, E. Reguera, International journal of hydrogen energy 37 (2012) 318-326

HE0058 – Synthesis and characterization of mesoporous PdPtCr alloy and its influence on the hydrogen kinetics in MgH2

The compounds made of MgH2 and (1 and 5 wt.%) Pd40Pt30Cr30 catalyst by mechanical milling were tested for their ability to absorb and desorb hydrogen. The mesoporous Pd40Pt30Cr30 was obtained by the reduction of chloride complexes and using a surfactant solution. The absorption kinetic tests showed that the MgH2 + 1 wt.% Pd40Pt30Cr30 sample attained 90% of hydrogen capacity around 10 min, at 350°C. The desorption tests showed that the MgH2 + 5 wt.% Pd40Pt30Cr30 sample desorbed completely in about 5 min at the same temperature. The highest hydrogen capacity, 6.8 wt.% of H2, was determined by absorption/desorption P-C-Isotherm curves at 300°C for MgH2 + 1 wt.% Pd40Pt30Cr30 sample. The MgH2 + 5 wt.% Pd70Pt30 was used in the hydrogenation tests to elucidate the fact that the presence of CrCl3 in the Pd40Pt30Cr30 alloy mixed to MgH2, leads to an increase in the hydrogen total capacity of absorption.
M.O.T. da Conceicão, M.C. Brum, C.S. Guimarães, D.S. dos Santos, Journal of Alloys and Compounds 536S (2012) S255– S258

HE0057 – The effect of V, VCl3 and VC catalysts on the MgH2 hydrogen sorption properties

MgH2 based composites processed by mechanical alloying with the addition of 5 wt.% of V, VCand VCl3 were evaluated for their absorption/desorption hydrogen capacities at 300 and 350°C. These composites were investigated by the following techniques: X-ray diffraction, XRD, Pressure–Composition Isotherms, PCI and Differential Scanning Calorimetry, DSC. It was observed that the addition of V, VC and VCl3 compounds improves hydrogen absorption and desorption kinetics in comparison to the MgH2. The MgH2-5 wt.% VCl3 composite showed the faster absorption kinetics which absorbed 6.0 wt.% of H2 in 7.5 min at 350°C. The desorption activation energy of the composite containing VCl3 (47 kJ mol 1) is smaller than VC (63 kJ mol 1). This indicates that this catalyst is more effective to be used in hydrogen storage system.
M.O.T. da Conceição, M.C. Brum, D.S. dos Santos, Journal of Alloys and Compounds (2013)

HE0056 – Hydrogen sorption–desorption studies on ZrCo–hydrogen system

The ZrCo–H2 system was investigated in this study owing to its importance as a suitable candidate material for storage, supply, and recovery of hydrogen isotopes. Desorption hydrogen pressure-composition isotherms were generated at six different temperatures in the range of 524–624 K. A van’t Hoff plot was constructed using the plateau pressure data of each pressure-composition isotherms and the thermodynamic parameters were calculated for the hydrogen desorption reaction of ZrCo hydride. The enthalpy and entropy change for the desorption of hydrogen were found to be 83.7 ± 3.9 kJ mol-1 H2 and 122 ± 4 J mol-1 H2 K-1, respectively. Hydrogen absorption kinetics of ZrCo–H2 system was studied at four different temperatures in the range of 544–603 K and the activation energy for the absorption of hydrogen by ZrCo was found to be 120 ± 5 kJ mol-1 H2 by fitting kinetic data into suitable kinetic model equation.
Ram Avtar Jat, S. C. Parida, J. Nuwad, Renu Agarwal, S. G. Kulkarni, J Therm Anal Calorim, 2012

HE0054 – New compounds in the potassium-aluminium-hydrogen system observed during release and uptake of hydrogen

Three new compounds are observed in the potassium-aluminium-hydrogen system, which are characterised using in-situ synchrotron radiation powder X-ray diffraction (SR-PXD), thermal analysis (TG and DSC) and Siverts measurements (PCT). All three new compounds (denoted 1, 2 and 3) are observed during release and uptake of hydrogen in the potassium- aluminium-hydrogen system and may be new intermediates. All three compounds were indexed and the following unit cells were found, 1: cubic, a = 17.0248(9) A° , 2: cubic, a = 14.2746(4)A° and 3: orthorhombic, a = 10.46(1), b = 6.661(6) and c = 6.173(5)A° . Formation and observation of 1, 2 and 3 depends on the mechano-chemical sample preparation (ball milling), temperature, (heating rate), and hydrogen pressure (and temperature for pressure change). Compound 1 is often observed in the temperature range 55e150 "C for a medium ball-milled sample heated under a constant hydrogen pressure of 50 bar 1 is clearly an intermediate for formation of KAlH4 and may have the composition KyAlHx with 1 < y < 3 and 4 < x < 6. Applying hydrogen pressure abruptly at elevated temperatures leads to faster hydrogenation, which can then be performed at lower hydrogen pressures. In the latter case, 1 is only observed shortly in a few PXD patterns. Compounds 2 and 3 are mainly observed during dehydrogenation of KAlH4 in the temperature ranges of ca. 200 to 350 "C and 200 to 390 "C respectively, as relatively weak Bragg diffraction peaks.
Lene Mosegaard Arnbjerg, Torben R. Jensen, International journal of hydrogen energy 37 (2012) 345-356

HE0053 – Recommended Best Practices for the Characterization of Storage Properties of Hydrogen Storage Materials

This Recommended Practices for the Characterization of Hydrogen Storage Materials document provides an introduction to and overview of the recommended best practices in making measurements of the hydrogen storage properties of materials. Due to the breadth of the subjects covered, material will be presented in its most concise and accessible form. The authors will use examples from literature to add clarity to key topics and to provide the reader with avenues for further detailed inquiry into a specific subject. The Recommended Practices document is divided into an introductory section and will be followed by four or more chapters that cover the topic areas of:concentration and capacity, kinetics, thermodynamics and cycle life measurements of hydrogen storage materials as well as other important hydrogen storage materials properties.
Karl J. Gross, K. Russell Carrington, Steven Barcelo, Abhi Karkamkar, Justin Purewal,

HE0051 – Iodide substitution in lithium borohydride, LiBH4–LiI

The new concept, anion substitution, is explored for possible improvement of hydrogen storage properties in the system LiBH4–LiI. The structural chemistry and the substitution mechanism are analyzed using Rietveld refinement of in situ synchrotron radiation powder Xray diffraction (SRPXD) data, attenuated total reflectance infrared spectroscopy (ATRIR), differential scanning calorimetry (DSC) and Sieverts measurements. Anion substitution is observed as formation of two solid solutions of Li(BH4)1?xIx, which merge into one upon heating. The solid solutions have hexagonal structures (space group P63mc) similar to the structures of hLiBH4 and bLiI. The solid solutions have iodide contents in the range ?0–62 mol% and are stable from below room temperature to the melting point at 330 ?C. Thus the stability of the solid solutions is higher as compared to that of the orthorhombic and hexagonal polymorphs of LiBH4 and ? and ? LiI. Furthermore, the rehydrogenation properties of the iodide substituted solid solution Li(BH4)1?xIx, measured by the Sieverts method, are improved as compared to those of LiBH4. After four cycles of hydrogen release and uptake the Li(BH4)1?xIx solid solution maintains 68% of the calculated hydrogen storage capacity in contrast to LiBH4, which maintains only 25% of the storage capacity after two cycles under identical conditions.
Line H. Rude, Elena Groppo, Lene M. Arnbjerg, Dorthe B. Ravnsbæk, Regitze A. Malmkjær, Yaroslav Filinchuk, Marcello Baricco, Flemming Besenbacher, Torben R. Jensen, Journal of Alloys and Compounds 509 (2011) 8299– 8305

HE005 – National Testing Laboratory for Solid-State Hydrogen Storage Technologies

Develop and operate a national-level testing and core reference laboratory aimed at assessing and validating the performance of emerging solid-state hydrogen storage materials and full-scale systems. Establish and validate measurement techniques for hydrogen sorption and related performance metrics.
Michael A. Miller and Richard A. Page FY 2006 Annual Progress Report DOE Hydrogen Program 529-534

HE0049 – Mg-Ni-Cu mixtures for hydrogen storage: A kinetic study

Mg based ternary mixtures containing increasing amounts of Ni and Cu were prepared by ball milling under argon for 16 hours and then activated at high temperature (623K) by charging-discharging cycles at H2 pressures of 50 bar/0.7 bar. The work aims to analyze the influence of the mixture composition on the storage properties (H2 intake and sorption kinetics).
C. Milanese, A. Girella, P. Cofrancesco, G. Bruni, V. Berbenni, P. Matteazzi, A. Marini, Intermetallics 18 (2010) 203-211

HE0048 – Effect of C (graphite) doping on the H2 sorption performances of the Mg-Ni storage system

The purpose of the study was to evaluate the effect of C addition on the reactivity, the sorption activation and the sorption performances of the Mg-Ni system.
C. Milanese, A. Girella, S. Garroni, G. Bruni, V. Berbenni, P. Matteazzi, A. Marini, International journal of hydrogen energy 35 (2010) 1285-1295

HE0047 – Synergetic effect of C (graphite) and Nb2O5 on the H2 sorption properties of the Mg-MgH2 system

Ternary Mg-Nb2O5-graphitic C mixtures were prepared by high energy ball milling under Ar for different times and charcaterized especially by the calorimetric technique.The aims of the work are to assess the effect of the simultaneous presence of the two dopants on the reactivity and the sorption properties of the Mg-MgH2 system, to study the influence of the milling time on the performances of the mixtures.
C. Milanese, A. Girella, S. Garroni, G. Bruni, V. Berbenni, P. Matteazzi, A. Marini, International journal of hydrogen energy 35 (2010) 9027-9037

HE0046 – A Reversible Nanoconfined Chemical Reaction

Hydrogen is recognized as a potential, extremely interesting energy carrier system, which can facilitate efficient utilization of unevenly distributed renewable energy. A major challenge in a future “hydrogen economy” is the development of a safe, compact, robust, and efficient means of hydrogen storage, in particular, for mobile applications. Here we report on a new concept for hydrogen storage using nanoconfined reversible chemical reactions. LiBH4 and MgH2 nanoparticles are embedded in a nanoporous carbon aerogel scaffold with pore size Dmax 21 nm and react during release of hydrogen and form MgB2. The hydrogen desorption kinetics is significantly improved compared to bulk conditions, and the nanoconfined system has a high degree of reversibility and stability and possibly also improved thermodynamic properties. This new scheme of nanoconfined chemistry may have a wide range of interesting applications in the future, for example, within the merging area of chemical storage of renewable energy.
Thomas K. Nielsen, Ulrike Bösenberg, Rapee Gosalawit, Martin Dornheim, Yngve Cerenius, Flemming Besenbacher, Torben R. Jensen, ACS Nano, Vol. 4, N° 7, 3903–3908 (2010)

HE0045 – Confinement of MgH2 Nanoclusters within Nanoporous Aerogel Scaffold Materials

Nanoparticles of magnesium hydride were embedded in nanoporous carbon aerogel scaffold materials in order to explore the kinetic properties of hydrogen uptake and release. A new modified procedure for the synthesis of magnesium hydride nanoparticles is presented. The procedure makes use of monoliths ( 0.4 cm3) of two distinct types of nanoporous resorcinol formaldehyde carbon aerogels loaded with dibutylmagnesium, MgBu2. Excess MgBu2 was removed mechanically, and the increase in mass was used as a measure of the amount of embedded MgH2. Energy-dispersive spectrometry revealed that MgH2 was uniformly distributed within the aerogel material. In situ synchrotron radiation powder X-ray diffraction showed that MgBu2 transformed directly to MgH2 at T 137 °C and p(H2) 50 bar. Two distinct aerogel samples, denoted X1 and X2, with pore volumes of 1.27 and 0.65 mL/g and average pore sizes of 22 and 7 nm, respectively, were selected. In these samples, the uptake of magnesium hydride was found to be proportional to the pore volume, and aerogels X1 and X2 incorporated 18.2 and 10.0 wt % of MgH2, respectively. For the two samples, the volumetric MgH2 uptake was similar, 12 vol %. The hydrogen storage properties of nanoconfined MgH2 were studied by Sieverts’ measurements and thermal desorption spectroscopy, which clearly demonstrated that the dehydrogenation kinetics of the confined hydride depends on the pore size distribution of the scaffold material; that is, smaller pores mediated faster desorption rates possibly due to a size reduction of the confined magnesium hydride.
Thomas K. Nielsen, Kandavel Manickam, Michael Hirscher, Flemming Besenbacher, Torben R. Jensen, ACS Nano, Vol. 3, N°. 11, 3521–3528 (2009)

HE0044 – Improved Hydrogen Storage Kinetics of Nanoconfined NaAlH4 Catalyzed with TiCl3 Nanoparticles

Nanoparticles of NaAlH4 have been infiltrated in nanoporous carbon aerogel with TiCl3 nanoparticles in order to explore possible synergetic effects between nanoconfinement and a functionalized catalytic scaffold. Resorcinol formaldehyde carbon aerogels with an average pore size of 17 nm and total pore volume of 1.26 mL/g were infiltrated with TiCl3 to obtain an aerogel doped with 3.0 wt %TiCl3 nanoparticles. NaAlH4 was melt-infiltrated into the functionalized carbon aerogel at 189 C and p(H2) ? 186 199 bar. Energy-dispersive spectrometry (EDS) combined with focused ion beam (FIB) techniques revealed the presence of Na, Al, Ti, and Cl inside the aerogel scaffold material. The infiltrated NaAlH4 was X-ray amorphous, whereas 27Al magic-angle spinning (MAS) NMR spectroscopy confirmed the presence of nanoconfined NaAlH4. Temperature-programmed desorption mass spectroscopy (TPD-MS) and Sieverts' measurements demonstrated significantly improved hydrogen desorption kinetics for this new nanoconfined NaAlH4 TiCl3 material as compared to nanoconfined NaAlH4 without the catalysts TiCl3 and to bulk ball-milled samples of NaAlH4 TiCl3. We find that the onset temperature for hydrogen release was close to room temperature (Tonset = 33 C), and the hydrogen release rate reached a maximum value at 125 C, which demonstrates favorable synergetic effects between nanoconfinement and catalyst addition.
Thomas K. Nielsen, Marek Polanski, Dariusz Zasada, Payam Javadian, Flemming Besenbacher, Jerzy Bystrzycki, Jørgen Skibsted, Torben R. Jensen, ACS Nano

HE0043 – Processing analysis of the ternary LiNH2–MgH2–LiBH4 system for hydrogen storage

In this article, we investigate the ternary LiNH2–MgH2–LiBH4 hydrogen storage system by adopting various processing reaction pathways. The stoichiometric ratio of LiNH2:MgH2:- LiBH4 is kept constant with a 2:1:1 molar ratio. All samples are prepared using solid-state mechano-chemical synthesis with a constant rotational speed, but with varying milling duration. Furthermore, the order of addition of parent compounds as well as the crystallite size of MgH2 are varied before milling. All samples are intimate mixtures of Li–B–N–H quaternary hydride phase with MgH2, as evidenced by XRD and FTIR measurements. It is found that the samples with MgH2 crystallite sizes of approximately 10 nm exhibit lower initial hydrogen release at a temperature of 150 C. Furthermore, it is observed that the crystallite size of Li–B–N–H has a significant effect on the amount of hydrogen release with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160 C and the other around 300 C. The main hydrogen release temperature is reduced from 310 C to 270 C, while hydrogen is first reversibly released at temperatures as low as 150 C with a total hydrogen capacity of w6 wt.%. Detailed thermal, capacity, structural and microstructural properties are discussed and correlated with the activation energies of these materials.
Michael U. Niemann, Sesha S. Srinivasan, Ashok Kumar, Elias K. Stefanakos, D. Yogi Goswami, Kimberly McGrath, International Journal of hydrogen energy, xxx (2009) 1-8

HE0042 – Novel catalytic effects of fullerene for LiBH4 hydrogen uptake and release

The addition of catalysts to complex hydrides is aimed at enhancing the hydrogen absorption desorption properties. Here we show that the addition of carbon nanostructure C60 to LiBH4 has a remarkable catalytic effect, enhancing the uptake and release of hydrogen. A fullerene–LiBH4 composite demonstrates catalytic properties with not only lowered hydrogen desorption temperatures but also regenerative rehydrogenation at a relatively low temperature of 350 ?C. This catalytic effect probably originates from C60 interfering with the charge transfer from Li to the BH4 moiety, resulting in a minimized ionic bond between Li+ and BH4 , and a weakened covalent bond between B and H. Interaction of LiBH4 with an electronegative substrate such as carbon fullerene affects the ability of Li to donate its charge to BH4, consequently weakening the B–H bond and causing hydrogen to desorb at lower temperatures as well as facilitating the absorption of H2. Degradation of cycling capacity is observed and is probably due to the formation of diboranes or other irreversible intermediates
Matthew S. Wellons, Polly A Berseth, Ragaiy Zidan, Nanotechnology 20 (2009) 204022

HE0041 – The Investigation of MgH2and LiBH4Mixtures Potential for Hydrogen Storage

MgH2has been examined as a potential hydrogen storage due to its high gravimetric capacity of 7.6 wt.%; however, its kinetics is slow. LiBH4has even higher capacity, 13.9 wt.% when it decomposes to LiH; unfortunately, this reaction requires high temperature exceeding 400oC. ?Destabilization of LiBH4with MgH2[1] and also of MgH2with LiBH4[2], have been reported. Vajo et al. [1] reported thermodynamic improvement of the hydrogen storage performance of MgH2destabilized with LiBH4; however, no kinetic improvement was observed. The reaction pathway through Mg and then MgB2corresponding to a two-step desorption was suggested. The MgB2formation was believed to improve the reversibility [3]. Johnson et al. [2] reported kinetic improvement of the hydrogen storage performance of LiBH4destabilized withMgH2. The presence of Li+in the crystal structure was suggested to be the reason for this enhancement. However, evidence of thermodynamic enhancement from LiBH4addition was not observed. ?We have examined if there is a “eutectic” molar ratio existing between MgH2and LiBH4that may improve both kinetic and thermodynamic hydrogen storage performances. We have found that a 3:1 mole ratio of MgH2and LiBH4mixture has the fastest desorption rate and highest hydrogen desorption capacity. The 3:1 mixture was doped with TiCl3and the result shows good reversibility and cycle stability.
Uncharat Setthanan, G. Sean McGrady, Poster

HE0040 – Ammine Magnesium Borohydride Complex as a New Material for Hydrogen Storage: Structure and Properties of Mg(BH4)2·2NH

The ammonia complex of magnesium borohydride Mg(BH4)2 · 2NH3 (I), which contains 16.0 wt % hydrogen, is a potentially promising material for hydrogen storage. This complex was synthesized by thermal decomposition of a hexaaammine complex Mg(BH4)2 · 6NH3 (II), which crystallizes in the cubic space group Fm¯3m with unit cell parameter a ) 10.82(1) Å and is isostructural to Mg(NH3)6Cl2. We solved the structure of I that crystallizes in the orthorhombic space group Pcab with unit cell parameters a ) 17.4872(4) Å, b ) 9.4132(2) Å, c ) 8.7304(2) Å, and Z ) 8. This structure is built from individual pseudotetrahedral molecules Mg(BH4)2 · 2NH3 containing one bidentate BH4 group and one tridentate BH4 group that pack into a layered crystal structure mediated by N-H· · ·H-B dihydrogen bonds. Complex I decomposes endothermically starting at 150 °C, with a maximum hydrogen release rate at 205 °C, which makes it competitive with ammonia borane BH3NH3 as a hydrogen storage material.
Grigorii Soloveichik, Jae-Hyuk Her, Peter W. Stephens, Yan Gao, Job Rijssenbeek, Matt Andrus, and J.-C. Zhao, Inorg. Chem., 2008, 47 (10), 4290-4298

HE004 – Dependence of dissociation pressure upon doping level of Ti-doped sodium alanate—a possibility for ‘‘thermodynamic tailoring’’ of the system

Pressure–concentration isotherms have been recorded for NaAlH4 with different doping levels of titanium. It is well known that titanium accelerates the hydrogenation and dehydrogenation reactions in this system. Our studies have shown that the titanium doping also significantly alters the thermodynamics of the system, which is demonstrated by the change of the dissociation pressure with doping level. This can be explained by changes in the systems energy by dilution of the TiAl-alloy present after doping: Such an alloy forms as a result of the doping reaction. Aluminum generated during the dehydrogenation reaction dilutes this alloy, which gives an additional contribution to the free energy of the system.
Guido Streukens, Borislav Bogdanovic, Michael Felderhoff and Ferdi Schüth, Phys. Chem. Chem. Phys., 2006, 8, 2889–2892

HE0039 – Room temperature reversible hydrogen storage in polyaniline (PANI) nanofibers

We report for the first time the reversible hydrogen storage behavior at room temperature in polyaniline nanofibers. The rate of hydrogen sorption during the initial run was very rapid and an extended plateau pressure of about 30 bars was obtained from the pressure-composition isotherm profiles of these polyaniline nanofibers. The reversible cycling capacity of ~3-4 wt.% was demonstrated at room temperature and have been attributed due their unique microstructural and surface properties
Michael U. Jurczyk, Sesha S. Srinivasan, Ayala R. Phani, Ashok Kumar, D. Yogi Goswami, Elias K. Stefanakos

HE0038 – High-surface area biocarbons for reversible on-board storage of natural gas and hydrogen

An overview is given of the development of advanced nanoporous carbons as storage materials for natural gas (methane) and molecular hydrogen in on-board fuel tankss for next generation clean automobiles.
Peter Pfeiffer and al, Mater. Res. Soc. Symp. Proc. Vol. 1041 © 2008 Materials Research Society

HE0037 – Hydrogen Storage Properties of Ternary Nitrides Prepared by Mechanochemical Milling

Lithium nitride reacts with many elements or binary nitrides to form ternary nitrides. Synthesis procedures for ternary nitrides often involve solid-state reactions that require high temperatures. In the current work we prepare, for the first time, ternary nitrides based on both Li and Group 13 elements by mechanochemical milling of Li3N and the Group 13 nitrides – BN, AlN and GaN. The ternary nitrides obtained are not the known Li3XN2 systems and we have tentatively designated them as Li–X–N (where X = B, Al or Ga). We report here an investigation of the hydrogen absorption–desorption behaviour of the Li–X–N ternary nitrides.
Henrietta W. Langmi, G. Sean McGrady, Poster

HE0036 – Mixed–Metal Li3N–Based Systems for Hydrogen Storage: Li3AlN2 and Li3FeN2

The concept of destabilization has been employed by several groups working in the area of hydrogen storage by metal hydrides to identify and pursue systems with lower H2 desorption temperatures.
Henrietta W. Langmit, Scott D. Culligan and G. Sean McGrady, Poster

HE0035 – Sorption properties of NaBH4/MH2 (M[Mg, Ti) powder systems

The sorption properties of NaBH4/MH2 (M ¼ Mg, Ti) powder systems prepared by highenergy ball milling have been thoroughly investigated. Concerning the systems containing MgH2, the 2:1 and 1:2 molar compositions have been studied and both lead to a multistep desorption pathway, where the formation of MgB2 confirms the destabilization of NaBH4 induced by the presence of MgH2. A noticeable kinetic enhancement is achieved for the MgH2-rich system (composition 1:2) if compared with the NaBH4-rich system (composition 2:1). Even though full re-absorption is obtained for neither of the two compositions, fast kinetics is achieved. During absorption, the unsuspected formation of the perovskite-type hydride NaMgH3 is detected and it is showed that this ternary phase contributes to reduce the gravimetric capacity of the systems. Conversely, in the 2NaBH4/ TiH2 system, there is no formation of the intermetallic compound TiB2. Furthermore, a decrease in the sorption kinetics is found in comparison with the systems based on MgH2
S. Garroni, C. Milanese, A. Girella, A. Marini, G. Mulas, E. Menendez, C. Pistidda, M. Dornheim, S. Surinach, M.D. Baro, International journal of hydrogen energy 35 (2010) 5434-5441

HE0034 – Effect of C (graphite) doping on the H2 sorption performance of the Mg–Ni storage system

Binary Mg–Ni mixtures and ternary Mg–Ni–C (graphite) samples with fixed proportions of metals (Mg 85%–Ni 15% by weight) and amount of C increasing in increments of 5 wt % from 5 wt % to 15 wt % were prepared by high energy ball milling (BM) in Ar for tBM ¼2 h. The purpose of the study was to evaluate the effect of C addition on the reactivity, the sorption activation and the storage performance of the Mg–Ni system. Increasing the amount of C had the effect of decreasing (from 10 to 3) the number of cycles needed for activation (performed at 623 K and 40 bar/0.9 bar charging/discharging H2 pressure). After full activation, the 5 wt % C-containing sample exhibited the best absorption kinetics performance: the average rate to charge up to 5 wt % H2 was about 3 times higher than that observed for the undoped sample. Unfortunately, increasing the amount of C had a negative impact on the desorption behaviour, causing an increase in the dehydrogenation activation energy and a decrease in the discharging rates. Within the present study, C reacted neither with H2 nor with the H2 active phases (the two discharged phases Mg and Mg2Ni and the related hydrides) and consequently did not lead to variation in the sorption enthalpies of the Mg–Ni system. But, its presence did cause a small increase (4 K at 0.9 bar H2) in the minimum desorption temperatures of the hydrides and a consequent minor decrease (0.2 bar) in the equilibrium pressures. The best sorption properties were obtained for the 5 wt % C-sample, that on the whole worked better than the binary mixture.
C. Milanese, A. Girella, S. Garroni, G. Bruni, V. Berbenni, P. Matteazzi, A. Marini, International journal of hydrogen energy xx (2009) 1-11

HE0033 – Thermodynamics of hydrogen adsorption in MOF-177 at low temperatures:measurements and modelling

Hydrogen adsorption measurements and modelling for the Zn-based microporous metal–organic framework (MOF) Zn4O(1,3,5-benzenetribenzoate)2, MOF-177, were performed over the 50–77 K and 0–40 bar ranges. The maximum excess adsorption measured under these conditions varies over about 105–70 mg g?1. An analysis of the isotherms near saturation shows that hydrogen is ultimately adsorbed in an incompressible phase whose density is comparable to that of the bulk liquid. These liquid state properties observed under supercritical conditions reveal a remarkable effect of nanoscale confinement. The entire set of adsorption isotherms can be well described using a micropore filling model. The latter is used, in particular, to determine the absolute amounts adsorbed and the adsorption enthalpy. When expressed in terms of absolute adsorption, the isotherms show considerable hydrogen storage capacities, reaching up to 125 mg g?1 at 50 K and 25 bar. The adsorption enthalpies are calculated as a function of fractional filling and range from 3 to 5 kJ mol?1 in magnitude, in accordance with physisorption. These results are discussed with respect to a similar analysis performed on another Zn-based MOF, Zn4O(1,4-benzenedicarboxylate)3, IRMOF-1, presented recently. It is found that both materials adsorb hydrogen by similar mechanisms.
Eric Poirier and Anne Dailly, Nanotechnology 20 (2009) 204006

HE0032 – Structure and Charge Control in Metal–Organic Frameworks Based on the Tetrahedral Ligand Tetrakis(4-tetrazolylphenyl)methane

Use of the tetrahedral ligand tetrakis(4-tetrazolylphenyl)methane enabled isolation of two three-dimensional metal–organic frameworks featuring 4,6- and 4,8-connected nets related to the structures of garnet and fluorite with the formulae Mn6-(ttpm)3·5DMF·3H2O (1) and Cu-(Cu4Cl)(ttpm)2]2·CuCl2·5DMF·11H2O (2) (H4ttpm=tetrakis(4-tetrazolylphenyl) methane). The fluorite-type solid 2 displays an unprecedented post-synthetic transformation in which the negative charge of the framework is reduced by extraction of copper(II) chloride. Desolvation of this compound generates Cu4(ttpm)2·0.7CuCl2 (2d), a microporous material exhibiting a high surface area and significant hydrogen uptake
Mircea Dinca, Anne Dailly and Jeffrey R. Long, Chem. Eur. J. 2008, 14, 10280 – 10285

HE0031 – Ternary nitrides for hydrogen storage: Li–B–N, Li–Al–N and Li–Ga–N systems

This paper reports an investigation of hydrogen storage performance of ternary nitrides based on lithium and the Group 13 elements boron, aluminum and gallium. These were prepared by ball milling Li3N together with the appropriate Group 13 nitride—BN, AlN or GaN. Powder X-ray diffraction of the products revealed that the ternary nitrides obtained are not the known Li3BN2, Li3AlN2 and Li3GaN2 phases. At 260 ?C and 30 bar hydrogen pressure, the Li–Al–N ternary system initially absorbed 3.7wt.% hydrogen, although this is not fully reversible. We observed, for the first time, hydrogen uptake by a pristine ternary nitride of Li and Al synthesized from the binary nitrides of the metals. While the Li–Ga–N ternary system also stored a significant amount of hydrogen, the storage capacity for the Li–B–N system was near zero. The hydrogenation reaction is believed to be similar to that of Li3N, and the enthalpies of hydrogen absorption for Li–Al–N and Li–Ga–N provide evidence that AlN and GaN, as well as the ball milling process, play a significant role in altering the thermodynamics of Li3N.
Henrietta W. Langmi, G. Sean McGrady, Journal of Alloys and Compounds 466 (2008) 287–292

HE0030 – Hydrogen storage properties of Pd nanoparticle/carbon template composites

Theoretical studies predict improved hydrogenation properties for hybrid carbon/metal composites. The hydrogen storage capacity of ordered porous carbon containing Pd clusters was measured. The C/Pd composite was obtained by chemical impregnation of an ordered porous carbon template (CT) with a H2PdCl4 solution followed by a reduction treatment. 10 wt.% of palladium clusters were introduced in the carbon porosity; the Pd clusters (2 nm in size) being homogeneously distributed. Thermodynamic hydrogenation properties of both Pd-free CT and the Pd–10 wt.% CT composite have been determined by hydrogen isotherm sorption measurements and thermal desorption spectroscopy (TDS) analysis. The introduction of the palladium into the carbon matrix does not increase the hydrogen storage capacity at 77 K and 1.6 MPa, since here the hydrogen uptake is being attributed to physisorption on the carbon. However, at room temperature and moderate pressure (0.5 MPa), the filling of the CT with 10 wt.% nanocrystalline Pd results in an hydrogen uptake eight times larger than that of the Pd-free CT. After the second cycle, a good reversibility is observed. TDS measurements confirm that the sharp increase of the hydrogen uptake is due to the presence of the Pd clusters in the carbon porosity
R. Campesia, F. Cuevas, R. Gadiou, E. Leroy, M. Hirscher, C. Vix-Guterl, M. Latroche, Carbon 46 (2008 ) 206 –214

HE003 – Independent verification of the saturation hydrogen uptake in MOF-177 and establishment of a benchmark for hydrogen adsorption in metal–organic frameworks

Hydrogen isotherms for MOF-177, Zn4O(1,3,5-benzenetribenzoate)2, crystals were independently measured by volumetric and gravimetric methods at 77 K to confirm its hydrogen uptake capacity and to establish the importance of calibrating gas adsorption instrumentation prior to evaluating H2 storage capacities. Reproducibility of hydrogen adsorption experiments is important because non-systematic errors in measurements can easily occur leading to erroneous reports of capacities. The surface excess weight percentage of hydrogen uptake in MOF-177 samples is 7.5 wt% at 70 bar, which corresponds to an absolute adsorbed amount of 11 wt%. These values are in agreement with our previous report and with those found independently by Southwest Research Institute. Considering its well-known structure and its significant H2 uptake properties, we believe MOF-177 is an excellent material to serve as a benchmark adsorber.
Hiroyasu Furukawa, Michael A. Miller and Omar M. Yaghi J. Mater. Chem., 2007, 17, 3197–3204

HE0029 – H2 sorption performance of NaBH4–MgH2 composites prepared by mechanical activation

The current research on solid state hydrogen storage materials for on-board applications is focused on reactive hydrides composites (RHC), i.e. systems based on the improvement of the dehydrogenation thermodynamic of a complex hydride when one (generally the light hydride MgH2) or more hydrides take part to the reaction. The extent of the destabilization, as well as the sorption characteristics of the composites, strongly depends on the structural and nanostructural properties of the constituent hydrides, which are in turn affected by the preparation route. The aim of this work is to evaluate the influence of different mechanical activation conditions on the storage properties of NaBH4 – MgH2 composites, up to now scarcely explored in literature. The first results regard composites with 2:1 and 1:2 stoichiometry milled under different atmosphere (Ar or H2). X-ray powders diffraction analysis shows that milling does not lead to the formation of any new phase, but it reduces the average crystallite size of the powders down to nanometric scale. All the mixtures release an H2 amount close to the theoretical value expected for the full dissociation of both the hydrides and much higher than the target fixed by the US Department of Energy for on-board application. The thermal programmed desorption profiles of the mixtures clearly show two steps, with MgH2 dissociating first and with higher rate and NaBH4 gradually dehydrogenating at temperatures close to 400°C. Concerning the 2:1 stoichiometry, when the samples are processed under Ar the two dehydrogenation processes are characterized by a lower starting temperature but also by a lower average rate with respect to the sample milled in H2. The 1:2 sample milled under Ar shows the best kinetic performance. Unfortunately, also for this mixture more than 10 h are required to obtain full desorption at a temperature as high as 450°C.
C. Milanese, A. Girella, G. Mulas, S. Enzo, S. Medici, S. Garroni, M. D. Barò, S. Suriñach & A. Marini, Ecosystems and Sustainable Development VII 389

HE0028 – Mg–Ni–Cu mixtures for hydrogen storage: A kinetic study

Mg-based ternary mixtures (40 Mg wt% 80) containing increasing amount (up to 30 wt %) of Ni and Cu were prepared by ball milling (BM) under Ar for 16 h and subsequently activated at high temperature (623 K) by charging/discharging cycles at H2 pressure of 50 bar/0.7 bar. The work aims to analyze the influence of the mixtures’ composition on the storage properties (H2 intake and sorption kinetics) and to describe the role played by an ad-hoc activation in reaching these same properties. The storage capacity of the mixtures decreases by decreasing the Mg starting content, the H2 active phases being ‘‘free Mg’’ and the ‘‘bonded Mg’’ intermetallic compounds Mg2Ni and Mg2Cu. After full activation (3 charging/ discharging runs), ‘‘free Mg’’ hydrogenates 10 times quicker than the ‘‘bonded Mg phases’’, while the discharging of both ‘‘free’’ and ‘‘bonded’’ Mg hydrides takes place simultaneously with similar kinetics. The best kinetic performance is shown by the samples with Mg ¼ 60 wt% and 70 wt% and the highest Ni content (30% and 20% respectively), with sorption rates up to 7 times higher than those of the pure Mg/ MgH2 system. Ó
C. Milanese, A. Girella, G. Bruni, P. Cofrancesco, V. Berbenni, P. Matteazzi, A. Marini, Intermetallics xxx (2009) 1–9

HE0027 – Synthesis of carbon nanotube–TiO2 nanotubular material for reversible hydrogen storage

A material consisting of multi-walled carbon nanotubes (MWCNTs) and larger titania (TiO2) nanotube arrays has been produced and found to be efficient for reversible hydrogen (H2) storage. The TiO2 nanotube arrays (diameter ?60 nm and length ?2–3 ?m) are grown on a Ti substrate, and MWCNTs a few ?m in length and ?30–60 nm in diameter are grown inside these TiO2 nanotubes using chemical vapor deposition with cobalt as a catalyst. The resulting material has been used in H2 storage experiments based on a volumetric method using the pressure, composition, and temperature relationship of the storage media. This material can store up to 2.5 wt% of H2 at 77 K under 25 bar with more than 90% reversibility.
Amrita Mishra, Subarna Banerjee, Susanta K Mohapatra, Olivia A Graeve and Mano Misra, Nanotechnology 19 (2008) 445607

HE0026 – Effect of the substrate on the thermodynamic properties of PdHx films studied by hydrogenography

We investigated the influence of the substrate on the thermodynamic properties of metal hydride thin films by hydrogenography, using PdHx as a model system. After appropriate hydrogen cycling, reproducible hydrogenation properties are found at the same equilibrium pressure for all substrates studied. Comparing these thin films with free-standing films—measured both by hydrogenography and by Sievert’s method—we find a very similar behavior. Hence, thin films can be used to study the hydrogenation behavior of the corresponding bulk materials.
Y. Pivak, R. Gremaud, K. Gross, M. Gonzalez-Silveira, A. Walton, D. Book,H. Schreuders, B. Dama and R. Griessen, Scripta Materialia xxx (2008) xxx–xxx

HE0025 – Reactivity and hydrogen storage performances of magnesium–nickel–copper ternary mixtures prepared by reactive mechanical grinding

Ternary Mg-based mixtures (50 Mg weight% 80) containing increasing amount of Ni (up to 30 wt%) and Cu (up to 20 wt%) have been prepared by ball milling in hydrogen reactive atmosphere ðPH2 ¼ 5 barÞ to determine the effects of both the processing conditions and the concurrent presence of the two transition metals on the sorption mechanisms and the storage properties of the Mg/MgH2 system. Combined SEM, TG and XRPD analyses showed that the processing time tBM (¼3 h, 8 h and 16 h) strongly affects the properties of the ‘‘as milled powders’’ (average particle sizes and microstructure, nature of the phases, amount of hydrogen absorbed upon milling, and desorption characteristics). However, after a combined high temperature/high pressure activation cycle, all the charged samples were composed of MgH2, Mg2NiH4 and MgCu2 while the discharged samples contained ‘‘free Mg’’ and the intermetallic compounds Mg2Ni and Mg2Cu (‘‘bonded Mg’’): in all cases the definitive storage performances are related only on the relative amounts of these three phases that, in turn, depend on the starting composition of the mixtures. Both Ni- and Cu-containing phases hydrogenated/dehydrogenated according to their own sorption reaction schemes; however, Mg2NiH4 and MgCu2 destabilized each other, with the beneficial effect of rising the desorption plateau pressures of the ‘‘bonded Mg’’ with respect to binary Mg–Ni and Mg–Cu mixtures. On the contrary, Ni- and Cu-containing phases did not exert any appreciable destabilizing effect towards ‘‘free MgH2’’.
C. Milanese, A. Girella, G. Bruni, P. Cofrancesco, V. Berbenni, M. Villa, P. Matteazzi, A. Marini , International Journal of Hydrogen Energy 33 (2008) 4593-4606

HE0024 – Hydrogen storage properties of 2LiNH2 + LiBH4 +MgH2

We have investigated the ternary mixture of complex hydrides with stoichiometry 2LiNH2 + LiBH4 +MgH2, and have identified a set of novel hydrogen storage reactions. One of these reactions involves the known reversible reaction Mg(NH2)2 + 2LiH?Li2Mg(NH)2 +2H2. Previous studies have shown that initiating this reaction from the binary mixture 2LiNH2 +MgH2 results in poor hydrogen desorption kinetics and a small amount of NH3 release. In contrast to this behavior, here we demonstrate that by starting from the ternary mixture 2LiNH2 + LiBH4 +MgH2, the above reaction can proceed at lower temperatures and with improved kinetics, while maintaining reversibility. The advantage of starting with the ternary mixture can be traced to the subsequent formation, melting, and reaction of Li4BH4(NH2)3 with MgH2 to form the mixed imide phase Li2Mg(NH)2, which acts as a seed for the reversible reaction, and is at least partly responsible for the improved kinetic response
Jun Yang, Andrea Sudik, Donald J. Siegel, Devin Halliday, Andy Drews, Roscoe O. Carter III, Christopher Wolverton, Gregory J. Lewis, J.W.A. Sachtler, John J. Low, Syed A. Faheem, David A. Lesch, Vidvuds Ozolins, Journal of Alloys and Compounds 446–447 (2007) 345–349

HE0023 – Activation of hydrogen storage materials in the Li–Mg–N–H system:Effect on storage properties

We investigate the thermodynamics, kinetics, and capacity of the hydrogen storage reaction: Li2Mg(NH)2 +2H2?Mg(NH2)2 + 2LiH. Starting with LiNH2 and MgH2, two distinct procedures have been previously proposed for activating samples to induce the reversible storage reaction. We clarify here the impact of these two activation procedures on the resulting capacity for the Li–Mg–N–H reaction. Additionally, we measure the temperature-dependent kinetic absorption data for this hydrogen storage system. Finally, our experiments confirm the previously reported formation enthalpy ( H), hydrogen capacity, and pressure–composition–isotherm (PCI) data, and suggest that this system represents a kinetically (but not thermodynamically) limited system for vehicular on-board storage applications.
Jun Yang, Andrea Sudik, C. Wolverton, Journal of Alloys and Compounds 430 (2007) 334–338

HE0022 – Nanocatalyst doping of Zn(BH4)2 for on-board hydrogen storage

In this work, we report the synthesis and characterization of Zn(BH4)2, a new class of complex borohydrides for on-board hydrogen storage. The thermal decomposition of Zn(BH4)2 comprises of not only the evolution of H2, but also an appreciable amount of B–H (borane) compounds. Lowering the decomposition temperature by catalytic doping may lead to negligible release of boranes. An amount of 1.5 mol% nanoNi was estimated and found to be the optimum concentration for nanocatalyst doping of Zn(BH4)2. Significance of the nanoNi doping, lowers the melting and thermal decomposition temperatures (at least 20–40 ?C) of Zn(BH4)2 as evidenced from the calorimetric analysis. At these low temperatures, the nanocatalyzed Zn(BH4)2 exhibits reduction in the amount of borane gases released by a factor of 20 as compared to the undoped sample
Sesha Srinivasan, Diego Escobar, Michael Jurczyk, Yogi Goswami, Elias Stefanakos, Journal of Alloys and Compounds 462 (2008) 294–302

HE0021 – Hydrogen Storage in a Microporous Metal-Organic Framework with Exposed Mn2+ Coordination Sites

Use of the tritopic bridging ligand 1,3,5-benzenetristetrazolate (BTT3-) enables formation of [Mn- (DMF)6]3[(Mn4Cl)3(BTT)8(H2O)12]2â42DMFâ11H2Oâ20CH3OH, featuring a porous metal-organic framework with a previously unknown cubic topology. Crystals of the compound remain intact upon desolvation and show a total H2 uptake of 6.9 wt % at 77 K and 90 bar, which at 60 g H2/L provides a storage density 85% of that of liquid hydrogen. The material exhibits a maximum isosteric heat of adsorption of 10.1 kJ/mol, the highest yet observed for a metal-organic framework. Neutron powder diffraction data demonstrate that this is directly related to H2 binding at coordinatively unsaturated Mn2+ centers within the framework.
Mircea Dinca ,Anne Dailly, Yun Liu, Craig M. Brown, Dan. A. Neumann and Jeffrey R. Long, J. AM. CHEM. SOC. 2006, 128, 16876-16883

HE0020 – An overview of advanced materials for hydrogen storage

In a future sustainable energy system based on renewable energy, environmentally harmless energy carriers like hydrogen will be of crucial importance. One of the major impediments for the transition to a hydrogen-based energy system is the lack of satisfactory hydrogen storage alternatives. In the last years, the possible to store hydrogen in various materials was extensively studied. This paper is a preliminary study with the focus on advanced nanostructured materials such as solids of large surface area based on carbon structures, metals and different types of metal alloys, other intermetallic compounds, etc. as possibilities for hydrogen storage. The newest materials used for hydrogen storage are light metal alloys. We have so far focused in this review almost exclusively on experimental studies. Also there are presented the most important characteristics of these materials such as mechanical strength, porosity and affinity to hydrogen, and also the recent developments in the search for innovative materials with high hydrogen-storage capacity and our contribution in this field.
Michael A. Miller and Richard A. Page FY 2006 Annual Progress Report DOE Hydrogen Program 529-534

HE002 – Thermodynamische und katalytische Eigenschaften von Titan- und Cer-dotierten komplexen Aluminiumhydriden

x
Thesis of Guido Streukens Fakultät für Chemie der Ruhr Universität Bochum Germany 2007

HE0019 – In situ synthesis and hydrogen storage properties of PdNi alloy nanoparticles in an ordered mesoporous carbon template

Organized mesoporous carbon has been used as a nanoreactor to prepare PdNi metallic particles using an incipient wetness method starting from Pd and Ni salts. The final composite material consists of nanosized metallic particles of an alloy with composition Pd0.60Ni0.40 highly dispersed within the carbon host structure. The thermodynamic hydrogenation properties of both the PdNi-free OMC and the Pd0.60Ni0.40- OMC composite have been determined by hydrogen isotherm sorption measurements. The introduction of the palladium–nickel alloy into the carbon matrix does not increase the hydrogen storage capacity at 77 K and 2 MPa, since the hydrogen uptake is mainly attributed to physisorption on the carbon surface. However, at room temperature and moderate pressure (0.5 MPa), the filling of the OMC with nanocrystalline Pd0.60Ni0.40 results in larger hydrogen uptake than that of the PdNi-free OMC.
R. Campesi, F. Cuevas, R. Gadiou, E. Leroy, M. Hirscher, C. Vix-Guterl, M. Latroche, Microporous and Mesoporous Materials 117 (2009) 511–514

HE0018 – Hydrogen storage properties of Pd nanoparticle/carbon template composites

Theoretical studies predict improved hydrogenation properties for hybrid carbon/metal composites. The hydrogen storage capacity of ordered porous carbon containing Pd clusters was measured. The C/Pd composite was obtained by chemical impregnation of an ordered porous carbon template (CT) with a H2PdCl4 solution followed by a reduction treatment. 10 wt.% of palladium clusters were introduced in the carbon porosity; the Pd clusters (2 nm in size) being homogeneously distributed. Thermodynamic hydrogenation properties of both Pd-free CT and the Pd–10 wt.% CT composite have been determined by hydrogen isotherm sorption measurements and thermal desorption spectroscopy (TDS) analysis. The introduction of the palladium into the carbon matrix does not increase the hydrogen storage capacity at 77 K and 1.6 MPa, since here the hydrogen uptake is being attributed to physisorption on the carbon. However, at room temperature and moderate pressure (0.5 MPa), the filling of the CT with 10 wt.% nanocrystalline Pd results in an hydrogen uptake eight times larger than that of the Pd-free CT. After the second cycle, a good reversibility is observed. TDS measurements confirm that the sharp increase of the hydrogen uptake is due to the presence of the Pd clusters in the carbon porosity.
R. Campesi, F. Cuevas, R. Gadiou, E. Leroy, M. Hirscher, C. Vix-Guterl, M. Latroche, Carbon 46 (2008) 206-214

HE0017 – Novel Sieverts’ type volumetric measurements of hydrogen storage properties for very small sample quantities

Novel volumetric analysis instrument for studying hydrogen storage property of very small quantities (?mg) of samples was developed and tested. Small pressure change arising from hydrogen uptake or release are precisely measured and equated to the change in the sample’s hydrogen content using the gas lawequation.Very small volume pressure reservoir enables these precise measurements, and all internal volumes are calibrated with high-purity helium gas. Capacity, equilibrium isotherm, and kinetic measurements can be performed in the pressure range of vacuum to 4MPa and the temperature range from cryogenic-673 K. Test measurements were made on small carbon nanotube samples and measurement of less than ?3 g of hydrogen uptake was demonstrated, which corresponds to an accuracy of better than 0.15 wt% for a 2 mg sample.
Yong-Won Lee, Bruce M. Clemens, Karl J. Gross, Journal of Alloys and Compounds 452 (2008) 410–413

HE0016 – Heat of adsorption for hydrogen in microporous high-surface-area materials

The automated Sieverts PCTPro2000 was used with a so-called Microdoser (MD) from HyEnergy, USA. This Microdoser offers the possibility to measure the hydrogen uptake of very small amounts of material. Therefore the MD includes a 0.51 ml reservoir, a pressure sensor and minimizes the sample cell volume to 1.2ml. The sample mass was between 99 mg and 400 mg and the samples have been activated in high vacuum according to table 1. Adsorption isotherms (0-20 bar) were measured at liquid nitrogen, liquid argon and temperatures above 87 K. Latter is realized by heating the sample cell in a dewar cooled by liquid nitrogen. The temperature was controlled to +/- 1 K.
B. Schmitz, U. Müller, N. Trukhan, M. Schubert, G. Férey, M. Hirscher, ChemPhysChem 2008

HE0015 – Heat of Adsorption for Hydrogen in Microporous High-Surface-Area Materials

The heat of adsorption for hydrogen is determined over a wide range of surface coverages for activated carbon and several metal–organic frameworks. Heat determination is based on hydrogen adsorption measurements performed at temperatures between 77 and 296 K (see figure, BTC=benzene-1,3,5-tricarboxylate). The materials with smaller cavities show a higher heat of adsorption for hydrogen.
Barbara Schmitz, Ulrich Müller, Natalia Trukhan,Markus Schubert,Gérard Férey and Michael Hirscher, ChemPhysChem 2008

HE0014 – Improved hydrogen storage properties of a V decorated Mg nanoblade array

An ultra-thin layer of V has been coated onto the surface of individual Mg nanoblades by dynamic shadowing growth. This 2.25 at% V decorated Mg nanoblade array can absorb and desorb hydrogen rapidly at temperatures T 500 K after activation by one hydrogen cycle, with a low hydrogen absorption activation energy of 35.0 ± 1.2 kJ per mol H2 and a desorption activation energy of 65.0 ± 0.3 kJ per mol H2. The improved hydrogen sorption kinetics is attributed to both the catalytic effect of the V coating and the unique nanoblade morphology with a large surface area and small hydrogen diffusion length
Yuping He and Yiping Zhao, Phys. Chem. Chem. Phys., 2009

HE0013 – The formation of MgH2 nanowires during the hydrogenation of Ti-doped Mg film

A unique diffusion barrier structure, consisting of layers of a Ti nanorod array and Ti film, has been fabricated on Si substrate for a subsequent 2 at.% Ti-doped Mg film deposition using a combinational technique of multilayer growth, co-deposition and dynamic shadowing growth. The hydrogenation of the Ti-doped Mg film on such a barrier structure shows that the barrier can prevent direct Mg–Si contact and suppress the formation of Mg2Si alloy in a high-temperature process. When this film has been hydrogenated at temperatures T 300 ?C for approximately 150 h, tetragonal single-crystal MgH2 nanowires are formed on the surface of the Ti-doped Mg film. The hydrogenation time and temperature are the two main factors for the nanowire formation. The doping of Ti also plays a significant role. This result reveals that complicated dynamic processes could occur during the hydrogenation of Ti-doped Mg film when Mg2Si formation can be eliminated by an effective diffusion barrier layer
Yuping He, Yongjun Liu and Yiping Zhao, Nanotechnology 19 (2008) 465602

HE0012 – Hydrogenation of Mg film and Mg nanoblade array on Ti coated Si substrates

The hydrogenation of Mg film and Mg nanoblade array fabricated on Ti coated Si substrates has been studied and compared. The nanoblades start to absorb hydrogen at a temperature between 250 and 300 °C, which is much lower than 350 °C for Mg film. However, the saturated total hydrogen uptake in nanoblades is less than half of that in the film, resulting from MgO formation by air exposure. The nanoblade morphology with large surface area and small hydrogen diffusion length, and the catalytic effect of Ti layer, are two main reasons for the nanoblade hydrogenation behavior.
Yuping He, Yiping Zhao, Liwei Huang, Howard Wang, and Russell J. Composto, APPLIED PHYSICS LETTERS 93, 163114 2008

HE0011 – Ternary nitrides for hydrogen storage: Li–B–N, Li–Al–N and Li–Ga–N systems

This paper reports an investigation of hydrogen storage performance of ternary nitrides based on lithium and the Group 13 elements boron, aluminum and gallium. These were prepared by ball milling Li3N together with the appropriate Group 13 nitride.BN, AlN or GaN. Powder X-ray diffraction of the products revealed that the ternary nitrides obtained are not the known Li3BN2, Li3AlN2 and Li3GaN2 phases. At 260 .C and 30 bar hydrogen pressure, the Li.Al.N ternary system initially absorbed 3.7wt.% hydrogen, although this is not fully reversible. We observed, for the first time, hydrogen uptake by a pristine ternary nitride of Li and Al synthesized from the binary nitrides of the metals. While the Li.Ga.N ternary system also stored a significant amount of hydrogen, the storage capacity for the Li.B.N system was near zero. The hydrogenation reaction is believed to be similar to that of Li3N, and the enthalpies of hydrogen absorption for Li.Al.N and Li.Ga.N provide evidence that AlN and GaN, as well as the ball milling process, play a significant role in altering the thermodynamics of Li3N.
Henrietta W. Langmi, G. Sean McGrady, Journal of Alloys and Compounds 466 (2008) 287–292

HE0010 – Nanoporous Polymers for Hydrogen Storage

The study clearly demonstrates that hypercrosslinked nanoporous polymers with high hydrogen adsorption capacity are good candidates for use in future hydrogen storage systems. The major advantages of nanoporous polymers are light weight, and rapid complete adsorption and desorption with no appreciable hysteresis. Using a variety of well known reaction, these synthetic polymers can be easily modified and their adsorption ability further tuned.
Jonathan Germain, Jean M. J. Fréchet and Frantisek Svec, Polymeric Materials: Science & Engineering 2007, 97, 272

HE001 – Crystal structure determination and reaction pathway of amide–hydride mixtures

Combined synchrotron in situ X-ray diffraction and neutron diffraction studies were performed on 2:1 mixtures of lithium amide and magnesium hydride, which have shown promise as solid-state hydrogen storage materials. The dehydrogenated product is a mixed lithium and magnesium imide, Li2Mg(NH)2, whose crystal structure has not heretofore been determined. Furthermore, at elevated temperatures, Li2Mg(NH)2 undergoes two structural transitions from an orthorhombic structure to a primitive cubic structure at intermediate temperature (350 ?C) followed by a facecentered cubic crystal structure at high temperature (500 ?C). Disordering of the Li, Mg and cation vacancies as a function of temperature drives the structural transitions.We report the reaction pathway from in situ X-ray diffraction studies and the crystal structures of the three structural variants of Li2Mg(NH)2 as determined by high-resolution X-ray and neutron powder diffraction. We also report the hydrogen storage reaction pathways for mixtures with other cation ratios.
Job Rijssenbeek, Yan Gao, Jonathan Hanson, Qingzhen Huang, Camille Jones, Brian Toby Journal of Alloys and Compounds xxx (2007) xxx–xxx

B3313 – Fundamental environmental reactivity testing and analysis of the hydrogen storage material 2LiBH4$MgH2

While the storage of hydrogen for portable and stationary applications is regarded as critical in bringing PEM fuel cells to commercial acceptance, little is known of the environmental exposure risks posed in utilizing condensed phase chemical storage options as in complex hydrides. It is thus important to understand the effect of environmental exposure of metal hydrides in the case of accident scenarios. Simulated tests were performed following the United Nations standards to test for flammability and water reactivity in air for a destabilized lithium borohydride and magnesium hydride system in a 2 to 1 molar ratio respectively. It was determined that the mixture acted similarly to the parent, lithium borohydride, but at slower rate of reaction seen in magnesium hydride. To quantify environmental exposure kinetics, isothermal calorimetry was utilized to measure the enthalpy of reaction as a function of exposure time to dry and humid air, and liquid water. The reaction with liquid water was found to increase the heat flow significantly during exposure compared to exposure in dry or humid air environments. Calorimetric results showed the maximum normalized heat flow of the fully charged material was 6 mW/mg under liquid phase hydrolysis; and 14 mW/mg for the fully discharged material also occurring under liquid phase hydrolysis conditions.
Charles W. James Jr., Kyle S. Brinkman, Joshua R. Gray, Jose A. Cortes-Concepcion, Donald L. Anton, International Journal of Hydrogen Energy (2013) 1-11

B3292 – Crystal structure, polymorphism, and thermal properties of yttrium borohydride Y(BH4)3

Y(BH4)3 was synthesized by cryo-milling mixtures of LiBH4 and YCl3 and characterized by powder X-ray and neutron diffraction (PXD, PND), differential scanning calorimetry (DSC), and temperature programmed desorption (TPD). The crystal structure was refined in the space group Pa?3 (no. 205) with lattice constant a = 10.8522(7) Å from 11B and D (2H) substituted samples using PND. It was found to contain Y3+ cations in a highly distorted octahedral environment formed by six [BD4]? complex anions. Heat treatment under 10 MPa of deuterium at 475 K led to a phase transformation from the primitive cubic room-temperature phase to a face-centered cubic high-temperature phase with space group Fm?3c (no. 226) and lattice constant a = 11.0086(1) Å. This high-temperature phase shows an ideal and undistorted octahedral coordination around the central Y3+ cation. In situ synchrotron radiation powder X-ray diffraction experiments (SR-PXD) show the presence of an intermediate phase during the thermal decomposition of Y(BH4)3 with presumably orthorhombic symmetry, and lattice constants a = 12.170(14) Å, b = 7.670(5) Å, and c = 7.478 (6) Å, in a narrow temperature region between 473 K and 520 K.
Christoph Frommen, Nadir Aliouane, Stefano Deledda, Jon Erling Fonneløp, Hilde Grove, Klaus Lieutenant, Isabel Llamas-Jansa, Sabrina Sartori, Magnus H. Sørby, Bjørn C. Hauback, Journal of Alloys and Compounds 496 (2010) 710–716

B3284 – Hydrogenation behavior of the solid solutions RE4NiMg1-xAlx and RE4-yNiMg1+y with RE = Gd and Y

The solid solutions RE4NiMg1?xAlx (0 < x < 0.9) and RE4?yNiMg1+y (0 < y < 0.5) with RE = Gd and Y were synthesized from the elements in sealed tantalum ampoules in an induction furnace. The limit of solubility was established in both cases. All the samples crystallize with the cubic Gd4RhIn type structure, space group F-43m. The solubility is much lower in the case of Y than for Gd which is linked with steric effects. The hydrogen sorption is irreversible and the large exothermicity of the reaction can lead to the decomposition of the compounds into rare earth hydrides and metallic Ni and Mg. Nevertheless, it is shown that the Y based compounds can absorb almost 3 wt.% of hydrogen at room temperature and under moderate pressure. Furthermore, the solid solutions do not allow destabilization of the hydrides.
Samuel Couillaud, Stefan Linsinger, Cédric Duée, Aline Rougier, Bernard Chevalier, Rainer Pöttgen, Jean-Louis Bobet, Intermetallics 18 (2010) 1115-1121

B3265 – Thermal Decomposition and Spectroscopic Studies of Preheated Ammonia Borane

This paper presents enhanced dehydrogenation of solid ammonia borane (AB, NH3BH3) at 85 °C after it was preheated at 80 °C for 2?4 h. Thermal treatments and subsequent hydrogen release experiments were carried out in a Hastelloy cell mounted on a high-pressure differential scanning calorimeter. With increased preheating durations, not only does the induction period for hydrogen release shorten but also the hydrogen release becomes fast. It is deduced that diammoniate of diborane (DADB, [(NH3)2BH2]+[BH4]?), oligomers or polymers, and AB form a solid solution, shifting the melting temperature of AB to a low value. Hydrogen evolution, as the result of the initial stage of oligomerization, is observed after maintaining pristine AB at 80 °C for 20 min. FTIR-ATR spectra of thermally treated AB indicated that only linear dimers of aminoborane (LDAB, NH3BH2NH2BH3) are detected for preheating periods shorter than 3 h, whereas other oligomers and polymers form for the longer thermal treatment at 80 °C.
Junshe Zhang, Yu Zhao, Daniel L. Akins, Jae W. Lee, J. Phys. Chem. C 2010, 114, 19529–19534

B3206 – Synthesis and hydriding/dehydriding properties of Mg2NieAB (AB [ TiNi or TiFe) nanocomposites

Mg2Ni–TiFe and Mg2Ni–TiNi nanocomposites were prepared by milling for a short time of two preliminary milled to a nanocrystalline state hydrogen absorbing phases, Mg2Ni and TiFe or Mg2Ni and TiNi. The milling results in a sufficient density of contacts between the fine powder particles with different composition. The presence of a large amount of such inter-particles contacts leads to lowering of the initial temperature of the composites gas phase hydriding, as in the same time the temperature range of hydriding is enlarged, compared to the composites components. On the grounds of the proved low temperature hydriding (?200 °C) of the nanocomposites, taking place with appropriate kinetics, the possibility for improved electrochemical hydriding was checked, exploiting the idea for charging Mg2Ni particles through the contacts with TiFe/TiNi. In this way we are supposed to achieve more complete electrochemical hydriding of the Mg2Ni particles, which are usually only superficially hydrogenated at room temperature, mainly due to the low diffusion coefficient of hydrogen in the Mg2Ni crystal lattice and corrosion processes in strong alkaline solutions. The achieved discharge capacity for the Mg2Ni-TiFe composite is essentially higher compared to that of the mechanical mixture of the two composite’s components.
Z. Zlatanova, T. Spassova, G. Eggeler, M. Spassova, International Journal of Hydrogen Energy 36 (2011) 7559-7566

B3203 – The composites of magnesium hydride and iron-titanium intermetallic

Hydride-intermetallic composites MgH2 + X wt.% FeTi (X = 10, 30, 50) were synthesized by Controlled Mechanical Milling (CMM) in a magneto-mill. Their thermal behavior was investigated by Differential Scanning Calorimetry (DSC) and Temperature Programmed Desorption (TPD). It is found that the DSC hydrogen desorption peak temperature as well as the activation energy of hydrogen desorption of the MgH2 constituent in composites decreases linearly with increasing volume fraction of FeTi with a coefficient of fit R2 = 0.98. A doping of the MgH2 + FeTi composites with 5 wt.% of nanometric-size nickel (n-Ni) produced by Vale Inco Ltd. further reduces the DSC hydrogen desorption peak temperature of MgH2 to the temperature range below 300 °C for the MgH2 + 10 and 30 wt.% FeTi composites. The most effective reduction of the DSC hydrogen desorption peak temperature of the MgH2 constituent by as much as 60 °C due to the catalytic effect of n-Ni is observed for the MgH2 + 10 wt.% FeTi + 5 wt.% n-Ni composite. At this composition the composite also has hydrogen capacity slightly higher than 5 wt.%.
Robert A. Varin, Zbigniew Zaranski, Tomasz Czujko, Marek Polanski, Zbigniew S. Wronski, International Journal of Hydrogen Energy 36 (2011) 1177-1183

B3132 – Synthesis and decomposition mechanisms of ternary Mg2CoH5 studied using in situ synchrotron X-ray diffraction

A ternary Mg2CoH5 hydride was synthesized using a novel method that relies on a relatively short mechanical milling time (1 h) of a 2:1 MgH2-Co powder mixture followed by sintering at a sufficiently high hydrogen pressure (>85 bar) and heating from RT to 500 °C. The ternary hydride forms in less than 2.5 h (including the milling time) with a yield of ?90% at ?300 °C. The mechanisms of formation and decomposition of ternary Mg2CoH5 were studied in detail using an in situ synchrotron radiation powder X-ray diffraction (SR-PXD). The obtained experimental results are supported by morphological and microstructural investigations performed using SEM and high-resolution STEM. Additionally, thermal effects occurring during the desorption reaction were studied using DSC. The morphology of as-prepared ternary Mg2CoH5 is characterized by the presence of porous particles with various shapes and sizes, which, in fact, are a type of nanocomposite consisting mainly of nanocrystallites with a size of ?5 nm. Mg2CoH5 decomposes at approximately 300 °C to elemental Mg and Co. Additionally, at approximately 400 °C, MgCo is formed as precipitates inserted into the Mg–Co matrix. During the rehydrogenation of the decomposed residues, prior to the formation of Mg2CoH5, MgH2 appears, which confirms its key role in the synthesis of the ternary Mg2CoH5.
M. Norek, T.K. Nielsen, M. Polanski, I. Kunce, T. P?ocinski, L.R. Jaroszewicz, Y. Cerenius, T.R. Jensen, J. Bystrzycki, International Journal of Hydrogen Energy 36(2011) 10760-10770

B3124 – Mechano-chemical reactions in LiBH4 + VCln (n = 2 and 3) mixtures

Mechano-chemical routes to the metathesis reaction 4LiBH4 + VCln ? Li4?nV(BH4)4 + nLiCl (n = 2 and 3) are explored at room and liquid nitrogen temperatures. The produced samples consist of crystalline LiCl and unreacted LiBH4. No other crystalline phases are observed directly by powder X-ray diffraction. The highest reactivity was observed when using VCl3. Two possible reaction paths are proposed in order to explain this result: (a) 2LiBH4 + VCl2 ? 2LiCl + VB2 + 4H2, with ?H = ?188 kJ/mol and (b) 3LiBH4 + VCl3 ? 3LiCl + 1/2B2H6 + VB2 + 9/2H2, with ?H = ?258 kJ/mol. The calculated enthalpy values show that reactions with VCl3 have stronger thermodynamical driving forces than with VCl2, corroborating the experimental results. Still, the different experimental methods lead to the same final products, with longer milling times being necessary to remove the precursor traces in the case of VCl2 and cryomilling. The results shed some light on the efficiency of mechano-chemical methods for the synthesis of mixed metal borohydrides based on LiBH4 and V-chlorides.
Isabel Llamas-Jansa, Nadir Aliouane, Stefano Deledda, Jon Erling Fonneløp, Christoph Frommen, Klaus Lieutenant, Sabrina Sartori, Magnus H. Sørby, Bjørn C. Hauback, Journal of Alloys and Compounds 509S (2011) S684– S687

B3049 – Studies of the effects of TiCl3 in LiBH4/CaH2/TiCl3 reversible hydrogen storage system

In the present study, the effects of TiCl3 on desorption kinetics, absorption/desorption reversibility, and related phase transformation processes in LiBH4/CaH2/TiCl3 hydrogen storage system was studied systematically by varying its concentration (x = 0, 0.05, 0.15 and 0.25). The results show that LiCl forms during ball milling of 6LiBH4/CaH2/xTiCl3 and that as temperature increases, o-LiBH4 transforms into h-LiBH4, into which LiCl incorporates, forming solid solution of LiBH4·LiCl, which melts above 280 °C. Molten LiBH4·LiCl is more viscous than molten LiBH4, preventing the clustering of LiBH4 and the accompanied agglomeration of CaH2, and thus preserving the nano-sized phase arrangement formed during ball milling. Above 350 °C, the molten solution LiBH4·LiCl further reacts with CaH2, precipitating LiCl. The main hydrogen desorption reaction is between molten LiBH4·LiCl and CaH2 and not between molten LiBH4 and CaH2. This alters the hydrogen reaction thermodynamics and lowers the hydrogen desorption temperature. In addition, the solid–liquid nano-sized phase arrangement in the nano-composites improves the hydrogen reaction kinetics. The reversible incorporation/precipitation of LiCl at the hydrogen reaction temperature and during temperature cycling makes the 6LiBH4/CaH2/0.25TiCl3 nano-composite a fully reversible hydrogen storage material. These four states of LiCl in LiBH4/CaH2/TiCl3 system, i.e. “formed-solid solution-molten solution-precipitation”, are reported for the first time and the detailed study of this system is beneficial to further improve hydrogen storage property of complex hydrides.
Dongan Liu, Jun Yang, Jun Ni, Andy Drews, Journal of Alloys and Compounds 514 (2012) 103– 108

B3012 – Hydrogen storage with hetero porphyrin aggregates

Hydrogen interaction of porphyrin hetero-pairs has been studied by differential scanning calorimetry (DSC). Aggregates were prepared by spontaneous aggregation of water soluble anionic porphyrins meso-tetra(4-carboxyphenyl)porphine (TCPP) and meso-tetra(4-sulfonatophenyl) porphine (TPPS) with cationic meso-tetra-p-trimethylaminophenyl porphine tetrachloride (TAP). Aggregate formation in solution was investigated via UVevisible spectroscopy at different pH ranges. At neutral to basic conditions, porphyrin pairs formed partially soluble hetero H-aggregates and at low pH, soluble homo J-aggregates was formed. H-aggregates were isolated by centrifuging and freeze-drying. The obtained solids were studied by X-ray powder diffraction. Thermal stability of dry aggregates was determined by thermogravimetric analysis. The TCPP-TAP hetero aggregates exhibited hydrogen uptake between 80 C and 250 C. The amount of hydrogen absorbed by the sample corresponds to 0.29% by weight, indicating a potential use of such materials as a solid state hydrogen storage medium.
Muzaffer Tonguc Oztek, Michael D. Hampton, Darlene K. Slattery, Sandy Loucks, international Journal of Hydrogen Energy 36 (2011) 6705-6710

B2617 – Highly active heteropolyanions supported Co catalysts for fast hydrogen generation in NaBH4 hydrolysis

This paper reports on the use of Co supported catalyst for the hydrolysis of NaBH4. Various materials with different acid/base surface properties have been chosen as supports (hydrotalcites, KF/Al2O3, heteropolyanions). The supports and the Co-containing catalysts were characterized by X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma, nitrogen adsorption. The NaBH4 hydrolysis reaction was studied in a liquid phase calorimeter coupled with a gas counter in order to follow at the same time the kinetics and the heat of reaction. Co supported on heteropolyanions showed great results in terms of reaction rate. Cobalt dispersed on heteropolyanions is a real promising catalytic system for the development of hydrogen generation in PEM fuel cells for portable devices.
Simona Bennici, Hao Yu, Emil Obeid, Aline Auroux, International Journal of Hydrogen Energy, 36 (2011) 7431–7442

B2567 – Hydrogen sorption performance of MgH2 doped with mesoporous nickel- and cobalt-based oxides

The effect of mesoporous Co3O4, NiCo2O4 and NiO on the hydrogen sorption performance of MgH2 was investigated. These oxides were synthesized by multi-step nanocasting and introduced during the high-energy ball milling of MgH2 powder to act as catalysts. Hydrogen desorption on the as-milled powders was assessed upon heating the samples from room temperature to 400 °C. In all cases, the onset temperature for desorption was lowered by taking advantage of the introduced additives. The NiO-doped sample displayed the best response, the desorption rate being 7 times faster than in pure MgH2. Complementary kinetic studies on this particular sample revealed that the sorption activation energies were much lower (50 kJ/mol for absorption and 335 kJ/mol for desorption) than the corresponding ones for undoped MgH2 (57 kJ/mol for absorption and 345 kJ/mol for desorption), thus proving the catalytic activity of the mesoporous NiO oxide. Significantly, the X-ray powder diffraction (XRPD) patterns taken on the NiO-doped sample after discharging/charging cycles revealed that Mg could fully hydrogenate at the end of the charging process, while Mg metal was still detected in the undoped (pure) sample. Favored conditions for dissociative chemisorption of hydrogen could be ascribed to the formation of metallic Ni arising from complete or partial reduction of NiO, as observed in the XRPD patterns.
Moisés Cabo, Sebastiano Garroni, Eva Pellicer, Chiara Milanese, Alessandro Girella, Amedeo Marini, Emma Rossinyol, Santiago Suriñach, Maria Dolors Baró, International Journal of Hydrogen Energy, 36 (2011) 5400–5410

B2565 – Ball-milling and AlB2 addition effects on the hydrogen sorption properties of the CaH2 + MgB2 system

Among the borohydrides proposed for solid state hydrogen storage, Ca(BH4)2 is particularly interesting because of its favourable thermodynamics and relatively cheap price. Composite systems, where other species are present in addition to the borohydride, show some advantages in hydrogen sorption properties with respect to the borohydrides alone, despite a reduction of the theoretical storage capacity. We have investigated the milling time influence on the sorption properties of the CaH2 + MgB2 system from which Ca(BH4)2 and MgH2 can be synthesized by hydrogen absorption process. Manometric and calorimetric measurements showed better kinetics for long time milled samples. We found that the total substitution of MgB2 with AlB2 in the starting material can improve the sorption properties significantly, while the co-existence of both magnesium and aluminum borides in the starting mixture did not cause any improvement. Rietveld refinements of the X-ray powder diffraction spectra were used to confirm the hypothesized reactions.
B. Schiavo, A. Girella, F. Agresti, G. Capurso, C. Milanese, Journal of Alloys and Compounds, 509 (2011) S714–S718

B2489 – Environmental exposure of 2LiBH4 + MgH2 using empirical and theoretical thermodynamics

It has been shown that the consequence of environmental exposure can be qualitatively predicted by modeling the heat generated as a result of environmental exposure of reactive hydrides along with heat loss associated with conduction and convection with the ambient surroundings. To this end, an idealized finite volume model was developed to represent the behavior of dispersed hydride from a breached system. Semi-empirical thermodynamic calculations and substantiating calorimetric experiments were performed in order to quantify the energy released, energy release rates and to quantify the reaction products resulting from water and air exposure of a lithium borohydride and magnesium hydride combination. The hydrides, LiBH4 and MgH2, were studied in a 2:1 “destabilized” mixture which has been demonstrated to be reversible. Liquid water hydrolysis reactions were performed in a Calvet calorimeter equipped with a mixing cell using pH-neutral water. Water vapor and gaseous oxygen reactivity measurements were performed at varying relative humidities and temperatures by modifying the calorimeter and utilizing a gas circulating flow cell apparatus. The results of these calorimetric measurements were used to develop quantitative kinetic expressions for hydrolysis and air oxidation in these systems. Thermodynamic parameters obtained from these tests were then incorporated into a computational fluid dynamics model to predict both the hydrogen generation rates and concentrations along with localized temperature distributions. The results of these numerical simulations can be used to predict ignition events and the resultant conclusions will be discussed.
C.W. James Jr., D.A. Tamburello, K.S. Brinkman, J.R. Gray, B.J. Hardy, D.L. Anton, International Journal of Hydrogen Energy 36 (2011) 2471-2477

B2466 – Improved hydrogen storage capacity through hydrolysis of solid NaBH4 catalyzed with cobalt boride

In this article the feasibility of the reaction of liquid water with a solid NaBH4/catalyst mixture for improved hydrogen storage capacity and on-demand H2 generation is reported. The synthesized low-cost nanosized catalyst consists of a Co2B core surrounded by an oxide layer, presenting a relatively large specific surface area (70 m2 g 1). Calorimetric experiments coupled to simultaneous measurements of the evolved hydrogen volume have shown the positive effect of the locally heat release during reduction of the superficial oxidized layer. The synergetic effects of the exothermicity of both the oxidized layer reduction and the hydrolysis reaction coupled to the high efficiency of the cobalt boride catalyst led to an “enhanced regime” observed at room temperature. The “enhanced regime” corresponds to a global reaction stoichiometry of 1 mol of NaBH4 reacting with 3 mol of water, conducting to a hydrogen yield of 8.7 wt.%. Effects of temperature and catalyst content were studied.
J. Delmas, L. Laversenne, I. Rougeaux, P. Capron, A. Garron, S. Bennici, D. Swierczynski, A. Auroux, International Journal of Hydrogen Energy 36 (2011) 2145-2153

B2413 – Maximizing the hydrogen yield in the catalyzed hydrolysis of pure borohydride powders

Around 10 wt% H2 can be stored in a NaBH4 based system at ambient temperature and atmospheric pressure. The hydrogen is released when water is added to an excess of NaBH4(s)/cobalt (s)/NaOH(s) powder mixture. The heat evolved during the reaction increases the temperature from 25 up to 140°C as monitored by an IR camera. This permits the formation of NaBO2.H2O with x=1/2, thermodynamically stable above 105°C, rather than NaBO2.4H2O typically formed in excess water at room temperature. The presence of NaOH plays a crucial role in accelerating the reaction and increasing the temperature
Simona Bennici, Anthony Garron, Aline Auroux, International Journal of hydrogen energy, 35 (2010) 8621-8625

B2412 – Determination of the heat evolved during sodium borohydride hydrolysis catalyzed by Co3O4

In this work we present a calorimetric study of NaBH4 hydrolysis in the presence of Co3O4. NaBH4 can be utilized as source of a high purity hydrogen generated by the hydrolysis reaction (BH4- + 4H2O -- B(OH)4- + 4H2) which is easily controlled by catalysts. A modified Setaram Titrys microcalorimeter was used to determine the enthalpy of hydrolysis in a system where water excess is added to pure solid NaBH4 as well as to solid NaBH4 mixed with Co3O4. Effects of different amounts of water and NaOH (solid and solution) additions on the rate of hydrolysis reaction were also investigated. Heats evolved under different experimental conditions were always about 240 kJ mol 1. Lower amount of water resulted in lower reaction rate. The addition of NaOH solution increased the catalytic activity compared to the addition of the same amount of solid NaOH.
Ljiljana Damjanovic, Mickaël Majchrzak, Simona Bennici, Aline Auroux, International Journal of hydrogen energy, 36 (2011) 1991-1997

B2410 – New insights into the mechanism of H2 generation through NaBH4 hydrolysis on Co-based nanocatalysts studied by differential reaction calorimetry

To our knowledge, the present study is the first investigation by liquid-phase calorimetry of the mechanism of hydrogen generation by hydrolysis of sodium borohydride catalyzed by Co2B nanoparticles generated in situ. The differential reaction calorimeter was coupled with a volumetric hydrogen measurement, allowing a simultaneous thermodynamic and kinetic study of the reaction. At the end of the reaction, the catalyst was characterized exsitu by TEM, XRD, magnetism, N2 adsorption, TGA–DTA, and the liquid hydrolysis products were analyzed by Wet-STEM and 11B-NMR. The in situ preparation method made it possible to form nanoparticles (<12 nm) of Co2B which are the active phase for the hydrolysis reaction. In semi-batch conditions, the Co2B catalyst formed in situ is subsequently reduced by each borohydride addition and oxidized at the end of the hydrolysis reaction by OH in the presence of metaborate. A coating of the nanoparticles has been observed by calorimetry and physico-chemical characterization, corresponding to the formation of a 2–3 nm layer of cobalt oxide or hydroxide species.
Anthony Garron, Dariusz Swierczynski, Simona Bennici, Aline Auroux, International Journal of hydrogen energy, 34 (2009) 1185-1199

B2409 – In situ generated catalysts for NaBH4 hydrolysis studied by liquid-phase calorimetry: Influence of the nature of the metal

Several metal chloride salts have been evaluated as precursors of in situ generated catalysts for borohydride hydrolysis. The apparatus used for this study is a reaction calorimeter coupled with a hydrogen volumetric flow-meter. Successive additions of low and high concentration solutions of NaBH4 were performed within this system in order to determine the stability of the catalysts and the poisoning effect of residualmetaborate. Both the kinetics of hydrogen production and the concomitant calorimetric signal were studied from this perspective. This work highlights the occurrence of two different types of behaviours among the in situ generated catalysts, and demonstrates that those metals which can be readily oxidized and form stable boride species are the best catalysts for the catalytic borohydride hydrolysis reaction, at a lower cost compared to precious metals. The performances of these catalysts are not affected by the concentration of the NaBH4 solution, and the rate of hydrogen generation remains constant during the reaction.
Anthony Garron, Simona Bennici, Aline Auroux, Applied Catalysis A: General 378 (2010) 90–95

B2397 – Effect of C (graphite) doping on the H2 sorption performance of the Mg–Ni storage system

Binary Mg–Ni mixtures and ternary Mg–Ni–C (graphite) samples with fixed proportions of metals (Mg 85%–Ni 15% by weight) and amount of C increasing in increments of 5 wt % from 5 wt % to 15 wt % were prepared by high energy ball milling (BM) in Ar for tBM ¼2 h. The purpose of the study was to evaluate the effect of C addition on the reactivity, the sorption activation and the storage performance of the Mg–Ni system. Increasing the amount of C had the effect of decreasing (from 10 to 3) the number of cycles needed for activation (performed at 623 K and 40 bar/0.9 bar charging/discharging H2 pressure). After full activation, the 5 wt % C-containing sample exhibited the best absorption kinetics performance: the average rate to charge up to 5 wt % H2 was about 3 times higher than that observed for the undoped sample. Unfortunately, increasing the amount of C had a negative impact on the desorption behaviour, causing an increase in the dehydrogenation activation energy and a decrease in the discharging rates. Within the present study, C reacted neither with H2 nor with the H2 active phases (the two discharged phases Mg and Mg2Ni and the related hydrides) and consequently did not lead to variation in the sorption enthalpies of the Mg–Ni system. But, its presence did cause a small increase (4 K at 0.9 bar H2) in the minimum desorption temperatures of the hydrides and a consequent minor decrease (0.2 bar) in the equilibrium pressures. The best sorption properties were obtained for the 5 wt % C-sample, that on the whole worked better than the binary mixture.
C. Milanese, A. Girella, S. Garroni, G. Bruni, V. Berbenni, P. Matteazzi, A. Marini

B2370 – A direct measurement of the heat evolved during the sodium and potassium borohydride catalytic hydrolysis

NaBH4 and KBH4 hydrolysis reactions (BH4 +4H2O?B(OH)4 +4H2), which can be utilized as a source of high purity hydrogen and be easily controlled catalytically, are exothermic processes. Precise determination of the evolved heat is of outmost importance for the design of the reactor for hydrogen generation. In this work we present an efficient calorimetric method for the direct measurement of the heats evolved during the catalyzed hydrolysis reaction. A modified Setaram Titrys microcalorimeter was used to determine the heat of hydrolysis in a system where water is added to pure solid NaBH4 or KBH4 as well as to solid NaBH4 or KBH4 mixed with a Co-based solid catalyst. The measured heats of NaBH4 hydrolysis reaction were: ?236 kJ mol?1, ?243 kJ mol?1, ?235 kJ mol?1, and ?236 kJ mol?1, without catalyst and in the presence of Co nanoparticles, CoO and Co3O4, respectively. In the case of the KBH4 hydrolysis reaction, the measured heats were: ?220 kJ mol?1, ?219 kJ mol?1, ?230 kJ mol?1, and ?228 kJ mol?1, without catalyst and with Co nanoparticles, CoO and Co3O4, respectively. Also, a comparison was made with an aqueous solution of CoCl2·6H2O used as catalyst in which case the measured heats were ?222 kJ mol?1 and ?196 kJ mol?1 for NaBH4 and KBH4 hydrolysis, respectively. The influence of solid NaOH or KOH additions on the heat of borohydride hydrolysis has been investigated as well.
Ljiljana Damjanovic, Simona Bennici, Aline Auroux, Journal of Power Sources 195 (2010) 3284–3292

B2351 – Comparison of the thermal decomposition kinetics for charged LiMn2O4 by TG and C80 methods

In order to disclose the decomposition kinetics of charged LiMn2O4 used in lithium-ion batteries, thermogravimetric analyzer (TGA) and C80 micro-calorimeter were employed in this study. Three stages of weight loss were detected by TG and two main exothermic processes were detected by C80 micro-calorimeter for the charged LiMn2O4. The chemical reaction kinetics is supposed to fit by an Arrhenius law, and then the activation energy is calculated as Ea = 90.4 and 140.1 kJ mol?1 based on TG and C80 data, respectively. And the C80 method shows more advantages in studying the thermodynamic and kinetic parameters for both the electrodes alone and its co-existing system with electrolyte.
Qingsong Wang, Jinhua Sun, Dongliang Chena, Chunhua Chen, Journal of Alloys and Compounds 468 (2009) 477–481

B2350 – Effects of solvents and salt on the thermal stability of charged LiCoO2

Lithium-ion batteries safety is an issue that should be solved. The thermal stability of Li0.5CoO2 in the presence of solvents/electrolyte and LiPF6 salt were studied by using C80 micro-calorimeter in this paper. It was found that the thermal stability of Li0.5CoO2 either in the presence of cyclic carbonate or linear carbonate is decreased greatly, especially for the linear carbonate–Li0.5CoO2 coexisting system, and the thermal stability of dimethyl carbonate–Li0.5CoO2 coexisting system is the least stable one. LiPF6 can prevent oxygen releasing from Li0.5CoO2 at lowtemperature, but the delayed reaction will generatemore heat at higher temperature. At last, thermal stability of two kinds of electrolytes with Li0.5CoO2 was explored. The LiPF6/ethylene carbonate + dimethyl carbonate + ethylmethyl carbonate–Li0.5CoO2 system shows less thermal stability, which is attributed to the activity between dimethyl carbonate and Li0.5CoO2, as well as agree with the thermal experiment on dimethyl carbonate–Li0.5CoO2 coexisting system.
Qingsong Wang, Jinhua Sun, Xianfeng Chen, Guanquan Chu, Chunhua Chen, Materials Research Bulletin 44 (2009) 543–548

B2349 – Thermal stability of LiPF6/EC + DEC electrolyte with charged electrodes for lithium ion batteries

The thermal stabilities of 1M LiPF6/EC + DEC and with electrodes were studied by calorimetry. The results show that both the electrolyte–Li0.5CoO2 and electrolyte–LixC6 system have lower decomposition onset temperatures than either the separate electrolyte or electrodes. The electrolyte is oxidized by Li0.5CoO2, while its reaction with lithiated graphite occurs because the solid electrolyte interphase (SEI) breaks down at 57 ?C. The 1M LiPF6/EC + DEC in air is less stable than in argon, but the reaction is similar
Qingsong Wang, Jinhua Sun, Xiaolin Yao, Chunhua Chen, Thermochimica Acta 437 (2005) 12–16

B2348 – Enhancing the thermal stability of LiCoO2 electrode by 4-isopropyl phenyl diphenyl phosphate in lithium ion batteries

To enhance the thermal stability of LiCoO2 in lithiumion batteries, 4-isopropyl phenyl diphenyl phosphate (IPPP) was investigated as an additive in 1.0MLiPF6/EC + DEC (1:1 wt.%) electrolyte. The thermodynamics and kinetics parameters of the single LiCoO2 and LixCoO2–IPPP-electrolyte are detected and calculated based on the C80 microcalorimeter data. The results indicated that IPPP can enhance the thermal stability of LiCoO2 electrode in lithium ion battery more or less corresponding to the IPPP content in electrolyte. Furthermore, the electrochemical performances of LiCoO2/IPPP-electrolyte/Li cells become slightly worse after using IPPP additive in the electrolyte. This alleviated trade-off between thermal stability and cell performance provides a possibility to formulate an electrolyte containing 5–10% of IPPP and enhance the LiCoO2 electrode thermal stability with minimum sacrifice in performance.
Qingsong Wang, Jinhua Sun, Chunhua Chen, Journal of Power Sources 162 (2006) 1363–1366

B2347 – Micro calorimeter study on the thermal stability of lithium-ion battery electrolytes

With the extensive applications of lithium-ion batteries, many batteries explosion accidents were reported. The thermal stability of lithium-ion battery electrolyte could substantially affect the safety of lithium-ion battery. The C80 micro calorimeter was used to study the thermal stability of several commonly used organic solvents and electrolytes. The samples were heated in argon atmosphere and air atmosphere, respectively. The chemical reaction kinetics was supposed to fit by an Arrhenius law, then the self-accelerating decomposition temperature was calculated. It is found that most of the samples are stable in argon atmosphere while decomposing in air atmosphere, and the single organic solvent is more stable than the electrolyte generally.
Qingsong Wang, Jinhua Sun, Xiaolin Yao, Chunhua Chen, Journal of Loss Prevention in the Process Industries 19 (2006) 561–569

B2346 – Enhancing the safety of lithium ion batteries by 4-isopropyl phenyl diphenyl phosphate

To enhance the safety of lithium ion batteries, 4-isopropyl phenyl diphenyl phosphate (IPPP) was explored as an additive in 1.0 M LiPF6/ ethylene carbonate (EC)+diethyl carbonate (DEC) (1:1 wt.%). The electrochemical performances of LiCoO2/IPPP electrolyte/C cells were tested. And then the LiCoO2/IPPP electrolyte/C cells were disassembled and wrapped to detect the thermal behaviors using a C80 microcalorimeter. The results indicated that 5% and 10% IPPP content in the electrolyte can enhance the safety of lithium ion batteries. Furthermore, the electrochemical performances of LiCoO2/IPPP electrolyte/C cells become slightly worse by using 5% and 10% IPPP content electrolyte. Therefore, 5–10% IPPP content in electrolyte can enhance the safety of lithium ion batteries with minimum sacrifice in electrochemical performance.
Qingsong Wang, Jinhua Sun, Materials Letters 61 (2007) 3338–3340

B2345 – Improved thermal stability of graphite electrodes in lithium-ion batteries using 4-isopropyl phenyl diphenyl phosphate as an additive

To enhance the thermal stability of graphite electrodes for lithium-ion batteries, 4-isopropyl phenyl diphenyl phosphate (IPPP) was investigated as an additive in the electrolyte of 1.0 M LiPF6 in ethylene carbonate and diethyl carbonate (1:1 in weight). The electrochemical performance of Li/IPPP-electrolyte/C half cells was evaluated. The thermal behavior of LixC6 and LixC6-IPPP-electrolytes were examined using a C80 micro-calorimeter. Electrolytes with 5 and 10% IPPP improve the thermal stability of the graphite electrode in the tests. The electrochemical performance of Li/IPPP-electrolyte/C cells is not degraded by the addition of this amount of IPPP to the electrolyte.
Qingsong Wang, Jinhua Sun, Chunhua Chen, J Appl Electrochem (2009) 39:1105–1110

B2344 – Effects of solvents and salt on the thermal stability of lithiated graphite used in lithium ion battery

The thermal stability of lithiated graphite in the presence of solvents, electrolytes and LiPF6 salt was studied using C80 microcalorimeter. The presence of cyclic carbonates or linear carbonates increases the activity of LixC6–solvent coexisting system, especially for the LixC6–linear carbonates one. LiPF6 was detected that it increases the activity greatly of its coexisting systemwithlithiated graphite. The coexisting system of LixC6 with the electrolyte of LiPF6/ethylene carbonate + diethyl carbonate shows less thermal stability, which is attributed to the activity between diethyl carbonate and LixC6. This also agrees with the experiment result of LixC6–diethyl carbonate coexisting system.
Qingsong Wang, Jinhua Sun, Chunhua Chen, Journal of Hazardous Materials 167 (2009) 1209–1214

B2331 – Thermal decomposition of cyclotriborazane

Cyclotriborazane (CTB), B3N3H12, is a crystalline white solid, which decomposes above 400K to hydrogen and a few other products, depending on the reaction conditions. In this work we present investigations of the thermal decomposition of both the neat compound and CTB dissolved in diglyme and tetraglyme. Several thermophysical and analytical methods, such as differential scanning calorimetry (DSC), thermogravimetry (TG), mass spectroscopy (QMS), and 11B nuclear magnetic resonance spectroscopy (NMR) have been used for this investigation. The decomposition of the neat substance releases 3.1 mol H2/mol CTB and leads to a polymeric products and borazine. In open vessels, sublimation as a competing process also occurs. The enthalpy of the decomposition process (1RHs) has been determined as 1RHs =?34.0±2.9 kJ/mol. In contrast to the thermal decomposition of the pure substance, the decomposition in polyethers, such as diglyme and tetraglyme, leads above 370K to borazine and small amounts of soluble oligomeric borazine species. Also BH3 group containing species are occurring as intermediates. In these systems no precipitation was detected. DSC measurements show for the decomposition in solution several strong exothermic effects. The overall decomposition enthalpy in diglyme is given by1RHd =?32.0±2.8 kJ/mol and in tetraglyme by1RHt =?48.0±4.7 kJ/mol. The enthalpy of solution of cyclotriborazanewas determined in diglyme and in tetraglyme with the values1DHd =?2.1±0.2 kJ/mol and1DHt =?4.6±0.5 kJ/mol, respectively.
R. Schellenberg, J. Kriehme, G. Wolf, Thermochimica Acta 457 (2007) 103–108

B2330 – Thermal properties and kinetics study of charged LiCoO2 by TG and C80 methods

The thermal stability of lithium-ion battery cathode could substantially affect the safety of lithium-ion battery. In order to disclose the decomposition kinetics of charged LiCoO2 used in lithium ion batteries, thermogravimetric analyzer (TG) and C80 microcalorimeter were employed in this study. Four stages of mass losses were detected by TG and one main exothermic process was detected by C80 microcalorimeter for the charged LiCoO2. The chemical reaction kinetics is supposed to fit by an Arrhenius law, and then the activation energy is calculated as Ea=148.87 and 88.87 kJ mol–1 based on TG and C80 data, respectively
Q. S. Wang, J. H. Sun, C. H. Chen and X. M. Zhou, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 2, 563–566

B2286 – Factors affecting the efficiency of Nafion-based catalytic membranes in the selective oxidation of light paraffins mediated by the Fenton system

The partial oxidation of propane to oxygenates (isopropanol, n-propanol, propionic aldehyde and acetone) is attained in a multifunctional three phase catalytic membrane reactor (3PCMR) operating under mild conditions (TR, 80-120°C; PR, 140 kPa). A comparative testing of different Nafion-based catalytic membranes mediated by Fe2+/H2O2 Fenton system has been carried out. The influences of textural and compositional properties and acid functionality on the catalytic performance of the Nafion membranes are outlined. The enhancing effect of the partial heterogenisation of the Fenton system on reaction rate and H2O2 yield is discussed.
C. Espro, G. Bonura, F. Arena, F. Frusteri, A. Parmaliana , F. Sini, V. Solinas, Catalysis Today 91-92 (2004) 215-218

B2195 – Synthesis and characterization of carbon black supported Pt-Ru alloy as a model catalyst for fuel cells

A set of bimetallic Pt-Ru catalysts prepared by co-impregnation of carbon black with ruthenium(III) chloride hydrate and hydrogen hexachloroplatinate(IV) hydrate were investigated by temperature-programmed reduction (TPR), chemisorption of hydrogen, transmission electron microscopy (TEM), microcalorimetry of adsorbed CO and a structure-sensitive reaction (n-hexane conversion). The results showed that the volumetric capacities for CO and H2 adsorption is influenced in the bimetallic Pt-Ru catalysts by the formation of a Pt-Ru alloy. The n-hexane reaction revealed that the reaction mechanism for the pure Pt catalyst mainly occurs via cyclic isomerization and aromatization due to the presence of bigger Pt surface ensembles, whereas the Pt-Ru catalysts exhibited predominantly bond-shift isomerization by the diluting effect of Ru metal addition. The differential heats of CO chemisorption on Pt-Ru catalysts fell between the two monometallic Pt and Ru catalysts extremes.
Yao Jun Zhang, A. Maroto-Valiente, I. Rodriguez-Ramos, Qin Xin, A. Guerrero-Ruiz, Catalysis Today 93-95 (2004) 619-626

B2184 – Development of a new thermogravimetric and calorimetric technique for the determination of energetics, thermodynamics and kinetics of hydrogen storage in various materials

The recent developments in the field of fuel cells and more particularly hydrogen storage under solid form have underlined the usefulness of the thermogravimetry (TG) under pressure of hydrogen to define the PCT (Pressure Concentration Temperature) curves. Such a PCT curve will define the capacity of storing hydrogen for a given metal or organic compound as a function of the temperature and the pressure. The calorimetric techniques (DSC) enable also to perform such studies at variable temperature and pressure, in order to determine the energy associated with the adsorption or desorption of hydrogen. The knowledge of this energy allows to assess the increase in temperature in the course of the reaction. This parameter will be very helpful for the industrialization and the safety of the storage process. Setaram develops an original combination of both thermogravimetric and calorimetric measurements that has the great advantage of being able to correlate both pieces of information (mass variation and energy) on the same sample under hydrogen pressure. The new thermogravimetric and calorimetric technique will apply for any material used for hydrogen storage under solid form (metal hydride, borohydride, alanate, zeolite, clathrate ..).
P. Le Parlouër, C. Mathonat

B2129 – Diurea Cross-Linked Poly(oxyethylene)/Siloxane Ormolytes for Lithium Batteries

Poly(oxyethylene)(POE)/siloxane hybrids (di-ureasils) doped with a wide concentration range of lithium triflate (LiCF3SO3) were investigated. The host matrix of these materials [d-U(2000)] is a sol-gel-derived siliceous framework to which POE chains with about 40.5 repeat units are bonded through urea linkages. Xerogels with ? > n > 5 (n is the molar ratio OCH2CH2 /Li+) were obtained as amorphous monoliths thermally stable up to at least 340°C. A crystalline POE/LiCF3SO3 complex was detected spectroscopically in samples with n < 10. Below 90°C the ormolyte with n = 20 exhibits the highest conductivity (5.8 x 10^(-6) ohm-1 cm-1 at 26°C). The redox stability domain of this material spans 4.1 V. Although Fourier transform infrared spectroscopy data suggest that the Li+ ions are complexed by the POE ether oxygen atoms at n < 10, this threshold composition is probably located at slightly lower salt content. "Free" triflate ions and weakly coordinated anions, present in all the samples examined, must be the main charge carriers of the d-U(2000)20LiCF3SO3 xerogel. Ion pairs (Li+CF3SO3-) or negatively charged triplets ([Li(CF3SO3)2]-) are formed at n < 40. At n < 5 positively charged triplets [Li2(CF3SO3)]+ also appear. Divalent positively charged multiplets [Li3(CF3SO3)]2+ occur at n = 1.
S.C. Nunes, V. de Zea Bermudez, D. Ostrovskii, M.M. Silva, S. Barros, M.J. Smith, L.D. Carlos, J. Rocha, and E. Morales, Journal of The Electrochemical Society 152 (2005) A429-A438

B2106 – Effect of Ga doping on the structural, electrochemical and thermal properties of LiCo0.975Ga0.025O2 as cathode materials for lithium ion batteries

Layered LiCo0.975Ga0.025O2 was prepared by a sol-gel method and its structure, electrochemical and thermal properties were compared with those of LiCoO2 synthesized by the same method. The results showed that gallium doping improved the capacity retention of LiCoO2 while it lowered the initial discharge capacity. The improvement of capacity retention was prominent when the cycle tests were carried out at higher cut-off voltage and larger current rate. Cyclic voltammetry test indicated that the phase transition of LiCoO2 was suppressed by gallium doping. XRD of LixCo0.975Ga0.025O2 indicated that gallium doping brought about fewer changes in the c-axis during charge. Furthermore, the gallium doping also significantly enhanced the chemical diffusivity of Li+, suppressed the Co dissolution, limited the decomposition of electrolyte and improved the thermal stability of LiCoO2 during cycling.
D-G. Tong, Y-Y. Luo, Y. He, X-Y. Ji, J-L. Cao, L-X. Tang, A-D. Tang, K-L. Huang, Q-Y. Lai, Materials Science and Engineering B 128 (2006) 220-228

B2102 – Pure hydrogen production on a new gold-thoria catalyst for fuel cell applications

A new gold catalyst was synthesized by deposition-precipitation of gold hydroxide on thoria. The catalyst showed extremely high catalytic activity at the lowest possible temperature for carrying out of water-gas shift reaction (WGSR) under experimental conditions. The measured degree of CO conversion at 393 K (GHSV = 4000 h-1) was 84%. The effect of space velocity and water vapor partial pressure on WGS activity was studied at different temperatures. The catalytic measurements testified high stability of Au/ThO2. HRTEM combined with EDS, X-ray diffraction and H2-TPR techniques were used for the catalyst characterisation. Detailed FTIR measurements of adsorbed CO at different temperatures on oxidized and reduced catalyst were performed. FTIR spectra were also collected during CO + O2 interaction at different temperatures, CO oxidation in the presence of hydrogen (PROX) and WGSR. Preliminary catalytic tests for CO oxidation in hydrogen-rich gas stream revealed that Au/ThO2 could be of interest as potential catalyst for the PROX process.
T. Tabakova, V. Idakiev, K. Tenchev, F. Boccuzzi, M. Manzoli, A. Chiorino, Applied Catalysis B: Environmental 63 (2006) 94-103

B2063 – Hydrogen uptake characteristics of mechanically alloyed Ti-V-Ni

It has been well established that hydrogen will react directly and reversibly with a large number of metals and alloys to form metallic hydrides. Extensive research has been done over the years to improve properties of these hydrogen purification and recovery media and in developing new compounds for this purpose. In the present study, the hydrogen uptake characteristics of mechanically alloyed titanium-vanadium-nickel have been studied. Thermal and composition data were obtained for the Ti-V-Ni system prepared by mechanical alloying at a ball-to-powder mass ratio of 10:1. It was found that this material would absorb up to approximately 1.0 wt% hydrogen at near ambient temperature and ambient pressure of hydrogen.
D. Cauceglia, M.D. Hampton, J.K. Lomness, D.K. Slattery, M. Resan, Journal of Alloys and Compounds 417 (2006) 159-163

B2053 – Crystal structures of electrospun PVDF membranes and its separator application for rechargeable lithium metal cells

Anelectrospinning methodwas used to prepare electrospun PVDF-based membranes (EPMs) for battery separators applications. The morphology of the EPMs was investigated by scanning electron microscopy (SEM). The relations between applied voltage and average fiber diameter (AFD) under certain electrospinning conditions were discussed. The thermal properties and crystal structure of the EPMs also were investigated by differential scanning calorimetry (DSC), and wide-angle X-ray diffraction (WAXD). Due to soften PVDF fibers in high temperature, the thermal treated EPMs can form an interconnected web structure, which greatly improves physical properties. Compared with CelgardTM 2400 (PP separator), the cell with EPM shows better cycling ability of CV and charge-discharge performance with little capacity loss after 50 cycles at C/2 rate.
K. Gao, X. Hu, C. Dai, T. Yi, Materials Science and Engineering B 131 (2006) 100-105

B2019 – Iodide-based electrolytes: A promising alternative for thermal batteries

Molten iodide-based salts due to their low melting points were envisaged to improve the performances of thermal batteries. Iodide-based salt drying and the determination of the basic properties (electrochemical window, conductivity, thermal heat capacity, ... ) of some electrolytes were carried out. The results obtained showed that some of iodide-based electrolytes are suitable for thermal batteries. In addition, the LiF-LiCl-LiI and LiF-LiBr-KBr electrolytes were tested in Li-Si/FeS2 single cells in the temperature of thermal battery operating conditions. The LiF-LiCl-LiI electrolyte could be considered as an interesting alternative for the improvements of thermal battery performances.
P. Masset, Journal of Power Sources 160 (2006) 688-697

B1980 – Micro calorimeter study on the thermal stability of lithium-ion battery electrolytes

With the extensive applications of lithium-ion batteries, many batteries explosion accidents were reported. The thermal stability of lithium-ion battery electrolyte could substantially affect the safety of lithium-ion battery. The C80 micro calorimeter was used to study the thermal stability of several commonly used organic solvents and electrolytes. The samples were heated in argon atmosphere and air atmosphere, respectively. The chemical reaction kinetics was supposed to fit by an Arrhenius law, then the self-accelerating decomposition temperature was calculated. It is found that most of the samples are stable in argon atmosphere while decomposing in air atmosphere, and the single organic solvent is more stable than the electrolyte generally.
Q. Wang, J. Sun, X. Yao, C. Chen, Journal of Loss Prevention in the Process Industries 19 (2006) 561-569

B1974 – Proton exchange membranes based on modified sulfonated poly(ether ether ketone) membranes with chemically in situ polymerized polypyrrole

Sulfonated poly(ether ether ketone) (SPEEK) membranes were modified with chemically in situ polymerized polypyrrole (PPy). The effects of temperature and methanol concentration on the solution uptake and the swelling ratio of SPEEK/PPy membranes were investigated. The solution uptake and the swelling ratio of the membranes decreased upon the incorporation of PPy. When the methanol concentration increased, both the solution uptake and the swelling ratio increased to a maximum, and then decreased. FT-IR, XRD, DSC and TGA were used to characterize the modified membranes. The methanol permeability of modified SPEEK membranes decreased upon the incorporation of PPy, and higher selectivity values were found for SPEEK/PPy membranes in comparison with pure SPEEK and Nafion® 117 membranes.
S. Xue, G. Yin, Electrochimica Acta 52 (2006) 847-853

B1963 – Enhancing the thermal stability of LiCoO2 electrode by 4-isopropyl phenyl diphenyl phosphate in lithium ion batteries

To enhance the thermal stability of LiCoO2 in lithium ion batteries, 4-isopropyl phenyl diphenyl phosphate (IPPP) was investigated as an additive in 1.0MLiPF6/EC + DEC (1:1 wt.%) electrolyte. The thermodynamics and kinetics parameters of the single LiCoO2 and LixCoO2-IPPP-electrolyte are detected and calculated based on the C80 microcalorimeter data. The results indicated that IPPP can enhance the thermal stability of LiCoO2 electrode in lithium ion battery more or less corresponding to the IPPP content in electrolyte. Furthermore, the electrochemical performances of LiCoO2/IPPP-electrolyte/Li cells become slightly worse after using IPPP additive in the electrolyte. This alleviated trade-off between thermal stability and cell performance provides a possibility to formulate an electrolyte containing 5-10% of IPPP and enhance the LiCoO2 electrode thermal stability with minimum sacrifice in performance.
Q. Wang, J. Sun, C. Chen, Journal of Power Sources 162 (2006) 1363-1366

B1959 – Permeabilities of methanol, ethanol and dimethyl ether in new composite membranes: A comparison with Nafion membranes

New composite membranes were prepared by solution casting from sulfonated poly(ether ether ketone), poly(vinylidene fluoride) and phosphotungstic acid. Their structures were characterized using XRD, DSC and FT-IR. The permeability of methanol, ethanol and dimethyl ether in composite membranes ranged from 1.9 to 3.7x10^(-7), 7.4 to 20x10^(-8) and 1.6 to 3.2x10^(-8) cm2/s, respectively. These values were about or more than one order of magnitude lower than those of Nafion® 117 membrane measured under the same condition. The water uptake and the swelling ratio of composite membranes were also studied, and composite membranes showed good water stability within measurement range of temperature. Higher selectivity values were observed for composite membranes compared with Nafion® 117 membrane.
S. Xue, G. Yin, K. Cai, Y. Shao, Journal of Membrane Science 289 (2007) 51-57

B1957 – Enhancing the safety of lithium ion batteries by 4-isopropyl phenyl diphenyl phosphate

To enhance the safety of lithium ion batteries, 4-isopropyl phenyl diphenyl phosphate (IPPP) was explored as an additive in 1.0 M LiPF6/ ethylene carbonate (EC)+diethyl carbonate (DEC) (1:1 wt.%). The electrochemical performances of LiCoO2/IPPP electrolyte/C cells were tested. And then the LiCoO2/IPPP electrolyte/C cells were disassembled and wrapped to detect the thermal behaviors using a C80 microcalorimeter. The results indicated that 5% and 10% IPPP content in the electrolyte can enhance the safety of lithium ion batteries. Furthermore, the electrochemical performances of LiCoO2/IPPP electrolyte/C cells become slightly worse by using 5% and 10% IPPP content electrolyte. Therefore, 5-10% IPPP content in electrolyte can enhance the safety of lithium ion batteries with minimum sacrifice in electrochemical performance.
Q. Wang, J. Sun, Materials Letters 61 (2007) 3338-3340

B1954 – Investigation of chemisorbed oxygen, surface segregation and effect of post-treatments on La0.8Sr0.2MnO3 powder and screen-printed layers for solid oxide fuel cell cathodes

In order to better understand the mechanism of the reaction of oxygen reduction at the surface of strontium doped lanthanum manganites (LSM) cathodes in solid electrolyte fuel cells (SOFC), the surface properties of La0.8Sr0.2MnO3 powders and screen-printed layers have been characterised by various techniques. Strontium enrichment at the surface has been evidenced by X-ray photoelectron spectroscopy according to the conditions of annealing (temperature, oxygen pressure) and polarisation treatments of the samples. The interaction between oxygen and La0.8Sr0.2MnO3 for SOFC cathodes has been studied by thermo-programmed desorption, in situ infrared spectrometry and calorimetry. The results indicate that various adsorbed oxygen species may exist on the surface of LSM depending on temperature. The presence of various adsorbed oxygen species and the surface Sr segregation are important factors to consider in the mechanism of oxygen reduction at LSM SOFC cathodes since they could be responsible for many discrepancies between the interpretations that can be found in the literature data.
N. Caillol, M. Pijolat, E. Siebert, Applied Surface Science 253 (2007) 4641-4648

B1934 – Synthesis and characterization of LiCo(0.3-x)GaxNi0.7O2 (x = 0, 0.05) as a cathode material for lithium ion battery

The single phase of LiCo(0.3-x)GaxNi0.7O2 (x = 0, 0.05) was synthesized by a sol-gel method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical performance. The powders are homogeneous and have a good-layered structure. The synthesized LiCo0.25Ga0.05Ni0.7O2 exhibits better electrochemical performance with an initial discharge capacity of 180.0 mAh g-1 and a capacity retention of 95.2% after 50 cycles between 2.8 and 4.4V at 0.2C rate. The study on the structural evolution of the material during the cycling shows that Ga-doping improves the structure stability of LiCo0.3Ni0.7O2 at ambient temperature and 55°C. Meanwhile, Ga-doping not only suppresses the alternating current (AC) impedance of LiCo0.3Ni0.7O2 but also promotes the Li+ diffusion in LiCo0.3Ni0.7O2. Furthermore, thermal stability of the charged LiCo0.25Ga0.05Ni0.7O2 is improved, which may be attributed to the retard of O2 evolution in LiCo0.3Ni0.7O2 and the suppression of electrolyte oxidation during cycling by Ga-doping.
D-G. Tong, J-L. Cao, Q-Y. Lai, A-D. Tang, K-L. Huang, Y. He, X-Y. Ji, Materials Chemistry and Physics 100 (2006) 217-223

B1927 – Hydrogen absorption-desorption in CeNi2

Hydrogen absorption and desorption properties of CeNi2 compound are presented. Hydrogen absorption leads to the formation of CeH3 and CeNi2Hx, with a variation of the cell parameter of the compound from a = 7.201 Å to 7.093 Å. The hydrogen content in the compound is around 0.5 H/M under a hydrogen pressure of 0.03MPa at 475 K. The enthalpy of CeNi2 hydride formation was measured to be -25 kJ molH-1by thermal analysis. From thermal desorption analysis the activation energies for hydrogen desorption from the CeNi2 hydride was estimated to be about 50 kJ/mol. The location of hydrogen in tetrahedral sites has been identified from a semi-empirical description of hydrogen absorption in CeNi2 structure by Miedema model.
M. Di Chio, S. Livraghi, M. Baricco, Journal of Alloys and Compounds 426 (2006) 180-185

B1829 – A study of the adsorption of thiophenic sulfur compounds using flow calorimetry

Selective adsorption of sulfur compounds from gasoline and diesel fuel has potential to produce ultra clean fuels for on-board fuel cell applications and also to meet the upcoming legislation for clean fuels. Removal of thiophenic sulfur compounds in a hexadecane solution using commercial zeolites, NaY, USY, HYand 13X, has been investigated by adsorption and flow calorimetry techniques. The S compounds chosen were thiophene (T), benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The adsorption studies were carried out in the liquid phase at 55°C. Among the zeolites studied, NaY has the highest saturation sorption capacity for the sulfur compounds. The overall heat of adsorption of sulfur compounds in a hexadecane solution was measured at 30°C using a flow microcalorimeter. A linear correlation between the heat of adsorption and the amount of S adsorbed was found for NaY. Competitive adsorption using a mixture of anthracene, DBT and quinoline indicates that NaY selectively adsorbs quinoline while anthracene and DBT have similar affinity to NaY. Liquid flow calorimetry combined with the analysis of the effluent from the calorimeter is a promising technique to aid the development of selective sorbents for S removal and other sorption processes since it provides information on the relative heats of adsorption, the sorption capacity and the breakthrough curves.
F.T.T. Ng, A. Rahman, T. Ohasi, M. Jiang, Applied Catalysis B: Environmental 56 (2005) 127-136

B1785 – Comparative study of trimethyl phosphite and trimethyl phosphate as electrolyte additives in lithium ion batteries

Safety concerns of lithium ion batteries have been the key problems in their practical applications. Trimethyl phosphite (TMP(i)) and trimethyl phosphate (TMP(a)) were used as the electrolyte additives to improve the safety and electrochemical performance of lithium cells. Gallvanostatic cell cycling, flammability test and thermal stability measurements by means of accelerated rate calorimeter (ARC) and micro calorimeter were performed. It is found that both TMP(i) and TMP(a) reduce the flammability of the electrolyte. The TMP(i) additive not only enhances the thermal stability of the electrolyte, but also improves its electrochemical performance. The TMP(a) additive can improve the thermal stability of the electrolyte at the expense of some degree of degradation of its electrochemical performance. Therefore, TMP(i) is a better flame retardant additive in the electrolyte compared with TMP(a).
X.L. Yao, S. Xie, C.H. Chen, Q.S. Wang, J.H. Sun, Y.L. Li, S.X. Lu, Journal of Power Sources 144 (2005) 170-175

B1770 – Comparisons of graphite and spinel Li1.33Ti1.67O4 as anode materials for rechargeable lithium-ion batteries

The aim of this work was to compare the electrochemical behaviors and safety performance of graphite and the lithium titanate spinel Li1.33Ti1.67O4 with half-cells versus Li metal. Their electrochemical properties in 1MLiPF6/EC + DEC (1:1 w/w) or 1MLiPF6/PC + DEC (1:1 w/w) at room and elevated temperatures (30 and 60°C) have been studied using galvanostatic cycling. At 30°C graphite has higher reversible capacity than Li1.33Ti1.67O4 when using the LiPF6/EC + DECas electrolyte. At 60°C graphite declines in cell capacity yet Li1.33Ti1.67O4 remains almost unchanged. In a propylene carbonate (PC) containing electrolyte, graphite electrode exfoliates and loses its mechanical integrity while Li1.33Ti1.67O4 electrode is very stable. An accelerating rate calorimeter (ARC) and microcalorimeter have been used to compare the thermal stability of lithiated lithium titanate spinel and graphite. Results show that Li1.33Ti1.67O4 may be used as an alternative anode material offering good battery performance and higher safety.
X.L. Yao, S. Xie, C.H. Chen, Q.S. Wang, J.H. Sun, Y.L. Li, S.X. Lu, Electrochimica Acta 50 (2005) 4076-4081

B1741 – Synthesis of phosphorous sulfide solid electrolyte and all-solid-state lithium batteries with graphite electrode

"A P2S5-based solid electrolyte (30P2S5-70Li2S) was synthesized from the rapidly quenched glassy counterpart by heat treatment. The 30P2S5-70Li2S solid electrolyte showed a high lithium-ion conductivity of about 1.0 10 3 S cm 1 at room temperature. Graphite showed reversible electrode reaction in the electrolyte A solid-state battery with the 30P2S5-70Li2S glass-ceramics, LiCoO2, and graphite as an electrolyte, a cathode, and an anode, respectively, showed steady charge-discharge cycling."
Y. Seino, K. Takada, B.-C. Kim, L. Zhang, N. Ohta, H. Wada, M. Osada, T. Sasaki, Solid State Ionics 176 (2005) 2389 - 2393

B1656 – Thermal decomposition of ammonia-borane under pressures up to 600 bar

The thermal decomposition of ammonia-borane BH3NH3 in the temperature range up to 450 K has been studied by differential scanning calorimetry (DSC) and volumetric analysis of the released volatile decomposition products. Measurements were performed in a transitiometer ST6-VI under pressures up to 600 bar and in a DSC C-80 in the pressure range 1-100 bar hydrogen. Above 360 K ammonia-borane undergoes an exothermic decomposion, which proceeds in two steps with rising temperature. The decomposition is accompanied by hydrogen release. Formation of further volatile products, beside hydrogen, seems to be negligible. The heat evolution and hydrogen release terminates near 430 K. The final amount of released hydrogen is approximately equal to 2 mol H2/mol ammonia-borane. Variation of pressure does not influence significantly the reaction enthalpy and hydrogen release. The transitiometer ST6-VI is well-suitable for the monitoring of solid-gas reaction under high-pressure conditions. This instrument enables a reliable determination of the reaction heat and the amount of gas release/gas uptake.
F. Baitalow, G. Wolf, J-P.E. Grolier, F. Dan and S.L. Randzio, Thermochimica Acta 445 (2006) 121-125

B1641 – Thermal stability of LiPF6/EC + DEC electrolyte with charged electrodes for lithium ion batteries

The thermal stabilities of 1 M LiPF6/EC + DEC and with electrodes were studied by calorimetry. The results show that both the electrolyte-Li0.5CoO2 and electrolyte-LixC6 system have lower decomposition onset temperatures than either the separate electrolyte or electrodes. The electrolyte is oxidized by Li0.5CoO2, while its reaction with lithiated graphite occurs because the solid electrolyte interphase (SEI) breaks down at 57°C. The 1 M LiPF6/EC + DEC in air is less stable than in argon, but the reaction is similar.
Q. Wang, J. Sun, X. Yao and C. Chen, Thermochimica Acta 437 (2005) 12-16

B1630 – Hydrogen uptake characteristics of mechanically alloyed mixtures of Ti-Mg-Ni

It has been well established that hydrogen will react directly and reversibly with a large number of metals and alloys to form metallic hydrides. Extensive research has been done over the years to improve properties of these hydrogen storage media and in developing new compounds to use as hydrogen storage media. In the present study, the hydrogen uptake characteristics of mechanically alloyed titanium-magnesium-nickel have been studied. Thermal and composition data obtained for studies carried out using three different ball-to-powder ratios by mass are presented in a discussion of the hydriding properties of mechanically alloyed Ti-Mg-Ni. It was found that up to 11 wt% hydrogen was obtained for a Ti-Mg-Ni mixture that was ball milled at a ball-to-powder ratio by mass of 70:1.
J. K. Lomness, M. D. Hampton and L. A. Giannuzzi, International Journal of Hydrogen Energy 27 (2002) 915-920

B1629 – Water activation of Mg2Ni for hydrogen uptake

Though the alloy, Mg2Ni, has desirable properties for storageof hydrogen, its application has been hindered by the difficulty of its initial activation for hydrogenuptake. A number of methods have been reported for activation of Mg2Ni. While someof these methods utilize aqueous solutions, there has been no report of activation with pure water.It has been demonstrated in this laboratory that magnesium nickel alloy can be activated forhydrogen uptake by treatment with water for as little as 2 min. Increasing the treatment time withwater increases the amount of hydrogen absorbed and increases the longevity of the activation.Thermal data, scanning electron microscopic data, and x-ray photoelectron spectroscopic data arepresented in a discussion of the activation of magnesium nickel alloy with water.
M.D. Hampton and J.K. Lomness, International Journal of Hydrogen Energy 24 (1999) 175-187

B1628 – Effects of various catalysts on hydrogen release and uptake characteristics of LiAlH4

The effects of various catalysts on the hydrogen release characteristics of LiAlH4 were studied. The catalysts were incorporated into the alanate by ball milling. The catalysts studied included elemental titanium, TiH2, TiCl4, TiCl3, AlCl3, FeCl3, elemental iron, elemental nickel, elemental vanadium, and carbon black. Dehydriding/rehydriding properties were characterized by using differential scanning calorimetry coupled with pressure measurement and X-ray diffraction. The addition of TiCl3 and TiCl4 to LiAlH4 eliminated the first step of hydrogen evolution and significantly lowered decomposition temperature of the second step. Doping with elemental iron caused only a slight decrease in the amount of hydrogen released and did not eliminate the first step of hydrogen evolution. Ball milling in the absence of the catalyst was found to decrease the release temperature of hydrogen, while doping with elemental iron did not have any additional effect on the temperature of hydrogen release of LiAlH4.
M. Resan, M.D. Hampton, J.K. Lomness and D.K. Slattery, International Journal of Hydrogen Energy 30 (2005) 1413-1416

B1538 – Surface study of liquid water treated and water vapor treated Mg2.35Ni alloy

Magnesiumnickel alloy (Mg2:35Ni) has been considered an excellent hydrogen storage medium because it has a high hydrogen capacity, forms a very stable hydride, is inexpensive, and it presents no environmental hazards. One of the major problems associated with the use of Mg2:35Ni alloy for hydrogen storage is its initial activation for hydrogen uptake. Earlier work in this laboratory showed that treatment of Mg2:35Ni with either liquid water or water vapor, activates the alloy for hydrogen up-take. In the present study, the surface modi6cation of Mg2:35Ni by liquid water and water vapor is characterized. x-ray photoelectron spectroscopy, and transmission electron microscopy suggest the presence of Mg(OH)2 on the surface. It is believed that this is the 6rst report showing the presence of hydroxides on the surface of an active hydrogen storage alloy.
M.D. Hampton, J.K. Lomness, L.A. Giannuzzi, International Journal of Hydrogen Energy 27 (2002) 79-83

B1477 – Thermoanalytical investigations of hydrogen adsorption on carbon materials

The hydrogen adsorption on carbon nanofibers of different origin was investigated by thermogravimetric measurements at temperatures between -10 and 25°C and pressures up to 140 bar. The applied gravimetric apparatus yields a distinctly higher precision, compared to volumetric and calorimetric methods. All investigated carbon nanofibers show a hydrogen uptake below 0.3 wt.% independently from sample pretreatment.
E. Henneberg, B. Bernhardt, K. Bohmhammel, Thermochimica Acta 415 (2004) 43-45

B1175 – Thermochemical investigations on borazane (BH3-NH3) in the temperature range from 10 to 289 K.

The molar heat capacity of borazane BH3-NH3 was determined in the 10-289 K range. Two different adiabatic calorimeter systems, each using the classical heat-step method, were applied for the measurements. The molar standard entropy of borazane at T=298.15 K was determined to be S°=96.34 J K-1 mol-1. For the phase transition at T=224 K, a transition entropy of ?S=6.87 J K-1 mol-1 was calculated from the heat capacity data. The results of X-ray powder diffraction confirm an order-disorder transition with a change of the lattice structure from orthorhombic to tetragonal. From low-temperature differential scanning calorimetry, a transition enthalpy of ?H=1.34 kJ mol-1 was found, the transition enthalpy derived from the heat capacity is ?H=1.48 kJ mol-1
G. Wolf, J.C. van Miltenburg, U. Wolf, Thermochimica Acta 317 (1998) 111-116

B1147 – Kinetic investigations on the basis of isothermal DSC measurements of hydrogenation and dehydrogenation of magnesium hybride

Results of kinetic investigations on the basis of isothermal DSC measurements by means of defined pressure changes are presented and interpreted for the Mg/MgH2 system. From an evaluation of the experimentally obtained DSC-signals, the dependence of reaction rate on hydrogen pressure p0, temperature and sample morphology could be described. Under certain conditions, it is possible to visualise individual rate-determining steps and, thus, to arrive at conclusions on the reaction mechanism.
K. Bohmhammel, B. Christ and G. Wolf, Thermochimica Acta 310 (1998) 167-171

B0637 – Calorimetric study of some carboxylic acids lewis-bases complexes in view of thermal energy storage.

This paper studies the equilibrium reaction between acetic acid and triethylamine induced by the formation of an H-bonded complex. These compounds were used as bulk reagents to form a complex in the liquid state. This type of reaction can be used in thermochemical energy storage at low temperature (from ambient temperature up to 423 K) and atmospheric pressure. Only one storage tank is required: the formation of the H-bond is an exothermic process, and this bond can be broken by heat absorption. Physical and thermodynamic parameters were determined by means of a Calvet calorimeter and a DSC 111 differential scanning calorimeter.
L. Elegant, M. Salman and Y. Schwob, Thermochimica Acta 130 (1988) 149-154

B0520 – Thermal storage energy by hydrogen bonding and phase change materials

L. Elegant, M. Salman, H. Schwob, AICAT, Ferrara, (1986) 309-313

A2274 – Study of the diffusion kinetics and mechanism of electrochemical hydriding of Mg-Ni-Mm alloys

Electrochemical hydriding in a 6 M KOH solution at 20 and 80 °C for 480 min was applied on a series of as-cast binary Mg–Ni and ternary Mg–Ni–Mm alloys (Mm = mischmetal containing 45% Ce, 38% La, 12% Nd and 4% Pr) containing 11–24 wt. % Ni and 0–6 wt. % Mm. The kinetics and mechanism of the hydriding process, as well as hydrogen release temperatures, were studied by glow discharge spectrometry hydrogen profiling, scanning electron microscopy, energy dispersion analysis, X-ray diffraction and mass spectrometry. A maximum hydrogen concentration of 1.1% was achieved in the eutectic MgNi24Mm5 alloy hydrided at 80 °C. In all cases, the main hydriding product was binary MgH2 hydride. Mass spectrometry revealed its destabilization due to Ni and Mm because its decomposition temperature was lowered by about 100 °C. Both nickel and mischmetal showed positive effects on hydriding and dehydriding kinetics. These effects are discussed in relation to the hydriding mechanism, electronic structure and atomic size of additives and structural variations of the alloys. Based on the H-concentration profiles, the diffusion coefficients of hydrogen were estimated. For the eutectic MgNi24Mm5 alloy, the H diffusion coefficient at 20 °C was 4 · 10?10 cm2 s?1.
D. Vojtech, V. Knotek, International Journal of Hydrogen Energy 36 (2011) 6689-6697

A2252 – Effect of nitride additives on LieNeH hydrogen storage system

Solid state reaction between LiNH2 and LiH potentially offers a practical pathway for hydrogen supply to fuel cell powered vehicles, particularly if the reaction kinetics can be further improved. Here we performed a comparative study of the effects of selected micron and nano-sized nitrides using temperature programmed desorption, mass spectrometry, X-ray diffraction and infrared spectroscopy. It was found that both micron and nano-sized BN and TiN act as effective catalysts within the system. While an increase in the concentration of TiN reduces dehydrogenation temperature, the opposite was observed for BN catalyst. Employment of both nano and micron-sized BN catalysts resulted in an almost similar dehydrogenation temperature; but dehydrogenation temperature was decreased about 20 °C by switching from micron to nano-sized TiN. The catalytic effects of the additives were proposed to be an improvement of surface reactivity and diffusion enhancement across the interface of the reactants. However, the role of BN and TiN are different in the way that TiN is likely to improve the surface reactivity of LiNH2, while BN mainly enhances diffusion across the interface of the reactants. Our findings also indicate that TiCl3 behaves like TiN, as a catalyst in Li?N?H system.
Shahrouz Nayebossadri, Kondo Francois Aguey-Zinsou, Z. Xiao Guo, International Journal of Hydrogen Energy 36 (2011) 7920-7926

A2219 – MgxMn(1 x)(BH4)2 (x = 0–0.8), a cation solid solution in a bimetallic borohydride

A solid solution of magnesium and manganese borohydrides was studied by in situ synchrotron radiation X-ray powder diffraction and infrared spectroscopy. A combination of thermogravimetry, mass and infrared spectroscopy, and atomic emission spectroscopy were applied to clarify the thermal gas desorption of pure Mn(BH4)2 and a solid solution of composition Mg0.5Mn0.5(BH4)2. MgxMn(1 x)(BH4)2 (x = 0–0.8) conserves the trigonal structure of Mn(BH4)2 at room temperature. Manganese is dissolved in the hexagonal structure of a-Mg(BH4)2, with the upper solubility limit not exceeding 10 mol.% at room temperature. There exists a two-phase region of trigonal and hexagonal borohydrides within the compositional range x = 0.8–0.9 at room temperature. Infrared spectra show splitting of various vibrational modes, indicating the presence of two cations in the trigonal MgxMn(1 x)(BH4)2 solid solutions, as well as the appearance of a second phase, hexagonal a-Mg(BH4)2, at higher magnesium contents. All vibrational frequencies are shifted to higher values with increasing magnesium content. The decomposition temperature of the trigonal MgxMn(1 x)(BH4)2 (x = 0–0.8) does not vary significantly as a function of the magnesium content (433–453 K). The desorbed gas contains mostly hydrogen and 3–7.5 mol.% diborane B2H6, as determined from analyses of the Mn(BH4)2 and Mg0.5Mn0.5(BH4)2 samples. An eutectic relation between a-Mg(BH4)2 and LiBH4 is observed. The solid solution MgxMn(1 x)(BH4)2 is a promising material for hydrogen storage as it decomposes at a similar temperature to Mn(BH4)2, i.e. at a much lower temperature than pure Mg(BH4)2 without significantly losing hydrogen weight capacity thanks to substitution of Mn by Mg up to 80 mol.%. The questions of diborane release and reversibility remain to be addressed.
Radovan Cerny, Nicolas Penin, Vincenza D’Anna, Hans Hagemann, Etienne Durand, Jakub Ruzicka, Acta Materialia 59 (2011) 5171–5180

A2158 – Structural and magnetic properties of RMn2?xFexD6 compounds (R=Y, Er; x?0.2) synthesized under high deuterium pressure

RMn2?xFexD6 compounds were obtained by applying a deuterium pressure of several kbar to RMn2?xFex compounds for x?0.2 and R=Y, Er. These compounds are isostructural to RMn2D6 compounds and crystallize in a K2PtCl6 type structure with a random substitution of R and half the Mn atoms in the same 8c site whereas the other Mn atoms are located on the 4a site and surrounded by six D atoms (24e site). According to neutron powder diffraction analysis the Fe atoms are preferentially substituted on the 4a site. YMn2?xFexD6 compounds are paramagnetic and their molar susceptibility follows a modified Curie–Weiss law. ErMn2?xFexD6 compounds display a ferromagnetic behavior at 2 K, but their saturation magnetization (MS?4.0 ?B/f.u.) is half that of their parent compounds (MS?8.0 ?B/f.u.). The neutron diffraction patterns of ErMn1.8Fe0.2D6 display below 13 K both ferromagnetic and antiferromagnetic short range order, which can be related to a disordered distribution of Er moments. The paramagnetic temperatures of ErMn2?xFexD6 compounds are negative and decrease versus the Fe content whereas they are positive and increase for their parent compounds.
V. Paul-Boncour, S.M.Filipek, R.Sato, R.Wierzbicki, G.André, F.Porcher, M. Reissner, G.Wiesinger, Journal of Solid State Chemistry 184 (2011 )463–469

A2155 – Catalytic investigation of ceria-zirconia solid solutions for solar hydrogen production

This study addresses the solar thermochemical production of hydrogen from water-splitting cycles using ceria-zirconia solid solutions prepared via soft chemistry methods. The effect of zirconium doping on the catalytic activity of ceria for hydrogen production was studied using thermogravimetric analysis. The influence of the zirconium content between 10% and 50% on the redox properties of the Ce1??Zr?O2 material was investigated. The higher the amount of zirconium, the higher the reduction yields. The reduction yield at 1400 °C in inert atmosphere was 9% for 10% Zr, 16% for 25% Zr, and 28% for 50% Zr. However, increasing the Zr content did not automatically lead to the highest amount of hydrogen produced during cycling. Indeed, the powder with 25% Zr produced 334 and 298 ?mol H2/g at 1050 °C during the first and the second cycle, respectively. In contrast, the powder with 50% Zr yielded 468 and 266 ?mol H2/g during the two successive cycles. Moderate Zr contents thus favored H2 production during repeated cycles without any significant reactivity losses. A kinetic study of the reduction and the hydrolysis steps was proposed. The activation energies for the thermal reduction and the hydrolysis of Ce0.75Zr0.25O2 were 221 kJ/mol and 51 kJ/mol, respectively. Finally, the use of a template molecule during synthesis was considered, which improved the reduction yield markedly (up to 52%) but strong sintering phenomena limited the hydrogen production and the material cyclability.
Alex Le Gal, Stéphane Abanades, International journal of hydrogen energy 36 (2011) 4739-4748

A2091 – Hydrogen production from NaBH4 hydrolysis via Co-ZIF-9 catalyst

ZIF-9, one of the zeolitic imidazolate frameworks, was synthesized via solvothermal method and the feasibility of ZIF-9 as catalyst in NaBH4 hydrolysis for hydrogen production was firstly reported in detail. The experimental result showed that initial hydrogen generation rate of ZIF-9 catalyst is relatively slow due to the gradual formation of CoB active centers. And then the hydrogen generation rate increases rapidly after the formation of CoB. The hydrogen generation rate of ZIF-9 at 40 °C can reach up to 3641.69 ml min? 1 g? 1(Co). It was found that the addition of NaOH can remarkably accelerate the hydrolysis rate of NaBH4. In the cycles of ZIF-9, no obvious decrease of hydrogen production rate was found which meant that ZIF-9 catalyst maintains relatively high stability. The XRD comparison before and after the cycling reaction showed that ZIF-9 maintains its basic crystal structure and crystallinity, but long range order of ZIF-9 catalyst is altered in a certain extent.
Qiming Li, Hern Kim, Fuel Processing Technology 100 (2012) 43–48

A1971 – KOH activated lignin based nanostructured carbon exhibiting high hydrogen electrosorption

Carbon materials capable of efficient hydrogen electrosorption at ambient conditions can be used for negative electrode material in chemical power sources, competitive for metallic hydride alloys. This paper describes physical, chemical and electrochemical properties of active carbon (LAC) produced from lignin processed by standard carbonization and KOH activation at temperature of 950 C. Microporous carbon with BET surface of 1946m2/g obtained in such conditions has a complex porous structure with a considerable number of supermicropores and small mesopores (ca. 50%). As a result, efficient hydrogen electrosorption of 510 mA h/g (1.89 wt% in meaning of energy storage) is obtained and favorable discharge characteristics at current densities up to 1 A/g.
K. Babe?, K. Jurewicz, Carbon 46 (2008) 1948-1956

A1969 – Hydrogen adsorption on Pd-modified carbon nanofibres: Influence of CNF surface chemistry and impregnation procedure

Different carbon nanofibre (CNF) based materials (parent, oxidized, and impregnated with a palladium loading of 1 wt.% using different procedures) have been tested for hydrogen storage at ambient pressure. Parent CNF are completely free of oxygen surface groups, whereas treatment in nitric acid increases mainly the amount of surface anhydrides groups. Add to the surface functionalization, the solvent employed in the palladium impregnation was also varied, using both aqueous and organic precursor solutions. Thermogravimetric analyses of the hydrogen adsorption–desorption cycles suggest that the presence of theses functional groups hinders the adsorption. Concerning the presence of palladium, its influence strongly depends on the previous activation of the surface and on the solvent used for the palladium addition. The use of aqueous precursors and functionalized CNFs leads to increases in the adsorption capacity close to 100% compared to the parent CNF (12.6 vs. 6.7 cm3/g).
Eva D?az, Marta Leon, Salvador Ordonez, International Journal of Hydrogen Energy, 35 (2010) 4576-4581

A1949 – From micro- to nano-size catalytic membrane hydrogenation reactors with accumulated hydrogen

Preconditions and prospects of development of the new generation nano-sized membrane reactors are studied in this work. In such reactors hydrogenation reactions will be performed for the first time in the pores of ceramic membranes actively employing hydrogen which is preliminarily adsorbed in mono- and multilayered oriented carbon nanotubes with graphene walls (OCNTG) formed on the inner surface of pores. It is shown with the use of microfiltration membranes “TRUMEM” (Daverage e 130 nm) that reactions of CO oxidation (over a Cu0,03Ti0,97O(2±?) catalyst) and oxidative conversion of methane to synthesis gas and light hydrocarbons (over La + Ce/MgO) are significantly intensified when membranes are used. Almost the same value of methane conversion as in a flow reactor is reached in a membrane catalytic module at temperatures which are lower by 100-170°C. Investigation of hydrogen adsorption, storage and desorption regularities in nano-sized membrane reactors was performed via forming of OCNTG in the pores of ultrafiltration membranes “TRUMEM” (Daverage ¼ 50 nm and 90 nm) and their saturation with hydrogen under 10-13 MPa. It is found that the amount of adsorbed hydrogen reached 14.0% of OCNTG weight. Adsorption of hydrogen in OCNTG is characterized for the first time by thermogravimetric analysis (TGA) coupled with mass-spectrometric analysis. Hydrogen desorption under atmospheric pressure occurs ate175 C. Adsorptivity to hydrogen of three carbon structures, nanocrystallites of pyrocarbon (NCP), their superposition, and OCNTG, is studied. It is found that this property is characteristic only for the latter structure. A new effect of hydrogen variation of performance (HVP) is found: hydrogen adsorbed in OCNTG affects the transport properties of membranes decreasing their performance on liquids 4-26-fold which confirms high activity of hydrogen indirectly, the dissociative mechanism of hydrogen adsorption being probably the basis.
A.P. Soldatov, M.V. Tsodikov, V.Yu. Bichkov, O.P. Parenago, V.N. Korchak, V.V. Teplyakov, International Journal of Hydrogen Energy 36 (2011) 1264-1270

A1935 – Ni- and Fe-based catalysts for hydrogen and carbon nanofilament production by catalytic decomposition of methane in a rotary bed reactor

Four catalysts, consisting of Ni, Ni:Cu, Fe or Fe:Mo as the active phase and Al2O3 or MgO as a textural promoter, were tested for the catalytic decomposition of methane in a rotary bed reactor, obtaining both CO2-free hydrogen and carbon nanostructures in a single step. Hydrogen yields of up to 14.4 Ndm3 H2·(h·gcat)?1 were obtained using the Ni-based catalysts, and methane conversions above 80% were observed with the Fe-based catalysts. In addition to hydrogen production, the Ni-based catalysts allowed the large-scale production of fishbone-like carbon nanofibres, whereas the use of the Fe-based catalysts promoted the production of carbonaceous filaments having a high degree of structural order, consisting of both chain-like carbon nanofibres and carbon nanotubes.
J.L. Pinilla, R. Utrilla, M.J. Lázaro, R. Moliner, I. Suelves, A.B. García, Fuel Processing Technology 92 (2011) 1480–1488

A1934 – Metallic and carbonaceous ebased catalysts performance in the solar catalytic decomposition of methane for hydrogen and carbon production

Solar catalytic decomposition of methane (SCDM) was investigated in a solar furnace facility with different catalysts. The aim of this exploratory study was to investigate the potential of the catalytic methane decomposition approach providing the reaction heat via solar energy at different experimental conditions. All experiments conducted pointed out to the simultaneous production of a gas phase composed only by hydrogen and un-reacted methane with a solid product deposited into the catalyst particles varying upon the catalysts used: nanostructured carbons either in form of carbon nanofibers (CNF) or multiwalled carbon nanotubes (MWCNT) were obtained with the metallic catalyst whereas amorphous carbon was produced using a carbonaceous catalyst. The use of catalysts in the solar assisted methane decomposition present some advantages as compared to the high temperature non-catalytic solar methane decomposition route, mainly derived from the use of lower temperatures (600e950 C): SCDM yields higher reaction rates, provides an enhancement in process efficiency, avoids the formation of other hydrocarbons (100% selectivity to H2) and increases the quality of the carbonaceous product obtained, when compared to the non-catalytic route.
J.L. Pinilla, D. Torres, M.J. Lazaro, I. Suelves, R. Moliner, I. Canadas, J. Rodr?guez, A. Vidal, D. Mart?nez, International Journal of Hydrogen Energy 37 (2012) 9645-9655

A1933 – Characterization of nanofibrous carbon produced at pilot-scale in a fluidized bed reactor by methane decomposition

Carbon nanofibers (CNFs) production in the range of hundreds of grams per day has been achieved in a fluidized bed reactor (FBR) by methane decomposition using a nickel based catalyst. The characterization of the carbon produced at different operating conditions (temperature, space velocity and the ratio of gas flow velocity, uo, to the minimum fluidization velocity, umf) has been accomplished by means of X-ray diffraction (XRD), N2 adsorption, temperature-programmed oxidation (TPO), scanning electron microscope (SEM) and transmission electron microscopy (TEM). It has been concluded that the structural and textural properties of the CNFs obtained in the FBR are analogous to the ones obtained in a fixed bed reactor at a production scale two orders of magnitude lower. Thus, FBR can be envisaged as a promising reaction configuration for the catalytic decomposition of methane (CDM), allowing the production of high quantities of CNFs with desirable structural and textural properties.
J.L. Pinilla, M.J. Lázaro, I. Suelves, R. Moliner, J.M. Palacios, Chemical Engineering Journal 156 (2010) 170–176

A1926 – A metal dusting process for preparing nano-sized carbon materials and the effects of acid post-treatment on their hydrogen storage performance

The preparation of various nano-sized carbon materials (NCMs) using a metal dusting process, in which a stainless steel coupon and CO–CO2 mixed gas are the only reactants needed, is demonstrated in this study. During the process, fresh Fe–Ni nano-particles, which catalyze the formation of the NCMs, are produced spontaneously and continuously from the steel. The possibility of using multi-wall carbon nanotubes (CNTs) prepared at 600°C as a hydrogen storage material is studied. Our electrochemical testing results indicate that the obtained CNTs have a hydrogen discharge capacity of as high as 104 mAh/g after being etched in 15 M boiling nitric acid solution for 4 h. However, it was found that prolonging the etching time not only decreases crystallinity but also damages the tubular structure of the CNTs, degrading the hydrogen storage performance.
Jeng-Kuei Chang, Heng-Yi Tsai, Wen-Ta Tsai, International Journal of Hydrogen Energy, 33 (2008) 6734-6742

A1399 – Metal sulfate water-splitting thermochemical hydrogen production cycles

A compilation of 350 thermochemical cycles to split water and the subsequent assessment of these cycles has pointed to several metal sulfate cycle as viable candidate cycles with high thermal efficiency. However, studies of the hydrogen generation step in two of the cycles showed alternate side reactions that make this class of metal sulfate cycles a poor candidate for further study.
Barry W. McQuillan, Gottfried E. Besenbruch, Lloyd E. Brown, Roger A. Rennels, Bunsen Y. Wong,

A1365 – Thermal decomposition of polymeric aminoborane (H2BNH2)x under hydrogen release

Polymeric aminoborane (H2BNH2)x has been isolated during the thermal decomposition of solid borazane H3BNH3 at temperatures below 370 K. Polymeric aminoborane is a white noncrystalline solid, stable at room temperature and up to 380 K. In the temperature range of 380–500K polymeric aminoborane undergoes a thermal decomposition, which was studied by differential scanning calorimetry (DSC), by thermogravimetry (TG) and by volumetric measurements. The solid residuewas characterized by IR spectroscopy, by powder X-ray diffraction (XRD) analysis and by solid state 11B NMR spectroscopy. The thermal decomposition of polymeric aminoborane (H2BNH2)x is an exothermic process accompanied by evolution of nearly 1 mol hydrogen per mole H2BNH2 unit corresponding to the volumetric measurements. The detected mass loss of the solid phase indicates the formation of further gaseous products beside hydrogen. The final mass loss increases with rising heating rate, in contrast to the final amount of evolved hydrogen, which still remains constant
J. Baumann , F. Baitalow, G. Wolf, Thermochimica Acta 430 (2005) 9–14

A1338 – Mechanical alloying and electronic simulations of (MgH2+M) systems (M=Al, Ti, Fe, Ni, Cu and Nb) for hydrogen storage

Mg-based alloys are promising candidates for hydrogen storage applications. Here, mechanical alloying (MA) was used to process powder mixtures of MgH2 with 8 mol% M (M = Al, Ti, Fe, Ni, Cu and Nb) in order to modify hydrogen storage properties of the Mg hydride. Electronic simulations of the systems were carried out to clarify the mechanisms of the alloy effects. X-ray di:raction (XRD) of the milled samples revealed the formation of new phases: a bcc solid solution phase for the (MgH2 + Nb) mixture; TiH2 phase for the (MgH2 + Ti); and MgCu2 phase for the (MgH2 + Cu). For all the mixtures, a high-pressure phase, gamma-MgH2, was also identified after mechanical alloying. Further qualitative and quantitative phase analyses were carried out using the Rietveld method. Scanning electron microscopy (SEM) of the milled powder clearly showed substantial particle size reduction after milling. Dehydrogenation at 300°C under vacuum shows that the (MgH2+Ni) mixture gives the highest level of hydrogen desorption and the most rapid kinetics, followed by MgH2 with Al, Fe, Nb, Ti and Cu. Theoretical predictions show that the (MgH2 + Cu) system is the most unstable, followed by (MgH2 + Ni), (MgH2 + Fe), (MgH2 + Al), (MgH2 + Nb), (MgH2 + Ti). The predicted alloying effects on the stability of MgH2 generally agree with the experimentally observed change in the hydrogen desorption capacity. The di:erences were discussed in the text.
C.X. Shang, M. Bououdina, Y. Song, Z.X. Guo, International Journal of Hydrogen Energy 29 (2004) 73-80

A1274 – Zr-substitution in LaNi5-type hydride compound by room temperature ball milling

High-energy ball milling at room temperature has been used to prepare the pseudo-binary compound La(1-x)ZrxNi5 (x = 0.5) in amorphous state. The stability of this phase has been investigated by XRD, DSC and DTA. It starts to crystallise into single-phase La0.5Zr0.5Ni5 alloy at 361°C and undergoes decomposition into LaNi5 and ZrNi5 above 670°C. Pressure-composition isotherm (PCI) curves of hydrogen absorption have been measured for crystalline La0.5Zr0.5Ni5 alloy and are compared to that of the binary LaNi5 and ZrNi5 compounds.
E. Msika, M. Latroche, F. Cuevas, A. Percheron-Guégan, Materials Science and Engineering B108 (2004) 91-95

A1061 – A comparative study of the Ruddlesden-Popper series, La(n+1)Ni(n)O(3n+1) (n=1, 2 and 3), for solid-oxide fuel-cell cathode applications

A comparative investigation of the much-studied La2NiO(4+d) (n=1) phase and the higher-order Ruddlesden-Popper phases, La(n+1)Ni(n)O(3n+1) (n=2 and 3), has been undertaken to determine their suitability as cathodes for intermediate-temperature solid-oxide fuel cells. As n is increased, a structural phase transition is observed from tetragonal I4/mmm in the hyperstoichiometric La2NiO4.15 (n=1) to orthorhombic Fmmm in the oxygen-deficient phases, La3Ni2O6.95 (n=2) and La4Ni3O9.78 (n=3). High temperature d.c. electrical conductivity measurements reveal a dramatic increase in overall values from n=1, 2 to 3 with metallic behavior observed for La4Ni3O9.78. Impedance spectroscopy measurements on symmetrical cells with La0.9Sr0.10Ga0.80Mg0.20O3-d (LSGM-9182) as the electrolyte show a systematic improvement in the electrode performance from La2NiO4.15 to La4Ni3O9.78 with ~ 1 ? cm2 observed at 1073 K for the latter. Long-term thermal stability tests show no impurity formation when La3Ni2O6.95 and La4Ni3O9.78 are heated at 1123 K for 2 weeks in air, in contrast to previously reported data for La2NiO4.15. The relative thermal expansion coefficients of La3Ni2O6.95 and La4Ni3O9.78 were found to be similar at ~ 13.2 x 10^(-6) K-1 from 348 K to 1173 K in air compared to 13.8 x 10^(-6) K-1 for La2NiO4.15. Taken together, these observations suggest favourable use for the n=2 and 3 phases as cathodes in intermediate-temperature solid-oxide fuel cells when compared to the much-studied La2NiO4+d (n=1) phase.
G. Amow, I.J. Davidson, S.J. Skinner, Solid State Ionics 177 (2006) 1205-1210

A0943 – Effects of iron oxide (Fe2O3, Fe3O4) on hydrogen storage properties of Mg-based composites

When magnesium powder containing small additions of certain multiple valence transition metal oxides (TMOs) is ball milled in hydrogen, the hydrogenated Mg-based product can show remarkable improvements in hydrogen absorption/desorption properties. Using a magnetically controlled Uni-Ball-Mill, small amounts of the iron oxides, Fe2O3 and Fe3O4, were ball milled with Mg powder in a hydrogen atmosphere (Mg to Fe atomic ratio; 20:1). Milling products as well as samples used in hydrogen absorption/desorption experiments were characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. TG analysis combined with DSC revealed a higher hydrogen storage capacity for the Mg+ Fe2O3 +H2-milled product (6 wt% H) compared with 5 wt% H for Mg+ Fe3O4 +H2. XRD revealed that during heating, both iron oxides were reduced to pure Fe, a result not previously reported for similar materials milled using different milling devices. For both samples, there was little difference found in the decomposition temperature of the as-prepared MgH2 and rehydrogenated composites. However, storage capacity degradations were observed for the rehydrogenated composites (4 wt%Hstorage capacity for MgH2 +Fe2O3 and 4.4 wt%Hfor MgH2 +Fe3O4). The higher capacity degradation of rehydrogenated MgH2 +Fe2O3 composite is also believed to be a result of the reduction reaction, during which more magnesium was consumed than was consumed by the same amount of Fe3O4. The results also were related to the particular ball-milling equipment and low-energy shearing milling mode employed, which promoted the development of a nanostructural hydride product which subsequently changed structure significantly during the first desorption cycle.
Z.G. Huang, Z.P. Guo, A. Calka, D. Wexler, C. Lukey, H.K. Liu, Journal of Alloys and Compounds 422 (2006) 299-304

A0891 – Ca-Na-N-H system for reversible hydrogen storage

Ca-Na-N-H system was introduced and evaluated in this paper for reversible hydrogen storage. Similar to other amide-hydride systems already reported, interaction between Ca(NH2)2-NaH (1/1) was observed in the temperature range of 120-270°C with 1.1 wt% of hydrogen desorption, from which 0.96 wt% of hydrogen can be recharged. XRD and FTIR identified NaNH2 and Ca-N-H solid solution as dehydrogenation products. Concurrent with hydrogen absorption/desorption transformation between -NH and -NH2 units within solid solution was observed.
Z. Xiong, G. Wu, J. Hu, P. Chen, Journal of Alloys and Compounds 441 (2007) 152-156

A0515 – Nanostructured C6B: A Novel Boron Rich Carbon For H2 Storage

We are proposing that a novel carbon, C6B, having a significantly large boron concentration (17 at %) in the lattice can be synthesized into novel carbon microstructures (keying on nanotubes). The unique nanostructure is one that is crenellated or puckered along the tube axis due the presence of these large boron concentrations. We are proposing to undertake a study in which these novel carbons are synthesized, H2 adsorption is measured and the mechanisms of adsorption are studied. We are also proposing that on the basis of this understanding the synthesis of these novel carbons can be scaled to allow for a commercially viable and responsive H2 storage material.
L.E. Jones, A. Cormack, J. Shelby, M. Lake and J. Howe