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82 articles found

L0162 – Application of LIBS and TMA for the determination of combustion predictive indices of coals and coal blends

Presented work brings results of Laser-Induced Breakdown Spectroscopy (LIBS) and Thermo-Mechanical Analysis (TMA) of coals and coal blends used in coal fired power plants all over Spain. Several coal specimens, its blends and corresponding laboratory ash were analyzed by mentioned techniques and results were compared to standard laboratory methods. The indices of slagging, which predict the tendency of coal ash deposition on the boiler walls, were determined by means of standard chemical analysis, LIBS and TMA. The optimal coal suitable to be blended with the problematic national lignite coal was suggested in order to diminish the slagging problems. Used techniques were evaluated based on the precision, acquisition time, extension and quality of information they could provide. Finally, the applicability of LIBS and TMA to the successful calculation of slagging indices is discussed and their substitution of time-consuming and instrumentally difficult standard methods is considered.
T. Ctvrtnickova, M.P. Mateo, A. Ynez, G. Nicolas, Applied Surface Science 257 (2011) 5447–5451

L0123 – A Novel tool for assessing slagging propensity of coals in PF boilers

Over the years, wide ranges of testing and evaluating procedures have been developed to predict plant performance. Some of the conventional test results and empirical ratios generated out of it offer poorer predictive capability for slagging behaviour experienced in power plants. For better understanding of the coal properties related to slagging problems, a new coal characterization index based on thermo-mechanical analysis (TMA) has been developed in Research and Development Laboratory, BHEL, Tiruchirapalli. A new sampling set up has been designed to carry out shrinkage measurements using TMA. Coal samples collected from various Indian power plants are evaluated. The shrinkage profile of the ash specimen was recorded and characteristic data from the profile were taken for further calculations. Based on proximate analysis, calorific value of the fuels and the shrinkage data of the ash, a new slagging propensity index was proposed. The new index offers better correlation with field observation and hence the new index proposed, offer better predictive capability for understanding the field slagging observations than the conventional indices. The new empirical index can be used as guidelines for relative assessment of coals with respect to slagging, while designing the boiler and tuning the operational parameters.
A. Lawrence, R. Kumar, K. Nandakumar, K. Narayanan, Fuel 87 (2008) 946–950

L0121 – Measurement of the Viscosity of Coal-Derived Slag Using Thermomechanical Analysis

This study describes an experimental technique to determine the viscosity of high-temperature ash samples, using a thermomechanical analysis (TMA) apparatus. The experimental technique was validated at low temperature by measuring the viscosity of a synthetic oil and comparing its viscosity with the calibrated value. Validation at high temperatures was achieved by comparing the measured viscosity of ash samples with the viscosity measurements obtained using a conventional high-temperature rotating bob viscometer. The results indicate that the technique can rapidly provide an indication of the viscosity of slags at high temperatures and could prove to be an alternative, cost-effective technique to current high-temperature ash sample viscosity measurement techniques.
Bart J. P. Buhre, Gregory J. Browning, Rajender P. Gupta, Terry F. Wall, Energy & Fuels, 2005

L0015 – Thermal analysis of coal minerals, ash and slag

J.D. Saxby, S.P. Chatfield, AIE 8th Australian Coal Science Conference (1998) 57-63

B3217 – Prediction of coal stockpile autoignition delay time using micro-calorimeter technique

Spontaneous ignition of coal is one of the major challenges faced by coal industries, which results in a great loss and energy wastage. To evaluate the thermal behavior of coal powder and predict the autoignition delay time (AIDT) of coal stockpile, a C80 micro-calorimeter was employed to detect the thermal behavior of coal at elevated temperature. The reaction heat, reaction order, frequency factor and activation energy of coal were obtained from the experimental data. Based on the Semenov model, the self-heating oxidation temperature (SHOT) and temperature of no return (TNR) were calculated for the 25 kg coal stockpile. Assuming that the coal stockpile is under quasi adiabatic conditions, its AIDT was predicted and compared with the experimental result. The comparison indicates that the micro-calorimeter technique is a useful way to access the safety of coal stockpile, which can be widely used in large scale coal storage and transportation.
Xuejuan Zhao, Qingsong Wang, Huahua Xiao, Zhanli Mao, Peng Chen, Jinhua Sun, Fuel Processing Technology 110 (2013) 86–93

B3086 – The influence of temperature on the adsorption of CTAB on coals

The influence of temperature on the adsorption behavior of the cationic surfactant cetyltrimethyl amonium bromide (CTAB) has been studied. Batch mode was used for the adsorption of CTAB on three different types of coal, namely oxidative altered coal (BO), subbituminous coal (SB) and bituminous coal (BC). Adsorption from aqueous solutions was carried out at 25, 40, 60 and 80 °C. The linear as well as nonlinear regression of experimental data confirmed that the adsorption process can be described using the Langmuir adsorption theory of monolayer coverage. Thus, the equilibrium constant of adsorption could be calculated from the Langmuir binding constant b. Further, thermodynamic parameters such as enthalpy ?Hads, entropy ?Sads and Gibbs energy ?Gads were determined from the dependence of the b constant on temperature. The calculated thermodynamic parameters indicate that the adsorption of CTAB on coals is an exothermic (?Hads < 0) and spontaneous (?Gads < 0) process. It was proved that the adsorption capacity of CTAB on coal increased with a rise in temperature for all the studied samples; the highest adsorption capacity was observed for the oxidative altered coal. Moreover, a close relationship between the adsorption capacity and the critical micelle concentration (CMC) of CTAB has been discovered. In addition, measuring the zeta potential proved that the adsorbed amount of CTAB on the coal surface corresponded to the zeta potential value. Addition of the cationic surfactant (CTAB) affects the value of ?-potential, making the zeta potential values more positive
Roman Marsalek, Jan Pospisil, Boleslav Taraba, Colloids and Surfaces A: Physicochem. Eng. Aspects 383 (2011) 80–85

B3084 – Thermophysical study of sandstone reservoir rocks

Thermal conductivity of both dry and fully water (brine solution, 5 g/l NaCl concentration) saturated rocks have been measured for 35 sandstone core samples obtained from both Hungary and Egypt. Measurements are executed in order to look for thermal anisotropy. The rock porosity, permeability and density were measured beside thermal conductivity, while some correlations were performed in order to differentiate among clayey laminated, flaser bedding and clean sandstone reservoirs. There is a very close correlation among thermal conductivity, rock porosity, bulk density, gas permeability and ultrasonic wave velocities for non laminated clean sandstones, while in banded sandstone reservoirs these relations show more than one trend giving a strong impression indicating the presence of more than one grain–fabric system and/or complex diagenesis. The relationship among the measured thermal conductivity for the core axis, the top and bottom are close and homogeneous for isotropic clean non laminated Szolnok sandstones, while they are vary in a wide range for banded and laminated Bahariya sandstone samples. The measured specific heat capacity indicates that some banded sandstone samples of the Bahariya Formation have bound water appears at 100 °C and giving low specific heat capacity value. This bound water can acted on all petrophysical parameters especially electrical properties. The prediction of specific heat capacity and heat flow from the reservoir temperature is possible using the calculated multi-regression and linear regression models.
Abdel Moktader A. El Sayed, Journal of Petroleum Science and Engineering 76 (2011) 138–147

B3053 – Study of Live Oil Wax Precipitation with High-Pressure Micro-Differential Scanning Calorimetry

For live oils, the effect of pressure (amount of dissolved gas) on the wax appearance temperature (WAT) can be quite pronounced. Here, we describe the use of high-pressure micro-differential scanning calorimetry (HP-?DSC) as an effective technique to determine theWATfor live oils. The effect of increasing equilibration time on WAT is described and compared to predictions from a thermodynamic model
Priyanka Juyal, Tran Cao, Andrew Yen, Rama Venkatesan, Energy Fuels 2011, 25, 568–572

B2974 – Immobilisation of lead(II) ions from aqueous solutions on natural coal. Comparison of calculated and measured adsorption enthalpie

The immobilisation of lead(II) ions from aqueous solutions on natural coal was investigated to compare calculated andmeasured adsorption enthalpies. For this purpose, adsorption isotherms were measured at temperatures of 303, 333 and 353 K. Adsorption enthalpy ?H was evaluated from temperature dependence of the equilibrium constant of adsorption using the van‘t Hoff equation. Thus, the value of ?H = 27 kJ mol-1 was obtained manifesting endothermic effect of lead(II) immobilisation on the coal. However, based on the flow and immersion calorimetric measurements, the exothermic character of lead(II) adsorption on the studied coal was proven with a value of about -7 kJ mol-1.
Boleslav Taraba, J Therm Anal Calorim, 2012

B2773 – Evaluation of pressure on the crystallization of waxes using microcalorimetry

Petroleum composition contains various sizes and quantities of paraffins. Their crystallization and deposition cause many of the problems of oil production. The determination of the wax appearance temperature (WAT) is a useful method of predicting the behavior of oil in production lines. The measured WAT value depends on factors such as: oil composition, thermal history, pressure, measurement technique and cooling rate. There are hardly any studies in the literature that have analyzed the effect of pressure and light fractions on the WAT of oils. Moreover, given the diversity of factors involved in the analysis of the results, the studies that do exist do not enable one to evaluate the effect of light fractions on paraffins with specific sizes and size distributions. This study characterized commercial paraffins with different features according to size and distribution of the molecule size. The paraffins were analyzed using high-pressure microcalorimetry (HPlDSC), and the saturation gas characteristics were varied. The results showed that the fractions heavier than C3, contained in the saturation gas, were more efficient at solubilizing paraffins with lower molar masses. Regarding the commercial paraffins with higher melting points, methane had a solvency that was slightly lower than the blend of gases with the highest levels of fractions[C3.
Lenise C. Vieira, Maria B. Buchuid, Elizabete F. Lucas, J Therm Anal Calorim, 2012

B2729 – Asphaltene phase behavior: prediction at a crossroads

Recent results from SAXS, X-ray transmission, and differential scanning and other calorimetry experiments with neat asphaltenes and asphaltene + hydrocarbon mixtures highlight the structural and behavioral complexity of asphaltenes, however defined, at diverse length scales. Much of this complexity spans the temperature range of importance for reservoir fluid applications, and calls into question many aspects of existing thermodynamic models for them. Apparent heat capacities, for neat asphaltenes, can drop below those of rigid organic crystals revealing the presence of significant exotherms. Of equal importance, typical molecular and submolecular analysis techniques: C13NMR, fluorescence, elemental analysis, ‘molar mass’ do not appear to correlate with asphaltene behaviors in their native oils or in solvent solutions at infinite dilution. Maya and athabasca asphaltenes provide an excellent illustration of this phenomenon. Our understanding of the phase behavior of neat asphaltenes and the behavior of asphaltenes in fluids is at a crossroads.
Yadollah Maham, Martin G. Chodakowski, Xiaohui Zhang, John M. Shaw, Fluid Phase Equilibria 227 (2005) 177–182

B2728 – Asphaltene phase behavior: prediction at a crossroads (II)

Recent results from SAXS, X-ray transmission, and differential scanning and other calorimetry experiments with neat asphaltenes and asphaltene + hydrocarbon mixtures highlight the structural and behavioral complexity of asphaltenes, however defined, at diverse length scales. Much of this complexity spans the temperature range of importance for reservoir fluid applications, and calls into question many aspects of existing thermodynamic models for them. Apparent heat capacities, for neat asphaltenes, can drop below those of rigid organic crystals revealing the presence of significant exotherms. Of equal importance, typical molecular and submolecular analysis techniques: C13NMR, fluorescence, elemental analysis, ‘molar mass’ do not appear to correlate with asphaltene behaviors in their native oils or in solvent solutions at infinite dilution. Maya and athabasca asphaltenes provide an excellent illustration of this phenomenon. Our understanding of the phase behavior of neat asphaltenes and the behavior of asphaltenes in fluids is at a crossroads.
Yadollah Maham, Martin G. Chodakowski, Xiaohui Zhang, John M. Shaw, Fluid Phase Equilibria 228–229 (2005) 21–26

B2664 – A study on spontaneous ignition of bituminous coal

The thermal properties of four bituminous coals were studied using isothermal and temperature-programmed calorimeters, such as a differential thermal analysis, a heat flux calorimeter C80. The corresponding spontaneous ignition was measured in an adiabatic spontaneous ignition tester. It was found that there were weak exothermic activities in bituminous coal at 50-100 °C and meanwhile carbon monoxide and carbon dioxide was generated. These thermal behaviors are responsible for the self heating from 50 °C and spontaneous ignition at 80 °C.
Xin-Rui Li, Hiroshi Koseki, Yusaku Iwata, THERMAL SCIENCE: Vol. 13 (2009), No. 1, pp. 105-112

B2577 – Study of Enhanced Fine Coal De-sulphurization and De-ashing by Ultrasonic Flotation

The feasibility of using ultrasound to enhance the performance of de-sulphurization and de-ashing during slime flotation was investigated. The Setaram C80 calorimeter, the contact angle gauge DCAT21 and an electrophoresis apparatus were used to study the surface nature of coal, pyrite and refuse before and after ultrasonic conditioning. The yield, ash and sulfur contents of equally sized coal slimes were also measured before and after ultrasonic conditioning. The results show that ultrasonic conditioning can drive the separation of pyrite and refuse from coal. After ultrasonic conditioning the hydrophobicity of coal and hydrophilicity of pyrite and refuse increase. The perfect index of flotation, the perfect index of de-sulphurization and the percentage of de-sulphurization increase by 22.51%, 25.36% and 2.49%, respectively. This study shows that ultrasonic conditioning can enhance the performance of de-sulphurization and de-ashing of coal flotation methods.
Kang Wen-ze, Xun Hai-xin, Chen Jun-tao, J China Univ Mining & Technol 2007, 17(3) 358–362

B2467 – Calorimetric investigation of chemical additives affecting oxidation of coal at low temperatures

Interactions in the system “coal–chemical additive–oxygen” were studied at the temperature 30 °C with the aim of recognising inhibitors of the coal oxidation process that are able tomodify the coal surface in a chemical way. Three coals of different ranks were tested. As possible inhibitors, 14 aqueous solutions (10 wt.%) of both inorganic (chlorides, sulphates, nitrates, phosphates, and sulphites) and organic (formates, acetates, urea, and thiourea) substances were examined. The action of additives on coal was evaluated from the heat effect during immersion of the coal in the additive solution. It was found that most of the studied substances proved immersing heats quite comparable with that of pure water. However, rather a chemical action was ascertained for sodium sulphite, phenol, urea and/or thiourea with heat effects several times exceeding heats for pure water. To quantify oxyreactivity of original coals as well as additive-treated ones, oxidation heats were measured by the pulse flow calorimetric method. Urea was found to be the chemically acting additive with the most significant inhibiting efficiency (up to 70%) of coal oxidation at low temperatures.
Boleslav Taraba, Rudolf Peter, Václav Slovák, Fuel Processing Technology 92 (2011) 712–715

B2390 – Urea thermolysis studied under flow reactor conditions using DSC and FT-IR

The thermal decomposition of urea has been studied under flow reactor conditions using a differential scanning calorimeter (DSC) and Fourier transformed infrared spectroscopy (FT-IR). Samples of urea were administered using either a cordierite monolith impregnated with a urea/water solution or a silica cup with a dry urea sample. The samples were heated between 25 and 700 ?C with heating rates of 10 and 20 K/min and the thermal response of the sample and off gas concentrations of ammonia and isocyanic acid were recorded. Biuret and cyanuric acid were decomposed in a separate set of experiments to verify some of the features observed in gas phase data during urea decomposition. Results show that depending on the way the sample is administered, i.e. cup or monolith different behavior in the evolved gases are observed. This is due to different reactions taking place in the vessel induced by the different conditions under which the pyrolysis of urea is preformed.
Andreas Lundström, Bengt Andersson, Louise Olsson, Chemical Engineering Journal 150 (2009) 544–550

B2381 – Effect of Pressure on the Crystallization of Crude Oil Waxes. II. Evaluation of Crude Oils and Condensate

Laboratory analyses of the formation of wax deposits in crude oil are generally performed at atmospheric pressure on stabilized samples without the presence of light components. Therefore, the effects of two important factors that influence the solubility of waxes, namely, light fractions and pressure, are not considered. As a consequence, the results may not reflect what really happens in production lines and equipment. In this work, we evaluated five Brazilian crude oil samples and one condensate, recombined with different gases and under varying pressures, using the high-pressure microcalorimetry technique (HP?DSC). The samples were characterized with regard to the distribution of waxes by the number or carbon atoms to correlate with the results for wax appearance temperature (WAT) and crystallization enthalpy. The results indicate that rising pressure causes the WAT to rise as well and the recombination with gases composed mainly of light hydrocarbons reduces the WAT. Methane has the greatest influence on the oils containing higher amounts of macrocrystalline waxes, an effect that is stronger at higher pressures. Nitrogen does not act as a solvent of the paraffins present, whether of the macro- or microcrystalline type. Fractions lighter than C3, contained in the saturation gas mixtures, are more efficient in the solubilization of waxes, mainly those with lower molar masses. Variations in temperature and enthalpy of crystallization depend upon the pressure, composition of the gas (or mixture of gases), and composition of each crude oil
Lenise C. Vieira, Maria B. Buchuid, Elizabete F. Lucas, Energy Fuels review, 2009

B2380 – Effect of Pressure on the Crystallization of Crude Oil Waxes. I. Selection of Test Conditions by Microcalorimetry

Evaluationsof the potential for formation ofwax deposits in laboratories generally are performed on stabilized oil samples, that is, at atmospheric pressure and without the presence of light components. Therefore, the effects to two important factors that influence the solubility of waxes, namely light fractions and pressure, are not considered.As a consequence, the results may not reflect what really happens in production lines and equipment. The high-pressure microcalorimetry technique (HP?DSC) is indicated for determining the wax appearance temperature (WAT) and crystallization enthalpy of waxes in oils, but due to the complexity of petroleumsystems, the reliability of the results depends on the experimental conditions chosen. This paper reports experiments to evaluate the factors that influence the accuracy of the experimental results for determining the WAT and crystallization enthalpy of samples of Brazilian crude oil and condensate, saturated with different types of gases, by using high pressure microcalorimetry (HP?DSC). The results show that heat flow values of more than twice the baseline oscillation, that is, 48 ?W, could be considered as a thermal event. It is fundamental to investigate the gas phase saturation envelope to evaluate the viability of pressurizing the reference cell and to determine the most adequate conditions of temperature for the pressurization of the oil samples. Still better results were obtained without pressurizing the reference cell and with exchange of test aliquots after analysis at 50 bar. The minimum saturation time necessary for the oil and condensate samples evaluated was 180 min, and the ideal mass for analysis was around 100mg. The most suitable procedure was to pressurize the samples rather than depressurize them,with the deviation between the two procedures being<1 C. The standard deviation of the values found in the conditions specified was<0.5 C.
Lenise C. Vieira, Maria B. Buchuid, Elizabete F. Lucas, Energy Fuels review, 2009

B2364 – Study of Enhanced Fine Coal De-sulphurization and De-ashing by Ultrasonic Flotation

The feasibility of using ultrasound to enhance the performance of de-sulphurization and de-ashing during slime flotation was investigated. The Setaram C80 calorimeter, the contact angle gauge DCAT21 and an electrophoresis apparatus were used to study the surface nature of coal, pyrite and refuse before and after ultrasonic conditioning. The yield, ash and sulfur contents of equally sized coal slimes were also measured before and after ultrasonic conditioning. The results show that ultrasonic conditioning can drive the separation of pyrite and refuse from coal. After ultrasonic conditioning the hydrophobicity of coal and hydrophilicity of pyrite and refuse increase. The perfect index of flotation, the perfect index of de-sulphurization and the percentage of de-sulphurization increase by 22.51%, 25.36% and 2.49%, respectively. This study shows that ultrasonic conditioning can enhance the performance of de-sulphurization and de-ashing of coal flotation methods
Wen-ze Kang, Hai-xin Xun, Jun-tao Chen, J China Univ Mining & Technol 2007, 17(3): 0358–0362

B2233 – Temperature-programmed reduction and acidic properties of molybdenum supported on MgO-Al2O3 and their correlation with catalytic activity

Aseries of catalyst withMoloading from 2 to 14 wt.% on MgO-Al2O3 mixed oxide supportwas prepared by incipient wetness impregnation method. Pure MgO and Al2O3 were prepared by using Mg(NO3)2.6H2O and Al(NO3)3.9H2O salt solutions and urea as hydrolyzing agent. MgO-Al2O3 (1:1) mixed oxide was prepared by co-precipitation of appropriate quantities of magnesium nitrate and aluminum nitrate salts. BET surface area, pore volume, pore size distribution, TPR, acidity and acid strength distributions of catalysts and supports were measured. MgO-Al2O3 (1:1) mixed oxide showed a biomodal pore size distribution. LTOC and TPR results show that an optimum 8% Mo on MgO-Al2O3 is sufficient to form MoO3 monolayer. TPR technique can also be used as a vital tool to determine the monolayer coverage. HDS activity has been correlated with LTOC. Introduction of basic MgO in the lattice of Al2O3 moderates the strong acidity in MgO-Al2O3. Impregnation of acidic MoO3 species further enhances the acidity favorable for HYC.
M. Kumar, F. Aberuagba, J.K. Gupta, K.S. Rawat, L.D. Sharma, G. Murali Dhar, Journal of Molecular Catalysis A: Chemical 213 (2004) 217-223

B2153 – The reaction conditions influence on sucrose acid hydrolysis studied by means of DSC method

The influence of the reaction conditions upon the sucrose acid hydrolysis to glucose/fructose equimolecular mixture was investigated, in heterogeneous and homogeneous system, by means of DSC method. The recorded DSC signal was used to evaluate the kinetic parameters and the afferent catalytic constant, k cat 323 values. In homogeneous conditions the used catalyst was acetic acid while in heterogeneous systems a series of carboxylic resins was used as catalysts. The results show a dependence of the kinetic parameters on homogeneous/heterogeneous catalyst nature and on resins experimental properties (cross-linking degree, granulation, porous nature of polymeric matrix, swelling time).
D. Chambré, C. Iditoiu and M-R. Szabo, Journal of Thermal Analysis and Calorimetry 88 (2007) 681-686

B2027 – Infiltrated glassy carbon membranes in gamma-Al2O3 supports

Anewinfiltrated microporous membrane without defects has been obtained. For that, a microporous glassy carbon (GC) membranewas infiltrated inside the mesoporous structure of a gamma-Al2O3 support with 70% of porosity. GC material was formed after carbonisation of a phenolic resin which is deposited on the inner face of a tubular ceramic multilayer system. This consists of a cordierite support, an intermediate layer of gamma-Al2O3 and a gamma-Al2O3 top layer. Textural properties of the unsupported GC membrane were determined by CO2 adsorption at 273K and inmersion calorimetry employing organic solvents with different molecular dimensions. The sequence of the GC deposition in gamma-Al2O3 support was studied by scanning electron microscopy (SEM). The final infiltrated membrane system was studied by N2 adsorption-desorption isotherms at 77K and gas permeation measurements.
J. Carretero, J.M. Benito, A. Guerrero-Ruiz, I. Rodriguez-Ramos, M.A. Rodriguez, Journal of Membrane Science 281 (2006) 500-507

B1916 – A method for the characterization of emulsions, thermogranulometry: Application to water-in-crude oil emulsion

Emulsions are used in a wide range of applications and industries. Their size distribution is an important parameter because it influences most of the emulsion properties of emulsions. Several techniques of characterization are used to determine the granulometric distribution of emulsions, but they are generally limited to dilute samples and are based on complex algorithms. We describe a method that allows characterization of the droplet size distribution of emulsions using thermal analysis (thermogranulometry). This method permits the use of very concentrated samples without any dilution or perturbation of the system. We first define our method by a thermodynamic and kinetic approach. We studied a real system, i.e., crude oil emulsions, which form very concentrated, viscous, and opaque emulsions with water. We present a correlation between the size of droplets and their freezing temperature, corresponding to our system. Then we compare the size distributions obtained by our method with those derived by direct microscopy observations. The results obtained show that thermogranulometry may be an interesting method of characterization of emulsions, even for concentrated systems.
D. Clausse, F. Gomez, C. Dalmazzone, C. Noik, Journal of Colloid and Interface Science 287 (2005) 694-703

B1915 – The interaction at the solid/liquid interface of 2,4-dichlorophenoxyacetic acid with silica modified by reaction with ammonia gas

A method for the attachment of ammonia to modified silica gel has been developed. In the first step, tetraethylorthosilicate and (3-glycidoxypropyl) trimethoxysilane were co-condensed in the presence of n-dodecylamine, a neutral surfactant template, to produce a modified mesoporous silica. The epoxy group incorporated into the mesoporous silica was opened by ammonia gas thus introducing amine chelate groups covalently bound to the inorganic surface. The modified material contained 1.13 ± 0.06 mmol of amine per gram of silica, exhibited a surface area of 831 ± 29 m2 g-1 and a porous diameter of 1.95 nm. Infrared, 29Si and 13C NMR spectra were in agreement with the proposed structure of the modified mesoporous silica in the solid state. This ordered organic-inorganic hybrid presented a high capacity for the removal of the agrochemical 2,4-dichlorophenoxyacetic acid from water: the H and G values for the interaction were determined to be -110.61 and -9.37 kJ mol-1, respectively.
A.G.S. Prado, E. DeOliviera, Journal of Colloid and Interface Science 291 (2005) 53-58

B1780 – Paraffin crystallization in synthetic mixtures: Predictive local composition models revisited

Aiming at identify the shortcomings of the available models for the description of the solid phase non-ideality, new solid liquid equilibrium data for multicomponent hydrocarbon systems was measured. The Predictive UNIQUAC and Wilson models for the description of the solid phase non-ideality, previously proposed, are here compared against this new data. The weaknesses displayed by these models on the predictive description of the measured phase behavior helps to identify their limitations and this is expected to lead to a new improved model for the solid phase non-ideality. Following this approach a new UNIQUAC based model is proposed that seems to overcome the limitations of the models identified on this work.
J.A.P. Coutinho, C. Gonçalves, I.M. Marrucho, J. Pauly, J-L. Daridon, Fluid Phase Equilibria 233 (2005) 28-33

B1201 – Measurement and calculation of heat capacity of heavy distillation cuts under pressure up to 40 MPa.

Isobaric heat capacities of natural mixtures were determined up to 40 MPa with a modified C-80 Setaram calorimeter equipped with cells designed for high pressures. The systems investigated were heavy distillation cuts with respective boiling points of 150, 200, 250 and 300°C. These experimental data were used as discriminatory values to test thermodynamic models and more precisely to choose among the great number of equations of state and mixing rules proposed in the literature, the most appropriate for the characterization of the heavy components.
D. Bessières, H. Saint-Guirons and J-L. Daridon, Journal of Thermal Analysis and Calorimetry 58 (1999) 39-49

B1118 – Caractérisation des particules de carbone issues de la combustion des carburants dans les moteurs diesels.

A. El Ghzaoui, S. Partyka, Calo. & analyse ther. vol 28 p 251-257

B1011 – Application of isothermal calorimetry to jet fuel autoxidation kinetics

The acid site strength distributions of y-Al2O3, BeO, Nb2O5, TiO2, WO3, and ZrO2 surfaces were evaluated starting from volumetric and calorimetric experimental data of ammonia adsorption collected at 80 and 150°C. A mathematical model was employed to describe the behavior of the adsorbate-adsorbent system. The model took into account a discrete inhomogeneity of the surface. A fitting procedure applied to both the isotherms and the integral heat curves of ammonia adsorption, at the two above temperatures, permitted the determination of the thermodynamic parameters characteristic of the different types of site. The number, nmax,i, the adsorption equilibrium constant, bi, as well as a new parameter termed the "half-coverage temperature at unit pressure," T°1/2,i, of each type of acid site were obtained. All the oxides showed a significant amount of acid sites with ammonia enthalpy of adsorption ?aHi at -40 kJ/mol corresponding to hydrogen-bonded ammonia. Three types of more energetic sites, with ?aHi ranging from -280 to -160 kJ/mol, were found for y-Al2O3, Nb2O5, TiO2, and ZrO2. Sites with ?aHi of -280 and -200 kJ/mol were found for BeO and WO3. Mean molar adsorption entropies were also determined, and the values obtained are typical of immobile or localized adsorption.
J.M. Pickar, E.G. Jones, W.J. Balster, NATAS (1995) 216-221

B0882 – Determination of adhesion in bitumen-mineral systems by heat-of-immersion calorimetry. II. Correlation of chemical properties with adhesion

The strength of chemical bonds formed between eight rock-forming minerals and six bitumen samples were examined by heat-of-immersion calorimetry. The materials were characterised by their physical and chemical properties. The amount of energy released by the bitumen-mineral interaction was much larger than expected for an immersion reaction, exceeding usual values by a factor of up to 10^2. An oxidation mechanism, catalysed at the mineral surface, is proposed to account for this observation, and trends in the heat-of-immersion data are correlated with chemical properties of the bitumen and mineral samples.
M.B. Evans, D.V Nowell, M.W. Powell, Journal of Thermal Analysis 40 (1993) 121-131

B0801 – Monitoring wax crystallisation in diesel using differential scanning calorimetry (DSC) and microcalorimetry

The crystallisation of wax on cooling a diesel was monitored by DSC with cooling rates of 5-0.2°C/min and by a microcalorimeter with the lower rates of 0.1-0.01°C/min. The melting of crystallised wax was also monitored by DSC to assess the thermodynamic reversibility of the process. The results show that crystallisation temperatures from DSC at a cooling rate of 1°C/min are close to those from microcalorimetry at 0.01°C/min (a realistic cooling rate for diesel in a vehicle). A comparison of crystallisation and melting data shows that equilibrium crystallisation conditions are not achieved even at the lowest cooling rate used here.
E. Gimzewski and G. Audley, Thermochimica Acta 214 (1993) 149-155

B0791 – Determination of adhesion in bitumen-mineral systems by heat-of-immersion calorimetry I.The effect of crude oil source on adhesive performance

Chemical factors influencing bitumen-mineral adhesion have been examined by heat-ofimmersion calorimetry. Two chosen minerals (quartz and calcite) and bitumen derived from Venezuelan and Middle East crude oils were characterised and the energy released by the bitumen-mineral interaetion measured. Heat-of-immersion data are correlated with the coneentration of heteroatomic species present in the bitumen and the structure of the mineral surfaces. Bitumen-quartz bonding is promoted by the presence of basic species in the bitumen and bitumen-calcite adhesion is favoured by the presence of acidic groups. A mechanism is proposed to account for the observed bond energies.
D.V. Nowell and M.W. PowelI, Journal of Thermal Analysis 37 (1991) 2109-2124

B0781 – Etude par analyse enthalpique différentielle des transferts d’eau dans des émulsions multiples E/H/E.

L. Potier, S. Raynal, D. Clausse, M. Seiller, J-L. Grossiord, JCAT (1992) 57-64

B0755 – Thermokinetic investigation of oxidation of heavy oil and its model compunds

This paper presents and discusses the thermokinetic parameters of oxidation of heavy oil (Nanyang deposit) and selected model compounds (n-dotriacontane, stearic acid and octadecanol). The method introduced in this work defines the key parameters which affect the quality of the numerical simulation of the energy balance equation of the in situ combustion process simulation experiment and the actual process in the field. A microcalorimetric technique is combined with a thermokinetie approach developed at the Institute of Chemistry to calculate the thermal energy of reactions such as oxidation of heavy oil or other compounds in in.situ combustion occurring in a porous medium as a function of time at different temperatures and pressures. The kinetic parameters were determined from calorimetric and chemical experiments.
Z.L. Zhang, Y.F. Liu, R.H. Hu and X.Q. Shen, Journal of Thermal Analysis 37 (1991) 1545-1556

B0751 – Calorimetric evidence for a dual mechanism in the low temperature oxidation of coal

Calorimetry linked with GPC analysis has allowed the measurement of the heat of reaction against the oxygen coverage for three french coals ranging from subbituminous to semianthracite. At low oxygen coverage, a complex evolution of the enthalpy is observed mainly attributed to a chemisorption located on radical sites formed and accumulated during the outgassing pretreatment, whereas at higher coverage, the enthalpy becomes independent of the oxygen coverage where the removal of hydrogen as water vapour predominates. At low coverage the degassing pretreatments influence in a persistent way the enthalpy measurements, and in consequence it is generally only at high oxygen coverage, that enthalpy measurements coming from differently pretreated samples may be usefully compared.
J.C. Petit, Journal of Thermal Analysis 37 (1991) 1719-1726

B0729 – Microcalorimetric investigation on the adsorption of n-hexane on different surface sites of coal

P.F. Rossi, A. Vettor, G. Milana, G. Oliveri, G. Busca, JCAT (1991) 237-243

B0713 – Thermochemical studies of helium and argon sorption by oxidated coals

The influence of noble gases such as helium and argon on the structure of oxidated coals (sub-bituminous coal, high-volatile bituminous coal and anthracite) has been studied. It was found that the process of oxidation changed; essentially, helium induced modification of the coal structure. An attempt has been made to explain the phenomena observed.
P. Starzewski, Y. Grillet, Thermochimica Acta 173 (1990) 17-23

B0693 – Reversible and irreversible interaction of oxygen with coal using pulse flow calorimetry

The effects of temperature, time, particle size and coal moisture content on heats of reversibly and irreversibly sorbed oxygen were studied separately using pulse flow calorimetry. The results of measurements performed on seven coal samples, ranging from subbituminous to low volatile bituminous, show that in coals of low porosity (open porosity less than ?8%), the particle size affects the heat of the apparent physical adsorption of oxygen much more than that of chemical sorption. However, in two samples of high porosity (open porosity 25 and 28%), the heats of both physically and chemically sorbed oxygen were found to be independent of particle size. The heat of reversibly sorbed oxygen decreased with increase in moisture content, while the heat of irreversibly sorbed oxygen remained constant and even increased in highly hydrophilic samples. Comparison of coal surfaces occupied by adsorbed molecules of oxygen and coal surfaces occupied by a nitrogen monolayer (BET) shows that at ambient temperature, oxygen is able to penetrate even into those micropores of coal which are inaccessible to N2 at -196°C.
B. Taraba, Fuel 69 (1990) 1191-1199

B0658 – Gas-solid interactions : heats of adsorption of water and n-hexane on coal.

P.F. Rossi, G. Milana, A. Vettor, AFCAT (1990) 137-145

B0496 – An experimental study of heat of immersion of coal

T.G Melkus, S.H. Chiang, W.W. Wen, AICHE Meeting, Miami Beach (USA) (1986)

B0473 – Calorimetric studies of oil shales and shale products

G.L. Corino, A.G. Turnbull, Csiro, Australie

B0441 – Thermodynamics and kinetics of immersion of coal by n-alcohols

The heats of immersion of Pocahontas No. 3 coal (325 mesh) have been measured at 36°C for a series of n-alcohols in a Calvet MS 70 microcalorimeter. The 200 mg coal samples were outgassed at 1 x 10^(-5) torr for 1h at room temperature. The evacuated sample bulbs with break-off tips were broken in 5 cm3 of the alcohols after establishment of an initial steady state. The rate at which the steady state was reestablished after immersion of the coal was followed. The heat of immersion decreased non-linearly from 20.2 J/g for methanol to 5.8 J/g for n-dodecanol. The immersion times of coal by methanol and n-dodecanol were 330 and 475 min/g, resp. A maximum in immersion time of 1220 min/g was observed for n-butanol. The results suggest limited penetration of the immersion liquids into the coal structure as the alcohol chain length increases.
E. Widyani and J.P. Wightman, Colloids and Surfaces 4 (1982) 209-212

B0422 – Wetting of powdered coals by alkanol-water solutions and other liquids

The wetting rates of powdered coals by alkanol-water solutions have been measured. A critical concentration of each alkanol is needed before any wetting occurs and this critical wetting concentration is lower for alcohols with longer carbon chains. A critical surface tension of 0.033 J m-2 for Pocahontas No. 3 coal is estimated from the measured wetting concentrations. Studies with a Calvet microcalorimeter show that the heats of immersion of powdered coal in water-methanol mixtures vary smoothly with changing concentration, reaching a maximum value of 16 J g-1 at 30 mol % methanol. Both for alkanols and other liquids, the heat of immersion of coal dust is released over long periods of up to nine hours.
J.O. Glanville and J.P. Wightman, Fuel 59 (1980) 557-562

A2093 – Role of additives in improved thermal activation of coal fly ash for alumina extraction

The extraction of alumina from coal fly ash is a good direction for its value-added utilization. The presence of the inert matters with high degree of polymerization, such as mullite and other aluminosilicates, makes the reactivity of coal fly ash very poor. The activation of coal fly ash is necessary before its utilization. The thermal activation calcination with the addition of NaOH and Na2CO3 was carried out in this research. The results showed that the addition of NaOH and Na2CO3 improved the alumina extraction evidently. The maximum alumina extraction reached ~ 60% when calcination at 600–900 °C with the addition of NaOH and that could reach 82% at 900 °C with the addition of Na2CO3. Detailed analysis and characterization was carried out by using thermal gravimetric and differential scanning calorimetric analysis (TG-DSC) and X-ray diffraction (XRD). The results indicated that NaOH and Na2CO3 facilitated the decomposition of the polymeric phases. At lower temperatures (< 600 °C), NaOH played a main role while Na2CO3 did at higher temperatures (> 700 °C). As a result, the mixed additives containing NaOH and Na2CO3 made alumina extraction attain 95% at 700 °C.
Yanxia Guo, Yaoyao Li, Fangqin Cheng, Miao Wang, Xuming Wang, Fuel Processing Technology 110 (2013) 114–121

A2069 – Effect of CS2 extraction on the physical properties and gasification activity of liquid-phase carbonization cokes

Two kinds of liquid-phase carbonization cokes (LPCCs) were prepared using vacuum residue (VR) and coal tar pitch (CTP) at 350–500 °C, at which the carbonaceous mesophase appears typically. And the effect of CS2 extraction on the physical properties (carbon crystalline structures, surface morphologies, surface areas and pore structures) and gasification activity of LPCCs were mainly investigated. The increasing carbonization temperature (CT) was favorable for LPCCs to form more ordered carbon crystallite structures, but their graphitization was far from natural graphite. The surface or inner pores of unextracted LPCCs conglutinated a large quantity of CS2-soluble fractions, which severely blocked the pore structure of LPCCs. Although the carbon crystalline structures of LPCCs after extraction were significantly unchanged, the BET surface areas and total pore volumes of extracted LPCCs increased significantly, which resulted in a greatly increasing gasification activity of LPCCs. And a higher extraction yield led to a higher increasing extent of gasification activity of LPCCs after extraction, regardless of precursors (VR and CTP). The soluble fractions conglutinated on the surface or inner pores of LPCCs were the most important factor of affecting on the gasification activity of LPCCs.
Sheng Huang, Shiyong Wu, Yamin Ping, Youqing Wu, Jinsheng Gao, Journal of Analytical and Applied Pyrolysis 93 (2012) 33–40

A2048 – Oxy-fuel combustion kinetics and morphology of coal chars obtained in N2 and CO2 atmospheres in an entrained flow reactor

The thermal reactivity and kinetics of four coal chars (HVN, UM, SAB and BA) in an oxy-fuel combustion atmosphere (30%O2–70%CO2) were studied using a thermobalance. The coal chars were obtained by devolatilization in an entrained flow reactor (EFR) at 1000°C for 2.5s under 100% N2 and CO2 atmospheres. The reactivity tests were carried out by isothermal thermogravimetric analysis at different temperatures in a kinetically controlled regime. Three nth-order representative gas–solid models – the volumetric model (VM), the grain model (GM) and the random pore model (RPM) – were employed in order to describe the reactive behaviour of the chars during oxy-fuel combustion. From these models, the kinetic parameters were determined. The RPM model was found to be the best for describing the reactivity of the HVN, UM and BA chars, while VM was the model that best described the reactivity of the SAB char. The reactivities of the chars obtained in N2 and CO2 in an oxy-fuel combustion atmosphere with 30% of oxygen were compared using the kinetic parameters, but no differences were observed between the two devolatilization atmospheres. The apparent volatile yield after the coal devolatilization under CO2 in the EFR was greater than under N2 for all the coals studied. According to the scanning electron microscopy (SEM) images of the chars, those obtained in the CO2 atmosphere experienced a greater degree of swelling, some particles showing partially reacted surfaces indicative of reaction between the char and CO2.
M.V. Gil, J. Riaza, L. Álvarez, C. Pevida, J.J. Pis, F. Rubiera, Applied Energy 91 (2012) 67–74

A2037 – Clay minerals in nonaqueous extraction of bitumen from Alberta oil sands Part 1. Nonaqueous extraction procedure

A non-aqueous bitumen extraction process was studied where only toluene and heptane, with no water additions, were used to extract bitumen from two Alberta oil sands ore samples. One sample had a high bitumen (13.5 wt.%) and low fines (5.3 wt.% < 45 ?m) contents, while the other sample had an intermediate bitumen (10.5 wt.%) and high fines (23.3 wt.%) contents. Bitumen recovery and product quality were measured under different process conditions such as the ratio of toluene to heptane and settling time. The Dean Stark procedure was used to determine the solids, bitumen and water contents of the extraction products. In addition, the water content was determined by the Karl Fischer titration method. High bitumen recovery was obtained for both oil sands ore samples although the high fines ore sample was more sensitive to the extraction conditions, especially the toluene to heptane ratio. A product with high purity, containing more than 99.5 wt.% bitumen on a solvent-free basis, was produced at room temperature under the optimum extraction conditions tested. The optimum settling time to achieve a pure product was less than 10 min, based on solids and water contents in the supernatant.
Ali Hooshiar, Peter Uhlik, Qi Liu, Thomas H. Etsell, Douglas G. Ivey, Fuel Processing Technology 94 (2012) 80–85

A1948 – Mechanism of co-pyrolysis of coal-tar pitch with polyacrylonitrile

Co-pyrolysis of coal-tar pitch with polyacrylonitrile (PAN) and PAN oxidized in air at 300 °C was studied as a possible way of manufacturing of carbonaceous materials enriched in nitrogen. The thermal behaviour of components and blends was evaluated by thermogravimetry and optical microscopy of solid residues. The transformation of nitrogen functional groups on co-treatment was monitored using elemental analysis, infrared spectroscopy and X-ray photoelectron spectroscopy. Oxidized polymer behaved as an inert during co-pyrolysis. In contrast, strong interactions of unoxidized PAN with pitch could be deduced from enhanced residue yield and extensive deterioration of the optical texture of resultant coke. Principal chemical interaction between components seems to be hydrogen abstraction from pitch constituents by radicals generated from PAN bonds scission. Pitch matrix does not modify distinctly the way of nitrogen functionalities evolution. At semi-coke stage majority of nitrogen occurs as pyridinic nitrogen with pyrrolic and/or pyridonic one being a second relevant form.
B. Grzyb, J. Machnikowski, J.V. Weber, A. Koch, O. Heintz, Journal of Analytical and Applied Pyrolysis 67 (2003) 77–93

A1938 – Influences of carbon structure on the reactivities of lignite char reacting with CO2 and NO

Raw and demineralized lignite samples were pyrolyzed from 773 to 1673 K to generate chars. The chars were characterized with Raman spectroscopy for the structure evolution. The reactivities of the chars reacting with CO2 and NO were measured with thermogravimetric analysis. The derived reactivity indexes were correlated with the treatment temperature and the Raman structural parameters to demonstrate the applicability of Raman spectroscopy for evaluation of the reactivities of char CO2 gasification and char–NO reaction. It was found that char microstructure evolution with the treatment temperature could be represented by Raman band area ratios. ID1/IG and IG/IALL represented the evolution of the ordered carbon structure while the combination of ID3/(IG+ID2+ID3) reflected the evolution of the amorphous carbon structure of the lignite chars with increasing the treatment temperature from 773 to 1673 K. Reactivity indexes of the demineralized chars reacting with both CO2 and NO were found to increase with increasing the treatment temperature, implying that the structure ordering did result in the losses of the reactivities. Higher reactivities of the non-demineralized chars indicated the catalytic role of inorganic matter in the reactions with both gases. ID1/IG and IG/IALL had good linear correlations with the reactivities particularly of the demineralized chars if considering the structure evolution behaviors at lower and higher temperatures, respectively. ID3/(IG+ID2+ID3) was found to have fairly good linear correlations with the reactivity indexes of the lignite chars generated over the whole temperature range.
Xiaoling Zhu, Changdong Sheng, Fuel Processing Technology 91 (2010) 837–842

A1912 – A study of oxy-coal combustion with steam addition and biomass blending by thermogravimetric analysis

The thermal characteristics of pulverized coal have been studied under oxy-fuel combustion conditions using non-isothermal thermogravimetric analysis (TG). The atmospheres used were 21%O2/79%N2, 21%O2/79%CO2, 30%O2/70%O2, and 35%O2/65%CO2. Coal blends of coal with 10 and 20% of biomass were also studied under these atmospheres. The addition of 10 and 20% of steam was evaluated for the oxy-fuel combustion atmospheres with 21 and 30% of O2 in order to study the effect of the wet recirculation of flue gas. The results obtained were similar for all the different rank coals and indicated that replacing N2 by CO2 in the combustion atmosphere with 21% of O2 caused a slight decrease in the rate of mass loss and delayed the burning process of the coal, biomass and coal/biomass blend samples. When the O2 concentration was increased to 30 and 35% in the oxy-fuel combustion atmosphere, the rate of mass loss increased, the burning process occurred at lower temperatures and it was shorter in duration. An increase in the rate of mass loss and a reduction in burning time and temperature were observed after the addition of steam to the oxy-fuel combustion atmosphere. No relevant differences between the 10 and 20% steam concentrations were observed.
M. V. Gil, J. Riaza, L. Alvarez, C. Pevida, J. J. Pis, F. Rubiera, J Therm Anal Calorim (2012) 109, 49–55

A1895 – Comparative combustion study of some polymers with oil shale

In this study, the combustion kinetics of Go¨ynu¨k oil shale, polyethylene, polyethylene glycol (PEG), polymethyl methacrylate (PMMA), polyvinyl chloride, and polymer–oil shale blends were investigated by thermogravimetric analysis. Experiments were conducted at non-isothermal conditions with a heating rate of 5 K min-1 in the 298–1173 K temperature interval under air atmosphere. An increase in the total conversion values with increasing mass percentage of polymers of the blends was observed. Differential thermogravimetric data were analyzed by an Arrhenius model. Effects of blending ratio of oil shale and polymer on the combustion kinetics were investigated. Kinetic parameters were determined and the results were discussed. An increase was observed in the frequency factor and activation energy values as the weight percentage of polymer in blends were increased. The minimum activation energy, 16.1 kJ mol-1, was calculated for PEG/oil shale with 2/3 blending ratio.
Yeliz Durak, Tülay Durusoy, J Therm Anal Calorim (2012) 108, 1273–1279

A1807 – Thermogravimetric study of coal and petroleum coke for co-gasification

As a preliminary study of gasification of coal and petroleum coke mixtures, thermogravimetric analyses were performed at various temperatures (1,100, 1,200, 1,300, and 1,400 °C) and the isothermal kinetics were analyzed and compared. The activation energies of coal, petroleum coke and coal/petroleum coke mixture were calculated by using both a shrinking core model and a modified volumetric model. The results showed that the activation energies for the anthracite and petroleum coke used in this study were 9.56 and 11.92 kcal/mol and reaction times were 15.8 and 27.0 min. In the case of mixed fuel, however, the activation energy (6.97 kcal/mol) and reaction time (17.0 min) were lower than the average value of the individual fuels, confirming that a synergistic effect was observed in the coprocessing of coal and petroleum coke.
Sang Jun Yoon, Young-Chan Choi, See-Hoon Lee, Jae-Goo Lee, Korean Journal of Chemical Engineering, May 2007, Volume 24, Issue 3, pp 512-517

A1746 – Effect of pyrolysis temperature on the char micro-structure and reactivity of NO reduction

NO is a well-known combustion-related pollutant causing photochemical smog and acid rain, which motivates extensive research efforts for reducing its emissions. It has been proved that NO can be chemisorbed on the surface of carbon at lower temperature and react with carbon at higher temperature. Reduction of NO with carbonaceous materials with or without catalyst loading has been proposed as a promising way to lower NO emissions from combustion systems. Among various carbonaceous materials, e.g., coal char, activated carbon, graphite, phenol-formaldehyde resin (PFR) char and biomass char, PFR char is an excellent model material used for the studies on the reduction of NO because it has a similar structure as coal char but negligible inorganic matter content. Char-NO reaction is a typical heterogeneous reaction. The precursor of char, the presence of catalyst, pore structure, reaction temperature, reactant concentration and gas composition have impacts on the reaction rate. Furthermore, heat treatment conditions during char preparation including pyrolysis temperature, heating rate and treatment time, to some degree, determine the element content, pore structure and micro-structure of resulting char and consequently influence gasification reactivity towards O2 and CO2 . For NO-carbon gasification reaction, the reactivity of coal char towards NO was found to decrease with increasing pyrolysis temperature and soaking time. Increasing heating rate during the char pyrolysis resulted in higher pore volume and total surface area and thus enhanced the rate of NO reduction.
Yanshan Yin, Jun Zhang, Changdong Sheng, Korean J. Chem. Eng., 26(3), 895-901 (2009)

A1729 – Thermooxidative decomposition of oil shales

The thermooxidative decomposition of four oil shale samples from Estonia, Jordan, Israel and Morocco and one sample of Estonian oil shale derivative, semicoke, was studied with the aim to determine the characteristics of the process and the differences of it related to the origin of oil shale. The experiments with a Setaram Setsys 1750 thermoanalyzer coupled to a Nicolet 380 FTIR Spectrometer were carried out under non-isothermal conditions up to 1000 C at the heating rates of 1, 2, 5, 10 and 20 C min-1 in an oxidizing atmosphere. A model-free kinetic analysis approach based on the differential isoconversional method of Friedman was used to calculate the kinetic parameters. The results of TG–DTA–FTIR analyses and the variation of activation energy E along the reaction progress a indicated the complex character of thermooxidative decomposition of oil shale and semicoke, being at that the most complicated for Estonian and Jordanian oil shale characterized by higher content of organic matter as compared to the other samples studied.
Tiit Kaljuvee, Merli Keelmann, Andres Trikkel, Rein Kuusik, J Therm Anal Calorim (2011) 105, 395–403

A1726 – Simultaneous thermogravimetric–mass spectrometric study on the pyrolysis behaviour of different rank coals

Simultaneous thermogravimetry–mass spectrometry was used to study the pyrolysis behaviour of an anthracite and three bituminous coals of different volatile matter content. This system was optimised by using calcium oxalate as a reference for calibration. A normalisation method that permitted a semiquantitative comparison between the volatile species of the coals was also developed. The instantaneous evolution of the volatile compounds was studied by means of temperature-programmed pyrolysis experiments. The peaks varied in shape, temperature and size, and showed a marked dependence on coal rank. This can be attributed to the varying amounts of the different functional groups in the coals studied. Special attention was paid to the nitric oxide released during pyrolysis, together with its precursor species.
A. Arenillas, F. Rubiera, J.J. Pis, Journal of Analytical and Applied Pyrolysis 50 (1999) 31–46

A1719 – Heterogeneous reduction of nitric oxide on synthetic coal chars

Model compounds, with a controlled heteroatoms content and well-defined functionalities, were used to study the release of nitrogen compounds from char combustion. In the present work, the mechanisms involved in NO-char heterogeneous reduction were studied with a synthetic coal (SC) char as carbon source. Another synthetic char (SN) without any nitrogen in its composition was also employed in these studies. Temperature programmed reduction (TPR) tests with a gas mixture of 400 ppm NO in argon and with isotopically labelled nitric oxide, 15NO (500 ppm 15NO in argon), were carried out. The gases produced were quantitatively determined by means of MS and FTIR analysers. Under the conditions of this work the main products of the NO-C reaction were found to be N2 and CO2. The main path of reaction involves the formation of surface nitrogen compounds that afterwards react with nitrogen from the reactive gas to form N2. It was observed that fuel-N also participates in the overall heterogeneous reduction reaction, although to a lesser extent.
C. Pevida, A. Arenillas, F. Rubiera, J.J. Pis, Fuel 84 (2005) 2275–2279

A1653 – Coal Pyrolysis in a Rotary Kiln: Part I. Model of the Pyrolysis of a Single Grain

A mathematical model is presented which describes the pyrolysis of a single grain of coal and is designed to be incorporated into an overall model simulating the rotary kiln coal pyrolysis process. The grain model takes into account the principal physical phenomena occurring during the conversion of coal to coke, namely, heat transfer toward and within the grain, drying of the coal, and the evolution of volatile species. Particular care has been taken in the determination of the thermophysical and kinetic parameters necessary for the model. Thus, the drying kinetics for Lorraine coal were measured by thermogravimetry. The kinetics of pyrolysis were determined by both thermogravimetry and gasphase chromatography, in order to separately monitor the evolution of the nine gaseous species considered. The true specific heat and the thermal conductivity of the solid were also mesured as a function of temperature. The numerical model, based on the finite-volume method, calculates the temperature, composition, and mass flow rates for the different gases evolved at each point in the grain at any instant of time. The model was, finally, validated by comparing the calculated and measured values of the overall conversion of the pyrolysis reaction and the temperature at the center of the grain.
Fabrice Patisson, Etienne Lebas, François Hanrot, Denis Ablitzer, Jean-Léon Houzelot, Metallurgical and Materials Transactions B, Volume 31B, April 2000—381

A1595 – Reaction mechanism of carbon gasification in CO2 under non-isothermal conditions

Experiments of carbon (graphite) gasification in CO2 have been carried out by thermal analysis techniques (TG-DTG-DSC) under non-isothermal conditions. The results indicate that the entire carbon gasification process can be divided into an exothermic slow gasification stage during the initial period and an endothermic fast gasification later. The analyses of energy conservation and non-isothermal kinetics arrive at the following conclusions; (1) The exotherm of the initial stage is caused by the combined effect of the exothermic chemisorption and the endothermic chemical reaction. The gasification reaction may be expressed by the series of chemisorption and chemical reaction and the overall process is controlled by interface reaction via chemisorption. (2) The endothermic effect of fast gasification stage is almost equal to the reaction heat of carbon gasification, which implies that the chemisorption step disappears. The gasification process can be expressed by a simple interface reaction.
Zhong-Suo Liu, Qi Wang, Zong-Shu Zou, Guang-Lei Tan, J Therm Anal Calorim (2011) 104, 1091–1096

A1493 – Arrhenius parameters determination in non-isothermal conditions for the uncatalyzed gasification of carbon by carbon dioxide

Non-isothermal thermogravimetric data were used to evaluate the Arrhenius parameters (activation energy, E, and pre-exponential factor, A) for the uncatalyzed gasification by carbon dioxide of two carbons, select as steam activated carbon (BPL) and SP-1 spectroscopically pure graphite. The paper reports on the application of the model-free isoconversional method (KAS/Vyazovkin linear method) for evaluating the activation energy of the gasification process. Activation energies have been calculated by this method were in good agreement with literature data for similar carbons. On the other hand, by means of the kinetic compensation relation between E and ln A, which was established by the model-dependent Coats–Redfern method, the value of the pre-exponential factor was estimated from the known value of the model-independent activation energy.
Zhongsuo Liu, Qi Wang, Zongshu Zou, Guanglei Tan, Thermochimica Acta, 512 (2011) 1–4

A1475 – Kinetics of combustion of oil shale with polystyrene

The combustion kinetics of Göynük oil shale, polystyrene and several polystyrene–oil shale blends were investigated by thermogravimetric analysis in the present study. Experiments were conducted at non-isothermal conditions with a heating rate of 5, 10 and 20 K min–1 in the 298–1173 K temperature interval under an air atmosphere. Differential thermogravimetric data were analyzed by two different models. Effects of blending ratio of oil shale and polystyrene and heating rate on the combustion kinetics were investigated. Kinetic parameters were determined and the results were discussed.
S. Yagmur, T. Durusoy, Journal of Thermal Analysis and Calorimetry, Vol. 96 (2009) 1, 189–194

A1434 – Changes in coal char reactivity and texture during combustion in an entrained flow reactor

Char particle combustion is the slowest step in the combustion of coal, therefore char reactivity and texture have an important influence on this process. In this work, two coals were devolatilised in an entrained flow reactor and the chars obtained were burned under different experimental conditions in order to achieve various degrees of burnoff. Char reactivity was determined by means of non-isothermal thermogravimetric analysis, and the conversion-time data were evaluated by the random pore model proposed by Bhatia and Perlmutter. Char texture was characterised by means of N2 and CO2 adsorption isotherms. The surface areas obtained were used to calculate intrinsic reaction rate parameters. It was found that under chemical controlled conditions, the available surface area during combustion is best represented by the N2 surface area.
B. Arias, C. Pevida, F. Rubiera, J. J. Pis, Journal of Thermal Analysis and Calorimetry, Vol. 90 (2007) 3, 859–863

A1382 – Kinetic models comparison for steam gasification of different nature fuel chars

The reactivity in steam of five different types of solid fuels (two coals, two types of biomass and a petcoke) has been studied. The fuel chars were obtained by pyrolysis in a fixed-bed reactor at a temperature of 1373 K for 30 min. The gasification tests were carried out by thermogravimetric analysis (TG) at different temperatures and steam concentrations. The reactivity study was conducted in the kinetically controlled regime and three representative gas-solid models, volumetric model (VM), grain model (GM) and random pore model (RPM), were applied in order to describe the reactive behaviour of the chars during steam gasification. The kinetic parameters of these models were derived and the ability of the models to predict conversion and char reactivity during gasification was assessed. The best model for describing the behaviour of the samples was the RPM. The effect of the partial pressure of steam in gasification was studied, and the reaction order with respect to steam was determined. The reactivity of the chars was compared by means of a reactivity index. Biomass exhibited a higher reactivity than coals and petcoke. However, significant differences in reactivity were observed between the two types of biomass used, which could be due to catalytic effects.
J. Fermoso, B. Arias, C. Pevida, M. G. Plaza, F. Rubiera, J. J. Pis, Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 3, 779–786

A1375 – Effect of mechanochemical treatment on petroleum coke–CO2 gasification

The effect of mechanochemical treatment during the grinding of petroleum coke on its gasification by CO2 was studied. An additive derived by drying the black liquor in papermaking industry is adopted in grinding process. Results show that the gasification reactivity of petroleum coke is effectively improved by grinding, and the activation by wet grinding is more noticeable than that by dry grinding. Besides, by wet grinding petroleum coke and additive together, the active metal species in additive are not easily volatilized in gasification, and retain a high catalytic reactivity to the coke–CO2 reaction throughout most of the conversion range. Changes in crystal structure of the petroleum coke induced by mechanochemical treatment is related to its gasification reactivity. In general, the crystalline amorphous phase transition is the tendency of long time mechanical grinding, while a crystal structure re-formation stage is observed after wet grinding of petroleum coke with and without additive for some time. Similar phenomenon has also been found in the reported data, but not given attention. Some discussion is made in the paper, and more work should be undertaken to disclose the mechanism.
Jianhui Zou, Boli Yang, Kaifeng Gong, Shiyong Wu, Zhijie Zhou, Fuchen Wang, Zunhong Yu, Fuel 87 (2008) 622–627

A1369 – Potential of thermogravimetric analysis coupled with mass spectrometry for the evaluation of kerogen in source rocks

The molecular composition of oil and yield from a source rock depends on the temperature to which the source rock is subjected. However, the yield of oil and gas represents hydrocarbons generated over a range of temperatures. A technique that measures both volatile yields and bulk and molecular compositions during volatile evolution would determine the differential effects of temperature change, thereby giving information on the effect of thermal gradients. Attaching a mass spectrometer to a thermogravimetric analyser assists in this goal since it allows gases to be analysed during petroleum source rock evaluation by pyrolysis. Single ion monitoring allows unambiguous identification of thermal events. It reveals temperature at which water, methane and carbon dioxide evolve. This allows organic and inorganic transitions to be distinguished. Parameters that describe the yields of oil and gas can also be derived from thermogravimetric analysis (TGA) in much the same way as they can for Rock–Eval pyrolysis data and are useful when combined with solid state 13C nuclear magnetic resonance (NMR) spectroscopy and Rock–Eval data for elucidating mineral matter effects
Craig P. Marshall, G.S. Kamali Kannangara, Michael A. Wilson, Jean-Pierre Guerbois, Birgitta Hartung-Kagi, Gwenda Hart, Chemical Geology 184 (2002) 185–194

A1320 – Porous structure evolution of cellulose carbon fibres during heating in the initial activation stage

This paper is focused on the description of changes in the porous structure during fast heating to the activation temperature of the viscose fibres, pyrolysed to different final temperatures. Standard regenerated cellulose fibre structures were tested. Fabrics were subjected to pyrolysis, the samples being heated to final temperatures of 400, 600 and 850°C. Carbon fibres were subsequently heated to activation temperature (850°C) at a rate of 100°C/ min, and then the samples were cooled down. The characteristics of obtained carbon preparations were examined. We have defined a level of restructuring and internal ordering of fibres which originated during slow pyrolysis as well as the range of temperature differences of pyrolysis and activation where fast increase of carbon fibre temperature before activation is advantageous for the development of porous structure. It allows for partial release of pores and fast rebuilding of structure accompanied by a considerable number of defects in the carbon matrix with higher reactivity to oxidiser which, in turn, promotes the development of pores in active carbon during oxidation. Temperature difference for viscose carbon fibres is approximately 150-300°C at pyrolysis temperature of 550-700°C.
K. Babel, Fuel Processing Technology 85 (2003) 75-89

A1247 – Activation of pyrolytic tire char with CO2: kinetic study

Chars from old tire pyrolysis have been activated with CO2. The chars were obtained by pyrolysis of a waste tire sample in a fixed bed reactor at a temperature of 1000°C for 3 h. The pyrolytic char, basically the original carbon black plus the tire mineral matter, was ground and sifted to an average particle size obtaining different fractions that were used as raw material in the activation experiments. These experiments were performed in a thermobalance at different temperatures (850, 900, 950 and 1000°C) in order to determine the activation energy and pre-exponential factor, basic intrinsic kinetic parameters of the activation process. Experimental conditions were optimized to avoid internal and external mass transfer phenomena performing experiments with different particle sizes, at different flow rates and initial weights. Moreover, the tire char activation was found to be a first order reaction with respect to CO2. A kinetic expression for tire activation, based on the random pore model and the structural parameters of the pyrolytic char, was deduced. In addition, with this kinetic model it can also be explained the maximum in reaction rate observed experimentally at conversions around 40%.
R. Murillo, M.V. Navarro, J.M. Lopez, T. Garcia, M.S. Callén, E. Aylon, A.M. Mastral, J. Anal. Appl. Pyrolysis 71 (2004) 945-957

A1246 – Characterisation of model compounds and a synthetic coal by TG/MS/FTIR to represent the pyrolysis behaviour of coal

Coal pyrolysis is the initial, accompanying reaction of a number of coal conversion processes such as hydrogenation, combustion and gasification. However, because of the inherent complexity of coal composition, it is difficult to describe coal pyrolysis clearly. Single model compounds have been used before in order to provide additional insight into the complex processes that occur in the pyrolysis of coal. Yet the picture obtained is a simplified one and certain important aspects such as coal structure, interactions between different surface groups and cross-links are omitted. The approach used in this work involves the preparation of a synthetic coal, SC, with a known structure by curing a mixture of single, well-defined model compounds. By means of chemical characterisation, the SC was shown to contain the macroscopic features of a high volatile coal (proximate and ultimate analyses). FTIR characterisation revealed the presence of functional groups similar to those of coal in the structure of the SC. Temperature-programmed pyrolysis tests were performed in a thermobalance linked to a mass spectrometer and a Fourier transform infrared analyser (TG/MS/FTIR). The thermal behaviour of the synthetic coal (i.e., rate of mass loss and the evolution profiles of gaseous compounds during pyrolysis tests) is very similar to that of the high volatile bituminous coal which was used as a reference material. The great advantage of using SC lies in the fact that its composition and structure can be accurately determined and employed in subsequent applications in basic and mechanistic studies.
A. Arenillas, C. Pevida, F. Rubiera, R. Garcia, J.J. Pis, J. Anal. Appl. Pyrolysis 71 (2004) 747-763

A1222 – Behavior of selenium in the combustion of coal or coke spiked with Se

Selenium (Se) is one of the most volatile trace metals emitted from coal-fired combustors and will most probably be considered for regulation in the electric power industry due to its significant environmental impact. Novel technologies are needed to remove Se vapor. This requires first a clear understanding of the behavior of selenium in combustion. In this work, coal and coke samples spiked with Se were prepared and the effect of Se on combustion was evaluated in a thermobalance. Impregnation with Se had a negligible impact on the combustion of coke; this allowed a systematic experimental study of the vaporization, condensation, and association of Se through burning cokes spiked with Se. Capturing the aerosol in the combustion flue gas on a membrane filter, coupled with identification of the species present using X-ray photoelectron spectroscopy, was established as a useful approach for coal combustion. The high volatility of Se and its affinity for oxygen, as well as the effect of chlorine on its vaporization, supported our previous calculations. The dominant Se species were identified as atomic Se and SeO2, which also confirmed the thermodynamic predictions.
R. Yan, D. Gauthier, G. Flamant, and Y. Wang, Combustion and Flame 138 (2004) 20-29

A1212 – The adjustment of hydrogen bonds and its effect on pyrolysis property of coal

Thermogravimetry (TG), in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFT) and on-line mass spectrometry (MS) were combined to study the effect of O-methylation and O-acetylation on the hydrogen bonds (HBs) in coal. A new method was proposed to compare the spectra of coal before and after the treatments by calibration of the band of kaolinite in coal. It was shown that both measures could reduce the amount of HBs in coal significantly (particularly the weak HBs), but neither of them could completely eliminate the HBs in coal because of the spatial resistance of three-dimensional structure in coal. It was proved that the stronger the hydrogen bonds formed by -OH groups, the less the extent to which they were reduced. The effect of O-acetylation is stronger than that of O-methylation on the reduction of HBs due to the low penetrability of the solvent used in the later treatment. Compared with the parent coal, both the pyrolysis temperature range and conversion of the treated coal increased, the initial decomposition temperature lowered, the decomposition rate accelerated and the composition of gas products was improved. Among the gases produced from the treated coal with these two methods, the amount of C1-C4 hydrocarbons increased, and CO2 and water reduced during pyrolysis compared with those of the raw coal.
D. Li, W. Li, H. Chen, B. Li, Fuel Processing Technology 85 (2004) 815- 825

A1180 – Thermal analysis of oxidised coals

The study has been performed on samples of high sulphur content Spanish brown coal Mequinenza and Polish flame coal Czeczot. The samples of raw coals and the coals oxidised by four different oxidising agents have been subjected to derivative thermogravimetry analysis (DTG). The results have shown that demineralisation has no effect on the temperature range of the maximum mass loss. The Czeczot flame coal has been shown to be characterised by a narrower temperature range of the main devolatilisation peak (380-500°C) than that of Mequinenza (320-500°C). The most pronounced structural changes in coal have been found to occur as a result of its oxidation by 5% nitric acid. After such a process of oxidation a new peak of devolatilisation appears with a maximum at 265°C, which can be assigned to the compounds having nitric groups in their structure.
R. Pietrzak, H. Wachowska, Thermochimica Acta 419 (2004) 247-251

A1132 – Supercritical gas extracts from low-quality coals: on the search of new precursors for carbon materials

This paper studies the chemical composition of several supercritical gas (SCG) extracts and its influence on the thermal behaviour under carbonisation conditions. The extracts were obtained from a Spanish lignite (Mequinenza), a low-quality coal from the point of view of energy applications. The lignite was treated with toluene, ethanol (EtOH) and tetrahydrofuran (THF) as solvents under different supercritical temperature and pressure conditions. The extracts display high aliphatic nature and enhanced concentrations of oxygen functional groups, aided by the contribution of hydrogenation and oxygen incorporation reactions occurring in the SCG extraction with EtOH and THF. Thiophenic compounds are also present in great concentrations derived from the exceptionally high organic sulphur content of the parent coal. The carbonisation of the extracts renders anisotropic material with fine mosaic texture, as a consequence of the significant thermal reactivity inferred by the aliphatic and oxygenated groups. The size of the mosaic increases with the temperature of the SCG extraction and varies with the supercritical solvent in the order: toluene < EtOH < THF.
R. Garcia, A. Arenillas, F. Rubiera, S.R. Moinelo, Fuel Processing Technology 86 (2004) 205-222

A1041 – Geochemical and micropaleontological characterisation of a Mediterranean sapropel S5: A case study from core BAN89GC09 (south of Crete)

Several geochemical and micropaleontological proxies were studied in a well developed sapropel S5 from a core collected south of Crete to investigate the causes and the mechanisms of its deposition, to reconstruct the paleoenvironmental and paleoceanographical conditions at time of its formation and to detect the roles played by productivity and anoxia. The geochemical proxies are also used to unravel the sediment provenance and therefore to help tracing water circulation patterns and freshwater sources. The multiproxy approach reveals that the sapropel layer has high internal variability and five different depositional phases can be identified, four within the visible sapropel layer. An increase in temperature and the development of a Deep Chlorophyll Maximum characterise the onset of the sapropel (phase 1), with enhanced productivity being favoured by local riverine input, not clearly ascribable to Nile river freshwater discharge, and by the shoaling of the pycnocline/nutricline. Surface water stratification and productivity develop, together with strong seafloor dysoxia/anoxia. Phase 2 is characterised by lower stratification, slightly lower temperature and/or higher seasonal contrast, and still high productivity. Phase 3 records high productivity, high temperature and high stratification, probably more sustained by the Nile input. A sudden partial reoxygenation takes place at the end of this phase, changing the main features of the sapropel. In the fourth phase, productivity starts to decrease, water stratification seems to be partially broken down and sediment oxygenation increases. A transitional phase (phase 5) occurs between the end of the visible sapropel and the normal pelagic post-sapropel sedimentation, where productivity is still high and oxygenation improves compared to the visible sapropel layer. The massive occurrence of Polysphaeridium zoharyi, cyst of a red tide forming dinoflagellate, also characterises this phase. The geochemical proxies indicate that pre-sapropel and post-sapropel sediments are quite different from each other, and the provenance shifts from a more mixed to a more markedly southern origin of sediments.
F. Sangiorgi, E. Dinelli, P. Maffioli, L. Capotondi, S. Giunta, C. Morigi, M.S. Principato, A. Negri, K-C. Emeis, C. Corselli, Palaeogeography, Palaeoclimatology, Palaeoecology 235 (2006) 192-207

A0698 – Kinetic studies of graphon and coal-char reaction with NO and O2: direct non-linear regression from TG curves

The reactions of carbonaceous materials (graphon and coal-char) with NO, O2 and NO+O2 were investigated by a thermogravimetric analysis (TGA). A method of direct non-linear regression of the kinetic equation was applied for a simultaneous calculation of the apparent activation energy, frequency factor and reaction order from a single TG curve of carbon gasification in various atmospheres. It was proven that the proposed calculation method is applicable for the calculation of kinetic parameters from overlapping processes. Calculations from TG curves of the above reactions demonstrate that NO-carbon and (NO+O2)-carbon reactions contain two processes, while O2-carbon is a single process. The reaction order of O2-carbon is approximate 0.5, while the reaction orders of NOcarbon or (NO+O2)-carbon reaction are dependent on the process and type of carbon. Graphon shows higher apparent activation energy than coal-char due to the pore structure and uncatalysed effects.
S. Wang, V. Slovak, B.S. Haynes, Fuel Processing Technology 86 (2005) 651- 660

A0673 – Kinetics of the pyrolysis and combustion of göynük oil shale

The pyrolysis and combustion kinetics of Göynük oil shale were investigated by thermogravimetric analysis in the present study. All experiments were conducted at non-isothermal conditions with a heating rate of 10-60 K min-1 in the 298-1173 K temperature interval under argon and air atmospheres for pyrolysis and combustion, respectively. Differential thermogravimetric data were analyzed by a reaction rate model assuming first order kinetics.
S. Yagmur and T. Durusoy, Journal of Thermal Analysis and Calorimetry 86 (2006) 479-482

A0562 – A simple kinetic analysis to determine the intrinsic reactivity of coal chars

"The intrinsic oxidation reactivity in air of an activated carbon char derived from bituminous coal was investigated using a new thermogravimetric analysis (TGA) method. Applying the new method, values of the Arrhenius activation energy E and pre-exponential factor A were estimated from TGA data obtained via heating samples at different constant rates. A novel statistical criterion was subsequently used to determine the heating rate at which optimum values of E and A were obtained. This is a valuable development, for in conventional non-isothermal TGA, while it is accepted that Arrhenius parameters vary with heating rate, there is no formal method for selecting one rate (and hence one set of values of E and A) over another. Using this new method, the following optimum values were obtained for the carbon at a heating rate of 25°C min-1: E=129.4 kJ mol-1 and ln(A/s-1)=10.4. These results are very similar to those calculated for the same material using more time consuming and less accurate isothermal TGA methods. It is therefore proposed that this new analysis method might be an improvement on conventional techniques to determine the intrinsic oxidation reactivity in air of coal chars."
E. Sima-Ella, G. Yuan, T. Mays, Fuel 84 (2005) 1920-1925

A0532 – Heterogeneous reduction of nitric oxide on synthetic coal chars

Model compounds, with a controlled heteroatoms content and well-defined functionalities, were used to study the release of nitrogen compounds from char combustion. In the present work, the mechanisms involved in NO-char heterogeneous reduction were studied with a synthetic coal (SC) char as carbon source. Another synthetic char (SN) without any nitrogen in its composition was also employed in these studies. Temperature programmed reduction (TPR) tests with a gas mixture of 400 ppm NO in argon and with isotopically labelled nitric oxide, 15NO (500 ppm 15NO in argon), were carried out. The gases produced were quantitatively determined by means of MS and FTIR analysers. Under the conditions of this work the main products of the NO-C reaction were found to be N2 and CO2. The main path of reaction involves the formation of surface nitrogen compounds that afterwards react with nitrogen from the reactive gas to form N2. It was observed that fuel-N also participates in the overall heterogeneous reduction reaction, although to a lesser extent.
C. Pevida, A. Arenillas, F. Rubiera, J.J. Pis, Fuel 84 (2005) 2275-2279

A0488 – TG-FTIR study of gaseous compounds evolved at thermooxidation of oil shale

The combined thermogravimetric (TG) Fourier transform infrared (FTIR) techniques were used for studying the gaseous compounds evolved at thermooxidation of oil shale samples from different deposits (Estonia, Jordan, Israel). In addition to H2O and CO2as the major species, the formation and emission of CO, SO2, HCl and a number of organic species as methane, ethane, ethylene, methanol, formic acid, formaldehyde, chlorobenzene, etc. was determined. Differences in the absorbance of respective bands in FTIR spectra depending on the origin of oil shale and on the heating rate used were established.
T. Kaljuvee, J. Pelt, M. Radin, Journal of Thermal Analysis and Calorimetry 78 (2004) 399-414

A0487 – Thermal degradation kinetics of Göynük oil shale with polystyrene

Göynük oil shale, polystyrene and several polystyrene-oil shale blends were degraded in a thermobalance apparatus at atmospheric pressure. Experiments were carried out dynamically by increasing the temperature from 298 to 1173 K with heating rates of 10 and 60 K min-1 under an argon atmosphere. Derivative thermogravimetric data were analyzed by a reaction rate model assuming first order kinetics. Effects of blending ratio of oil shale and polystyrene and heating rate on the thermal degradation kinetics were investigated. Kinetic parameters were determined and the results were discussed.
L. Degirmenci, T. Durusoy, Journal of Thermal Analysis and Calorimetry 79 (2005) 663-668

A0438 – Characterisation of the oxidation products of pyrite by thermogravimetric and evolved gas analysis

The identification of the main components of urinary calculi, the knowledge of the true number of water molecules bounded to the calcium oxalate, and the determination of each hydrate in the mixture, are the interests of this memory. The thermal analysis (simultaneous DTA-TG) was applied on thirty-three urinary calculi. The determination of the calcium oxalate hydrates was confirmed by calorimetry (DSC).
P.S. Thomas, D. Hirschausen, R.E. White, J.P. Guerbois, A.S. Ray, Journal of Thermal Analysis and Calorimetry 72 (2003) 769-776

A0432 – Simultaneous thermogravimetric-mass spectrometric study on the pyrolysis behaviour of different rank coals

Simultaneous thermogravimetry-mass spectrometry was used to study the pyrolysis behaviour of an anthracite and three bituminous coals of different volatile matter content. This system was optimised by using calcium oxalate as a reference for calibration. A normalisation method that permitted a semiquantitative comparison between the volatile species of the coals was also developed. The instantaneous evolution of the volatile compounds was studied by means of temperature-programmed pyrolysis experiments. The peaks varied in shape, temperature and size, and showed a marked dependence on coal rank. This can be attributed to the varying amounts of the different functional groups in the coals studied. Special attention was paid to the nitric oxide released during pyrolysis, together with its precursor species.
A. Arenillas, F. Rubiera, J.J. Pis, Journal of Analytical and Applied Pyrolysis 50 (1999) 31-46

A0341 – A study of the self-heating of fresh and oxidized coals by differential thermal analysis.

Differential thermal analysis (DTA) has been used as a method to study the self-heating behaviour of fresh and oxidized coals. Oxidation was performed in air at 200°C for periods of up to 72 h. Six coals ranging from a High A Bituminous coal to a semi-anthracite were used. As the rank of the coal increases, both the self-heating and the end of combustion temperatures also increase. The total heat loss (area under the DTA curve) increases with the rank of the coal. An increase in the self-heating temperature, a decrease in the temperature of the end of combustion and a decrease in total heat flow were observed as a consequence of coal oxidation. A relationship between the total heat loss and the calorific value as determined using the ASTM standard method is pointed out.
J.J Pis, G. de la Puente, E. Fuente, A. Moran, F. Rubiera, Thermochimica Acta 279 (1996) 93-101

A0247 – Coal pyrolysis : thermogravimetric study and kinetic modelling

In this experimental study on coal pyrolysis it was found that heat transfer and heating rate have an important influence on the results obtained. A model has been developed which takes into account these aspects. The kinetic parameters were determined using a differential method and the experimental data obtained at low heating rates. The agreement between the predictions of the model, for any heating rate, and the experimental values is fairly good.
T. Coll, J.F. Perales, J. Arnaldos and J. Casal, Thermochimica Acta 196 (1992) 53-62

A0225 – Thermochemistry of coal oxidation.

Five types of Polish bituminous coal of different grades were analysed using, simultaneously, thermogravimetric analysis (TGA), differential thermogravimetry (DTG), differential thermal analysis (DTA) and evolving gas analysis (EGA) to investigate the non-isothermal coal oxidation. The TGA, DTG and DTA curves, together with EGA, provided parameters which characterize the tendency of a given coal towards oxidation. The TGA and EGA parameters can also be used to approximate the specific active surface area of coal in reaction with oxygen. Due to the negative effects of coal oxidation, such as self-oxidation, an inhibitor was proposed and tested by analysis of the above specified thermoanalytical curves and EGA.
M.S. Matyjaszczyk, R. Przeliorz, Thermochimica Acta 96 (1985) 169-187