Pyrolysis is a coal conversion technology that plays an important role for the production of different chemicals like methane, hydrogen, different organic fractions or sulfur compounds.
Pyrolysis is a coal conversion technology that plays an important role for the production of different chemicals like methane, hydrogen, different organic fractions or sulfur compounds.
The influence of pressure over the thermal decomposition behavior of mineral materials is important in order to asses their reactivity and stability. Calcium oxalate monohydrate is a well characterized material frequently used to check the performance of a thermogravimetric analyzer.
High temperature, corrosion resistant superalloys need to be characterized in terms of their oxidation kinetics. Thermogravimetric analysis (TGA) is the perfect tool for tool to get the full picture of the oxidation behavior. These characterizations require the TGA instrument to provide a good gas-solid interface, a high mass signal stability over long periods of time and a efficient control of the sample atmosphere . These requirements are met by the THEMYS TGA.
Zeolith-Imidazol-Gerüste (ZIF) sind eine Klasse von metallorganischen Gerüsten. Dank ihrer hochporösen Struktur können sie verwendet werden, um Kohlendioxid aus ihren Strömen zu entfernen. Die thermogravimetrische Analyse kann verwendet werden, um die Sorptionskapazität zur Bestimmung von porösen Materialien reine contre (wie in dem vorliegenden Beispiel), oder komplexe Gasmischungen, zusammen mit der Bewertung der Sorptionskinetik bei einer gegebenen Temperatur.
Why isothermal stability?
A stable signal under isothermal conditions is required for many gas-solid experiments like oxidation, reduction, adsorption, and more particularly when looking for kinetics data.
Why is drift and precision data important?
A properly designed TGA instrument should be based on a reliable thermobalance:
Exploring the limits of quantification
As proof of the outstanding performance of the THEMYS HIGH SENSITIVITY balance, a series of tests were run with a decreasing initial sample mass of a well-characterized material : copper sulfate pentahydrate.
Metal-based inorganic nanoparticles are one of the most studied materials due to their innumerable applications. Moreover, the compound functionalization with organic ligands results essential for some uses, e.g. in drug delivery technology. Even if several techniques are common available to establish size, structure and morphology of the particles, the identification of the quantity and the way in which the
ligands are attached on their surface is not trivial.
Some steel based alloys, when quenched after being overheated, form a given quantity of residual austenite. This crystalline phase is undesirable in quenched steels and is critical in the final quality of the product. This is particularly important in the field of steel recycling.
Thermogravimetry (TG) or Thermogravimetric Analysis (TGA) measure the mass loss or gain of a sample of material as a function of time or temperature when it is heated or cooled under a certain temperature profile. Simultaneous thermal analysis (TG-DTA or TG-DSC) additionally allows qualifying or quantifying the corresponding heat effects. But these two methods do not allow for the definite identification of the products of the studied reactions or decompositions and for the determination of their chemical mechanism.
Titration TGA is a method for dosing a gas or a vapor aliquot (i.e. of known amount) on a sample being
weighed by a TGA balance. It can be applied to the study of physisorption or chemisorption phenomena
and to some extent to all gas-solid reactions (e.g. oxydo-reductions).
A loss-on-drying test is designed to determine the amount of any kind of volatile matter in a sample when the sample is dried under specified conditions. Here, the loss-on-drying of a lubricant (cutting oil) was determined using the LABSYS evo TGA 1150, according to the procedure described in the ASTM E1868-10 standard. This test method applies to a wide variety of solid or liquid materials, mixtures or blends when the major component is stable at the test temperature.
The emissions of volatile organic compounds (VOC) has become one of the main concerns of numbers of industries. Due to their major impact on the environment and human health, international policies have become more and more restrictive with regard to VOC emissions. Moreover, their poor chemical compatibilities with many materials may lead to damages when they are evolved in confined systems.
Die Bestimmung der kinetischen Parameter einer Zersetzung ist ein wichtiger Schritt zur Bewertung der Stabilität eines Materials. Verschiedene Techniken, Modelle und Standards wurden entwickelt, um diese Kinetiken besser zu verstehen. Hier wurde die Zersetzung von Polyethylenterephthalat Probe (PET) wurde durchgeführt unter Verwendung der TGA LABSYS EvO 1150. Das Verfahren angewendet die von dem ASTM E1641-13 Standard beschrieben, qui die Ozawa / Flynn / Wand isoconversional Methode verwendet.
Instrumentation may need to be adapted when meant to be used in unusual laboratory environment. Among the most challenging laboratory conditions are those of the International Space Station (ISS)…
Calorimetry is a common technique for the characterization of water-in-oil emulsions that can be met in the petroleum or food industry fields. A phenomenon affecting the stability of emulsions is know as coalescence, which refers to the merging of small water droplets into larger ones. Gravity being one of the driver for coalescence, researchers from the European Space Agency initiated the FASES (Fundamental and Applied Studies on Emulsion Stability) project, to study the impact of the absence of gravity on emulsion stability. They consulted SETARAM Instrumentation to develop a calorimeter able to fit with the challenging conditions of a laboratory in space.
Some studies may not be possible with standard thermal analyzers or calorimeters because of some limitations in terms of pressure, temperature, resistance to corrosive atmospheres, etc. But in many cases, the adaption of a few elements of these analyzers can change the situation and allow fitting them to the needs of such studies.
A very large number of reactions now involve solid catalysts. Their evaluation has become a major concern for industrial processes. The Calvet calorimeters are particularly well adapted to help in understanding heterogeneous catalytic processes. Thanks to the large number of calorimetric cells that can be used, they allow matching many industrial conditions .
In the following application, the goal was to develop a cell enabling the possibility of measuring the heat of conversion of gaseous 2-butene to 1-butene flowing through a catalytic bed.
It may occur that standard instruments are limited in terms of application because of temperature, pressure ranges available, because of the lack of chemical compatibility of some materials against the atmospheres to be tested, or because some functionalities aren’t available.
Thermogravimetry is a common technique for the characterization of the thermal stability of materials, to understand their degradation process or to analyze their composition. Some materials like fluorides or oxyfluorides – which have interesting optical properties – release significant amounts of corrosive gases during their thermal stability testing. To fit to a customer request, our standard SETSYS Evolution TGA was modified in order to stand the release of fluorine and hydrofluoric acid (up to 20% of initial sample mass). A further challenge was that the users wanted to test the material mass uptake under a flow of a gas containing up to 10% in mass of fluorine.
Coupling analytical methods can be a way to draw more information from a single sample to understand more into depth its chemical / physical behavior, or to obtain simultaneous data under the exact same conditions. But it requires the evolution of standard analyzers so that they can physically fit and that they are not disturbed by their simultaneous operation.
A good way to determine the adsorbed species on the surface of a catalyst is infrared spectroscopy, while thermogravimetry is a good tool for the quantification of those adsorbed species. The Laboratory of Catalysis and Spectrochemistry of Caen (France) approached us to modify a standard microbalance in order to fit it with operando IR spectroscopy. The goal was to develop a TG-IR coupling with an IR beam directly oriented to the surface of the catalyst being weighed by the balance.
Radioactive materials science requires handling of hazardous substances (fuels, wastes, reactive gases, etc) under safe conditions for the operators and characterization instruments. In a lot of cases, these materials need to be handled in glove boxes or in hot cells (lead chamber) depending on the radiations types and intensities.
Thermal analysis and calorimetry are common thermal characterization techniques for nuclear fuels (current or candidates), wastes, and surrounding materials (ex: cladding). It means that the instruments concerned must be customized to become compatible with these specific operating conditions.
Glass-ceramics (wollastonite–plagioclaseglass-ceramics in this case) are materials produced from parent waste glasses by controlled crystallization at higher temperatures, which results in a growth of one or more crystalline phases within the vitreous mass. The most advantageous properties of those type of materials are high flexural strength (100– 120 MPa), high resistance to weathering and a zero water absorption rate.
The evolution of the crystalline phases and microstructures during the crystallization process of a glass derived from FGRP (Fibreglass Reinforced Plastics) wastes is analyzed.
Shows the possibilities of DRC
in recent years, increased efforts are under way to develop materials with reversible H2 storage properties meeting the targets for on-board applications fixed by the US Department of Energy. At this respect, it is fundamental to evaluate with accuracy both the thermodynamic and the kinetics sorption properties of the candidate materials.
On the analytical point of view, the coupling between a manometric technique (PCTPro) and a calorimetric technique (Sensys DSC) is very interesting as both the absorbed/desorbed volume of hydrogen together with the corresponding enthalpy is measured on the same sample.
Solutions to work with TGA under aggressive and corrosive atmospheres
The requirements for thermal analysis under humid atmosphere with a specific humidity
The input of hyphenated techniques in the field of thermogravimetric analysis has now long been proved, with a large number of applications for TG-MS or TG-FTIR. They have showed themselves particularly interesting when the chemistry of a reaction or thermal decomposition has to be elucidated thanks to the qualification of the evolved chemicals.
However, these techniques are limited in numerous cases, especially when a large number of molecules are evolved in a short period of time, or more specifically in the field of TG-MS if high molecular weight molecules are ionized into multiple smaller fragments. This is particularly the case when analyzing the thermal decomposition of complex organic substances such as biomass or polymeric materials.
This is why the technique of TG-GC-MS is becoming increasingly popular, as gas chromatography allows a first separation of the evolved species, before their identification by the mass spectrometer.
Eine Kombination aus Kalorimetrie und Kalorimetriemethode. Die mit der Wechselwirkung zwischen den Substanzen verbundene Wärmefreisetzung wird dann von den ersten Augenblicken an gemessen. Eine solche Bestimmung kann für thermodynamische und kinetische Parameter von Prozessen wie chemische Reaktion, Adsorption oder Auflösung durchgeführt werden.
Use of the PCTPro for measurements at very low temperature
With the recent advances in solid state research and the development of new synthesis paths, only small amounts of material are produced. To investigate the sorption properties of these small samples an accurate tool for measurement is required. The PCTPro-2000 can measure sample quantities down to mg’s thank to its Microdoser attachment
The boiling point of a pure compound is one of the essential information necessary to know before any industrial implementation. Nevertheless, its determination needs very specific conditions to limit the influence of the atmosphere. Indeed, internal gas convection, vapor pressure in the crucible or kinetic of vaporization are important factors that play an important role in the measurement. To determine precisely the boiling point, those factors have to be optimized. The DSC technique can be used for such a measurement
Solutions to work under corrosive or fluorine atmospheres
The MHTC 96 drop calorimetry is very convenient for the investigation og metals and alloys, for minerals and axodes, for any advanced material.
The Thermal Energy Storage (TES) is defined as the temporary storage of thermal energy at high or low temperatures. As most of the renewable energy sources (solar, wind, …) are intermittently available, the target of TES is to improve performances of energy systems with a smoother supply and an increased reliability.For each TES mode, various types of transformations or reactions are available and are well known. This application note will demonstrate how the thermal analysis and calorimetric methods are used to investigate the
different TES techniques and to characterize the materials (solid and liquid) used in the corresponding processes.
Modern industry requires more and more materials resisting to high and very high temperatures. A good characterization of these materials is becoming necessary in order to precisely measure their properties, to know their field of applications and also their limits of use. Among all the properties needed, heat capacity data are required at high temperature to be combined with thermal conductivity and thermal diffusivity.For material scientists there is a key issue to accurately measure the heat capacity of samples, especially at high temperatures. Many calorimetric devices and methods have been used to meet the requirements but the DSC technique remains the most often used for such a determination. The major difficulties in this case, besides the matters of simply reaching high temperatures or building measurement systems with materials than can stand high temperatures, is to overcome the drop of sensitivity of commonly employed thermocouples when approaching their upper limit of use or to deal with perturbations linked with the radiation effects of the measured samples. Another difficulty is related to the plate-type DSC technique that limits the amount of material to be investigated.The solution is to use the technology developed around the Calvet principle (3D) sensors that has been successfully used in the accurate determination of specific heat with various types of thermal analyzers. Based on this expertise, a 3D detector was designed to be used on the Labsys DSC for the Cp determination at high temperature.
The plate-type DSC technique is today a largely used technique for the thermal investigations of materials up to very high temperature (1600°C). However the main limitation of the technique is the small amount of material that can be investigated. In the case of weak thermal effects or also for experiments on non homogeneous samples, the results provided by the plate-type DSC technique are most of the time very poor. In order to provide a better solution for these types of investigations, Setaram has selected the technology developed around the Calvet principle (3D) sensors that has been successfully used for many years in the development of calorimetric detectors. Based on this expertise, a 3D DSC detector was designed to be used on the Labsys DSC for the Cp determination at high temperature, but also for the investigation of large amounts of samples up to 1600°C.
Some experiments carried out at constant temperature consists of monitoring the calorimeter output over a long time period and measurements of minor thermal variations. To be sure that the measurement is significant it implies that the calorimetric output with an inert sample must be very stable. The curve shown below is the type of curve that could be expected on using the standard equipment without any special devices like main stabilizers, thermostated water circuit or air conditioners : it has been carried out in a normal room but under the following conditions : no heating system, closed shutter, no air stream in the room : the general rule is to avoid any rapid room temperature variation.
Demonstrate the capability of SensysDSC to measure heat capacity even of material having a low density
On using the circulation mixing vessel it is possible to inject two different liquids continuously. Thus, the titration of an acid by a base is possible. On changing the flow-rates given by the two pumps the ratio HCI / NaOH is modified, but the total flow-rate is kept constant. For this application the micro-DSC must be used with a pair of circulation mixing vessel (S60/112014), the temperature prestabilizer (S60/26626) and two Peristaltic 2-channel pumps (2 times S60/29332)
Kinetic determination using the PCTPro for hydrogen adsorption and desorption
The SetsysTMA allows measuring variations in dimension of the sample when this sample is subjected to a temperature program under a non-oscillatory load. Dilatometric measurements under small loads can be carried out with SetsysTMA as well as stress-strain studies under various deformation modes (compression, penetration, traction, flexure) with appropriate probes.
Depending on the temperature range, three versions are available.
The thermomechanical behavior of fibers or films can be highlighted by using a special device for traction studies. The sample is maintained between two clamps. The upper clamp is linked to the sample-holder tube whereas the lower clamp exhibits a hole in which the hooklike end of the probe is introduced.
To assess the thermal expansion coefficient of a sample, the variation in length of this sample, ?L sample, has to be plotted against temperature T. With a non-differential system, the raw expansion curve obtained can be described by the following equation : ?L sample – ?L assembly + drift = f(T)
?L assembly is due to the expansion of the material making up the probe and the sample-holder tube which is not compensated for the length of the sample. The drift term is due to a temperature gradient between the sample-holder and the probe. With an adapted software it is possible to correct the raw data of the two above interfering terms and thus obtain the expansion curve of the sample.
Presents the experiment of determination of critical temperature and pressure of hexane
Presents the melting curve of a small mass (0,15 mg) of gold
Calibration is essential for a calorimeter : the accurate determination of the calibration factor conditions the quality of the obtained results of energy. In a conventional DSC the heat transfer between the sample and the heat sink passes through the lower part of the crucible. In a Calvet type DSC such as DSC111, DSC121 and microDSC’s, this heat transfer is done in all directions. These properties give to Calvet type DSC much better metrological properties such as the linearity of the output of a DSC to power dissipated in its heart.
The Mathis modified transient plane source technique offers the only method available today to test vacuum-sealed materials.
Connected to the Joule effect calibration device (S60/1429) this vessel consists of a resistor, which dissipates a constant heat power. The value of the power can be selected on the calibration device. Linked to a microcomputer the procedure of calibration is the automatic : it provides the calibration curve on the whole temperature range.
testing through skins
Some experiments require monitoring the thermal behavior of a substance at successively different temperatures (see sheet AN334 : Propellant stability).
Some instruments available on the market have a water bath of 20-30 liters and for this reason are thermally very inert : after a modification of the set temperature they require about 24 hours to have a stable signal. The curve here under shows the calorimeter response after a set temperature modification.
TG-DSC was used to determine the critical point of water
Thermogravimetry measures the mass loss or gain of the sample and DTA detects the corresponding thermal effects. But, these two methods do not identify the type of reaction or decomposition which measure the mechanism of the transformation. With a mass spectrometer linked to TAG, gases with a molar mass between 1 and 300 g are controlled with a high detection limit.
Coupling a Fourrier Transformed Infrared Spectrometer makes it possible to identify evolved gas during a thermal analysis. All products of decomposition can be detected and compared with reference spectrums, except for metallic or monoatomic compounds.
This powerful method has application in many fields ; polymers, inorganic materials, fiber..
The alumina tube used up to 1750°C is removed to work up to 2400°C. The experiment is run directly in the graphite resistor under vacuum or inert gas (except nitrogen).
The TGA-DTA probe used is made with a tungsten plate and four wires in W/Re for the measurement of the temperature of the sample and the DTA signal up to 2400°C.
The DTA transducer is made of tungsten and tungsten rhenium thermocouples to work up to 2400°C. It is less sensitive than a classical DTA rod made of platinum but small energy changes can be detected. Rhodium is a good example with a small enthalpy of melting of 50 cal/g.
The DTA rod made of tungsten rhenium can be calibrated by a melting of a standard such as sapphire.
At very high temperatures, only sapphire can be used because properties like melting point and enthalpy are well defined. The temperature given by thermocouples can be checked and the DTA signal calibrated.
This liquid and gas tight vessel is used for any kind of investigation which requires the analysis of a liquid or a solid totally sealed off from the outside environment. For example even minute sample loss through evaporation is avoided. The seal is obtained by the elastomer 0-ring.
The Calvet Low Temperature calorimeter BT 2.15 is especially designed for calorimetric investigations from very low temperature (-196°C) up to medium temperature (200°C). The size of its experimental vessels is identical to the C80 one. In order to have compatible vessels on the C80 and the BT 2.15, identical vessel bodies are used for the standard, vacuum and gas circulation vessels (normal and high pressures). The length of the pipe connecting the vessel to the outside is different.
With this vessels it is possible to introduce a liquid (or a gas). The liquid enters first the temperature prestabilizer (S60/26626) in which it flows in a loop. In this zone the temperature of the liquid equilibrates to the temperature of the calorimeter. The liquid then enters the lower part of the vessel. The liquid (gas) then exits via the outlet tubing. Generally a peristaltic pump is used (S60/29332).
The TAG provides the investigator with a symmetrical TGA-DTA system which means with two furnaces. Deviation on the thermogravimetric signal is equivalent to 1.5 mg at 1000°C with a monofurnace system. That is only due to the combined resulting form the buoyancy effect which vary with the density of the gas, combined with the driving force produced by flowing gases and other disturbing effects.
These perturbations are physically compensated with a second furnace. Moreover, thanks to homogeneity in the furnaces, the DTA signal is stable.
With this vessel it is possible simultaneously to introduce two liquids. They are injected by two peristaltic 2-channel pumps (S60/29332) or by gravity.
The liquids enter first the temperature prestabilizer (S60/26626) through which they flow in a loop. In this zone the temperature of the liquid equilibrates to the temperature of the calorimeter. The two inlet liquids are then forced to be mixed through a mixer. The resulting heat is then monitored by the transducer. The mixture exits through the outlet tubing.
The major advantage of the TGA-DTA rod is analysis on the same sample. Thermogravimetry and thermal analysis can be quantitative thanks to a calibration of this rod.
Melting of metals gives a sensitivity of the rod at different temperatures and quantitative analysis can be run. The enthalpy of a thermal effect can be calculated when introducing the calibration of the rod into the computer during a data treatment.
The accuracy of the measurement of the heat capacity of the liquid by calorimetric method depends on a correction term due to the vapor phase above the liquid. In order to overcome this difficulty, a special calorimetric vessel has been designed. The main feature is a tube welded to the experimental vessel. It is filled through one tube by means of a syringe, until the liquid comes out through a second tube. When the liquids is heated it expands freely in the tubes but the volume of the liquid in the vessel, located in the detection zone of the calorimeter remains constant. The determination of the heat capacity of this corresponding volume is achieved using the step heating mode.
Notice : the heat capacity can also be measured by using the sealed vessel (S60/1528).
The sample is then in the presence of its vapor pressure : it is suitable for solids but can sometimes also be used for liquids.
Some compounds have a high vapor pressure or evolved gas which are reactive with platinum or alumina.
These materials can be analyzed in sealed crucibles (fig. 1) under vacuum or known atmosphere. The sensitivity of the DTA transducer is more than enough to detect thermal effects.
Experiments were run with sulfides which are reactive to platinum at low concentrations.
Mass loss of organic compounds are sometimes very long because they are enclosed in a mineral. For a long term experiment, it is important to have a good regulation of temperature and a controlled atmosphere, without leaks, in order to protect the sample from air exposure.
Analyzed oil-bearing rock contains organic compounds ; evolved compounds should be a function of a temperature level similar to a distillation.
For some types of mixing, the reversal mixing vessel (see application sheet TN252) is not adapted : incompatibility of mercury with the samples, mixing of viscous substances. It is replaced by the mixing vessel with membrane. A membrane separates the two chambers eliminating the use of mercury. Mixing is performed by piercing the membrane by a rod which also acts as a stirrer (manual stirring). In the case of viscous substances or formation of a solid during the reaction, a continuous stirring is obtained by adapting a driven motor on the rod. When possible the reversal mixing vessel is preferred to the mixing vessel with membrane. It gives a better precision (no connection with outside).
Many powdered compounds (catalysts, oxides, coals,..) are characterized by their surfaces. The measurement of physical or chemical interactions between any solute with the surface of powders characterizes their reactivity. Flow calorimetry is well-adapted method for such an investigation. The liquid percolation vessel enables the liquid to pass through the powder, deposited on a poral filter. The typical experimentation consists in using a first percolation of a carrier liquid in order to achieve the wetting of the powder. Then it is substituted by a solute and the adsorption heat of the solute on the powder is directly measured. After this process the solute is replaced by the carrier liquid and the adsorption heat is measured.
Die Genauigkeit der Wärmekapazität einer flüssigkeitskalorimetrischen Methode hängt von der flüssigen Phase ab. Um diese Schwierigkeit zu überwinden, wurde ein spezielles kalorimetrisches Gefäß entwickelt. Das Hauptmerkmal ist ein mit dem Versuchsgefäß verschweißtes Rohr. Die Befüllung erfolgt mit einer Spritze durch das Röhrchen, bis sich eine Flüssigkeit im Röhrchen befindet. Der obere Teil des Gefäßes befindet sich nicht mehr im Versuchsgefäß. Wenn die Flüssigkeit erwärmt wird, dehnt sich die Flüssigkeit im Rohr frei aus, aber das Flüssigkeitsvolumen im Gefäß, das sich in Richtung der Kalorimeterzone befindet, bleibt konstant. Die Bestimmung der Wärmekapazität dieses Volumens erfolgt im Stufenheizmodus.
In most organic reactions, the stirring of the mixture has to be maintained during the reaction for a good homogeneity of the mixture and for improving the efficiency of the reaction. In industrial reactors, large amounts of chemical products are continuously mixed by means of mechanical stirrers. It can be the reaction of two liquids giving a crystallized solid, or the mixing of a liquid and a solid giving another solid, or also reactions between solids. In all cases, stirring and sometimes strong stirring, is needed.
SETARAM has designed a mixing vessel linked with a mechanical stirrer in order to simulate types of reactions and to evaluate what is the heat evolved during mixing and reaction. These data are helpful to design the reactor and its cooling system.
Gas adsorption investigation requires a good contact between the gas and the solid. A silica reactor has been designed for the Calvet DSC111 in which the reactive gas flows through the sample situated on a sintered glass. This particular cell design is especially interesting for the gas-solid reactions or also for the investigation of reactions occurring in a corrosive medium. The exhausted gases are easily analyzed at the outlet of the silica tube by means of a gas chromatograph or a mass spectrometer (see application note AN226).
Many organic materials used in chemical reactions exhibit an hazardous behavior when heated. Their composition may produce a large amount of vapor and increase very highly the pressure in the reactor. So the pressure, especially its evolution during the reaction, has to be well known in order to design correctly the reactor and the safety devices to prevent any risk of explosion and destruction of the reactor. Chemical plants are especially interested in this pressure control during reaction or storage.
SETARAM has designed a calorimetric high pressure vessel linked with a pressure gauge in order to evaluate in the same time the pressure evolved during the reaction and to follow the heat dissipated. Both data can be used to calculated the reactor dimensions and to evaluate the risk of decomposition.
Many solid porous compounds, especially zeolites, are well known for their adsorbing properties. In order to measure their adsorption capacity, a special experimental set-up has been designed for the C80 calorimeter. This device allows characterizing the adsorption of vapor on a solid under reduced pressures. The liquid to be adsorbed is initially frozen, then kept at a well-defined temperature, determining a well-known vapor pressure. This vapor is adsorbed on the solid, previously regenerated under vacuum.
Isothermal thermogravimetry is a very interesting method for the investigation of gas adsorption. An experimental thermogravimetric device is described, which allows running such tests at low temperature under reduced pressure, or with a linear programmation of the pressure. This is particularly well adapted for the determination of specific surface of compounds, and also to measure the capacity of gas adsorption of molecular sieves at low temperature.
The standard vessels are simple tight containers to be used in the C80 calorimeter when the experiment requires no physical contact between outside and sample. Depending on the internal pressure in the container (gas evolved during heating) two models are available : the normal pressure vessel for investigations at medium temperature (220°C) and low pressure (5 bars) and the high pressure vessel for investigations at higher temperature (300°C) and high pressure (100 bars).
The main feature of the vacuum vessels is the connection pipe between the container and outside. Vacuum in the container and also a static pressure of gas are obtained through the pipe. With this facility, different types of experiments are possible : purge the sample before applying a pressure of inert gas, work under vacuum or reduced pressure, work under static pressure of reactive gas (up to 100 bars).
In the gas circulation vessels, the connection consists of two coaxial pipes, to enable the continuous and intermittent circulation of gas on the sample (liquid or solid). At the outlet of the vessel, the evolved gases carried by the sweeping gas can be analyzed on line through a gas analyzer. The gas circulation vessels are used with different types of carrier gas (inert, reductive, oxidative) at various pressures, depending on the model of vessel. Using an adapted gas circuit, different ways of experimentation are possible : use a simple carrier gas, or start an experiment with inert gas and switch for active gas in the second part of the experiment, or introduce an active gas in the carrier gas.
The two chambers of the reversal mixing vessel are separated by a tilting lid. The samples (liquid-liquid or liquid-solid) are separately introduced into the vessel outside of the calorimeter. In order to obtain a complete separation of the chambers, a mercury seal on the lid can be used. If the vapor pressures of the samples are low, the mercury seal is not required. After the introduction of the vessels into the calorimeter, the thermal equilibrium is to be achieved in order to have the two separated components at the same temperature. Then, mixing is performed by reversing the calorimeter. If the samples mix easily, only a few rotations of the calorimeter are necessary. In the case of difficult mixing, the reversing mechanism can be maintained during the whole test.
Mixing or reaction of two liquids, particularly when they are viscous
(polymerization, organic synthesis..).
For special applications (oxidation, reduction, decomposition), the pressure of reactive gas must be initially fixed in the experimental crucible. The described pressurization device is designed for the initial pressurization of the sealed high pressure crucibles with inert or reactive gases, after a previous degassing of the sample. The stainless steel crucibles are sealed under the pressure chosen on the control high pressure panel.
Applications of many powdered compounds (catalysts, oxydes, coals..) are dependent on their surfaces. The measurement of physical or chemical interactions between any solute with the surface of powders characterizes their reactivity.
Flow calorimetry is a well adapted method for such investigation. A special flow cell is designed and allows the percolation of liquids through a powder. The solutes are introduced in a carrier liquid. Adsorption and desorption reactions can be investigated.
Describes the ampoule mixing vessel which enables the determination of heat of wetting of a powder
Presents the adsorption of ethanol onactive carbon using the ampoule mixing vessel
Explains what is a titration calorimeter
Shows the titration of a HCL solution by a NaOH solution
Explains the different methods for the determination of heat capacity
Explains the different methods for the determination of heat of mixing and heat of interaction between solids, liquids, solids with liquid, solid or solid with gas
Shows the possibilities of DRC
Presents the cooling curve of a Labsys
Presents the cooling curve of a Setsys
Presents the cooling curve of a Setsys-cryo
Presents the cooling curve of a mHTC or other eqipment of the 96 line
The batch mixing cell enables two liquid bodies (or one liquid body and one powder body) to be mixed and their mixing heat to be measured. The mixing cell comprises two volumes that are initially hermetically separated by a membrane. As is shown in Figure 1, a piston fitted with a mixer is used to pierce the membrane. In a second phase, two sample volumes are brought into full mutual contact and mixed in a continuous and equal manner in the measuring and reference cells
Presents the determination of heat of dissolution of KCl in water on using reversing mixing vessel and reversing mechanismwith
Describes the ampoule mixing vessel which enables the determination of heat of wetting of a powder
Presents an accessory which protects the inside of the furnace of setsys when corrosive atmosphere is to introduced
Presents a crucible enabling to measure the heat of vaporization of a liquid, See example of vaporization of water in TN095
Presents the determination of heat of vaporization of water : see also application note TN094 for description of the crucible
Presents the melting of inndium under helium, air, argon and vacuum
A method is presented for obtaining Cp at constant pressure in the temperatur erange 343K to 548K at pressures up to 20MPa with an estimated accuracy of ± 0.003 Cp