Tian-Calvet microcalorimeter

M. Laffitte. Trends in Combustion Calorimetry. The Use of the Tian-Calvet Microcalorimeter for Combustion Measurements. In Experimental Chemical Thermodynamics, vol. 1 S. Sunner, M. Mansson, Eds. IUPAC-Pergamon Press Oxford, 1979 chapter 17 3. 

Measurements of the change of temperature of a solid on being stretched or compressed were first made by Joule in the 19th century and extensive studies on rubbers by Muller about 20 years ago. For plastics little work has been done until the recent studies of Haward and his associates40 and the work, using the Tian-Calvet microcalorimeter, of Godovskii et al.41 ... 

The simultaneous measurement of the heat of adsorption and the adsorbed amount of H20 was performed by means of a Tian-Calvet microcalorimeter, operating at 303 K, connected to a volumetric apparatus. The samples were pretreated in vacuo at the chosen temperature and subsequently transferred into the calorimeter without further exposure to air. Small doses of water were subsequently admitted onto the sample, the pressure being continuously monitored by a transducer gauge (Baratron MKS, 0-100 Torr). 

We shall examine here the two major procedures for gas adsorption calorimetry (cf. Section 3.3.3). Both procedures make use of a diathermal, heat-flowmeter, Tian-Calvet microcalorimeter (cf. Section 3.2.2). 

Two operational arrangements fulfilling the above requirements are represented in Figures 5.16b and 5.16c. For convenience, both are incorporated in a Tian-Calvet microcalorimeter with large cells (i.e. c. 100 cm3). The first device uses a disc stirrer (up and down movement) and cancels any temperature difference between the added solution and the adsorbent by placing both the adsorbent and the solution reservoir in the top part of the microcalorimetric cell (Rouquerol and Partyka, 1981). The second device uses a propeller which is given very fast half-turns (c. 10 per minute) by means of a hindered magnetic transmission which serves to damp the vibrations from the motor. 

A batch microcalorimetric experiment, very similar to the one just described, is possible with a diathermal heat flowmeter type of microcalorimeter, which is less versatile than the Tian-Calvet microcalorimeter (especially in its temperature range and ultimate sensitivity), but of a simpler design. In the Montcal microcalorimeter (Partyka et al., 1989), the thermopile with up to 1000 thermocouples is replaced by a few thermistors. 

Immersion calorimetry can be used to study either the surface chemistry or the texture of active carbons. A sensitive Tian-Calvet microcalorimeter is adaptable for either purpose, the main difference being in the choice of wetting liquids. 

Heats of adsorption were measured at 303 K with a Tian-Calvet microcalorimeter (Setaram), connected to a vacuum/gas volumetric apparatus, that enabled the simultaneous determination of adsorbed amounts by the stepwise contact with subsequent doses of the adsorptive [5]. 

Heats of adsorption of water vapour on J7-A1203 have been determined by means of a Tian-Calvet microcalorimeter at temperatures between 25 and 740°C. 8... 

The aim of this classification is mainly historical. It introduces the reader to the way of thinking of the thermochemists prior to 1912 and does not pretend to be comprehensive and modem. Quite logically, it does not include, for instance the Tian-Calvet microcalorimeter. 

Figure 6.3. Section of a Tian-Calvet microcalorimeter as produced by the SETARAM company...

A Tian-Calvet microcalorimeter (model BT 2.15, Setaram, France) was used to measure the enthalpies of adsorption of propane and propylene at room temperature. The samples (0.1 g) were treated under different conditions (i) vacuum at 523 K, (ii) vacuum at 773 K, (iii) He at 1073 K and (iv) H2 at 1073 K, all for 4h. Then, thqr were s ed into a Pyrex RMN tube in pure He and placed into the microcalorimetric celL A conventional manometric system coupled to the microcalorimet was used to m isare the amount adsorbed employing a (type 660) manometer witii a pr xsion of 0.001 Torr. The maximum apparent leak rate of the manometric system (including tire calorimetric cells) was 10 Torrmiri in a volume of about 60 cm. ... 

MA1 Maron, S.H. and Filisko, F.E., A modified Tian-Calvet microcalorimeter for polymer solution measurements, J. Macromol. Sci.-Phys. B, 6, 57, 1972. 

In recent years, the Tian-Calvet microcalorimeter has been developed into a commercial instrament. Working on a few milligram of sample with inaccuracy of about 1 percent is a feature of this calorimeter. 

The results of CO adsorption microcalorimetry described in this overview were collected with a differential and isothermal microcalorimeter (Tian-Calvet Microcalorimeter) linked to a static volumetric system. The equipment permits the introduction of successive small doses of CO onto the catalyst. Both the calorimetric and the volumetric data were stored and analyzed by microcomputer processing. The obtained data are presented as differential heats versus the amount of CO adsorbed... 

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