On the suitability of controlled transformation rate thermal analysis (CRTA) for kinetic studies. Part 2. Comparison with conventional TG for the thermolysis of dolomite with different particle sizes

Abstract

The thermal decomposition of dolomite is studied, both conventionally (isothermal or constant heating rate experiments) and by controlled transformation rate thermal analysis (CRTA) using the “rate-jump” method. A comparative study was carried out in order to determine carefully the effects of particle size on the activation energy of the reaction. The reliability of the kinetic results seems to be much higher with the “rate-jump” method whose results are practically independent of grain size. This is because CRTA allows both a close control of the pressure in the sample surroundings and the use of reaction rates low enough to keep temperature gradients and, therefore, heat or mass transfer problems at a negligible level. It is shown that the activation energy of the thermal decomposition of dolomite obtained from the CRTA method is largely independent of particle size, always remaining in the neighbourhood of 200 kJ mol −1.