The kinetics of the thermal degradation of calcium carbonate

Abstract

The decomposition of calcium carbonate fine powder in a flowing nitrogen atmosphere has been investigated by non-isothermal thermogravimetry at heating rates in the range, 10–50 deg min−1. The analog percentage weight change record was digitized at 1 deg intervals. The resulting data, transformed into dimensionless extents of reaction and calculated rates of reaction, was then subjected to the Arrhenius, Friedman and Generalized Kissinger analyses, using a recently developed FORTRAN program system. The value ofn namely 0.39 ±0.04, resulting when the data is analyzed assuming an nth order reaction, strongly indicates that the most probable rate controlling step is a three-dimensional diffusion process (D4 mechanism), withE=172.4 kJ·mol−1 andA=1.97·104 K−1·min−1. Reasons for the wide disparity in previously reported kinetic data are discussed.