Analysis of the oxidation reactivity of carbonaceous materials using thermogravimetric analysis

The aim of this work is to develop a simplified, though rigorously based thermogravimetric anal. (TG) method to est. intrinsic reactivity parameters (activation energy, E, and pre-exponential factor, A) for the oxidn. in air of engineering carbonaceous materials. To achieve this aim, a modified Coats-Redfern method for analyzing linear curves has been devised. The new method assumes first-order reaction kinetics with respect to carbon, and uses a statistical criterion to est. an 'optimum' heating rate. For the oxidn. in air of a model carbon, an optimum rate of 27 K min-1 was detd., at which E=125.8 kJ mol-1. This is in good agreement with activation energies obtained using established, though more limited model-free or isoconversional methods. [on SciFinder (R)]