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 analysis (TG) method to estimate intrinsic reactivity parameters (activation energy, E, and pre-exponential factor, A) for the oxidation in air of engineering carbonaceous materials. To achieve this aim, a modified Coats-Redfern method for analysing linear curves has been devised. The new method assumes first-order reaction kinetics with respect to carbon, and uses a statistical criterion to estimate an 'optimum' heating rate. For the oxidation in air of a model carbon, an optimum rate of 27 K min(-1) was determined, 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.