Kinetic analysis of non-isothermal thermogravimetric analyser results using a new method for the evaluation of the temperature integral and multi-heating rates

A technique using non-isothermal thermogravimetric analyser results was developed for the validation of reaction rate models together with associated parameters suitable for chemically controlled gas-solid reactions. The solution of the temperature integral which occurs in the calculation is achieved by numerical integration with respect to a dimensionless activation energy variable, y=E/RT, following a transformation of the temperature integral equation. The evaluation of the validity of the kinetic model and determination of all the constants is accomplished with a two-step regression procedure with experimental results from several thermogrammes with different linear heating rates. The technique was validated by comparing results obtained for the combustion of two coal-chars with corresponding isothermal results using a shrinking core model with a nth order surface reaction. (c) 2005 Elsevier Ltd. All rights reserved.