A new kinetic model for temperature programed thermogravimetry and its applications to the gasification of coal chars with steam and carbon dioxide

Abstract

For the kinetic analysis of non-catalytic solid-gas reaction by thermogravimetry, the rate equation f=1— exp[ — a(T—c)b], (f= fractional conversion of reactive solid, T= temperature, a,b, c = constants) was proposed to follow precisely the experimental TGA curve (f vs. T) obtained by a temperature-programed run at heating-up speed ϕ = dT/dθ (θ = reaction time). Assuming the reaction to be first-order with respect to weight of reactive solid, a method based on data-fitting process was derived to determine the rate constant kϕand kinetic parameters (activation energy E and preexponential factor A) of the Arrhenius-type rate constant, from only a single temperature-programed run. The proposed method was applied to experimental data on the gasification of coal chars with steam and carbon dioxide at temperatures up to 1000°C, and was confirmed to be valid and useful for the quantitative evaluation of kinetic parameters and the comparison of gasification reactivity of coal char. © 1985, The Society of Chemical Engineers, Japan. All rights reserved.