Normalization of the power-law rate equation for determining the kinetic parameters of the char-CO2 reaction

Abstract

The power-law (or nth-order) rate equation is the most commonly used model to describe the kinetics of the char−CO2 reaction, which consists of three major kinetic parameters: the activation energy (E), the pre-exponential factor (A0), and the reaction order (n). So far, the temperature dependence of the reaction order and its influence on determining kinetic parameters have not attracted enough attention. This paper specially addresses the impact of the CO2 partial pressure on the reaction kinetics. CO2 gasification of the lignite char and coffee grounds char is conducted via thermogravimetry analysis (TGA) at 1098–1173 K and 0.025–0.05 MPa CO2 partial pressure. An exploration is made to normalize the power-law rate equation for kinetic computation, and pressure-independent E and A0 are obtained. Findings and insights obtained in this study can offer reliable evaluation of kinetic parameters and comparability of different kinetic studies.