Comparative pyrolysis, combustion, and kinetic modeling of twelve Cameroonian woody biomass

Abstract

Pyrolysis and combustion processes of twelve Cameroonian woody biomass were performed in a thermobalance to determine their thermal degradation profiles and the associated kinetic parameters. Classical characterizations were first performed on the twelve woody samples. For the thermogravimetric analyses, the samples were heated from ambient temperature to 900 °C at four low temperature rates (5, 10, 15, and 20 °C/min) and under nonoxidative (pure nitrogen) or oxidative (synthetic air) atmospheres. The optimal values of the kinetic parameters of the twelve samples were determined considering the temperature rate of 5 °C/min and using the extended independent parallel reaction (EIPR) model with three constituents, plus the char under an oxidative atmosphere. The first-order reaction function was considered in the pyrolysis case for the three constituents and for the degradation under air of the hemicellulose and lignin constituents, whatever the sample. The second-order or fourth-order Avrami–Erofeev reaction functions were introduced for the degradation under air of the cellulose constituent or of the char. The optimal values of the kinetic parameters determined in these conditions were compared and led to quite good simulations of the mass and mass rate curves. ANOVA computations performed on the characterizations and on the optimal values of the kinetic parameters for pyrolysis or combustion of the twelve samples indicated that the mean values of these parameters did not present differences with a significance threshold equal to 0.05.