Comparative studies on the pyrolysis of cellulose, hemicellulose, and lignin based on combined kinetics

Abstract

The thermal degradation behavior and pyrolytic mechanism of cellulose, hemicellulose, and lignin are investigated at different heating rates from 10 Kmin-1to 100 Kmin-1with a step-size of 10 Kmin-1using thermogravimetric analysis (TGA) equipment. It is observed that there are one, two, and three stages of pyrolytic reactions takes place in cellulose, hemicellulose, and lignin respectively. Isoconversional method is not suitable to analyse pyrolysis of hemicellulose and lignin as it involves multi-step reactions. The activation energies of the main decomposition stage for cellulose, hemicellulose, and lignin are 199.66, 95.39, and 174.40 kJ mol-1respectively. It is deduced that the pyrolysis reaction of cellulose corresponds to random scission mechanism while the pyrolysis reaction of hemicellulose and lignin follows the order based reaction mechanisms.