Comparison of the pyrolysis and kinetics of three components of biomass

The pyrolysis characteristics of three main components of biomass, namely cellulose, xylan hemicellulose and lignin have been investigated by means of thermogravimetric analysis. Models of their pyrolysis kinetics were derived using the Coats-Redfern integral method. The results show that differences in the pyrolysis of the three components result mainly from differences in their molecular structures. The observed mass losses of cellulose, xylan hemicellulose and lignin were approximately 86%, 69%, and 51% respectively within the experimental temperature range (room temperature to 900°C), indicating that the extent of decomposition varies in the order cellulose > xylan hemicellulose > lignin. In each case two distinct temperature regions were observed. The pyrolysis of both lignin and xylan can be described by second-order kinetics equations in both temperature regions. The best description of the pyrolysis of cellulose, however, involves a first-order reaction in the low temperature region and a second-order reaction in the high temperature region.