Kinetics of Primary Product Formation from Wood Pyrolysis

Abstract

Weight loss curves of thin layers (150 μm) of beech wood powder, measured for heating rates of 1000 K/min and final temperatures in the range 573−708 K, show final char yields of 37−11%. The process is kinetically controlled and, for the most part, isothermal. A one-step global reaction, with E = 141.2 ± 15.8 kJ/mol and ln A = 22.2 ± 2.9 s-1, is a degradation mechanism capable of capturing the main features of the process. The thermogravimetric curves also allow the formation rate constants to be estimated for char and total volatiles (activation energies of 111.7 ± 14.3 and 148.6 ± 17.4 kJ/mol, respectively) and, once integrated byproduct distribution, those for liquids and gases (activation energies of 148 ± 17.2 and 152.7 ± 18.2 kJ/mol, respectively). A comparison is provided with pyrolysis mechanisms available in the literature.