Kinetics of the isothermal degradation of wood in the temperature range 528-708 K

Two sets of thermogravimetric curves of isothermal degradation of beech wood have been measured for temperatures between 528-584 and 573-708 K, respectively. The reduced sample size (layers 150 m thick) and the moderate temperatures establish a kinetically controlled process. The curves are well described by a global degradation mechanism consisting of three sequential steps. The kinetic constants estimated for the first-order reaction rates are: (I) ln A1=10.24.5 s-1 and E1=76.2 kJ21.1 mol-1; (II) ln A2= 22.52 s-1 and E2=142.810 kJ mol-1; and (III) ln A3=2.31 s-1 and E3=43.8 5.7 kJ mol-1. Good agreement is obtained with previous dynamic (I and II step) and isothermal (II step) analyses.