KINETICS OF THE THERMAL-DECOMPOSITION OF CELLULOSE UNDER THE EXPERIMENTAL CONDITIONS OF THERMAL-ANALYSIS - THEORETICAL EXTRAPOLATIONS TO HIGH HEATING RATES

Thermobalance-mass spectrometer (TG-MS) experiments carried out by the authors in a period of 8 years are reviewed and analyzed. Celluloses and lignocellulosic biomass samples were studied. The data are evaluated by the method of least squares. The results indicate that a single rate-controlling reaction step dominates the kinetics of the cellulose decomposition at low heating rates (2-20 degrees C/min) provided that the heat and mass transport problems are experimentally eliminated and the amount of catalytic impurities is reduced by dilute acid or hot water washing treatments. The kinetic parameters obtained from the experiments with different cellulose and biomass samples evidenced only ca 8% scattering. A simple explanation is given for the kinetic compensation effect observed. Theoretical extrapolations are presented to predict the behavior of extremely small, idealized cellulose samples at high heating rates.