Kinetic Study of Pine Wood Pyrolysis Using Thermogravimetric Analysis

The pyrolysis characteristics and kinetics of pine wood were studied using thermogravimetric analysis. The results obtained from thermal degradation indicated that pyrolysis involved three stages: moisture loss (<200 degrees C), devolatilization (200-400 degrees C), and charring (>400 degrees C). With an increase in the heating rate, the main pyrolysis process shifted to a higher temperature range, the maximum weight loss rate decreased, and endothermic and exothermic effects were heightened. The results of kinetic analysis by the Popescu method indicated that the most probable pyrolysis mechanism during devolatilization is three-dimensional diffusion, which can be represented by the Zhuralev, Lesokin and Tempelmen equation (G(alpha) = {[1/(1-alpha)1/3-1}2) (250-350 degrees C) and Jander equation (G(alpha) = (1-alpha)(1/3)](2)) (350-380 degrees C). The average apparent activation energy value (168.6 kJ/mol) determined by the Popescu method is similar to that (167.4 kJ/mol) calculated by the Flynn-Wall-Ozawa (FWO) method. This means that the pyrolysis mechanism determined using Popescu method is credible. Moreover, the activation energy changed depending on the conversion rate.