Title
Kinetic study of pine sawdust pyrolysis via TG/DTG analysis
Authors
XIAOLI GU XULIANG ZHOU MIAOHUA WU XINYI WANG YUDI CHEN and KANGHUA CHENG

Received May 7, 2015
Published Volume 51 Issue 5-6 May-June
Keywords pine sawdust, pyrolysis, reaction kinetics, TG/DTG

Abstract
The pyrolysis of pine sawdust was investigated by thermogravimetric techniques (TG/DTG) in the temperature range from room temperature (20 °C) to 1000 °C under dynamic heating conditions (10, 20, 40 and 80 K min-1 heating rates). Little differences in the weight loss as a function of heating rates were observed. Total weight losses of 83%, 78%, 79% and 83% at heating rates of 10 K/min, 20 K/min, 40 K/min and 80 K/min were observed, respectively. From the thermogravimetric analysis, it was established that the thermal decomposition pine sawdust consisted of three main stages: water evaporation (<200 °C), devolatilization of organic volatiles (200~500 °C) and char formation (>500 °C). The kinetic processing of non-isothermal TG data was performed by model-free methods, such as the Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sonuse (KAS) methods. The average activation energy calculated by the FWO and KAS methods was 96.38 and 91.72 kJ mol-1, respectively. Experimental results showed that the values of kinetic parameters obtained by both methods were in good agreement and could be successfully applied to understand the complex degradation mechanism of the solid-state reaction. With a further increase of the conversion degree, a complicated relation between activation energy (Ea) and conversion (α) was evident, as the thermal degradation process of pine sawdust underwent a multi-step reaction. The findings of this study contribute to better understanding of the devolatilization process of different types of biomass.