Thermogravimetric analysis and Kinetic study of poplar wood pyrolysis

A kinetic study of the pyrolysis process of poplar wood (populus L.) was investigated using a thermogravimetric analyzer. The weight loss was measured in nitrogen atmosphere. The samples were heated over a range of temperature from 298 K to 973 K with four different heating rates of 2, 5, 10, 15 K min-1. The results obtained from thermal decomposition process indicate that there are three main stages such as dehydration, active and passive pyrolysis. In the DTG thermograms the temperature peaks at maximum weight loss rate changed with increasing heating rate. The kinetic parameters such as activation energy and pre-exponential factor were obtained by model free methods proposed by FWO, KAS and Kissinger. The activation energy and pre-exponential factor obtained by Kissinger method are 153.92 kJ/mol and 2.14 x 1012 min-1, while, the same average parameters calculated from FWO and KAS methods are 158.58 and 157.27 kJ mol-1 and 7.96 x 1013 and 1.69 x 1013min-1, respectively. The results obtained from the first method represented actual values of kinetic parameters which are the same for the whole pyrolysis process, while the second method presented apparent values of kinetic parameters, because they are the sum of the parameters of the physical processes and chemical reaction that occur simultaneously during pyrolysis. Experimental results showed that values of kinetic parameters from both method are in good agreement and can be successfully used to understand the degradation mechanism of solid-state reaction. It is planned on using the results from TGA in computer softwares for simulating pyrolysis to achieve a better understanding of the devolatilization process of different type of biomass.