TGA-DSC-MS Analysis of Pyrolysis Process of Various Biomasses with Isoconversional (Model-Free) Kinetics

Abstract

Slow pyrolysis characteristics of different biomasses (hazelnut shell (HS), sawdust (Beech), and sawdust chemically treated (SDCT)) were investigated by simultaneous thermal analysis (STA), coupled with mass spectrometry (MS). Thermal decomposition of these samples was divided into three stages corresponding to removal of water, devolatilization, and formation of bio-char. It was found that differences in thermal behavior of the samples are due to differences in their composition. Mass spectrometry results showed that H-2, CH4, H2O, CO2 (C3H8), CO, and C2H6 were the main gaseous products released during pyrolysis. It was shown that HS could be a good fuel, since during its pyrolysis at high temperature, more gaseous products are released compared to other systems. Isoconversional (model-free) method was used in order to determine variation magnitudes of effective activation energy (E-a) values on conversion fraction (alpha) during pyrolysis. It was found that identified variations of E-a with alpha arise from the different chemical structures among cellulose, hemicelluloses and lignin in tested samples that may affect on their effective activation energies.