Kinetic Modeling of Rice Husk Components Pyrolysis Based on Independent Parallel Reactions

Abstract

This study presents the pyrolysis decomposition mechanism of rice husk in nitrogen atmosphere by thermogravimetric analysis (TGA). The thermal decomposition was carried out in three stages: moisture removal (180-200℃), main devolitization (200-400℃) and continuous slight devolitization (400℃). The weight loss of the rice husk was modeled based on the assumption that lignocellulose component (cellulose, hemicellulose, and lignin) undergo pyrolysis independently in parallel first-order reaction. The kinetic parameters of the three lignocellulose components were determined by means of Microsoft Excel Solver tool using least square algorithm. The result of the thermal degradation of rice husk samples shows that the model predictions of the cellulose, hemicellulose and lignin components agreed with the experiments. The activation energy and pre-exponential factors of cellulose, hemicellulose and lignin are 187kJ/mol and 1.2〖*10〗^15 〖min〗^(-1), 29Kj/mol and 1.6〖*10〗^7 〖min〗^(-1) and 90kJ/mol and 1.8〖*10〗^1 〖min〗^(-1) respectively. The results suggest that thermal decomposition rate of cellulose was found to be higher, whereas that of lignin decomposition rate was lower. The thermal decomposition of hemicellulose decomposition was intermediate.