Abstract: The pyrolysis characteristics of walnut shell at different heating rates (5-50K/min) under the stream of N₂ were studied using thermogravimetric analysis. The result showed that the pyrolysis process of walnut shell included four stages, namely drying, pre-pyrolysis, fast-pyrolysis and slow decomposition of residue. The weight loss during the fast-pyrolysis stage and the slow decomposition stage of residue was about 55% and 32%, respectively. The pyrolysis process could be described by the first-order global model for both fast-pyrolysis and slow decomposition stages. With the method of Coats-Redfern, the average activation energy was 50.7 and 17.3kJ/mol for both pyrolysis stages, respectively. The pyrolysis speed increases with increasing of heating rate.

Key words: walnut shell, pyrolysis, thermogravimetric analysis, kinetics