A Kinetic Study on the Pyrolysis of Hemp Stalk Using Thermogravimetric Analysis

Abstract

Agricultural wastes could be a good candidate to obtain liquid, solid and gaseous fuels transformed through thermal conversion methods such as pyrolysis in power plants. Whereas, considering the complex nature of lignocellulosic structure of biomass and existence of various set of reactions involving the formation of radicals, determining biomass pyrolysis kinetics for scaling up becomes a challenge. In this study, the pyrolysis kinetics of an agricultural bio-waste, hemp stalk, was determined by a model-free method.  Thermal decomposition experiments were conducted by a thermogravimetric analyzer from room temperature to 1000 °C under N₂ flow (100 mL/min^-1) at a linear heating rate of 10 °C/min and Coats&Redfern model is utilized to calculate the kinetic parameters during degradation. Different reaction orders are assumed in the model and best fitting is decided according to the regression coefficients. As a result, the quality of the fit was found to be remarkably good in the case of assuming the order of reaction as 0.5, 1.0 and 2.0, for temperature intervals starting from 170.8, 240.1 and 380.9 °C. Moreover, a considerable change is not observed in mass loss after approximately 550 °C indicating the expiration of the main pyrolysis reactions.