Pyrolysis kinetics of biomass wastes using isoconversional methods and the distributed activation energy model

Abstract

In this work, a thermogravimetric analyser was used to assess the pyrolysis kinetics of pineapple, orange and mango peel wastes and agro-industrial by-products, rice husk and pine wood. Five isoconversional methods (KAS, FWO, Starink, Vyazovkin and Friedman) and one model-fitting method (DAEM) accurately fitted the experimental data at three heating rates (5, 10 and 20 °C/min) between 10% and 90% conversion. These methods agree with the trends shown by the activation energy (E_a) distribution calculated, with fluctuations between 150 and 550 kJ/mol. The fluctuations of E_a in the whole range of conversion, in addition to a higher number of relevant reactions obtained by DAEM for fruit peel samples compared to agro-industrial samples, are associated with a higher extractive content in the peels. Kinetic parameters fitted by DAEM were successfully verified at the highest heating rate studied.

Keywords: Biomass; Isoconversional methods; Kinetic models; Pyrolysis; Thermogravimetric analysis.