A detailed non-isothermal kinetic study of elephant grass pyrolysis from different models

Elephant grass (Pennisetum Purpureum) is a promising source of renewable energy. Thermal degradation of this biomass in an inert atmosphere was studied. Thermogravimetric analysis were carried out at different heating rates (5-50 K min(-1)) and temperatures ranged from 473 to 773 K. Two model-free (isoconversional) methods, Kissinger (KAS) and Flinn-Wall-Ozawa (FWO) were used to determine the activation energy. Both methods indicated that the activation energy was relatively constant until the conversion 0.6. A non-linear method (Vyazovkin advanced isoconversional method) was used to evaluate the activation energy behavior. From Vyazovkin advanced isoconversional method (WA), the average activation energy until conversion 0.6 was 185.28 6.87 kJ mol(-1). The activation energies obtained through WA were utilized to determine the reaction mechanism using master plots parameters (Criado method). The results showed that the main process reaction mechanism could be characterized by two successive reactions, a diffusion followed by a reaction-order model. A model-based method (three-component mechanism) was proposed considering parallel reactions in the entire pyrolysis process. Activation energy for hemicellulose, cellulose and lignin ranged from 46.5 to 65.5 kJ mol(-1), from 108.0 to 127.2 kJ mol(-1) and from 45.6 to 53.5 kJ mol(-1), respectively. (C) 2016 Elsevier Ltd. All rights reserved.