Bioenergy potential analysis of Brazil nut biomass residues through pyrolysis: Gas emission, kinetics, and thermodynamic parameters

Abstract

The kinetics of the pyrolysis of Brazil nut residues (Bertholletia excelsa), in this case, shells (BNS) and husks (BNH), were investigated via a thermogravimetric analysis in an inert atmosphere. The Flynn–Wall–Ozawa, Kissinger-Akahira-Sunose, Starink and Vyazovkin isoconversional models were used to estimate kinetic and thermodynamic parameters. The mean activation energy values ranged from 135.59 to 138.51 kJ/mol for the shells and from 151.94 to 153.92 kJ/mol for the husks in the active pyrolysis region. High values of the pre-exponential factor (>108 s−1) indicated the presence of complex reactions for both samples, which was confirmed in the analysis of the reaction mechanism using the master-plot method, through the multiple types of behavior during the variation of the conversion levels. Thermodynamic parameters, such as the enthalpy change, Gibbs free energy change and entropy change, characterized a nonspontaneous endothermic process, with little energy required. TG-MS analyses revealed less harmful gas emission behavior for the environment compared to fossil fuels. The results of the study, with an emphasis on its satisfactory higher heating value (13.8 and 14.6 MJ/kg), showed that Brazil nut residues, an Amazon Forest waste, have great potential in pyrolysis applications for the generation of renewable energy, which can contribute to forest preservation through the development of the circular bioeconomy.

Keywords

• Brazil nut
• Biomass pyrolysis
• Kinetic analysis
• Isoconversional models