Non-isothermal pyrolysis of Polyalthia longifolia using thermogravimetric analyzer: Kinetics and thermodynamics

Non-isothermal thermogravimetric experiments were carried out at four different heating rates to investigate thermal decomposition of Polyalthia longifolia leaves, with primary goals of determining kinetic triplets (activation energy, frequency factor, and reaction mechanism) and thermodynamic parameters. Kinetics investigation was conducted by utilizing five iso-conversional approaches, viz., Starink (STK), Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS), differential Friedman method (DFM), and distributed activation energy model (DAEM). Results indicated that average activation energy (E-alpha) ranged between 211.57 and 231 kJ/mol. Average values of activation energy obtained by KAS (211.57 kJ/mol) were found to be in the neighborhood of that obtained by other three integral methods, i.e., OFW (210.80 kJ/mol), STK (211.80 kJ/mol), and DAEM (211.57 kJ/mol). Criado's master plots approach revealed that experimental data matches with none of the reaction model until conversion of 0.4 and thereafter follows D3 for conversion of 0.5-0.7, whereas master plots based on the integral form of data disclosed that this method is not appropriate for pyrolysis of the present biomass sample. Finally, pyrolysis of P. longifolia biomass to produce bioenergy is found to be feasible (E-alpha - Delta H = similar to 5-6 kJ/mol).