Investigation of Thermal Degradation Properties and Chemical Kinetic Characteristics of Biomass Pyrolysis via TG/DTG and FTIR Techniques: Sesame Stalks as Potential Source of Bioenergy in Ethiopia

Abstract

The dependence on fossil fuels and the overexploitation of it is a bottlenecked problem of the globe leading to finding alternative renewable resources that may be used as an energy source in place of fossil fuels. Thermogravimetric analysis (TGA) is a technique used to identify potential renewable energy sources. This study investigated the kinetic, thermodynamic parameters, and pyrolysis characteristics of sesame stalk (SS) biomass pyrolysis using thermogravimetric (%) (TG)‐derivative thermogravimetry (DTG) techniques. The pyrolysis was carried out at different heating rates (15, 20, and 25°C/min). The chemical kinetics parameters were determined using isoconversional model‐free methods, including Kissinger–Akahira–Sunose (KAS), the Ozawa–Flynn–Wall (OFW), and model fitting techniques like the Coats–Redfern (CR) model. The thermodynamic parameters (∆ H , ∆ G , and ∆ S ) were calculated using kinetic data. The average activation energy for SS biomass was found to be 77.96 and 84.15 kJ/mole for the KAS and OFW methods, respectively. The activation energy ( E ) for SS biomass from the integral method varied between 29.61–142.58 kJ/mole for reaction order models and 4.90–122.33 kJ/mole for diffusion models. The distributions of pre‐exponential factor ( A ) for the reaction order models are virtually normal in the range of 0.2–0.7, upon the Eα values obtained using the OFW and KAS approach. The average value of enthalpy, Gibbs free energy, and entropy of SS were also reported. The study suggests that SSs are a potential biomass for sustainable bioenergy production, and kinetic and thermodynamic data are crucial for reactor design for the pyrolysis of SSs.