Thermokinetic analysis of coconut husk conversion by pyrolysis process

Abstract

The energy produced from agricultural wastes by pyrolysis can replace fossil fuels in many applications. Therefore, to make the process more efficient and optimal, an understanding of the kinetic and thermodynamic behaviour is required before progressing to pyrolytic applications. Thus, this study investigates the pyrolysis thermokinetic of coconut husk under varied heating conditions in nitrogen environment. Three model-free approaches, which are; Kissinger-Akahira-Sunose (KAS), Distributed Activation Energy Model (DAEM), Ozawa-Flynn-Wall (FWO) were deployed to analyse the kinetic parameters. The temperature range for the maximum devolatilization was found to be between 200 and 380 °C. Average activation energy was obtained based on various model free approaches with KAS, DEAM and FWO having a value of 99.15 kJmol−1, 99.15 kJmol−1 and 103 kJmol−1 respectively. The comparison between activation energy, Ea and change in enthalpy ΔH showed that average energy barrier is low with a value of 4.85 kJmol−1 for all methods. Further, maximum values of thermodynamic parameters, such as change in enthalpy, and Gibbs free energy were estimated at 98.49 kJmol−1, 158.50 kJmol−1 respectively. Overall, kinetic, and thermodynamic analysis shows that coconut husk has potential for bioenergy production through pyrolysis.