Evaluating the commercial potential of Cocos nucifera derived biochar catalyst in biodiesel synthesis from Kanuga oil: Optimization, kinetics, thermodynamics, and process cost analysis

Abstract

In the current study, sulfonic acid functionalized steam-activated char catalyst was prepared from Cocos nucifera (coconut) husk (named as ACH-SO3H) at low temperatures for the pre-treatment of Kanuga oil to its methyl ester. This catalyst is attempted reportedly first time for Kanuga oil-derived biodiesel production. An ester yield of 99.51% was achieved over parametric states optimized by response surface methodology of catalyst loading 4.9 wt%, methanol concentration of wt%, for 83 min at 55.75 °C. Based on the proximate analysis, the feedstock Kanuga oil exhibited a high free fatty acid suggesting that the fuel production require the usage of an acid catalyst. Catalyst developed was examined using BET, SEM, EDAX, FTIR, and XRD. Fuel characterization of the produced methyl ester demonstrated that it has physico-chemical properties acceptable for biodiesel according to ASTM standards. The esterification reaction with ACH-SO3H exhibited kinetics that resembled pseudo-first-order behaviour, with an Ea of 68.83 kJ mol−1. Endothermic nature and non-spontaneity of the esterification reaction were confirmed through the thermodynamic study. Despite repeated use, the catalyst demonstrated outstanding stability, with the capacity to be reused thrice without notable decay in catalytic action. Catalyst production cost of $6.74/kg was estimated in the work.