Biodiesel Synthesis through Methanolysis of Palm Olein Using Calcium Oxide Catalyst Derived from Staghorn Coral

Abstract

This study explored the synthesis of a heterogeneous catalyst derived from staghorn coral where it was utilised to convert palm olein into methyl esters through transesterification process. The prepared catalyst was characterised by various methods, namely Hammett indicator method, benzoic acid titration method, X-ray fluorescence (XRF) spectroscopy, Brunauer-Emmett-Teller (BET)-N2 adsorption analysis, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, thermal gravimetric analysis (TGA), X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Based on the results acquired from ATR-FTIR and XRD analyses, it was evident that staghorn coral was converted into calcium oxide (CaO) upon thermal activation at 900°C. The impacts of catalyst loading, reaction time and methanol/oil molar ratio on biodiesel content were investigated to determine the optimum reaction conditions. The methyl esters content of 62.07% was achieved under optimised parameters comprising 6 wt% catalyst loading, reaction time of 4 h and methanol to oil molar ratio of 15:1. All in all, despite the low percentage of biodiesel production, staghorn coral has shown to be a potent catalyst and its catalytic ability could be improved to a whole new level through further modifications.