A non-conventional sustainable process route via methyl acetate esterification for glycerol-free biodiesel production from palm oil industry wastes

Abstract

In the present study, a sustainable and environmentally safe process was utilized for production of biodiesel free of glycerol via methyl acetate esterification by employing the beneficial usage of palm oil industrial waste products. A non-conventional novel approach was then investigated for the esterification process using methyl acetate as the esterifying agent in the presence of solid acid catalyst prepared via impregnation on spent bleaching earth as catalyst support. The new solid acid catalyst was synthesized by calcination and sulfonation of the spent bleaching earth. The catalyst was characterized via Hammett Indicator, X-ray Fluorescence, Thermogravimetric Analysis, X-ray Diffraction, Nitrogen adsorption-desorption analysis, and Ammonia-temperature programmed desorption techniques. Optimization study was carried out for reaction parameters such as reaction temperature (60–110 °C), catalyst amount (2–14 %), PFAD/MA molar ratio (1:3–1:18) and reaction time (1–6 h). The maximum free fatty acid conversion of 89.89 % was obtained at optimized reaction conditions: catalyst amount 12 w/w%, reaction time 3 h, reaction temperature 100 °C and PFAD/MA molar ratio 1:12. A plausible mechanism for the esterification of palm fatty acid distillate using methyl acetate in the presence of the synthesized acid catalyst has also been proposed. This study also ascertained the effectiveness of methyl acetate as a suitable alternative esterifying agent for esterification of palm fatty acid distillate.