RSM Process Optimization of Biodiesel Production from Waste Cooking Palm Oil in the Presence of SO3H-PSC Catalysts

Abstract

This research studied the synthesis of green and novel catalysts from waste materials for biodiesel production. An activated carbon (AC) material from palm seed cake (PSC) was soaked with zine chloride (ZnCl2) and treated with sulfonic acid (SO3H). The use of a sulfonated palm seed cake (SO3H-PSC)-derived catalyst for the transesterification/esterification of triglyceride (TG) in waste cooking palm oil (WCPO) was demonstrated. The synthesized SO3H-PSC catalyst was characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and the Brunauer–Emmet–Teller (BET) method. To study the effects of methanol/oil mole ratio, amount of catalyst, and reaction time, the process of biodiesel production in a microwave reactor was optimized using a Box-Behnken design (BBD) approach with response surface methodology (RSM). As a result, the optimum reaction parameters found were 5.40 wt.% of the SO3H-PSC catalyst, 17.35:1 methanol/WCPO mole ratio, and 8.57 min of reaction time. The synthesized biodiesel from WCPO meets the criteria for standard biodiesel (ASTM D-6751 and EN 14214). The heterogeneous catalyst demonstrates a promising and effective application for the biodiesel process, especially for feedstocks containing high free fatty acid (FFA) content.