Statistical Optimization of Esterification Reaction to Produce Biodiesel from the Mixture of PFAD and Palm Stearin Oil Using Two-Step Reaction

Abstract

In this study, the optimization of esterification from the mixture of palm fatty acid distillate (PFAD) and palm stearin (PS) oil followed by transesterification reaction has been investigated. The free fatty acid (FFA) content of raw oil mixture was ca. 50%. Response surface methodology (RSM) and 3-level-3-factor Box-Behnken design were employed to predict the conversion of FFA as a function of reaction temperature, wt.% of catalyst (based on FFA in the mixture) and molar ratio of methanol to FFA. Experiments were performed under varied conditions with three fixed parameters; 3:1 molar ratio of methanol to triglycerides in oil mixture, 60 °C reaction temperature and 500 rpm stirring rate. From the statistical investigation, it was found that the molar ratio of methanol to FFA was the most important factor on reducing FFA content in esterification step.