Heterogeneous esterification of free fatty acid to biodiesel

Abstract

The potential of sulphated zirconia (SZ) as heterogeneous acid catalyst for esterification of free fatty acid (FFA) to biodiesel has been investigated. Experiments using oleic acid as a model compound preceded the esterification of palm oil free fatty acid (POFFA) mixtures. The relation of reaction time, SZ loading and methanol to oil molar ratio on biodiesel yield and conversion was investigated. Optimisation of esterification process via response surface methodology (RSM) for blended POFFA revealed maximum biodiesel yield (FAME) and conversion were 80.2% and 78.4%, respectively. The optimum conditions were operating reaction time = 87min, catalyst loading = 0.98wt% and molar ratio methanol to oil = 11.6:1. The fuel properties of biodiesel from POFFA and oleic acid blends were found to conform to the ASTM standard.