Esterification and transesterification over SrO–ZnO/Al2O3 as a novel bifunctional catalyst for biodiesel production

Abstract

Abstract A series of novel bifunctional catalysts (SrO–ZnO/Al2O3) have been synthesised via the wet impregnation method for biodiesel production. The basic and acidic activities of the prepared catalysts were investigated using corn oil and oleic acid, respectively. Physio-chemical characteristics of the synthesised catalysts were analysed by XRD, SEM-EDS, TGA-DSC, and FT-IR. 1H NMR was used for analysing the fatty acid ethyl ester and the free fatty acid. The catalyst exhibited higher catalytic activity in transesterification reaction, with 95.1% reaction conversion at operating conditions of 10:1 ethanol to corn oil molar ratio, 10 wt% catalyst loading, and 180 min at 70 °C. However, the conversion for esterification reaction was 71.4% at operating conditions 5:1 ethanol to corn oil molar ratio, 10 wt% catalyst loading, 6 h reaction time at 70 °C reaction temperature. The kinetic studies revealed that the transesterification and esterification reactions have good agreement with the first-order model.