Homogeneous and heterogeneous catalytic production of biodiesel from palm kernel oil and coconut oil

Abstract

Nowadays, fatty acid methyl ester or biodiesel, prepared from transesterification of vegetable oil is believed to be a viable alternative for diesel fuel. Homogeneous basic catalysts such as NaOH and KOH are commonly used to obtain high methyl esters conversion from several vegetable oils such as refined palm, rapeseed and soybean oil. Despite the ample supply of palm kernel oil (PKO) and coconut oil (CCO) in Asia, there has been limited research on the use of these resources. This research is focused on the transesterification of crude PKO and CCO with NaOH as catalyst. Results showed that the crude PKO and CCO could be used as a material having a methyl ester content of 95-99% and a product yield of 75%. It was found that the optimum condition for the transesterification of crude PKO and CCO was 0.5-1% NaOH as catalyst at catalyst at methanol: oil mole ratio 6:1 and 60-65 ℃. However, a more complex process for the removal of the side product and dissolved catalyst would be required when using a homogeneous catalyst. Preliminary screening of solid catalysts for heterogeneous transesterification was also carried out. Among ten solids tested, results suggest that ZnO and superacid sulfated stannous oxide (SO₄.SnO₂) are promising heterogeneous catalysts for the production of biodiesel.