Enhanced enzymatic transesterification of palm oil to biodiesel

Inefficient reaction is one of the drawbacks for the enzymatic production of biodiesel (BD). A method for enhanced Novozym 435-catalyzed transesterification of palm oil (PO) to BD using a mixture of methanol and methyl acetate (MA) as acyl acceptors has been developed. BD yield using methanol–MA mixture reached 95–96% after 8 h at a methanol to PO molar ratio of 1:1, a MA to palm oil molar ratio of 12:1, 2 g of PO, temperature of 50 °C and Novozym 435 loading of 0.6 g. In contrast with methanol–MA mixture, BD yield using MA alone after 24 h was 88–89% under the same reaction conditions. Novozym 435 was repeatedly used at 40 and 50 °C for 10 cycles. There was no considerable loss in the enzyme activity at 40 °C using either methanol–MA mixture or MA alone, while the remaining activity of the enzyme at 50 °C in both cases after 10 cycles was 82–85%. The developed method has a potential to be used for efficient enzymatic production of BD.

► Comparison of methanol with methyl acetate (MA) as acyl acceptor for Novozym 435-catalyzed transesterification of palm oil to biodiesel. ► Methanol is more reactive than MA but deactivates Novozym 435. ► The presence of MA minimizes methanol deactivation of Novozym 435. ► Combined use of methanol and MA enhances the reaction 3-fold and reduces the enzyme load.