Lipase-Catalyzed Synthesis of Glycerol-Free Biodiesel from Rapeseed Oil and Dimethyl Carbonate

Abstract

The enzymatic production of glycerol-free biodiesel by the transesterification of rapeseed oil was studied using lipase as catalyst. A series of co-solvents were employed in an attempt to improve reaction kinetics. The effects of the reaction conditions (molar ratio of dimethyl carbonate (DMC) and rapeseed oil, type of lipases, amount of lipases, solvent effects, reaction temperature and time) on the conversion and yield of biodiesel and glycerol carbonate (GC) were investigated. The optimal conditions for biodiesel and GC were 20% Novozym 435, 3:1 molar ratio of DMC to rapeseed oil, and with 20% [Omim][BF6] as solvent. Under these conditions, the conversions of 88.51% biodiesel and 73.87% GC have been achieved after 48 h. The biodiesel and GC conversions were eight times higher compared to the conventional solvent-free system, respectively. There was no obvious loss in the biodiesel and GC yield after Novozym 435 having been used for five recycling.