Synthesis and component confirmation of biodiesel from palm oil and dimethyl carbonate catalyzed by immobilized-lipase in solvent-free system

The transesterification of palm oil and dimethyl carbonate (DMC) for preparing biodiesel has been carried out at the catalysis of immobilized-lipase in solvent-free system. The components were all confirmed by GC and GC–MS analysis. The fatty acid methyl esters (FAMEs) were analyzed with internal standard method. The fatty acids glycerol carbonate esters (FAGCs) were characterized as the intermediates. And, glycerol dicarbonate (GDC) was confirmed as the byproduct by comparing with the model compound. Moreover, the effects of the reaction conditions (type of lipases, molar ratio of DMC and palm oil, amount of catalyst, reaction temperature and time) on the yield of FAMEs were investigated. The yield of FAMEs could reach 90.5% at 55 °C for 24 h with the molar ratio of DMC to oil 10:1 and the catalyst amount of 20% Novozym 435 (based on the oil weight). There was no obvious loss in the FAMEs yield after Novozym 435 having been used for eight cycles.