Biocatalytic transesterification of rapeseed oil by methyl formate

Abstract

Due to the awareness of adverse effects of conventional fuels on environment and on a frequent rise in the crude oil price, the need for a sustainable and environment-friendly alternate source of energy has gained importance. Recently, options have been analysed to replace the triglyceride transesterification process, which is generally used in biodiesel production, by the process where raw glycerol is not generated, whereas triacylglycerides obtained instead glycerol can be directly used as fuel for a diesel engine in a mixture with fatty acid esters. In the present work, interesterification of rapeseed oil to biodiesel was carried out with methyl formate and using lipase as a catalyst. The research was carried out at the Laboratory of Chemical and Biochemical Research for Environmental Technology of Aleksandras Stulginskis University. First, the most effective biocatalyst suitable for the process was selected. 14 different lipases were studied. The samples obtained after the synthesis were analysed by the thin-layer and gas chromatography. Process experiments were performed using a methyl formate to oil molar ratio of 6:1 to 40:1, a lipase amount of 5 to 17% (mass of oil) and synthesis duration of 3 to 48 h. The highest yield of fatty acid methyl esters (FAME) was obtained using Lipozyme RM IM as a catalyst and its optimal amount was 13%. The optimal temperature was found to be 20°C and the duration of interesterification 42 h. The optimal molar ratio of methyl formate to oil was determined to be 32:1. Under the obtained conditions the transesterification degree was 60.68 ± 0.95%.