Biodiesel from Vegetable Oils with MgO Catalytic Transesterification in Supercritical Methanol

Abstract

In this experimental work, transesterification reactions with magnesium oxide (MgO) in supercritical methanol of vegetable oil samples (rapeseed oil, soybean oil, and sunflower oil) have been studied to obtain biodiesel. MgO as a catalyst can considerably improve the transesterification reaction of sunflower seed oil in supercritical methanol. The variables affecting the methyl ester yield during the transesterification reaction, such as the catalyst content, reaction temperature, and the molar ratio of vegetable oil to alcohol, were investigated and compared with those of non-catalyst runs. The catalytic transesterification ability of MgO is quite weak under ambient temperature. When MgO was added from 1.0% to 3.0%, the transesterification speed increased, while the catalyst content was further enhanced to 5% and the yield of methyl ester slowly plateaued. It was observed that increasing the reaction temperature had a favorable influence on methyl ester yield. In addition, for molar ratios ranging from 1–41, the higher the molar ratios of methanol to oil were charged, the more quickly transesterification speed was obtained.

Keywords:

• biodiesel
• catalytic transesterification
• MgO
• supercritical methanol