Transesterification of Vegetables oil using Sub-and Supercritical Methanol

Abstract

A benign process, non catalytic transesterification in sub and supercritical methanol method was used to prepare biodiesel from vegetables oil. The experiment was carried out in batch type reactor (8.8 ml capacity, stainless steel, AKICO, JAPAN) by changing the reaction condition such as reaction temperature (from 210°C in subcritical condition to 290°C in supercritical state in ranges of 20°C), molar ratio oil to methanol (1:12-1:42) and time of reaction (10-90 min). The fatty acid methyl esters (FAMEs) content was analyzed by gas chromatography-flame ionization detector (GC-FID). Such analysis can be used to determine the biodiesel yield of the transesterification. The results showed that the yield of biodiesel increases gradually with the increasing of reaction time at subcritical state (210-230oC). However, it was drastically increased at the supercritical state (270-290oC). Similarly with the influence of molar ratio oil-methanol, yield biodiesel sharply increased with increasing ratio molar of oil-methanol up to 1:24. The maximum yield 86 and 88% were achieved for soybean oil and palm oil, respectively, at 290oC, 90 min of reaction time and molar ratio of oil to methanol 1:24.