Resumen
Transesterification of waste vegetable oil is one of the promising partial substitutes for fossil fuels. The degradation characteristics of waste vegetable oil using supercritical alcohols (ethanol and methanol) have been studied in this research. The elementary target was to conduct comparative analysis of the effect of supercritical methanol and supercritical ethanol as solvents on the transesterification along with the analysis of product obtained in terms of carbon number. The experiments were carried out at transesterification temperatures of 250, 270 and 290 °C, retention time of 0 to 60 min at an interval of 15 min and oil to alcohol molar ratios of 1:6, 1:12 and 1:18 for both alcohols. The conversion increased with increase in transesterification temperature and retention time. At 290 °C, almost 99% conversion was achieved for 60-min holding time for both alcohols. Increase in conversion of waste vegetable oil was observed as the molar ratio increased. Supercritical transesterification resulted into ester yield higher than 95% with non-ester composition and glycerol collectively less than 5%.