Production of biodiesel by transesterification of refined soybean oil

Abstract

This study focused on the production of biodiesel via transesterification of refined soybean oil obtained locally. Sodium hydroxide was used as the alkali catalyst and methanol (as alcohol) was used in the transesterification process due to its low cost. The methanol-to-oil molar ratio was maintained at 6:1. The effect of reaction temperature with time and the catalyst loading were studied. The reaction temperature and the catalyst loading were varied at 30, 40, 50, 60 and 70 oC; and at 0.5 and 1.0% weight of oil, respectively. After transesterification of the soybean oil, the fatty acid methyl esters [FAMEs (biodiesel)] conversion was found to rise with an increase in the catalyst loading and also with the reaction temperature but no significant difference (P > 0.05) was found between the temperatures of 60 oC and 70 oC. The optimum methyl esters conversion of 97.89% was achieved at 60 oC for 3 h with 1% (w/w) catalyst. The viscosity (at 40 oC), density, cloud point, pour point, flash point and acid number were 3.40 cSt, 0.86 g/ml, -1 oC, -7 oC, 175 oC and 0.19, respectively. This optimum methyl esters conversion obtained met ASTM standard of D-6751. Therefore, soybean oil has been shown in this study as a good candidate for biodiesel production and the data acquired can be scaled up for large scale production. © 2010 International Formulae Group. All rights reserved.

Keywords: Renewable energy, fatty acid methyl esters, diesel, catalyst.