Effect of homogeneous alkaline catalyst type on biodiesel production from soybean [<i>Glycine max</i> (L.) Merrill] oil

Abstract

Transesterification or alcoholysis is the most commonly applied method for biodiesel production. A catalyst is needed to improve the transesterification reaction and yield. The present study used soybean oil as the raw oil to mix with methanol and four strong alkali catalysts (NaOH, KOH, CH₃ONa &amp; CH₃OK) to undergo a transesterification reaction. Transesterification was carried out using 100% excess alcohol, <i>i.e.</i>, molar ratio of alcohol to soybean oil was 6:1, and catalyst concentration of 1% at 60^oC. Alkali metal alkoxides were found to be more effective transesterification catalysts compared to hydroxides. Sodium methoxide was the most efficient catalyst, although KOH and NaOH could also be used because they are cheaper and are used widely in large scale processing.