Production of methyl esters from palm fatty acids in supercritical methanol

Abstract

This study investigated the biodiesel production via a noncatalytic esterification reaction in supercritical methanol. The palm oil fatty acids were chosen as the raw material because of its availability as a low cost byproduct of palm oil industry. The variables affecting the methyl ester (biodiesel) conversion were investigated. which included molar ratio of fatty acids and methanol (1:1 to 1:12), reaction temperature (250 and 300 degree celsius) and reaction time (from 10 to 80 min). the results from this study showed that esterification of palm oil fatty acids in supercritical methanol gave the high conversion of 94% and was obtained at the molar ratio 1:6 (fatty acids: methanol) and at 300 degree celsius after 30 min. Furthermore, water whose content in fatty acid between 0-30 %v/v was found to lower the percent yield of methyl ester by hydrolyzing methyl ester back to fatty acids, and the degree of hydrolysis increased as water content and reaction time increased. when compare the result of methyl esterification of fatty acids in with methyl transesterification of purified oil, the result shows that the esterification of palm fatty acids requires lower operating conditions (Molar ratio and Time). when compared with conventional acid catalyzed process, supercritical methyl esterification of fatty acids required shorter reaction time and no neutralization process was needed.