Methyl ester production from high free fatty acid mixed crude palm oil

Abstract

Methyl esters were prepared from mixed crude palm oil containing a high free fatty acid content by using a two-stage process. Sulfuric acid was used as the catalyst in an esterification reaction which was then followed by a transesterification reaction using sodium hydroxide as the catalyst. The products of the reaction at various time intervals were sampled to determine the percentage of tri-,di-, and monoacyl glycerides, free fatty acid and methyl ester present. Analysis was performed by a thin layer chromatographic technique. A factorial experiment was carried out using 8, 10 and 12% by volume of methanol and 1, 3 and 5 % w/w of sulfuric acid in the acid catalyzed esterification process. Similarly, 16 , 20 and 24% v/v methanol and 2, 3 and 4 % w/w of sodium hydroxide were used in the alkaline catalyzed transesterification process. Results from the analyses showed that with 3 and 5 % w/w of sulfuric acid, the free fatty acid of the oil could be significantly decreased in less than one hour at 60oC. However, the amount of methanol used had a negligible effect on the reduction of the free fatty acid content. The subsequent transesterification process using sodium hydroxide as catalyst and 20 and 24 % v/v of methanol produced an ester having 99 % w/w methyl ester.

Keywords

• mixed crude palm oil
• 2 stage process
• esterification-transesterification process