Esterification and Trans-esterification Reaction of Fish Oil for Bio-diesel Production

To produce biodiesel efficiently from fish oil containing 4% free fatty acid, esterification and trans-esterification were carried out with Vietnam catfish oil, which was kindly provided from GS-bio company. Heterogeneous solid acid catalysts such as Amberlyst-15 and Amberlyst BD-20 and sulfuric acid as homogeneous acid catalyst were used for the esterification of free fatty acids in the fish oil. Sulfuric acid showed the highest removal efficiency of free fatty acid and the shortest reaction time among three acid catalysts. The base catalysts for trans-esterification such as KOH, NaOCH3 and NaOH were compared with each other and KOH was determined to be the best transesterification catalyst. Some solid material, which assumed to be sapo- nified product from glycerol and biodiesel, were observed to form in the fish oil biodiesel when using NaOCH3 and NaOH as the transesterification catalyst. The initial acid value of fish oil was proven to have a negative effect on biodiesel conversion. Of the three catalysts, KOH catalyst transesterification was shown to have high content of FAME and the optimal ratio of methanol/oil ratio was identified to be 9:1.