Thesis (M.Sc.)--Chulalongkorn University, 2008

Production of biodiesel from palm fatty acid, which was a by-product from refining palm oil production, was investigated semi-continuous process catalyzed by Novozym 435. It was found that, using tert-butanol as a cosolvent could maintain activity of lipase even high amount of methanol was present in the system and could improve yield of fatty acid methyl ester (FAME). A molar ratio of palm fatty acid and methanol, tert-butanol quantity and flow rate had significant effects on the percent molar conversion in semi-continuous process. The appropriate conditions for synthesis were as follows: reaction temperature 50℃, flow rate 1.87 mg/sec, and methanol to palm fatty acid ratio 2:1 and tert-butanol 29% based on palm fatty acid weight. One-step and three-step process were investigated. The highest conversion ratio of the FAME from one-step and three-step under the optimal condition was 80% and 92%, respectively. The lipase catalyst could be used for > 240 hours without decrease of the activity.