Thesis (M.Eng.)--Chulalongkorn University, 2011

Biofuels has received significant attention recently as a biodegradable and nonpolluting fuel. In this study, butyloleate was prepared in solvent-free system by esterification of oleic acid with butanol using immobilized lipase Novozym 435 as biocatalyst in a batch system. The conversion of free fatty acid (FFA) could reach 91.0% at reaction temperature of 45°C, oleic acid/butanol molar ratio of 1:2, Novozym 435 loading based on FFA weight of 5%, a shaking rate of 250 rpm, and a reaction period of 24 h. The removal of water that was produced during the enzymatic esterification by the addition of molecular sieves could enhance the FFA conversion to 96.1%. Novozym 435 having been used for five cycles still remained active with only slightly loss of catalytic activity. From kinetic study of the reaction at temperatures of 35- 60°C, the reaction appeared to be second order, at which the activation energy (Ea) was 13.64 kJ/mol. This product could reasonable be used as biobased industrial material in biolubricants and diesel fuel additives.