Abstract: Lipozyme TL IM was used for the synthesis of biodiesel from rapeseed oil.The effects of pretreatment of the lipase,rinsing the lipase with solvents, reaction temperature, way of addition of methanol on the stability of the lipase were investigated. The experiment showed that the lipase was more stable when Lipozyme TL IM was preincubated in oleic acid methyl ester for 0.5 h, and subsequently in rapeseed oil for 12 h. 40 ℃ was found to be the optimal reaction temperature of batch runs.The stability of the immobilized lipase was enhanced by rinsing the lipase with acetone to remove glycerol adsorbed on the support. A three-step methanolysis protocol was used to protect the immobilized lipase from inactivation by methanol. The pretreated Lipozyme TL IM was used to catalyse the methanolysis at 40 ℃ reacting 24 h as one batch. One molar equivalent of methanol was added at various reacton time in 0, 8 or 16 h respectively at each batch. Acetone was used to remove glycerol at 8, 16 or 24 h respectively at one time and the immobilized lipase was reused for the next step or batch. The residual activity of lipase is still about 85% after being continuously reacted for 10 batches.

Key words: biodiesel, Lipozyme TL IM, rapeseed oil