Biodiesel Preparation Catalyzed By Immobilized Burkholderia Cepacia Lipase

Enzymatic preparation of biodiesel with lipase is a green manufacturing process, which is becoming one of the main directions of new biodiesel techniques. In order to improve catalyzing effeciency and reduce production costs of biodiesel, three probable ways: the choice of new acyl receptor, optimization of process parameters, utilization of synergistic effect of combined lipases, can be employed. In this study, with methanol and methyl acetate as acyl receptor,the Burkholderia cepacia lipase isolated by ourself was applied to catalyze production of biodiesel through transesterification of soybean oil. The effects of enzyme loading, methanol/ oil molar ratio,water content, reaction temperature and reaction time on the conversion rate of biodiesel were studied in details, the parameters of biodiesel preparation with methanol as acyl receptor were optimized by using response surface methodology. The results were showed as follows:(1) With methyl acetate as acyl receptor, under the following conditions: enzyme loading15%, water content 4.0%, reaction temperature 40.4℃,reaction time 12 h, methyl acetate /oil molar ratio 9.0, yield of methyl ester were over 80%.(2) Methanol is usually used as acyl receptor in biodiesel preparation. In the single factorial experiments, the effects of conditions of immobilized Burkholderia cepacia lipase catalyzed production of biodiesel such as the enzyme loading, methanol/ oil molar ratio,water content, reaction temperature and reaction time on the conversion rate of biodiesel were studied. Based on the single factorial experiments, the major impact factors were optimized by response surface method, the quadric regression equation on the yield of methyl ester was established. The results showed that the optimum conditions were: enzyme loading 2.4%, water content 7.1%, reaction temperature 40.4℃, reaction time 10.7 h, methanol/ oil molar ratio 4.5,the predicted yield of methyl ester were 96.9%. In order to check up the reliability of the model, the measuring yield of methyl ester were 97.2%, which coincided with the predicted value 96.9% very well.(3) The synergistic effect which has been proved between lipases with different characteristics can effectively reduce the total amount of enzyme loading, and significantly improve the catalyzing efficiency, so as to shorten the reaction time. The respective combination of two usual immobilized enzymes Novozym 435, Lipozyme TLIM with immobilized B. cepacia lipase from was tried. The results showed that the compound lipases could effectively solve the problems of high enzyme loading and relative lower yield of methyl ester in organic solvent system when single lipase was applied. This suggests that a new biodiesel preparation technique may be developed with the above immobilized lipases.