Study On Production Of Biodiesel With Compound Lipases

Increasing attention is being paid to biodiesel as a friendly environmental, non-toxic and renewable diesel fuel. In this study, the biodiesel production with compound lipases has been investigated.Synergistic effect was found in biodiesel production catalyzed by free compound lipase, and was validated by a series of free lipases. The results showed that the transesterification efficiency of compound lipases in biodiesel production was higher than that of single lipase with high region-selectivity. This synergistic effect is especially obvious among lipases with the similiar transesterification efficiency yet different region-selectivity.The biodiesel production with compound immobilized lipases was investigated. The transesterification efficiencies between compound lipases and single lipase in solvent-free system and tert-butanol system were compared, and the compound lipases were found to have higher efficiency. And the ratios of lipases in the compound lipases were optimized.In solvent-free system, when Novozym435 was mixed with Lipozyme TLIM and Lipozyme RMIM both at the ratio of 70/30, the methyl ester yields were higher than that of only with Novozym435 by 9.52% and 9.99% respectively; while in tert-butanol system, when Novozym435 was mixed with Lipozyme TLIM and Lipozyme RMIM at the ratio of 60/40 and 80/20, the methyl ester yields were higher than that of only with Novozym435 by 9.89% and 7.48% respectively. Compound lipases exhibited synergistic effect in isolvent-free system and tert-butanol system.The reaction condition in tert-butanol system was optimized. The results showed when the optimal conditions for transesterification were 40% solvent quantity, temperature 40℃, 4:1methanol/oil molar ratio, Novozym435 1.35%+Lipozyme TLIM 1.80% lipase, 200rpm, methyl esters yield of 92% was obtained after 24h reaction, and the compound lipases were continuously used for 8 cycles, methyl esters yield were always over 90%, which suggested there was no obvious loss of their activity.Compound lipases were used to catalyze more oil substrates. The methyl ester yields was all higher than 90%, much higher than that of single lipase in soybean oil, rapseed oil, cottonseed oil, castor oil, olive oil, tea oil and tung oil. The results showed that compound lipases have great potentiality to apply for various oils to make biodiesel.