Biodiesel Production From Vegetable Oils With Methyl Acetate As Acyl Acceptor

Biodiesel fuels synthesized from vegetable oils and animal fats have received considerable attention in recent years as a renewable, biodegradable, and non-toxic fuel. So far, among its synthetic methods, enzymatically catalyzing method is one of the most potential one, which overcomes nearly all problems caused by the chemical methods, but one main problem that lipases are of high price and instability during processing blocks it from industrialization. In conventional enzymatic methods, short chain alcohols (such as methanol or ethanol) are used as acyl acceptor in the transesterification of TAGs (triacylglycerols) for biodiesel production. But these alcohols can denature lipases, and the reaction side-product glycerol is also easily absorbed on the surface of immobilized lipases, which negatively affects on the activities of the lipases.A novel route for biodiesel production from different kinds of refined and crude vegetable oils (cottonseed oil, rap oil, oil camellia oil and soybean oil) is reported in this paper. Herein, methyl acetate was used as a novel acyl acceptor, which does not influence the lipase activity and no glycerol is produced in the reaction. The main results are as follows:When choosing Novozym 435 (immobilized Candida Antarctica lipase) as the catalyst, lipase loading 30% of oil weight, molar ratio of methyl acetate/oil 14:1, temperature 40℃and reaction time 14h, the highest methyl ester (biodiesel) yield of 97% with the refined cottonseed oil was obtained, and the crude cottonseed oil was 96%. Also when choosing Novozym 435 (immobilized Candida Antarctica lipase) as the catalyst, lipase loading 30% of oil weight, molar ratio of methyl acetate/oil 16:1, temperature 40℃and reaction time 14h, the highest ME yield of 93% with the refined rape oil was gotten..With camellia oil, when choosing Novozym 435 (immobilized Candida Antarctica lipase) as the catalyst, lipase loading 30% of oil weigh, molar ratio of methyl acetate/oil 16:1, temperature 40℃and reaction time 12h, the highest ME yield of 92% was gotten with the refined oil, and the crude oil was 90%.With soybean oil, when choosing Novozym 435 (immobilized Candida Antarctica lipase) as the catalyst, lipase loading 30% of oil weight, molar ratio of methyl acetate/oil 12:1, temperature 40℃and reaction time 10h, the highest ME yield of 91% was produced with the refined soybean oil, and the crude soybean oil was 89%.Meanwhile, the manipulation stability of the lipase was also tested. Owing to the minor effect of methyl acetate and the reaction products on the lipase, it has been running for 40 cycles with no significant loss of its activity, suggesting that the lipase can stably and well function under the novel technics.From the above experimental results, it bears out that the new route seems to be very promising for biodiesel synthesis, especially in large-scale production.