Monday, May 5, 2008
6-44

Enzymatic synthesis of biodiesel via alcoholysis of palm oil

Andre L. F. Matassoli1, Igor N.S. Correa2, Claudia O. Veloso1, and Marta A. P. Langone1. (1) Ppgeq, Rio de Janeiro State University, Rua Sao Francisco Xavier 524 / Predio Haroldo Lisboa/ Sala 427, Rio de Janeiro, Brazil, (2) Ppgeq, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier 524, PHLC, sl. 427, Rio de Janeiro, Brazil

Biodisel is a renewable fuel source, with significant potential for use as an alternative to diesel fuels. It is nontoxic, safe to handle and biodegradable. However, production cost of biodiesel is not economically competitive with fossil diesel according to relatively high cost of the lipid feedstocks, which are usually edible-grade refined oils. The conventional process of biodiesel synthesis consists of methanolysis of vegetable oils catalyzed by strong bases. Crude vegetable oils containing high amount of free fatty acids result in several problems to alkali catalytic transesterification. Biodiesel can also be obtained from biocatalytic transesterification using lipases. Lipases (EC 3.1.1.3) constitute a group of enzymes that is becoming increasingly attractive for the oil industry in esterification and transesterification reactions. In this work, biodiesel synthesis by transesterification of crude palm oil, with acid value of 6.26mg KOH/g oil, and alcohol catalyzed by commercial immobilized lipases was investigated. The effect of the type of the alcohol (ethanol or methanol), biocatalyst concentration and molar ratio of reactants was determined. The ethanolysis of palm oil by successive additions of ethanol (stepwise ethanolysis) was also investigated. The performance of the enzymatic transesterification was compared to the traditional process that uses KOH as catalyst. The best biodiesel yield (50 %) was obtained with three stage stepwise addition of ethanol using 9% w/w of Lipozyme TL IM and ethanol/oil molar ratio of 3 at 50ºC. In these conditions, the reactions carried out with 1% and 3% of KOH (w/w) result in lower yields, 3 and 20%, respectively.

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