Sunday, May 4, 2008
4-44

Studies on kinetics of the biodiesel fuel production process catalyzed by free and immobilized lipases

Renata M. R. G. Almeida, Anny Caroline S. da Silva, Rosana R. L. Araujo, Davi A. Mendonça, and Livia M. O. Ribeiro. Technology Center, Federal University of Alagoas, Campus A. C. Simoes, Via Br 104-North, Km 97, Tabuleiro dos Martins, Maceio, Brazil

Alternative fuels for diesel engines are becoming increasingly important due to diminishing petroleum reserves and the environmental consequences of exhaust gases from petroleum-fuelled engines. In recent years, studies on biological systems for biodiesel synthesis have become an attractive alternative to classical methodologies mainly because chemical transesterification alkali-catalysis is energy intensive, the recovery of glycerol is difficult, and free fatty acids and water interfere with the reaction. Although the use of lipases can overcome the problems mentioned above it has some difficulties in the scale up of the process and the high costs of lipases have reduced industrial applications of theses enzymes in transesterification reaction. The use of immobilized lipases is very advantageous since it can be easily recovered at the end of the reaction and continuously recycled. In this work experimental assays were carried out to study the biodiesel fuel production kinetics with ethanol from two different types of vegetables oils: soybean and coconut. The transesterification reactions were catalyzed by commercial lipases in free and immobilized forms, Lipozyme CALB L and Novozym 435, respectively, kindly supplied by Novozymes Latin America Ltda. The assays were carried out in a batch stirred glass reactor. A stirring of 150 rpm was kept constant throughout the progress of all experiments. The temperature of the reaction system was controlled heating metal jacket. Samples were withdrawn from the reactor at regular intervals for subsequent analysis. Biodiesel fuel concentrations were determined by gas chromatographic analysis. The results biodiesel yields of different runs were compared.


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