Tuesday, May 3, 2011
Commercially available immobilized lipase preparations (Novozym 435 and Lipozyme TL IM both from Novozymes and Lipase PS IM from Amano) were used as catalysts in the transesterification reaction of different native oils from Brazilian Amazon regions, such as Andiroba (Carapa guianensis), Babassu (Orbignia sp.), Palm tree (Elaeis sp.) and Jatropha (Jatropha curcas) in a solvent free system. In a typical reaction, 10 % (w/w) of the immobilized preparation in relation to the total reaction medium was added to the mixture of vegetable oil-to-ethanol molar ratio of 1:9. Reactions were run at 50° C for a maximum period of 48 h and were monitored by quantifying the concentration of ethyl esters with time by gas chomatogharpghy. All immobilized lipase preparations under the conditions tested were able to form the main esters of fatty acids present in the tested feedstocks, although both the reaction rate and yield in esters were dependent on the source of lipase and the vegetable oil. The biocatalyst activities were higher when vegetable oil with short chain fatty acids or with a high unsaturated degree were used. Viscosity values for biodiesel samples obtained in each reaction showed consistent reduction in relation to their original feedstock material, which also confirms the high conversion of triglycerides to ethyl esters. As the viscosity values obtained are not yet in the range established by the ASTM D5761 (3.0 to 6.0 cSt) further study is still required to optimize this process as a function of various reaction parameters.