Tuesday, May 3, 2011
Biodiesel is an alternative to petroleum and its derivatives, since its production is cheaper and its use reduces the pollutants emission, besides it is a source of renewable energy. The use of vegetable oils in Brazil has a promising future, since Brazil is one of the largest producers of soybeans and has great prospects for the production of other oilseeds. The objective of this work was to study the variables that influence the transesterification of coconut oil for biodiesel production in catalytic systems with immobilized enzymes. The transesterification reactions were conducted in closed flasks, stirred at 200 rpm and catalyzed by immobilized lipase Novozym®435 (Cândida antarctica) and Lipozyme TL-IM (Thermomices lanuginosus) with ethanol or methanol. The yields on biodiesel were higher with Novozym®435 with both alcohols. Thus others variables were studied with the experiments performed only with this last lipase. The assays were run out according to an experimental design 24 where the variables studied were temperature (40 and 60°C ), concentration of enzymes (5 and 10%), ratio of oil: ethanol (1:3 and 1:9) and was used methanol or ethanol. The best result, 80.5% conversion was obtained on condition of higher temperature, higher molar ratio, higher concentration of enzymes and ethanol as alcohol. The yields obtained showed that the results with ethanol were more significant when compared to methanol. The amount of water is also studies (0 and 5%) and it was observed that increasing the concentration of water exerts a positive influence in the process of biodiesel production.