Biodiesel Production from Corn Oil via Enzymatic Catalysis with Ethanol

This work presents experimental results on alkali and enzymatic catalysis of corn oil into biodiesel with an optimization of operating conditions and further experiments on enzyme reuse. A comparison of the alkali-catalyzed methanolysis and ethanolysis of corn oil is done, followed by the study of the enzymatic-catalyzed ethanolysis using the alcohol at different concentrations (ethanol absolute, 96%, and 70%, v/v). Results show that the best operating conditions for biodiesel production using absolute ethanol (containing no water) as reagent are an oil/alcohol molar ratio of 1:6, a catalyst/oil weight percentage of 2.8 wt %, a reaction time of 12 h, and a reaction temperature of 35 degrees C. For these conditions it was possible to obtain a reaction yield of 98.95 wt % with a fatty acid ethyl esters (FAEE) content of 69.2 wt %, with linoleate (C18:2) and oleate (C18:1) being the most significant esters (with relative percentages of 42.97 wt % and 22.54 wt %, respectively). Regarding the evaluation of the enzyme activity loss during reaction, it was concluded that under these conditions it is possible to reuse the enzyme four times after which there was a significant loss of the biodiesel quality according to the EN 14214:2009 standard.