Biodiesel production by solvent-free ethanolysis of palm oil catalyzed by fermented solids containing lipases of Burkholderia contaminans

Fermented solids containing lipases from Burkholderia contaminans LTEB (denominated BCFS) were obtained by solid-state fermentation using sugarcane bagasse impregnated with soybean oil. These solids were dried and used to catalyze the ethanolysis of palm oil in a solvent-free reaction medium. The reaction was optimized in 25-mL vials, containing 15 mmol of palm oil. Molar ratios (MR) of ethanol to palm oil of 3:1 and 4.5:1 were tested, with stepwise addition of ethanol. In these experiments, the maximum conversion of palm oil achieved in 48 h was 90%, with a MR of 4.5:1 and ethanol addition in 3 steps. We then used BCFS in a packed-bed reactor with recirculation. Ethanol was added in four steps, with an overall molar ratio of ethanol added to initial oil of 5.5:1, giving a conversion of 89% in 30 h. When the same fermented solids were used under the same conditions in successive 30-h batches in this packed-bed bioreactor, with sequential washings with n -hexane and tert -butanol between cycles, the conversion in the 5th cycle was 66%. These results are comparable to those that have been obtained for transesterification of palm oil in solvent-free reaction media with commercial lipases, with our catalyst having the advantage that it is much cheaper to prepare.