Utilization of immobilized lipases as catalysts in the transesterification of non-edible vegetable oils with ethanol

• Main Authors: P. C. Tiosso, A. K. F. Carvalho, H. F. de Castro, F. F. de Moraes, G. M. Zanin
• Format: Article
• Language: English
• Published: Brazilian Society of Chemical Engineering 2014-12-01
• Series: Brazilian Journal of Chemical Engineering
• Subjects: Lipase; Biocatalyst; Non-edible feedstock; Biodiesel; Ethanol
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322014000400002&lng=en&tlng=en

This work reports the use of commercially available immobilized lipase preparations (Novozym® 435 and Lipozyme TL IM, both from Novozymes, and Lipase PS IM from Amano) as catalysts in the transesterification reaction of different alkyl-chain triglycerides with ethanol. The ethanolysis of native oils from Brazilian Amazon plants andiroba (Carapa guianensis), babassu (Orbignya sp.), jatropa (Jatropha curcas), and palm (Elaeis sp.) was studied in a solvent-free system. In a typical reaction, the immobilized preparations were added to the mixture of vegetable oil-to-ethanol in a molar ratio of 1:9. The reactions were performed at 50 ºC for a maximum period of 48 h. Under the conditions used, all the immobilized lipase preparations were able to generate the main esters of fatty acids present in the tested feedstocks, and both the reaction rate and ester yield were dependent on the source of lipase and vegetable oil. The viscosity values for the samples obtained in each reaction displayed a consistent reduction in relation to their original feedstocks, which also confirms the high conversion of triglycerides to ethyl esters (99.8-74.0%). The best performances were obtained with Amano PS IM and Novozym® 435, with the biodiesel samples from the babassu and jatropha oils exhibiting viscosity values in accordance with those predicted by the technical standards of ASTM D6751 (1.9-6.0 mm²/s). Lipozyme TL IM displayed an unsatisfactory performance, indicating that the conditions of the transesterification reaction should be improved. This comparative study using different catalysts and several vegetable oil sources with varying fatty acid compositions is particularly important for all tropical countries with a diversity of native vegetable oil sources.