Biocatalytic esterification of palm oil fatty acids for biodiesel production using glycine-based cross-linked protein coated microcrystalline lipase

Conversion of feedstocks containing high free fatty acid contents to alkyl esters is limited by the currently used alkali-catalyzed biodiesel synthesis process. In this study, esterification of palm fatty acids to ethyl esters was studied using heterogeneous cross-linked protein coated microcrystalline (CL-PCMC) lipase. Optimization of biocatalyst synthesis by variation of matrix components and organic solvents showed that highly active CL-PCMCs could be prepared from Thermomyces lanuginosus lipase with glycine as the core matrix in acetone. The optimized reaction contained 20% (w/w) glycine-based CL-PCMC-lipase, a 1:4 fatty acid molar equivalence to ethanol in the presence of an equimolar amount of tert-butanol which led to production of 87.2% and 81.4% (mol/mol) of ethyl ester from palmitic acid and industrial palm fatty acid distillate (PFAD), respectively after incubation at 50 °C for 6 h. CL-PCMC-lipase is more catalytically efficient than protein coated microcrystalline (PCMC) lipase, Novozyme®435 and Lipolase 100T for both free fatty acids and palm fatty acid distillate. The CL-PCMC-lipase showed high operational stability with no significant loss in product yield after 8 consecutive batch cycles. The glycine-based microcrystalline lipase is thus a promising alternative economical biocatalyst for biodiesel production from inexpensive feedstocks with high free fatty acid contents.

Glycine was used as the core matrix with acetone as the precipitating solvent for preparation of high-performance CL-PCMC-lipase for synthesis of ethyl ester from palmitic acid. The optimized biocatalyst showed higher catalytic performance than commercial immobilized enzymes on biodiesel synthesis from palm fatty acid distillate.Figure optionsDownload as PowerPoint slideHighlights
► The use of glycine as the core matrix for high performance CL-PCMC preparation.
► Biodiesel synthesis from palm fatty acid distilllate using glycine-based CL-PCMC lipase.
► The use of tert-butanol as a co-solvent at low molar content for improving catalytic performance of CL-PCMC lipase on fatty acid esterification.