Kinetic study on esterification of palmitic acid catalyzed by glycine-based crosslinked protein coated microcrystalline lipase

Enzymatic esterification of fatty acid-rich feedstocks represents an efficient and eco-friendly catalytic process for production of biodiesel. In this study, the reaction kinetics on esterification of palmitic acid with methanol using the heterogeneous glycine-based crosslinked protein coated microcrystalline lipase (CL-PCMC-LIP/Gly) was studied. The maximum FAME yield of over 95% based on a molar basis was achieved at 15% (w/w) enzyme dosage with a 4:1 [MeOH]/IFFA] molar ratio after incubation at 50 degrees C for 1 h in the presence of tert-butanol as a co-solvent. According to the rate equation based on the Ping Pong Bi Bi mechanism model with methanol inhibition, the maximum velocity of the reaction was 4.8 x 10(-3) M/min while the Michaelis-Menten's constants for palmitic acid (Km,pA) and methanol (K-m,K-MeOH) were 2.2 M and 1.4 M, respectively with the inhibition constant of methanol (14(i,MeoH)) of 32.6 M. The turnover number (k(cat)) of CL-PCMC-LIP/Gly was 2.7 min(-1) under the optimized experimental condition. The reaction kinetics result provides an important basis for further up-scaling study of the enzymatic esterification process for biodiesel synthesis. (C) 2015 Elsevier B.V. All rights reserved.