Determination of internal diffusion limitation and its macroscopic kinetics of the transesterification of CPB alcohol catalyzed by immobilized lipase in organic media |
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| Institution: | 1. College of Material and Chemical Engineering, Zhejiang University, Hangzhou 310027, China;2. College of Food Science, Biotechnology and Environmental Engineering, Hangzhou University of Commerce, Hangzhou 310035, China;1. “Petru Poni” Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iasi, Romania;2. Department of Microbiology, Faculty of Biology, University of Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain;3. University of Maribor, Institute of Engineering Materials and Design, Smetanova ulica 17, 2000 Maribor, Slovenia;1. Laboratory of Biotransformation, Institute of Microbiology, Czech Academy of Sciences, Vídeňská 1083, CZ 14220 Praha 4, Czech Republic;2. Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, CZ 16628 Praha 6, Czech Republic;3. Department of Structure and Function of Proteins, Institute of Microbiology, Czech Academy of Sciences, Zámek 136, CZ 37333 Nové Hrady, Czech Republic;1. CAPEC-PROCESS Research Center, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads, Building 229, 2800 Kgs. Lyngby, Denmark;2. Danish Polymer Centre, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads, Building 229, 2800 Kgs. Lyngby, Denmark |
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| Abstract: | Optically active cyanohydrin esters such as (S)-α-cyano-3-phenoxybenzyl (CPB) acetate can be obtained with enzymatic transesterification of racemic cyanohydrins in organic media. The influence of internal diffusion limitation on transesterification of CPB alcohol with vinyl acetate catalyzed by immobilized lipase was studied. Internal diffusion limitation could not be ignored since the immobilized lipase granule was not small enough. In order to express the effect of internal diffusion limitation quantitatively, a method was proposed which calculates the effective diffusion coefficient (De) first and then calculates apparent Thiele modulus (Φ) and finally obtains internal diffusion effectiveness factor, η value (0.55). De was calculated to be 3.1 × 10?10 m2 s?1 by supposing that the immobilized lipase was a sphere granule and the diffusion only existed in one dimension. Φ was calculated to be 2.2 by presuming that transport of substrate through the catalyst could be described by Fick's law. Using King–Altman method, a kinetic model of the transesterification of CPB alcohol with vinyl acetate in organic media in the presence of internal diffusion limitation was proposed based on ping-pong bi–bi mechanism. The relative error of the model was 11.18%. A practicable method to evaluate η value and relatively simple model for such kind of reaction system was proposed in this paper. |
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