Modelling the enantioselective hydrolysis of a meso-diester using pig liver esterase in a two-phase hollow fibre reactor

The enzymatic hydrolysis of the meso-diester cis-cyclohex-4-ene-1,2-dicarboxylate into the monoester methyl-hydrogen(1S,2R)-cyclohex-4-ene-1,2-dicarboxylate, using pig liver esterase, has been studied both experimentally and theoretically in an ultrafiltration hollow fibre contactor. The enzyme is immobilized inside the asymmetric pores of the fibres. The study of the influence of the Reynolds number of each phase on the mass-transfer rate shows that the membrane resistance is the step that controls the transfer of diester from the organic to the aqueous phase, for Reynolds numbers in the aqueous phase above four. A comprehensive mathematical model comprising mass transfer and simultaneous enzymatic conversion was developed. The experimental results are compared with model predictions based on the kinetics of free enzyme in aqueous solution. It is concluded that, although the enzyme activity is decreased when it is immobilized, the proposed hollow fibre reactor is a good candidate to perform the enzymatic hydrolysis under study. The advantages are threesome: the reaction and separation processes are performed in a single step, by contacting two phases through a stable interface; the immobilized enzyme can be used continually and presents a high activity over a large period of time; and the enantiomeric excess of the desired enantiomer (97-98%) remains unaltered during operation.