Enzymatic reaction in supercritical carbon dioxide internal mass transfer limitation

Abstract

Publisher Summary This chapter discusses the enzymatic reactions in supercritical carbon dioxide. The intrinsic catalytic properties of enzymes are modified either during immobilization or after they are immobilized. In heterogeneous catalysis, carried out by immobilized enzymes, the rate of reaction is determined not simply by pH, temperature, and substrate solution but by the rates of proton, heat, and substrate transport through the support matrix to the immobilized enzyme. The chapter discusses the internal mass transfer limitation both in hexane and in supercritical CO 2 (scCO 2 ) with different enzymatic support sizes. The theory of generalized Thiele modulus can be applied to an enzymatic reaction both in n-hexane and scCO 2 . The Thiele modulus values indicate a limitation because of the internal mass transfer rate. Thus, in the hexane case, a diffusional control is observed, while in scCO 2 , an intermediate rate between the reactional and diffusional rates is apparent.