Chromatographic reactors for reversible enzymatic syntheses

Enzymatic synthesis in organic solvents can be used to synthesize a range of specialty esters used as flavors, fragrances and pharmaceutical intermediates. To apply such synthesis routes on a large scale, however, requires that factors such as equilibrium-limited conversion, inhibition by reactants and/or products, and enzyme stability be dealt with. Combining an enzymatic reaction with adsorptive separation can, many times, provide a better reaction system, resulting in greater production rates.; Reactors combining an immobilized lipase catalyst with a compatible adsorbent selective to one of the reaction products are investigated in this work. Continuous operation of such adsorptive reactors is shown to be possible in a simulated-moving-bed (SMB) arrangement. The application of these adsorptive reactors to a lipase-catalyzed reversible transesterification for the synthesis of isoamyl proponent is experimentally investigated in fixed-bed and SMB reactors. Product concentrations corresponding to complete conversion are attained in the transient of an adsorptive fixed-bed reactor. Nearly continuous operation is shown to be possible in the SMB chromatographic reactor. While complete conversion is not. seen, the product ester is isolated at 83% purity, which represents a large improvement over the 32% purity seen in conventional reactors. A model is developed to represent the transient and steady-states of fixed-bed and SMB adsorptive reactors. Model parameters are determined to describe the reaction kinetics, adsorption equilibrium and transport rates. Simulation results are found to be in agreement with the experimental observations.