Modeling of lipase-catalyzed oil hydrolysis in supercritical CO2 in a packed-bed reactor

Research on enzyme-catalyzed reactions of oils in supercritical CO2 (scCO(2)) aims at solvent-free natural products enriched in bioactive substances. Easy tailoring of scCO(2) properties and low mass transfer limitations belong to advantages of the method, which perspective of large-scale application depends on enzyme stability in scCO(2). Mathematical model for immobilized lipase-catalyzed vegetable oil hydrolysis in a continuous-flow reactor involves a slow reversible decrease of enzyme activity caused by glycerol retention in the enzyme bed. Reaction kinetics is modeled as pseudo-first-order and pseudo-second-order reversible hydrolysis of tri-, di-, and monoglycerides. Reaction rate constants and parameters of glycerol adsorption were estimated by fitting the model to previously published experimental data. Conditions of hydrolysis catalyzed by Lipozyme TL IM were pressure 10-30 MPa, temperature 30-50 degrees C, and scCO(2) flow rate-to-enzyme load ratio 2-120 g.g(-1) min(-1). The rate controlling step was hydrolysis of triglycerides with pressure and temperature dependent kinetic constant 100-230 min(-1).