CONTINUOUS SYNTHESIS OF ETHYL MYRISTATE BY ENZYMATIC-REACTION IN SUPERCRITICAL CARBON DIOXIDE

The enzymatic esterification of myristic acid with ethanol catalyzed by an immobilized lipase from Mucor Miehei has been performed under supercritical conditions. After previous experiments in supercritical carbon dioxide showing a high stability of this enzyme(1) and leading to a kinetic description of the reaction in a stirred reactor,(2) the reaction was realized in a continuous mode through a fixed-bed reactor. The effects of water concentration and fluid flowrate on the reaction rate are investigated. An increase of carbon dioxide moisture content from 0 to 0.25% (mass) causes an increase in the conversion, whereas, beyond this value, the lipase activity is irreversibly altered. Production rate surprisingly increases with fluid flowrate when reactants flowrates are maintained constant, but decreases when reactant concentrations are kept constant, confirming a reaction mechanism including inhibition by ethanol.