Esterification Catalysis through Functionalized Membranes

Abstract

Breaking the thermodynamic equilibrium in reversible esterification reactions is achieved through water adsorption on a functionalized membrane. The used functionalized catalytic membrane contains sulfonated polystyrene grafts which act as an alternative to conventional esterification process catalysts. A set of parameters influencing the esterification reaction have been studied. These include feed reactants molar ratio, temperature, different styrene percentages in the membrane, and membrane area. The results show that the increase of molar ratio, temperature, styrene percentage, and membrane surface area increases the reaction conversion and product yield. The high reaction rate obtained on the onset of the reaction, which is attributable to water removal by adsorption, is offset as the reaction proceeds owing to the deactivation of the catalytic active sites by the water adsorbed within the membrane. Therefore, the conversion rate increases up to a maximum and then decreases owing to catalyst deactivation as the membrane becomes progressively saturated with the adsorbed water. The maximum conversion reached was 93.78 percent after a processing time of 10 sec when using 10:1 molar ratio ethanol to acetic acid, 5 percent styrene in the grafted membrane having a diameter of 14.2 cm (1.52 meq of catalyst/g) at 30ºC, and a membrane internal adsorption surface area of 252,450 cm2.