Improvement of esterification conversion by rapid pervaporation dehydration using a high-flux and acid-resistant MOR zeolite membrane

Abstract

Esterification coupled with pervaporation (PV) is an effective method to improve conversion by thoroughlyand rapidly removing the water product. In this study, a high-flux and acid-resistant mordenite (MOR) zeolite membrane was applied to enhance the esterification of acetic acid and ethanol. The effects of catalysts, catalyst loading, reaction temperature and initial acid/alcohol molar ratio on the conversion of ethanol for the esterification with PV were investigated systematically. Results showed that a high conversion (99.3%) was obtained in a short reaction time of 480 min when the operating conditions were optimized as reaction temperature of 353 K, concentrated H2SO4 catalyst loading of 0.1 wt% and initial acid/alcohol molar ratio of 1.5:1. The conversion of esterification without PV reached equilibrium was 76.7% but enhanced to 99.3% with PV in 480 min. The conversion of ethanol was up to 98.4% even at a low initial acid/alcohol molar ratio of 1.2:1. Importantly, the membrane showed good acidic stability in the esterification with PV after 8 reaction cycles. Thus through the coupling of PV and esterification, the conversion of ethanol was greatly improved due to the water from esterification was removed timely. On the other hand, the usage of acetic acid could be reduced, which enormously decreased the energy consumption in the production process.