Esterification of Acetic Acid by Flow-Type Membrane Reactor with AEI Zeolite Membrane

AEI-type zeolite membrane for dehydration was prepared, and a flow-type membrane reactor for the esterification of acetic acid and ethanol by AEI membrane was developed. A synthesized AEI membrane had suitable molecular sieving property for gas separation (H₂/i-butane and CO₂/CH₄) and pervaporation (H₂O/acetic acid). AEI membrane showed H₂O permeance of 6.2 × 10^-7 mol m^-2 s^-1 Pa^-1 with a separation factor of 67 at 363 K for the equimolar mixture of H₂O/acetic acid. AEI membrane maintained stable performance under acidic conditions. The yield of ethyl acetate at 363 K in a flow-type membrane reactor with AEI membrane successfully exceeded the equilibrium of 69.1%, reaching 89.0%. The flow rate of feed solution strongly affected the conversion of acetic acid and the space-time yield (STY) of ethyl acetate. Due to the more significant proportion of water selectively removed from the reaction system at a lower feed flow rate, the thermodynamic equilibrium shifted significantly, resulting in higher conversions. In contrast, STY increased with increasing feed flow rate. Our flow-type membrane reactor exhibited a relatively large STY of 430 kg m^-3 h^-1 compared with the batch-type membrane reactor previously reported.