Vapor phase esterification using a CHA type of zeolite membrane

Abstract

Vapor phase esterification in a chabazite (CHA) zeolite membrane reactor was attempted not only to improve the productivity but also to avoid the use of liquid strong acid. CHA zeolite membrane was successfully prepared on a porous alumina tube by hydrothermal synthesis, showing a water permeance of ca. 2×10−7mol/(m2·s·Pa) and a selectivity of 2850 for H2O/EtOH at 130°C. As the alternate of the liquid acid, proton exchanged mordenite (H-MOR) was selected as a solid catalyst, where the esterification was found to be explained according to the Eley-Rideal mechanism. When vapor-phase esterification was carried out in a double tube type membrane reactor, some equilibrium shift was observed; this was achieved by continuous and selective water removal along the reactor length. Further, it was demonstrated that a simulation model for the membrane reactor, established on the assumption that the ideal conditions could be applied, described the reactor performance well.