The study on the coupled process of column distillation and vapor permeation by NaA zeolite membrane for ethanol dehydration

A pilot was used to experimentally study the ethanol dehydration process, based on the coupled process of distillation and vapor permeation by NaA zeolite membrane, and the effects of the water content in the feed, reflux ratio, mass flow, the product purity of the distill and the operating stability were systematically analyzed. It was found that due to the placement of NaA membrane, the operation zone of the original column could be significantly extended in the coupling, which in return could reduce the column facility investment. Based on the interplay among the operation parameters, it was found that the water content of the distilled product from the column could be used as a critical parameter to balance the energy consumption of the column and the membrane facility investment, and a value of 20 wt.% was recommended for the coupling. During the steady test of the coupling, the results indicated that the pilot plant could be continuously operated for 18 h to dehydrate the feed (water/ethanol) from 60 wt.% to 8 wt.%, where the steady state was further validated in process simulation of Aspen plus. In summary, the parameters suitable for the stable operation of the distillation-vapor permeation coupling were investigated for the given condition. This research paves a foundation for the large-scale industrial design and application of the distillation-vapor permeation coupling.