(464d) Na-LTA Membranes with High Water Selectivity for Dimethyl Ether Production in a Catalytic Membrane Reactor

As an important industrial intermediate, Dimethyl Ether (DME), can be used as a promising clean fuel in various ways. Traditionally, DME is produced either through methanol dehydration or a couple of consecutive reactions for DME directly from syngas. However, the yield of DME is low, limited by the equilibrium in both processes. In order to increase the DME yield, a novel catalytic membrane reactor to remove the produced water in-situ from the reaction system will be beneficial.

In this study, a highly water permeable NaA membrane, prepared on ceramic hollow fibers with secondary growth method, was investigated to selectively remove water from the simulated gas mixtures of CO₂/H₂/CO/Methanol/H₂O with representative compositions from the reactions producing DME from syngas route at very challenging conditions (temperatures up to 250 ^oC and pressures up to 600 psig). Current results showed that, when the feed water concentration was 2.57 mol.%, the membrane selectivity of H₂O/CO₂ was higher than 200, and no CO, H₂, Methanol were detected in the permeate side of the membrane at 250 ^oC and 300 psig. Stability testing over 11 h showed the NaA membrane had a good stability with <10% performance degradation. These results suggest that NaA membranes are capable of removing water in-situ in a membrane reactor, and thus increase the DME yield in syngas route at elevated temperatures and high pressures. We also expect NaA membranes be used to increase the product yield of reactions with water as a by-product in a catalytic membrane reactor at harsh conditions.