Influence of Cross-Linking, Temperature, and Humidity on CO2/N2 Separation Performance of PDMS Coated Zeolite Membranes Grown within a Porous Poly(ether sulfone) Polymer

Studies of zeolite membranes for gas separations, including natural gas purification, biogas purifications, and CO2/N2 separation are well documented. In this paper, using CO2/N2 separation as a model system, we examine a series of zeolite (faujasite)/polymer composite membranes. These zeolite membranes were prepared by growing a continuous zeolite layer within a porous poly(ether sulfone) (PES) support followed by a polydimethylsiloxane (PDMS) coating layer to fix defects in the zeolite/PES layer. The effect of PDMS cross-linking, humidity in the feed gas (46 ppm), and temperature on the transport properties were studied. The separation performance was significantly improved with membranes that used cross-linked PDMS versus un-cross-linked PDMS. At room temperature, the introduction of humidity completely suppressed CO2/N2 separation. With higher temperatures, the effect of humidity on CO2/N2 separation performance was alleviated to some extent. Exposure to humidity at high temperature led to poor recove...