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SSZ-13 zeolite membranes were synthesized on the inside surface of porous stainless steel tubes. In parallel with zeolite pores, the membranes had nonzeolite pores that were larger than the 0.38-nm zeolite pore diameter, but single-gas permeances of H2, N2, CH4, and n-C4H10 decreased with increasing kinetic diameter at 298 K. The CO2/CH4, H2/CH4 and H2/n-C4H10 ideal selectivities were 11, 9.0, and 63, respectively, at 298 K, and the separation selectivities for the mixtures of the same gas pairs were 12, 8.2, and 5.7 at 298 K. The SSZ-13 membranes selectively removed H2O from HNO3/H2O liquid mixtures by pervaporation to break the azeotrope at 69.5 wt % HNO3. The permeate concentration was 38.3% HNO3, and the total flux was 0.12 kg/m2·h at 298 K.

We present experimental and theoretical results for single-component permeance of CH 4 and CF 4 through a supported silicalite membrane at a range of temperatures and pressures. Our theoretical model uses a continuum description of molecular transport through zeolite crystals that is directly parametrized from atomically detailed simulations of molecular adsorption and transport. This approach does not require any assumptions regarding the loading dependence of the adsorbed species' transport or Maxwell-Stefan diffusivities. Our results are the first direct comparison between a fully atomistic description of intracrystalline transport and permeance measurements for a macroscopic zeolite membrane. These results help to isolate the contributions to the overall flux through polycrystalline zeolite membranes that arise from molecular transport through nonzeolitic pores. We also discuss avenues for future extensions and improvements of our atomistic approach to modeling practical zeolite membranes.