Separation of light gas mixtures using zeolite SSZ-13 membranes

High-quality SSZ-13 membranes with enhanced permeances were synthesized on the symmetric mullite supports by modifying the synthesis recipes, and shown to be useful for light gas separations. The best SSZ-13 membrane displayed doubled CO₂ permeance and comparative CO₂/CH₄ selectivities compared to our previous mullite supported SSZ-13 membranes. Single-gas permeance of CO₂, H₂, N₂, CH₄, C₂H₆ and C₃H₈ decreased at 298 K with increasing kinetic diameter, except for CO₂. The CO₂/CH₄, CO₂/N₂, H₂/CH₄ and N₂/CH₄ ideal selectivities were 360, 20, 62 and 16, respectively, at room temperature. The mixture selectivities for the same equimolar gas pairs at 298 K were 406, 32, 43 and 16, and the faster-gas permeances of 4.4, 3.2, 1.8 and 0.22 mol/(m² s Pa), respectively. Calcination times, long-time operation and long-term storage had few effects on membrane performance.