Improved SSZ-13 thin membranes fabricated by seeded-gel approach for efficient CO₂ capture

High-quality standard oil synthetic zeolite-13 (SSZ-13) membranes with thickness only ∼ 1.0 µm were prepared on tubular supports by the new seeded-gel approach. Seeded-gel approach is simpler than the normal secondary-growth one since adding seeds in the gel is simpler than seeding on the support surface. The synthesis time was greatly reduced from 3.0 to 1.0 d after synthesis modification of gel aging and seed sizes. Low temperature ozone calcination was used for the removal of the organic structural directing agent. The best SSZ-13 membrane displayed CO₂ permeances of 1.3 × 10^–6 and 1.5 × 10^–6 mol·m⁻²·s⁻¹·Pa⁻¹ and CO₂/CH₄ and CO₂/N₂ selectivities of 125 and 27 for equimolar CO₂/CH₄ and CO₂/N₂ mixtures at 0.2 MPa pressure drop and 298 K, respectively. Separation performance of the membrane in the two binary mixtures is higher than that of most zeolite membranes. Three SSZ-13 membranes were reproducibly prepared on tubular supports by seeded-gel approach and the standard deviation ratios of CO₂ permeance and CO₂/CH₄ selectivity are 12.5% and 7%, respectively. It suggests that this new synthesis approach is creditable. The effects of temperature and pressure on separation performance of the thin SSZ-13 membranes were studied in the two binary mixtures. The tubular SSZ-13 membranes displayed great potentials for CO₂ capture from natural gas, biogas and flue gas.