SSZ-13 zeolite membranes on four-channel α-Al₂O₃ hollow fibers for CO₂ separation

High-silica CHA (SSZ-13) zeolite membranes exhibit great potential for CO₂ separation. However, the practical application is significantly hindered by the high investment cost. Here, we synthesized SSZ-13 zeolite membranes on four-channel hollow fibers with pore size of 150 nm, 370 nm and 600 nm, respectively. The CO₂/CH₄ selectivity of 127 ± 11 as well as CO₂ permeance of (3.1 ± 0.6) × 10^-7 mol m⁻² s⁻¹ Pa⁻¹ was achieved on the membranes synthesized on the hollow fibers with 150 nm pore size at 433 K for 96 h. The single gas permeation was quantitively assigned to evaluate surface diffusion, Knudsen diffusion and viscous flow through the as-synthesized membranes. The permeation of small molecules (e.g., CO₂ and N₂) is mainly contributed by the zeolitic pores, however, the permeation of relatively big molecule (e.g., CH₄) is more sensitive to the non-zeolitic pores. For the membranes with α_CO2/CH4 of 130 and 48, the non-zeolitic pores contributed 24.7% and 69% of CH₄ permeance, respectively.