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) x 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 N-2) 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 alpha(CO2/CH4) of 130 and 48, the non-zeolitic pores contributed 24.7% and 69% of CH4 permeance, respectively.

Automated summary

High-silica CHA (SSZ-13) zeolite membranes show great potential for CO2 separation, but practical application is limited by high investment costs. In this study, SSZ-13 zeolite membranes were successfully synthesized on hollow fibers with different pore sizes, achieving good CO2/CH4 selectivity and CO2 permeance on membranes with 150 nm pores. Evaluation of gas permeation found that small molecules mainly pass through zeolitic pores, while larger molecules are more sensitive to non-zeolitic pores.