Honeycomb ZIF‐67 Membrane With Hierarchical Channels for High‐Permeance Gas Separation

Membrane technology exhibits low cost and high efficiency in gas separation. Zeolite‐imidazole framework‐67 (ZIF‐67) membrane shows a theoretically superior performance in H 2 /CO 2 separation, owing to its effective size‐sieving pores between H 2 and CO 2 . However, the gas molecules are permeate through a series of consecutive crystal cells of common ZIF‐67 polycrystalline membranes, resulting in high transport resistance to the gas permselective transport. To this end, this work employs a contra‐diffusion synthesis to construct a honeycomb ZIF‐67 (h‐ZIF67) crystalline membrane for low‐resistance H 2 /CO 2 permselective transport. The controlled growth of h‐ZIF67 following the van der Drift theory produces the honeycomb polycrystal with hierarchical channels for low‐resistance gas permeation. The prepared membrane with micron‐scale thickness still achieves a H 2 permeance as high as 1.6 × 10 −7 mol m −2 s −1 Pa −1 and a H 2 /CO 2 selectivity of 17, which can be maintained after a long‐term operation for the H 2 /CO 2 mixture separation.