Highly steam-stable CHA-type zeolite imidazole framework ZIF-302 membrane for hydrogen separation

Metal-organic frameworks (MOFs) as molecular sieve membrane materials have received extensive attention on the gas separation application. However, the membrane separation performance is extremely limited by its intrinsic stability of frameworks. The successful preparation of high-quality gas separation membranes with excellent stability remains a grand challenge. ZIF-302 is based on hydrophobic ligand in-situ design with a high-stabile chabazite (CHA) topology. Herein, we synthesized uniform ZIF-302 nanocrystals with exceptional stability by introducing a modulator. Correspondingly, the continuous dense ZIF-302 polycrystalline membranes were also prepared for the separation of H₂, N₂, CO₂, CH₄ and other gases. The permeance of H₂ and separation factor for H₂/CH₄ mixtures at 35 °C and 1 bar were 2.8 × 10^-8 mol m⁻² s⁻¹ Pa⁻¹ and 51.5, respectively, exceeding the Robeson upper bound in 2008. Furthermore, the separation performance of the super-hydrophobic ZIF-302 membranes for humidified mixed gases can maintain more than 168 h at 35 °C, indicating reliable long-term operational stability. Therefore, the CHA-type ZIF-302 polycrystalline membrane is promising for actual industrial gas separation.