Vapor-phase synthesis of high-flux zeolitic imidazolate framework membranes within confined nanochannels for gas separation.

Membrane separation has emerged as a key technology for sustainable development, as it operates without the need for thermal-drive or chemical adsorbents. Metal-organic framework membranes have attracted considerable interest as advanced separation materials owing to their exceptional chemical stability and superior molecular sieving performance. In this study, we propose a vapor-phase synthesis strategy for fabricating ZIF-8 membrane within a porous support material. The zinc salt impregnated within the pores is subjected to high-temperature pyrolysis to produce the zinc oxide precursor. The oxide produced through high-temperature decomposition within the substrate exhibits strong adhesion to the porous framework. Under exposure to 2-methylimidazole vapor, the zinc oxide precursor embedded in the porous substrate is converted into a continuous and uniform ZIF-8 film, effectively filling the internal pores and forming a continuous membrane that is structurally well-integrated with the support. The final ZIF-8 membrane demonstrates moderate separation performance, achieving a H2 permeability as high as 8 × 104 Barrer while maintaining H2/CO2 selectivity (α = 5.84). This facile and scalable approach offers a potentially suitable strategy for high-throughput pre-separation or membrane contactor applications.