Scalable synthesis of bimetallic ZIF membranes on the inner-surface of ZnO hollow fiber for gas separation

Metal-organic framework (MOF) membranes with high stability and porosity have shown great potential for efficient hydrogen separation. As a result, searching for a simple and efficient synthesis method to synthesize large-area, continuous, and dense MOF membrane has received an extensive attention. In this work, we demonstrated that a support-induced synthesis strategy to fabricate a series of 20-cm long bimetallic Zn/Co-ZIF membranes on the inner surface of ZnO hollow fiber. Uniform-thickness Zn/Co-ZIF membranes were prepared by periodically inverting the autoclave to alter the flow state of the synthesis solution inside the hollow fibers. The obtained Zn/Co-ZIF membrane showed a good H₂/CH₄ selectivity of 15.75 with a H₂ permeance of 1.15 × 10⁻⁷ mol·m⁻²·s⁻¹·Pa⁻¹ and the membrane displayed excellent long-term operation stability for 20 days. Furthermore, the 11 Zn/Co-ZIF membranes (with a membrane area up to about 100.91 cm²) were successfully prepared in an autoclave in order to further improve the metal source utility. These membranes exhibited similar H₂ separation performance, with H₂/CH₄ selectivities of 12.69–14.59 and H₂ permeances of 1.64–2.05 × 10⁻⁷ mol·m⁻²·s⁻¹·Pa⁻¹, demonstrating excellent reproducibility.