Mixed Matrix Membranes Based on Benzimidazole-Modulated MOFs for Enhanced CO <sub>2</sub> Capture and H <sub>2</sub> Separation
Peiyao Niu, Tianyou Li, Qizheng Zhao, Yongchao Sun, Jingfa Zhang, Fangxu Fan, Gaohong He, Canghai Ma
Abstract
Mixed matrix membranes (MMMs) integrate the benefits of organic polymer membranes with porous inorganic fillers, leading to an enhancement in both gas permeability and separation selectivity. As a commonly used filler, ZIF-8 exhibits promise in enhancing the gas separation performance of MMMs. However, further improving the gas selectivity of ZIF-8-based MMMs remains a challenge. To improve the gas selectivity of ZIFs, we synthesized ZIF-BI via the “mixed linker method” using a bulky benzimidazole ligand, which restricts imidazole ring twisting and enhances gas selectivity. At a 40 wt % ZIF-BI loading, the ZIF-BI/6FBDA MMM exhibited CO 2 and H 2 permeabilities of 25.7 and 49.6 Barrer, respectively. Additionally, the CO 2 /CH 4 and H 2 /N 2 selectivities reached 151.4 and 261.1, both transcending the 2008 Robeson upper bounds. This work provides an innovative way to make ZIF materials and high-performance gas separation membranes, offering solutions for CO 2 capture and H 2 separation.