Mixed Matrix Membranes Based on Metal–Organic Frameworks with Tunable Pore Size for CO<sub>2</sub> Separation

Two isomorphous MOFs (Ni<sub>2</sub>(l-asp)<sub>2</sub>bipy and Ni<sub>2</sub>(l-asp)<sub>2</sub>pz) with different pore sizes were incorporated into poly­(ether-<i>block</i>-amide) (Pebax-1657) to prepare the mixed matrix membranes (MMMs) with gas permeation properties for CO<sub>2</sub>, H<sub>2</sub>, N<sub>2</sub>, and CH<sub>4</sub>. Different loading ratios of MOFs with mass percentage from 10% to 30% were studied. Compared with the pure polymer membrane, the as-synthesized two series of MMMs showed improved CO<sub>2</sub> permeability and CO<sub>2</sub>/H<sub>2</sub> selectivity. The highest CO<sub>2</sub> permeation property was achieved by Ni<sub>2</sub>(l-asp)<sub>2</sub>­bipy@­Pebax-20 of 120.2 barrers with an enhanced CO<sub>2</sub>/H<sub>2</sub> selectivity of 32.88 compared with 55.85 barrers and 1.729 of the pure polymer membrane, respectively, which makes it a potential candidate for future applications in CO<sub>2</sub> capturing.