Mixed Matrix Membranes Based on Metal–Organic Frameworks with Tunable Pore Size for CO₂ Separation

Two isomorphous MOFs (Ni₂(l-asp)₂bipy and Ni₂(l-asp)₂pz) 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 CO₂, H₂, N₂, and CH₄. 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 CO₂ permeability and CO₂/H₂ selectivity. The highest CO₂ permeation property was achieved by Ni₂(l-asp)₂­bipy@­Pebax-20 of 120.2 barrers with an enhanced CO₂/H₂ 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 CO₂ capturing.