Hierarchical Fibrous Metal–Organic Framework/Ionic Liquid Membranes for Efficient CO2/N2 Separation

The structural diversity and chemical functionality of metal–organic frameworks (MOFs) render them promising candidates for CO2 adsorption and separation. However, their applications are often restricted by their intrinsic fragility and decreased processability. Herein, a hierarchical fibrous MOF/ionic liquid (IL) membrane was constructed by assembling well-ordered ZIF-8 nanounits with an encapsulated IL along the polyimide (PI) fibers. This design promotes the formation of an efficient three-dimensional gas transfer network and generates an abundance of nanopores decorated with CO2-philic units, thereby enhancing the separation of CO2 from N2. The hierarchical fibrous PI/ZIF-8/IL membranes exhibit remarkable structural features, including a large specific surface area of 79.89 m2 g–1, a high porosity of 93.28%, and excellent mechanical stability. Moreover, the PI/ZIF-8/IL membranes demonstrate an enhanced CO2 adsorption capacity of 3.32 mmol/g at 298 K and 1 bar, an excellent CO2/N2 selectivity of 28, and a stable recyclable regeneration capability. The integrated hierarchical pore structure proposed in this study provides a practical direction for the rational design of MOF/IL membranes for targeted gas separation applications.