Fabrication of a high-performance MOF-COP-based porous hollow fiber membrane for carbon dioxide separation

A thin-film nanocomposite (TFNC) hollow fiber membrane with high CO2 permeability and selectivity was synthesized for the separation of carbon dioxide, a major greenhouse gas. A highly porous polyethersulfone (PES) hollow fiber membrane support with a porous structure was first fabricated using heat and pressure treatments, and a thin film was prepared via interfacial polymerization by reacting polyethylenimine (PEI) with 1,3,5-benzenetricarbonyl trichloride (TMC) on the surface of the PES support. A metal–organic framework (MOF)-covalent organic polymer (COP) complex, obtained via polycondensation between an UiO-66-NH2 based MOF and a piperazine- and cyanuric chloride-based COP, was then added to the TFNC to prepare the mixed matrix membrane. The complex contributed to reducing defects between the porous support and the coating layer and additionally led to high CO2 permselectivity by providing a CO2 permeation pathway within the support. The newly prepared TFNC hollow fiber membrane contributed to its excellent separation performance, as evidenced by a CO2 permeability of 352 GPU and a CO2/N2 ideal selectivity of 75 after optimization of the MOF-COP content.