Selective Gas Permeation in Mixed Matrix Membranes Accelerated by Hollow Ionic Covalent Organic Polymers

Mixed matrix membranes (MMMs) have gained great attention for the efficient CO2 removal from raw nature gas or biogas (CO2/CH4 separation) and flue gas (CO2/N2 separation). Nevertheless, the development of high-performance MMMs for industrial applications is largely limited by the lack of suitable porous fillers. Herein, a novel ionic covalent organic polymer (ICOP-1) consisting of gas selective pores and hollow cavities is facilely fabricated using a metal triflate catalyzed condensation reaction. Considering its unique structural properties, ICOP-1 is explored as a novel filler to enhance the gas separation properties of polysulfone (PSf) membranes. Defect-free MMMs are successfully prepared owing to the high polymer–filler affinity originating from the organic nature of these two phases. Besides, the large cavities and size-selective pores of ICOP-1 lead to a simultaneous increase in membrane CO2 permeability and CO2/CH4, CO2/N2 selectivities. With the addition of only 0.5 wt % of ICOP-1 fillers, the as-prepared MMM demonstrates the optimal gas separation performance with a CO2/CH4 selectivity of 39.7 (at a CO2 permeability of 6.19 Barrer) and a CO2/N2 selectivity of 36.7 (at a CO2 permeability of 6.85 Barrer), opening new opportunities in membrane-based industrial CO2 capture applications.