An Ionic Covalent\nOrganic Framework Membrane with\nConfined Mobile Carriers for Stable and Efficient Carbon Dioxide Capture

Membrane-based postcombustion carbon capture is a promising\nmethod\nfor reducing carbon dioxide (CO<sub>2</sub>) emissions. Mobile carrier-facilitated\ntransport membranes (FTMs) are receiving attention because they can\nsimultaneously increase CO<sub>2</sub> permeability and CO<sub>2</sub>/N<sub>2</sub> selectivity. However, FTMs still face the challenge\nof carrier loss. Stable immobilization of mobile carriers is essential\nfor achieving and maintaining superior separation performance of FTMs.\nHerein, we report an ionic covalent organic framework (COF) membrane\nwith confined mobile carriers for stable and efficient CO<sub>2</sub> separation. In this structure, a typical CO<sub>2</sub> mobile carrier,\n2,5-diethylenetriamine (DETA), is stabilized in the negatively charged\nnanochannels of the COF membrane. Thanks to the intrinsic CO<sub>2</sub>-facilitated transport of DETA, the COF membrane presents a CO<sub>2</sub> permeance of 2347 GPU and a CO<sub>2</sub>/N<sub>2</sub> selectivity\nof 191 under simulated flue gas conditions. Because the CO<sub>2</sub> mobile carriers are firmly confined within the pores through electrostatic\ninteractions, the membrane shows stable separation performance during\nthe 310 h continuous test. The excellent performance and robust stability\ndemonstrate the significant potential of this innovative membrane\nstructure for practical use in the capture of CO<sub>2</sub> from\nflue gas.