Recent progress in ternary mixed matrix membranes for CO2 separation

Mixed matrix membranes (MMMs) could combine the advantages of both polymeric membranes and porous fillers, making them an effective alternative to conventional polymer membranes. However, interfacial incompatibility issues, such as the presence of interfacial voids, hardening of polymer chains, and blockage of micropores by polymers between common MMMs fillers and the polymer matrix, currently limit the gas separation performance of MMMs. Ternary phase MMMs (consisting of a filler, an additive, and a matrix) made by adding a third compound, usually functionalized additives, can overcome the structural problems of binary phase MMMs and positively impact membrane separation performance. This review introduces the structure and fabrication processes for ternary MMMs, categorizes various nanofillers and the third component, and summarizes and analyzes in detail the CO2 separation performance of newly developed ternary MMMs based on both rubbery and glassy polymers. Based on this separation data, the challenges of ternary MMMs are also discussed. Finally, future directions for ternary MMMs are proposed.