A review from material functionalization to process feasibility on advanced mixed matrix membranes for gas separations

Carbon capture and hydrocarbon purification via economically viable and energy-efficient membrane systems have recently attracted increased interest. Mixed matrix membranes (MMMs) made from metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), and 2-dimensional (2D) materials such as MXenes and layered double hydroxides (LDHs) are particularly attractive for gas separations. This work conducted a critical review of the latest development of MMMs based on advanced filler functionalization strategies, and their performances and stabilities under different operating conditions related to pressure, temperature, and feed gas impurities. Moreover, the upscaling and techno-economic feasibility of MMMs for industrial applications in postcombustion carbon capture, natural gas sweetening, biogas upgrading, hydrogen purification and olefin/paraffin separation were systematically discussed. Advanced MMMs developed at higher technology readiness levels are still challenging to meet their industrial gas separations. Herein, we present the latest ideas for improving fillers for MMMs and optimizing process design with regard to enhancing material properties and process efficiency. These concepts are expected to be implemented in next-generation MMMs to achieve high separation performance.