The advancements in mixed matrix membranes containing functionalized MOFs and 2D materials for CO2/N2 separation and CO2/CH4 separation

CO2 separation plays a crucial role in tackling the climate change induced by the greenhouse effects and improving the energy quality of natural gas and biogas. The efficient CO2 separation technology is highly required. Membrane separation technology is particularly attractive in CO2 separation processes owing to its advantages. However, the trade-off relationship limited the gas separation efficiency of polymeric membranes in gas separation processes. Therefore, it is necessary to prepare the high-performance membranes such as mixed matrix membranes (MMMs) for CO2 separation. This review mainly focuses on the preparation methods, the material properties and the CO2 separation efficiency of the MMMs containing various fillers such as modified ZIFs, MOFs, and GO, and the emerging MOF-based composites, 2D MOFs and 2D MXene. The modified fillers demonstrated higher compatibility with polymer matrix, resulting in enhanced mechanical stability and CO2 separation efficiency of MMMs. 2D materials could significantly enhance the CO2 separation efficiency of MMMs, owing to their layered structure and the effective regulation of gas transport ways. Finally, the future direction and conclusions of fillers and MMMs in gas separation processes are provided.