Application of ionic liquids in the mixed matrix membranes for CO2 separation: An overview

•Advances of IL-based MMMs for CO2 separation were comprehensively overviewed.•Roles of ILs applied in MMMs for fabrication and CO2 separation were presented.•Effects of ILs on the interfacial morphology and property of MMMs were discussed.•Future perspectives on IL-based MMMs for CO2 separation were proposed. Membrane technology is highly promising in CO2 capture and separation process mainly because of its energy-efficiency and environmental friendliness. Mixed matrix membranes (MMMs) combine the excellent gas separation performance of fillers and the processability of polymer matrix, but it is still a challenge to enhance the gas separation performance for practical application. In this review, ionic liquids (ILs)-based MMMs with modified microstructures and improved separation performance are systematically introduced, which mainly due to the adjustability, the role of wetting agents, as well as the high CO2 affinity of ILs. The development of conventional ILs and functionalized ILs for CO2 separation are first briefly presented, following by the advance of ILs/fillers/polymers blended MMMs, ILs@fillers/polymers MMMs, ILs/fillers/PILs MMMs, and MMMs post-treated with ILs for CO2 separation. Meanwhile, the effects of ILs on the interfacial morphology, membranes microstructures and CO2 separation performance of membranes are emphasized. Finally, the understandings of challenges and perspectives of IL-based MMMs are proposed.