Recent Advances in Carbon Dioxide Separation Membranes: A Review

Separation membranes, which have the possibility to develop energy-saving and compact processes, are expected to be applied in the field of CO2 separation and capture and are attracting considerable interest from both industries and academia. The purpose of this review is to provide an overview of recent advances in both organic and inorganic materials for high-performance CO2 separation membranes from the viewpoint of molecular design to an engineering perspective. The overview includes gas permeation theory for CO2 capture and separation, controlled intrinsic micropores and their size-sieving property, CO2 diffusivity in the membrane matrix, selective CO2 solubility and selective permeability, functionalization using chemical reactions, etc. CO2 separation mechanisms and the effects of properties of membrane materials on both the CO2 permeability and permselectivity over other light gases are discussed, and the recent developments regarding inorganic and glassy polymer membranes with intrinsic microporous structures, rubbery polymer membranes, ionic liquid-based gel membranes, and facilitated-transport membranes are reviewed. Taking into consideration the industrial applications, the characteristics of each membrane with respect to process design, such as membrane thickness, and physical aging, and dependence of CO2 permeability on gas properties, are also discussed. Finally, future research challenges and perspectives for the commercialization of CO2 capture and separation process using high-performance materials are proposed.