Current Progress on Dual-Layer Hollow Fiber Mixed-Matrix Membrane in CO2 Capture

Carbon dioxide (CO₂) is a greenhouse gas which is mainly found in natural gas (NG), biogas, and flue gas. Anthropogenic CO₂ emissions are the direct result of burning fossil fuels. Meanwhile, pre- and postcombustion CO₂ separation is a current state of CO₂ removal method in an extensive manner. From environmental, economic, and transportation perspectives, removal of CO₂ has driven the development of its separation process technology. Among the reported technologies, membrane-based gas separation technologies have grown substantially, breakthroughs and advances in past decades. This review paper aims to provide an overview on competitive gas separation processes, different types of membranes available, gas transport mechanisms, and fabrication process of hollow fiber membranes, particularly dual-layer hollow fiber membrane. The performance of the membranes in CO₂ separation and effect of spinning parameters on the formation of hollow fiber membranes are highlighted. In addition, approaches to improve the dual-layer adhesion, strategies to enhance the filler compatibility in the development of dual-layer hollow fiber mixed-matrix membranes, and effect of post-treatments on the gas separation performance of membrane are also discussed. Finally, challenges and future perspectives of dual-layer hollow fiber mixed-matrix membranes toward CO₂ capture, particularly on CO₂/CH₄ and CO₂/N₂ separation, are also included, due to its substantial and direct relevance to the gas separation industry.