Engineering Polymeric Membranes for CO₂ Separation: Materials, Fabrication, Challenges, and Future Perspectives

ABSTRACT Carbon dioxide (CO₂) emissions from anthropogenic sources are major contributors to global warming and climate change, necessitating efficient separation from gas mixtures for mitigation and utilization. Polymeric membranes have emerged as a promising alternative to conventional CO₂ separation technologies, such as amine absorption and cryogenic distillation, due to their lower energy consumption, modular design, and operational simplicity. Recent advances suggest that membrane‐based systems can reduce energy penalties while offering scalable solutions for carbon capture and storage (CCS), natural gas purification, and biogas upgrading. This review highlights that advanced polymeric membrane materials, particularly polymers of intrinsic microporosity (PIMs) and mixed‐matrix membranes (MMMs), have demonstrated substantial improvements in CO₂ permeability while maintaining competitive selectivity. This reflects significant progress toward overcoming the traditional permeability−selectivity trade‐off. Compared to conventional technologies, membranes offer operational and energy advantages, although challenges remain under high‐pressure and mixed‐gas conditions. Various membrane materials are discussed, including cellulose‐based membranes for low cost and biodegradability, polyimides for thermal and chemical stability, polybenzimidazole and polysulfone for mechanical strength, and rubbery polymers for high CO₂ permeability. The incorporation of inorganic fillers further enhances performance, though issues such as plasticization and aging remain critical barriers to large‐scale application. Fabrication approaches, particularly dense and thin‐film composite membranes, are also emphasized for their industrial relevance. Overall, this review provides a comprehensive assessment of recent material advancements, performance trends, and key challenges (plasticization, aging, and thermal stability), offering insights into the future development of high‐performance polymeric membranes for CO₂ separation.