Diamine-Crosslinked and Blended Polyimide Membranes: An Emerging Strategy in Enhancing H2/CO2 Separation

The increasing demand for high-purity hydrogen (H2) as renewable energy sources is driving advancements in membrane technology, which is essential for achieving efficient gas separation. Polyimide (PI) membranes have become an emerging option for H2/CO2 separation due to its excellent thermal stability and stability under harsh conditions. However, the neat PI membrane suffers performance loss due to CO2 plasticization effect and an encountered trade-off limit between permeability and selectivity. Therefore, membrane modification by crosslinking and blending emerged as a recent strategy to enhance the membrane's performance and properties. This paper provides: (1) An overview of the possible method to do the modification in PI membranes, including the advantages and challenges of the membrane modification types; (2) As blending and crosslinking is the most popular modification for the PI membrane, their roles in enhancing membrane properties for improved H2/CO2 separation are discussed; (3) The critical parameters of the blending and crosslinking processes are also clarified for the optimal purification process; (4) The future outlook for H2/CO2 separation using membrane technology is discussed, aiming to provide commercialization strategy for optimal H2/CO2 separation. Thus, this review could provide guidelines for the readers to implement changes that significantly enhance the membrane's features for high-purity H2 production.