Acid-Catalyzed Interfacial Polymerization of a Benzimidazole-Linked Polymer Membrane for Efficient H₂/CO₂ Separation

The development of cost-effective and energy-efficient membrane materials is of significant importance for the purification of hydrogen and the capture of carbon dioxide. Given the potential of benzimidazole-linked polymers (BILPs) for H2/CO2 separation, this study aimed to synthesize a novel BILP membrane material (BILP-x) through an acid-catalyzed interfacial polymerization strategy. The BILP-x membranes achieved an exceptional H2 permeance of 176.6 GPU and a H2/CO2 selectivity of 12.3 at room temperature. Decreasing the BTA concentration can significantly increase the H2 permeance to 987.6 GPU, while the H2/CO2 selectivity decreased to 8.0 at room temperature. In addition, the BILP-x membrane demonstrated exceptional long-term stability in H2/CO2 separation, maintaining its performance for up to 300 h under alternating temperatures of 373 and 423 K. Meanwhile, the molecular dynamics simulations verified that the addition of acid accelerated the diffusion rate of TP molecules in the interfacial polymerization reaction, resulting in the formation of denser membranes. The finding not only validates the promise of BILP-x membranes for H2/CO2 separation, but also opens up a new avenue for the development of high-performance membrane materials for a range of separation applications.