Precise syngas ratio control is crucial for efficiently producing high-quality clean fuels such as naphtha, kerosene, and diesel. In light of the rising demand for energy-efficient hydrogen separation, this study investigates the H₂/CO separation performance of novel benzimidazole-linked polymer (BILP-101x) and poly(p-phenylene benzobisimidazole) (PBDI) membranes fabricated via a simple interfacial polymerization process. The effects of temperature, pressure, and H₂ molar fraction on the membranes' separation performance were comprehensively evaluated. Both membranes displayed high H2 permeance (BILP-101x∼136 GPU; PBDI∼76 GPU) and selectivity (BILP-101x∼78; PBDI∼50) for H2/CO separation at 150 °C. The superior H₂ permeance of BILP-101x was attributed to its higher fractional free volume and diffusion coefficients compared to PBDI, as confirmed by molecular simulations. Notably, both membranes demonstrated remarkable stability during long-term testing under simulated syngas conditions (50/25/25H₂/CO₂/CO, 100 °C for 120 h), outperforming most polymeric membranes reported in literature for H2/CO separation. The superior H2/CO separation performance coupled with the excellent stability (over 120 h) endows BILP-101x and PBDI membranes with an attractive application prospect for industrial syngas ratio adjustment.@en

Separation of hydrogen from carbon dioxide for sustainable H₂ production and CO₂ capture still faces great challenges due to the smaller size of H₂ and higher condensability of CO₂. Herein, a high-performance benzimidazole-linked polymer (BILP) membrane for hydrogen separation was directly prepared on α-Al₂O₃ substrate through a facile interfacial polymerization approach at room temperature. The separation performance of the BILP membrane were regulated by controlling the reaction time and the microstructure was systematically characterized. Molecular simulations were performed to deep understand the separation mechanism in the BILP membrane. The best performance membrane displays an extraordinary mixed gas selectivity of 40 for H₂/CO₂ together with outstanding H₂ permeance of 250 gas permeation units (GPU) at 473 K, far exceeding the Robeson's upper bound. Besides, the membrane can withstand high temperature and pressure, and also shows good H₂/N₂ and H₂/CH₄ selectivity. The excellent separation performance, coupled with high temperature and pressure resistance and easy preparation, render BILP membranes great potential for economic H₂ purification, H₂ recovery, and natural gas treatment.

@en