Hydrogen-Bonded Ultrathin Porous Polyamide Membrane for High Flux H₂/CO₂ Separation

High-performance polymer-based H2/CO2 separation membranes are attractive for sustainable blue hydrogen production. However, achieving high-flux separation remains a challenge, as H2 and CO2 have similar diffusion rates within the polymer. In this work, hydrogen-bonded polyamide (PA) network membranes are synthesized through interfacial polymerization involving Tröger’s base diamine (TBDA) and 1,3,5-benzenetricarbonyl trichloride, aiming to enhance the efficiency of H2/CO2 separation. Incorporating the contorted TBDA unit into the PA structure enhances microporosity, which, in turn, boosts the H2 permeance of the PA membrane. Notably, the presence of numerous intermolecular hydrogen bonds between N atoms in the TBDA and H atoms in the amide groups helps to restrict the pore size further, thereby improving the H2/CO2 selectivity of the membrane. The resulting PA membrane demonstrates an outstanding H2/CO2 selectivity of 23.5, coupled with a high H2 permeance of 160 gas permeation unit (GPU), significantly exceeding the current upper bound. Additionally, our PA membranes maintain a stable H2/CO2 selectivity of approximately 21.5 and a H2 permeance of around 160 GPU over 100 h, indicating excellent long-term stability. These findings suggest that the development of such advanced polymer membranes could pave the way for more efficient and sustainable blue hydrogen production, overcoming existing limitations in gas separation technologies.