Construction of a Stable Crystalline Polyimide Porous Organic Framework for C₂ H₂ /C₂ H₄ and CO₂ /N₂ Separation

Utilization of porous materials for gas capture and separation is a hot research topic. Removal of acetylene (C₂ H₂ ) from ethylene (C₂ H₄ ) is important in the oil refining and petrochemical industries, since C₂ H₂ impurities deactivate the catalysts and terminate the polymerization of C₂ H₄ . Carbon dioxide (CO₂ ) emission from power plants contributes to global climate change and threatens the survival of life on this planet. Herein, 2D crystalline polyimide porous organic framework PAF-120, which was constructed by imidization of linear naphthalene-1,4,5,8-tetracarboxylic dianhydride and triangular 1,3,5-tris(4-aminophenyl)benzene, showed significant thermal and chemical stability. Low-pressure gas adsorption isotherms revealed that PAF-120 exhibits good selective adsorption of C₂ H₂ over C₂ H₄ and CO₂ over N₂ . At 298 K and 1 bar, its C₂ H₂ and CO₂ selectivities were predicted to be 4.1 and 68.7, respectively. More importantly, PAF-120 exhibits the highest selectivity for C₂ H₂ /C₂ H₄ separation among porous organic frameworks. Thus PAF-120 could be a suitable candidate for selective separation of C₂ H₂ over C₂ H₄ and CO₂ over N₂ .