Efficient C2H2/CO2 separation in anion-functionalized metal–organic framework with high C2H2 packing density

The development of high-performance porous adsorbents for the efficient recovery of C 2 H 2 from C 2 H 2 /CO 2 mixtures holds significant industrial value. However, the separation of C 2 H 2 /CO 2 remains highly challenging due to their similarities in physicochemical properties. To tackle this key obstacle, we utilize a feasible fluorinated anion modulation strategy to optimize the negative electrostatic microenvironment of ultra-microporous MOFs for the preferential recognition of C 2 H 2 . Notably, compared to SIFSIX-dpds-Cu, TIFSIX-dpds-Cu exhibits higher C 2 H 2 uptake (81.0 cm 3  g −1 ) and C 2 H 2 /CO 2 selectivity (43.2). Furthermore, the C 2 H 2 packing density of TIFSIX-dpds-Cu can reach 522 g L −1 , outperforming most previously reported materials. Density functional theory calculations and in situ FT-IR spectra collaboratively demonstrate that the multiple C−H···F and C−H···C interactions are formed between TIFSIX-dpds-Cu and C 2 H 2 molecules. With the synergistic drive of multiple hydrogen bonds and van der Waals forces within the confined pores, ultimately achieving efficient C 2 H 2 purification. Breakthrough experiments reveal that TIFSIX-dpds-Cu achieves complete separation of C 2 H 2 /CO 2 mixtures, yielding the high-purity C 2 H 2 productivity (≥99.5 %) of 58.42 cm 3  g −1 in a single adsorption−desorption cycle.