Divergent Adsorption Regulation in Metal–Organic Frameworks for Highly Efficient CF4/C2F6 Separation

The efficient removal of low-concentration components from homologous mixtures is often hampered by the co-directional effect of traditional thermodynamic regulation approaches, typically leading to a trade-off between adsorption capacity and selectivity. Focusing this challenge on the critical task of purifying perfluorocarbons in electronics industry, a divergent regulation strategy is reported that significantly improves the separation efficiency of low-concentration hexafluoroethane (C₂F₆) from tetrafluoromethane (CF₄). This approach involves the selective shielding of open metal sites and the modulation of channel geometry within an electron-deficient ligand-based pore environment, thereby facilitating a C₂F₆ dense-packing accommodation mode while weakening the CF₄ affinity due to the reduced host-guest interactions. Simultaneously enhanced C₂F₆ adsorption and reduced CF₄ adsorption are achieved, resulting in record-high low-pressure C₂F₆ uptake and C₂F₆/CF₄ selectivity. Comprehensive insights into the unique separation mechanism are illustrated through a combination of solid-state MAS nuclear magnetic resonance (SSNMR), molecular simulations, and meticulously designed comparative experiments. As a result, benchmark C₂F₆/CF₄ separation performance is achieved, as demonstrated by the unprecedented electronic-grade (over 99.999%) CF₄ productivity (401 L kg^-1) obtained from an industrially relevant C₂F₆/CF₄ (3:97) mixture, as well as the excellent water/air/heat stability and recyclability.