Stable SIFSIX-3-Ni NanoMOF Enabled Green Capture and Circular Utilization of CO2/CF4/C2F6: A Carbon-Neutral Strategy for Aluminum Electrolysis Emission Control

The aluminum electrolysis industry generates massive greenhouse gas emissions dominated by CO₂ and perfluorocarbons (PFCs, CF₄/C₂F₆), presenting dual challenges of climate impact and resource waste. Here, we report a robust nickel-based metal–organic framework (SIFSIX-3-Ni) featuring confined square channels (3.55 Å) that achieves the molecular-sieving separation of CO₂ from CF₄/C₂F₆ mixtures. Unlike conventional adsorbents, this MOF exhibits exceptional CO₂ selectivity (>10⁵ IAST) through precise size exclusion and strong quadrupole interactions with CO₂ by proximal fluorine arrays. Breakthrough experiments validate its molecular-sieving capability across varying gas compositions (CO₂: 50–80 vol %), with 40–65 min g^–1 CO₂ retention times enabling direct CF₄/C₂F₆ enrichment. The enriched CF₄/C₂F₆ was subjected to an aspen distillation simulation to obtain 99.99% CF₄ and C₂F₆. Crucially, the synthetic MOF demonstrates remarkable stability under corrosive HF exposure and maintains a 100% CO₂ adsorption capacity over five temperature-swing cycles. This work establishes a paradigm for simultaneous carbon capture and high-value PFC recovery in advancing sustainable aluminum electrolysis off-gas utilization.