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.