Radiation‐Resistant Kr‐Selective MOF With Record Kr/Xe Selectivity at Elevated Pressure

ABSTRACT The separation of Kr/Xe from spent nuclear fuel off‐gas is critical, yet most current adsorbents exhibit Xe‐Kr co‐adsorption under elevated pressures, posing challenges for industrial pressure swing adsorption processes. Herein, we present and evaluate a metal‐organic framework, CALF‐20M‐w, engineered for molecular sieving separation of Kr/Xe under industrial pressure conditions. CALF‐20M‐w possesses a pore size of 3.7 Å, which position between Kr (3.6 Å) and Xe (4.1 Å) kinetic diameters, enables record Kr/Xe uptake ratio (52.2) and selectivity of 4424 at 195 K and 5 bar, surpassing all benchmark materials. GCMC simulations reveal that Kr atoms occupy favorable positions within CALF‐20M‐w's intersecting channels, while Xe atoms are sterically excluded in the pressure range of 1–30 bar. Dynamic breakthrough separation experiments and PSA simulation show CALF‐20M‐w can yield >99.9% pure Xe, demonstrating feasibility for radioactive Kr removal from spent nuclear fuel off‐gases. Moreover, CALF‐20M‐w exhibits extreme radiation resistance under β‐irradiation (72 kGy/h) and γ‐irradiation (240 kGy), outperforming UiO‐66 and ZIF‐8. CALF‐20M‐w sets new benchmarks for high‐pressure molecular sieving in Kr/Xe separation, offering a highly promising strategy for nuclear waste management and rare gas purification.