Optimizing Pore Size and Polarity in Halogen-Functionalized Metal–Organic Frameworks for Efficient Xenon/Krypton Separation: A Synergistic Strategy

High-purity xenon (Xe) is crucial in semiconductor manufacturing and medical imaging, but trace krypton (Kr) in Xe poses a significant challenge in separation due to their highly similar properties. Traditional gas separation methods are ineffective for Xe/Kr, necessitating innovative adsorbent materials. This study proposes an effective strategy using halogen-functionalized ligands to adjust the pore size and polarity in metal–organic framework (MOF) materials, achieving efficient Xe/Kr separation. A series of MOFs (LIFM-DMOF-X 1, X = F, Cl, Br, I) were designed to simultaneously control pore size and wall polarity. Experimental results show that LIFM-DMOF-Cl 1 and LIFM-DMOF-Br 1 exhibit excellent adsorption performance and selectivity for Xe/Kr. Theoretical calculations confirm stronger Xe interactions with MOF C–H groups and halogen atoms, validating the structure–property relationship. This approach provides a synergistic strategy for developing particular gas separation materials for Xe/Kr.