Recovery of High-Purity SF6 from Humid SF6/N2 Mixture within a Co(II)-Pyrazolate Framework

Sulfur hexafluoride (SF₆) is extensively employed in the power industry. However, its emissions significantly contribute to the greenhouse effect. The direct recovery of high purity SF₆ from industrial waste gases would benefit its sustainable use, yet this represents a considerable challenge. Herein, we report the enrichment of SF₆ from SF₆/N₂ mixtures via adsorptive separation in a stable Co(II)-pyrazolate MOF BUT-53 (BUT: Beijing University of Technology), which features dynamic molecular traps. BUT-53 exhibits an excellent SF₆ adsorption uptake of 2.82 mmol/g at 0.1 bar and 298 K, as well as an unprecedented SF₆/N₂ (10:90) selectivity of 2485. Besides, the remarkable SF₆/N₂ selectivity of BUT-53 enables recovery of high purity (>99.9%) SF₆ from a low concentration (10%) mixture through a breakthrough experiment. The excellent SF₆/N₂ separation efficiency was also well maintained under humid conditions (RH = 90%) over multiple cycles. Molecular simulation, single-crystal diffraction, and adsorption kinetics studies elucidate the associated adsorption mechanism and water tolerance.