Highly selective adsorption of SF6 over N2 in a bromine-functionalized zirconium-based metal-organic framework

We have systematically synthesized a series of functionalized UiO-66-X (X = NO2, NH2, Cl, Br, I, Br-2) compounds to further improve the selective SF6 adsorption of UiO-66, which is one of the best-performing adsorbents, and to investigate the effect of the polarizability of adsorbent atoms on the SF6 and CF4 adsorption, especially at low pressures, which is the industrially relevant condition. UiO-66-Br-2 with the highest polarizability exhibited a high Henry's constant (104 mmol g(-1) bar(-1)) for SF6 adsorption as well as high SF6/N-2 selectivity (200), both of which are considerably higher than those of other adsorbent materials, including MOFs. Moreover, UiO-66-Br-2 showed good SF6/N-2 separation under a dynamic mixture flow condition as well as facile regeneration without increasing the temperature. These results show that UiO-66-Br-2 is a potential adsorbent for the selective capture of SF6 from various SF6/N-2 mixtures in industry.