Pore Environmental Modification by Amino Groups in Robust Microporous MOFs for SF₆ Capturing and SF₆/N₂ Separation

Capturing and separating the greenhouse gas SF₆ from nitrogen N₂ have significant greenhouse mitigation potential and economic benefits. We used a pore engineering strategy to manipulate the pore environment of the metal-organic framework (MOF) by incorporating organic functional groups (-NH₂). This resulted in an enhanced adsorption of SF₆ and separation of the SF₆/N₂ mixture in the MOF. The introduction of amino (-NH₂) groups into YTU-29 resulted in a reduction of the Brunauer-Emmett-Teller surface but an increase in interactions with SF₆ within the confined pores. Water-stable YTU-29-NH₂ showed a significantly higher SF₆ uptake (95.5 cm³/g) than YTU-29 (77.4 cm³/g). The results of the breakthrough experiments show that YTU-29-NH₂ has a significantly improved separation performance for SF₆/N₂ mixtures, with a high SF₆ capture of 0.88 mmol/g compared to 0.56 mmol/g by YTU-29. This improvement is due to the suitable pore confinement and accessible -NH₂ groups on pore surfaces. Considering its excellent regeneration ability and cycling performance, ultrastable YTU-29-NH₂ demonstrates great potential for SF₆ capturing and SF₆/N₂ separation.