Construction of an Al-Based MOF with Methyl-Functionalized Microporous Nano-Traps for Efficient Separation of SF₆/N₂

Sulfur hexafluoride (SF₆) is indispensable to the power industry, yet its emission requires strict control due to the potent greenhouse effect. The direct recovery of high-purity SF₆ from industrial waste gas is vital for sustainable use but remains a formidable challenge. Herein, we report NU-62, an Al-MOF featuring methyl-functionalized microporous nano-traps, engineered by employing a hexacarboxylate ligand with three methyl groups on its backbone and two types of unusual 4-connected trinuclear Al clusters coordinated with formates and acetates. Leveraging the tailored pore environments, NU-62 exhibited a high SF₆ uptake of 3.99 mmol g^-1 and an outstanding SF₆/N₂ (10:90, v/v) selectivity of 209 at 298 K and 1 bar, achieving highly selective SF₆ capture from SF₆/N₂ mixture. Furthermore, breakthrough experiments confirm its efficient separation for an SF₆/N₂ mixture, with good performance retained even under 70% relative humidity. Theoretical calculations suggest that SF₆ is preferentially adsorbed in the methyl-functionalized nano-traps through multiple C─H···F hydrogen bonding interactions. This work demonstrates the great potential of methyl-functionalized pore engineering in enabling energy-efficient and sustainable SF₆ recovery for industrial applications.