Metal-Organic Framework-Based Single-Molecule SF6 Trap for Record SF6 Capture

Pursuing best-performing porous adsorbents to realize an effective SF6 recovery from SF6/N2 blends is of pronounced industrial worth. To tackle this key obstacle, we propose a single-molecule SF6 trap, which is based upon a splint-like pore in a highly stable metal-organic framework Ni(adc)(dabco)0.5 through multipoint F center dot center dot center dot pi affinity. The pore walls are decorated with oppositely parallel anthracene rings, and the overlapping region of anthracene rings forms a giant overlap of potential fields. This very strong SF6 trap presents a record initial isosteric heat of adsorption (47.6 kJ mol-1), Henry constant (285.0 mmol g-1 bar-1), and uptake (2.23 mmol g-1) for SF6, making it a new benchmark with an unexampled ideal selectivity (919.4) toward SF6 capture. The SF6 adsorption mechanism within the Ni(adc)(dabco)0.5-based single-molecule trap is identified via in situ powder X-ray diffraction and Fourier transform infrared reflection spectroscopy in conjunction with theoretical studies. The highest selectivity (948.2), SF6 breakthrough uptake (2.1 mmol g-1), and dimensionless time (481.6) with the breakthrough effect of complete separation further consolidated that this MOF-based single-molecule SF6 trap is a novel state-of-the-art candidate toward SF6/N2 separation.