Pore-Structure Control in Metal–Organic Frameworks (MOFs) for Capture of the Greenhouse Gas SF₆ with Record Separation

In the electronics industry, the efficient recovery and capture of sulfur hexafluoride (SF₆) from SF₆/N₂ mixtures is of great importance. Herein, three metal–organic frameworks with fine-tuning pore structures, Cu(peba)₂, Ni(pba)₂, and Ni(ina)₂, were designed for SF₆ capture. Among them, Ni(ina)₂ has perfect pore sizes (6 Å) that are comparable to the kinetic diameter of sulfur hexafluoride (5.2 Å), affording the benchmark binding affinity for SF₆ gas. Ni(ina)₂ exhibits the highest SF₆/N₂ selectivity (375.1 at 298 K and 1 bar) and ultra-high SF₆ uptake capacity (53.5 cm³ g⁻¹ at 298 K and 0.1 bar) at ambient conditions. The remarkable separation performance of Ni(ina)₂ was verified by dynamic breakthrough experiments. Theoretical calculations and the SF₆-loaded single-crystal structure provided critical insight into the adsorption/separation mechanism. This porous coordination network has the potential to be used in industrial applications.