tert-Butyl Functionalized Ultra-Microporous Three-Dimensional Covalent Organic Framework for Efficient SF₆/N₂...

Efficient capture and recovery of sulfur hexafluoride (SF₆) from SF₆/N₂ mixtures is critical for mitigating greenhouse effects and promoting gas recycling in the electronics industry. Herein, we report a novel ultra-microporous three-dimensional covalent organic framework (COF), termed CPOF-12, enriched with tert-butyl groups. CPOF-12 exhibits a Brunauer-Emmett-Teller (BET) surface area of 1,140 m² g^-1, a pore volume of 0.66 cm³ g^-1, and a uniform pore size of 0.59 nm, which closely matches the kinetic diameter of SF₆ (0.52 nm). Gas adsorption measurements reveal a high SF₆ uptake of 2.20 mmol g^-1 at 298 K and 1 bar, along with an exceptional SF₆/N₂ selectivity of 149.4, calculated using ideal adsorbed solution theory (IAST). This study highlights the effectiveness of pore surface engineering in COFs for high-performance separation of greenhouse gases.