Hierarchically Structured HKUST-1 Nanocrystals for Enhanced SF₆ Capture and Recovery

Abstract

HKUST-1, an inexpensive metal–organic framework possessing open metal sites, has a great potential for capture and recovery of SF6. In this work, the structural property of HKUST-1 was modified to yield a hierarchically structured HKUST-1 nanocrystal exhibiting a superior performance with higher SF6 uptake (4.98 mmol g–1 at 25 °C and 1 bar), better SF6/N2 selectivity (∼70 at 25 °C), faster SF6 adsorpton kinetics, and lower energy penalty for regeneration compared to those of bulk HKUST-1 crystal as well as those of conventional zeolite and porous carbon adsorbents. Higher surface area and the presence of mesoporosity to facilitate the transport of SF6 to active sites residing in microporous spaces were found to be key factors contributing to such enhancement. The outstanding potential utility of our HKUST-1 crystal in industrial applications was also validated with an idealized vacuum swing adsorption model.