Selective Capture of Trifluoromethane from Nitrogen Using a Scalable Ultramicroporous Nickel-Based Metal–Organic Framework

Abstract

Trifluoromethane (CHF3) is a potent greenhouse gas and a useful industrial feedstock, and its selective capture from N2-rich streams is relevant to both emission control and resource recovery. Here, we investigate the ultramicroporous nickel-based metal–organic framework Ni-ina for CHF3/N2 separation (ina = isonicotinic acid). Ni-ina, synthesized by a scalable modified hydrothermal method, has a pore size of about 0.6 nm, well matched to the kinetic diameter of CHF3 (0.46 nm). It exhibits a CHF3 uptake of 3.58 mmol g–1 at 298 K and 10 kPa, with much lower N2 uptake. The value is, to our knowledge, the highest reported for MOF under identical conditions. The ideal adsorbed solution theory (IAST)-predicted selectivity for a CHF3/N2 mixture (10:90, v/v) is 127 at 298 K and 100 kPa. Grand canonical Monte Carlo (GCMC) simulations and breakthrough experiments confirm preferential CHF3 adsorption and regenerable separation performance. These results identify Ni-ina as a promising adsorbent for CHF3 capture from N2-rich streams.