Abstract
The removal of carbon dioxide from fuel gases and N-2-rich flue gas are critical for chemical energy industry, and reduction of carbon emission. Adsorptive size-sieving based gas separation is highly desired to maximize the separation efficiency but rarely reported. Herein, an ultra-microporous metal-organic framework built from copper(II) and 5-fluoropyrimidin-2-olate, termed as Cu-F-pymo, has been studied for the separation of CO2 from CH4 and N-2. Cu-F-pymo can exclusively capture CO2 over CH4 and N-2 with significant high IAST selectivity (> 107) and a high adsorption capacity of 69.2 cm(3) cm(-3). Such molecular size-sieving effect is attributed to the small pore size of Cu-F-pymo (similar to 3.3 angstrom), which can only allow the diffusion of CO2. The oxygen moieties decorated on the channel surface enforced the binding affinity toward CO2 through electrostatic and hydrogen bonding interactions as confirmed by molecular simulation studies. The outstanding size-sieving CO2 separation performance was further confirmed by cycling column breakthrough tests, which demonstrated the dynamic CO2 capture capacity of 1078 mmol kg(-1) and 941 mmol kg(-1) for CO2/CH4 (50:50), CO2/N-2(15:85) mixtures, respectively. More importantly, the mild regeneration feature of Cu-F-pymo underlies its potentials for practical carbon capture applications.