Metal–Organic Framework with Rich Accessible Nitrogen Sites for Highly Efficient CO2 Capture and Separation

A novel microporous metal–organic framework (FJU-44), with abundant accessible nitrogen sites on its internal surface, was constructed from the tetrapodal tetrazole ligand tetrakis­(4-tetrazolylphenyl)­ethylene (H4TTPE) and copper chloride. Notably, the CO2 uptake capacity (83.4 cm3/g, at 273 K and 1 bar) in the activated FJU-44a is higher than most of tetrazolate-containing MOF materials. Particularly, FJU-44a exhibits superior adsorption selectivity of CO2/N2 (278–128) and CO2/CH4 (44–16), which is comparable to some well-known CO2 capture materials. Furthermore, the fixed-bed breakthrough experiment indicates that the postcombustion flue gas flow over a packed column with FJU-44a adsorbents can be effectively separated.