Topology-Oriented Assembly of Iron-2,5-Furandicarboxylate Coordination Cubes for Highly Selective CO2/SF6/N2 Capture.

As typical greenhouse gases, selective capture of CO2 (carbon dioxide) and SF6 (sulfur hexafluoride) is of great importance. Herein, on the basis of a typical six-connected pcu topology, three isomorphic Fe-2,5-furandicarboxylate (Fe-FDC) metal-organic framework (MOF) adsorbents (SNNU-133-135) were successfully prepared via a rational assembly of {[Fe3O]8(FDC)12} cubic building blocks. With dihedral angles in Fe-FDC cubes varying from 80° (SNNU-133), 87° (SNNU-134), to 90°(SNNU-135), three MOF isomers show step-by-step enhancement of selective CO2 and SF6 capture performance. For SNNU-135, at 298 K and 1 bar, the adsorption capacities for CO2 and SF6 are 83.6 and 66.7 cm3/g, and the CO2/N2 and SF6/N2 selectivity values are up to 29.4 and 509.1, respectively. Furthermore, the practical breakthrough interval time of SNNU-135 can reach 75 and 185 min g-1 (298 K, 1 bar, 1 mL min-1, CO2/N2 = 15:85 and SF6/N2 = 10:90) with the captured CO2 and SF6 amounts of 1.24 and 2.34 mmol/g, and the SF6 purity greater than 99.9%. The most regular Fe-FDC cubes, all available Fe-OMSs together with multiple weak interactions, cause SNNU-135 to have the highest CO2 and SF6 adsorption capacity, best CO2/N2 and SF6/N2 selectivity performance, and one-step separation ability for CO2/SF6/N2 ternary mixtures.