A microporous MOF with a polar pore surface exhibiting excellent selective adsorption of CO from CO-N and CO-CH gas mixtures with high CO loading.

A microporous MOF {[Zn(SDB)(L)]·S} (IITKGP-5) with a polar pore surface has been constructed by the combination of a V-shaped -SO functionalized organic linker (HSDB = 4,4'-sulfonyldibenzoic acid) with an N-rich spacer (L = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene), forming a network with sql(2,6L1) topology. IITKGP-5 is characterized by TGA, PXRD and single crystal X-ray diffraction. The framework exhibits lozenge-shaped channels of an approximate size of 4.2 × 5.6 Å along the crystallographic b axis with a potential solvent accessible volume of 26%. The activated IITKGP-5a revealed a CO uptake capacity of 56.4 and 49 cm g at 273 K/1 atm and 295 K/1 atm, respectively. On the contrary, it takes up a much smaller amount of CH (17 cm g at 273 K and 13.6 cm g at 295 K) and N (5.5 cm g at 273 K; 4 cm g at 295 K) under 1 atm pressure exhibiting its potential for a highly selective adsorption of CO from flue gas as well as a landfill gas mixture. Based on the ideal adsorbed solution theory (IAST), a CO/N selectivity of 435.5 and a CO/CH selectivity of 151.6 have been realized at 273 K/100 kPa. The values at 295 K are 147.8 for CO/N and 23.8 for CO/CH gas mixtures under 100 kPa. In addition, this MOF nearly approaches the target values proposed for PSA and TSA processes for practical utility exhibiting its prospect for flue gas separation with a CO loading capacity of 2.04 mmol g.