A Moisture-Stable 3D Microporous Co^II -Metal-Organic Framework with Potential for Highly Selective CO₂ Separation...

Selective adsorption and separation of CO₂ from flue gas and landfill gas mixtures have drawn great attention in industry. Porous MOF materials are promising alternatives to achieve such separations; however, the stability in the presence of moisture must be taken into consideration. Herein, we have constructed a microporous metal-organic framework (MOF) {[Co(OBA)(L)_0.5 ]⋅S}_n (IITKGP-8), by employing a V-shaped organic linker with an azo-functionalized N,N' spacer forming a 3D network with mab topology and 1D rhombus-shaped channels along the crystallographic 'b' axis with a void volume of 34.2 %. The activated MOF reveals a moderate CO₂ uptake capacity of 55.4 and 26.5 cm³  g^-1 at 273 and 295 K/1 bar, respectively, whereas it takes up a significantly lower amount of CH₄ and N₂ under similar conditions and thus exhibits its potential for highly selective sorption of CO₂ with excellent IAST selectivity of CO₂ /N₂ (106 at 273 K and 43.7 at 295 K) and CO₂ /CH₄ (17.7 at 273 K and 17.1 at 295 K) under 1 bar. More importantly, this MOF exhibits excellent moisture stability as assessed through PXRD experiments coupled with surface area analysis.