A thermally/chemically robust and easily regenerable anilato-based ultramicroporous 3D MOF for CO2 uptake and separation

The combination of the properly designed novel organic linker, 3,6-N-ditriazoyil-2,5-dihydroxy-1,4-benzoquinone (trz2An), with CoII ions results in a 3D ultramicroporous MOF with high CO2 uptake capacity and separation efficiency, with particular attention to CO2/N2 and CO2/CH4 gas mixtures. This material consists of 1D chains of octahedrally coordinated CoII ions linked through the anilato ligands in the equatorial positions and to the triazole substituents from two neighbouring chains in the two axial positions. This leads to a 3D microporous structure with voids with an affinity for CO2 molecules and channels that enable the selective entrance of CO2 but not of molecules with larger kinetic diameter such as N2 or CH4. The adsorption studies revealed that i) the MOF presents a remarkable carbon dioxide uptake, above 20% in weight; ii) CO2 adsorptive separation is successfully performed in CO2:N2 and CO2:CH4 gas mixtures, exhibiting high selectivity in a large operation range; iii) regeneration is easily achieved at mild conditions.