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

Abstract

The combination of a properly designed organic linker, 3,6-N-ditriazolyl-2,5-dihydroxy-1,4-benzoquinone (trz₂An), with Co^II ions results in a novel 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 Co^II ions linked through anilato ligands at the equatorial positions and triazole substituents from two neighbouring chains at 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 entry of CO₂ but not of molecules with larger kinetic diameters such as N₂ or CH₄. 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 under mild conditions.