Immobilization of Oxygen Atoms in the Pores of Microporous Metal–Organic Frameworks for C₂H₂ Separation and Purification

The development of porous metal–organic framework (MOF) solids displaying efficient separation and purification of acetylene is of cardinal significance but challenging in the chemical industry. Among the reported MOFs for such a purpose, there usually exists an issue associated with trade-off between the uptake capacity and adsorption selectivity. In this work, we employed an N-oxide-functionalized dicarboxylate ligand to successfully construct under suitable solvothermal conditions a dicopper paddlewheel-based MOF featuring two different types of nanocages and rich open oxygen atoms on the channel surface. These structural features endow the material with the promising potential for C₂H₂ recovery from CO₂ and CH₄ at ambient conditions with impressive adsorption selectivity of C₂H₂ over CO₂ and CH₄ as well as considerable C₂H₂ capture capacity, which have been validated by isotherm measurements, ideal adsorbed solution theory calculations, and breakthrough experiments. Furthermore, molecular modeling studies revealed the vital role that the oxygen atoms coming from both N-oxide moieties and carboxylate groups play in selectively recognizing C₂H₂ over CO₂ and CH₄.