Surface modification induced enhanced CO₂ sorption in cucurbit[6]uril, an organic porous material

Abstract

The CO₂ adsorption properties of an organic macrocycle, cucurbit[6]uril (CB[6]), have been evaluated through experimental and theoretical studies. Quantum mechanical calculations show that CB[6] is capable of adsorbing the CO₂ molecule selectively within its cavity relative to nitrogen. Adsorption experiments at 298 K and at 1 bar pressure gave a CO₂ adsorption value of 1.23 mmol g^-1 for the unmodified material. Significant enhancements in the CO₂ adsorption capacity of the material were experimentally demonstrated through surface modification using physical and chemical methods. Ethanolamine (EA) modified CB[6] provided an excellent sorption selectivity value of 121.4 for CO₂/N₂ at 323 K and is unique with respect to its discrimination potential between CO₂ and N₂. The chemical nature of the interaction between CO₂ and amine is shown to be the primary mechanism for the enhanced CO₂ absorption performance.