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

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.