Gas Adsorption Capability of Hybrid Polymers with Modifi ed Cyclodextrin-amorphous Silica

Abstract

Cyclodextrins (CDs) are well-known macrocyclic compounds in the fields of supramolecular and molecular recognition. For use as separation and adsorption materials, the water-soluble CDs must be modified into solid forms. Hybrid polymers consisting of amorphous silica and modified α- or β-CDs (propyl-modified α-CD, butyl-modified β-CD, and ethylenediamine modified-βCD), designated as propyl-α-CDP (2), butyl-β-CDP (3), and EDA-β-CDP (4), respectively, were prepared, and their adsorption capacities for CO₂, CH₄, and H₂ were evaluated. The α-CDP (1), which was derived from α-CD shows no adsorption capability for all gases examined. On the other hand, compound 2 exhibited the maximum CO₂ adsorption of about 18.0 ml at ～500 kPa. Compound 4 adsorbed the maximum amounts of CH₄ and H₂ (about 7.5 and 4.0 ml, respectively). In contrast, the 3 demonstrated almost no adsorption capability for CH₄ or H₂ molecules, adsorbing only CO₂ gas.