A Theoretical Study on Interactions between Silica Gel and Adsorbed Molecules by using ab initio MO Method

Abstract

Gas-phase adsorptive interactions between adsorbates and silica gel are studied by using the ab initio molecular orbital (MO) method. As for adsorbates we have treated C2H4 and C6H6. A kind of adsorption site constructed by two silanol (≡Si-O-H) groups is considered, and the effect of a heterogeneous distribution of silanol groups on adsorption phenomena is discussed. The adsorption energies obtained by ab initio MO calculation are in good agreement with those obtained by experiments. For C2H4 and C6H6 the sites constructed by silanol groups act as adsorption sites but the sites constructed by siloxane (≡Si-O-Si≡) groups do not.