Determination of the basicity of alkali-exchanged molecular sieves

Abstract

A procedure is proposed to quantify the basicity of zeolite oxygen centers by estimating the proton affinity (PA) of these centers, employing measured IR frequency shifts of the stretching and deformation modes of the OH group of adsorbed methanol. The PA scale is established with the help of density functional theory (DFT) calculated PA values of selected zeolites calibrated to the experimental gas phase PA of small oxygen-containing molecules. The reliability of the method is increased by combining two experimental parameters.