Features of ESR spectra of copper-containing cation-decationized zeolites

The authors report on a study of Cu-containing Y zeolites, both dealuminized and nondealuminized, in which the Cu had been introduced by ion exchange, by impregnation, or by simultaneous ions exchange and impregnation. CuY zeolites differ in the type of stabilization of copper ions, depending on the quantity of copper introduced. At low concentrations, the copper is stabilized in the form of isolated ions, and these ions do not interact with pyridine molecules. At high concentrations, the copper is stabilized in the form of isolated ions, and these ions do not interact with pyridine molecules. At high concentrations, the copper ions are stabilized in clusters on the surface or in the large void spaces of the zeolite.