Characterization of the Cu + sites in MFI zeolites: combined computational and experimental study

Abstract

The site-specificity of the CO probe molecule interaction with the Cu +/MFI system is investigated by a combination of experimental and theoretical techniques. Three Cu + site types differing in CO adsorption energies ( E ads) were identified. Based on a very good agreement of experimental and calculated E ads, the detail information about the structure and localization of Cu + sites in MFI, including information about the localization of framework Al atom can be obtained. The IR spectra of CO adsorbed on the same Cu +/MFI samples clearly shows that the CO stretching frequencies are not site-specific in Cu +/MFI system. This conclusion is supported by calculated CO frequencies that do not depend on the Cu + site type.