XPS Detection of Some Redox Phenomena in Cu-zeolites

X-ray photoelectron spectroscopy analysis of Cu 2p peaks is able to descriminate between Cu(II) and Cu(I). This is particularly useful when copper is supported in a zeolite matrix, as in heterogeneous catalysts. The preparation route, the Si/Al ratio and the kind of zeolite all contribute to determine the final oxidation state of copper. In turn, the oxidation state determines the effectiveness of the catalyst. Samples prepared via the gas phase and solution are considered in this work after calcination. Both H-zeolite and Na-zeolite are found in different copper final states when considered just after preparation, depending on ion- exchange or impregnation routes.