Activity and Characterization by XPS, HR-TEM, Raman Spectroscopy, and BET Surface Area of CuO/CeO₂-TiO₂ Catalysts

Abstract

Structural and textural studies of a CuO/TiO 2 system modified by cerium oxide were conducted using Raman spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and N 2 absorption (BET specific surface area). The introduction of a minor amount of CeO 2 (Ce 0.09 Ti 0.82 O 1.91 Cu 0.09 sample) resulted in a material with the maximum surface area value. The results of Raman spectroscopy revealed the presence of only two crystalline phases, TiO 2 anatase and CeO 2 cerianite, with well-dispersed copper species. TEM micrographs showed a trend toward smaller TiO 2 crystallites when the cerium oxide content was increased. The XPS analysis indicated the rise of a second peak in Ti 2p spectra with the increasing amount of CeO 2 located at higher binding energies than that due to the Ti 4+ in a tetragonal symmetry. The CuO/TiO 2 system modified by CeO 2 displayed a superior performance for methanol dehydrogenation than the copper catalyst supported only on TiO 2 or CeO 2 .