Raman Observation of the Chemical State of Ru/CeO₂ Catalysts

The chemical transformations of CeO₂ and Ru/CeO₂ catalysts under oxidative treatment (i.e., typical conditions of oxidation reactions on metal/oxide catalysts) were investigated using in situ Raman spectroscopy, and complemented by near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS). The main attention was focused on the Raman study of the effect of Ru loadinag degree on the structure of CeO₂ support in Ru/CeO₂ catalysts undergoing oxidative treatment. The advances and limitations of Raman spectroscopy for studying the chemical state of Ru/CeO₂ catalysts were systematically investigated and discussed, demonstrating its high potential to monitoring the physicochemical state of ceria support in the Ru/CeO₂ system. The limited applicability of Raman spectroscopy for monitoring the Ru species in Ru/CeO₂ catalyst was also demonstrated.