Effect of calcination temperature on Al2O3-supported CeO2: complementary results from XRD and XPS
| Autor: | P. J. Schmitz, George W. Graham, C. R. Peters, R.K. Usmen, Robert Walter Mccabe |
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| Rok vydání: | 1993 |
| Předmět: |
Cerium oxide
Analytical chemistry General Physics and Astronomy chemistry.chemical_element Surfaces and Interfaces General Chemistry Condensed Matter Physics Surfaces Coatings and Films law.invention Cerium X-ray photoelectron spectroscopy chemistry law Oxidation state X-ray crystallography Electronic effect Calcination Particle size Nuclear chemistry |
| Zdroj: | Applied Surface Science. 72:181-187 |
| ISSN: | 0169-4332 |
| DOI: | 10.1016/0169-4332(93)90010-9 |
| Popis: | X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) have been used to follow the effect of calcination temperature on CeO2 particle size, relative CeO2 concentration, and cerium oxidation state for CeO2 supported on γ-Al2O3. When the calcination temperature was increased from 500 to 900°C, XRD results indicated a decrease in the relative concentration of CeO2 at the highest loading (15 wt%), while XPS results reflected an apparent reduction of Ce4+toCe3+ at the lowest loading (5 wt%). Together these results suggest a transformation of a portion of the CeO2 particles to a more dispersed Ce3+-like species following high-temperature calcination. The reduction of ceria under these conditions is thermodynamically unfavorable. The apparent reduction of Ce4+ to Ce3+ upon calcination may be the result of an electronic effect, rather than a true reduction of the ceria. |
| Databáze: | OpenAIRE |
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