Electron paramagnetic resonance spectra of CeO2 catalyst for CO oxidation

Oliva, Cesare; Termignone, Giorgio; Vatti, Francesco P.; Forni, L.; Вишняков, А.В.

doi:10.1007/bf00354457

Cited by 49 publications

(27 citation statements)

References 22 publications

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“…These paramagnetic signals may be ascribed to Ce 3? ion in the bulk structure, with one unpaired electron in the 4f state [25], or to electrons trapped at oxygen vacancies of the ceria lattice [26]. These contributions would be supported by the fact that Ce 3?…”

Section: Epr Resultsmentioning

confidence: 94%

The Interaction of Oxides of the Pd/Ce/Zr/Al2O3 Catalysts Prepared by Impregnation Over Alumina and Promoting Effects on Surface Properties

2010

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Pd/CeO 2 , Pd/ZrO 2 and Pd/CeO 2 -ZrO 2 , were prepared by impregnation on a well defined alumina support. The oxides are finely dispersed over alumina support. TPR results on promoted Zr and Ce catalysts indicate partial reduction of CeO 4 and ZrO 2 . The dispersions for Pd/ Al 2 O 3 and Pd/Zr/Al 2 O 3 are similar but very different on , increasing 4 and 7 times in relation to the Pd/Al 2 O 3, suggesting re-dispersion of Pd, mainly due to the promoting effect of Ce. EPR signals of Pd/Ce/Al 2 O 3 are related with O 2-species of Ce 4? -O 2-. DRIFTS studies with NO and CH 4 reaction showed that the Pd d? species interacts with Ce ?d , modifying significantly the NO ? CH 4 reaction route.

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Section: Epr Resultsmentioning

confidence: 94%

The Interaction of Oxides of the Pd/Ce/Zr/Al2O3 Catalysts Prepared by Impregnation Over Alumina and Promoting Effects on Surface Properties

2010

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“…In addition, the samples that contain CeO 2 typically show a sharp axial signal with g ⊥ = 1.965 and g = 1.940. These features have been previously related with either quasi-free electrons or with Ce 3+ cations located in distorted sites of the fluorite lattice [21][22][23][24]. A recent study has assigned this signal to Cr 3+ impurities of CeO 2 at the ppb level [25].…”

Section: Epr Study Of Oxygen Adsorptionmentioning

confidence: 89%

Nature of the vanadia?ceria interface in V5+/CeO2 catalysts and its relevance for the solid-state reaction toward CeVO4 and catalytic properties

Martı́nez-Huerta¹

2004

Journal of Catalysis

145

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“…68 Electron in Oxygen Vacancies Close to Titanium Centers. An alternative assignment for the g = 1.96 signal in ZnO samples could be proposed by analogy with the assignment proposed for the similar signal (g = 1.96) observed in ceria, 69,70 which is also a oxygen deficient semiconductor. 70−74 Moreover, as in the case of ZnO, the signal is detected at relatively high temperature 70 and its width is small.…”

Section: However This V Omentioning

confidence: 97%

ZnO Oxygen Vacancies Formation and Filling Followed by in Situ Photoluminescence and in Situ EPR

et al. 2012

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Oxygen vacancies of zinc oxide were followed by photoluminescence (PL) and electron paramagnetic resonance (EPR) spectroscopies. The green PL emission was associated with oxygen vacancies: its intensity is enhanced upon static thermal treatment under inert or under vacuum, whereas it decreases upon oxygen treatment. A unique EPR signal at g = 1.96 was measured at room temperature after thermal in situ treatment under flow of inert or oxygenated atmospheres, its double integration follows the same trends than the green PL emission and its evolution was shown to probe the oxygen vacancy concentrations. The relative concentration of the related paramagnetic species would be increased/decreased upon trapping/release of the electron associated to the formation/filling of oxygen vacancy. The influence of Ti impurities on the PL and RPE signals was investigated. Finally, it is concluded that the EPR signal is related to oxygen vacancies and its position shift could be explained by the involvement of some mixing orbitals. Thanks to static (PL and EPR) and dynamic (EPR) in situ characterizations, the conditions of formation or filling of oxygen vacancies are discussed depending of the atmosphere and temperature of the pretreatment of kadox and ex-carbonate zinc oxide. High temperature treatments, inert atmospheres, and vacuum lead to the formation of new oxygen vacancies. This process is reversible upon oxygenated atmospheres. The efficiency of such filling up depends on the temperature and starts to prevail on the oxygen vacancy formation below 500 K. It is also shown that few native oxygen vacancies can also be filled up.

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Electron paramagnetic resonance spectra of CeO2 catalyst for CO oxidation

Cited by 49 publications

References 22 publications

The Interaction of Oxides of the Pd/Ce/Zr/Al2O3 Catalysts Prepared by Impregnation Over Alumina and Promoting Effects on Surface Properties

The Interaction of Oxides of the Pd/Ce/Zr/Al2O3 Catalysts Prepared by Impregnation Over Alumina and Promoting Effects on Surface Properties

Nature of the vanadia?ceria interface in V5+/CeO2 catalysts and its relevance for the solid-state reaction toward CeVO4 and catalytic properties

ZnO Oxygen Vacancies Formation and Filling Followed by in Situ Photoluminescence and in Situ EPR

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