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Yang, L.; Kresnawahjuesa, Oferi; Gorte, Raymond J.

doi:10.1023/a:1009012610200

Cited by 34 publications

(18 citation statements)

References 38 publications

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“…Since the transfer of oxygen from CeO 2 to a precious metal must be endothermic [9], there must be a barrier to the oxygen-transfer reaction. Furthermore, it is reasonable to assume that one might lower the height of this barrier by allowing the transfer to occur in two steps, as might occur when a third component is inserted between the ceria and the precious metal.…”

Section: Introductionmentioning

confidence: 99%

The effect of Fe and other promoters on the activity of Pd/ceria for the water-gas shift reaction

Wang

Gorte

2003

Applied Catalysis A: General

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The effect of adding oxide promoters, at monolayer coverages, to Pd/ceria catalysts was studied for the watergas-shift reaction in 25 torr each of H 2 O and CO under differential conditions. Oxides of Fe, Tb, Gd, Y, Sn, Sm, Pr, Eu, Bi, Cr, V, Pb, and Mo were added to ceria by wet impregnation of aqueous salts and calcined to 873 K prior to addition of 1 wt% Pd. While most of the oxides had a negligible effect on the water-gas-shift rates, rates on the Fe-promoted sample were 8 times higher than on the unpromoted Pd/ceria at 473 K, while rates on the Mo-and Pb-promoted cerias were significantly lower than on pure Pd/ceria. By varying the Fe loading, it was found that the maximum catalytic activity was achieved at the monolayer coverage. Addition of Fe in bulk ceria through sol-gel and preparation of Fe 2 O 3 -CeO 2 physical mixtures had no effect on the catalytic activity. AbstractThe effect of adding oxide promoters, at monolayer coverages, to Pd/ceria catalysts was studied for the water-gas-shift reaction in 25 torr each of H 2 O and CO under differential conditions. Oxides of Fe, Tb, Gd, Y, Sn, Sm, Pr, Eu, Bi, Cr, V, Pb, and Mo were added to ceria by wet impregnation of aqueous salts and calcined to 873 K prior to addition of 1 wt% Pd. While most of the oxides had a negligible effect on the water-gas-shift rates, rates on the Fe-promoted sample were 8 times higher than on the unpromoted Pd/ceria at 473 K, while rates on the Moand Pb-promoted cerias were significantly lower than on pure Pd/ceria. By varying the Fe loading, it was found that the maximum catalytic activity was achieved at the monolayer coverage. Addition of Fe in bulk ceria through sol-gel and preparation of Fe 2 O 3 -CeO 2 physical mixtures had no effect on the catalytic activity.

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Section: Introductionmentioning

confidence: 99%

The effect of Fe and other promoters on the activity of Pd/ceria for the water-gas shift reaction

Wang

Gorte

2003

Applied Catalysis A: General

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“…For example, the free energy change in the simultaneous reduction of Ce0 2 to Ce 2 0 3 and oxidation of CO (H 2 ) to C0 2 (H 2 0) is +15 kcal/mol-CO (+22 kcal/mol-H 2 ) at 300 K, falling only to +9 kcal/mol-CO (+7 kcal/mol-H 2 ) at 1000 K. A recent study by Yang et al [9] has shown that the binding of oxygen in freshly-prepared ceria (and ceria-zirconia) is actually much weaker than in well-crystallized solids, ~200 kJ/mol ( Pd films may be oxidized by their ceria-zirconia supports merely by heating to 470 K in UHV reinforces Yang et al's result [10].…”

Section: Interaction Of Ceria With the Active Noble Metalsmentioning

confidence: 96%

Ceria and Other Oxygen Storage Components in Automotive Catalysts

Shelef

Graham

McCabe

2002

Catalysis by Ceria and Related Materials

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“…These observations can be explained as being due to desorption of O 2 from the ceria containing materials (and the concomitant formation of Ce 3+ ) [16][17][18][19][20][21][22][23]. Initially this O 2 (rather than leaving the system) reacted with the PM and formed CO 2 .…”

Section: Formation Of Ce 3+ -Co Species From Reaction Between Cexzr1-mentioning

confidence: 99%

“…The rationale behind the use of these materials in this reaction is related to the oxygen storage capacity of the catalysts. CeO 2 can desorb and re-adsorb O 2 through formation and consumption of a Ce 2 O 3 oxide [16][17][18][19][20]. The oxygen atoms involved in this process are active for promotion of various combustion and reforming reactions [21][22][23][24][25] and for this reason (as well as their ability to dampen excursions to overly fuel rich or fuel lean exhaust conditions) Ce (x) Zr (1-x) O 2 catalysts are used as supports in many catalytic formulations.…”

Section: Introductionmentioning

confidence: 99%

Attempts at an in situ Raman study of ceria/zirconia catalysts in PM combustion

Sullivan

Dulgheru

Atribak

et al. 2011

Applied Catalysis B: Environmental

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Publisher's statementThis is the author's version of a work that was accepted for publication in Applied Catalysis B: Environmental. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Applied Catalysis B: Environmental, 108-109 (1) Ce (x) Zr (1-x) O 2 catalysts with various Ce / Zr contents were studied using Raman spectroscopy under different gaseous atmospheres, at different temperatures and in the presence of a model soot.Catalysts with high concentrations of Zr fluoresced at elevated temperatures making analysis of their spectra impossible. This effect became even more pronounced at higher temperatures. CeO 2 and solid solutions with relatively low concentrations of Zr showed a red shift and a decrease in intensity of the characteristic F 2g peak at high temperatures under different atmospheres. The magnitude of the latter effect was higher under reducing atmospheres. These changes are reversible upon cooling, showing that they relate to a lattice expansion effect rather than any major chemical change to the material. In the presence of the model soot the Raman spectra of all materials was much decreased due to the absorption of the incident and scattered radiation by the soot particles. The presence of soot does not change the relative intensities or positions of the peaks in the spectra of the solid solutions. Evidence is shown for the production of a Ce 3+ -CO species following interaction between the soot and the surface at high temperature in an inert atmosphere.

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Cited by 34 publications

References 38 publications

The effect of Fe and other promoters on the activity of Pd/ceria for the water-gas shift reaction

The effect of Fe and other promoters on the activity of Pd/ceria for the water-gas shift reaction

Ceria and Other Oxygen Storage Components in Automotive Catalysts

Attempts at an in situ Raman study of ceria/zirconia catalysts in PM combustion

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