Study of the surface and redox properties of ceria–zirconia oxides

Damyanova, S.; Pawelec, B.; Arishtirova, K.; Martı́nez-Huerta, M.V.; Fierro, J.L.G.

doi:10.1016/j.apcata.2007.12.005

Cited by 229 publications

(131 citation statements)

References 39 publications

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“…For the pure CeO 2 two main signals can be detected. The first one at 486 º C, is attributed to the reduction of the surface shell and the high temperature signal at 764 ºC to the reduction of the bulk of the material [13,47,48]. ,which may follow different kinetics, as was discussed by Li et al [50,51], and probably through the formation of FeO as intermediate species, as proposed by Zhong et al [52].…”

Section: 5mentioning

confidence: 92%

Fe-doped ceria solids synthesized by the microemulsion method for CO oxidation reactions

Laguna

Centeno

Boutonnet

et al. 2011

Applied Catalysis B: Environmental

170

126

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A series of Ce-Fe mixed oxides as well as the pure oxides were synthesized by the microemulsions method. The solid solution formation was established for all the Fedoped systems and only a hardly noticeable segregation of α-Fe 2 O 3 was appreciated for the solid with the maximum iron content (50 Fe atomic%). The oxygen exchange is improved for all the Fe-doped systems; however the 10 Fe atomic% appears as the optimal iron content for achieving the maximum oxygen vacancies concentration and the higher reducibility efficiency. The CO oxidation (TOX, PROX) is especially achieved for the solids with the lower iron contents but with a superior oxygen vacancies proportion. These Ce-Fe systems prepared from microemulsions are very attractive to be considered as supports for depositing active phases capable of enhancing oxygen exchange ability of the whole system, allowing higher CO oxidation abilities.

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Section: 5mentioning

confidence: 92%

Fe-doped ceria solids synthesized by the microemulsion method for CO oxidation reactions

Laguna

Centeno

Boutonnet

et al. 2011

Applied Catalysis B: Environmental

170

126

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“…Sun & Sermon (1996) measured a surface Ce/Zr ratio of 0.25 in a sample with nominal bulk composition Ce/Zr = 0.15, and Martinez-Arias et al (2003) obtained a Ce/Zr surface ratio of 2.6 for a sample with nominal bulk composition Ce/Zr = 1. More recently, Ce enrichment of the surface has been reported by Damyanova et al (2008) for Zr-rich solutions (Ce/Zr = 0.047 at the surface in a sample with only Ce/Zr = 0.007 overall) and Atribak et al (2009) for Ce-rich solutions (Ce/Zr = 8.1 at the surface, when nominal composition was Ce/Zr = 5.7), in both cases based on XPS measurements.…”

Section: (B) Cation Segregation At the (111) Surfacementioning

confidence: 99%

Phase separation and surface segregation in ceria–zirconia solid solutions

et al. 2011

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Using a combination of density functional theory calculations and statistical mechanics, we show that a wide range of intermediate compositions of ceria-zirconia solid solutions are thermodynamically metastable with respect to phase separation into Ce-rich and Zr-rich oxides. We estimate that the maximum equilibrium concentration of Zr in CeO 2 at 1373 K is approximately 2 per cent, and therefore, equilibrated samples with higher Zr content are expected to exhibit heterogeneity at the atomic scale. We also demonstrate that in the vicinity of the (111) surface, cation redistribution at high temperatures will occur with significant Ce enrichment of the surface, which we attribute to the more covalent character of Zr-O bonds compared with Ce-O bonds. Although the kinetic barriers for cation diffusion normally prevent the decomposition/segregation of ceria-zirconia solid solutions in typical catalytic applications, the separation behaviour described here can be expected to occur in modern three-way catalytic converters, where very high temperatures are reached.

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“…Bands observed at 3436-3448 cm -1 and 1632-1648 cm -1 are assigned to the stretching and bending vibrations of the O-H bond related to the formation of hydroxyl carbonate complex species 38 . The formation of tetragonal solid solution phase 39 and a distortion of the unit cell in ZrO 2 /CeO 2 mixed oxides 40 is characterized by the band found at ~ 566 cm -1 . However, weak bands for monoclinic phase appear at 744 and 444 cm -1 at 12% Zr-Ce mixture fired at 1600°C 41 .…”

Section: Ftirmentioning

confidence: 99%

Preparation and characterization of ZrO2/CeO2 ceramic composite synthesized by microwave combustion method

Abo-Almaged¹,

Khattab²,

Sadek³

2016

Orient. J. Chem

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ZrO 2 nano-powders with the substitution of; 5, 12 and 17 mole %CeO 2 contents were prepared by a microwave combustion method utilizing Ce(NO 3 ) 3 .6H 2 O, ZrN 2 O 7 .xH 2 O and urea as precursors. The obtained cakes were calcined at different temperatures. XRD, SEM, EDS, and TEM techniques were used to determine the effect of microwave and calcining temperature between 450 to 1000 o C on the prepared powders. The results obtained show the formation of a single phase; a tetragonal solid solution with a particle size ranging between 10 to 20 nm. The densification parameters, phase compositions, microstructures and mechanical properties (micro-hardness) were investigated.

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Study of the surface and redox properties of ceria–zirconia oxides

Cited by 229 publications

References 39 publications

Fe-doped ceria solids synthesized by the microemulsion method for CO oxidation reactions

Fe-doped ceria solids synthesized by the microemulsion method for CO oxidation reactions

Phase separation and surface segregation in ceria–zirconia solid solutions

Preparation and characterization of ZrO2/CeO2 ceramic composite synthesized by microwave combustion method

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