Effect of Ce–Zr mixed oxides on the chemical state of Rh in alumina supported automotive exhaust catalysts studied by XPS and XRD

Suhonen, Sami; Valden, M.; Hietikko, M.; Laitinen, Riitta; Savimäki, A.; Härkönen, Matti

doi:10.1016/s0926-860x(01)00636-6

Cited by 93 publications

(45 citation statements)

References 26 publications

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“…Finally, Figure 6C shows the Zr 3d spectra: the peaks at 181.9-182.3 eV denote the Zr 3d 5/2 states, whereas the signals at 184.4 eV correspond to the Zr 3d 3/2 levels. According to the BE of Zr 3d 5/2 , Ce-Zr mixed oxide can be well-distinguished from the ZrO 2 phase (182.9 eV [55,56]). As a whole, no signal due to the ZrO 2 phase has been detected for any of the ceria-zirconia samples.…”

Section: Reducibility and Redox Properties Of Ceria-zirconia Materialsmentioning

confidence: 99%

Investigations into nanostructured ceria–zirconia catalysts for soot combustion

Piumetti

Bensaid

Russo

et al. 2016

Applied Catalysis B: Environmental

141

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Section: Reducibility and Redox Properties Of Ceria-zirconia Materialsmentioning

confidence: 99%

Investigations into nanostructured ceria–zirconia catalysts for soot combustion

Piumetti

Bensaid

Russo

et al. 2016

Applied Catalysis B: Environmental

141

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“…This phase is characterized by its unusually high Rh 3d 5/2 binding energy ¾310 eV and enhanced stability against H 2 -reduction. 6,7 The increase in the Rh 3d 5/2 binding energy and the stability enhancement have been explained either by the diffusion of Rh to the aluminium oxide 8,9 or by the formation of a more stable oxide phase, RhO 2 , on the surface of -Al 2 O 3 . 6 When supported on pure Ce-Zr mixed oxide Rh has been demonstrated to remain in easily reducible form also after air ageing at 1000°C.…”

Section: Introductionmentioning

confidence: 99%

“…6 When supported on pure Ce-Zr mixed oxide Rh has been demonstrated to remain in easily reducible form also after air ageing at 1000°C. 7 In this work the synergistic effects of Pt and Rh on the reducibility of Rh oxides in automotive exhaust catalysts are investigated.…”

Section: Introductionmentioning

confidence: 99%

The effect of platinum on the reducibility of Rh oxides on CeZr modified alumina supported automotive catalysts

Polvinen

Vippola

Valden

et al. 2004

Surface & Interface Analysis

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The reducibility of Rh oxide on Rh-only and Pt-Rh catalysts was investigated. The catalyst washcoats were composed of alumina modified by La and Ce-Zr mixed oxide. The catalyst ageing was performed in air at 1000• C for 3 h. In order to study the synergistic effect of Pt and Rh on the reducibility of Rh oxide, the propensity of the noble metal oxides to reduction was investigated by exposing the fresh and aged catalysts to 400 mbar of H 2 at 300 • C. XPS was used to observe the changes in chemical state of the noble metals and TEM and XRD were employed to determine the catalyst composition and morphology. Differences were revealed in the behaviour of Rh-only and Pt-Rh catalysts in H 2 -reduction. Rhodium supported on alumina-containing washcoats without Pt was found to react with the support at elevated temperatures to form a reduction-resistive oxide phase. On the Pt-Rh bimetallic catalyst Rh was found to be partly reducible after air ageing and the Rh 3d transition emerged with an unusually low binding energy after H 2 -reduction. Pt-Rh alloy particles were also formed in air ageing.

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“…The content of Ce-Zr mixed oxides in alumina is usually in the range of 10-40 wt.%. The mostly investigated characteristic of Ce-Zr mixed oxides is its promoted oxygen storage capability (OSC) in three-way catalysts [25][26][27][28][29][30][31][32][33]. Other possible roles of Ce-Zr mixed oxides have been mentioned [34].…”

Section: Introductionmentioning

confidence: 99%