Structural analysis of Rh-Pd/CeO2 catalysts under reductive conditions: an X-ray investigation

Morgan S Scott, Geoffrey Ian Neil Waterhouse, Kenichi Kato, Lan-Yun Shery Chang, Hicham Idriss, Tilo Soehnel

Research output: Contribution to journalArticleResearchpeer-review

4 Citations (Scopus)

Abstract

X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) were used to probe the electronic and geometric structures of Rh-Pd/CeO2 catalysts before and after ethanol steam reforming (ESR) at 400 °C, as well as after heating in CO atmospheres as a function of time and temperatures. The O/Ce ratio determined by XPS for the as-prepared Rh-Pd/CeO2 catalysts (individual metal loadings of 0.5 or 2 wt%) were close to 2, with the Rh and Pd present primarily in oxidized form (as oxide and chloride surface species). After ESR at 400 °C the ceria support was heavily reduced to CeO2-x (x = 0.3-0.4), with Rh0 (64 % of total Rh) and Pd0 (67 % of total Pd) being the dominant species. Heating the as-prepared Rh-Pd/CeO2 catalysts under a CO atmosphere at 200-400 °C while monitoring the Pd and Rh K edges by XAS was also conducted. XAS of the K edge of Pd and Rh indicated, as expected, reduction of Pd before that of Rh from 200 °C onward. The FCC order of Pd is however perturbed at 400 °C. On the contrary, Rh once reduced maintained a well ordered (FCC) structure. This observation is rationalised by the greater reduction effect of Pd on CeO2 compared to Rh and therefore at the interface Pd structure may be altered at high temperatures
Original languageEnglish
Pages (from-to)123-133
Number of pages11
JournalTopics in Catalysis
Volume58
Issue number2
DOIs
Publication statusPublished - 2015

Keywords

  • In-situ CO reduction
  • Rh and Pd XANES
  • Rh and Pd XPS
  • Bimetallic catalysts
  • Ethanol steam reforming (ESR)
  • CeO2 HRTEM

Cite this

Scott, M. S., Waterhouse, G. I. N., Kato, K., Chang, L-Y. S., Idriss, H., & Soehnel, T. (2015). Structural analysis of Rh-Pd/CeO2 catalysts under reductive conditions: an X-ray investigation. Topics in Catalysis, 58(2), 123-133. https://doi.org/10.1007/s11244-014-0351-z
Scott, Morgan S ; Waterhouse, Geoffrey Ian Neil ; Kato, Kenichi ; Chang, Lan-Yun Shery ; Idriss, Hicham ; Soehnel, Tilo. / Structural analysis of Rh-Pd/CeO2 catalysts under reductive conditions: an X-ray investigation. In: Topics in Catalysis. 2015 ; Vol. 58, No. 2. pp. 123-133.
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abstract = "X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) were used to probe the electronic and geometric structures of Rh-Pd/CeO2 catalysts before and after ethanol steam reforming (ESR) at 400 °C, as well as after heating in CO atmospheres as a function of time and temperatures. The O/Ce ratio determined by XPS for the as-prepared Rh-Pd/CeO2 catalysts (individual metal loadings of 0.5 or 2 wt{\%}) were close to 2, with the Rh and Pd present primarily in oxidized form (as oxide and chloride surface species). After ESR at 400 °C the ceria support was heavily reduced to CeO2-x (x = 0.3-0.4), with Rh0 (64 {\%} of total Rh) and Pd0 (67 {\%} of total Pd) being the dominant species. Heating the as-prepared Rh-Pd/CeO2 catalysts under a CO atmosphere at 200-400 °C while monitoring the Pd and Rh K edges by XAS was also conducted. XAS of the K edge of Pd and Rh indicated, as expected, reduction of Pd before that of Rh from 200 °C onward. The FCC order of Pd is however perturbed at 400 °C. On the contrary, Rh once reduced maintained a well ordered (FCC) structure. This observation is rationalised by the greater reduction effect of Pd on CeO2 compared to Rh and therefore at the interface Pd structure may be altered at high temperatures",
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Scott, MS, Waterhouse, GIN, Kato, K, Chang, L-YS, Idriss, H & Soehnel, T 2015, 'Structural analysis of Rh-Pd/CeO2 catalysts under reductive conditions: an X-ray investigation', Topics in Catalysis, vol. 58, no. 2, pp. 123-133. https://doi.org/10.1007/s11244-014-0351-z

Structural analysis of Rh-Pd/CeO2 catalysts under reductive conditions: an X-ray investigation. / Scott, Morgan S; Waterhouse, Geoffrey Ian Neil; Kato, Kenichi; Chang, Lan-Yun Shery; Idriss, Hicham; Soehnel, Tilo.

In: Topics in Catalysis, Vol. 58, No. 2, 2015, p. 123-133.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - Structural analysis of Rh-Pd/CeO2 catalysts under reductive conditions: an X-ray investigation

AU - Scott, Morgan S

AU - Waterhouse, Geoffrey Ian Neil

AU - Kato, Kenichi

AU - Chang, Lan-Yun Shery

AU - Idriss, Hicham

AU - Soehnel, Tilo

PY - 2015

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KW - Rh and Pd XANES

KW - Rh and Pd XPS

KW - Bimetallic catalysts

KW - Ethanol steam reforming (ESR)

KW - CeO2 HRTEM

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DO - 10.1007/s11244-014-0351-z

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