High-pressure X-ray photoelectron spectroscopy of palladium model hydrogenation catalysts. Part 2: Hydrogenation of trans-2-pentene on palladium

D. Teschner, A. Pestryakov, E. Kleimenov, M. Hävecker, H. Bluhm, H. Sauer, A. Knop-Gericke, R. Schlögl

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)

Abstract

We have performed the first "high-pressure" X-ray photoelectron spectroscopy (XPS) study on the palladium, hydrogen, and olefin (trans-2-pentene) system to gain better insight into the hydrogenation reaction. We report here data collected with the use of a Pd(111) single crystal and a polycrystalline foil. Hydrogenation was observed on polycrystalline foil (RT and 373 K) but not on Pd(111) single crystal, as revealed by on-line mass spectrometry. We observed the reaction in the presence of a huge amount of carbon (up to 73%) in the information depth of XPS. Mainly graphite was present on Pd(111), whereas other components, C-H and C-Pd, were also formed on the foil to a much greater extent. C-Pd characterizes a carbon species in the interaction with palladium, whereas C-H represents hydrogenated carbon, including chemisorbed species. The d-band of the foil showed a remarkable upshift toward EFERMI compared with Pd(111). We concluded that the differences found in the valence and the C1s region are indicators of different electronic structures that contribute to the variation in activity. The palladium foil lost its activity at an elevated temperature (523 K), most probably because of desorption of hydrogen. From additional UPS measurements, we concluded that trans-2-pentene is hydrogenated in σ-bonded chemisorption modus, at least in UHV conditions.

Original languageEnglish
Pages (from-to)195-203
Number of pages9
JournalJournal of Catalysis
Volume230
Issue number1
DOIs
Publication statusPublished - 15 Feb 2005

Keywords

  • Carbonaceous deposits
  • d-band
  • High-pressure XPS
  • Hydrogenation
  • Palladium
  • UPS

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry

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