Carbon monoxide oxidation over well-defined Pt/ZrO 2 model catalysts: Bridging the material gap

Attila Wootsch, Claude Descorme, Sophie Rousselet, Daniel Duprez, Claude Templier

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Four different Pt/ZrO 2 /(C/)SiO 2 model catalysts were prepared by electron beam evaporation. The morphology of these samples was examined before and after the catalytic reaction by Rutherford back-scattering (RBS), transmission electron microscopy (TEM) and grazing-incidence small-angle scattering (GISAXS). The catalytic behavior of such model catalysts was compared to a conventional Pt/ZrO 2 catalyst in the CO oxidation reaction using different oxygen excess (λ = 1 and 2). The so-called material gap was observed: model catalysts were active at higher temperature (620-770 K) and resulted in higher activation energy values (E a = 77-93 kJ mol -1 at λ = 1 and 129-141 kJ mol -1 at λ = 2) compared to the powdered Pt/ZrO 2 catalyst (370-470 K, E a = 74-76 kJ mol -1 ). This material gap is discussed in terms of diffusion limitations, reaction mechanism and apparent compensation effect. Diffusion processes seem to limit the reaction on planar samples in the reactor system that was shown to be appropriate for the evaluation of the catalytic activity of powder samples. Kinetic parameters obeyed the so-called apparent compensation effect, which is discussed in detail. Langmuir-Hinshelwood-type of reaction, between CO ads and O ads , was proposed as the rate-determining step in all cases. Pt particles deposited on planar structures can be used for modeling conventional powdered catalysts, even though some limitations must be taken into account.

Original languageEnglish
Pages (from-to)1310-1322
Number of pages13
JournalApplied Surface Science
Volume253
Issue number3
DOIs
Publication statusPublished - Nov 30 2006

Keywords

  • CO oxidation
  • Compensation effect
  • Electron beam evaporation
  • GISAX
  • Material gap
  • Model catalysts
  • Platinum
  • Pt
  • Pt/ZrO
  • RBS

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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