Mechanisms of CO oxidation reaction and effect of chlorine ions on the CO oxidation reaction over Pt/CeO2 and Pt/CeO2/gamma-Al2O3 catalysts

Oran U., Uner D.

APPLIED CATALYSIS B-ENVIRONMENTAL, vol.54, no.3, pp.183-191, 2004 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 54 Issue: 3
  • Publication Date: 2004
  • Doi Number: 10.1016/j.apcatb.2004.06.011
  • Journal Name: APPLIED CATALYSIS B-ENVIRONMENTAL
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.183-191
  • Keywords: CO oxidation, platinum, ceria, alumina, reaction mechanism, chlorine poisoning, CARBON-MONOXIDE, PT-CEO2AL2O3 CATALYSTS, HYDROGEN CHEMISORPTION, THERMAL TREATMENTS, OXYGEN-STORAGE, KINETICS, PLATINUM, ADSORPTION, REDUCTION, STABILITY
  • Middle East Technical University Affiliated: Yes

Abstract

The reaction orders and activation energies of CO oxidation reaction over Pt/gamma-Al2O3, Pt/CeO2 and Pt/CeO2/Y-Al2O3 were investigated for stoichiometric gas mixtures. The effect of residual chlorine originating from catalyst precursors on the CO oxidation activity of Pt/gamma-Al2O3, Pt/CeO2 and Pt/CeO2/gamma-Al2O3 was also studied. Indirect evidence was collected indicating that platinum was selectively deposited on alumina surface when Pt/CeO2/gamma-Al2O3 catalyst was prepared from the physical mixture of pure oxides. The reaction orders of CO and O-2 was found approximately as -2.0 and +1.0, respectively, over the Pt/gamma-Al2O3 catalyst, but as -1.0 and 0.0 over the Pt/CeO2 and Pt/CeO2/gamma-Al2O3 catalysts. The activation energy of CO oxidation reaction over Pt/gamma-Al2O3 catalyst under stoichiometric conditions was around 120.0 kJ/mol. On the other hand, over Pt/CeO2 catalysts activation energies were measured to be around 70 kJ/mol. Surface reaction mechanisms were postulated to explain the differences in the reaction orders and activation energies. (C) 2004 Elsevier B.V. All rights reserved.