Understanding the effect of halide poisoning in CO oxidation over Au/TiO2

S. M. Oxford, J. D. Henao, J. H. Yang, M. C. Kung, Harold H Kung

Research output: Contribution to journalArticle

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Abstract

The effect of halide poisoning of Au/TiO2 catalysts in low temperature CO oxidation was investigated using bromide as the poison and a combination of X-ray absorption spectroscopy (XANES and EXAFS), quantitative CO adsorption, and catalytic measurements. It was found that halide prevented full reduction of cationic Au by displacing oxyhydroxy ligands and remaining bound to Au during low temperature reduction, causing a reduction in catalytic activity. On reduced Au samples, bromide (likely as NaBr molecule) was preferentially adsorbed on Au and not on TiO2, and suppressed both the adsorption of CO and the catalytic activity. At low Br contents, each adsorbed Br suppressed adsorption of three CO, suggesting that Br was adsorbed on three-fold sites but the effect decreased with increasing Br content possibly due to crowding of adsorbed Br. When 5-10% of the Au was bound to Br, the catalytic activity was completely blocked, although ∼35% of the original CO adsorption capacity remained. The data suggest that not all CO adsorption sites are catalytic active sites, and are consistent with the perimeter Au atoms at/near the particle-support interface (perimeter) being active sites.

Original languageEnglish
Pages (from-to)180-186
Number of pages7
JournalApplied Catalysis A: General
Volume339
Issue number2
DOIs
Publication statusPublished - May 1 2008

Fingerprint

Carbon Monoxide
Adsorption
Oxidation
Catalyst activity
Bromides
Catalyst poisoning
X ray absorption spectroscopy
Poisons
Ligands
Atoms
Temperature
Catalysts
Molecules

Keywords

  • CO oxidation
  • Gold
  • Halide
  • Nanoparticle
  • Perimeter sites
  • Poisoning

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

Cite this

Understanding the effect of halide poisoning in CO oxidation over Au/TiO2. / Oxford, S. M.; Henao, J. D.; Yang, J. H.; Kung, M. C.; Kung, Harold H.

In: Applied Catalysis A: General, Vol. 339, No. 2, 01.05.2008, p. 180-186.

Research output: Contribution to journalArticle

Oxford, S. M. ; Henao, J. D. ; Yang, J. H. ; Kung, M. C. ; Kung, Harold H. / Understanding the effect of halide poisoning in CO oxidation over Au/TiO2. In: Applied Catalysis A: General. 2008 ; Vol. 339, No. 2. pp. 180-186.
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