Understanding the effect of halide poisoning in CO oxidation over Au/TiO[subscript 2]

Journal Article · Tue Jul 08 04:00:00 EDT 2008 · Appl. Catal. A-Gen.

DOI:https://doi.org/10.1016/j.apcata.2008.01.025· OSTI ID:1006709

Oxford, S M; Henao, J D; Yang, J H; Kung, M C; Kung, H H ^[1]

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1. NWU

The effect of halide poisoning of Au/TiO{sub 2} 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 TiO{sub 2}, 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 {approx}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.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: USDOE
• OSTI ID: 1006709
• Journal Information: Appl. Catal. A-Gen., Journal Name: Appl. Catal. A-Gen. Journal Issue: (2) ; 05, 2008 Vol. 339; ISSN ACAGE4; ISSN 0926-860X
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ABSORPTION SPECTROSCOPY
ADSORPTION
ATOMS
BROMIDES
CAPACITY
CARBON MONOXIDE
CATALYSTS
GOLD
HALIDES
INTERFACES
LIGANDS
OXIDATION
POISONING
REDUCTION
TEMPERATURE RANGE 0065-0273 K
TITANIUM OXIDES
X-RAY SPECTROSCOPY