In situ transient FTIR and XANES studies of the evolution of surface species in CO oxidation on Au/TiO2.
J Phys Chem B
; 110(17): 8689-700, 2006 May 04.
Article
em En
| MEDLINE
| ID: mdl-16640425
ABSTRACT
The adsorption of CO and its reaction with oxygen were investigated using a combination of in situ Fourier transform infrared spectroscopy, step response measurements in a microreactor, (18)O isotopic labeling, and X-ray absorption near edge structure spectroscopy. An as-prepared sample in which Au is present as a surface oxyhydroxy complex does not adsorb CO. On an activated sample in which only metallic Au is detected, 0.18 +/- 0.03 mol CO/(mol Au) are adsorbed on Au at -60 degrees C, which shows an IR band at 2090 cm(-1). When oxygen is present in the gas phase, this species reacts with a turnover rate of 1.4 +/- 0.2 mol CO(mol Au min)(-1), which is close to the steady-state turnover rate. In contrast, there is a very small quantity of adsorbed oxygen on Au. A small IR peak at 1242 cm(-1) appears when an activated sample is exposed to CO. It reacts rapidly with oxygen and is shifted to 1236 cm(-1) if (18)O is used. It is assigned to the possible intermediate hydroxycarbonyl.
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Base de dados:
MEDLINE
Assunto principal:
Titânio
/
Monóxido de Carbono
/
Ouro
Tipo de estudo:
Diagnostic_studies
Idioma:
En
Ano de publicação:
2006
Tipo de documento:
Article