Changes in a Au/TiO2 catalyst during the activation process from an as-prepared state, consisting of supported AuOx(OH) 4-2x- species, were monitored with X-ray absorption spectroscopy and FTIR spectroscopy, complemented with XPS, microcalorimetry, and TEM characterization. When the catalyst was activated with H2 pulses at 298 K, there was an induction period when little changes were detected. This was followed by a period of increasing rate of reduction of Au3+ to Au0, before the reduction rate decreased until the sample was fully reduced. A similar trend in the activation process was observed if CO pulses at 273 K or a steady flow of CO at about 240 K was used to activate the sample. With both activation procedures, the CO oxidation activity of the catalyst at 195 K increased with the degree of reduction up to 70% reduction, and decreased slightly beyond 80% reduction. The results were consistent with metallic Au being necessary for catalytic activity.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry