In situ time-resolved characterization of Au-CeO2 and AuOx-CeO2 catalysts during the water-gas shift reaction: presence of Au and O vacancies in the active phase

X Wang; J A Rodriguez; J C Hanson; M Pérez; J Evans

doi:10.1063/1.2136876

In situ time-resolved characterization of Au-CeO2 and AuOx-CeO2 catalysts during the water-gas shift reaction: presence of Au and O vacancies in the active phase

J Chem Phys. 2005 Dec 8;123(22):221101. doi: 10.1063/1.2136876.

Authors

X Wang¹, J A Rodriguez, J C Hanson, M Pérez, J Evans

Affiliation

¹ Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973, USA. rodrigez@bnl.gov

PMID: 16375458
DOI: 10.1063/1.2136876

Abstract

Synchrotron-based in situ time-resolved x-ray diffraction and x-ray absorption spectroscopies were used to study the behavior of nanostructured {Au+AuO(x)}-CeO(2) catalysts under the water-gas shift (WGS) reaction. At temperatures above 250 degrees C, a complete AuO(x)-->Au transformation was observed with high catalytic activity. Photoemission results for the oxidation and reduction of Au nanoparticles supported on rough ceria films or a CeO(2)(111) single crystal corroborate that cationic Au(delta+) species cannot be the key sites responsible for the WGS activity at high temperatures. The rate determining steps for the WGS seem to occur at the gold-ceria interface, with the active sites involving small gold clusters (<2 nm) and O vacancies.