Gold Stabilized with Iridium on Ceria–Niobia Catalyst: Activity and Stability for CO Oxidation

ZANELLA, RODOLFO; BONIVARDI, ADRIAN; AGUIRRE, ALEJO; HERNÁNDEZ, SANDRA; BARRIOS, CELINA; COLLINS, SEBASTIÁN E.

TOPICS IN CATALYSIS

SPRINGER/PLENUM PUBLISHERS

Año: 2019 vol. 62 p. 977 - 988

1022-5528

Monometallic gold and iridium, and bimetallic gold?iridium on ceria?niobia (Nb2O5?CeO2) catalysts were synthesized by deposition?precipitation with urea. Ceria?niobia support, synthesized by co-precipitation, presented a higher reducibility and a higher surface acidity as a consequence of the deposition of niobia on the ceria surface. The Au?Ir/CeNb showed an enhanced activity and stability during the carbon monoxide oxidation reaction as compared with the monometallic catalysts. These catalysts were thoroughly characterized chemical and structurally. High-resolution electron microscopy, UV?Vis spectroscopy and CO adsorption showed evidences of iridium-gold closeness. In situ infrared spectroscopy in the diffuse reflectance (DRIFT) mode was used to investigate the reactivity of the active sites. A lower coverage of carbonate species was observed under reaction as a result of the presence of niobia in the catalyst formulation. Concentration-modulation excitation spectroscopy (c-MES) allowed a selective identification of intermediates and ?spectator? species. New adsorption sites for CO were identified and correlated with the high activity and stability of the bimetallic catalyst.