Volume 4, Issue 4 p. 512-520
Full Paper

Influence of Vanadium or Cobalt Oxides on the CO Oxidation Behavior of Au/MOx/CeO2–Al2O3 Systems

Tomás Ramírez Reina

Tomás Ramírez Reina

Instituto de Ciencia de Materiales de Sevilla, Centro mixto, Universidad de Sevilla–CSIC, Avenida Americo Vespucio 49, 41092 Sevilla (Spain), Fax: (+34) 954460665

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Andrea Álvarez Moreno

Andrea Álvarez Moreno

Instituto de Ciencia de Materiales de Sevilla, Centro mixto, Universidad de Sevilla–CSIC, Avenida Americo Vespucio 49, 41092 Sevilla (Spain), Fax: (+34) 954460665

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Dr. Svetlana Ivanova

Dr. Svetlana Ivanova

Instituto de Ciencia de Materiales de Sevilla, Centro mixto, Universidad de Sevilla–CSIC, Avenida Americo Vespucio 49, 41092 Sevilla (Spain), Fax: (+34) 954460665

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Prof. Dr. José Antonio Odriozola

Prof. Dr. José Antonio Odriozola

Instituto de Ciencia de Materiales de Sevilla, Centro mixto, Universidad de Sevilla–CSIC, Avenida Americo Vespucio 49, 41092 Sevilla (Spain), Fax: (+34) 954460665

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Dr. Miguel Angel Centeno

Corresponding Author

Dr. Miguel Angel Centeno

Instituto de Ciencia de Materiales de Sevilla, Centro mixto, Universidad de Sevilla–CSIC, Avenida Americo Vespucio 49, 41092 Sevilla (Spain), Fax: (+34) 954460665

Instituto de Ciencia de Materiales de Sevilla, Centro mixto, Universidad de Sevilla–CSIC, Avenida Americo Vespucio 49, 41092 Sevilla (Spain), Fax: (+34) 954460665Search for more papers by this author
First published: 01 March 2012
Citations: 26

Graphical Abstract

And cobalt takes the gold: Vanadium-doped catalysts (with or without gold) are less active than those with a non-doped support, owing to the loss of the oxygen storage/release properties of the Ce4+/Ce3+ redox pair in the crystallization of CeVO4. Cobalt doping enhances the catalytic performance of the support; the activity depends on the loading of cobalt, which forms a submonolayer in the support surface.

Abstract

A series of V2O5- and Co3O4-modified ceria/alumina supports and their corresponding gold catalysts were synthesized and their catalytic activities evaluated in the CO oxidation reaction. V2O5-doped solids demonstrated a poor capacity to abate CO, even lower than that of the original ceria/alumina support, owing to the formation of CeVO4. XRD, Raman spectroscopy, and H2-temperature programmed reduction studies confirmed the presence of this stoichiometric compound, in which cerium was present as Ce3+ and its redox properties were avoided. Co3O4-doped supports showed a high activity in CO oxidation at subambient temperatures. The vanadium oxide-doped gold catalysts were not efficient because of gold particle agglomeration and CeVO4 formation. However, the gold–cobalt oxide–ceria/alumina catalysts demonstrated a high capacity to abate CO at and below room temperature. Total conversion was achieved at −70 °C. The calculated apparent activation energy values revealed a theoretical optimum loading of a half-monolayer.