Influence of Vanadium or Cobalt Oxides on the CO Oxidation Behavior of Au/MO x /CeO 2 –Al 2 O 3 Systems

A series of V 2 O 5 ‐ and Co 3 O 4 ‐modified ceria/alumina supports and their corresponding gold catalysts were synthesized and their catalytic activities evaluated in the CO oxidation reaction. V 2 O 5 ‐doped solids demonstrated a poor capacity to abate CO, even lower than that of the original ceria/alumina support, owing to the formation of CeVO 4 . XRD, Raman spectroscopy, and H 2 ‐temperature programmed reduction studies confirmed the presence of this stoichiometric compound, in which cerium was present as Ce 3+ and its redox properties were avoided. Co 3 O 4 ‐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 CeVO 4 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.