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

摘要

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 goldcobalt oxideceria/alumina catalysts demonstrated a high capacity to abate CO at and below room temperature. Total conversion was achieved at -70 degrees C. The calculated apparent activation energy values revealed a theoretical optimum loading of a half-monolayer.