The oxidation of carbon monoxide over unsupported and supported vanadium oxide catalysts was investigated from the standpoint of structure sensitivity. The activity of unsupported V2O5 catalyst changed greatly with the treatment of the catalyst: The fusion of unsupported V2O5 markedly decreased the turnover frequency, while the reduction-oxidation treatment of the fused catalyst increased it. The turnover frequency of V2O5/TiO2 with low V2O5 content was much smaller than that of the V2O5/TiO2 with high V2O5 content or the unsupported V2O5. Such a retarding effect of the TiO2 support on the activity of the oxidation of carbon monoxide is in contrast to the known promoting effect of TiO2 for the oxidations of various hydrocarbons. From these results coupled with the characterization of the catalysts, it was concluded that the oxidation of carbon monoxide on vanadium oxide catalysts is a structure-sensitive reaction and that the activity of surface defects such as steps, kinks, and vacancies is much higher than that of the surface V=O species in the smooth (010) face of V2O5.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry