Catalytic activities of unsupported and supported vanadium oxides for H2 oxidation were investigated in relation to the catalyst structures. From results of reaction rates and steady-state catalyst structures at various O2 concentrations, the active oxygen species was found to be the surface V=O species. The specific activity of the surface V=O species, or the turnover frequency, on usupported V2O5 catalyst did not change with the treatment of the catalyst. Neither fusion nor reduction-oxidation treatment affected the turnover frequency. This indicates that H2 oxidation on vanadium oxide catalyst is a structure-insensitive reaction. It was also found that the turnover frequency for V2O5/TiO2 and V2O5/Al2O3 is constant and independent of the kind of support or V2O5 content. In other words, the rate of H2 oxidation on the vanadium catalyst is determined only by The number of surface V=O species for all catalysts. These behaviors in H2 oxidation are discussed in comparison with those in CO or ethylene oxidation.
ASJC Scopus subject areas