Characterisation and reactivity of V2O5-MoO3/TiO2 de-NOx SCR catalyst

TiO2-supported V2O5–MoO3 catalysts, having V and Mo loadings representative of commercial SCR catalysts, are considered in this study. These catalysts are constituted by TiO2 anatase supporting the V and Mo active components. MoO3 acts as a “structural” promoter preventing the TiO2 matrix from sintering upon vanadia addition. The Mo and V oxide are present on the catalyst surface in the form of molybdenylic and vanadylic species, respectively, and the presence of polymeric MoxOy species cannot be excluded. The features of theVandMosurface oxide species closely resemble those observed over the binary V2O5/TiO2 and MoO3/TiO2 catalysts, thus pointing out the vibrational independence of the V and Mo surface vanadyl and molybdenyl oxide species. However, in spite of their structural and vibrational independence, the presence of electronic interactions between the TiO2-supported V and Mo oxides is also apparent. These interactions may operate via the TiO2 support or may involve mixed V–Mo surface oxide species who were, however, not observed.