Studies of architecture of MoO3–TiO2 catalysts

Abstract

X-Ray diffraction, F.t.i.r., scanning electron microscopy (SEM) and ion-scattering spectroscopy (ISS) have been applied to characterize a series of MoO₃–TiO₂(anatase) samples prepared by the grafting and impregnation methods. The sample prepared with the grafting method exhibits good dispersion of MoO₃, whereas the impregnation technique leads to a poorer dispersion of molybdena on the surface of titania. The poorer dispersion of MoO₃ is due to the clustering of molybdena when the MoO₃ loading does not exceed the theoretical monolayer coverage (6.3 wt% MoO₃). At higher MoO₃ loading, crystals of MoO₃ of morphology different from pure MoO₃ crystals, appear. A possible explanation of this phenomenon is discussed.