Transmission electron microscopy and energy-dispersive X-ray spectroscopy study-of V2O5/TiO2-ZrO2 catalyst

Transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) sp ectroscopy techniques were used to investigate the structure of a TiO2-ZrO2 binary oxide support and a V2O5/TiO2-ZrO2 catalyst. The TiO2-ZrO2 (1:1 mol e ratio) was obtained by a homogeneous coprecipitation method, and the 12 w t % V2O5/TiO2-ZrO2 catalyst was prepared by a wet impregnation method. Both samples were subjected to thermal treatments from 773 to 1073 K in order t o understand the temperature stability of these materials. The TiO2-ZrO2 su pport was in an amorphous state when calcined at 773 K. However, the format ion of the ZrTiO4 compound was noted at higher calcination temperatures cha racterized by a layer structure with a lattice spacing of ca. 2.87 Angstrom due to the (111) plane of this compound. The V2O5/TiO2-ZrO2 catalyst when calcined at 773 K shows heterogeneity in the distribution of vanadium oxide species on the support surface. The TEM/EDX analysis further provides clea r evidence for ZrV2O7 and TiO2 formation at 1073 K calcination in agreement with X-ray diffraction observations.