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) spectroscopy techniques were used to investigate the structure of a TiO 2 −ZrO 2 binary oxide support and a V 2 O 5 /TiO 2 −ZrO 2 catalyst. The TiO 2 −ZrO 2 (1:1 mole ratio) was obtained by a homogeneous coprecipitation method, and the 12 wt % V 2 O 5 /TiO 2 −ZrO 2 catalyst was prepared by a wet impregnation method. Both samples were subjected to thermal treatments from 773 to 1073 K in order to understand the temperature stability of these materials. The TiO 2 −ZrO 2 support was in an amorphous state when calcined at 773 K. However, the formation of the ZrTiO 4 compound was noted at higher calcination temperatures characterized by a layer structure with a lattice spacing of ca. 2.87 Å due to the (111) plane of this compound. The V 2 O 5 /TiO 2 −ZrO 2 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 clear evidence for ZrV 2 O 7 and TiO 2 formation at 1073 K calcination in agreement with X-ray diffraction observations.