Abstract :
This study focused on preparation of tungsten oxide supported on zirconia by thermal spreading. The prepared samples were characterized by
infrared spectroscopy, UV–vis diffuse reflection spectroscopy, X-ray diffraction, and also by methanol dehydration reaction. It was observed that
isolated octahedral tungsten dispersed species and dispersed polytungstate were formed on zirconia surface, although some WO3 that remained
after the thermal treatment could also be detected. The presence of these species led to an increase of the number of Lewis sites and the generation
of Bro¨nsted acid sites. High calcination temperatures promoted the creation of Bro¨nsted sites as a consequence of polytungstate species formation.
The activity on methanol dehydration was also determined by the concentration of these species, whereas the isolated WOx species were found
poorly active. The correlation observed between the catalytic performance and the tungsten dispersed species, as revealed by spectroscopic
techniques, evidenced the occurrence of thermal spreading of WO3 on ZrO2. The results presented in this work show that WO3 thermal spreading
on ZrO2 may be effectively accomplished as predicted by thermodynamics.
