Study of the formation of WO_x nanostructures supported on zirconia prepared by different synthesis routes

Different synthesis procedures of Pt supported on tungstated zirconia catalysts (Pt/WO_x-ZrO₂) were investigated with the aim to elucidate the different WO_x nanostructures developed on the zirconia surface depending on the preparation route. Pt/WO_x-ZrO₂ catalysts were synthesized by the coprecipitation and impregnation methods and pretreated by various procedures such as different calcinations temperatures or the use of reflux. The catalysts characterization was carried out by X-ray diffraction (XRD), Raman spectroscopy, transmission and scanning electron microscopy (TEM, SEM) and nitrogen physisorption, and the catalytic activity was evaluated in the n-hexane isomerization reaction. The results indicate that the development of active sites for isomerization of n-hexane is enhanced by the stabilization of the WO_x nanostructures on the surface of zirconia, before the formation of the WO₃ crystallites, and it largely depends on the synthesis method.