Influence of the incorporation of Fe and Mn on the nanostructure and reactivity of catalysts based on tungstated zirconia

Tungstated zirconia catalysts promoted with different contents of Fe and Mn (ZWFM) were synthesized by the coprecipitation method. The materials were characterized by XRD, Raman, XPS, and HAADF-STEM. Platinum was added by impregnation and reduced in situ before the catalytic test. The catalytic evaluation was performed on the Pt/ZWFM samples in the hydroisomerization of n-hexane at 260 °C. The characterization results indicate that the promoters can be located both on the surface of the zirconia and within the structure of the poly-tungstates, modifying the nanostructure and domain size of the Zr-WO_x clusters. These WO_x species are responsible for the formation of the acid sites for the isomerization reaction. The catalytic activity was affected by the promoter amount since we found that the high catalytic activity was related to a low promoter content. On the other hand, the segregation of iron and manganese oxides at high promoter contents hindered the formation of the acid sites.