WOx effect on the catalytic properties of Pt particles on Al_2O_3

摘要

The effect of WOx on the microstructure, Lewis acidity and catalytic conversion of Pt/Al_2O_3 catalysts was studied. High surface areas were obtained at low W concentration and the WOx species decreased the AI2O3 surface area and Lewis acid sites. WOx species in tetrahedral coordination were found. Multiple layers of close-packed spheres forming pores were seen on the Al_2O_3. The addition of WOx produced semi-cubic particles and the spheres disappeared. At low W concentrations (0.5-2 wt%W) dehydroci-clization and isomerization selectivities were higher than the hydrocracking selectivity. On the contrary high hydrocracking selectivity was found for samples with high W concentration (4-22 wt%W).