Alumina-doped Pt/WOx/ZrO2 catalysts for n-heptane isomerization Original Research Article

n-Heptane isomerization over Al2O3-doped Pt/WOx/ZrO2 (Pt/WZA) in comparison with Pt/WOx/ZrO2 (Pt/WZ) was studied in the presence of H2 at 200 °C. Higher isomerization selectivity was observed for these catalysts. The catalytic activity depends strongly on surface WOx loading and calcination temperature of WOx/Al2O3–ZrO2 (WZA) and WOx/ZrO2 (WZ) supports. The maximum activity for both Pt/WZA and Pt/WZ catalysts occurs at a WOx concentration of 10 wt.% W which is slightly higher than the theoretical monolayer capacities of WZA and WZ supports calcined at 800 °C. Pt/WZA catalyst exhibits the higher maximum activity than Pt/WZ. The loss in activity observed at high H2 pretreatment temperatures appears to be due to the strong interaction between Pt and reduced WOx species.