Platinum supported WOx–ZrO2: Effect of calcination temperature and tungsten loading Original Research Article

The influence of calcination temperature (500–880°C) and of tungsten loading (2, 5 and 18 wt.%) on platinum supported on tungsten-oxide-promoted zirconia, where the platinum was added after high-temperature calcination of the support, has been studied. Catalysts were characterized by X-ray diffraction, temperature-programmed reduction, ammonia temperature-programmed desorption, X-ray photoelectron spectroscopy, laser Raman spectroscopy and catalytic activity for n-hexane isomerization in the presence of hydrogen. A maximum in catalytic activity, defined as “moles of n-hexane converted×(surface density of tungsten atoms)−1 h−1”, is observed for the sample calcined at 700°C. Regarding tungsten loading, samples calcined at 830°C and containing 2 and 5 wt.% tungsten show a lower catalytic activity than a sample containing 18 wt.%. The catalytic activity is associated with the presence of crystalline WO3.