Preparation of tungsten oxide promoted zirconia by different methods

The platinum on tungsten oxide promoted zirconia preparation using different procedures has been studied. Zirconium oxyclhoride, ammonium hydroxide, ammonium metatungstate, and hexachloroplatinic acid solutions were used as raw materials in all cases. Tungsten oxide promoted zirconium hydroxide (obtained using the three first reagents) was calcined at 700 or 800 °C; then, each fraction was impregnated with hexachloroplatinic acid solutions. The solids were characterized by nitrogen adsorption, X-ray diffraction (XRD), NH3–TPD, temperature-programmed reduction (TPR) and used as catalysts for n-hexane isomerization at 200 °C, WHSV = 4 h−1, 6 kg cm−2 and H2:n-hexane (molar) = 7. The solids have different properties depending on the preparation procedure: surface area, pore size distribution, X-ray diffraction patterns, TPR profiles and activity for the isomerization reaction. Different WOx domain sizes are also obtained, which modify the TPR profiles and the catalytic activity for n-hexane isomerization.