INFLUENCE OF THE TUNGSTEN-OXIDE PRECURSOR ON WOX-ZRO2 AND PT WOX-ZRO2PROPERTIES/

The influence of the tungsten precursor and of the preparation conditi ons on the properties of platinum free or platinum containing WOx prom oted zirconia has been studied. Catalysts were characterized by hydrog en chemisorption at room temperature, TPR, XRD and Laser Raman spectro scopy and during the n-hexane reaction at 200 degrees C, 6 kg cm(-2), and a hydrogen/n-hexane molar ratio 7. For all catalysts, the same WOx species were observed after calcination: crystalline WO3 and an amorp hous WOx species were detected by Laser Raman. The best catalytic acti vity and stability were observed on catalysts in which platinum was ad ded after calcination, independently of the WOx precursor used in the preparation. (C) 1997 Elsevier Science B.V.