Platinum over tungsten oxide or sulfate promoted zirconia: a study of the metallic and acid functions and their poisoning

M.G. FALCO; J.M. GRAU; N.S. FÏGOLI

APPLIED CATALYSIS A-GENERAL

Elsevier Sci. B.V.

Lugar: Amsterdam; Año: 2004 vol. 264 p. 183 - 192

0926-860X

Bifunctional platinum over tungsten oxide promoted zirconia (Pt/WZ) and platinum over sulfate promoted zirconia (Pt/SZ)catalysts, were studied. The metallic and acid functions are provided by Pt and WOx or SO42- species, respectively. The catalysts were characterized by DRX, Sg, ICP-OES, DRIFTS and test reactions: cyclohexane dehydrogenation (metallic function) and n-pentane isomerization (acid function). The catalytic activity and selectivity and the poisoning with S and N compounds of both reactions, were measured. Benzene and methylcyclopentane were obtained in the cyclohexane reaction and iso-pentane was the main product during n-pentane isomerization. Both reactions were carried out at 300 °C, atmospheric pressure and in the presence of hydrogen. Poisoning studies using sulphur (carbon disulfide) and nitrogen (n-butylamine) containing compounds were made. Pt/WZ and Pt/SZ were sensitive to poisons. The poisoning with CS2 affects directly the activity of the metal function and indirectly the one of the acid function because decreases the hydrogen dissociation capacity of Pt. The poisoning with n-butylamine only affects the acid function. Key words: Pt/WOx-ZrO2; Pt/SO42--ZrO2; N and S poisoning; metal function, acid function