Ensemble size reduction by rhenium-sulfur as a method to lower the rate of deactivation of hydrocarbon reactions over Pt catalysts

FABIO H. RIBEIRO; ADRIAN L. BONIVARDI; GABOR A. SOMORJAI

CATALYSIS LETTERS

SPRINGER

Lugar: Berlin; Año: 1994 vol. 27 p. 1 - 10

1011-372X

The reactions of cyclohexane (6.7 kPa) andn-hexane (13.3 kPa) in H2 (450 kPa) were studied on platinum-rhenium model catalysts in the range 570?740 K. The catalysts were prepared by depositing rhenium on a platinum foil or platinum on a rhenium foil. The catalyst total area was 0.5?1.0 cm2. The surfaces were pre-sulfided before reaction and thiophene added to the feed to maintain the surface sulfided under reaction conditions. Sulfur binds with rhenium forming a catalytically inactive rhenium-sulfur compound. As the concentration of rhenium-sulfur on the surface is increased and the platinum ensembles become smaller, only dehydro-genation-hydrogenation activity is observed. However, the catalyst becomes more resistant to deactivation.