The promoting effect of Nb2O5 addition to Pd/Al2O3 catalysts on propane oxidation

Pd/Nb2O5/Al2O3 catalysts were investigated on propane oxidation. Diffuse re flectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS) ana lysis suggested that monolayer coverage was attained between 10 and 20 wt.% of Nb2O5. Temperature programmed reduction (TPR) evidenced the partial red uction of niobium oxide. The maximum propane conversion observed on the Pd/ 10% Nb2O5/Al2O3 corresponded to the maximum Nb/Al surface ratio. The presen ce of NbOx polymeric structures near to the monolayer could favor the ideal Pd-0/Pd2+ surface ratio to the propane oxidation which could explain the p romoting effect of niobium oxide. (C)2000 Elsevier Science B.V. All rights reserved.