Interaction of Carbon Monoxide with Pd/Nb and Pd/NbOx/Nb Systems

Jirsàk, Tomàš; Nikolajenko, V.; Knor, Z.

doi:10.1021/j100042a021

Cited by 4 publications

(1 citation statement)

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“…Carbon monoxide was adsorbed at room temperature by exposing the sample surface to ∼40 L of CO (p CO ) 5 × 10 -7 mbar for 60 s), expecting to saturate the palladium surface with CO. 9 Partial pressures of the desorbed CO (AMU 28) or CO 2 (AMU 44) molecules or Pd atoms (AMU 108) were measured by the quadrupole mass spectrometer. The heating rate during TPD measurements was 12 Ks -1 (73 Ks -1 in the case of Pd desorption).…”

Section: Methodsmentioning

confidence: 99%

Interaction of CO with Palladium Supported on Oxidized Tungsten

et al. 2006

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A model catalyst system, palladium on tungsten oxide, has been examined by temperature-programmed desorption and photoemission spectroscopy. The samples were prepared by evaporation of palladium onto an oxidized tungsten foil under ultrahigh vacuum conditions. Mostly three-dimensional (3-D) palladium (Pd) clusters were found to be present on oxidized tungsten (WOx) surfaces at room temperature. Upon annealing to 670 K, the palladium clusters are redispersed and decorated by the WOx surface layer. The nature of the WOx phase on top of the palladium clusters is dependent on the mode of oxidation of the tungsten foil prior to palladium deposition. Mainly W(2+) species decorate palladium deposits on tungsten oxidized at room temperature, while mainly W(4+) species are on top of palladium deposits on the surface oxidized at 1300 K. The appearance of a Pd(n+)-O-W(4+) mixed oxide phase with n < 2 was observed on the oxidized tungsten surface. The substantial reduction (relative to nonannealed samples) of molecular CO coverage induced by annealing is discussed in terms of the changes in chemical composition and morphology of the outermost surface.

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Section: Methodsmentioning

confidence: 99%