XPS study of metal-support interactions on Pd/SiO/sub 2/ and Pd/La/sub 2/O/sub 3/

Journal Article · Fri Jun 01 04:00:00 UTC 1984 · J. Catal.; (United States)

OSTI ID:6196270

Fleisch, T H; Hicks, R F; Bell, A T

The electronic properties of palladium supported on SiO/sub 2/ and La/sub 2/O/sub 3/ were investigated by X-ray photoelectron spectroscopy. Spectra were collected after each stage of catalyst preparation: deposition of the palladium chloride precursor, oxidation in air at 623 K, and reduction in H/sub 2/ at 573 K. The Pd 3d/sub 5/2/ binding energies recorded following precursor deposition and oxidation were the same on both catalysts. However, after reduction the Pd 3d/sub 5/2/ binding energies of the Pd/La/sub 2/O/sub 3/ samples shifted below the corresponding values for metallic Pd, while the Pd 3d/sub 5/2/ binding energies of the Pd/SiO/sub 2/ samples did not. Furthermore, the binding energies for the Pd/La/sub 2/O/sub 3/ samples decreased with increasing metal loading, the largest Pd particles apparently exhibiting the greatest interaction. A maximum shift of -0.7 eV relative to the Pd foil value was observed for 8.8% Pd/La/sub 2/O/sub 3/. This binding energy shift is interpreted as arising from a change in the chemical state of Pd, i.e., that Pd supported on La/sub 2/O/sub 3/ is more electronegative than zero-valent Pd alone. A model is proposed which suggests that a thin covering of the La/sub 2/O/sub 3/ support lies on a portion of the Pd surface. The exact composition of the support depended strongly on the reduction temperature and the amount of Pd deposited. 49 references, 13 figures, 9 tables.

• Research Organization: Amoco Research Center, Naperville, IL
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6196270
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 87:2; ISSN JCTLA
• Country of Publication: United States
• Language: English

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CATALYST SUPPORTS
CATALYSTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
ELECTRON SPECTROSCOPY
ELECTRONIC STRUCTURE
ELEMENTS
EXPERIMENTAL DATA
HYDROGEN
INFORMATION
KINETICS
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
METALS
MINERALS
NONMETALS
NUMERICAL DATA
OXIDATION
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PALLADIUM
PHOTOELECTRON SPECTROSCOPY
PLATINUM METALS
RARE EARTH COMPOUNDS
REACTION KINETICS
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SPECTRA
SPECTROSCOPY
SURFACE PROPERTIES
TEMPERATURE EFFECTS
TRANSITION ELEMENTS
X-RAY SPECTRA
X-RAY SPECTROSCOPY