XPS and Auger studies of selected Zr/Ni intermetallic alloy catalysts
Various intermetallic alloys of Zr/Ni have been studied with regard to their surface compositions using Auger and XPS spectroscopies as a function of elevated temperature exposure to hydrogen and oxygen gas. ZrNi/sub 5/, Zr/sub 2/Ni/sub 7/, ZrNi/sub 3/, ZrNi and Zr/sub 2/Ni, prepared by arc melting, were studied either as powders or as slices of the arc melted sample button. The elevated temperature treatments were chosen to duplicate the sample treatment these alloys received prior to catalytic hydrogenation. The alloys were sequentially analyzed with XPS and/or Auger techniques after the following representative treatment cycle: As-prepared; 400/sup 0/C H/sub 2/; 400/sup 0/C O/sub 2/; and a final 400/sup 0/C H/sub 2/ exposure. In general, the as-prepared alloys are depleted in nickel at the surface (as compared to the bulk) and the alloys have been decomposed into a mixed Ni (or NiO) and ZrO/sub 2/ surface layer residing on the bulk alloy. After the elevated temperature H/sub 2/ treatment the NiO (if present) is reduced to Ni (>200/sup 0/C) and additional ZrO/sub 2/ is formed. Elevated temperature O/sub 2/ treatment causes additional Ni to segregate to the surface and form NiO (>200/sup 0/C), which is reduced to Ni after the final 400/sup 0/C H/sub 2/ treatment. After this general sequence of treatments, three alloys (ZrNi/sub 5/, Zr/sub 2/Ni/sub 7/, and Zr/sub 2/Ni) were found to have greater Ni surface concentrations than their corresponding bulk composition. These results follow the measured catalytic hydrogenation of ethylene to ethane activities which indicate that the higher the surface nickel concentration the greater the catalytic hydrogenation activity.
- Research Organization:
- EG and G Idaho, Inc., Idaho Falls (USA); Texas A and M Univ., College Station (USA). Dept. of Chemistry
- DOE Contract Number:
- AC07-76ID01570
- OSTI ID:
- 5145756
- Report Number(s):
- EGG-M-28086; CONF-861019-9; ON: DE87001434
- Resource Relation:
- Conference: 10. international vacuum congress and 6. international conference on solid surfaces and the 33. national symposium of the American Vacuum Society, Baltimore, MD, USA, 27 Oct 1986; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NICKEL ALLOYS
SURFACE PROPERTIES
ZIRCONIUM ALLOYS
AUGER ELECTRON SPECTROSCOPY
CATALYSTS
HEAT TREATMENTS
HYDROGEN
INTERMETALLIC COMPOUNDS
OXIDATION
OXYGEN
PHOTOELECTRON SPECTROSCOPY
REDUCTION
ALLOYS
CHEMICAL REACTIONS
ELECTRON SPECTROSCOPY
ELEMENTS
NONMETALS
SPECTROSCOPY
360104* - Metals & Alloys- Physical Properties