XPS and Auger studies of selected Zr/Ni intermetallic alloy catalysts

Conference · Wed Jan 01 04:00:00 EST 1986

OSTI ID:5145756

Wright, R B; Hankins, M R; Owens, M S; Cocke, D L

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
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ALLOYS
AUGER ELECTRON SPECTROSCOPY
CATALYSTS
CHEMICAL REACTIONS
ELECTRON SPECTROSCOPY
ELEMENTS
HEAT TREATMENTS
HYDROGEN
INTERMETALLIC COMPOUNDS
NICKEL ALLOYS
NONMETALS
OXIDATION
OXYGEN
PHOTOELECTRON SPECTROSCOPY
REDUCTION
SPECTROSCOPY
SURFACE PROPERTIES
ZIRCONIUM ALLOYS