Surface studies of WO/sub 3//Al/sub 2/O/sub 3/ and Ni/W/Al/sub 2/O/sub 3/ catalysts

Technical Report · Mon Dec 31 23:00:00 EST 1979

OSTI ID:6525418

This study has provided a comprehensive picture of the nature of the tungsten species present in WO/sub 3//Al/sub 2/O/sub 3/ and Ni/W/Al/sub 2/O/sub 3/ catalysts. It has been shown that WO/sub 3//Al/sub 2/O/sub 3/ and MoO/sub 3//Al/sub 2/O/sub 3/ catalysts are very similar structurally. Preliminary results for Ni/W/Al/sub 2/O/sub 3/ catalysts have shown that the promoting action of Ni is different than that of Co in Co/Mo/Al/sub 2/O/sub 3/ catalysts. Results led to the following conclusions: (1) At low loading (< 15% WO/sub 3/) the surface tungsten species is a tetrahedrally coordinated WO/sub 4//sup 2 -/ interaction complex. (2) Between 15 to 24% WO/sub 3/ a polymeric WO/sub 3/ (octahedral) species is formed in addition to the tetrahedral interaction species. (3) Above 24% WO/sub 3/ crystallites of bulk WO/sub 3/ formed on top of the tungsten monolayer. (4) No detectable amounts of Al/sub 2/ (WO/sub 4/)/sub 3/ were presented in any of the catalysts studied. (5) The tungsten interaction species are not reducible while the bulk WO/sub 3/ deposited above 24% WO/sub 3/ is reduced to metallic W. (6) Nickel ions are incorporated into the tungsten monolayer displacing a portion of the tungsten interaction species. (7) The nickel species are completely reduced to metallic Ni. (8) The comparative x-ray Photoelectron Spectroscopy (ESCA) Laser Raman Spectroscopy (LRS) and Low Energy Ion Scattering Spectroscopy (ISS) studies demonstrate the complimentary nature of these techniques for the study of heterogeneous catalysts. 6 figures, 3 tables.

• Research Organization: Pittsburgh Univ., PA (USA)
• DOE Contract Number: AC02-79ER10485
• OSTI ID: 6525418
• Report Number(s): DOE/ER/10485-T3; ON: DE83007299
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical &amp; Physicochemical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BINDING ENERGY
CATALYST SUPPORTS
CATALYSTS
CHALCOGENIDES
CHEMICAL REACTIONS
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY
LASER SPECTROSCOPY
METALS
NICKEL
NICKEL COMPOUNDS
NICKEL OXIDES
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
RAMAN SPECTRA
REDUCTION
RESEARCH PROGRAMS
SPECTRA
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNGSTEN
TUNGSTEN COMPOUNDS
TUNGSTEN OXIDES