The surface chemistry of vanadium oxide catalysts
The surface chemistry of vanadium oxide catalysts was studied using UHV surface techniques and catalytic experiments at atmospheric pressure. In UHV, vanadium oxide films were grown on single crystal vanadium, Au(111), and Au foil substrates. Silica supported V{sub 2}O{sub 5} was used in the catalytic experiments. Auger electron spectroscopy and low energy electron spectroscopy revealed temperature dependent surface segregation of contaminants on the V(110) surface. Several cleaning procedures were used to remove persistent sulfur contamination. Vanadium oxide films grown on a Au(111) substrate were ordered. The growth mode and preparation of these films is discussed. The structure and Auger spectrum of the films were consistent with a V{sub 2}O{sub 3} surface. The TPD of hydrogen, ethanol, and ethylene were examined on this surface. The peak temperatures for the desorption of H{sub 2}O, CO, and CO{sub 2} were sensitive to the surface oxidation state. Polycrystalline V{sub 2}O{sub 5} supported on Au foil was also studied. Two water desorption peaks were observed after the adsorption of predissociated hydrogen. CO, CO{sub 2}, and C{sub 2}H{sub 4} were the principle desorption products after ethanol adsorption in UHV and at atmospheric pressure. The partial oxidation of methane and ethanol over V{sub 2}O{sub 5}-SiO{sub 2} was investigated. Methane oxidation with N{sub 2}O proceeded very slowly, however activation energies and rate laws were determined. Ethanol oxidation with O{sub 2} was more rapid. Catalyst dispersion were measured using irreversible oxygen uptake following reduction at 641 K. Ethanol partial oxidation was structure insensitive. The catalytic results were consistent with the UHV results from gold-supported samples.
- Research Organization:
- California Univ., Berkeley, CA (USA)
- OSTI ID:
- 6761029
- Country of Publication:
- United States
- Language:
- English
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ACTIVATION ENERGY
ADSORPTION
ALCOHOLS
ALKALI METALS
ALKANES
ALKENES
ARGON
ATMOSPHERIC PRESSURE
AUGER ELECTRON SPECTROSCOPY
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COHERENT SCATTERING
CONTROL
DESORPTION
DIFFRACTION
ELECTRON DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY
ETHANOL
ETHYLENE
FILMS
FLUIDS
GASES
GOLD
HEAT TREATMENTS
HYDROCARBONS
HYDROGEN
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
IMPURITIES
KINETICS
METALS
METHANE
MINERALS
NITROGEN COMPOUNDS
NITROGEN OXIDES
NITROUS OXIDE
NONMETALS
ORGANIC COMPOUNDS
OXIDATION
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PARTIAL OXIDATION PROCESSES
POTASSIUM
RARE GASES
REACTION KINETICS
SCATTERING
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
SPECTROSCOPY
SULFUR
SURFACE PROPERTIES
SYNTHESIS
TEMPERATURE CONTROL
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
VANADIUM
VANADIUM COMPOUNDS
VANADIUM OXIDES
WATER