Transition metal oxides deposited on rhodium and platinum: Surface chemistry and catalysis

Thesis/Dissertation · Fri Jul 01 00:00:00 EDT 1994

DOI:https://doi.org/10.2172/10186279· OSTI ID:10186279

Boffa, Alexander Bowman ^[1]

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1. Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

The surface chemistry and catalytic reactivity of transition metal oxides deposited on Rh and Pt substrates has been examined in order to establish the role of oxide-metal interactions in influencing catalytic activity. The oxides investigated included titanium oxide (TiOx), vanadium oxide (VOx), iron oxide (FeOx), zirconium oxide (ZrOx), niobium oxide (NbOx), tantalum oxide (TaOx), and tungsten oxide (WOx). The techniques used to characterize the sample included AES, XPS, LEED, TPD, ISS, and STM. After characterization of the surface in UHV, the sample was enclosed in an atmospheric reaction cell to measure the influence of the oxide deposits on the catalytic activity of the pure metal for CO and CO₂ hydrogenation. The oxide deposits were found to strongly enhance the reactivity of the Rh foil. The rates of methane formation were promoted by up to 15 fold with the maximum in rate enhancement occurring at oxide coverages of approximately 0.5 ML. TiOx TaOx, and NbOx were the most effective promoters and were stable in the highest oxidation states during both reactions (compared to VOx, WOx, and FeOx). The trend in promoter effectiveness was attributed to the direct relationship between oxidation state and Lewis acidity. Bonding at the metal oxide/metal interface between the oxygen end of adsorbed CO and the Lewis acidic oxide was postulated to facilitate C-O bond dissociation and subsequent hydrogenation. 192 refs.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 10186279
• Report Number(s): LBL-35954; ON: DE95000793; TRN: AHC29424%%62
• Resource Relation: Other Information: TH: Thesis (Ph.D.); PBD: Jul 1994
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
10 SYNTHETIC FUELS
01 COAL, LIGNITE, AND PEAT
TITANIUM OXIDES
CATALYTIC EFFECTS
VANADIUM OXIDES
IRON OXIDES
TUNGSTEN OXIDES
ZIRCONIUM OXIDES
NIOBIUM OXIDES
TANTALUM OXIDES
CARBON MONOXIDE
METHANATION
CARBON DIOXIDE
CATALYSTS
CATALYST SUPPORTS
CONFIGURATION INTERACTION
CHEMICAL ANALYSIS
AUGER ELECTRON SPECTROSCOPY
PHOTOELECTRON SPECTROSCOPY
ELECTRON DIFFRACTION
ION SCATTERING ANALYSIS
MICROSCOPY
DESORPTION
TEMPERATURE CONTROL
EXPERIMENTAL DATA
400201
100200
010408
CHEMICAL AND PHYSICOCHEMICAL PROPERTIES
PRODUCTION
C1 PROCESSES