Adsorption of NO and CO an Rh/ZrO sub 2 (100)

Journal Article · Sat Nov 30 23:00:00 EST 1991 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(91)90148-W· OSTI ID:7076907

Zafiris, G S; Gorte, R J ^[1]

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1. Univ. of Pennsylvania, Philadelphia (United States)

The structure and adsorption properties of Rh films supported on a ZrO{sub 2}(100) crystal have been examined using Auger electron microscopy (TEM), and temperature programmed desorption (TPD) of NO and CO. For Rh vapor deposition at 300 K, film growth is close to two dimensional; however, metal particles are formed by heating above {approximately}500 K or exposure to air. Transmission electron diffraction (TED) indicates that the particles are preferentially oriented with respect to the substrate, which implies that interactions exist between the support and the Rh. TPD curves for CO are essentially independent of particle size and are similar to curves obtained on bulk Rh crystals. However, TPD curves for NO are strongly affected by particle size and film annealing. For particles between 3 and 10 nm formed by annealing, more than 98% of the NO dissociated during TPD from a saturation exposure. For the 10-nm particles, the TPD results were similar to curves on bulk metals in that N{sub 2} left the surface from two separate features: a sharp peak at 440 K due to NO{sub ad} + N{sub ad} = N{sub 2} + O{sub ad} and a broad feature between 450 and 700 K due to N{sub ad} recombination. For smaller particles, only the recombination feature was observed at approximately the same temperature. The implications of these results do not indicate strong electronic interactions between Rh and ZrO{sub 2}, but do suggest that Rh particle morphologies may be altered by ZrO{sub 2}, which could, in turn, affect catalytic properties.

• OSTI ID: 7076907
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 132:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330701 -- Emission Control-- Nitrogen Oxides
330702 -- Emission Control-- Carbon Monoxide
54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ADSORPTION
AIR POLLUTION CONTROL
ANNEALING
AUGER ELECTRON SPECTROSCOPY
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC CONVERTERS
CHALCOGENIDES
CHEMICAL REACTIONS
COATINGS
COHERENT SCATTERING
CONTROL
DESORPTION
DIFFRACTION
DISSOCIATION
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
ELECTRON SPECTROSCOPY
ELEMENTS
EQUIPMENT
FILMS
HEAT TREATMENTS
METALS
MICROSCOPY
MORPHOLOGY
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
OXIDES
OXYGEN COMPOUNDS
PARTICLE SIZE
PLATINUM METALS
POLLUTION CONTROL
POLLUTION CONTROL EQUIPMENT
REDUCTION
RHODIUM
SCATTERING
SIZE
SORPTION
SORPTIVE PROPERTIES
SPECTROSCOPY
SURFACE PROPERTIES
TEMPERATURE CONTROL
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TRANSMISSION ELECTRON MICROSCOPY
VAPOR DEPOSITED COATINGS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES