Structure sensitive selectivity of the NO-CO reaction over Rh single crystal surfaces

Conference · Tue Oct 01 00:00:00 EDT 1996

OSTI ID:370778

Peden, C H.F.; Herman, G S ^[1]; Belton, D N; Permana, H; Schmieg, S J ^[2]

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1. Pacific Northwest National Lab., Richland, WA (United States)
2. General Motors Research and Development Center, Warren, MI (United States)

We have studied the effects of temperature, NO conversion, and NO-CO ratio on the activity and selectivity of the NO-CO reaction at high (1 torr < P < 100 torr) pressures over the Rh(100), Rh(110) and Rh(111) single crystal surfaces. Although differences in the overall rate of NO reduction are significant but small, we find large differences between these three single crystal surfaces with regard to their selectivities for the two competitive nitrogen-containing products, N{sub 2}O vs. N{sub 2}. These differences can be understood in terms of the relative surface coverages of adsorbed NO and N-atoms during steady-state reaction. For example, higher N coverages favor N-atom recombination (N{sub 2} formation) more than the NO+N reaction (N{sub 2}O formation). A potentially important cause of varying steady-state coverages of adsorbed nitrogen-containing intermediate species may be differences in site-occupancies and, correspondingly, competition for these sites. We are investigating this possibility with the use of photoelectron diffraction where we are taking advantage of the quite different N(1s) binding energies for adsorbed NO and N-atoms.

• OSTI ID: 370778
• Report Number(s): CONF-960376--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
36 MATERIALS SCIENCE
54 ENVIRONMENTAL SCIENCES
ADSORPTION
AIR POLLUTION CONTROL
BINDING ENERGY
CARBON MONOXIDE
CATALYTIC EFFECTS
COMBUSTION PRODUCTS
EXHAUST GASES
GASEOUS WASTES
NITRIC OXIDE
NITROGEN
NITROUS OXIDE
PETROLEUM PRODUCTS
REDUCTION
RHODIUM
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE