An in situ infrared study of the reactivity of adsorbed NO and CO on Rh catalysts
- Univ. of Akron, OH (United States)
The reactivity of adsorbed NO and CO has been investigated by combined in situ infrared (IR) and mass spectroscopy (MS) on Rh/SiO[sub 2], Ce-Rh/SiO[sub 2], and oxidized Rh/SiO[sub 2] at 298-423 K. Exposure of preadsorbed CO to a gaseous NO pulse on Rh/SiO[sub 2], and Ce-Rh/SiO[sub 2] resulted in the desorption of linear CO and formation of a low wavenumber NO[sup [minus]] (1650-1700 cm[sup [minus]1]) species on the reduced Rh site; exposure of preadsorbed CO on oxidized Rh/SiO[sub 2] to a gaseous NO pulse resulted in the displacement of the gem-dicarbonyl without formation of CO[sub 2] at 298-423 K. Increasing NO exposure time led to the desorption of all adsorbed CO and formation of NO[sup +] species, a high wavenumber NO[sup [minus]] (1740-1770 cm[sup [minus]1]) species, and a bidentate nitrato species. Prolonged exposure of preadsorbed NO to CO resulted in displacement of the adsorbed NO[sup +] and chemisorption of CO as gem-dicarbonyl and a linear CO on Rh[sup +]. Exposure of the catalyst to a mixture of NO-CO-He (1:1:3) at 373 K and 0.1 MPa resulted in the formation of CO[sub 2]. The formation of CO[sub 2] from the reaction of adsorbed CO with oxygen produced from dissociated NO was more rapid than the desorption of adsorbed CO. The linear CO adsorbed on a Rh site with oxidation state greater than +1 may be a precursor towards CO[sub 2] formation. The increase in the rate of CO[sub 2] formation may be related to the increased coverage and reactivity of adsorbed species in the presence of gaseous NO and CO. 51 refs., 12 figs., 1 tab.
- OSTI ID:
- 6651133
- Journal Information:
- Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 148:2; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
330701 -- Emission Control-- Nitrogen Oxides
330702 -- Emission Control-- Carbon Monoxide
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ABSORPTION SPECTROSCOPY
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSTS
CATALYTIC EFFECTS
CERIUM
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CRYSTAL DOPING
ELEMENTS
KINETICS
MASS SPECTROSCOPY
METALS
MINERALS
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
RARE EARTHS
REACTION KINETICS
RHODIUM
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SPECTROSCOPY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TRANSITION ELEMENTS