An in situ infrared study of the reactivity of adsorbed NO and CO on Rh catalysts

Journal Article · Mon Aug 01 00:00:00 EDT 1994 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1994.1261· OSTI ID:6651133

Srinivas, G; Chuang, S S.C.; Debnath, S ^[1]

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1. 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), Vol. 148:2; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
33 ADVANCED PROPULSION SYSTEMS
CARBON MONOXIDE
CHEMICAL REACTIONS
NITRIC OXIDE
RHODIUM
CATALYTIC EFFECTS
ABSORPTION SPECTROSCOPY
CATALYSTS
CERIUM
CHEMICAL REACTION KINETICS
CRYSTAL DOPING
MASS SPECTROSCOPY
SILICA
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
ELEMENTS
KINETICS
METALS
MINERALS
NITROGEN COMPOUNDS
NITROGEN OXIDES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
RARE EARTHS
REACTION KINETICS
SILICON COMPOUNDS
SILICON OXIDES
SPECTROSCOPY
TEMPERATURE RANGE
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties
330701 - Emission Control- Nitrogen Oxides
330702 - Emission Control- Carbon Monoxide