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

Abstract

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 wasmore » 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.« less

Authors:
; ;  [1]
  1. Univ. of Akron, OH (United States)
Publication Date:
OSTI Identifier:
6651133
Resource Type:
Journal Article
Journal Name:
Journal of Catalysis; (United States)
Additional Journal Information:
Journal Volume: 148:2; Journal ID: ISSN 0021-9517
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Srinivas, G, Chuang, S S.C., and Debnath, S. An in situ infrared study of the reactivity of adsorbed NO and CO on Rh catalysts. United States: N. p., 1994. Web. doi:10.1006/jcat.1994.1261.
Srinivas, G, Chuang, S S.C., & Debnath, S. An in situ infrared study of the reactivity of adsorbed NO and CO on Rh catalysts. United States. https://doi.org/10.1006/jcat.1994.1261
Srinivas, G, Chuang, S S.C., and Debnath, S. Mon . "An in situ infrared study of the reactivity of adsorbed NO and CO on Rh catalysts". United States. https://doi.org/10.1006/jcat.1994.1261.
@article{osti_6651133,
title = {An in situ infrared study of the reactivity of adsorbed NO and CO on Rh catalysts},
author = {Srinivas, G and Chuang, S S.C. and Debnath, S},
abstractNote = {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.},
doi = {10.1006/jcat.1994.1261},
url = {https://www.osti.gov/biblio/6651133}, journal = {Journal of Catalysis; (United States)},
issn = {0021-9517},
number = ,
volume = 148:2,
place = {United States},
year = {1994},
month = {8}
}