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Title: Chemisorption and reaction of NO and N{sub 2}O on oxidized and reduced ceria surfaces studied by soft X-ray photoemission spectroscopy and desorption spectroscopy

Abstract

The authors have examined the chemisorption and reaction of NO and N{sub 2}O on ceria surfaces by soft X-ray photoelectron spectroscopy (SXPS), X-ray absorption spectroscopy, and isothermal and temperature programmed desorption (TPD) spectroscopy. Samples include highly oriented CeO{sub 2}(100) and CeO{sup 2}(111) thin films with surfaces of variable oxidation states. CeO{sub 2}(111) thin films were grown in situ allowing control over the initial oxidation state of the ceria surface, quantitatively determinedly by valence band, Ce 4d, and Ce 3d photoemission. Following NO exposure, various N-containing surface species were observed by N 1s photoemission, and the distribution of these species depended upon surface oxidation state, exposure, and adsorption temperature. These species included N{sub 2}O, nitrite, NO{sup {minus}}, and three states believed to be associated with atomic or anionic forms of N. Nitrite and N{sub 2}O are seen on a fully oxidized surface while NO{sup {minus}}, N{sub 2}O, and dissociation products are observed on a reduced surface. The primary reaction of NO with reduced ceria is reoxidation of the ceria by the NO, both by NO{sup {minus}} formation and by NO dissociation, leading to immediate and thermally induced N{sub 2} desorption. Adsorption of NO at 150 K is predominantly molecular while exposuremore » to NO at 400 K leads to a thermally activated nitride which desorbs at temperatures above 500 K. Dissociative adsorption of NO leads to the displacement of N{sup 3{minus}} at high exposures.« less

Authors:
; ; ;  [1]
  1. Oak Ridge National Lab., TN (United States)
Publication Date:
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
687741
DOE Contract Number:  
AC05-96OR22464; AC02-76CH00016
Resource Type:
Journal Article
Journal Name:
Journal of Catalysis
Additional Journal Information:
Journal Volume: 186; Journal Issue: 2; Other Information: PBD: 10 Sep 1999
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 33 ADVANCED PROPULSION SYSTEMS; NITRIC OXIDE; NITROUS OXIDE; CHEMISORPTION; CERIUM OXIDES; SORPTIVE PROPERTIES; REDUCTION; AIR POLLUTION CONTROL

Citation Formats

Overbury, S.H., Mullins, D.R., Huntley, D.R., and Kundakovic, L. Chemisorption and reaction of NO and N{sub 2}O on oxidized and reduced ceria surfaces studied by soft X-ray photoemission spectroscopy and desorption spectroscopy. United States: N. p., 1999. Web. doi:10.1006/jcat.1999.2577.
Overbury, S.H., Mullins, D.R., Huntley, D.R., & Kundakovic, L. Chemisorption and reaction of NO and N{sub 2}O on oxidized and reduced ceria surfaces studied by soft X-ray photoemission spectroscopy and desorption spectroscopy. United States. doi:10.1006/jcat.1999.2577.
Overbury, S.H., Mullins, D.R., Huntley, D.R., and Kundakovic, L. Fri . "Chemisorption and reaction of NO and N{sub 2}O on oxidized and reduced ceria surfaces studied by soft X-ray photoemission spectroscopy and desorption spectroscopy". United States. doi:10.1006/jcat.1999.2577.
@article{osti_687741,
title = {Chemisorption and reaction of NO and N{sub 2}O on oxidized and reduced ceria surfaces studied by soft X-ray photoemission spectroscopy and desorption spectroscopy},
author = {Overbury, S.H. and Mullins, D.R. and Huntley, D.R. and Kundakovic, L.},
abstractNote = {The authors have examined the chemisorption and reaction of NO and N{sub 2}O on ceria surfaces by soft X-ray photoelectron spectroscopy (SXPS), X-ray absorption spectroscopy, and isothermal and temperature programmed desorption (TPD) spectroscopy. Samples include highly oriented CeO{sub 2}(100) and CeO{sup 2}(111) thin films with surfaces of variable oxidation states. CeO{sub 2}(111) thin films were grown in situ allowing control over the initial oxidation state of the ceria surface, quantitatively determinedly by valence band, Ce 4d, and Ce 3d photoemission. Following NO exposure, various N-containing surface species were observed by N 1s photoemission, and the distribution of these species depended upon surface oxidation state, exposure, and adsorption temperature. These species included N{sub 2}O, nitrite, NO{sup {minus}}, and three states believed to be associated with atomic or anionic forms of N. Nitrite and N{sub 2}O are seen on a fully oxidized surface while NO{sup {minus}}, N{sub 2}O, and dissociation products are observed on a reduced surface. The primary reaction of NO with reduced ceria is reoxidation of the ceria by the NO, both by NO{sup {minus}} formation and by NO dissociation, leading to immediate and thermally induced N{sub 2} desorption. Adsorption of NO at 150 K is predominantly molecular while exposure to NO at 400 K leads to a thermally activated nitride which desorbs at temperatures above 500 K. Dissociative adsorption of NO leads to the displacement of N{sup 3{minus}} at high exposures.},
doi = {10.1006/jcat.1999.2577},
journal = {Journal of Catalysis},
number = 2,
volume = 186,
place = {United States},
year = {1999},
month = {9}
}