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Title: Chemistry of NO{sub 2} on CeO{sub 2} and MgO: Experimental and theoretical studies on the formation of NO{sub 3}

Abstract

In environmental catalysis the destruction or removal of nitrogen oxides (DeNOx process) is receiving a lot of attention. Synchrotron-based x-ray absorption near-edge spectroscopy, high-resolution photoemission, and first-principles density-functional calculations (DFT-GGA) were used to study the interaction of nitrogen dioxide with CeO{sub 2} and MgO. The only product of the reaction of NO{sub 2} with pure CeO{sub 2} at 300 K is adsorbed nitrate. The NO{sub 3} is a thermally stable species which mostly decomposes at temperatures between 450 and 600 K. For the adsorption of NO{sub 2} on partially reduced ceria (CeO{sub 2-x}), there is full decomposition of the adsorbate and a mixture of N, NO, and NO{sub 3} coexists on the surface of the oxide at room temperature. Ce{sup 3+} cations can assist in the transformation of NO and NO{sub 2} in DeNOx operations. Adsorbed NO{sub 3} (main product) and NO{sub 2} are detected after exposing MgO to NO{sub 2} gas. A partial NO{sub 2,ads}{yields}NO{sub 3,ads} transformation is observed on MgO(100) from 150 to 300 K. DFT-GGA calculations show strong bonding interactions for NO{sub 2} on Mg sites of this surface, and dicoordination via O, O is more favorable energetically than monocoordination via N. The NO{sub 2,ads} species disappearsmore » from magnesium oxide at temperatures below 600 K, whereas part of the NO{sub 3,ads} is stable up to temperatures near 800 K. MgO can be very useful as a sorbent for trapping NO{sub 2}. A general trend is found after comparing the chemical behavior of NO{sub 2} on different types of oxides (CeO{sub 2}, MgO, TiO{sub 2}, Fe{sub 2}O{sub 3}, CuO, ZnO). On all these systems, the main product after adsorbing NO{sub 2} at 300 K is nitrate with minor amounts of chemisorbed NO{sub 2} and no signs of full decomposition of the adsorbate. This trend and the results of DFT-GGA calculations indicate that NO{sub 2} is very efficient for the nitration (i.e., formation of NO{sub 3} as a ligand) of metal centers that are missing O neighbors in oxide surfaces. (c) 2000 American Institute of Physics.« less

Authors:
 [1];  [1];  [2];  [3];  [4]
  1. Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973 (United States)
  2. National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States)
  3. Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)
  4. Molecular Simulations Inc., 9685 Scranton Road, San Diego, California 92121 (United States)
Publication Date:
OSTI Identifier:
20216530
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 112; Journal Issue: 22; Other Information: PBD: 8 Jun 2000; Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; NITROGEN DIOXIDE; CERIUM OXIDES; CATALYSIS; MAGNESIUM OXIDES; ADSORBENTS; DECOMPOSITION; SURFACES; NITROGEN OXIDES; AUTOMOBILES; ENGINES; EXHAUST GASES; POLLUTANTS; EXPERIMENTAL DATA; THEORETICAL DATA

Citation Formats

Rodriguez, Jose A., Jirsak, Tomas, Sambasivan, Sharadha, Fischer, Daniel, and Maiti, Amitesh. Chemistry of NO{sub 2} on CeO{sub 2} and MgO: Experimental and theoretical studies on the formation of NO{sub 3}. United States: N. p., 2000. Web. doi:10.1063/1.481629.
Rodriguez, Jose A., Jirsak, Tomas, Sambasivan, Sharadha, Fischer, Daniel, & Maiti, Amitesh. Chemistry of NO{sub 2} on CeO{sub 2} and MgO: Experimental and theoretical studies on the formation of NO{sub 3}. United States. doi:10.1063/1.481629.
Rodriguez, Jose A., Jirsak, Tomas, Sambasivan, Sharadha, Fischer, Daniel, and Maiti, Amitesh. Thu . "Chemistry of NO{sub 2} on CeO{sub 2} and MgO: Experimental and theoretical studies on the formation of NO{sub 3}". United States. doi:10.1063/1.481629.
@article{osti_20216530,
title = {Chemistry of NO{sub 2} on CeO{sub 2} and MgO: Experimental and theoretical studies on the formation of NO{sub 3}},
author = {Rodriguez, Jose A. and Jirsak, Tomas and Sambasivan, Sharadha and Fischer, Daniel and Maiti, Amitesh},
abstractNote = {In environmental catalysis the destruction or removal of nitrogen oxides (DeNOx process) is receiving a lot of attention. Synchrotron-based x-ray absorption near-edge spectroscopy, high-resolution photoemission, and first-principles density-functional calculations (DFT-GGA) were used to study the interaction of nitrogen dioxide with CeO{sub 2} and MgO. The only product of the reaction of NO{sub 2} with pure CeO{sub 2} at 300 K is adsorbed nitrate. The NO{sub 3} is a thermally stable species which mostly decomposes at temperatures between 450 and 600 K. For the adsorption of NO{sub 2} on partially reduced ceria (CeO{sub 2-x}), there is full decomposition of the adsorbate and a mixture of N, NO, and NO{sub 3} coexists on the surface of the oxide at room temperature. Ce{sup 3+} cations can assist in the transformation of NO and NO{sub 2} in DeNOx operations. Adsorbed NO{sub 3} (main product) and NO{sub 2} are detected after exposing MgO to NO{sub 2} gas. A partial NO{sub 2,ads}{yields}NO{sub 3,ads} transformation is observed on MgO(100) from 150 to 300 K. DFT-GGA calculations show strong bonding interactions for NO{sub 2} on Mg sites of this surface, and dicoordination via O, O is more favorable energetically than monocoordination via N. The NO{sub 2,ads} species disappears from magnesium oxide at temperatures below 600 K, whereas part of the NO{sub 3,ads} is stable up to temperatures near 800 K. MgO can be very useful as a sorbent for trapping NO{sub 2}. A general trend is found after comparing the chemical behavior of NO{sub 2} on different types of oxides (CeO{sub 2}, MgO, TiO{sub 2}, Fe{sub 2}O{sub 3}, CuO, ZnO). On all these systems, the main product after adsorbing NO{sub 2} at 300 K is nitrate with minor amounts of chemisorbed NO{sub 2} and no signs of full decomposition of the adsorbate. This trend and the results of DFT-GGA calculations indicate that NO{sub 2} is very efficient for the nitration (i.e., formation of NO{sub 3} as a ligand) of metal centers that are missing O neighbors in oxide surfaces. (c) 2000 American Institute of Physics.},
doi = {10.1063/1.481629},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 22,
volume = 112,
place = {United States},
year = {2000},
month = {6}
}