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Critical Step in the HCl Oxidation Reaction over Single-Crystalline CeO2-x(111) : Peroxo-Induced Site Change of Strongly Adsorbed Surface Chlorine

Koller, Volkmar ; Lustemberg, Pablo G. ; Spriewald-Luciano, Alexander ; Gericke, Sabrina M. LU ; Larsson, Alfred LU ; Sack, Christian ; Preobrajenski, Alexei LU ; Lundgren, Edvin LU ; Ganduglia-Pirovano, M. Veronica and Over, Herbert (2023) In ACS Catalysis 13(19). p.12994-13007
Abstract

The catalytic oxidation of HCl by molecular oxygen (Deacon process) over ceria allows the recovery of molecular chlorine from the omnipresent HCl waste produced in various industrial processes. In previous density functional theory (DFT) model-calculations by Amrute et al. [ J. Catal. 2012, 286, 287−297.], it was proposed that the most critical reaction step in this process is the displacement of tightly bound chlorine at a vacant oxygen position on the CeO2(111) surface (Clvac) toward a less strongly bound cerium on-top (Cltop) position. This step is highly endothermic by more than 2 eV. On the basis of a dedicated model study, namely the reoxidation of a chlorinated single-crystalline... (More)

The catalytic oxidation of HCl by molecular oxygen (Deacon process) over ceria allows the recovery of molecular chlorine from the omnipresent HCl waste produced in various industrial processes. In previous density functional theory (DFT) model-calculations by Amrute et al. [ J. Catal. 2012, 286, 287−297.], it was proposed that the most critical reaction step in this process is the displacement of tightly bound chlorine at a vacant oxygen position on the CeO2(111) surface (Clvac) toward a less strongly bound cerium on-top (Cltop) position. This step is highly endothermic by more than 2 eV. On the basis of a dedicated model study, namely the reoxidation of a chlorinated single-crystalline Clvac-CeO2-x(111)-(Formula Presented × Formula Presented)R30° surface structure, we provide in situ synchrotron-based spectroscopic data (high resolution core level spectroscopy (HRCLS) and X-ray adsorption near edge structure (XANES)) for this oxygen-induced dechlorination process. Combined with theoretical evidence from DFT calculations, the Clvac → Cltop displacement reaction is predicted to be induced by an adsorbed peroxo species (O22-), making the displacement step concerted and exothermic by 0.6 eV with an activation barrier of only 1.04 eV. The peroxo species is shown to be important for the reoxidation of Clvac-CeO2-x(111) and is considered essential for understanding the function of ceria in oxidation catalysis.

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; ; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Deacon process, displacement of strongly adsorbed chlorine, oxygen-induced dechlorination process, peroxo surface species, reduced ceria
in
ACS Catalysis
volume
13
issue
19
pages
14 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85174812867
ISSN
2155-5435
DOI
10.1021/acscatal.3c03222
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2023 The Authors. Published by American Chemical Society.
id
1ced7c6a-f39c-4ccf-885b-7f272a998217
date added to LUP
2023-12-13 15:40:12
date last changed
2024-02-09 10:38:09
@article{1ced7c6a-f39c-4ccf-885b-7f272a998217,
  abstract     = {{<p>The catalytic oxidation of HCl by molecular oxygen (Deacon process) over ceria allows the recovery of molecular chlorine from the omnipresent HCl waste produced in various industrial processes. In previous density functional theory (DFT) model-calculations by Amrute et al. [ J. Catal. 2012, 286, 287−297.], it was proposed that the most critical reaction step in this process is the displacement of tightly bound chlorine at a vacant oxygen position on the CeO<sub>2</sub>(111) surface (Cl<sub>vac</sub>) toward a less strongly bound cerium on-top (Cl<sub>top</sub>) position. This step is highly endothermic by more than 2 eV. On the basis of a dedicated model study, namely the reoxidation of a chlorinated single-crystalline Cl<sub>vac</sub>-CeO<sub>2-x</sub>(111)-(Formula Presented × Formula Presented)R30° surface structure, we provide in situ synchrotron-based spectroscopic data (high resolution core level spectroscopy (HRCLS) and X-ray adsorption near edge structure (XANES)) for this oxygen-induced dechlorination process. Combined with theoretical evidence from DFT calculations, the Cl<sub>vac</sub> → Cl<sub>top</sub> displacement reaction is predicted to be induced by an adsorbed peroxo species (O<sub>2</sub><sup>2-</sup>), making the displacement step concerted and exothermic by 0.6 eV with an activation barrier of only 1.04 eV. The peroxo species is shown to be important for the reoxidation of Cl<sub>vac</sub>-CeO<sub>2-x</sub>(111) and is considered essential for understanding the function of ceria in oxidation catalysis.</p>}},
  author       = {{Koller, Volkmar and Lustemberg, Pablo G. and Spriewald-Luciano, Alexander and Gericke, Sabrina M. and Larsson, Alfred and Sack, Christian and Preobrajenski, Alexei and Lundgren, Edvin and Ganduglia-Pirovano, M. Veronica and Over, Herbert}},
  issn         = {{2155-5435}},
  keywords     = {{Deacon process; displacement of strongly adsorbed chlorine; oxygen-induced dechlorination process; peroxo surface species; reduced ceria}},
  language     = {{eng}},
  month        = {{10}},
  number       = {{19}},
  pages        = {{12994--13007}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{ACS Catalysis}},
  title        = {{Critical Step in the HCl Oxidation Reaction over Single-Crystalline CeO<sub>2-x</sub>(111) : Peroxo-Induced Site Change of Strongly Adsorbed Surface Chlorine}},
  url          = {{http://dx.doi.org/10.1021/acscatal.3c03222}},
  doi          = {{10.1021/acscatal.3c03222}},
  volume       = {{13}},
  year         = {{2023}},
}