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Edvin Lundgren. Portrait.

Edvin Lundgren

Professor

Edvin Lundgren. Portrait.

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

Author

  • Volkmar Koller
  • Pablo G. Lustemberg
  • Alexander Spriewald-Luciano
  • Sabrina M. Gericke
  • Alfred Larsson
  • Christian Sack
  • Alexei Preobrajenski
  • Edvin Lundgren
  • M. Veronica Ganduglia-Pirovano
  • Herbert Over

Summary, in English

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.

Department/s

  • Combustion Physics
  • LU Profile Area: Light and Materials
  • LTH Profile Area: Nanoscience and Semiconductor Technology
  • Synchrotron Radiation Research
  • NanoLund: Centre for Nanoscience
  • MAX IV Laboratory
  • LTH Profile Area: Photon Science and Technology

Publishing year

2023-10-06

Language

English

Pages

12994-13007

Publication/Series

ACS Catalysis

Volume

13

Issue

19

Document type

Journal article

Publisher

The American Chemical Society (ACS)

Topic

  • Materials Chemistry

Keywords

  • Deacon process
  • displacement of strongly adsorbed chlorine
  • oxygen-induced dechlorination process
  • peroxo surface species
  • reduced ceria

Status

Published

ISBN/ISSN/Other

  • ISSN: 2155-5435