V. Koller¹, C. Sack¹, P. Lustemberg^2,3*, M. V. Ganduglia-Pirovano², H. Over¹

1 Physical Chemistry Department, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany

2 Institute of Catalysis and Petrochemistry, ICP, Spanish National Research Council, CSIC, 28049 Madrid, Spain

3 Institute of Physics Rosario, IFIR, National Scientific and Technical Research Council, CONICET, S2000EKF Rosario, Santa Fe, Argentina

* Corresponding authors emails: p.lustemberg@csic.es

DOI10.24435/materialscloud:1b-0f [version v1]

Publication date: May 24, 2022

How to cite this record

V. Koller, C. Sack, P. Lustemberg, M. V. Ganduglia-Pirovano, H. Over, Dynamic response of oxygen vacancies on the Deacon reaction over reduced single crystalline CeO₂-x(111) surfaces, Materials Cloud Archive 2022.67 (2022), doi: 10.24435/materialscloud:1b-0f.

Description

The heterogeneously catalyzed HCl oxidation reaction (Deacon reaction) over ceria leads under typical reaction conditions to a reduction and surface chlorination of CeO2. The reduced single crystalline CeO2-x(111) model surface stabilizes various ordered surface structures, e.g. (√7 × √7)R19.1°, (3 × 3), or (4 × 4), depending on the concentration of oxygen vacancies (VO). Saturating these phases with HCl at room temperature, followed by annealing to the process temperature of 700 K, leads in all cases to a uniformly covering (√3 × √3)R30° overlayer structure with identical Cl coverage and identical adsorption geometry. Low energy electron diffraction (LEED) fingerprinting, density functional theory (DFT) calculations and X-ray photoelectron spectroscopy (XPS) evidence that Cl adsorbs into the O-vacancy at the surface (Clvac) with a high adsorption energy (>2 eV). From thermal desorption spectroscopy (TDS) and XPS of Cl 2p the adsorption energy of Clvac and the water formation is found to dependent sensitively on the degree of bulk-reduction x of CeO2-x(111). Chlorine desorption in TDS shifts from 1175 K to 1320 K when the the reduction degree x is increased from CeO1.8(111) (x = 0.2) to CeO1.6(111) (x = 0.4). In order to rationalize why the formation of (√3 × √3)R30°-Clvac structure on CeO2-x(111) is independent of the original reduction degree x of CeO2 x(111), efficient diffusion of surface and bulk oxygen vacancies (VO) is required.

Materials Cloud sections using this data

Files

File name	Size	Description
README.txt MD5md5:7e4495b8dddf550ded6e0d4c7cb0a01f	2.0 KiB	Readme text, has the relevant information of the data uploaded to the repository
Surfaces_Models.zip MD5md5:ba27b5bb69a3c59a5b7605655ee47fac	61.5 MiB	Surfaces_Models.zip: It contains the 5 ceria (111) surface models as described in the manuscript
Chlorine_Adsorption.zip MD5md5:cf5ffcd5b11b71b26a806b0cf56d9a47	153.6 MiB	Chlorine_Adsorption.zip: It contains the 5 folders with Cl atoms adsorbed in the different models
Hydrogen_Adsorption.zip MD5md5:e0d69c085cdccb4b5b13a90cf9730431	14.8 MiB	Hydrogen_Adsorption.zip: It contains the 3 folders with H atoms adsorbed in the different models

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External references

Keywords

Reduced ceria Oxygen vacancy mobility Chlorine adsorption Deacon process HCl oxidation LEED fingerprinting