Journalartikel

Jahr der Veröffentlichung: 2022

Seiten: 13202-13212

Zeitschrift: Journal of Physical Chemistry C

Bandnummer: 126

Heftnummer: 31

ISSN: 1932-7447

eISSN: 1932-7455

DOI Link: https://doi.org/10.1021/acs.jpcc.2c03821

Verlag: American Chemical Society

Abstract: 

The heterogeneously catalyzed HCl oxidation reaction (Deacon reaction) that produces chlorine and the byproduct water leads to a reduction and surface chlorination of the ceria (CeO₂) catalyst under typical reaction conditions. The interaction of HCl with reduced ceria can be modeled with a reduced single crystalline CeO_2–x(111) model surface that is able to stabilize various ordered surface structures, e.g., (√7 × √7)R19.1°, (3 × 3), or (4 × 4), depending on the concentration of oxygen vacancies (V_O). Saturating these phases with HCl at room temperature, followed by annealing to the Deacon process temperature of 700 K, results in all cases in a uniformly covering (√3 × √3)R30°-Cl_vac overlayer structure with identical adsorption geometry and Cl coverage. Low energy electron diffraction (LEED) fingerprinting, density functional theory (DFT) calculations, and X-ray photoelectron spectroscopy (XPS) indicate that Cl adsorbs in the surface oxygen vacancies (Cl_vac) with a high adsorption energy (>2 eV). From thermal desorption spectroscopy (TDS) and XPS of Cl 2p, it is found that both the adsorption energy of Cl_vac and the water formation ability depend on the degree of reduction x of CeO_2–x(111). TDS spectra show that chlorine desorption shifts from 1175 to 1320 K when the degree of reduction x is increased from CeO_1.8(111) (x = 0.2) to CeO_1.6(111) (x = 0.4). In order to rationalize why the formation of the (√3 × √3)R30°-Cl_vac structure on CeO_2–x(111) is independent of the original degree of reduction x of CeO_2–x(111), efficient diffusion of surface and bulk oxygen vacancies is required.

Harvard-Zitierstil: Koller, V., Sack, C., Lustemberg, P., V. Ganduglia-Pirovano, M. and Over, H. (2022) Dynamic Response of Oxygen Vacancies in the Deacon Reaction over Reduced Single Crystalline CeO2-x(111) Surfaces, Journal of Physical Chemistry C, 126(31), pp. 13202-13212. https://doi.org/10.1021/acs.jpcc.2c03821

APA-Zitierstil: Koller, V., Sack, C., Lustemberg, P., V. Ganduglia-Pirovano, M., & Over, H. (2022). Dynamic Response of Oxygen Vacancies in the Deacon Reaction over Reduced Single Crystalline CeO2-x(111) Surfaces. Journal of Physical Chemistry C. 126(31), 13202-13212. https://doi.org/10.1021/acs.jpcc.2c03821