Kinetics of Oxygen Exchange over CeO2-ZrO2 Fluorite-Based Catalysts Full article
| Journal |
The Journal of Physical Chemistry A
ISSN: 1089-5639 , E-ISSN: 1520-5215 |
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| Output data | Year: 2007, Volume: 111, Number: 20, Pages: 4498-4505 Pages count : 8 DOI: 10.1021/jp0687706 | ||||
| Tags | Adsorption; Catalysts; Desorption; Oxygen; Reaction kinetics; Zirconia | ||||
| Authors |
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| Affiliations |
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Funding (1)
| 1 | Russian Foundation for Basic Research | 05-03-34761 |
Abstract:
The kinetics of 18O/16O isotopic exchange over CeO2−ZrO2−La2O3 and Pt/CeO2−ZrO2 catalysts have been investigated under the conditions of dynamic adsorption−desorption equilibrium at atmospheric pressure and a temperature range of 650−850 °C. The rates of oxygen adsorption−desorption on Pt sites, support surface, oxygen transfer (spillover) from Pt to the support as well as the amount of oxygen accumulated in the oxide bulk, and oxygen diffusion coefficient were estimated. The nanocrystalline structure of lanthana-doped ceria-zirconia prepared via the Pechini route with a developed network of domain boundaries and specific defects guarantees a high oxygen mobility in the oxide bulk (D = (1.5 ÷ 2.0)·10-18 m2 s-1 at 650 °C) and allows accumulation of over-stoichiometric/excess oxygen. For Pt/CeO2−ZrO2, oxygen transfer from Pt to support (characteristic time < 10-2 s) was shown to be responsible for the fast exchange between the gas-phase oxygen and oxygen adsorbed on the mixed oxide surface. The rate of direct exchange between the phase and surface oxygen is increased as well due to the increased concentration (up to 2 monolayers) of surface/near subsurface oxygen species accumulated on the oxygen vacancies (originated from the incorporation of highly dispersed Pt atoms). The characteristic time of diffusion of the oxygen localized in the subsurface layers is about 1 s. The overall quantity of over-stoichiometric oxygen and/or hydroxyl groups accumulated in the bulk can reach the equivalent of 10 monolayers, and characteristic time of oxygen diffusion within the bulk is about 20 s. All these kinetic data are required for the further step of modeling partial oxidation of hydrocarbons under steady- and unsteady-state conditions.
Cite:
Sadovskaya E.M.
, Ivanova Y.A.
, Pinaeva L.G.
, Grasso G.
, Kuznetsova T.G.
, van Veen A.
, Sadykov V.A.
, Mirodatos C.
Kinetics of Oxygen Exchange over CeO2-ZrO2 Fluorite-Based Catalysts
The Journal of Physical Chemistry A. 2007. V.111. N20. P.4498-4505. DOI: 10.1021/jp0687706 WOS Scopus РИНЦ ANCAN PMID OpenAlex
Kinetics of Oxygen Exchange over CeO2-ZrO2 Fluorite-Based Catalysts
The Journal of Physical Chemistry A. 2007. V.111. N20. P.4498-4505. DOI: 10.1021/jp0687706 WOS Scopus РИНЦ ANCAN PMID OpenAlex
Dates:
| Submitted: | Dec 20, 2006 |
| Accepted: | Mar 5, 2007 |
| Published print: | May 1, 2007 |
| Published online: | May 2, 2007 |
Identifiers:
| Web of science: | WOS:000246569300048 |
| Scopus: | 2-s2.0-34250180228 |
| Elibrary: | 13537894 |
| Chemical Abstracts: | 2007:477612 |
| Chemical Abstracts (print): | 147:80472 |
| PMID: | 17472353 |
| OpenAlex: | W2013823625 |