Self-Sustained Oscillations in Oxidation of Methane over Palladium: Experimental Study and Mathematical Modeling Full article
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Journal of Chemical Physics
ISSN: 0021-9606 , E-ISSN: 1089-7690 |
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| Output data | Year: 2022, Volume: 157, Number: 4, Article number : 044703, Pages count : 14 DOI: 10.1063/5.0097251 | ||||
| Tags | IN-SITU XPS; CATALYTIC-OXIDATION; KINETIC OSCILLATIONS; CARBON-MONOXIDE; Pd K; BEHAVIOR; NICKEL; Pd/Al2O3; PROPANE; HYDROGENATION | ||||
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| Affiliations |
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Funding (1)
| 1 | Ministry of Science and Higher Education of the Russian Federation | 075-15-2022-263 |
Abstract:
An experimental study of the catalytic oxidation of methane over Pd foil in a flow reactor revealed that regular temporal oscillations in the reaction rate can arise at atmospheric pressure under methane-rich conditions. CO, CO2, H2, and H2O were detected as products. The oscillations of partial pressures of products and reactants in the gas phase were accompanied by oscillations of the catalyst temperature. According to an operando x-ray diffraction and mass-spectrometry study, the oscillations originate due to spontaneous oxidation and reduction of palladium; the high active catalyst surface is represented by metallic palladium, and the transition to the low-active state is accompanied by the formation of the PdO phase. In addition, it was detected that carbon dissolves in near-surface layers of palladium to form the PdCx phase. To describe the oscillations in the oxidation of methane, a 17-step reaction mechanism and a corresponding kinetic model were developed. The mechanism considers direct dissociative adsorption of methane and oxygen, pyrolytic activation of methane, oxidation and reduction of palladium, and direct formation and desorption of CO, CO2, H2, and H2O. Numerical solutions from the mathematical model of the continuously stirred-tank reactor qualitatively reproduce experimentally observed oscillatory dynamics. We have also developed a model, which considers the reversible diffusion of adsorbed oxygen and carbon atoms into the Pd bulk that allows us to explain the long induction period preceding the appearance of the oscillations. Mathematical modeling shows that the concentrations of dissolved oxygen and carbon atoms also oscillate under reaction conditions. © 2022 Author(s).
Cite:
Lashina E.A.
, Vinokurov Z.S.
, Saraev A.A.
, Kaichev V.V.
Self-Sustained Oscillations in Oxidation of Methane over Palladium: Experimental Study and Mathematical Modeling
Journal of Chemical Physics. 2022. V.157. N4. 044703 :1-14. DOI: 10.1063/5.0097251 WOS Scopus РИНЦ AN PMID OpenAlex publication_identifier_short.sciact_skif_identifier_type
Self-Sustained Oscillations in Oxidation of Methane over Palladium: Experimental Study and Mathematical Modeling
Journal of Chemical Physics. 2022. V.157. N4. 044703 :1-14. DOI: 10.1063/5.0097251 WOS Scopus РИНЦ AN PMID OpenAlex publication_identifier_short.sciact_skif_identifier_type
Dates:
| Submitted: | Apr 27, 2022 |
| Accepted: | Jul 4, 2022 |
| Published print: | Jul 28, 2022 |
| Published online: | Aug 1, 2022 |
Identifiers:
| Web of science: | WOS:000835325400020 |
| Scopus: | 2-s2.0-85135434160 |
| Elibrary: | 50518905 |
| Chemical Abstracts: | 2022:2053422 |
| PMID: | 35922353 |
| OpenAlex: | W4283809510 |
| publication_identifier.sciact_skif_identifier_type: | 1476 |