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Hydrogen-Assisted 1,2-Dichloroethane Dechlorination Catalyzed by Pt-Cu/SiO2: Insights into the Nature of Ethylene-Selective Active Sites
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Библиографическое описание: Hydrogen-Assisted 1,2-Dichloroethane Dechlorination Catalyzed by Pt-Cu/SiO2: Insights into the Nature of Ethylene-Selective Active Sites / D. V. Kazachkin, D. R. Luebke, V. I. Kovalchuk, J. L. d’Itri. - Текст : непосредственный // Журнал Сибирского федерального университета. Химия. - 2008. - Т. 1, № 4. - С. 303-325. - ISSN 1998-2836.
Аннотация: Differently pretreated silica-supported Pt, Cu, and Pt-Cu catalysts with Cu to Pt atomic ratio of 1 to 6 have been investigated by a combination of reaction kinetics and FTIR spectroscopic studies in order to understand the factors that control the selectivity toward ethylene and ethane in the CH2ClCH2Cl+H2 reaction. Carbon monoxide adsorption was used to probe the electronic modification of Pt and Cu as well as the nature of ethylene-selective active sites. It was shown that there is a very limited, if any, electronic interaction between Pt and Cu in the bimetallic catalysts reduced at 493 K. However, the Pt-Cu catalysts, for which no dipole-dipole coupling shift was observed in the IR spectra of adsorbed CO suggesting extremely small Pt ensembles on the catalyst surface, demonstrated high ethylene selectivity in the 1,2-dichloroethane dechlorination. Electronic interactions between Pt and Cu have been discovered for the Pt-Cu/SiO2 catalysts reduced at 773 K. The interactions manifested themselves by a higher stability of Cu0-CO adsorption complexes in vacuum and by an increase in intensity of the Pt-CO band in the FTIR spectra upon evacuation of CO from the gas phase suggesting the formation of Pt-Cu solid solutions. The higher temperature reduction resulted in the dipole-dipole coupling shift of 6 to 19 cm-1 in the FTIR spectra of adsorbed CO. The initial ethylene selectivity of the catalysts was inversely proportional to the dipole-dipole coupling shift. The observations are consistent with the idea that the nature of the Pt-Cu species, viz., alloy particles as opposed to Cu/Pt overlayers, does not control the reaction selectivity, which is a function of the Pt ensemble size on the surface of Pt-Cu moieties.
Год издания: 2008
Авторы: Kazachkin Dmitry V. , Luebke David R. , Kovalchuk Vladimir I. , d’Itri Julie L.
Источник: Журнал Сибирского федерального университета. Химия
Выпуск: Т. 1, № 4
Номера страниц: 303-325
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  • Отдел научно-библиографической работы (пр. Свободный, 79, к. Б3-10): свободно 1 из 1 экземпляров
  • Книгохранилище научной литературы (пр. Свободный, 79, 3 этаж): свободно 1 из 1 экземпляров