Publicación: Comparative study of Cu, Ag and Ag-Cu catalysts over graphite in the ethanol dehydrogenation reaction: Catalytic activity, deactivation and regeneration
Fecha
2019
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info:eu-repo/semantics/openAccess
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Resumen
The physicochemical and catalytic properties of bimetallic AgCu catalysts and their monometallic counterparts supported on a high surface area graphite have been comparatively evaluated in the ethanol dehydrogenation reaction, performed in a continuous-flow reactor. While Cu was incorporated by the incipient wetness impregnation technique, for Ag catalysts two synthesis procedures were explored: incipient wetness impregnation and adsorption of Tollens’ reagent. The catalysts prepared by wetness impregnation exhibited higher metal dispersion, being improved for the bimetallic catalysts in comparison with the monometallic counterparts. The results obtained in the catalytic tests revealed that Cu catalysts is nearly two orders of magnitude more active than Ag catalyst in the dehydrogenation reaction of ethanol on either a turnover frequency or a weight basis, but at the same time both catalysts were 100% selective to acetaldehyde. Whereas selectivity was not affected by the bimetallic composition, there was a substantial decrease in the reaction rate among the bimetallic catalysts as
the Cu/Ag ratio diminished, due to blockage of copper surface active sites by silver. Both silver and copper, and the bimetallic catalysts, suffered from deactivation at 523 K, caused by blocking of active sites by adsorbed
hydrocarbons on the catalyst surface (fouling). Carbonaceous deposits were removed through a thermal treatment under H2 flow, which allowed the total recovery of the initial catalytic activity.
Descripción
The registered version of this article, first published in “Applied Catalysis A: General, Volume 576", is available online at the publisher's website: Elsevier, https://doi.org/10.1016/j.apcata.2019.02.031
La versión registrada de este artículo, publicado por primera vez en “Applied Catalysis A: General, Volume 576", está disponible en línea en el sitio web del editor: Elsevier, https://doi.org/10.1016/j.apcata.2019.02.031
Categorías UNESCO
Palabras clave
Bimetallic catalysts, Alcohol dehydrogenation, Fouling, Catalyst reactivation
Citación
J.M. Conesa, M.V. Morales, C. López-Olmos, I. Rodríguez-Ramos, A. Guerrero-Ruiz, Comparative study of Cu, Ag and Ag-Cu catalysts over graphite in the ethanol dehydrogenation reaction: Catalytic activity, deactivation and regeneration, Applied Catalysis A: General, Volume 576, 2019, Pages 54-64, ISSN 0926-860X, https://doi.org/10.1016/j.apcata.2019.02.031
Centro
Facultades y escuelas::Facultad de Ciencias
Departamento
Química Inorgánica y Química Técnica