Preparation, Characterization, and Activity forn-Hexane Reactions of Alumina-Supported Rhodium–Copper Catalysts
1997; Elsevier BV; Volume: 171; Issue: 2 Linguagem: Inglês
10.1006/jcat.1997.1807
ISSN1090-2694
AutoresA. Guerrero‐Ruíz, B. Bachiller‐Baeza, Paloma Ferreira-Aparicio, I. Rodrı́guez-Ramos,
Tópico(s)Catalytic Processes in Materials Science
ResumoAlumina-supported rhodium–copper catalysts were prepared and characterized by chemisorption of hydrogen, temperature-programmed reduction, X-ray photoelectron spectroscopy, and infrared spectroscopy of adsorbed CO. It is shown that the alumina support interacts with rhodium as well as with copper. None of the bimetallic catalysts have a single phase, but are composed of segregated phases of rhodium and copper and alloyed clusters, the latter being formed at the lowest rhodium loading. The catalytic properties of the catalysts were studied by means of then-hexane reaction. The turnover frequencies remained constant upon incorporation of copper into rhodium catalysts. However, the selectivity pattern changed; i.e., the isomerization reaction was enhanced at the expense of the hydrogenolysis reaction. The hydrogenolysis product distribution also shifted to a lower fragmentation factor. These results were explained by an ensemble effect in which the addition of copper isolates the rhodium in small clusters.
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