Formation of small rhodium metal particles on the surface of a carbon support |
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Authors: | A Yu Stakheev O P Tkachenko K V Klement’ev W Grünert G O Bragina I S Mashkovskii L M Kustov |
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Institution: | (1) Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia;(2) Ruhr University Bochum, D-44780 Bochum, Germany;(3) HASYLAB at DESY, D-22607 Hamburg, Germany |
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Abstract: | A rhodium catalyst supported on a Sibunit graphitized carbon carrier was studied by in situ XAFS spectroscopy. A comparative study of the reduction of rhodium was performed for the following two samples: Rh/C(120) dried at 120°C and Rh/C(350) calcined at 350°C. EXAFS data showed an absence of carbon atoms within the nearest environment of rhodium atoms in the Rh/C(120) uncalcined sample, which implies the absence of direct interaction between rhodium and the carbon support. In the course of the reduction of this sample (200°C), coarse particles with small metal cores were initially formed. These metal particles rapidly agglomerated upon the complete reduction of rhodium (350°C). These reduction of the Rh/C(350) calcined sample at 100–500°C resulted in the formation of small metal particles early in the reduction (100°C). The high dispersity of these particles was retained as the temperature of treatment in hydrogen was increased to 500°C due to metal-support interaction. The conversion of benzene into cyclohexane on the Rh/C(350) catalyst containing small rhodium particles was much higher at the same temperature of hydrogenation.Translated from Kinetika i Kataliz, Vol. 46, No. 1, 2005, pp. 122–130. Original Russian Text Copyright © 2005 by Stakheev, Tkachenko, Klementev, Grünert, Bragina, Mashkovskii, Kustov. |
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