Hydrogenolysis ruthenium-copper aggregates

Ruthenium-copper aggregates of the type described have been studied with chemical and physical probes. Chemical probes that have been very informative include hydrogen chemisorption and the hydrogenolysis of ethane to methane. Physical probes useful in these characterizations include X-ray diffraction and electron spectroscopy. 

Figure 3.2 Hydrogen chemisorption capacity and ethane hydrogenolysis activity of ruthenium-copper aggregates as a function of copper content (3). (Reprinted with permission from Academic Press, Inc.)...

In addition to hydrogen chemisorption and ethane hydrogenolysis, the reactions of cyclohexane provide a useful chemical probe for investigating ruthenium-copper aggregates. On pure ruthenium, two reactions of cyclohexane are readily observed dehydrogenation to benzene and hydrogenolysis to lower carbon number alkanes. The product of the latter reaction is predominantly methane, even at very low conversions. 

As shown in Figure 3.5, addition of copper to ruthenium decreases hydrogenolysis activity markedly but has a much smaller effect on dehydrogenation activity. The presence of copper thus improves the selectivity of conversion of cyclohexane to benzene. The data were obtained at 316°C with cyclohexane and hydrogen partial pressures of 0.17 and 0.83 atm, respectively. The ruthenium-copper aggregates were heated to 400°C in hydrogen in their preparation. 

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