Data, ruthenium-copper aggregates

In the upper field of Figure 3.2 the hydrogen chemisorption data refer to strongly adsorbed hydrogen. The volume adsorbed per square meter of surface is shown for ruthenium-copper aggregates of varying copper content. 

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. 

It is of interest to relate ESCA data on ruthenium-copper aggregates to data on hydrogen chemisorption on these materials, since changes in the degree of coverage of ruthenium by copper affect both the Cu/Ru intensity ratio and hydrogen chemisorption capacity. Such a relationship is shown in Figure 3.11... 

Pure copper exhibits no strong chemisorption of hydrogen. Data on strong hydrogen chemisorption on ruthenium-copper aggregates have been used as a measure of the amount of ruthenium surface not covered by copper (3,4). As the coverage by copper increases, the amount of strongly chemi-... 

Figure 3.11 Correlation of hydrogen chemisorption capacity of ruthenium-copper aggregates with the ratio /c //Ru of the intensity of electron emission from the copper 2pm level to that from the ruthenium 3dsl2 level (14) (chemisorption data at room temperature). (Reprinted with permission from North-Holland Publishing Company.)...

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