Characterization of 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. 

For highly dispersed ruthenium-copper catalysts (bimetallic clusters), to 

In a typical hydrogen adsorption experiment, ruthenium-copper aggregates are first contacted with flowing hydrogen in the adsorption cell at 400°C to ensure thorough reduction. The cell is then evacuated to a pressure of approximately 10-6 torr and cooled to room temperature for adsorption measurements. Isotherms for total hydrogen adsorption and for weakly adsorbed hydrogen are then determined in the manner described for nickel-copper catalysts in Chapter 2. 

The materials were all heated in hydrogen at 500°C in their preparation (3). The presence of copper with the ruthenium markedly decreases the amount of strongly adsorbed hydrogen. 

The incorporation of only 1.5 at.% copper decreases the amount of strongly chemisorbed hydrogen by about 60% and lowers the activity for ethane hydrogenolysis by three orders of magnitude. With further increases in the amount of copper, the hydrogen chemisorption capacity and ethane hydrogenolysis activity continue to decrease markedly. 

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