Cu-Ru catalysts

Shimizu H, Christmann K, Ertl G. 1980. Model studies on bimetallic Cu/Ru catalysts II. Adsorption of hydrogen. J Catal 61 412. 

The behaviour of a model Cu-Ru catalyst on carbon, in CO and H2 in ETEM show sheet-like Cu particles and smaller Ru particles in CO, whereas primarily larger spherical Cu particles and smaller Ru ones are observed in H2 (figure 5.25),... 

Initial conversion rates are not easy to compare because of the very different coverages obtained according to the second metal used. We can only notice that for M/Cus = 0,10 and 0,17 (Cu-Ir and Cu-Rh), these rates are very low. The main important feature i. that the same cyclodehydration reactions are observed, like that for Cu-Ru catalyst, whatever the nature of the second metal is. 

Figure 16 Alumina-supported Cu/Ru catalyst, showing EDS analysis of one particle in micrograph (a). Ru, Al, and Cu peaks clearly shown (b), the Cu background intensity due to bremstrahlung shown dotted...

Fig. 13. Relative Ru-speciftc activity as a function of Cu coverage (ML) on Ru(0001) (dashed lines) and Cu atomic ratio on silica-supported Cu/Ru catalysts (points and solid curves) for the ethane hydrogenolysis (a) and cyclohexane dehydrogenation (b) reactions. Note that the atomic ratio reported for the supported system probably underestimates the surface coverage of Cu since Cu resides predominantly on the Ru surface in these catalysts. From Ref. 159. Data for silica-supported catalysts taken from Ref. 184.

The Ru-Cu catalysts modified with TA also proved to be not very effective. Skeletal Cu-Ru catalysts (1 1) were prepared by leaching a Cu-Ru-A1 alloy (15 15 70) at 60°C with a 20% aqueous NaOH solution. Modification of the Cu-Ru (1 1) catalyst was carried out in a 4% aqueous solution of (2R,3R)-tartaric acid at pH 4.4. Hydrogenation of EAA was carried out without solvent at 30°C and 140 bar for 5h. For comparison the hydrogenation of EAA using skeletal Ru and Cu catalysts were also examined under the same conditions. Results are summarized in Table 4.14. 

Likewise, as was the case with the Cu-Ru catalysts, the violation from additivity was observed upon the introduction of small amounts of Pd into the Cu catalyst At 5% Pd the specific rate related to m of surface area of the Pd phase increased up to 150 times the rate of hydrogenation on the pure Pd catalyst. This indicated sharp changes of the properties of copper in bimetallic catalysts after mixing it with palladium. 

Because Cu did not adsorb hydrogen, the exposed surface of Ru in Cu-Ru catalysts can be determined by adsorption of hydrogen using galvanostatic and potentiodynamic measurements in KOH and H2SO4 media... 

Klabunovskii, E.I., Vedenyapin, A.A., and Areshidze, G.Kh. (1975) Asymmetric activity of skeletal Cu-Ru-Catalysts in hydrogenation of acetacetic ester. Izv. AN SSSR. Ser. khim. 2311-2313, Chem. Abstr. 1976, 84, 43254n. 

D-Glucitol is converted to a mixture of 1,4-anhydro-D-glucitol, 2,5-anhydro-L-iditol, 2,5-anhydro-D-mannitol and l,4 3,6-dianhydro-D-glucitol on treatment with hydrogen in the presence of a Cu-Ru catalyst. Reactions of other alditols with bimetallic catalysts are described. The preparations of three stereoisomers (exo, endo endo, exo endo, endo) of the known Chem. Abstr., 1991, 115, 136 644) dianhydro nitrate derivative 27 (exo, exo form) have been reported and the enzymatic preparations of l,4 3,6-dianhydro-D-glucitol mono acetates is mentioned in Chapter 7. 

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