On ruthenium oxide

J.-M. Zen, C.-B. Wang, Oxygen Reduction on Ruthenium Oxide Pyrochlore Produced in a Proton Exchange Membrane, J. Electrochem. Soc. 141 (1994) 38-39. 

The screen-printing paste is made up in the manner described in Section 4.2.2 and the patterns printed. The heater element and its leads would typically be platinum and the interdigitated electrodes gold. As illustrated below (Fig. 4.49) the heater might also be a composition based on ruthenium oxide (see Section 4.2.2). The contacting tabs are also screen-printed gold. 

Petrykin V, Macounova K, Shlyakhtin OA, Krtil P (2010) Tailoring the selectivity for electrocatalytic oxygen evolution on ruthenium oxides by zinc substitution. Angew Chem Int Ed 49(28) 4813 815... 

Zen J -M and Wang C W (1994) Oxygen reduction on ruthenium oxide pyrochlore produced in a proton exchange membrane, J. Electrochem. Soc., 141, pp. L51-L52. 

Hydrogenation of 19-nor-A -3-keto steroids also gives 5a- and 5 -product mixtures under the usual conditions but with ruthenium oxide at high pressures only the 5j8-isomer is formed.The presence of a 4-methyl group on a A -3-keto steroid increases the amount of a attack as compared to the parent enone. ... 

A solution of 20 g of estradiol in 500 ml of ethanol containing 1 ml of 40 % sodium hydroxide is hydrogenated over 5 g of ruthenium oxide or 3-5 g of 5% ruthenium-on-charcoal at 65° and 1500 psi. After filtration and evaporation, the residue is recrystallized to give 80% of 5a, 10a-estrane-3j9, 17 -diol. °... 

High-valent ruthenium oxides (e. g., Ru04) are powerful oxidants and react readily with olefins, mostly resulting in cleavage of the double bond [132]. If reactions are performed with very short reaction times (0.5 min.) at 0 °C it is possible to control the reactivity better and thereby to obtain ds-diols. On the other hand, the use of less reactive, low-valent ruthenium complexes in combination with various terminal oxidants for the preparation of epoxides from simple olefins has been described [133]. In the more successful earlier cases, ruthenium porphyrins were used as catalysts, especially in combination with N-oxides as terminal oxidants [134, 135, 136]. Two examples are shown in Scheme 6.20, terminal olefins being oxidized in the presence of catalytic amounts of Ru-porphyrins 25 and 26 with the sterically hindered 2,6-dichloropyridine N-oxide (2,6-DCPNO) as oxidant. The use... 

Structural data on ruthenium porphyrins shows that the Ru-N (porphyrin) distance is relatively unaffected by changing the oxidation state, as expected for a metal atom inside a fairly rigid macrocyclic ring (Table 1.11). 

Detailed studies have been performed on pseudocapacitors with layers of hydrated ruthenium oxide, RuOj- HjO. Protons relatively readily undergo intercalation and deintercalation in this material ... 

A wider application of ruthenium oxide capacitors is hindered by the high cost of ruthenium oxide. Attempts have been reported, therefore, to substitute ruthenium oxide with other, cheaper materials capable of intercalation and deintercalation of hydrogen and/or other ions. Promising results with pseudocapacities of about 100 F/g have been obtained with the mixed oxides of ruthenium and vanadium and also with mixed oxides on the basis of manganese oxide. 

Goodman DW, Peden CHF, Chen MS. 2007. CO oxidation on ruthenium The nature of the active catal3dic surface. Surf Sci 601 L124. 

For Cl2 or 02 evolution the stability of ruthenium based electrodes is not sufficient on a technical scale. Therefore the possibility of stabilizing the ruthenium oxide without losing too much of its outstanding catalytic performance was investigated by many groups. For the Cl2 process, mixed oxides with valve metals like Ti or Ta were found to exhibit enhanced stability (see Section 3.1), while in the case of the 02 evolution process in solid polymer electrolyte cells for H2 production a mixed Ru/Ir oxide proved to be the best candidate [68, 80]. 

Rare, shiny, and lightest metal of the platinum group. Hardens platinum and palladium. The presence of 0.1 % of ruthenium in titanium improves its resistance to corrosion 100-fold. The spectacular catalytic properties of ruthenium are used on industrial scales (hydrogenations, sometimes enan-tioselective, and metathesis). Titanium electrodes coated with ruthenium oxide are applied in chlorine-alkaline electrolysis. Suitable for corrosion-resistant contacts and surgical instruments. 

Dioxo-ruthenium porphyrin (19) undergoes epoxidation.69 Alternatively, the complex (19) serves as the catalyst for epoxidation in the presence of pyridine A-oxide derivatives.61 It has been proposed that, under these conditions, a nms-A-oxide-coordinated (TMP)Ru(O) intermediate (20) is generated, and it rapidly epoxidizes olefins prior to its conversion to (19) (Scheme 8).61 In accordance with this proposal, the enantioselectivity of chiral dioxo ruthenium-catalyzed epoxidation is dependent on the oxidant used.55,61 In the iron porphyrin-catalyzed oxidation, an iron porphyrin-iodosylbenzene adduct has also been suggested as the active species.70... 

Cationic ruthenium complexes of the type [Cp Ru(MeCN)3]PF6 have been shown to provide unique selectivities for inter- and intramolecular reactions that are difficult to reconcile with previously proposed mechanistic routes.29-31 These observations led to a computational study and a new mechanistic proposal based on concerted oxidative addition and alkyne insertion to a stable ruthenacyclopropene intermediate.32 This proposal seems to best explain the unique selectivities. A similar mechanism in the context of C-H activation has recently been proposed from a computational study of a related ruthenium(ll) catalyst.33... 

Consequently, in the early 1990s, interest in the direct processes decreased markedly, and the emphasis in research on CH4 conversion returned to the indirect processes giving synthesis gas (13). In 1990, Ashcroft et al. (13) reported some effective noble metal catalysts for the reaction about 90% conversion of methane and more than 90% selectivity to CO and H2 were achieved with a lanthanide ruthenium oxide catalyst (L2Ru207, where L = Pr, Eu, Gd, Dy, Yb or Lu) at a temperature of about 1048 K, atmospheric pressure, and a GHSV of 4 X 104 mL (mL catalyst)-1 h-1. This space velocity is much higher than that employed by Prettre et al. (3). Schmidt et al. (14-16) and Choudhary et al. (17) used even higher space velocities (with reactor residence times close to 10-3 s). 

Another useful bimetallic for fuel cell electrodes is Pt/Ru. Ruthenium is readily oxidized to Ru02 by calcination after it is impregnated. The PZC of ruthenium oxide is unknown. Propose a comprehensive sequence of experiments with which the SEA method can be applied for the synthesis of a Pt/Ru bimetallic catalyst supported on carbon. The goal is to have intimate contact between the Pt and Ru phases in the final, reduced catalyst. 

Kim, l.-H., et ah, Synthesis and characterization of electrochemically prepared ruthenium oxide on carbon nanotube film substrate for supercapacitor applications. Journal of The Electrochemical Society, 2005.152(11) p. A2170-A2178. 

More recently Hartog and Zwietering (103) used a bromometric technique to measure the small concentrations of olefins formed in the hydrogenation of aromatic hydrocarbons on several catalysts in the liquid phase. The maximum concentration of olefin is a function of both the catalyst and the substrate for example, at 25° o-xylene yields 0.04, 1.4, and 3.4 mole % of 1,2-dimethylcyclohexene on Raney nickel, 5% rhodium on carbon, and 5% ruthenium on carbon, respectively, and benzene yields 0.2 mole % of cyclohexene on ruthenium black. Although the cyclohexene derivatives could not be detected by this method in reactions catalyzed by platinum or palladium, a sensitive gas chromatographic technique permitted Siegel et al. (104) to observe 1,4-dimethyl-cyclohexene (0.002 mole %) from p-xylene and the same concentrations of 1,3- and 2,4-dimethylcyclohexene from wi-xylene in reductions catalyzed by reduced platinum oxide. 

Kohno, M., Kaneko, T., Ogura, S., Sato, K., Inoue, Y. 1998. Dispersion of ruthenium oxide on barium titanates (BasTij,0. , Ba.,Tij303, BaTi.,0, and BajTi,Oj, ) and photocatalytic activity for water decomposition. J Chem Soc Faraday Trans 94 89-94. 

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