Ruthenium- palladium alloys

Basov, N.L., and V.M. Gryaznov, 1985, Dehydrogenation of cyclohexanol and hydrogenation of phenol into cyclohexanone on a membrane catalyst produced from a palladium-ruthenium alloy, in Membrane Catalyst Permeable to Hydrogen or Oxygen (V.M. Gryaznov, Ed.), Akad. Nauk SSSR, Inst Nefickhim. Sint, Moscow, USSR, p. 117. 

Thus the palladium alloy with 53% copper proved to be more permeable than palladium [37]. However, the maximal operating temperature for membranes of this alloy is 623 K. Palladium-ruthenium alloys are more thermostable and may be used up to 823 K. At the increase in ruthenium content from 1 to 9.4 at.%, the hydrogen permeability of the alloys attained a maximum at a ruthenium content of about 4.5%. The long-term strength of this alloy at 823 K after service for lOOOhr was greater by a factor of almost 5 than that of pure palladium [35]. 

The data of Tables 2 and 3 show that palladium-ruthenium alloys with mass % of ruthenium from 4 to 7 have high hydrogen permeability, catalytic activity toward many reactions with hydrogen evolution or consumption, and good mechanical strength [35]. Seamless tubes with a wall thickness of 100 and 60 p.m, as well as foils of 50-tim thickness made of the mentioned alloy, are commercially available in Russia. The tube of outer diameter of 1 mm and wall thickness of 0.1 mm is stable at a pressure drop of up to 100 atm and a temperature up to 900 K. The application of such tubes for membrane reactor will be discussed in next part of this section. 

Ceramic plates with palladium alloy may be joined to a stainless steel reactor shell by special welding. Anodized alumina plate 0.4 mm thick covered with palladium-ruthenium alloy by cathodic sputtering was sealed to the reactor body with phosphate adhesive [140]. Tubular ceramic supports may be joined with reactor modules through a... 

V.M. Gryaznov, A.P. Mischenko, V.P. Polyakova et al.. Palladium-ruthenium alloys as the membrane catalysts, Doki Akad. Nauk SSSR 277 624 (1973). 

M.M. Ermilova, N.V. Orekhova, L.S. Morozova, and E.V. Skakunova, Selective hydrogenation of cyclopolyolefines on membrane catalyst from palladium-ruthenium alloy. Membrane Catalysts Permeable to Hydrogen and Oxygen, Moscow, Topchiev Inst, of Petrochemical Synthesis, 1985, p. 70. 

P.P. Mardilovich, PV. Kurman. A.N. Govyadinov ei. al.. The gas permeability of anodic alumina membranes with palladium-ruthenium alloy layer, Russian J. Phys. Chem., in press. 

R. Paterson, V. M. Gryaznov, Gas Permeability of Anodized Alumina Membranes with a Palladium-Ruthenium Alloy Layer, Russ./. Phys. Chem. 1996, 70(3), 514-517. 

Pure ruthenium powder or mixed ruthenium-molybdenum powders have been found able to effect good joints between molybdenum and tungsten. A eutectic melting above 1 900°C is formed, and joints produced in hydrogen atmospheres at 2 100°C operate satisfactorily at 1 500°C. A cobalt-palladium-gold alloy has also been reported to be useful in brazing molybdenum. 

Ruthenium alloyed to platinum, palladium, titanium and molybdenum have many apphcations. It is an effective hardening element for platinum and palladium. Such alloys have high resistance to corrosion and oxidation and are used to make electrical contacts for resistance to severe wear. Ruthenium-palladium alloys are used in jewelry, decorations, and dental work. Addition of 0.1% ruthenium markedly improves corrosion resistance of titanium. Ruthenium alloys make tips for fountain pen nibs, instrument pivots, and electrical goods. Ruthenium catalysts are used in selective hydrogenation of carbonyl groups to convert aldehydes and ketones to alcohols. 

Some of the materials that have been examined as catalysts include Pure Platinum, Platinum-Iridium Alloys, Various Compositions of Platinum-Rhodium Alloys, Platinum-Palladium Alloys, Platinum-Ruthenium Alloys, Platinum-Rhenium Alloys, Platinum-Tungsten Alloys, FejOj-M CVI Oj (Braun Oxide), CoO-Bi20j, CoO with AI2O3, Thorium, Cerium, Zinc and Cadmium. 

Ruthenium is most often combined with platinum or palladium in alloys. Electrical contacts, devices for measuring very high and very low temperatures, and medical instruments are often made from ruthenium alloys. Ruthenium is also used in alloys with other platinum family metals to make jewelry and art objects. This use is limited, however, because of the high cost of ruthenium metal. 

Ruthenium is often combined with platinum or palladium in alloys to make medical instruments. IMAGE COPYRIGHT 2009, JOSEPH. USED UNDER LICENSE FROM SHUTTERSTOCK.COM. 

The aim of this contribution is to present data on the preparation of catalysts containing as embedding species a large family of eolloids such as colloids of ruthenium, platinum, or palladium-gold alloys and triflate derivatives such as lanthanum and silver triflate or tert-butyldimethylsilyltrifluoromethanesulfonate (BMSTM). Silica, zirconia and tantalum oxides were used as carrier. All these preparations considered the polymeric sol-gel route using as starting materials silicon, zirconium or tantalum alcoxides. 

In a number of papers attempts have been made to find a correlation between the catalytic activity and physicochemical characteristics of metals and alloys. It has been suggested that the strong catalytic properties of platinum— ruthenium alloys can be related to their electronic structure [247, 248]. The number of impaired d electrons on the catalyst atom can serve as a quantitative characteristic of the electronic structure. According to [247], for platinum and palladium the number of d electrons on the atoms is 0.6 for rhodium 1.4 for iridium 1.7 and for ruthenium 2.2. 

Ruthenium is a hard, white metal and has four crystal modifications. It does not tarnish at room temperatures, but oxidizes explosively. It is attacked by halogens, hydroxides, etc. Ruthenium can be plated by electrodeposition or by thermal decomposition methods. The metal is one of the most effective hardeners for platinum and palladium, and is alloyed with these metals to make electrical contacts for severe wear resistance. A ruthenium-molybdenum alloy is said to be... 

The corrosion behaviour of amorphous alloys has received particular attention since the extraordinarily high corrosion resistance of amorphous iron-chromium-metalloid alloys was reported. The majority of amorphous ferrous alloys contain large amounts of metalloids. The corrosion rate of amorphous iron-metalloid alloys decreases with the addition of most second metallic elements such as titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, copper, ruthenium, rhodium, palladium, iridium and platinum . The addition of chromium is particularly effective. For instance amorphous Fe-8Cr-13P-7C alloy passivates spontaneously even in 2 N HCl at ambient temperature ". (The number denoting the concentration of an alloy element in the amorphous alloy formulae is the atomic percent unless otherwise stated.)... 

An interesting approach to the inter-diffusion problem was made by Rhys S who protected ruthenium-rich ruthenium-gold alloys by palladium-... 

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