Ruthenium decomposition

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... 

SSIMS has also been used to study the adsorption of propene on ruthenium [3.29], the decomposition of ammonia on silicon [3.30], and the decomposition of methane thiol on nickel [3.31]. 

Platinum Platinum-coated titanium is the most important anode material for impressed-current cathodic protection in seawater. In electrolysis cells, platinum is attacked if the current waveform varies, if oxygen and chlorine are evolved simultaneously, or if some organic substances are present Nevertheless, platinised titanium is employed in tinplate production in Japan s. Although ruthenium dioxide is the most usual coating for dimensionally stable anodes, platinum/iridium, also deposited by thermal decomposition of a metallo-organic paint, is used in sodium chlorate manufacture. Platinum/ruthenium, applied by an immersion process, is recommended for the cathodes of membrane electrolysis cells. ... 

The largest uses of platinum group metals in electronics are ruthenium for resistors and palladium for multilayer capacitors, both applied by thick film techniques . Most anodes for brine electrolysis are coated with mixed ruthenium and titanium oxide by thermal decomposition . Chemical vapour deposition of ruthenium was patented for use on cutting tools . 

The mechanistic investigations presented in this section have stimulated research directed to the development of advanced ruthenium precatalysts for olefin metathesis. It was pointed out by Grubbs et al. that the utility of a catalyst is determined by the ratio of catalysis to the rate of decomposition [31]. The decomposition of ruthenium methylidene complexes, which attribute to approximately 95% of the turnover, proceeds monomolecularly, which explains the commonly observed problem that slowly reacting substrates require high catalyst loadings [31]. This problem has been addressed by the development of a novel class of ruthenium precatalysts, the so-called second-generation catalysts. 

The most significant and widely studied reactivity of the ruthenium and osmium porphyrin carbene complexes is their role in catalyzing both the decomposition of diazoesters to produce alkenes and the cyclopropanation of alkenes by diazoesters. Ethyl diazoacetate is used to prepare the carbene complex 0s(TTP)(=CHC02Et)... 

Recently, we have shown that the combination of barium tetratitanate, BaTi40g and sodium hexatitanate, NagTigOis, with ruthenium oxides leads to active photocatalysts for water decomposition[1,2]. The unique feature of these photocatalysts is that no reduction of the titanates is required to be activated this is intrinsically different from conventional photocatalysts using TIO2 which are often heat-treated in a reducing atmosphere. Such different photocatalytic characteristics suggest that efficiency for the separation of photoexcited charges (a pair of electrons and holes) which is the most important step in photocatalysis is... 

Unfortunately, complexes 39 and 40 are still more prone to decomposition than catalyst 16. Therefore, Grubbs sought to investigate a series of new ruthenium catalysts bearing NHCs with varying degrees of iV-heterocyclic backbone and aryl side chain substitution, and catalysts 16 and 30a were chosen as basic catalyst structures [57]. In 2009, complexes 41a-c and 42a-c were prepared to attempt to understand how the degree of substitution on the backbone influences catalyst activity and lifetime (Fig. 3.15). 

The layer of titanium and ruthenium oxides usually is applied to a titanium substrate pyrolytically, by thermal decomposition (at a temperature of about 450°C) of an aqueous or alcoholic solution of the chlorides or of complex compounds of titanium and rathenium. The optimum layer composition corresponds to 25 to 30 atom % of ruthenium. The layer contains some quantity of chlorine its composition can be written as Ruq 2sTio 750(2- c)Cl r At this deposition temperature and Ru-Ti ratio, the layer is a poorly ordered solid solution of the dioxides of ruthenium and titanium. Chlorine is completely eliminated from the layer when this is formed at higher temperatures (up to 800°C), and the solid solution decomposes into two independent phases of titanium dioxide and ruthenium dioxide no longer exhibiting the unique catalytic properties. 

Fig. 10. Ruthenium over titanium ratio for mixed (Ru, Ti)02 based electrodes prepared by thermal decomposition. Nominal compositions are given in the figure. After [46],...

Additional Comments Regarding the Ruthenium Carbonyl-Tri-methylamine WGSR System. A potential mechanistic pathway for a WGSR system involves the production of formate, followed by its catalytic decomposition ... 

Ruthenium carbonyl decomposes the formate ion in basic media, but at a rate slower than the rate of the WGSR. At 100° and 0.10 mM Rug(C0)] 2 under 3 atm N2> the rate of decomposition of trimethyl ammonium formate to H2 and CO2 is 0.6 mmol/hr. Under 5 atm CO the rate is slower (<0.1 mmol/hr), but the overall rate of H2 production is >0.4 mnol/hr. At this low CO pressure, the rate of H2 production directly from CO and H2O is more than three times that from formate decomposition. Furthermore, since increases in CO pressure result in improved H2 production rates (10 mnol/hr at 50 atm CO), while apparently inhibiting the rate of formate decomposition, it may be concluded that formate decomposition has little mechanistic significance in the WGSR activity of Ru (CO)... 

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