Palladium sulphides

Poisoning of sulphur compounds Pd-coated membranes could rapidly be destroyed after exposure to a gas stream containing hydrogen sulphide and the poisoning effects are irreversible [43,44]. Palladium becomes palladium sulphide, whose lattice constant is twice than of pure Pd and, thus, the structural stress leads to the formation of cracks. 

The palladium may be recovered by heating the spent catalyst to redness in order to remove organic impurities this treatment may reduce some of the barium sulphate to barium sulphide, which acts as a catalytic poison. The palladium is then dissolved out with aqua regia and the solution evaporated the residue is dissolved in hot water and hydrochloric acid to form palladium chloride. 

In view of its susceptibility to sulphide tarnishing, silver may itself require some measure of protection in many decorative and industrial applications. Chromate passivation processes are commonly employed, but as an alternative, thin coatings of gold, rhodium or palladium may be used. 

The ores from this region are of tholeiitic intrusions hosting Cu-Ni sulphides with relatively low PGM content. In these ores, most of the palladium is associated with pentlandite, where the platinum and rhodium are mainly associated with pyrrhotite. Only sperrilite and Pt-Fe alloys have, so far, been found in these ores. 

Variation of the nature of the gate electrode results in the different types of FET. For example, in the metal oxide semiconductor FET (MOS-FET) palladium/palladium oxide is used as the gate electrode. This catalyti-cally decomposes gases such as hydrogen sulphide or ammonia with the production of hydrogen ions, which pass into the semiconductor layer. An enzyme may be coated on the palladium, e.g. urease, which catalyses the production of ammonia from urea and thus provides a device for the measurement of this substrate. 

The sulphide ligands containing one butenyl group form chelate complexes with platinum(II) and palladium(II) halides. The chelated butyl pentenyl sulphide complexes could only be obtained for platinum-(II). The compounds containing two group VI atoms functioned as bidentate ligands by donation from the two sulphim atoms only. All these chelated olefinic sulphide complexes react with simple monodentate... 

Diphenyl selenide is a colourless, strongly refractive oil, B.pt. 167° C. at 16-5 mm. insoluble in water but miscible with alcohol or ether in all proportions. It has a faint odour, and a density of 1 3712 at 0° C., 1 3561 at 15 2° C., and 1 350 at 20° C. With cold bromine in ether solution it yields the dibromide. Diphenyl selenide, unlike dimethyl selenide, does not combine with alkyl iodides, and in this respect it resembles diphenyl sulphide.2 When heated nearly to its boiling-point with sulphur it gives diphenyl sulphide, the reaction being practically quantitative at 300° C.3 With palladium chloride it forms the complex PdCl2.2(C6H5)2Se, orange-red needles, M.pt. 181° to 182° C.4... 

The oxides of the metals ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, gold, and mercury are decomposed at a red heat and the chlorides, bromides, iodides, and sulphides are also decomposed, except those of silver and mercury. 

Borane-methyl sulphide complex 4-Toluenesulfonyl chloride cis-3,5-Cyclohexadiene-l,2-diol l -Dynamax 83,123-6 column Silver oxide Sodium hydride Palladium on charcoal Tetrabenzylpyrophosphate... 

Cobalt Sesquisulphide, Co2S3, results when a mixture of sulphur and the carbonates of cobalt and potassium are raised to white heat.2 Nickel, in similar circumstances, yields double sulphides such as K2S.3NiS, and thus resembles palladium and platinum, whilst cobalt behaves more like rhodium and iridium. The position of cobalt before nickel in the Periodic Table is thus supported. 

Double sulphides of iron and nickel are present in nickel matte, and are hence of commercial importance. Double sulphides with potassium, K2S.3NiS, and barium, BaS.4NiS, may be obtained by fusing nickel, sulphur, and an alkali at a high temperature.8 They are crystalline compounds. Cobalt yields only the sesquisulphide, Co2S3, in like circumstances. Nickel thus resembles palladium and platinum, whilst cobalt resembles rhodium and iridium in these respects. The position of nickel after cobalt in the Periodic Table thus receives further justification. 

Schneider 3 believed he had obtained the oxide, Pd5Os, by fusing the double palladium potassium sulphide with sodium hydroxide and potassium nitrate. It is very doubtful, however, if this is to be regarded as a separate chemical entity.3... 

Palladium Subsulphide, Pd2S.—This sulphide has been prepared by heating to bright redness a mixture of paUadous sulphide (1 part) with ammonium chloride (6 parts), sodium hydroxide (12 parts), and flowers of sulphur (12 parts). The product is washed with cold water.1... 

Palladic Sulphide, Palladium Disulphide, PdS2, has been prepared1 by igniting at bright red heat a mixture of ammonium chlor-palladate (1 part) with sulphur (12 parts) and sodium hydroxide (12 parts). The chlor-palladate may be replaced by palladous sulphide. The product is treated first with alcohol and then with dilute hydrochloric acid, when the disulphide is left as a dark brown crystalline powder, which readily dissolves in aqua regia. Exposure to air does not affect it, but... 

Reactions of Salts of Palladium.—Both hydrogen sulphide and ammonium sulphide effect the precipitation of black palladium monosulphide, PdS, from solutions of its salts. The precipitate is insoluble in excess of ammonium sulphide, but dissolves on boiling with concentrated hydrochloric acid, and is soluble in aqua regia. 

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