Ruthenium

Like other platinum group metals, ruthenium is an excellent hardener of platinum and palladium, with which it is alloyed for electrical contacts to improve their wear resistance.   Ruthenium improves titanium's corrosion resistance a hundredfold.   Ruthenium is a good catalyst.   Hydrogen sulfide, H₂S, is split catalytically by light using an aqueous suspension of CdS particles mixed with ruthenium dioxide, a method that can remove H₂S from petroleum refining and other industrial processes. ^{Lide 4-25}

Ruthenium was discovered by Berzelius and Osann in 1827 from the residues left after dissolving platinum in aqua regia, although Klaus is usually given credit for this discovery by isolating it in 1844.   It is plated by electrodeposition or thermal decomposition methods.   Ruthenium occurs in free form along with other metals of the platinum group found in the Ural Mts. and in North and South America.   It is also found elsewhere in pentlandite and pyroxinite ores.   It is prepared commercially by a complex process, the final stage of which is a hydrogen reduction of ammonium ruthenium chloride, a powder, which is then consolidated by powder metallurgy processes or by arc welding. ^{Lide 4-25}