Platinum sponge, hydrogenation catalyst

Derivation (1) By passing hydrogen with bromine vapor over warm platinum sponge which acts as a catalyst (2) As a by-product in the bromination of organic compounds. 

Following the development of sponge-metal nickel catalysts by alkali leaching of Ni-Al alloys by Raney, other alloy systems were considered. These include iron [4], cobalt [5], copper [6], platinum [7], ruthenium [8], and palladium [9]. Small amounts of a third metal such as chromium [10], molybdenum [11], or zinc [12] have been added to the binary alloy to promote catalyst activity. The two most common skeletal metal catalysts currently in use are nickel and copper in unpromoted or promoted forms. Skeletal copper is less active and more selective than skeletal nickel in hydrogenation reactions. It also finds use in the selective hydrolysis of nitriles [13]. This chapter is therefore mainly concerned with the preparation, properties and applications of promoted and unpromoted skeletal nickel and skeletal copper catalysts which are produced by the selective leaching of aluminum from binary or ternary alloys. 

The behavior of carbon monoxide-hydrogen mixtures in the presence of metals of the platinum group lias been made the subject of special study by a number of investigators. Orloff82 was the first to observe that under certain conditions in the presence of a nickel-palladium catalyst, a reaction took place which resulted in the formation of ethylene. This is in contradiction to the observations of Breteau,88 who stated that in the presence of palladium sponge, carbon monoxide and hydrogen react in the cold to form methane and that at 400° C. this transformation becomes fairly rapid. Recently it has seemed desirable that the experiments of Orloff... 

Cavallito (66) reports that neither it nor 3-benzoxypyridine was hydrogenated in the presence of Willstatter s palladium sponge catalyst (67). Under low pressure conditions in ether or dioxane Raney nickel and platinum oxide were ineffective. However, other examples show that reduction takes place readily under a variety of conditions. Biel used Raney nickel at 125° and 50 atm (68), excellent yield of 6-propyl-3-hydroxypiperidine resulted from reduction of the pyridine in acetic acid with platinum oxide (69). Ruthenium in the conversion of 3-hydroxypyridine in aqueous solution gave very high yield of the corre-... 

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