ABSTRACT
Unsupported metals are found in a variety of forms; wires, ribbons, single crystals, colloids, powders, blacks and the so called skeletal species. A black is a metallic powder obtained by reduction of a metal salt or by condensation of a metal vapor. Such materials are also sometimes referred to as powders. The blacks and powders are usually composed of relatively large particles having a low surface area. Catalytic reactions can be run over large, massive metal panicles as well as the much smaller, dispersed metal crystallites. At present, the most commonly used massive metal catalysts are the metal single crystals. These materials have well-defined surfaces and can have varying amounts of corner, edge or face atoms on their surface depending on the angle of cleavage in producing the crystal. Some metallic modifiers can be incorporated into the nickel oxide by coprecipitation of a mixed hydroxide from a solution containing a salt of the modifier along with the nickel nitrate.
