Raney Nickel , otherwise "skeletal nickel" - a solid microcrystalline porous nickel catalyst used in many chemical processes; The method of its preparation was proposed in 1926 by the American engineer Murray Reney. It is a gray fine powder (particle size usually 400-800 nm), containing, in addition to nickel, a certain amount of aluminum (up to 15 wt.%) And saturated with hydrogen (up to 33 at.%). The powder particles have a large number of pores, as a result of which the specific surface is about 100 m² / g. Raney nickel is pyrophoric , that is, it spontaneously ignites in air at room temperature, therefore it is stored under a layer of water , alcohol or gasoline.
Raney Nickel is widely used as a catalyst for various processes of hydrogenation or hydrogen reduction of organic compounds (for example, hydrogenation of arenes , alkenes , vegetable oils, etc.). It also accelerates some processes of oxidation by atmospheric oxygen . The structural and thermal stability of Raney nickel allows its use in a wide range of reaction conditions; in laboratory practice, it can be reused. Raney nickel is catalytically significantly less active than the platinum group metals , but much cheaper than the latter.
Raney nickel is obtained by fusion of nickel with aluminum at 1200 ° C (20-50% Ni; sometimes small amounts of zinc or chromium are added to the alloy), after which the milled alloy is treated with a hot sodium hydroxide solution with a concentration of 10 - 35% to remove aluminum; the residue is washed with water in a hydrogen atmosphere. The principle underlying the preparation of Raney nickel is also used to obtain catalytically active forms of other metals - cobalt , copper , iron , etc.
Sources
- Nekrasov B.V. Fundamentals of General Chemistry. - M .: Chemistry, 1973. - T. 2. - S. 340.
- Remy G. Inorganic chemistry course. - M .: Mir, 1974. - T. 2. - S. 703.