Nickel/aluminum alloy

TABLE 11.59 Type K Thermocouples Nickel-Chromium Alloy vs. Nickel-Aluminum Alloy... 

Catalytic methanation processes include (/) fixed or fluidized catalyst-bed reactors where temperature rise is controlled by heat exchange or by direct cooling using product gas recycle (2) through wall-cooled reactor where temperature is controlled by heat removal through the walls of catalyst-filled tubes (J) tube-wall reactors where a nickel—aluminum alloy is flame-sprayed and treated to form a Raney-nickel catalyst bonded to the reactor tube heat-exchange surface and (4) slurry or Hquid-phase (oil) methanation. 

Other metal hydrides and metal alkoxides have been used as well as diphenylsilane and nickel—aluminum alloy (13). 

Raney Not a process, but a nickel catalyst widely used for hydrogenating organic compounds. It is made from a 50/50 nickel/aluminum alloy by leaching out the aluminum with concentrated aqueous sodium hydroxide. The product has a spongy texture and is highly active. Invented by M. Raney in 1926. The business was acquired by W. R. Grace in 1963. U.S. Patent 1,628,190. 

The hydrogenolysis of thiophene and its homologs has been investigated in the presence of Ni-Al alloy and aqueous alkali (65) and over vanadium oxide (47). It has been shown that / -(2-thenoyl)-propionic acid (II) on treatment with nickel aluminum alloy in aqueous alkali solution yielded... 

T-l Raney Nickel Catalyst. To prepare, proceed as follows in a one liter three necked flask containing 600 ml of a 10% sodium hydroxide solution, 40 g of Raney nickel aluminum alloy (50%) is added in small portions. During the addition the temp should be 90-95° and there should be good stirring (do not use a magnetic stirring device). After the addition is complete (25 to 30 min), stir for 1 hour more, and let the nickel settle to the bottom of the flask. Decant the solution off, wash with 5 times 200 ml of water, 5 times 50 ml of ethanol, in such a way to keep the nickel always covered with liquid. The catalyst must be stored under ethanol and refrigerated. It may he stored for three months and remain active. 

Several reductions have been achieved by dissolving a nickel-aluminum alloy containing usually 50% of aluminum in 20-50% aqueous sodium hydroxide in the presence of a reducible compound. Since under such conditions elemental hydrogen is generated by dissolution of aluminum, and since Raney nickel is formed in this process, such reductions have to be considered catalytic hydrogenations rather than dissolving metal reductions. Their outcome certainly points to the former type. 

Surprisingly good results in the reduction of aromatic ketones were obtained in treating the ketones with a 50% nickel-aluminum alloy in 10-16% aqueous sodium hydroxide at temperatures of 20-90° (yields 65-90%) [769, 827]. 

Reduction of unsaturated ketones to saturated alcohols is achieved by catalytic hydrogenation using a nickel catalyst [49], a copper chromite catalyst [50, 887] or by treatment with a nickel-aluminum alloy in sodium hydroxide [555]. If the double bond is conjugated, complete reduction can also be obtained with some hydrides. 2-Cyclopentenone was reduced to cyclopentanol in 83.5% yield with lithium aluminum hydride in tetrahydrofuran [764], with lithium tris tert-butoxy)aluminium hydride (88.8% yield) [764], and with sodium borohydride in ethanol at 78° (yield 100%) [764], Most frequently, however, only the carbonyl is reduced, especially with application of the inverse technique (p. 21). 

Raney nickel A porous nickel catalyst produced from a nickel-aluminum alloy. 

The checkers used material purchased from Harshaw ( hemical Company. The submitters used nickel-aluminum alloy (50% Ni, 50% Al) supplied by British Drug Houses Ltd. 

B. - o-Carboxy phenyl) propionic acid. In an open 1-1. widemouthed round-bottomed flask are placed 18 g. (0.094 mole) of 0-carboxycinnamic acid and 550 ml. of 10% sodium hydroxide solution. The mixture is warmed to 90° (Note 8) on a steam bath and stirred mechanically. The steam bath is then removed while 54 g. (Note 9) of nickel-aluminum alloy (Raney catalyst) powder is added through the open neck of the flask in small portions (from the end of a spatula) at frequent intervals (Note 10). When addition of the alloy is complete (about 50 minutes), the mixture is stirred and maintained at 90-95° for 1 hour by warming on a steam bath. Distilled water is added as needed to maintain the total volume at approximately 550 ml. The hot mixture is filtered with suction, and the metallic residue is washed with 50 ml. of hot 10% sodium hydroxide solution and two 50-ml. portions of hot water in such a manner that the solid is always... 

The Raney nickel reagent is prepared by addition of 9.5 g. of sodium hydroxide pellets over 8-10 minutes to a stirred suspension of 7.8 g of nickel-aluminum alloy (50% Ni, 50% A1 powder, purchased from Merck-Schuchardt) in 120 ml. of distilled water contained in a 250-ml. beaker. Fifteen minutes after the addition is completed, the beaker is immersed into a 70° water bath for 20 minutes. The water is decanted, and the catalyst is washed sequentially with two 20-ml. portions of distilled water and two 20-ml. portions of methanol. 

---