Catalysts Raney alloy

NICKEL CATALYSTS (RANEY ALLOY or RANEY NICKEL) (7440-02-0) see Raney alloy. 

Probably the largest use of Ni is in the manuf of Monel metal, stainless steels, Ni-chrome resistance wire, in alloys for electronic and space applications, and as a catalyst (Raney Ni). It is also used as a fuel in pyrotechnics (Ref 2) and... 

It was mentioned in Section 3.3.4 that alkenes react with H2 on the surface of elemental Pd or elemental Pt to form alkanes. Similar hydrogenations occasionally also can be accomplished using Raney nickel as a catalyst. Raney nickel is prepared from a 1 1 Ni/Al alloy and aqueous KOH. 

Selective removal is a method used for very few, but important catalysts. Raney Nickel is a representative of this group. Starting from a relatively coarse powder of an alloy (e.g. NiAl, constituted of several phases in the present practice), one component (Al) is removed by a leaching agent (NaOH) leaving the active agent (Ni) in a relatively highly dispersed form. 

The process used for the preparation of Raney nickel was originally described in a patent issued to Murray Raney in 1927. The catalyst is prepared from Raney alloy which is commercially available and which consists of approximately equal weights of nickel and aluminum. 

Tishchenko (79), using a modified form of Raney nickel, obtained a 95.7 % yield of camphor from the dehydrogenation of borneol. Rutovskii, (80) received a 93.5% yield of camphor with Raney alloy. Reeves and Adkins (81), studying the dehydrogenation of primary alcohols, removed the hydrogen with ethylene. It was found that, though Raney nickel could be used for a catalyst for the reaction, the yields were low and, in general, the Raney nickel was inferior to a catalyst composed of copper, zinc, nickel, and barium chromite. 

A more direct approach is to use sodium deuteroxide in deuterium oxide to remove the aluminum from the Raney alloy. The activity of the resulting catalyst depends on the temperature and duration of the leaching process. Washing the catalyst with deuterium oxide and/or dioxane gives an effective catalyst for deuteration reactions. 

Raney copper is prepared from the commercially available copper aluminum alloy. It does not have much to offer the synthetic chemist as only a few reactions are reported to be affected by this catalyst. Raney copper, as well as Raney cobalt, generally produces fewer side reactions than Raney nickel even though they usually require higher reaction temperatures for the same reaction. Raney copper is, however, quite usefiil for the selective hydrogenation of substituted dinitro benzenes (Eqn. 8.6) with its activity apparently increasing with continued reuse. Raney copper can also be used for the catalytic hydrolysis of hindered nitriles to the amides (Eqn. 12.13). "2... 

Other specialized alloys have also been used to prepare skeletal metal catalysts. Raney ruthenium has been prepared from the ruthenium aluminum alloy. 20 A colloidal platinum has been prepared by the action of acetic acid on a platinum lithium alloy. l Skeletal nickel catalysts have been made from a number of intermetallic compounds of nickel with the rare earth elements, lanthanum and samarium. The rare earth element is removed from the alloy by reaction with diiodoethane or dibromoethane which convert the rare earths to the soluble halide salts. 22 Several multicomponent catalysts have also been prepared from the corresponding aluminum alloys. 23-126... 

A special type of catalyst which is typified by Raney Nickel is prepared by leaching out one component from a binary alloy leaving a skeletal structure of the desired catalyst. Raney Nickel itself is made by leaching out aluminium from an aluminium-nickel alloy with sodium hydroxide. Cobalt and iron catalysts have also been prepared in this manner. 

Hydrogenation of a,6-unsaturated aldehydes on Raney zinc catalysts was studied. Saturated aldehydes were obtained along with saturated alcohols. The amounts of each were dependent on reaction conditions. On reduction of nitriles and oximes with Raney alloy improved yields of primary amines were obtained. Treatment of ketoximes with Raney-nickel yields the ketones. 

Nezukone, 365 Nickel-aluminum alloy, 289 Nickel boride, 289-290 Nickel carbonyl, 181, 290-293 Nickel catalysts, Raney type, 289,290,293-294, 431... 

Treatment with acids It is well known that certain components in Raney alloys, e.g., NiAl or NiAla, are difficult to dissolve with NaOH. However, they can be dissolved by aqueous solutions of a-hydroxy acids. Selective elimination of Al, together with the removal of disordered Ni results in an improved precursor Ni catalyst, denoted as the acid-treated RNi (RNiA). Thus, treatment of a conventional RNiH (6% Al) with a solution of glycolic acid (GA) or TA at pH 3.5 and 100"C yields RNiA(GA) or RNiA(TA) with an Al content less than 3%. "Soft" TA modification (pH 5 0"C) does not eliminate Al, but nevertheless gives MNi with a better e.d.a. thain RNiH (Table 1). The optimum modifying conditions stated in the early studies (pH 3.5-5 100 C) thus not only provide the favorable adsorption species (i.e., TAHNa) but also partly remove the N-regions by corrosion with acid (a one pot preparation of TA-MRNiA). 

Alcan 756 C.l. 77775 Carbonyl nickel powder CCRIS 427 EINECS 231-111-4 EL12 Fibrex Fibrex P HSDB 1096 Ni 0901-S Ni 270 Ni 4303T Nichel Nickel 200 Nickel 201 Nickel 205 Nickel 207 Nickel 270 Nickel catalyst Nickel compounds Nickel, elemental Nickel, elemental/metal Nickel particles Nickel sponge NP 2 Raney alloy Raney nickel RCH 55/5. Metallic element, used in electroplating, as a hydrogenation catalyst and in iron- and copper-based alloys. Metal mp = 1453° bp (calc) = 2732° d= 8.908. Atomergic Chemetals Inco, Europe Lancaster Synthesis Co. Sigma-Aldrich Fine Chem. 

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