|stuff about Raney- not too specific||Bookmark|
Effect Of Additives On The Formation Of Raney Copper
Raney copper is an active hydrogenation catalyst. It is formed by selectively dissolving aluminium from a copper-aluminium alloy using sodium hydroxide, leaving highly-porous copper. The catalyst may have dopants added, either directly in the precursor alloy, or in the leaching solution. These dopants promote the catalytic activity of Raney copper by increasing the surface area and, in the case of chromate, stabilising the structure.
The selective dissolution of aluminium results in the loss of about two-thirds of the atoms from the alloy (CuAl2) leaving only the copper atoms to form a solid structure. The way in which the copper arranges itself, and how the structure rearranges with time resulting in a loss of surface area, was the initial focus of this project. This has now been solved (A.J. Smith, T. Tran and M.S. Wainwright, J. Appl. Electrochem., (in press) 1999).
The way in which the dopants are able to increase and stabilise the surface area, and where they are incorporated into the final structure, is the second and main focus of this work. The mechanisms for the two main dopants (zinc and chromium) are almost fully understood by now. All that remains is to discover where the dopants reside in the copper structure. By understanding how the dopants work, it is hoped that they may be better optimised, or that other dopants may be found that work better.
A.J. Smith, T. Tran and M.S. Wainwright, Kinetics & Mechanism of the Preparation of Raney Copper, Journal of Applied Electrochemistry, submitted 1 Feb 1999
Description of a new Ethyl Acetate production method.
A brief description of the Raney Metal Catalysts
Sponge Metal catalysts (also known as raney catalysts) are made by first forming an alloy of a base metal (typically nickel, cobalt or copper) with aluminum. In general, other transition metals are added as promoters. The alloy is then crushed and sized to powders or granules. Next the alloy is activated by treatment with caustic soda to form a highly active catalyst. Sponge Metals Catalysts require no further pre-activation prior to use. These catalysts are utilized in a wide range of industrial hydrogenation and reductive alkylation reactions. For more selective hydrogenation reactions, Sponge Cobalt catalysts are used. Sponge Copper catalysts are also useful for hydrogenation and dehydrogenation reactions
Paper containing technical data for the formation of Raney Catalysts
Example of a dehydrogenation using Raney Copper
Shreiber, E. H., Rhodes, M. D. and Roberts, G. W., "Methanol Dehydrogenation with Raney Copper in a Slurry Reactor", Appl. Cat. B. Environmental, 23, 9 (1999).
hydrogenation using Raney compounds
R. Menini, A. Martel, H. Ménard, J. Lessard, O. Vittori. The Electrocatalytic Hydrogenation of Phenanthrene at Raney Nickel Electrodes. Influence of Inert Gas Pressures. Electrochimica Acta, 205, Vol. 45 (1998) 1697-1703.