Raney nickel
Following the development of Raney nickel, other alloy systems with aluminium were considered, of which the most notable include copper, ruthenium and cobalt. Further research showed that adding a small amount of a third metal to the binary alloy would promote the activity of the catalyst. Some widely used promoters are zinc, molybdenum and chromium. An alternative way of preparing enantioselective Raney nickel has been devised by surface adsorption of tartaric acid.