GB664851A - Improvements in and relating to the preparation of catalysts - Google Patents

Abstract

Aniline is prepared by the hydrogenation of nitrobenzene at 300 DEG C. in the presence of an alkali-free foraminate catalyst prepared by the partial extraction of a copper-silicon alloy with liquid phenol or vaporized methanol (see Group III).ALSO:Alkali-free foraminate catalysts containing copper, cobalt, nickel, or iron are prepared from alloys of one or more of these metals with silicon and/or aluminium by treating the alloy at above 100 DEG C (preferably 180 DEG -300 DEG C) with a phenol or a monohydric aliphatic alcohol containing not more than four carbon atoms to extract a portion (not exceeding 70 per cent by weight) of the silicon and/or aluminium. Suitable alloys are copper-aluminium (40-80 per cent copper), copper-silicon (50-92 per cent copper), cobalt-aluminium (15-55 per cent cobalt), cobalt-silicon (30-75 per cent cobalt), nickel-aluminium (30-65 per cent nickel), nickel-silicon (30-85 per cent nickel), and iron-aluminium (30-60 per cent iron). The catalysts may be used in processes of hydrogenation, dehydrogenation, hydrogenolysis, or reductive amination. In examples a granular copper-silicon alloy is extracted with vaporised methanol or liquid phenol and is used for the hydrogenation of nitrobenzene to aniline (see Group IV (b). Other examples describe the treatment of a nickel-silicon alloy with methanol, and a copper-aluminium alloy with phenol. The Provisional Specification refers also to substantially complete extraction of the alloy to form powdered catalysts, and to the use of propanols, butanols, and alcohols containing up to six carbon atoms, as extracting agents.