Promoted cobalt oxide catalysts

摘要

Hexamethylene diamine is formed by the liquid phase hydrogenation of adiponitrile at 50-170 DEG C. in the presence of a cobalt oxide catalyst promoted by 0.03-1 per cent by weight of silica or titania and prepared by introducing colloidal silica or titania into a purified aqueous solution of cobalt nitrate, precipitating cobalt carbonate therefrom, washing, converting to oxide at 150-500 DEG C., forming into pellets, sintering at 600-1200 DEG C., cooling, and reducing with hydrogen (see Group III). In an example the nitrile mixed with anhydrous ammonia is treated with hydrogen in the presence of the catalyst at a pressure of 4000 p.s.i. and a temperature of 150 DEG C. for 2 hours. Other constituents of the catalyst may be barium, iron, nickel and alumina.ALSO:Cobalt oxide catalyst promoted by 0.03-1 per cent by weight of the silica or titania is prepared by introducing colloidal silica or titania into a purified aqueous cobalt nitrate solution, precipitating cobalt carbonate therefrom, washing, converting to oxide at 150 DEG -500 DEG C., forming into pellets, sintering at 600 DEG -1200 DEG C., cooling and reducing with hydrogen. The cobalt nitrate solution may be formed by digesting an excess of commercial cobalt with aqueous nitric acid to a pH of 5.4 and filtering off impurities. The silica may be added as a silica sol and titania as titania gel. In an example the carbonate is precipitated by heating the nitrate solution to 85 DEG C. and adding ammonium carbonate; the mixture is digested for 2 hours at 85 DEG C., filtered, washed, ignited at 400 DEG C., kneaded with water, redried, granulated, mixed with a stearin lubricant and pelletted. The pellets are sintered at 700 DEG -900 DEG C. for 3 hours and then reduced at 400 DEG C. in a nitrogen-hydrogen mixture, the hydrogen content of which is gradually increased. Reference is made to the inclusion of barium, iron nickel and alumina in the catalyst. The catalyst is useful for the liquid phase hydrogenation of adiponitrile to hexamethylenediamine (see Group IV(b)).