Patent GB-1362284-A (GB)
Title: Process for the production of a catalyst and its use in the produ ction of hydroxy-diphenyls
IPC: C07C37/84
Filed: 1971-10-08
Abstract: 1362284 Dehydrogenation catalysts BAYER AG 8 Oct 1971 [10 Oct 1970] 46961/71 Heading B1E [Also in Division C2] Dehydrogenation catalyst comprising (a) alkali metal carbonate and/or alkali metal sulphate, (b) copper, aluminium and chromium in elemental and/or combined form, (c) elemental nickel and, optionally, (d) nickel in combined form, which catalyst has an elemental nickel content of from 10 to 35 weight per cent, is prepared by a process wherein a catalyst precursor composition containing copper, aluminium, chromium and nickel compounds, for example hydroxide and/or carbonate and/or chromate, and having a Cu:Al:G:Ni elemental weight ratio of 0.05-1.0:1.6-8.0:6.8-17.1:40-60 is shaped into mouldings, for example tablets. having a bulk density of from 0.8 to 1.6 g/ml, preferably of from 0.9 to 1.4 g/ml, and thereafter is subjected to reducing treatment with hydrogen at a temperature of from 350 to 420‹C, preferably of from 370 to 390‹C, in two stages, the catalyst precursor composition or the catalyst produced therefrom being impregnated, either before or after shaping into mouldings or before or after the second stage of the reducing treatment, with least one alkali metal carbonate and/or alkali metal sulphate in an amount to provide an alkali metal: nickel elemental weight ratio of 0.65-3.4:40-60, preferably 0.95-2.8:40-60. The second stage of the reducing treatment may be preceded either by stabilising treatment, for example employing either ammonia and carbon dioxide in succession or very dilute air (exemplified as an air-carbon dioxide mixture) at room temperature, or by aging treatment in carbon dioxide at a temperature of 100‹C; the stabilised material may be comminuted and again shaped into mouldings having the specified bulk density before effecting the second stage of the reducing treatment which may be followed either by treatment to displace adsorbed hydrogen, employing either nitrogen or carbon dioxide, or by aging treatment in, for example, either carbon dioxide at a temperature of 100‹C or very dilute air (exemplified as an aircarbon dioxide mixture) at room temperature. The catalyst precursor composition may be obtained by a conventional procedure; as exemplified, a copper - aluminium - nickel hydroxide-carbonate mixture is precipitated from nitrate solution by means of alkali metal carbonate solution and, after washing, is reacted with ammonium bichromate. After deactivation by reason of use in the preparation of hydroxydiphenyl by dehydrogenation of wholly or partially hydrogenated hydroxydiphenyl, the catalyst may be regenerated by rinsing with an inert solvent, for example selected from xylene, phenol, diphenyl ether, cyclohexanol and dimeric condensation products of cyclohexanone; as exemplified, deactivated catalyst is regenerated by rinsing either at 170‹C with phenol or at 200‹C with a mixture of 2-cyclohexenylcyclohexanone, 2- cyclohexylidenecyclohexanone, 2 - cyclohexyl - cyclohexanone and cyclohexanone and thereafter purging at 330‹C with nitrogen (Example  5).