Rhodium catalysts, process for their preparation and process for the preparation of optionally substituted diphenyl amine using the rhodium catalysts

摘要

Diphenylamine optionally substituted by alkyl or alkoxy groups can be prepared by treating appropriately substituted dicyclohexylamine over catalysts containing 0.05-5% by weight of rhodium at 250-450 ° C. and 1-10 bar H2. In addition to rhodium, the catalysts also contain at least one other platinum metal from the group of palladium, platinum and iridium on a support, which contains the noble metals in a total amount of 0.05-5% by weight and a percentage by weight of rhodium in all noble metals of 10-90 % and which also contains additives of 1-6% by weight of an alkali metal hydroxide and 1-6% by weight of an alkali metal sulfate. All percentages are based on the total weight of the catalyst.