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

摘要

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