| abstract |
Aromatic amines (substituted anilines) of the general formula R¹-NH2 and / or corresponding cycloaliphatic amines of the general formula R²-NH2, where R¹ is a phenyl ring substituted by aliphatic groups having 1 to 20 carbon atoms and cycloaliphatic groups having 5 to 20 carbon atoms and R² is a corresponding one Substituted cyclohexyl ring means, corresponding phenols are obtained in the presence of an optionally recycled cycloaliphatic amine R²-NH2 with excess ammonia and excess hydrogen over a hydrogenation / dehydrogenation catalyst, the reaction being carried out continuously in at least two reaction zones at essentially atmospheric pressure in the gas phase is carried out in such a way that a lower temperature is maintained in a first reaction zone and a higher temperature is maintained in a second reaction zone and / or differently reactive catalysts are arranged in the reaction zones. The catalysts can e.g. be a palladium, ruthenium, rhodium or platinum catalyst or a palladium, platinum-copper or silver catalyst and are supported catalysts with aluminum oxide as a support, which additionally contains a basic substance and / or zinc, chromium, manganese, iron, cobalt or May contain nickel. |