GB874864A - A process for the production of cyclohexanone - Google Patents

Abstract

Cyclohexanone is produced from aniline or nitrobenzene by a process wherein the initial material is led with an equal or greater amount of water or steam and with an excess of hydrogen at a temperature of 150 DEG -300 DEG C. over a hydrogenation catalyst, the reaction mixture formed is cooled, freed from the gaseous constituents and reacted in a pressure vessel in the liquid state at a temperature of 250 DEG -350 DEG C. in the presence of a dehydrogenation catalyst under the vapour pressure of the water containing reaction mixture set up by the prevailing temperature, the hydrogen and ammonia formed during the reaction being removed continuously from the pressure vessel. The hydrogenation is preferably carried out at 170 DEG -225 DEG C. using metallic copper, zinc, nickel or iron or their oxides or sulphides as catalyst at normal or elevated pressure. The dehydrogenation may be carried out using metallic copper, nickel or zinc or their oxides as catalyst and at a pressure of 40-60 atmospheres. The dehydrogenation may be carried out in two or more stages using the same or increased temperatures. In an example the dehydrogenation is carried out, using finely divided copper, in three reactors connected in series where the liquid catalyst mixture is kept in motion by passing steam up through the mixture and the gases evolved are carefully decompressed so there is no appreciable vapourisation of the liquid portions.