| abstract |
The present invention relates to a method for continuously preparing cyclohexanone from phenol making use of a catalyst comprising at least one catalytically active metal selected from platinum and palladium comprising a) hydrogenating phenol to form a product stream comprising cyclohexanone and unreacted phenol; b) separating at least part of the product stream, or at least part of the product stream from which one or more components having a lower boiling point than cyclohexanone have been removed, into a first fraction comprising cyclohexanone and a second fraction comprising phenol and cyclohexanol, using distillation; c) separating the second fraction into a third fraction, rich in cyclohexanol, and a fourth fraction, rich in phenol and, using distillation; d) subjecting at least part of the fourth fraction to a further distillation step, thereby forming a fifth fraction and a sixth fraction, wherein the fifth fraction is enriched in phenol compared to the sixth fraction, and wherein the sixth fraction comprises side-products having a higher boiling point than phenol, and phenol, wherein step d) is carried out in a vacuum distillation column equipped with trays in the lower part of the column, and wherein in the upper part of the column, i.e. in the part above the feed inlet, packing material is present instead of trays in at least part of said upper part, which packing material has a comparable or improved separating efficiency, and provides a reduction of the pressure drop by at least 30%, preferably more than 50%, as compared to the case with trays in the upper part, under otherwise similar distillation conditions. |