A Process for Revamping a Plant for the Production of Cyclohexanone

A process for the construction of a second chemical plant, which second chemical plant is suitable for the separation of cyclohexanone from a second mixture, which second mixture comprises reaction products from the hydrogenation of phenol, said process comprising:

• a) providing a first chemical plant, which first chemical plant is suitable for the separation of cyclohexanone from a first mixture, which first mixture comprises reaction products from the oxidation of cyclohexane, and which first plant comprises:
• i) a distillation column suitable for distilling overhead cyclohexane;
• ii) a distillation column suitable for distilling overhead cyclohexanone;
• iii) a distillation column suitable for distilling overhead components having a lower boiling point than cyclohexanone;
• iv) a distillation column suitable for distilling overhead a mixture comprising cyclohexanol and cyclohexanone;
• v) a cyclohexane oxidation unit suitable for the oxidation of cyclohexane;
• and
• vi) a heat recovery unit suitable for the recovery of heat from off-gas from the cyclohexane oxidation unit suitable for the oxidation of cyclohexane;
• b) disabling i) said distillation column suitable for distilling overhead cyclohexane from said first chemical plant, v) said cyclohexanone oxidation unit and vi) said heat recovery unit, and wherein said second chemical plant comprises a distillation column suitable for distilling overhead cyclohexanone, wherein said cyclohexanone is part of a third mixture, which third mixture comprises said second mixture from which components having a lower boiling point than cyclohexanone have been removed;
• and
• c) adding to said first chemical plant a phenol hydrogenation unit.

A chemical plant suitable for the separation of cyclohexanone from a second mixture, which second mixture comprises reaction products from the hydrogenation of phenol, which chemical plant comprises:

• a) a distillation column suitable for distilling overhead components having a lower boiling point than cyclohexanone;
• b) a distillation column suitable for distilling overhead cyclohexanone;
• c) a distillation column suitable for distilling overhead a mixture comprising cyclohexanol and cyclohexanone in a wt.:wt. ratio of at least 4:1;
• d) a cyclohexanol dehydrogenation unit suitable for the dehydrogenation of cyclohexanol to form a mixture comprising cyclohexanol and cyclohexanone;
• e) a feed line suitable for recycling said mixture comprising cyclohexanol and cyclohexanone formed in d) from d) to a);
• and
• f) a phenol hydrogenation unit that produces a mixture comprising reaction products from the hydrogenation of phenol;
• characterised in that at least one of a) and d) have been used in a chemical plant for the separation of cyclohexanone from a first mixture, which first mixture comprises reaction products from the oxidation of cyclohexane;
• and wherein at least one of c) and d) has a capacity greater than that necessary for the separation of cyclohexanone from the second mixture, based on the chemical plant operating at full capacity of a) and b), wherein capacity of the plant or distillation column means the mass of cyclohexanone separated in a given time, and wherein capacity of the cyclohexanol dehydrogenation unit means the weight of cyclohexanol that is converted into cyclohexanone unit per unit time.

A process for the separation of cyclohexanone from a second mixture, which second mixture comprises reaction products from the hydrogenation of phenol, said process comprising:

• a) distilling overhead in a distillation column components having a lower boiling point than cyclohexanone;
• b) distilling overhead in a distillation column cyclohexanone;
• c) distilling overhead in a distillation column a mixture of cyclohexanol and cyclohexanone in a wt.:wt. ratio of at least 4:1;
• d) dehydrogenating in a cyclohexanol dehydrogenation unit cyclohexanol distilled overhead in c) to form a mixture comprising cyclohexanol and cyclohexanone;
• e) recycling the mixture comprising cyclohexanol and cyclohexanone formed in d) from d) to a);
• and
• f) hydrogenating phenol in a phenol hydrogenation until that produces a mixture comprising reaction products from the hydrogenation of phenol;
• characterised in that at least one of the distillation column of a) and the cyclohexanol dehydrogenation unit of d) have been used in a chemical plant for the separation of cyclohexanone from a first mixture, which first mixture comprises reaction products from the oxidation of cyclohexane;
• and wherein at least one of c) and d) is carried out at a rate below the capacity of, respectively, the distillation column of c) and the cyclohexanol dehydrogenation unit of d), wherein capacity of the plant or distillation column means the mass of cyclohexanone separated in a given time, and wherein capacity of the cyclohexanol dehydrogenation unit means the weight of cyclohexanol that is converted into cyclohexanone unit per unit time.