Improvements in or relating to the recovery of phenol from phenol-brine mixtures by distillation

摘要

Phenol is recovered from salt mixture obtained in the synthetic production of phenol, e.g., by the chlorobenzene process, by allowing the mixture to settle out into two layers the upper of which is rich in phenol while the lower is rich in brine, separating the layers, evaporating the upper phenol layer to separate out the salt and fractionating the salt free phenol to recover phenol as a bottoms product and water as a top product. The lower layer is stripped to remove phenol as vapor which is added to the salt free phenol undergoing fractionation. The phenolbrine mixture is fed to separator 12. The upper phenol layer is fed to evaporator 32 from which salt is removed through 34 while the phenol vapours are passed to tower 37. The lower brine layer is stripped in tower 16 and the condensate separated into phenol and water layers in separator 26 the phenol layer being fed through line 26 to tower 37 while the water layer is refluxed to tower 16. In a modification the phenol layer is returned to the separator 12. The fractionation in tower 37 is preferably effected in presence of a water entrainer, e.g., toluene charged to the system through line 46. The tower 16 may be operated at increased pressure, viz., 3 atmospheres.ALSO:Phenol is recovered from salt mixture obtained in the synthetic production of phenol, by allowing the mixture to settle out into two layers, the upper one of which is rich in phenol, while the lower is rich in brine, separating the layers, evaporating the upper phenol layer to separate out the salt and fractionating the salt-free phenol to recover phenol as a bottoms product and water as a top product. The lower layer is stripped to remove phenol as vapour which is added to the salt-free phenol undergoing fractionation. The phenol-brine mixture is fed to separator 12. The upper phenol layer is fed to evaporator 32 from which salt is removed through 34 while the phenol vapours are passed to tower 37. The lower brine layer is stripped in tower 16 and the condensate separated into phenol and water layers in separator 26, the phenol layer being fed to tower 37, while the water layer is refluxed to tower 16. In a modification, the phenol layer is returned to the separator 12. The fractionation in tower 37 is preferably effected in presence of a water entrainer, e.g. toluene charged to the system through line 46. The tower 16 may be operated at increased pressure, viz. 3 atmospheres.