GB802054A - Improvements relating to the recovery of pure phenol from crude phenol - Google Patents

Abstract

Crude phenol obtained by oxidation of cumene by way of cumene hydroperoxide is purified by passing it over a dehydration contact at 200-400 C., in order to convert hydroxyl containing compounds, present in the crude phenol into decomposition products boiling below the boiling point of phenol, and separating said decomposition products from phenol by fractional distillation. Suitable dehydration contacts are activated aluminium oxide, activated bleaching earth and phosphoric acids. The bleaching earths are preferably activated by means of hydrochloric acid before use, and a suitable phosphoric acid contact may be prepared by applying orthophosphoric or polyphosphoric acid to a carrier such as activated carbon or infusorial earth. The treatment of the crude phenol may be carried out batchwise or continuously. If the reaction is carried out continuously the dehydration step is preferably carried out in a reaction vessel arranged in advance of and connected with a distilling column for continuously separating pure phenol from the crude product. Substances formed by dehydration such as water, mesityl oxide and a -methylstyrene, and a small amount of phenol can be discharged as the head product, while the pure phenol is discharged laterally at a suitable point of the column. In the batchwise process the crude phenol which has been separated from the acetone, cumene and a -methyl styrene is dehydrated, and then subjected to fractional distillation. Examples are given using dehydration contacts of Al2O3 precipitated on infusorial earth, bleaching earth and phosphoric acid precipitated on granulated active carbon. Specification 745,343 is referred to.