The liquid-phase oxidation of benzene to phenol in a benzene–water bi-phase system was studied. The catalyst was dissolved in water that was saturated with benzene. Therefore benzene was oxidized to phenol in water. The produced phenol was extracted to the benzene phase. By extracting the produced phenol into the organic phase, products were easily separated from the catalyst. Therefore consecutive oxidation of phenol was prevented. The experiment was carried out in a stirred tank batch reactor.
Two kinds of catalyst systems were used. One was an Fe–H₂O₂ system and the other was a V–O₂ system. The effect of the reaction conditions such as hydrochloric acid concentration, oxidant concentration and catalyst concentration on the yield of phenol and selectivity to phenol in the Fe–H₂O₂ system was discussed. The yield became large at low hydrochloric acid concentrations, high oxidant concentrations and high catalyst concentrations. The selectivity was independent of the oxidant concentration and the catalyst concentration. But the hydrochloric acid concentration affected the selectivity. The effect of the catalyst concentration on the yield of phenol and the selectivity to phenol in the V–O₂ system was discussed. The yield was increased with an increase of catalyst concentration. Selectivity slightly decreased when the yield increased. An extractor that had aqueous alkaline, was used to separate phenol from the reactor. Selectivity was improved when phenol was taken out from the reactor by the extractor in both catalyst system cases.