Study On The Direct Hydroxylation Of Benzene To Phenol With Hydrogen Peroxide

Phenol is one of the important raw materials in organic chemical industry. It was mainly used for producting resins, pharmaceutical intermediates, pesticides, perfumes, dyes, additives and other fine chemicals materials. In recent years, due to the rapid development of Chinese economy, the demand rate for phenol was growing fast. Although phenol production has also increased year by year, it still couldn’t meet the consumption of phenol. Traditional production of phenol was primarily by the reaction of benzene with propylene. The first product was the cumene, then the cumene was oxidated to phenol. However, This method has many disadvantages like long process, the consumption of propylene and the production of by-product. Therefore, the exploration of a green preparation phenol attracts much attention and it has become a hot research topic. The direct oxidation of benzene to phenol by hydrogen peroxide in one step has become one of the green reaction because it has many advantages, such as the only by-product of water, the environmentally friendly process, the facile step, the high atom economy and low cost. The contents and results are summarized as follows:The CuxOy@C catalyst was directly prepared with glucose and copper(II) sulfate by a one-pot hydrothermal method. The catalytic performance was investigated for the hydroxylation of benzene to phenol with hydrogen peroxide as the oxidant. The features of the reaction system with the prepared heterogeneous catalyst were studied by various reaction parameters including reaction temperature, catalyst amount, hydrogen peroxide amount, reaction time, effect of solvents and additives. With glucose as the additive, the maximum yield of phenol was 13.0% under the reaction conditions of 1.0 mL benzene,3.0 mL acetonitrile,50 mg catalyst,3.0 mL H2O2, at 50 ℃ for 4 h.To further improve the the catalytic performance, the CuxOy@C catalyst was treated with hydrogen peroxide and hydrazine hydrate respectively, and the catalysts CuxOy@C-HP, CuxOy@C-HP-HN, CuxOy@C-HN and CuxOy@C-HN-HP were obtained. The different species of copper were detected in the CuxOy@C-HP. Moreover, the copper oxalate was generated in CuxOy@C-HP. It was also found glucose employed as additives could improve the yield of phenol.Under the reaction system of direct oxidation of benzene to phenol, the adsorption properties of benzene and phenol were studied with hydrophilic carbon and activated carbon as adsorbents, respectively. The effect of solvent and the initial concentration for adsorption of benzene and phenol was discussed. The results showed that adsorption equilibration time of benzene and phenol adsorbed by activated carbon and hydrophilic carbon is about 20 and 25 minutes, respectively,while solvents have little effect on the adsorption of equilibrium time. From the influence of different solvents on the adsorption of benzene and phenol under the condition of same adsorbent, it was found that the ethanol was the best solvent. The hydrophilic carbon for the adsorption of benzene was better than the activated carbon; the adsorption of phenol on activated carbon adsorption of phenol was better than hydrophilic carbon.