Non-Catalytic Reactions Producing Phenol From Benzene with Hydrogen Peroxide and Water At Near and Supercritical Water Conditions

Phenol, a bulk chemical commodity used in a wide variety of applications including plastics manufacture, is conventionally produced by reacting benzene and propylene under pressure in the presence of acid catalysts with acetone as a side product. A novel, non-catalytic means of producing phenol involves reacting hydrogen peroxide in water and benzene at near-critical and supercritical water conditions. The principal products of the supercritical water reaction are phenol, diphenyl, and trace amounts of dibenzofuran. Remarkably phenol is produced in greater than a 2:1 stoichiometric ratio with hydrogen peroxide, which may indicate that the reaction is driven by hydroxyl radicals initiated by the decomposition of hydrogen peroxide. The potential advantages of this reaction are that it eliminates propylene as a feedstock and the need to find a market for acetone. Furthermore, since no catalyst or additional solvents are utilized, high pressure and temperature water reactions between hydrogen peroxide and benzene presents a potential, new, green process for producing phenol. The reaction between benzene and hydrogen peroxide was evaluated in a 30 mL 316 stainless steel bolt-closure batch reactor at conditions up to 30 MPa at 400 C. The effects of concentration, temperature, and pressure upon selectivity are discussed and a possible mechanism is proposed.