Gas phase oxidation of benzene to phenol ad hydroquinone by using an H 2O 2 fuel cell system

Abstract

A reaction system for the oxidation of benzene to phenol and hydroquinone in the gas phase over a carbon whisker cathode was designed by using H 2O 2 fuel cell. The rates of the formation of products increased with increasing the partial pressures of benzene and O 2 in the cathode compartment, but the rates were independent of the partial pressure of H 2 in the anode compartment. The optimum rate of formation was obtained at a cathode potential of −0.1 V (vs. Ag|AgCl) which was positive compared with that of −0.2V observed under short circuit conditions. This result suggests to cogenerate phenol and electricity. The addition of Pd to the carbon whisker cathode improved the oxidation of benzene. However, the adition of Fe 2O 3 to the carbon whisker did not affect the oxidation. Synergism of co-addition of Pd black and Fe 2O 3 to the carbon whisker for enhancing the oxidation which had been reported in the liquid phase was not observed in the gas phase. A reasonable model of the reaction mechanism specific for the oxidation of benzene in the gas phase has been proposed.