Effects of microwave radiation on one-step oxidation of benzene to phenol with nitrous oxide over Fe-ZSM-5 catalyst

Direct oxidation of benzene to phenol over Fe-ZSM-5 catalyst was chosen as a model reaction to characterize the influence of microwave irradiation on ad-/desorption processes during heterogeneously catalyzed reactions. The direct oxidation of benzene was investigated under different reaction conditions (temperature, residence time, reactant-concentrations) and microwave power in a specially designed reactor. The results obtained by additional microwave radiation were compared to those obtained by conventional heating under similar reaction conditions. In addition, ex situ TG-MS analyses were also conducted to study the sorption behaviour. Extensive investigations were carried out to determine adsorption–desorption effects (benzene, phenol and a mixture of both) and the coking behaviour under microwave conditions. Microwave induces a trend towards increased phenol selectivity and relative deactivation during the reaction. However, there was no conclusive improvement in the performance was obtained by means of microwave heating.