Hierarchically structured Fe/ZSM-5 as catalysts for the oxidation of benzene to phenol

Different synthetic routes including carbon black and organosilane, templating and desilication were successfully employed to synthesize hierarchical Fe/ZSM-5 zeolites with improved catalytic performance in benzene oxidation to phenol with nitrous oxide. All these mesoporous zeolites show similar crystallinity, which is lower as compared to a conventional Fe/ZSM-5 catalyst. Hierarchical Fe/ZSM-5 catalysts exhibit superior catalytic performance, especially in terms of stability, in the selective oxidation of benzene to phenol with nitrous oxide. The best performance is obtained for the organosilane templated zeolites. The high initial activity and stability are related to the high interconnectivity of the micropores and mesopores, thus limiting the zeolite domain size. This results in enhanced mass transport and prevents fast blocking of the micropore space by carbonaceous byproducts.