Selective Hydroxylation of Benzene to Phenol over Fe Nanoparticles Encapsulated within N-Doped Carbon Shells

Iron-containing heterogeneous catalysts hold great promising for the direct hydroxylation of benzene to phenol. However, their catalytic performance is greatly hampered by the inherent drawbacks of iron-containing solids, in particular their hydrophilic surface structure and inevitable leaching of iron species during the Fenton process, which result in poor selectivity and durability toward phenol production. Herein, we demonstrate that the encapsulation of iron nanoparticles with N-doped carbon layer as core–shell nanostructures (Fe@NC) is a promising synthetic strategy to advance iron-containing solids for benzene hydroxylation. The rigid carbon shells conformably coating on iron cores not only protect iron from leaching but also facilitate the selective adsorption of benzene molecules on Fe@NC because of their excellent stability against acid etching and hydrophobic surface with the unique π-conjugated electron system. As a result, Fe@NC exhibit a robust catalytic durability and good yield with high selectivity for the direct hydroxylation of benzene to phenol. Benefiting from their unique core–shell nanostructures and strong host–guest electron interaction between metals and carbons, Fe@NC are expected to be promising also for other liquid-phase organic synthesis.