Highly Dispersed Manganese Based Mn/N–C/Al₂O₃ Catalyst for Selective Oxidation of the C–H Bond of Ethylbenzene

Abstract

The solvent-free oxidation of ethylbenzene to acetophenone with high conversion rate and selectivity is of great importance. Herein, a catalyst composed of nitrogen-doped carbon and mesoporous alumina supported manganese (Mn) was prepared by pyrolysis and calcination. We demonstrated its excellent catalytic activity (27.8%), selectivity (>99%), and stability (without a significant decrease over eight cycles) for the solvent-free oxidation of ethylbenzene with molecular oxygen. In the heterogeneous catalytic system, phenanthroline had two functions. First, it acted as a versatile chelating ligand to lock Mn and improve its dispersity. Second, it served as a nitrogen source to provide doped pyridine-N (9.4%), which promoted the adsorption and bond breaking of molecular oxygen. More abundant active Mn in the bulk phase than on the surface guaranteed the stability and reusability of the catalyst. Meanwhile, the mesoporous aluminum oxides provided a stable support for active components and adsorption sites for reactants.