Manganese/CaCO3-based dual functional catalyst facilitating basic catalysis activity and stability for the selective oxidation of aromatics

The pore engineering of alkaline earth metal carbonates with significant specific surface area (SSA) provides promising opportunities for the optimization of surface bases and further construction of bifunctional catalysts. Herein, Mn/CaCO3, with a high dispersion of Mn species and massive basic sites, is successfully synthesized utilizing a one-pot NaCl-assisted mechanochemistry protocol. To be astonished, the SSA of Mn25/CaCO3 reaches 77 m2/g, nearly ten times more than Mn/CaCO3-Pr (prepared by precipitation). Mn25/CaCO3 exhibits unique synergetic catalysis of basic and redox catalysis in the selective oxidation of ethylbenzene (EB) to acetophenone (AP), illustrating the turnover frequency (TOF) of EB is 3 and 7.1-fold compared to Mn/CaCO3-DP (synthesized by deposition precipitation) and Mn/CaCO3-Pr. The low energy barriers in activating EB for Mn25/CaCO3 are disclosed by density functional theory (DFT), further explaining the interactions of base-redox synergetic effect. This research lays a solid foundation for the exploration of highly efficient selective aerobic oxidation catalysts.