Mesoporous MnCeOx solid solutions for low temperature and selective oxidation of hydrocarbons

Abstract

The development of noble-metal-free heterogeneous catalysts that can realize the aerobic oxidation of C–H bonds at low temperature is a profound challenge in the catalysis community. Here we report the synthesis of a mesoporous Mn_0.5Ce_0.5O_x solid solution that is highly active for the selective oxidation of hydrocarbons under mild conditions (100–120 °C). Notably, the catalytic performance achieved in the oxidation of cyclohexane to cyclohexanone/cyclohexanol (100 °C, conversion: 17.7%) is superior to those by the state-of-art commercial catalysts (140–160 °C, conversion: 3-5%). The high activity can be attributed to the formation of a Mn_0.5Ce_0.5O_x solid solution with an ultrahigh manganese doping concentration in the CeO₂ cubic fluorite lattice, leading to maximum active surface oxygens for the activation of C–H bonds and highly reducible Mn⁴⁺ ions for the rapid migration of oxygen vacancies from the bulk to the surface.