Revelation of Mn⁴⁺-O_sur-Mn³⁺ active site and combined Langmuir-Hinshelwood mechanism in propane total oxidation at low temperature over MnO₂

Mn-based oxides exhibit attractive catalytic activity for VOCs oxidation, but the catalytic mechanism and kinetics are still significant challenges and rarely mentioned. Therefore, we prepared OMS-2 manganese oxide octahedral molecular sieve with α-MnO₂ crystal phase as model compound. By analyzing the properties of the surface chemical states of the catalysts in different reaction stages, combined with the control experiments, the coordination of Mn⁴⁺-O_sur-Mn³⁺ was confirmed as the active site at low temperature. Meanwhile, the reaction path of propane catalytic oxidation on MnO₂ surface based on condensation mechanism was proved by in-situ spectroscopy and density functional theory calculation. And kinetic studies revealed that the catalytic combustion of propane processed through Langmuir-Hinshelwood mechanism at low temperature. All these systematic study results supplied a well-defined understanding for the propane combustion over manganese oxide.