Promoting the Reactivity of Surface Lattice Oxygen in Ce Modified α-MnO2 via a Structure Reconstruction Strategy for Toluene Oxidation

Abstract

Modulating the synthesis method to construct structural defects is significant for designing MnO₂-based catalysts that exhibited superior performance. In this paper, a Ce-α-MnO₂-δ catalyst with temperature-induced phase reconstruction is successfully designed and prepared. During the high-temperature calcination process, Ce-α-MnO₂-δ underwent a phase transition from δ-MnO₂ to α-MnO₂. This structural reconstruction created numerous defects, redistributed surface charges, increased the contents of active Mn³⁺ and Ce⁴⁺. The introduction of oxygen vacancies improved the adsorption and reactivation of toluene and gaseous oxygen and sped up the depletion and replacement period of lattice oxygen. Compared with the Ce-α-MnO₂ catalyst prepared by ordinary hydrothermal method, Ce-α-MnO₂-δ has better catalytic performance and excellent durability, reaching 90% of toluene conversion at 229 °C. Furthermore, in situ DRIFTS tests illustrated that the toluene oxidation reaction adhered to the MvK mechanism, revealing the essential role of lattice oxygen in Ce-α-MnO₂-δ in the catalytic oxidation of toluene.

Keywords: Ce doped α‐MnO2; VOCs; catalytic oxidation; oxygen vacancies; phase reconstruction.