Low-temperature removal of aromatics pollutants via surface labile oxygen over Mn-based mullite catalyst SmMn2O5

The development of high efficient oxide catalyst is crucial to remove the aromatics pollutants. Herein, we propose a ternary mullite SmMn2O5 to catalytically oxidize benzene and toluene at a low temperature. Through a joint exploration of experimental characterizations and density functional theory calculations, the active species on the surface of the material are accessed. In the presence of the two-coordinated surface labile oxygen (Olab), the hydrothermal-synthesized mullite achieves a remarkable deep oxidation performance with T90 at 223 °C (benzene) and 228 °C (toluene), superior to most reported oxide catalysts. Simultaneously, SmMn2O5 displays no deactivation after 150 h reactions with repeating water vapor. Combining in situ DRIFTS and DFT calculations, the dissociation of maleic anhydride into acetic anhydride species on Olab active sites turns out to be the rate-controlled step with a calculated kinetic barrier of 1.253 eV. These findings of Olab allow to understand the catalytic oxidation of metal oxides at the atomic level and are thus imperative for the catalyst development.