Regulating oxygen species for promoted deep oxidation of toluene: A comparative study of adsorbed oxygen and lattice oxygen

To explore effective way for the complete catalytic degradation of toluene at low temperature, catalysts with diverse activity of adsorbed oxygen (Oads) and lattice oxygen (Olatt) are synthesized by introducing Sr2+ into the birnessite structure. Sr modification highly improved low-temperature catalytic activity and CO2 selectivity of toluene oxidation under moist condition, especially on the BS-7.5 (Sr:Mn = 0.075) catalyst. A series of physiochemical characterizations and DFT calculations identified abundant Olatt with higher activity in Sr-doped birnessite and higher activity of Oads in pure birnessite. In situ DRIFTS analysis further confirmed that activation of Olatt introduced by Sr replacement of Mn governed the reaction process towards continuous deep oxidation of toluene. These findings provide a deeper understanding of the mechanism of toluene degradation and strongly pave a way for improving the complete catalytic oxidation performance of VOCs at low temperature over MnO2 catalysts from the aspect of regulating active oxygen-related properties.