Catalytic Behavior of Ag-Mn Catalyst for Efficient Toluene Removal at Low Temperature: Effect of Redox Property

Ag-Mn bimetallic catalysts were prepared by liquid-phase redox method and discussed their synergistic effect on the catalytic oxidation of toluene. The activity order of the catalysts was: Ag-Mn > Mn > Ag-Mn-R > Mn-R. The addition of Ag caused some K+ to be substituted over Ag-Mn, which resulted in the collapse of the structure, and led to more lattice defects and increased the active species. Furthermore, the Ag-Mn catalyst contained a large amount of Mn4+ and Olatt species, the best low-temperature reducibility and the lowest oxygen desorption temperature. After the reduction treatment, the high-valent manganese ions decreased, and the lattice oxygen concentration was greatly reduced. Besides, the high concentration of high valence manganese, easily released lattice oxygen and oxidized silver of Ag-Mn could contribute to the superior catalytic performance. The mechanism followed by toluene → benzoate → benzoquinone → manganese carbonate → CO2 + H2O. The nanorod structure of potassium manganese ore became thinner after Ag doping, which increased the lattice defects and more oxygen vacancies. The surface oxygen consumed in the oxidation process was supplemented by the release of a large amount of lattice oxygen, obtaining continuous toluene oxidation performance. The catalytic oxidation of toluene followed MVK mechanism over Ag-Mn. Toluene was first adsorbed on the oxygen vacancy to form benzoate, and then further oxidized to benzoquinone, carbonate and finally oxidized to CO2 and H2O. [Display omitted]