Insight into synergistic effect in bimetallic Ag-Cu/CeMnOx catalysts for soot combustion

The soot combustion process has high importance in air purification and reducing air pollution by vehicles with internal combustion engines. Catalysts based on transition metal oxides, especially those based on Ce and/or Mn, have high activity towards combustion of small soot particles, and the addition of silver and copper is a promising way to enhance their catalytic properties. Here, the effects of the method of Ag and Cu introduction into the mixed CeO 2 -MnO x oxides as well as the effect of Ag/Cu molar ratio on the soot combustion activity are considered. Co-impregnation of CeO 2 -MnO x with Cu and Ag precursors leads to an insignificant activity growth, while the sequential impregnation or reductive impregnation accompanied by the Ag reduction leads to a significant activity growth due to the synergistic effect of Ag and Cu. The metal states and interactions with the CeO 2 -MnO x support are discussed. The correlation between the presence of Cu + /0 and small metallic Ag nanoparticles, Ag-Cu interaction, and catalytic activity in soot combustion is revealed. • Synergistic effect in bimetallic Ag-Cu/CeMnO x catalysts is considered. • Effect of method of Ag and Cu introduction into CeO 2 -MnO x is discussed. • Ag/Cu molar ratio affects soot combustion activity. • Sequential or reductive impregnation leads to a significant activity growth. • Correlation between states of metal species, Ag-Cu interaction, and catalytic activity.