Enhanced performance of Pt-based diesel oxidation catalyst via defective MnOx: The role of Pt/MnOx interface

Abstract

To strengthen the interface effect of Pt with MnOx, manganese oxides with different defective concentration were obtained via removing oxygen under reduction treatment. The excellent performance on the Pt-based oxidation catalyst with optimum reduction temperature is 250 °C, and it's the light-off temperature of CO, C3H6 and NO are 170 °C, 180 °C and 185 °C, respectively, and the highest NO maximum conversion of 76%. The defect on MnOx could induce the adsorption of Pt2+ to produce the higher platinum dispersion and more active oxygen species. The abundant oxygen vacancies on manganese manganite would transfer to the subsurface, reducing the Mn valence and affecting the electronic effect of Pt with MnOx. Meanwhile, the existence of interfacial structure induces the shrinkage of platinum cell with the reduction of lattice parameter, because of the doping of Mn ion. The strong interaction of Pt with MnOx could promote the reduction of manganese oxides at the lower temperature. The interface of Pt-MnOx could accelerate the oxygen mobility and facilitate the formation of more bridged nitrates and chelating nitrates. Due to the interfacial structure of Pt with MnOx, the low temperature catalytic performance and high NO conversion of catalyst are remarkably improved.