Optimizing Gasoline Soot Oxidation of Pt/Ceo2-Zro2 Catalysts Via Improving of Catalyst-Soot Contact Efficiency and Adjusting Pt Microchemical State

The solid (catalyst)-solid (soot) contact efficiency and microchemical state of noble metals have a great influence on the soot oxidation performance of catalysts. In this study, CeO2-ZrO2 composite oxides with different pore structures were prepared by coprecipitation and microsphere template-assisted coprecipitation methods, and the relevant Pt/CeO2-ZrO2 with different initial Pt microchemical states was synthesized by impregnation and liquid-phase chemical reduction methods. The purpose of obtaining excellent catalytic activity is to improve the generation and transfer of active oxygen species in the catalyst. Soot oxidation under O2 and O2 + NO conditions was used to evaluate the prepared catalysts, and the results showed that CeO2-ZrO2 (CZ) with a porous structure can provide effective contact between soot and the catalyst, showing a T50 value almost 90 °C lower than the CeO2-ZrO2 reference sample (CZ-ref) under 1%O2/N2 reaction conditions. In addition, the oxygen molecule adsorption-activation ability and catalytic cycle process are closely related to the initial Pt microchemical state. Pt loaded through the impregnation method does not promote activity with oxidized Pt species as the dominant component, but adjusting the Pt microchemical state with more metallic Pt species using the liquid-phase chemical reduction method results in an obvious activity improvement in the absence of NO. In the presence of NO, both oxidized and metallic Pt species exhibit enhanced soot oxidation for CZ-ref series catalysts, and this promotion effect is more obvious in metallic Pt species