Constructing nano-structure on silver/ceria-zirconia towards highly active and stable catalyst for soot oxidation

Abstract Different to Pt-based catalysts used in diesel particulate filter (DPF), Ag/CeO 2 -ZrO 2 catalyst, whose main feature is a considerable amount of silver species exposed on the surface of catalyst, possesses outstanding soot oxidation performance even in loose contact mode and in the absence of NO x . The Ag/CeO 2 -ZrO 2 catalyst with the special structure and Ag particle ranging from 17 to 35 nm is herein prepared by controlling precipitant, and its combustion temperature T 10 and T max can be achieved as low as 254 °C and 280 °C in 5.0% H 2 O/4.8% O 2 /90.2% N 2 and loose contact mode, respectively. The H 2 -TPR and XPS characterization results show that the interaction between Ag and ceria, controlled by precipitant, leads to the high content of the species of Ag + and Ce 3+ . It can be concluded that the distribution of silver species with high superficial Ag + /Ag 0 ratio and Ag-Ce interface in Ag/CeO 2 -ZrO 2 catalyst does favor the activation and transfer of oxygen species. It appears that the adsorbed oxygen species play an important role in catalytic performance. Moreover, the catalyst/soot contact for the Ag/CeO 2 -ZrO 2 catalyst is expected to be enhanced due to the transfer of oxygen species. The prepared Ag/CeO 2 -ZrO 2 catalyst is repeatedly used five times without any appreciable loss of activity, thus shows good stability initially.