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

Different to Pt-based catalysts used in diesel particulate filter (DPF), Ag/CeO2-ZrO2 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 NOx. The Ag/CeO2-ZrO2 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 degrees C and 280 degrees C in 5.0% H2O/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 Ce3+. It can be concluded that the distribution of silver species with high superficial Ae/Ag ratio and Ag-Ce interface in Ag/CeO2-ZrO2 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/CeO2-ZrO2 catalyst is expected to be enhanced due to the transfer of oxygen species. The prepared Ag/CeO2-ZrO2 catalyst is repeatedly used five times without any appreciable loss of activity, thus shows good stability initially. (C) 2016 Elsevier B.V. All rights reserved.