Evolution of Pd chemical states and effects of C3H6 and H2O on the CO oxidation over Pd/CeO2 catalyst

Determination of dynamic changes of the supported Pd catalysts under the reaction conditions of CO/Hydrocarbons (HCs) oxidation is of great importance to the development of high performance catalysts for vehicle exhaust purification. Here we found that Pd/CeO2 catalysts dominated with either PdO or Ce1_ xPdxO2_delta species, obtained by modulating the interaction between the Pd precursors and the CeO2 support during the preparation, show different dynamic properties under the conditions of CO oxidation and also different deactivation behaviors when C3H6 is coexisting. Under the CO oxidation condition, the PdO species can be easily reduced to metallic Pd, whereas the Ce1_xPdxO2_delta species remain mainly as ionic Pd2+. In situ IR characterization revealed that the chemical states of Pd species on CeO2 during CO oxidation were related to their redox properties, which also dramatically affect the role of C3H6 and H2O in the reactions.

Automated summary

The determination of dynamic changes in supported Pd catalysts during the CO/Hydrocarbons oxidation reactions is crucial for the development of efficient catalysts for vehicle exhaust purification. This study found that Pd/CeO2 catalysts, prepared by modulating the interaction between Pd precursors and CeO2 support, exhibited different dynamic properties under CO oxidation conditions, and also showed different deactivation behaviors in the presence of C3H6. The chemical states of Pd species on CeO2 during CO oxidation were found to correlate with their redox properties, which significantly influenced the role of C3H6 and H2O in the reactions.