Dynamic observation: The rapid oxidative redispersion of large Pt nanoparticles supported on ceria‐based oxide in autoexhaust catalysts is demonstrated in the absence of Cl by in situ XANES analysis. An atomic migration model accounts for the observed redispersion through the trapping of Pt species at sites on the Ce support that exhibit strong interactions between the Pt oxide and the support.
Electronic and structural dynamics of an industrially relevant Pt/CeO2–ZrO2 catalyst with an ordered arrangement of Ce and Zr ions during oxygen storage/release processes at 573–773 K were studied in real time by time‐resolved energy‐dispersive XAFS at the Zr K edge and Ce L3 edge (see experimental setup). On the basis of these results, the roles of Ce and Zr ions in the function of the mixed‐oxide catalyst were elucidated.
Suppression of noble metal sintering is a very important approach in the development of automotive three-way catalysts. The investigation into the Pt sintering behavior revealed that the formed Pt-O-M (M: cation of oxide, i.e., cerium oxide) bond acted as an anchor to suppress the Pt sintering, and that the strength of the Pt-oxidesupport interaction was well correlated with the electron density of oxygen in the support oxide. To achieve a good balance between catalytic activity and the sintering suppression, ceria based oxide support was verified to be suitable for Pt, and zirconia based oxide support was appropriate support for Rh. Through optimizing the configuration of Pt and Rh in the catalyst, a novel three-way catalyst was developed successfully, and this catalytic activity is far superior to the conventional catalyst, but with lower noble metal content.
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