Temperature-driven mechanistic transition in propylene oxidation over Pt/CeO<sub>2</sub> ensemble catalysts.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41102217.
- Also identified by DOI 10.1038/s41467-025-64243-y and PMC identifier 12532794.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Pt/CeO<sub>2</sub> ensemble catalysts are promising for propylene (C<sub>3</sub>H<sub>6</sub>) oxidation in vehicle exhaust, yet identifying the intrinsic active sites and understanding how the metal-support interface evolves at varying reaction temperatures remains contentious. Herein, we demonstrate that H<sub>2</sub>-activated Pt/CeO<sub>2</sub> ensemble catalysts feature metallic Pt ensembles as intrinsic active sites, lowering the 50% conversion temperature by 120 °C after hydrogen activation. Various operando characterization techniques reveal an approximately 170 °C threshold temperature for the dynamic change of the reaction models. Meanwhile, kinetics and theoretical analysis illustrates that oxygen-facilitated dehydrogenation of sp<sup>3</sup> C-H bonds is the rate-determining step. At low temperatures, both C<sub>3</sub>H<sub>6</sub> and O<sub>2</sub> adsorb and activate on metallic Pt, without CeO<sub>2</sub> involvement. Once the temperature exceeds threshold, C<sub>3</sub>H<sub>6</sub> fully covers Pt sites, while O<sub>2</sub> activates over Pt-O-Ce interfaces and participates in dehydrogenation. This study highlights the dynamic nature of oxygen activation, leading to distinct reaction temperature regimes during C<sub>3</sub>H<sub>6</sub> oxidation.