AI Article Synopsis
- Developing advanced three-way catalysts is crucial for controlling emissions during cold starts, focusing on lower temperature efficiency.
- Density functional theory and microkinetics simulations reveal that NO formation at low temperatures primarily occurs through a dimer on metallic Pd, but re-oxidation of Pd limits NO conversion and requires richer conditions for high nitrogen selectivity.
- Doping CeO with Fe enhances oxygen vacancies, leading to improved nitrogen selectivity, which is supported by experimental evidence from a Pd catalyst on Fe-doped CeO made via flame spray pyrolysis.
Article Abstract
Developing better three-way catalysts with improved low-temperature performance is essential for cold start emission control. Density functional theory in combination with microkinetics simulations is used to predict reactivity of CO/NO/H mixtures on a small Pd cluster on CeO(111). At low temperatures, NO formation occurs via a NO dimer over metallic Pd. Part of the NO intermediate product re-oxidizes Pd, limiting NO conversion and requiring rich conditions to obtain high N selectivity. High N selectivity at elevated temperatures is due to NO decomposition on oxygen vacancies. Doping CeO by Fe is predicted to lead to more oxygen vacancies and a higher N selectivity, which is validated by the lower onset of N formation for a Pd catalyst supported on Fe-doped CeO prepared by flame spray pyrolysis. Activating ceria surface oxygen by transition metal doping is a promising strategy to improve the performance of three-way catalysts.
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Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8154324 | PMC |
| http://dx.doi.org/10.1021/acscatal.1c00564 | DOI Listing |
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