Highly dispersed FeOx was impregnated onto CeO2 using the unique precursor Na/Fe-ethylenediaminetetraacetate (NaFeEDTA) at varying Fe surface density (0-1.5 Fe/nm2). These catalysts were used for NO reduction by CO and were compared to a more traditional Fe(NO3)3 precursor impregnated on Na-promoted CeO2. Extensive characterization and spectroscopic measurements showed that NaFeEDTA produced a narrower distribution of smaller, noncrystalline, surface FeOx species with excellent redox cyclability (Fe3+ → Fe2+). The NaFeEDTA catalysts exhibited corresponding higher steady-state activity for NO reduction by CO. In situ X-ray absorption spectroscopy with simultaneous gas-phase monitoring indicated that NO conversion began concurrent with reduction of Fe and Ce, suggesting that NO reduction occurred at a reduced Fe-O-Ce interface site. These results illustrate a new synthesis-structure-activity relationship for NO reduction by CO over redox-cycling FeOx sites that may support future rational design of emission control catalysts without Pt-group metals or zeolites.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films