An experimental and DFT study of the adsorption and oxidation of NH3 on a CeO2 catalyst modified by Fe, Mn, La and Y

• Compared transition and rare earth dopants on ceria.
• Surface acidity and reducibility are studied by experimental and DFT methods.
• NH3 oxidation is carried out to confirmation the properties.
• Fe and Mn doped CeO2 has better reducibility and larger surface acidities.

Four metals (Fe, Mn, La and Y) doped onto CeO2 were prepared by coprecipitation, and the corresponding slab models were constructed by DFT calculations to investigate the influences of dopants on the adsorption and oxidation of NH3 molecules. A higher reducibility, a larger quantity of labile surface oxygen and a greater extent of surface distortion were responsible for the higher NH3 activation of the Fe–Ce and Mn–Ce than the La–Ce and Y–Ce samples. Moreover, Fe–Ce and Mn–Ce provided more NH3 adsorption sites on the Lewis acid sites than La–Ce and Y–Ce, and the Mn dopant also generated a tightly bonded interaction with NH4+ on the Brønsted acid sites. The Mulliken charges of NH3 were also in agreement with the results above and indicated that the lone pair electrons of nitrogen can transfer to Fe or Mn cations, whereas this process is less favorable for the La or Y cations. The improvement of both the reducibility and acidity by Fe and Mn doping led to higher NH3 oxidation, whereas the enhancement was not considerable for La–Ce and Y–Ce.

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