DFT studies of the CH₄-SCR of NO on Fe-doped ZnAl₂O₄(100) surface under oxygen conditions

The catalytic reduction performance of NO on the surface of Fe-doped ZnAl₂O₄ (100) was calculated based on DFT. The adsorption of NO and other molecules, the change of reaction energy of CH₄ and C₂H₄ as reducing agents, and the activation energy barrier of CH₄ were studied. It was found that the best adsorption energy of NO is -2.166 eV. Compared with Al and Zn sites, doped Fe atoms are better adsorption catalytic sites. At temperatures of 300 K and 600 K, the molecules will move in the direction of the Fe atoms. O₂ adsorption will repel NO, reduce its adsorption energy, and cause NO to lose electrons and be oxidized. The reaction enthalpy with CH₄ as the reducing agent is -7.02 eV, and with C₂H₄ is -3.45 eV. Transition state calculations show that O reduces the dissociation barrier of CH₄ by about 2 eV. The smaller adsorption energy and negative reaction enthalpy of the product indicate that the iron-doped ZnAl₂O₄ has a good catalytic NO potential. This also provides a basis for future research on the catalytic mechanism of different hydrocarbons.