Revealing the effect of electronic interaction between dual redox sites on CeO2-Fe2O3 NH3-SCR catalyst through interface contact tailoring

Due to the requirements of different applications environments, higher catalytic activity or SO2 and H2O tolerance, the binary or ternary metal oxide NH3-SCR catalysts with dual redox sites have been widely studied in recent years. The electronic interaction between the dual redox sites has a significant impact on the catalyst performance. Herein, a series of CeO2-Fe2O3 composite catalysts with continuously enhanced interface contact as well as electronic interactions were prepared through a facile grinding method. The activity tests showed that neither the catalyst with the least interfacial contacts nor the one with the greatest interfacial contacts exhibited the highest NOx removal activity. The comprehensive characterizations demonstrated that the apparent physicochemical properties including the NH3 adsorption ability, redox property, and so on, changed in favor of NH3SCR reaction when enhancing the interface contact for the CeO2-Fe2O3 composite catalysts. However, the reaction mechanism as well as the reactivity of main NH3 and NO adsorbed species were also altered by the electronic interactions between Ce and Fe active species. The unsatisfactory NOx removal activity of the CeO2Fe2O3 catalyst with strongest electronic interactions between Ce and Fe active species was explained by the reactivity of main NH3 and NO adsorbed species. This work can provide new ideas for improving the performance of NH3-SCR catalysts through changing the interface contact and electronic interaction between the dual redox sites.