Modulating the Activity and SO Resistance of α-FeO Catalysts for NH-SCR of NO via Crystal Facet Engineering.

The development of Fe-based catalysts for the selective catalytic reduction of NO by NH (NH-SCR of NO) has garnered significant attention due to their exceptional SO resistance. However, the influence of different sulfur-containing species (e.g., ferric sulfates and ammonium sulfates) on the NH-SCR activity of Fe-based catalysts as well as its dependence on exposed crystal facets of FeO has not been revealed. This work disclosed that nanorod-like α-FeO (FeO-NR) predominantly exposing (110) facet performed better than nanosheet-like α-FeO (FeO-NS) predominantly exposing (001) facet in NH-SCR reaction, due to the advantages of FeO-NR in redox properties and surface acidity. Furthermore, the results of the SO/HO resistance test at a critical temperature of 250 °C, catalytic performance evaluations on FeO-NR and FeO-NS sulfated by SO + O or deposited with NHHSO (ABS), and systematic characterization revealed that the reactivity of ammonium sulfates on FeO catalysts to NO(+O) contributed to their improved catalytic performance, while ferric sulfates showed enhancing and inhibiting effects on NH-SCR activity on FeO-NR and FeO-NS, respectively; despite this, FeO-NR showed higher affinity for SO + O. This work set a milestone in understanding the NH-SCR reaction on FeO catalysts in the presence of SO from the aspect of crystal facet engineering.