Nature of active Fe species and reaction mechanism over high-efficiency Fe/CHA catalysts in catalytic decomposition of N2O

Abstract Fe/CHA catalysts (Fe/SAPO-34 and Fe/SSZ-13) with various Fe loadings were synthesized by a solid-state ion exchange method for N2O decomposition. Under the same reaction conditions, obviously superior activities of Fe/CHA catalysts were observed in comparison with the current state-of-the-art Fe/zeolite, i.e., Fe/FER. Meanwhile, Fe/CHA catalysts exhibited a robust high-temperature hydrothermal stability. The characterization results and DFT calculations indicated that the dispersion of Fe species over Fe/CHA catalysts was strongly influenced by the support nature, although SAPO-34 and SSZ-13 have similar morphology. Combined with the catalytic performance, dinuclear [HO-Fe-O-Fe-OH]2+ species were identified as the most active Fe species for Fe/CHA catalysts in N2O decomposition reaction. Furthermore, the dimeric Fe species in SSZ-13 were more active than those in SAPO-34, due to lower Fe-O binding energies. Finally, DFT calculations provided a comprehensive understanding on the N2O decomposition mechanism over Fe/CHA catalysts.