High-performance Fe-Cu composite oxide for selective catalytic reduction of NOx with NH3: Driving of Cu on ?-Fe2O3

One kind of driving of Cu on alpha-Fe2O3 was successfully created for removing NOx. It brought excellent lowtemperature performance, high N2 selectivity and strong water and sulfur resistance. The concrete process was that Cu2+ ions entered into the crystal lattice of Fe2O3, forming solid solution with Cu-O-Fe structure and further changed the property of Fe2O3. On the one hand, Cu2+ ions adjusted the electrophilicity of Fe3+ species, thereby facilitating the generation and adsorption of NO2, nitrate and nitrite species and increasing Lewis acid sites. The increase of NH3 and NOx adsorbed species on the catalyst surface conduced to excellent lowtemperature NH3-SCR activity. On the other hand, the regulation of Cu brought abundant lattice defects to Fe2O3 which strengthened the redox ability and generated oxygen vacancy. It led to the growth of surface adsorbed oxygen, which was crucial for the fast SCR reaction. In-situ DRIFTS results revealed that the NH3 on Lewis acid sites preferred to react with weakly adsorbed NO2 through Langmuir-Hinshelwood (L-H) mechanism over the Fe-Cu composite oxide catalyst. Meanwhile, the NH3 on Lewis acid sites was also able to react with monodentate nitrates, bidentate nitrates and nitrites through L-H reaction mechanism. This work provided a new inspiration for the construction of green and efficient catalysts to remove NOx in the practical industrial applications.

Automated summary

This study successfully created a method to use Cu for removing NOx on alpha-Fe2O3, which showed excellent low-temperature performance, high selectivity, and strong water and sulfur resistance. The presence of Cu2+ ions in the crystal lattice of Fe2O3 formed a solid solution and changed its property. This adjustment of Cu2+ ions increased Lewis acid sites and lattice defects, which facilitated the generation and adsorption of NO2, nitrate, and nitrite species, leading to high NH3-SCR activity. The regulation of Cu also strengthened the redox ability and oxygen vacancy, crucial for the fast SCR reaction. The results provided inspiration for the development of green and efficient catalysts for NOx removal in practical industrial applications.