Understanding the high performance of an iron-antimony binary metal oxide catalyst in selective catalytic reduction of nitric oxide with ammonia and its tolerance of water/sulfur dioxide.

In recent years, Fe-based catalysts for the selective catalytic reduction of NO with NH (NH-SCR) have been attracting more attention. In this work, a novel Fe-Sb binary metal oxide catalyst was synthesized using the ethylene glycol assisted co-precipitation method and was characterized using a series of techniques. It was found that the catalyst with a molar ratio of 7:3 (Fe:Sb) displayed the best NH-SCR activity with 100% conversion of NO (nitrogen oxides) over a wide temperature window and with good resistance to HO + SO at 250 °C. The X-ray photoelectron spectroscopy (XPS) and in situ diffused reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) of NO adsorption results suggested that strong electron interactions between Fe and Sb in Fe-O-Sb species existed and electrons of Sb could be transferred to Fe through the 2Fe + Sb ↔ 2Fe + Sb redox cycle. The introduction of Sb significantly improved the adsorption behaviour of NO species on the FeSbO surface, which benefitted the adsorption/transformation of NO, thereby facilitating the NH-SCR reaction. In addition, the FeSbO catalyst demonstrated a good tolerance of HO and SO, since the decomposition of NHHSO on the catalyst surface was promoted by the introduction of Sb.