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 3 (NH 3 -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 3 -SCR activity with 100% conversion of NO x (nitrogen oxides) over a wide temperature window and with good resistance to H 2 O + SO 2 at 250 °C. The X-ray photoelectron spectroscopy (XPS) and in situ diffused reflectance infrared Fourier transform spectroscopy ( in situ DRIFTS) of NO x 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 3+ + Sb 3+ ↔ 2Fe 2+ + Sb 5+ redox cycle. The introduction of Sb significantly improved the adsorption behaviour of NO x species on the Fe 0.7 Sb 0.3 O x surface, which benefitted the adsorption/transformation of NO x , thereby facilitating the NH 3 -SCR reaction. In addition, the Fe 0.7 Sb 0.3 O x catalyst demonstrated a good tolerance of H 2 O and SO 2 , since the decomposition of NH 4 HSO 4 on the catalyst surface was promoted by the introduction of Sb.