Fe2O3 particles as superior catalysts for low temperature selective catalytic reduction of NO with NH3

Fe₂O₃ particle catalysts were experimentally studied in the low temperature selective catalytic reduction (SCR) of NO with NH₃. The effects of reaction temperature, oxygen concentration, NH₃]/NO] molar ratio and residence time on SCR activity were studied. It was found that Fe₂O₃ catalysts had high activity for the SCR of NO with NH₃ in a broad temperature range of 150–270°C, and more than 95% NO conversion was obtained at 180°C when the molar ratio NH₃]/NO] = 1, the residence time was 0.48 seconds and O₂ volume fraction was 3%. In addition, the effect of SO₂ on SCR catalytic activity was also investigated at the temperature of 180°C. The results showed that deactivation of the Fe₂O₃ particles occurred due to the presence of SO₂ and the NO conversion decreased from 99.2% to 58% in 240 min, since SO₂ gradually decreased the catalytic activity of the catalysts. In addition, X-ray diffraction, Thermogravimetric analysis and Fourier transform infrared spectroscopy were used to characterize the fresh and deactivated Fe₂O₃ catalysts. The results showed that the deactivation caused by SO₂ was due to the formation of metal sulfates and ammonium sulfates on the catalyst surface during the de-NO reaction, which could cause pore plugging and result in suppression of the catalytic activity.