Low-temperature selective catalytic reduction of NO with NH3 over an FeOx/β-MnO2 composite

A series of Fe-modified beta-MnO2 (FeOx/beta-MnO2) composite catalysts were prepared by an impregnation method with beta-MnO2 and ferro nitrate as raw materials. The structures and properties of the composites were systematically characterized and analyzed by X-ray diffraction, N-2 adsorption-desorption, high-resolution electron microscopy, temperature-programmed reduction of H-2, temperature-programmed desorption of NH3, and FTIR infrared spectroscopy. The deNO(x) activity, water resistance, and sulfur resistance of the composite catalysts were evaluated in a thermally fixed catalytic reaction system. The results indicated that the FeOx/beta-MnO2 composite (Fe/Mn molar ratio of 0.3 and calcination temperature of 450 degrees C) had higher catalytic activity and a wider reaction temperature window compared with beta-MnO2. The water resistance and sulfur resistance of the catalyst were enhanced. It reached 100% NO conversion efficiency with an initial NO concentration of 500 ppm, a gas hourly space velocity of 45 000 h(-1), and a reaction temperature of 175-325 degrees C. The appropriate Fe/Mn molar ratio sample had a synergistic effect, affecting the morphology, redox properties, and acidic sites, and helped to improve the low-temperature NH3-SCR activity of the composite catalyst.

Automated summary

A series of Fe-modified beta-MnO2 composite catalysts were prepared and characterized. The FeOx/beta-MnO2 composite with a Fe/Mn molar ratio of 0.3 and calcination temperature of 450 degrees C showed higher catalytic activity and improved water and sulfur resistance compared to beta-MnO2. The appropriate Fe/Mn molar ratio sample exhibited synergistic effects, affecting the morphology, redox properties, and acidic sites, and enhanced the low-temperature NH3-SCR activity of the composite catalyst.