Promotion effect of urchin-like MnO @PrO hollow core-shell structure catalysts for the low-temperature selective catalytic reduction of NO with NH.

A MnO @PrO catalyst with a hollow urchin-like core-shell structure was prepared using a sacrificial templating method and was used for the low-temperature selective catalytic reduction of NO with NH. The structural properties of the catalyst were characterized by FE-SEM, TEM, XRD, BET, XPS, H-TPR and NH-TPD analyses, and the performance of the low-temperature NH-SCR was also tested. The results show that the catalyst with a molar ratio of Pr/Mn = 0.3 exhibited the highest NO conversion at nearly 99% at 120 °C and NO conversion greater than 90% over the temperature range of 100-240 °C. Also, the MnO @PrO catalyst presented desirable SO and HO resistance in 100 ppm SO and 10 vol% HO at the space velocity of 40 000 h and a testing time of 3 h test at 160 °C. The excellent low-temperature catalytic activity of the catalyst could ultimately be attributed to high concentrations of Mn and adsorbed oxygen species on the catalyst surface, suitable Lewis acidic surface properties, and good reducing ability. Additionally, the enhanced SO and HO resistance of the catalyst was primarily ascribed to its unique core-shell structure which prevented the MnO core from being sulfated.