Effects of Nd-modification on the activity and SO2 resistance of MnOx/TiO2 catalysts for low-temperature NH3-SCR

MnOx/TiO2 (MnTi) and Nd-modified MnOx/TiO2 (MnNdTi) were prepared via a coprecipitation method. The used samples were obtained by exposing the fresh catalysts to 50 ppm SO2 stream at 210 °C for 3 h and 6 h, respectively. Comparative investigations were performed on the fresh and used catalysts to identify the nature of improvement effects. As a result, the addition of Nd could improve the low temperature SCR activity of MnOx/TiO2 due to the enhanced redox property and more surface active species. SO2 resistance tests revealed that MnTi was deactivated quickly in 3 h, while MnNdTi still retained 80% of NOx conversion and deactivated in 6 h, implying that the SO2 resistance of MnNdTi was greatly enhanced. The main reason for the improvement of the SO2 resistance of MnNdTi was that the sulfation of the Mn active species was inhibited by the preferential reaction between SO2 and NdOx.