x and Hg 0 from simulated flue gas by Ce x Zr y Mn z O 2/r-Al 2O 3: the performance and its mechanism]]>

摘要

In this study, series of Ce~( x )Zr~( y )Mn~( z )O~(2)/r-Al~(2)O~(3)catalysts were prepared by impregnation method and explored to co-purification of NO~( x )and Hg_(0)at low temperature. The physical and chemical properties of the catalysts were investigated by XRD, BET, FTIR, NH~(3)-TPD, H~(2)-TPR, and XPS. The experimental results showed that 10% Ce~(0.2)Zr~(0.3)Mn~(0.5)O~(2)/r-Al~(2)O~(3)yielded higher conversion on co-purification of NO~( x )and Hg_(0)than the other prepared catalysts at low temperature, especially at 200–300?°C. 91% and 97% convert rate of NO~( x )and Hg_(0)were obtained, respectively, when 10% Ce~(0.2)Zr~(0.3)Mn~(0.5)O~(2)/r-Al~(2)O~(3)catalyst was used?at 250?°C. Moreover, the presence of H~(2)O slightly decreased the removal of NO~( x )and Hg_(0)owing to the competitive adsorption of H~(2)O and Hg_(0). When SO~(2)was added, the removal of Hg_(0)first increased slightly and then presented a decrease due to the generation of SO~(3)and (NH~(4))~(2)SO~(4). The results of NH~(3)-TPD indicated that the strong acid of 10% Ce~(0.2)Zr~(0.3)Mn~(0.5)O~(2)/r-Al~(2)O~(3)improved its high-temperature activity. XPS and H~(2)-TPR results showed there were high-valence Mn and Ce species in 10% Ce~(0.2)Zr~(0.3)Mn~(0.5)O~(2)/r-Al~(2)O~(3), which could effectively promote the removal of NO~( x )and Hg_(0). Therefore, the mechanisms of Hg_(0)and NO~( x )removal were proposed as Hg (ad)?+?[O]?→?HgO (ad), and 2NH~(3)/NH~(4)_(+)(ad)?+?NO~(2)(ad)?+?NO (g)?→?2?N~(2)?+?3H~(2)O/2H_(+), respectively. Graphical abstract ?.