Effect of molybdenum on mercury oxidized by V2O5–MoO3/TiO2 catalysts
Effect of molybdenum on mercury oxidized by V2O5–MoO3/TiO2 catalysts
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DOI：
10.1016/j.cej.2014.05.071
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发表时间：
2014-10
影响因子：
15.1
通讯作者：
Bo Zhao;Xiaowei Liu;Zijian Zhou;H. Shao;W. Chao;Junping Si;Minghou Xu
中科院分区：
文献类型：
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作者：
Bo Zhao;Xiaowei Liu;Zijian Zhou;H. Shao;W. Chao;Junping Si;Minghou Xu
采用溶胶-凝胶法制备了不同V2 O 5和MoO 3含量的V2 O 5-MoO 3/TiO 2催化剂粉末。首次在实验室对粉末在汞氧化SCR催化剂中的应用进行了测试。结果表明，钛钒钼催化剂比钛钒催化剂具有更高的汞氧化效率。特别是V2 O 5-MoO 3/TiO 2催化剂中含有5wt%的五氧化二钒和5wt%的三氧化钼（TV 5 M5），即使只有6%O2存在，它仍然表现出很强的汞氧化能力。发现V_2O_5-MoO_3/TiO_2催化剂氧化单质汞遵循Mars-Maessen机理。X射线光电子能谱结果表明，三氧化钼不能直接氧化Hg 0，但高价态钼可以辅助氧化低价态钒，增加晶格氧的数量，有利于汞的氧化。此外，HCl对TV 5 M5催化剂上汞的氧化有促进作用，在6%O2/N2气氛中，随着HCl含量的增加，催化剂表面逸出的氧化汞浓度增加。
A detail process of sol–gel method was introduced to prepare V2O5–MoO3/TiO2catalyst powders containing different quantities of vanadium pentoxide and molybdenum trioxide in this study. Powder for the application in these SCR catalysts for mercury oxidation was tested in laboratory for the first time. The results indicated that titanium–vanadium–molybdenum catalysts are of higher mercury oxidation efficiency than titanium–vanadium catalysts. Especially the V2O5–MoO3/TiO2catalyst contained 5 wt% vanadium pentoxide and 5 wt% molybdenum trioxide (TV5M5), even with only the present of 6% O2, it still performed a strong mercury oxidation ability. Elemental mercury oxidized by V2O5–MoO3/TiO2catalysts was found to follow the Mars–Maessen mechanism. Molybdenum trioxide could not directly oxidize Hg0, but molybdenum in high valence could assist to oxidize vanadium in low valence to increase the number of lattice oxygen for mercury oxidation according to the X-ray photoelectron spectroscopy results. In addition, HCl exhibited a promotional effect on mercury oxidation across TV5M5, the concentration of oxidized mercury escaped from the catalyst surface increased as the content of HCl introduced into the 6% O2/N2atmosphere increasing.