新型铁锰复合氧化物催化低温脱除NO_x(英文)

Removal of NO_x Using Novel Fe-Mn Mixed-Oxide Catalysts at Low Temperature

采用溶胶-凝胶法合成了一系列铁锰复合氧化物催化剂,利用X射线衍射(XRD)对催化剂的活性相态进行研究,并考察了铁锰摩尔比及焙烧温度对催化性能的影响.结果表明,该催化剂体系在低温(80-220℃)下选择性催化氨还原NOx反应中显示出优异的活性.其中Fe(0.4)-MnOx(500)(即摩尔比n(Fe)/(n(Fe)+n(Mn))=0.4,焙烧温度500℃)催化剂具有最佳低温催化活性,在空速30000h-1,温度80℃的条件下,NOx转化效率达到90.6%,N2选择性达100%.Fe-MnOx复合氧化物催化剂中形成的Fe3Mn3O8晶相有利于促进NO氧化成NO2,从而提高低温选择性催化还原的活性.

A series of novel Fe-Mn mixed-oxide catalysts were prepared by a sol-gel method. X-ray diffraction （XRD） was used to characterize the active phase and the effects of the n（Fe）/（n（Fe）＋n（Mn） molar ratio as well as the calcination temperature on the catalytic properties were investigated. This catalytic system had good selective catalytic reduction （SCR） properties for NOx by ammonia at low temperatures （80-220 ℃）. We achieved 90.6% conversion of NOx with 100% selectivity of N2 on an Fe（0.4）-MnOx mixed oxide （the molar ratio of n（Fe）/（n（Fe）＋n（Mn））=0.4 and calcined at 500 ℃） at 80 ℃ with a space velocity of 30000 h -1. XRD characterization results showed that a new Fe3Mn3O8 phase was generated for Fe-MnOx. The oxidation activity of NO to NO2 by O2 on these Fe-MnOx catalysts suggested that the existence of Fe3Mn3O8 was beneficial for an increased oxidation rate of NO to NO2,which improved the activity of low-temperature SCR.