钛纳米管负载锰催化剂的低温选择性催化还原脱硝性能

Low temperature selective catalytic reduction of NO over manganese supported on TiO2 nanotubes

  • 摘要: 采用水热法合成了钛纳米管(TiNT),以400℃焙烧后得到的TiO2纳米管为载体,采用浸渍法制备了MnOx/TiNT催化剂,用于低温NH3选择性催化还原脱NO反应(SCR)。BET、TEM、XRD及TG测试表明,经过400℃焙烧之后的钛纳米管主要成分为锐钛矿型TiO2,所制备的催化剂活性组分分散性较好。在模拟烟气条件下,考察了锰负载量、空速、O2含量、氨氮比及进口NO浓度对MnOx/TiNT的SCR催化性能的影响。在150℃、\NH3\/\NO\比为1.2、O2浓度为3%、NO浓度为0.06%、空速GHSV为23613.8h-1、Mn的负载量为5%~15%的条件下,NO的转化率达到95%以上。反应气氛中单独通入水会造成催化剂的活性下降;切断H2O,催化剂的活性可以恢复至初始水平。温度越高,催化剂抗水性能越好,而且水存在情况下的抗硫性能优于其单独抗硫性能。再次切断H2O和SO2,催化剂的活性逐渐上升,但不能恢复到初始水平。

     

    Abstract: Titanate nanotubes were synthesized hydrothermally with commercial TiO2 nanoparticles in NaOH; after calcination at 400℃, TiO2 nanotubes were obtained and used as the support to prepare manganese catalyst (MnOx/TiNT) by wet-impregnation for low temperature selective catalytic reduction of NO (SCR). The results of BET, TEM, XRD and TG measurements showed that TiO2 nanotubes exhibit well-defined TiO2 anatase phase after calcination at 400℃ and manganese particles are highly dispersed on the wall of TiO2 nanotubes. The effects of active component loading, space velocity, oxygen content, \NH3\/\NO\ ratio and NO concentration on the SCR performance of MnOx/TiNT were investigated in a simulated flue gas. Under the reaction conditions of 150℃, \NH3\/\NO\ of 1.2, \O2\ of 3%, \NO\ of 0.06%, GHSV of 23613.8h-1 and Mn loading of 5%~15%(mass ratio), NO conversion exceeds 95%. The catalyst is deactivated in the presence of H2O at 180℃, but its activity can be recovered almost completely when cutting off H2O; higher resistance to H2O is observed at higher temperature. The presence of SO2 can also deactivate the catalyst gradually; however, the catalyst exhibits better resistance toward SO2 in the presence of H2O than that without H2O. The SCR activity of MnOx/TiNT catalyst deactivated by SO2 rises gradually after cutting off H2O + SO2, but cannot be recovered to its initial level.

     

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