钛纳米管负载锰催化剂的低温选择性催化还原脱硝性能

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MnO_x/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MnO_x/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。

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

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 (MnO_x/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 MnO_x/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 MnO_x/TiNT catalyst deactivated by SO₂ rises gradually after cutting off H₂O + SO₂, but cannot be recovered to its initial level.