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 TiO_2 nanotubes

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23 613.8 h-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。

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 resultsof 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.Theeffects 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 23 613.8 h-1 and Mn loading of5% ～ 15%（mass ratio）,NO conversion exceeds 95%.The catalyst is deactivated in the presence of H2O at180 ℃,but its activity can be recovered almost completely when cutting off H2O;higher resistance to H2O isobserved 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 ofMnOx /TiNT catalyst deactivated by SO2 rises gradually after cutting off H2O ＋ SO2,but cannot be recovered to its initial level.