Ce掺杂对Mn/ACN催化剂低温NH3-SCR脱硝活性的影响

中文摘要: 采用浸渍法将活性组分Mn、Ce负载到酸处理后的椰壳活性炭(ACN)上，制备出Mn/CAN和Mn-Ce/ACN脱硝催化剂，在固定床上对所制备的催化剂进行了脱硝性能评价，着重探讨了2种活性组分的负载顺序、负载量对催化剂活性的影响，并对催化剂进行了BET、SEM、XRD、XPS表征。结果表明，通过比较Mn/CAN和Mn-Ce/ACN催化剂的脱硝活性，发现Ce的添加能明显提高催化剂的脱硝活性，在温度高于90 ℃时能达到90%以上的NO去除率，在120~250 ℃之间，NO转化率维持在100%。活性组分的负载顺序及负载量是影响催化剂活性的重要因素。同时负载活性组分，Ce、Mn负载量均为5%时，催化剂表现出最好的脱硝性能。Mn负载在活性炭上，降低了活性炭的比表面积和孔容，而Mn、Ce负载量均为5%的Mn-Ce/ACN的比表面积和微孔孔容降到695.0 m 2/g和0.130 cm 3/g，随着Mn、Ce负载量的增加，比表面积和孔容进一步降低；当Ce、Mn负载量均增加到10%时，其比表面积和微孔孔容只有539.8 m 2/g和0.106 cm 3/g。Mn 3+和Mn 4+共存于2种催化剂上，而Ce 4+和Ce 3+共存并使Mn-Ce/CAN上Mn 4+比例略微增加，导致催化剂表现出最好的脱硝性能。
Abstract:Mn and Ce were loaded on the coconut-hell-based activated carbon treated by nitric acid (ACN) using impregnation method for low temperature selective catalytic reduction (SCR) of NO with NH 3.The catalytic activity was evaluated at a fixed-bed,and,the loading order and loading amount of Ce and Mn were studied.The Catalysts were characterized by BET,SEM,XRD and XPS.The results showed that the Ce adding to Mn/ACN improves significantly the denitration activity of catalyst;when temperature is higher than 90 ℃,when the removal rate of NO achieves 90% and maintains 100% at 120~250 ℃.The loading sequence and amount of active component are important factors for influencing catalyst activity.When 5% Ce and 5% Mn were simultaneously loaded on ACN,the catalyst exhibits the best denitration performance.Mn loading on activated carbon can reduce the specific surface area and pore volume of active carbon,and the specific surface area and micro pore volume of Mn-Ce/ACN with 5% Mn and 5% Ce decrease to 695.0 2/g and 0.130 cm 3/g;with the increase of loading,specific surface area and pore volume further decrease;Mn loading with 10% Ce increases to 10%,the specific surface area and micro-pore volume have only 539.8 m 2/g and 0.106 cm 3/g.Mn 3+and Mn 4+coexist in Mn/ACN and Mn-Ce/ACN.Ce 4+and Ce 3+coexist in Mn-Ce/ACN and improve the slight increase of Mn 4+content,leading to the best denitration activities.