中试规模下蜂窝式Mn-Ce/Al2O3脱硝催化剂的低温性能

采用自行设计的反应装置，研究中试规模条件下关键参数对蜂窝堇青石Mn-Ce/Al2O3催化剂脱硝效率的影响以及抗硫抗水性能，并通过扫描电子显微镜（SEM）、能谱仪（EDS）、X射线衍射（XRD）和比表面积测试仪（BET）研究催化剂的理化性质。结果表明，反应温度、空速、氨氮比对催化活性均有明显影响，同时，催化剂对氮氧化物浓度有较强适应性，NO浓度在134~469 mg·m-3区间内脱硝效率均可保持在75%以上。催化剂在100 oC，空速3 336 h-1，NH3]/NO]为0.9，烟气量20 m3·h-1条件下连续反应168 h，其催化效率可以稳定保持在75%~80%，说明蜂窝式Mn-Ce/Al2O3具有良好的稳定性。催化剂在含5%H2O气氛中催化效率由80%减少至60%，在去除H2O后抑制作用消失。反应气中通入143 mg·m-3 SO2后催化效率由80%降低至62%，停止通入SO2后活性不能恢复。同时通入143 mg·m-3 SO2和5%H2O，催化效率下降并维持在53%左右，停止通入后活性恢复至67%。通过对SO2中毒前后的催化剂表征分析可得，SO2存在条件下生成的硫酸铵盐堵塞了20 nm孔径以下的部分孔道，覆盖了催化剂表面活性位点，是引起效率下降的主要原因。

Low temperature performance of honeycomb Mn-Ce/Al2O3 denitration catalyst in the pilot-scale

A self-designed pilot scale reaction device was used to study the influence of key parameters on the denitration efficiency of honeycomb Mn-Ce/Al2O3 catalyst and the performance of SO2 and H2O resistance. Furthermore, the experiments of SEM, EDS, XRD, BET were carried out respectively in order to obtain physicochemical properties of the prepared catalysts. The result showed that reaction temperature, space velocity and mole ratio of NH3/NO have a significant impact on the catalysts’ performance. Meanwhile, the catalysts adapted well to the change of the concentration of NOx. The NOx conversion stayed above 75% in the range from 134 to 469 mg·m-3 of the NOx concentration. When the reaction temperature was 100 °C, space velocity was 3 336 h-1, NH3 to NOx ratio was 0.9 and the total flow rate was maintained at 20 m3·h-1, the catalytic efficiency can be steady at 75%~80% after 168 hours reaction. After introduction of 143 mg·m-3 SO2 into the reactants, NO conversion ratio decreased to 62% and activity cannot be completely recovered after SO2 is shut off. The NO conversion ratio of Mn-Ce/Al2O3 declined quickly to 60% when being introduced 5% H2O into the simulated gas. Then, the NO conversion ratio could raise quickly as soon as H2O was closed. After in the presence of 143 mg·m-3 SO2 and 5% H2O together, NO conversion was maintained at 53%. The activity of the deactivated catalyst could recover to 67% after removing H2O and SO2. It is mainly because the presence of SO2 result in formed ammonium sulfate on the catalyst surface which covers the active site and blocks the pore size of below 20 nm.