Fe-Mn基分子筛催化剂NH_3低温选择性催化还原NO性能

Catalytic performance of low-temperature selective catalytic reduction of NO by NH_3 over Fe-Mn-based zeolite catalysts

采用柠檬酸法制备了不同Fe和Mn含量的Fe-Mn/HBeta催化剂,采用BET、XRD、SEM和XPS等方法对不同催化剂的特征参数进行表征,以氨气为还原剂,在空速为5 000 h^(-1)的条件下,考察了活性成分负载量和焙烧温度对其活性的影响;探讨了催化剂的抗水抗硫性能。研究结果表明,焙烧温度为550℃、6%Fe-6%Mn/HBeta催化剂具有相对较优的催化活性,反应温度为90~230℃时,NO转化率为63.9%~96.99%,比表面积、孔体积和平均孔径分别为356.19 m^2/g、0.61cm^3/g和16.83 nm,活性成分在催化剂表面高度分散,催化剂表面Mn主要以Mn^(3+)和Mn^(4+)存在,且以Mn^(4+)居多;反应温度为180℃条件下,6%Fe-6%Mn/HBeta催化剂具有较好的抗水能力和同时抗水抗SO_2能力,但单独抗SO_2能力较差。

Fe-Mn/HBeta catalysts with different Fe and Mn contents were synthesized from citric acid,which were characterized by BET,XRD,SEM and XPS methods. The reaction activity of the catalysts were adjusted by changing the preparing condition,which including the calcination temperature and loading amount of active components with ammonia as reductant under the condition of space velocity of 5 000 h^-1. Further study on water-resistance and anti-sulfur ability of the catalysts were discussed. The experiment results show that the loading amount of active components of 6% Fe-6% Mn/HBeta was optimum at calcination temperature of 550℃.The catalytic conversion of nitrogen monoxide by the selected catalyst was between 63. 9% —97. 0% at reduction reaction temperatures of 90—230℃. The active components dominated by Mn^3 ＋ and Mn^4 ＋ state were uniformly distributed on the surface of the catalyst with specific surface area,pore volume and mean pore size of 356. 19m^2/g,0. 61 cm^3/g and 16. 83 nm,respectively. The selected catalyst has good synchronous ability of resistance to water and sulfur dioxide while separate resistance to sulfur dioxide was poor.