双金属Ce-Mn/ZSM-5催化剂的制备及NH3-SCR脱硝性能研究

Study on the preparation and catalytic performance of bimetallic Ce-Mn/ZSM-5 catalyst for selective catalytic reduction of nitric oxide by NH3

    摘要
  • 摘要: 采用浸渍法制备了铈锰复合氧化物分子筛催化剂（Ce-Mn/ZSM-5），在固定床反应器上考察不同Ce/Mn质量比对分子筛催化剂选择催化还原NO的影响，利用XRD、TEM、NH3-TPD、H2-TPR、in-situ DRIFTS等手段对催化剂进行了表征分析。结果表明，双金属改性的Ce-Mn/ZSM-5催化剂在NH3-SCR反应中表现出较为优异的催化活性，具有较宽的活性温度窗口。当Ce/Mn质量比为0.4时，催化剂具有最佳的脱硝效率，在265-465℃脱硝率均可达到80%以上，在370℃时，NO的转化率最高可达97.28%。锰和铈物种高度分散于催化剂表面，未改变ZSM-5的晶体结构，且构成协同作用。0.4Ce-Mn/ZSM-5具备丰富的酸性位、良好的氧化还原性能，该配比有助于催化剂的催化活性和稳定性的提高，在NH3-SCR反应过程同时遵循E-R机理和L-H机理。

     

    Abstract: A series of Ce-Mn/ZSM-5 catalyst with different mass ratios of Ce and Mn was prepared by impregnation method, and the influence of Ce loading on denitrification performance was investigated in a fixed-bed reactor. XRD, TEM, NH3-TPD, H2-TPR, in-situ DRIFTS were used to characterize the catalysts. The results show that the bimetallic Ce-Mn/ZSM-5 have a broad active temperature window. Especially, the catalyst with Ce/Mn mass ratio of 0.4 has the best denitrification efficiency, and the denitrification rate can be higher than 80% between 266 and 465℃, and up to 97.28% at 370℃.Manganese and cerium species can be well dispersed on the surface of the support without changing the crystal structure of ZSM-5.0.4Ce-Mn/ZSM-5 catalyst has abundant acidic sites, good redox performance. There are both E-R mechanism and L-H mechanism in NH3-SCR reaction.

     

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