Influence of CeO2 contents on the SCR performance of commercial rare earth catalysts

doi:10.16085/j.issn.1000-6613.2019-1584

Abstract

Abstract:

The effect of CeO₂ contents on the NH₃-SCR performance of commercial rare earth catalysts in diesel was investigated. By using XRD, N₂ adsorption-desorption, XPS, H₂-TPR and NH₃-TPD analysis, we found that the addition of CeO₂ had no effect on the crystal structure of the catalysts, but it promoted the dispersion of SiO₂ on the surface of the rare earth catalysts, which affected the SCR performance and hydrothermal stability of the catalysts. The content of CeO₂ affected the texture properties of the catalysts, and larger pore volume and appropriate specific surface were beneficial for the improvement of the hydrothermal aging performance of the catalysts. The content of Ce on the surface firstly decreased and then increased when the CeO₂ content increased from 14% to 20%, and the amount of Ce⁴⁺ was positively correlated with the hydrothermal aging performance of the catalysts. Moreover, the redox ability and the number of acid sites decreased with the increase of CeO₂ content because it could hinder the reduction of other components or increase the thermal stability of the rare earth catalysts. According to the results of catalytic activity tests for NH₃-SCR, the optimum content of CeO₂ in the rare earth catalysts was 16%.

Key words: cerium oxide, catalyst, NH₃-SCR, hydrothermal aging, catalysis

摘要：

考察了不同CeO₂含量对柴油机商用稀土选择性催化还原（SCR）催化剂NH₃-SCR性能的影响。通过X射线衍射、N₂吸附-脱附、X射线光电子能谱、H₂-程序升温还原和NH₃-程序升温脱附等表征手段对催化剂的结构及性能进行了研究。研究发现，CeO₂含量对催化剂的晶体结构没有影响，添加后促进了稀土催化剂表面SiO₂的分散，从而对催化剂的脱硝性能及水热老化性能产生影响；CeO₂含量影响催化剂的织构性质，较大的孔体积和适当的比表面有利于催化剂水热老化后催化剂的脱硝性能的提高；随着CeO₂含量从14%增加到20%，其表面Ce含量呈先降低后升高的趋势，其中Ce⁴⁺含量与催化剂的水热老化后催化剂的脱硝性能成正相关；CeO₂含量的增加会阻碍稀土催化剂中其他组分的还原或增加其热稳定性，从而影响催化剂的还原能力和酸性位数量；通过脱硝性能测试，稀土催化剂中CeO₂的最佳含量为16%。

关键词: 氧化铈, 催化剂, 氨选择性催化还原, 水热老化, 催化作用

CLC Number:

O643.36

Yan WANG, Zhaoqiang LI, Cheng ZHANG, Yu WANG, Rongrong FAN, Zhiyong DING, Xin GUO, Rong WANG. Influence of CeO₂ contents on the SCR performance of commercial rare earth catalysts[J]. Chemical Industry and Engineering Progress, 2020, 39(7): 2662-2669.

王艳, 李兆强, 张丞, 王雨, 樊蓉蓉, 丁智勇, 郭欣, 王荣. CeO₂含量对柴油机商用稀土SCR催化剂脱硝性能的影响[J]. 化工进展, 2020, 39(7): 2662-2669.

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Influence of CeO₂ contents on the SCR performance of commercial rare earth catalysts

CeO₂含量对柴油机商用稀土SCR催化剂脱硝性能的影响

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