Ce金属改性对Cu-SAPO-34催化剂水热稳定性能的影响

毛静雯; 徐斌; 胡宜康; 张昌远; 孟慧敏

Ce金属改性对Cu-SAPO-34催化剂水热稳定性能的影响

毛静雯¹,
徐斌^{1, 2, ,},
胡宜康¹,
张昌远¹,
孟慧敏¹

1.
河南科技大学车辆与交通工程学院, 河南洛阳 471003
2.
河南省能源动力装置节能与污染物控制国际联合实验室, 河南洛阳 471003

基金项目:

国家重点研发计划"新型节能环保农用发动机开发" 2106YFD0700700

详细信息

中图分类号: TK429;X701
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- 文章访问数: 202
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- 被引次数: 0
出版历程
- 收稿日期: 2020-09-07
- 修回日期: 2020-09-21
- 网络出版日期: 2021-01-23
- 刊出日期: 2020-10-10

Effect of Ce metal modification on the hydrothermal stability of Cu-SAPO-34 catalyst

1.
School of Vehicle and Transportation Engineering, Henan University of Science and Technology, Luoyang 471003, China
2.
Henan International Joint Laboratory for Energy Saving and Pollutant Control of Energy Power Plants, Luoyang 471003, China

Funds:

National Key Research and Development Program "Development of New Energy-saving and Environmentally Friendly Agricultural Engines 2106YFD0700700

More Information

Corresponding author: XU Bin,Tel:13938823801, E-mail:xu64327@163.com

摘要

摘要: 采用浸渍法制备系列铜铈复合氧化物分子筛催化剂（Cu-Ce/SAPO-34），探讨了Ce负载量对Cu/SAPO-34催化剂的水热稳定性的影响，通过XRD、SEM、H₂-TPR、XPS和NH₃-TPD等表征手段分析不同催化剂活性和稳定性差异的原因。研究表明，750℃水热老化未造成Cu-Ce/SAPO-34催化剂菱沸石（chabazite，CHA）骨架坍塌，但破坏了部分孔结构和酸性位点，使催化剂表面结晶度下降。水热老化促使催化剂晶格发生拉伸畸变，使Cu²⁺迁移到催化剂表面，Cu²⁺和Ce⁴⁺团簇形成CuO和CeO₂，造成催化剂的Cu活性物种减少和氧空穴浓度降低，所以Cu-Ce/SAPO-34的NH₃选择性催化还原（NH₃-Selective Catalytic Reduction，NH₃-SCR）性能下降。掺杂Ce能提高Cu/SAPO-34催化剂表面的Cu²⁺和Cu⁺活性物种量，减少Cu物种团簇形成CuO，改善催化剂表面活性Cu物种分布性。提高Ce的负载量能稳固Cu-Ce/SAPO-34催化剂的结构，使中、弱强度酸位点得以维持，从而提高其水热稳定性。结果表明，在研究的系列Cu-Ce/SAPO-34催化剂中，Cu/Ce质量比为4：5时具有最佳的水热稳定性。
- 催化剂 /
- 分子筛 /
- 团聚 /
- 脱附 /
- 活性 /
- 选择催化还原
Abstract: A series of copper-cerium composite oxide molecular sieve catalysts (Cu-Ce/SAPO-34) were prepared by impregnation method, and the effects of Ce loading on the hydrothermal stability of Cu/SAPO-34 catalyst were discussed. The reasons for the difference in activity and stability of different catalysts were analyzed by XRD, SEM, H₂-TPR, XPS, and NH₃-TPD. The present study showed that hydrothermal aging at 750 ℃ did not cause the chabazite (CHA) framework of Cu-Ce/SAPO-34 catalyst to collapse, but destroyed part of the pore structure and acid sites, and reduced the crystallinity of the catalyst surface. Hydrothermal aging promoted tensile distortion of the catalyst lattice, causing Cu²⁺ to migrate to the catalyst surface, and Cu²⁺ and Ce⁴⁺ clustered to form CuO and CeO₂, which resulted in the reduction of the Cu active species and the decrease of the oxygen hole concentration of the catalyst. Therefore, the performance of Cu-Ce/SAPO-34 for the selective catalytic reduction of NO_x by NH₃ (NH₃-SCR) decreased. Ce doping could increase the amount of Cu²⁺ and Cu⁺ active species on the surface of Cu/SAPO-34 catalyst, reduce Cu species clusters to form CuO, and improve the distribution of active Cu species on the catalyst surface. Increasing the loading of Ce could stabilize the structure of Cu-Ce/SAPO-34 catalyst and maintain the medium and weak acid sites, thereby improving its hydrothermal stability. The results indicated that the Cu/Ce mass ratio of 4:5 had the best hydrothermal stability among the series of Cu-Ce/SAPO-34 catalysts in this study.
- catalyst /
- molecular sieves /
- agglomeration /
- desorption /
- reactivity /
- SCR

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图 1 Cu-Ce/SAPO-34催化剂的NO_x转化率

Figure 1 NO_x conversion rate of Cu-Ce/SAPO-34 catalysts

(a): fresh catalysts; (b): after 750 ℃ hydrothermal aging

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图 2 Cu-Ce/SAPO-34催化剂XRD谱图

Figure 2 XRD patterns of Cu-Ce/SAPO-34 catalyst

a: 4%Cu/SAPO-34; b: 4%Cu/SAPO-34-750 ℃; c: Cu:Ce(4:1)/SAPO-34-750 ℃; d: Cu:Ce(4:3)/SAPO-34-750 ℃; e: Cu:Ce(4:5)/SAPO-34-750 ℃

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图 3 Cu-Ce/SAPO-34催化剂的SEM照片

Figure 3 SEM images of Cu-Ce/SAPO-34 catalyst

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图 4 Cu-Ce/SAPO-34催化剂的H₂-TPR谱图

Figure 4 H₂-TPR profiles of Cu-Ce/SAPO-34 catalyst

a: 4%Cu/SAPO-34; b: 4%Cu/SAPO-34-750 ℃; c: Cu:Ce(4:1)/SAPO-34-750 ℃; d: Cu:Ce(4:3)/SAPO-34-750 ℃; e: Cu:Ce(4:5)/SAPO-34-750 ℃

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图 5 Cu/SAPO-34和Cu-Ce/SAPO-34催化剂的XPS谱图

Figure 5 XPS spectra of Cu/SAPO-34 and Cu-Ce/SAPO-34 catalysts

a: 4%Cu/SAPO-34; b: Cu:Ce(4:5)/SAPO-34

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图 6 750 ℃水热老化前后Cu:Ce(4:5)/SAPO-34催化剂的XPS谱图

Figure 6 XPS spectra of Cu:Ce(4:5)/SAPO-34 catalyst before and after 750℃ hydrothermal aging

a: Cu:Ce(4:5)/SAPO-34-750 ℃; b: Cu:Ce(4:5)/SAPO-34

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图 7 Cu-Ce/SAPO-34的NH₃-TPD谱图

Figure 7 NH₃-TPD profiles of Cu-Ce/SAPO-34

a: 4%Cu/SAPO-34; b: 4%Cu/SAPO-34-750 ℃; c: Cu:Ce(4:1)/SAPO-34-750 ℃; d: Cu:Ce(4:3)/SAPO-34-750 ℃; e: Cu:Ce(4:5)/SAPO-34-750 ℃

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表 1 Cu-Ce/SAPO-34和Cu/SAPO-34催化剂表面元素的含量

Table 1 Content of surface elements of Cu-Ce/SAPO-34 and Cu/SAPO-34 catalysts

Catalyst	Atomic content w/%					Relative content w/%
Catalyst	Cu	Ce	Si	Al	P	Cu²⁺	Cu⁺	Ce³⁺	Ce⁴⁺
4%Cu/SAPO-34	1.69	0.00	14.36	26.88	14.69	23.96	76.04	-	-
Cu:Ce(4:5)/SAPO-34	2.45	3.29	7.77	27.93	16.05	24.17	75.83	43.88	56.12
Cu:Ce(4:5)/SAPO-34-750 ℃	2.87	4.53	5.71	29.47	15.68	37.64	62.36	65.58	34.42

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