负载型CuMn2O4催化剂同时去除甲苯与NOx性能及机理研究

刘旭; 黄妍; 赵令葵; 李思密; 陶泓帆; 饶思敏; 朱洪

doi:10.19906/j.cnki.JFCT.2023024

负载型CuMn₂O₄催化剂同时去除甲苯与NO_x性能及机理研究

doi: 10.19906/j.cnki.JFCT.2023024

湘潭大学环境与资源学院, 湖南湘潭411105

基金项目: 湖南省教育厅科研项目（22A0129）和国家自然科学基金（52270107）资助

详细信息

通讯作者:
E-mail: xtuhy@163.com

中图分类号: X701
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出版历程
- 收稿日期: 2023-03-08
- 修回日期: 2023-03-22
- 录用日期: 2023-03-24
- 网络出版日期: 2023-04-06

Study on performance and mechanism of CuMn₂O₄/MO₂ supported catalyst for simultaneous removal of toluene and NO_x

College of Environment and Resources, Xiangtan University, Xiangtan 411105, China

Funds: The project was supported by Hunan Provincial Department of Education funded research projects (22A0129), Supported by the National Natural Science Foundation of China (52270107)

摘要

摘要: 本研究使用低温溶胶凝胶自燃法制备了不同载体负载的CuMn₂O₄/MO₂(M=Mn、Ti、Ce)催化剂，并对其同时去除甲苯和NO_x的性能进行了评价。结果表明，CeO₂载体的加入可显著缓解CuMn₂O₄上甲苯氧化与NH₃-SCR的相互抑制，因此，CuMn₂O₄/CeO₂催化剂表现出最优异的甲苯与NO_x同时去除效率。通过BET、XRD、NH₃-TPD、O₂-TPD及结合XPS与in-situ DRIFTs对催化剂的物化性质及CuMn₂O₄同时去除甲苯与NO_x的反应机理进行了分析。结果表明，CeO₂的引入提高了催化剂中Mn^{4 +}/Mn^{n +}的占比，促使CuMn₂O₄/CeO₂催化剂形成表面丰富的酸性位点和氧空位。此外，Cu、Mn和Ce之间的强相互作用加速电子转移，增强了Cu⁺ + Ce^{4 +} ↔Cu^{2 +} + Ce^{3 +}、Mn^{4 +} + Ce^{3 +} ↔Mn^{3 +} + Ce^{4 +}的氧化还原循环。In-situ DRIFTs证实了CuMn₂O₄催化剂上NH₃-SCR反应遵循Langmuir-Hinshelwood机制，甲苯的氧化遵循Mars-van Krevelen机制。因此，CeO₂作为载体的CuMn₂O₄/CeO₂催化剂优异的氧化还原能力促使甲苯的完全氧化，表现出优异的甲苯与NO_x同时去除能力。本工作可为同时消除甲苯和NO_x的催化剂开发提供指导。
- 负载型催化剂 /
- 催化氧化 /
- NH₃-SCR /
- NO /
- 甲苯
Abstract: In this study, CuMn₂O₄/MO₂(M=Mn, Ti, Ce) catalysts with different support loads were prepared by sol-gel spontaneous combustion at low temperature, and the removal performance of toluene and NO_x was evaluated. The results showed that the addition of CeO₂ carrier could significantly alleviate the mutual inhibition of toluene oxidation and NH₃-SCR over CuMn₂O₄. Therefore, CuMn₂O₄/CeO₂ catalyst showed the best removal efficiency of toluene and NO_x simultaneously. The physicochemical properties of the catalyst and the reaction mechanism of CuMn₂O₄ were analyzed by BET, XRD, NH₃-TPD, O₂-TPD and combined XPS and in-situ DRIFTs. The results showed that the introduction of CeO₂ increased the proportion of Mn^{4 +}/Mn^{n +} in the catalyst, and promoted the formation of rich acid sites and oxygen vacancies on the surface of CuMn₂O₄/CeO₂ catalyst. In addition, the strong interaction between Cu, Mn and Ce accelerated electron transfer and enhance the redox cycle for Cu⁺ + Ce^{4 +} ↔Cu^{2 +} + Ce^{3 +}、Mn^{4 +} + Ce^{3 +} ↔Mn^{3 +} + Ce^{4 +}. It has been confirmed by in-situ DRIFTs that NH₃-SCR reaction on CuMn₂O₄ catalyst follows Langmuir-Hinshelwood mechanism and oxidation of toluene follows Mars-van Krevelen mechanism. Therefore, CuMn₂O₄/CeO₂ catalyst with CeO₂ as the support has excellent reoxidation ability to promote the complete oxidation of toluene, so it shows excellent removal ability of toluene and NO_x simultaneously. This work can provide guidance for the development of catalysts for simultaneous removal of toluene and NO_x.
- supported catalyst /
- catalytic oxidation /
- NH₃-SCR /
- NO /
- toluene

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图 1 实验装置示意图

Figure 1 Schematic diagram of experimental apparatus

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图 2 CuMn₂O₄/MO₂（M=Mn、Ce、Ti）催化剂NH₃-SCR还原NO（a）, 单独氧化甲苯（b）

Figure 2 CuMn₂O₄/MO₂ (M=Mn, Ce, Ti) catalyst NH₃-SCR reduction of NO (a), alone oxidized toluene (b)

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图 3 CuMn₂O₄/MO₂（M=Mn、Ce、Ti）催化剂协同处理NO（a）, 协同处理甲苯（b）

Figure 3 CuMn₂O₄/MO₂ (M=Mn, Ce, Ti) catalyst synergistic treatment of NO (a), synergistic treatment of toluene (b)

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图 4 CuMn₂O₄/CeO₂的稳定性测试

Figure 4 Stability test of CuMn₂O₄/CeO₂

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图 5 催化剂吸附等温线

Figure 5 Catalyst adsorption isotherms

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图 6 负载前后尖晶石的XRD谱图

Figure 6 Spinel XRD before and after loading

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图 7 不同载体负载尖晶石催化剂的NH₃-TPD谱图

Figure 7 NH₃-TPD spectra of spinel catalysts supported by different carriers

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图 8 不同载体负载尖晶石催化剂的O₂-TPD谱图

Figure 8 O₂-TPD spectra of spinel catalysts supported by different carriers

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图 9 不同载体催化剂的XPS谱图

Figure 9 XPS spectra of different supported catalysts

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图 10 CuMn₂O₄在300 ℃吸附时间原位光谱研究

Figure 10 In-situ spectroscopic study of CuMn₂O₄ adsorption time at 300 ℃ (a): Adsorption of toluene and NO after toluene adsorption; (b): Toluene is oxidized into toluene; (c): Toluene is oxidized into NH₃-SCR

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图 11 甲苯与NO的同时去除示意图

Figure 11 Diagram of simultaneous removal of toluene and NO

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表 1 催化剂的比表面积以及孔容孔径

Table 1 Catalyst specific surface area

Specie	Surface area /（m²·g⁻¹）	Pore volume /（cm³·g⁻¹）	Mean pore size /nm
CuMn₂O₄	1.61	0.00249	5.99
CuMn₂O₄/MnO₂	18.52	0.04165	7.89
CuMn₂O₄/TiO₂	19.24	0.04759	8.32
CuMn₂O₄/CeO₂	23.76	0.05247	8.84

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表 2 催化剂的XPS表面元素比值

Table 2 XPS of surface element ratio

Species	O Atomic/%			Binding energy/eV		Cu⁺/Cu^{2 +}	Mn^{4 +}/Mn^{3 +}	Atomic /%
Species	O_ads	O_latt	O_ads/O_lat	O_ads	O_lat			Cu	Mn	O	M
CuMn₂O₄	52.54	47.46	1.10	531.7	530.1	0.57	0.47	7.16	26.29	66.55
CuMn₂O₄/MnO₂	47.85	52.15	0.91	531.8	530.4	0.82	0.50	6.01	26.81	67.17
CuMn₂O₄/TiO₂	42.20	57.80	0.73	532.4	530.9	0.22	0.22	6.56	23.06	65.24	5.14
CuMn₂O₄/CeO₂	35.11	64.89	0.54	531.0	529.6	0.28	0.78	5.51	23.66	65.75	5.08

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