N掺杂Mo/HZSM-5催化剂制备及对甲烷无氧芳构化催化性能影响

韩运达; 张新庄; 吴保强; 张浩; 黄帆; 马晓迅

doi:10.19906/j.cnki.JFCT.2021035

N掺杂Mo/HZSM-5催化剂制备及对甲烷无氧芳构化催化性能影响

doi: 10.19906/j.cnki.JFCT.2021035

西北大学化工学院，国家碳氢资源清洁利用国际合作基地，陕北能源先进化工利用技术教育部工程研究中心，陕西省洁净煤转化工程技术研究中心，陕北能源化工产业发展协同创新中心，陕西西安 710069

基金项目: 国家重点研发计划项目(2018YFB0604603)，国家自然科学基金(21536009)和陕西省重点研发计划项目(2017ZDCXL-GY-10-03,2018ZDXM-GY-167)资助

详细信息

通讯作者:
Tel: 13772424852, E-mail: maxym@nwu.edu.cn

中图分类号: TE646
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出版历程
- 收稿日期: 2020-12-02
- 修回日期: 2021-01-14
- 网络出版日期: 2021-03-30
- 刊出日期: 2021-04-10

Preparation of N-doped Mo/HZSM-5 catalyst and its effect on performance of non-oxidative methane aromatization reaction

School of Chemical Engineer, Northwest University, International Science and Technology Cooperation Base of Most for Clean Utilization of Hydrocarbon, Resources Chemical Engineering Research Center of the Ministry of Education for Advance Use, Technology of Shanbei Energy, Shaanxi Research Center of Engineering Technology for Clean Coal Coversion, Collaborative Innovation, Center for Shanbei Energy and Chemical Industry, Xi'an 710069, China

Funds: The project was supported by the National Key Research and Development Program (2018YFB0604603), the National Natural Science Foundation of China (21536009) and the Shaanxi Provincial Key Research and Development Program (2017ZDCXL-GY-10-03, 2018ZDXMGY-167)

摘要

摘要: 采用三聚氰胺作为N源，N掺杂改性HZSM-5沸石分子筛后负载Mo活性金属组分，制备了一种用于甲烷无氧芳构化反应(MDA)的催化剂。采用XPS、N₂吸附-脱附、XRD、H₂-TPR、TEM和NH₃-TPD对催化剂性质和Mo金属组分状态进行了分析表征，并考察了催化剂的甲烷无氧芳构化反应催化性能。结果表明，HZSM-5经过N掺杂改性后，会在分子筛表面生成一层含氮基团，有序调控了分子筛的酸性位点；同时会诱导Mo金属组分在催化剂表面更好的锚定落位。此方法制备的Mo/HZSM-5-CN催化剂能有效提高MDA反应的甲烷转化率和芳烃选择性，减缓了积炭的生成，展现出更优良的催化性能。
- 三聚氰胺 /
- N掺杂 /
- 甲烷无氧芳构化 /
- HZSM-5
Abstract: Catalysts for methane dehydroaromatization (MDA) were prepared using melamine as nitrogen source, doped with modified HZSM-5 zeolites and loaded with active metal component Mo. Using XPS, N₂-isothermal adsorption and desorption, XRD, H₂-TPR, TEM and NH₃-TPD, properties of the catalyst and state of active metal components were analyzed. Its catalytic performance for MDA reaction was investigated. The results showed that HZSM-5 after modified with melamine not only formed a layer of carbon and nitrogen groups on surface of the zeolites, but also controlled the medium and strong acid sites of the zeolites in orderly. At the same time it induced better anchor of Mo metal components on surface of the catalyst. The Mo/HZSM-5-CN catalyst prepared by this method could effectively increase methane conversion rate and aromatic selectivity of the MDA reaction, slow down generation of carbon deposits, and exhibit better catalytic performance.
- melamine /
- N-doped /
- non-oxidative methane aromatization /
- HZSM-5

HTML全文

FIG. 611. FIG. 611.

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图 1 催化剂MDA催化性能评价装置

Figure 1 Catalytic performance evaluation device of MDA

1: single phase valve; 2: mass flow controller; 3: four-way valve; 4: distribution board; 5: U shaped quartz tube reactor; 6: reaction heating furnace; 7: pipeline with temperature control; 8: ten way valve; 9: online chromatography

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图 2 改性前后催化剂XPS的N 1s和Mo 3d谱图

Figure 2 XPS spectra of N 1s and Mo 3d for the catalysts before and after modification

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图 3 改性前后催化剂的N₂吸附-脱附等温曲线

Figure 3 N₂-adsorption-desorption of catalysts before and after modification

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图 4 改性前后催化剂的XRD谱图

Figure 4 XRD patterns of the catalysts before and after modification

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图 5 Mo/HZSM-5和Mo/HZSM-5-CN的H₂-TPR谱图

Figure 5 H₂-TPR spectra of Mo/HZSM-5 and Mo/HZSM-5-CN

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图 6 Mo/HZSM-5和Mo/HZSM-5-CN的TEM照片

Figure 6 TEM images of Mo/HZSM-5 and Mo/HZSM-5-CN

((a1), (a2)): Mo/HZSM-5; ((b1), (b2)): Mo/HZSM-5-CN

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图 7 改性前后催化剂的NH₃-TPD谱图

Figure 7 NH₃-TPD spectra of the catalysts before and after modification

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图 8 改性前后甲烷转化率及芳烃选择性

Figure 8 Methane conversion rate and aromatics selectivity before and after modification

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图 9 反应后催化剂的积炭

Figure 9 Carbon deposit of spent catalysts

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表 1 改性前后催化剂的比表面积和孔道结构分布

Table 1 Surface area and pore structure distribution of the catalysts before and after modification

Catalyst	Surface area A/（m²·g⁻¹）			Pore volume v/（cm³·g⁻¹）
Catalyst	total	micropore	external	total	micropore
HZSM-5	367	328	39	0.198	0.139
HZSM-5-CN	318	279	38	0.180	0.118
Mo/HZSM-5	293	246	47	0.179	0.112
Mo/HZSM-5-CN	300	255	45	0.167	0.114

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表 2 改性前后催化剂的酸量分布

Table 2 Amounts of acid sites of the catalysts before and after modification

Catalyst	Weak acid/ （mmol·g⁻¹)	Medium acid/ （mmol·g⁻¹)	Strong acid/ （mmol·g⁻¹)	Total/ （mmol·g⁻¹)
HZSM-5	0.534	0.109	0.388	1.031
HZSM-5-CN	0.465	0.105	0.215	0.785
Mo/HZSM-5	0.391	0.122	0.116	0.629
Mo/HZSM-5-CN	0.362	0.192	0.147	0.701

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表 3 催化剂MDA反应中不同时间点活性与积炭

Table 3 Analysis of catalyst activity and carbon deposition in MDA reaction

Catalyst	Time/ min	Conversion/ %	Selectivity/ %	Carbon depostion/ %
Mo/HZSM-5	20	18.65	69.54	12.8
	40	13.54	63.88
	60	9.79	56.81
	80	7.63	41.60
Mo/HZSM-5-CN	20	21.67	81.75	10.9
	40	18.03	82.10
	60	15.10	77.50
	80	10.63	50.64

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