晶种存在形态对所合成的SAPO-34分子筛性质及其甲醇转化催化性能的影响

张强; 马晓月; 刘璐

晶种存在形态对所合成的SAPO-34分子筛性质及其甲醇转化催化性能的影响

张强^1, ,,
马晓月²,
刘璐¹

1.
中国石油大学(华东) 重质油国家重点实验室, 山东青岛 266580
2.
东营市海科新源化工有限责任公司, 山东东营 257000

基金项目:

国家自然科学基金 21406270

详细信息

中图分类号: TQ426.61
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- 文章访问数: 163
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- 被引次数: 0
出版历程
- 收稿日期: 2018-04-17
- 修回日期: 2018-07-07
- 网络出版日期: 2021-01-23
- 刊出日期: 2018-10-10

Effect of seed form on the structure and properties of as-synthesized SAPO-34 molecular sieves and their catalytic performance in the conversion of methanol to olefins

1.
State Key Laboratory of Heavy Oil Processing, China University of Petroleum(East China), Qingdao 266580, China
2.
Dongying Haike Spring Chemical Limited Liability Company, Dongying 257000, China

Funds:

the National Natural Science Foundation of China 21406270

More Information

Corresponding author: ZHANG Qiang, E-mail:xyz@upc.edu.cn

摘要

摘要: 采用常规水热合成法、添加粉末晶种和添加含有分子筛前驱体的液相晶种等方法制备了低硅铝比的SAPO-34分子筛。采用XRD、SEM、FT-IR及TPD等表征手段研究了合成方法对晶体结构、形貌、晶粒粒径及酸性的影响。并在固定床上对比了其甲醇转化制烯烃的催化性能差异。结果表明，晶种存在形态对分子筛的结晶度影响不大，但影响了硅在骨架中的分布、晶粒粒径和酸性等。与添加粉末晶种相比，采用含有分子筛前驱体的液相晶种法更有利于减小分子筛晶粒粒径，降低分子筛酸性，提高低碳烯烃选择性。
- 低硅铝比 /
- SAPO-34 /
- 分子筛 /
- 甲醇制烯烃 /
- 固态晶种法 /
- 液态晶种法
Abstract: A series of SAPO-34 molecular sieves with low Si/Al ratio were synthesized by conventional hydrothermal method as well as adding powder crystal seed and liquid crystal seed containing SAPO-34 precursor. These SAPO-34 molecular sieves were characterized by XRD, SEM, FT-IR and NH₃-TPD and the effects of synthesis method on the structure, morphology, crystal size and acidity of the resultant SAPO-34 molecular sieves as well as their catalytic performance in the conversion of methanol to olefins (MTO) were investigated. The results indicate that although the seed form has little influence on the crystallinity, the silicon distribution in SAPO-34 framework, crystal size, and acidic properties are strongly related to the seed form. In comparison with the SAPO-34 sample synthesized with powder form seed, the SAPO-34 molecular sieves prepared using liquid crystal seed containing SAPO-34 precursor exhibit smaller crystal size, weaker acidic strength, and higher selectivity to light olefins in MTO.
- low silicon/aluminium ratio /
- SAPO-34 /
- molecular sieves /
- methanol-to-olefin /
- solid seed method /
- liquid seed method

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图 1 不同方法合成SAPO-34分子筛的XRD谱图

Figure 1 XRD patterns of SAPO-34 molecular sieves synthesized by different methods

a: direct method; b: solid seed method; c: liquid seed method

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图 2 不同方法合成SAPO-34分子筛的SEM照片

Figure 2 SEM images of SAPO-34 molecular sieves synthesized by different methods

(a): direct method; (b): solid seed method; (c): liquid seed method

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图 3 不同方法合成的SAPO-34分子筛的红外光谱谱图

Figure 3 FT-IR spectra of SAPO-34 molecular sieves synthesized by different methods

a: direct method; b: solid seed method; c: liquid seed method

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图 4 不同方法合成的SAPO-34分子筛的NH₃-TPD谱图

Figure 4 NH₃-TPD profiles of SAPO-34 molecular sieves synthesized by different methods

a: direct method; b: solid seed method; c: liquid seed method

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表 1 不同方法合成的SAPO-34分子筛的孔结构

Table 1 Textural properties of SAPO-34 molecular sieves synthesized by different methods

Sample	Surface area A/(m²·g^-1)			v_micro/(cm³·g^-1)	Average pore diameter d/nm
Sample	total	micro	external	v_micro/(cm³·g^-1)	Average pore diameter d/nm
Direct method	488.8	486.37	2.43	0.26	1.93
Solid seed method	492.9	491.59	1.31	0.27	2.11
Liquid seed method	496	492.5	3.49	0.26	2.21

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表 2 不同方法合成的SAPO-34分子筛的NH₃-TPD表征

Table 2 NH₃-TPD results of SAPO-34 molecular sieves synthesized by different methods

Sample	Acid density /(mmol·g^-1)
Sample	weak	strong	total
a	0.23	0.20	0.43
b	0.20	0.10	0.30
c	0.15	0.11	0.26

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表 3 不同方法合成分子筛的烯烃收率

Table 3 Yields of olefins for MTO over various SAPO-34 molecular sieves synthesized by different methods

Molecular sieves	Yields w/%
Molecular sieves	direct method	solid seed method	liquid seed method
CH₄	1.61	1.07	1.29
C₂H₆	1.61	0.89	1.28
C₂H₄	30.74	30.12	34.29
C₃H₈	4.50	3.21	3.91
C₃H₆	29.05	32.11	34.49
C₄H₁₀	0.45	0.45	0.48
C₄H₈	6.02	7.73	8.69
∑C₂⁼+C₃⁼	59.79	62.23	68.78
Conversion x/%	89.14	95.66	98.58
remarks: the sampling behavior is taken after reaction 10 min

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