苯在酸碱处理多级孔Y分子筛上的吸附及传质行为

万晓蕊; 初春雨; 白国强; 高士梁; 孟秀红; 段林海

苯在酸碱处理多级孔Y分子筛上的吸附及传质行为

辽宁石油化工大学辽宁省石油化工催化科学与技术重点实验室, 辽宁抚顺 113001

基金项目:

国家自然科学基金 21476101

详细信息

通讯作者:
段林海, Fax: +86-24-56860658, E-mail: lhduan@126.com

中图分类号: O643
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- 被引次数: 0
出版历程
- 收稿日期: 2015-12-16
- 修回日期: 2016-02-28
- 网络出版日期: 2021-01-23
- 刊出日期: 2016-05-10

Adsorption and mass transfer behavior of benzene on hierarchically structured Y by acid-base treatment

Key Laboratory of Petrochemical Catalytic Science and Technology of Liaoning Province, Liaoning Shihua University, Fushun 113001, China

Funds:

the National Natural Science Foundation of China 21476101

摘要

摘要: 利用H₄EDTA-NaOH共处理的方法制备了具有不同孔径分布的多级微-介孔NaY分子筛。运用XRD、N₂吸附、SEM、TEM对其结构进行了表征。采用频率响应(FR) 和智能重量分析仪(IGA) 技术研究了苯在改性后的多级孔NaY分子筛及微孔NaY分子筛上的吸附和传质性能。结果表明, 适当的酸碱处理不会改变分子筛的晶体结构, 但可调变NaY分子筛的精细结构; 介孔的引入降低了分子在孔道中的扩散阻力, 较大的孔径和较好的孔道贯通性有利于扩散和吸附中心的可接近性; 对于微孔NaY分子筛, 苯在分子筛上的吸附过程为其传质过程的速控步骤, 对于酸碱处理的多级孔NaY分子筛, 分子筛颗粒中微/介孔内的扩散过程及分子筛微-介孔孔道间的分子交换过程是传质过程的速控步骤。
- 多级孔Y /
- 苯 /
- 频率响应 /
- 吸附扩散
Abstract: A series of hierarchical NaY zeolites with different pore size distribution were synthesized by sequential treatment with ethylenediaminetetraacetic acid and NaOH. The structural properties of the as-synthesized hierarchical NaY zeolites were characterized by X-ray diffraction, N₂ sorption, SEM and TEM. The adsorption and diffusion performances of benzene on NaY and hierarchical NaY zeolites were studied by frequency response (FR) and intelligent gravimetric analyser (IGA). It was found that the structure of NaY zeolite was remained by suitable acid and base treatment, but the connectivity in the pores was finely tailored. Mesoporous was introduced to reduce the molecular diffusion resistance in the pores, while the larger pore size and connectivity in the mesoporous was more beneficial to diffusion and accessibility of activity site. The adsorption of benzene on NaY was found to be the rate-controlling step. While, the limiting steps for the overall mass transfer processes in the hierarchical zeolites are the diffusion process in the length scale of micropore/mesopore and the mass transfer at the micropore-mesopore molecular exchange rather than the intracrystalline diffusion one in the micropores of the zeolite crystals.
- hierarchical porous Y /
- benzene /
- frequency response /
- adsorption and diffusion

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图 1 NaY、SJ-1、SJ-2和SJ-3的XRD谱图

Figure 1 XRD patterns of NaY, SJ-1, SJ-2 and SJ-3 zeolites

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图 2 NaY、SJ-1、SJ-2和SJ-3的N₂吸附脱附等温线和脱附分支孔径分布

Figure 2 Adsorption-desorption isotherms and the corresponding BJH desorption pore size distributions of parent zeolite NaY, SJ-1, SJ-2 and SJ-3

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图 3 改性前后样品的SEM和TEM照片

Figure 3 SEM and TEM images of untreated NaY, acid-base treated NaY-based micro-/mesoporous composites

(a): SEM image of NaY; (b): SEM image of NaY after modification; (c): TEM image of NaY; (d): TEM image of NaY after modification

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图 4 303 K时苯在NaY、SJ-1、SJ-2和SJ-3分子筛上的吸附等温曲线

Figure 4 Adsorption isotherms of benzene on NaY, SJ-1, SJ-2 and SJ-3 zeolites at 303 K

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图 5 303 K时苯在NaY分子筛和SJ-1、SJ-2和SJ-3分子筛上的吸附速率曲线

Figure 5 Adsorption rate curve of benzene on NaY, SJ-1, SJ-2 and SJ-3 zeolite at 303 K

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图 6 373 K时不同压力下苯在NaY分子筛上吸附频率响应谱图

Figure 6 FR spectra of benzene adsorption on NaY at 373 K under different pressures

(a): 66.99 Pa; (b): 133.32 Pa; (c): 266.64 Pa

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图 7 373 K时不同压力下苯在SJ-1分子筛吸附频率响应谱图

Figure 7 FR spectra of benzene adsorption on SJ-1 at 373 K under different pressures

(a): 66.99 Pa; (b): 133.32 Pa; (c): 266.64 Pa

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图 8 373 K时不同压力下苯在SJ-2分子筛上吸附频率响应谱图

Figure 8 FR spectra of benzene adsorption on SJ-2 at 373 K under different pressures

(a): 66.99 Pa; (b): 133.32 Pa; (c): 266.64 Pa

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图 9 373 K时不同压力下苯在SJ-3分子筛吸附频率响应谱图

Figure 9 FR spectra of benzene adsorption on SJ-3 at 373 K under different pressures

(a): 66.99 Pa; (b): 133.32 Pa; (c): 266.64 Pa

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表 1 NaY、SJ-1、SJ-2和SJ-3的织构性质

Table 1 Texture properties data of NaY, SJ-1, SJ-2 and SJ-3 zeolites

Sample	d_aver/nm	A_BET/(m²·g^-1)	A_meso/(m²·g^-1)	A_mic/(m²·g^-1)	v_p/(m³·g^-1)	v_micro/(m³·g^-1)	v_meso/(m³·g^-1)
NaY	3.12	647	49	598	0.352	0.313	0.039
SJ-1	8.68	709	147	562	0.666	0.296	0.37
SJ-2	8.54	688	109	579	0.563	0.304	0.259
SJ-3	9.44	556	143	413	0.608	0.217	0.391

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表 2 室温下苯分子在NaY、SJ-1、SJ-2和SJ-3分子筛上的扩散时间常数

Table 2 Diffusion time constants of benzene on NaY, SJ-1, SJ-2 and SJ-3 zeolite

D/r²(s^-1)
NaY	SJ-1	SJ-2	SJ-3
6.17×10^-7	1.61×10^-6	2.07×10^-6	1.41×10^-6

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