摘 要

UiO-66是一种微孔MOFs，具有8Å和11Å的四面体和八面体孔笼，通过5~7Å三角形孔口连接。利用UiO-66对正异构烷烃的反择形吸附机理，即优先吸附分子动力学直径较大的异构烷烃，可从95wt%的庚烷中直接获得高纯度正庚烷产品，然而由于其微孔结构限制，脱附温度较高(≥240℃)。为改善正庚烷/甲基环己烷在UiO-66上的吸附扩散性能，降低脱附温度，本文采用模板法合成多级孔UiO-66（本文称H-UiO-66），考察合成温度及合成时间对H-UiO-66的影响，并采用XRD和N₂吸附/脱附等温线对H-UiO-66进行表征，测定nHEP/MCH在UiO-66、H-UiO-66上动态吸附/脱附性能。主要研究内容和结论如下：

（1）多级孔UiO-66合成工艺优化。考察合成温度及合成时间对H-UiO-66孔结构的影响。结果表明：合成温度120℃、合成时间24时，H-UiO-66的介孔孔容可达0.90cm³/g，占总孔容比例为0.81。

（2）测定了nHEP/MCH双组分（配比为1:1）在UiO-66、H-UiO-66上动态吸附分离性能。结果表明：吸附温度从140℃提高到200℃，UiO-66对正庚烷的穿透吸附量下降了41%，而甲基环己烷的穿透吸附量降低18%；吸附温度从140℃提高到200℃，吸附剂H-UiO-66正庚烷的穿透吸附量下降了45%，而甲基环己烷的穿透吸附量降低20%。

（3）测定了nHEP/MCH双组分（配比为1:1）在UiO-66、H-UiO-66上动态脱附分离性能。结果表明：引入多级孔后，对正庚烷和甲基环己烷的脱附率H-UiO-66明显高于UiO-66。

关键词：多级孔UiO-66 正庚烷 甲基环己烷 吸附 脱附

Study on Synthesis of Hierarchical Pores UiO-66 and Its Adsorption/Desorption Performance for n-Heptane/Methyl Cyclohexane

ABSTRACT

UiO-66 is a microporous MOFs with tetrahedral and octahedral cages of 8Å and 11Å, connected by a 5 to 7Å triangular orifice. Based on the anti-selective adsorption mechanism of n-isoalkanes of UiO-66, the preferential adsorption isoparaffins with large molecular dynamic diameters, high-purity n-heptane products can be directly obtained from 95 wt% of heptane. However, due to its microporous structure, desorption temperature is high (≥240°C). For improving adsorption and diffusion properties of n-heptane/methylcyclohexane on UiO-66 and reducing the desorption temperature, in this paper, hierarchical pore UiO-66 (referred to as H-UiO-66) was synthesized by template method, and the effects of synthesis temperature and synthesis time on H-UiO-66 were investigated. XRD and adsorption/desorption isotherms of N₂ were used for H- UiO-66 was characterized to determine the dynamic adsorption/desorption properties of nHEP/MCH on UiO-66 and H-UiO-66. The main research contents and conclusions are as follows.

(1) Optimization of synthesis process of multi-hole UiO-66. Effects of /synthesis temperature and time on the pore structure of H-UiO-66 were investigated. Results show that synthesis temperature is 120°C and synthesis time is 24h, the mesoporous volume of H-UiO-66 can reach 0.90cm³/g, and the total pore volume ratio is 0.81.

(2) Dynamic adsorption and separation performance of nHEP/MCH two-component (1:1 ratio) on UiO-66 and H-UiO-66 was measured. Results show that adsorption temperature of n-heptane on UiO-66 decreases 41%, methylcyclohexane decreases 18% from 140 °C to 200 °C. Adsorption temperature increases from 140°C to 200°C, breakthrough adsorption uptake of n-heptane on H-UiO-66 decreased 45%, and methylcyclohexane decreases 20%.

(3) Dynamic desorption and separation performance of nHEP/MCH two-component (1:1 ratio) on UiO-66 and H-UiO-66 was measured. Results show desorption rate of n-heptane and methylcyclohexane on H-UiO-66 is significantly higher than that on UiO-66 after the introduction of hierarchical pore.

Keywords: hierarchical pores UiO-66; n-heptane; methyl cyclohexane; adsorption; desorption

目录

摘 要 I

ABSTRACT II

第1章 概述 1

1.1 正庚烷及其用途 1

1.2 正庚烷分离技术研究现状 1

1.2.1 精馏分离法 1

1.2.2 萃取分离法 2

1.2.3 吸附分离法 2

1.3 多级孔MOFs合成研究进展 3

1.4 多级孔UiO-66的合成及应用 4

1.5 本文主要研究内容 4

第2章 实验 6

2.1 主要试剂 6

2.2 多级孔UiO-66制备方法 6

2.2.1 XRD分析物相 6

2.2.2 N₂吸附/脱附等温线分析孔结构 6

2.3 正庚烷/甲基环己烷在UiO-66及H-UiO-66动态吸附/脱附实验 7

2.3.1 实验装置和步骤 7

2.3.2正庚烷/甲基环己烷在UiO-66及H-UiO-66动态实验条件 7

2.3.3 数据处理及分析方法 7

第3章 结果与讨论 9

3.1 多级孔UiO-66表征 9

3.1.1不同合成温度及时间对H-UiO-66 物相结构影响 9

3.1.2不同合成温度及时间对H-UiO-66孔结构影响 9

3.2 多级孔UiO-66对双组分nHEP/MCH吸附穿透曲线 11

3.3 多级孔UiO-66对双组分nHEP/MCH脱附曲线 12

第4章 结论与展望 16

4.1 结论 16

4.2 展望 17

参考文献 18

致谢 21

第1章 概述

1.1 正庚烷及其用途

正庚烷，英文名：n-heptane；化学式：C₇H₁₆；常温常压下是无色、易挥发透明液体^[1-2]，对皮肤有一定的刺激性。

正庚烷在常温常压下化学性质稳定，可作为萃取溶剂、增溶剂、橡胶工业溶剂^[3]。此外，正庚烷还可作有机合成的原料；实验试剂的制备；臭氧、测定辛烷值的标准物、三甘油脂等的测定^[4]以及色谱分析参比物。

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