论文总字数：26146字

摘 要

全球能源的需求每年以1.7 %的速度递增，高速的消耗加剧了能源利用的紧张局面，同时带来日益严重的环境问题。天然气、沼气等清洁能源的推广使用既可以缓解能源危机，又可以减轻环境污染、气候变化等问题。酸性CO₂气体的存在降低了热值，同时也会腐蚀管道，因此需要提纯除去混合气中的CO₂，提高燃气的适用性和热值。

常用的提纯天然气、沼气的方法分为：低温分离法、化学吸收法、膜分离法、变压吸附法。变压吸附法经济可行、环境友好广泛用于气体分离领域，吸附剂是变压吸附法的核心。

金属有机骨架材料 (MOFs) 是具有高吸附容量、高选择性、高稳定性、低耗再生能力强的吸附剂。其中，MIL-101孔隙率高、稳定性好、制备简单，是理想的气体吸附分离材料。由于CO₂相比于CH₄拥有较大的四极矩，因而CO₂有更大的极化率，为了提升CH₄/CO₂吸附分离性能，通常在材料中引入亲CO₂组分改性，因此在MOFs材料中引入碱性位，增加孔道极性，可以提升CO₂吸附能力，实现CH₄/CO₂分离。所以本文利用氨基改性MIL-101(Cr) 材料并对其CH₄/CO₂吸附分离性能进行研究。

考察聚乙烯亚胺 (PEI) 改性MIL-101(Cr)，并通过X射线衍射分析、比表面积与孔隙分析研究氨基改性MIL-101(Cr) 吸附剂的结构特征。结果表明，利用聚乙烯亚胺改性MIL-101(Cr)，随着聚乙烯亚胺含量的增加，MIL-101-PEI 系列吸附剂的骨架结构都能够很好地保持。

测试聚乙烯亚胺改性MIL-101(Cr) 吸附剂在1 bar、25 ^oC下的CO₂、CH₄吸附量。表明，氨基改性后的MIL-101(Cr) 与CO₂作用力显著增强，MIL-101-PEI-45 对CO₂的吸附量由74.60 cm³/g增加到114.89 cm³/g，提升54 %，CH₄吸附量则由16.52 cm³/g下降为7.87 cm³/g，降低52.36 %。同时，CO₂在80 ^oC、真空下即可再生，脱附条件温和。

关键词：金属有机骨架 氨基改性 吸附分离 甲烷 二氧化碳

Amine-Functionalized MIL-101(Cr) and its Adsorption Properties for CH₄/CO₂ Separation

ABSTRACT

The progress of the international energy demand shows a 1.7 % average annual growth in the 2005~2020 period.The high-speed consumption has exacerbated the tension of energy utilization as well as the serious environmental problems. Promoting the utilize of natural gas, biogas and other clean energy can solve the energy crisis and reduce environmental pollution. The acidic CO₂ gas needs to be reduced in order to avoid pipelines' corrosion and improve the heat value.

The purification methods of natural gas, biogas gas can be divided as follows: low temperature separation method, chemical absorption method, membrane separation method, pressure swing adsorption (PSA) method. PSA technology has been widely used in gas separation field which considered as economically and environmental friendly.

Metal-Organic Frameworks (MOFs), with novel structure and unique performance, has gained wide attention. Among them, MIL-101 is the ideal gas adsorption separation material owing to high porosity, good stability and simple preparation. CO₂ has larger quadrupole moment than CH₄, which causes CO₂ gas molecules to have much higher polarizability, therefore much stronger electrostatic interactions with sorbents. An obvious strategy to provide both the aforementioned properties was to introduce CO₂-philic moieties which can create strong interactions between the material surface and the CO₂. So this article focused on Amine-Functionalized MIL-101(Cr) materials and its separation performance of CH₄/CO₂.

We introduced Polyethylenimine (PEI) into MIL-101(Cr) through impregnation method. We also studied the structure characteristics of MIL-101-PEI adsorbents through X Ray Diffraction analysis, specific surface area and porosity analysis.The results showed that when we choose PEI as the amino source, the skeleton structure of MIL-101-PEI adsorbents can keep well with the increasing content of PEI.

The adsorption capacity of CO₂ and CH₄ on PEI-Functionalized MIL-101(Cr) adsorbents was measured under adsorption temperature of 298 K and adsorption pressure of 1 bar. The results showed that the interaction strength of Amine-Functionalized MIL-101(Cr) with carbon dioxide was strongly increased. The carbon dioxide adsorption capacity of MIL-101-PEI-45 was improved 54%, from 74.60 cm³/g to 114.89 cm³/g. The methane adsorption capacity was decreased 52.36 %, from 16.52 cm³/g to 7.87 cm³/g, which resulted in a better adsorption capability of CO₂ and separation performance for CO₂/CH₄. The ideal adsorbed solution theory (IAST) model was used to predict the adsorption separation of CO₂ over CH₄. The adsorbents could be regeneration with a temperature swing to 80 ^oC under vacuum. Desorption condition was mild.

Key Words: Metal-Organic Frameworks；Amino functionalized；Adsorption separation；Methane；Carbon dioxide

目 录

摘要 I

ABSTRACT II

第一章 绪论 1

1.1 引言 1

1.2 吸附分离 1

1.2.1 吸附基础 1

1.2.2 吸附理论与吸附方程 2

1.3 CH₄/CO₂分离研究进展 4

1.3.1 CH₄/CO₂混合气体分离体系 5

1.3.2 CH₄/CO₂混合气体分离 5

1.4 金属有机骨架材料 (MOFs) 7

1.4.1 金属有机骨架MIL-101 8

1.5 金属有机骨架材料改性方法 9

1.5.1 MOFs材料的配位改性 10

1.5.2 MOFs材料的掺杂改性 10

1.6 论文研究内容、目的和意义 11

第二章 实验仪器与方法 13

2.1 实验试剂和仪器 113

2.1.1 实验试剂 13

2.1.2 实验仪器 13

2.2 MIL-101(Cr)合成、后处理和改性 14

2.2.1 MIL-101(Cr)合成 14

2.2.2 MIL-101(Cr)后处理 15

2.2.3 MIL-101(Cr)改性 15

2.3 吸附剂表征 15

2.3.1 X射线衍射（X-Ray Diffraction, XRD） 15

2.3.2 红外分析（FT-IR） 15

2.3.3 比表面及孔结构测定 16

2.3.4 元素含量分析 16

第三章 聚乙烯亚胺改性MIL-101(Cr) 吸附分离CH₄/CO₂ 17

3.1 X射线衍射 18

3.2 比表面积及孔隙分析 19

3.3 傅立叶变换红外光谱 20

3.4 CH₄/CO₂吸附等温线 21

3.5 CH₄/CO₂吸附与脱附 24

3.6 本章小结 24

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