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题名: 聚合物孔材料的合成及VOCs吸附、分离过程的研究
作者: 王俊慧1
学位类别: 博士
答辩日期: 2017-05
授予单位: 中国科学院大学
授予地点: 北京
导师: 郝郑平
关键词: 挥发性有机化合物,吸附,膜分离,共轭微孔聚合物,PDMS ; Volatile organic compounds, Adsorption, Membrane separation, Conjugated microporous polymers, PDMS
其他题名: Synthesis of Polymer-based Porous Materials and Performances for Adsorption and Membrane Separation of Volatile Organic Compounds
学位专业: 环境工程
中文摘要: 随着我国国民经济的持续快速发展,能源消费的不断攀升,近二、三十年来,我国城市群地区正面临着以高浓度细颗粒物(PM2.5)和近地面臭氧为特征的区域性大气环境问题。挥发性有机化合物(Volatile Organic Compounds,VOCs)作为生成PM2.5和臭氧的重要前驱物,受到了政府和广大民众的关注。与销毁技术相比,回收技术可以浓缩大部分有机气体,不但可以净化空气,还能够回收大量溶剂,实现环保和经济的双重效益。论文主要针对工业源挥发性有机污染物VOCs的回收控制技术,研制了系列高效的聚合物基吸附、分离功能材料。采用氧化偶联反应合成了高吸附性能的共轭微孔高分子材料(CMPs),并用物理混合法制备了具有不同性能和结构的介孔硅-PDMS填充膜,用于分离VOCs/空气体系。通过多种表征手段研究了吸附质取代基电性对吸附质吸附行为的影响,还对无机填料孔道结构、表面形貌对填充膜吸附、分离性能的影响进行了系统研究。研究的主要内容及结论如下: 1. 通过氧化偶联反应,合成了一系列具有微孔-介孔复合孔结构的新型共轭微孔高分子吸附材料(CMPs),骨架结构中只含有C、H两种元素。通过调节单体浓度,可以调控其比表面积和孔结构。与市售活性炭相比,CMPs具有超强疏水性,同时也表现出较高的有机物/水选择性,对水和苯分子的吸脱附动力学均符合线性推动力模型(LDF),微孔-介孔复合孔结构使得气体在其中的吸附扩散速率较快。气体中高浓度水蒸气的存在对其吸附VOCs分子影响较小。 2.选取三种分子尺寸接近、含有不同性质取代基的芳香烃污染物:苯、甲苯、氯苯,研究了在共轭微孔高分子材料(CMP)上的吸附行为。供电子基团(-CH3)能够提高吸附质与吸附剂的相互作用力,并有利于提高吸附速率,吸电子基团(-Cl)则大大降低了吸附质-吸附剂的相互作用,且对氯苯的扩散速率有所削弱。 3. 以表面硅烷化处理的KIT-6介孔硅作为无机填料与PDMS高分子聚合物以物理共混的方式合成了一系列p-KIT-6/PDMS填充膜。当无机填料添加量为2 wt.%时,性能最佳,对n-C4H10的渗透量和n-C4H10/N2选择性分别提高了464%和284%,对CO2/N2体系也表现出了类似的分离效果。通过计算n-C4H10和CO2的溶解系数和扩散系数,发现两种冷凝性气体在填充膜中的扩散系数急剧提高,主要是归因于p-KIT-6丰富的三维介孔孔道结构。提出了一个合理的界面形态假设,认为,填充膜之所以能够同时提高n-C4H10的渗透量和n-C4H10/N2选择性,主要是由于两种气体在膜中扩散路径的差异导致的,而扩散速率与气体本身性质有关。4. 通过制备三种具有不同颗粒尺寸(纳米级和微米级)和孔道结构(二维和三维)的MCM介孔硅材料:nm MCM-48,nm MCM-41和μm MCM-48,并将其添加到PDMS膜中,制成MCM/PDMS填充膜,发现无机材料的孔道结构和颗粒尺寸对填充膜材料的分离性能均有很大影响。三维的孔道结构能促进气体在膜中的扩散速率,而纳米级的颗粒能与有机膜形成较好的结合从而提高对气体的选择性。
英文摘要: With the sustained and rapid development of China's national economy and the rising energy consumption, China's urban agglomeration is facing regional atmospheric environmental issues characterized by high concentration of fine particles (PM2.5) and near-surface ozone in the past two or three decades. Volatile Organic Compounds (VOCs), which are important precursors for the formation of PM2.5 and ozone, are of concern to the government and the general public. Compared with the destruction technology, recycling technology can concentrate most of the organic vapors, to achieve environmental and economic benefits, purifying the air and also recovering a large number of solvents. Focusing on the recovery of VOCs from industrial processes, a serious of high-efficiency adsorption and separation materials were studied in this paper, mainly including conjugated microporous polymers, mesoporous silica (KIT-6, MCM-48, MCM-41)/PDMS mixed matrix membranes. The influence of the properties of substituent on benzene on the adsorption thermodynamic and kinetic behaviors was studied. Systemic investigations have been carried out on the effect of the pore structure and morphology of inorganic fillers on the vapor/gas separation performance. The main research conclusions are listed as follow: 1. Conjugated microporous polymers (CMP), with micro/mesoporous structure were synthesized through homocoupling polymerization reaction as adsorbents for the removal of volatile organic compounds from gas streams. The results of the static water vapor adsorption experiment indicated that CMP-50 had a more hydrophobic surface than the commercial activated carbon (AC), and higher benzene/water selevtivity. CMP-50 had high adsorption capacity under wet condition (RH=80%) and fast adsorption kinetics. Moreover, the presence of water vapor in the gas stream had little effect on the adsorption capacity. 2. The adsorption of benzene, toluene and chlorobenzene, with similar molecule size, on CMP was conducted to investigate the influences of derivative groups on benzene rings on adsorption behaviors. The electron-donating substituent (-CH3) can increase the interactions between adsorbate and adsorbent and result in higher adsorption kinetics. However, the electron-withdrawing substituent (-Cl) can greatly decrease the adsorbate-adsorbent interaction and adsorption kinetics. -Cl can results in lower adsorption capacity of chlorobenzen on CMPs, which cannot exist in liquid in confined pores. 3. The first use of the mesoporous KIT-6 silica as an additive was explored to enhance the gas permeability and separation characteristics of PVDF supported polydimethyl- siloxane (PDMS). With an optimum loading of 2 wt.%, the n-C4H10 permeability and n-C4H10/N2 ideal selectivity of the MMM were shown to increase by 464% and 248% compared with the neat polymer membrane, respectively. In addition, the optimum membrane was also evaluated for CO2/N2 separation,which proved that the permeability and selectivity were increased simultaneously. The diffusivity coefficient of n-C4H10 has been greatly increased by the addtion of KIT-6, due to the abundent 3D mesoporous structure. An interface morphology has also been proposed to explain the separation phenomenon of the MMM reasonably. 4. Three kinds of mesoporous silica with different particle size (nanometer and micrometer) and pore structure (2D and 3D) have been synthesized and incorporated into PDMS membrane solution to fabricate MCM/PDMS membranes, and their separation performance for C3H6/N2 and n-C4H10/N2 have been examined. The results indicate that 3D pore structure can facilitate the diffusion of gases in membranes and nanometer-sized particles can enhance the adhesion between polymer and fillers, which results in better selectivity.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/38699
Appears in Collections:环境纳米材料研究室_学位论文

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作者单位: 1.中国科学院生态环境研究中心

Recommended Citation:
王俊慧. 聚合物孔材料的合成及VOCs吸附、分离过程的研究[D]. 北京. 中国科学院大学. 2017.
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