PAF-1碳化材料的吸附分离性能研究

发布时间：2018-04-12 08:51

  本文选题：吸附分离 + 理想吸附溶液理论　； 参考：《浙江师范大学》2015年硕士论文

【摘要】：现代化工业社会过多使用化石燃料,释放大量的C02等温室气体,严重危害地球生态平衡,而吸附分离技术是目前捕集C02最有效的方法之一。多孔芳香骨架材料(Porous aromatic frameworks, PAFs)则由于其巨大的比表面积、良好的物理化学稳定性、孔容和孔径可调控性及永久的微孔性等优良特性,使得此类材料在气体吸附分离等领域有着广泛的应用前景。本文选用PAF-1材料作为前驱体对其进行碳化后处理,并初步研究碳化材料对C02的吸附分离性能,文章主要围绕以下三个方面进行研究：1.首先参考文献合成四溴代四苯甲烷并以其为聚合反应单体,利用金属Ni催化的厄尔曼偶联反应合成具有金刚石结构的PAF-1材料。然后,采用KOH作为活化剂,通过高温处理以实现PAF-1的碳化,并考察活化温度对碳化材料结构的影响。利用XRD、SEM、TGA和N2吸脱附等表征手段对所得材料进行结构表征,结果表明,所制备的PAF-1材料具有较高的BET比表面积(3921 m2/g),最可几孔径分布在约1.4 nm处。碳化后所得材料BET比表面积均有所下降,孔径变小,孔径分布结果显示其同时具有0.5-0.8 nm和1.2 nm两种尺寸的孔。在实验考察温度范围内,碳化材料的BET比表面积、总孔容及微孔孔容都随着碳化温度的升高而升高,其中以800℃为最佳碳化温度。2.选取碳化温度为800℃的碳化材料(K-PAF-1-800)作为吸附剂,利用静态体积法分别测定了CO2、CH4和N2在25℃、37℃和50℃下的单组分气体吸附等温线,并选用Toth模型对实验数据进行拟合。结果表明,该模型可以很好地描述实验测得的吸附等温线。此外,采用Clausius-Clapeyron方程计算获得等量吸附热随吸附量的变化曲线,获得了吸附热力学参数。当吸附量较低时,CO2、CH4和N2的等量吸附热随着吸附量的升高有所增加,但随着吸附量的进一步升高,等量吸附热反而呈下降趋势,这与K-PAF-1-800同时具有两种尺寸的孔有关,当吸附量较低时,吸附主要发生在小孔孔道中,随着吸附量的增加,吸附质分子之间的作用力增加,从而导致等量吸附热随着吸附量的升高而增加；当吸附质在小孔孔道中充填满后,吸附质分子只能在大孔孔道中吸附,由于吸附质分子与大孔孔道间的作用力较弱,从而导致等量吸附热随着吸附量的升高而降低。3.基于三种吸附质分子在K-PAF-1-800上的吸附强度不同,采用穿透柱技术测定了CO2/N2和CO2/CH4双组分混合气体在K-PAF-1-800上的吸附分离行为。实验结果表明,我们所研究的K-PAF-1-800材料对CO2/N2和CO2/CH4两种不同的混合体系均表现出良好的吸附分离性能。此外,利用理想吸附溶液理论(ideal adsorbed solution theory, IAST)对双组分混合气体的吸附分离性能进行了预测,预测结果与穿透柱实验结果基本相符。
[Abstract]:In modern industrial society, excessive use of fossil fuels, release of a large amount of CO2 and other greenhouse gases, seriously endangers the ecological balance of the earth. Adsorption and separation technology is one of the most effective methods to capture CO2 at present.The porous aromatic frames (PAFs) have excellent properties such as large specific surface area, good physical and chemical stability, pore volume and pore size control, and permanent micropore properties.This kind of material has a wide application prospect in gas adsorption separation and other fields.In this paper, PAF-1 was chosen as the precursor for carbonization and post-treatment, and the adsorption and separation properties of CO2 were preliminarily studied. The study focused on the following three aspects: 1.Firstly, tetrabromotetraphenylmethane was synthesized with reference to the literature and used as polymerization monomer to synthesize PAF-1 material with diamond structure by Erman coupling reaction catalyzed by metal Ni.Then, KOH was used as activator to realize the carbonization of PAF-1 by high temperature treatment, and the effect of activation temperature on the structure of carbonized materials was investigated.The structure of the PAF-1 was characterized by XRD-SEMGA and N2 adsorption and desorption. The results showed that the prepared PAF-1 material had a high BET specific surface area of 3921 m2 / g ~ (-1) and the most suitable pore size was about 1.4 nm.After carbonization, the BET surface area decreased and the pore size became smaller. The pore size distribution showed that the pore size was 0.5-0.8 nm and 1.2nm at the same time.The BET surface area, total pore volume and micropore volume of carbonized materials increased with the increase of carbonation temperature, and the optimum carbonization temperature was 800 鈩，

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