金属—有机骨架材料对硫化物吸附分离行为的分子模拟研究

发布时间：2018-02-09 10:18

本文关键词： 金属-有机骨架材料硫化物吸附/分离分子模拟　出处：《浙江理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着煤、石油、天然气等能源的大量消耗,空气中SO_2、H_2S等硫化物日益增加,硫化物的存在不仅污染环境,同时也将危害人类健康及腐蚀天然气输运管道设备等。因此,筛选高效捕获及分离硫化物的微孔材料有重要的意义。金属-有机骨架材料(Metal-organic frameworks,MOFs)因具有较高的比表面积和孔隙率、孔径可调性以及高的热稳定性和化学稳定性等独特优势,被认为是用于硫化物吸附与分离最有前途的新型多孔材料。虽然研究者可通过突破实验、吸附实验等方式研究硫化物在不同MOFs材料中的吸附与分离行为,但是目前已经报道和合成的MOFs材料高达数万种,若利用上述方法测定硫化物在其中的吸附等温线,成本高、效率低。近年来发展起来的分子模拟方法能够快速对大量MOFs材料进行研究,获得有效的构-效关系,同时能够对传统实验手段做出补充,从分子层面揭示吸附机制。本论文针对硫化物在不同MOFs材料中的吸附与分离行为与其结构性质之间的构-效关系不清楚这一问题,拟采用巨正则系统蒙特卡罗模拟方法探讨烟道气中SO_2及天然气中H_2S在不同MOFs材料中的吸附与分离行为,揭示MOFs材料与硫化物(SO_2、H_2S)之间的相互作用机制,阐述MOFs材料的拓扑结构、金属离子以及有机配体等因素对硫化物吸附分离性能的影响,为设计对硫化物具有良好吸附与分离性能的MOFs材料提供理论指导和依据。论文的主要研究结果如下:(1)拓扑结构不同,孔径不同,低压下孔径越小,硫化物与ZIFs材料之间的相互作用越强,吸附性能越好。低压时硫化物在孔径较小的ZIF-2中的吸附量最大。高压时硫化物在ZIFs材料中的吸附量随着孔径或比表面积增大而增加。ZIF-3对烟道气中SO_2及天然气中H_2S具有较优的捕获和选择性。(2)对于M-DOBDCs系列材料,不饱和金属位点和有机配体配位时所构成角度越大,烟道气中SO_2与不饱和金属位点接触概率越大,其与M-DOBDCs之间相互作用越强,而CO2与该M-DOBDCs之间相互作用则越弱,角度最大的Zn-DOBDC材料对烟道气中SO_2捕获与分离性能最优。M-DOBDCs系列材料对天然气中H_2S的捕获与分离性能则与不饱和金属位点和有机配体配位时所构成角度成反比,角度最小的Mg-DOBDC材料对H_2S的捕获与分离性能最佳。(3)对于有机配体不同的UMCMs系列材料,N原子的位置不同导致孔道电荷密度分布不同。硫化物倾向于吸附在N原子朝向主孔道的UMCM-150(N)1材料中,该材料对烟道气中SO_2及天然气中H_2S具有较优的捕获和分离性能,向UMCM-150(N)1中引入极性功能化基团可以改善其对硫化物的分离性能,其中极性较大基团(硝基和羧基)改性的UMCM-150(N)1材料对烟道气中SO_2捕获和分离性能较佳,经过(氨基和羧基)改性的UMCM-150(N)1材料对天然气中H_2S具有较优的捕获和分离性能。
[Abstract]:With the massive consumption of coal, oil, natural gas and other energy sources, the number of sulfides such as SO2H2S in the air is increasing day by day. The presence of sulfides will not only pollute the environment, but also endanger human health and corrode natural gas transportation pipeline equipment and so on. It is of great significance to screen microporous materials for high efficiency capture and separation of sulfides. Metal-organic frameworks / MOFss have unique advantages such as high specific surface area and porosity, adjustable pore size, high thermal and chemical stability, etc. It is considered to be the most promising new porous material for the adsorption and separation of sulfides, although researchers can study the adsorption and separation behavior of sulfides in different MOFs materials by breakthrough experiments, adsorption experiments, etc. However, tens of thousands of MOFs materials have been reported and synthesized at present. If the adsorption isotherms of sulfides in them are determined by the above methods, the cost will be high. Low efficiency. Molecular simulation methods developed in recent years can rapidly study a large number of MOFs materials, obtain effective structure-activity relationships, and complement traditional experimental methods. The adsorption mechanism is revealed at the molecular level. In this paper, the structure-activity relationship between the adsorption and separation behavior of sulfides in different MOFs materials and their structural properties is not clear. The adsorption and separation behavior of SO_2 in flue gas and H2S in natural gas in different MOFs materials is studied by means of Monte Carlo simulation of grand canonical system. The mechanism of interaction between MOFs material and so _ 2 / S _ 2 / S _ 2S _ S is revealed, and the topological structure of MOFs material is expounded. Effects of metal ions and organic ligands on the adsorption and separation of sulphide, It provides theoretical guidance and basis for the design of MOFs materials with good adsorption and separation properties for sulfides. The main results of this paper are as follows: the topological structure is different, the pore size is different, and the pore size is smaller at low pressure. The stronger the interaction between sulfides and ZIFs materials, The adsorption capacity of sulfides in ZIF-2 with small pore size is the highest at low pressure. The adsorption capacity of sulfide in ZIFs materials increases with the increase of pore size or specific surface area. ZIF-3 increases the adsorption of SO_2 in flue gas and H2S in natural gas at high pressure. Have better capture and selectivity. 2) for M-DOBDCs, The greater the angle of coordination between unsaturated metal sites and organic ligands, the greater the contact probability between SO_2 and unsaturated metal sites in flue gas, the stronger the interaction between CO2 and M-DOBDCs, but the weaker the interaction between CO2 and M-DOBDCs. The best capture and separation performance of SO_2 in flue gas by the most angled Zn-DOBDC materials. M-DOBDCs series of materials for the capture and separation of H 2S in natural gas are inversely proportional to the angle formed by the coordination of unsaturated metal sites and organic ligands. For organic ligands with different UMCMs series, different positions of N atoms lead to different distribution of pore charge density. Sulfides tend to adsorb toward N atoms. In the UMCM-150(N)1 material of the main pore, The material has better capture and separation performance for SO_2 in flue gas and H2S in natural gas. The introduction of polar functional groups into UMCM-150(N)1 can improve the separation performance of sulfides. The modified UMCM-150(N)1 materials with larger polar groups (nitro and carboxyl groups) have better capture and separation performance for SO_2 in flue gas, and the modified UMCM-150(N)1 materials (amino and carboxylic groups) have better capture and separation performance for H2S in natural gas.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O647.3;X701

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