金属有机骨架材料分子设计与储氢性能分子模拟研究毕业论文

 2021-04-06 10:04

摘 要

金属有机骨架材料(Metal Organic Frameworks,MOFs)因为具有极高的比表面积和稳定性,在气体存储和工业催化等方面被广泛使用。金属有机骨架材料具有模块化可设计性的优点,可以通过替换或者改性功能化模块,来设计合成成千上万种MOFs材料。然而由于材料结构的相似性和多样性,这也给材料的筛选带来了很大的困难。随着模拟计算理论的逐渐进步与完善,通过计算不仅可以对不同结构的MOFs材料进行大规模的筛选,而且可以通过计算机软件设计新型MOFs材料,并模拟计算其理论性能,从而为减少开发合成材料的人力和物力,为合成理想的MOF材料提供理论指导。最近的研究表明,通过在MOFs材料中嵌入不饱和金属位以及不饱和键能够显著提高MOFs材料的储氢性能。在有机连接体中插入含金属的功能基团是嵌入不饱和金属位的一个有效方法。

摘 要

金属有机骨架材料(Metal Organic Frameworks,MOFs)因为具有极高的比表面积和稳定性,在气体存储和工业催化等方面被广泛使用。金属有机骨架材料具有模块化可设计性的优点,可以通过替换或者改性功能化模块,来设计合成成千上万种MOFs材料。然而由于材料结构的相似性和多样性,这也给材料的筛选带来了很大的困难。随着模拟计算理论的逐渐进步与完善,通过计算不仅可以对不同结构的MOFs材料进行大规模的筛选,而且可以通过计算机软件设计新型MOFs材料,并模拟计算其理论性能,从而为减少开发合成材料的人力和物力,为合成理想的MOF材料提供理论指导。最近的研究表明,通过在MOFs材料中嵌入不饱和金属位以及不饱和键能够显著提高MOFs材料的储氢性能。在有机连接体中插入含金属的功能基团是嵌入不饱和金属位的一个有效方法。儿茶酚配体可以与金属结合,形成具有单酸酐金属中心的MOFs和丰富的不饱和式金属配位点从而兼具不饱和键和金属位的优点。在该研究中,M-儿茶酚系统(其中M = Mg2 ,Sc2 ,Ti2 ,V2 ,Cr2 ,Mn2 ,Fe2 ,Co2 ,Ni2 ,Cu2 和Zn2 )被用作MOFs中金属化儿茶酚连接体的计算模型。本文主要通过分子设计手段设计由不同配位金属、苯环及不饱和炔键数量的儿茶酚有机连接体组装而成的MOFs材料,并计算其对氢气的吸附量,探讨材料的吸附机理,为合成具有更优的氢气吸附性能的材料奠定理论基础。

本文先进行分子设计,通过使ToBaCCo3.0软件设计出带有不同构型的金属-儿茶酚官能团及不同拓扑结构的近1800种MOFs材料。然后通过材料的结构数据进行预筛选,选择其中237种吸附性能较好的MOFs,通过巨正则蒙特卡洛模拟(GCMC)方法模拟77K、10MPa的条件下237种材料对氢气的体积吸附量与质量吸附量。通过对同一拓扑结构的MOF材料进行对比发现,配位金属为Mg、Cu、Co、Ni时,对氢气的吸附效果较好。对比不同拓扑结构的吸附量,发现nbob和pcu拓扑结构的MOF材料与其他拓扑类型的MOFs材料相比具有较高的比表面积和孔隙率,吸附效果最好。在237种MOF材料种挑选出其中吸附量最高的六种,分别为bcu_(Zr6O8)(TRZ)8(OH)8_CAT_L4_Fe、bcu_(Zr6O8)(TRZ)8(OH)8_CAT_L4_Ni、nbob_4c_Cu_1_CAT_L3_Fe、nbob_4c_Cu_CAT_L3_Ni、nbob_4c_Cu_CAT_L4_Cr、pcu_6c_Cu_CAT_L4_Co。在77K、10MPa下它们的绝对质量储氢量分别达到了15.168%、14.5735%、16.4564%、14.5735%、29.17968%、18.7202%,均远远超过了美国能源部DOE的质量储氢标准。为了检验上述六种材料的常温储氢性能,本文又讨论了在常温298K下,材料在1-12MPa下的吸附等温线。发现nbob_4c_Cu_CAT_L3_Ni在常温下的储氢性能达到了5.2746%,非常接近美国DOE标准,而且其对压力变化的反应很敏感,而其他五种材料在常温下的储氢性能较差。可以将nbob_4c_Cu_CAT_L3_Ni作为储氢的候选材料使用。

关键词:储氢;分子模拟;金属有机骨架材料;儿茶酚金属盐;

Abstract

Metal Organic Frameworks (MOFs) are widely used in gas storage materials and catalysts because of their high specific surface area and stable physicochemical properties. However, due to the diversity of new material structures, it also represents the diversification of functional properties, which brings great difficulties to the screening of metal-organic framework materials. With the rapid development of computer technology, theoretical calculations can not only screen a large number of different structures, but also reduce the cost of materials and time required for material synthesis, and lay the foundation for the synthesis of ideal materials. Recent studies have shown that the hydrogen storage properties of MOFs can be significantly improved by embedding unsaturated metal sites and unsaturated bonds in MOFs. The insertion of a metal-containing functional group into an organic linker is an effective method of embedding an unsaturated metal site. The catechol ligand can be combined with a metal to form MOFs having a metal center of a monoanhydride and a rich unsaturated metal coordination site, thereby having the advantages of both an unsaturated bond and a metal site. In this study, the M-catechol system (where M = Mg2 ,Sc2 ,Ti2 ,V2 ,Cr2 ,Mn2 ,Fe2 ,Co2 ,Ni2 ,Cu2 和Zn2 ) was used as the metallated catechol linker in MOFs. Calculate the model. In this paper, MOFs materials assembled from catechol organic linkers with different coordination metals, benzene rings and unsaturated acetylene bonds were designed by molecular design means, and the adsorption amount of hydrogen was calculated, and the adsorption mechanism of the materials was discussed. To lay a theoretical foundation for the synthesis of materials with better hydrogen adsorption properties.

In this paper, molecular design was first used to design nearly 1800 MOFs with different configurations of metal-catechol functional groups and different topologies by using ToBaCCo software. Then, through pre-screening of the structural data of the material, 237 kinds of MOFs with better adsorption performance were selected, and the volume of hydrogen of 237 materials under the conditions of temperature 77k and pressure 10MPa was simulated by the giant regular Monte Carlo simulation (GCMC) method. Adsorption amount and mass adsorption amount. By comparing the MOF materials of the same topology, it is found that when the coordination metals are Mg, Cu, Co, and Ni, the adsorption effect on hydrogen is better. Comparing the adsorption capacity of different topologies, it is found that the MOF materials of nbob and pcu topologies have higher specific surface area and porosity than other topological types of MOF materials, and the adsorption effect is the best. Six of the 237 kinds of MOF materials were selected, which were the six materials above.At 77K and 10MPa, their absolute mass hydrogen storage capacity reached 15.168%, 14.5735%, 16.4644%, 14.5735%, 29.18286%, and 18.7220%, respectively, which far exceeded the US Department of Energy DOE quality hydrogen storage standards. In order to test the hydrogen storage performance of the above six materials, the adsorption isotherm of the material at 12:00 MPa at room temperature of 298K is discussed. It is found that the hydrogen storage performance of nbob_4c_Cu_CAT_L3_Ni at room temperature reaches 5.2466%, which is very close to the US DOE standard, while the other five materials have poor hydrogen storage performance at normal temperature. Nbob_4c_Cu_CAT_L3_Ni can be used as a candidate material for hydrogen storage.

Key words: Hydrogen storage; Molecular simulation; Metal organic framework material; Catechol metal salt;

目 录

摘要 I

Abstract II

目 录 IV

第一章 绪论 1

1.1概述 1

1.2选题的意义 2

第二章 理论计算原理和方法 4

2.1分子模拟方法简介 4

2.1.1蒙特卡洛模拟 5

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