结晶微孔材料的透射电子显微分析

发布时间：2018-05-19 09:02

本文选题：透射电子显微分析 + 电子衍射断层术　；参考：《吉林大学》2015年博士论文

【摘要】：随着材料科学的发展,材料种类也越来越丰富,微孔材料因为具有大的比表面积、分子选择性等优点,而被广泛应用于气体吸附与分离、离子交换以及催化等领域。但一种材料是否有应用价值、有多大的应用前景,与其结构性质是紧密相关的,因此对材料的结构进行研究有着十分重要的意义。微孔材料根据其结晶性划分,包含了无定形的微孔材料(如活性炭、PAF等)已及结晶的微孔材料(如分子筛、金属-有机骨架材料等)。无定形材料由于在原子量级为无序排列或者为短程有序,因此很难用一个确切的结构模型来描述,因此我们研究的重点是结晶微孔材料的结构问题。传统的研究晶体结构的主要手段有:单晶X-射线衍射法(SXRD)、粉末X-射线衍射法(PXRD)以及透射电子显微分析(TEM)等三种方法。本论文主要运用透射电子显微学方法来研究沸石分子筛(Zeolite)和金属-有机骨架材料(Metal-Organic Frameworks,MOFs)的结构问题,特别是利用一种全新的透射电子显微分析技术——三维电子衍射断层重构(Electron Diffraction Tomography,EDT)技术来解析分子筛和金属-有机骨架材料的结构。本文主要包含以下几个部分:第一章是绪论部分,概述了微孔材料和透射电子显微镜的发展历史,简单介绍了传统的透射电子显微学的应用以及取得的成果,并重点讲述了三维电子衍射断层技术(EDT)的发展背景、工作原理。另外,也对三维电子衍射断层重构的研究工具——RED软件做了详细介绍等。第二章,主要介绍了传统的透射电子显微学在沸石分子筛材料的结构研究中的应用。首先,我们利用高分辨透射电子显微术(High Resolution Transmission Electron Microscopy,HRTEM)研究了A相富集Beta分子筛中的A、B相层错共生的缺陷问题。并在原子级层面分析了其A、B相的堆积方式,计算了不同样品颗粒中A相所占的比例。其次,我们研究了多级孔Beta分子筛材料的孔壁结晶情况,以及样品整体的结晶性,并证明了该样品颗粒整体上是高度有序的结晶微介孔复合材料。最后,我们还研究了多级孔ZSM-5分子筛样品颗粒的结晶状况,以及构成样品颗粒的纳米片的生长取向问题。第三章,主要探索了EDT技术在MOFs材料的结构分析中应用的可行性。目前,利用EDT技术解析分子筛结构已经有了大量报道,但利用EDT技术来解析MOFs材料的结构尚未有报道,因此我们计划将EDT技术拓展到MOFs材料的结构解析领域。金属锆的MOFs具有着良好的稳定性,而Ui O-66便是其中的典型代表。Ui O-66具有粒径尺寸均一(一般在100-300nm)、稳定性良好,因此很适合用EDT技术来尝试解析它的结构。我们在用EDT方法获得Ui O-66的骨架结构之后,将其与HRTEM直接“观察”得到的结果进行了比较,发现两者是吻合的,最后我们又将其与PXRD精修得到的结构的原子位置进行了比较,发现RED方法获得结果与PXRD结果的原子位置坐标基本相同,仅有一个氧原子(O2)的位置坐标有较大的偏差(0.35?),其他原子的位置坐标偏差均小于0.1?。这说明EDT技术应用于金属-有机骨架材料的结构解析是可行的。第四章,我们主要应用了EDT技术来研究了MOFs材料——JUC-32的端基氧原子。材料端基原子(或原子团)的性质在很大程度上决定了材料的物理化学性质,因此对材料端基原子的研究具有重要的意义。随着透射电子显微技术的进步,特别是球差校正电镜的出现,利用透射电子显微镜直接“观察”到金属氧化物中的氧原子已经实现。但想要“观察”到氧原子就需要很高的放大倍率,此时单位面积电子辐照剂量也非常高,对样品损伤也十分严重,因此利用球差校正电镜只能研究在电子束辐照下非常稳定的材料。而绝大多数MOFs材料在电子束作用下都很不稳定,因而很难用球差校正电镜直接“观察”来研究。而利用其他电子显微学方法来研究MOFs材料的端基原子的文献也鲜有报道,因此利用EDT技术来研究确定JUC-32端基氧原子位置就有着十分重要的意义。第五章,我们利用EDT技术成功解析了一种新型磷铝分子筛PST-6的结构骨架,并将其结果与HRTEM照片分析的结果进行了对比,发现两者是基本吻合的,再次证明了三维电子衍射断层重构技术可以广泛应用于复杂分子筛的结构解析。总结,本论文讨论了传统透射电子显微学在材料结构研究中的应用,将EDT技术对比传统的结构解析方法的做了对比,探讨了EDT技术在MOF材料的结构解析中的运用的可行性,最后我们利用EDT技术成功解析了结构未知的磷铝分子筛PST-6的骨架结构。我们的研究工作为EDT技术的进一步完善和发展做出了积极的贡献。也为电子显微学方法在材料结构研究中的应用与推广产生了极大的促进作用。
[Abstract]:With the development of material science, the variety of materials is becoming more and more rich. Microporous materials have been widely used in the fields of gas adsorption and separation, ion exchange and catalysis because of the advantages of large specific surface area and molecular selectivity. However, whether a material has application value or not has many applications and is closely related to its structure and properties. Therefore, it is of great significance to study the structure of materials. According to their crystallization, microporous materials include amorphous microporous materials (such as activated charcoal, PAF, etc.) and crystallized microporous materials (such as molecular sieves, metal organic skeleton materials, etc.). Amorphous materials are arranged in order of order in order of order, or for short range. Therefore, it is difficult to describe the structure of a precise structural model, so the focus of our research is the structure of crystalline microporous materials. The main means to study the crystal structure are three methods, such as single crystal X- ray diffraction (SXRD), powder X- ray diffraction (PXRD) and transmission electron microanalysis (TEM). This paper is mainly used in this paper. Transmission electron microscopy is used to study the structural problems of zeolite molecular sieves (Zeolite) and metal organic framework materials (Metal-Organic Frameworks, MOFs), especially for the analysis of molecular sieves and gold using a new transmission electron microscopic analysis technique, three dimensional electron diffraction fault reconstruction (Electron Diffraction Tomography, EDT) technology. The structure of the genera organic skeleton material. This article mainly contains the following parts: the first chapter is the introduction, summarizing the development history of microporous materials and transmission electron microscopy, briefly introducing the application and achievements of traditional transmission electron microscopy, and focusing on the development background of the three-dimensional electron diffraction tomography (EDT). The second chapter, the second chapter, mainly introduces the application of traditional transmission electron microscopy in the structure study of zeolite molecular sieve materials. First, we use High Resolution Transmission Elec (high resolution transmissive electron microscopy). Tron Microscopy, HRTEM) studied the defects of A and B phase dislocation in Beta molecular sieves enriched by A phase, and analyzed the accumulation mode of A and B phase at the atomic level and calculated the proportion of A phase in different sample particles. Secondly, we studied the pore wall crystallization of multistage pore Beta molecular sieves and the crystallization of the sample as a whole. It is proved that the sample particles are highly ordered crystalline micro mesoporous composites on the whole. Finally, we also studied the crystallization of the sample particles of the multistage ZSM-5 molecular sieve and the growth orientation of the nanoscale particles that constitute the sample particles. The third chapter mainly explored the application of EDT in the structural analysis of MOFs materials. At present, there have been a lot of reports on the analysis of molecular sieve structure using EDT technology, but it is not reported that using EDT technology to analyze the structure of MOFs materials has not been reported. Therefore, we plan to extend the EDT technology to the domain of structural analysis of MOFs materials. The MOFs of metal zirconium has good stability, and Ui O-66 is a typical.Ui O-66. The size of the particle size is uniform (generally in 100-300nm) and has good stability, so it is very suitable to use EDT technology to try to analyze its structure. After we use the EDT method to obtain the skeleton structure of Ui O-66, we compare the results with the results obtained directly from the HRTEM "observation", and find that they are in good agreement with the PXRD. Finally, we also refined it with the PXRD. The atomic position of the structure is compared. It is found that the results obtained by the RED method are basically the same as the atomic position coordinates of the PXRD results. The position coordinates of only one oxygen atom (O2) have a larger deviation (0.35?) and the position coordinates of other atoms are less than 0.1? This indicates that the EDT technology is applied to the structural analysis of the metal organic skeleton materials. It is feasible. In the fourth chapter, we mainly use EDT technology to study the MOFs material, the terminal oxygen atom of JUC-32. The properties of the end group atom (or atomic mass) determine the physical and chemical properties of the material to a great extent. Therefore, it is of great importance to the study of the end group atom of the material. Especially for the appearance of spherical aberration correction electron microscopy, the oxygen atom in metal oxide has been realized by transmission electron microscope directly. But the need to "observe" the oxygen atom needs a high magnification. At this time the radiation dose per unit area is very high and the damage to the sample is very serious, so the spherical aberration correction is used. Electron microscopy can only study very stable materials irradiated by electron beams, and most of the MOFs materials are very unstable under the action of electron beams. Therefore, it is difficult to use the spherical aberration correction electron microscopy to direct "observation". And the literature of the end group of MOFs materials by other electron microscopy methods is rarely reported, so the use of EDT Technology It is of great significance to study and determine the position of the JUC-32 terminal radical oxygen atom. In the fifth chapter, we have successfully analyzed the structural skeleton of a new type of phosphorus aluminum molecular sieve PST-6 using EDT technology, and compared the results with the results of the HRTEM photo analysis. The layer reconstruction technique can be widely used in the structural analysis of complex molecular sieves. In this paper, the application of traditional transmission electron microscopy in the study of material structure is discussed. The comparison of EDT technology to traditional structural analytical methods is made, and the feasibility of using EDT technology in the structural analysis of MOF materials is discussed. Finally, we benefit The framework of the unknown structure of phosphorus and aluminum molecular sieve PST-6 is successfully analyzed by EDT technology. Our research work has made a positive contribution to the further improvement and development of EDT technology. It also has a great promoting effect on the application and popularization of electron microscopy in the study of material structure.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB303

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