阴离子开放骨架磷酸铝合成中的结构导向效应

发布时间：2018-08-17 16:30

【摘要】：开放骨架磷酸铝由于具有独特的结构和组成,在催化、吸附、分离、离子交换和主客体化学研究等方面有着重要的应用前景。在这类材料的合成中,结构导向剂起了至关重要的作用。在合成中如果不使用结构导向剂,则不能得到相应的开放骨架结构,结构导向剂所起的作用被称为结构导向效应。多种合成参数都可以影响结构导向效应,包括凝胶组成、结构导向剂自身的物理和化学性质、晶化温度及晶化时间等。然而,人们仍然不清楚这些因素如何影响或者决定结构导向效应以及结构导向效应的本质。本论文以阴离子开放骨架磷酸铝为研究对象,通过只改变一个合成参数,研究合成参数的改变对合成产物的影响。在本论文中,我们通过改变结构导向剂的种类以及晶化温度,研究了相应合成体系的晶化过程,希望能对结构导向效应的本质和来源有所认识。主要从以下两个方面开展了研究:1.以1,4-丁二胺、2-甲基-1,5-戊二胺和1,6-己二胺为结构导向剂,相应地合成出了拓扑结构相同且具有12×8交叉的三维孔道的Al PO-BDA、Al PO-MPMD、Al PO-HDA三种磷酸铝化合物。晶化过程的XRD研究表明含有1,4-丁二胺的初始混合物晶化最快,而含有1,6-已二胺的初始混合物晶化最慢。晶化过程的NMR研究表明在三种化合物的形成过程中,Al和P经历了不同的演化过程。另外,通过~(31)P{~(27)Al}PT-J-HMQC NMR确认了在晶化过程中特定Al和P位点的演化历程。通过分析三种化合物的可能晶化起点(核心单元),我们发现在Al PO-BDA、Al PO-MPMD和Al PO-HDA晶化过程中,由于三种有机胺的结构不同,导致其所导向的核心单元也不相同,即晶化起点不同,但随着晶化的进行,最终却生成了相同的拓扑结构。因此,在开放骨架Al PO-HDA中,有机胺起到了结构导向效应,更确切地说,为拓扑结构导向效应。2.研究了摩尔组成为Al_2O_3:1.8 P_2O_5:2.4 R:125 H_2O(R=1,3-丙二胺或1,4-丁二胺)的初始混合物在160°C和190°C的晶化过程。在160°C,1,3-丙二胺和1,4-丁二胺分别导向了两个拓扑结构完全不同的层状磷酸铝Ui O-18和开放骨架磷酸铝APDAB200,显示增加一个亚甲基对1,3-丙二胺的结构导向效应产生了显著的影响;而在190°C,1,3-丙二胺和1,4-丁二胺则分别导向了具有相同拓扑结构的开放骨架磷酸铝Ui O-26和APDAB200,显示增加一个亚甲基对1,3-丙二胺的结构导向效应没有产生影响。因此增加一个亚甲基对1,3-丙二胺分子的结构导向效应的影响存在着温度依赖性。在160°C,向1,3-丙二胺增加一个亚甲基并未明显改变液相的p H以及液相中的P浓度。虽然在初始混合物中向1,3-丙二胺增加一个亚甲基并未对磷酸铝小结构单元的种类和分布产生显著的影响,却导致了不同的核心单元,得到了不同的长程有序结构。在190°C,同样向1,3-丙二胺增加一个亚甲基也并未显著改变液相中的P浓度,却显著改变了反应阶段的液相的p H。尽管如此,1,3-丙二胺和1,4-丁二胺却导向了相似的核心单元,最终晶化出了具有相同拓扑结构的长程有序结构。
[Abstract]:Owing to its unique structure and composition, open-skeleton aluminium phosphate has important application prospects in catalysis, adsorption, separation, ion exchange and host-guest chemistry. In the synthesis of such materials, structure-directing agents play an important role. Without the use of structure-directing agents, the corresponding openness can not be achieved. A variety of synthetic parameters can influence the structure-directing effect, including gel composition, physical and chemical properties of the structure-directing agent itself, crystallization temperature and crystallization time. However, it is still unclear how these factors affect or determine the structure-directing effect. In this paper, the effect of synthesis parameters on the product was studied by changing only one synthesis parameter. In this paper, we studied the crystallization of the corresponding synthesis system by changing the type of structure-directing agent and the crystallization temperature. The following two aspects have been studied: 1. Al PO-BDA, Al PO-MPMD and Al PO-HDA with the same topological structure and 12 *8 cross-section were synthesized with 1,4-butanediamine, 2-methyl-1,5-pentadiemine and 1,6-hexanediamine as structure-directing agents. Aluminum phosphate compounds. XRD studies of the crystallization process show that the initial mixtures containing 1,4-butanediamine crystallize fastest, while the initial mixtures containing 1,6-hexanediamine crystallize slowest. NMR studies of the crystallization process show that Al and P undergo different evolutionary processes during the formation of the three compounds. In addition, through ~ (31) P {~ (27) Al} PT J-HMQC NMR The evolution of specific Al and P sites during crystallization was confirmed. By analyzing the possible crystallization starting points (core units) of the three compounds, we found that in the crystallization process of Al PO-BDA, Al PO-MPMD and Al PO-HDA, the orientation of the core units was different because of the different structures of the three organic amines, i.e. the crystallization starting points were different, but with the change of crystallization starting points. Thus, in the open skeleton Al PO-HDA, organic amines play a structure-directed role, more specifically, for the topological structure-directed effect. 2. The initial mixtures of Al_2O_3:1.8 P_2O_5:2.4 R:125 H_2O (R=1,3-propanediamine or 1,4-butanediamine) at 160 degrees C and 19 degrees C were studied. Crystallization at 0 degree C. Two layered aluminium phosphate Ui O-18 and open skeleton aluminium phosphate APDAB200 with completely different topologies were directed at 160 degree C, 1,3-propanediamine and 1,4-butanediamine, respectively, indicating that the addition of a methylene has a significant effect on the structure-directing effect of 1,3-propanediamine, while at 190 degree C, 1,3-propanediamine and 1,4-butanediamine respectively. The results show that the addition of a methylene has no effect on the structure-directing effect of 1,3-propanediamine. Therefore, the effect of adding a methylene on the structure-directing effect of 1,3-propanediamine molecule is temperature-dependent. A methylene does not change the concentration of P H in the liquid phase and P in the liquid phase. Although the addition of a methylene to 1,3-propanediamine in the initial mixture has no significant effect on the type and distribution of small structural units of aluminum phosphate, it results in different core units and different long-range ordered structures. However, 1,3-propanediamide and 1,4-butanediamide led to similar core units and eventually crystallized long-range ordered structures with the same topological structure.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O614.31

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