过渡金属氧簇材料的制备及其催化性能研究

发布时间：2018-03-17 05:33

本文选题：多金属氧酸盐　切入点：杂多蓝　出处：《扬州大学》2017年硕士论文　论文类型：学位论文

【摘要】：多金属氧酸盐是一类金属氧簇无机化合物,其结构稳定,热稳定性好,反应条件温和,既具有酸催化性能,又具有氧化还原催化性能,且催化的反应活性高,选择性好,是高效的环境友好型的绿色双功能催化剂。它无论是在均相还是多相催化反应中都拥有良好的催化活性,在很多领域有着广泛的应用。本文中我们分别从三个不同的方面探究多金属氧酸盐的催化性能,主要研究内容和结论如下:1.以 Well-Dawson 磷钨酸 H6[P2W18062]·24H20(oxi-[P2W18062]6-)作为母体采用化学还原的方法制备两种杂多蓝晶体:H10[P2W18O62]·27H2O(red-[P2W18O62]10-),H7[P2W18062]·12H2O(int-[P2W18062]7-)。通过单晶X-射线衍射、红外光谱、拉曼光谱、紫外光谱、循环伏安、热重分析、光电子能谱等对其结构进行基础表征。将杂多蓝晶体red-[P2W18062]10-负载到氧化石墨烯表面,利用red-[P2W18062]10-的还原性还原氧化石墨烯,同时硝酸银被还原成银纳米粒子负载到氧化石墨烯表面,制备出rGO@P2W18@Ag复合材料催化剂,这一过程中red-[P2W18062]10-失去电子变成oxi-[P2W18062]6-。同时探究复合材料催化剂对硼氢化钠还原对硝基苯酚的催化性能以及催化机理,结果表明oxi-[P2W18062]6-作为“电子海绵”储存电子协同银纳米粒子的催化作用在50秒内使对硝基苯酚被硼氢化钠还原成对氨基苯酚。2.我们采用一步法将Zn2+作为一种低成本和环保的控制剂来改性前驱体[B-α-BiW9033]9-。在硫酸锌存在下,由前驱体Na9[BiW9O33]·16H20制备新型二维聚合物Zn/Bi-多金属氧酸盐Na2Zn4H5[Zn3Bi(B-α-ZnW9034)2]52H20。我们对制备成功的Zn/Bi夹心型钨酸盐分别进行了 X-射线分析,FT-IR、Raman、UV、热重分析(TG)、CV等一系列表征证明其结构和性质。以过氧化氢氧化环已醇生成环已酮为研究对象,作为均相催化剂研究其催化活性及催化活性位点。3.我们以TEOS作为前驱体对Fe3O4纳米粒子的表面进行改性,制备了 Fe3O4@Si02磁性颗粒。通过阴阳离子的静电作用将拥有良好磁学性质的磁性纳米粒子和杂多酸相结合制备出负载型的磁性杂多酸催化剂。同样的以过氧化氢氧化环已醇生成环已酮为研究对象,在外加磁场的环境中能够实现催化剂简单高效的分离,解决了杂多酸在催化过程中易溶解于反应体系,较难实现催化剂的回收和再利用问题。
[Abstract]:Polyoxometalates are a kind of inorganic compounds with stable structure, good thermal stability and mild reaction conditions. They not only have acid catalytic activity, but also have redox catalytic activity, and the catalytic activity is high and the selectivity is good. It is a highly efficient environment-friendly green bifunctional catalyst. It has good catalytic activity in both homogeneous and heterogeneous catalytic reactions. In this paper, we explore the catalytic properties of polyoxometalates from three different aspects. The main contents and conclusions are as follows: 1. Two kinds of heteropoly blue crystals: H10 [P2W18O62] 路27H2O red- [P2W18O62] 10-H7 [P2W18062] 路12 H _ 2O _ int- [P2W18062] 7-H7 were prepared by chemical reduction method using Well-Dawson phosphotungstate H6 [P2W18062] 路24H20oxi- [P2W18062] 6-. by single crystal X-ray diffraction, infrared spectrum, Raman spectrum, UV spectrum, cyclic voltammetry, The structure was characterized by thermogravimetric analysis and photoelectron spectroscopy. The heteropoly blue crystal red- [P2W18062] 10- was loaded on the surface of graphene oxide, and the reductive reductive graphene was obtained by red- [P2W18062] 10-. At the same time silver nitrate was reduced to silver nanoparticles supported on the surface of graphene oxide to prepare rGO@P2W18@Ag composite catalyst. In this process, red- [P2W18062] 10- lost electrons became oxi- [P2W18062] 6-.At the same time, the catalytic properties and mechanism of composite catalyst for reduction of p-nitrophenol by sodium borohydride were investigated. The results show that oxi- [P2W18062] 6- acts as a "electron sponge" to store electrons in the presence of silver nanoparticles to reduce p-nitrophenol to p-aminophenol by sodium borohydride within 50 seconds. We used one-step method to treat Zn2 as a kind of low cost and low cost, and the results show that oxi- [P2W18062] 6- can reduce p-nitrophenol to p-aminophenol by sodium borohydride within 50 seconds. Environmental protection control agent to modify precursor [B- 伪 -BiW9033] 9-. in the presence of zinc sulfate, A novel two-dimensional polymer Na2Zn4H5 [Zn3BiB- 伪 -ZnW9034K2] 52H20was prepared from the precursor Na9 [BiW9O33] 路16H20. The structure and properties of the successfully prepared Zn/Bi sandwich tungstate were characterized by X-ray analysis and thermogravimetric analysis. Hydrogen peroxide oxidation of cyclohexanol to cyclohexanone was studied. As homogeneous catalyst, the catalytic activity and catalytic activity site of Fe3O4 nanoparticles were studied. 3. We used TEOS as precursor to modify the surface of Fe3O4 nanoparticles. Fe3O4@Si02 magnetic particles were prepared. Magnetic nanoparticles with good magnetic properties were combined with heteropoly acids by electrostatic interaction of anion and anion to prepare supported magnetic heteropoly acid catalyst. Similarly, hydrogen peroxide was used to oxidize the catalyst. Cyclohexanone was produced by cyclohexanol. In the environment of external magnetic field, the catalyst can be separated simply and efficiently, which solves the problem that heteropoly acid is easily dissolved in the reaction system in the process of catalysis, and it is difficult to realize the recovery and reuse of the catalyst.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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