铜基纳米催化剂的制备及在Rochow反应中的催化性能研究

发布时间：2018-03-09 22:32

本文选题：Rochow反应　切入点：M2　出处：《中国科学院大学(中国科学院过程工程研究所)》2017年博士论文　论文类型：学位论文

【摘要】：甲基氯硅烷是最重要也是用量最大的有机硅单体,是整个有机硅工业的基础和支柱。工业生产中,其主要是采用直接法(即Rochow反应)来合成。采用固态的硅粉(Si)在铜基催化作用下与气态的一氯甲烷(MeC1)接触反应,目标产物为二甲基二氯硅烷(M2,Me2SiCl2)。铜基催化剂是该反应的经典催化剂,然而,目前的研究主要集中于微米尺度铜催化剂的开发,且催化性能即M2选择性和Si转化率仍然有待进一步提高。因此,开发新型高效催化体系及探索其催化机理仍然是一项具有理论和实际应用价值的研究课题。基于此,本论文开展了以下研究工作:(1)在采用液相还原法制备金属Cu纳米线基础上,通过调控温度和时间氧化制备了一系列含有不同Cu、Cu_2O和CuO组分的纳米线和纳米管材料,并将其用于Rochow反应中。相较于一元和二元组分催化剂,三元Cu-Cu_2O-CuO多壁核壳纳米线表现出更加优异的M2选择性和Si转化率。这归因于三元层状异质结构及不同组元间的协同作用。(2)采用六面体、八面体和菱形十二面体三种Cu_2O纳米晶作为模型催化体系研究了晶面对Rochow反应催化性能的影响。实验结果表明暴露{100}晶面的Cu_2O六面体M2的催化选择性最优,这归因于其表面结构对MeC1的解离吸附最强。在此基础上将ZnO纳米粒子负载在不同晶面的Cu_2O纳米晶上得到5%ZnO/Cu_2O异质结纳米晶,催化性能显示负载于六面体Cu_2O的异质结纳米晶表现出更加优异的M2选择性和Si转化率,证实其形成的P-N异质结构对催化性能具有促进作用。(3)采用硬模板法制备了一种多孔CuO-ZnO纳米复合物,并将其回用于Rochow反应中。本方法是以回收的有机硅单体合成反应中的废触体为原料。质量占比67wt%的炭黑制备的CZ80/20复合物与商业催化剂的催化性能基本相当,这得益于二元组分比例及二者的协同作用。本方法对循环工艺的发展进行了有益的探索。
[Abstract]:Methyl chlorosilane is the most important and the largest amount of silicone monomer. It is the foundation and pillar of the whole organosilicon industry. It is mainly synthesized by direct method (i.e. Rochow reaction). The solid silica fume is used to react with gaseous methylene chloride (MeC1) under the catalysis of copper. The target product is dimethyl dichlorosilane M _ 2N _ 2M _ 2i _ 2SiCl _ 2H _ 2O. Cu-based catalyst is the classic catalyst for this reaction. However, the current research is mainly focused on the development of micron scale copper catalyst. The selectivity of M2 and the conversion of Si still need to be further improved. Therefore, it is still a research topic with theoretical and practical application value to develop a new type of highly efficient catalytic system and explore its catalytic mechanism. In this paper, the following research work was carried out: (1) A series of nanowires and nanotube materials containing different Cu 2O and CuO components were prepared by controlling the temperature and time of oxidation on the basis of liquid phase reduction method to prepare Cu nanowires. And used in Rochow reaction. Compared with monolithic and binary catalyst, Ternary Cu-Cu_2O-CuO multiwalled core-shell nanowires exhibit better M2 selectivity and Si conversion due to ternary layered heterostructures and synergistic effects between different components. The effects of octahedron and rhombohedral 12 Cu_2O nanocrystals on the catalytic performance of Cu_2O hexahedron M2 exposed to {100} plane were investigated as model catalysts. The results showed that the selectivity of Cu_2O hexahedron M2 exposed to {100} faces was optimal. This is attributed to the strongest dissociation and adsorption of MeC1 on its surface structure. On this basis, 5ZnO / Cu _ 2O heterojunction nanocrystals were obtained by loading ZnO nanoparticles onto Cu_2O nanocrystals with different faces. The catalytic properties showed that the heterojunction nanocrystals supported on hexahedron Cu_2O exhibited better M2 selectivity and Si conversion. It is confirmed that the P-N heterostructure has a catalytic effect on the catalytic performance. (3) A porous CuO-ZnO nanocomposite was prepared by hard template method. In this method, the waste thixodes in the synthesis of organic silicon monomers were used as raw materials. The catalytic properties of the CZ80/20 complexes prepared from carbon black with 67 wt% mass ratio were basically equal to those of commercial catalysts. This method is beneficial to the development of recycling process.
【学位授予单位】：中国科学院大学(中国科学院过程工程研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O643.36

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