负载不同形貌钯纳米粒子催化剂的制备及催化Suzuki偶联反应的研究

发布时间：2018-06-08 01:54

本文选题：钯 + 纳米粒子　；参考：《中南民族大学》2015年硕士论文

【摘要】：钯负载型催化剂用于催化碳-碳键之间的偶联反应,此反应是现代合成反应中重要的反应之一,在各种化合物的合成中得到广泛应用。其中类似的偶联反应包括Stille偶联反应、Heck偶联反应和Suzuki偶联反应等。Suzuki偶联反应已成为制备联苯类化合物最直接有效的方法。此反应是在有机溶剂中,由各种配体钯进行催化反应。Suzuki偶联反应在工业生产中有很多优点,比如操作简单,原料广泛易得,产量高。但是有许多文献报道钯高效催化碳-碳偶联反应具有单一的合成方法,原料较贵,反应后产物很难回收再利用。近年来的热点是研究活性高、选择性高的钯催化剂在石油化工中的应用。Suzuki反应目前主要应用到医药生产、功能高分子材料及液晶材料的合成中。大多数报道的 Suzuki反应都是用芳基溴化物、芳基碘化物或者是芳基氯化物进行合成反应的。现阶段,大部分催化剂都是将钯负载到配体上合成均相催化剂,虽然均相催化剂催化的效果好,但是反应之后很难进行回收再利用,从而浪费金属钯,污染环境特别是水污染,使得成本增加。所以设计合成出可回收可再利用的负载型钯催化剂,是近几年Suzuki偶联反应的主要研究方向。纳米粒子的尺寸、组成及结晶度、分散性及形貌等会影响自身的催化活性和选择性能。形貌的不同是与顶角和边上的原子比例不同有关,其导致了钯纳米粒子的选择性能和催化性能的不同,从而这引起了人们的极大关注。催化的研究显示,金属纳米粒子的活性与形状和粒径大小有关。具有不同形貌的钯催化剂,对催化C-C偶联的反应的选择性和活性不同。载体类型因其结构组成和性质的不同对催化剂性能的也有明显的影响。就其而言,载体具有相连通的孔结构,有利于传质,高比表面积和孔隙率则提供足够的负载量和传质面积,通过活化引入功能基团可与金属形成强化学键。本论文制备不同形貌的钯纳米粒子,并用二氧化钛负载,对钯纳米粒子和负载钯催化剂其进行TEM、XRD、XPS表征。催化间溴甲苯与苯硼酸的Suzuki偶联反应,通过产率的变化确定其最佳温度、时间。以PVP为保护剂,氯化钯为钯源,以NaBH4为还原剂,苯甲醇为溶剂在室温下反应5 min制得绒球状Pd纳米粒子。改变温度与时间,同样的保护剂和前驱体,以甲酸铵为还原剂,二次蒸馏水作溶剂获得类球形钯纳米粒子。同样以三缩四乙二醇为还原剂,乙醇为溶剂获得二十面体钯纳米粒子。并对钯纳米粒子进行TEM、XRD、XPS表征,观察其形态、计算粒径大小。绒球状纳米粒子粒径最大,为自组装体。在所制备的不同形貌的钯溶液中加入二氧化钛金属氧化物,在室温下搅拌24 h,使其能够充分吸附钯纳米粒子。设置温度25°C,真空旋干,冷却至室温,真空干燥。并对负载不同形貌的钯进行TEM、XRD表征,观察到在二氧化钛载体上均负载了钯纳米粒子,并观察到二氧化钛载体上的钯纳米粒子形貌由于在旋干过程中受温度和溶剂去除的影响使得形貌发生了一些改变,都趋于各向同性。并用电感耦合等离子体(ICP)发射光谱法来测试催化剂中的钯的含量,其中绒球状钯纳米粒子中的含量最多。以碳酸钾为碱试剂,负载不同形貌的钯纳米粒子作为催化剂,以DMF水溶液(DMF:H2O=1:1)为溶剂在一定温度下催化间溴甲苯与苯硼酸反应一定时间。设置在不同温度的催化反应,通过产率来确定其最佳温度。同样方法设置不同反应时间确定合适条件。其负载二十面体钯纳米粒子催化剂催化反应的最佳温度和时间分别为110°C、2 h。
[Abstract]:Palladium supported catalysts are used to catalyze the coupling reaction between carbon and carbon bonds. This reaction is one of the most important reactions in modern synthetic reactions and is widely used in the synthesis of various compounds. The similar coupling reactions include Stille coupling reaction, Heck coupling reaction and Suzuki coupling reaction, which have become a preparation combination. The most direct and effective method of benzene compounds in organic solvents, the catalytic reaction of various ligands palladium in the catalytic reaction.Suzuki coupling reaction has many advantages in industrial production, such as simple operation, widely available raw materials and high yield. But there are many reports that palladium has a single synthesis method for high efficiency carbon carbon coupling reaction. The raw materials are more expensive and the reaction products are difficult to recycle and reuse. In recent years, the hot spot is to study the application of high active and selective palladium catalysts in the petrochemical industry. The.Suzuki reaction is mainly used in the synthesis of pharmaceutical production, functional polymer materials and liquid crystal materials. Most of the Suzuki reactions in the reports are aryl bromides and aryl groups. Iodide or aryl chloride is synthesized. At the present stage, most of the catalysts are supported on the ligand to synthesize the homogeneous catalyst. Although all the catalysts have good catalytic effect, it is difficult to recycle and reuse them after the reaction, so that the metal palladium is wasted and the environment especially water pollution is polluted, so the cost is increased. The design and synthesis of recoverable and reusable palladium catalyst is the main research direction of Suzuki coupling reaction in recent years. The size, composition and crystallinity of the nanoparticles, dispersion and morphology will affect the catalytic activity and selective properties of the nanoparticles. The difference of the morphology is related to the atomic ratio at the top angle and on the edge. The selection and catalytic properties of palladium nanoparticles are different, which have aroused great concern. The catalytic study shows that the activity of the metal nanoparticles is related to the shape and size of the particles. The palladium catalysts with different morphologies have different selectivity and activity for the reaction of C-C coupling. The difference in properties also has an obvious effect on the performance of the catalyst. In its case, the carrier has a connected pore structure, which is beneficial to mass transfer. The high specific surface area and porosity provide enough load and mass transfer area, and the metal can form a strengthening bond with the metal by activating the functional group. The palladium nanoparticles with different morphologies are prepared in this paper. The palladium nanoparticles and the supported palladium catalysts were characterized by TEM, XRD, and XPS, which catalyze the Suzuki coupling reaction between bromine toluene and benzyl boric acid. The optimum temperature and time were determined by the change of yield, with PVP as the protectant, palladium chloride as the palladium source, NaBH4 as the reductant, and benzyl alcohol as the solvent at room temperature for 5 min Ball like Pd nanoparticles. Change the temperature and time, the same protectant and precursor, use ammonium formate as reducing agent, two distilled water as solvent to obtain spherical palladium nanoparticles. The same as three shrinkage four glycol as reducing agent and ethanol as solvent to obtain twenty surface palladium nanoparticles. And the palladium nanoparticles were characterized by TEM, XRD, and XPS. The particle size of the particle size is the largest. The particle size of the ball like nanoparticles is the largest, which is the self assembly. The titanium dioxide metal oxide is added to the palladium solution with different morphologies. At room temperature, 24 h is stirred, and the palladium nanoparticles can be fully adsorbed. The temperature is 25 degree C, vacuum drying, cooling to room temperature, vacuum drying. The palladium in the appearance was characterized by TEM and XRD. It was observed that palladium nanoparticles were loaded on the titanium dioxide carrier, and the morphology of the palladium nanoparticles on the titanium dioxide carrier was observed to be isotropic because of the influence of temperature and solvent removal during the spin drying process, and the morphology of the palladium nanoparticles tended to be isotropic and was induced by inductively coupled plasma (ICP). The content of palladium in the catalyst is measured by the method of emission spectrometry, in which the content of palladium nanoparticles is the most. With the potassium carbonate as the alkali reagent, the palladium nanoparticles with different morphologies are supported and the DMF aqueous solution (DMF:H2O=1:1) is used as the solvent at a certain temperature to catalyze the reaction between bromo methylene and phthalic acid at a certain temperature. The optimum temperature of the catalytic reaction is determined by the yield. The same method is used to determine the appropriate conditions. The optimum temperature and time for the catalytic reaction of the supported twenty surface palladium nanoparticles are 110 C, 2 h., respectively.
【学位授予单位】：中南民族大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TB383.1

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