负载型钯催化剂在Heck反应中的应用

比较了Heck反应中传统的催化剂在分离和回收方面的问题,介绍了负载型钯催化剂的优点,归纳了负载型钯催化剂按固相载体高分子、二氧化硅、活性炭、分子筛和金属氧化物等进行的分类,总结了各类负载型钯催化剂在Heck反应中的应用。认为目前还必须克服负载型催化剂易流失、成本高等问题。     

高分散负载型钯基催化剂的制备及催化加氢研究进展

贵金属钯具有良好的催化性能和稳定性,是理想的加氢反应催化剂。贵金属钯成本较高,这一定程度上限制了其在大规模生产中的应用。为了提高贵金属钯催化加氢反应效率和催化稳定性,有效降低贵金属钯的单位消耗,开发高分散负载型钯基催化剂是有效途径之一。综述了近年来高分散负载型钯基催化剂的制备方法及其在加氢反应中的催化行为。     

硫化钯催化剂的合成及其应用研究进展

在非均相催化反应中,硫化钯作为催化剂的应用具有重要意义。综述了负载型和非负载型硫化钯的合成方法,重点讨论在气相或液相条件下前驱体、反应温度、反应气氛及载体对合成硫化钯晶相的影响,初步分析硫化钯在催化领域中的应用及未来的发展趋势。     

可回收钯催化剂在Suzuki反应中的最新研究进展

钯催化的卤代芳烃和芳基硼酸的Suzuki偶联反应,是有机合成中形成碳-碳键最为有效的方法之一,但均相钯催化剂的回收和利用一直是个难题。负载型催化剂的出现,为实现贵金属钯与产物的高效分离和回收提供了可能。本文对负载钯催化剂的载体进行分类讨论,对近年来可回收钯催化剂在Suzuki偶联反应中的应用研究进行了简要阐述,并对其发展前景做了展望。     

高分子负载钯催化Suzuki反应的研究进展

高分子负载钯催化剂与均相催化剂相比易于分离、可重复使用,同时大多数高分子负载钯催化剂保留了较高的催化活性。高分子负载钯催化剂已成为Suzuki反应催化剂的研究热点之一。本文综述了近年来高分子负载钯络合物及钯纳米催化剂在Suzuki反应中的研究进展。     

负载型钯酞菁催化剂上CCl2F2的选择性加氢脱氯反应

负载型钯酞菁能有效催化CCl₂F₂的选择性加氢脱氯反应,在氟化物为载体的钯酞菁催化剂上,CCl₂F₂转化成CH₂F₂的选择性可达75％以上.对比研究表明,负载型钯酞菁催化剂上CCl₂F₂选择性加氢脱氯的稳态催化活性要高于普通的负载型金属钯催化剂.在钯活性中心引入环状酞菁配体能有效提高催化剂在高腐蚀性反应条件下的稳定性.红外光谱、X射线衍射和紫外-可见光谱表征揭示了负载型钯酞菁催化剂具有良好催化活性和催化稳定性的可能原因.     

负载型钯催化剂上甲烷催化燃烧的研究进展

概述了负载型钯催化剂对甲烷完全氧化的催化机理,以及钯催化剂在甲烷催化燃烧中的性能特点。     

离子液体及负载型钯催化剂在加氢反应中的研究进展

离子液体是在小于100℃条件下呈液态的盐,易溶解,热稳定性、催化性强,被誉为绿色溶剂与催化体系,现已得到了广泛应用。负载型钯催化剂具有表面积大,金属分散性,热稳定性强的特点,不过价格昂贵且目标产物选择性不高、反应机理不稳定。对此,就离子液体与负载型钯催化剂在加氢反应中的应用展开分析。     

负载型Pd催化剂

介绍了制备负载型钯催化剂的几种方法，以及它在反应中的应用。阐述了几种催化剂载体的优点，最后对这种催化剂的前提提出展望。     

用于偶联反应的载钯催化剂制备研究进展

偶联反应一般是指C-C偶联或C-N等的偶联,像Still反应、Suzuki反应和Buchwald反应等,它们中的反应催化剂一直以来是使用均相钯配体催化剂,对于负载型钯催化剂的使用较少。将载钯催化剂用于偶联反应是有机合成反应中均相反应多相化的典型例子,且在工业化生产中较均相催化剂更具有优势。从负载钯催化剂的制备、介孔碳的制备及反应驱动力三个方面介绍了偶联反应的近期进展,并对未来发展进行了展望。     

Suzuki Coupling Reactions in Pure Water Catalyzed by Supported Palladium – Relevance of the Surface Polarity of the Support

Heterogeneous (supported) palladium catalysts like palladium on carbon and a variety of metal oxides have been shown to be highly active for Suzuki coupling reactions in neat water under mild reaction conditions (T=65 °C). It has been demonstrated for the first time that hydrophobic effects of the catalyst surface play an important role for the catalyst activity in water. Catalysts possessing hydrophobic surfaces (e.g., palladium on carbon) show higher activity for Suzuki coupling reactions in water than their hydrophilic counterparts (palladium on metal oxides). Tuning of the surface polarity of metal oxide supports (by silylation) results in higher activity under these conditions. Stronger alkaline conditions (three‐fold excess of base) compensate the effect of hydrophobic supports and result in high activity of the catalysts also with hydrophilic supports. The addition of tetrabutylammonium bromide to generate, activate and stabilize the catalytic species (dissolved palladium complexes) is necessary for the conversion of more demanding substrates. The reaction is considered to be homogeneous taking place near the catalyst surface inside a droplet or layer of the reactant.     

多相贵金属催化剂对芳香化合物催化加氢研究进展

综述了近年来多相贵金属催化剂对芳香化合物加氢的研究；揭示了负载型铂、钯、钌、铑以及二元金属催化剂各自在加氢反应中的特点，以及载体、助催化剂对其活性和选择性的重要作用；同时介绍了TCSM和Raney型贵金属催化剂的概况。     

碳材料负载钯催化Suzuki偶联反应的研究进展

过渡金属钯催化的Suzuki偶联反应是有机合成中的重要反应之一。固载钯催化剂具有制备简单、易分离、廉价等优点;碳材料具有大的比表面积、良好的孔结构、性质稳定、容易回收再生等优点,是理想的钯催化剂载体。综述了不同碳材料负载钯催化剂催化Suzuki偶联反应的研究进展。     

天然气催化燃烧催化剂的研究（Ⅰ）

介绍了天然气催化燃烧负载型贵金属催化剂的研究现状。在天然气催化燃烧催化剂中,贵金属催化剂尤其是Pd基催化剂得到了深入的研究。载体的选择和催化剂的化学修饰对催化剂的活性和稳定性具有至关重要的作用,催化剂前驱体的选择亦对催化燃烧活性有影响。在Pd基催化剂中,PdO是甲烷催化燃烧的活性中心,PdO─Pd─PdO的氧化还原过程对Pd基催化剂的活性起着决定性的作用。     

无配体负载钯催化Suzuki偶联反应的研究进展

金属钯催化的Suzuki偶联反应是碳一碳偶联反应中的最重要的反应之一。传统的均相催化体系具有很多的不足,如产物与催化剂不易分离、原料价格昂贵、催化剂不能重复使用等,而使用无配体负载钯的催化剂可有效地解决上述问题。综述了近些年来无配体材料负载钯催化Suzuki偶联反应的研究进展,载体包括碳材料、多孔分子筛、水滑石、高分子材料、金属氧化物、硅藻土、纤维素、磷灰石和氟硅胶等。     

负载钯催化Suzuki偶联反应的研究进展

过渡金属钯催化C-C偶联反应在有机合成中具有重要地位,负载型钯催化剂具有分离简便、可重复使用等优点,引起了人们的关注。综述了不同载体催化剂催化Suzuki偶联反应的研究进展。     

Palladium- catalyzed hydrogenation of soybean oil

The hydrogenation of soybean oil has been studied using charcoal-supported palladium catalysts at hydrogen pressures between ambient and 70 psig and at temperatures between 80 C and 160 C in three types of stirred reactor. The catalysts employed were 1-10% w/w Pd supported on charcoal and represented differing metal placement on the support. The structure of the catalysts was confirmed by metal surface area measurements, transmission electron microscopy (TEM) and electron spectroscopy for chemical analysis (ESCA). Comparative studies also were carried out under similar conditions using samples of commercial nickel catalysts. Palladium catalysts with the metal placed on the exterior of the charcoal support were the most active and selective at ambient pressure, and although palladium catalysts with metal placed within the charcoal pore system became the most active at higher hydrogen pressures, only the former type of catalyst retained high selec-tivity over the whole temperature and pressure range. Palladium catalysts gave rise to moretrans- acids than nickel, particularly under conditions normally em-ployed with the latter, but if diffusion limitation was avoided, especially at lower temperatures, palladium gave lower quantities oftrans- acid than nickel. In addition, the selectivity of a well designed palladium catalyst was superior to that of nickel and its activity was 15-20 times greater. It is concluded that if palladium is deposited on the exterior of the charcoal so that it is accessible to the triglyceride molecules, then its selectivity and activity is superior to that of nickel, even at low temperatures, at which nickel is inactive. This underlines the importance of choosing the correct preparative route to give optimum metal placement, and it is suggested that when previous studies have indicated that palladium is unselective for fat hardening, it is likely that the metal was not dispersed on the exterior surface of the support. Furthermore, whereas nickel is best used under diffusion-controlled conditions because its selectivity is better in the latter situation palladium should be used under diffusion-free conditions, which implies that very careful attention should be paid to the reactor design.     

Systematic Study of the Oxidation of Methane Using Supported Gold Palladium Nanoparticles Under Mild Aqueous Conditions

The oxidation of methane using hydrogen peroxide has been studied using supported gold palladium catalysts prepared using the incipient wetness technique. The effect of reaction conditions and catalyst parameters has been investigated. The supported gold palladium nanoparticles produce methyl hydroperoxide as the primary reaction product which is subsequently converted to methanol with high selectivity, ca. 40–70 %. The selectivity to methanol is influenced by the oxidation state the palladium component of the catalyst. In contrast to homogeneous gold and palladium catalysts the heterogeneous gold palladium nanoalloys are reusable and affords high oxygenate selectivity (ca. 90 %).     

2-乙基蒽醌加氢催化剂的研究进展

高活性和高选择性的催化剂是解决蒽醌法生产过氧化氢过程中瓶颈问题的根本途径。综述了近年来高活性和高选择性镍、钯、铂系催化剂制备的进展。指出负载型镍系非晶态合金和钯系高分子催化剂应是今后蒽醌加氢催化剂研究的方向。     

Single-phase gold/palladium catalyst: The nature of synergistic effect

The liquid phase oxidation of glycerol with oxygen has been studied using mono and bimetallic catalysts based on Au and Pd metals supported on activated carbon, in order to study the effect of the metal on the distribution of the products and on activity of catalysts. It was found that by using bimetallic catalysts (Au–Pd) a strong synergistic effect was shown. By using a preformed nucleating centre we were able to obtain a single alloyed phase, which allowed us to address the synergistic effect to the presence of alloyed Au/Pd. The advantage of using this latter catalyst lies not only in the high activity but also in a prolonged catalyst life. Although a partial leaching of palladium and assembling of the particles have been revealed by ICP and HRTEM respectively, activity after 10 re-cycles decreased less than expected (about 10%).