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。     

加氢反应催化剂中银组分功能综述

贵金属中的廉价金属Ag以其独特的物理化学性质在催化领域发挥了重要作用。在加氢反应中,Ag自身是一种性能优异的催化剂加氢活性组分,其显著特性是对反应物分子中含有多种加氢活性位点或者从炔烃到烯烃的部分加氢反应,能够控制加氢程度,实现选择性加氢。Ag作为催化剂助剂组分,能够提高Pt、Au和Ni催化剂选择性加氢性能、催化活性或稳定性。此外,Ag作为助剂能够降低Cu、Ni催化剂的还原温度,甚至能免除催化剂预还原步骤,还能够抑制催化剂中金属组分在酸催化体系中析出。综述单金属Ag催化剂和含Ag多金属催化剂在加氢反应中的研究进展,重点阐述Ag作为主组分或者助剂在催化剂中发挥的特殊功能。     

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。     

Recent advances on metal-free graphene-based catalysts for the production of industrial chemicals

With the development of carbon catalysts, graphene-based metal-free catalysts have drawn increasing attention in both scientific research and in industrial chemical production processes. In recent years, the catalytic activities of metal-free catalysts have significantly improved and they have become promising alternatives to traditional metal-based catalysts. The use of metal-free catalysts greatly improves the sustainability of chemical processes. In view of this, the recent progress in the preparation of graphene-based metal-free catalysts along with their applications in catalytic oxidation, reduction and coupling reactions are summarized in this review. The future trends and challenges for the design of graphene-based materials for industrial organic catalytic reactions with good stabilities and high catalytic performance are also discussed.     

微波技术在催化领域中的应用

简述了微波诱导催化反应原理以及微波诱导催化反应对催化剂和载体的要求。介绍了微波技术在制备催化剂和改性载体方面的应用。     

磁性可回收钯催化剂催化Suzuki反应的研究进展

钯催化剂催化卤代芳烃和芳基硼酸生成碳一碳键的Suzuki偶联反应是合成联苯化合物的最重要的途径之一。相比于传统均相钯催化剂的利用率低,污染产品等缺点,磁性钯催化剂易回收,可重复利用,具有工业化应用前景,受到了广泛的关注。综述了近年来无配体磁性钯催化剂、无包裹磁性钯配体催化剂以及以碳、氧化硅、聚合物包裹的具有核壳结构的磁性钯配体催化剂的制备及其催化Szuki偶联反应的研究进展。     

催化裂化汽油的二次反应

从降烯烃、降硫和增产丙烯的现实需要出发,分析了FCC汽油二次反应中的理想和非理想反应.用小型提升管催化裂化实验装置考察了FCC粗汽油在REUSY、ZRP和MO-REY沸石催化剂上二次反应的产品分布和改质汽油组成;探讨了操作强度对二次反应转化率和选择性的影响.结果表明：在Y型或ZRP沸石催化剂作用下,FCC汽油二次反应不仅产生更轻的干气和富含丙烯的液化气,也产生更重的柴油和焦炭.二次反应得到的改质汽油与原料汽油相比,其烯烃含量和硫含量降低,芳烃含量和辛烷值明显提高.二次反应的转化深度和选择性取决于原料汽油的烯烃含量、催化剂沸石类型和操作强度.     

Study of the Individual Reactions of Hydrodesulphurization of Dibenzothiophene and Hydrogenation of 2-Methylnaphthalene on ZnNiMo/γ-Alumina Catalysts

A series of ZnNiMo/γ-alumina catalysts with variable Zn/(Ni + Zn) ratio were synthesized. These catalysts were characterized by chemical analysis, temperature programmed reduction (TPR) and BET surface area. After that, these catalysts were tested in the individual reactions of hydrodesulphurization (HDS) of dibenzothiophene (DBT) and hydrogenation (HYD) of 2-methylnaphthalene (2MN). The results showed an increment of the catalytic activity, for both reactions, when the catalysts were doubly promoted with Ni and Zn in comparison to those mono-promoted catalysts.     

Fischer-Tropsch synthesis catalyzed by iron catalyst supported on porous polymers. II. Catalytic results

Macroporous styrene-divinylbenzene and 4-vinylpyridine-divinylbenzene copolymers were used as supports for an iron Fischer-Tropsch catalyst. The catalytic systems were studied in batch reactions of uniformly supported catalysts, continuous reactions of uniformly supported catalysts and continuous reactions of fully heterogenised catalysts. We have shown that the particular distribution of products and selectivity observed for the corresponding homogeneous catalytic systems are in general conserved in the supported ones. The supported induces a better selectivity in alkene synthesis, and for the fully heterogenised system there is, depending on the rate of gas flow, a relatively important selectivity in the oxy product.     

Preparation of recoverable Ru catalysts for liquid-phase oxidation and hydrogenation reactions

We here report the synthesis, characterization and catalytic performance of new supported Ru(III) and Ru(0) catalysts. In contrast to most supported catalysts, these new developed catalysts for oxidation and hydrogenation reactions were prepared using nearly the same synthetic strategy, and are easily recovered by magnetic separation from liquid phase reactions. The catalysts were found to be active in both forms, Ru(III) and Ru(0), for selective oxidation of alcohols and hydrogenation of olefins, respectively. The catalysts operate under mild conditions to activate molecular oxygen or molecular hydrogen to perform clean conversion of selected substrates. Aryl and alkyl alcohols were converted to aldehydes under mild conditions, with negligible metal leaching. If the metal is properly reduced, Ru(0) nanoparticles immobilized on the magnetic support surface are obtained, and the catalyst becomes active for hydrogenation reactions.     

Recent Advances in Catalysis Over Mesoporous Molecular Sieves

This overview covers the recent achievements in the application of mesoporous molecular sieves as catalysts and catalyst supports. Main structural and textural features are outlined in relation to the novel synthesis approaches of mesoporous molecular sieves and understanding of their properties. For application of mesoporous molecular sieves as catalysts different ways of introduction of active sites on their surfaces are provided. The main part describes selected catalytic reactions catalyzed by mesoporous molecular sieves focused on very recent papers. The examples include metathesis, acylation reactions, C–C coupling reactions of Heck and Suzuki types, base-catalyzed reactions (Knoevenagel and Michael additions, Claisen-Schmidt condensation, Tischenko reaction) and last but not least immobilization of organometallic complexes for different catalytic applications including chiral catalysts.     

Varying the Directionality of Protein Catalysts for Aldol and Retro-Aldol Reactions

Natural aldolase enzymes and created retro-aldolase protein catalysts often catalyze both aldol and retro-aldol reactions depending on the concentrations of the reactants and the products. Here, we report that the directionality of protein catalysts can be altered by replacing one amino acid. The protein catalyst derived from a scaffold of a previously reported retro-aldolase catalyst, catalyzed aldol reactions more efficiently than the previously reported retro-aldolase catalyst. The retro-aldolase catalyst efficiently catalyzed the retro-aldol reaction but was less efficient in catalyzing the aldol reaction. The results indicate that protein catalysts with varying levels of directionality in usually reversibly catalyzed aldol and retro-aldol reactions can be generated from the same protein scaffold.     

The Role of the Support in the Oxidative Destruction of Chlorobenzene on Pt/Zeolite Catalysts: An FT-IR Investigation

The vapor-phase cyclohexane oxidative dehydrogenation has been investigated over several catalysts. A typical catalyst for total oxidation, as Mn₂O₃, materials applied in the field of oxide hydrogenation reactions, as silica-supported vanadia- and niobia-based catalysts, V-, Fe-, and Ce-phosphates used for partial oxidation reactions and ZSM5 zeolite, protonic and Co exchanged, have been tested. Over almost all the catalysts, benzene is the main product obtained, although cyclohexene is obtained with high selectivity at low conversion on phosphate catalysts.     

Supported Pd Nanoparticles for Carbon–Carbon Coupling Reactions

We intent to present an overview of the available catalysts for the carbon–carbon cross-coupling reactions based on supported palladium (Pd) nanoparticles (NPs). We begin this perspective with a brief introduction about the cross-coupling reactions and the mechanistic implications of using Pd NPs as catalyst, i.e. heterogeneous versus homogeneous catalysis, then we summarize some of the most versatile Pd supported catalysts as a function of its nature. The supported catalysts have been classified in inorganic, organic and hybrid supports. Finally we outline the perspectives for the development of new Pd supported catalysts.     

化学工业中的新酸碱催化过程

介绍了1990年以来全世界化学工业中投入生产的新酸碱催化过程。这些过程采用的催化剂主要为沸石,杂多酸,离子交换树脂,改性氧化锆和超强碱等,涉及的反应类型包括均相和多相催化的液相和气固相反应。同时对酸碱催化未来的研究方向进行了评述。     

Development of novel Lewis acid catalysts for selective organic reactions in aqueous media

New types of Lewis acids as water-compatible catalysts have been developed. Various metal salts were found to work as Lewis acid catalysts in aqueous media, and catalytic asymmetric aldol reactions in such media have been attained. Furthermore, Lewis acid-surfactant combined catalysts, which can be used for reactions in water without using any organic cosolvents, have been also developed. These investigations will contribute to reducing the use of harmful organic solvents and to develop efficient catalytic systems which cannot be realized in conventional organic solvents.     

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。     

Microemulsion Prepared Pt in Ceria: Catalytically Active for Water Gas Shift Reaction but Totally Inert for Methanation

A core–shell Pt in ceria type of catalyst prepared by a microemulsion technique shows high activity for both water gas shift and reverse water gas shift reactions but it does not catalyze methanation from carbon oxides and hydrogen feeds at all, whereas Pt-ceria catalysts prepared by traditional methods are effective for all these reactions under comparable reaction conditions. This clearly reveals the fact that the nature of active sites for shift reactions is different from those of methanation reactions, where a special metal-support interface in catalysts created by microemulsion offers the differentiation.     

聚酯催化剂的研究进展

详细叙述了锑系、钛系、锗系、锡系、铝系和酶催化剂在聚酯反应中的应用情况,介绍了这些催化剂的分类和它们的优、缺点,指出高效环保型催化剂是聚酯催化剂发展的方向。     

Pechmann反应法合成4-取代香豆素的研究进展

综述了Pechmann反应法制备4-取代香豆素类化合物的最新进展，重点就4-位取代基的类别和反应条件，特别是就新型固体酸催化剂、路易斯酸催化剂、离子液体、微波技术、超声波等在Pechmann反应中的应用进行了介绍。