磁性固体超强酸催化酯化反应的研究进展

磁性固体超强酸是一类具备选择性高、催化活性高、在外磁场存在下易于产物分离,方便回收.可逐渐替代了液体酸的酯化反应,在非均相反应中具有广泛的应用前景的催化剂综述了此类催化剂改性的制备方法和失活再生.县体介绍了金属或金属氧化物、分子筛与载体相结合.将明显提高催化效率和催化剂的重复使用性能。磁性固体超强酸是一类新型环保的绿色催化剂。     

丁醛催化缩合制备辛烯醛催化剂的研究

羟醛缩合是增长碳链的一类重要的有机反应。在反应过程中同时存在许多副反应,导致反应选择性降低,选择合适的催化剂对此类反应十分关键。固体碱催化剂不仅具有较高的活性和选择性,而且催化剂和反应体系易于分离。通过Ca负载SiO2,Ca负载Al2O3制备碱性氧化物催化剂Ca/SiO2、Ca/Al2O3,由实验表明Ca/Al2O3碱性氧化物催化剂具有较好具有很好稳定性、较高的选择性。     

丁烯烷基化固体酸催化剂的研究进展

阐述了异丁烷 丁烯烷基化催化剂的发展状况,主要涉及了几种新型固体酸催化剂,包括固体超强酸催化剂、分子筛催化剂和负载型杂多酸催化剂。文章着重对SO2-4 MxOy、MCM-41和负载型杂多酸催化剂的制备,活性和选择性作了探讨。同时指出了这些固体酸催化剂存在的问题,预测了烷基化催化剂研究的发展方向。     

负载型杂多酸催化剂的研究进展

负载型杂多酸作为一类新型固体酸催化材料,其合理利用不仅可以有效提高催化活性和选择性,而且减少了设备腐蚀和环境污染,且易于回收利用。本文着重综述了近年来活性炭、S iO2、MCM-41分子筛等各种负载型杂多酸催化剂的研究成果和动态,包括所涉及的反应物系、反应机理、催化性能与催化剂酸性质的关系等。最后通过负载型杂多酸催化剂目前存在的问题,展望了其今后的研究方向和重点。     

负载杂多化合物催化酯类反应研究进展

综述了杂多化合物催化剂催化酯类反应在国内外的研究和应用情况。杂多化合物由于具有准液相和超强酸性的特征,广泛用于各种酯类反应。杂多酸作为均相催化剂催化酯类反应具有很高的活性和选择性,但存在反应产物和催化剂分离问题。采用杂多酸盐及以活性炭、SiO₂、TiO₂和MCM-41等负载的杂多化合物多相催化酯类,催化剂不仅具有很高反应活性和选择性,同时易于同产物分离,克服了均相催化的缺点。     

环己酮自缩合固体催化剂的研究

研制了一种应用于环己酮自缩合反应的新型固体催化剂CC-1。与传统的浓硫酸催化剂相比，CC-1催化剂具有更优异的选择性，操作更简便。通过对不同用量的带水剂包括环己烷、正庚烷以及甲苯的使用效果进行考察，发现以用量为50 mL的正庚烷作带水剂的效果最理想，环己酮的转化率和二聚物的选择性分别达到87.5%和97.9%。对CC-1催化环己酮缩合反应的进程研究表明，该反应具有典型的连串反应特点。对CC-1催化剂的再生性能考察表明,该催化剂具有优良的再生性能，至少可以再生8次，维持催化剂活性在转化率85%和选择性96%左右。     

新型高稳定性长链烷烃脱氢催化剂的研制

介绍了新型脱氢催化剂的研制和该催化剂H2化学吸附性能以及脱氢反应性能，讨论了助催化剂组分Sn和碱金属对催化剂活性、稳定性及选择性的影响。结果表明，新型催化剂的转化率比工业用DF-2催化剂高2个百分点，寿命和选择性与DF-2相当。     

绿色化学的研究概述

绿色化学又称环境友好化学、清洁化学。绿色化学＂十二条原则＂指导化工生产向更经济、更绿色的方向发展,强调能源利用率,是清洁生产的重要保障。近年来绿色化学的研究主要是围绕原子经济性反应、反应选择性及生产原料、溶剂、催化剂和产品的绿色化而展开。     

胺与甲酸氮甲酰化反应催化剂的研究

氮甲酰化反应是有机合成化学中的重要反应，而催化剂的选择是氮甲酰化反应的关键所在。文章综述了无机氧化物，聚合物PEG-400，Lewis酸，树脂AmberliteIR-120，无机盐。VBl催化合成氮甲酰化产物的研究成果。不同的催化剂在活性、选择性、稳定性等方面各有特点，其中绿色高效可回收利用的催化剂是该领域的主要研究方向。     

固体酸催化剂烷基化脱噻吩硫的研究进展

综述了为提高催化剂的活性、稳定性和选择性,对固体酸催化剂以及脱硫工艺进行改进的最新研究进展,指出全优适宜的烷基化脱硫固体酸催化剂及新型脱硫工艺的开发,是今后的研究方向。     

Glycerol transformations on polysaccharide derived mesoporous materials

New polysaccharide based solid acids are excellent catalysts for selective chemical transformations of glycerol. Reasonable selectivities to mono-, di- and triacetylated glycerols can be obtained by controlled microwave activation of glycerol–acetic and solid acid mixtures. Etherifications of glycerol using a range of alcohols have also been achieved and with a degree of selectivity to both 1- and 2-positions. The use of the Starbon^® material as a support for palladium further extends the range of heterogeneous catalysed chemistry to the selective oxidations of glycerol to both glycolic and oxalic acids. In all of the reactions, the catalysts can be easily recovered and reused with only a small loss in activity.     

甲醇气相脱水制二甲醚催化剂研究进展

甲醇气相脱水制二甲醚反应为固体酸催化反应,常用的固体酸催化剂有γ-Al₂O₃和分子筛类。γ-Al₂O₃表面存在弱酸中心或中等强度酸中心,催化剂有较好的初始催化活性,但活化所需的反应温度较高,耐水稳定性差;分子筛类催化剂表面有许多强酸性位,低温下催化活性较高,但在高温反应条件下易产生烃类副产物和积炭,热稳定性差。为改善这两类催化剂的催化性能,对催化剂进行了各种改性研究,改性后催化剂的活性、选择性和稳定性均有一定程度提高。综述了近年来在γ-Al₂O₃和分子筛催化剂上进行的改性研究,总结并展望了甲醇脱水催化剂的发展方向。     

One‐Pot Hydroacetylation of Menadione (Vitamin K3) to Menadiol Diacetate (Vitamin K4) by Heterogeneous Catalysis

Vitamin K₄ (menadiol diacetate, MDD) can be easily synthesized through cleaner and more efficient catalytic alternatives following the green chemistry principles. Ionic gold‐based hydroxylated fluorides are active bi‐functional catalysts for the one‐pot hydroacetylation of menadione leading to MDD with 77% selectivity. Unprecedent results were obtained in the presence of oxide‐fluoride catalysts by using a microwave‐assisted hydrogen‐transfer (Meerwein–Ponndorf–Verley reaction) coupled with an acetylation approach, yielding very high selectivities for the target product (95%).     

氯代硝基苯选择性加氢催化剂研究现状与进展

氯代苯胺（chloraniline,CAN）是重要的精细化学品中间体,应用广泛。氯代硝基苯（chloronitrobenzene,CNB）经催化加氢合成CAN的方法存在脱氯副反应,因此改进催化剂性能以提高该反应选择性受到广泛重视。本文从多相催化体系和均相催化体系分别总结了近年来此类催化剂的研究现状与进展。多相催化体系常用的改性方式包括调变金属相分散度、调变载体性质、添加金属助剂等。其中,通过调变金属相分散度得到的单原子催化剂,因其高原子利用率而呈现出优异的催化性能,但提高其稳定性仍是未来探索的方向。均相催化剂包括金属配合物催化剂、金属胶体催化剂等,常用的改性方式有添加金属离子/配合物等。均相催化剂反应效率高,但普遍制备过程繁琐、较难回收,仍有待优化。另外,本文还总结了反应介质对该加氢体系的影响。最后总结了催化剂改性方案的特点,对未来CNB选择性加氢催化剂的设计与应用提供了理论指导。     

Advancements in Heterogeneous Catalysis for Biodiesel Synthesis

Heterogeneous catalysts are promising for the transesterification reaction of vegetable oils to produce biodiesel and have been studied intensively over the last decade. Unlike the homogeneous catalysts, heterogeneous catalysts can be easily separated from reaction mixture and reused for many times. They are environmentally benign and could be easily operated in continuous processes. This review classifies the solid catalysts into two categories based on their catalytic temperature, i.e. high temperature catalysts and low temperature catalysts. The nature of the catalysts can be specified into solid bases and solid acids. Three aspects, catalyst activity, catalyst life and oil flexibility, will be reviewed. Two kinds of heterogeneous catalysts, reported by IFP Inc. and by WSU, respectively, show a high catalytic activity, long catalyst life and low leaching of catalyst components. These two catalysts also show ability to simultaneously catalyze esterification and transesterification, and can be used in half-refined or crude oil system which provide a potential for greatly decrease the feedstock cost.     

Environmentally benign multiphase catalysis with dense phase carbon dioxide

Environmental concerns stemming from the use of conventional solvents and from hazardous waste generation have propelled research efforts aimed at developing benign chemical processing techniques that either eliminate or significantly mitigate pollution at the source. This paper provides an overview of heterogeneous and homogeneous catalysis in dense phase CO₂, considered a green solvent. In addition to solvent replacement, the demonstrated advantages of using dense phase CO₂ include the enhanced miscibility of reactants, such as O₂ and H₂ which eliminate interphase transport limitations, and the chemical inertness of CO₂. Further, the physicochemical properties of CO₂-based reaction media can be pressure-tuned to obtain unique fluid properties (e.g. gas-like transport properties, liquid-like solvent power and heat capacities). The advantages of CO₂-based reaction media for optimizing catalyst activity and product selectivity are highlighted for a variety of reactions including alkylation on solid-acid catalysts, hydrogenation on supported noble metal catalysts and a broad range of homogeneous oxidations with transition metal catalysts and dioxygen as an oxidant. Through these examples, the need is emphasized for a systematic approach to research and development of supercritical carbon dioxide based processes, taking into account conventional multiphase reaction engineering principles, catalytic chemistry and phase behavior.     

Novel heterogeneous zinc triflate catalysts for the rearrangement of α-pinene oxide

New solid acid catalysts based on silica‐supported zinc triflate have been prepared for use in the rearrangement of α-pinene oxide to campholenic aldehyde. These catalysts exhibit considerable activity and can be recycled without loss of selectivity towards the aldehyde. The selectivity towards the aldehyde can be increased to 80% (at 50% conversion) when the reaction is performed at 25°C using hexagonal mesoporous silica (HMS₂₄) as the catalyst support. This revised version was published online in July 2006 with corrections to the Cover Date.     

Catalytic Applications of Zeolites in Chemical Industry

New materials are prerequisite for major breakthrough applications influencing our daily life, and therefore are pivotal for the chemical industry. Nanoporous materials constitute an important class of heterogeneous catalysts as they not only offer higher surface areas and enhanced activity, but also provide shape/size selectivity. As a well-established family of nanoporous materials, zeolites are of paramount importance for the chemical industry as heterogeneous catalysts with shape/size-selective character in various reactions. Zeolites can also play an active role in the quest for raw material change as catalysts providing the required selectivity towards base chemicals. In this contribution, an overview of the current and potential applications of zeolites as catalysts in chemical industry is presented.     

Solid acids for green chemistry

Solid acids and especially those based on micelle-templated silicas and other mesoporous high surface area support materials are beginning to play a significant role in the greening of fine and specialty chemicals manufacturing processes. A wide range of important organic reactions can be efficiently catalyzed by these materials, which can be designed to provide different types of acidity as well as high degrees of reaction selectivity. The solid acids generally have high turnover numbers and can be easily separated from the organic components. The combination of this chemistry with innovative reaction engineering offers exciting opportunities for innovative green chemical manufacturing in the future.