Benzylation of benzene and other aromatics by benzyl chloride over mesoporous AlSBA-15 catalysts

Aluminum-containing mesoporous molecular sieves AlSBA-15 with different n_Si/n_Al ratios and AlMCM-41 have been synthesized hydrothermally and characterized in detail by physicochemical methods, viz. XRD, N₂ adsorption and ²⁷Al NMR spectroscopy. The low angle XRD and N₂ adsorption measurements reveal that the structural order of SBA-15 was retained after the incorporation of Al. The increase of the unit cell parameter with increasing aluminum content and ²⁷Al MAS NMR spectroscopy confirm the incorporation of aluminum in the framework. Benzylation of benzene and substituted benzenes reaction employing benzyl chloride as the alkylating agent over AlSBA-15 and AlMCM-41 have been investigated. The influence of various reaction parameters such as reaction temperature, reactant feed ratio and catalyst amount affecting the activity and selectivity of AlSBA-15, have been studied. Among the mesoporous catalysts studied, AlSBA-15(45), where the number in parentheses indicates the molar n_Si/n_Al ratio, shows both high conversion and high selectivity for the benzylation of benzene. The activity of this catalyst for the benzylation of different aromatic compounds is in the following order: benzene > toluene > p-xylene > mesitylene > anisole. Kinetics of the benzene benzylation over different catalysts have also been investigated.     

Alkylation of hydroquinone with tert-butanol over AlSBA-15 mesoporous molecular sieves

A series of AlSBA-15 catalysts with different pore size and different Si/Al ratio were prepared and characterized by N₂ adsorption and NH₃-temperature programmed desorption (NH₃-TPD) methods. Their catalytic behaviors for the alkylation of hydroquinone with tert-butanol were studied and compared with that of HZSM-5, HY, HAlMCM-41. It is found that the catalytic activity correlates well with the amount of medium-strong acid sites on the surface of the catalysts, and the selectivity towards 2-tert-Butylhydroquinone has some connection with the pore size of the catalysts. The reusability of the catalyst depends on its hydrothermal stability, which needs to be improved for the AlSBA-15 catalysts.     

含磷多孔有机聚合物的合成及其在多相催化中的应用

含磷多孔有机聚合物不仅具有发达的孔隙和表面结构,还具有很强的可调变性和可修饰性,在多相催化中有着广泛的应用前景。目前还没有概述含磷多孔有机聚合物的制备及其在多相催化中应用的综述,本文对该领域近十年来的研究进展进行了归纳和梳理。指出含磷多孔有机聚合物的合成方法发展十分迅速,包括偶联缩聚、锂盐参与的缩聚、Friedel-Crafts缩聚、溶剂热烯烃聚合、Scholl缩聚、酚醛聚合、醛胺缩合、聚吡喃盐的磷代以及多段式聚合等。基于其骨架中含有大量膦配体,含磷多孔有机聚合物能负载一系列金属化合物制成负载型金属纳米颗粒催化剂,甚至单原子或单位点金属催化剂。表明聚合物基催化剂中,膦配体不仅能诱导金属在聚合物中均匀分布,并且在调控金属的表面电子性质和位阻性质等方面发挥重要作用,进而对催化剂的活性和选择性产生影响。     

酸性离子液体及其在催化反应中的应用研究进展

介绍了酸性离子液体及其分类,对酸性离子液体的特性进行了概述.综述了近年来Lewis酸性离子液体、Br(o)nsted酸性离子液体、双酸性离子液体在催化反应中的应用研究进展,对酸性离子液体的固载化及离子液体的酸性表征方法进行了评述,提出了酸性离子液体在应用过程中存在的问题和发展方向.     

介孔分子筛SBA-15在催化领域的应用进展

从负载固体酸催化剂、金属和金属氧化物以及手性催化剂三方面综述了介孔分子筛SBA-15在催化领域应用的研究进展;并展望了介孔分子筛SBA-15在催化领域的研究方向。     

Nanotechnology: applications and potentials for heterogeneous catalysis

Nanotechnology offers the potential to design, synthesize, and control at nanometer length scale. While the catalysis community has many techniques at their disposal to synthesize catalytic materials at such a scale, the ability to fully design and control is still lacking. Examples are presented to illustrate what can nanotechnology do for heterogeneous catalysis to help achieve the goal of designing catalysts for perfect selectivity in a chemical reaction. Some current state-of-the-art approaches and potential limitations are discussed. Some examples of what can catalysis do for nanotechnology are also presented. However, this aspect is much less studied, although it offers rich opportunities for the catalysis community.     

神经网络全局势函数在多相催化中的应用

当今的多相催化研究需要新的技术和方法从原子尺度上表征活性中心结构和反应中间体。本文作者课题组近期开发了理论模拟新技术来探索催化剂活性位点结构,即基于神经网络势函数的大规模原子模拟(LASP)软件中实现的全局神经网络势函数计算方法。本文介绍了该方法可以显著降低催化体系的计算代价,而维持与密度泛函理论同一级别的计算精度,从而解决多相催化中的许多复杂问题。本文对神经网络势函数方法的实现细节和目前已实现的应用场景进行了详细介绍。神经网络势函数可以用来预测材料晶体结构,理解高压氢化条件下TiO₂表面的结构演化和确定三元氧化物ZnCrO晶相中合成气制甲醇活性位点。最后文章分析了神经网络势函数的局限性和今后可能的三个研究方向,即材料性质预测、多元素体系神经网络势函数构造和化学反应拟合。     

离子液体的研究开发及其在催化反应中的应用

离子液体是在室温下为液态、具有离子特性的新型溶剂，具有超低蒸气压，也称为绿色溶剂。通过选择合适的阳离子、阴离子和配体，可以调变离子液体的化学、物理性能。作为一种环境友好的反应介质，离子液体在清洁催化中的应用具有诱人前景。     

聚离子液体及其在天然产物分离中的应用

天然产物资源丰富,其高效利用离不开先进的分离技术。兼具离子液体高选择性及聚合物安全、易回收等特性的聚离子液体为天然产物的分离提供了新途径。在介绍聚阳离子型、聚阴离子型和聚两性型离子液体制备技术的基础上,综述了使用聚离子液体的固相萃取、固相微萃取、分子印迹固相萃取、液液萃取及毛细管电泳技术在黄酮类、生物碱类、酚类、蛋白质类等天然产物分离中的研究进展,分析了聚离子液体分离作用机理及其具有良好的分离效率、稳定性和回收再利用性能的原因,特别强调了刺激响应聚离子液体在天然产物分离中的优势,并从聚离子液体设计和定制出发对聚离子液体在分离领域所存在的挑战和潜在的应用进行了展望。     

SBA-15固载酸性离子液体催化酯化反应性能

为了减少离子液体用量及解决催化剂分离问题,采用键合法制备了以SBA-15为载体的固载化离子液体催化剂[C₃SO₃HCP]HSO₄/SBA-15,通过FT-IR、TG、XRD、BET和TEM分析了催化剂的结构和稳定性。并将其应用于催化丁二酸酐和乙醇的酯化反应。结果表明:[C₃SO₃HCP]HSO₄被成功固定在SBA-15上,且具有较高的热稳定性和催化活性,克服了非均相催化剂活性不高与均相催化剂难以分离的不足。在催化剂用量为反应物总质量的5%、n(C₄H₄O₃):n(C₂H₅OH)=1:3,反应温度80℃;反应时间4 h、带水剂用量为反应物总质量的30%的条件下,酯收率达93.7%,且该催化剂循环使用8次后,仍具有较高的催化活性。此外,还考察了以[C₃SO₃HCP]HSO₄/SBA-15为催化剂催化合成系列酯也获得了较高的酯收率,且易于与产物酯分离。     

Reflections on applications of NMR in heterogeneous catalysis and surface chemistry

The use of NMR to characterise heterogeneous catalytic systems and processes is assessed, critically, in overview. The generally wide scope and applicability of NMR is placed in the context of the constraints of NMR experimental requirements and the general goal of studying catalytic systems under conditions relevant to their actual use. In particular, the issues of sensitivity, resolution and dynamic processes in NMR are considered alongside the aims of surface selectivity, sample environment control and the desirability of associated characterisation of the catalytic systems by methods complementary to NMR.     

离子液体在酶催化应用中的研究进展

简要介绍了离子液体的性质,论述了离子液体作为反应介质在脂肪酶、纤维素酶、蛋白酶等催化中的应用研究进展;阐述了离子液体对酶活性影响的机理。提出了离子液体在酶催化应用中所存在的问题。     

离子液体在酶催化应用中的研究进展

简要介绍了离子液体的性质,论述了离子液体作为反应介质在脂肪酶、纤维素酶、蛋白酶等催化中的应用研究进展;阐述了离子液体对酶活性影响的机理。提出了离子液体在酶催化应用中所存在的问题。     

Functional mesoporous poly(ionic liquid)-based copolymer monoliths: From synthesis to catalysis and microporous carbon production

Ionic liquid-functionalized mesoporous polymeric networks with specific surface area up to 935 m²/g have been successfully synthesized one pot by solvothermal copolymerization of divinylbenzene and monomeric ionic liquids. The as-obtained polymers exhibit a monolithic structure featuring large pore volumes, an abundant mesoporosity and an adjustable content of ionic liquids. The effect of the reaction conditions on the pore structure has been studied in detail. These poly(ionic liquid)-based porous networks (PILPNs) have then been employed as precursors in two distinct applications, namely organocatalysis and production of microporous carbon monoliths. Selected organocatalyzed reactions, including carbonatation of propylene oxide by cycloaddition with carbon dioxide, benzoin condensation, and cyanosilylation of benzaldehyde have been readily triggered by PILPNs acting as crosslinked polymer-supported (pre)catalysts. The two latter reactions required the prior deprotonation of the imidazolium salt units with a strong base to successfully generate polymer-supported N-heterocyclic carbenes, referred to as poly(NHC)s. Facile recycling and reuse of polymer-supported (pre)catalysts was achieved by simple filtration owing to the heterogeneous reaction conditions. Furthermore, PILPNs could be easily converted into microporous carbon monoliths via CO₂ activation.     

新型环己亚胺类离子液体的合成及其催化酯化反应性能

利用环己亚胺与1,3-丙烷磺酸内酯生成的1-(3-磺丙基)环己亚胺盐,合成了2种新型Br?nsted酸性离子液体1-(3-丙磺基) 环己亚胺硫酸氢盐（[HMIPS]HSO4）和1-(3-丙磺基) 环己亚胺对甲苯磺酸盐（[HMIPS]OTs）。采用1H NMR、FT-IR、LC-ESI-MS及DSC-TG等方法对其进行了表征。结果表明,所合成的[HMIPS]HSO4和[HMIPS]OTs是一类新型的Br?nsted酸性离子液体。该类型离子液体含有环己亚胺7元环,分解温度高于260℃,其水溶液的pH值与相同浓度的硫酸水溶液的相近,具有较强的Br?nsted酸性。最后考察了所合成的新型离子液体对柠檬酸和正丁醇酯化反应的催化性能,并与传统咪唑类离子液体进行了对比。结果显示,所合成的新型离子液体具有良好的催化活性,[HMIPS]HSO4为催化剂时,在n(柠檬酸):n(正丁醇):n([HMIPS]HSO4)＝5:1:0.02,110-130℃和回流反应2 h的条件下,柠檬酸的转化率为98.3%,柠檬酸三丁酯的收率可达97.5%。而传统的咪唑离子液体[MIMPS]HSO4为催化剂时,柠檬酸的转化率和柠檬酸三丁酯的收率分别为95.8%和94.7%。[HMIPS]HSO4催化剂在重复使用10次后催化活性未见明显下降。     

Ultrasonic preparation of mesoporous silica using pyridinium ionic liquid

Mesoporous silica matrices have been prepared via classic acid catalyzed and sono-catalyzed sol-gel routes. Tetramethoxysilan (TMOS) and methyl-trimethoxysilane (MTMS) were used as silica precursors, and N-butyl-3-methylpyridinium tetrafluoroborate ([bmPy][BF₄]) was employed as co-solvent and pore template. The ionic liquid (IL) to silica mole ratio was varied between 0.007 and 0.07. Nitrogen adsorption-desorption and small-angle neutron scattering measurements were used to characterize the obtained materials. The ionic liquid played the role of catalyst that affected the formation of the primary xerogel particles, and changed the porosity of the materials. Ultrasound treatment resulted in microstructure change on the level of the colloid particle aggregates. In comparison with IL containing xerogels, the IL containing sonogels show increased pore diameter, bigger pore volumes and diminished surface areas.     

离子液体催化合成香豆素葡萄糖苷糖酯类化合物的研究

以室温离子液体1正-丁基-3-甲基咪唑四氟硼酸盐中合成了香豆素葡萄糖苷糖酯类化合物。实验结果表明,反应时间4 h,反应物香豆素-3-羧酸与四乙酰溴代葡萄糖摩尔比为1.0∶1.0,产品收率为86.6%。用IR与1H NMR对其结构进行了表征。