介孔与介孔主客体材料在催化领域的应用

 综述了近年来介孔分子筛催化材料制备的研究成果及其在催化领域特别是精细化学品合成中的应用. 文章分为两部分,分别讨论了介孔材料本身作为催化剂以及介孔主客体催化材料的应用.     

纳米自组装合成大孔容介孔氧化铝

提出了一种纳米自组装大孔容介孔氧化铝固体材料的制备方法．提出了二级纳米自组装机理和框架式大孔容介孔固体材料形成机理．在一级纳米自组装体,超增溶胶团中,氢氧化铝沉淀与VB值小于1的表面活性剂原位自组装成线状、棒状二级纳米自组装体．二级纳米自组装氢氧化铝焙烧形成棒状纳米氧化铝．对于大孔容介孔固体材料的形成,我们提出了没有外表面要求限制,纳米氧化铝组成没有连续外表面的框架式介孔固体材料机理．采用二级纳米自组装体为模板剂合成出适用于渣油加氢处理催化剂的大孔容介孔固体材料,物理性质为1．8～2．7mL·g^-1的孔容、180～429m^2·g^-1比表面、17～57nm的平均孔径、大于10nm的孔为81％～94％、87％～93％的孔隙率和7．7～25N／mm的强度．     

主客体相互作用和自组装方法构建水溶性的金纳米粒子网络

纳米材料具有与许多奇异的尺寸相关的物理化学性质,因而引起研究者广泛的关注．控制纳米材料的形貌,如纳米粒子、纳米棒和纳米线等是目前研究的热点．与这些纳米材料相比,纳米网络具有广泛应用前景．例如,这种纳米网络可以应用于高集成度的电子元件．同时纳米网络中的空腔可以用作承载酶和药物等,应用于酶催化反应和药物控制释放等领域．为了满足这些应用要求,     

环糊精与表面活性剂主客体作用诱导的金纳米棒可控自组装

The self-assembly of colloidal nanocrystals has emerged as a powerful strategy for the bottom-up fabrication of functional materials and nanodevices. Recently, the self-assembly of gold nanorods (GNRs) has attracted significant attention because of their unique plasmonic properties, but the realization of their adjustable self-assembly of GNRs through facile and effective approaches remains challenging. In this work, the controllable self-assembly of GNRs in aqueous solution was realized through the host-guest interactions of cyclodextrins (CDs) and the cetyltrimethylammonium bromide (CTAB) molecules adsorbed on the surface of the GNRs. The self-assembly of GNRs was readily achieved by the addition of aqueous α-CD solutions with varied concentrations into aqueous dispersions of CTAB-stabilized GNRs. At a relatively low α-CD concentration, slow aggregation of the GNRs occurred, resulting in their side-by-side assembly. This was revealed by the blue shift of the longitudinal surface plasmon resonance (LSPR) band in the absorption spectra and confirmed by transmission electron microscopy (TEM) observations. On the other hand, when a higher concentration of α-CD was added, fast aggregation of the GNRs occurred, resulting in their end-to-end assembly. This was revealed by the red shift in the LSPR band together with the TEM observations. If β-CD was employed instead of α-CD, the self-assembly of GNRs could also be induced, although a relatively higher concentration of β-CD was required to achieve the extent of aggregation similar to that induced by α-CD, indicating that the supramolecular host–guest interaction between CDs and the surfactant CTAB was crucial to the directed self-assembly of GNRs. Furthermore, the α-CD-induced assembly was inhibited on addition of excess CTAB, confirming that the supramolecular interaction of α-CD and CTAB played a key role in directing the self-assembly of the GNRs. Based on these experimental results, a possible mechanism for the α-CD-induced self-assembly of GNRs was proposed as follows: at a lower α-CD concentration, the gradual formation of the host-guest inclusion complex α-CD/CTAB led to the partial replacement of the highly charged CTAB bilayers adsorbed on the GNRs by the less charged complex, which resulted in a slow side-by-side assembly of the GNRs; at a higher α-CD concentration, the CTAB bilayers were quickly replaced by the α-CD/CTAB complex, and the CTAB molecules adsorbed at both ends of the GNRs were almost completely replaced, resulting in a fast end-to-end assembly of the GNRs. Additionally, on the basis of the hydrolysis of α-cyclodextrin catalyzed by α-amylase, the self-assembly of GNRs directed by the host-guest interaction could be used to realize the feasible detection of α-amylase in solutions. This self-assembly strategy mediated by the host-guest interaction may be extendable to other colloidal systems involving surfactants adsorbed on the surface of nanoparticles, and may open new avenues for the controllable self-assembly of non-spherical nanoparticles.     

大孔Mo-Ni/Al_2O_3催化剂的催化裂化柴油加氢性能研究

采用三次纳米自组装合成法,制备了一种以二次纳米自组装Al2O3为主体的大孔主客体催化剂FA-40,具有0.78 cm3·g-1的孔容、114 m2·g-1的比表面积、27 nm的平均孔径、6.0 nm和40 nm的双峰孔结构、孔分布在10~100 nm高度集中、低堆积密度为0.56 g·cm-3、活性金属含量高达35.70%。XRD和TEM分析结果显示,活性金属以直径小于2 nm的微晶态纳米粒子形式均匀分散于主体表面。采用劣质催化裂化柴油进行20 h加氢实验评价,反应趋于稳定时,FA-40的脱硫、脱氮及芳烃饱和率分别达到94.4%、95.5%和67.9%,与F-5相比分别提高了20%、80%和140%。300 h的长周期加氢实验表明,FA-40具有良好的加氢性能。     

原位塌陷自组装法制备氧化锰纳米结构材料

采用一种简单的原位塌陷自组装法利用高锰酸钾(KMnO4)和油酸(OA)在O/W乳液界面上发生的"Baeyer test for unsaturation"反应,用乙醚作为共溶剂来制备氧化锰纳米结构.与之前相比,加入乙醚(EE)最大的优点是减少了反应过程中油酸的用量,大大简化了产品的洗涤过程,降低了制备成本.得到的产品分...     

用自组装法制备聚合物纳米复合膜

文章比较了自组装法（ｓｅｌｆ－ａｓｓｅｍｂｌｙ,ＳＡ）与Ｌａｎｇｍｕｉｒ－Ｂｌｏｄｇｅｔｔ技术（ＬＢ）及其它方法在制备聚合物纳米复合膜时的优劣。ＳＡ法由于操作简单、膜的结构稳定性较高,因此较ＬＢ技术等具有更大的实用价值。利用ＳＡ法,可以制备各种有机聚电解质与其带相反电荷的有机聚电解质、粘土化合物及无机纳米颗粒等组成的聚合纳米复合膜。     

CdSe纳米结构单元的制备与自组装

纳米CdSe作为一种重要的半导体纳米材料,在发光二极管、生物标记、太阳能电池等领域有着广泛的应用。本文综述了CdSe纳米结构单元制备与自组装的最新研究进展。归纳出了6种有代表性的制备与组装方法,详细介绍了这些方法的原理以及采用这些方法制备的CdSe纳米结构。最后,对这一领域的发展方向作了展望。     

大孔Mo-Ni/Al2O3催化剂的催化裂化柴油加氢性能研究

采用三次纳米自组装合成法,制备了一种以二次纳米自组装Al₂O₃为主体的大孔主客体催化剂FA-40,具有0.78cm³·g^-1的孔容、114m₂·g^-1的比表面积、27nm的平均孔径、6.0nm和40nm的双峰孔结构、孔分布在10~100nm高度集中、低堆积密度为0.56g·cm^-3、活性金属含量高达35.70%。XRD和TEM分析结果显示,活性金属以直径小于2nm的微晶态纳米粒子形式均匀分散于主体表面。采用劣质催化裂化柴油进行20h加氢实验评价,反应趋于稳定时,FA-40的脱硫、脱氮及芳烃饱和率分别达到94.4%、95.5%和67.9%,与F-5相比分别提高了20%、80%和140%。300h的长周期加氢实验表明,FA-40具有良好的加氢性能。     

Reversible photoswitching self-assembly of azobenzene-functionalized hyperbranched polyglycerol induced by host-guest chemistry

Reversible assembly and disassembly of rod-like large complex micelles have been achieved by applying photoswitching of supramolecular inclusion and exclusion of azobenzene-functionalized hyperbranched polyglycerol and α-cyclodextrin as driving force, promising a versatile system for self-assembly switched by light. Hydrogen-nuclear magnetic resonance (1H NMR) and Fourier transform infrared (FT-IR) spectroscopy were applied to characterize the azobenzene-functionalized hyperbranched polyglycerol. Atomic force microscopy (AFM), transmission electron microscopy (TEM) and dynamic laser light scattering (DLS) were employed to investigate and track the morphology of the rod-like large complex micelles before and after irradiation of UV light.     

磁性纳米Fe3O4的氧化共沉淀法制备及催化性能

以单一 Fe²⁺作为铁源,0.4% 的 H₂O₂为氧化剂,NaOH 为沉淀剂,采用氧化共沉淀法制备了尺寸为 7 nm的 Fe₃O₄颗粒。为进一步体外模拟肿瘤饥饿治疗,设计了一个包含5 mL(10 μg·mL^-1)的葡萄糖氧化酶和15 mL(5 mg·mL^-1)葡萄糖溶液的体系,以探究纳米 Fe₃O₄的类过氧化氢酶(CAT)与类过氧化物酶(POD)催化性能的最适条件。结果表明：在 1 mg·mL^-1 pH=5.0 时,纳米Fe₃O₄的类CAT活性能推动葡萄糖氧化反应的反应速度增加、限度增大;pH=5.0时,纳米Fe₃O₄的类POD活性更好,能高效率催化H₂O₂产生活性氧。     

磁性纳米Fe3O4的氧化共沉淀法制备及催化性能

以单一 Fe²⁺作为铁源,0.4% 的 H₂O₂为氧化剂,NaOH 为沉淀剂,采用氧化共沉淀法制备了尺寸为 7 nm的 Fe₃O₄颗粒。为进一步体外模拟肿瘤饥饿治疗,设计了一个包含5 mL(10 μg·mL^-1)的葡萄糖氧化酶和15 mL(5 mg·mL^-1)葡萄糖溶液的体系,以探究纳米 Fe₃O₄的类过氧化氢酶(CAT)与类过氧化物酶(POD)催化性能的最适条件。结果表明：在 1 mg·mL^-1 pH=5.0 时,纳米Fe₃O₄的类CAT活性能推动葡萄糖氧化反应的反应速度增加、限度增大;pH=5.0时,纳米Fe₃O₄的类POD活性更好,能高效率催化H₂O₂产生活性氧。     

大孔FCC催化剂的制备及裂化性能研究

利用聚苯乙烯(PS)颗粒和脱油残渣(VR)乳液为模板剂制备了大孔重油催化裂化催化剂,与未加模板的参比催化剂相比,比表面积分别增加了38.0%和46.2%,孔体积分别增加了20.6%和35.8%,平均孔径分别增加了54.5%和27.3%。微反评价结果表明,大孔催化剂活性较高,对重油的转化率分别提高了9.8%和12.2%,总液收分别提高了10.2%和7.3%。与参比催化剂相比,积炭后PS颗粒和VR乳液模板大孔催化剂的活性有一定程度的降低,但是当积炭量相同时,大孔催化剂的重油转化率和总液体产物收率都比参比催化剂要高,且两类大孔催化剂的数据比较接近。催化剂的基质经模板扩孔后,由于具有微孔-介孔-大孔的梯度孔分布,孔径分布更加合理,重油分子在催化剂孔道内的扩散速率更快,容炭能力更强,所以大孔催化剂具有较好的裂化性能。     

超增溶胶团自组装合成纳米氧化铝

应用超增溶胶团纳米自组装原理,以硝酸铝和尿素为熔盐,聚异丁烯马来酸三乙醇胺为表面活性剂制备超增溶氢氧化铝胶团,然后以氢氧化铝为前躯体合成纳米氧化铝.采用BET、压汞法、SEM、TEM和XRD方法对合成的氧化铝进行表征.结果表明,纳米氧化铝粒子形状为球形体或棒状体,孔道在几十纳米到几百纳米,粒度分布均匀且纯度较高.     

Chirality manipulation of supramolecular self-assembly based on the host-guest chemistry of cyclodextrin

Chiral materials have been of the interests of scientists for nearly a century. People have endeavored a great effort to manipulate the chirality of various self-assembled materials. Among these efforts, cyclodextrins are used only in recent years, although it has long been recognized that the chirality of cyclodextrin can be transferred to the guest. In this review, we for the first time summarize the recent advancement of the supramolecular chirality manipulation on the basis of the host-guest chemistry of cyclodextrins. By using the simple Harata-Kodaka's rule, natural cyclodextrins can be exploited in a dynamic manner to create chirality inversion materials through crystalline self-assembly, which is facile and environment-friendly. What is more, we also discussed the remarks on future outlooks at the end of this article and expect it to stimulate a rapid development on both the theory and application level.     

新型大孔结构重油加氢催化剂的制备、表征与评价

将聚苯乙烯（PS）颗粒模板加入到铝溶胶中,经干燥、煅烧除去PS模板制备了大孔氧化铝载体;采用低温N₂吸附 脱附和SEM对合成Al₂O₃的孔结构进行了表征;将Co-Mo活性组分担载在大孔氧化铝载体上制得重油加氢催化剂,并以大港焦化蜡油为原料在固定床高压微反装置上对合成的催化剂进行活性评价。实验表明,加入PS模板后,Al2O3的比表面积增加了41.5m²/g,孔体积增加了0.35cm³/g;加氢脱硫活性提高了12%,脱氮活性提高了22%。     

Preparation of Au/Ag multilayers via layer-by-layer self-assembly in spherical polyelectrolyte brushes and their catalytic activity

Spherical polyelectrolyte brushes(SPBs) consisting of polystyrene(PS) core and poly(2-aminoethyl methacrylate hydrochloride)(PAEMH) shell were prepared by photo-emulsion polymerization. Au nanoparticles(Au-NPs) with controlled size and size distribution were synthesized in situ using SPBs as nanoreactors. Via layer-by-layer deposition technique on the surface of SPBs, nano-composite particles with Au/Ag-NPs bilayer and Au/Ag/Au-NPs trilayer were prepared. The structures of the as-prepared Au/Ag multilayer SPBs were characterized by UV-Vis spectroscopy, TEM, ICP-AES and DLS. The charge reversal of the nano-composite particles observed by zeta potential confirmed the success of layer-by-layer assembly. The Au/Ag-NPs bilayer nano-composite particles showed high catalytic efficiency with an apparent activation energy of about 41.2 k J/mol in the reduction reaction of 4-nitrophenol to 4-aminophenol in the existence of sodium borohydride monitored. The catalytic activity of Au/Ag-NPs multilayer SPBs close to that of Au-NPs SPBs and much higher than that of Ag-NPs SPBs reveals its potential applications in cost-effective catalysts with high-performance.     

Preparation and properties of macroporous superabsorbent composite

A fast swelling macroporous superabsorbent composite was prepared by the copolymerization of partially neutralized acrylic acid, 2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid (AMPS), and attapulgite (APT) using N, N′‐methylenebisacrylamide (NNMBA) and trihydroxymethyl propane glycidol ether as crosslinking agents. For fast swelling rate (SR), sodium bicarbonate, polyethylene glycol (PEG), and sodium carboxymethylcellulose (CMC) were introduced into the reaction system as foaming agent and stabilizers. Furthermore, the copolymer was surface‐crosslinked with glycerine and sodium silicate, and then blended with aluminum sulfate and sodium carbonate. The influences of the amount of NNMBA, trihydroxymethyl propane glycidol ether, PEG, CMC and sodium bicarbonate, and reaction temperature on water absorbence both under atmospheric pressure and load, and on the SR were investigated. The water absorbence of the sample in 0.9 wt% NaCl aqueous solution under atmospheric pressure and certain load (P ≈ 2 × 10³ Pa) could reach 54 and 8 g.g^?1, respectively, and the SR could reach 0.471 ml g^?1 s^?1. The excellent strength, resilience, and the dispersion of swollen hydrogel were also observed for the sample. Moreover, the surface morphology of macroporous superabsorbent composite was characterized using scanning electron microscope. Copyright © 2009 John Wiley & Sons, Ltd.