Pd Nanoparticles Encapsulated in Hollow Mesoporous Aluminosilica Nanospheres as an Efficient Catalyst for Multistep Reactions and Size-Selective Hydrogenation

最近,具有中空核壳结构的纳米材料在催化领域中有着深入的研究和广泛的应用.在本文中,我们使用一种简单易行的方法合成了一种包裹钯纳米颗粒的中空介孔硅铝酸盐纳米球(简写为Pd@HMAn).首先,通过一种先原位合成钯纳米粒子再对其进行二氧化硅包裹的方法,在brIJ56-环己烷-水的反相胶束中合成了具有核壳结构的包裹钯纳米颗粒的二氧化硅纳米球(简写为Pd@SIO2).然后,使用CTAb,nA2CO3和nAAlO2试剂,通过简单的碱性条件下刻蚀Pd@SIO2的过程,我们成功得到了具有多孔性能的中空核壳型Pd@HMAn纳米催化剂.由于硅铝酸盐外壳具有酸催化作用,并且内核钯纳米颗粒又是一种高活性的催化媒介,因此,这种复合的多功能纳米催化剂能够很好的应用于多步催化反应中.此外,通过一个简单的热处理的方法,能够缩小硅铝酸盐外壳上的孔道,我们发现这种孔道调节后的Pd@HMAn纳米催化剂在尺寸选择性氢化反应中有很好的应用前景.In this work,yolk-shell structured Pd@hollow mesoporous aluminosilica nanospheres(designated as Pd@HMAN) have been successfully fabricated by a straightforward synthetic route.Core-shell Pd@SiO2 nanospheres were firstly obtained by silica coating of in-situ synthesized Pd nanoparticles in a Brij56-cyclohexane-water reverse micelle system.Simply by alkaline etching of as-prepared Pd@SiO2 core-shell nanospheres in the presence of CTAB,Na2CO3 and NaAlO2,Pd@HMAN particles with high porosity were obtained.As the mesoporous aluminosilica shells can serve as acid catalysts,and the Pd yolks can be applied to catalytic hydrogenation,the as-prepared Pd@HMAN can be used as a stable multifunctional catalyst for multistep reactions.Moreover,due to their adjustable pore parameters,Pd@HMAN after simple thermal treatment can be further applied in the size-selective hydrogenation.ProjectsupportedbytheMinistryofScienceandTechnologyofChina(No.2011CB932403); theNationalNaturalScienceFoundationofChina(Nos.21131005;21021061;20925103;20923004); theFokYingTungEducationFoundation(No.121011)~

包钯纳米颗粒的中空介孔硅铝酸盐纳米球的合成及其在多步催化反应和尺寸选择催化氢化中的应用(英文)

E-mail Addresses: [email protected] this work, yolk-shell structured Pd@hollow mesoporous aluminosilica nanospheres (designated as Pd@HMAN) have been successfully fabricated by a straightforward synthetic route. Core-shell Pd@SiO2 nanospheres were firstly obtained by silica coating of in-situ synthesized Pd nanoparticles in a Brij56-cyclohexane-water reverse micelle system. Simply by alkaline etching of as-prepared Pd@SiO2 core-shell nanospheres in the presence of CTAB, Na2CO3 and NaAlO2, Pd@HMAN particles with high porosity were obtained. As the mesoporous aluminosilica shells can serve as acid catalysts, and the Pd yolks can be applied to catalytic hydrogenation, the as-prepared Pd@HMAN can be used as a stable multifunctional catalyst for multistep reactions. Moreover, due to their adjustable pore parameters, Pd@HMAN after simple thermal treatment can be further applied in the size-selective hydrogenation.Ministry of Science and Technology of China 2011CB932403 National Natural Science Foundation of China 21131005 21021061 20925103 20923004 Fok Ying Tung Education Foundation 12101

A cationic surfactant assisted selective etching strategy to hollow mesoporous silica spheres

通讯作者地址: Zheng, NF (通讯作者), Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 2. Xiamen Univ, Dept Chem, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 电子邮件地址: [email protected] mesoporous silica spheres have recently attracted increasing attention. However, effective synthesis of uniform hollow mesoporous spheres with controllable well-defined pore structures for fundamental research and practical applications has remained a significant challenge. In this work, a straightforward and effective "cationic surfactant assisted selective etching" synthetic strategy was developed for the preparation of high-quality hollow mesoporous silica spheres with either wormhole-like or oriented mesoporous shell. The as-prepared hollow mesoporous silica spheres have large surface area, high pore volume, and controllable structure parameters. Our experiments demonstrated that cationic surfactant plays critical roles in forming the hollow mesoporous structure. A formation mechanism involving the etching of solid SiO2 accelerated by cationic surfactant followed by the redeposition of dissolved silica species directed by cationic surfactant is proposed. Furthermore, the strategy can be extended as a general strategy to transform silica-coated composite materials into yolk-shell structures with either wormhole-like or oriented mesoporous shell.NSFC 21021061,20925103 ,20923004 ,20871100 MOST of China 2009CB930703,2011CB932403 Fok Ying Tung Education Foundation 121011 NSF of Fujian 2009J06005 Key Scientific Project of Fujian Province 2009HZ0002-

Hollow Mesoporous Aluminosilica Spheres with Perpendicular Pore Channels as Catalytic Nanoreactors

通讯作者地址: Zheng, NF (通讯作者),Xiamen Univ, Coll Chem & Chem Engn, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Coll Chem & Chem Engn, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 2. Xiamen Univ, Coll Chem & Chem Engn, Dept Chem, Xiamen 361005, Peoples R China 3. Univ Calif Santa Barbara, Dept Chem Engn, Santa Barbara, CA 93106 USA 电子邮件地址: [email protected] design and synthesis of hollow/yolk-shell mesoporous structures with catalytically active ordered mesoporous shells can infuse new vitality into the applications of these attractive structures. In this study, we report that hollow/yolk-shell structures with catalytically active ordered mesoporous aluminosilica shells can be easily prepared by using silica spheres as the silica precursors. By simply treating with a hot alkaline solution in the presence of sodium aluminate (NaAlO2) and cetyltrimethylammonium bromide (CTAB), solid silica spheres can be directly converted into high-quality hollow mesoporous aluminosilica spheres with perpendicular pore channels. On the basis of the proposed formation mechanism of etching followed by co-assembly, the synthesis strategy developed in this work can be extended as a general strategy to prepare ordered mesoporous yolk-shell structures with diverse compositions and morphologies simply by replacing solid silica spheres with silica-coated nanocomposites. The reduction of 4-nitrophenol with yolk-shell structured Au@ordered mesoporous aluminosilica as the catalyst has clearly demonstrated that the highly permeable perpendicular pore channels of mesoporous aluminosilica can effectively prevent the catalytically active yolk from aggregating. Furthermore, with accessible acidity, the yolk-shell structured ordered mesoporous aluminosilica spheres containing Pd yolk exhibit high catalytic activity and recyclability In a one-pot two-step synthesis involving an acid catalysis and subsequent catalytic hydrogenation for desired benzimidazole derivative, which makes the proposed hollow ordered aluminosilica spheres a versatile and practicable scaffold for advanced catalytic nanoreactor systems.MOST of China 2011CB932403 2009CB930703 NSFC 21131005 21021061 20925103 Fok Ying Tung Education Foundation 121011 NSF of Fujian Province 2009J06005 U.S. National Science Foundation CHE-092465