A three-dimensional mesoporous titanosilicate support for gold nanoparticles: vapor-phase epoxidation of propene with high conversion.
A three-dimensional mesoporous titanosilicate support for gold nanoparticles: vapor-phase epoxidation of propene with high conversion.
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DOI：
10.1002/anie.200352900
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发表时间：
2004-03
影响因子：
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通讯作者：
A. Sinha;S. Seelan;S. Tsubota;M. Haruta
中科院分区：
文献类型：
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作者：
A. Sinha;S. Seelan;S. Tsubota;M. Haruta
2θ= 1.0-2.08，这对于无序介观结构材料是典型的。这样的XRD图案类似于具有短的、互连的、虫孔状中孔的3D网络的介观结构的MSU-1、[11] UTD-1、[12] HMS、[13]和KIT-1、[14]的那些。高分辨率的TEM图像（图1a，插图）证实了这种均匀的，3D网络的存在，这些网络由短的相互连接的虫洞状通道组成。漫反射UV光谱（图1 B）显示，Ti浓度高达6.0 mol%的样品在220-245 nm处显示出吸收峰，这是由于四面体配位的Ti中心，即大多数钛以孤立的四面体物质存在于二氧化硅基质中。样品没有产生高于300 nm的峰，这表明不存在任何本体二氧化钛。具有最高钛浓度（8摩尔%）的样品显示两个清晰的峰，一个在235 nm处，归因于四面体配位的钛，另一个在272 nm处，归因于更高的（5-，6-）配位的Ti。对钛含量为2- 6mol%的钛硅酸盐的XPS分析表明，Ti 2 p3/2芯能级的结合能（BE）约为460.0eV，这表明在二氧化硅晶格中完全孤立的Ti位点的四面体配位。[15]然而，在较高的Ti含量（8摩尔%）的BE到459.3 eV的位移表明不完全隔离的Ti网站高Ti含量。[16]对于具有八面体配位的聚集的Ti，BE约为458.5eV。[16]BET表面积、Barrett-Joyner-Halenda（BJH）孔径和中孔体积分别为838-896 m2 gcm-1、7.1-9.2 nm和1.0-1.4 cm 3 gcm-1。通过DP方法将金纳米颗粒沉积在所有载体上。在所得材料上的金负载量为0.3- 0.4wt%，并且良好分散的Au纳米颗粒的平均尺寸为3.0 ± 1.0nm。EXAFS/XANES分析表明，Au纳米粒子是完全金属的性质。
2θ= 1.0–2.08, which is typical for disordered mesostructured materials. Such XRD patterns are similar to those of mesostructured MSU-1,[11] UTD-1,[12] HMS,[13] and KIT-1,[14] which have 3D networks of short, interconnected, wormholelike mesopores. High-resolution TEM images (Figure1a, inset) confirmed the presence of such uniform, 3D networks of short interconnected wormholelike channels. The diffusereflectance UV spectra (Figure 1 b) show that samples with Ti concentrations of up to 6.0 mol% exhibit absorbance peaks at 220–245 nm, which result from tetrahedrally coordinated Ti centers, that is, most of the titanium is present as isolated tetrahedral species in the silica matrix. The samples yielded no peaks above 300 nm, which indicates the absence of any bulk titania. The sample with the highest titanium concentration (8 mol%) shows two clear peaks, one at 235 nm due to tetrahedrallly coordinated titanium, and another at 272 nm, attributable to higher (5-, 6-) coordinate Ti. The XPS analysis of titanosilicates with 2–6 mol% titanium content showed that the binding energy (BE) of the Ti 2p3/2 core level is about 460.0 eV, which indicates tetrahedral coordination of completely isolated Ti sites in the silica lattice.[15] However, the shift of the BE to 459.3 eV at higher Ti content (8 mol%) indicates incomplete isolation of Ti sites for high Ti content.[16] The BE is about 458.5 eV for aggregated Ti with octahedral coordination.[16] The BET surface area, Barrett–Joyner–Halenda (BJH) pore diameter, and mesopore volume were 838–896 m2 gÀ1, 7.1–9.2 nm, and 1.0–1.4 cm3 gÀ1, respectively. Gold nanoparticles were deposited on all the supports by the DP method. The gold loading on the resultant materials was 0.3–0.4 wt%, and the average size of the well-dispersed Au nanoparticles was 3.0 Æ 1.0 nm. An EXAFS/XANES analysis showed that the Au nanoparticles were completely metallic in nature.