Multilayered SiO2/TiO2 nanosol particles in two-dimensional aluminosilicate catalyst-support
Multilayered SiO2/TiO2 nanosol particles in two-dimensional aluminosilicate catalyst-support
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DOI：
10.1021/jp9815863
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发表时间：
1998-07-30
影响因子：
3.3
通讯作者：
Yoon, JB
中科院分区：
文献类型：
--
作者：
Choy, JH;Park, JH;Yoon, JB
利用带正电的SiO2/TiO 2溶胶粒子与蒙脱土中的Na+离子进行离子交换反应，制备了一种新型的蒙脱土层与SiO2/TiO 2溶胶粒子层间一对一互层的层状纳米复合材料。离子交换反应在45、60和75 ℃的三个不同温度下通过将1重量% Na+蒙脱石的水悬浮液与Si/Ti摩尔比选择为20/2的SiO2/TiO 2溶胶溶液混合来进行。根据粉末X射线衍射分析，发现在400 ℃下煅烧的层状纳米复合材料的基底间距随着离子交换反应温度从40 ℃升高到60 ℃和75 ℃而从35.4埃增加到47.3埃和60.0埃。由N2吸附-脱附等温线估算出的BET比表面积、Langmuir比表面积和孔隙率均随基间距的增大而增大，最大BET比表面积和孔隙率分别为683 m2/g和0.50 mL/g。尽管基底间距的大增量，多孔性质，如比表面积，孔隙率，和孔径，那些分别从t-图和化学位移的NMR计算，被确定为几乎是恒定的。从紫外/维斯光谱，吸收边的蓝移观察到，表明在夹层中的TiO 2溶胶粒子的量子尺寸。因此，提出了产品是插层型纳米复合材料的SiO2/TiO 2纳米粒子在蒙脱土的层间空间的多层结构。
A new layered nanocomposite, which is one-to-one interstratified with a montmorillonite layer and a mixed SiO2/TiO2 sol particle one, has been prepared by ion exchange reaction of the Na+ ion in montmorillonite with the positively charged SiO2/TiO2 sol particles. The ion exchange reaction was performed at three different temperatures of 45, 60, and 75 degrees C by mixing an aqueous suspension of 1 wt % Na+ montmorillonite with SiO2/TiO2 sol solution where the molar ratio of Si/Ti was selected as 20/2. According to the powder X-ray diffraction analysis, the basal spacings of layered nanocomposites calcined at 400 degrees C were found to increase from 35.4 Angstrom, to 47.3 Angstrom, and to 60.0 Angstrom as the ion exchange reaction temperature was raised from 40 degrees C, to 60 degrees C, and to 75 degrees C. Their BET and Langmuir specific surface areas and porosities, estimated from nitrogen adsorption-desorption isotherms, become larger with the increment of basal spacing, and the highest BET specific surface area and the largest porosity are found to be 683 m(2)/g and 0.50 mL/g, respectively. Despite the large increment of the basal spacing, the porous properties such as specific surface areas, porosities, and pore sizes, those which are calculated from t-plots and chemical shift of Xe-129 NMR, respectively, are determined to be almost constant. From the UV/vis spectra, the blue shift of the absorption edge was observed, indicating that the TiO2 sol particles in the interlayer are quantum sized. It is therefore proposed that the products are intercalation-type nanocomposites with the multistacked structure of the SiO2/TiO2 nanoparticles in the interlayer space of montmorillonite.