Zr-Ce-SBA-15介孔材料的合成和形貌调控

Synthesis and Morphological Control of Zr-Ce-SBA-15 Mesoporous Materials

摘要:

以正硅酸乙酯(TEOS)为硅源，P123为模板剂，氯化氧锆(ZrOCl2·8H2O)和硝酸亚铈(Ce(NO3)3·6H2O)为锆、铈前驱体，在不外加无机酸的条件下，利用无机前驱盐自身水解产生的弱酸性环境，水热法一步合成Zr-Ce-SBA-15介孔材料。通过改变起始物料配比和调节合成温度可以实现对产物的形貌进行有效控制。利用小角X射线衍射 (LXRD)、透射电子显微镜 (TEM)、扫描电子显微镜 (SEM)、电感耦合等离子体原子发射光谱 (ICP-AES)和氮气吸附等手段对所合成的样品进行了表征。结果表明：在 nZr(Ce):nSi物质量的比分别为 0.03，0.05，0.10时，合成的材料具有类似于SBA-15高度有序的二维六方相介孔结构，锆、铈物种被成功引入SBA-15材料的骨架中。当nZr(Ce):nSi摩尔比为0.05，晶化温度为100 ℃时，Zr-Ce-SBA-15表现为六方板状形貌。随着晶化温度的升高，Zr-Ce-SBA-15的形貌由六方板状转变成圆盘状

Abstract:

The highly ordered mesoporous materials Zr-Ce-SBA-15 were synthesized by a hydrothermal route using tetraethyl orthosilicate (TEOS) as a silica source, Pluronic P123 as a template, zirconyl chloride and cerous nitrate as precursors under a moderate acidic condition. The main strategy of this method was to utilize the acidity self-generated in the aqueous solutions, where no addition of mineral acids was necessary. Through a simple adjustment of the initial reactant molar ratio in the synthesis gel and the crystallization temperature, the morphology of mesoporous materials could be controlled efficaciously. The as-synthesized materials were characterized by XRD, TEM, SEM, inductively coupled plasma atomic emission spectrometry (ICP-AES) and N2 adsorption. Results indicate that the Zr and Ce species are incorporated into the framework of SBA-15. The obtained Zr-Ce-SBA-15 materials with different nZr(Ce):nSi molar ratios of 0.03, 0.05 and 0.10 possess 2D-hexagonal P6mm mesoporous structure similar to SBA-15. In addition, the morphology of the bimetallic Zr-Ce-SBA-15 mesoporous materials varies with different nZr(Ce):nSi molar ratios and different crystallization temperatures. When the nZr(Ce):nSi ratio is 0.05 and the crystallization temperature 100 oC, the material of Zr-Ce-SBA-15 displays hexagonal-platelet morphology. With increasing of crystallization temperature, the morphology of the bimetallic Zr-Ce-SBA-15 mesoporous materials is changed from hexagonal-platelet to circular-platelet.