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采用浸渍法和沉积-沉淀法对有序六方介孔氧化硅分子筛SBA-15进行铈改性。通过X射线衍射、Fourier红外光谱、透射电镜、N2吸附-脱附、X射线光电子能谱和感应耦合等离子体原子发射光谱等对复合材料Ce-SBA-15的介孔结构、铈元素的含量及其化学态进行了表征。结果表明:以硫酸铈为铈源的沉积-沉淀法即使在小的负载量下,铈元素在载体中的分散性很差;而以醋酸铈为铈源的浸渍法能使铈元素在载体中均匀分散,得到的复合材料保持载体SBA-5高度有序的二维六方孔道结构,未检测到氧化铈晶相峰。以醋酸铈为铈源时,当铈负载量达到10.74%时,浸渍法制备的载体的比表面积为368.3m2/g。分子筛中引入的铈元素主要以正四价态形式存在。
The hexagonal modified mesoporous silica SBA-15 was modified by impregnation and deposition-precipitation. The mesoporous structure, cerium content and the content of cerium in Ce-SBA-15 composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N2 adsorption-desorption, X-ray photoelectron spectroscopy and inductively coupled plasma atomic emission spectrometry Its chemical state was characterized. The results show that the deposition of cerium sulfate cerium source - precipitation method even at a small load, the dispersion of cerium in the carrier poor; and cerium acetate cerium source impregnation method enables the cerium element in the carrier Uniformly dispersed. The obtained composite material maintains the highly ordered two-dimensional hexagonal pore structure of the carrier SBA-5, and no cerium oxide crystal phase peak is detected. When cerium acetate was used as cerium source, the specific surface area of the support prepared by impregnation was 368.3m2 / g when the loading of cerium reached 10.74%. The cerium element introduced in the molecular sieve exists mainly in the form of a positive tetravalent state.