多金属氧酸盐/介孔分子筛杂化材料的制备与表征

采用嵌段共聚物模板P123和缺位Keggin结构的多金属氧酸盐K₈SiW₁₁O₃₉•12H₂O, 由溶胶-凝胶法合成了具有类六方结构的SiW₁₁/SBA-15杂化介孔分子筛材料, 并通过X射线衍射(XRD)、傅立叶变换红外光谱(FT-IR)、紫外漫反射光谱(UV/DRS)、电感耦合等离子原子发射光谱(ICP-AES)、低温N₂吸附、透射电子显微镜(TEM)等手段对其进行了表征. 结果表明, 杂化材料中不仅规整均一的类六方介孔结构得以保持, 而且多金属氧酸盐的Keggin单元保留完整(含量达25%左右), 并共价键联于介孔材料的孔道内部. 稳定性实验表明, 杂化材料中多金属氧酸盐在水中的流失率远低于一般浸渍法制备的样品.

Preparation and Characterization of Hybrid Polyoxometalate-mesoporous Molecular Sieve Materials

Hybrid mesoporous molecular sieve material based on lacunary polyoxometalate, K₈SiW₁₁O₃₉•12H₂O, was prepared via sol-gel method as well as block copolymer templating technique. The as-obtained SiW₁₁/SBA-15 composites were characterized by FT-IR, UV/DRS, XRD, ICP-AES, N₂ adsorption-desorption and TEM. The results indicate that not only a hexagonal-like packing of channels with homogeneous pore diameter is maintained in the hybrid materials, but also Keggin units remain perfectly with a content of ～25% and are grafted onto the pore wall of mesoporous silica by covalent linkage. The immobilization degree of polyoxometalate was measured in water at 25 ℃ and compared with those of the samples prepared by impregnation. It is shown that the lost percent of polyoxometalate in the hybrid material is much less than those of the impregnated samples.