W掺杂SiO2介孔材料的制备与表征

以非离子表面活性剂三嵌段共聚物P123为模板剂、正硅酸乙酯(TEOS)为硅源、钨酸钠(Na2WO4·2H2O)为钨源, 通过水热法一步合成了W掺杂的二氧化硅介孔材料W-SiO2, 并通过XRD、HRTEM、EDX、FT-IR、N2吸附-脱附等表征手段, 考察了随着W含量增加, W-SiO2介孔材料结构的变化规律以及钨物种在材料中的存在状态. 结果表明, 当WO3含量w(WO3)约为10%时, W-SiO2中的钨物种是高度分散进入介孔骨架,形成W-O-Si 键; 当w(WO3)=20%时, 样品中开始有未掺入到SiO2骨架中WO3的结晶出现; 当w(WO3)约60%时, W-SiO2 样品能保持很好的介孔孔道结构, 更高含量WO3掺入将破坏二氧化硅介孔结构.

Preparation and Characterization of Mesoporous Silicon Dioxide Doped with Tungsten

Mesoporous silicon dioxide materials doped with tungsten were synthesized by hydrothermal technique, employing nonionic surfactant block copolymer (P123) as template, ethyl silicate (TEOS) as inorganic precursor and sodium tungstate (Na2WO4·2H2O) as the source of tungsten. Several methods such as XRD, HRTEM, EDX, FT-IR and nitrogen adsorption-desorption isotherms were employed to characterize the structure of the W-doped SiO2 mesoporous materials and the state of tungsten in the mesoporous materials. The results showed that the tungsten species in W-SiO2 was highly dispersed when the amount of WO3 was less than 10%; when the amount of WO3 was 20%, some WO3 crystal could be detected in W-SiO2. When the amount of WO3 was lower than 60%, well organized pore structures could still be detected in W-SiO2 material. As the amount of WO3 was more than 60%, the mesoprous structure was collapsed.