MgO气凝胶制备及结构研究

Preparation and Structural Study of Magnesium Oxide Aerogels

摘要:

以甲醇镁为镁源,甲醇和去离子水为溶剂,采用溶胶-凝胶法结合乙醇超临界干燥工艺制备MgO气凝胶,考察去离子水、甲醇、丙三醇对MgO气凝胶凝胶时间及比表面积的影响,采用红外光谱(FTIR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、氮气吸脱附测试仪等对其结构及形貌进行表征,并且利用同步辐射小角X射线散射(SAXS)对其进行了分形结构分析。结果表明：MgO气凝胶具有丰富的网络骨架结构、高的孔隙率(98%)、高的比表面积(904.9 m₂/g)、较低的密度(0.055 g/cm₃),平均孔径为19.6 nm,属典型的介孔材料,SAXS测试显示MgO气凝胶分形维数为2.32,表面粗糙且疏松,具有明显的孔分形结构。

Abstract:

_{:Magnesium oxide aerogels were made by sol-gel process using magnesium methoxide as precursor,methanol and deionized water as solvents followed by ethanol supercritical fluid drying. The influences of the different factors on the gel time and the specific surface area of magnesium oxide aerogels were studied, and the structure and morphology were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM) and X-ray diffraction (XRD), and the Small Angle X-ray Scatter (SAXS) was utilized to determine the fractural structure of the magnesium oxide aerogels. The results show that MgO aerogels are typical mesoporous materials with the average pore size of 19.6 nmand possessrich network,high porosity(98%), high specific surface area(904.9 m2/g) and low density(0.055 g/cm3). The resultsof SAXS analysis show that the fractal dimension of the MgO aerogels is 2.32 in high q area which proves the existence of rough surface and pore fractal structure.}