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采用溶胶-凝胶法制备Al2O3含量为30%的SiO2-Al2O3复合氧化物,借助热重-差热分析(TG-DTA)、N2物理吸附、X射线粉末衍射(XRD)、傅里叶变换红外(FTIR)、氨程序升温脱附(NH3-TPD)以及吡啶吸附红外(Py-IR)光谱研究了500～900℃范围的热处理过程对SiO2-Al2O3结构、织构、酸性质的影响规律,并与四氢呋喃(THF)聚合性能进行关联.结果表明,经500℃热处理的SiO2-Al2O3拥有高的比表面积、大量的Si—O—Al键以及丰富的酸性中心.随着热处理温度升至700℃,SiO2-Al2O3的织构性质无显著变化,Si—O—Al键数量减少,SiO2-Al2O3总酸量和酸密度下降,强酸中心消失.至900℃时,比表面积和孔体积急剧下降,平均孔径显著增加,酸量和酸密度进一步减少.聚合反应结果表明,产品的收率和分子量均随热处理温度的升高呈现上升趋势.900℃时,产品收率最高,可达47%,聚合物分子量(Mn)为1710.
The SiO2-Al2O3 composite oxide with 30% Al2O3 content was prepared by sol-gel method. The properties of the composite were characterized by means of TG-DTA, N2 physical adsorption, X-ray powder diffraction (XRD), Fourier transform infrared (FTIR), ammonia temperature-programmed desorption (NH3-TPD) and pyridine-bound infrared (Py-IR) spectroscopy were used to study the influence of heat treatment process on the structure, texture and acidity of SiO2-Al2O3 And THF (THF) .The results show that SiO2-Al2O3 with high heat treatment at 500 ℃ has high specific surface area, large amount of Si-O-Al bonds and abundant acidic sites.With the increase of heat treatment temperature to 700 ℃, The texture properties of SiO2-Al2O3 showed no significant changes, the number of Si-O-Al bonds decreased, the total acidity and acid density of SiO2-Al2O3 decreased, and the strong acid sites disappeared.When 900 ℃, the specific surface area and pore volume decreased sharply, the average pore size And the acidity and acid density decreased further.The results of the polymerization showed that the yield and molecular weight of the product all showed an upward trend with the increase of the heat treatment temperature.The product yield was the highest at 900 ℃, up to 47%, the molecular weight of the polymer (Mn) of 1710.