低堆密度大孔体积γ-Al_2O_3的制备与表征

Preparation and Characterization of γ-Al_2O_3 with Low Bulk Density and Large Pore Volume

以Al2(SO4)3和NH3.H2O为原料合成了拟薄水铝石,经煅烧得到γ-Al2O3;采用X射线衍射、透射电子显微镜、热重-示差扫描量热和压汞法等方法对拟薄水铝石和γ-Al2O3进行了表征。表征结果显示,低堆密度大孔体积的γ-Al2O3的较佳制备条件为:反应液的pH为8、Al3+浓度为0.9mol/L、反应时间60min、反应温度70℃、NH3.H2O的质量分数为21%、800℃下煅烧5h。在此条件下制备的γ-Al2O3的比表面积为207.43m2/g、总孔体积为2.93mL/g、堆密度为0.23g/mL,且具有双孔分布,其中孔径大于100nm的孔的体积占总孔体积的58.91%,适用于大分子脱氢催化剂的载体。

Pseudo-boehmite and γ-Al2O3 was prepared from Al2 （SO4 ）3 and NH3 · H2O. XRD, TEM, TG-DSC and mercury porosimeter were used in characterization of both pseudo-boehmite and γ-Al2O3 Under optimal conditions for preparation of low bulk density and large pore volume γ-Al2O3： reaction solution pH 8, Al3^＋ concentration 0.9 moL/L,reaction time 60 min, reaction temperature 70 ℃, NH3 · H2O mass fraction 21%, calcination temperature 800 ℃ and calcination time 5 h, specific surface area of the obtained γ-Al2O3 is 207.43 m^2/g, pore volume is 2.93 mL/g and bulk density is 0.23 g/mL. The obtained γ-Al2O3 possesses bimodal pore size distribution. Pores with radius at least 100 nm is more than 58.91%. The ,γ-Al2O3 can be used as support of catalyst for dehydrogenation of large molecules.