MgO/γ-Al_2O_3烷氧基化催化剂制备及结构与性能研究

在γ Al2 O3 载体上浸渍Mg (NO3 ) 2 ·6H2 O ,然后分别经 40 0、45 0和 5 0 0℃焙烧制成MgO/γ Al2 O3 固体碱催化剂。结果表明 ,MgO在γ Al2 O3 载体表面具有单层分散性质 ,当MgO的负载量低于某一数值 (阈值 )时 ,从样品的X光粉末衍射谱图上观察不到MgO的特征衍射峰 ,负载量超过阈值时开始出现MgO的晶相 ,且MgO的XRD衍射峰强度随MgO的负载量的增加而增加 ,其单分散阈值为 0 0 80 gMgO/ 10 0m2 γ Al2 O3 。应用CO2 TPD技术测定了样品的碱性 ,结果表明 ,样品在接近阈值时其碱量大幅度增加 ,碱强度提高。样品的比表面最初随着MgO负载量的增加而下降 ,但达阈值后基本保持不变。

Modelling and Characterization of Monolayer Dispersion of Magnesium Oxide on γ-Al2O3

Al 2O 3-supported MgO catalysts with different MgO loading were prepared by impregnating γ-Al 2O 3 with magnesium nitrate solution and then calcining at 400,450 and 500 ℃ respectively.Resulting MgO/γ-Al 2O 3 catalysts were characterized by XRD.It is proved that MgO on γ-Al 2O 3 has the monolayer character,and experimental results show that the utmost monolayer dispersion capacity (threshold) of MgO on γ-Al 2O 3 is 0.080 g MgO/100 m 2 γ-Al 2O 3.Below the threshold,the MgO crystalline was not found in the XRD patterns.The intensity of diffraction peaks of MgO crystalline increases with increasing MgO loading.The base amount of the catalyst with the threshold loading is much greater than that of γ-Al 2O 3 carrier,and its base strength is also higher.