金属离子Al^(3+)对SBA-15分子筛形貌的调控作用研究

Influence of Al^(3+) ions on the morphology of mesoporous SBA-15

以异丙醇铝为铝源,在高浓度酸性环境下,通过Al3+调控SBA-15的形貌与性质。在强酸条件下,所得样品的实际n(Si)∶n(Al)都远高于配料n(Si)∶n(Al),且样品的Brnsted酸为0,Lewis酸也较低,铝元素无论是以嫁接还是骨架配位形式都难以嵌入到SBA-15的体相中。随着配料n(Si)∶n(Al)降低,SBA-15由线粒状向端粒颗粒状发展;当配料n(Si)∶n(Al)=5和2.5时,SBA-15仍然具有有序结构,但是二维有序性不强。当n(Si)∶n(Al)=20时,所得材料具有最高的比表面积、孔容及孔径,其值分别为827m2/g,1.25cm3/g,6.06nm。无机硅物种和有机高分子表面活性剂相互作用及体系Al3+浓度导致的胶束空间限制这两方面是Al3+对SBA-15的形貌形成的原因。

In high-concentration acidic conditions,using isopropanol aluminum as aluminum source,Al3＋ ions were used to adjust morphology and properties of mesoporous SBA-15.In high-concentration acidic,the experimental ratio of n（Si） ∶ n（Al） of samples is far greater than that of theoretical,and the Bronsted acid of samples is 0,Lewis acid is low.Al3＋ ions are unable to embed into mesoporous SBA-15 whether by grafting or skeleton forms of coordination As the ratio of n（Si） ∶ n（Al）decreasing,the morphology of mesoporous SBA-15 is developed from line of granular to telomere granular.The morphology of mesoporous SBA-15 still has ordered structures when the ratio of n（Si） ∶ n（A1） is 5 or 2.5,but the two-dimensional order is not obvious.When the ratio of n（Si） ∶ n（Al） is 20,the material has the highest specific surface area,pore volume and poresize,their value are 827 m2/g,1.25 cm3/g,6.06 nm,respectively.Interaction of inorganic silicon with organic polymer surfactant and micellar space constraints caused by concentration of system are the two reasons for influence of Al3＋ ions on the morphology of mesoporous SBA-15.