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提出了一种(NH4)2Si F6处理提高SBA-15介孔材料水热稳定性的改良方法.采用SBA-15介孔材料中预引入Al3+离子,再进行1%SiO 2计量的(NH4)2Si F6处理,最后用强酸洗脱预引入的Al3+.结果显示,由此处理的SBA-15材料,其水热稳定性明显优于相同条件下未预引入Al3+时(NH4)2Si F6处理的样品.两者在800°C、100%水蒸气处理12 h后,虽然均能很好保持其介观有序度、形貌及六方孔道结构,但前者的比表面积可高达271 m2/g,而后者仅为224 m2/g.表明Al3+离子介入能大幅度提升(NH4)2Si F6处理对SBA-15介孔材料的稳定化作用.这主要得益于预引入的骨架Al3+在保障(NH4)2Si F6处理修复SBA-15材料表面缺陷和进行表面疏水化、提升其水热稳定性的同时,能减缓(NH4)2Si F6释放的多余F离子对SBA-15材料骨架的刻蚀破坏作用.Al3+离子介入的这种提升作用与其引入方式和SBA-15材料所经受的温度密切相关.
(NH4) 2Si F6 to improve the hydrothermal stability of SBA-15 mesoporous materials is proposed.Using SBA-15 mesoporous materials which are pre-introduced with Al3 + ions and then with 1% SiO2, F6 and finally with strong acid.The results showed that the hydrothermal stability of the SBA-15 material treated by this method was better than that of the (NH4) 2SiF6-treated sample under the same conditions. Both were able to maintain their mesoscopic order, morphology and hexagonal pore structure well at 800 ° C and 100% steam for 12 h, but the former had a specific surface area of up to 271 m2 / g, while the latter Only 224 m2 / g, indicating that Al3 + intercalation can greatly enhance the stabilizing effect of (NH4) 2SiF6 on the SBA-15 mesoporous materials, mainly due to the pre-introduced Al3 + The surface damage and surface hydrophobization of SBA-15 material can be repaired and the hydrothermal stability of SBA-15 material can be repaired. Meanwhile, the destructive effect of excess F ions released by (NH4) 2SiF6 on the skeleton of SBA-15 material can be retarded. This lifting effect is closely related to the way it is introduced and the temperature experienced by the SBA-15 material.