MFI沸石前驱体和硅酸钠共组装制备水热稳定的管状介孔分子筛  

Synthesis of Hydrothermally Stable Mesoporous Aluminosilicates with Tubular Morphology from MFI Zeolitic Precursors and Sodium Silicates

作　　者：郑均林[1] 张晔[1] 吴东[1] 孙予罕[1] 

机构地区：[1]中国科学院山西煤炭化学研究所,煤转化国家重点实验室,太原030001

出　　处：《化学学报》2004年第14期1357-1361,J006,共6页Acta Chimica Sinica

基　　金：国家重点基础研究专项经费 (No .G2 0 0 0 0 4 80 0 1 );国家重点自然科学基金 (No.2 99730 57);山西省自然科学基金 (No .991 0 2 3)资助项目

摘　　要：在CTAB模板剂的作用下 ,硅酸钠、铝酸钠和含有MFI纳米簇的沸石前躯体溶液通过S+ I-路线共组装得到了高水热稳定的管状形貌介孔分子筛 .XRD结果显示样品具有类似MCM 41的规则排列六方孔道结构 .在沸水中处理 15 0h后 ,介孔特征仍然保留 ,显示出很好的水热稳定性 .综合SEM和TEM的观察结果 ,此介孔分子筛具有中空的管状形貌 ,平均管长2 .0 μm ,平均直径为 0 .3 0 μm .含有MFI纳米簇的沸石前躯体作为硅源的一部分加入体系中 ,MFI纳米簇伴随来自于硅酸钠的可溶性硅物种共同进入分子筛骨架 ,在提高水热稳定性的同时 ,没有降低六方纳米孔道的规整度 ,也没有对分子筛形貌调变带来不利影响 .MFI纳米簇中 ,硅氧四面体和铝氧四面体的紧密联结方式在进入分子筛骨架时得以保留是水热稳定性提高的主要原因 .作为硅源的另一部分加入的硅酸钠 ,使合成体系pH值足够高 (pH >13 ) ,加入H2 SO4调节体系pH值到10 ,管状形貌的介孔分子筛在逐步中和过程中形成 .通过这种特殊的共组装方法合成介孔分子筛 ,在获得中空的管状形貌的同时显著提高水热稳定性 ,为这种管状形貌介孔分子筛的应用奠定了基础 .Hydrothermally stable mesoporous aluminosilicates with hollow tubular morphology and hexagonal nanochannels were prepared through co-assembly of sodium silicates, sodium aluminates and MFI aluminosilicate precursors. The XRD results indicated that the synthesized materials were well-ordered hexagonal mesostructures of MCM-41 type. The highly regular hexagonal mesostructures could survive 150 h age in boiling water, exhibiting good hydrothermal stability. Combining the SEM and TEM investigations, the as-made materials showed hollow tubular morphology with mean diameter of 0.30 μm and average length of 2.0 μm. MFI aluminosilicate precursors as precursor (I) enhanced the hydrothermal stability without compromising the ability to tailor the second-order structure. Sodium silicates donating soluble silica species as precursor (II) made the assembly system strongly alkaline, and hollow tubular morphology of mesoporous aluminosilicates evolved after the pH value of the mixture was adjusted to 10 by adding proper amount of H 2SO 4. Under the direction of CTAB template, these two different precursors cooperated with each other and condensed together in the assembly process. Combining the properties of good hydrothermal stability, tubular morphology and high surface areas, these mesostructured materials can find potential applications in catalysis, separation and optic electronics.

关 键 词：沸石前驱体 硅酸钠 共组装 制备 水热稳定性 管状形貌 介孔分子筛 硅酸钠 铝酸钠 MFI纳米簇 

分 类 号：O643.3[理学—物理化学]