Hierarchical mesoporous zeolites: direct self-assembly synthesis in a conventional surfactant solution by kinetic control over the zeolite seed formation.
Hierarchical mesoporous zeolites: direct self-assembly synthesis in a conventional surfactant solution by kinetic control over the zeolite seed formation.
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DOI：
10.1002/chem.201101401
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发表时间：
2011-12
期刊：
影响因子：
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通讯作者：
Yanxin Zhu;Zile Hua;Jian Zhou;Lijun Wang;Jinjin Zhao;Yun Gong;W. Wu;M. Ruan;Jianlin Shi
中科院分区：
文献类型：
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作者：
Yanxin Zhu;Zile Hua;Jian Zhou;Lijun Wang;Jinjin Zhao;Yun Gong;W. Wu;M. Ruan;Jianlin Shi
通过对沸石晶种形成的动力学控制，我们报道了以十六烷基三甲基溴化铵(CTAB)为软模板剂，在常规溶液路线中直接合成分级介孔分子筛。具有高度聚合度的纳米、亚纳米晶型沸石种子对于防止在CTAB和一定量的乙醇存在下形成单独的无定形介孔相以及防止中间相和沸石晶体之间的相分离是必不可少的。提出并详细讨论了分子筛在溶液过程中的形成机理，包括母液老化的影响、亚纳米沸石晶种的形成及其与CTAB的自组装效应以及乙醇的作用。所制备的介孔ZSM-5沸石对涉及大分子的羟醛缩合反应，特别是在合成维西德基方面，表现出比传统沸石更高的催化活性。
By kinetic control over the zeolite seed formation, we report the direct fabrication of hierarchical mesoporous zeolites using hexadecyl trimethyl ammonium bromide (CTAB) as the soft template in a conventional solution route. Nanometer-sized, subnanocrystal-type zeolite seeds with a high degree of polymerization are essential to prevent the formation of a separate amorphous mesoporous phase and the phase separation between the mesophase and zeolite crystals in the presence of CTAB and a certain amount of ethanol. The mechanisms for the formation of hierarchically porous zeolites in the solution process, including the effect of mother liquid aging, formation of subnanocrystal zeolite seeds and their self-assembly effect with CTAB, and the role of ethanol are proposed and discussed in detail. The prepared mesoporous ZSM-5 zeolite showed much higher catalytic activity than conventional counterparts for aldol condensations involving large molecules, especially in the synthesis of vesidryl.