Fabrication of hierarchical ZSM-5 zeolite membranes for ultrafiltration

doi:10.11949/j.issn.0438-1157.20170451

Abstract

Abstract:

Hierarchical ZSM-5 zeolite membranes were synthesized through secondary growth method in the presence of small amount of cetyltrimethylammonium bromide (CTAB). The results show that CTAB spherical micelles and molecular sieve particles self-assembled to form ordered mesoporous structure. At the same time, the presence of CTAB micelles and hydrophobic long chains suppresses the growth of crystals. By adjusting the CTAB/SiO₂ molar ratio, synthesis temperature or crystallization time, the crystal grain size and the crosslinking degree of the zeolite membranes were changed remarkably to realize the simple and effective regulation of the average pore size, ranging from 7 to 30 nm. Under the synthesis at 180℃ for 20 h and the CTAB/SiO₂ molar ratio about 0.05, the obtained zeolite membrane exhibited a high water permeability of 138 kg·m^-2·h^-1·MPa^-1, and a molecular weight cut-off(MWCO) of 28500, corresponding to the average pore size of 7.39 nm, achieving the standard of small aperture ultrafiltration.

Key words: zeolite, membrane, hierarchical, ultrafiltration, CTAB

摘要：

利用二次生长法，以十六烷基三甲基溴化铵（CTAB）为结构导向剂，一步水热合成了多级孔道ZSM-5分子筛膜。结果表明，CTAB球形胶束与分子筛颗粒自组装形成了介孔结构，同时，CTAB胶束及疏水长链抑制了晶体的长大。通过调整CTAB/SiO₂摩尔比、合成温度及晶化时间等制膜条件，改变分子筛膜的晶体颗粒尺寸及膜层交联度，实现了分子筛膜介孔结构的有效调节，其孔径范围7~30 nm。在CTAB/SiO₂摩尔比为0.05、合成温度180℃、时间20 h下，多级孔分子筛膜纯水渗透通量达到138 kg·m^-2·h^-1·MPa^-1，截留分子量28500，对应平均孔径7.39 nm，达到小孔径超滤的标准。

关键词: 分子筛, 膜, 多级孔, 超滤, CTAB

CLC Number:

TQ028.8

YAO Xun, PENG Li, XU Xiaohan, ZHANG Chun, GU Xuehong. Fabrication of hierarchical ZSM-5 zeolite membranes for ultrafiltration[J]. CIESC Journal, 2017, 68(11): 4351-4358.

姚迅, 彭莉, 徐晓涵, 张春, 顾学红. 多级孔道ZSM-5分子筛超滤膜的制备[J]. 化工学报, 2017, 68(11): 4351-4358.

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