Seeding-free aqueous synthesis of zeolitic imidazolate framework-8 membranes: How to trigger preferential heterogeneous nucleation and membrane growth in aqueous rapid reaction solution
Seeding-free aqueous synthesis of zeolitic imidazolate framework-8 membranes: How to trigger preferential heterogeneous nucleation and membrane growth in aqueous rapid reaction solution
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DOI：
10.1016/j.memsci.2014.08.038
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发表时间：
2014-12
影响因子：
9.5
通讯作者：
S. Tanaka;T. Shimada;Kosuke Fujita;Yoshikazu Miyake;Koji Kida;K. Yogo;J. Denayer;Miki Sugita;T. Takewaki
中科院分区：
文献类型：
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作者：
S. Tanaka;T. Shimada;Kosuke Fujita;Yoshikazu Miyake;Koji Kida;K. Yogo;J. Denayer;Miki Sugita;T. Takewaki
沸石咪唑盐框架（ZIFs）由于具有类似沸石的永久孔隙和可调节的均匀微孔，在膜分离应用中受到了广泛的关注。尽管室温水相合成为zif的合成开辟了一条环保、高效的途径，但它也给膜的制备带来了挑战，包括不可避免的均质成核。尽管人们普遍认识到ZIF的配位化学与沸石的共价化学有着根本的不同，但许多在水体系中制备的ZIF膜是基于传统的沸石膜的二次种子生长技术。在这项研究中，我们首先应用了载体表面活化方法来促进非均相成核，然后在水体系中生长晶体。利用乙酸锌在α-氧化铝多孔载体上成功生长了连续生长良好的ZIF-8膜，具有较高的氢透性6.9×10−7mol/m2s Pa，对氢/甲烷的理想分离选择性为13.6。羧酸官能团的羧酸官能团与锌-醋酸盐的相互作用是控制非均相成核和膜生长的关键。避免播种过程和减少有机溶剂的使用可以为改善膜制备的可重复、可扩展和可商业化的工艺配置提供潜力。
Zeolitic imidazolate frameworks (ZIFs) have received attention for membrane separation applications due to their zeolite-like permanent porosity and tunable uniformly-sized micropores. Although aqueous room temperature synthesis has apparently opened up environmental friendly and efficient ways to synthesize ZIFs, it poses challenges for membrane preparation including unavoidable homogeneous nucleation. Many ZIF membranes preparedin an aqueous systemare based on conventional secondary seeded growth techniques for zeolite membranes in spite of well-recognizing that the coordination chemistry of ZIFs is fundamentally different from the covalent chemistry of zeolites. In this study, we first applied a support-surface activation approach to promote heterogeneous nucleation followed by crystal growthin the aqueous system. Continuous well-intergrown ZIF-8 membranes were successfully grown onα-alumina porous support using zinc acetate and showed relatively-high hydrogen permeance of 6.9×10−7mol/m2s Pa with corresponding ideal separation selectivity of 13.6 for the hydrogen/methane. The competitive interaction between the coordination of constructing framework and zinc–acetate interaction by carboxylate functionality of acetate anions is essential to control heterogeneous nucleation and membrane growth. Avoiding the seeding process and reducing the use of organic solvents can provide potential for improving a reproducible, scalable, and commercializable process configuration for membrane preparation.