(234e) Design Strategies for the Preparation of Metal-Organic Framework Membranes

In recent years, metal-organic frameworks (MOFs), a new class of nanoporous crystalline materials, has aroused wide attention for their superior functions in many research areas, in particular, for gas and liquid separations.^[1-5] MOF membrane, as a typical separation media, often comprises a thin MOF layer integrated with a porous substrate. Therefore, a strong interaction between the MOF crystal and support is a principal requirement for preparing high quality MOF membranes.^[6] Unfortunately, it has been confirmed that the heterogeneous nucleation density of MOF crystals on ceramic supports is very low, which makes it extremely difficult to prepare defect-free MOF membranes by in situ solvothermal methods.^[2-3] Therefore, additional steps, such as support modification or seeding processes,^[1-3] are always required for membrane fabrication. However, up to now, few works are aware of the importance of the match between MOFs and inorganic supports.^[1] Here we reported a robust strategy to prepare integrated MOF membranes using in situ solvothermal methods. According to the metal ions in MOF crystals, various metal oxides (with the same cations as that in MOFs) were applied as matched supports. Several representative MOFs: MOF-5 (IRMOF-1), ZIF-8, and HKUST-1(Cu₃(btc)₂) were selected as the membrane materials, correspondingly, ZnO and CuO were used as supports. The results showed that the integrated MOF membranes were easily prepared on the matched supports by the in situ hydrothermal growth. For the MOF-5 and HKUST-1 membranes, the membrane formation mechanism was discussed in detail. ZnO was demonstrated as a suitable support for the in situ synthesis of continuous ZIF membranes. The integrity of the prepared membranes was measured by scanning electron microscopy and gas permeation performance.

Acknowledgment

This work is supported by the National Basic Research Program of China (No. 2009CB623406); National Natural Science Foundation of China (No. 20990222, No. 21006047) and China Postdoctoral Science Foundation funded project (No. 20090461105).

References:

[1] Y. X. Hu, X. L. Dong, J. P. Nan, W. Q. Jin, X. M. Ren, N. P. Xu and Y. M. Lee, Chem. Commun., 2011, 47, 737–739.

[2] J. P. Nan, X. L. Dong, W. J. Wang, W. Q. Jin and N. P. Xu, Langmuir, 2011, 27, 4309–4312.

[3] A. Huang, W. Dou and J. Caro, J. Am. Chem. Soc. 2010, 132, 15562–15564.

[4] S. R. Venna and M. A. Carreon, J. Am. Chem. Soc., 2010, 132, 76–78.

[5] M. C. McCarthy, V. Varela-Guerrero, G. V. Barnett and H.-K. Jeong, Langmuir, 2010, 26, 14636–14641.

[6] J. Gascon and F. Kapteijn, Angew. Chem. Int. Ed., 2010, 49, 1530–1532