(376r) A Combined Seeding Approach for High-Flux Zeolitic-Imidazolate Framework ZIF-67 Membranes for Olefin/Paraffin Separation
Jingze Sun1, Chen Yu1, Kumar Varoon Agrawal2, and Hae-Kwon Jeong*1,3
1Artie McFerrin Department of Chemical Engineering and 3Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843-3122
2Laboratory of Advanced Separations (LAS), École Polytechnique Fédérale de Lausanne (EPFL) CH-1951, Sion, Swizerland
* Corresponding author: email@example.com
Having been extensively researched as potential membrane materials, zeolite-imidazole frameworks (ZIFs) are famous for their robust synthesis protocols, chemical and thermal stabilities, and well-defined ultra-micropores (~ 2 to 5 Å).1, 2 Composed of zinc nodes and 2-methylimidazole linkers, ZIF-8 has been shown very promising for propylene/propane separation, because of its effective aperture size lying between that of propylene and propane..3, 4 Due to its slightly smaller aperture, ZIF-67 (Co-substituted ZIF-8)5, 6 seems promising for improving propylene/propane separation performances as compared with ZIF-8. Previous works from our group for ZIF-8/ZIF-67/ZIF-8 multi-layer membranes has exhibited propylene/propane separation factors as high as 209.7 Unfortunately, no ZIF-67 membranes have been reported primarily due to the transformation of ZIF-67 seed crystals into a double hydroxide phase upon the secondary growth.
Here, we are glad to present the first phase-pure ZIF-67 membranes as thin as ~ 300 nm. The resulting ultrathin ZIF-67 membranes resulted from microwave-assisted (MW) seeding followed by Electrophoretic Nuclei Assembly (ENACT), by which high-quality densely-packed ZIF-8 seed layers prepared.8 Much increased propylene permeances were observed from these ultra-thin ZIF-67 membranes as compared to ZIF-8 membranes. To obtain phase-pure ZIF-67 membranes, it was found critical 1) to have densely-packed ZIF-67 seed layers by combining MW and ENACT seeding and 2) to lower secondary growth temperature. This MW/ENACT seeding technique was demonstrated effective for ZIF-8 and ZIF-90 membranes on alumina supports as well.
References and Notes:
- S. Park, W. R. Kang, H. T. Kwon, S. Kim, M. Seo, J. Bang, S. hyup Lee, H. K. Jeong and J. S. Lee, Journal of Membrane Science, 2015, 486, 29-39.
- C. Zhang, R. P. Lively, K. Zhang, J. R. Johnson, O. Karvan and W. J. Koros, The journal of physical chemistry letters, 2012, 3, 2130-2134.
- K. Li, D. H. Olson, J. Seidel, T. J. Emge, H. Gong, H. Zeng and J. Li, Journal of the American Chemical Society, 2009, 131, 10368-10369.
- H. Bux, F. Liang, Y. Li, J. Cravillon, M. Wiebcke and J. r. Caro, Journal of the American Chemical Society, 2009, 131, 16000-16001.
- F. Hillman, J. M. Zimmerman, S.-M. Paek, M. R. Hamid, W. T. Lim and H.-K. Jeong, Journal of Materials Chemistry A, 2017, 5, 6090-6099.
- P. Krokidas, M. Castier, S. Moncho, D. N. Sredojevic, E. N. Brothers, H. T. Kwon, H.-K. Jeong, J. S. Lee and I. G. Economou, The Journal of Physical Chemistry C, 2016, 120, 8116-8124.
- H. T. Kwon, H.-K. Jeong, A. S. Lee, H. S. An and J. S. Lee, Journal of the American Chemical Society, 2015, 137, 12304-12311.
- G. He, M. Dakhchoune, J. Zhao, S. Huang and K. V. Agrawal, Advanced Functional Materials, 2018.