Heteroepitaxially grown zeolitic imidazolate framework membranes with unprecedented propylene/propane separation performances.
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Propylene/propane separation is one of the most challenging separations, currently achieved by energy-intensive cryogenic distillation. Despite the great potential for energy-efficient membrane-based separations, no commercial membranes are currently available due to the limitations of current polymeric materials. Zeolitic imidazolate framework, ZIF-8, with the effective aperture size of 4.0 , has been shown to be very promising for propylene/propane separation. Despite the extensive research on ZIF-8 membranes, only a few reported ZIF-8 membranes have displayed good propylene/propane separation performances presumably due to the challenges of controlling the microstructures of polycrystalline membranes. Here we report the first well-intergrown membranes of ZIF-67 (Co-substituted ZIF-8) by heteroepitaxially growing ZIF-67 on ZIF-8 seed layers. The ZIF-67 membranes exhibited impressively high propylene/propane separation capabilities. Furthermore, when a tertiary growth of ZIF-8 layers was applied to heteroepitaxially grown ZIF-67 membranes, the membranes exhibited unprecedentedly high propylene/propane separation factors of 200 possibly due to enhanced grain boundary structure.
author list (cited authors)
Kwon, H. T., Jeong, H., Lee, A. S., An, H. S., & Lee, J. S.
complete list of authors
Kwon, Hyuk Taek||Jeong, Hae-Kwon||Lee, Albert S||An, He Seong||Lee, Jong Suk