title: Heteroepitaxially grown zeolitic imidazolate framework membranes with unprecedented propylene/propane separation performances.
abstract: 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 Å, 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.
authors.forename: Hyuk Taek
authors.initials: HT
authors.lastname: Kwon
authors.forename: Hae-Kwon
authors.initials: HK
authors.lastname: Jeong
authors.affiliation: Materials Architecturing Research Center, Korea Institute of Science and Technology , Hwarang-ro 14-gil, Seongbuk-gu, Seoul 136-791, Republic of Korea.
authors.forename: Albert S
authors.initials: AS
authors.lastname: Lee
authors.affiliation: Department of Chemical and Biological Engineering, Korea University , 5-1 Anam-dong, Seongbuk-gu, Seoul 136-713, Republic of Korea.|Center for Environment, Health and Welfare Research, Korea Institute of Science and Technology , Hwarang-ro 14-gil, Seongbuk-gu, Seoul 136-791, Republic of Korea.
authors.forename: He Seong
authors.initials: HS
authors.lastname: An
authors.affiliation: Center for Environment, Health and Welfare Research, Korea Institute of Science and Technology , Hwarang-ro 14-gil, Seongbuk-gu, Seoul 136-791, Republic of Korea.
authors.forename: Jong Suk
authors.initials: JS
authors.lastname: Lee
mesh_terms: D000475:Alkenes / Q000737:chemistry / Q000302:isolation & purification*; D007093:Imidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D010316:Particle Size; D011407:Propane / Q000737:chemistry / Q000302:isolation & purification*; D013499:Surface Properties; D017641:Zeolites / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000475:Alkenes; D007093:Imidazoles; D017641:Zeolites; C013658:propylene; D011407:Propane