title: Ultra-selective high-flux membranes from directly synthesized zeolite nanosheets.
abstract: A zeolite with structure type MFI is an aluminosilicate or silicate material that has a three-dimensionally connected pore network, which enables molecular recognition in the size range 0.5-0.6 nm. These micropore dimensions are relevant for many valuable chemical intermediates, and therefore MFI-type zeolites are widely used in the chemical industry as selective catalysts or adsorbents. As with all zeolites, strategies to tailor them for specific applications include controlling their crystal size and shape. Nanometre-thick MFI crystals (nanosheets) have been introduced in pillared and self-pillared (intergrown) architectures, offering improved mass-transfer characteristics for certain adsorption and catalysis applications. Moreover, single (non-intergrown and non-layered) nanosheets have been used to prepare thin membranes that could be used to improve the energy efficiency of separation processes. However, until now, single MFI nanosheets have been prepared using a multi-step approach based on the exfoliation of layered MFI, followed by centrifugation to remove non-exfoliated particles. This top-down method is time-consuming, costly and low-yield and it produces fragmented nanosheets with submicrometre lateral dimensions. Alternatively, direct (bottom-up) synthesis could produce high-aspect-ratio zeolite nanosheets, with improved yield and at lower cost. Here we use a nanocrystal-seeded growth method triggered by a single rotational intergrowth to synthesize high-aspect-ratio MFI nanosheets with a thickness of 5 nanometres (2.5 unit cells). These high-aspect-ratio nanosheets allow the fabrication of thin and defect-free coatings that effectively cover porous substrates. These coatings can be intergrown to produce high-flux and ultra-selective MFI membranes that compare favourably with other MFI membranes prepared from existing MFI materials (such as exfoliated nanosheets or nanocrystals).
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Mi Young
authors.initials: MY
authors.lastname: Jeon
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Donghun
authors.initials: D
authors.lastname: Kim
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Prashant
authors.initials: P
authors.lastname: Kumar
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Pyung Soo
authors.initials: PS
authors.lastname: Lee
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Neel
authors.initials: N
authors.lastname: Rangnekar
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.|Department of Chemistry and Chemical Theory Center, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Peng
authors.initials: P
authors.lastname: Bai
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Meera
authors.initials: M
authors.lastname: Shete
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Bahman
authors.initials: B
authors.lastname: Elyassi
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Han Seung
authors.initials: HS
authors.lastname: Lee
authors.affiliation: Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
authors.forename: Katabathini
authors.initials: K
authors.lastname: Narasimharao
authors.affiliation: Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
authors.forename: Sulaiman Nasir
authors.initials: SN
authors.lastname: Basahel
authors.affiliation: Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
authors.forename: Shaeel
authors.initials: S
authors.lastname: Al-Thabaiti
authors.affiliation: X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA.
authors.forename: Wenqian
authors.initials: W
authors.lastname: Xu
authors.affiliation: Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, USA.
authors.forename: Hong Je
authors.initials: HJ
authors.lastname: Cho
authors.affiliation: Department of Chemistry and Chemical Theory Center, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Evgenii O
authors.initials: EO
authors.lastname: Fetisov
authors.affiliation: Department of Chemistry and Chemical Theory Center, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Raghuram
authors.initials: R
authors.lastname: Thyagarajan
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Robert F
authors.initials: RF
authors.lastname: DeJaco
authors.affiliation: Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Fan
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: K Andre
authors.initials: KA
authors.lastname: Mkhoyan
authors.affiliation: Department of Chemistry and Chemical Theory Center, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: J Ilja
authors.initials: JI
authors.lastname: Siepmann
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Tsapatsis