MFI zeolite membranes from a- and randomly oriented monolayers

Abstract

c-Oriented columnar MFI films made by secondary growth of randomly oriented seed monolayers, deposited using sonication-assisted covalent attachment, exhibit n-hexane/2,2-dimethylbutane separation factor of up to 10 4 , n-/i-butane separation factor of up to 50, and p-/o-xylene separation factor of up to 2. A MFI film from a-oriented seed layer shows lower separation factors for the linear vs. branched isomers but higher separation factor for p-/o-xylene.

Hierarchical Nanomanufacturing: From Shaped Zeolite Nanoparticles to High‐Performance Separation Membranes

“…The right-most image of (b) is an SEM image of higher magnification that shows the crystal defects ( * ) associated with the fluorescing features, and the well-intergrown b-oriented crystals (labeled "b"). [114,211,222,223] b-(*), [95,201] h0h-oriented (^), [114] and thin (500 nm) randomly oriented (~, t) [125,224] silicalite-1 membranes for separating the indicated components at temperatures ranging from room temperature to as high as 400 8C (light gray: RT-100 8C, gray: 100-200 8C, black: 200-400 8C. 2.2-DMB: 2,2-dimethylbutane.…”

“…By comparing the separation capabilities of siliceous MFI membranes having different microstructures, it is evident that separation performance is an extremely sensitive function of the preferred orientation, [95,114,211] and not simply a limit of the trade-off between flux and separation that is characteristic of polymeric films. [212] The sensitivity in the case of zeolitic films can be attributed not only to differences in the orientation of intracrystalline pores, but, as suggested by laser scanning confocal microscopy (LSCM) studies, [213,214] to differences in intercrystalline pathways (grain boundary structure) as well.…”

Oriented growth and assembly of zeolite crystals on substrates

“…The composite membrane produced by growing a beta-zeolite film on the Nafion membrane with acidification has much lower methanol permeability [72] . Furthermore, zeolite crystals have significant application potential in separation and catalytic membranes [6,[73][74][75] . The work in this respect has been reviewed elsewhere [1,76,77] .…”

Hierarchische Nanofertigung: von geformten Zeolithnanopartikeln zu hochleistungsfähigen Trennmembranen

“…Für Silicalit-1- [214] und andere Filme [216] haben [217,218] und die neuesten Ergebnisse [219] [114,211,222,223] b-(*) [95,201] und h0h-orientierten (^) [114] sowie dünnen (500 nm) zufällig orientierten Silicalit-1-Membranen (~, t) [125,224] für die Trennung der angegebenen Komponenten bei Raumtemperatur bis 400 8C (hellgrau: RT-100 8C, grau: 100-200 8C, schwarz: 200-400 8C). 2,2-DMB: 2,2-Dimethylbutan.…”

“…Vergleicht man die Trenneigenschaften silicatischer MFI-Membranen unterschiedlicher Mikrostruktur, so wird deutlich, dass die Trennleistung stark von der Vorzugsorientierung M. Tsapatsis und M. A. Snyder Aufsätze 7712 www.angewandte.de abhängt [95,114,211] und nicht, wie für Polymerfilme typisch, einfach dem Kompromiss zwischen Fluss und Trennung entspricht. [212] Diese für Zeolithfilme charakteristische Abhängigkeit lässt sich sowohl auf Unterschiede in der Orientierung der intrakristallinen Poren als auch, wie Studien mit konfokaler Laserrastermikroskopie (LSCM) belegen, [213,214] auf Unterschiede der interkristallinen Pfade (Korngrenzenstruktur) zurückführen.…”