ZSM-5

ZSM-5

ZSM-5 (structure type MFI) is an aluminosilicate zeolite mineral belonging to the pentasil family of zeolites. Its chemical formula is NanAlnSi96-nO192•16H2O (0Mobil Oil Company in 1975, it is widely used in the petroleum industry as a heterogeneous catalyst for hydrocarbon isomerization reactions.

Structure

ZSM-5 is composed of several pentasil units linked together by oxygen bridges to form pentasil chains. A pentasil unit consists of eight five-membered rings. In these rings, the vertices are Al or Si and an O is assumed to be bonded between the vertices.



The pentasil chains are interconnected by oxygen bridges to form corrugated sheets with 10-ring holes. Like the pentasil units, each 10-ring hole has Al or Si as vertices with an O assumed to be bonded between each vertex. Each corrugated sheet is connected by oxygen bridges to form a structure with “straight 10-ring channels running parallel to the corrugations and sinusoidal 10-ring channels perpendicular to the sheets.” ["Zeolites and Ordered Mesoporous Materials: Progress and Prospects". (2005) Vol 157. Ed: J. Čejka, H. van Bekkum. ISBN: 0-444-52066-X] Adjacent layers of the sheets are related by an inversion point. The estimated pore size of the channel running parallel with the corrugations is 5.4 – 5.6 Å. [Modeling of Structure and Reactivity in Zeolites (1992). Ed: C.R.A. Catlow. Academic Press, Ltd.: London. ISBN: 0-12-164140-6]

ynthesis

ZSM-5 is a synthetic zeolite, closely related to ZSM-11. There are many ways to synthesize ZSM-5, a common method is as follows [Lermer, H.; Draeger, M.; Steffen, J.; Unger, K.K. "Zeolites", 1985, "5", 131-134]

:SiO2 + NaAlO2 + NaOH + N(CH2CH2CH3)4Br + H2O → ZSM-5 + analcime + alpha-quartz

ZSM-5 is typically prepared at high temperature and high pressure in a Teflon coated autoclave and can be prepared using varying ratios of SiO2 and Al containing compounds.

Uses

ZSM-5 has a high silicon to aluminum ratio. Whenever an Al3+ cation replaces a Si4+ cation, an additional positive charge is required the keep the material charge-neutral. With proton (H+) as the cation, the material becomes very acidic. Thus the acidity is proportional to the Al content. The very regular 3-D structure and the acidity of ZSM-5 can be utilized for acid-catalyzed reactions such as hydrocarbon isomerization and the alkylation of hydrocarbons. One such reaction is the isomerization of meta-xylene to

References


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  • ZSM-5 — ZSM 5, zeolita tamiz poroso molecular(o zeolita Socony Mobil) 5 (estructura tipo MFI estructura mordenita invertido) es un aluminosilicato zeolita mineral perteneciente al pentasil de la familia de las zeolitas. Su fórmula química es Na n Al n Si …   Wikipedia Español

  • ZSM — can stand for:* ZSM 5, a zeolite mineral * Zoologische Staatssammlung München, a German zoological institute …   Wikipedia

  • ZSM — ist: Zeolithe Socony Mobil , eine Gruppe von Zeolithe (Stoffgruppe), die erstmals in den Laboren der Mobil Oil (Socony, Standard Oil Company of New York) synthetisiert wurden. eine Abkürzung für die Zoologische Staatssammlung München …   Deutsch Wikipedia

  • ZSM — [Abk. für engl. zeolite Socony Mobil = Zeolith der (ehem.) amer. Ölgesellschaft Socony (= Standard Oil Co. of New York) Mobil]: Bez. für synthetische ↑ Zeolithe …   Universal-Lexikon

  • ZSM-5 — La zéolite ZSM5 est un minéral synthétique appartenant à la famille des aluminosilicates hydratés de métaux. Elle est synthétisée généralement en milieu basique au moyen d’un agent organique de type sel de tétrapropylammonium à des pressions et… …   Wikipédia en Français

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  • ZSM-2 — Zeolite Socony Mobil #2 (Academic & Science » Chemistry) …   Abbreviations dictionary

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