Metal clusters in zeolites: an intriguing class of catalysts

Metal/zeolite catalysts offer challenging perspectives for catalysis; as an object of fundamental research they have helped to revive the debate on some general concepts. Metal-proton interaction in zeolites and anchoring of metal clusters by protons are phenomena supported by independent data. The...

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Bibliographic Details
Published in:Accounts of chemical research 1993-07, Vol.26 (7), p.383-387
Main Author: Sachtler, Wolfgang M. H
Format: Article
Language:English
Subjects:
400201 - Chemical & Physicochemical Properties
ATOMIC CLUSTERS
CATALYST SUPPORTS
CATALYSTS
CHALCOGENIDES
CHEMICAL PREPARATION
ELEMENTS
GALLIUM COMPOUNDS
GALLIUM OXIDES
INORGANIC ION EXCHANGERS
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
ION EXCHANGE MATERIALS
MATERIALS
METALS
MINERALS
MORDENITE
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
SILICATE MINERALS
STRUCTURAL CHEMICAL ANALYSIS
SYNTHESIS
TRANSITION ELEMENTS
ZEOLITES
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Summary:Metal/zeolite catalysts offer challenging perspectives for catalysis; as an object of fundamental research they have helped to revive the debate on some general concepts. Metal-proton interaction in zeolites and anchoring of metal clusters by protons are phenomena supported by independent data. The formation of isolated Pt atoms, in sodalite cages of Y and in side pockets of mordenite, is possible at low metal loadings, low reduction temperatures, and high concentrations of protons. The catalytic characteristics of metal/zeolite catalysts can be manipulated by exploiting the chemistry which drives metal ions into small cages or stabilizes them with appropriate ligands in large cages. Hydrolysis of multipositive ions to oxo complexes of low effective charge, such as (GaO)[sup +], improves the Coulomb interaction with widely spaced negative charges in the zeolite. Formation of [open quotes]alloy[close quotes] clusters in bimetallic catalysts is controlled, among other things, by reoxidation of one metal by zeolite protons at elevated temperatures. 39 refs., 3 figs.
ISSN:0001-4842
1520-4898
DOI:10.1021/ar00031a005