From a technological point of view, the synthesis of new high-silica zeolites is of prime importance owing to their high potential as industrial catalysts and catalyst supports. Two such materials have been synthesized which are made up of the 1,3-stellated cubic unit (hexahedral ([42 54 ]) bre unit) as a secondary building unit, with the aid of existing imidazolium-based structure-directing agents under "excess fluoride" conditions. One of them, denoted PST-21, is the first aluminosilicate zeolite consisting of 9-ring apertures solely; it displays exceptional activity towards steering the skeletal isomerization of 1-butene to isobutene and bridges the gap between small- and medium-pore structures. A series of hypothetical structures are also described that are nonjointly built from the bre unit; all of these structures are chemically feasible and will thus be helpful in designing the synthesis of novel zeolites containing 9-ring and/or 10-ring channels.
Keywords: 9-ring structures; aluminosilicates; isomerization of 1-butene; zeolites.
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