Identification of precursor species in the formation of MFI zeolite in the TPAOH-TEOS-H20 system
Article Abstract:
A study was conducted to assess the effects of polycondensation process of tetraethyl orthosilicate (TEOS) in a concentrated aqueous solution of tetrapropylammonium hydroxide (TPAOH) when processed in low temperatures. Nuclear magnetic resonance was used to monitor the condensation process which revealed the formation of annealed five-ring species and the depletion of three-ring entities. A phase boundary between TEOS and TPAOH was present after 45 minutes of mixing at 0 deg Celcius and, later, at room temperature. At approximately the same time, all TEOS was hydrolyzed and transferred to the liquid phase.
Publication Name: Journal of Physical Chemistry B
Subject: Chemicals, plastics and rubber industries
ISSN: 1520-6106
Year: 1999
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Physiochemical characterization of silicalite-1 nanophase material
Article Abstract:
A study was conducted to analyze the synthesis of a silicalite-1 nanophase material supporting an elementary particle size of 18-100 nm. The material was prepared from clear solution and purified by supercentrifugation. The nanopowder was then determined by a number of methods. These include scanning electron microscopy, high-resolution transmission electron microscopy and 13C cross polarization magic angle spinning nuclear magnetic resonance. Experimental results indicated that the nanophase material supported elementary crystallites of 18-100 nm.
Publication Name: Journal of Physical Chemistry B
Subject: Chemicals, plastics and rubber industries
ISSN: 1520-6106
Year: 1998
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Characterization of nanosized material extracted from clear suspensions for MFI zeolite synthesis
Article Abstract:
A study was conducted on the crystalline mechanisms of zeolites. To further study zeolite synthesis, a silicon specimen was contained in an aged clear suspension. When subjected to intense heat, the crystallization resulted forming silicate-1. This process was followed by acidification, salting out, phase transfer into organic solvent and freeze-drying processes. Silicate-1 is a zeolite and a polymorph with MFI topology that can be synthesized by traditional hydrothermal gel method or by the clear solution process.
Publication Name: Journal of Physical Chemistry B
Subject: Chemicals, plastics and rubber industries
ISSN: 1520-6106
Year: 1999
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