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Title: The Synthesis and Structure of SSZ-73: an All-Silica Zeolite with an Unusual Framework Topology

Abstract

This paper reports the synthesis, characterization, and crystallographic studies of the new all-silica zeolite SSZ-73. The framework topology of SSZ-73 is isostructural with the aluminophosphate STA-6 (SAS). SSZ-73 is prepared from fluoride-containing gels using 3-ethyl-1,3,8,8-tetramethyl-3-azoniabicyclo[3.2.1]octane cation as a structure-directing agent. SSZ-73 is an all-silica zeolite with a one-dimensional system of eight-ring pores. However, SSZ-73 possesses a remarkably high micropore volume (0.25 cm{sup 3}/g) due to the rather large cages in the structure. A single-crystal X-ray diffraction study of the as-made material shows that fluoride resides within the double six-ring cages of the SAS framework. Molecular docking studies were performed for the two geometric isomers of the structure-directing agent in the all-silica frameworks of SAS, RTH, ITE, and STF. The studies suggest that the isomer with the ethyl group cis to the bridgehead carbon is the likely structure-directing agent for SSZ-73 and that the other isomer may be responsible for the small amounts of RTH impurity observed in some preparations of SSZ-73.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
929943
Report Number(s):
BNL-80538-2008-JA
Journal ID: ISSN 0897-4756; CMATEX; TRN: US200822%%941
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chemistry of Materials; Journal Volume: 19
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ZEOLITES; SILICA; SYNTHESIS; CRYSTALLOGRAPHY; ISOMERS; national synchrotron light source

Citation Formats

Wragg,D., Morris, R., Burton, A., Zones, S., Ong, K., and Lee, G. The Synthesis and Structure of SSZ-73: an All-Silica Zeolite with an Unusual Framework Topology. United States: N. p., 2007. Web. doi:10.1021/cm0705284.
Wragg,D., Morris, R., Burton, A., Zones, S., Ong, K., & Lee, G. The Synthesis and Structure of SSZ-73: an All-Silica Zeolite with an Unusual Framework Topology. United States. doi:10.1021/cm0705284.
Wragg,D., Morris, R., Burton, A., Zones, S., Ong, K., and Lee, G. Mon . "The Synthesis and Structure of SSZ-73: an All-Silica Zeolite with an Unusual Framework Topology". United States. doi:10.1021/cm0705284.
@article{osti_929943,
title = {The Synthesis and Structure of SSZ-73: an All-Silica Zeolite with an Unusual Framework Topology},
author = {Wragg,D. and Morris, R. and Burton, A. and Zones, S. and Ong, K. and Lee, G.},
abstractNote = {This paper reports the synthesis, characterization, and crystallographic studies of the new all-silica zeolite SSZ-73. The framework topology of SSZ-73 is isostructural with the aluminophosphate STA-6 (SAS). SSZ-73 is prepared from fluoride-containing gels using 3-ethyl-1,3,8,8-tetramethyl-3-azoniabicyclo[3.2.1]octane cation as a structure-directing agent. SSZ-73 is an all-silica zeolite with a one-dimensional system of eight-ring pores. However, SSZ-73 possesses a remarkably high micropore volume (0.25 cm{sup 3}/g) due to the rather large cages in the structure. A single-crystal X-ray diffraction study of the as-made material shows that fluoride resides within the double six-ring cages of the SAS framework. Molecular docking studies were performed for the two geometric isomers of the structure-directing agent in the all-silica frameworks of SAS, RTH, ITE, and STF. The studies suggest that the isomer with the ethyl group cis to the bridgehead carbon is the likely structure-directing agent for SSZ-73 and that the other isomer may be responsible for the small amounts of RTH impurity observed in some preparations of SSZ-73.},
doi = {10.1021/cm0705284},
journal = {Chemistry of Materials},
number = ,
volume = 19,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • A new molecular sieve topology has been determined from a multistage Monte Carlo computer simulation procedure using the program ZEFSAII. The material, SSZ-77, consists of alternating layers present in the RUT and AST topologies, and intergrowths may be possible in the way that this material grows. The product first arose from a synthesis where it appears that the degradation of the quaternary ammonium structure directing agent (SDA) produced the viable organo-guest molecule in the structure formation. The synthesis requires the use of Ge as well as Si as lattice components. In the absence of Ge, only RUT forms. An additionalmore » study was carried out to determine the suitable size of guest molecules in a series spanning trimethylamine to tetraethylammonium in the presence of benzyltrimethylammonium. It is found from NMR investigations that none of the larger molecules are occluded within the cages of the SSZ-77 structure, and that the primary occluded species is trimethylamine or tetramethylammonium.« less
  • No abstract prepared.
  • Physico-chemical characterization of the high-silica zeolite catalyst SSZ-74 (ref. 1) suggested that it, like the related materials TNU-9 (ref. 2) and IM-5 (ref. 3), has a multidimensional 10-ring channel system4. Such pore systems are ideal for many petrochemical applications, and indeed SSZ-74 has been shown to be a good catalyst for a wide variety of reactions1. The elucidation of its framework structure, however, proved to be difficult. Comparable problems were encountered with TNU-9 and IM-5, which were synthesized with related structure-directing agents. Their framework structures, which are the two most complex ones known, both have 24 Si atoms in themore » asymmetric unit, and were finally solved by combining high-resolution powder diffraction data with information derived from high-resolution electron microscopy images5, 6. Therefore, a similar approach, using the powder charge-flipping algorithm7 to combine the two types of data and molecular modelling to help to locate the structure-directing agent, was applied to SSZ-74. This procedure eventually revealed a most unusual 23-Si-atom framework structure (|(C16H34N2)4|[Si92square4O184(OH)8]) with ordered Si vacancies.« less
  • This report describes the synthesis and structure solution of the new zeolite SSZ-65. SSZ-65 may be prepared as either a borosilicate (Si52.5B1.5O108) or an aluminosilicate using 1-[1-(4-chloro-phenyl)-cyclopropylmethyl]-1-ethyl-pyrrolidinium as a structure-directing agent. The structure of SSZ-65 was determined with the FOCUS Fourier recycling method. The framework of SSZ-65 possesses a two-dimensional system of intersecting 12-ring channels with pore apertures of 6.9 Angstroms x 5.9 Angstroms . The topological symmetry of SSZ-65 is P6/mmm, but improvements in the Rietveld refinement of the powder diffraction data are obtained in space group P6/m (a = 16.8009(2) Angstroms and c = 12.6154(1) Angstroms ). Themore » agreement values improve from Rwp = 0.116, Rp = 0.094, and R(F2) = 0.142 in P6/mmm to Rwp = 0.103, Rp = 0.085, and R(F2) = 0.092 in P6/m.« less
  • No abstract prepared.