| Abstract
| - A framework model of the zeolite SSZ-73. SSZ-73 shares the same framework topology (SAS) as the aluminophosphate STA-6. This all-silica zeolite has been prepared by using the organocation 3-ethyl-1,3,8,8-tetramethyl-3-azoniobicyclo[3.2.1]octane as a structure-direction agent in fluoride media. Because of its large cages, SSZ-73 has the highest micropore volume of any known zeolite with one-dimensional small pores.
- This paper reports the synthesis, characterization, and crystallographic studies of the new all-silicazeolite 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-dimensionalsystem of eight-ring pores. However, SSZ-73 possesses a remarkably high micropore volume (0.25 cm3/g) due to the rather large cages in the structure. A single-crystal X-ray diffraction study of the as-madematerial shows that fluoride resides within the double six-ring cages of the SAS framework. Moleculardocking studies were performed for the two geometric isomers of the structure-directing agent in theall-silica frameworks of SAS, RTH, ITE, and STF. The studies suggest that the isomer with the ethylgroup cis to the bridgehead carbon is the likely structure-directing agent for SSZ-73 and that the otherisomer may be responsible for the small amounts of RTH impurity observed in some preparations ofSSZ-73.
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