Method for making germanosilicate ssz-75 (Chevron U.S.A.)

CATEGORY: MOLECULAR SIEVES
PATENT
Method for making germanosilicate ssz-75 (Chevron U.S.A.)
Publication number
US20130183233 A1
Application number
US 13/786,796
Publication date
Jul 18, 2013
Inventors
Tracy Margaret Davis, Anton Petushkov
Original Assignee
Chevron U.S.A. Inc.
Abstract
The present invention is directing to a method for making a germanosilicate SSZ-75 molecular sieve using a tetramethylene-1,4-bis-(N-methylpyrrolidinium) dication as a structure directing agent.
TECHNICAL FIELD
The present invention relates to a method for making germanosilicate molecular sieve SSZ-75 using a tetramethylene-1,4-bis-(N-methylpyrrolidinium) dication as a structure directing agent.
BACKGROUND
Molecular sieves having the STI framework topology defined by the connectivity of the tetrahedral atoms (referred to herein simply as “STI”) are known. See, for example, Ch. Baerlocher et al., Atlas of Zeolite Framework Types, 6th Revised Edition, 2007 of the International Zeolite Association. Examples of ST1 molecular sieves include naturally occurring stilbite, the zeolite designated TNU-10, and the molecular sieve designated SSZ-75. Stilbite is disclosed by D. W. Breck, Zeolite Molecular Sieves: Structure Chemistry and Use 1984, Robert E. Krieger Publishing Company. TNU-10 is reported by S. B. Hong et al., J. Am. Chem. Soc. 2004, 126, 5817-5826. SSZ-75 is disclosed in U.S. Pat. No. 7,713,512.
Because of their unique sieving characteristics, as well as their catalytic properties, crystalline molecular sieves and zeolites are especially useful in applications such as hydrocarbon conversion, gas drying and separation. Although many different crystalline molecular sieves have been disclosed, there is a continuing need for new molecular sieves with desirable properties for gas separation and drying, hydrocarbon and chemical conversions, and other applications. New molecular sieves may contain novel internal pore architectures, providing enhanced selectivity in these processes.
SUMMARY
In accordance with the present invention, there is provided a crystalline molecular sieve having STI topology and having silicon to germanium mole ratio of less than 15.
The present invention further provides such a crystalline molecular sieve having a composition comprising, as-synthesized and in its anhydrous state, in terms of mole ratios, the following:
Si/Ge
<15
M2/n/Si
  0 to 0.03
Q/Si
0.02 to 0.08
F/Si
0.01 to 0.04
wherein M is an alkali metal cation, an alkaline earth metal cation or a mixture thereof; n is the valence of M; Q is a tetramethylene-1,4-bis-(N-methylpyrrolidinium) dication; and F is fluoride.
The present invention also includes a method of preparing a molecular sieve, the method comprising contacting under crystallization conditions a source of silicon; a source of germanium; a source of fluoride ions; and a structure directing agent comprising a tetramethylene-1,4-bis-(N-methylpyrrolidinium) dication.
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