Chemistry of inorganic compounds – Zeolite – Organic compound used to form zeolite
Reexamination Certificate
2001-07-13
2003-04-08
Sample, David (Department: 1755)
Chemistry of inorganic compounds
Zeolite
Organic compound used to form zeolite
C423S712000, C423S713000, C423S709000, C423S718000
Reexamination Certificate
active
06544495
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to new crystalline zeolite SSZ-57 and a method for preparing SSZ-57 using a N-butyl-N-cyclohexylpyrrolidinium cation, N-propyl-N-cycloheptylpyrrolidinium or N-butyl-N-cyclooctylpyrrolidinium cation as tempting agent.
2. State of the Art
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 zeolites with desirable properties for gas separation and drying, hydrocarbon and chemical conversions, and other applications. New zeolites may contain novel internal pore architectures, providing enhanced selectivities in these processes.
Crystalline aluminosilicates are usually prepared from aqueous reaction mixtures containing alkali or alkaline earth metal oxides, silica, and alumina. Crystalline borosilicates are usually prepared under similar reaction conditions except that boron is used in place of aluminum. By varying the synthesis conditions and the composition of the reaction mixture, different zeolites can often be formed.
SUMMARY OF THE INVENTION
The present invention is directed to a family of crystalline molecular sieves with unique properties, referred to herein as “zeolite SSZ-57” or simply “SSZ-57”. Preferably, SSZ-57 is obtained in its borosilicate form, but the present novel zeolite can be synthesized in both the borosilicate or aluminosilicate phase. The term “borosilicate” refers to a zeolite containing oxides of both boron and silicon. The term “aluminosilicate refers to a zeolite containing oxides of both aluminum and silicon.
In accordance with this invention, there is provided a zeolite having a mole ratio greater than about 20 of an oxide selected from silicon oxide, germanium oxide and mixtures thereof to boron oxide or a combination of boron oxide and aluminum oxide, gallium oxide, indium oxide, titanium oxide or a mixture thereof and having, after calcination, the X-ray diffraction lines of Table 3 below.
The present invention further provides such a zeolite having a composition, as synthesized and in the anhydrous state, in terms of mole ratios as follows:
YO
2
/WcOd
20-∞
M
2
YO
2
0.01-0.03
Q/YO
2
0.02-0.05
wherein Y is silicon, germanium or a mixture thereof; W is boron or a combination of boron and aluminum, gallium, indium, titanium or a mixture thereof; M is an alkali metal cation, alkaline earth metal cation or mixtures thereof; n is the valence of M (i.e., 1 or 2); c is 1 or 2; d is 2 when c is 1 (i.e., W is tetravalent) or d is 3 or 5 when c is 2 (i.e., d is 3 when W is trivalent or 5 when W is pentavalent); and Q comprises a N-butyl-N-cyclohexylpyrrolidinium cation, N-propyl-N-cycloheptylpyrrolidinium cation or N-butyl-N-cyclooctylpyrrolidinium.
In accordance with this invention, there is also provided a zeolite prepared by thermally treating a zeolite having a mole ratio of an oxide selected from silicon oxide, germanium oxide and mixtures thereof to boron oxide or a combination of boron oxide and aluminum oxide, gallium oxide, indium oxide, titanium oxide or a mixture thereof greater than about 20 at a temperature of from about 200° C. to about 1100° C., the thus-prepared zeolite having the X-ray diffraction lines of Table 3 below. The present invention also includes this thus-prepared zeolite which is predominantly in the hydrogen form, which is prepared by ion exchanging with an acid or with a solution of an ammonium salt followed by a second calcination.
Also provided in accordance with the present invention is a method of preparing a crystalline material comprising an oxide selected from silicon oxide, germanium oxide and mixtures thereof and boron oxide or a combination of boron oxide and aluminum oxide, gallium oxide, indium oxide, titanium oxide or a mixture thereof, said method comprising contacting under crystallization conditions sources of said oxides and a tempting agent comprising a N-butyl-N-cyclohexylpyrrolidinium cation, N-propyl-N-cycloheptylpyrrolidinium cation or N-butyl-N-cyclooctylpyrrolidinium.
DETAILED DESCRIPTION OF THE INVENTION
The present invention comprises a family of crystalline zeolites designated herein “zeolite SSZ-57” or simply “SSZ-57”.
In preparing SSZ-57 zeolites, a N-cyclohexyl-N-butylpyrrolidinium ammonium cation, N-propyl-N-cycloheptylpyrrolidinium cation or N-butyl-N-cyclooctylpyrrolidinium is used as a crystallization template. In general, SSZ-57 is prepared by contacting an active source of an oxide selected from silicon oxide, germanium oxide and mixtures thereof and boron oxide or a combination of boron oxide and aluminum oxide, gallium oxide, indium oxide, titanium oxide or a mixture thereof with the tempting agent.
SSZ-57 is prepared from a reaction mixture having the composition shown in Table A below.
TABLE A
Reaction Mixture
Typical
Preferred
YO
2
/WaO
b
20-∞
35-90
OH-/YO
2
0.1-0.50
0.2-0.3
Q/YO
2
0.05-0.5
0.1-0.2
M
2
/YO
2
0.02-0.4
0.1-0.25
H
2
O/YO
2
25-80
30-50
where Y, W, Q, M and n are as defined above, and a is 1 or 2 and b is 2 when a is 1 (i.e., W is tetravalent) or b is 3 when a is 2 (i.e., W is trivalent).
In practice, SSZ-57 is prepared by a process comprising:
(a) preparing an aqueous solution containing sources of at least one oxide capable of forming a crystalline molecular sieve and the N-butyl-N-cyclohexylpyrrolidinium cation, N-propyl-N-cycloheptylpyrrolidinium cation or N-butyl-N-cyclooctylpyrrolidinium in the presence of an anionic counterion which is not detrimental to the formation of SSZ-57;
(b) maintaining the aqueous solution under conditions sufficient to form crystals of SSZ-57; and
(c) recovering the crystals of SSZ-57.
Accordingly, SSZ-57 may comprise the crystalline material and the tempting agent in combination with metallic and non-metallic oxides bonded in tetrahedral coordination through shared oxygen atoms to form a cross-linked three dimensional crystal structure. The metallic and non-metallic oxides comprise an oxide selected from silicon oxide, germanium oxide and mixtures thereof and boron oxide or a combination of boron oxide and aluminum oxide, gallium oxide, indium oxide, titanium oxide or a mixture thereof.
Typical sources of silicon oxide include silicates, silica hydrogel, silicic acid, fumed silica, colloidal silica, tetra-alkyl orthosilicates, and silica hydroxides. Boron, as well as aluminum, gallium, germanium, titanium, and indium can be added in forms corresponding to their silicon counterparts.
A source zeolite reagent may provide a source of boron. In most cases, the source zeolite also provides a source of silica. The source zeolite in its dealuminated or deboronated form may also be used as a source of silica, with additional silicon added using, for example, the conventional sources listed above. Use of a source zeolite reagent as a source of alumina for the present process is more completely described in U.S. Pat. No. 5,225,179, issued Jul. 6, 1993 to Nakagawa entitled “Method of Making Molecular Sieves”, the disclosure of which is incorporated herein by reference.
Typically, an alkali metal hydroxide and/or an alkaline earth metal hydroxide, such as the hydroxide of sodium, potassium, lithium, cesium, rubidium, calcium, and magnesium, is used in the reaction mixture; however, this component can be omitted so long as the equivalent basicity is maintained. The tempting agent may be used to provide hydroxide ion. Thus, it may be beneficial to ion exchange, for example, the halide for hydroxide ion, thereby reducing or eliminating the alkali metal hydroxide quantity required. The alkali metal cation or alkaline earth cation may be part of the as-synthesized crystalline oxide material, in order to balance valence electron charges therein.
The reaction mixture is maintained at an elevated temperature until the crystals of the SSZ-57 zeolite are formed.
Chevron U.S.A. Inc.
Sample David
Sheridan Richard J.
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