U.S. patent application number 11/863005 was filed with the patent office on 2008-07-03 for preparation of molecular sieve ssz-13.
Invention is credited to Stephen J. Miller, Lun-teh Yuen.
Application Number | 20080159950 11/863005 |
Document ID | / |
Family ID | 39584261 |
Filed Date | 2008-07-03 |
United States Patent
Application |
20080159950 |
Kind Code |
A1 |
Miller; Stephen J. ; et
al. |
July 3, 2008 |
PREPARATION OF MOLECULAR SIEVE SSZ-13
Abstract
Disclosed is a method for preparing crystalline zeolite SSZ-13,
said method comprising (a) preparing a reaction mixture comprising
(1) at least one active source of an oxide of a tetravalent element
or mixture of tetravalent elements, (2) optionally at least on
active source of an oxide of a trivalent element or mixture of
trivalent elements, (3) at least one active source of an alkali
metal, (4) seed crystals of zeolite SSZ-13, (5) benzyl
trimethylammonium cation in an amount sufficient to form crystals
of zeolite SSZ-13, the benzyl trimethylammonium cation being used
in the absence of a 1-adamantammonium cation, and (6) an amount of
water that is not substantially in excess of the amount required to
cause and maintain crystallization of the small pore zeolite; and
(b) heating said reaction mixture at crystallization conditions for
sufficient time to form crystallized material containing crystals
of SSZ-13.
Inventors: |
Miller; Stephen J.; (San
Francisco, CA) ; Yuen; Lun-teh; (Orinda, CA) |
Correspondence
Address: |
CHEVRON CORPORATION
P.O. BOX 6006
SAN RAMON
CA
94583-0806
US
|
Family ID: |
39584261 |
Appl. No.: |
11/863005 |
Filed: |
September 27, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60882010 |
Dec 27, 2006 |
|
|
|
Current U.S.
Class: |
423/704 ;
423/700 |
Current CPC
Class: |
Y02P 30/42 20151101;
C01B 37/02 20130101; C01B 39/48 20130101; Y02P 30/20 20151101; Y02P
30/40 20151101 |
Class at
Publication: |
423/704 ;
423/700 |
International
Class: |
C01B 33/36 20060101
C01B033/36 |
Claims
1. A method for preparing crystalline zeolite SSZ-13, said method
comprising: a. preparing a reaction mixture comprising (1) at least
one active source of an oxide of a tetravalent element or mixture
of tetravalent elements, (2) optionally at least one active source
of an oxide of a trivalent element or mixture of trivalent
elements, (3) at least one active source of an alkali metal, (4)
seed crystals capable of forming SSZ-13, (5) benzyl
trimethylammonium cation in an amount sufficient to form crystals
of zeolite SSZ-13, the benzyl trimethylammonium cation being used
in the absence of a 1-adamantammonium cation, and (6) an amount of
water that is not substantially in excess of the amount required to
cause and maintain crystallization of the SSZ-13; and b. heating
said reaction mixture at crystallization conditions for sufficient
time to form crystallized material containing crystals of said
SSZ-13.
2. The method of claim 1 wherein said reaction mixture during
crystallization has a water to (1) molar ratio between about 1 and
about 5.
3. The method of claim 1 or claim 2, wherein the heating said
reaction mixture at crystallization conditions is done in the
absence of an external liquid phase.
4. The method of claim 1 wherein the mole ratio Of the oxides in
the SSZ-13 formed from (1) and (2) is greater than 12.
5. The method of claim 3 wherein the mole ratio of oxides in the
SSZ-13 formed from (1) and (2) is 200 or more.
6. The method of claim 4 wherein the pore: size of the SSZ-13 is
less than 5 Angstroms.
7. The method according to claim 1 wherein said reaction mixture
has the following molar composition ranges: TABLE-US-00005
YO.sub.2/W.sub.2O.sub.3 20-.infin. M.sup.+/YO.sub.2 0.1-0.4
R/YO.sub.2 0.001-0.4 OH.sup.-/YO.sub.2 0.2-0.6 H.sub.2O/YO.sub.2
1-5
where Y is silicon, germanium or both, W is aluminum, boron,
gallium, iron, or a mixture thereof, M.sup.+ is an alkali metal ion
and R is a benzyl trimethylammonium cation, the benzyl
trimethylammonium cation being used in the absence of a
1-adamantammonium cation.
8. A method for preparing shaped crystalline zeolite SSZ-13, said
method comprising: a. preparing a reaction mixture comprising at
least (1) at least one active source of an oxide of a tetravalent
element or mixture of tetravalent elements, (2) optionally at least
one active source of an oxide of a trivalent element or mixture of
trivalent elements, (3) at least one active source of an alkali
metal, (4) seed crystals of SSZ-13, (5) a benzyl trimethylammonium
cation in an amount sufficient to form crystals of zeolite SSZ-13,
the benzyl trimethylammonium cation being used in the absence of a
1-adamantammonium cation, and (6) an amount of water that is not
substantially in excess of the amount required to cause and
maintain crystallization of the SSZ-13; b. forming said reaction
mixture into shaped particles; and c. heating said shaped particles
at crystallization conditions for sufficient time to form crystals
of said SSZ-13 within said shaped particles.
9. The method of claim 8 wherein said shaped particles during
crystallization have a water to (1) mole, ratio between about 1 and
about 5.
10. The method of claim 8 or 9, wherein the heating said reaction
mixture at crystallization conditions is done in the absence of an
external liquid phase.
11. The method of claim 8 wherein the mole ratio of the oxides in
the SSZ-13 formed from (1) and (2) is greater than 12.
12. The method of claim 11 wherein the mole ratio of oxides in the
SSZ-13 formed from (1) and (2) is 200 or more.
13. The method of claim 8 wherein the pore size of the small pore
zeolite is less than 5 Angstroms.
14. The method according to claim 8 wherein said reaction mixture
has the following molar composition ranges: TABLE-US-00006
YO.sub.2/W.sub.2O.sub.3 20-.infin. M.sup.+/YO.sub.2 0.1-0.4
R/YO.sub.2 0.001-0.4 OH.sup.-/YO.sub.2 0.2-0.6 H.sub.2O/YO.sub.2
1-5
where Y is silicon, germanium or both, W is aluminum, boron,
gallium, iron, or a mixture thereof, M.sup.+ is an alkali metal ion
and R is a benzyl trimethylammonium cation, the benzyl
trimethylammonium cation being used in the absence of a
1-adamantammonium cation.
15. A molecular sieve having a composition, as synthesized and in
the anhydrous state, comprising (1) a tetravalent oxide or mixture
of tetravalent oxides, (2) optionally, a trivalent oxide or
mixtures of trivalent oxides, and (3) benzyl trimethylammonium
cation, wherein the as-synthesized SSZ-13 does not contain a 1
-adamantammonium cation.
16. The molecular sieve of claim 15, wherein the tetravalent oxide
or mixture of tetravalent oxides is selected from the group
consisting of silicon oxide, germanium oxide, and mixtures
thereof.
17. The molecular sieve of claim 15, wherein the trivalent oxide or
mixtures of trivalent oxides is selected from the group consisting
of aluminum oxide, boron oxide, gallium oxide, iron oxide, and
mixtures thereof.
18. The molecular sieve of claim 15, wherein the composition is
aluminum free.
19. The molecular sieve of claim 15, wherein a mole ratio of oxides
(1) and (2) in the composition is greater than 12.
20. The molecular sieve of claim 19, wherein the mole ratio of
oxides (1) and (2) is 200 or more.
21. The molecular sieve of claim 15, having a pore size less than 5
Angstroms.
22. The molecular sieve of claim 15, wherein the molecular sieve
has pores with 8 membered rings.
23. A method for preparing crystalline zeolite SSZ-13, said method
comprising: a. preparing a reaction mixture comprising (1) at least
one active source of an oxide of a tetravalent element or mixture
of tetravalent elements, (2) optionally at least one active source
of an oxide of a trivalent element or mixture of trivalent
elements, (3) at least one active source of an alkali metal, (4)
seed crystals capable of forming SSZ-13, (5) benzyl
trimethylammonium cation in an amount sufficient to form crystals
of zeolite SSZ-13, the benzyl trimethylammonium cation being used
in the absence of a 1-adamantammonium cation, and (6) an amount of
water that is not substantially in excess of the amount required to
cause and maintain crystallization of the SSZ-13; and b. heating
said reaction mixture at crystallization conditions for sufficient
time to form crystallized material containing crystals of said
SSZ-13, wherein said reaction mixture during crystallization has a
water to (1) molar ratio between about 1 and about 5.
24. The method of claim 23, wherein the heating said reaction
mixture at crystallization conditions is done in the absence of an
external liquid phase.
Description
[0001] This application claims benefit under 35 USC 119 of
Provisional Application 60/882,010, filed Dec. 27, 2006.
FIELD OF THE INVENTION
[0002] The present invention relates to a process for producing the
crystalline zeolite designated SSZ-13 from a reaction mixture.
BACKGROUND
[0003] Molecular sieves are a commercially important class of
crystalline materials. They have distinct crystal structures with
ordered pore structures which are demonstrated by distinct X-ray
diffraction patterns. The crystal structure defines cavities and
pores which are characteristic of the different species.
[0004] Molecular sieves identified by the International Zeolite
Associate (IZA) as having the structure code CHA are known. For
example, the molecular sieve known as SSZ-13 is a known crystalline
CHA material. It is disclosed in U.S. Pat. No. 4,544,538, issued
Oct. 1, 1985 to Zones, which is incorporated by reference herein in
its entirety. In U.S. Pat. No. 4,544,538, the SSZ-13 molecular
sieve is prepared in the presence of
N,N,N-trimethyl-1-adamantammonium cation which serves as a
structure directing agent ("SDA"), also known as on organic
template. However, this SDA is costly, which makes the synthesis of
SSZ-13 using this SDA costly. This cost can limit the usefulness of
SSZ-13 in commercial processes. Thus, it would be desirable to find
a way to synthesize SSZ-13 without having to use the costly
N,N,N-trimethyl-1-adamantammonium cation SDA.
[0005] One way of reducing the amount of the
N,N,N-trimethyl-1-adamantammonium cation SDA in the synthesis of
SSZ-13 is disclosed in copending Provisional Application No.
60/826,882, filed Sep. 25, 2006 by Zones. There, the amount of
N,N,N-trimethyl-1-adamantammonium cation SDA needed to synthesize
SSZ-13 is reduced significantly by the addition to the SSZ-13
reaction mixture of benzyl trimethylammonium cation (e.g., benzyl
trimethylammonium hydroxide).
[0006] While this synthesis method can provide significant cost
savings, it still requires the use of the costly
N,N,N-trimethyl-1-adamantammonium cation SDA.
[0007] It has now been found that SSZ-13 can be prepared using
benzyl trimethylammonium cation ("BzTMA cation") in the absence of
a 1-adamantammonium cation, such as
N,N,N-trimethyl-1-adamantammonium cation.
[0008] U.S. Pat. No. 5,558,851, issued Sep. 24, 1996 to Miller,
discloses a method for preparing a crystalline aluminosillicate
zeolite from a reaction mixture containing only sufficient water so
that the reaction mixture may be shaped if desired. In the method,
the reaction mixture is heated at crystallization conditions and in
the absence of an external liquid phase, so that excess liquid need
not be removed from the crystallized material prior to drying the
crystals. U.S. Pat. No. 5,558,851 is incorporated by reference
herein in its entirety.
SUMMARY
[0009] There is provided a method for preparing crystalline zeolite
SSZ-13 said method comprising: [0010] a. preparing a reaction
mixture comprising (1) at least one active source of an oxide of a
tetravalent element or mixture of tetravalent elements, (2)
optionally at least on active source of an oxide of a trivalent
element or mixture of trivalent elements; (3) at least one active
source of an alkali metal, (4) seed crystals capable of forming
SSZ-13, (5) benzyl trimethylammonium cation in an amount sufficient
to form crystals of zeolite SSZ-13, the benzyl trimethylammonium
cation being used in the absence of a 1-adamantammonium cation, and
(6) an amount of water that is not substantially in excess of the
amount required to cause and maintain crystallization of the
SSZ-13; and [0011] b. heating said reaction mixture at
crystallization conditions and in the absence of an external liquid
phase for sufficient time to form crystallized material containing
crystals of said SSZ-13.
[0012] Further provided is a method for preparing shaped
crystalline zeolite SSZ-13, said method comprising: [0013] a.
preparing a reaction mixture comprising at least (1) at least one
active source of an oxide of a tetravalent element or mixture of
tetravalent elements, (2) optionally at least on active source of
an oxide of a trivalent element or mixture of trivalent elements,
(3) at least one active source of an alkali metal, (4) seed
crystals capable of forming SSZ-13, (5) benzyl trimethylammonium
cation in an amount sufficient to form crystals of zeolite SSZ-13,
the benzyl trimethylammonium cation being used in the absence of a
1-adamantammonium cation, and (6) an amount of water that is not
substantially in excess of the amount required to cause and
maintain crystallization of the SSZ-13; [0014] b. forming said
reaction mixture into shaped particles; and [0015] c. heating said
shaped particles at crystallization conditions for sufficient time
to form crystals of said SSZ-13 within said shaped particles.
[0016] Also provided is a molecular sieve having a composition, as
synthesized and in the anhydrous state, comprising (1) a
tetravalent oxide or mixture of tetravalent oxides (e.g., silicon
oxide, germanium oxide or mixtures thereof), (2) optionally, a
trivalent oxide or mixtures of trivalent oxides (e.g., aluminum
oxide, boron oxide, gallium oxide, iron oxide or mixtures thereof)
arid (3) benzyl trimethylammonium cation, wherein the as
synthesized SSZ-13 does not contain a 1-adamantammonium cation.
[0017] Also provided is a method for preparing crystalline zeolite
SSZ-13, said method comprising: [0018] a. preparing a reaction
mixture comprising (1) at least one active source of an oxide of a
tetravalent element or mixture of tetravalent elements, (2)
optionally at least one active source of an oxide of a trivalent
element or mixture of trivalent elements, (3) at least one active
source of an alkali metal, (4) seed crystals capable of forming
SSZ-13, (5) benzyl trimethylammonium cation in an amount sufficient
to form crystals of zeolite SSZ-13, the benzyl trimethylammonium
cation being used in the absence of a 1-adamantammonium cation, and
(6) an amount of water that is not substantially in excess of the
amount required to cause and maintain crystallization of the
SSZ-13; and [0019] b. heating said reaction mixture at
crystallization conditions for sufficient time to form crystallized
material containing crystals of said SSZ-13, wherein said reaction
mixture during crystallization has a water to (1) molar ratio
between about 1 and about 5.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0020] The present invention relates to a method of preparing small
pore zeolite-13. As used herein, the term "small pore zeolite"
refers to zeolites having a pore size of less than 5 Angstroms,
including those in which the pores have 8 membered rings. The small
pore zeolite SSZ-13 can have a mole ratio of (1) a tetravalent
oxide or mixture of tetravalent oxides (e.g., silicon oxide,
germanium oxide or mixtures thereof) to a (2) trivalent oxide or
mixtures of trivalent oxides (e.g., aluminum oxide, boron oxide,
gallium oxide, iron oxide or mixtures thereof) in the zeolite
framework of greater than 12, including mole ratios of 200 or
more.
[0021] The reaction mixture from which and in which the small pore
zeolite SSZ-13 is crystallized comprises at least one active source
of a tetravalent oxide or mixture of tetravalent oxides (e.g.,
silicon oxide, germanium oxide or mixtures thereof) and at least
one trivalent oxide or mixtures of trivalent oxides (e.g., aluminum
oxide, boron oxide, gallium oxide, iron oxide or mixtures thereof),
a structure directing agent ("SDA") capable of forming the SSZ-13
zeolite, and an amount of water not substantially in excess of the
amount required to cause and maintain crystallization of zeolite
SSZ-13. As used herein, the term "not substantially in excess of
the amount required to cause and maintain crystallization" means
the minimum amount of water required is that which causes and
maintains Crystallization of zeolite SSZ-13. This amount of water
is considerably less than that required in conventional processes
for preparing zeolites. While an amount slightly in excess of this
minimum amount may be employed (especially if it is required to
allow the reaction mixture to be thoroughly mixed and/or kneaded),
the amount of water employed in the reaction mixture should not be
so great that the reaction mixture turns into a solution or fluid
gel.
[0022] The amount of liquid required in the reaction mixture of the
present invention, where the liquid may include aqueous and,
organic liquids (e.g., the SDA), is that amount which is needed to
adequately blend the mixture. Thus, a reaction mixture is prepared
by mixing water with active sources of SSZ-13 zeolite to form a
uniform mass that can be, for example, in the form of a heavy
paste-like consistency or in the form of a powder or granules. The
active sources will be in a form which can be easily blended into a
uniform mass, and may be, for example, powders, hydrated particles,
or concentrated aqueous solutions. Sufficient water is added to wet
all the powders during mixing and/or kneading of the reaction
mixture. Alternatively, sufficient water is added that the powders
may be kneaded into a uniform and generally homogeneous,
self-supporting mixture. It is not necessary that all of the active
sources be readily soluble in water during kneading, since the
water added to the active sources will be insufficient to make a
fluid-like mixture. The amount of water added depends on the mixing
apparatus and on the active sources employed. Those familiar with
the art can readily determine without undue experimentation the
amount of liquid required to properly mix active sources of the
zeolite. For example, hydrated sources of the zeolite may require
relatively less water, and dried sources may require relatively
more. Though it is preferred that the mixture be blended and/or
kneaded until the mixture has a uniform, homogeneous appearance,
the length of time devoted to kneading the mixture is not critical
in the present invention.
[0023] The water content of the reaction mixture after blending
and/or kneading may be further adjusted, for example, by drying or
by the addition of water so that the reaction mixture has the
desired consistency.
[0024] In some embodiments, it is important, in preparing the
reaction mixture used to make SSZ-13, that the amount of water
present in the reaction mixture as prepared for the crystallization
step be sufficient to cause and maintain crystallization of said
SSZ-13, but not so much that the water forms a liquid phase
external to the reaction mixture, or transforms the reaction
mixture into a solution or fluid gel. Conveniently, the reaction
mixture will be in the form of granules, a powder or a
self-supporting mass. While it is not a requirement to form the
reaction mixture into shaped particles before the reaction mixture
is subjected to crystallization conditions, it may be desired in
many cases to do so. In this case, the amount of water used in the
reaction mixture of this invention is less than the amount of water
required in conventional processes for preparing zeolites. Thus,
during the crystallization step according to the present process,
there is no separate liquid phase present which must be removed
from the crystallized material at the end of the crystallization
step by, for example filtering or decanting, prior to drying the
crystals. Also, the amount of water present in the reaction mixture
is insufficient to cause the reaction mixture to collapse or
"melt", i.e., once the reaction mixture is formed (including any
adjustment in the liquid content that may be needed), the resulting
mass is self-supporting. It is important to note that as used
herein the term "self-supporting" (or any equivalent thereof)
refers to a reaction mixture that does not collapse or "melt" under
its own weight. This term includes the case where the reaction
mixture is comprised of individual granules in which each granule
is self-supporting or a powder in which each particle in the powder
is self-supporting.
[0025] The solids content of the reaction mixture will depend on
the particular composition of the SSZ-13 desired. SSZ-13 zeolites
having a very high mole ratio of tetravalent oxide to trivalent
oxide are within the scope of the process, including zeolites
having a mole ratio of tetravalent oxide (e.g., silicon oxide,
germanium oxide or mixtures thereof) to trivalent oxide (e.g.,
aluminum oxide, boron oxide, gallium oxide, iron oxide or mixtures
thereof) of greater than 12, including zeolites having such a mole
ratio of 200 and higher. Also included are SSZ-13 zeolites which
are essentially free of the trivalent oxide(s) such as aluminum
oxide, i.e.; the oxides in the zeolite are essentially all
tetravalent oxide (e.g., all silicon oxide). Especially when
commercial silica sources are used, aluminum is almost always
present to a greater or lesser degree. Thus, by "aluminum free" is
meant that no aluminum is intentionally added to the reaction
mixture, e.g., as an alumina or aluminate reagent, and that to the
extent aluminum is present, it occurs only as a contaminant in the
reagents. Other metallic components which may be added to the
reaction mixture include, for example, active sources of germanium
oxide, aluminum oxide, boron oxide, gallium oxide, iron oxide and
mixtures thereof.
[0026] Typical sources of silicon oxide (SiO.sub.2) include
silicates, silica hydrogel, silicic acid, colloidal silica, fumed
silica, tetraalkyl orthosilicates silica hydroxides, precipitated
silica and clays. Typical sources of aluminum oxide
(Al.sub.2O.sub.3) when used in the reaction mixture include
aluminates, alumina, and aluminum compounds such as AlCl.sub.3,
Al.sub.2(SO.sub.4).sub.3, aluminum hydroxide (Al(OH.sub.3)), kaolin
clays, and other zeolites. Germanium, boron, gallium and iron can
be added in forms corresponding to their aluminum and silicon
counterparts. Salts, particularly alkali metal halides such as
sodium chloride, can be added to or formed in the reaction mixture.
They are disclosed in the literature as aiding the crystallization
of zeolites while preventing silica occlusion in the lattice.
[0027] The reaction mixture also comprises one or more active
sources of alkali metal oxide. Sources of lithium, sodium and
potassium, are conveniently employed with sodium being a typical
alkali metal. Any alkali metal compound which is not detrimental to
the crystallization process is suitable. Non-limiting examples
include alkali metal oxides, hydroxides, nitrates, sulfates,
halogenides, oxalates, citrates and acetates.
[0028] In one embodiment of the present invention, depending on the
consistency of the reaction mixture, it may be able to form the
reaction mixture into a desired, self-supporting shape before the
crystallization step (referred to herein as the "preforming step"),
thereby reducing the number of process steps required to prepare
catalytic materials containing the zeolite prepared in the mixture.
Prior to forming the reaction mixture, it may be necessary to
change the liquid content of the reaction mixture, either by drying
or by adding more liquid, in order to provide a formable mass which
retains its shape. In general, for most shaping methods, water will
generally comprise from about 20 percent to about 60 percent by
weight, and preferably from about 30 percent to about 50 percent by
weight of the reaction mixture.
[0029] In the preforming step, the reaction mixture can be formed
into shaped particles. Methods for preparing the particles are well
known in the art, and include, for example, extrusion, spray
drying, granulation, agglomerization and the like. The particles
are preferably of a size and shape desired for the ultimate
catalyst, and may be in the form of, for example, extrudates,
spheres, granules, agglomerates and prills. The particles will
generally have a cross sectional diameter between about 1/64 inch
and about 1/2 inch, and preferably between about 1/32 inch and
about 1/4 inch, i.e. the particles will be of a size to be retained
on a 1/64 inch, and preferably on a 1/32 inch screen and will pass
through a 1/2 inch, and preferably through a 1/4 inch screen.
[0030] In one embodiment, the shaped particles prepared from the
reaction mixture will contain sufficient water to retain a desired
shape. Additional water is not required in the mixture in order to
initiate or maintain crystallization within the shaped particle.
Indeed, it may be preferable to remove some of the excess water
from the shaped particles prior to crystallization. Convention
methods for drying wet solids can be used to dry the shaped
particles, and may include, for example drying in air or an inert
gas such as nitrogen or helium at temperatures below about
200.degree. C. and at pressures from subatmospheric to about 5
atmospheres pressure.
[0031] Naturally occurring clays, e.g., bentonite, kaolin,
montmorillonite, sepiolite and attapulgite, are not required, but
may be included in the shaped particles prior to crystallization to
provide particles having good crush strength. Such clays can be
used in the raw state as originally mined or can be initially
subjected to calcination, acid treatment or chemical modification.
Microcrystalline cellulose has also been found to improve the
physical properties of the particles.
[0032] According to the present process, zeolite SSZ-13 is
crystallized either within the reaction mixture or within the
shaped particles made from the reaction mixture. In either case,
the composition of the reaction mixture from which the SSZ-13 is
formed has the following molar composition ranges:
TABLE-US-00001 Composition Molar Range Example Embodiment
YO.sub.2/W.sub.2O.sub.3 20-.infin. 20-100 M.sup.+/YO.sub.2 0.1-0.4
0.2-0.4 R/YO.sub.2 0.001-0.4 0.01-0.3 OH.sup.-/YO.sub.2 0.2-0.6
0.4-0.6 H.sub.2O/YO.sub.2 1-5 2-4
where Y is silicon, germanium or both, W is aluminum, boron,
gallium, iron, or a mixture thereof, M.sup.+ is an alkali metal
ion, preferably sodium, and R is a benzyl trimethylammonium cation,
the benzyl trimethylammonium cation being used in the absence of a
1-adamantammonium cation.
[0033] As stated above, the liquid present in the reaction mixture
(which may be in the form of shaped particles) may be a combination
of aqueous and organic liquids, so long as the amount of water
present is sufficient to cause and maintain crystallization of the
SSZ-13 zeolite, while at the same time optionally keeping the
reaction mixture self-supporting. Since the total liquid content
may affect, for example, the physical strength of any shaped
particles made from the reaction mixture, it is preferred that the
total volatiles content of the reaction mixture during
crystallization be in the range of between about 20% and about 60%
(w/w), and preferably between about 30% and about 60% (w/w), where
the total volatiles content is the measure of total volatile
liquid, including water, in the reaction mixture. It is a feature
of the present process that no additional liquid beyond that
required to cause and maintain crystallization of the SSZ-13 is
required for crystallization of the SSZ-13 within the reaction
mixture.
[0034] In one embodiment, crystallization of the zeolite takes
place in the absence of an external liquid phase, i.e., in the
absence of a liquid phase separate from the reaction mixture. In
general, it is not detrimental to the present process if some
liquid water is present in contact with the reaction mixture or
with the shaped particles during crystallization, and it can be
expected that some water may appear on the surface of the reaction
mixture during crystallization. However, it is an objective of the
present invention to provide a method of crystallizing SSZ-13 in
such a way as to minimize the amount of water which must be treated
and/or discarded following crystallization. To that end, the
present method provides a method of synthesizing SSZ-13 which
requires no additional water for crystallization beyond a
sufficient amount of water required to cause and maintain
crystallization of the SSZ-13, while at the same time optionally
keeping the reaction mixture self-supporting. Indeed, under certain
conditions, liquid water present during crystallization may alter
the form of the reaction mixture or shaped particles, and, in
extreme circumstances, may cause the reaction mixture or shaped
particles to lose their integrity or to dissolve.
[0035] Crystallization is conducted at an elevated temperature and
usually in an autoclave so that the reaction mixture is subject to
autogenous pressure until the small pore zeolite crystals are
formed. The temperatures during the hydrothermal crystallization
step are typically maintained from about 140.degree. C. to about
200.degree. C.
[0036] It is an important feature of the present process that the
crystallization of the SSZ-13 is frequently accelerated relative to
conventional crystallization methods. Thus, the crystallization
time required to form crystals will typically range from about 1
hour to about 10 days, and more frequently from about 3 hours to
about 4 days.
[0037] The SSZ-13 is crystallized within the reaction mixture,
which comprises amorphous, non-crystalline reagents. Crystals of
SSZ-13 (i.e., "seed" crystals) are added to the mixture prior to
the crystallization step, and methods for enhancing the
crystallization of zeolites by adding "seed" crystals are well
known. The seed crystals are employed in amounts from about 1 to
about 10 wt. % of the weight of silicon oxide (calculated from the
amount of active silica source) in the reaction mixture.
[0038] Once the SSZ-13 crystals have formed, the crystals may be
water-washed and then dried, e.g., at 90.degree. C. to 150.degree.
C. for from 8 to 24 hours. The drying step can be performed at
atmospheric or subatmospheric pressures.
[0039] The present invention also includes SSZ-13 made by the
process of this invention in its as-synthesized state. The term
"as-synthesized" refers to the SSZ-13 in its form prior to removal
of the BzTMA cation by thermal treatment (e.g., calcination) or
other methods. Thus, the as-synthesized SSZ-13 has a composition
comprising (1) a tetravalent oxide or mixture of tetravalent oxides
(e.g., silicon oxide, germanium oxide or mixtures thereof), (2)
optionally, a trivalent oxide or mixtures of trivalent oxides
(e.g., aluminum oxide, boron oxide, gallium oxide, iron oxide or
mixtures thereof) and (3) BzTMA cation, wherein the as-synthesized
SSZ-13 does not contain a 1-adamantammonium cation.
[0040] The SSZ-13 zeolite may be used in catalysts (such as for
converting methanol to light olefins such as ethylene and
propylene), in separations (such as in mixed matrix membranes for
separating CO.sub.2 from methane), and in environmental
applications (such as adsorption of CO and light hydrocarbons).
When shaped particles are formed from the reaction mixture
described hereinbefore, they may be of a size and shape desired for
the use to which the SSZ-13 will be put. Alternatively, the SSZ-13
pore zeolite can be composited with other materials resistant to
the temperatures and other conditions using techniques such as
spray drying, extrusion and the like.
[0041] The following examples demonstrate, but do not limit, the
present invention.
EXAMPLE 1
[0042] Twenty grams of Hi-Sil 233 (source of silicon oxide) was
placed in a suitable vessel. Reheis F-2000 alumina (1.7 grams) was
dissolved in 5 grams of a 50% aqueous NaOH solution and then added
to the Hi-Sil 233 in the vessel. The resulting mixture is mixed
thoroughly. To the resulting mixture was added 1 gram of SSZ-13
seed crystals, and the mixture thoroughly mixed again for 5
minutes. 23.3 Grams of a 2.36 mmole/gram solution of benzyl
trimethylammonium hydroxide was added slowly to the mixture while
mixing. 8 Grams of D.I. water was added slowly and the resulting
mixture mixed thoroughly for 1 hour. The resulting mixture was in
the form of slightly wet granules with a volatiles content of
59.6%.
[0043] The molar composition of the synthesis mix was:
TABLE-US-00002 SiO.sub.2/AL.sub.2O.sub.3 35 Na+/SiO.sub.2 0.21
R/SiO.sub.2 0.18 OH-/SiO.sub.2 0.39 H.sub.2O/SiO.sub.2 4.8
[0044] The resulting reaction mixture was divided into two parts
(parts A and B), each part was placed in separate 3.5 inch pipe
autoclaves and crystallized at 160.degree. C. for 2 days (for Part
A) and 4 days (for part B).
[0045] The products were washed with pH 12.5 water twice, then once
with plain D.I. water. The products were filtered and dried in a
vacuum oven at 120.degree. C. overnight, then calcined at
1100.degree. F. for 6 hours.
[0046] The resulting products were SSZ-13.
EXAMPLE 2
[0047] Twenty grams of Hi-Sil 233 (source of silicon oxide) was
placed in a suitable vessel. Reheis F-2000 alumina (1.7 grams) was
dissolved in 7.9 grams of a 50% aqueous NaOH solution and then
added to the Hi-Sil 233 in the vessel. The resulting mixture is
mixed thoroughly. To the resulting mixture was added 1 gram of
SSZ-13 seed crystals, and the mixture thoroughly mixed again for 5
minutes. 23.3 Grams of a 2.36 mmole/gram solution of benzyl
trimethylammonium hydroxide was added slowly to the mixture while
mixing. 8 Grams of D.I. water was added slowly and the resulting
mixture mixed thoroughly for 1 hour. The resulting mixture was in
the form of slightly wet granules with a volatiles content of
61%.
[0048] The molar composition of the synthesis mix was:
TABLE-US-00003 SiO.sub.2/Al.sub.2O.sub.3 35 Na.sup.+/SiO.sub.2 0.33
R/SiO.sub.2 0.18 OH.sup.-/SiO.sub.2 0.51 H.sub.2O/SiO.sub.2 5.2
[0049] The resulting reaction mixture was placed in a 3.5 inch pipe
autoclave and crystallized at 170.degree. C. for 2 days.
[0050] The product was washed with pH 11 water twice, then once
with plain D.I. water. The product was filtered and dried in a
vacuum oven at 120.degree. C. overnight, then calcined at
1100.degree. F. for 6 hours.
[0051] The resulting product was SSZ-13.
EXAMPLE 3
[0052] Twenty grams of Hi-Sil 233 (source of silicon oxide) was
placed in a suitable vessel. 1.2 grams of Barcroft 250 alumina (52%
Al2O3) was dissolved in 7.9 grams of a 50% aqueous NaOH solution
and then added to the Hi-Sil 233 in the vessel. The resulting
mixture is mixed thoroughly. To the resulting mixture was added 1
gram of SSZ-13 seed crystals, and the mixture thoroughly mixed
again for 5 minutes. 23.3 Grams of a 2.36 mmole/gram solution of
benzyl trimethylammonium hydroxide was added slowly to the mixture
while mixing. 6 Grams of D.I. water was added slowly and the
resulting mixture mixed thoroughly for 1 hour. The resulting
mixture was in the form of slightly wet granules with a volatiles
content of 60%.
[0053] The molar composition of the synthesis mix was:
TABLE-US-00004 SiO.sub.2/Al.sub.2O.sub.3 50 Na.sup.+/SiO.sub.2 0.33
R/SiO.sub.2 0.18 OH.sup.-/SiO.sub.2 0.51 H.sub.2O/SiO.sub.2 5.0
[0054] The resulting reaction mixture was placed in a 3.5 inch pipe
autoclave and crystallized at 170.degree. C. for 2 days.
[0055] The product was washed with pH 11 water twice, then once
with plain D.I. water. The product was filtered and dried in a
vacuum oven at 120.degree. C. overnight, then calcined at
1100.degree. F. for 6 hours.
[0056] The resulting product was SSZ-13.
[0057] For the purposes of this specification and appended claims,
unless otherwise indicated, all numbers expressing quantities,
percentages or proportions, and other numerical values used in the
specification and claims, are to be understood as being modified in
all instances by the term "about" Furthermore, all ranges disclosed
herein are inclusive of the endpoints and are independently
combinable.
[0058] All of the publications, patents and patent applications
cited in this application are herein incorporated by reference in
their entirety to the same extent as if the disclosure of each
individual publication, patent application or patent was
specifically and individually indicated to be incorporated by
reference in its entirety.
[0059] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to make and use the invention. Many
modifications of the exemplary embodiments of the invention
disclosed above will readily occur to those skilled in the art.
Accordingly, the invention is to be construed as including all
structure and methods that fall within the scope of the appended
claims.
* * * * *