Molecular sieve abstract
To control the pressure generated by the decomposition of quaternary
ammonium hydroxides during the crystallization of molecular sieve
materials at elevated temperatures, to levels below the mechanical
limits of the equipment, the present invention substitutes halide
salts of the same quaternary ammonium structure directing agent
compound for some fraction of the hydroxide compound. In addition,
because the quaternary ammonium hydroxides are generally more expensive
than the corresponding halides, using a combination of the two reduces
the cost of manufacturing the molecular sieve product.
Molecular sieve claims
We claim as our invention:
1. A method for synthesizing molecular sieve materials at temperatures
in excess of about 125.degree. C. using organic structure directing
agents having a quaternary ammonium hydroxide group, comprising
substituting an effective amount of a like organic structure directing
agent in the quaternary ammonium halide form, for a predetermined
fraction (but less than all) of the quaternary ammonium hydroxide,
such that final pressure is reduced without substantially reducing
the reaction temperature.
2. The method of claim 1 for synthesizing ZSM-12 wherein the organic
structure directing agent is selected from hydroxides and halides
of the group of TEA, MTEA, dimethylpyridinum. pyrollidinium, diethyldimethylammonium,
dibenzyldimethylammonium, hexamethylammonium, diquat-4 diquat-5
diquat-6 decamethonium, N-containing polymers, (PhCH.sub.2)Me.sub.3N,
(PhCH.sub.2).sub.2Me.sub.2N, Et.sub.2Me.sub.2N, benzyltrialkylammonium.sup.+,
BzNR.sub.3 and dibenzyldiethylammonium.sup- .+.
3. The method of claim 1 for synthesizing zeolite Beta, wherein
the organic structure directing agent is selected from hydroxides
and halides of the group of TEA, TEA in the presence of diethanoleamine,
Dibenzyl-14-diazobicyclo[2.2.2.]octane, dibenzyldimethylammonium
and benzyldimethylamine + benzylhalide
4. The method of claim 2 wherein up to about 70% of the quaternary
ammonium hydroxide is substituted with the halide form.
5. The method of claim 2 wherein up to about 50% of the quaternary
ammonium hydroxide is substituted with the halide form.
6. The method of claim 4 wherein the halide form is a bromide.
7. The method of claim 3 wherein up to about 50% of the quaternary
ammonium hydroxide is substituted with the halide form.
8. The method of claim 3 wherein up to about 35% of the quaternary
ammonium hydroxide is substituted with the halide form.
9. The method of claim 7 wherein the halide form is a bromide.
10. A method of reducing the cost of synthesis of molecular sieve
materials from mixtures containing organic structure directing agents
having a quaternary ammonium hydroxide group, by substituting an
effective amount of a like organic structure directing agent in
the quaternary ammonium halide form, for a predetermined fraction
(but less than all) of the quaternary ammonium hydroxide.
11. A method for reducing the pressure, without reducing the temperature
to below about 125.degree. C.,during synthesis of molecular sieve
materials from mixtures containing organic structure directing agents
having a quaternary ammonium group, wherein the organic structure
directing agent comprises a mixture of the hydroxide and halide
forms.
Molecular sieve description
RELATED APPLICATIONS
[0001] The present application is a continuation-in-part of U.S.
application Ser. No 60/335417 filed Nov. 15 2001 entitled "Methods
for Preparing Titanium-Silicate Molecular Sieves" and U.S.
application Ser. No. 60/387945 filed Jun. 12 2002 entitled "TS-PQ
Titano-Silicate Molecular Sieves and Methods For Synthesis and Use
Thereof."
FIELD OF THE INVENTION
[0002] Molecular sieve compounds, such as synthetic zeolites, are
often synthesized using organic structure directing agents, such
as quaternary ammonium compounds. At the relatively high temperatures
used for efficient synthesis of these compounds, the organic structure
directing agents tend to decompose, yielding high vapor pressure
fragments. These decomposition products, in turn, can cause mechanical
failure of the reaction vessels in which the synthesis is conducted,
unless the reaction conditions are moderated to reduce the pressure,
and such moderation, in turn, reduces the yield of the synthesis.
The present invention comprises a method for reducing the pressure
within the reaction vessel, while maintaining optimal yield of high-quality
molecular sieve product.
BACKGROUND OF THE INVENTION
[0003] The synthesis of zeolites such as ZSM-12 in the presence
of an organic quaternary ammonium compound is well understood in
the prior art. (U.S. Pat. No. 3832449 teaches the use of TEAOH,
while U.S. Pat. No. 4452769 teaches the use of MTEAOH.) The decomposition
of such compounds, via the Hofmann elimination reaction, to yield
a high vapor pressure organic fraction (usually a mixture of alkenes
and amines,) is also well understood in the prior art. The Hofmann
elimination reaction is readily apparent when a quaternary ammonium
hydroxide is heated to 125.degree. C. or higher, (see Morrison &
Boyd, Organic Chemistry, 2.sup.nd edition, 1966 Allyn & Bacon,
Inc., Boston, Mass., USA)
[0004] The pressure limit of zeolite synthesis equipment may be
due to several factors, including valve type and construction, agitator
and other seals, vessel materials and thickness, and the like. Prior
art methods that have been used to reduce the pressure generated
during a zeolite crystallization include lowering the operating
temperature and/or significant reduction of the alkalinity of the
reaction mixture. Both of these methods increase the time required
to crystallize the desired zeolite and the risk of producing contaminated
product. Another way to manage the high pressure resulting from
the use of quaternary ammonium hydroxides is to increase the mechanical
limit of the equipment, by installing better quality valves, agitator
seals, pressure relief equipment, etc., and improving the structural
integrity of the reactor. All of these prior art methods add significant
cost to the manufacture of a zeolite.
BRIEF DESCRIPTION OF THE INVENTION
[0005] To control the pressure generated by the decomposition of
quaternary ammonium hydroxides during the crystallization of zeolites
at elevated temperatures, to levels below the mechanical limits
of the equipment, the present invention substitutes halide salts
of the same quaternary ammonium compound for some fraction of the
hydroxide compound. In addition, because the quaternary ammonium
hydroxides are generally more expensive than the corresponding halides,
using a combination of the two reduces the cost of manufacturing
the zeolite product.
DETAILED DESCRIPTION OF THE INVENTION
[0006] The present invention reduces the amount of the quaternary
ammonium hydroxide in the zeolite synthesis reaction mixture and
thus to some degree, the alkalinity of the mixture, in order to
reduce the quantity of decomposition products, usually alkenes and
amines, having high vapor pressures. These compounds contribute
significantly to the total pressure developed during a zeolite crystallization.
The quaternary ammonium halide substitutes do not decompose directly
at neutral or lower pH. The dissociated cations derived from them
may however, in the presence of the alkalinity required for zeolite
synthesis, also partially convert to the above mentioned decomposition
products. Their presence helps to ensure the purity of the final
zeolite product by maintaining the proportion of quaternary ammonium
cation in the reaction mixture.
[0007] The organic structure directing agent (SDA) may be any known
directing agent for the specified molecular sieve structural type.
The SDA is preferably selected from the group consisting of compounds
containing quaternary ammonium cations. Hydroxides of those cations
are preferable because, in addition to their SDA function, they
provide a source of alkalinity. It is known in the art that many
other base materials are effective in such reactions, but tetraethylammonium
hydroxide (TEAOH) is preferred in the present invention for the
synthesis of zeolite Beta and ZSM-12.
[0008] It has been found that complete substitution of the halide
for the hydroxide species results in undesireable contamination
of the product by another zeolite phase, due to a reduction of the
alkalinity of the reaction mixture. Similarly, adding another source
of alkalinity, such as sodium hydroxide, also causes a contaminant
phase to grow.
[0009] The halide for hydroxide substitution of the present invention
has been used in the synthesis of two different zeolites, Beta (BEA)
at several different SiO.sub.2/Al.sub.2O.sub.3 ratios, and ZSM-12
(MTW). Examples for each are presented herein, together with examples
of failed synthesis attempts that illustrate the critical nature
of the partial substitution of the hydroxide species with the halide
species. In these examples we found that TEAOH may be used in combination
with TEA-halide and/or halide salts, up to preferably about 70 mole
percent substitution of halide for hydroxide.
[0010] In order to prepare ZSM-12 in a commercial reactor, a combination
of (preferably) tetraethylammonium hydroxide (TEAOH) and tetraethylammonium
bromide (TEABr) may be used to moderate the pressure. Based on the
experience of the present inventors, it is expected that this technology
may be extended to any molecular sieve materials that are typically
prepared using a quaternary ammonium hydroxide reagent.
ZSM-12 Synthesis
[0011] The method of the present invention may be useful as an
adjunct to a wide variety of synthetic methods known in the art.
For example, the method of ZSM-12 synthesis disclosed in U.S. Pat.
No. 3832449 which teaches the use of TEAOH, suggests that the
use of TEABr and other TEA Halides may be practiced. One skilled
in the art will recognize that the lower molecular weight halides
(F and Cl) may be more corrosive, thus increasing the cost of reaction
equipment, but may be employed in the method of the present invention.
Similarly, one skilled in the art will recognize that higher molecular
weight halogens may increase the mass that must be transported in
the reaction, thus having a negative effect on kinetics without
other substantial benefits, but may, nonetheless, be employed in
the method of the present invention. One skilled in the art will
also recognize that the examples in this patent that used halide
compounds all were conducted at low temperature, 100.degree. C.,
for very long times greater than 50 days. Such conditions are not
economically viable on commercial scale. The present invention defines
a preferred region of synthesis compositions where the subject zeolites
are crystallized rapidly, in less than 5 days, in pure form and
under conditions where the final pressures achieved are low and
moreover realistic for commercial equipment.
[0012] Other organic structure directing agents known to be useful
in the synthesis of ZSM-12 and which may be substituted with a
fraction of halide for hydroxide according to the present invention
include: methyltriethylammonium (see U.S. Pat. No. 4452769); dimethylpyridinium
or pyrollidinium (see U.S. Pat. No. 4391785); diethyldimethylammonium
(see U.S. Pat. No. 4552739); dibenzyldimethylammonium (see U.S.
Pat. No. 4636373); hexamethylimmonium (see U.S. Pat. No. 5021141);
diquat-4 diquat-5 or diquat-6 (see U.S. Pat. No. 5137705); decamethonium
(see U.S. Pat. No. 5192521).
[0013] Similarly, the following organic structure directing agents
are known in the art as being useful in the synthesis of ZSM-12
and other MTW-type zeolites, CHZ5 Nu13 Theta3 TPZ-12 and may
be partially substituted with halide species for the hydroxide:
N-containing polymers, (PhCH.sub.2)Me.sub.3N, (PhCH.sub.2)Me.sub.2N,
Et.sub.2Me.sub.2N, Benzyltrialkylammonium.sup.+, BzNR.sub.3 Dibenzyldiethylammonium.sup.+.
See R. Szostak, Handbook of Molecular Sieves, 1992Van Nostrand
Reinhold, NY, N.Y., USA)
Beta Synthesis
[0014] For the synthesis of zeolite Beta, the following organic
structure directing agents may be halide-substituted according to
the method of the present invention: TEAOH (see U.S. Pat. No. 3308069);
Dibenzyldimethylammonium hydroxide (see U.S. Pat. No. 4642226).
[0015] Similarly, other known syntheses of Beta which quaternary
ammonium halides or molecules which react to form such a halide
can be improved economically by promoting faster syntheses at higher
temperature if quaternary ammonium hydroxide is substituted in part
for the quaternary halide. These include: quaternary ammonium TEABr
+ NH.sub.4OH ( M. J. Eapen et al., Zeolites, v. 14 1994 p.295);
TEA-halide + diethanoleamine (see U.S. Pat. No. 5139759); TEACl
(see WO 94/26663); Benzyldimethylamine + benzylhalide (Eur. Patent
Appl. 149846);
EXAMPLES
[0016] The raw materials, and their nominal compositions and suppliers,
used in the following examples are:
[0017] TEAOH solution-35% tetraethylammonium hydroxide aqueous
solution, SACHEM, Inc.
[0018] TEABr solution-50% tetr aethylammonium bromide aqueous solution,
SACHEM, Inc.
[0019] Sodium aluminate solution-23.4% Al.sub.2O.sub.3 19.5% Na.sub.2O
aqueous solution, Southern Ionics, Inc.
[0020] Colloidal silica solution-40% SiO.sub.2 0.5% Na.sub.2O,
aqueous solution, Nyacol, Inc.
[0021] Alumina coated colloidal silica solution-4% Al.sub.2O.sub.3
26% SiO.sub.2 aqueous solution, ONDEO Nalco, Inc.
[0022] Aluminum sulfate powder-17.5% Al.sub.2O.sub.3
[0023] Sodium silicate solution-28.7% SiO.sub.2 8.9% Na.sub.2O
aqueous solution, PQ Corporation
[0024] Precipitated silica-92.4% SiO.sub.2 balance H.sub.2O, PPG
Industries, Inc.
[0025] Potassium hydroxide solution-45% KOH, balance H.sub.2O
Example 1-Prior Art ZSM-12 Example
[0026] 273 parts of the TEAOH solution were added to 215 parts
of deionized water. To this solution, 7 parts of the sodium aluminate
solution were added and the resulting solution was mixed well. 455
parts of the colloidal silica solution were added to the previous
solution with sufficient mixing to keep the gel fluid. Finally,
50 parts of the alumina coated colloidal silica solution were added
to the gel and the mixture was agitated for 30 minutes to homogenize
the resulting gel. The molar composition of this mixture was 1.0
Al.sub.2O.sub.3/1.65 Na.sub.2O/90 SiO.sub.2/1080 H.sub.2O/18 TEAOH.
The mixture was placed in an agitated autoclave and heated to 160.degree.
C. After 72 hours at 160.degree. C. the autoclave was cooled to
ambient temperature. During the 72 hours at 160.degree. C., the
pressure in the autoclave rose continuously to about 500 psig. The
product slurry was filtered and the solids were washed with 7000
parts of deionized water. The resulting filter cake was dried at
120.degree. C. for 16 hours. X-ray diffraction analysis of the dried
solids indicated it was pure ZSM-12. A sample of the dried solids
was calcined in a static bed at 538.degree. C. for 5 hours in air.
The BET surface area of the calcined solids was measured to be 414
m.sup.2/g.
Example 2-Present Invention ZSM-12
[0027] 134 parts of the TEAOH solution were added to 229 parts
of deionized water. 5.5 parts of the sodium aluminate solution were
added to the TEAOH solution along with 134 parts of the TEABr solution.
The resulting solution was mixed well. To this solution was added
441 parts of the colloidal silica solution with good agitation to
keep the resulting mixture fluid. Finally, 58 parts of the alumina
coated colloidal silica solution were added to the gel and this
mixture was stirred well for 30 minutes to make it homogeneous.
The molar composition of this mixture was 1.0 Al.sub.2O.sub.3/1.5
Na.sub.2O/90 SiO.sub.2/1080 H.sub.2O/9 TEAOH/9 TEABr so that the
molar TEA.sup.+/SiO.sub.2 was the same as in the prior art example.
The molar OH.sup.-/SiO.sub.2 was reduced to 0.133 compared to 0.237
for the mixture of the prior art example. The mixture was placed
in an agitated autoclave and heated to 160.degree. C. After 72 hours
at 160.degree. C. the autoclave was cooled to ambient temperature.
The pressure rose continuously over the 72 hours at 160.degree.
C. to a final pressure of 330 psig. The product slurry was filtered
and the solids were washed with 7000 parts of deionized water. The
resulting filter cake was dried at 120.degree. C. for 16 hours.
X-ray diffraction analysis of the dried solids indicated it was
pure ZSM-12. A sample of the dried solids was calcined in a static
bed at 538.degree. C. for 5 hours in air. The BET surface area of
the calcined solids was measured to be 397 m.sup.2/g.
Example 3-Present Invention ZSM-12
[0028] 104 parts of the TEAOH solution were added to 232 parts
of deionized water. To this solution were added 5.5 parts of the
sodium aluminate solution and 163 parts of the TEABr solution. The
resulting solution was mixed well. 439 parts of the colloidal silica
solution were added to the solution with good agitation to keep
the mixture fluid. Finally, 57 parts of the alumina coated colloidal
silica solution were added to the gel. The final mixture was homogenized
for 30 minutes. The molar composition of this mixture was 1.0 Al.sub.2O.sub.3/1.5
Na.sub.2O/90 SiO.sub.2/1080 H.sub.2O/7 TEAOH/11 TEABr so that the
molar TEA.sup.+/SiO.sub.2 was the same as in the prior art example.
The molar OH.sup.-/SiO.sub.2 was reduced to 0.111 compared to 0.237
for the mixture of the prior art example. The mixture was placed
in an agitated autoclave and heated to 160.degree. C. After 72 hours
at 160.degree. C. the autoclave was cooled to ambient temperature.
The pressure rose continuously over the 72 hours at 160.degree.
C. to a final pressure of 315 psig. The product slurry was filtered
and the solids were washed with 7000 parts of deionized water. The
resulting filter cake was dried at 120.degree. C. for 16 hours.
X-ray diffraction analysis of the dried solids indicated it was
pure ZSM-12. A sample of the dried solids was calcined in a static
bed at 538.degree. C. for 5 hours in air. The BET surface area of
the calcined solids was measured to be 390 m.sup.2/g.
Example 4-Failed ZSM-12
[0029] To 283 parts of deionized water, 188 parts of the TEAOH
solution were added. This was followed by 7.5 parts of the sodium
aluminate solution and the resulting solution was mixed well. Next,
470 parts of the colloidal silica solution were added to the mixture
with good agitation to keep the mixture fluid. Finally, 51 parts
of the alumina coated colloidal silica solution were added to the
gel and the resulting mixture was stirred for 30 minutes to homogenize
it. The molar composition of this mixture was 1.0 Al.sub.2O.sub.3/1.65
Na.sub.2O/90 SiO.sub.2/1080 H.sub.2O/12 TEAOH. The molar TEA.sup.+/SiO.sub.2
of this mixture was 0.133 lower than the molar TEA.sup.+/SIO.sub.2
of 0.2 for the prior art example. The molar OH.sup.-/SiO.sub.2 of
the mixture of this example was 0.17 again lower than the 0.237
of the prior art example. The mixture was placed in an agitated
autoclave and heated to 160.degree. C. After 72 hours at 160.degree.
C. the autoclave was cooled to ambient temperature. The pressure
rose continuously over the 72 hours at 160.degree. C. to a final
pressure of 275 psig. The product slurry was filtered and the solids
were washed with 7000 parts of deionized water. The resulting filter
cake was dried at 120.degree. C. for 16 hours. X-ray diffraction
analysis of the dried solids indicated it was pure ZSM-12 and ZSM-5.
Example 5 -Failed ZSM-12 Example with TEABr
[0030] To 542 parts of deionized water was added 12 parts of the
aluminum sulfate powder and the aluminum sulfate was dissolved by
mixing. 177 parts of the TEABr solution were added to the solution
and the mixture was stirred. To this solution was added 78 parts
of precipitated silica, which was evenly distributed by mixing.
Finally, 191 parts of the sodium silicate solution were added to
the slurry with good agitation to keep the gel fluid. This mixture
was stirred for 30 minutes to homogenize the gel. The molar composition
of this mixture was 1.0 Al.sub.2O.sub.310 Na.sub.2O/100 SiO.sub.2/2000
H.sub.2O/20 TEABr. The molar TEA.sup.+/SiO.sub.2 was 0.2 the same
as in the prior art formulation. The molar OH.sup.-/SiO.sub.2 was
also 0.2 and was slightly lower than the 0.237 of the mixture of
the prior art example. The mixture was placed in an agitated autoclave
and heated to 160.degree. C. After 72 hours at 160.degree. C. the
autoclave was cooled to ambient temperature. The product slurry
was filtered and the solids were washed with 7000 parts of deionized
water. The resulting filter cake was dried at 120.degree. C. for
16 hours. X-ray diffraction analysis of the dried solids indicated
it was pure ZSM-5 with no trace of ZSM-12.
Example 6-Prior Art 50 SiO.sub.2/Al.sub.2O.sub.3 Beta Synthesis
[0031] 307 parts of the TEAOH solution were added to 117 parts
of deionized water followed by 27 parts of the sodium aluminate
solution. The resulting solution was mixed well. Finally, 549 parts
of the colloidal silica solution were added to the mixture with
good agitation to keep the resulting gel fluid. The final mixture
was homogenized for 30 minutes. This mix had a molar composition
of 1.0 Al.sub.2O.sub.3/2.1 Na.sub.2O/60 SiO.sub.2/600 H.sub.2O/12
TEAOH. The mixture was placed in an agitated autoclave and heated
to 160.degree. C. After 24 hours at 160.degree. C. the autoclave
was cooled to ambient temperature. The pressure in the autoclave
rose continuously over the 24 hours at 160.degree. C. to a final
pressure of about 380 psig. The product slurry was filtered and
the solids were washed with 7000 parts of deionized water. The resulting
filter cake was dried at 120.degree. C. for 16 hours. X-ray diffraction
analysis of the dried solids indicated it was pure zeolite Beta.
A sample of the dried solids was calcined in a static bed at 538.degree.
C. for 5 hours in air. The BET surface area of the calcined solids
was measured to be 707 m.sup.2/g.
Example 7-Present Invention Example for 50 SiO.sub.2/Al.sub.2O.sub.3
Beta
[0032] To 127 parts of deionized water were added 228 parts of
the TEAOH solution and 26 parts of the sodium aluminate solution.
The resulting solution was mixed well and 76 parts of the TEABr
solution were added to it with more mixing. Finally, 543 parts of
the colloidal silica solution were added to the previous solution
with good agitation to keep the gel fluid. This final mixture was
stirred well for 30 minutes to homogenize it. The molar composition
of this mixture was 1.0 Al.sub.2O.sub.3/2.1 Na.sub.2O/60 SiO.sub.2/600
H.sub.2O/9 TEAOH/3 TEABr. The molar TEA.sup.+/SiO.sub.2 of this
formulation is the same as for the prior art formulation while the
molar OH.sup.-/SiO.sub.2 was reduced to 0.22 as compared to 0.27
for the prior art example. The mixture was placed in an agitated
autoclave and heated to 160.degree. C. After 24 hours at 160.degree.
C. the autoclave was cooled to ambient temperature. The pressure
in the autoclave rose continuously over the 24 hours at 160.degree.
C. to a final pressure of about 160 psig. The product slurry was
filtered and the solids were washed with 7000 parts of deionized
water. The resulting filter cake was dried at 120.degree. C. for
16 hours. X-ray diffraction analysis of the dried solids indicated
it was pure zeolite Beta. A sample of the dried solids was calcined
in a static bed at 538.degree. C. for 5 hours in air. The BET surface
area of the calcined solids was measured to be 692 m.sup.2/g.
Example 8-Failed 50 SiO.sub.2/Al.sub.2O.sub.3 Beta
[0033] 237 parts of the TEAOH solution were added to 172 parts
of deionized water along with 27 parts of the sodium aluminate solution.
The solution was mixed well. Finally, 564 parts of the colloidal
silica solution were added to the solution with good agitation to
keep the gel fluid. The final gel was mixed for 30 minutes to make
it homogeneous. The molar composition of this gel was 1.0 Al.sub.2O.sub.3/2.1
Na.sub.2O/60 SiO.sub.2/600 H.sub.2O/9 TEAOH. The molar TEA.sup.+/SiO.sub.2
of this formulation is 0.15 compared to 0.2 for the prior art formulation.
The molar OH.sup.-/SiO.sub.2 is also lower at 0.22 for this example
compared to 0.27 for the prior art example. The mixture was placed
in an agitated autoclave and heated to 160.degree. C. After 24 hours
at 160.degree. C. the autoclave was cooled to ambient temperature.
The product slurry was filtered and the solids were washed with
7000 parts of deionized water. The resulting filter cake was dried
at 120.degree. C. for 16 hours. X-ray diffraction analysis of the
dried solids indicated it was zeolite Beta contaminated with ZSM-5.
Example 9-Prior Art 22 SiO.sub.2/Al.sub.2O.sub.3 Beta
[0034] 192 parts of the TEAOH solution were added to 130 parts
of deionized water followed by 69 parts of the sodium aluminate
solution. The resulting solution was mixed well. Finally, 609 parts
of the colloidal silica solution were added to the mixture with
good agitation to keep the resulting gel fluid. The final mixture
was homogenized for 30 minutes. This mix had a molar composition
of 1.0 Al.sub.2O.sub.3/1.77 Na.sub.2O/25.6 SiO.sub.2/230 H.sub.2O/2.89
TEAOH. The mixture was placed in an agitated autoclave and heated
to 160.degree. C. After 48 hours at 160.degree. C. the autoclave
was cooled to ambient temperature. The pressure in the autoclave
rose continuously over the 48 hours at 160.degree. C. to a final
pressure of about 350 psig. The product slurry was filtered and
the solids were washed with 7000 parts of deionized water. The resulting
filter cake was dried at 120.degree. C. for 16 hours. X-ray diffraction
analysis of the dried solids indicated it was pure zeolite Beta.
A sample of the dried solids was calcined in a static bed at 538.degree.
C. for 5 hours in air. The BET surface area of the calcined solids
was measured to be 648 m.sup.2/g.
Example 10-Present Invention 22 SiO.sub.2/Al.sub.2O.sub.3 Beta
[0035] To 26 parts of deionized water were added 136 parts of the
TEAOH solution, 49 parts of the sodium aluminate solution and 25
parts of the potassium hydroxide solution. The resulting solution
was mixed well and 68 parts of the TEABr solution were added to
it with more mixing. 553 parts of the colloidal silica solution
were added to the previous solution with good agitation to keep
the gel fluid. Finally, 143 parts of the alumina coated colloidal
silica solution were added to the gel with continued good mixing.
This final mixture was stirred well for 30 minutes to homogenize
it. The molar composition of this mixture was 1.0 Al.sub.2O.sub.3/1.18
Na.sub.2O/0.59 K.sub.2O/25.6 SiO.sub.2/205 H.sub.2O/1.93 TEAOH/0.96
TEABr. The molar TEA.sup.+/SiO.sub.2 of this formulation is the
same as for the prior art formulation while the molar OH /SiO.sub.2
was reduced to 0.214 as compared to 0.251 for the prior art example.
The mixture was placed in an agitated autoclave and heated to 160.degree.
C. After 48 hours at 160.degree. C. the autoclave was cooled to
ambient temperature. The pressure in the autoclave rose continuously
over the 48 hours at 160.degree. C. to a final pressure of about
200 psig. The product slurry was filtered and the solids were washed
with 7000 parts of deionized water. The resulting filter cake was
dried at 120.degree. C. for 16 hours. X-ray diffraction analysis
of the dried solids indicated it was pure zeolite Beta. A sample
of the dried solids was calcined in a static bed at 538.degree.
C. for 5 hours in air. The BET surface area of the calcined solids
was measured to be 730 m.sup.2/g.
Example 11-Failed 22 SiO.sub.2/Al.sub.2O.sub.3 Beta
[0036] 137 parts of the TEAOH solution were added to 71 parts of
deionized water along with 74 parts of the sodium aluminate solution.
The solution was mixed well and 68 parts of the TEABr solution were
added with continued mixing. Finally, 650 parts of the colloidal
silica solution were added to the solution with good agitation to
keep the gel fluid. The final gel was mixed for 30 minutes to make
it homogeneous. The molar composition of this gel was 1.0 Al.sub.2O.sub.3/1.77
Na.sub.2O/25.6 SiO.sub.2/205 H.sub.2O/1.93 TEAOH/0.96 TEABr. The
molar TEA.sup.+/SiO.sub.2 of this formulation is the same as for
the prior art formulation while the molar OH.sup.-/SiO.sub.2 was
reduced to 0.214 as compared to 0.251 for the prior art example.
The mixture was placed in an agitated autoclave and heated to 160.degree.
C. After 48 hours at 160.degree. C. the autoclave was cooled to
ambient temperature. The product slurry was filtered and the solids
were washed with 7000 parts of deionized water. The resulting filter
cake was dried at 120.degree. C. for 16 hours. X-ray diffraction
analysis of the dried solids indicated it was mordenite.
Example 12-Failed 22 SiO.sub.2/Al.sub.2O.sub.3 Beta with TEABr
[0037] To 429 parts of the TEABr solution were added 36 parts of
the sodium aluminate solution and 18 parts of the potassium hydroxide
solution. The resulting solution was mixed well. 410 parts of the
colloidal silica solution were added to the previous solution with
good agitation to keep the gel fluid. Finally, 106 parts of the
alumina coated colloidal silica solution were added to the gel with
continued good mixing. This final mixture was stirred well for 30
minutes to homogenize it. The molar composition of this mixture
was 1.0 Al.sub.2O.sub.3/1.18 Na.sub.2O/0.59 K.sub.2O/25.6 SiO.sub.2/250
H.sub.2O/8.2 TEABr. The molar TEA.sup.+/SiO.sub.2 of this formulation
is 0.32 as compared to 0.113 for the prior art formulation while
the molar OH.sup.-/SiO.sub.2 was reduced to 0.138 as compared to
0.251 for the prior art example. The mixture was placed in an agitated
autoclave and heated to 160.degree. C. After 48 hours at 160.degree.
C. the autoclave was cooled to ambient temperature. The product
slurry was filtered and the solids were washed with 7000 parts of
deionized water. The resulting filter cake was dried at 120.degree.
C. for 16 hours. X-ray diffraction analysis of the dried solids
indicated it was still amorphous.
[0038] While the invention has been described in its preferred
embodiments, it is to be understood that the words which have been
used are words of description rather than of limitation, and that
changes may be made within the purview of the appended claims without
departing from the true scope and spirit of the invention in its
broader aspects. Rather, various modifications may he made in the
details within the scope and range of equivalents of the claims
and without departing from the spirit of the invention. The inventors
further require that the scope accorded their claims be in accordance
with the broadest possible construction available under the law
as it exists on the date of filing hereof (and of the application
from which this application obtains priority,) and that no narrowing
of the scope of the appended claims be allowed due to subsequent
changes in the law, as such a narrowing would constitute an ex post
facto adjudication, and a taking without due process or just compensation.
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