U.S. patent application number 15/492330 was filed with the patent office on 2017-08-03 for zeolite production method.
The applicant listed for this patent is The University of Tokyo, UNIZEO CO., LTD.. Invention is credited to Shanmugam Palani Elangovan, Keiji Itabashi, Yoshihiro Kamimura, Tatsuya Okubo.
Application Number | 20170217779 15/492330 |
Document ID | / |
Family ID | 45402074 |
Filed Date | 2017-08-03 |
United States Patent
Application |
20170217779 |
Kind Code |
A1 |
Itabashi; Keiji ; et
al. |
August 3, 2017 |
ZEOLITE PRODUCTION METHOD
Abstract
Disclosed is a method for readily and inexpensively producing
zeolite without using an organic structure-directing agent (organic
SDA). Specifically disclosed is a method whereby a gel containing a
silica source, an alumina source, an alkaline source and water is
reacted with zeolite seed crystals, to produce a zeolite with the
same kind of skeletal structure as the zeolite. The gel used is a
gel of a composition whereby, when a zeolite is synthesized from
this gel only, the synthesized zeolite comprises at least one of
the kinds of composite building units of the target zeolite.
Inventors: |
Itabashi; Keiji; (Tokyo,
JP) ; Okubo; Tatsuya; (Tokyo, JP) ; Kamimura;
Yoshihiro; (Tokyo, JP) ; Elangovan; Shanmugam
Palani; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UNIZEO CO., LTD.
The University of Tokyo |
Tokyo
Tokyo |
|
JP
JP |
|
|
Family ID: |
45402074 |
Appl. No.: |
15/492330 |
Filed: |
April 20, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13807080 |
Mar 5, 2013 |
9670068 |
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PCT/JP2011/064765 |
Jun 28, 2011 |
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15492330 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C01B 39/36 20130101;
C01B 39/02 20130101; C30B 5/00 20130101; C01B 39/365 20130101; C01B
39/26 20130101; C01B 39/38 20130101; C01B 39/026 20130101; C01B
39/46 20130101; C01B 39/42 20130101; B01J 29/7007 20130101; C30B
29/34 20130101 |
International
Class: |
C01B 39/46 20060101
C01B039/46; C30B 5/00 20060101 C30B005/00; C30B 29/34 20060101
C30B029/34; C01B 39/02 20060101 C01B039/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 1, 2010 |
JP |
2010-151489 |
Nov 24, 2010 |
JP |
2010-260929 |
Jun 24, 2011 |
JP |
2011-140636 |
Claims
1-14. (canceled)
15. A method of producing a zeolite comprising: reacting a gel and
zeolite seed crystals to produce a zeolite having the same kind of
skeletal structure as the zeolite seed crystals; wherein: the gel
comprises a silica source, an alumina source, an alkali source and
water; the gel is capable of synthesizing a zeolite without the use
of the zeolite seed crystals, wherein the zeolite synthesized
without the use of the zeolite seed crystals comprises one or more
building units of zeolite; the zeolite seed crystals comprise one
or more composite building units of zeolite; the zeolite seed
crystals and the zeolite synthesized without the use of zeolite
seed crystals comprise at least one equivalent composite building
unit of zeolite; wherein the reacting step occurs without the use
of an organic structure-directing agent; wherein beta zeolite is
used as the zeolite crystals; and wherein the gel has a composition
of: SiO.sub.2/Al.sub.2O.sub.3=10 to 14, Na.sub.2O/SiO.sub.2=0.05 to
0.25, and H.sub.2O/SiO.sub.2=5 to 50.
16. The method of producing a zeolite according to claim 15,
wherein the zeolite synthesized without the use of zeolite seed
crystals has a different kind of skeletal structure as the zeolite
seed crystals.
17. The method of producing a zeolite according to claim 16,
wherein the zeolite produced is beta zeolite, beta zeolite is used
as the zeolite seed crystals, and the gel has a composition which
forms a mordenite zeolite, when the zeolite is synthesized from the
gel without the use of the zeolite seed crystals.
18. The method of producing a zeolite according to claim 15,
wherein, as a post treatment, dealumination of the zeolite is
carried out by mixing the zeolite and an aqueous solution of citric
acid or a salt thereof, and heating a mixed aqueous solution under
an autogenous pressure.
19. A method of producing a zeolite comprising: reacting a gel and
zeolite seed crystals to produce a zeolite having the same kind of
skeletal structure as the zeolite seed crystals; wherein: the gel
comprises a silica source, an alumina source, an alkali source and
water; the gel is capable of synthesizing a zeolite without the use
of the zeolite seed crystals, wherein the zeolite synthesized
without the use of the zeolite seed crystals comprises one or more
building units of zeolite; the zeolite seed crystals comprise one
or more composite building units of zeolite; the zeolite seed
crystals and the zeolite synthesized without the use of zeolite
seed crystals comprise at least one equivalent composite building
unit of zeolite; wherein the reacting step occurs without the use
of an organic structure-directing agent; wherein beta zeolite is
used as the zeolite crystals; and wherein the gel has a composition
of: SiO.sub.2/Al.sub.2O.sub.3=6 to 40, Na.sub.2O/SiO.sub.2=0.05 to
0.25, Li.sub.2O/SiO.sub.2=0.005 to 0.25, and H.sub.2O/SiO.sub.2=5
to 50.
20. The method of producing a zeolite according to claim 19,
wherein the zeolite synthesized without the use of zeolite seed
crystals has a different kind of skeletal structure as the zeolite
seed crystals.
21. The method of producing a zeolite according to claim 20,
wherein the zeolite produced is beta zeolite, beta zeolite is used
as the zeolite seed crystals, and the gel has a composition which
forms a mordenite zeolite, when the zeolite is synthesized from the
gel without the use of the zeolite seed crystals. is used as the
gel.
22. The method of producing a zeolite according to claim 19,
wherein, as a post treatment, dealumination of the zeolite is
carried out by mixing the zeolite and an aqueous solution of citric
acid or a salt thereof, and heating a mixed aqueous solution under
an autogenous pressure.
Description
TECHNICAL FIELD
[0001] The present invention relates to a zeolite production method
in which zeolite seed crystals are used.
BACKGROUND ART
[0002] Synthetic zeolites are crystalline aluminosilicates, and
have uniform fine pores of a size of angstroms which are produced
due to the crystalline structure. Using this characteristic,
synthetic zeolites are industrially used as a molecular sieve
adsorbent which adsorbs only molecules having a specific size, an
adsorption separating agent which adsorbs molecules having a strong
affinity, or a basis of catalysts.
[0003] A variety of zeolite production methods have been proposed.
When, for example, beta zeolite, which is one synthetic zeolite, is
considered as an example, an ordinary zeolite production method is
a method in which tetraethylammonium ions are used as an organic
structure-directing agent (hereinafter referred to as an "organic
SDA"). Such a method is described in, for example, the following
PTL 1. However, while compounds including tetraethylammonium ions
are expensive, the compounds are almost decomposed after
crystallization of beta zeolite is completed, and therefore it is
impossible to collect and reuse the compounds. As a result, beta
zeolite produced using this method is expensive. Furthermore, since
tetraethylammonium ions are entrapped in the crystals, it is
necessary to fire and remove tetrasthylammonium ions when beta
zeolite is used as an adsorbent or a catalyst. At this time,
exhaust causes environmental contamination, and a large amount of
chemicals is also required for a detoxifying treatment of the
mother fluid of synthesis. As such, since a method of synthesizing
a zeolite in which the organic SDA is used is a production method
which is not only expensive but also causes a large environmental
load, there has been a demand for realization of a production
method in which the organic SDA is not used.
[0004] Under such circumstances, in recent years, a method of
synthesizing beta zeolite in which the organic SDA is not used has
been proposed (refer to NPL 1). In this method, a substance
obtained by firing beta zeolite, which. has been synthesized using
tetraethylammonium ions, so as to remove organic components is used
as seed crystals, the substance is added to a sodium
aluminosilicate reaction mixture which does not include any organic
substance, and a hydrothermal treatment is carried out, thereby
crystallizing beta zeolite. However, in this method, since beta
zeolite, which has been synthesized using tetraethylammonium ions,
is fired and used as seed crystals, tetraethylammonium ions become
necessary at all times as the organic SDA while the amount of the
organic SDA used decreases. In addition, according to this method,
there is only one kind of seed crystal, and there is only one
numerically limited example for the composition of the sodium
aluminosilicate reaction mixture. Therefore, while the composition
of the synthesized beta zeolite is not clearly described, the
composition is considered to have only the determined values.
[0005] Meanwhile, PTL 2 by the authors of NPL 1 discloses the
SiO.sub.2/Al.sub.2O.sub.3 ratios of seed crystals, and also
describes the composition of the sodium aluminosilicate reaction
mixture not as a point composition but as a narrow range away from
a point. However, since the contents disclosed by PTL 2 are
basically the same technique as the contents of NPL 1, and the
composition range of the reaction mixture is narrow, the
SiO.sub.2/Al.sub.2O.sub.3 ratio of beta zeolite is limited only to
a limited range. In order to meet a variety of needs, zeolites
having a wide SiO.sub.2/Al.sub.2O.sub.3 ratio range are desirable.
In addition, in order to reduce the environmental load as much as
possible, there is a demand for proposing a new zeolite production
method in which seed crystals which do not need to be fired are
used, and the organic SDA is not used.
CITATION LIST
Patent Literature
[0006] [PTL 1] U.S. Pat. No. 3,308,069
[0007] [PTL 2] Chinese Patent Laid-Open Publication No.
101249968A
Non-Patent Literature
[0008] [NPL 1] Chemistry of Materials, Vol. 20, No. 14, pp. 4533 to
4535 (2008)
SUMMARY OF INVENTION
Technical Problem
[0009] Therefore, an object of the invention is provide a zeolite
production method which can solve the variety of problems of the
related art.
Solution to Problem
[0010] As a result of thorough investigations in order to solve the
problems, the inventors found that, when an organic SDA-free
zeolite is produced by reacting zeolite seed crystals and a gel for
zeolite synthesis, it is possible to readily obtain a target
zeolite by introducing a concept of the composite building units of
the zeolite for selecting the kind of the zeolite seed crystals and
the composition of the gel.
[0011] The invention has been made based on the above finding, and
solves the problems by providing a zeolite production method in
which a gel including a silica source, an alumina source, an alkali
source and water, and zeolite seed crystals are reacted so as to
produce a zeolite having the same kind of skeletal structure as the
zeolite, and, a gel having a composition which, when the zeolite is
synthesized from the gel alone, makes the synthesized zeolite
include at least one of the composite building units of the target
zeolite as the composite building unit is used as the gel.
Advantageous Effects of Invention
[0012] According to the zeolite production method of the invention,
it is possible to readily and inexpensively produce a target
zeolite without using the organic SDA by appropriately selecting a
kind of zeolite seed crystals and a composition of the gel based on
the viewpoint of the composite building unit of the zeolite.
Particularly, the method of the invention is effective for
producing a zeolite which could not have been thus far produced
without using the organic SDA.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a view showing the composite building units of MFI
zeolite.
[0014] FIG. 2 is a view showing the composite building unit of
mordenite (MOR).
[0015] FIGS. 3A to 3E are views showing the relationship between
the composite building units of zeolite seed crystals and the
composite building units of zeolites produced from a gel alone.
[0016] FIG. 4 is a flow chart showing the sequence of the
production method of the invention.
[0017] FIG. 5 shows X-ray diffraction diagrams of seed crystals
used in Example 1-1 and the like.
[0018] FIGS. 6A and 6B are X-ray diffraction diagrams of zeolites
obtained in Examples 1-1 and 1-8.
[0019] FIG. 7 shows X-ray diffraction diagrams of seed crystals
used in Example 2-1 and the like.
[0020] FIGS. 8A to 8C are X-ray diffraction diagrams of zeolites
obtained in Examples 2-1, 2-5, and 2-7.
[0021] FIG. 9 is an X-ray diffraction diagram of seed crystals used
in Example 3-1 and the like.
[0022] FIGS. 10A to 10C are X-ray diffraction diagrams of zeolites
obtained in Examples 3-3, 3-5, and 3-6.
[0023] FIG. 11 is an X-ray diffraction diagram of seed crystals
used in Example 4-1 and the like.
[0024] FIGS. 12A to 12C are X-ray diffraction diagrams of zeolites
obtained in Examples 4-4, 4-7, and 4-14.
[0025] FIG. 13 is an X-ray diffraction diagram of seed crystals
used in Example 5-1 and the like.
[0026] FIGS. 14A and 14B are X-ray diffraction diagrams of zeolites
obtained in Examples 5-1 and 5-3.
[0027] FIGS. 15A to 15C are X-ray diffraction diagrams of zeolites
obtained in Examples 6-1, 6-3, and 6-6.
[0028] FIGS. 16A and 16B are .sup.27Al MAS NMR spectra of zeolites
obtained in Examples 6-1 and 6-2.
[0029] FIGS. 17A to 17C are X-ray diffraction diagrams of beta
zeolites obtained in Examples 7-1 to 7-3 after dealumination.
[0030] FIGS. 18A to 18C are X-ray diffraction diagrams of a variety
of zeolites obtained in Examples 7-4 to 7-6 after
dealumination.
DESCRIPTION OF EMBODIMENTS
[0031] In the zeolite production method of the invention, zeolite
seed crystals and a gel for zeolite synthesis are used. In
addition, a target zeolite is produced by mixing and reacting the
seed crystals and the gel.
[0032] The zeolite seed crystals being used have the same kind of
skeletal structure as the target zeolite. The "same kind of
skeletal structure" means that, for example, in a case in which the
seed crystals are beta zeolite, the target zeolite is also beta
zeolite. In this case, the value of Si/Al and the like of the beta
zeolite which is the seed crystals may be the same as or different
from the value of Si/Al and the like of the target beta zeolite.
The kind of the zeolite used as the seed crystals is not
particularly limited, and a zeolite having the same kind of
skeletal structure as the target zeolite can be appropriately used.
Examples of the target zeolite include MFI, MEL, MSE, MTW, BEA,
TUN, MFS, MOZ, EON, LTF, and the like when the target zeolite is
expressed using structure codes consisting of three capital letters
which are regulated by the International Zeolite Association, but
the target zeolite is not limited thereto.
[0033] As a method ofobtaining zeolite seed crystals, it is
possible to employ a variety of methods which have thus far become
known. For example, it is possible to employ (a) a zeolite
production method without using an organic SDA. Alternatively, it
is also possible to employ (b) a method of producing a zeolite
using the organic SDA. In this case, a zeolite from which the
organic SDA has been removed through firing is used. In addition,
(c) it is also possible to produce a zeolite according to the
invention using a zeolite produced using the organic SDA as seed
crystals and use the produced zeolite as seed crystals. In a case
in which the method (c) is employed, there is a large advantage
that a zeolite which could not have been thus far produced without
using the organic SDA can be produced without using the organic
SDA.
[0034] The size of the zeolite seed crystals is not particularly
limited. Generally, when seed crystals having an average grain
diameter of 100 nm to 2000 nm and particularly 200 nm to 1000 nm
are used, satisfactory results can be obtained. The average grain
diameter refers to the grain diameter of the crystals having
highest frequency in observation using a scanning electron
microscope. However, the average grain diameter of the seed
crystals does not limit the scope of the invention.
[0035] The SiO.sub.2/Al.sub.2O.sub.3 ratio of the zeolite seed
crystals is selected within an appropriate range depending on the
kind of zeolite being used. In a case in which, for example, MFI is
used as the zeolite seed crystals, the SiO.sub.2/Al.sub.2O.sub.3
ratio is preferably 5 to 200, and particularly preferably 10 to
100. In a case in which MEL is used, similarly, the
SiO.sub.2/Al.sub.2O.sub.3 ratio is preferably 5 to 200, and
particularly preferably 10 to 100. In a case in which MSE is used,
the SiO.sub.2/Al.sub.2O.sub.3 ratio is preferably 10 to 50, and
particularly preferably 15 to 40. In a case in which MTW is used,
the SiO.sub.2/Al.sub.2O.sub.3 ratio is preferably 5 to 200, and
particularly preferably 10 to 100. In a case in which BEA is used,
the SiO.sub.2/Al.sub.3 ratio is preferably 8 to 50, and
particularly preferably 10 to 30. Meanwhile, the
SiO.sub.2/Al.sub.2O.sub.3 ratio of the zeolite seed crystals may be
the same as or different from the SiO.sub.2/Al.sub.2O.sub.3 ratio
of the target zeolite depending on the producing conditions of the
target zeolite.
[0036] The amount of the zeolite seed crystals being used is
preferably less since the advantages of the invention further
develop, and is appropriately determined in consideration of the
production rate of the target zeolite and the like. Generally, the
amount of the zeolite seed crystals is preferably 0.1 weight % to
30 weight %, particularly preferably 1 weight % to 20 weight %, and
still more preferably 1 weight % to 10 weight % with respect to the
silica component included in the gel.
[0037] The gel being used in the invention together with the
zeolite seed crystals includes a silica source, an alumina source,
an alkali source, and water. In addition, the gel has a composition
from which a certain kind of zeolite is produced in a case in which
the gel is heated alone.
[0038] Examples of the silica source include silica and a
silicon-containing compound which can produce silicate ions in
water. Specific examples thereof include wet-processed silica,
dry-processed silica, colloidal silica, sodium silicate,
aluminosilicate gels, and the like. The silica sources can be used
as a single type or in combination of two or more kinds. Among the
above silica sources, use of silica (silicon dioxide) is preferable
since a zeolite can be obtained without producing unnecessary
byproducts.
[0039] As the alumina source, for example, a water-soluble
aluminum-containing compound can be used. Specific examples thereof
include sodium aluminate, aluminum nitrate, aluminum sulfate, and
the like. In addition, aluminum hydroxide is also one of the
preferable alumina sources. The alumina sources can be used as a
single type or in combination of two or more kinds. Among the above
alumina sources, use of sodium aluminate or aluminum hydroxide is
preferable since a zeolite can be obtained without producing
unnecessary byproducts.
[0040] As the alkali source, for example, sodium hydroxide,
potassium hydroxide, lithium hydroxide, or the like can be used.
Meanwhile, in a case in which sodium silicate is used as the silica
source or a case in which sodium aluminate is used as the alumina
source, sodium, which is an alkali metal component included in the
source, is also considered as NaOH which is an alkali component.
Therefore, Na.sub.2O, K.sub.2O, and Li.sub.2O are computed as the
sum of all alkali components in the reaction mixture.
[0041] The gel used in the invention contains the above respective
components, and has a composition which, when a zeolite is
synthesized from the gel alone, makes the synthesized zeolite
include at least one of the composite building units of the target
zeolite as the composite building unit. Before describing the
composition of the gel in detail, the composite building units of a
zeolite will be described.
[0042] For zeolites which have thus far become known, it is found
that the skeletal structures are constituted by combinations of
three-dimensional basic structures. The basic structures are termed
composite building units, and, thus far, 47 kinds are known. In the
International Zeolite Association, the respective composite
building units are expressed using codes consisting of three small
letters. For example, the skeletal structure of MFI zeolite is
constituted by a combination of four composite building units shown
in FIG. 1, that is, cas, mor, mel, and mfi. In addition, mordenite
(MOR) includes only one composite building unit termed mor in the
skeletal structure as shown in FIG. 2. The composite building units
which constitute the skeletal structures of the respective zeolites
are described in "Atlas of Zeolite Framework Types", 6th Revised
Edition 2007, Structure Commission of the International Zeolite
Association. The composite building units are geometrically
classified basic structures which configure the skeletal structures
of zeolites, and attention should be paid to the fact that a
compound having a structure of the composite building unit does not
exist.
[0043] In a case in which the target zeolite of the production
method of the invention is MFI zeolite, there are four composite
building units of cas, mor, mel, and mfi as described above, and
the gel being used at this time has a composition which makes the
zeolite synthesized from the gel include at least one composite
building unit of cas, mor, mel, and mfi. As such a gel, for
example, a gel having a composition from which mordenite (MOR),
which is a zeolite including mor as the composite building unit, is
produced may be used. The relationship is summarized and shown in
FIG. 3.
[0044] As shown in FIG. 3A, in a case in which MFI zeolite is used
as the seed crystals of the zeolite, when a gel having a
composition from which mordenite (MOR), which is a zeolite
including at least one of four composite building units of cas,
mor, mel, and mfi which constitute the skeletal structure of MFI
zeolite, is produced is used as the gel, MFI zeolite can be
obtained as a target zeolite.
[0045] In addition, as shown in FIG. 3E, in a case in which MEL
zeolite is used as the seed crystals of the zeolite, when a gel
having a composition from which mordenite (MOR), which is a zeolite
including at least one of three composite building units of mor,
mel, and mfi which constitute the skeletal structure of MEL
zeolite, is produced is used as the gel, MEL zeolite can be
obtained as a target zeolite.
[0046] As shown in FIG. 3C, in a case in which MSE zeolite is used
as the seed crystals of the zeolite, when a gel having a
composition from which mordenite (MOR), which is a zeolite
including at least one of three composite building units of bea,
mtw, and mor which constitute the skeletal structure of NSF
zeolite, is produced is used as the gel, MSE zeolite can be
obtained as a target zeolite. Currently, MSE zeolite cannot be
synthesized without using a special organic SDA such as
N,N,N,N'-tetraethylbicyclo[2.2.2]-oct-7-ene-2,3:5,6-dipyrrolidinium
diiodide.
[0047] As shown in FIG. 3D, in a case in which MTW zeolite is used
as the seed crystals of the zeolite, when a gel having a
composition from which MFI, which is a zeolite including at least
one of four composite building units of bik, jbw, mtw, and cas
which constitute the skeletal structure of MTW zeolite, is produced
or a gel having composition from which a plurality of compounds
including MFI are produced is used as the gel, MTW zeolite can be
obtained as a target zeolite.
[0048] Furthermore, as shown in FIG. 3E, in a case in which beta
zeolite (BEA) is used as the seed crystals of the zeolite, when a
gel having a composition from which mordenite (MOR), which is a
zeolite including at least one of three composite building units of
bea, mtw, and mor which constitute the skeletal structure of beta
zeolite, is produced is used as the gel, beta zeolite can be
obtained as a target zeolite. Meanwhile, beta zeolite shown in FIG.
3E has the same composite building unit as MSE zeolite shown in
FIG. 30, which has been described above, but has a different
skeletal structure.
[0049] As the gel used in the invention, it is possible to use a
gel having a composition which makes a zeolite synthesized from the
gel alone have a different kind of skeletal structure from the
zeolite of the seed crystals. The gels shown in FIGS. 3A to 3E,
which have been thus far described, belong to the above case.
[0050] The proportions of a variety of components included in the
gel used in the invention may be appropriately determined depending
on, when a zeolite is synthesized from the gel alone, composite
building units that the zeolite includes. Specifically, in the case
shown in FIG. 3A, the silica source, the alumina source, the alkali
source, and water may be mixed to be a gel being used so as to
obtain a composition preferably expressed by the molar ratios shown
in the following (a) or (b).
[0051] (a)
[0052] SiO.sub.2/Al.sub.2O.sub.3=40 to 200, particularly 44 to
200
[0053] Na.sub.2O/SiO.sub.2=0.24 to 0.4, particularly 0.25 to
0.35
[0054] H.sub.2O/SiO.sub.2=10 to 50, particularly 15 to 25
[0055] (b)
[0056] SiO.sub.2/Al.sub.2O.sub.3=10 to 40, particularly 12 to
40
[0057] Na.sub.2O/SiO.sub.2=0.05 to 0.25, particularly 0.1 to
0.25
[0058] H.sub.2O/SiO.sub.2=5 to 50, particularly 10 to 25
[0059] The method of producing a zeolite of the invention is
particularly advantageous in producing a zeolite which could not
have been produced without using the organic SDA in the past, and
there are cases in which the method of producing a zeolite of the
invention is still advantageous in producing a zeolite which can be
obtained without using the organic SDA. For example, while MFI
zeolite is a zeolite which can be synthesized without using the
organic SDA, in this case, the lowest SiO.sub.2/Al.sub.2O.sub.3
ratio that can be achieved is 24, and it is not possible to obtain
MFI zeolite having a lower SiO.sup.2/Al.sub.2O.sub.3 ratio than the
above. In contrast to the above, when MFI zeolite is synthesized
according to the production method of the invention, it is possible
to obtain MFI zeolite having a lower SiO.sub.2/Al.sub.2O.sub.3
ratio than 24 as shown in Examples 1-1 to 1-8 which will be
described below.
[0060] In the case shown in FIG. 3B, the silica source, the alumina
source, the alkali source, and water may be mixed in the gel being
used so as to obtain a composition preferably expressed by the
molar ratios shown in the following (a) or (b).
[0061] (a)
[0062] SiO.sub.2/Al.sub.2O.sub.3=40 to 200, particularly 44 to
200
[0063] Na.sub.2O/SiO.sub.2=0.24 to 0.4, particularly 0.25 to
0.35
[0064] H.sub.2O/SiO.sub.2=10 to 50, particularly 15 to 25
[0065] (b)
[0066] SiO.sub.2/Al.sub.2O.sub.3=10 to 40, particularly 12 to
40
[0067] Na.sub.2O/SiO.sub.2=0.05 to 0.25, particularly 0.1 to
0.25
[0068] H.sub.2O/SiO.sub.2=5 to 50, particularly 10 to 25
[0069] In the case shown in FIG. 3C, the silica source, the alumina
source, the alkali source, and water may be mixed in the gel being
used so as to obtain a composition preferably expressed by the
molar ratios shown in the following (a) or (b). That is, a gel
including only sodium ions may be used, and a gel including both
sodium and potassium, that is, a gel including an ion mixture may
be used. When a zeolite is synthesized using the gel including an
ion mixture, compared to a case in which a zeolite is synthesized
using the gel including only sodium ions, production of impurities
as by-products, particularly, production of small amounts of
zeolite by-products can be further prevented, which is
advantageous. A zeolite can be synthesized from a gel including
only potassium ions; however, when the fraction of potassium ions
increases, there is a tendency for the crystallization rate to
become slow, and the crystallinity of an obtained zeolite
decreases. As the potassium source, for example, potassium
hydroxide is preferably used. In addition, in order to adjust the
K.sub.2O/(Na.sub.2O+K.sub.2O) ratio, a potassium salt such as
potassium chloride, potassium sulfate, or potassium nitrate may be
used as a potassium ion source other than potassium hydroxide.
[0070] (a)
[0071] SiO.sub.2/Al.sub.2O.sub.3=40 to 200, particularly 44 to
200
[0072] (Na.sub.2O+K.sub.2)/SiO.sub.2=0.24 to 0.4, particularly 0.25
to 0.35
[0073] K.sub.2O/(Na.sub.2O+K.sub.2O)=0 to 0.7, particularly 0.01 to
0.65
[0074] H.sub.2O/SiO.sub.2=10 to 50, particularly 15 to 25
[0075] (b)
[0076] SiO.sub.2/Al.sub.2O.sub.3=10 to 40, particularly 12 to
40
[0077] (Na.sub.2O+K.sub.2O)/SiO.sub.2=0.05 to 0.25, particularly
0.1 to 0.25
[0078] K.sub.2O/(Na.sub.2O+K.sub.2O)=0 to 0.7, particularly 0.01 to
0.65
[0079] H.sub.2O/SiO.sub.2=5 to 50, particularly 10 to 25
[0080] In the case shown in FIG. 3D, the silica source, the alumina
source, the alkali source, and water may be mixed in the gel being
used so as to obtain a composition preferably expressed by the
molar ratios shown below.
[0081] SiO.sub.2/Al.sub.2O.sub.3=10 to 150, particularly 30 to
120
[0082] Na.sub.2O/SiO.sub.2=0.075 to 0.23, particularly 0.1 to
0.2
[0083] H.sub.2O/SiO.sub.2=5 to 50, particularly 8 to 20
[0084] In the case shown in FIG. 3E, the silica source, the alumina
source, the alkali source, and water may be mixed in the gel being
used so as to obtain a composition preferably expressed by the
molar ratios shown in the following (a) or (b).
[0085] (a)
[0086] SiO.sub.2/Al.sub.2O.sub.332 40 to 200, particularly 44 to
200
[0087] Na.sub.2O/SiO.sub.2=0.24 to 0.4, particularly 0.25 to
0.35
[0088] H.sub.2O/SiO.sub.2=10 to 50, particularly 15 to 25
[0089] (b)
[0090] SiO.sub.2/Al.sub.2O.sub.3=10 to 40, particularly 12 to
40
[0091] Na.sub.2O/SiO.sub.2=0.05 to 0.25, particularly 0.1 to
0.25
[0092] H.sub.2O/SiO.sub.2=5 to 50, particularly 10 to 25
[0093] In the case shown in FIG. 3E, the inventors further found
that, when lithium ions are added to the gel, (i) in a case in
which the seed crystals are not added, mordenite is crystallized,
and (ii) in a case in which beta zeolite is added as the seed
crystals, beta zeolite can be obtained. As the lithium ion source,
for example, a lithium halide such as lithium chloride or lithium
bromide or a lithium salt such as lithium acetate may be used, and
lithium hydroxide may be used. Lithium hydroxide is particularly
preferably used as the lithium ion source. In a case in which beta
zeolite is used as the seed crystals, the silica source, the
alumina source, the alkali source, the lithium ion source, and
water may be mixed in the gel being used so as to obtain a
composition expressed by the molar ratios shown in the following
(c).
[0094] (c)
[0095] SiO.sub.2/Al.sub.2O.sub.3=6 to 40, particularly 10 to 40
[0096] Na.sub.2O/SiO.sub.2=0.05 to 0.25, particularly 0.1 to
0.25
[0097] Li.sub.2O/SiO.sub.2=0.005 to 0.25, particularly 0.01 to
0.15
[0098] H.sub.2O/SiO.sub.2=5 to 50, particularly 10 to 25
[0099] When a gel having the composition shown in the above (c) is
used, compared to a case in which a gel having the composition
shown in the above (a) and (b) is used, beta zeolite having a low
SiO.sub.2/Al.sub.2O.sub.3 ratio can be obtained, which is
advantageous. In addition, as a result of investigations, the
inventors unexpectedly clarified that, when a .sup.27Al MAS NMR
spectrum is measured regarding beta zeolite obtained using a gel
having the composition shown in the above (c), six-coordinate
aluminum as well as tetracoordinate aluminum is present. Details of
the existing state of the six-coordinate aluminum are not evident.
As a result of measuring the BET surface area of beta zeolite
obtained using a gel having the composition shown in the above (c)
by a nitrogen adsorption measurement, it was found that the value
becomes equal to or larger than the value of the BET surface area
of beta zeolite obtained using a gel having the composition shown
in the above (a) or (b).
[0100] In any case shown in FIGS. 3A to 3E, when a gel is prepared,
the respective raw materials are preferably added sequentially
using a method in which a uniform gel is readily obtained. For
example, the alumina source is added to and dissolved in an aqueous
solution of sodium hydroxide at room temperature, subsequently, the
silica source is added, the mixture is stirred and mixed, whereby a
uniform gel can be obtained. When preparing the gel, the
temperature is not particularly limited and, generally, the gel is
prepared at room temperature (20.degree. C. to 25.degree. C.)
[0101] The zeolite seed crystals and the gel can be mixed, for
example, in a process of preparing the gel while the seed crystals
are added to the silica source. Alternatively, in the process of
preparing the gel, the seed crystals can be added to the gel before
and after addition of the silica source. In addition, a method of
adding the seed crystals after the gel is aged or temporarily
heated is effective from the viewpoint of shortening the
crystallization time (for example, refer to Example 5-10 described
below). In any cases, after the mixing, the seed crystals and the
gel are stirred and mixed so that the seed crystals are uniformly
dispersed.
[0102] FIG. 4 shows an example of the sequence of producing a
zeolite using a reaction between the zeolite seed crystals and the
gel. In the invention, it is possible to produce a zeolite in an
order of <1>, <2>, <3>, and <6> in FIG. 4.
When this order is employed, it is possible to produce a zeolite
having a wide range of SiO.sub.2/Al.sub.2O.sub.3 ratio. In
addition, it is also possible to produce a zeolite in an order
<1>, <2>, <4>, and <6> in FIG. 4. When this
order is employed, there are frequent cases in which the seed
crystals having a low SiO.sub.2/Al.sub.2O.sub.3 ratio can be
effectively used through static heating after aging.
[0103] Furthermore, in FIG. 4, it is also possible to produce a
zeolite in an order of <1>, <2>, <4>, <5>,
and <6>. In this order, operations of aging and stirring are
carried out. The operations of aging and stirring are a new method
necessary for mass production of a zeolite. The reason is that,
since a large-scale pressurized vessel is required for mass
production, a stirring operation is essential in order to maintain
the internal temperature of the pressurized vessel constant.
However, when stirring is carried out without the aging operation,
there is an accompanying production of impurities such that the
purity is liable to decrease.
[0104] In the production method of the invention, the following
three orders are also available.
[0105] <7>, <2>, <3>, <6>
[0106] <7>, <2>, <4>, <3>, <6>
[0107] <7>, <2 >, <4>, <5>, <6>
[0108] In the above three methods, a zeolite obtained using the
method of the invention is used as the seed crystals. That is, in
the three production methods, since the seed crystals can be
repeatedly used, essentially, the organic SDA is not used. In
summary, it is possible to term the above three methods a method of
producing a zeolite using green processes which cause ultimately
small environmental loads. Using the above production methods, a
"green zeolite" is produced for the first time.
[0109] In the above respective orders, the gel including the seed
crystals is fed into a sealed vessel, heated, and reacted so as to
crystallize a target zeolite. The gel does not include the organic
SDA.
[0110] In a case in which a seed crystals having a low
SiO.sub.2/Al.sub.2O.sub.3 ratio are used, heating the aged gel
without stirring facilitates a progress of crystallization (an
order of <1>, <2>, <4>, <3> and <6>).
Aging refers to an operation in which the gel is held at a
temperature lower than the reaction temperature for a certain
period of time. Generally, the gel is left static without being
stirred during aging. It is reported that aging brings about
effects of preventing production of impurities as by-products,
enabling heating during stirring without causing production of
impurities as by-products, increasing the reaction rate, and the
like. However, the action mechanism is not evident. The temperature
and time of aging are set so as to develop the above effects as
much as possible. In the invention, aging is carried out at
preferably 20.degree. C. to 80.degree. C., more preferably
20.degree. C. to 60.degree. C., for preferably a range of two hours
to one day.
[0111] In a case in which the gel is stirred in order to obtain a
uniform temperature throughout the gel during heating, it is
possible to prevent production of impurities as by-products by
carrying out heating and stirring after aging (in an order of
<1>, <2>, <4>, <5> and <6>). Stirring
is carried out in order to make the composition and temperature of
the gel uniform, and the gel is mixed by using stirring blades,
rotating a vessel, or the like. The stirring intensity or number of
revolutions may be adjusted depending on the uniformity of the
temperature or the circumstance of production of impurities as
by-products. Stirring may be carried out intermittently as well as
continuously. A combination of aging and stirring in the above
manner enables industrial mass production.
[0112] Three methods described below are methods of producing a
zeolite using the green process which is one of the characteristics
of the invention. According to the three methods, limitless
self-reproduction becomes possible using a zeolite obtained
according to the invention as the seed crystals, and a producing
process in which the organic SDA is not used becomes possible. That
is, the three methods are a method in an order of <7>,
<2>, <3> and <6>, a method in an order of
<7>, <2>, <4>, <3>and <6>, and a
method in an order of <7>, <2>, <4>, <5>
and <6>. The characteristics of the respective processes are
as described above. In a case in which a zeolite obtained according
to the invention is used as the seed crystals, regardless of the
low SiO.sub.2/Al.sub.2O.sub.3 ratio, there are frequent cases in
which a zeolite can be crystallized without the aging operation in
the case of static synthesis. In a case in which a zeolite
synthesized using the organic SDA is used as the seed crystals, the
fired zeolite is used; however, in a case in which a zeolite
obtained using the invention is used, the zeolite does not need to
be fired. This difference is assumed to result from the difference
in the effects of the seed crystals, but the details are not
evident. However, in a case in which the gel is stirred and heated,
the gel is preferably aged.
[0113] In any case of the static method and the stirring method,
the heating temperature is in a range of 100.degree. C. to
200.degree. C., and preferably 120.degree. C. to 180.degree. C.,
and the gel is heated under an autogenous pressure. At a
temperature of lower than 100.degree. C., since the crystallization
temperature becomes extremely slow, there are cases in which the
production efficiency of a zeolite becomes poor. On the other hand,
at a temperature of higher than 200.degree. C., since an autoclave
having a high pressure capacity becomes necessary, the economic
efficiency becomes poor, and the production rate of impurities
becomes fast. The heating time is not critical in the present
production method, and the gel may be heated until a zeolite having
a sufficiently high crystallinity is produced. Generally, a zeolite
having a satisfactory crystallinity can be obtained by
approximately five hours to 240 hours of heating.
[0114] In the method of producing a zeolite of the invention, in a
case in which the heating time is insufficient, an amorphous
component is produced. In addition, when heating further continues
after crystallization of a target zeolite is completed, production
and growth of a zeolite which is produced when the zeolite is
synthesized from the gel alone begins, and the proportion of the
target zeolite decrease. A time during which only the target
zeolite stably exists as a single phase varies depending on the
temperature; however, generally, is not long. In order to obtain
the target zeolite as a single phase, heating is made to be
completed before the production and growth of a zeolite produced
when the zeolite is synthesized from the gel alone begins so that
the sealed vessel is cooled, and the reaction is completed. An
accompaniment of an extremely small amount of impurity zeolite does
not significantly impair the characteristics of the target zeolite,
and the zeolite can be sufficiently used.
[0115] Crystals of the target zeolite can be obtained by heating.
After completion of the heating, produced crystal powder is
separated from the mother fluid through filtering, then, is washed
using water or warm water, and is dried. The crystals of the
obtained zeolite do not include organic substances in a dried
state, and therefore the crystals do not need to be fired, and can
be used as an adsorbent or the like when dehydrated. In addition,
when used as a solid acid catalyst, the crystals can be used as an
H.sup.+ type by, for example, exchanging Na.sup.+ ions in the
crystals with NH.sub.4.sup.+ ions, and firing the crystals.
[0116] Once the target zeolite is obtained in the above manner, a
post treatment may be carried out on the zeolite. Examples of the
post treatment include dealumination using citric acid or a salt
thereof. The Si/Al ratio in a zeolite can be further increased by
carrying out dealumination. A zeolite becomes more versatile when
the Si/Al ratio is increased.
[0117] The dealumination can be directly carried out on a Na-type,
K-type, Li-type, or mixed-type zeolite. In addition, the
dealumination can be carried out by mixing a zeolite which is a
treatment target and an aqueous solution of citric acid, or heating
a liquid mixture under the autogenous pressure. The concentration
of the citric acid or the salt thereof in the liquid mixture is
preferably set to 0.1 mol/L to 2 mol/L, and particularly preferably
set to 0.5 mol/L to 1 mol/L. The concentration of the zeolite in
the liquid mixture is preferably set to 10 g/L to 40 g/L, and
particularly preferably set to 15 g/L to 25 g/L. The temperature of
the liquid mixture is preferably set to 25.degree. C. to
135.degree. C., and particularly preferably set to 72.degree. C. to
90.degree. C. The heating time of the liquid mixture is preferably
set to six hours to seven days, and particularly preferably set to
15 hours to 30 hours. In a case in which the liquid mixture is
heated, in general, the liquid mixture is preferably heated while
being stirred using an autoclave.
[0118] In the liquid mixture, an ammonium salt such as ammonium
nitrate or ammonium chloride may coexist. Due to this, it is
possible to effectively prevent a zeolite from becoming amorphous,
which may be caused due to the dealumination, and to stabilize the
crystallinity of the zeolite. The concentration of the ammonium
nitrate is preferably set to 0.5 mol/L to 2 mol/L, and particularly
preferably set to 0.8 mol/L to 1.2 mol/L from the viewpoint of
making the above effect more significant.
[0119] After the dealumination, the zeolite is preferably washed
using water, fired in the atmosphere, and converted into an H-type.
Firing is preferably carried out at 400.degree. C. to 550.degree.
C., and particularly preferably at 400.degree. C. to 500.degree. C.
The firing time at this time is preferably three hours to six
hours, and particularly preferably three hours to five hours.
[0120] Through the dealumination, the Si/Al ratio in the zeolite
can be preferably increased to 5 to 50, and more preferably to 10
to 40. The dealumination smoothly progresses in a case in which
beta zeolite is used as the zeolite.
[0121] For the dealumination of a zeolite using citric acid or a
salt thereof, the above operation may be carried out once or may be
repeated a plurality of times. When the dealumination is carried
out a plurality of times, it is possible to preferably increase the
upper limit value of the SiO.sub.2/Al.sub.2O.sub.3 ratio of the
zeolite to 400.
EXAMPLES
[0122] Hereinafter, the invention will be described in more detail
using examples. However, the scope of the invention is not limited
to the examples. Unless otherwise described, "%" represents "weight
%". Meanwhile, analysis devices used in the following examples,
comparative examples, and reference examples are as follows.
[0123] Powder X-ray diffraction apparatus: powder X-ray diffraction
apparatus MO3XHF.sup.22 produced by MAC Science Co., Ltd., Cuka-ray
used, voltage of 40 kV, current of 30 mA, scanning step of
0.02.degree., scanning speed 2.degree./min. Composition analyzing
apparatus: ICP-AES LIBERTY Series II.BET surface area measuring
apparatus produced by Varian Inc.: AUTOSORB-1 produced by Quanta
chrome Instruments
Example 1-1
[0124] Synthesis of MFI Zeolite
[0125] (1) Preparation of Seed Crystals
[0126] The following seed crystals 1 to 4 were prepared. The X-ray
diffraction diagrams of the seed crystals are shown in FIG. 5.
[0127] Seed crystals 1 (SiO.sub.2/Al.sub.2O.sub.3=24.0): HSZ-820NAA
produced by Tosoh Corporation was used. This zeolite is MFI zeolite
produced without using an organic structure-directing agent. This
zeolite was used as seed crystals without being fired. BET specific
surface area: 316 m.sup.2/g.
[0128] Seed crystals 2 (SiO.sub.2/Al.sub.2O.sub.3=40.0): This
zeolite is MFI zeolite obtained by using sodium aluminate as the
alumina source, powder-form silica (Cab-O-Sil, M-5) as the silica
source, and sodium hydroxide as the alkali source, and carrying out
stirring and heating using a well-known method of the related art
in which an organic structure-directing agent is not used. The
conditions of the stirring and heating are 170.degree. C. and 96
hours. The SiO.sub.2/Al.sub.2O.sub.3 ratio of the zeolite was 40.0.
This zeolite was used as seed crystals without being fired. BET
specific surface area: 295 m.sup.2/g.
[0129] Seed crystals 3 and. 4: These zeolites are MFI zeolites
obtained by carrying out stirring and heating using a well-known
method of the related art in which tetrapropylammonium hydroxide is
used as an organic structure-directing agent, sodium aluminate is
used as the alumina source, and powder-form silica (Cab-O-Sil, M-5)
is used as the silica source. The conditions of the stirring and
heating are 150.degree. C. and 72 hours. The
SiO.sub.2/Al.sub.2O.sub.3 ratios of the zeolites were 52.0 (Seed
crystals 3) and 60.8 (Seed crystals 4). The zeolites were fired at
550.degree. C. for 10 hours in the air, and used as seed
crystals.
[0130] (2) Synthesis of Zeolites
[0131] An aqueous solution was obtained by dissolving 0.115 g of
sodium aluminate and 2.582 g of 36% sodium hydroxide in 12.88 g of
pure water. A mixture of 2.427 g of powder-form silica (Cab-O-Sil,
M-5) and 0.243 g of Seed crystals 1 was added to the aqueous
solution little by little, stirred, and mixed so as to obtain a gel
having a composition described in Table 1. When a zeolite is
synthesized from the gel alone, the gel has a composition from
which mordenite (MOR) is produced. A mixture of the gel and a
mixture of the seed crystals was fed into a 60 cc stainless steel
sealed vessel, and statically heated at 160.degree. C. for 20 hours
under the autogenous pressure without being aged and stirred. After
cooling of the sealed vessel, a product was filtered and washed
using warm water, thereby obtaining white powder. The X-ray
diffraction diagram is shown in FIG. 6A. As is evident from the
drawing, the product was MFI zeolite not including impurities. As a
result of a composition analysis, the SiO.sub.2/Al.sub.2O.sub.3
ratio and the BET specific surface area were as shown in Table
1.
Examples 1-2 -10 and Comparative Examples 1-1 to 1-4
[0132] Zeolites were synthesized in the same manner as in Example
1-1 except that gels and seed crystals having compositions shown in
Tables 1 and 2 were used, and the reaction conditions described in
the tables were used. The results are shown in Tables 1 and 2. In
addition, the X-ray diffraction diagram of the product obtained in
Example 1-8 is shown in FIG. 6B. Meanwhile, when the zeolite is
synthesized from the gel alone, all of the gels used in the
examples and comparative examples had compositions from which
mordenite (MOR) was produced.
TABLE-US-00001 TABLE 1 Reaction Products Gel composition Seed
crystals conditions BET specific SiO.sub.2/ Na.sub.2O/ H.sub.2O/
SiO.sub.2/ Addition Temperature Time SiO.sub.2/ surface area
Example Al.sub.2O.sub.3 SiO.sub.2 SiO.sub.2 Al.sub.2O.sub.3
amount*.sup.1 (wt %) (.degree. C.) (h) Zeolite Al.sub.2O.sub.3
(m.sup.2/g) 1-1 100 0.300 20 24.0 10 160 20 MFI 18.6 307 1-2 100
0.300 20 40.0 20 150 16 MFI 23.8 254 1-3 100 0.300 20 24.0 20 150
24 MFI 21.0 321 1-4 100 0.300 20 52.0 20 150 30 MFI 23.0 -- 1-5 100
0.300 20 60.8 20 150 30 MFI 22.2 -- 1-6 70 0.300 25 24.0 30 160 21
MFI 19.2 317 1-7 80 0.275 20 24.0 20 160 22 MFI 19.4 -- 1-8 70
0.325 25 24.0 30 165 11 MFI 17.0 397 1-9 40 0.300 25 24.0 20 160 24
MFI -- -- (slightly low crystallinity) 1-10 30 0.193 20 60.8 10 150
67 MFI -- -- (slightly low crystallinity) *.sup.1Amount of silica
in the gel
TABLE-US-00002 TABLE 2 Seed crystals Reaction conditions
Comparative Gel composition Addition Temperature Time Example
SiO.sub.2/Al.sub.2O.sub.3 Na.sub.2O/SiO.sub.2 H.sub.2O/SiO.sub.2
SiO.sub.2/Al.sub.2O.sub.3 amount*.sup.1 (wt %) (.degree. C.) (h)
Products 1-1 100 0.300 20 -- 0 160 50 Amorphous + small amount of
MOR 1-2 100 0.300 20 -- 0 140 288 MOR 1-3 40 0.300 25 -- 0 140 144
Amorphous + MOR 1-4 30 0.193 20 -- 0 150 240 MOR *.sup.1Amount of
silica in the gel
Example 2-1
[0133] Synthesis of MEL Zeolite
[0134] (1) Preparation of Seed Crystals
[0135] The following seed crystals 1 and 2 were prepared. The X-ray
diffraction diagrams of the seed crystals are shown in FIG. 7.
[0136] Seed crystals 1 and 2: These zeolites are MEL zeolite
obtained by carrying out stirring and heating using a well-known
method of the related art in which tetrabutylammonium hydroxide is
used as an organic structure-directing agent, sodium aluminate is
used as the alumina source, and powder-form silica (Cab-O-Sil, M-5)
is used as the silica source. The conditions of the stirring and
heating are 180.degree. C. and 96 hours. The
SiO.sub.2/Al.sub.2O.sub.3 ratios of the zeolites were 66.0 (Seed
crystals 1) and 34.0 (Seed crystals 2). The zeolites were fired at
550.degree. C. for 10 hours in the air, and used as seed crystals.
The BET specific surface areas were 426 m.sup.2/g for Seed crystals
1 and 416 m.sup.2/g for Seed crystals 2.
[0137] (2) Synthesis of Zeolites
[0138] An aqueous solution was obtained by dissolving 0.113 g of
sodium aluminate and 2.582 g of 36% sodium hydroxide in 12.88 g of
pure water. A mixture of 2.427 g of powder-form silica (Cab-O-Sil,
M-5) and 0.243 g of Seed crystals 1 was added to the aqueous
solution little by little, stirred, and mixed so as to obtain a gel
having a composition described in Table 3. When a zeolite is
synthesized from the gel alone, the gel has a composition from
which mordenite (MOR) is produced. A mixture of the gel and a
mixture of the seed crystals was fed into a 60 cc stainless steel
sealed vessel, and statically heated at 140.degree. C. for 15 hours
under the autogenous pressure without being aged and stirred. After
cooling of the sealed vessel, a product was filtered and washed
using warm water, thereby obtaining white powder. The X-ray
diffraction diagram is shown in FIG. 8A. As is clear from the
drawing, the product was MEL zeolite not including impurities. As a
result of a composition analysis, the SiO.sub.2/Al.sub.2O.sub.3
ratio and the BET specific surface area were as shown in Table
3.
Examples 2-2 to 2-7 and Comparative Examples 2-1 to 2-4
[0139] Zeolites were synthesized in the same manner as in Example
2-1 except that gels and seed crystals having compositions shown in
Tables 3 and 4 were used, and the reaction conditions described in
the tables were used. The results are shown in Tables 3 and 4. In
addition, the X-ray diffraction diagrams of the products obtained
in Examples 2-5 and 2-7 are shown in FIGS. 5B and 8C. Meanwhile,
when the zeolite is synthesized from the gel alone, all of the gels
used in the examples and comparative examples had compositions from
which mordenite (MOR) was produced.
TABLE-US-00003 TABLE 3 Products Gel composition Seed crystals
Reaction conditions BET specific SiO.sub.2/ Na.sub.2O/ H.sub.2O/
SiO.sub.2/ Addition Temperature Time SiO.sub.2/ surface area
Example Al.sub.2O.sub.3 SiO.sub.2 SiO.sub.2 Al.sub.2O.sub.3
amount*.sup.1 (wt %) (.degree. C.) (h) Zeolite Al.sub.2O.sub.3
(m.sup.2/g) 2-1 100 0.300 20 66.0 10 140 15 MEL 17.6 326 2-2 100
0.300 20 34.0 20 150 20 MEL 18.8 315 2-3 70 0.300 20 34.0 30 160 20
MEL 19.0 319 2-4 70 0.325 25 34.0 30 160 13 MEL 18.4 -- 2-5 60
0.325 25 34.0 30 160 15 MEL 17.4 438 2-6 50 0.325 25 34.0 30 160 17
MEL 16.2 -- 2-7 30 0.193 20 66.0 10 150 67 MEL 15.4 317
*.sup.1Amount of silica in the gel
TABLE-US-00004 TABLE 4 Seed crystals Reaction conditions
Comparative Gel composition Addition Temperature Time Example
SiO.sub.2/Al.sub.2O.sub.3 Na.sub.2O/SiO.sub.2 H.sub.2O/SiO.sub.2
SiO.sub.2/Al.sub.2O.sub.3 amount*.sup.1 (wt %) (.degree. C.) (h)
Products 2-1 100 0.300 20 -- 0 160 50 Amorphous + small amount of
MOR 2-2 100 0.300 20 -- 0 140 288 MOR 2-3 40 0.300 25 -- 0 140 144
Amorphous + MOR 2-4 30 0.193 20 -- 0 150 240 MOR *.sup.1Amount of
silica in the gel
Example 3-1
[0140] Synthesis of MSE Zeolite
[0141] (1) Preparation of Seed Crystals
[0142] The following seed crystals were prepared. The X-ray
diffraction diagram of the seed crystals is shown in FIG. 9.
[0143]
N,N,N',N'-tetraethylbicyclo[2.2.2]-oct-7-ene-2,3:5,6-dipyrrolidiniu-
m diiodide was used as an organic structure-directing agent.
According to the description in the specification of U.S. Pat. No.
6,049,018, a reaction mixture was prepared using aluminum hydroxide
as the alumina source, colloidal silica as the silica source, and
potassium hydroxide as the alkali source, and heated at 160.degree.
C. for 16 days using the static method. MSE zeolite obtained by
heating and firing the product at 540.degree. C. for 8 hours in the
air was used as the seed crystals. The SiO.sub.2/Al.sub.2O.sub.3
ratio was 24.0.
[0144] (2) Synthesis of Zeolites
[0145] An aqueous solution was obtained by dissolving 0.096 g of
sodium aluminate and 2.147 g of 36% sodium hydroxide in 10.74 g of
pure water. A mixture of 2.022 g of powder-form silica (Cab-O-Sil,
M-5) and 0.202 g of the seed crystals was added to the aqueous
solution little by little, stirred, and mixed so as to obtain a gel
having a composition described in Table 5. When a zeolite is
synthesized from the gel alone, the gel has a composition from
which mordenite (MOR) is produced. A mixture of the gel and a
mixture of the seed crystals was fed into a 60 cc stainless steel
sealed vessel, and statically heated at 160.degree. C. for 29 hours
under the autogenous pressure without being aged and stirred. After
cooling of the sealed vessel, a product was filtered and washed
using warm water, thereby obtaining white powder.
Examples 3-2to 3-3 and Comparative Examples 3-1 to 3 -3
[0146] Zeolites were synthesized in the same manner as in Example
3-1 except that gels and seed crystals having compositions shown in
Tables 5 and 6 were used, and the reaction conditions described in
the tables were used. The results are shown in Tables 5 and 6.
Meanwhile, when a zeolite is synthesized from the gel alone, all of
the gels used in the examples and comparative examples have a
composition from which mordenite (MOR) is produced. The X-ray
diffraction diagram of the product obtained in Example 3-3 is shown
in FIG. 10A. As is evident from the drawing, the product was MSE
zeolite including a small amount of beta zeolite (BEA).
Examples 3-4
[0147] An aqueous solution was obtained by dissolving 0.096 g of
sodium aluminate, 2.08 g of 36% sodium hydroxide, and 0.67 g of an
aqueous solution of 1 mol/L potassium hydroxide in 10.13 g of pure
water. A mixture of 2.026 g of powder-form silica (Cab-O-Sil, M-5)
and 0.203 g of the seed crystals used in Example 3-1 was added to
the aqueous solution little by little, stirred, and mixed so as to
obtain a gel having a composition described in Table 5. When a
zeolite is synthesized from the gel alone, the gel has a
composition from which mordenite (MOR) is produced. A mixture of
the gel and a mixture of the seed crystals was fed into a 60 cc
stainless steel sealed vessel, and statically heated at 140.degree.
C. for 57 hours under the autogenous pressure without being aged
and stirred. After cooling of the sealed vessel, a product was
filtered and washed using warm water, thereby obtaining white
powder. As a result of an X-ray diffraction measurement, the
product was MSE zeolite not including impurities.
Examples 3-5 to 3-8 and Comparative Examples 3-4 to 3-8
[0148] In the examples and comparative examples for which
K.sub.2O/(Na.sub.2O+K.sub.2O) >0, zeolites were synthesized in
the same manner as in Example 3-4 except that appropriate
concentrations of an aqueous solution of sodium hydroxide and an
aqueous solution of potassium hydroxide were used as a Na ion
source and a K ion source at a variety of mixing proportions, gels
and seed crystals having compositions shown in Tables 5 and 6 were
used, and the reaction conditions described in the tables were
used. The results are shown in Tables 5 and 6. In addition, the
X-ray diffraction diagrams of the products obtained in Examples 3-5
and 3-6 are shown in FIGS. 10B and 10C. Meanwhile, when a zeolite
is synthesized from the gel alone, the gel used in the examples and
comparative examples has a composition from which mordenite (MOR)
is produced.
TABLE-US-00005 TABLE 5 Reaction Gel composition Seed crystals
conditions Products Ex- (Na.sub.2O + K.sub.2O/ Addition Temper-
Na.sub.2O/ K.sub.2O/ BET specific am- SiO.sub.2/ K.sub.2O)/
(Na.sub.2O + H.sub.2O/ SiO.sub.2/ amount*.sup.1 ature Time
SiO.sub.2/ (Na.sub.2O + (Na.sub.2O + surface area ple
Al.sub.2O.sub.3 SiO.sub.2 K.sub.2O) SiO.sub.2 Al.sub.2O.sub.3 (wt
%) (.degree. C.) (h) Zeolite Al.sub.2O.sub.3 K.sub.2O) K.sub.2O)
(m.sup.2/g) 3-1 100 0.300 0 20 24.0 10 160 29 MSE + small -- -- --
-- amount of MOR 3-2 100 0.300 0 20 24.0 10 150 42 MSE + small --
-- -- -- amount of MOR 3-3 100 0.300 0 20 24.0 10 140 50 MSE +
small 13.8 1.0 0 426 amount of BEA 3-4 100 0.300 0.0333 20 24.0 10
140 57 MSE 14.2 -- -- -- 3-5 100 0.300 0.0667 20 24.0 10 140 64 MSE
13.2 0.65 0.40 408 3-6 100 0.300 0.1333 20 24.0 10 140 72 MSE 13.0
0.48 0.50 365 3-7 100 0.300 0.3333 20 24.0 10 140 96 MSE -- -- --
-- 3-8 100 0.300 0.5000 20 24.0 10 140 120 MSE -- -- -- --
*.sup.1Amount of silica in the gel
TABLE-US-00006 TABLE 6 Seed crystals Reaction Gel composition
Addition conditions Comparative SiO.sub.2/ (Na.sub.2O + K.sub.2O)/
K.sub.2O/(Na.sub.2O + H.sub.2O/ amount*.sup.1 Temperature Time
Example Al.sub.2O.sub.3 SiO.sub.2 K.sub.2O) SiO.sub.2
SiO.sub.2/Al.sub.2O.sub.3 (wt %) (.degree. C.) (h) Products 3-1 100
0.300 0 20 -- 0 160 50 Amorphous + small amount of MOR 3-2 100
0.300 0 20 -- 0 140 288 MOR 3-3 40 0.300 0 25 -- 0 140 144
Amorphous + MOR 3-4 100 0.300 0.067 20 -- 0 140 360 MOR 3-5 100
0.300 0.133 20 -- 0 140 360 MOR 3-6 100 0.300 0.500 20 -- 0 140 720
MOR + unidentified substance 3-7 100 0.300 0.750 20 -- 0 140 720
Unidentified substance 3-8 100 0.300 0.957 20 -- 0 140 720
Unidentified substance *.sup.1Amount of silica in the gel
Example 4-1
[0149] (1) Preparation of a Seed Crystal
[0150] The following seed crystals were prepared. The X-ray
diffraction diagram of the seed crystals is shown in FIG. 11.
[0151] The seed crystals are MTW zeolite obtained by carrying out
static heating using a well-known method of the related art in
which tetraethylammonium hydroxide was used as an organic
structure-directing agent, sodium aluminate was used as the alumina
source, and colloidal silica (LUDOX, HS-40) was used as the silica
source. The conditions for the static heating are 160.degree. C.
and 120 hours. The SiO.sub.2/Al.sub.2O.sub.3 ratio of the zeolite
was 94.6. The zeolite was fired at 550.degree. C. for 10 hours in
the air, and used as seed crystals.
[0152] (2) Synthesis of Zeolites
[0153] An aqueous solution was obtained by dissolving 0.231 g of
sodium aluminate and 2.027 g of 36% sodium hydroxide in 10.85 g of
pure water. A mixture of 4.893 g of powder-form silica (Cab-O-Sil,
M-5) and 0.489 g of the seed crystals was added to the aqueous
solution little by little, stirred, and mixed so as to obtain a gel
having a composition described in Table 7. When a zeolite is
synthesized from the gel alone, the gel has a composition from
which a plurality of compounds including MFI zeolite are produced.
A mixture of the gel and a mixture of the seed crystals was fed
into a 60 cc stainless steel sealed vessel, and statically heated
at 165.degree. C. for 4 days under the autogenous pressure without
being aged and stirred. After cooling of the sealed vessel, a
product was filtered and washed using warm water, thereby obtaining
white powder. As a result of an X-ray diffraction of the product,
it was confirmed that the product was MTW zeolite not including
impurities.
Examples 4-2 to 4-11 and Comparative Examples 4-1 to 4-5
[0154] Zeolites were synthesized in the same manner as in Example
4-1 except that gels and seed crystals having compositions shown in
Tables 7 and 8 were used, and the reaction conditions described in
the tables were used. The results are shown in Tables 7 and 8. In
addition, the X-ray diffraction diagrams of the products obtained
in Examples 4-4 and 4-7 are shown in FIGS. 12A and 12B. Meanwhile,
when a zeolite is synthesized from the gel alone, all of the gels
used in the examples and comparative examples have a composition
from which a plurality of compounds including MFI zeolite are
produced.
[0155] In addition, when a zeolite is synthesized from the gel, the
gel used in Comparative example 4-5 has a composition from which
mordenite is produced.
Examples 4-12 to 4-14
[0156] MTW zeolite obtained in Example 4-7 was used as the seed
crystals. A gel having a composition shown in Table 7 was used. In
addition, zeolites were synthesized in the same manner as in
Example 4-1 except that the reaction conditions described in the
same table were used. The results are shown in Table 7 in addition,
the X-ray diffraction diagram of a product obtained in Example 4-14
is shown in FIG. 12C. Zeolites obtained in the examples are "green
zeolites" obtained without essentially using an organic SDA.
Meanwhile, when a zeolite is synthesized from the gel alone, all of
the gels used in the examples have a composition from which a
plurality of compounds including MFI zeolite are produced.
TABLE-US-00007 TABLE 7 Gel composition Seed crystals Reaction
conditions SiO.sub.2/ Na.sub.2O/ H.sub.2O/ SiO.sub.2/ Addition
Temperature Time Products Example Al.sub.2O.sub.3 SiO.sub.2
SiO.sub.2 Al.sub.2O.sub.3 amount*.sup.1 (wt %) (.degree. C.) (h)
Zeolite SiO.sub.2/Al.sub.2O.sub.3 4-1 120 0.125 8.3 94.6 10 165 96
MTW + small amount 66.0 of lamellar silicate 4-2 120 0.175 11.7
94.6 10 165 96 MTW + small amount 53.4 of lamellar silicate 4-3 100
0.100 10 94.6 10 165 72 MTW + small amount 46.8 of lamellar
silicate 4-4 100 0.150 10 94.6 10 165 65 MTW + small amount 51.4 of
lamellar silicate 4-5 100 0.200 13.2 94.6 10 165 65 MTW 36.6 4-6 80
0.125 8.25 94.6 10 165 72 MTW + small amount -- of lamellar
silicate 4-7 80 0.175 11.5 94.6 10 165 36 MTW 32.4 4-8 60 0.150 10
94.6 10 165 55 MTW 29.0 4-9 60 0.200 13.3 94.6 10 165 36 MTW --
4-10 40 0.150 10 94.6 10 165 72 MTW + MOR -- 4-11 20 0.100 6.5 94.6
10 165 120 MTW + amorphous -- 4-12 80 0.175 11.5 32.4*.sup.2 10 165
24 MTW + MFI 28.8 4-13 100 0.200 13.2 32.4*.sup.2 10 165 18 MTW
20.8 4-14 120 0.175 11.7 32.4*.sup.2 10 165 16 MTW 29.2
*.sup.1Amount of silica in the gel *.sup.2As the seed crystals, the
product of Example 4-7 was used.
TABLE-US-00008 TABLE 8 Gel composition Seed crystals Reaction
conditions Comparative SiO.sub.2/ Na.sub.2O/ H.sub.2O/ SiO.sub.2/
Addition Temperature Time Example Al.sub.2O.sub.3 SiO.sub.2
SiO.sub.2 Al.sub.2O.sub.3 amount*.sup.1 (wt %) (.degree. C.) (h)
Products 4-1 100 0.150 10 -- 0 165 144 MFI + lamellar silicate +
MOR 4-2 80 0.175 11.5 -- 0 165 336 MFI + MOR 4-3 60 0.200 13.3 -- 0
165 168 MFI + MOR 4-4 60 0.150 10 -- 0 165 168 MFI + MOR 4-5 20
0.150 10 94.6 10 165 72 MOR *.sup.1Amount of silica in the gel
Example 5-1
[0157] Synthesis of BEA Zeolites
[0158] (1) Preparation of Seed Crystals
[0159] The following seed crystals were prepared. The X-ray
diffraction diagram of the seed crystals is shown in FIG. 13.
[0160] The seed crystals are BEA zeolite obtained by carrying out
static heating using a well-known method of the related art in
which tetraethylammonium hydroxide was used as an organic
structure-directing agent, sodium aluminate was used as the alumina
source, and powder-form silica (Mizukasil, P707) was used as the
silica source. The conditions for the static heating are
165.degree. C. and 96 hours. The SiO.sub.7/Al.sub.2O.sub.3 ratio of
the zeolite was 24.0. The zeolite was fired at 550.degree. C. for
10 hours in the air, and used as seed crystals.
[0161] (2) Synthesis of Zeolites
[0162] An aqueous solution was obtained by dissolving 0.127 g of
sodium aluminate and 2.562 g of 36% sodium hydroxide in 12.88 g of
pure water. A mixture of 2.426 g of powder-form silica (Cab-O-Sil,
M-5) and 0.243 g of the seed crystals was added to the aqueous
solution little by little, stirred, and mixed so as to obtain a gel
having a composition described in Table 9. When a zeolite is
synthesized from the gel alone, the gel has a composition from
which mordenite (MOR) is produced. A mixture of the gel and a
mixture of the seed crystals was fed into a 60 cc stainless steel
sealed vessel, and statically heated at 140.degree. C. for 32 hours
under the autogenous pressure without being aged and stirred. After
cooling of the sealed vessel, a product was filtered and washed
using warm water, thereby obtaining white powder. The X-ray
diffraction diagram of the product is shown in FIG. 14A. As is
evident from the drawing, the product was BEA zeolite not including
impurities.
Examples 5-2 to 5-9 and Comparative Examples 5-1 to 5-3
[0163] Zeolites were synthesized in the same manner as in Example
5-1 except that gels and seed crystals having compositions shown in
Tables 9 and 10 were used, and the reaction conditions described in
the tables were used. The results are shown in Tables 9 and 10. In
addition, the X-ray diffraction diagram of the product obtained in
Example 5-3 is shown in FIG. 14B. Meanwhile, when a zeolite is
synthesized from the gel alone, all of the gels used in the
examples and comparative examples have a composition from which
mordenite (MOR) is produced.
Example 5-10
[0164] A gel having the same composition as for the gel used in
Example 5-9 was heated at 140.degree. C. for 5 hours without adding
the seed crystals. After completion of heating, the sealed vessel
was cooled. After the temperature of the gel was lowered to room
temperature, the lid of the sealed vessel was opened, the same seed
crystals as in Example 5-9 were added at the same amount as in the
same example, and the gel was uniformly stirred. After that, the
lid was sealed, and the gel was again heated at 140.degree. C. for
25 hours, thereby synthesizing a zeolite. Products were as shown in
Table 9. As is evident from comparison between the present example
and Example 5-9, the crystallization time was significantly
shortened compared to Example 5-9.
TABLE-US-00009 TABLE 9 Gel Seed Aging Reaction Products composition
crystals conditions conditions BET specific SiO.sub.2/ Na.sub.2O/
H.sub.2O/ SiO.sub.2/ Addition Temperature Time Temperature Time
SiO.sub.2/ surface area Example Al.sub.2O.sub.3 SiO.sub.2 SiO.sub.2
Al.sub.2O.sub.3 amount*.sup.1 (wt %) (.degree. C.) (h) (.degree.
C.) (h) Zeolite Al.sub.2O.sub.3 (m.sup.2/g) 5-1 90 0.300 20 24.0 10
-- -- 140 32 BEA -- -- 5-2 60 0.325 25 24.0 10 -- -- 140 30 BEA --
-- 5-3 34 0.225 20 24.0 10 -- -- 150 48 BEA -- -- 5-4 30 0.193 20
24.0 10 80 24 150 120 BEA 13.0 473 5-5 20 0.225 25 24.0 10 -- --
150 67 BEA -- -- 5-6 18 0.200 15 24.0 10 -- -- 150 60 BEA 9.4 534
5-7 16 0.200 15 24.0 10 -- -- 150 60 BEA 8.8 374 5-8 14 0.195 15
24.0 10 -- -- 150 65 BEA + small -- -- amount of GIS 5-9 40 0.325
25 24.0 10 -- -- 140 38 BEA 10.4 -- 5-10 40 0.325 25 24.0 10 -- --
140 25 BEA 10.4 -- *.sup.1Amount of silica in the gel
TABLE-US-00010 TABLE 10 Seed crystals Reaction conditions
Comparative Gel composition SiO.sub.2/ Addition amount*.sup.1
Temperature Products Example SiO.sub.2/Al.sub.2O.sub.3
Na.sub.2O/SiO.sub.2 H.sub.2O/SiO.sub.2 Al.sub.2O.sub.3 (wt %)
(.degree. C.) Time (h) Zeolite 5-1 90 0.300 20 -- 0 140 168 MOR 5-2
60 0.325 25 -- 0 140 168 MOR 5-3 30 0.193 20 -- 0 150 240 MOR
*.sup.1Amount of silica in the gel
Example 6-1
[0165] Synthesis of BEA Zeolites
[0166] (1) Preparation of Seed Crystals
[0167] The same seed crystals as used in Example 5-1 were used.
[0168] (2) Synthesis of Zeolites
[0169] An aqueous solution was obtained by dissolving 0.477 g of
sodium aluminate, 0.822 g of 36% sodium hydroxide, and 0.141 g of a
lithium hydroxide additive in 14.54 g of pure water. A mixture of
2.017 g of powder-form silica (Cab-O-Sil, M-5) and 0.202 g of the
seed crystals was added to the aqueous solution little by little,
stirred, and mixed so as to obtain a gel having a composition
described in Table 11. When a zeolite is synthesized from the gel
alone, the gel has a composition from which mordenite (MOR) is
produced. A mixture of the gel and a mixture of the seed crystals
were fed into a 60 cc stainless steel sealed vessel, statically
aged at 80.degree. C. for 16 hours, and then statically heated at
150.degree. C. for 72 hours under the autogenous pressure without
being stirred. After cooling of the sealed vessel, a product was
filtered and washed using warm water, thereby obtaining white
powder. The X-ray diffraction diagram of the product is shown in
FIG. 15A. As is evident from the drawing, the product was BEA
zeolite not including impurities,
Examples 6-2 to 6-7 and Comparative Example 6-1 to 6-4
[0170] Zeolites were synthesized in the same manner as in Example
6-1 except that gels and seed crystals having compositions shown in
Tables 11 and 12 were used, and the reaction conditions described
in the tables were used. The results are shown in Tables 11 and 12.
In addition, the X-ray diffraction diagrams of the products
obtained in Examples 6-3 and 6-6 are shown in FIGS. 15B and 15C.
Meanwhile, when a zeolite is synthesized from the gel alone, all of
the gels used in the examples have a composition from which
mordenite (MOR) is produced. In addition, the .sup.27Al MAS NMR
spectra of the products obtained in Examples 6-1 and 6-2 are shown
in FIGS. 16A and 16B. The presence proportions (molar ratios) of
tetracoordinate aluminum and six-coordinate aluminum, which were
obtained from the spectra, are shown in Table 11.
TABLE-US-00011 TABLE 11 Seed crystals Aging Gel composition
Addition conditions SiO.sub.2/ Na.sub.2O/ Li.sub.2O/ H.sub.2O/
SiO.sub.2/ amount*.sup.1 Temperature Example Al.sub.2O.sub.3
SiO.sub.2 SiO.sub.2 SiO.sub.2 Al.sub.2O.sub.3 (wt %) (.degree. C.)
Time (h) 6-1 20 0.175 0.050 25 24.0 10 80 16 6-2 18 0.165 0.050 25
24.0 10 -- -- 6-3 16 0.160 0.050 15 24.0 10 -- -- 6-4 14 0.155
0.050 15 24.0 10 -- -- 6-5 14 0.155 0.035 15 24.0 10 -- -- 6-6 12
0.155 0.050 15 24.0 10 -- -- 6-7 16 0.165 0.020 15 24.0 10 -- --
6-8 16 0.170 0.010 15 24.0 10 -- -- Products Reaction BET
Coordination number conditions specific and presence Temperature
Time SiO.sub.2/ surface proportion of Al Example (.degree. C.) (h)
Zeolite Al.sub.2O.sub.3 area (m.sup.2/g) (%) 6-1 170 72 BEA 8.8 518
Tetracoordinate: 98 Six-coordinate: 2 6-2 150 72 BEA 7.0 548
Tetracoordinate: 80 Six-coordinate: 20 6-3 150 46 BEA 6.8 472
Tetracoordinate: 75 Six-coordinate: 25 6-4 150 44 BEA 5.8 537
Tetracoordinate: 62 Six-coordinate: 38 6-5 150 45 BEA 6.4 410
Tetracoordinate: 71 Six-coordinate: 29 6-6 150 42 BEA 5.2 485
Tetracoordinate: 60 Six-coordinate: 40 6-7 150 62 BEA 9.0 529
Tetracoordinate: 88 Six-coordinate: 12 6-8 150 68 BEA 9.4 481
Tetracoordinate: 95 Six-coordinate: 5 *.sup.1Amount of silica in
the gel
TABLE-US-00012 TABLE 12 Gel composition Seed crystals Reaction
conditions Comparative SiO.sub.2/ Na.sub.2O/ Li.sub.2O/ H.sub.2O/
Addition Temperature Time Products Example Al.sub.2O.sub.3
SiO.sub.2 SiO.sub.2 SiO.sub.2 SiO.sub.2/Al.sub.2O.sub.3
amount*.sup.1 (wt %) (.degree. C.) (h) Zeolite 6-1 30 0.190 0.050
15 -- 0 150 168 MOR 6-2 20 0.175 0.050 25 -- 0 150 168 MOR 6-3 18
0.165 0.050 15 -- 0 150 168 MOR 6-4 16 0.160 0.050 15 -- 0 150 168
MOR 6-5 12 0.155 0.050 15 -- 0 150 168 MOR *.sup.1Amount of silica
in the gel
Example 7-1
[0171] Dealumination of a Zeolite
[0172] An aqueous solution of 1 N citric acid (10 ml) and the beta
zeolite obtained in Example 5-9 (0.2) were mixed so as to obtain a
liquid mixture. The liquid mixture was fed into an autoclave,
heated at 135.degree. C. for 96 hours, and dealumination of the
zeolite was carried out. After completion of heating, the zeolite
was filtered, washed using water, and, then, fired at 550.degree.
C. for six hours in the atmospheric atmosphere. For the fired
zeolite, the SiO.sub.2/Al.sub.2O.sub.3 ratio and Na/Al ratio were
chemically analyzed. An ICP-AES was used for the analysis. The
results are shown in Table 13. In addition, the X-ray diffraction
diagram of the obtained zeolite is shown in FIG. 17A.
Example 7-2
[0173] Dealumination of a zeolite was carried out in the same
manner as in Example 7-1 except that the conditions shown in the
following Table 13 were employed as the conditions of the
dealumination. The same analysis as in Example 7-1 was carried out
on the obtained zeolite. The results are shown in Table 13. In
addition, the X-ray diffraction diagram of the obtained zeolite is
shown in FIG. 17B.
Example 7-3
[0174] A mixed aqueous solution of 1 M citric acid and 1 M ammonium
nitrate was used instead of the aqueous solution of 1 M citric
acid. In addition, the conditions shown in the following table 13
were employed as the conditions of the dealumination. Dealumination
of a zeolite was carried out in the same mariner as in Example 7-1
except the above. The same analysis as in Example 7-1 was carried
out on the obtained zeolite. The results are shown in Table 13. In
addition, the X-ray diffraction diagram of the obtained zeolite is
shown in FIG. 17C.
Examples 7-4 to 7-6
[0175] The MEL zeolite obtained in Example 2-2 (Example 7-4), the
MSE zeolite obtained in Example 3-6 (Example 7-5), and the MTW
zeolite obtained in Example 4-7 (Example 7-6) were used instead of
the beta zeolite used in Example 7-1. In addition, the conditions
shown in the following table 13 were employed as the conditions of
the dealumination. Dealumination of a zeolite was carried out in
the same manner as in Example 7-1 except the above. The same
analysis as in Example 7-1 was carried out on the obtained zeolite.
However, in Example 7-5, the K/Al ratio in addition to the Na/Al
ratio was analyzed. The results are shown in Table 13. In addition,
the X-ray diffraction diagrams of the obtained zeolites are shown
in FIG. 18A to 18C.
TABLE-US-00013 TABLE 13 Dealumination treatment After Concentration
Concentration dealumination Zeolite of citric of ammonium
Temperature Time SiO.sub.2/ Example Kind SiO.sub.2/Al.sub.2O.sub.3
acid (M) nitrate (M) (.degree. C.) (h) Al.sub.2O.sub.3 Na/Al 7-1
BEA (Example 5-9) 10.4 1.0 0.0 135 96 64.6 0.03 7-2 BEA (Example
5-9) 10.4 0.5 0.0 80 24 46.4 0.02 7-3 BEA (Example 5-9) 10.4 1.0
1.0 80 24 21.4 0.04 7-4 MEL (Example 2-2) 18.8 0.5 0.0 80 24 32.6
0.17 7-5 MSE (Example 3-6) 13.0 0.5 0.0 80 24 39.0 0.03 (Na/Al)
0.60 (K/Al) 7-6 MTW (Example 4-7) 32.4 0.5 0.0 80 24 34.6 0.35
[0176] As is evident from the results shown in Table 13, it is
found that the SiO.sub.2/Al.sub.2O.sub.3 ratios of zeolites
extremely increase due to dealumination using citric acid. In
addition, it is found that the Na/Al ratios approximate to zero,
and the zeolites are converted into H-type zeolite. Furthermore, it
is found from the results of FIGS. 17 and 18 that the crystallinity
of zeolites is maintained even when dealumination is carried
out.
* * * * *