JP7109184B2 - MWF-type zeolite and gas separation method - Google Patents

Description

The present invention relates to an MWF-type zeolite and a gas separation method.

Zeolites can be used as adsorbents, desiccants, separating agents, separation membranes, catalysts, catalyst carriers, detergent aids, ion exchange agents, wastewater treatment agents, fertilizers, food additives, cosmetic additives, etc. Among them, It is useful for gas separation applications.
Here, the MWF-type zeolite means a zeolite having an MWF structure with a code that defines the structure of zeolite defined by the International Zeolite Association (IZA). Patent Document 1 discloses ZSM-25, which is a type of MWF-type zeolite. In addition, as described in Patent Document 2 and Non-Patent Document 1, the structure of ZSM-25, which is a type of MWF-type zeolite, has recently been clarified. The structure is reported to be a zeolite with a hexahedral crystal system Im3m space group and pores composed of eight-membered oxygen rings. In addition, by selectively adsorbing carbon dioxide, it is reported to be used for the separation of carbon dioxide and methane and the separation of carbon dioxide and nitrogen.

U.S. Pat. No. 4,247,416 Korean patent 101555149

Peng Guo, Jiho Shin, Alex G.; Greenaway, Jung Gi Min, Jie Su, Hyun June Choi, Leifeng Liu, Paul A.; Cox, Suk Bong Hong, Paul A.; Wright, Xiaodong Zou. "A zeolite family with expanding structural complexity and embedded isoretic structures" Nature. 2015, 524, 74-78.

In natural gas refining plants, the development of low-quality gas fields is progressing in response to an increase in demand, and separation of carbon dioxide and methane from gas containing high-concentration carbon dioxide is desired. In addition, in recent years, due to the decrease in the amount of flue gas from naphtha, the production of liquefied carbon dioxide from high-concentration carbon dioxide flue gas has decreased, so there is a need for a more selective carbon dioxide refining technology.
However, the MWF-type zeolites disclosed in Patent Document 1, Patent Document 2, Non-Patent Document 1, etc. do not have sufficient gas separation ability to meet the above-described high requirements.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an MWF-type zeolite membrane having high carbon dioxide permeation selectivity and high permeation rate.

The present inventors have made intensive studies to solve the above problems, and as a result, in the diffraction pattern obtained by subjecting the MWF-type zeolite to X-ray diffraction measurement, the intensity ratio of the specific diffraction peak is in the range of a predetermined value. The inventors have found that the problems of the present application can be solved by using type zeolite, and have completed the present invention.

That is, the present invention is as follows.
[1]
An MWF-type zeolite membrane comprising an MWF-type zeolite,
An MWF-type zeolite that satisfies 0.24 ≤ B/A < 0.38, where A and B are the peak heights near 2θ = 11.1 and 16.8° in the peaks obtained by X-ray diffraction. film.
[2]
The MWF-type zeolite membrane according to [1], which has a thickness of 0.1 μm or more and 50 μm or less.
[3]
A gas mixture comprising a plurality of gas components is brought into contact with the MWF-type zeolite membrane according to [1] or [2], and from the gas mixture, a gas component having a high permeation rate through the MWF-type zeolite membrane is removed from the MWF-type zeolite membrane. A method for separating a gas, comprising the step of permeating to and separating.
[4]
The gas mixture contains carbon dioxide, hydrogen, oxygen, nitrogen, methane, ethane, ethylene, propane, propylene, normal butane, isobutane, 1-butene, 2-butene, isobutene, sulfur hexafluoride, helium, carbon monoxide, The gas separation method according to [3], which contains at least two gas components selected from the group consisting of nitrogen monoxide, hydrogen sulfide and water.

According to the present invention, it is possible to provide an MWF-type zeolite membrane with high carbon dioxide permeation selectivity and high permeation rate.

1 is an X-ray diffraction (XRD) diagram of the MWF-type zeolite obtained in Example 1. FIG. 1 is an X-ray diffraction (XRD) diagram of the MWF-type zeolite obtained in Example 2. FIG.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail. The present invention is not limited to the following description, and various modifications can be made within the scope of the gist thereof.

The MWF-type zeolite membrane of the present embodiment contains MWF-type zeolite. Furthermore, in the MWF-type zeolite membrane of the present embodiment, in the peak obtained by X-ray diffraction, when the peak heights near 2θ = 11.1 and 16.8 ° are A and B, respectively, 0.24 ≤ B /A<0.38 is satisfied.
The MWF-type zeolite that constitutes the MWF-type zeolite membrane of the present embodiment (hereinafter also referred to as "MWF-type zeolite in the present embodiment") has little distortion and defects in the crystal lattice, and has a clearly formed crystal microstructure. In addition, since the higher-order structure including the eight-membered ring structure is regularly arranged, the selectivity of carbon dioxide adsorption to the amount of methane adsorbed is high. Owing to such properties of MWF-type zeolite, the MWF-type zeolite membrane of the present embodiment exhibits high carbon dioxide permeation selectivity and a high carbon dioxide permeation rate. That is, the MWF-type zeolite in the present embodiment, like the MWF-type zeolite membrane of the present embodiment, has peak heights near 2θ=11.1 and 16.8° in the peaks obtained by X-ray diffraction, respectively. where B satisfies 0.24≦B/A<0.38, and it can be said that the B/A values of the MWF-type zeolite of the present embodiment and the MWF-type zeolite membrane of the present embodiment are in good agreement. .

[X-ray diffraction peak]
In the MWF-type zeolite membrane of the present embodiment and the MWF-type zeolite of the present embodiment, in the peaks obtained by X-ray diffraction, when the peak heights near 2θ = 11.1 and 16.8 ° are A and B, respectively , 0.24≦B/A<0.38.
Here, the X-ray diffraction pattern is obtained by irradiating the surface of zeolite uniformly fixed on a non-reflective sample plate for powder with X-rays from CuKα as a radiation source, with the scanning axis as θ/2θ.
The peak near 2θ=11.1° refers to the maximum peak existing in the range of 11.1°±0.1°.
The peak near 2θ=16.8° refers to the maximum peak existing in the range of 16.8°±0.2°.

Among the X-ray diffraction peaks at 25° C. of the MWF-type zeolite membrane of the present embodiment and the MWF-type zeolite of the present embodiment, the peaks near 2θ=11.1 and 16.8° are (4 4 0) and ( 7 4 3) diffraction peak. When the heights of these diffraction peaks are A and B, respectively, a large value of peak height A means that a higher-order structure such as an eight-membered ring structure is clear, that is, fine structures are regularly arranged. , suggesting that the pores are properly formed. By properly forming the pore structure without defects, the molecular sieve effect of MWF-type zeolite works for gas molecules of different sizes, allowing CO ₂ to enter the pores, but making it difficult for CH ₄ to enter the pores. When placed in a mixed gas of CO ₂ and CH ₄ , it is thought that the selective adsorption of CO ₂ is increased, and that the permeation selectivity of CO ₂ is increased when formed into a membrane. From this point of view, it is important that the value of A is relatively large, and B/A is preferably small. That is, in the MWF-type zeolite membrane of the present embodiment and the MWF-type zeolite of the present embodiment, B/A is less than 0.38, preferably 0.375 or less, more preferably 0.37 or less. preferable.
On the other hand, B has a higher index of reflection than A and reflects a finer structure, and when B is large, it indicates that a finer structure is clear. That is, there are few defects in Si--O or Al--O bonds, the uniformity of bond distance and angle is high, and defects such as CH ₄ entering the crystal lattice and sites that adsorb CH ₄ are generated. Since CO ₂ adsorption site defects are less likely to occur, when placed in a mixed gas of CO ₂ and CH ₄ , the CO ₂ /CH ₄ adsorption amount ratio can be maximized, and when made into a membrane, it can permeate the membrane. It is believed that this increases the permselectivity of CO ₂ . Therefore, higher B is preferable. Furthermore, the reflection index of A is 4 4 0, and has sensitivity to crystallinity in the a-axis and b-axis directions, but has no sensitivity in the c-axis direction. , b-axis, and c-axis. Therefore, the fact that B is higher than A indicates that the higher-order structures such as the 8-membered ring structure reflected in A are regularly arranged in the three-dimensional direction. The fact that the higher-order structures such as the eight-membered ring structure are regularly arranged in the three-dimensional direction means that the pores are continuously arranged without interruption. It is a state in which the pores are penetrating the front and back of the membrane without interruption. It is thought that the gas permeation rate is increased because the pores are penetrating. From this point of view, higher B/A is preferable. That is, in the MWF-type zeolite membrane of the present embodiment and the MWF-type zeolite of the present embodiment, B/A is 0.24 or more, preferably 0.245 or more, and more preferably 0.25 or more. preferable.
In particular, when the MWF-type zeolite particles are mixed with a resin, which is an optional component, to form a membrane, as will be described later, a high B/A suggests that the orientation of each particle in the membrane is aligned. This allows the carbon dioxide permeating the zeolite particles to quickly propagate to the next zeolite particle, thereby increasing the gas permeation rate of the membrane.

The above B/A value can be measured by the method described in the examples described later, and in any case, the composition ratio of the mixed gel, the conditions during hydrothermal synthesis (heating temperature and heating time), and the film formation The above range can be adjusted by a method for adjusting the conditions, the mixing conditions of the resin and the zeolite, etc., within the preferable ranges described later.

The peak half-value width obtained by X-ray diffraction indicates the crystallinity of the crystal lattice plane where the diffraction occurs, and is preferably narrower. Among them, the peak near 2θ = 11.1 ° in particular shows a higher-order structure such as an 8-membered ring structure, and represents the appropriate formation of pores. It is preferable that the half width is narrow because it affects the molecular sieve effect due to molecular shielding. That is, in the MWF-type zeolite membrane of the present embodiment and the MWF-type zeolite of the present embodiment, the range of the peak half width near 2θ = 11.1° is preferably 0.31 deg or less, more preferably 0 0.28 deg or less, more preferably 0.25 deg or less. According to the structure of MWF-type zeolite, which is suggested by having such a peak half-value width, CH ₄ does not permeate the crystal lattice, the amount of adsorption is reduced, and the lack of CO ₂ adsorption sites is eliminated. Since the adsorption amount of these can be maximized, the adsorption amount ratio of CO ₂ /CH ₄ can be maximized. The inventor presumes that this can be done quickly.
The value of the half-value width of the peak is determined by adjusting the composition ratio of the mixed gel, the conditions during hydrothermal synthesis (heating temperature and heating time), the film forming conditions, the mixing conditions of the resin and the zeolite, etc., within the preferred ranges described later. The above range can be adjusted by, for example.

As will be described later, when a resin is added to the MWF-type zeolite of the present embodiment to form a film, the smaller the particle size of the MWF-type zeolite of the present embodiment, the more highly dispersed the particles are, and the thinner the film thickness becomes. . On the other hand, from the viewpoint of ensuring sufficient crystallinity, it is preferable to increase the particle size of the MWF-type zeolite. Taking these into consideration, the average particle size of the MWF-type zeolite in the present embodiment is preferably 10 nm or more and 5 μm or less, more preferably 30 nm or more and 3 μm or less, and even more preferably 50 nm or more and 2 μm or less.

(Optional component)
The MWF-type zeolite membrane of the present embodiment can contain optional components other than the MWF-type zeolite of the present embodiment, as long as the peak ratio 0.24≦B/A<0.38 is satisfied. For example, the MWF-type zeolite membrane of the present embodiment can further contain a resin as an optional component. In this embodiment, the resin is preferably a resin having a polarized functional group.
Polarized functional groups include, but are not limited to, hydroxyl groups, amino groups, nitrile groups, carbonyl groups, ether groups, and the like. Resins containing at least one of these include the following: Examples include moisture-curable silicone resins, polyurethane resins, polyether resins, polyamide resins, and polyimide resins. Polarized functional groups are coordinated with polarized points such as hydroxyl groups and acid sites on the surface of MWF-type zeolite, and have high adhesiveness. contribute.
The content of the resin in the MWF-type zeolite membrane of the present embodiment is not particularly limited, but is 10% by mass or more and 70% by mass or less from the viewpoint of the balance between the film-forming properties and the gas separation properties and gas permeability of the zeolite. more preferably 20% by mass or more and 60% by mass or less, and even more preferably 30% by mass or more and 55% by mass or less.

In this embodiment, as described above, the value of B/A is set within a specific range. The B/A value suggests that the higher-order structures such as the eight-membered ring structure are regularly arranged in a three-dimensional direction, that is, the pores are continuously arranged without interruption. Inside the MWF-type zeolite membrane, the pores are in a state in which the pores penetrate through the front and back of the membrane without being interrupted. As described above, the MWF-type zeolite membrane of the present embodiment has a desired crystal structure, so that a good gas permeation rate can be obtained even when the membrane thickness is increased. Therefore, the thickness of the MWF-type zeolite membrane of this embodiment is not particularly limited. From the viewpoint of improving the balance between the strength and the permeation rate of carbon dioxide, the thickness is preferably 0.1 μm or more and 50 μm or less, more preferably 0.2 μm or more and 20 μm or less, and 0.3 μm or more and 10 μm or less. is more preferable. The film thickness can be measured by a conventional method using a scale, or by cleaving the film, observing the cross section with an electron microscope or an optical microscope, and measuring from the obtained image. Range can be adjusted. When it is mixed with a resin as an optional component, it can be adjusted within the above range by the coating amount of the mixed solution of zeolite and resin.

[Method for synthesizing MWF-type zeolite]
The method for producing an MWF-type zeolite according to the present embodiment includes a silica source containing silicon, an aluminum source containing aluminum, an alkali metal source containing at least one selected from alkali metals (M1) and alkaline earth metals (M2), and a step of preparing a mixed gel containing water.
The mixed gel and each component contained therein will be described below.

[Preparation process of mixed gel]
The process for preparing the mixed gel is not particularly limited. and aging the mixture obtained in the step.
In the mixing step, these components including a silica source, an aluminum source, an alkali metal source, water, and, if necessary, an organic structure-directing agent can be mixed at once or in multiple steps.
The order of mixing in multiple stages is not limited, and may be appropriately selected depending on the conditions used. Mixing in multiple stages may be carried out either with stirring or without stirring, but a precursor that forms a gis structure, which is a constituent element of MWF-type zeolite and does not contain an organic structure-directing agent, is produced. From the point of view, it is preferable to use a mixed solution containing an alkali metal source, an aluminum source, and a silica source, and to have a stirring step and an aging step. When the aluminum source and silica source are mixed and aged, the temperature is preferably low from the viewpoint of suppressing excessive condensation reaction between Al and Si and achieving both precursor formation and uniform mixing. Specifically, the temperature in the mixing, stirring and aging steps is preferably 15°C or less. From the viewpoint of preventing excessive condensation reaction and sufficiently uniform mixing, the time for mixing, stirring and aging steps is preferably 10 minutes or more and 24 hours or less, more preferably 20 minutes or more and 12 hours or less, 30 minutes or more, Eight hours or less is most preferred.

From the viewpoint of promoting the formation of the MWF-type zeolite skeleton by forming precursors of the gis structure, which is the internal structure of the MWF-type zeolite, and surrounding them to form precursors of lta and pau structures containing an organic structure-directing agent. , an alkali metal source, an aluminum source, and a silica source are mixed first, and then the organic structure-directing agent is added to the mixed solution containing these sources. The temperature and time of the mixing, stirring, and aging steps of the mixed gel obtained by mixing the organic structure-directing agent with the alkali metal source, aluminum source, and silica source are set to 15° C. or less from the viewpoint of preventing excessive condensation reaction and sufficiently uniform mixing. 10 minutes or more and 24 hours or less are preferable, 12° C. or less, 20 minutes or more and 12 hours or less are more preferable, and 10° C. or less and 45 minutes or more and 8 hours or less are most preferable. From the above, it is presumed that the fine structure and the long-period structure are properly formed and high crystallization is achieved, thereby optimizing the B/A and the half-value width and obtaining high CO ₂ selectivity.
The stirring is not particularly limited as long as it is a generally used stirring method, but specific examples include methods using blade stirring, vibration stirring, rocking stirring, centrifugal stirring, and the like.
The rotation speed for stirring is not particularly limited as long as it is a generally used stirring speed, and is, for example, 1 rpm or more and less than 2000 rpm.
The time of the mixing step is not particularly limited, and can be appropriately selected depending on the temperature of the mixing step.
From the standpoint of excellent economic efficiency, the faster the rate of addition of the raw materials in the mixing step, the higher the production efficiency. On the other hand, from the viewpoint of suppressing excessive condensation reaction between Al and Si and achieving both precursor formation and uniform mixing, a slow addition rate is preferable. From these points of view, when preparing a mixed gel of about 100 cc, it is preferably 0.1 cc/min or more and 100 cc/min or less, more preferably 0.2 cc/min or more and 50 cc/min or less, and 0.1 cc/min or more and 100 cc/min or less. Most preferably, it is 5 cc/min or more and 10 cc/min or less.
The aging step may be carried out either by standing still or by stirring.
When stirring in the aging step, there is no particular limitation as long as it is a generally used stirring method, but specific examples include methods using blade stirring, vibration stirring, rocking stirring, centrifugal stirring, and the like. .
The rotation speed for stirring is not particularly limited as long as it is a generally used stirring speed, and is, for example, 1 rpm or more and less than 2000 rpm.

[Mixed gel]
The mixed gel in the present embodiment is a mixture containing a silica source, an aluminum source, an alkali metal source and water as essential components, preferably containing an organic structure directing agent.
The silica source is a component in the mixed gel that serves as a raw material for silicon contained in the zeolite produced from the mixed gel, and the aluminum source is a raw material for aluminum contained in the zeolite produced from the mixed gel. The alkali metal source refers to a component in the mixed gel that serves as a raw material for the alkali metal and/or alkaline earth metal contained in the zeolite produced from the mixed gel.

[Silica source]
The silica source is not particularly limited as long as it is commonly used, but specific examples include amorphous silica, colloidal silica, wet silica, dry silica, silica gel, sodium silicate, and amorphous aluminosilicate. gel, tetraethoxysilane (TEOS), trimethylethoxysilane, and the like. These compounds may be used singly or in combination. Here, the amorphous aluminosilicate gel serves as both a silica source and an aluminum source.
Among these, amorphous silica, colloidal silica, wet silica, dry silica, and silica gel are preferred because they tend to yield zeolite with a high degree of crystallinity. From the same point of view, colloidal silica, wet-process silica, and dry-process silica are more preferable.
Examples of colloidal silica include, but are not limited to, Ludox®, Syton®, Nalco®, Snowtex®.
Examples of wet-process silica include, but are not limited to, Hi-Sil (registered trademark), Ultrasil (registered trademark), Vulcasil (registered trademark), Santocel (registered trademark), Valron-Estersil (registered trademark), Tokusil ( registered trademark), Zeosil (registered trademark), Carplex (registered trademark), Mizukasil (registered trademark), Sylysia (registered trademark), Syloid (registered trademark), Gasil (registered trademark), Silcron (registered trademark), Nipgel (registered trademark ), and Nipsil®.
Examples of dry process silica include HDK (registered trademark), Aerosil (registered trademark), Reolosil (registered trademark), Cab-O-Sil (registered trademark), Fransil (registered trademark), and ArcSilica (registered trademark).

[Aluminum source]
The aluminum source is not particularly limited as long as it is commonly used, but specific examples include sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum acetate, aluminum hydroxide, aluminum oxide, aluminum chloride, and aluminum alkoxide. , metallic aluminum, amorphous aluminosilicate gel, and the like. These compounds may be used singly or in combination.
Among these, sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum acetate, aluminum hydroxide, aluminum chloride, and aluminum alkoxide are preferred because they tend to yield zeolite with a high degree of crystallinity. From the same point of view, sodium aluminate and aluminum hydroxide are more preferred, and sodium aluminate is even more preferred.

[Alkali metal source]
The type of alkali in the alkali metal source is not particularly limited, and any alkali metal and/or any alkaline earth metal compound can be used.
Alkali metal sources include, but are not limited to, alkali metal or alkaline earth metal hydroxides, bicarbonates, carbonates, acetates, sulfates, nitrates, and the like. These compounds may be used alone or in combination.
Li, Na, K, Rb, Cs, Ca, Mg, Sr, Ba and the like can be used as alkali metals and alkaline earth metals used as alkali metal sources. Na and K are preferable, and Na is more preferable, from the viewpoint of facilitating crystal formation of the MWF-type skeleton. Also, the alkali metals and alkaline earth metals used as the alkali metal source may be used singly or in combination.
Specifically, examples of alkali metal sources include, but are not limited to, sodium hydroxide, sodium acetate, sodium sulfate, sodium nitrate, sodium carbonate, sodium hydrogen carbonate, potassium hydroxide, potassium acetate, potassium sulfate, potassium nitrate. , potassium carbonate, potassium hydrogen carbonate, lithium hydroxide, lithium acetate, lithium sulfate, lithium nitrate, lithium carbonate, lithium hydrogen carbonate, rubidium hydroxide, rubidium acetate, rubidium sulfate, rubidium nitrate, rubidium carbonate, rubidium hydrogen carbonate, hydroxide Cesium, cesium acetate, cesium sulfate, cesium nitrate, cesium carbonate, cesium hydrogen carbonate, calcium hydroxide, calcium acetate, calcium sulfate, calcium nitrate, calcium carbonate, calcium hydrogen carbonate, magnesium hydroxide, magnesium acetate, magnesium sulfate, magnesium nitrate , magnesium carbonate, magnesium hydrogen carbonate, strontium hydroxide, strontium acetate, strontium sulfate, strontium nitrate, strontium carbonate, strontium hydrogen carbonate, barium hydroxide, barium acetate, barium sulfate, barium nitrate, barium carbonate, barium hydrogen carbonate, etc. be done.
Among these, sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide, calcium hydroxide, magnesium hydroxide, strontium hydroxide and barium hydroxide are preferred, and sodium hydroxide, potassium hydroxide, Lithium hydroxide, rubidium hydroxide and cesium hydroxide are more preferred, and sodium hydroxide is even more preferred.

[Organic Structure Directing Agent]
The organic structure-directing agent in producing zeolite by hydrothermally synthesizing a mixed gel is a compound that promotes crystallization into a zeolite structure. In crystallization of zeolite, an organic structure-directing agent can be used as necessary. It is preferable to synthesize using a mixed gel containing an organic structure directing agent from the viewpoint that the crystal formation of the MWF-type skeleton becomes easier and/or the synthesis time is shortened and the zeolite is produced more economically. .
The organic structure-directing agent may be of any type as long as it can form a desired MWF-type zeolite. Further, the organic structure-directing agents may be used singly or in combination.
Examples of organic structure-directing agents include, but are not limited to, amines, quaternary ammonium salts, alcohols, ethers, amides, alkylureas, alkylthioureas, cyanoalkanes, containing nitrogen as a heteroatom. Alicyclic heterocyclic compounds can be used, preferably quaternary ammonium salts, more preferably tetraalkylammonium salts, and even more preferably tetraethylammonium salts.
Such salts are associated with anions. Representatives of such anions include, but are not limited to, halogen ions such as Cl ⁻ , Br ⁻ , I ⁻ , hydroxide ions, acetate ions, sulphate ions, nitrate ions, carbonate ions and carbonate ions. Contains hydrogen ions. Among these, halogen ions and hydroxide ions are preferred, and halogen ions are more preferred, from the viewpoint of facilitating crystal formation of the MWF-type skeleton.
[Composition ratio of mixed gel]
The ratio of the silica source and OH ^- in the mixed gel is represented by the molar ratio of OH ^- to SiO ₂ , that is, OH ^- /SiO ₂ (OH ^- is the alkali metal source and/or the hydroxide contained in the organic structure directing agent). ions). In order to synthesize the MWF-type zeolite in this embodiment, it is desirable to control the conditions for synthesizing the precursor oligomer.
Since the 8-membered ring structure is formed without loss, the molecular sieve effect is exhibited, and the CH ₄ adsorption amount is reduced. The intensity ratio of peak A derived from a higher-order structure such as an 8-membered ring structure is high. It is desirable to form higher-order structures. From these points of view, it is preferable to prevent re-dissolution of the grown zeolite, and in order to suppress dissolution, it is preferable that OH ^- is as small as possible.
On the other hand, if there is a defect or distortion in the fine structure that constitutes the 8-membered ring or skeleton, that is, in the Si—O or Al—O bond, the number of CO ₂ adsorption sites may decrease, and the amount of CO ₂ adsorption may decrease. be. When such a fine structure is formed without defects or distortion, the peaks B and C, which are parallel to the plane belonging to the peak A and originate from finer structures, are relatively high. In order not to cause Si--O or Al ^-- O defects and bond strain, it is preferable to dissolve more of the raw material silica source and aluminum source. preferable.
Therefore, the MWF-type zeolite, which has a large amount of CO ₂ adsorption and a small amount of CH ₄ adsorption, is limited to cases where B/A is within a specific range. As a result of intensive studies by the inventors, the amount of OH ^- present in the synthesis liquid relative to SiO ₂ is such that if 0.10≦OH ^- /SiO ₂ ≦0.60, Si—O or Al—O It is possible to synthesize an MWF-type zeolite capable of achieving a specific ratio of B/A without causing defects or bond strain.
Within the above range, OH ⁻ /SiO ₂ is more preferably 0.15 or more, even more preferably 0.18 or more.
Within the above range, OH ^- /SiO ₂ is more preferably less than 0.40, more preferably 0.35 or less.
The ratio of silica source and aluminum source in the mixed gel is expressed as the molar ratio of the oxides of the respective elements _, ie _SiO2 / _Al2O3 .
The ratio of SiO ₂ /Al ₂ O ₃ is not particularly limited as long as the ratio is capable of forming zeolite, but since the formation of zeolite having a skeleton different from the MWF type skeleton tends to be suppressed, it is preferably 5.0 or more. , 6.0 or more. From the same point of view, it is more preferably 6.8 or more.
SiO ₂ /Al ₂ O ₃ is preferably 12 or less, more preferably 10 or less, since the formation of zeolite having a framework different from the MWF-type framework tends to be suppressed. From the same point of view, it is more preferably 7.8 or less.
The ratio of the aluminum source and the alkali metal source in the mixed gel is expressed as the additive molar ratio of M12O and _M2O to _Al2O3 , that is, (M12O _{+ M2O} )/ _{Al2O3 (} where M1 is an alkali metal and M2 represents an alkaline earth metal). This (M1 ₂ O+M2O)/Al ₂ O ₃ is preferably 1.3 or more, more preferably 1.5 or more, from the viewpoint of facilitating crystal formation of the MWF-type skeleton. From the same point of view, it is more preferably 1.7 or more.
(M1 ₂ O+M2O)/Al ₂ O ₃ is preferably 3.2 or less, more preferably 2.5 or less, from the viewpoint of suppressing the formation of zeolite having a framework different from the MWF-type framework. From the same point of view, it is more preferably 2.2 or less.
When the mixed gel contains an organic structure directing agent, the ratio of the aluminum source to the organic structure directing agent in the mixed gel is expressed as the molar ratio of organic structure _directing agent to _{Al2O3 ,} i.e., R/ _Al2O3 . (where R represents an organic structure directing agent). It is preferably 2.0 or more, and more preferably 3.0 or more, in terms of easier crystal formation of the MWF-type skeleton and/or shorter synthesis time and excellent economic efficiency in producing zeolite. preferable. From the viewpoint of suppressing the formation of zeolite having a skeleton different from the MWF-type skeleton, it is more preferably 4.0 or more.
R/Al ₂ O ₃ is preferably 50 or less, more preferably 30 or less, from the viewpoint of shortening the synthesis time and improving the economic efficiency in producing zeolite. From the viewpoint of suppressing the formation of zeolite having a skeleton different from the MWF-type skeleton, it is more preferably 20 or less.
_The ratio of aluminum source to water in the mixed gel is expressed as the molar ratio of water to _{Al2O3 , H2O} / _Al2O3 . It is preferably 70 or more, more preferably 80 or more, because the components in the mixed gel tend to be more uniformly dispersed. From the viewpoint of suppressing the formation of zeolite having a skeleton different from the MWF-type skeleton, it is more preferably 90 or more.
The H ₂ O/Al ₂ O ₃ ratio is preferably 3,000 or less, more preferably 1,000 or less, from the viewpoint of shortening the synthesis time and being excellent in economic efficiency in producing zeolite. From the viewpoint of suppressing the formation of zeolite having a skeleton different from the MWF-type skeleton, it is more preferably 500 or less.
As described above, in the method for producing an MWF-type zeolite in the present embodiment, a silica source containing silicon, an aluminum source containing aluminum, and at least one selected from alkali metals (M1) and alkaline earth metals (M2) are used. and water, wherein the molar ratio of each component in the mixed gel is determined with respect to the silicon, aluminum, alkali metal (M1) and alkaline earth metal (M2) When calculated as an oxide of each element, the molar ratios α, β, γ, δ represented by the following formulas (1), (2), (3) and (4) are 5.0 ≤ α ≤ 12 , 1.3≦β≦3.2, 70≦γ≦3000 and 0.10≦δ≦0.60. It is particularly preferable that the MWF-type zeolite in the present embodiment is obtained by the method for producing the MWF-type zeolite in the present embodiment described above.
α=SiO ₂ /Al ₂ O ₃ (1)
β=(M1 ₂ O+M2O)/Al ₂ O ₃ (2)
γ=H ₂ O/Al ₂ O ₃ (3)
δ=OH ⁻ /SiO ₂ (4)
Furthermore, in the method for producing MWF-type zeolite in the present embodiment, the molar ratios α, β, γ, and δ satisfy the above ranges, the mixed gel further contains an organic structure directing agent R, and the following formula (5 ) more preferably satisfies 2.0≦ε≦50.
ε=R/Al ₂ O ₃ (5)
Although seed crystals do not necessarily exist in the mixed gel, MWF-type zeolite according to the present embodiment can also be obtained by adding previously produced MWF-type zeolite as seed crystals to the mixed gel.

[Hydrothermal synthesis step]
The method for producing MWF-type zeolite in the present embodiment preferably further includes a hydrothermal synthesis step in which the hydrothermal synthesis temperature is 100°C to 170°C. That is, preferably, the mixed gel obtained in the preparation step is hydrothermally synthesized by holding the mixed gel at a predetermined temperature for a predetermined time while stirring or standing still.
The temperature of the hydrothermal synthesis is not particularly limited as long as it is a commonly used temperature, but it is preferably 100° C. or higher from the viewpoint of shortening the synthesis time and improving the economic efficiency of zeolite production. From the viewpoint of suppressing the formation of zeolite having a skeleton different from the MWF-type skeleton, the temperature is more preferably 110° C. or higher, and even more preferably 115° C. or higher.
The temperature is preferably 170° C. or lower because it tends to suppress the decomposition of the organic structure-directing agent. From the viewpoint of suppressing the formation of zeolite having a skeleton different from the MWF-type skeleton, the temperature is more preferably 155° C. or lower, and even more preferably 145° C. or lower.
The temperature for hydrothermal synthesis may be constant or may be changed stepwise.
The hydrothermal synthesis time is not particularly limited as long as it is a generally used time, and can be appropriately selected depending on the hydrothermal synthesis temperature.
The hydrothermal synthesis time is preferably 3 hours or longer, more preferably 10 hours or longer, in order to form the MWF skeleton. It is more preferably 24 hours or more from the viewpoint of increasing the yield of MWF-type zeolite and being excellent in economic efficiency.
It is preferably 30 days or less, more preferably 20 days or less, because it tends to suppress the decomposition of the organic structure-directing agent. From the viewpoint of suppressing the formation of zeolite having a skeleton different from the MWF-type skeleton, it is more preferably 10 days or less.
In the hydrothermal synthesis step, the container in which the mixed gel is placed is not particularly limited as long as it is a commonly used container. In that case, it is preferable to put it in a pressure vessel and perform hydrothermal synthesis.
The pressure-resistant container is not particularly limited, and various shapes such as a spherical shape, a vertically long shape, and a horizontally long shape can be used.
When stirring the mixed gel in the pressure container, the pressure container is rotated vertically and/or horizontally, preferably vertically.
When rotating the pressure container in the vertical direction, the rotation speed is not particularly limited as long as it is within the range generally used, but is preferably 1 to 50 rpm, more preferably 10 to 40 rpm.
In the hydrothermal synthesis step, in order to preferably stir the mixed gel, there is a method of using a vertically long pressure vessel and rotating it vertically.

[Separation/drying process]
After the hydrothermal synthesis step, the product solid and liquid containing water are separated, but the separation method is not particularly limited as long as it is a general method, and filtration, decantation, spray drying (rotary spray, Nozzle spraying, ultrasonic spraying, etc.), a drying method using a rotary evaporator, a vacuum drying method, a freeze-drying method, a natural drying method, or the like can be used, and the separation can be usually performed by filtration or decantation.
The separated material may be used as it is or washed with water or a predetermined solvent. If desired, the separated material can be dried.
The temperature for drying the separated material is not particularly limited as long as it is a common drying temperature, but it is usually from room temperature to 150°C or less.
The atmosphere for drying is not particularly limited as long as it is a generally used atmosphere, but an air atmosphere, an inert gas such as nitrogen or argon, or an oxygen-added atmosphere is usually used.

[Baking process]
If necessary, the MWF-type zeolite can be calcined and used. The firing temperature is not particularly limited as long as it is a temperature generally used, but when the organic structure-directing agent is desired to be removed, the remaining ratio can be reduced. is more preferable. A temperature of 400° C. or higher is more preferable from the viewpoint of shortening the calcination time and being excellent in economic efficiency when producing zeolite.
Since the crystallinity of zeolite tends to be maintained, the temperature is preferably less than 550°C, more preferably 530°C or less, and even more preferably 500°C or less.
The calcination time is not particularly limited as long as the organic structure-directing agent is sufficiently removed, and can be appropriately selected depending on the calcination temperature. Therefore, the time is preferably 0.5 hours or longer, more preferably 1 hour or longer, and even more preferably 3 hours or longer.
Since the crystallinity of zeolite tends to be maintained, the time is preferably 20 days or less, more preferably 10 days or less, and even more preferably 7 days or less.
The firing atmosphere is not particularly limited as long as it is a generally used atmosphere, but an air atmosphere, an atmosphere containing an inert gas such as nitrogen or argon, or an oxygen-added atmosphere is usually used.

[Cation exchange]
If desired, the MWF-type zeolite can be cation-exchanged to the desired cation form. Cation exchange includes, but is not limited to, NH4NO3, LiNO3, NaNO3, KNO3, _{RbNO3 , CsNO3 ,} Be( _NO3 ) ₂ , Ca _{( NO3} ) _{2 ,} Mg _{( NO3} ) ₂ , Sr(NO ₃ ) ₂ , Ba(NO ₃ ) ₂ and other nitrates, or the nitrate ions contained in the nitrates are halide ions, sulfate ions, carbonate ions, bicarbonate ions, acetate ions, phosphate ions, phosphorus Salts that are oxyhydrogen ions and acids such as nitric acid and hydrochloric acid can be used.
The temperature for cation exchange is not particularly limited as long as it is a general cation exchange temperature, but it is usually from room temperature to 100°C or less.
When separating the zeolite after cation exchange, the separation method is not particularly limited as long as it is a general method, filtration, decantation, spray drying method (rotary atomization, nozzle atomization, ultrasonic atomization, etc.), rotary evaporator can be used, such as drying, vacuum drying, freeze-drying, or air-drying, and usually separation can be carried out by filtration or decantation.
The separated material may be used as it is or washed with water or a predetermined solvent. If desired, the separated material can be dried.
The temperature for drying the separated material is not particularly limited as long as it is a common drying temperature, but it is usually from room temperature to 150°C or less.
The atmosphere for drying is not particularly limited as long as it is a generally used atmosphere, but an air atmosphere, an inert gas such as nitrogen or argon, or an oxygen-added atmosphere is usually used.
Furthermore, ammonium-type zeolite can also be converted into proton-type zeolite by calcining the zeolite.

[Method for producing microparticles]
When the MWF-type zeolite is mixed with a resin to form a thin film, the average particle size of the MWF-type zeolite can be adjusted to the preferred range described above by the method for synthesizing the MWF-type zeolite. . Specific methods for making particles smaller include, but are not limited to, wet ball milling, wet bead milling, jet milling, and the like. When using the wet ball mill method, put 100 cc of φ1 mm boric acid glass beads and 100 cc of deionized water in a 500 ml boric acid glass container, put 1 g of MWF type zeolite to be milled, and grind the container at 100 rpm to 500 rpm for 6 hours to 36 hours. By rotating and pulverizing, it is possible to make small particles without reducing the crystallinity. When the wet ball mill method is used, for example, 100 cc of φ1 mm boric acid glass beads and 100 cc of deionized water are placed in a 500 ml boric acid glass container, 1 g of MWF type zeolite to be milled is added, and the milling is performed at 100 rpm to 500 rpm for 6 hours to 36 hours. By pulverizing by rotating the time container, it is possible to make small particles without lowering the crystallinity.

[Film formation method]
The method for producing the MWF-type zeolite membrane is not particularly limited, and the MWF-type zeolite in the present embodiment can be used to form a membrane by various known methods. In the present embodiment, a film can be formed using only MWF-type zeolite, or a film can be formed together with resin in addition to MWF-type zeolite. An example of the latter will be described. The MWF-type zeolite in the present embodiment can be used, for example, as fine particles as described above. A method of putting the fine particles into a mixed solution of a resin and a solvent to form a thin film of the mixture on a support, The MWF-type zeolite membrane of the present embodiment can be produced by a method of depositing MWF-type zeolite particles as seed crystals on a support and hydrothermally synthesizing them in a raw material solution to form a thin film.
In the method of putting MWF-type zeolite particles in a mixture of a resin and a solvent and forming a thin film of the mixture on a support, the selectivity of the support is high, and an inexpensive organic porous film can be used. , is an economical film formation method. In addition, since the resin enters between the zeolite particles, it is easy to handle, such as not cracking even if the membrane is deformed, and it is excellent in terms of easy installation and processing of the membrane.
In the method of depositing MWF-type zeolite particles as seed crystals on a support and hydrothermally synthesizing them in a raw material solution to form a thin film, it becomes a continuous zeolite membrane, so the gas selective permeability and gas permeability of zeolite are improved. It is excellent in that a film with a particularly high speed can be obtained.

In the method of putting MWF-type zeolite particles in a mixture of a resin and a solvent and forming a thin film of the mixture on a support, (1) a resin having a polarized functional group is used, and (2) the resin concentration is sufficiently high. By using a solvent-diluted mixture and (3) adjusting the drying conditions after film formation, the zeolite particles are appropriately oriented, and the peak obtained by X-ray diffraction measurement of the obtained thin film has a peak value of 2θ = 11. A film satisfying 0.24≦B/A<0.38 is obtained, where A and B are the peak heights near .1 and 16.8°, respectively.
The mixed solution (2) in which the resin concentration is sufficiently diluted with a solvent is a mixed solution obtained by mixing the resin with a solvent capable of dissolving the resin to be used and dissolving the resin sufficiently. An appropriate solvent may be selected for each resin, and when moisture-curable silicone is used, toluene, tetrahydrofuran, and the like can be used. As for the mixing ratio of the resin and the solvent, the higher the solvent ratio, the lower the viscosity, the easier the zeolite particles move, and the more closely packed and oriented the particles become. On the other hand, if the solvent ratio is too high, the solvent will remain in the film when the composite film is dried, resulting in pinholes and defects. From these points of view, the concentration of the solvent in the mixture of the resin and the solvent is preferably 40% by mass or more and 90% by mass or less, more preferably 42% by mass or more and 80% by mass or less, and 43% by mass or more and 70% by mass or less. More preferred. A thin film of a mixture of zeolite and resin can be preferably obtained by adding an appropriate amount of the MWF-type zeolite (fine particles) of the present embodiment to a mixed liquid obtained by diluting an appropriate resin with a solvent at a desired concentration and forming a film. From the viewpoint of the balance between the film-forming property and the gas separation property and gas permeability of the zeolite, the amount of the MWF-type zeolite added in the present embodiment is 30% by mass or more as the concentration of the MWF-type zeolite in the present embodiment in the mixed liquid. It is preferably 90% by mass or less, more preferably 40% by mass or more and 80% by mass or less, and still more preferably 45% by mass or more and 70% by mass or less.
The drying conditions after film formation in (3) above are the optimum resins in (1) and (2) above, and a mixture of zeolite, resin, and solvent adjusted to the solvent dilution concentration is applied on a support and dried. These are the drying conditions for forming a thin film of the zeolite-resin composite by removing the solvent by means of drying. Longer drying times allow more time for the zeolite to move within the mixture of coated zeolite, resin, and solvent, facilitating closer packing and orientation of the zeolite particles within the membrane. On the other hand, if the drying time is too long, the solvent will remain in the film, causing pinholes and defects. From these points of view, the drying time is preferably 2 hours or more and 24 hours or less, more preferably 3 hours or more and 18 hours or less, and even more preferably 4 hours or more and 15 hours or less. The drying temperature can be appropriately selected according to the solvent to be volatilized, but by adjusting the temperature so that the drying time is within the above-described drying time, a film having an ideal arrangement of zeolite particles can be produced. If the drying time is too long, a vacuum may be applied to accelerate drying.
A support used for film formation is not particularly limited, but a porous resin film or an inorganic porous support having high gas permeability can be used. Porous resin membranes with high gas permeability preferably have high solvent resistance. Preferred porous membranes include cellulose acetate membranes, cellulose membranes, Teflon (registered trademark) membranes, and the like. The inorganic porous support is not particularly limited, but since it is preferable to have a high surface flatness, an alumina sintered body, a mullite sintered body, a stainless steel sintered body, or the like can be used.

In the method of forming a thin film by depositing MWF-type zeolite particles as seed crystals on a support and hydrothermally synthesizing them in a raw material solution, (4) the particle diameter of the seed crystals to be deposited and (5) film formation By setting the composition of the raw material solution used for hydrothermal synthesis at an appropriate value, the zeolite crystallites grow in an appropriate orientation within the film, and the peak obtained by X-ray diffraction measurement of the obtained thin film , where A and B are the peak heights near 2θ=11.1 and 16.8°, respectively, a film satisfying 0.24≦B/A≦0.38 is obtained.
The particle size of the seed crystal to be attached in (4) above is preferably small because if the particle size is large, the film thickness after film formation becomes thick and the transmission speed becomes slow. In addition, by using a small seed crystal, the film thickness in the initial stage of film growth is made as thin as possible, and by increasing the portion of the newly grown film as much as possible, higher-order structures such as eight-membered rings are arranged in a three-dimensional direction. , a continuous membrane can be produced before and after the membrane without discontinuous pores. On the other hand, if the size of the seed crystal is too small, the crystallinity of the seed crystal deteriorates, so the larger the seed crystal, the better. From these points of view, the particle size of the seed crystal is preferably 10 nm or more and 5 μm or less, more preferably 30 nm or more and 3 μm or less, and still more preferably 50 nm or more and 2 μm or less.
Appropriate values of the raw material liquid used for hydrothermal synthesis during film formation in (5) above are the same as the composition ratio of the mixed gel and α, δ, and ε in the method for synthesizing MWF-type zeolite particles. In particular, β (β=(M1 ₂ O+M2O)/Al ₂ O ₃ ), which is the ratio of the contents of alkali metals and alkaline earth metals to Al ₂ O ₃ , is important, and the preferred range of β is 1.4≦β. ≤3.1, more preferably 1.5≤β≤3.05, most preferably 1.6≤β≤3.0. The ratio of aluminum source to water in the mixed gel, γ=H ₂ O/Al ₂ O ₃ , tends to disperse the components in the mixed gel more uniformly. It is preferably 70 or more, more preferably 80 or more. From the viewpoint of suppressing the formation of zeolite having a skeleton different from the MWF-type skeleton, it is more preferably 90 or more. On the other hand, the higher the concentration of the solid raw material components in the mixed gel, the more the crystal growth and recrystallization tend to be promoted rather than the dissolution of seed crystals and grown films. It is more preferably 600 or less, still more preferably 450 or less.
By using a raw material solution with a preferred composition ratio, zeolite crystallites grow in a suitable orientation within the film, and the peaks obtained by X-ray diffraction measurement of the obtained thin film have 2θ=11.1 and 16.0. A membrane satisfying 0.24≦B/A<0.38 is obtained when the peak heights near 8° are A and B, respectively, and the CO ₂ /CH ₄ selectivity is high and the CO ₂ permeation rate is high. An MWF-type zeolite membrane can be produced.

[Separation of gas mixture]
By using the MWF-type zeolite membrane of the present embodiment, among the components of the gas mixture, the gas component with high selective permeability due to the MWF-type zeolite can be selectively permeated by the MWF-type zeolite membrane and separated. That is, in the gas separation method of the present embodiment, a gas mixture composed of a plurality of gas components is brought into contact with the MWF-type zeolite membrane of the present embodiment, and from the gas mixture, a gas component having high selective permeability is separated from the MWF-type zeolite membrane. It includes the step of separating by permeation through a membrane.
Examples of gas mixtures include, but are not limited to, carbon dioxide, hydrogen, oxygen, nitrogen, methane, ethane, ethylene, propane, propylene, normal butane, isobutane, 1-butene, 2-butene, isobutene, hexafluoride. Examples include those containing at least one component selected from sulfur, helium, carbon monoxide, nitrogen monoxide, water, and the like.
Furthermore, the gas mixture more preferably contains at least two of the above components. In this case, the two components are preferably a combination of a component with high permselectivity and a component with low permselectivity due to the MWF-type zeolite membrane of the present embodiment.
Exemplary gas mixture combinations include, but are not limited to, at least one component selected from the group consisting of carbon dioxide and water and at least one component selected from the group consisting of oxygen, nitrogen and methane. gas mixtures containing

Applications of the MWF-type zeolite membrane of the present embodiment are not particularly limited. Alternatively, it can be used as a catalyst for hydrocracking, alkylation, etc., a catalyst carrier for supporting metals, metal oxides, etc., an adsorbent, a drying agent, a detergent aid, an ion exchange agent, a wastewater treatment agent, a fertilizer, a cosmetic additive, etc. can be done.

EXAMPLES The present embodiment will be described in more detail below with examples and the like, but these are illustrative and the present embodiment is not limited to the following examples. A person skilled in the art can implement the present embodiment by adding various changes to the examples shown below, and such changes are included in the scope of the present invention as long as the predetermined requirements of the present embodiment are satisfied.

[Crystal structure analysis]
Crystal structure analysis was performed by the following procedure.
(1) The MWF-type zeolite membranes obtained in the respective Examples and Comparative Examples were used as samples, and were fixed on a sample stage by adjusting the height of the surface of the membrane and that of the surface of the sample stage.
(2) The film fixed in (1) above was subjected to crystal structure analysis under the following conditions, and the predetermined peak intensity and half-value width were measured.
X-ray diffractometer (XRD): Rigaku powder X-ray diffractometer "RINT2500 type" (trade name)
X-ray source: Cu tube (40 kV, 200 mA)
Measurement temperature: 25°C
Measurement range: 5 to 60° (0.02°/step)
Measurement speed: 0.2°/min Slit width (scattering, divergence, light reception): 1°, 1°, 0.15 mm

[Measurement of gas permeation selectivity and permeation rate]
Gas permeation selectivity and permeation rate were determined by the following procedure.
(1) A membrane containing MWF-type zeolite was attached to a stainless steel cell. When the membrane was a flat membrane, one side of the membrane was on the source gas side and the other side was on the permeated gas side.
(2) The source gas side was filled with a mixed gas containing 10 mol % of CO ₂ and 90 mol % of CH ₄ at 0.1 MPa and sealed.
(3) After 1 hour from the start of gas flow, the composition of the gas coming out on the permeation gas side was analyzed by gas chromatography, and the gas permeation selectivity was calculated from the composition ratio. In addition, the flow rate of the gas coming out to the permeating gas side was measured with a gas flow meter, and the gas permeation rate per unit membrane area was calculated.

[Example 1]
62.02 g of water, 0.91 g of sodium hydroxide (NaOH, manufactured by Wako Pure Chemical Industries, Ltd.), and 1.64 g of sodium aluminate (NaAlO ₂ , manufactured by Wako Pure Chemical Industries, Ltd.) are added and dissolved to form an aqueous solution. Obtained. While stirring this aqueous solution at 10° C., 10.67 g of colloidal silica (Ludox AS-40, manufactured by Grace) was added at a rate of 1 cc/min. After stirring this solution at 10° C. for 1 hour, 11.15 g of tetraethylammonium bromide (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as an organic structure directing agent is added and mixed, and the mixed gel is obtained by stirring at 10° C. for 3 hours. prepared. The composition of the mixed gel is α=SiO ₂ /Al ₂ O ₃ =7.1, β=Na ₂ O/Al ₂ O ₃ =2.1, γ=H ₂ O/Al ₂ O ₃ =380, δ= OH ⁻ /SiO ₂ =0.32 and ε=R/Al ₂ O ₃ =5.3. The mixed gel is charged into a 200 mL stainless steel autoclave containing a fluororesin inner cylinder, hydrothermally synthesized at 125 ° C. for 7 days while maintaining a vertical stirring rotation speed of 20 rpm, the product is filtered and dried at 120 ° C., A powdery zeolite was obtained.
1 g of the obtained MWF-type zeolite was placed in a 500 ml boric acid glass container, and 100 cc of φ1 mm boric acid glass beads and 100 cc of ion-exchanged water were added and pulverized by rotating at 500 rpm for 6 hours. The obtained fine MWF-type zeolite particles were observed with an FE-SEM, and the particle diameters of 200 particles were measured.
1 g of a moisture-curable silicone resin (TSE382, manufactured by Momentive Performance Materials Japan LLC) and 1 g of toluene were placed in a glass container and completely dissolved by ultrasonic cleaning. 1 g of the above-mentioned micronized MWF-type zeolite was added to this mixed liquid, and mixed by sufficiently stirring.
A porous cellulose acetate membrane (pore size: 0.45 μm, manufactured by Advantec Toyo Co., Ltd.) was attached to a glass plate, and the above-mentioned mixture of resin, solvent and zeolite was applied to the surface of the plate with an applicator. The obtained membrane was dried at 40° C. for 12 hours. After drying, the obtained film was cut with a laser cutter and attached to a sample stage, and the cross section was observed with a scanning electron microscope to measure the thickness of the thin film of the mixture of zeolite and resin. there were.
FIG. 1 shows the XRD spectrum of the resulting mixture of zeolite and resin. From the spectrum, it was confirmed that the obtained zeolite was MWF type zeolite. The peak intensity ratio obtained from the XRD pattern was B/A=0.37.
The obtained thin film of the mixture of MWF-type zeolite and resin had a CO ₂ /CH ₄ permeation selectivity of 60 and a CO ₂ permeation rate of 105 GPU.

[Example 2]
MWF-type zeolite particles were produced in the same manner as in Example 1, and micronized to 0.15 μm in the same manner as in Example 1. A micronized MWF-type zeolite was used as a seed crystal and rubbed onto an alumina porous support having a diameter of 10 mm and a length of 60 mm. Further, it was dried at 80° C. for 6 hours, and the excessively attached seed crystals were removed. This was placed in a raw material gel having the same composition as the raw material gel used in Example 1 except that γ=H ₂ O/Al ₂ O ₃ =250, and hydrothermally synthesized at 125° C. for 4 days to form a hollow tube type. An MWF-type zeolite membrane was obtained.
FIG. 2 shows the XRD spectrum of the obtained MWF-type zeolite membrane. It was B/A=0.34 from the XRD pattern. The obtained membrane was cleaved together with the support, attached to a sample table, and the cross section was observed with a scanning electron microscope to measure the thickness of the MWF-type zeolite membrane, which was 1.5 μm.
The obtained MWF-type zeolite membrane had a CO ₂ /CH ₄ permeation selectivity of 312 and a CO ₂ permeation rate of 224 GPU.

[Example 3]
61.69 g of water, 1.35 g of a 50 mass % sodium hydroxide aqueous solution, and 1.64 g of sodium aluminate were added and dissolved to obtain an aqueous solution. While stirring this aqueous solution at 10° C., 10.83 g of colloidal silica (Ludox AS-40, manufactured by Grace) was added at a rate of 1 cc/min. After stirring this solution at 10° C. for 1 hour, 11.08 g of tetraethylammonium bromide was added as an organic structure-directing agent, mixed, and stirred at 12° C. for 4 hours to prepare a mixed gel. The composition of the mixed gel is α=SiO ₂ /Al ₂ O ₃ =7.2, β=Na ₂ O/Al ₂ O ₃ =1.8, γ=H ₂ O/Al ₂ O ₃ =382, δ= OH ⁻ /SiO ₂ =0.23 and ε=R/Al ₂ O ₃ =5.3. The mixed gel is charged into a 200 mL stainless steel autoclave containing a fluororesin inner cylinder, hydrothermally synthesized at 130 ° C. for 4 days while maintaining the vertical stirring rotation speed of 20 rpm, the product is filtered and dried at 120 ° C., A powdery zeolite was obtained.
1 g of the obtained MWF-type zeolite was placed in a 500 ml boric acid glass container, and 100 cc of φ1 mm boric acid glass beads and 100 cc of ion-exchanged water were added and pulverized by rotating at 300 rpm for 4 hours. The obtained fine MWF-type zeolite particles were observed with an FE-SEM, and the particle size of 200 particles was measured. The average particle size was 0.25 μm.
1 g of a moisture-curable silicone resin (TSE382, manufactured by Momentive Performance Materials Japan LLC) and 1.2 g of toluene were placed in a glass container and completely dissolved by ultrasonic cleaning. 1 g of the above-mentioned micronized MWF-type zeolite was added to this mixed liquid, and mixed by sufficiently stirring.
The same porous cellulose acetate membrane as in Example 1 was adhered to a glass plate, and the above-mentioned mixed solution of resin, solvent and zeolite was applied to the surface thereof with an applicator. The obtained membrane was dried at 40° C. for 12 hours. When the film thickness was measured by the same method as in Example 1, the film thickness of the mixture of zeolite and resin after drying was 4 μm.
The peak intensity ratio obtained from the XRD pattern of the obtained zeolite-resin mixture was B/A=0.25.
The obtained thin film of the mixture of MWF-type zeolite and resin had a CO ₂ /CH ₄ permeation selectivity of 55 and a CO ₂ permeation rate of 115 GPU.

[Comparative Example 1]
A mixture of 20.00 g of water, 1.52 g of sodium hydroxide (NaOH, manufactured by Wako Pure Chemical Industries, Ltd.), and 11.15 g of tetraethylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an organic structure directing agent, and 42 g of water. 00 g, 1.94 g of aluminum hydroxide (Al(OH) ₃ , manufactured by Aldrich) and 10.67 g of colloidal silica (Ludox AS-40, manufactured by Grace) were mixed and stirred at 28° C. for 24 hours. A mixed gel was prepared by The composition of the mixed gel is α=SiO ₂ /Al ₂ O ₃ =7.1, β=Na ₂ O/Al ₂ O ₃ =1.9, γ=H ₂ O/Al ₂ O ₃ =380, δ= OH ⁻ /SiO ₂ =0.54 and ε=R/Al ₂ O ₃ =5.3. The mixed gel was hydrothermally synthesized at 125° C. for 7 days while stirring, and the product was filtered and dried at 120° C. to obtain powdery zeolite.
The obtained zeolite had an average particle size of 2.3 μm.
1 g of the same moisture-curable silicone resin as in Example 1 and 0.6 g of toluene (solvent concentration: 37. wt %) were placed in a glass container and completely dissolved by ultrasonic cleaning. 1 g of the MWF-type zeolite prepared in Comparative Example 1 was added to this mixed solution and thoroughly stirred to mix.
The same porous cellulose acetate membrane as in Example 1 was adhered to a glass plate, and the above-mentioned mixed solution of resin, solvent and zeolite was applied to the surface thereof with an applicator. The obtained membrane was dried at 40° C. for 12 hours. When the film thickness was measured by the same method as in Example 1, the film thickness of the mixture of zeolite and resin after drying was 8 μm.
From the XRD spectrum of the mixture of the obtained zeolite and resin, it was confirmed that the obtained zeolite was MWF type zeolite. The peak intensity ratio obtained from the XRD pattern was B/A=0.23.
The obtained thin film of the mixture of MWF-type zeolite and resin had a CO ₂ /CH ₄ permeation selectivity of 4.5 and a CO ₂ permeation rate of 87 GPU.

[Comparative Example 2]
A mixture of 56.00 g of water, 1.52 g of sodium hydroxide, and 11.15 g of tetraethylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an organic structure directing agent, 117.6 g of water, 1.94 g of aluminum hydroxide, and colloidal A mixed gel was prepared by mixing 10.67 g of silica (Ludox AS-40, manufactured by Grace) and stirring at 28° C. for 24 hours. The composition of the mixed gel is α=SiO ₂ /Al ₂ O ₃ =7.1, β=Na ₂ O/Al ₂ O ₃ =1.9, γ=H ₂ O/Al ₂ O ₃ =1060, δ= OH ⁻ /SiO ₂ =0.54 and ε=R/Al ₂ O ₃ =5.3. The mixed gel was hydrothermally synthesized at 135° C. for 14 days while stirring, and the product was filtered and dried at 120° C. to obtain powdery zeolite.
The obtained zeolite had an average particle size of 5.5 μm.
Using the obtained MWF-type zeolite as a seed crystal, it was rubbed and adhered onto an alumina porous support having a diameter of 10 mm and a length of 60 mm. Further, it was dried at 80° C. for 6 hours, and the excessively attached seed crystals were removed. This was placed in a raw material gel having the same composition as the raw material gel used in Comparative Example 2, and hydrothermally synthesized at 125° C. for 4 days to obtain a hollow-tube MWF-type zeolite membrane. When the film thickness was measured by the same method as in Example 2, the film thickness was 6.5 μm.
From the spectrum, it was confirmed that the obtained zeolite was MWF type zeolite. The peak intensity ratio obtained from the XRD pattern was B/A=0.38.
The CO ₂ /CH ₄ permeation selectivity of the obtained MWF-type zeolite thin film was 3.7, and the CO ₂ permeation rate was 7.2 GPU.

[Comparative Example 3]
69.76 g of water, 0.85 g of sodium hydroxide (NaOH, manufactured by Wako Pure Chemical Industries, Ltd.), and 1.64 g of sodium aluminate (NaAlO ₂ , manufactured by Wako Pure Chemical Industries, Ltd.) are added and dissolved to form an aqueous solution. Obtained. While stirring this aqueous solution at 28° C., 13.53 g of colloidal silica (Ludox AS-40, manufactured by Grace) was added at a rate of 1 cc/min. After stirring this solution at 28° C. for 1 hour, 39.36 g of tetraethylammonium bromide (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as an organic structure directing agent is added and mixed, and the mixed gel is obtained by stirring at 28° C. for 3 hours. prepared. The composition of the mixed gel is α=SiO ₂ /Al ₂ O ₃ =9.0, β=Na ₂ O/Al ₂ O ₃ =3.1, γ=H ₂ O/Al ₂ O ₃ =428, δ= OH ⁻ /SiO ₂ =0.47 and ε=R/Al ₂ O ₃ =18.7. The mixed gel was hydrothermally synthesized at 125° C. for 7 days while stirring, and the product was filtered and dried at 120° C. to obtain powdery zeolite.
When the film thickness was measured by the same method as in Example 1, the obtained zeolite had an average particle size of 2.5 μm.
1 g of the same moisture-curable silicone resin as in Example 1 and 1 g of toluene were placed in a glass container and were completely dissolved by ultrasonic cleaning. 1 g of the MWF-type zeolite prepared in Comparative Example 3 was added to this mixed solution and thoroughly stirred to mix.
The same porous cellulose acetate membrane as in Example 1 was adhered to a glass plate, and the above-mentioned mixed solution of resin, solvent and zeolite was applied to the surface thereof with an applicator. The obtained membrane was dried at 40° C. for 12 hours. The film thickness of the mixture of zeolite and resin after drying was 10 μm.
From the XRD spectrum of the mixture of the obtained zeolite and resin, it was confirmed that the obtained zeolite was MWF type zeolite. The peak intensity ratio obtained from the XRD pattern was B/A=0.45.
The CO ₂ /CH ₄ permeation selectivity of the obtained thin film of the mixture of MWF-type zeolite and resin was 12, and the CO ₂ permeation rate was 32 GPU.

α to ε in Table 1 represent the following molar ratios.
α= _SiO2 / _{Al2O3 ,}
β=(M12O+ _M2O )/ _{Al2O3 ,}
γ=H ₂ O/Al ₂ O ₃ ,
δ=OH ⁻ /SiO ₂ ,
ε=R/Al ₂ O ₃ (R represents an organic structure directing agent.)
Also, B/A and C/A in Table 1 are obtained as follows.
B/A = (Peak intensity near 2θ = 16.8°)/(Peak intensity near 2θ = 11.1°)

The MWF-type zeolite membrane according to the present invention is a separation membrane for various gases and liquids, a separation agent, an electrolyte membrane for fuel cells, a filler for various resin moldings, a membrane reactor, a catalyst for hydrocracking, alkylation, etc., a metal , catalyst carriers for supporting metal oxides, etc., adsorbents, desiccants, detergent aids, ion exchange agents, wastewater treatment agents, fertilizers, cosmetic additives, etc.

Claims (3)

An MWF-type zeolite membrane comprising an MWF-type zeolite,
In the peaks obtained by X-ray diffraction , the height of the maximum peak among the peaks existing in the range of 2θ = 11.1 ° ± 0.1 ° is A, and the range of 2θ = 16.8 ° ± 0.2 ° 0.24 ≤ B / A < 0.38 , where B is the height of the largest peak among the peaks present in
An MWF-type zeolite membrane having a thickness of 0.1 μm or more and 50 μm or less . A gas mixture comprising a plurality of gas components is brought into contact with the MWF-type zeolite membrane according to claim 1 , and from the gas mixture, a gas component having a high permeation rate through the MWF-type zeolite membrane is permeated through the MWF-type zeolite membrane. A gas separation method, comprising the step of separating. The gas mixture contains carbon dioxide, hydrogen, oxygen, nitrogen, methane, ethane, ethylene, propane, propylene, normal butane, isobutane, 1-butene, 2-butene, isobutene, sulfur hexafluoride, helium, carbon monoxide, 3. The gas separation method according to claim 2 , comprising at least two gas components selected from the group consisting of nitric oxide, hydrogen sulfide and water.

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