JP2001031416A - Production of zeolite membrane, mfi type zeolite membrane and separation of molecule - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a zeolite membrane which has good crystallinity and controlled orientation, by treating with steam a membrane-like article comprising zeolite seed crystals and silica. SOLUTION: The seed crystals are produced by charging a zeolite precursor slurry sol or solution containing a silica source, water and, if necessary, an alkali source, an organic template, and an aluminum source, and then subjecting the slurry sol or solution to a hydrothermal synthetic method at 50 to 250 deg.C or the like. The seed crystals are mixed with a zeolite precursor containing silica, gelling the mixture, forming a membrane like article from the gel singly or on a porous support, and then bringing the membrane-like article into contact with 100 to 200 deg.C steam to form the zeolite membrane. The obtained MFI type zeolite membrane has excellent transmittance expressed by the equation: a/b=0.3 to 1.5 and the inequality: b/c>4.4, wherein a is the maximum peak strength in 2θ of 7.3 to 8.2 degree; b is the maximum peak strength in 2θ of 8.5 to 9.1 degree; c is the maximum peak strength in 2θ of 13. 0 to 14. 2 degree, when subjecting to an X-ray diffraction measurement using a CuKα as an X-ray source at an incident angle of 3 degree and at a scanning rate of 2θ 4 degree/min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION Zeolite has pores of several angstroms in the crystal, and gas separation membranes utilizing the molecular sieve effect of the pores in the crystal of the zeolite, hydrophilicity / hydrophobicity, affinity, and the like. Applications to vapor separation membranes, membrane reactors, gas sensors, etc. are being considered. The present invention relates to a method for producing a zeolite membrane used for these applications, an MFI-type zeolite membrane, and a method for separating molecules.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a zeolite membrane, there has been known a method in which a porous support is impregnated with a slurry, a colloid, or a solution of a zeolite precursor containing silica, and then subjected to hydrothermal treatment as it is. In the method of hydrothermal treatment,
There is a drawback that a large amount of raw material is used, the amount of zeolite actually forming a membrane is small, and a large amount of waste liquid and waste inorganic solid are generated.

As a method for solving the problem, Japanese Patent Laid-Open No.
As disclosed in JP 89714, a sol or gel of a zeolite precursor is previously coated on a support, dried to form a gel film, and exposed to one or more vapors selected from organic amines, alcohols, and water. A method for producing a zeolite membrane has been proposed. In this method, a necessary amount of the raw material is applied to the support and then crystallized with steam or the like, so that the worry of waste liquid is eliminated. However, this method has a drawback that the crystallization time is long and the orientation of the zeolite crystals cannot be controlled.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to reduce the waste liquid, shorten the crystallization time, improve the crystallinity, and improve the orientation. An object of the present invention is to provide a method for producing a controllable zeolite membrane, an MFI-type zeolite membrane whose orientation is controlled, and a method for separating molecules using the zeolite membrane.

[0005]

The present invention has the following arrangement to achieve the above object.

The first aspect of the present invention is a method for producing a zeolite membrane, comprising treating a membrane containing a zeolite seed crystal and silica with steam. In the production method of the present invention, a zeolite seed crystal, after previously contacting the porous support, a solution containing silica,
It is preferred to coat the slurry or colloid to form a film and treat it with steam.

According to a third aspect of the present invention, CuKα is used as the X-ray source (wavelength = 1.54 angstroms), the incident angle is fixed at 3 degrees, and the scanning speed is 2θ.
When X-ray diffraction measurement was performed at 4 degrees / minute with a parallel optical system, the peak intensity of the maximum peak within 2θ = 7.3 to 8.2 degrees was a in the diffraction pattern, and 2θ = 8.5 to 9.5. Assuming that the maximum peak intensity within 1 degree is b and the maximum peak intensity within 2θ = 13.0 to 14.2 degrees is c, the MFI zeolite satisfying the following equations (1) and (2): It is a membrane.

(1) a / b = 0.3 to 1.5 (2) b / c> 4.4 The invention according to a fifth aspect of the present invention provides the permeable membrane or the MFI-type zeolite membrane described above. Then, a gas or liquid mixture composed of at least two types of molecules is brought into contact with at least one type of molecule to separate at least one type of molecule.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing a zeolite membrane, an MFI type zeolite membrane, and a method for separating molecules according to the present invention will be described in detail.

The zeolite referred to in the present invention is a crystalline inorganic oxide having a pore size of a molecular size. The molecular size is a range of the size of a molecule existing in the world, and generally means a range of about 2 to 20 angstroms. Zeolites are crystalline silicates, crystalline aluminosilicates, crystalline metallosilicates, crystalline aluminophosphates, crystalline microporous substances composed of crystalline metalloaluminophosphates, etc., in the present invention, And especially a zeolite containing a silica component. That is, crystalline silicate, crystalline aluminosilicate, crystalline metallosilicate, and crystalline silicoaluminum phosphate. There is no particular limitation on the type, for example, Atlas of zeolite
Structured Types (by Meyer, Olson, Baerochar, Zeolites, 17 (1/2), 199
6): Atlas of Zeolite Structure types (WM Meie
r, DH Olson, Ch. Baerlocher, Zeolites, 17 (1/2),
(1996).

The feature of the method for producing a zeolite membrane of the present invention is that
The object is to treat a film containing a zeolite seed crystal and silica with steam. What is used as seed crystal is a zeolite-containing particle which has already been fully or partially crystallized. The type of zeolite is preferably the same as the type of zeolite to be produced, but different types may help crystallization, and different types of zeolite may be used. It is presumed that the effects of the zeolite seed crystal of the present invention are shortening of the crystallization time, densification of the film, and control of the orientation of the film. The size of the crystal is preferably smaller. When the seed crystal is contained in the pores of the porous support, it is essential that the seed crystal be smaller than the pore diameter of the porous support.

The crystallization of zeolite can be divided into two processes: nucleation and growth of zeolite crystals. In general,
The process of nucleation of zeolite takes a long time. The present inventors have found that the crystallization time can be significantly reduced if a seed crystal that can be a crystal nucleus is present in advance, and that if the seed crystals are densely spread in advance, the seed crystals will grow with each other. Has been found to further promote densification. Furthermore, it has surprisingly been found that a zeolite membrane having a specific orientation can be produced by pre-existing a seed crystal.

The seed crystal is a zeolite particle produced by a usual method for producing zeolite particles. The smaller the zeolite crystal, the more preferable. The size of the crystal is not particularly limited, but is generally 5 μm or less, preferably 1 μm or less. More preferably, it is 0.1 μm or less. As the seed crystal, commercially available zeolite particles can be used, but it is also possible to produce the seed crystal by using a hydrothermal synthesis method or a steam method.

The seed crystal is prepared by placing a slurry, sol, or solution of the zeolite precursor in an autoclave,
A hydrothermal synthesis method in which the slurry is heated to a temperature of about 250 ° C. to about 250 ° C., and a steam method in which a slurry, sol, or solution of the zeolite precursor is previously dried and exposed to steam at a temperature of about 50 ° C. to 250 ° C. in an autoclave. And so on. The zeolite precursor is a mixture that can be converted to zeolite by heating for a certain period of time, for example, a silica source, an alkali source,
It contains an organic template, water, and the like. An alumina source and the like are included as necessary. Here, essential ones are a silica source and water, and others depend on the type of zeolite to be made.

As a silica source, colloidal silica, fumed silica, water glass, precipitated silica, silicon alkoxide and the like are used. The alkali source is an alkali metal hydroxide such as sodium hydroxide, lithium hydroxide, potassium hydroxide, or the like.

An organic template is a template for an organic compound that constructs pores of a zeolite, and includes an organic template such as tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide.
Grade ammonium salts, crown ethers, alcohols and the like are used.

The alumina source is necessary when producing a crystalline aluminosilicate zeolite, but aluminum salts such as aluminum nitrate, aluminum sulfate and aluminum chloride, aluminum hydroxide, aluminum oxide and aluminum alkoxide can be used.

Whether or not the seed crystal zeolite has been formed can be confirmed by powder X-ray diffraction or the like. The generated zeolite seed crystals are generally subjected to washing, drying, calcination and the like, but these operations are not particularly required. It is preferable to omit these operations from the viewpoint of reducing the production cost of the zeolite membrane.

In the production method of the present invention, a film containing a zeolite seed crystal and silica is treated with steam. A method for producing a film containing a zeolite seed crystal and silica will be described. For example, there is a method of mixing a seed crystal and a zeolite precursor containing silica and then obtaining a film by gelation or the like. Examples of the gelation include a drying method, a method using a catalyst, and the like. The film may be used alone or may be coated on a support.
Further, a zeolite seed crystal may be formed into a film by press molding or the like, and a zeolite precursor containing silica may be coated or dipped therein. In the case of a single film,
Although a certain degree of strength is required, the film coated on the support may have a low strength such as a liquid film because the support has strength. When coating with a support, the seed crystal may be coated first and then coated with a zeolite precursor containing silica, or the zeolite precursor may be coated and then coated with a zeolite seed crystal. . A mixture of a zeolite precursor and a seed crystal may be coated. The zeolite precursor containing silica is a mixture that can be converted into a zeolite by heating for a certain period of time, and contains a silica source, an alkali source, an organic template, water, and the like. An alumina source and the like are included as necessary. Here, essential ones are a silica source and water, and others depend on the type of zeolite to be made.

As the silica source, colloidal silica, fumed silica, water glass, precipitated silica, silicon alkoxide and the like are used. The alkali source is an alkali metal hydroxide such as sodium hydroxide, lithium hydroxide, potassium hydroxide, or the like.

The organic template is a template for an organic compound that constructs pores of zeolite, and includes a tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide and the like.
Grade ammonium salts, crown ethers, alcohols and the like are used.

The alumina source is necessary when producing a crystalline aluminosilicate zeolite, but aluminum salts such as aluminum nitrate, aluminum sulfate and aluminum chloride, aluminum hydroxide, aluminum oxide and aluminum alkoxide can be used.

When the seed crystal coating step and the step of coating the zeolite precursor containing silica are performed separately,
During that time, the steps of drying, baking, and washing may or may not be performed.

When a support is used, its material and form are not particularly limited, but when it is used as a permeable membrane, it is preferable to use a porous support. The material of the porous support is not particularly limited, and examples thereof include metals, metal oxides, and organic polymers. From the viewpoint of heat resistance and chemical resistance, metal oxides are preferably used. The metal oxide is not particularly limited, but may be alumina, zirconia,
Silica, mullite, titania, zeolite or zeolite analogs are preferably used. Examples of metals include
A porous support (sintered metal) made of stainless steel is exemplified. In applications where heat resistance is not required, a porous support made of an organic polymer can also be used.

The shape of the support is not particularly limited.
A commercially available product such as a sphere, a plate, a tube, a monolith, and a honeycomb can be used. Before forming the zeolite membrane of the present invention on a support, one or more intermediate layers may be provided on the support. The intermediate layer is formed by, for example, coating particles having a relatively small particle diameter on a support and, if necessary, drying or firing. The intermediate layer has effects such as smoothing the surface of the support, reducing the pore size of the support, and improving the affinity with the zeolite membrane layer. The intermediate layer or the zeolite membrane may be coated on either side of the support, or may be coated on both sides. When the support is in the form of a tube, a monolith, or a honeycomb, it is preferable to coat the inside of the support.

The method of coating the support with a zeolite seed crystal or a zeolite precursor is not particularly limited.
Any known method can be applied. For example, a method in which a support is immersed in a slurry and then pulled up as it is, a method of applying, a method in which one side of the support is brought into contact with the slurry and the pressure is reduced from the other side, and a method in which the slurry is pressed from one side of the support by applying pressure. A spin coating method in which a coating solution is dropped while rotating the support, and a spray coating method in which the coating solution is sprayed onto the support to coat the coating solution are conceivable. The coating of the zeolite membrane may be performed twice or more. Also 2
It is more preferable to perform the process more than once in terms of the denseness.

It is preferable that the seed crystal be present in the pores of the porous support in view of the strength, pressure resistance and denseness of the membrane. However, the seed crystal may be attached to the support surface. Absent.

The zeolite seed crystal and silica-containing film formed as described above is treated with steam to form a zeolite membrane.

The steam treatment is usually carried out by bringing steam at 50 ° C. to 250 ° C. into contact with a zeolite seed crystal and a film containing silica. The preferred range of temperature is 80 ° C
200 ° C. Among them, the temperature is preferably 100 ° C. or higher, more preferably 130 ° C. or higher, and particularly preferably 145 ° C. or higher. Generally, the treatment is carried out within a range of 100 ° C to 200 ° C.

Although water vapor is essential, vapors of other compounds may coexist. The vapor of another compound is, for example, vapor of amines, alcohols and the like. When the zeolite membrane contains a quaternary ammonium salt, amine is generated by partial decomposition, and the vapor is usually present. The steaming time varies depending on the type of zeolite, the type of zeolite precursor containing silica, and the temperature, but is maintained until crystallization is performed.

Whether the zeolite membrane was formed was determined by the thin film X
It can be measured by the line diffraction method. Specifically, for example, X
Using CuKα as the radiation source (wavelength = 1.54 angstroms)
X-ray diffraction measurement can be performed with a parallel optical system at an incident angle of 3 degrees and a scan speed of 2θ4 degrees / min. It can be identified by comparing the obtained X-ray diffraction pattern with the X-ray diffraction pattern of a known document. In addition, the orientation of the zeolite membrane can be considered by comparing the peak intensity ratio of each peak.

After the zeolite membrane is formed, it may be subjected to treatments such as washing with water, drying and baking. When a template is used to generate a zeolite membrane, it is essential to perform firing. When firing the generated zeolite membrane, the temperature is raised as long as possible in order to prevent the generated zeolite membrane from cracking. Preferably, the heating rate is 3
C./min or lower, more preferably 2.degree. C./min or lower, particularly preferably 1.degree. C./min or lower. Of course, it is better that the temperature drop rate is low. Preferably, the temperature is lowered at a rate of 5 ° C./min or less, more preferably 3 ° C./min or less, particularly preferably 2 ° C./min or less.

The zeolite membrane obtained by the production method of the present invention preferably has as few holes as possible other than the holes in the zeolite crystal. Reducing such holes outside the crystal is referred to as densification treatment. Since it is better to have as few holes outside the crystal as possible, it is preferable to perform this densification treatment on the zeolite membrane. Of course, if a dense film is formed without performing the densification processing, it is not necessary to perform the densification processing. As a method of the densification treatment, a known method can be used, but as a specific example, it does not enter pores of zeolite, but enters other pores, for example, pores formed at a grain boundary between crystals. A method of impregnating with an organic material having a desired size, followed by baking in a gas substantially free of oxygen such as nitrogen gas, and carbonizing to fill the pores, is not limited to this method. A polymer compound such as silicone or a silane coupling agent such as alkylalkoxysilane or alkoxysilane may be embedded in the pores formed at the grain boundaries.

The method for producing a zeolite membrane according to the present invention is a novel and industrially useful method. However, the zeolite thus produced also provides a novel zeolite membrane in terms of orientation.
The method for producing a zeolite membrane of the present invention comprises A-type, X-type, and Y-type.
Can be applied to all types of zeolite membranes such as zeolite, mordenite, β and MFI types.
I-type zeolite is easily formed. MFI made by the method of the present invention
Type zeolite membrane (after 550 ° C calcination), using CuKα as X-ray source (wavelength = 1.54 angstroms), fixing the incident angle to 3 degrees, X-ray diffraction with parallel optics at a scan speed of 2θ 4 degrees / min. When measured, the diffraction pattern
The peak intensity of the maximum peak within θ = 7.3 to 8.2 degrees is a, 2θ
= 8.5 to 9.1 degrees, the maximum peak intensity is b, 2θ = 13.0 to
When the maximum peak intensity within 14.2 degrees is c, the following 2
Satisfy the formula. (1) a / b = 0.3 to 1.5 (2) b / c> 4.4 As a result of the permeation experiment, it was found that the MFI-type zeolite membrane having this orientation exhibits excellent performance in terms of permeability and permeation selectivity. all right.

Although the reason is not clear at present,
It can be considered as follows. The maximum peak at 8.5 to 9.1 degrees represents the peak of the (200) plane or the (020) plane. MF
Type I zeolite has pore entrances on the (100) and (010) planes, and has no pore entrance on the (001) plane. Therefore, the larger the value of the maximum peak intensity b within the range of 2θ = 8.5 to 9.1 degrees, the larger the number of pore entrances on the membrane surface, and the better the transmittance. 2θ = 7.3-8.2
The maximum peak indicates the peak of the (-101) plane or the (011) plane, and the value of a / b can indicate how much the zeolite pore entrance is exposed on the membrane surface. In the powder X-ray diffraction diagram of a normal MFI-type zeolite,
The value of a / b is about 1.9, and the fact that a / b shows a smaller value than this indicates that an excellent orientation is exhibited in terms of transmittance. Further, the peak at 2θ = 13.0 to 14.2 degrees is (002)
Planes or (012) plane peaks, that is, that these peaks are large means that many surfaces without pore entrances appear on the film surface, which is not preferable as a permeable film. . Therefore, the larger b / c is, the more the pore entrance is exposed on the membrane surface, which is preferable as a permeable membrane. In the powder X-ray diffractogram of the ordinary MFI-type zeolite, b / c is about 4.3, and having a b / c value larger than this value indicates that it has a preferred orientation. However, if the orientation is too complete, there is no escape for stress due to heat history, etc.
It is susceptible to temperature changes and is expected to crack during firing, and it is better that the orientation is slightly incomplete. Therefore, b / c
Is preferably about 4.4 to 13, more preferably 5 to 11. Similar considerations can be made for a / b. A value of 1.5 or less is preferable for permeability, but it is considered that a value of 0.3 or more is better from the viewpoint of the strength of the film against a temperature change. Preferably, a / b is between 0.5 and 1.3.

Accordingly, the zeolite membrane has a good balance of permeability, heat resistance and strength, and it is useful to use the zeolite membrane as a separation membrane. Methods include contacting a gas or liquid mixture of molecules, permeating at least one molecule, and separating at least one molecule.

The MFI type zeolite membrane of the present invention has a silica /
When the alumina ratio is increased, it becomes largely hydrophobic, and is very useful for separating ethanol from a dilute ethanol aqueous solution and for permeating and separating gas in the presence of vapors of polar molecules such as water vapor and ethylene glycol vapor. By utilizing such properties, it can be effectively used as a hydrogen permeable membrane for an electrolytic capacitor or a hydrogen permeable membrane for a fuel cell.

An example of use as a hydrogen permeable membrane for an electrolytic capacitor will be described with reference to the drawings. FIG.
FIG. 9 is a schematic cross-sectional view showing an example of an electrolytic capacitor using the zeolite membrane of the present invention, and FIG. 9 is a schematic plan view of a sealing plug portion of the electrolytic capacitor in FIG. 8 as viewed from above.

That is, in FIG. 8, an electrolytic solution is impregnated into an electrolytic capacitor element 2 wound with kraft paper interposed between an anode foil and a cathode foil, and the anode terminal 3 and the cathode terminal 4 are passed through the through holes of the sealing plug 1. The aluminum container 5
It is stored in. FIG. 9 is a view showing a state in which the sealing plug 1 of FIG. 8 is viewed from above, and shows the zeolite membrane 6 of the present invention.
Can be installed, for example, at position 6 in FIG. 9 with an adhesive or the like.

The present invention will be described in more detail by the following examples.

[0041]

EXAMPLES Example 1 (Synthesis of Seed Crystal) 20 g of a 20-25% aqueous solution of tetrapropylammonium hydroxide (TPAOH) (Tokyo Kasei Co., Ltd. 2
(0-25% aqueous solution), 0.28 g of NaOH (Katayama Chemical Reagent First Class) was added and stirred. 5 g of fumed silica (Aldrich) was added thereto and heated to 80 ° C. to obtain a transparent aqueous solution. This was put in an autoclave of a Teflon line and heated at 125 ° C. for 8 hours, whereby silicalite fine particles (about 80 nm) were obtained. Diluted with water to 8% colloid.

Example 2 (Coating of seed crystal on support) 8% silicalite colloid 0.1% obtained in Example 1
g is a porous support of α-alumina having a square of 1.4 cm on a side and a thickness of 3 mm (manufactured by Nippon Insulators Co., Ltd .: coated on one side with alumina fine particles for a thickness of about 50 μm, average pore diameter is 0.1 μm After coating onto the surface treated with the fine particles of alumina as uniformly as possible, the mixture was dried and baked at 550 ° C. for 3 hours.

Example 3 (Preparation of Silicalite Membrane by the Method of the Present Invention) The surface of the support obtained in Example 2 coated with silicalite fine particles was coated with LUDOX HS-30 and a 1: 1 aqueous solution of 10% TPAOH aqueous solution. After dropping 0.1 g of the mixed sol and drying at room temperature for 1 hour, 0.5 g of water was put into a 50 ml autoclave and heated at 175 ° C. for 5 days under steam pressure. 550 of the film sample
Calcination was performed at 2 ° C for 2 hours. The heating rate during firing was 0.6 ° C /
min., and the temperature drop rate was 1.2 ° C./min. It was confirmed by X-ray diffraction and an electron microscope that a silicalite thin film was formed on the support. The membrane pressure of the zeolite membrane was about 2 μm. The X-ray diffraction pattern is shown in FIG. In the X-ray diffraction measurement, CuKα was used as the X-ray source (wavelength = 1.54 angstroms), the incident angle was fixed at 3 degrees, and the scan speed was 2θ 4.
X-ray diffraction measurement was performed with a parallel optical system at a degree / minute. From FIG. 1, 2
The peak intensity of the maximum peak within θ = 7.3 to 8.2 degrees is a, 2θ
= 8.5 to 9.1 degrees, the maximum peak intensity is b, 2θ = 13.0 to
When the maximum peak intensity within 14.2 degrees is c, a / b = 0.
73 b / c was 5.88.

Comparative Example 1 (Production of silicalite membrane by hydrothermal synthesis) The support obtained in Example 2 was treated with 40 SiO ₂ (Aldrich).
Fumed silica): 12 TPAOH (tetrapropylammonium hydroxide): 16800 H ₂ O in placed in gel composition, was heated for 24 hours at 130 ° C. in an autoclave. It was confirmed by X-ray diffraction and an electron microscope that an approximately 2 μm thin film of silicalite was formed on the support.
The film sample was fired at 550 ° C. for 2 hours. The heating rate during firing was 0.6 ° C./min, and the cooling rate was 1.2 ° C./min. As a result of X-ray diffraction and electron microscope observation, it was confirmed that a silicalite thin film was formed on the support. The film was found to have a thickness of about 2 microns. The X-ray diffraction pattern is shown in FIG. X-ray diffraction measurement
Using CuKα (wavelength = 1.54 angstroms), the incident angle was fixed at 3 °, and the X-ray diffraction measurement was performed with a parallel optical system at a scan speed of 2θ4 ° / min. From FIG. 1, 2θ = 7.3 to 8.2
A / b = 1.96, where a is the peak intensity of the maximum peak in degrees and 2 is the maximum peak intensity in 2θ = 8.5-9.1 degrees and b is the maximum peak intensity in 2θ = 13.0-14.2 degrees. b / c = 2.43
Met.

Example 4 (Hydrogen / steam separation test) The silicalite membranes prepared in Example 3 and Comparative Example 1 were sandwiched between glass tubes having an inner diameter of 1 cmφ and adhered with a two-liquid equivalent type epoxy resin adhesive. At the same time, the periphery was covered with the adhesive as shown in FIG. 3 to form a transmission cell having a transmission area of 0.785 cm ² . This permeation cell is installed in a permeation apparatus as shown in FIG. 4, and a gas of 2 atm containing saturated vapor pressure water vapor and hydrogen at room temperature is brought into contact with the permeable membrane of the present invention, and the other side of the membrane is brought to atmospheric pressure. In this state, the gas was permeated by a differential pressure of about 1 atm, and the supply gas and the permeated gas, water and hydrogen, were analyzed by gas chromatography. The amount of hydrogen in the supply gas analyzed by gas chromatography was A, the amount of water in the gas was B, the amount of hydrogen in the permeated gas was C, and the amount of water was D, and CB / AD was determined. The hydrogen permeation rate was measured with a soap film flow meter.

The silicalite membrane of Comparative Example 1 had a CB / AD of 1.9 and a hydrogen permeation rate of 2.0 × 10 ⁻⁷ mol / (s · m ² · Pa). On the other hand, the silicalite membrane of Example 3 had a hydrogen permeation rate of 5.0 × 10 ⁻⁷ mol / (s · m ² · Pa) at CB / AD = 3.6, and a higher permeation rate than the comparative example. It was also found that the selective separation coefficient was high. This is considered to be due to the special orientation.

Example 5 0.1 g of a mixture of 1 g of LUDOX HS-30 and a 10% TPAOH aqueous solution was dropped as uniformly as possible onto the surface of the support obtained in Example 2 on which the silicalite fine particles were coated, and then cooled to room temperature. After drying for 1 hour, 0.5 g of water was put into a 50 ml autoclave and heated at 150 ° C. for 5 days under steam pressure. The film sample was fired at 550 ° C. for 2 hours. The heating rate during firing was 0.6 ° C./min, and the cooling rate was 1.2 ° C./min. The fact that a thin film of silicalite is formed on the support is indicated by X
Confirmed by line diffraction and electron microscope. The X-ray diffraction pattern is shown in FIG. In the X-ray diffraction measurement, CuKα was used as the X-ray source (wavelength = 1.54 angstroms), the incident angle was fixed at 3 °, and the X-ray diffraction measurement was performed with a parallel optical system at a scan speed of 2θ4 ° / min. From FIG. 5, the peak intensity of the maximum peak in 2θ = 7.3 to 8.2 degrees is a, the maximum peak intensity in 2θ = 8.5 to 9.1 degrees is b, and the maximum peak intensity in 2θ = 13.0 to 14.2 degrees is c. Then, a / b = 1.16 b / c = 5.38.

Comparative Example 2 The same experiment as in Example 5 was performed using a support not coated with a seed crystal. The X-ray diffraction pattern was as shown in FIG. 6, indicating that almost no zeolite membrane was formed. It was proved that the crystallization rate could be increased by adding the seed crystal.

Example 6 Porous α-alumina support having a square shape of 1.4 cm on a side and a thickness of 3 mm (manufactured by Nippon Insulator: alumina fine particles having a thickness of about 5
0 μm coated, average pore size 0.1
μm) on the surface treated with alumina fine particles, LUDOX HS
-30 was diluted twice with water and dip-coated three times, and then a mixed sol of HS-30: 20% TPAOH aqueous solution: 8% silicalite colloid (Example 1) = 1: 1: 2 was dipped. Coated. Then, after vacuum drying at room temperature, 50ml
Pour 0.5 g of water into the autoclave and add 15 g
Heat at 0 ° C. for 5 days. The film sample was fired at 550 ° C. for 2 hours. The heating rate during firing was 0.6 ° C./min, and the cooling rate was 1.2 ° C./min. It was confirmed by X-ray diffraction and an electron microscope that a silicalite thin film was formed on the support. The X-ray diffraction pattern is shown in FIG. In the X-ray diffraction measurement, CuKα was used as the X-ray source (wavelength = 1.54 angstroms), the incident angle was fixed at 3 degrees, and the scan speed was 2θ.
X-ray diffraction measurement was performed with a parallel optical system at 4 degrees / minute. 2θ = 7.3
The peak intensity of the maximum peak within ~ 8.2 degrees is a, 2θ = 8.5 ~
A / b = 0.68 b / c, where b is the maximum peak intensity within 9.1 degrees and c is the maximum peak intensity within 2θ = 13.0 to 14.2 degrees.
= 8.33.

[0050]

The method for producing a zeolite membrane according to the present invention has the effects of reducing the waste liquid and shortening the crystallization time. The silicalite membrane having a special orientation produced by this method has a high permeability. The selectivity can be increased while keeping the amount large.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction diagram of a zeolite membrane obtained by the method of Example 3.

FIG. 2 is an X-ray diffraction diagram of a zeolite membrane obtained by the method of Comparative Example 1.

FIG. 3 is a cell for measuring transmission of a permeable membrane.

FIG. 4 is a diagram of an apparatus for examining the permeation characteristics of hydrogen / water vapor of a permeable membrane.

FIG. 5 is an X-ray diffraction diagram of a zeolite membrane obtained by the method of Example 5.

6 is an X-ray diffraction diagram of a zeolite membrane obtained by the method of Comparative Example 2. FIG.

FIG. 7 is an X-ray diffraction diagram of a zeolite membrane obtained by the method of Example 6.

FIG. 8 is a schematic cross-sectional view showing one example of an electrolytic capacitor using the zeolite membrane of the present invention.

FIG. 9 is a schematic plan view of the sealing plug portion of the electrolytic capacitor in FIG. 1 as viewed from above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sealing stopper 2 ... Electrolytic capacitor element 3 ... Anode terminal 4 ... Cathode terminal 5 ... Container 6 ... Zeolite membrane

Claims (5)

[Claims] 1. A method for producing a zeolite membrane, comprising treating a membrane containing a zeolite seed crystal and silica with steam. 2. A method wherein a zeolite seed crystal is brought into contact with a porous support in advance, and then coated with a solution, slurry or colloid containing silica to form a film and treated with steam. The method for producing a zeolite membrane according to claim 1. 3. An X-ray diffraction measurement using a parallel optical system with CuKα as an X-ray source (wavelength = 1.54 angstroms), an incident angle fixed at 3 ° and a scan speed of 2θ4 ° / min.
In the diffraction pattern, the peak intensity of the maximum peak within 2θ = 7.3 to 8.2 degrees is a, the maximum peak intensity within 2θ = 8.5 to 9.1 degrees is b, and the maximum peak intensity within 2θ = 13.0 to 14.2 degrees is c. Wherein the following formulas (1) and (2) are satisfied. (1) a / b = 0.3 to 1.5 (2) b / c> 4.4 4. The MFI-type zeolite membrane according to claim 3, wherein the MFI-type zeolite membrane is formed on a support and has a thickness of 3 μm or less on the surface of the support. 5. An MFI-type zeolite membrane according to claim 3 or 4 is contacted with a gas or liquid mixture comprising at least two kinds of molecules, and at least one kind of molecules is permeated to separate at least one kind of molecules. Method.