JPH1036113A - Zeolite membrane, its production and separation of gas mixture by using zeolite membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a zeolite membrane effective for selective separation of a gas from a gas mixture by making zeolite have a specific structure by a specific method. SOLUTION: This zeolite membrane comprises a surface layer of polycrystalline zeolite formed on a porous substrate, and an anchor layer of polycrystalline zeolite which is formed in pores in the near-surface layer of the porous substrate under the surface layer. This zeolite membrane is produced through processes of making zeolite particulates adhere to the porous outside surface of the porous substrate, and forming a zeolite membrane in the substrate surface. Preferably the zeolite particulates to adhere to the membrane are mainly composed of X-type zeolite, and the zeolite membrane is of Y type. This membrane is particularly effective for separation of carbon dioxide from combustion exhaust gas (a mixed gas of carbon dioxide and gaseous nitrogen).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a zeolite membrane, and more particularly, to a zeolite membrane, a method for producing the same, and a method for separating a mixed gas using the zeolite membrane.

[0002]

2. Description of the Related Art In recent years, various techniques for reducing atmospheric carbon dioxide (CO ₂ ) have been developed as measures for preventing global warming. As one of such technologies, a method of separating and recovering CO ₂ from flue gas discharged from a thermal power plant or the like has been studied. The proportion of energy supply from nuclear, hydro, geothermal, etc. will increase in the future, but oil, coal and natural gas combustion and power generation will still account for a large proportion,
O ₂ recovery and emission control are extremely effective in preventing global warming.

[0003] Among various CO ₂ separation and recovery methods, the membrane separation method has high energy efficiency and is expected as a promising process. Inorganic materials such as zeolites and ceramics are considered to have better heat resistance and corrosion resistance than polymer films, but no practical inorganic material films have been obtained so far. If a permeable membrane rich in CO ₂ selectivity can be obtained from an inorganic material, the heat loss from high-temperature combustion exhaust gas can be reduced,
With high energy efficiency, it is possible to separate the CO ₂ directly, the benefit is immense.

[0004]

As a typical material exhibiting unique adsorption characteristics and excellent molecular sieve action, natural or artificial synthetic zeolites are known. Synthetic zeolites are obtained as crystal powders having a particle size of several microns or less, and become granular in the order of several millimeters. In addition to being used industrially, attempts have been made to experimentally form membranes. A type, ZSM-5 type, mordenite type,
There are reports on film formation of ferrierite type, Y type and the like, and for ZSM-5 type, separation performance evaluation of mixed gas is also performed.

[0007] Geus et al. Have reported that a ZSM- containing a large amount of Si component on a porous stainless steel support substrate by a hydrothermal synthesis method.
Regarding the type 5 (silicalite) membrane, the permeation characteristics of methane, n-butane and iso-butane are studied. The transmission coefficient ratio α (n-butane / iso-butane) of iso-butane to iso-butane using a single component gas is 6 at 25 ° C.
0 or more, and C utilizing the molecular sieve property of zeolite
It has been clarified that isomer separation of four components is possible.

Also, Jia et al. Reported that a polycrystalline silicalite membrane on the inner surface of a porous α-alumina support
Butane / iso-butane) was about 3 at 25 ° C., which was not enough. Yan et al. Reported that ZS
When an M-5 membrane was produced, the transmission coefficient ratio α (n-butane / iso-butane) increased with an increase in the permeation temperature,
At 185 ° C., it was 31.1. Transmission coefficient ratio α (CO
₂ / N ₂ ) was 2.8 at 30 ° C. Kusakabe
Produced silicalite films on the inner surface and outer surface of the porous α-alumina tube, and obtained a high value of α (n-butane / iso-butane) of 10 to 50 at 30 to 100 ° C. However, α (CO ₂ / N ₂ ) was at most about 5.

As described above, in the ZSM-5 type, since the intrinsic pore diameter is 0.5 to 0.6 nm, n-butane (0.43 nm) whose dynamic molecular diameter is close to the pore diameter and iso-butane (0.5 nm). On the other hand, for CO ₂ having a dynamic molecular diameter of 0.33 nm, separation by molecular sieving was not effective, but separation by adsorption affinity was also insufficient. Here, the Y-type zeolite is a zeolite having the same crystal structure as faujasite, which is a natural zeolite, and its void opening has an oxygen content of 12%.
It has a membered ring structure, the pore diameter is about 0.75 nm, and molecules of about 0.95 nm can pass through the pores by molecular vibration. Further, it is more hydrophilic than silicalite and is excellent in CO ₂ adsorption. further,
Although a Y-type zeolite membrane was formed on a porous alumina substrate, there is no report on gas separation characteristics.

Accordingly, the present invention focuses on the Y-type zeolite membrane, and describes a Y-type zeolite membrane effective for selective separation of a mixed gas, a method for producing the same, and a method for selective gas separation using the Y-type zeolite membrane. The task is to provide.

[0009]

Means for Solving the Problems In order to solve the above problems, the present inventors have completed the following invention. That is, the first invention is directed to a polycrystalline surface layer formed on the surface of the porous substrate, and a zeolite existing in a pore below the surface layer and on the surface of the porous substrate. A zeolite membrane comprising a polycrystalline anchor portion. According to this invention, since the zeolite polycrystal is present in the pores on the surface side of the porous substrate under the zeolite polycrystalline membrane, the surface of the zeolite has Fully covered with a polycrystalline layer of As a result, pores having a specific diameter possessed by the zeolite are continuously formed on the surface of the porous substrate, and this membrane allows sufficient adsorption and separation based on the molecular sieving effect of the zeolite, or sufficient catalytic activity. It is exhibited in.

[0010] In the present invention, the zeolite in the surface layer is preferably a Y-type zeolite having excellent characteristics of separating CO ₂ from a mixture.

The second invention comprises a step of adhering zeolite particles on a surface including pores on the surface of a porous substrate, and a step of synthesizing a zeolite membrane on the surface of the substrate. This is a method for producing a characteristic zeolite membrane. According to the present invention, zeolite particles are adhered on the surface including the pores on the porous substrate surface side, and the zeolite becomes a seed crystal when a zeolite membrane is synthesized on the substrate surface. As a result, the seed crystal is densely present on the surface of the porous substrate. According to the presence of such seed crystals, polycrystals are deposited on the pores on the surface of the porous substrate and on the surface of the porous substrate. A zeolite membrane having a surface layer portion and a polycrystalline anchor portion of zeolite existing in a hole below the surface layer portion and on the surface side of the porous substrate is formed.

In the present invention, the zeolite particles preferably contain an X-type zeolite as a main component, and the zeolite membrane is preferably a Y-type. According to this aspect, X
Type zeolite has the same faujasite type crystal structure as Y type zeolite, and is preferable as a seed crystal for the synthesis of Y type zeolite.

According to a third aspect of the present invention, there is provided a polycrystalline zeolite surface layer formed on the surface of a porous substrate, and a surface layer below the surface layer and present in a pore on the surface side of the porous substrate. Separating a gas of at least one component from a mixture of gases using a zeolite membrane having a polycrystalline zeolite anchor. According to this method, since the surface of the porous substrate is sufficiently covered with the zeolite membrane, the gas of one component is separated from the gas mixture by a molecular sieve action and an adsorption action based on the crystal structure of zeolite. be able to.

In the present invention, the zeolite in the surface layer is a Y-type zeolite, and in a preferred embodiment, carbon dioxide is separated from a gas mixture containing carbon dioxide and nitrogen in the presence of water. . According to this embodiment, carbon dioxide can be selectively separated from nitrogen by the Y-type zeolite in the presence of water.

[0015]

Embodiments of the present invention will be described below in detail. (Porous substrate) As the porous substrate of the present invention, various known porous substrates can be used. An appropriate porous substrate is selected according to the production environment such as the synthesis temperature of the zeolite membrane, the use temperature of the zeolite membrane, and other usage conditions. Preferably, it is a ceramic porous substrate from the viewpoint of heat resistance, acid resistance and the like, and more preferably, α-alumina.

(Zeolite) As the zeolite constituting the zeolite membrane of the present invention, a currently known synthetic zeolite can be used. Specifically, A type, X type, Y
Type, ZSM-5 type, silicalite and the like. In the zeolite membrane of the present invention, at least the zeolite in the membrane portion is preferably an X-type or Y-type zeolite. This is because these zeolites are more hydrophilic than silicalite and have carbon dioxide adsorption. As such a zeolite,
More preferably, it is a Y-type zeolite. The Y-type zeolite has a particularly high CO ₂ permeability coefficient ratio α (CO 2
₂ / N ₂ ).

(Method for Manufacturing Zeolite Membrane) Hydrothermal synthesis is mainly used for the synthesis of zeolite membrane. Upon hydrothermal synthesis, select various starting materials and their amounts,
Various zeolites are synthesized by selecting hydrothermal conditions. In the present invention, prior to the synthesis of the zeolite membrane on the surface of the porous substrate, zeolite particles are attached to the surface including the pores on the surface of the porous substrate. In order to adhere the zeolite particles in this manner, for example, the surface of the porous substrate is polished in a dry manner using the zeolite particles. Since zeolite particles are a brittle material compared to a ceramic porous substrate, they are ground during polishing and adhere in a form to close pores on the substrate surface. As the zeolite particles to be attached,
It is preferable to use X-type zeolite as a main component.

When the zeolite particles are attached to the surface of the porous substrate in this manner and the zeolite membrane is hydrothermally synthesized, the zeolite particles serving as seed crystals for synthesizing a zeolite polycrystalline film are densely packed. It will be on the surface of the porous substrate. As a result, the synthesized polycrystal is also densely synthesized on the substrate according to the state of existence of these seed crystals. That is, the seed crystal is not only densely present on the surface of the base material, but also because the seed crystal is present even inside the pores, so that the surface of the porous base material is dense in the planar direction and the vertical direction. A polycrystalline film (surface layer portion and anchor portion) is formed integrally. For this reason, pinholes and crystal gaps are not easily formed, and a state is formed in which the surface of the porous substrate is covered with a continuous polycrystalline film.

(Selective Separation Method of Component Gas from Mixed Gas by Zeolite Membrane) According to the method for producing a zeolite membrane of the present invention, the surface layer of the polycrystalline zeolite and the surface of the porous base material below it A zeolite polycrystalline film having a zeolite polycrystalline anchor portion also present in the side hole can be obtained. A state in which the surface of the base material is densely covered with the polycrystalline layer of zeolite is formed. Therefore,
The zeolite polycrystalline film obtained by the method of the present invention,
It is thought that pinholes, cracks, and crystal gaps are significantly reduced, and the excellent molecular sieving effect of zeolite,
It is also possible to selectively separate gases from a mixture of various gases by the adsorption action. In particular, in the separation using a Y-type zeolite membrane in the presence of water, it is conceivable that the pores (about 0.75 nm) of the zeolite membrane are apparently small due to the adsorption of water. Thereby, in contact with the mixture of carbon dioxide and nitrogen gas, the permeation of nitrogen gas (N ₂ : dynamic molecular diameter of about 0.4 nm) is selectively inhibited, and as a result, carbon dioxide is selectively It is considered that they are separated and transmitted. Furthermore, it is conceivable that the affinity of water adsorbed in the pores of zeolite for carbon dioxide may enhance the separation from nitrogen gas. Further, in contact between the mixture of carbon dioxide and methane gas and the Y-type zeolite membrane in the presence of water, the permeation of methane gas is selectively inhibited, and as a result, carbon dioxide is separated and permeated. The presence of water refers to a state where water is adsorbed on the zeolite membrane. Specifically, the state includes a state in which the zeolite membrane itself contains moisture in advance, and a state in which moisture is supplied to the zeolite membrane by the moisture present in the mixture of the gases to be separated.

In the method for separating a gas mixture according to the present invention, since the combustion exhaust gas (mixed gas of carbon dioxide and nitrogen gas) contains water, the present invention provides a method for separating Y in the presence of water according to the present invention.
The gas separation method using a zeolite membrane is particularly effective for separating carbon dioxide from combustion exhaust gas. In addition, recovery of methane gas by separation of carbon dioxide from landfill gas (mixed gas of carbon dioxide and methane gas) generated in lakes and marshes, removal of carbon dioxide generated in fresh food storage, and converter gas (blast furnace etc.) It can also be applied to the recovery of carbon dioxide from gas generated when carbon in pig iron is removed as carbon dioxide by blowing oxygen into the inside.

[0021]

According to the first invention, a zeolite membrane having a polycrystalline zeolite surface layer portion and a polycrystalline zeolite linker portion has pores having a diameter inherent to the zeolite formed continuously. This membrane allows the composition to be adsorbed and separated from the mixture by an efficient molecular sieving effect. According to the second invention, the surface portion of the polycrystalline zeolite formed on the surface of the porous base material, and the polycrystal existing in the pores below the surface layer portion and on the surface side of the porous base material A zeolite membrane provided with a zeolite linker portion can be produced. According to the third aspect, the component gas can be efficiently separated from the gas mixture by the zeolite membrane.

[0022]

EXAMPLE In this example, the porous base material was porous α.
-Alumina tube (manufactured by NOK Co., Ltd., inner diameter 1.0 mm, outer diameter 2.8 mm, average pore diameter 150 nm) and porous α-alumina flat plate (manufactured by Nippon Special Ceramics Co., Ltd., size 10 mm ×
10 mm and a pore diameter of 1 to 3 μm). Next, using about 2 g of commercially available zeolite powder (F-9, manufactured by Tosoh Corporation, 200 mesh (particle size: 74 to 88 μm), main component Na-X type zeolite), the outer surface of the alumina tube and the flat plate were used. By polishing one surface, zeolite powder was rubbed on these surfaces. As a result of the surface treatment of the support tube and the flat plate, particles constituting the zeolite powder were ground into fine powder, and the fine powder was uniformly embedded so as to close pores on the surface of the support tube. The comparative example was an alumina tube which was not polished with zeolite powder and had no powder particles attached to the surface, using the same alumina tube as the α-alumina tube of the example.

Examples and comparative examples are summarized in the following table.

[Table 1]

Next, with respect to the alumina tubes and flat plates of Examples 1, 2 and 3, and the alumina tube of Comparative Example 1, synthesis of a Y-type zeolite membrane was attempted by a hydrothermal synthesis method. When synthesizing a Y-type zeolite membrane, water glass (17 to
_{19%, Na 2 O, 35~38} % SiO 2), using sodium aluminate as the aluminum source. In preparing the raw material solution for hydrothermal synthesis, water glass was dissolved in water with stirring, sodium aluminate was added, and finally sodium hydroxide was added. This liquid was aged for 20 hours with stirring. The molar ratio of the components in the raw material solution for hydrothermal synthesis obtained by aging is as follows: Al ₂ O ₃ : SiO ₂ : Na ₂ O: H ₂ O = 1: 10:
14: 798.

Next, the alumina tubes (length 3 cm) of Examples 1 and 2 vertically fixed with a Teflon holder were placed in a Teflon-made autoclave (60 ml in internal volume) containing 30 ml of the raw material solution, and airtight. State. This autoclave was placed in an electric furnace maintained at 90 ° C. for 6 hours.
Hydrothermal synthesis was carried out for 12 hours and 24 hours. Similarly, hydrothermal synthesis was performed on the flat plate of the example and the alumina tube of the comparative example. The alumina tube and flat plate of these examples and the alumina tube of the comparative example were taken out of the autoclave after the autoclave was taken out of the electric furnace and allowed to stand for one day. Then, after sufficiently washing with water, it was dried in a clean bench.

As described above, the surface morphology of the alumina tube and the alumina plate after the hydrothermal synthesis step was observed with a scanning electron microscope. The crystallinity was evaluated by X-ray diffraction. In addition, the thermogravimetric analysis of the zeolite was performed with a thermobalance.
Further, with respect to the α-alumina tube of Example 1, various gas permeation experiments were performed.

(Surface Form of Zeolite Membrane) Examples 1 and 2 (alumina tube) and Comparative Example 1 (alumina tube)
The surface and cross-section of the tube after hydrothermal synthesis were compared visually and with an electron microscope. FIG. 1 shows an electron micrograph of the surface of the alumina tube of Example 1 after the hydrothermal synthesis for 12 hours, and FIG. 2 shows an electron micrograph of a cross section of the alumina tube. Also,
FIG. 3 shows an electron micrograph of the surface of the alumina tube of Example 1 after the hydrothermal synthesis for 24 hours, and FIG. 4 shows an electron micrograph of the cross section thereof.

As is clear from FIGS. 1 and 2, the surface of the alumina tube of Example 1 after hydrothermal synthesis for 12 hours is covered with a continuous polycrystalline film, and the thickness of this film is 1-2 μm. Met. Further, as is clear from FIGS. 3 and 4, in the alumina tube after the hydrothermal synthesis for 24 hours, the thickness of the continuous polycrystalline film was further 5 to 6 μm, and the surface of the continuous film was partially crystallized. Fine particles were precipitated. Further, FIG.
And from the cross section of FIG. 4, the same type of crystalline fine particles as the fine particles on the continuous film and the surface thereof were also precipitated in the pores of the alumina tube. After the hydrothermal synthesis for 24 hours, the precipitation range of such fine particles is about 15 μm from the surface of the alumina tube.
Was in the range. Also, the alumina tube of Example 2 and the alumina flat plate of Example 3 were observed in the same manner. A crystalline film was formed, and crystalline fine particles were deposited on the surface.

On the other hand, after the hydrothermal synthesis for 24 hours, only fine crystalline particles were observed on the surface of the alumina tube of the comparative example, and a continuous film could not be obtained. Was.

(Crystallinity of Zeolite Membrane) Examples 1 and 2
The surface of the alumina tube of Example 2 and the surface of the alumina plate of Example 2
The crystal structure was identified by line diffraction. From this result, it was found that the continuous polycrystalline film formed on any surface and the fine particles on the surface were Y-type zeolite. FIG. 5 shows the results of a test performed on the surface of the alumina flat plate of Example 2. As shown in FIG. 5A, the characteristic peak of the Y-type zeolite crystal was not detected in the X-ray diffraction after the hydrothermal reaction for 6 hours. As shown in FIG. 5 (b), after the hydrothermal reaction for 12 hours, a diffraction peak indicating the formation of Y-type zeolite (the peak of the diffraction pattern is indicated by a mark ●) is detected,
After 24 hours (see FIG. 5 (c)), the peak of the Y-type zeolite further increased. In these X-ray diffraction spectra, no peaks other than those of α-alumina and Y-type zeolite were detected. That is, the zeolite membrane formed on the alumina flat plate of Example 2 was a membrane composed of crystalline Y-type zeolite. Note that the white fine particles by-produced on the film surface were also crystalline Y-type zeolites.

(Moisture Content of Zeolite Membrane) The water of the Y-type zeolite membrane formed on the surface of the alumina tube of Example 1 was used to collect fine particles of Y-type zeolite formed on the surface, It measured from the weight change at the time of temperature fall.
The measurement was performed in dry nitrogen and in air containing moisture, and the temperature was raised and lowered at 5 ° C. per minute. FIG. 6 shows the results. From this figure, the dehydration from the Y-type zeolite progressed as the temperature rose, and the equilibrium was reached at about 320 ° C. in a nitrogen stream and at about 420 ° C. in air. In the air, when the temperature was lowered, water was absorbed and the weight recovered. From the difference in weight between the air and the nitrogen after the temperature was lowered, it was found that the Y-type zeolite left in the air at room temperature contained about 20 wt% of water.

(Gas Permeability of Zeolite Membrane) The gas permeability of this zeolite membrane was determined by using He, CO ₂ , N ₂ , CH ₄ ,
Various single component gases of C ₂ H ₆ and SF ₆ and CO ₂ -N ₂
Measurements were made of CO ₂ N ₂ and CH ₄ , which are composition gases in a mixed gas and a CO ₂ —CH ₄ mixed gas. The transmission temperatures were 30 ° C, 80 ° C, and 130 ° C. The measurement was performed based on the gas permeability measurement system illustrated in FIG. This system consists of a gas cylinder 1 filled with various gases.
0 and the alumina tube of Example 1 attached to a part of a stainless steel tube 16 that penetrates a quartz tube 14 heated to a predetermined permeation temperature by an electric furnace 12 (stored in room temperature air and containing moisture). (In a state) 18 and a gas chromatograph device 20. In this system, various gases filled in the gas cylinder 10 are supplied into the quartz tube 14 and come into contact with the outer surface of the alumina tube 18 attached to the stainless steel tube 16. The gas that has passed through the outer surface of the alumina tube 18 and passed through the stainless steel tube 16 is TCD
The gas is introduced into a gas chromatograph device 20 having a detector and is detected. As shown in FIG. 8, the alumina tube 18 is connected to a substantially central portion of the stainless steel tube 16 penetrating the quartz tube 14 in a hermetically sealed state sealed with an epoxy resin. 16 and communicates with the inside.

The transmissivity of various single component gases at the permeation temperatures of 30 ° C., 80 ° C., and 130 ° C. is plotted on the abscissa with the dynamic molecular diameter (nm) of the permeated molecule as the transmissivity (mol · m ⁻² · s ⁻¹ ·
FIG. 9 shows a graph created with Pa ^-1 ) as the vertical axis.
In any gas, as the permeation temperature increases,
Although the transmittance was improved in each case, the transmittance of the gas did not depend on the size of the permeable molecule. CO ₂ , C
The permeability of adsorbable gas such as H ₄ and C ₂ H ₆ is He or N
_It was big compared to ₂ . Further, the transmittance of each gas at a permeation temperature of 130 ° C. was plotted against the reciprocal of the square root of the molecular weight of the permeated molecule, but no linearity indicating Knudsen diffusion was obtained. From these results, it was found that the zeolite membrane synthesized on the surface of the alumina tube of Example 1 had sufficiently small leakage of gas molecules from pinholes and crystal gaps.

FIG. 10 shows the transmittance of the first embodiment.
From the measurement results, the transmission temperature is plotted on the horizontal axis, and CO_Two, N_Two,
CH_FourIn single-component gases and their mixtures
A graph showing the transmittance of these component gases on the vertical axis is shown.
FIG. 11 shows CO 2 in Example 2._Two, N_Twoof
Single component gas, CO_Two-N_TwoEach component gas in the mixed system of
From the transmittance measurement results for
FIG. From these figures, it can be seen that at a permeation temperature of 30 ° C.
CO_TwoThe transmittance of (single component) is 7 to 11 × 10^-8In
And CO in various mixed systems_TwoAlso has a transmittance of 10
~ 11 × 10^-8Met. That is, at a permeation temperature of 30 ° C.
Is a single component system or a mixed system (N_TwoOr CH_Four)smell
Even CO_TwoHad little change in transmittance. Exchange
In other words, N_TwoAnd CH_FourHas a transmittance of CO_TwoMix
And this decreasing trend is remarkable at low temperatures.
Was. This is because on the low temperature side, CO _TwoSucking
This is considered to be due to an increase in the amount of coating.

FIG. 12 shows the transmission coefficient ratio α in the single-component gas system and the mixed system in the alumina tubes of Examples 1 and 2.
Is shown. The permeation coefficient ratio α (CO ₂ / N ₂ ) of CO _{2 to} N ₂ in the single component gas increased with the permeation temperature. At a permeation temperature of 30 ° C., α was about 4-5. On the other hand, in the CO ₂ -N ₂ mixed system, α (CO ₂ / N ₂ ) increases with the permeation temperature because the nitrogen permeability is reduced in the low temperature region (see FIGS. 10 and 11). Thus, the temperature reached 20 to 100 near room temperature (30 ° C.). Moreover, the transmittance of CO ₂ at this time was about 1 × 10 ⁻⁷ (see FIGS. 10 and 11).

In addition, CO_Two-CH_FourEven in a mixed system,
CH in low temperature range_Four10 is reduced (see FIG. 10).
), The transmission coefficient ratio α (CO_Two/ CH_Four) Is transparent
It increases with over-temperature, and around 30 ° C,
It was 0. CO at this time _TwoIs 1 × 10^-7
(See FIG. 10).

As described above, in the Y-type zeolite membrane synthesized on the outer surface of the alumina tube of Examples 1 and ₂ , N ₂
CO ₂ could be selectively separated in a mixed system with CH ₄ and CH ₄ .

[Brief description of the drawings]

FIG. 1 is an electron micrograph (magnification: 20) of the surface of an alumina tube of Example 1 after hydrothermal synthesis for 12 hours.
00 times).

FIG. 2 is an electron micrograph (2,000-fold magnification) of a cross section on the surface side of the alumina tube after hydrothermal synthesis has been performed on the surface of the alumina tube of Example 1 for 12 hours.

FIG. 3 is an electron micrograph (magnification: 20) of the surface of the alumina tube of Example 1 after hydrothermal synthesis for 24 hours.
00 times).

FIG. 4 is an electron micrograph (2,000-fold magnification) of a cross section on the surface side of the alumina tube after hydrothermal synthesis on the surface of the alumina tube of Example 1 for 24 hours.

FIG. 5 is an X-ray diffraction spectrum of the surface after hydrothermal synthesis on the alumina plate of Example 3, a spectrum after synthesis for 6 hours (a) and a spectrum after synthesis for 12 hours (b). FIG. 7 is a diagram combining a spectrum (c) after being synthesized for 24 hours.

FIG. 6 is a diagram showing a change in weight of the zeolite membrane of Example 1.

FIG. 7 is a diagram schematically illustrating a system for measuring the transmittance of various gases.

FIG. 8 is a diagram showing details of an attached state of the alumina tube to the system.

FIG. 9 is a view showing the relationship between the permeability of various single component gases and the dynamic molecular diameter in the zeolite membranes of Examples 1 and 2.

FIG. 10 is a diagram showing the relationship between the permeation temperature and the gas permeability for the zeolite membrane of Example 1.

FIG. 11 is a diagram showing the relationship between the permeation temperature and the gas permeability for the zeolite membrane of Example 2.

FIG. 12 is a diagram showing separation coefficients of various gases in the zeolite membranes of Examples 1 and 2.

Claims (6)

[Claims] 1. A surface layer of polycrystalline zeolite formed on the surface of a porous substrate, and a polycrystalline zeolite existing in a hole below the surface layer and on the surface side of the porous substrate. A zeolite membrane comprising a zeolite anchor portion. 2. The zeolite membrane according to claim 1, wherein the zeolite in the surface layer is a Y-type zeolite. 3. A zeolite comprising: a step of adhering zeolite particles on a surface including pores on the surface of a porous substrate; and a step of synthesizing a zeolite membrane on the surface of the substrate. Manufacturing method of membrane. 4. The method according to claim 3, wherein the zeolite particles are mainly composed of X-type zeolite,
The method for synthesizing a zeolite membrane, wherein the zeolite membrane is Y-type. 5. A surface layer of polycrystalline zeolite formed on the surface of a porous substrate, and a polycrystalline zeolite formed in pores below the surface layer and on the surface side of the porous substrate. Separating a gas of at least one component from a mixture of gases using a zeolite membrane with a zeolite anchor. 6. The method according to claim 5, wherein the zeolite in the surface layer is a Y-type zeolite, and separates carbon dioxide from a gas mixture containing carbon dioxide and nitrogen in the presence of water. And how.