JP4856595B2 - Method for producing zeolite membrane composite for gas separation - Google Patents

Description

  The present invention relates to a method for producing a zeolite membrane composite for gas separation.

  Crystalline aluminosilicates, which are collectively referred to as zeolite, have a molecular-size microspace (nanospace) in one crystal and are called “molecular sieve”. Zeolite with such a unique higher order structure exhibits shape selection function (molecular sieving function), adsorption / separation purification function, ion exchange function, solid acid function, catalytic function, etc., so it can be used in a wide range of industrial fields. Has been.

There are many types of zeolite such as LTA, MFI, MOR, AFI, FER, FAU, and DDR depending on their crystal structures. Among them, DDR (Deca-Dodecasil 3R) is a crystal whose main component is silica, and its pores are formed by a polyhedron including an oxygen 8-membered ring, and the pore diameter of the oxygen 8-membered ring is 0. .44 × 0.36 nm is known (Non-Patent Document 1).
The DDR type zeolite having such a structural feature has a relatively small pore diameter among zeolites, and allows carbon dioxide (CO ₂ ) having a molecular diameter of 0.33 nm to pass therethrough, and has a molecular diameter of 0.38 nm. Methane (CH ₄ ) hardly permeates and can be applied as a separation membrane.
Y-type zeolite (FAU) is a zeolite having the same crystal structure as faujasite, which is a natural zeolite, and has a 12-membered ring structure of oxygen, and the pore diameter of the oxygen 12-membered ring is 0.74 nm. It is known and can pass through vacancies to molecules of about 0.95 nm by molecular vibration. In addition, it is more hydrophilic than silicalite and has excellent carbon dioxide (CO ₂ ) adsorption properties (Patent Document 2), so that it can be applied as a gas separation membrane.

  By the way, since zeolite is poor in plasticity, in most cases, when forming into a film, a hydrothermal synthesis method, that is, using a large amount of water and an organic crystallization regulator such as an aluminum source, a silica source, an alkali metal, and amines as appropriate. Prepare the desired product zeolite composition, enclose them in a pressure vessel such as an autoclave, and heat them in the presence of a porous support such as alumina or a tube. A zeolite membrane is synthesized. Moreover, after applying a zeolite seed crystal, a zeolite membrane is further synthesized by hydrothermal synthesis (for example, Patent Document 1).

  However, the zeolite membrane formed by hydrothermal synthesis has a drawback that defects such as pinhole defects and cracks are likely to occur, and the thickness of the zeolite membrane is increased to prevent such defects.

JP 2003-159518 A JP-A-10-36114 W. M. Meier, D. H. Olson, Ch. Baerlocher, Atlas of zeolite structure types, Elsevier (1996)

A zeolite membrane formed by hydrothermal synthesis has poor bonding efficiency between adjacent zeolite crystals, and voids are generated, resulting in low gas separation efficiency.
An object of this invention is to provide the manufacturing method of the zeolite membrane composite for gas separations using the zeolite membrane which reduced the space | gap by densification.

  The present inventors have found that after applying or immersing an alkaline aqueous solution on the surface of the zeolite membrane, the zeolite membrane can be densified by heat-treating the zeolite membrane under pressure, and further research is advanced based on this finding. The present invention has been completed.

That is, the present invention
[1] In the method for producing a zeolite membrane composite for gas separation, (1) a step of forming a zeolite membrane on the surface of the porous support, (2) a step of applying or immersing an alkaline aqueous solution on the surface of the zeolite membrane, (3) A zeolite membrane for gas separation, comprising a step of forming a zeolite membrane inside the porous support by heat-treating the zeolite membrane obtained in the step (2) under pressure. Production method of the composite,
[2] The production method according to [1], wherein the zeolite membrane is a DDR type zeolite membrane or a Y type zeolite membrane,
[3] Alkaline aqueous solution is composed of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, potassium bicarbonate, calcium hydroxide, lithium hydroxide, sodium silicate, natural soda, organic amine and ammonium salt. The production method according to [1] or [2] above, which is an aqueous solution containing at least one selected from the above,
[4] The manufacturing method according to any one of [1] to [3], wherein the heat treatment is performed at 80 to 300 ° C.
[5] The production method according to any one of [1] to [4], wherein the pressure is 5 to 70 MPa, and [6] a zeolite membrane composite for gas separation is carbon dioxide separation. The production method according to any one of the above [1] to [5], which is a zeolite membrane composite for use,
About.

  According to the method of the present invention, since the zeolite membrane can be easily densified, a composite having a defect-free zeolite membrane that can be used industrially and suitably as a gas separation membrane can be produced and provided. Is possible.

  The method for producing a zeolite membrane composite for gas separation according to the present invention comprises the steps of (1) forming a zeolite membrane on the surface of a porous support, and (2) the surface of the zeolite membrane. A step of applying or immersing an alkaline aqueous solution on the substrate, and (3) a step of forming a densified zeolite membrane inside the porous support by heat-treating the zeolite membrane obtained in the step (2) under pressure. It is characterized by including. Hereinafter, each step will be described.

[Step (1)]
This step is a step of forming a zeolite membrane on the surface of the porous support. This step can be carried out, for example, by applying zeolite powder (seed crystal) on the surface of the porous support and synthesizing it hydrothermally.
Examples of the porous support used in the present invention include, but are not limited to, porous bodies such as alumina, silica, cordierite, zirconia, titania, Vycor glass, and sintered metal. Can be used. Although the shape of the said porous support body is not specifically limited unless the objective of this invention is inhibited, Usually, it is plate shape or tube shape. The pore diameter of the porous support is not particularly limited as long as the object of the present invention is not impaired, but is usually 0.01 to 5 μm, preferably 0.05 to 2 μm.

  The zeolite membrane is formed by, for example, applying a zeolite powder (seed crystal) suspension aqueous solution (hereinafter also referred to as a zeolite powder suspension aqueous solution) to the surface of the porous support and then drying it as desired. Done. The type of zeolite used as a raw material is not particularly limited, and for example, Y type zeolite (FAU), DDR type zeolite (Deca-Dodecasil 3R) A type zeolite (LTA), L type zeolite (LTL), mordenite (MOR), ZSM -5 (MFI), silica sodalite (SOD) and the like. The coating method is not particularly limited as long as the object of the present invention is not impaired, but a rubbing (rubbing) method or a dipping method is preferable.

The rubbing (rubbing) method is a method in which a zeolite powder suspension (seed crystal) is uniformly applied by rubbing a zeolite powder suspension on the surface of a porous support and then drying it if desired.
The dipping method is a method in which a porous support is dipped in a zeolite powder suspension, and a zeolite powder (seed crystal) is uniformly coated on the surface.

  In this step, hydrothermal synthesis is performed after the coating or drying, and a zeolite membrane can be formed from the zeolite powder coated on the porous support by the hydrothermal synthesis. Hydrothermal synthesis is performed by Toshihiro Tomita, Kunio Nakayama, Hitoshi Sakai, Microporous and Mesoporous Materials 68 (2004) 71-75 or Hidetoshi Kita, Kazunobu Fuchida, Tatsuya Horita, Hidetoshi Asamura, and Kenichi Okamoto, Separation and Purification Technology 25 (2001). It can be carried out according to the method described in 261-268. The temperature of hydrothermal synthesis is not particularly limited as long as it does not hinder the object of the present invention, but from the viewpoint that a zeolite membrane is more uniformly formed on a porous support, 80 to 300 ° C. is preferable, and the reaction time is Usually 2 to 720 hours, preferably 6 to 120 hours.

[Step (2)]
This step is a step of applying or immersing an alkaline aqueous solution on the surface of the zeolite membrane obtained in the step (1).

  Examples of the alkaline aqueous solution used in the present invention include sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium hydroxide, potassium carbonate, potassium hydrogen carbonate, calcium hydroxide, lithium hydroxide, sodium silicate (water glass), natural soda. , An organic amine, an ammonium salt, or an alkaline aqueous solution that generates zeolite crystals. Examples of the organic amine include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethanolamine, diethanolamine, triethanolamine, propylamine, ethylenediamine, 1-adamantanamine, melamine, piperazine, 4-amino-tetramethylpiperazine , Hexamethylenediamine, pentaethylenehexamine, bis (2-hydroxyl) iminotris (hydroxymethyl) methane, pyridine, aniline, N-methylaniline, N, N-dimethylaniline, and the like. Methylammonium chloride, tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium hydroxide, tetraethylammonium chloride , Tetraethylammonium bromide or hydroxide of the organic amine, (e.g., such as hydroxide methyl ammonium), chlorides (e.g., such as methyl chloride ammonium), bromide (e.g., such as methyl bromide ammonium) and the like.

  Although the method of application | coating or immersion is not specifically limited unless the objective of this invention is inhibited, The dripping application method and the dip coating method are preferable.

The drop coating method is a method in which a predetermined amount of an alkaline aqueous solution is dropped onto the surface of the zeolite membrane obtained in the step (1) to uniformly coat the surface. In addition, as for the dripping amount in dripping application | coating, 0.02-0.2 microliter / mm < ² > is preferable.
The dip coating method is a method of applying an alkaline aqueous solution to a zeolite membrane by immersing the zeolite membrane obtained in the step (1) in an alkaline aqueous solution and then pulling it up at 0.1 mm / sec to 10 mm / sec. It is.

[Step (3)]
This step is a step of forming a densified zeolite membrane inside the porous support by heat-treating the zeolite membrane obtained in the step (2) under pressure. In this step, the zeolite crystals of the zeolite membrane laminated on the porous support are dissolved, and after the dissolved zeolite moves into the pores of the porous support, the zeolite is recrystallized and filled, A zeolite membrane composite for gas separation in which a densified zeolite membrane is formed inside the porous support is obtained. The thickness of the zeolite membrane of the obtained zeolite membrane composite for gas separation is not particularly limited, but is usually about 0.1 to 5 μm.

  Although the apparatus used for the heat processing under pressure of this process will not be specifically limited if it is a press apparatus provided with the heating apparatus, For example, a heat press apparatus as shown in the lower figure of FIG. 1 can be used. This apparatus includes a piston 1, a cradle 5, and a band heater 6 as main components. The pressure treatment is usually performed at about 5 to 70 MPa, preferably about 10 to 60 MPa, more preferably about 30 to 50 MPa. The heating treatment is usually performed at about 80 to 300 ° C, preferably about 100 to 200 ° C, more preferably about 110 to 180 ° C. The treatment time is usually about 0.1 to 72 hours, preferably about 0.5 to 12 hours, more preferably about 0.5 to 3 hours.

  Next, a gas separation method using the zeolite membrane composite for gas separation produced according to the present invention will be described. A gas separation method using a zeolite membrane composite for gas separation produced according to the present invention is characterized in that a carbon dioxide mixed gas is brought into contact with the zeolite membrane composite for gas separation and carbon dioxide is selectively permeated. .

  As a specific aspect of the above method, the carbonic acid mixed gas is placed on one side (zeolite membrane side) of the zeolite membrane composite for gas separation, and the carbon dioxide partial pressure on the opposite side (porous support surface side) is set. If the carbon dioxide partial pressure on the zeolite membrane side is set below, the carbon dioxide selectively permeates through the zeolite membrane composite for gas separation, and carbon dioxide in the carbon dioxide mixed gas is separated to the porous support surface side. Can do. This carbon dioxide separation method can be suitably carried out at a temperature of usually about 0 to 500 ° C, preferably about 25 to 200 ° C.

  The carbonic acid mixed gas is not particularly limited as long as it contains carbon dioxide. For example, carbon dioxide and hydrogen, oxygen, nitrogen, helium, neon, argon, krypton, xenon, fluorine, chlorine, bromine, Examples of the mixed gas include carbon monoxide, nitrogen monoxide, nitrogen dioxide, ammonia, sulfur dioxide, hydrogen sulfide, hydrogen chloride, water (steam), methanol, ethanol, paraffinic hydrocarbons, olefinic hydrocarbons, and the like. The paraffinic hydrocarbons are also called saturated chain hydrocarbons, alkanes or methane hydrocarbons. Examples of such paraffinic hydrocarbons include methane, ethane, propane, butane, pentane, hexane, heptane, Examples include octane.

  The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[Example 1]
(Process 1)
A DDR type zeolite membrane was prepared with reference to non-patent literature (Toshihiro Tomita, Kunio Nakayama, Hitoshi Sakai, Microporous and Mesoporous Materials 68 (2004) 71-75).
Specifically, it was performed as follows. After putting 1.3 g of 1-adamantanamine in a 100 ml wide-mouthed bottle made of polyethylene, 8.3 g of ethylenediamine (manufactured by Aldrich) is put and 1-adamantane is used with a shaker (manufactured by Thomas Scientific Instruments) Shaking was continued until the amine crystal particles disappeared. Thereafter, 67 g of water was added and the mixture was shaken with a shaker for 1 hour. The mixture was placed in a 100 ml eggplant flask, stirred at 95 ° C. for 1 hour in an oil bath, and the resulting cloudy suspension was cooled with ice. While stirring this suspension, 14 g of 40 wt% silica sol (AS-40, manufactured by LUDOX) was added and shaken for 3 hours to obtain a raw material solution.
DDR type zeolite powder (seed crystal) produced according to the method described in non-patent literature (MC den Exter, JC Jansen, H. van Bekkum, Stud. Surf. Sci. Catal. 84 (1994) 1159-1166) For 30 minutes or more to prepare a DDR type zeolite powder suspension aqueous solution of 0.15% by weight. A disk-shaped alumina porous support (outer diameter 18.5 mm, thickness 3.0 mm, average pore diameter 0.7 μm, manufactured by Noritake Co., Ltd.) and an outer diameter of 70 mm containing 15 ml of a DDR type zeolite powder suspension. The seed crystal was applied to the surface of the porous support while being immersed in a glass petri dish and stirring for 30 minutes. The porous support coated with the seed crystal was dried at 80 ° C. A Teflon sealing tape (Nitoflon pipe seal, manufactured by Nitto Denko Corporation) was wound around one surface of the porous support.
The porous support was placed vertically in a stainless steel pressure vessel with a fluororesin inner cylinder having an internal volume of 100 ml, and the raw material solution was introduced until the porous support was submerged. Subsequently, hydrothermal synthesis was carried out under heat treatment conditions of 150 ° C. for 50 hours, and a DDR type zeolite membrane was laminated on the porous support.
(Results and Discussion)
The obtained film was evaluated by X-ray diffraction (RINT 2000, manufactured by Rigaku Corporation), and the structure of the film was observed by a scanning electron microscope (S-5000, manufactured by Hitachi, Ltd.). When the crystal phase was evaluated by X-ray diffraction, the diffraction peaks of the DDR type zeolite and the porous support were detected, and it was found to be a DDR type zeolite membrane. Moreover, when this was observed with the scanning electron microscope, it turned out that the film | membrane about 5 micrometers in thickness is formed on the porous support body. 3 and 4 are scanning electron micrographs showing the structure of the produced DDR type zeolite membrane, FIG. 3 shows the surface of the membrane, and FIG. 4 shows the cross section of the membrane.

(Process 2)
15 μL of 5M NaOH aqueous solution was uniformly applied to the surface of the DDR type zeolite membrane of the porous support on which the DDR type zeolite membrane obtained in Step 1 was laminated by dropwise application. After the protective sheet 2 (outer diameter 19.0 mm, thickness 1.5 mm, trade name: Hyper Sheet, manufactured by Japan Gore-Tex) is pressed on the surface of the DDR type zeolite membrane and the protective sheet 2 is installed on the cradle 5, the zeolite membrane Was introduced into a hot press apparatus schematically shown in the lower part of FIG. An enlarged view around the zeolite membrane is shown in the upper diagram of FIG.
(Process 3)
After introducing the porous support into the hot press apparatus as described above, the entire hot press apparatus was heated from room temperature to 150 ° C. over 15 minutes while maintaining the pressure at 40.0 MPa, and at that temperature for 2 hours. Retained. Next, the porous support was taken out from the hot press apparatus, the protective sheet attached to the porous support was peeled off, the porous support was placed in distilled water, and left for 12 hours. After washing, it was dried in a dryer at 80 ° C. to obtain a zeolite membrane composite for gas separation.
(Results and Discussion)
When the crystal phase was evaluated by examining the crystal of the zeolite membrane of the gas separation zeolite membrane composite obtained in Step 3 by X-ray diffraction, the same DDR type zeolite and porous support as those before Step 3 were treated. Thus, it was found that the zeolite crystals were not changed by the treatment in Step 3. Further, when this was observed with a scanning electron microscope, it was found that a part of the zeolite crystals on the film surface was dissolved to form a smooth surface. A film having a smooth surface with a thickness of 4 μm was formed on the porous support, and it was found that a part of the film was dissolved and moved inside the porous support. 5 and 6 are scanning electron micrographs showing the structure of the DDR type zeolite membrane prepared in Step 3 treatment of the DDR type zeolite membrane. FIG. 5 shows the surface of the membrane, and FIG. 6 shows the cross section of the membrane. Show.

[Example 2]
In Step 3, except that the heat treatment condition under the pressurized condition is changed from 150 ° C. to 180 ° C., the same operation as in Example 1 is performed, the DDR type zeolite membrane is densified and the membrane is repaired, and the gas separation zeolite A membrane complex was obtained. Evaluation of the obtained zeolite membrane composite for gas separation was performed by X-ray diffraction as in Example 1, and the structure of the obtained zeolite membrane composite for gas separation was determined by observation with a scanning electron microscope.
(Results and Discussion)
The X-ray diffraction peaks of the DDR type zeolite and the porous support similar to those in Example 1 were detected, and it was found that the zeolite crystals were not changed by Step 3. Moreover, when this was observed with a scanning electron microscope, the triclinic structure of typical DDR type zeolite crystals found on the film surface disappeared, and a porous structure constituting a porous support was seen, It was observed that the film formed on the porous support was dissolved and introduced into the porous support. From the scanning electron micrograph of the fractured surface of the porous support, it was found that a part of the package was empty, but the porous structure in the porous support was satisfied and the structure was dense. As is clear from this, it has been found that the DDR type zeolite crystals move and are densely packed into the pores of the porous support by the densification treatment (step 3) according to the present invention. 7 and 8 are scanning electron micrographs showing the structure of the DDR type zeolite membrane produced in the densification treatment of the DDR type zeolite membrane. FIG. 7 shows the surface of the membrane, and FIG. 8 shows the cross section of the membrane. Show.

[Example 3]
(Process 1)
A Y-type zeolite membrane was prepared with reference to non-patent literature (Hidetoshi Kita, Kazunobu Fuchida, Tatsuya Horita, Hidetoshi Asamura, and Kenichi Okamoto, Separation and Purification Technology 25 (2001) 261-268).
Specifically, it was performed as follows. In a glass beaker, 105 g of distilled water was added, 1.3 g of sodium aluminate was added with stirring, and the mixture was stirred at room temperature for 5 minutes. Thereafter, 6.3 g of sodium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) was added while stirring, and the mixture was stirred for about 30 minutes until the solution reached room temperature. This solution was added to a plastic container containing 40 g of water glass (manufactured by Aldrich), stirred at room temperature for 4 hours, and allowed to stand at 30 ° C. for 16 hours. This solution was transferred to a Pyrex glass reaction vessel equipped with a cooling tube, and a Y-zeolite seed crystal (product number: HSZ-320NAA, manufactured by Tosoh Corporation) was applied thereto by a rubbing (rubbing) method. A mullite porous support (outer diameter: 18.5 mm, thickness: 3.0 mm, manufactured by Nikkato Co., Ltd.) was installed with the seed crystal introduction side facing down, and hydrothermal synthesis was carried out in an oil bath at 100 ° C. for 7 hours. did. After the reaction, the product was immediately taken out, and unreacted substances adhering to the membrane surface were washed away with running water. Thereafter, the porous support was placed in distilled water and left for 24 hours while changing the water until the pH of the water reached 7. After washing, it was dried in a dryer at 80 ° C., and a Y-type zeolite membrane was laminated on the porous support.
(Results and Discussion)
When the crystal phase was evaluated by examining the obtained film by X-ray diffraction, the diffraction peaks of the Y-type zeolite and the porous support were detected, and it was found that the film was a Y-type zeolite film. Moreover, when this was observed with the scanning electron microscope, it turned out that the film | membrane whose thickness is around 6 micrometers is formed on the porous support body with the surface which is not smooth. 9 and 10 are scanning electron micrographs showing the structure of the produced Y-type zeolite membrane, FIG. 9 shows the surface of the membrane, and FIG. 10 shows the cross section of the membrane.

(Process 2)
30 μL of a 5 M NaOH aqueous solution was uniformly applied to the surface of the Y-type zeolite membrane of the porous support obtained by laminating the Y-type zeolite membrane obtained in step 1 by dropwise application. After the protective sheet 2 (outer diameter 19.0 mm, thickness 1.5 mm, product name: Hyper sheet, manufactured by Japan Gore-Tex) is pressed on the surface of the Y-type zeolite membrane and the protective sheet 2 is installed on the cradle 5, the zeolite membrane The porous support body laminated with was introduced into a hot press apparatus. A schematic view around the zeolite membrane is shown in FIG.
(Process 3)
After introducing the porous support into the hot press apparatus as described above, the entire hot press apparatus was heated from room temperature to 150 ° C. over 15 minutes while maintaining the pressure at 34.6 to 40.0 MPa. Hold at temperature for 2 hours. Next, the porous support is taken out from the hot press apparatus, the protective sheet attached to the porous support is peeled off, the porous support is put into distilled water, and water is exchanged until the pH of the water reaches 7. Left for hours. After washing, it was dried in a dryer at 80 ° C. to obtain a zeolite membrane composite for gas separation.
(Results and Discussion)
The zeolite phase of the zeolite membrane composite for gas separation obtained in Step 3 was evaluated by X-ray diffraction to evaluate the crystal phase. As a result, the same Y-type zeolite and porous support as those before the densification treatment were obtained. Was found to be a Y-type zeolite membrane. Further, when this was observed with a scanning electron microscope, it was found that a film having a smooth surface with a thickness of 3 μm was formed on the porous support and a part of the crystal was dissolved. 11 and 12 are scanning electron micrographs showing the structure of the Y-type zeolite membrane produced in the densification treatment of the Y-type zeolite membrane. FIG. 11 shows the surface of the membrane, and FIG. 12 shows the cross section of the membrane. .

[Test example]
(Gas permeation test)
A gas permeation test was conducted using the densified Y-type zeolite membrane and untreated Y-type zeolite membrane obtained in Example 3. A permeation test of carbon dioxide / nitrogen (CO ₂ / N ₂ = 20: 80) mixed gas at room temperature was performed under the following conditions. The results are shown in Table 1. _{Incidentally,} showing the experimental apparatus of CO 2 / _{N 2} mixed gas schematically in Figure 13. A Y-type zeolite membrane and a densified Y-type zeolite membrane are attached to the cells, respectively, and a CO ₂ / N ₂ test gas is circulated, and a CO ₂ / N ₂ mixed gas is brought into contact with the composite as shown in FIG. The gas (permeated gas) that permeated the Y-type zeolite membrane was sampled, and gas chromatography (GC) measurement was performed under the following experimental conditions.
(Experimental conditions)
Gas analysis: gas chromatography; GC (TCD)
Column: Porapak-Q 2m, Molecular Sieve 5A 2m
Carrier gas: He
Test gas: CO ₂ / N ₂ = 20: 80
Gas flow rate: 100ml / min
Inlet gas pressure: 150kPa

(result)

As is clear from Table 1, the densified Y-type zeolite membrane has both reduced CO ₂ permeability and N ₂ permeability compared to the untreated Y-type zeolite membrane, but the decrease in N ₂ permeability. Was larger than the decrease in CO ₂ permeability, and the CO ₂ / N ₂ separation selectivity α (CO ₂ / N ₂ ) was 23.
Therefore, from the gas permeation test results, it was possible to confirm the gas separation characteristics and usefulness of the Y-type zeolite membrane densified by the production method of the present invention.

    According to the present invention, it is possible to provide a defect-free zeolite membrane composite for gas separation that can be used industrially and suitably as a gas separation membrane.

FIG. 1 is a schematic view showing a zeolite membrane laminated on a porous support in a hot press apparatus in step 3. The upper figure shows an enlarged view around the zeolite membrane, and the lower figure shows a schematic diagram of the hot press apparatus. The upper figure is a view of the pressure applied to the surface of the zeolite membrane laminated on the porous support in Step 3 as seen from the side of the zeolite membrane. FIG. 2 is a schematic view showing densification of the zeolite membrane laminated on the porous support in Step 3. In step 3, a porous support including a zeolite membrane that has been densified or filled in pores by dissolving and re-depositing the zeolite membrane with respect to the zeolite membrane having defects laminated on the porous support, It is the schematic seen from the side. FIG. 3 shows the results of observation with a scanning electron microscope of the surface of the DDR type zeolite membrane laminated on the porous support. FIG. 4 shows a scanning electron microscope observation result of the fracture surface of the DDR type zeolite membrane laminated on the porous support. FIG. 5 shows a scanning electron microscope observation result of the DDR type zeolite membrane surface of the zeolite membrane composite for gas separation produced in Example 1. 6 shows a scanning electron microscope observation result of the fracture surface of the DDR type zeolite membrane of the gas separation zeolite membrane composite produced in Example 1. FIG. FIG. 7 shows the results of observation with a scanning electron microscope of the DDR type zeolite membrane surface of the gas separation zeolite membrane composite produced in Example 2. FIG. 8 shows a scanning electron microscope observation result of the fracture surface of the DDR type zeolite membrane of the zeolite membrane composite for gas separation produced in Example 2. FIG. 9 shows the result of observation with a scanning electron microscope of the surface of the Y-type zeolite membrane laminated on the porous support. FIG. 10 shows a scanning electron microscope observation result of the fracture surface of the Y-type zeolite membrane laminated on the porous support. FIG. 11 shows the results of observation with a scanning electron microscope of the surface of the Y-type zeolite membrane of the zeolite membrane composite for gas separation produced in Example 3. FIG. 12 shows a scanning electron microscope observation result of the fracture surface of the Y-type zeolite membrane of the zeolite membrane composite for gas separation produced in Example 3. FIG. 13 is a schematic diagram showing an experimental apparatus used in a carbon dioxide / nitrogen mixed gas separation experiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston 2 Protective sheet 3 Zeolite membrane 3a Defect 3b in zeolite membrane Densified zeolite membrane 4 Porous support body 4a Zeolite membrane layer filled in the support pore 5 Receiving base 6 Band heater

Claims (4)

In the method for producing a zeolite membrane composite for gas separation, (1) a step of forming a zeolite membrane on the surface of the porous support, (2) coating or dipping an alkaline aqueous solution for generating zeolite crystals on the surface of the zeolite membrane. Step, (3) a step of heat-treating the zeolite membrane obtained in the step (2) at 80 to 300 ° C. under a pressure of 5 to 70 MPa to form a zeolite membrane inside the porous support. A method for producing a zeolite membrane composite for gas separation, comprising:   The method according to claim 1, wherein the zeolite membrane is a DDR type zeolite membrane or a Y type zeolite membrane.   The alkaline aqueous solution was selected from sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, potassium bicarbonate, calcium hydroxide, lithium hydroxide, sodium silicate, natural soda, organic amine and ammonium salt The production method according to claim 1 or 2, which is an aqueous solution containing at least one kind. The production method according to any one of claims 1 to 3 , wherein the zeolite membrane composite for gas separation is a zeolite membrane composite for carbon dioxide gas separation.