JP2007061774A - Zeolite separation film and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zeolite separation film capable of sufficiently suppressing that impurities originating from the raw material of a zeolite film get mixed in an organic solvent, and its manufacturing method. <P>SOLUTION: The manufacturing method of the zeolite separation film composed of a support and the zeolite film provided on the support includes a film base material forming process for bringing the support in contact with a reaction liquid containing the raw material of the zeolite film to form a zeolite film base material comprising zeolite crystals on the surface of the support, a washing process for washing the zeolite film base material and an immersion process for immersing the zeolite film base material in water after the washing process to obtain the zeolite film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a zeolite separation membrane and a method for producing the same.

  Zeolite, which is representative of a crystalline porous material, is a material that has solid acidity, ion exchange capacity, adsorption separation capacity, molecular level pores and the like due to its pore structure. In recent years, the use of this zeolite as a membrane has attracted attention as a separation membrane for separating water in an organic solvent.

  In the method for producing a zeolite membrane, the zeolite membrane is formed on the surface of the support by bringing the support into contact with a reaction solution containing a raw material of the zeolite membrane mainly composed of a silica source and an alumina source and heating the reaction solution. A so-called hydrothermal synthesis method is often used (see Patent Document 1).

  However, in the hydrothermal synthesis method, when a zeolite membrane body is formed on the surface of the support, the raw material of the zeolite membrane such as unreacted substances, zeolite particles, or amorphous components is formed on the surface of the zeolite membrane body. Derived impurities (eg sodium) are observed. In this case, when the zeolite membrane body is used as it is as a separation membrane, there arises a problem that the permeation flux of the permeation component that permeates the zeolite membrane is reduced and the separation performance of the zeolite membrane is lowered.

In order to suppress such a situation, in the conventional method for producing a zeolite separation membrane, after the zeolite membrane body is pulled up from the reaction solution, for example, the operator performs a cleaning operation such as rubbing the zeolite membrane body with a brush. Done. Thus, a zeolite separation membrane having sufficient permeation flux and separation performance has been produced.
Japanese Patent Laid-Open No. 2004-82008

  However, the zeolite separation membrane obtained as described above has the following problems although the zeolite membrane body is sufficiently washed. That is, when water is separated from an organic solvent such as alcohol using the zeolite separation membrane, impurities (for example, sodium) derived from the raw material of the zeolite membrane tend to be mixed in the organic solvent.

  If impurities derived from the raw material of the zeolite membrane are mixed in the organic solvent in this way, it may cause a decrease in product yield in fields requiring extremely high purity with respect to the organic solvent, for example, fields such as semiconductor manufacturing processes. There is a fear.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a zeolite separation membrane that can sufficiently suppress the contamination of impurities derived from the raw material of the zeolite membrane into an organic solvent and a method for producing the same. .

  The inventors of the present invention have intensively studied to solve the above-mentioned problems. As a result, in the zeolite separation membrane, the reason why impurities derived from the raw material of the zeolite membrane are mixed in the alcohol is that the zeolite membrane element is formed on the support surface. When forming the body, it was thought that deposits adhered not only to the surface but also to the inside of the zeolite membrane body, which could not be sufficiently removed only by the conventional washing process. As a result of further earnest studies, the present inventors have found that the above problems can be solved by the following invention, and have completed the present invention.

  That is, the method for producing a zeolite separation membrane of the present invention comprises contacting a support and a reaction liquid containing a raw material for the zeolite membrane in a method for producing a zeolite separation membrane comprising a support and a zeolite membrane provided on the support. A membrane element forming step for forming a zeolite membrane element composed of zeolite crystals on the surface of the support; a washing step for washing the zeolite membrane element; and after the washing step, the zeolite membrane element is immersed in water. And a dipping step for obtaining a zeolite membrane. Here, in the present invention, the term “support” refers to a support in which a seed film of a zeolite membrane element is attached on the surface of the support element, or in the case where no seed crystal is attached.

  The method for producing a zeolite separation membrane of the present invention includes a dipping step in addition to the washing step. Therefore, in the washing step, in addition to removing the deposits attached to the surface of the zeolite membrane element body, Deposits adhered to the inside of the membrane element are also removed. That is, when the washed zeolite membrane is immersed in water, the water sufficiently penetrates into the zeolite membrane. Then, since impurities (for example, sodium) derived from the raw material of the zeolite membrane adhering to the inside of the zeolite membrane element are generally water-soluble, they are eluted by the invading water and sufficiently removed from the zeolite membrane element. Therefore, according to the manufacturing method of the said zeolite separation membrane, the zeolite separation membrane which can fully suppress mixing of the sodium in an organic solvent can be obtained.

  Moreover, in the said immersion process, since the deposit | attachment containing sodium will show alkalinity, if it melt | dissolves in water, when the said deposit | attachment is eluted with water, the pH of water will gradually change from alkaline to alkaline. As a result, zeolite crystals generally dissolve in neutral water, but are difficult to dissolve in alkaline water. Therefore, as described above, the pH of the water shifts to alkaline, thereby suppressing the dissolution of the zeolite crystals in water. Is done. That is, according to the above method for producing a zeolite separation membrane, the dissolution of the zeolite crystal itself is suppressed after the deposits are eluted, so that the decrease in strength (hereinafter also referred to as “membrane strength”) is suppressed. A separation membrane can be obtained.

  Furthermore, the immersion step has an amount of water that can immerse the zeolite membrane body, and since this water is used without waste, it can be performed with a small amount of water, compared to the case of watering, Moreover, since the zeolite membrane is only immersed in water, there is an advantage that the operation is extremely easy.

  In the dipping step, the zeolite membrane is preferably immersed in water for 6 to 72 hours. In this case, it is possible to suppress the impurities derived from the raw material of the zeolite membrane inside the zeolite membrane element from being eluted more securely and the zeolite crystals themselves to be dissolved and the membrane strength from being weakened. Therefore, according to the method for producing a zeolite separation membrane, it is possible to obtain a zeolite separation membrane that has sufficient membrane strength and that can more reliably suppress the contamination of impurities derived from the raw material of the zeolite membrane into the organic solvent. it can.

  In the dipping step, the temperature of the water described above is preferably 80 ° C. or lower. When the temperature is 80 ° C. or lower, even if the deposits are relatively large crystals, the characteristics of the zeolite membrane such as the permeation flux Q and the separation performance α are reduced as compared with the case where the temperature exceeds 80 ° C. It is possible to sufficiently elute the solution.

Here, the “permeation flux Q (kg / m ² h)” refers to the amount of liquid permeating the zeolite separation membrane per unit time. For example, when water is to be separated from a mixed solution of ethanol and water, the amount of water passing through the zeolite separation membrane per unit time.

The “separation performance α” is, for example, in the case of a mixed solution of ethanol and water, a liquid that has passed through the zeolite separation membrane with the water concentration before separation being A1 mass% and the ethanol concentration being A2 mass%. Or if the density | concentration of the water in gas is B1 mass% and the density | concentration of ethanol is B2 mass%, following formula (2);
α = (B1 / B2) / (A1 / A2) (2)
It is represented by. In addition, it becomes possible to isolate | separate a specific liquid with higher concentration from a liquid mixture, so that this value is large.

  The zeolite separation membrane of the present invention is obtained by the production method described above. According to the zeolite separation membrane obtained by the above-described method for producing a zeolite separation membrane, sodium can be prevented from being mixed into the organic solvent.

  ADVANTAGE OF THE INVENTION According to this invention, the zeolite separation membrane which can suppress mixing of the impurity originating in the raw material of the zeolite membrane in an organic solvent, and its manufacturing method can be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  The method for producing a zeolite separation membrane according to the present embodiment includes a seed attachment step in which a seed crystal is attached to a support element, and a contact liquid is brought into contact with a reaction liquid containing a raw material for the zeolite membrane. Above, a membrane element forming step for forming a zeolite membrane element composed of zeolite crystals, a separation step for separating the zeolite membrane element and the reaction solution, a washing step for washing the zeolite membrane element, and a zeolite membrane element A dipping step of immersing the body in water to obtain a zeolite membrane.

  Since the method for producing a zeolite separation membrane includes a dipping step in addition to the washing step, in the washing step, in addition to removing deposits attached to the surface of the zeolite membrane element body, in the dipping step, the zeolite membrane element is removed. Deposits attached to the inside of the body are also removed. That is, when the washed zeolite membrane is immersed in water, the water sufficiently penetrates into the zeolite membrane. Then, since impurities (for example, sodium) derived from the raw material of the zeolite membrane adhering to the inside of the zeolite membrane element are generally water-soluble, they are eluted by the invading water and sufficiently removed from the zeolite membrane element. Therefore, according to the method for producing a zeolite separation membrane, it is possible to obtain a zeolite separation membrane that can sufficiently suppress the contamination of impurities (for example, sodium) derived from the raw material of the zeolite membrane into the organic solvent.

  In the immersion step, the deposit containing impurities (for example, sodium) derived from the raw material of the zeolite membrane exhibits alkalinity when dissolved in water. Therefore, when the deposit is eluted with water, the pH of the water is medium. It gradually shifts from alkaline to alkaline. As a result, zeolite crystals generally dissolve in neutral water, but are difficult to dissolve in alkaline water. Therefore, as described above, the pH of the water shifts to alkaline, thereby suppressing the dissolution of the zeolite crystals in water. Is done. That is, according to the method for producing a zeolite separation membrane, after the deposits are eluted, the dissolution of the zeolite crystal itself is suppressed, so that a zeolite separation membrane in which a decrease in membrane strength is suppressed can be obtained.

  Furthermore, the immersion step has an amount of water that can immerse the zeolite membrane body, and since this water is used without waste, it can be performed with a small amount of water, compared to the case of watering, Moreover, since the zeolite membrane is only immersed in water, there is an advantage that the operation is extremely easy.

  Hereinafter, each step will be described in detail.

[Seed adhesion process]
The seed attachment step is a step of attaching a seed crystal to a support element to form a support.

  Such seed deposition step can be performed arbitrarily. By performing this seed adhesion step, it becomes possible to form a more uniform zeolite membrane element on the support in the membrane element forming step described later, and more uniform on the support in the cleaning step described later. It becomes possible to form a zeolite membrane element.

  The seed crystal differs depending on the type of zeolite of the target zeolite membrane. For example, the same type of zeolite as the zeolite to be formed may be used, or the crystal structure may be similar.

  In the solution containing the seed crystal, the concentration of the seed crystal in the solution is preferably 0.01% by mass to 20% by mass, and more preferably 0.1% by mass to 10% by mass. When the concentration of the seed crystal is less than 0.01% by mass, the seed crystal does not sufficiently adhere to the support element and there are defects such as pinholes in the zeolite membrane as compared with the case where the concentration is in the above range. If the concentration of the seed crystal exceeds 20% by mass, the layer containing the seed crystal becomes too thick as compared with the case where the concentration is in the above range, and the seed crystal in the outer portion is crystallized. Since the inner seed crystal is retained without being sufficiently crystallized, the zeolite membrane tends to be peeled off or defective.

  The support element is not particularly limited, but is preferably porous, and is made of, for example, ceramics, organic polymer, or metal. Examples of ceramics include mullite, alumina, silica, titania, zirconia, and the like. Examples of metals include stainless steel, sintered nickel, and a mixture of sintered nickel and iron. Among these, it is preferable to use alumina as a support element. When alumina is used as the support element, elution of the material of the support element can be suppressed. Note that the support element may be made by sintering zeolite.

  When the support element is porous, the average pore diameter of the pores is preferably 0.1 μm to 20 μm, and more preferably 0.1 μm to 5 μm. In this case, a zeolite membrane with few pinholes can be formed, and a zeolite separation membrane with high separation performance can be obtained. Moreover, it is preferable that a porosity is 5 to 50%, and it is more preferable that it is 30 to 50%. In this case, since the gas permeation amount of the support element is high, a zeolite separation membrane having a high permeation flux can be obtained.

  When the average pore diameter is less than 0.1 μm, compared to the case where the average pore diameter is in the above range, the seed crystal does not sufficiently adhere in the support element pores, and therefore tends to be easily peeled off. When the average pore diameter exceeds 20, compared to the case where the average pore diameter is in the above range, the pores cannot be filled with zeolite crystals, pinholes are generated, and the separation performance tends to be lowered. Further, if the porosity is less than 5%, compared with the case where the porosity is in the above range, the gas permeation flux tends to be low, so that a high permeation flux cannot be obtained. If it exceeds 50%, the mechanical strength of the support is low as compared with the case where the porosity is in the above range, so that the product tends to be unusable.

  The shape of the support element is not particularly limited, and examples thereof include a hollow shape such as a cylindrical shape, a hollow fiber shape, and a tube shape, a plate shape, a honeycomb shape (honeycomb shape), and a pellet shape. It is.

  The seed attaching step is performed by bringing the support element into contact with a solution containing the seed crystal. Examples of the contacting method include an impregnation method, a dip coating method, a spray coating method, a coating method, and a filtration method.

  Note that the solution containing the seed crystal may contain an additive such as a surfactant.

  After passing through the seed attaching step, it is preferable to dry the seed crystal. In this case, the seed crystal can be sufficiently attached to the support element.

[Film body forming process]
The membrane element forming step is a step of bringing a support and a reaction solution containing a raw material of the zeolite membrane into contact with each other to form a zeolite membrane element made of zeolite crystals on the surface of the support. The membrane element forming step is performed by bringing the support to which the seed crystals are attached into contact with a reaction solution containing a raw material for the zeolite membrane.

  The synthesis of the zeolite membrane can be performed, for example, by a hydrothermal synthesis method, a dry gel conversion method, or the like. Among these, it is preferable to synthesize the zeolite membrane by a hydrothermal synthesis method.

  First, in the membrane element forming step, the raw material of the zeolite membrane is added to water and stirred to prepare a reaction solution used for the zeolite synthesis reaction. Then, a zeolite membrane is formed on the surface of the support by impregnating the support with the reaction solution.

  The raw material of the zeolite membrane is an alumina source and a silica source, and may contain an alkali metal source and / or an alkaline earth metal source as necessary. Examples of the alumina source include aluminum powder, aluminum aluminate, aluminum sulfate, aluminum nitrate, aluminum chloride, alumina powder, colloidal alumina, and the like. Silica sources include sodium silicate, water glass, alkali metal silicates such as potassium silicate, silica powder, silicic acid, colloidal silica, acid clay, kaolin, silicon alkoxide (aluminum isopropoxide, etc.), etc. Can be mentioned. Examples of the alkali (earth) metal source include sodium chloride, potassium chloride, calcium chloride, magnesium chloride and the like. In addition, alkali metal silicate can be used as a silica source and an alkali metal source.

The molar ratio (converted to SiO ₂ / Al ₂ O ₃ ) between the silica source and the alumina source in the reaction solution can be appropriately determined depending on the type of zeolite of the target zeolite membrane.

  Moreover, the density | concentration of the said silica source and an alumina source is not specifically limited. That is, in the film body forming step, the concentration of the silica source or the alumina source may be increased to make the reaction liquid gel, which may be brought into contact with the support, and the concentration of the silica source or the alumina source should be reduced. Thus, the low viscosity reaction liquid may be brought into contact (impregnated) with the support.

  That is, the composition of the reaction solution, the reaction temperature, the reaction time, and the like vary depending on the zeolite type of the target zeolite membrane.

  Note that the reaction solution may contain an additive such as a crystallization accelerator. Examples of the crystallization accelerator include tetrapropylammonium salt and tetrabutylammonium salt.

  As described above, the reaction solution contains various substances. Substances that can become impurities derived from the raw material of the zeolite membrane after film formation include alkali metals, alkaline earth metals, or crystallization accelerators. An additive etc. are mentioned. These are generally water-soluble.

[Separation process]
The separation step is a step of separating the zeolite membrane body and the reaction liquid. Separation methods include, for example, a method in which a support on which a zeolite membrane element is formed is pulled out from the reaction solution, and a support in which the zeolite membrane element is formed is immersed in the reaction solution. For example, a method of removing from a discharge port provided at the bottom of the container, a method of moving the container together with the reaction liquid from a state where the support on which the zeolite membrane element is formed is immersed in the reaction liquid, Etc.

  In addition, it is preferable to perform a isolation | separation process immediately from the state which the support body in which the zeolite membrane element was formed is immersed in the reaction liquid. In this case, it can suppress that a zeolite membrane body dries and a deposit | attachment solidifies.

[Washing process]
The cleaning step is a step of cleaning the zeolite membrane. Specifically, in the membrane element forming step, it is a step of removing deposits such as unreacted substances, zeolite particles, or amorphous components formed on the zeolite membrane element.

  Immediately after the separation step, the zeolite membrane element is at a high temperature, so that the zeolite membrane element is easily dried. That is, when the zeolite membrane element is separated from the reaction solution, the moisture on the surface of the zeolite membrane element is evaporated and dried. In this case, when the surface of the zeolite membrane element is dried, the deposit on the surface of the zeolite membrane element is solidified, and it tends to be difficult to remove the deposit in the washing step.

  Therefore, the zeolite membrane is washed after the separation step. The washing step is preferably performed immediately after the separation step. Here, the reason why the washing step is performed immediately after the separation step is to perform washing before the zeolite membrane is dried, and specifically, it is preferably within 30 minutes.

  The washing water used in the washing step is not particularly limited, but pure water is preferable. When washing water other than pure water, such as tap water containing alkali ions, is used, there is a risk that alkali ions contained in tap water may adhere to the zeolite separation membrane as compared with the case of using pure water. Furthermore, there is a risk that the characteristics of the zeolite membrane element may change due to the change in the physical properties of the zeolite crystals in which the alkali metal or alkaline earth metal in the zeolite membrane element is not replaced with calcium in tap water.

  The method for cleaning the zeolite membrane is not particularly limited. Specific examples include hand cleaning, spray cleaning, brush cleaning, and ultrasonic cleaning.

  By washing the zeolite membrane element in this way, the deposits adhering to the surface of the zeolite membrane element can be removed.

[Immersion process]
The dipping step is a step of immersing the zeolite membrane body in water to obtain a zeolite membrane. Specifically, it is a step of removing deposits adhering to the inside of the zeolite membrane element. Here, an example of the immersion process will be specifically described with reference to FIG.

  FIG. 1 is a perspective view showing an immersion apparatus used in the immersion process of the present embodiment. As shown in FIG. 1, the immersion apparatus 100 includes a container 10, and the support tray 3 is disposed on the bottom surface of the container 10. The support tray 3 has a plurality of linearly extending grooves 5 arranged in parallel with each other. In the immersion device 100 having such a configuration, the cylindrical separation membrane element 1 is disposed in each groove 5. The separation membrane element 1 has a zeolite membrane element on the outside of a cylindrical support. At this time, water 8 is stored in the container 10 in a non-flowing state, and the separation membrane element 1 is immersed in the water 8.

  In this immersion apparatus 100, the separation membrane element 1 is placed in the groove 5 at the top of the support tray 3, and then the separation membrane element 1 and the support tray 3 are immersed in the water 8 in the container 10. Also good. Further, the support tray 3 is disposed on the bottom surface of the container 10, the separation membrane element body 1 is disposed in the upper groove 5, and then water 8 is injected into the container 10 to immerse the separation membrane element body 1. May be.

  As the separation membrane element 1 is immersed in the water 8 in this way, the water 8 enters the inside of the separation membrane element 1. The impurities (for example, sodium) derived from the raw material of the zeolite membrane adhering to the inside of the separation membrane element 1 are generally water-soluble, and thus are eluted by the infiltrated water 8. Therefore, when dehydration treatment of the organic solvent is performed using the zeolite separation membrane produced by the method for producing a zeolite separation membrane according to the present embodiment, contamination of impurities derived from the raw material of the zeolite membrane into the organic solvent can be suppressed. .

  In the dipping step, the water 8 is preferably pure water. Here, pure water means water having a resistance value of 1 MΩ / cm or more. When water 8 other than pure water, for example, tap water containing alkali ions, is used, alkali ions contained in tap water may adhere to the separation membrane element 1 as compared with the case where pure water is used. Furthermore, there is a risk that the characteristics of the zeolite membrane element may change due to the change in the physical properties of the zeolite crystals in which the alkali metal or alkaline earth metal in the zeolite membrane element is not replaced with calcium in tap water.

  The pH of the water 8 is preferably 4 to 9 in the initial state, that is, immediately after the separation membrane element 1 is immersed in the water 8. If the pH of the water 8 is less than 4, the zeolite crystals may be decomposed compared to the case where the pH of the water 8 is in the above range. If the pH of the water 8 exceeds 9, the water 8 Compared with the case where the pH is in the above range, the deposits inside the separation membrane element 1 tend not to be sufficiently eluted.

  In the immersion step, it is preferable that the separation membrane element 1 is immersed in the water 8 for 6 to 72 hours. When the immersion time is less than 6 hours, the immersion is insufficient as compared with the case where the immersion time is in the above range, and the above-described effects tend not to be obtained. When the immersion time exceeds 72 hours, the immersion is performed. Compared to the case where the time is in the above range, the zeolite crystals may be decomposed.

  In the dipping step, the temperature of the water 8 described above is preferably 80 ° C. or less, and more preferably 20 to 80 ° C. When the temperature is 80 ° C. or lower, even if the deposits are relatively large crystals, the characteristics of the zeolite membrane such as the permeation flux Q and the separation performance α are not deteriorated as compared with the case where the temperature exceeds 80 ° C. It is possible to elute more fully.

  In addition, when the temperature of the water 8 exceeds 80 ° C., the zeolite crystals are decomposed in a short time, there is a possibility that sufficient characteristics of the zeolite membrane may not be obtained, and when the temperature is less than 20 ° C., The elution of impurities tends to be delayed.

  In the immersion step, it is preferable to circulate the water 8 in the container 10 from the non-flowing state with a motor, a stirrer, or the like while the separation membrane element 1 is immersed. In this case, since the pH of the water 8 is suppressed from being locally increased, the deposits inside the separation membrane element body 1 can be more effectively removed. Further, when the separation membrane element 1 is hollow, it is preferable to circulate so that the water 8 enters the hollow portion of the separation membrane element 1. In this case, the deposits can be sufficiently removed from the hollow portion of the separation membrane element body 1.

  According to the method for producing a zeolite separation membrane, zeolite separation membranes having various compositions and structures such as MFI type, X type, Y type, A type, and T type can be produced on the surface of the support. Since the zeolite separation membrane thus obtained is obtained by the above-described method for producing a zeolite separation membrane, it is possible to suppress contamination of impurities derived from the raw material of the zeolite membrane into the organic solvent.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  For example, in the above embodiment, the seed attachment step is optional and is not necessarily an essential step in the present invention. In addition, when not performing a seed adhesion process, a support element | base_body becomes a support body.

  Moreover, in this embodiment, you may further provide the cooling process which cools a zeolite membrane element body after the said isolation | separation process. By performing the cooling step in this way, it is difficult to dry the zeolite membrane body and it is possible to suppress the deposit from solidifying.

  In addition, if it is after a separation process, the said cooling process may be performed simultaneously with a washing | cleaning process, and may be performed between a separation process and a washing | cleaning process. When performing a cooling process and a washing | cleaning process simultaneously, a liquid is made into the water of low temperature (for example, 10 to 40 degreeC), and it wash | cleans, cooling a zeolite membrane body with a liquid. In this case, since the number of steps can be reduced, the working time can be shortened. Further, when the cooling step is performed between the separation step and the washing step, for example, in a container storing the reaction solution, the reaction solution is extracted from the state in which the zeolite membrane element is immersed in the reaction solution, and cooled. Pure water is introduced. Thereby, the reaction liquid adhering to the zeolite membrane element is diluted, and the ratio of the reaction liquid mixed in the liquid in the washing step can be reduced.

  In the cooling step, the method for cooling the zeolite membrane is not particularly limited. Examples of the cooling method include a method of immersing the zeolite membrane element in water, a method of spraying water onto the zeolite membrane element, and a method of dropping water onto the zeolite membrane element.

  In the above embodiment, in the immersion step, the water 8 is stored in the container 10 and the separation membrane element 1 is immersed in the non-flowing water 8. At this time, the water 8 is in a fluid state. Good,

  In addition, as shown in FIG. 1, in the present embodiment, three separation membrane elements 1 are immersed, but the number of separation membrane elements 1 to be immersed is not limited to three, but one or two. There may be four or more. In this case, the number of grooves 5 of the support tray 3 is made to correspond to the number of separation membrane elements 1 to be arranged. In the present embodiment, the separation membrane element 1 is disposed on the support tray 3. However, one end of the separation membrane element 1 is supported by a support and suspended from above the container 10. It may be immersed in water 8. At this time, the separation membrane element 1 is immersed in the water 8 so that the entire separation membrane element 1 is not brought into contact with the other separation membrane element 1 or the wall of the container 10 except for one end to be supported. It is preferable to do so.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to the Example given below.

Example 1
[Seed adhesion process]
A type A zeolite fine particles (seed crystals, average particle size 300 nm) were placed in water and stirred to prepare a solution having a concentration of 0.5 mass%. A tubular porous support body (average pore diameter 1.3 μm, outer diameter 10 mm, inner diameter 6 mm, length 13 cm) made of α-alumina is immersed in this solution for 3 minutes and then pulled up at a rate of about 0.2 cm / s. It was. This was dried in a constant temperature bath at 25 ° C. for 2 hours and then dried in a constant temperature bath at 70 ° C. for 16 hours to obtain a support.

[Film body forming process]
Next, 1 mol part of alumina (Al ₂ O ₃ ), 2 mol parts of silicon dioxide (SiO ₂ ), and 2 mol parts of sodium oxide (Na ₂ O) were added to 150 mol parts of water to obtain a reaction solution. The support was immersed in this reaction solution and held at 100 ° C. for 3 hours to form a zeolite membrane on the surface of the support.

[Washing process]
Next, the zeolite membrane was washed by hand washing with a non-woven fabric of PVA and dried.

[Immersion process]
Then, as shown in FIG. 1, the separation membrane element 1 on which the zeolite membrane element is formed is arranged in the groove 5 of the support tray 3 arranged at the bottom of the container 10, and water 8 is put into the container 10. . Then, the separation membrane element 1 was immersed in water 8 for 19 hours. In addition, the water 8 at this time used the pure water of 40 degreeC, and the water 8 was made into the non-flowing state during immersion. In this way, a zeolite separation membrane having a zeolite membrane formed on the surface of the support was obtained.

(Comparative Example 1)
In Example 1, a zeolite separation membrane in which a zeolite membrane was formed on the surface of the support was obtained in the same manner as in Example 1 except that the dipping process was not performed.

(Evaluation methods)
[Separation performance and permeation flux]
Two zeolite separation membranes obtained in Example 1 and Comparative Example 1 were prepared, and a pervaporation (PV) test apparatus shown in FIG. 2 was assembled in order to evaluate the separation performance. This PV test apparatus has a supply tank 21 to which a supply liquid A is supplied. A pipe 31 for supplying the supply liquid A to the supply tank 21 is connected to the supply tank 21, and a separator 22 is installed in the supply tank 21 and a stirring device 32 for stirring the supply liquid A is provided. ing. As the separator 22, the zeolite separation membranes of Example 1 and Comparative Example 1 were used. A tube 16 is connected to the open end of the separator 22, and a vacuum pump 24 is connected to the end of the tube 16 via a liquid nitrogen trap 23. A vacuum gauge 25 is attached in the middle of the tube 16.

  A supply liquid A (water / ethanol mass ratio = 10/90) at 75 ° C. is supplied to the supply liquid container 21 of this PV test apparatus through a pipe 31 and the inside of the separator 22 is sucked by a vacuum pump 24 (vacuum gauge). 25 degree of vacuum: 10 to 1000 Pa). The liquid B that passed through the separator 22 was collected by a liquid nitrogen trap 23. The composition of the supply liquid A and the permeate B was measured using a gas chromatograph (trade name: GC-14B, manufactured by Shimadzu Corporation) to determine the separation performance α. Further, the weight of the collected liquid was measured, and the permeation flux Q was determined based on the weight, membrane area, and collection time. The obtained results are shown in Table 1.

[Sodium concentration measurement]
100 ml of a mixed solvent of 90% ethanol and 10% water was prepared, and PV measurement was performed at 75 ° C. for 5 hours using the zeolite separation membranes of Example 1 and Comparative Example 1. Thereafter, the concentration of sodium in the alcohol was calculated using an ICP / MASS measuring apparatus (CIROS-120 manufactured by SPECTRO, inductively coupled plasma optical emission spectrometer). The obtained results are shown in Table 1.

  From the results of Example 1 and Comparative Example 1 above, it was found that according to the zeolite separation membrane of the present invention, the sodium concentration in the alcohol can be sufficiently reduced without lowering the permeation flux and the separation performance. From this, it was confirmed that according to the method for producing a zeolite separation membrane of the present invention, a zeolite separation membrane capable of sufficiently suppressing the mixing of sodium into the organic solvent can be obtained.

FIG. 1 is a perspective view showing an immersion apparatus in the immersion process of the present embodiment. FIG. 2 is a schematic diagram showing the pervaporation (PV) test apparatus used in Example 1 and Comparative Example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Separation membrane element, 3 ... Support tray, 5 ... Groove, 8 ... Water, 10 ... Container, 16, 31 ... Pipe, 21 ... Feed tank, 22 ... Separator, 23 ... Liquid nitrogen trap, 24 ... Vacuum pump 25 ... Vacuum gauge, 32 ... Stirrer, 100 ... Dipping device.

Claims (4)

In a method for producing a zeolite separation membrane comprising a support and a zeolite membrane provided on the support,
A membrane element forming step of bringing the support into contact with a reaction solution containing a raw material of the zeolite membrane, and forming a zeolite membrane element comprising zeolite crystals on the surface of the support;
A washing step for washing the zeolite membrane element;
A step of immersing the zeolite membrane body in water after the washing step to obtain the zeolite membrane, and a method for producing a zeolite separation membrane.   The method for producing a zeolite separation membrane according to claim 1, wherein in the immersion step, the zeolite membrane body is immersed in water for 6 to 72 hours.   3. The method for producing a zeolite separation membrane according to claim 1, wherein the temperature of the water is 80 ° C. or less in the dipping step. A zeolite separation membrane obtained by the method for producing a zeolite separation membrane according to any one of claims 1 to 3.

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