Method for manufacturing zeolite membranes

Abstract

To provide a zeolite membrane capable of reducing the transmission amount of a component relatively lower in permeability in a mixture, in separation by a molecular sieve effect of the mixture using an untreated zeolite membrane.SOLUTION: A method of manufacturing a zeolite membrane according to the present invention includes a step of bringing a dehydration-condensation reaction accelerator into contact with an untreated zeolite membrane.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for producing a zeolite film. [Background technology]

[0002] Zeolite membranes are used as separation membranes to separate and remove water from aqueous solutions of organic compounds. One known method for producing zeolite membranes is to form them by hydrothermal synthesis in the presence of seed crystals without using an organic template (see, for example, Patent Document 1). In this method, a calcination step to remove the organic template after film formation is unnecessary, thus yielding an uncalcined zeolite membrane. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2015 / 159986 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, in the conventional techniques described above, when separating and removing water-soluble organic compounds by contacting an aqueous solution containing water-soluble organic compounds with a zeolite membrane and allowing water to permeate through, the inventors have found that a large amount of water-soluble organic compounds may permeate along with the water to be separated. In other words, in membrane separation using the molecular sieving effect of a zeolite separation membrane to separate a mixture of a relatively permeable component from a relatively permeable component from a mixture of a relatively permeable component and a relatively permeable component, the inventors have found that a large amount of the relatively permeable component may permeate through. When the amount of the relatively permeable component that is accompanied by the separation increases in this way, the separation efficiency decreases.

[0005] One aspect of the present invention aims to realize a zeolite membrane capable of reducing the permeation amount of a component with relatively low permeability in a mixture in the separation of the mixture by the molecular sieve effect of an untreated zeolite membrane.

Means for Solving the Problems

[0006] In order to solve the above problems, a method for manufacturing a zeolite membrane according to one aspect of the present invention includes a step of bringing a dehydration condensation reaction accelerator into contact with an unfired zeolite membrane.

Effects of the Invention

[0007] According to one aspect of the present invention, in the separation of a mixture by the molecular sieve effect of an untreated zeolite membrane, a zeolite membrane capable of reducing the permeation amount of a component with relatively low permeability in the mixture can be realized.

Brief Description of the Drawings

[0008] [Figure 1] It is a diagram schematically showing the configuration of an apparatus using an unfired zeolite membrane in an embodiment for pervaporation.

Modes for Carrying Out the Invention

[0009] Hereinafter, one embodiment of the present invention will be described.

[0010] 〔Contact Step〕 A method for manufacturing a zeolite membrane according to one aspect of the present invention includes a step of bringing a dehydration condensation reaction accelerator into contact with an unfired zeolite membrane (hereinafter, also referred to as the "contact step"). In the contact step, bringing a dehydration condensation reaction accelerator into contact with an unfired zeolite membrane means allowing the dehydration condensation reaction accelerator to act on at least the surface of the unfired zeolite membrane. The contact can be carried out by passing the dehydration condensation reaction accelerator through the unfired zeolite (for example, by liquid passing, air passing, etc.), or by immersing the unfired zeolite in the dehydration condensation reaction accelerator or allowing the dehydration condensation reaction accelerator to flow down on the surface of the unfired zeolite.

[0011] [Untreated zeolite membrane] An untreated zeolite film in one aspect of the present invention is a zeolite film that has not undergone a treatment process. The treatment process is a process in which, after the process, the amount of relatively low permeability components that permeate the zeolite film is reduced compared to before the process. Specifically, it is a process of performing one or more operations such as heating, calcination, surface treatment, and contact with a dehydration condensation reaction accelerator. Although the detailed mechanism is speculative, it is thought that the amorphous portion contained in the untreated zeolite film reacts, reducing the amount of relatively low permeability components that permeate through the amorphous portion.

[0012] Heating is a step of heating the zeolite membrane to a temperature that satisfies the conditions of the steps described above. The heating temperature is 120°C or higher, preferably 150°C or higher, and more preferably 200°C or higher. From the viewpoint of preventing damage due to the difference in thermal expansion coefficient between the separation membrane and the substrate (support), it is preferably 900°C or lower, more preferably 850°C or lower, even more preferably 800°C or lower, particularly preferably 750°C or lower, and most preferably 500°C or lower.

[0013] Firing involves heating the zeolite film to a temperature at which the organic template agent, when synthesized using an organic template agent, is thermally decomposed to a size that allows it to pass through the pores of the zeolite, thereby removing it. From the viewpoint of sufficiently removing the organic template agent, the firing temperature is preferably 350°C or higher, more preferably 400°C or higher, even more preferably 430°C or higher, and particularly preferably 450°C or higher. From the viewpoint of preventing fracture due to the difference in thermal expansion coefficient between the separation membrane and the substrate (support), the temperature is preferably 900°C or lower, more preferably 850°C or lower, even more preferably 800°C or lower, particularly preferably 750°C or lower, and most preferably 500°C or lower. From the viewpoint of sufficiently removing the organic template agent, the firing time is preferably 24 hours or more, and from the viewpoint of productivity, it is preferably 72 hours or less. Surface treatment is treatment with a compound such as a silane coupling agent.

[0014] The untreated zeolite membrane may be a manufactured product or a commercially available product. The untreated zeolite membrane as a manufactured product is, for example, a zeolite membrane that is synthesized without using an organic template agent that regulates the crystal structure of zeolite and has not been calcined. Also, the untreated zeolite membrane as a manufactured product is a zeolite membrane that is synthesized using an organic template agent and the organic template agent has been removed by an oxidizing agent and has not been calcined. The untreated zeolite membrane can be manufactured by hydrothermal synthesis, and more specifically, it can be manufactured by, for example, the method described in Patent Document 1.

[0015] The contact with the dehydration condensation reaction accelerator is as described below.

[0016] The crystal structure in the untreated zeolite membrane is not limited and can be appropriately selected from various known structures. Examples of the crystal structure include chabazite (CHA), faujasite (FAU) and A-type (LTA), MFI, MER, MOR, EMT, SOD, CAN, JBW, HEU, BRE, ABW, ANA, BEA, MTW, NES, LEV, MAZ, MEL, MSE, MTT, MTW, PAU, RTH, SZR, TON, VET. The untreated zeolite membrane can generally be manufactured by hydrothermal synthesis, and can be manufactured by, for example, the method described in Patent Document 1 mentioned above.

[0017] The cation used in hydrothermal synthesis is not limited. Examples of the cation include K + , 2+ , + , <00,00123>, + , , + , 2+ ,

[0018] , 2+ , + , Na + , Li + , Rb + , Cs + , Sr 2+ and Ca 2+ are included.

[0018] The untreated zeolite membrane has K + , Na + , Li + , Rb + , Cs + , Sr 2+ and Ca 2+It may contain as a counter cation. Amorphous portion contains AlO2 - It is a nearby counter-cation. K + kaNa + Li + , Rb + , Cs + Sr 2+ and Ca 2+ When it contains as a counter cation, K + kaNa + Li + , Rb + , Cs + Sr 2+ and Ca 2+ It may be incorporated into the untreated zeolite film by using it as a cation, or it may be incorporated by performing cation exchange after hydrothermal synthesis.

[0019] [Dehydration condensation reaction accelerator] In one aspect of the present invention, the dehydration condensation reaction accelerator is a component that promotes the dehydration condensation reaction in an untreated zeolite membrane. The dehydration condensation reaction in an untreated zeolite membrane will be described later. The dehydration condensation reaction accelerator can be in any form that allows for sufficient contact with the untreated zeolite membrane. Examples of forms of the dehydration condensation reaction accelerator include liquids, gases, solutions, and supercritical fluids. By bringing the dehydration condensation reaction accelerator into contact with the untreated zeolite membrane, the amount of water-soluble organic compounds that permeate through the untreated zeolite membrane when it is used for the concentration of water-soluble organic compounds can be reduced.

[0020] Ethanol is a specific example of a dehydration condensation reaction accelerator. Ethanol may also be used in aqueous solution. When an aqueous solution of ethanol is used as a dehydration condensation reaction accelerator, the ethanol content in the aqueous solution is preferably 90% by volume or more, more preferably 95% by volume or more, and even more preferably 97% by volume or more, from the viewpoint of sufficiently reducing the amount of water-soluble organic compounds that permeate the untreated zeolite membrane.

[0021] When ethanol is used as a dehydration condensation reaction accelerator, the temperature can be appropriately determined within a range that allows sufficient treatment of the untreated zeolite film by contact. From the viewpoint of shortening the treatment time by contact with the untreated zeolite film, the temperature of the ethanol used as a dehydration condensation reaction accelerator is preferably 25°C or higher, more preferably 50°C or higher, even more preferably 75°C or higher, particularly preferably 90°C or higher, and most preferably 100°C or higher. Furthermore, from the viewpoint of suppressing thermal decomposition of the untreated zeolite film, the temperature of the ethanol is preferably 135°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower. The above temperature range is the temperature under conditions of atmospheric pressure or higher.

[0022] Another specific example of a dehydration condensation reaction accelerator is carbon dioxide. Carbon dioxide can be used in a fluid state and is preferably used as a gas or supercritical fluid. When using carbon dioxide as a dehydration condensation reaction accelerator, the conditions can be appropriately determined from the range that allows sufficient treatment of the untreated zeolite film by contact and the state of the carbon dioxide. For example, when carbon dioxide is a gas, it is preferable to use dry carbon dioxide, and it is preferable to use commercially available dry gas. From the above viewpoint, the temperature of the carbon dioxide should be above dry room temperature, and is preferably 100°C or higher. Using heated carbon dioxide is preferable because, although this is hypothetical, it increases the rate of the dehydration condensation reaction of the silanol groups of the amorphous portion or the dissociated silanol groups, and it eliminates the need for an additional drying step. In particular, when a potassium salt is used as the base when synthesizing the zeolite, the potassium carbonate produced by the reaction with carbon dioxide has low water solubility, so it is preferable to increase the reaction rate to rapidly increase the concentration of potassium carbonate and exceed the saturation concentration earlier. Furthermore, if carbon dioxide is a supercritical fluid, the temperature and pressure should be above the critical point. From the viewpoint of simplifying the equipment, it is preferable to use carbon dioxide as a gas, and the pressure should preferably be less than 1 MPa. In addition, carbon dioxide may be used as a mixed gas with a gas that is inert to the untreated zeolite membrane, such as nitrogen.

[0023] The dehydration condensation reaction accelerator can also be determined according to the type of countercation in the amorphous portion present in the untreated zeolite film. In this case, the dehydration condensation reaction accelerator can be selected to be a component that reacts with the countercation to produce a salt that is poorly soluble in water, or a salt of an acid that is stronger than silicic acid.

[0024] For example, NaF and sodium urate are examples of salts that are poorly soluble in water. Therefore, the counter cation is Na +In such cases, using a dehydration condensation reaction accelerator that forms NaF or sodium urate makes it easier to carry out an irreversible dehydration condensation reaction and maintain a state in which the permeate amount of water-soluble organic compounds is reduced. Another specific example of a dehydration condensation reaction accelerator is a fluoride solution or a fluorocomplex solution. Examples of fluoride solutions or fluorocomplex solutions include aqueous solutions of fluoride or fluorocomplexes. An example of a compound containing a fluorocomplex is Na2SiF6. The amount of fluoride used and the applicable temperature may also be appropriately determined from the above viewpoint. When using Na2SiF6, the zeolite film is immersed in a saturated aqueous solution of Na2SiF6 at room temperature for a certain period of time and then dried.

[0025] Furthermore, the counter cation is Na + In this case, uric acid solution can be cited as another specific example of a dehydration condensation reaction accelerator. The concentration and application temperature of the uric acid solution may be determined appropriately from the viewpoint of ensuring sufficient treatment of the untreated zeolite membrane by contact. When using uric acid solution, the zeolite membrane is immersed in a saturated aqueous solution of uric acid with warm water for a certain period of time, and then heated and dried.

[0026] [Other processes] A method for producing a zeolite film according to one aspect of the present invention may further include other steps besides the contact step described above, to the extent that the effects of the present invention can be obtained. An example of other steps is a step of growing zeolite crystals by hydrothermal synthesis to produce an untreated zeolite film (hereinafter also referred to as the "production step").

[0027] [Generation process] The production process can be carried out by known methods for producing the aforementioned untreated zeolite film. The production process may be carried out prior to the aforementioned contact process. Examples of the production process include a step of growing zeolite crystals without using an organic template compound to produce an untreated zeolite film, and a step of growing zeolite crystals in the presence of an organic template compound, and then treating the resulting zeolite film with an oxidizing agent to remove the organic template compound from the zeolite film to produce an untreated zeolite film. The former can be carried out by a method such as that described in Patent Document 1 mentioned above. The latter can be carried out by a method such as that described in "Microporous and Mesoporous Materials 2005, 87, 45-51."

[0028] The above-mentioned organic template compounds are organic compounds that serve as templates for regulating the crystal structure of zeolites. When using organic template compounds in the production process, the organic template compound can be appropriately selected from compounds known as templates in the production of zeolite films, depending on the desired crystal structure of the zeolite film. Examples of organic template compounds include organic amines, and more specifically, N,N,N-trimethylammonium compounds, N,N,N-tripropylammonium compounds, and N,N,N-trimethyladamantanammonium compounds.

[0029] Furthermore, the oxidizing agent used to treat the organic template compound is a component that acts on the organic template compound in the crystal structure of the zeolite film, decomposing the compound and making it removable from the zeolite film. The oxidizing agent can be appropriately selected from components known to decompose the organic template compound in the crystal structure of the zeolite film during its production. Examples of oxidizing agents include ozone and atomic oxygen obtained by irradiating ozone with ultraviolet light. The conditions for using the oxidizing agent should be such that the dehydration condensation reaction of the silanol group does not proceed completely.

[0030] [Consideration] According to a manufacturing method in one aspect of the present invention, an untreated zeolite membrane can be obtained that reduces the amount of water permeate from an aqueous solution of a water-soluble organic compound when separating and removing water from the aqueous solution using the untreated zeolite membrane. The reason for this is not entirely clear, but it is thought to be as follows.

[0031] In hydrothermal synthesis, the reaction does not proceed until amorphous moieties grow within the zeolite film to form a zeolite cage, and unreacted regions (where the T atom is Si and the countercation is K) remain within the zeolite film. + In this case, the Si-OK (where T is the central atom of the tetrahedral substructure in the zeolite framework) remains, and this unreacted portion is thought to become a channel for organic compounds during subsequent use.

[0032] In one aspect of the present invention, in the aforementioned contact step, a dehydration condensation reaction accelerator is brought into contact with the untreated zeolite film. Since the permeation of water-soluble organic compounds is suppressed by contact with the dehydration condensation reaction accelerator, it is considered that the reaction proceeds in the rightward direction shown in the following equation during the contact step.

[0033] [ka]

[0034] Thus, it is thought that in the unreacted region, the silanol group becomes a siloxane bond through dehydration condensation. Since the siloxane bond site cannot become a channel for the water-soluble organic compound mentioned above, it is thought that the amount of water-soluble organic compound permeate is reduced.

[0035] It is thought that because ethanol has a low dielectric constant, the stability of the silanol group is higher than that of the Si-OK group, and that ethanol absorbs water to form a siloxane bond.

[0036] It is thought that carbon dioxide reacts in the untreated zeolite film in a similar manner to how molds for iron are made, where water glass and sand are mixed and carbon dioxide gas is blown in to solidify them. In other words, it is thought that when carbon dioxide comes into contact with the untreated zeolite film, it neutralizes the weakly basic Si-OK group as carbonic acid, forming a weaker basic silanol group with potassium carbonate, and as a result, the reaction proceeds to the right in the above reaction equation.

[0037] It is thought that the fluoride solution reacts in the untreated zeolite film in a similar manner to when water glass is cured with NaSiF6 to form an adhesive, generating a countercation salt, similar to carbon dioxide, and allowing the reaction to proceed from right to left in the above reaction equation. Furthermore, the countercation is Na + In this case, since an insoluble salt is formed with the countercation, the above reaction equation is considered to be an irreversible reaction.

[0038] It is thought that uric acid solution, like carbon dioxide and fluoride solutions, also generates a countercation salt and allows the reaction in the rightward direction of the above reaction equation to proceed. Furthermore, urine spray, like fluoride solutions, also generates a countercation Na + In this case, it is thought that the formation of an insoluble salt with the countercation prevents the leftward reaction in the above reaction equation.

[0039] 〔summary〕 As is clear from the above description, a method for producing a zeolite membrane according to one aspect of the present invention includes a step of contacting an untreated zeolite membrane with a dehydration condensation reaction accelerator. Therefore, according to one aspect of the present invention, a zeolite membrane capable of reducing the permeation of water-soluble organic compounds can be realized when separating and removing water from an aqueous solution of a water-soluble organic compound using an untreated zeolite membrane.

[0040] In one embodiment of the present invention, ethanol may be used as the dehydration condensation reaction accelerator. This configuration is even more effective from the viewpoint of easily preventing the permeation of organic compounds.

[0041] In one embodiment of the present invention, an aqueous ethanol solution containing 95% by volume or more of ethanol may be used as the dehydration condensation reaction accelerator. The volume percentage is the value at 20°C. If it is 95% by mass or more, it means 95% by volume or more. This configuration is even more effective from the viewpoint of sufficiently preventing the permeation of water-soluble organic compounds through the zeolite membrane and from the viewpoint of making the separation membrane that has undergone the dehydration condensation reaction usable in fields where safety is required, such as food applications.

[0042] When ethanol is used as the dehydration condensation reaction accelerator, the temperature of the dehydration condensation reaction accelerator may be 25°C or higher. This configuration is even more effective in shortening the contact process time and increasing productivity.

[0043] When ethanol is used as a dehydration condensation reaction accelerator, the temperature of the accelerator may be 120°C or lower. This configuration is even more effective from the standpoint of accelerating the reaction and being economical.

[0044] In one embodiment of the present invention, carbon dioxide may be used as the dehydration condensation reaction accelerator. This configuration is even more effective in terms of sufficiently preventing the permeation of water-soluble organic compounds through the zeolite membrane.

[0045] When carbon dioxide is used as a dehydration condensation reaction accelerator, the carbon dioxide may be in gaseous form. This configuration is even more effective because it allows for easy prevention of permeation of water-soluble organic compounds, simplifies the equipment by eliminating the use of flammable materials in the work process, and allows the manufactured separation membrane to be used in fields requiring safety, such as food applications.

[0046] When carbon dioxide is used as a dehydration condensation reaction accelerator, the carbon dioxide may be in a supercritical state. This configuration is expected to improve both the diffusion and action of carbon dioxide, making it even more effective in terms of improving the effects of the aforementioned contact process and increasing productivity by shortening the contact process time.

[0047] In one embodiment of the present invention, prior to the contact step, a step is further included in which zeolite crystals are grown by hydrothermal synthesis to produce an untreated zeolite film, wherein the untreated zeolite film is Na + or K + The material may contain a countercation, and in the contact step, a compound that forms a water-insoluble salt with the countercation may be used as a dehydration condensation reaction accelerator. This configuration is expected to prevent the reconfiguration of the flow path of organic compounds, and is therefore even more effective in suppressing unintended permeation of water-soluble organic compounds when using an untreated zeolite membrane.

[0048] The process further includes a generation step, in which the counter cation is Na + In this case, a fluoride solution may be used as the dehydration condensation reaction accelerator, or uric acid solution may be used as the dehydration condensation reaction accelerator. This configuration is even more effective in suppressing the unintended permeation of water-soluble organic compounds when using the untreated zeolite membrane in the above case.

[0049] If the process further includes a production step, the production step may be a step of growing zeolite crystals without using an organic template compound, which is a template agent that regulates the crystal structure of the zeolite, in order to produce an untreated zeolite film. Alternatively, if the process further includes a production step, the production step may be a step of growing zeolite crystals in the presence of an organic template compound, which is a template agent that regulates the crystal structure of the zeolite, and then treating the resulting zeolite film with an oxidizing agent to remove the organic template compound from the film in order to produce an untreated zeolite film. This configuration does not require calcination, and is therefore more effective than methods for producing zeolite films that require calcination, from the standpoint of increasing the productivity of zeolite films and saving labor.

[0050] In one aspect of the present invention, an untreated zeolite membrane is obtained in which the change in the permeate amount of water-soluble organic compounds is reduced. Therefore, one aspect of the present invention is expected to contribute to the dissemination and development of technologies using zeolite membranes and to the achievement of the Sustainable Development Goals (SDGs) related to industry and technological innovation.

[0051] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Examples]

[0052] The present invention will be described in more detail by examples, but the present invention is not limited to the following examples unless it exceeds the essence of the invention.

[0053] In the following examples, the particle size distribution, air permeability, and vaporization performance of the seed crystals were measured by the following methods.

[0054] The dispersion for measuring the particle size distribution of seed crystals was prepared by adding water to the ultrasonic dispersion bath of the measuring device, stirring it with a stirrer, circulating the dispersion through a flow cell, and adding seed crystals to the water in the ultrasonic dispersion bath until the intensity of the light transmitted through the dispersion fell within the appropriate light intensity range displayed on the device. Typically, the amount of water used as the dispersion solvent was 250 mL, and the amount of seed crystal dispersed was typically 0.01 g. When using powdered seed crystals, the dispersion was subjected to ultrasonic waves for 5 minutes to remove aggregated seed crystals before measurement. Measurements were performed using a flow method. From the obtained data, the primary particle values ​​D10, D50, and D90 were acquired.

[0055] [Measurement of secondary particle size] The secondary particle size of the seed crystal was measured under the following conditions. • Device name: ELSZ-2000ZS (manufactured by Otsuka Electronics Co., Ltd.) • Measurement method: Dynamic light scattering method Measurement range: 0.02~44.3μm • Light source: High-power semiconductor laser • Detector: High-sensitivity APD • Dispersing solvent: Water From the obtained data, the median diameter of the secondary particle size was acquired.

[0056] [Air permeability] A cylindrical porous support-zeolite membrane composite, in which an untreated zeolite membrane is supported on the surface of a porous support, is sealed at one end, and the other end is connected to a 5 kPa vacuum line in a sealed state. The airflow rate is measured using a mass flow meter installed between the vacuum line and the porous support-zeolite membrane composite, and the air permeability [L / (m³] is measured. 2 The following was used: ·h). A KOFLOC 8300 mass flow meter for N2 gas with a maximum flow rate of 500 mL / min (at 20°C and 1 atm) was used as the mass flow meter. When the mass flow meter reading on the KOFLOC 8300 was 10 mL / min (at 20°C and 1 atm) or less, a Lintec MM-2100M mass flow meter for air gas with a maximum flow rate of 20 mL / min (at 0°C and 1 atm) was used for measurement.

[0057] [Pervaporation performance measurement] Performance measurements using a porous support-zeolite membrane composite by pervaporation were performed under the following conditions, by selectively permeating water from a 100°C water / ethanol aqueous solution (5 / 95 mass%) which was the liquid to be treated.

[0058] A schematic diagram of the apparatus used in the pervaporation method is shown in Figure 1. As shown in Figure 1, the apparatus comprises a raw material tank 1 containing an aqueous solution of organic compounds as raw materials, a membrane module 2 containing a porous support-zeolite membrane composite, and a vacuum pump 3 connected to the membrane module 2. A measuring trap 4 is connected between the membrane module 2 and the vacuum pump 3.

[0059] The membrane module 2 comprises a metal cylinder, a connecting member connected to one end of the cylinder (the side facing the measurement trap 4), and a sealing member that can be opened and closed to seal the other end of the cylinder. The membrane module 2 houses a porous support-zeolite membrane composite. One end of the porous support-zeolite membrane composite is connected to the connecting member, and the space on the inner circumference side of the porous support-zeolite membrane composite is isolated from the space on the outer circumference side of the porous support-zeolite membrane composite, and is in communication with the measurement trap 4 via the connecting member. The other end of the porous support-zeolite membrane composite is sealed.

[0060] The raw material tank 1 is configured to supply raw materials to the membrane module 2 via the supply tank 5 and the heater 6. Furthermore, the raw materials within the membrane module 2 are configured to be returned to the supply tank 5 or to the raw material tank 1 via the cooler 7. The raw materials are also configured to circulate between the supply tank 5 and the heater 6. Additionally, the raw materials returned from the cooler 7 to the raw material tank 1 are configured to be sampled. Pumps P1 and P2 and valves V1 to V12 are appropriately placed in the flow path of the apparatus.

[0061] [Example of manufacturing a porous support-zeolite membrane composite] 37.6 g of aluminum hydroxide (containing 53.5% by mass of Al2O3, manufactured by Aldrich), 243.0 g of 25 wt% KOH aqueous solution, and 1910.2 g of water were added and mixed and stirred to dissolve the mixture. 232.5 g of colloidal silica (Nissan Chemical Corporation, Snowtec-40) was added to this and stirred for 2 hours to obtain an aqueous reaction mixture. The composition (molar ratio) of this aqueous reaction mixture was SiO2 / Al2O3 / KOH / H2O = 1 / 0.125 / 0.7 / 80 / and SiO2 / Al2O3 = 8.

[0062] As the inorganic porous support, a porous alumina tube (outer diameter 12 mm, inner diameter 9 mm, length 1200 mm) was used. The average pore size of this porous alumina tube was 1.3 μm, and the porosity was 42%.

[0063] FAU-type zeolite was obtained by mixing 10.0 g of proton-type Y-type zeolite (HY (SAR=5), manufactured by Shokubai Kasei Kogyo Co., Ltd.) with 5.00 g of NaOH and 100 g of water, heating the mixture at 100°C for 7 days, filtering, washing with water, and drying. The volume-based particle size distribution of this FAU-type zeolite was measured, and D 50 The average particle size was 1.73 μm, with maximum values ​​of 1.32 μm and 2.98 μm (particle size: approximately 2 μm).

[0064] This FAU-type zeolite was used as a seed crystal. The seed crystal was dispersed in water at a concentration of 2% by mass. The support material was then immersed in this solution for a predetermined time, and subsequently dried at 100°C for at least 5 hours to allow the seed crystal to adhere. The mass of the attached seed crystal was 3 g / m². 2 That was the case.

[0065] A support with seed crystals attached was immersed vertically in a 200 ml Teflon® inner cylinder containing the aqueous reaction mixture, the autoclave was sealed, and the temperature was raised from room temperature to 180°C over 5 hours. After the temperature was raised, it was heated at 180°C for 24 hours under self-sustaining pressure. After the predetermined time had elapsed, it was allowed to cool, the porous support-zeolite membrane composite was removed from the aqueous reaction mixture, washed, and dried at 100°C for 4 hours. In this way, a porous support-zeolite membrane composite was obtained in which an untreated CHA-type zeolite membrane was supported on the outer surface of the porous support.

[0066] [Comparative Example] A permeation vaporization performance test was conducted on the porous support-zeolite membrane composite obtained in the above manufacturing example. The "porous support-zeolite membrane composite obtained in the above manufacturing example" corresponds to an untreated zeolite membrane that has not been "contacted with a dehydration condensation reaction accelerator". The aforementioned permeation vaporization performance test was performed on this. The result was a water permeation flux (Qw) of 3236 [g / m³]. 2 ·h], the permeate flux (Qa) of ethanol is 256 [g / m³]. 2 The result was [h]. The results are shown in Table 1.

[0067] [Examples] A permeation vaporization performance test was performed on the porous support-zeolite membrane composite after use in the control example. The "porous support-zeolite membrane composite after use in the control example" is a porous support-zeolite membrane composite that has been in contact once with the treated liquid, a 100°C water / ethanol aqueous solution (5 / 95 mass%), in the permeation vaporization performance test. The aforementioned permeation vaporization performance test was performed on this porous support-zeolite membrane composite. The result was a water permeation flux (Qw) of 3372 [g / m³]. 2 ·h], the permeate flux (Qa) of ethanol is 102 [g / m³]. 2 The result was [h]. The results are shown in Table 1.

[0068] [Table 1]

[0069] As shown in Table 1, the porous support-zeolite membrane composite that had never been in contact with a 100°C water / ethanol aqueous solution (5 / 95 mass%) showed a high amount of ethanol permeation compared to the control example. On the other hand, the examples showed that the porous support-zeolite membrane composite that had been in contact with a 100°C water / ethanol aqueous solution (5 / 95 mass%) showed a significant reduction in ethanol permeation. Thus, it was found that by contacting the above water / ethanol aqueous solution, the water permeation flux Qw remained substantially the same, while the ethanol permeation flux Qa after ethanol treatment decreased significantly, thus increasing the ethanol recovery rate. [Industrial applicability]

[0070] This invention can be used to produce zeolite membranes that exhibit low permeability of relatively less permeable components in the separation of water-soluble organic compounds and water mixtures. [Explanation of symbols]

[0071] 1. Raw material tank 2 membrane modules 3. Vacuum pump 4. Measuring trap 5. Supply Tank 6 Heater 7 Cooler P1, P2 pumps V1~V12 valves

Claims

1. A method for producing a zeolite film, comprising the step of contacting an untreated zeolite film containing countercations with a dehydration condensation reaction accelerator.

2. The method for producing a zeolite film according to claim 1, wherein the dehydration condensation reaction accelerator contains ethanol.

3. The method for producing a zeolite membrane according to claim 2, wherein the dehydration condensation reaction accelerator is an aqueous ethanol solution containing 95% by volume or more of ethanol.

4. The method for producing a zeolite film according to claim 2 or 3, wherein the temperature of the dehydration condensation reaction accelerator is 25°C or higher.

5. A method for producing a zeolite film according to any one of claims 2 to 4, wherein the temperature of the dehydration condensation reaction accelerator is 120°C or lower.

6. The method for producing a zeolite membrane according to claim 1, wherein the dehydration condensation reaction accelerator contains carbon dioxide.

7. The method for producing a zeolite film according to claim 6, wherein the carbon dioxide is a gas and the temperature of the carbon dioxide is room temperature.

8. The method for producing a zeolite film according to claim 6 or 7, wherein the carbon dioxide is in a supercritical state.

9. Prior to the contact step, the process further includes a step of growing zeolite crystals by hydrothermal synthesis to produce the untreated zeolite film, The aforementioned untreated zeolite film is Na ＋ or K ＋ The above includes as the counter cation, In the contact step, a compound that forms a water-insoluble salt with the counter cation is used as the dehydration condensation reaction accelerator. A method for producing a zeolite film according to any one of claims 1 to 8.

10. The aforementioned countercation is Na ＋ The method for producing a zeolite membrane according to claim 9, wherein a fluoride solution is used as the dehydration condensation reaction accelerator.

11. The aforementioned countercation is Na ＋ The method for producing a zeolite membrane according to claim 9, wherein uric acid water is used as the dehydration condensation reaction accelerator.

12. The method for producing a zeolite film according to any one of claims 9 to 11, wherein the step of generating is a step of growing zeolite crystals without using an organic template compound, which is an organic compound and is a template agent that regulates the crystal structure of the zeolite, in order to produce the untreated zeolite film.

13. The method for producing a zeolite film according to any one of claims 9 to 11, wherein the step of generating the zeolite is to grow zeolite crystals in the presence of an organic template compound, which is an organic compound and acts as a template agent that regulates the crystal structure of the zeolite, and to treat the obtained zeolite film with an oxidizing agent to remove the organic template compound from the zeolite film and produce the untreated zeolite film.

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