Gas separation membrane and gas separation method

Abstract

This invention provides gas separation membranes and other devices that enable efficient gas separation and have a wide range of applications. [Solution] A gas separation membrane comprising a liquid crystal thin film having gas separation ability, wherein the liquid crystal thin film contains a polymer in which at least one of the compounds represented by the following formulas (1α), (1β), etc., is polymerized. TIFF2026070630000028.tif33102 TIFF2026070630000029.tif34106

Description

[Technical Field]

[0001] The present invention relates to a gas separation membrane and a gas separation method. [Background technology]

[0002] Conventionally, technologies have been developed to separate specific gases from mixed gases containing multiple types of gases. For example, Patent Document 1 shows a gas separation apparatus that uses aluminum-containing zeolite as a separation membrane. [Prior art documents] [Patent Documents]

[0003] [Patent Document 2] International Publication No. 2019 / 159782 brochure [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Patent Document 1 demonstrates that carbon dioxide and nitrogen can be efficiently separated. However, there are concerns that the range of application is limited because zeolites typically have a certain hardness.

[0005] In view of the above circumstances, the present invention aims to provide a gas separation membrane and the like that can efficiently perform gas separation and has a wide range of applications. [Means for solving the problem]

[0006] According to one aspect of the present invention, a gas separation membrane comprising a liquid crystal thin film having gas separation ability, wherein the liquid crystal thin film contains a polymer in which at least one of the compounds represented by the following formulas (1α), (1β), (1γ), or (1δ) is polymerized, [ka] In equation (1α), X - Cl - , Br- 、I - 、F - 、BF4 - 、PF6 - 、OH - 、CF3SO3 - and (CF3SO2)2N - selected from the group consisting of 1 R, 2 R and 3 R may be the same or different, and is -(CH2) k-1 CH3, -(CF2) k-1 CF3, -(CH2) g (CF2) k-1 CF3 and -(CH2CH2O) g CH3, selected from the group consisting of, and k and g are 1 R, 2 R and 3 R may be the same or different in 4 R, 5 R and 6 R may be the same or different, and is CH2=CH-COO-(CH2) p -O-, CH2=CCH3-COO-(CH2) p -O-, CH2=CH-CH=CH-(CH2) p -O-, CH3-(CH2) p-1 -O- and H, selected from the group consisting of, and p is 4 R, 5 R and 6 R may be the same or different in, g is an integer from 1 to 8, k is an integer from 1 to 8, p is an integer from 1 to 22, and n is an integer from 0 to 6, 4 R, 5 R and 6 At least one of R is selected from the group consisting of CH2=CH-COO-(CH2) p -O-, CH2=CCH3-COO-(CH2) p -O- and CH2=CH-CH=CH-(CH2) p -O-,

Chemical formula

[0007] According to the above embodiment, a gas separation membrane or the like is provided that can efficiently separate gases and has a wide range of applications. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing an example of a gas separation membrane according to this embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below. The various features shown in the embodiments below can be combined with each other. Furthermore, unless otherwise specified, "~" in this specification represents the following from the above.

[0010] In other words, the gas separation membrane of this embodiment is as follows. A gas separation membrane, Equipped with a liquid crystal thin film having gas separation capability, The liquid crystal thin film comprises a polymer in which at least one compound represented by the following formula (1α), (1β), (1γ), or (1δ) is polymerized. [ka] In equation (1α), X - Cl - , Br - , I - F - BF4 - PF6 - , OH - CF3SO3 - and (CF3SO2)2N - Selected from the group consisting of, 1 R, 2 R and 3 R may be the same or different, -(CH2) k-1 CH3, -(CF2) k-1 CF3, -(CH2) g (CF2) k-1 CF3 and -(CH2CH2O) g Selected from the group consisting of CH3, k and g are, 1 R, 2 R and 3 In R, they may be the same or different. 4 R, 5 R and 6 R can be the same or different, and CH2=CH-COO-(CH2) p -O-, CH2=CCH3-COO-(CH2) p-O-, CH2=CH-CH=CH-(CH2) p -O-, CH3-(CH2) p-1 selected from the group consisting of -O- and H p is 4 R 5 R and 6 R may be the same or different in g is an integer from 1 to 8, k is an integer from 1 to 8, p is an integer from 1 to 22, and n is an integer from 0 to 6 4 R 5 R and 6 at least one of R, R, and R is CH2=CH-COO-(CH2) p -O-, CH2=CCH3-COO-(CH2) p -O- and CH2=CH-CH=CH-(CH2) p selected from the group consisting of -O-

Chemical formula

Chemical formula

[0011] [Gas separation membrane 100] The overview and applications of such gas separation membranes are described below. Figure 1 is a cross-sectional view showing an example of the gas separation membrane of this embodiment. The gas separation membrane 100 shown in Figure 1 comprises a liquid crystal thin film 1 and a support film 2. In this embodiment, the gas separation ability of the gas separation membrane 100 is mainly exhibited by the function of the liquid crystal thin film 1. Therefore, the gas separation membrane of this embodiment may be composed of a single layer of the liquid crystal thin film 1. This does not prevent the support film 2 itself from having gas separation ability, and in order to provide desired functions, other films not shown can be combined to form the gas separation membrane. In this embodiment, the gas separation membrane 100 is described as being laminated on the liquid crystal thin film 1 and further comprising a support film 2 that supports the liquid crystal thin film 1. The following describes each film that constitutes the gas separation membrane 100 shown in Figure 1.

[0012] [Liquid crystal thin film only] In this embodiment, the liquid crystal thin film 1 is characterized by containing a polymer in which at least one of the compounds represented by the following formulas (1α), (1β), (1γ), or (1δ) is polymerized.

[0013] [ka] In equation (1α), X - Cl - , Br - , I - F - BF4 - PF6 - , OH - CF3SO3 - and (CF3SO2)2N - Selected from the group consisting of, 1 R, 2 R and 3 R may be the same or different, -(CH2) k-1 CH3, -(CF2) k-1 CF3, -(CH2) g (CF2) k-1 CF3 and -(CH2CH2O) g Selected from the group consisting of CH3, k and g are, 1 R, 2 R and 3 In R, they may be the same or different. 4 R, 5 R and 6 R can be the same or different, and CH2=CH-COO-(CH2) p -O-, CH2=CCH3-COO-(CH2) p -O-, CH2=CH-CH=CH-(CH2) p -O-, CH3-(CH2) p-1 Selected from the group consisting of -O- and H, p is 4 R, 5 R and 6 In R, they may be the same or different. g is an integer from 1 to 8, k is an integer from 1 to 8, p is an integer from 1 to 22, and n is an integer from 0 to 6. 4 R, 5 R and 6 At least one of R is CH2=CH-COO-(CH2) p-O-, CH2=CCH3-COO-(CH2) p -O- and CH2=CH-CH=CH-(CH2) p Selected from the group consisting of -O-.

[0014] [ka] In equation (1β), X - , 4 R, 5 R, 6 R and n are equivalent to those shown in equation (1α), respectively. Z + This refers to a group in which the nitrogen atom contained in the nitrogen-containing aromatic group has cationic properties. 10 R is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a halogen atom, and multiple 10 If R exists, it may be the same or different. m is an integer between 0 and 3.

[0015] [ka] In equation (1γ), 1 R, 2 R, 4 R, 5 R, 6 R and n are equivalent to those shown in equation (1α), respectively. l is an integer between 0 and 6.

[0016] [ka] In equation (1δ), 4 R, 5 R, 6 R and n are equivalent to those shown in equation (1α), respectively. Z + This refers to a group in which the nitrogen atom contained in the nitrogen-containing aromatic group has cationic properties. 10R is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a halogen atom, and multiple 10 If R exists, it may be the same or different. m is an integer between 0 and 3. l is an integer between 0 and 6.

[0017] In other words, 4 R, 5 R and 6 At least one of R is CH2=CH-COO-(CH2) p -O-, CH2=CCH3-COO-(CH2) p -O- and CH2=CH-CH=CH-(CH2) p The group is selected from the group consisting of -O-, and in this respect, each of the above compounds can be said to be polymerizable.

[0018] Note that in formulas (1β) and (1δ), Z is contained in the compound. + Z is a group in which the nitrogen atom contained in the nitrogen-containing aromatic group is cationic. Various nitrogen-containing aromatic groups can be selected here, but for example, it is a group selected from the group consisting of imidazolyl group, pyridyl group, pyrimidinyl group, pyrazinyl group, pyridadinyl group, triazinyl group, pyrrolyl group, pyrazolyl group, isothiazolyl group, isoxazolyl group, thiadiazolyl group, triazolyl group, tetrazolyl group and indolyl group. Note that the nitrogen-containing aromatic group may be a group composed of a fused ring containing the above various nitrogen-containing aromatic groups. In this embodiment, from the viewpoint of using a compound that is easily available, Z is used here. + Preferably, the nitrogen atom contained in the imidazolyl group or pyridyl group is a cationic group. + -(CH2) n -ya-(CH2) l -SO3 - , 10The bonding position to R can be set as appropriate. That is, the nitrogen atom in the nitrogen-containing aromatic group may be the bonding position to the above group, or an atom other than the nitrogen atom in the nitrogen-containing aromatic group (typically a carbon atom) may be the bonding position to the above group. Furthermore, the nitrogen atom of a cationic group is -(CH2) n -It may be present at the bonding position to -(CH2) n - It may be located at a position different from the bonding position to -.

[0019] Furthermore, the compounds represented by formulas (1α) to (1δ) have the characteristic of giving a liquid crystal structure when polymerized. In this embodiment, this liquid crystal structure can provide gas separation ability to the liquid crystal thin film 1. The type of structure in this liquid crystal structure can be appropriately set depending on the compound, but typically, the polymer in this embodiment preferably contains liquid crystals exhibiting a bicontinuous cubic structure or a columnar liquid crystal structure, and more preferably contains liquid crystals exhibiting a bicontinuous cubic structure. By including such a liquid crystal structure in the polymer, it becomes easier to exhibit gas separation ability.

[0020] Compounds represented by formulas (1α) to (1δ) are typically polymerized in the presence of a polymerization initiator to yield a polymer. The polymerization initiator may be either a photopolymerization initiator or a thermal polymerization initiator. That is, by coexisting the compounds represented by formulas (1α) to (1δ) with a polymerization initiator and subjecting them to predetermined conditions (light irradiation conditions, heating conditions), the polymerization reaction can be promoted and a polymer can be obtained. The amount of polymerization initiator used can be set as appropriate, but for example, when the mass of the compounds represented by formulas (1α) to (1δ) is 100 parts by mass, it is preferable to set the amount to 0.01 parts by mass or more and 8 parts by mass or less, and more preferably to 0.05 parts by mass or more and 5 parts by mass or less. By setting the amount within this range, the rate of the polymerization reaction can be appropriately adjusted, making it easier to obtain the desired liquid crystal structure.

[0021] Examples of polymerization initiators include the following compounds: Benzoin ether, dialkylbenzyl ketal, dialkoxyacetophenone, dialkoxyphenylacetophenone, acylphosphine oxide or bisacylphosphine oxide, α-diketone (e.g., 9,10-phenanthrenequinone), diacetylquinone, furylquinone, anisylquinone, 4,4'-dichlorobenzylquinone and 4,4'-dialkoxybenzylquinone, camphor quinone, and others. Examples of thermal polymerization initiators include azo compounds (e.g., 2,2'-azobis(isobutyronitrile) (AIBN) or azobis-(4-cyanovaleric acid)), peroxides (e.g., dibenzoyl peroxide, dilauroyl peroxide, tert-butyl peroctanoate, tert-butyl perbenzoate or di-(tert-butyl) peroxide), aromatic diazonium salts, bissulfonium salts, aromatic iodonium salts, aromatic sulfonium salts, potassium persulfate, ammonium persulfate, alkyllithium, cumyl potassium, sodium naphthalene, distylyl dianion, etc.). Of course, these are not the only examples, and various polymerization initiators may be used to promote the polymerization of the compound represented by formula (1).

[0022] In this specification, "light irradiation conditions" refer to the manner in which radiation (light) is irradiated from various light sources, and include the irradiation of infrared rays, ultraviolet rays, X-rays, gamma rays, etc. In addition, light irradiation conditions also include the manner in which exposure is performed using halogen lamps, xenon lamps, UV lamps, excimer lamps, metal halide lamps, noble gas fluorescent lamps, mercury lamps, etc.

[0023] Furthermore, the liquid crystal thin film 1 may contain various additives other than those described above, as long as it does not depart from the spirit of the invention. Examples of such additives include surfactants, pigments, dyes, antistatic agents, antiblocking agents, lubricants, etc., but are not limited to these, and various additives may be added depending on the function to be imparted to the liquid crystal thin film 1.

[0024] The thickness of the liquid crystal thin film 1 can be appropriately set depending on the gas separation application. On the other hand, the thickness of the liquid crystal thin film 1 is preferably in the range of 5 to 500 nm, and more preferably in the range of 10 to 200 nm. By setting the thickness of the liquid crystal thin film 1 within this range, it is easier to balance the mechanical strength of the liquid crystal thin film 1 with the gas separation performance.

[0025] [Support membrane 2] In this embodiment, the support film 2 supports the liquid crystal thin film 1 and contributes to improving the overall strength of the gas separation film 100. Since the gas separation film 100 in this embodiment is used for gas separation, it is preferable that the support film 2 is a porous film.

[0026] The size and distribution of pores on the surface of the support film 2 are not particularly limited, but it is preferable, for example, to have uniform pores, or pores that gradually increase in size from the surface on which the liquid crystal thin film 1 is formed to the other surface, and on the surface on which the liquid crystal thin film 1 is formed, the size of the micropores is 1 nm to 100 nm. If the pore diameter of the support film 2 is within this range, appropriate gas permeability can be ensured.

[0027] The pore diameter on the surface of support film 2 can be calculated using electron microscope images. The pore diameter refers to the value obtained by photographing the surface of the microporous support film with an electron microscope, measuring the diameter of all observable pores, and averaging them. If the pores are not circular, the pore diameter can be determined by using an image processing device to find a circle with an area equal to that of the pore (an equivalent circle), and using the diameter of the equivalent circle as the pore diameter. Alternatively, it can be determined by differential scanning calorimetry (DSC), and details are described in Ishikiriyama et al., Journal of Colloid and Interface Science, Vol. 171, p. 103, Academic Press, Inc. (1995).

[0028] The material constituting the support film 2 is not particularly limited. For example, homopolymers or copolymers such as polysulfone, polyethersulfone, polyamide, polyester, cellulose polymers, vinyl polymers, polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfone, and polyphenylene oxide can be used. These polymers can be used alone or in blends. Among the above, examples of cellulose polymers include cellulose acetate and cellulose nitrate. Examples of preferred vinyl polymers include polyethylene, polypropylene, polyvinyl chloride, and polyacrylonitrile. Among these, homopolymers and copolymers such as polysulfone, polyethersulfone, polyamide, polyester, cellulose acetate, cellulose nitrate, polyvinyl chloride, polyacrylonitrile, polyphenylene sulfide, and polyphenylene sulfide sulfone are preferred. Furthermore, among these materials, polysulfone and polyethersulfone are particularly preferred because they have high chemical stability, mechanical strength, and thermal stability, and are easy to mold.

[0029] The thickness of the support film 2 can be set as appropriate, but it is preferably in the range of 1 μm to 5 mm, and more preferably in the range of 10 μm to 1 mm. This makes it easier to achieve the strength of the gas separation membrane 100. In addition, to increase the strength of the gas separation membrane 100, the support film 2 may be reinforced with cloth, nonwoven fabric, paper, etc. The preferred thickness of these reinforcing materials is 50 to 150 μm.

[0030] [Method for manufacturing the gas separation membrane 100] Next, a method for manufacturing the gas separation membrane 100 of this embodiment will be described. The gas separation membrane 100 of this embodiment has a structure in which a liquid crystal thin film 1 and a support film 2 are laminated. In this case, the gas separation membrane 100 can typically be obtained by combining the following steps. That is, in this embodiment, an example is to manufacture the gas separation membrane 100 by combining the steps of forming a composition film on the support film 2 to give the liquid crystal thin film 1 and polymerizing the compounds contained in the composition film to form a polymer.

[0031] The method for forming the composition film on the support film 2 is not particularly limited. For example, this could involve applying a solution containing the compound represented by formula (1) described above onto the support film 2 and removing the solvent contained in the solution, or transferring a composition film formed on a releaseable substrate onto the support film 2.

[0032] The method for coating the solution containing the compound represented by formula (1) onto the support film 2 is not particularly limited, but a method that allows for uniform coating is preferred. Examples include coating using devices such as a spin coater, wire bar, flow coater, die coater, roll coater, or spray. The solvent for the solution is not particularly limited, as long as it does not dissolve the support film 2 and dissolves the compound represented by formula (1) and the polymerization initiator. Solvent removal can be done by known methods and is not particularly limited, but it is preferable to remove it sufficiently by heating or reduced pressure so as not to interfere with the self-assembly of the liquid crystal.

[0033] Formation of a composition film on a releaseable substrate is possible by known methods and is not particularly limited, but a method of applying a solution containing the compound represented by formula (1) onto the releaseable substrate and then removing the solvent is preferably used. The type of releaseable substrate is not particularly limited, but materials such as glass, metal, silicon wafer, and polymer can be used. In addition, if necessary, releaseable substrates that have been surface-treated by silicon coating, polyvinyl alcohol coating, corona discharge, etc., can also be used. The method of applying the solution containing the compounds represented by formulas (1α) to (1δ) onto the releaseable substrate is not particularly limited, but a method that allows for uniform application is preferred, for example, a method of applying the solution using equipment such as a spin coater, wire bar, flow coater, die coater, roll coater, or spray. The solvent of the solution is not particularly limited as long as it does not dissolve the releaseable substrate and dissolves the compounds represented by formulas (1α) to (1δ) and polymerization initiators. Solvent removal from the solution is possible by known methods and is not particularly limited, but it is preferable to remove it sufficiently by heating or reduced pressure so as not to hinder the self-assembly of the liquid crystal.

[0034] Next, the surface of the composition film formed on the releaseable substrate is brought into contact with the surface of the support film 2, the compound represented by formulas (1α) to (1δ) is polymerized, and then the releaseable substrate is peeled off to obtain the desired gas separation membrane 100. The conditions for polymerizing the compound are as described above, and light irradiation conditions, heating conditions, etc., are used. When the releaseable substrate is coated with polyvinyl alcohol, the polyvinyl alcohol can also be dissolved in water or the like when peeling off the releaseable substrate. By adopting this method, the gas separation membrane 100 can be efficiently peeled off from the releaseable substrate. In addition, in this embodiment, the anion portion of the polymer contained in the liquid crystal thin film 1 can also be replaced. That is, after polymerizing the compound represented by formulas (1α) to (1δ), the existing anions can be replaced with anions different from the polymerization raw materials. Typically, such anion exchange can be carried out by passing a solution containing the anions to be replaced through the gas separation membrane 100.

[0035] The gas separation membrane in this embodiment may be composed solely of a liquid crystal thin film. In this case, a solution containing compounds represented by formulas (1α) to (1δ) is applied to a releaseable substrate, the compounds are polymerized, and then the releaseable substrate is peeled off to obtain a single-layer film of liquid crystal thin film.

[0036] [Applications of gas separation membrane 100 (gas separation method)] The gas separation membrane 100 obtained as described above can typically be used for gas separation applications. That is, the gas separation method of this embodiment comprises preparing the gas separation membrane 100 and using the gas separation membrane 100 to selectively permeate a specific gas from a mixed gas containing multiple types of gases.

[0037] In other words, the gas separation method of this embodiment separates multiple gases by selectively permeating a specific gas from a mixed gas containing multiple gases. The mixed gas in this embodiment can be set as appropriate, but may contain any combination of gases from among hydrogen, helium, carbon dioxide, hydrocarbon gases (including methane, ethane, acetylene, etc.), nitrogen, oxygen, ammonia, etc. The gas separation membrane 100 of this embodiment selectively permeates a predetermined gas from a mixed gas containing such a combination of gases. That is, the inventors have found that since the polymer contained in the liquid crystal thin film 1 provided in the gas separation membrane 100 has a predetermined liquid crystal structure, it is possible to construct a system that easily permeates a predetermined gas and difficult to permeate other gases. Based on this mechanism, the gas separation membrane 100 of this embodiment can be suitably used for gas separation applications.

[0038] In a more typical example, the gas separation membrane 100 of this embodiment is used to selectively permeate carbon dioxide from a mixed gas containing at least nitrogen and carbon dioxide. That is, in one embodiment of this embodiment, the liquid crystal thin film 1 can selectively permeate carbon dioxide (carbonic acid gas). Although not necessarily based on such a mechanism, when a polymer of a compound represented by formulas (1α) to (1δ) has a predetermined liquid crystal structure, the gaps created in the liquid crystal structure can provide an environment in which nitrogen molecules are less permeable and carbon dioxide is more permeable. In other words, when the above-mentioned mixed gas is applied, it is thought that gas separation can be efficiently performed based on the gaps created by the liquid crystal structure. However, since the type and size of the liquid crystal structure may change depending on the type of compound used, the applications of the gas separation membrane 100 of this embodiment are not necessarily limited to mixed gases containing nitrogen and carbon dioxide.

[0039] Furthermore, various atmospheres can be selected when carrying out the above gas separation method. That is, the above gas separation method may be carried out at atmospheric pressure, or under pressurized or depressurized conditions. In addition, in the exemplary gas separation method of this embodiment, temperature and humidity conditions may be adjusted. That is, the gas separation membrane 100 of this embodiment may be used for gas separation in an environment where the temperature is 0°C or higher, in an environment where the temperature is 10°C or higher, in an environment where the temperature is 20°C or higher, or in an environment where the temperature is 30°C or higher. On the other hand, the gas separation membrane 100 of this embodiment may be used for gas separation in an environment where the temperature is 200°C or lower, in an environment where the temperature is 150°C or lower, or in an environment where the temperature is 100°C or lower. Furthermore, the gas separation membrane 100 of this embodiment may be used for gas separation in an environment with a relative humidity of 85% or higher, or in an environment with a relative humidity of 90% or higher, or in an environment with a relative humidity of 95% or higher. While not necessarily limited to these conditions, the gas separation membrane 100 of this embodiment tends to exhibit significantly better gas separation performance in environments with high relative humidity. Therefore, it is preferable to adopt the aforementioned relative humidity conditions when permeating a specific gas.

[0040] In a more typical embodiment, the gas separation membrane 100 of this embodiment is preferably used for selectively permeating a specific gas from fuel exhaust gas. That is, fuel exhaust gas can be used as the mixed gas mentioned above. Fuel exhaust gas is characterized by containing a large amount of water vapor and often satisfies the relative humidity mentioned above. Although various specific gases can be assumed to be selectively permeated from fuel exhaust gas, it is typically carbon dioxide. That is, fuel exhaust gas often contains a large amount of carbon dioxide, and it is also intended to be used for selectively permeating this carbon dioxide from fuel exhaust gas (mixed gas). The gases contained in the fuel exhaust gas are not limited to the above. That is, the gas separation membrane 100 of this embodiment is also intended to be applied to gas separation of exhaust gas containing NOx (nitrogen oxides) and SOx (sulfur oxides). Typical examples include the selective permeation or non-permeation of NOx (nitrogen oxides) and SOx (sulfur oxides) depending on the type of liquid crystal thin film 1.

[0041] Furthermore, the gas separation membrane 100 may absorb moisture during the gas separation process. In particular, since the liquid crystal thin film 1 of this embodiment exhibits gas separation ability easily in environments with high relative humidity, it is preferable that a predetermined amount of moisture is absorbed into the liquid crystal thin film 1 during the gas separation process. For example, when the dry mass of the liquid crystal thin film 1 is X[g], the mass of the liquid crystal thin film 1 during the gas separation process may be 1.01X[g] or more, 1.05X[g] or more, or 1.08X[g] or more. There is no particular upper limit to the mass of the liquid crystal thin film 1 during the gas separation process, but for example, it may be 1.2X[g] or less, or 1.15X[g] or less. Although not necessarily limited to this, the absorption of a predetermined amount of moisture into the liquid crystal thin film 1 makes it easier to control the gaps in the liquid crystal structure to a predetermined size. This makes it easier to exhibit suitable gas separation ability.

[0042] Furthermore, they may be provided in the following embodiments.

[0043] (1) A gas separation membrane comprising a liquid crystal thin film having gas separation ability, wherein the liquid crystal thin film contains a polymer in which at least one of the compounds represented by the following formulas (1α), (1β), (1γ), or (1δ) is polymerized, [C1] In formula (1α) of TIFF2026070630000013.tif33103, X - Cl - , Br - , I - F - BF4 - PF6 - , OH - CF3SO3 - and (CF3SO2)2N - Selected from the group consisting of, 1 R, 2 R and 3 R may be the same or different, -(CH2) k-1 CH3, -(CF2) k-1 CF3, -(CH2) g (CF2) k-1 CF3 and -(CH2CH2O) g Selected from the group consisting of CH3, k and g are 1 R, 2 R and 3 In R, they may be the same or different. 4 R, 5 R and 6 R can be the same or different, and CH2=CH-COO-(CH2) p -O-, CH2=CCH3-COO-(CH2) p -O-, CH2=CH-CH=CH-(CH2) p -O-, CH3-(CH2) p-1 Selected from the group consisting of -O- and H, p is, 4 R, 5 R and 6 In R, g can be the same or different integers, k is an integer from 1 to 8, p is an integer from 1 to 22, and n is an integer from 0 to 6. 4 R, 5 R and 6 At least one of R is CH2=CH-COO-(CH2) p-O-, CH2=CCH3-COO-(CH2) p -O- and CH2=CH-CH=CH-(CH2) p Selected from the group consisting of -O-, [C2] In formula (1β) of TIFF2026070630000014.tif34106, X - , 4 R, 5 R, 6 R and n are equivalent to those shown in equation (1α), respectively, and Z + This refers to a group in which the nitrogen atom contained in the nitrogen-containing aromatic group has cationic properties. 10 R is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a halogen atom, and multiple 10 If R exists, it may be the same or different, and m is an integer from 0 to 3. [C3] In formula (1γ) TIFF2026070630000015.tif3198, 1 R, 2 R, 4 R, 5 R, 6 R and n are equivalent to those shown in equation (1α), respectively, and l is an integer from 0 to 6. [C4] In formula (1δ) of TIFF2026070630000016.tif3095, 4 R, 5 R, 6 R and n are equivalent to those shown in equation (1α), respectively, and Z + This refers to a group in which the nitrogen atom contained in the nitrogen-containing aromatic group has cationic properties. 10 R is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a halogen atom, and multiple 10 A gas separation membrane in which R can be the same or different if present, m is an integer from 0 to 3, and l is an integer from 0 to 6.

[0044] (2) A gas separation membrane according to (1) above, wherein the polymer contains a liquid crystal exhibiting a bicontinuous cubic structure or a columnar liquid crystal structure.

[0045] (3) A gas separation membrane as described in (1) or (2) above, which is used for selectively permeating carbon dioxide from a mixed gas containing at least nitrogen and carbon dioxide.

[0046] (4) A gas separation membrane according to any one of (1) to (3) above, which is used for the purpose of selectively permeating a specific gas from fuel exhaust gas.

[0047] (5) A gas separation membrane described in any one of (1) to (4) above, which is used for gas separation in an environment with a relative humidity of 85% or higher.

[0048] (6) A gas separation membrane according to any one of (1) to (5) above, further comprising a support membrane laminated on the liquid crystal thin film and supporting the liquid crystal thin film.

[0049] (7) A gas separation method comprising: preparing a gas separation membrane as described in any one of (1) to (6) above; and selectively permeating a specific gas from a mixed gas containing multiple types of gases using the gas separation membrane.

[0050] (8) A gas separation method according to (7) above, wherein the mixed gas is fuel exhaust gas.

[0051] (9) A gas separation method according to (7) or (8) above, wherein the permeation of the specific gas is carried out in an environment with a relative humidity of 85% or higher. Of course, this is not always the case. [Examples]

[0052] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples.

[0053] [Example 1] A support film was prepared by casting a 15.7 wt% dimethylformamide solution of polysulfone onto a polyester nonwoven fabric to a thickness of 200 μm at room temperature (25°C), and immediately immersing it in pure water for 5 minutes. Subsequently, a dichloromethane solution containing 1.0 wt% of the compound represented by formula (1A) and 0.01 wt% of 2,2-dimethoxy-2-phenylacetophenone was applied by spin coating onto a PET film coated with polyvinyl alcohol, which is a releaseable substrate, and then vacuum-dried to form a liquid crystal thin film. The surface of the support film was brought into contact with the surface of the obtained liquid crystal thin film, and the temperature was raised to 80°C, then lowered to 10°C. Ultraviolet light with a wavelength of 365 nm was irradiated from the releaseable substrate side for 10 minutes to polymerize the liquid crystal thin film. The releaseable substrate was peeled off from the composite obtained by dissolving the polyvinyl alcohol to prepare the desired composite film. In this Example 1, the thickness of the liquid crystal thin film provided in the composite film was approximately 100 nm.

[0054] [ka]

[0055] [Example 2] A composite film was prepared using the same method as in Example 1, except that the compound represented by formula (1A) in Example 1 was replaced with the compound represented by formula (1B) below.

[0056] [ka]

[0057] [Example 3] The composite film obtained in Example 1 was permeated with 3 mL of a 500 ppm sodium hydroxide aqueous solution to determine the BF4 contained in the liquid crystal thin film. - A composite film was obtained by converting anions to hydroxide ions.

[0058] [Example 4] A composite film was prepared using the same method as in Example 1, except that the compound represented by formula (1A) in Example 1 was replaced with the compound represented by formula (1C) below.

[0059] [ka]

[0060] [Example 5] A composite film was prepared using the same method as in Example 1, except that the compound represented by formula (1A) in Example 1 was replaced with the compound represented by formula (1D) below.

[0061] [ka]

[0062] Except for the compound represented by formula (1D) in this example, all compounds are known from the literature, and these known compounds were prepared using the methods described in the relevant literature. On the other hand, the compound represented by formula (1D) was synthesized according to the following scheme. Details are described below. In the following compound synthesis, all reagents and solvents were obtained from Tokyo Chemical Industry Co., Ltd., Kanto Chemical Co., Ltd., Fujifilm Wako Pure Chemical Corporation, Sigma-Aldrich Japan Ltd., or Dojin Chemical Laboratories, Inc. Furthermore, 3,5-bis((9,11-dodecadienyl)oxy)-4-dodecyloxybenzyl chloride (compound 3 in Scheme 1 below) was synthesized using the same procedure as described in the literature (T. Sakamoto, T. Ogawa, H. Nada, K. Nakatsuji, M. Mitani, B. Soberats, K. Kawata, M. Yoshio, H. Tomioka, T. Sasaki, M. Kimura, M. Henmi, T. Kato, Adv. Sci.,5, 1700405 (2018)). Silica gel column chromatography was performed using a medium-pressure preparative liquid chromatography system manufactured by Yamazen Corporation. 1 H and 13¹³C-NMR spectra were measured using a JEOL JNM-ECX400 spectrometer. Mass spectra (MS) were measured using a Bruker Autoflex™ speed spectrometer.

[0063] [ka]

[0064] [Synthesis of the compound represented by formula (1D)] Step 1: Synthesis of 1-(3,5-bis((9,11-dodecadienyl)oxy)-4-dodecyloxybenzyl)-imidazole (compound 4) A solution of sodium hydride (60% suspension, 0.113 g, 2.7 mmol) dispersed in dry N,N-dimethylformamide (DMF) (10 mL) was slowly added dropwise to a dry DMF solution of imidazole (0.176 g, 2.6 mmol) (5 mL) under ice cooling, and the mixture was stirred for 30 minutes. Then, a dry DMF solution of compound 3 (1.312 g, 1.97 mmol) (20 mL) was added dropwise. After replacing the atmosphere in the reaction vessel with an Ar atmosphere, the mixture was stirred under ice cooling for 1 hour, and then the temperature was raised to 60°C and stirred for 15 hours. After cooling to room temperature, the solution was poured into saturated NH4Cl water, and the product was extracted three times with ethyl acetate. The organic phases were combined, washed with saturated NH4Cl water and saturated NaCl water, and then dried over anhydrous MgSO4. After filtration and subsequent removal of the solvent, the crude product was purified by silica gel column chromatography (hexane:ethyl acetate = 4:6) and vacuum-dried to obtain compound 4 as a colorless viscous fluid (yield 0.753 g (1.06 mmol), yield 54%). 1H NMR (400 MHz, CHLOROFORM-D): δ = 7.53 (s, 1H), 7.09 (s, 1H), 6.90 (s, 1H), 6.31 (s, 2H), 6.30 (dt, J = 16.8, 10.8 Hz, 2H), 6.04 (dd, J = 16.0, 10.8 Hz, 2H), 5.70 (dt, J = 15.6, 7.2 Hz, 2H), 5.08 (d, J = 16.8, 2H), 5.01 (s, 2H), 4.95 (d, J = 10.8 Hz, 2H), 3.94-3.87 (m, 6H), 2.07 (q, J = 7.1 Hz, 4H), 1.80-1.70 (m, 6H), 1.50-1.20 (m, 38H), 0.88 (t, J = 6.8 Hz, 3H).

[0065] Step 2: Synthesis of 3-(1-(3,5-bis((9,11-dodecadienyl)oxy)-4-dodecyloxybenzyl)-imidazolium-3-yl)propane-1-sulfonate (compound 1D) Compound 4 (731 mg, 1.03 mmol) obtained in the above process was dissolved in dry toluene (15 mL), and 1,3-propanesultone (201 mg, 4.41 mmol) was added, and the mixture was stirred at room temperature for 1 day. After removing the solvent by distillation, the crude product was purified by two silica gel column chromatography cycles (first cycle: dichloromethane:methanol = 9:1 → 8:2, dichloromethane:methanol = 95:5 → 85:15), and then vacuum-dried to obtain compound 1D as a white solid (yield 470 mg (0.57 mmol), yield 55%). 11H NMR (400 MHz, CHLOROFORM-D): δ = 9.01 (s, 1H), 7.17 (s, 1H), 7.01 (s, 1H), 6.57 (s, 2H), 6.29 (dt, J = 17.6, 10.4 Hz, 2H), 6.03 (dd, J = 15.6, 10.4 Hz, 2H), 5.68 (dt, J = 15.2, 7.2 Hz, 2H), 5.32 (s, 2H), 5.06 (d, 16.8 Hz, 2H), 4.93 (d, 10.0 Hz, 2H), 4.59 (t, 6.0 Hz, 2H), 3.94 (m, 6H), 2.90 (t, J = 5.6 Hz, 2H), 2.42 (m, 2H), 2.06 (q, 7.1 Hz, 4H), 1.80 - 1.65 (m, 6H), 1.50 - 1.20 (m, 38H), 0.87 (t, J = 6.4 Hz, 3H). 13 13C-NMR (100 MHz, CHLOROFORM-D) δ = 153.88, 138.95, 137.59, 137.42, 135.58, 130.95, 127.66, 122.13, 121.37, 114.67, 107.67, 73.53, 69.45, 53.96, 48.75, 47.40, 32.64, 32.01, 30.43, 29.84, 29.77, 29.70, 29.56, 29.48, 29.28, 26.41, 26.22, 22.77, 14.20. MS (MALDI-TOF): [m / z] + 824.85, 847.33, 863.39; Calcd for [M + H] + 825.58; for [M + Na] + 847.56; for [M + K] + 863.54: [m / z] - 824.07; Calcd for [M - H] - 823.57.

[0066] [Comparative Example 1] A composite film was prepared using the same method as in Example 1, except that the compound represented by formula (1A) in Example 1 was replaced with the compound represented by formula (2) below.

[0067] [ka]

[0068] [Gas separation capacity evaluation] Each composite membrane obtained as described above was prepared, and its gas separation performance was evaluated. Specifically, each composite membrane (25 mmφ) obtained above was set in a cell holder, and a mixed gas of 10% carbon dioxide and 90% nitrogen was humidified to a predetermined humidity and passed through it. The permeated gas was swept with helium gas humidified to a predetermined humidity, and the carbon dioxide and nitrogen concentrations in the helium gas were quantified by gas chromatography. The temperature of the separation membrane was maintained at 40°C in an oven, and the humidity of the incoming mixed gas and helium gas was humidified to a relative humidity of 90% using a humidifier. Furthermore, in order to evaluate the gas separation performance of each composite membrane, the fabricated composite membrane was allowed to stabilize under conditions of 90% relative humidity for 5 hours or more, and then the gas separation performance was evaluated.

[0069] Specifically, the composite membranes obtained in Examples 1-5 and Comparative Example 1 were subjected to a mixed gas flow under the conditions described above for evaluating gas separation performance, and the gas permeability of each gas after 60 minutes was evaluated in GPU units. The results are shown in Table 1. Table 1 also shows the gas permeability of carbon dioxide to nitrogen gas, calculated as selectivity. Note that 1 GPU is defined as 1 × 10⁻⁶ units when evaluating gas permeability. -6 cm 3 (STP) / (s·cm 2 (equivalent to cmHg)

[0070] [Table 1]

[0071] The compounds represented by formula (1A) used in Examples 1 and 3 are known to yield liquid crystals exhibiting a bicontinuous cubic structure when polymerized. Furthermore, the various compounds used in Examples 2, 4, and 5 yielded liquid crystals exhibiting a columnar liquid crystal structure when polymerized. On the other hand, the compound represented by formula (2) is known to yield a liquid crystal exhibiting a smectic liquid crystal structure when polymerized. This suggests that the gas separation ability described above is influenced by the liquid crystal structure. It should be noted that this gas separation ability can be particularly pronounced in environments with high relative humidity.

[0072] The results from the above examples support the claim that the gas separation membrane of the present invention can efficiently perform gas separation. Furthermore, the liquid crystal thin film provided in the gas separation membrane of the present invention is a polymer of a predetermined compound, and it is expected to have a wide range of applications.

[0073] The embodiments of the present invention have been described above, but these are merely examples, and various other configurations can be adopted. Furthermore, the present invention is not limited to the embodiments described above, and modifications, improvements, etc., within the scope that can achieve the objectives of the present invention are included in the present invention. [Explanation of Symbols]

[0074] 1: Liquid crystal thin film 2: Support membrane 100: Gas separation membrane

Claims

1. A gas separation membrane, Equipped with a liquid crystal thin film having gas separation capability, The liquid crystal thin film comprises a polymer in which at least one of the compounds represented by the following formulas (1α), (1β), (1γ), or (1δ) is polymerized. 【Chemistry 1】 In equation (1α), X － is selected from the group consisting of Cl － , Br － , I － , F － , BF ４ － , PF ６ － , OH － , CF ３ SO ３ － and (CF ３ SO ２ ), ２ N － and is selected from the group consisting of １ R, ２ R and ３ R may be the same or different, -(CH ２ ) ｋ－１ CH ３ , - (CF ２ ) ｋ－１ CF ３ ,-(CH ２ ) ｇ (CF ２ ) ｋ－１ CF ３ and - (CH ２ CH ２ O) ｇ CH ３ Selected from the group consisting of, k and g are, １ R, ２ R and ３ In R, they may be the same or different. ４ R, ５ R and ６ R may be the same or different, CH ２ =CH-COO-(CH ２ ) ｐ -O-, CH ２ = CCH ３ -COO- (CH ２ ) ｐ -O-, CH ２ =CH-CH=CH-(CH ２ ) ｐ -O-, CH ３ - (CH ２ ) ｐ－１ Selected from the group consisting of -O- and H, p is, ４ R, ５ R and ６ In R, they may be the same or different. g is an integer from 1 to 8, k is an integer from 1 to 8, p is an integer from 1 to 22, and n is an integer from 0 to 6. ４ R, ５ R and ６ At least one of R is CH ２ =CH-COO-(CH ２ ) ｐ -O-, CH ２ = CCH ３ -COO- (CH ２ ) ｐ -O- and CH ２ =CH-CH=CH-(CH ２ ) ｐ Selected from the group consisting of -O-, 【Chemistry 2】 In equation (1β), X － , ４ R, ５ R, ６ R and n are equivalent to those shown in equation (1α), respectively. Z ＋ This refers to a group in which the nitrogen atom contained in the nitrogen-containing aromatic group has cationic properties. １０ R is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a halogen atom, and multiple １０ If R exists, it may be the same or different. m is an integer between 0 and 3. 【Transformation 3】 In equation (1γ), １ R, ２ R, ４ R, ５ R, ６ R and n are equivalent to those shown in equation (1α), respectively. l is an integer from 0 to 6. 【Chemistry 4】 In equation (1δ), ４ R, ５ R, ６ R and n are equivalent to those shown in equation (1α), respectively. Z ＋ This refers to a group in which the nitrogen atom contained in the nitrogen-containing aromatic group has cationic properties. １０ R is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a halogen atom, and multiple １０ If R exists, it may be the same or different. m is an integer between 0 and 3. l is an integer between 0 and 6. Gas separation membrane.

2. In the gas separation membrane according to claim 1, A gas separation membrane comprising a polymer containing a liquid crystal exhibiting a bicontinuous cubic structure or a columnar liquid crystal structure.

3. In the gas separation membrane according to claim 1, A gas separation membrane used for selectively permeating carbon dioxide from a mixed gas containing at least nitrogen and carbon dioxide.

4. In the gas separation membrane according to claim 1, A gas separation membrane used for selectively permeating specific gases from fuel exhaust gas.

5. In the gas separation membrane according to claim 1, A gas separation membrane used for gas separation in environments with relative humidity of 85% or higher.

6. In the gas separation membrane according to claim 1, A gas separation membrane further comprising a support film laminated on the liquid crystal thin film and supporting the liquid crystal thin film.

7. A gas separation method, A gas separation membrane according to any one of claims 1 to 6, Using the aforementioned gas separation membrane, a specific gas is selectively permeated from a mixed gas containing multiple types of gases. A gas separation method comprising:

8. In the gas separation method described in claim 7, A gas separation method wherein the mixed gas is fuel exhaust gas.

9. In the gas separation method described in claim 7, The method of permeating the aforementioned specific gas is performed in an environment with a relative humidity of 85% or higher, and is a gas separation method.

Images