Gas separation membrane, gas separation membrane module and gas permeation device

Abstract

To provide a gas separation membrane, a gas separation membrane module and a gas permeation device having gas separation property, gas permeability and heat resistance and pressure resistance in extremely high temperature and high pressure steam atmosphere absent in conventional products.SOLUTION: A gas separation membrane 10 includes a polyimide resin 1 and a scaly filler 2. In a gas separation membrane module 30, the gas separation membrane 10 is disposed in a closed vessel 7 having a mixed gas inflow port 4, a permeation gas outflow port 5 and a non-permeation gas outflow port 6. A gas permeation device 50 has two or more gas separation membrane modules 30 disposed with the gas separation membrane 10 in the closed vessel 7 having the mix gas inflow port 4, the permeation gas outflow port 5 and the non-permeation gas outflow port 6.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to gas separation membranes, gas separation membrane modules and gas permeation devices. [Background technology]

[0002] Gas separation using gas separation membranes is a resource- and energy-saving technique that can be achieved using compact equipment, and its use is expanding in a variety of fields, including petrochemistry, chemistry, precision machinery, food, automobiles, nuclear power, the environment, biology, and medicine, and its importance is increasing.

[0003] Polymer materials used for such gas separation membranes include cellulose acetate, polydimethylsiloxane, ethyl cellulose, polysulfone, ethylene-propylene copolymer, polypropylene, polyamide, polyimide, and the like.

[0004] For example, Patent Document 1 proposes a gas separation membrane formed of a polyimide consisting of a specific repeating unit. Patent Document 1 describes that this gas separation membrane can be suitably used for separating gas from an organic vapor mixture, for example, by contacting the organic vapor mixture mainly containing organic vapor and water vapor with the gas separation membrane and selectively allowing the water vapor to permeate therethrough.

[0005] Furthermore, as a method for improving the strength and separation performance of a separation membrane, a method has been proposed in which an additive such as a filler is incorporated into the separation membrane. For example, Patent Document 2 describes the addition of a plate-like filler to a specific propylene-based polymer, and describes that by doing so, it is possible to provide a propylene-based resin composition that has high rigidity and an excellent balance between low-temperature impact resistance and a low linear expansion coefficient. Furthermore, for example, Patent Document 3 describes that a porous film made of polyarylene sulfide contains a reinforcing material such as mica or glass flakes as an additive. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2010-201417 A [Patent Document 2] JP 2017-218517 A [Patent Document 3] JP 2010-254943 A Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, gas separation technology using separation membranes has been attracting attention as a movement toward carbon neutrality. In many cases, it is expected that operating conditions will be more severe than those used up until now, such as high-temperature and high-pressure steam environments of 150°C or more. For this reason, in addition to permeability, separation membranes are required to have pressure resistance and heat resistance to withstand the severe operating conditions.

[0008] However, when the separation membrane is made of the above-mentioned polyimide, the influence of temperature, pressure, and steam in the above-mentioned high-temperature and high-pressure steam environment causes oxidation degradation and hydrolysis, resulting in a problem that the pressure resistance cannot be maintained. In addition, when the above-mentioned propylene-based resin is used, even if the strength of the membrane is maintained in a low-temperature range by including a filler in the membrane, the heat resistance and pressure resistance are insufficient in a high-temperature range, so the membrane is damaged and does not function as a separation membrane. Although the above-mentioned polyarylene sulfide has excellent heat resistance and hydrothermal resistance, it is damaged by water hammer due to pressure fluctuations of water or steam, resulting in a problem that it does not function as a separation membrane.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a gas separation membrane, a gas separation membrane module, and a gas permeation device that have gas separation properties and gas permeability, and also have heat resistance and pressure resistance even in an extremely high-temperature and high-pressure water vapor atmosphere that are not available in conventional products. [Means for solving the problem]

[0010] The gas separation membrane according to the present invention, which has solved the above-mentioned problems, comprises a polyimide resin and a scaly filler. Effect of the Invention

[0011] According to the present invention, it is possible to provide a gas separation membrane, a gas separation membrane module, and a gas permeation device which have gas separation properties and gas permeability, and which also have heat resistance and pressure resistance even in an extremely high-temperature, high-pressure water vapor atmosphere that are not available in conventional products. Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view illustrating an example of a gas separation membrane 10 according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional schematic diagram illustrating an example of a gas separation membrane 20 according to a second embodiment of the present invention. [Diagram 3] FIG. 2 is a cross-sectional schematic view showing an outline of an example of a gas separation membrane module 30 according to a third embodiment of the present invention. [Figure 4] FIG. 11 is a cross-sectional schematic view showing an example of a gas separation membrane module 40 according to a fourth embodiment of the present invention. [Diagram 5] FIG. 13 is a cross-sectional schematic diagram illustrating an example of a gas permeation device 50 according to a fifth embodiment of the present invention. [Figure 6] FIG. 11 is a cross-sectional schematic diagram showing an outline of another example of a gas permeation device 50 according to a fifth embodiment of the present invention. [Figure 7] FIG. 13 is a schematic cross-sectional view showing an outline of yet another example of a gas permeation device 50 according to a fifth embodiment of the present invention. [Figure 8] FIG. 13 is a cross-sectional schematic diagram illustrating an example of a gas permeation device 60 according to a sixth embodiment of the present invention. [Figure 9] FIG. 11 is a schematic cross-sectional view showing an outline of another example of a gas permeation device 60 according to a sixth embodiment of the present invention. [Figure 10] FIG. 11 is a schematic cross-sectional view showing an outline of yet another example of a gas permeation device 60 according to a sixth embodiment of the present invention. [Figure 11] FIG. 1 is a schematic diagram showing an example of a gas separation membrane module 110 using a spiral-type gas separation membrane 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the gas separation membrane, gas separation membrane module, and gas permeation device according to the present embodiment will be described in detail with reference to the drawings as appropriate. In some embodiments described below, the same elements are given the same reference numerals, and detailed description may be omitted.

[0014] [Gas separation membrane] Fig. 1 is a cross-sectional schematic diagram illustrating an example of a gas separation membrane 10 according to a first embodiment of the present invention. Fig. 1 illustrates the case where the gas separation membrane 10 is a flat membrane. As shown in FIG. 1, a gas separation membrane 10 includes a polyimide resin 1 and a scaly filler 2 . The polyimide resin 1 is one of the super engineering plastics, and is known to have excellent mechanical properties and heat resistance. The gas separation membrane 10 obtains gas separation and gas permeability by the polyimide resin 1, and the size of the molecules passing through can be made smaller than the size of a water molecule, more specifically, smaller than the size of water vapor (dynamic molecular diameter of water vapor 0.3 nm or less) because of the high temperature and high pressure conditions. Here, water vapor has a kinetic molecular diameter similar to that of hydrogen, which is 0.265 nm (2.65 Å). The kinetic molecular diameter of hydrogen is 0.289 nm (2.89 Å). The kinetic molecular diameter of helium is 0.26 nm (2.6 Å). Note that methane, carbon monoxide, and carbon dioxide are approximately the same size as nitrogen and are considered to be relatively large gas molecules. Specifically, the kinetic molecular diameters are said to be 0.36 nm (3.6 Å) for nitrogen, 0.38 nm (3.8 Å) for methane, 0.376 nm (3.76 Å) for carbon monoxide, and 0.33 nm (3.3 Å) for carbon dioxide. Therefore, the gas separation membrane 10 according to this embodiment allows water vapor, hydrogen, and helium to pass through, but does not allow nitrogen, methane, carbon monoxide, carbon dioxide, and other gases with kinetic molecular diameters exceeding 0.3 nm to pass through.

[0015] In this embodiment, the gas separation membrane 10 contains the flake-like filler 2, thereby providing it with heat resistance and pressure resistance in an extremely high temperature and high pressure water vapor atmosphere (for example, under conditions of 180°C and water vapor supply of 0.5 MPaG). In addition, intentionally introducing the flake-like filler 2 into the polyimide resin 1 causes partial disturbance in the packing state of the polyimide resin 1, which has the effect of facilitating gas permeation.

[0016] As shown in FIG. 1, a gas separation membrane 10 is formed on a porous support 3 that supports the gas separation membrane 10. By providing the porous support 3, the pressure resistance of the gas separation membrane 10 can be further improved. Note that the gas separation membrane 10 can also be stacked in multiple sheets to maintain pressure resistance. If sufficient pressure resistance can be maintained by stacking multiple gas separation membranes 10, the porous support 3 does not need to be provided. Also, if a single gas separation membrane 10 has sufficient pressure resistance, it is not necessary to stack multiple gas separation membranes 10 or to provide the porous support 3.

[0017] The polyimide resin 1 contains a diamine component and a tetracarboxylic acid component. The diamine component for constituting the polyimide resin 1 may be an aliphatic diamine, but aromatic diamines and heterocyclic diamines are preferred in order to achieve high heat resistance.Examples of the diamine component include m-phenylenediamine, p-phenylenediamine, 2,4-tolylenediamine, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl methane, 4,4'-diaminodiphenyl methane, 3,4'-diaminodiphenyl methane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl methane, 4 ... Aminodiphenyl ketone, 3,4'-diaminodiphenyl ketone, 2,2'-bis(4-aminophenyl)propane, 2,2'-bis(4-aminophenyl)hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 1,3-bis(3-aminophenoxybenzene), 1,3-(4-aminophenoxybenzene), 1,4-bis(3-aminophenoxybenzene), 1,4-bis(4-aminophenoxybenzene), N,N'-bis(4-aminophenyl)-N,N'-diphenylbenzidine, 4 -Methyl-2,4-bis(4-aminophenyl)-1-pentene, N,N'-bis(4-aminophenyl)-N,N'-diphenylenediamine, 4-methyl-2,4-bis(4-aminophenyl)-2-pentene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-diaminotriphenylamine, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 4-methyl-2,4-bis(p-aminophenylpentane), 5 or 6-amino-1-(p-aminophenyl)-1, 3,3-trimethylindane, bis(p-aminophenyl)phosphine oxide, 4,4'-diaminoazobenzene, 4,4'-diaminodiphenylurea, 2,2-bis[p-(p'-aminophenoxy)phenyl]propane, 2,2-bis[p-(m-aminophenoxy)phenyl]benzophenone, 4,4'-bis(p-aminophenoxy)diphenylsulfone, 9,9-bis(4-aminophenyl)fluorene, 2,7-diaminofluorene, benzoguanamine, acetoguanamine, 3,6-diaminocarbazole, and the like can be used.The aromatic diamine may be a compound in which a hydrogen atom of the aromatic diamine is substituted with at least one substituent selected from the group consisting of a chlorine atom, a fluorine atom, a bromine atom, a methyl group, a methoxy group, a cyano group, a phenyl group, and the like.

[0018] Examples of the tetracarboxylic acid component for constituting the polyimide resin 1 include tetracarboxylic acid dianhydrides, which are tetravalent groups. Examples of the tetracarboxylic acid component include pyromellitic anhydride, 4,4'-oxydiphthalic anhydride, 3,4'-oxydiphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorotetracarboxylic dianhydride, and 1,1,2,3,4,4,5,5,6,7,8,9,9,10,11,12,13,14,15,16,17,18,19,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,55,56,57,58,69,70,71,72,73,74,75,86,87,96,97,98,9 ... Examples of the compounds that can be used include norbornane dianhydride, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic dianhydride, bis(1,3-dihydro-1,3-dioxoisobenzofuran-5-carboxylic acid)ethane-1,2-diyl, bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)1,4-phenylene, and naphthalene-1,4,5,8-tetracarboxylic dianhydride. The tetracarboxylic dianhydride, which is a tetravalent group, may be replaced with a tetracarboxylic diester or a dithioanhydride.

[0019] As a method for producing the polyimide resin 1, a conventionally known method can be applied, as described below. (1) A method in which a diamine and a tetracarboxylic acid component are reacted in a solvent to produce a polyamic acid, which is then molded into a film or the like and heated to form imide bonds. (2) A method in which a diamine and a tetracarboxylic acid component are reacted under heating to directly form a polyimide bond.

[0020] In the above method (1), for example, 4,4'-diaminodiphenyl ether is used as a diamine component, and pyromellitic anhydride is used as a tetracarboxylic acid component, and these components are condensed in a polar organic solvent to form a polyamic acid solution. Thereafter, the polyamic acid solution is applied to a glass plate or the like, heated and dried, and peeled off from the glass plate to produce a flat membrane (film-like) polyimide resin 1. The thickness of the film can be controlled to any desired value by adjusting the concentration and amount of the polyamic acid solution to be applied. In this case, polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and N,N-dimethylsulfoxide are suitable as the organic solvent. The imidization reaction may also be chemical imidization using acetic anhydride or the like.

[0021] For example, at least one of mica, silica, boron nitride, and glass flakes can be used as the scaly filler 2. By using these, it is possible to more reliably provide heat resistance and pressure resistance under an extremely high temperature and high pressure water vapor atmosphere. In this embodiment, a gas separation membrane 10 with improved heat resistance and pressure resistance can be obtained by incorporating scaly filler 2 into polyamic acid or polyamic acid ester and then carrying out an imidization reaction to produce a membrane (film) made of polyimide resin 1 containing the scaly filler 2. In this embodiment, the gas separation membrane 10 can also be produced by adding the scaly filler 2 to the aromatic polyimide solution and then removing the solvent by heating.

[0022] In this embodiment, the scale-like filler 2 is preferably arranged perpendicular to the gas permeation direction. When the scale-like filler 2 is arranged perpendicular to the gas permeation direction in this manner, the surface area in the creeping direction is large against the gas pressure, and therefore pressure resistance can be more effectively exhibited. Such an embodiment of the scaly filler 2 can be achieved by casting a varnish (a solution of polyamic acid or polyamic acid ester) containing the scaly filler 2 on glass and then leaving it to stand for a predetermined time. It is advisable to use degassing in combination with leaving it to stand. Note that the time for leaving it to stand differs depending on the type of polyamic acid or polyamic acid ester used, the type of scaly filler 2, etc., and therefore it is preferable to confirm it by conducting a test or the like in advance. One example of the time for leaving it to stand is degassing treatment at room temperature under reduced pressure for 3 hours, but is not limited to this.

[0023] The content of the scaly filler 2 is preferably 0.2% by mass or more and 30% by mass or less, and more preferably 0.5% by mass or more and 20% by mass or less. If the content of the scaly filler 2 is 0.2% by mass or more, the degree of increase in the solid content in the varnish is sufficient, and the heat resistance and pressure resistance can be more reliably improved. On the other hand, if the content of the scaly filler 2 is 30% by mass or less, gas permeability is not impaired or impossible. The filler content (mass %) can be calculated as follows: Filler mass part / (filler mass part+varnish solid mass part)×100.

[0024] The average particle size of the scaly filler 2 is preferably 2 μm or more and 30 μm or less, and more preferably 2 μm or more and 10 μm or less. If the average particle size of the scaly filler 2 is 2 μm or more, the particles are less likely to aggregate, and can be uniformly dispersed in the varnish. If the average particle size of the scaly filler 2 is 30 μm or less, the particles are not excessively large, and the tensile strength of the polyimide resin 1 is less likely to decrease. Therefore, the heat resistance and pressure resistance of the gas separation membrane 10 can be more reliably improved.

[0025] In this embodiment, a dispersant may be added to the varnish in order to adjust the viscosity of the varnish. The amount of dispersant added is preferably 0.001 or more and 0.01 or less in weight ratio to the polyimide resin 1. In this embodiment, the scaly filler 2 may be one with a dispersant. As the dispersant, a nonionic surfactant can be preferably used. As the dispersant, for example, BYK-W903, BYK-W996, BYK-W9010, etc. manufactured by BYK-Chemie Japan Co., Ltd. can be mentioned.

[0026] The aspect ratio of the scaly filler 2 is preferably 10 or more and 30 or less, and more preferably 15 or more and 30 or less. In this way, the scaly filler 2 has a sufficiently large area in the creeping direction against gas pressure, and can more effectively exhibit pressure resistance.

[0027] In this embodiment, the aspect ratio of the scaly filler 2 can be determined by measuring the particle thickness (minor axis) from the lateral direction of the particle and the particle diameter (major axis) from above the particle with an optical microscope or a scanning electron microscope (SEM), calculating the average value of each, and calculating the ratio of the average major axis to the average thickness (measured with SEM). The average particle diameter of the scaly filler 2 is the average major axis, and can also be determined by a laser diffraction method.

[0028] The porous support 3 is desirably an inorganic material in order to support the polyimide resin 1. Examples of inorganic materials include zeolite, a porous ceramic membrane, and a porous glass membrane. In this embodiment, the polyimide resin 1 containing the scaly filler 2 is poured (applied, etc.) onto the porous support 3 and cured, thereby forming a gas separation membrane 10 on the porous support 3.

[0029] Fig. 2 is a cross-sectional schematic diagram showing an outline of an example of a gas separation membrane 20 according to a second embodiment of the present invention. Fig. 2 illustrates the case where the gas separation membrane 20 is a hollow fiber membrane. 1 and gas separation membrane 20 shown in Fig. 2 are similar except that gas separation membrane 10 is a flat membrane while gas separation membrane 20 is a hollow fiber membrane. That is, gas separation membrane 20 has polyimide resin 1 and scaly filler 2 like gas separation membrane 10.

[0030] The hollow fiber gas separation membrane 20 can be manufactured, for example, by using a varnish in which the aforementioned polyamic acid or polyamic acid ester is impregnated with flake-like filler 2, and a wet membrane forming method using a coagulating liquid. Similarly to the above, when the gas separation membrane 20 is a hollow fiber membrane, the scale-like filler 2 is preferably arranged perpendicular to the gas permeation direction. When the gas separation membrane 20 is a hollow fiber membrane, such an arrangement is achieved by discharging a polyimide solution containing the scale-like filler 2 from a hollow fiber spinning nozzle in a wet membrane production method.

[0031] [Gas separation membrane module] Fig. 3 is a cross-sectional schematic diagram showing an outline of an example of a gas separation membrane module 30 according to a third embodiment of the present invention. Fig. 3 illustrates the case where a gas separation membrane 10 (flat membrane) is used. 3, a gas separation membrane module 30 is configured by housing a lamination element 8, which is configured using a plurality of gas separation membranes 10 according to the first embodiment, in a sealed container 7. The gas separation membranes 10 are supported by a porous support 3. The sealed vessel 7 has at least a mixed gas inlet 4 , a permeate gas outlet 5 , and a non-permeate gas outlet 6 . As shown in FIG. 3, both ends of the mixing element 8 are fixed to the sealed container 7 by resin walls 9 formed by solidifying a thermosetting resin such as an elastomer resin, an acrylate resin, an epoxy resin, or a phenolic resin.

[0032] 3, the sealed container 7 is shaped like a rectangular parallelepiped, and a mixed gas inlet 4 is provided so that a mixed gas containing water vapor flows in perpendicular to the flat gas separation membrane 10. A permeable gas outlet 5 is provided in a direction parallel to the flat gas separation membrane 10 (perpendicular to the direction in which the mixed gas flows in). A non-permeable gas outlet 6 is provided on the opposite surface of the sealed container 7 to the mixed gas inlet 4, across the flat gas separation membrane 10.

[0033] In the gas separation membrane module 30, the mixed gas flowing in from the mixed gas inlet 4 is separated into gas that permeates the gas separation membrane 10 and gas that does not permeate the gas separation membrane 10. The mixed gas may include gas that contains high-temperature, high-pressure steam at 150°C or higher or 180°C or higher (up to about 220°C). The gas that permeates the gas separation membrane 10 contains, for example, molecules such as water (water vapor) and hydrogen, as well as molecules smaller than hydrogen molecules, and atoms (ions). Gases that do not permeate the gas separation membrane 10 include, for example, lithium (ion), sodium (ion), nitrogen, methane, carbon monoxide, carbon dioxide, or molecules larger than water (water vapor) or hydrogen, as well as atoms (ions), such as radioactive substances. The gas that has permeated through gas separation membrane 10 flows out (is discharged) from permeated gas outlet 5 . Furthermore, the gas that has not permeated through gas separation membrane 10 flows out from non-permeation gas outlet 6 .

[0034] Fig. 4 is a cross-sectional schematic diagram showing an outline of an example of a gas separation membrane module 40 according to a fourth embodiment of the present invention. Fig. 4 illustrates the case where a gas separation membrane 20 (hollow fiber membrane) is used. As shown in FIG. 4, the gas separation membrane module 40 includes a cylindrical sealed container 71 and a fiber bundle element 72 that is configured using a large number of gas separation membranes 20 according to the second embodiment housed therein. The sealed vessel 71 has at least a mixed gas inlet 4 , a permeate gas outlet 5 , and a non-permeate gas outlet 6 . As shown in FIG. 4, both ends of the yarn bundle element 72 are fixed to the sealed container 71 by resin walls 9 formed by solidifying a thermosetting resin such as an elastomer resin, an acrylate resin, an epoxy resin, or a phenolic resin.

[0035] 4 is provided with a mixed gas inlet 4 so that a mixed gas containing water vapor flows in parallel to the hollow fiber gas separation membrane 20. A permeate gas outlet 5 is provided in a direction perpendicular to the hollow fiber gas separation membrane 20 (perpendicular to the direction in which the mixed gas flows in). A non-permeate gas outlet 6 is provided at a position opposite the mixed gas inlet 4, with the hollow fiber gas separation membrane 20 in between.

[0036] In the gas separation membrane module 40, the mixed gas flowing in from the mixed gas inlet 4 is separated into gas that permeates the gas separation membrane 20 and gas that does not permeate the gas separation membrane 20. The mixed gas may include gas that contains high-temperature, high-pressure steam at 150°C or higher or 180°C or higher (up to about 220°C). The gas that permeates the gas separation membrane 20 contains, for example, molecules such as water (water vapor) and hydrogen, as well as molecules smaller than hydrogen molecules, and atoms (ions). Gases that do not permeate the gas separation membrane 20 include, for example, lithium (ion), sodium (ion), nitrogen, methane, carbon monoxide, carbon dioxide, or molecules larger than water (water vapor) or hydrogen, atoms (ions), etc., such as radioactive substances. The gas that has permeated through gas separation membrane 20 flows out from permeated gas outlet 5 . Furthermore, the gas that has not permeated through gas separation membrane 20 flows out from non-permeation gas outlet 6 .

[0037] [Gas permeation device] 5 to 7 are schematic cross-sectional views showing an example of a gas permeation device 50 according to a fifth embodiment of the present invention. Note that the gas permeation device 50 shown in Fig. 5 illustrates a case in which the gas permeation device 50 includes a plurality of gas separation membrane modules 30 according to the third embodiment that use gas separation membranes 10 (flat membranes).

[0038] In the present embodiment shown in FIG. 5, two gas separation membrane modules 30 are provided, each having a gas separation membrane 10 arranged in a sealed container 7 having a mixed gas inlet 4, a permeable gas outlet 5, and a non-permeable gas outlet 6. In this embodiment, the non-permeable gas outlet 6 of the gas separation membrane module 30 in the front stage is connected to the mixed gas inlet 4 of the gas separation membrane module 30 in the rear stage, and the gas separation membrane modules 10 are arranged in series. However, the gas permeation device 50 is not limited to this embodiment. As shown in FIG. 6, the gas permeation device 50 may have a plurality of gas separation membrane modules 30 arranged in parallel in the gas permeation device 50. Also, as shown in FIG. 7, the gas permeation device 50 may have a plurality of gas separation membrane modules 30 arranged in series in the gas permeation device 50, and the plurality of gas separation membrane modules 30 may be arranged in parallel. The selection of these embodiments in the gas permeation device 50 according to this embodiment can be appropriately performed depending on the amount of water vapor expected to be generated, the purity of the water vapor after permeating the gas permeation device 50 (the content of impurities contained in the water vapor), and the like.

[0039] 8 to 10 are schematic cross-sectional views showing an example of a gas permeation device 60 according to a sixth embodiment of the present invention. The gas permeation device 60 shown in Fig. 8 illustrates a case in which a plurality of gas separation membrane modules 40 according to the fourth embodiment using gas separation membranes 20 (hollow fiber membranes) are provided. In other words, the example shown in Figs. 8 to 10 differs from the example shown in Figs. 5 to 7 described above in that a gas separation membrane module 40 according to the fourth embodiment using a gas separation membrane 20 (hollow fiber membrane) is used, or a gas separation membrane module 30 according to the third embodiment using a gas separation membrane 10 (flat membrane) is used.

[0040] In the present embodiment shown in FIG. 8, two gas separation membrane modules 40 are provided, each having a gas separation membrane 20 arranged in a sealed container 7 having a mixed gas inlet 4, a permeable gas outlet 5, and a non-permeable gas outlet 6. In this embodiment, the non-permeable gas outlet 6 of the gas separation membrane module 40 in the front stage is connected to the mixed gas inlet 4 of the gas separation membrane module 40 in the rear stage, and the gas separation membrane modules 20 are arranged in series. However, the gas permeation device 60 is not limited to this embodiment. As shown in FIG. 9, the gas permeation device 60 may have a plurality of gas separation membrane modules 40 arranged in parallel. Also, as shown in FIG. 10, the gas permeation device 60 may have a plurality of gas separation membrane modules 40 arranged in series, and the plurality of gas separation membrane modules 40 may be arranged in parallel. The selection of these embodiments of the gas permeation device 60 according to this embodiment can be appropriately performed according to the amount of water vapor expected to be generated, the purity of the water vapor after permeating the gas permeation device 60 (the content of impurities contained in the water vapor), and the like. Although not shown, in this embodiment, the gas separation membrane module 30 and the gas separation membrane module 40 can also be used in combination.

[0041] The gas separation membrane, gas separation membrane module, and gas permeation device according to the present embodiment described above can be suitably employed in cases where, for example, in a high-temperature, high-pressure water vapor environment of 180°C or higher, it is desired to allow gases with small molecular sizes, such as water (water vapor) and hydrogen, to permeate from a mixture of water vapor and other gases, but not allow gases with molecular sizes larger than those of water (water vapor) or hydrogen to permeate.

[0042] The gas separation membrane, gas separation membrane module, and gas permeation device according to this embodiment can be suitably used in facilities that are subject to extremely high temperature and high pressure water vapor atmospheres in a variety of fields, including petrochemistry, chemistry, precision machinery, food, automobiles, nuclear power, the environment, biology, and medicine. EXAMPLES

[0043] The present invention will be described in more detail below by comparing examples in which the present invention is effective with comparative examples in which the present invention is not effective, but the present invention is not limited to the following examples.

[0044] Example 1 Equimolar amounts of 4,4'-bis(3-aminophenoxy)biphenyl and pyromellitic anhydride were added to a separable flask equipped with a stirrer and a nitrogen inlet tube, and N-methyl-2-pyrrolidone (NMP) was added so that the concentration of these was 15% by mass. After that, the mixture was stirred in an ice bath under a nitrogen stream for 1 hour and at room temperature (20 to 25°C) for 7 hours to obtain a viscous polyamic acid solution (varnish).

[0045] Next, mica (M-XF, manufactured by Repco Co., Ltd.) having an average particle size of 4 μm and an average aspect ratio of 15 was added as a scaly filler 2 in an amount of 5% by mass relative to the polyamic acid solution, and stirred at room temperature for 24 hours. The mica-containing polyamic acid varnish was diluted to an appropriate concentration with NMP and cast on glass. The mica-containing polyamic acid varnish cast on the glass was degassed at room temperature for 3 hours under reduced pressure, and then heated at 80° C. for 2 hours. Thereafter, it was peeled off from the glass plate and heated at 100° C., 150° C., 200° C., and 250° C. under reduced pressure for 2 hours each to obtain a flat-membrane mica-containing polyimide membrane (gas separation membrane 10).

[0046] Ten sheets of the polyimide membrane were prepared and alternately sandwiched with ten sheets of plate-like zeolite to form an element with a cassette structure, thereby forming a gas separation membrane module 30 having the configuration shown in Fig. 3. Nitrogen gas (mixed gas) containing water vapor was then supplied to this gas separation membrane module 30, and the water vapor was permeated (separated).

[0047] First, the gas separation membrane module 30 was placed in a thermostatic chamber, and a mixed gas was supplied to the gas separation membrane module 30 at 180°C to allow water vapor to permeate. The pressure of the supplied gas was set to 0.5 MPaG. The flow rate of water vapor was adjusted so that the amount of water supplied was 0.5 MPaG.

[0048] The system was operated continuously for 500 hours, but no pressure drop was observed. After operation, the cassette was disassembled and the appearance of the polyimide membrane was checked, and no cracks were observed, indicating that the membrane was in good condition. When examined with an SEM, the flake-like fillers were found to be aligned perpendicular to the gas permeation direction. However, the flake-like fillers were not all neatly aligned in the vertical direction; for example, there were overlapping areas.

[0049] Furthermore, when the amount of mica added was increased to 28 mass % and a similar water vapor permeation test was carried out, no cracks or the like were observed in the appearance of the polyimide film, and the film was excellent. Furthermore, similar water vapor permeation tests were conducted using mica (S-325, manufactured by Repco Co., Ltd.) with an average particle size of 27 μm and an average aspect ratio of 30 as a flake-like filler in an amount of 0.3 to 3 mass% relative to the polyamic acid solution, and boron nitride (GP particle size D50, manufactured by Denka Co., Ltd.) with an average particle size of 8 μm and an average aspect ratio of 10 in an amount of 3 to 20 mass%. In either case, no cracks were observed in the appearance of the polyimide film, and the results were good.

[0050] Example 2 Equimolar amounts of 4,4'-diaminodiphenyl ether and 4,4'-oxydiphthalic anhydride were added to a separable flask equipped with a stirrer and a nitrogen inlet tube, and polymerized together with p-chlorophenol at 180°C for 4 hours to obtain a polyimide solution with a polymer concentration of 12% by mass.

[0051] Next, mica (S-XF, manufactured by Repco Corporation) having an average particle size of 3 μm and an average aspect ratio of 15 was added as scaly filler 2 in an amount of 5% by mass relative to the polyimide solution, and the mixture was stirred for 6 hours.

[0052] The obtained mica-containing polyimide solution was discharged from a hollow fiber spinning nozzle, and the discharged mica-containing polyimide in the form of hollow fiber was placed under a nitrogen atmosphere and then immersed in a coagulation liquid consisting of a 72% by mass ethanol aqueous solution at 0°C to obtain a wet fiber. This was immersed in ethanol at 50°C for 2 hours and dehydrated. After immersing in isooctane at 80°C for 3 hours, it was dried to 100°C, and then the temperature was raised stepwise to 250°C for heat treatment to obtain a hollow fiber membrane (gas separation membrane 20).

[0053] An evaluation element with an effective length of about 5 cm was produced using 50 of the hollow fiber membranes, a stainless steel pipe, and epoxy resin as a cured resin. This element was attached to a stainless steel container to form a gas separation membrane module 40 as shown in Fig. 4. Nitrogen gas (mixed gas) containing water vapor was then supplied to this gas separation membrane module 40 to permeate (separate) the water vapor.

[0054] First, the gas separation membrane module 40 was placed in a thermostatic chamber, and a mixed gas was supplied to the gas separation membrane module 40 at 180°C to allow water vapor to permeate. The pressure of the supplied gas was set to 0.5 MPaG. The flow rate of water vapor was adjusted so that the amount of water supplied was 0.5 MPaG.

[0055] The system was operated continuously for 100 hours, but no significant pressure fluctuations were observed. After operation, the module was disassembled and the appearance of the hollow fiber membrane was checked, and no cracks were observed, indicating that the membrane was in good condition. When examined with an SEM, it was found that the flake-like fillers were arranged perpendicular to the gas permeation direction. However, the flake-like fillers were not all neatly aligned in the vertical direction; for example, there were overlapping areas.

[0056] When the amount of mica added was increased to 30 mass % and a similar water vapor permeation test was carried out, no cracks or the like were observed in the external appearance of the hollow fiber membrane, and the results were good. In addition, similar water vapor permeation tests were conducted using mica (M-400, manufactured by Repco Co., Ltd.) with an average particle size of 24 μm and an average aspect ratio of 28 as a flake-like filler in an amount of 0.2 to 2 mass% relative to the polyamic acid solution, and boron nitride (GP particle size D50, manufactured by Denka Co., Ltd.) with an average particle size of 8 μm and an average aspect ratio of 10 in an amount of 3 to 20 mass%.In all cases, no cracks were observed in the appearance of the hollow fiber membrane, and the results were good.

[0057] Comparative Example 1 A polyamic acid solution was prepared using the same method and raw materials as in Example 1 described above. Next, this polyamic acid solution (varnish) was diluted to an appropriate concentration with NMP and cast onto glass. The polyamic acid varnish cast onto the glass was degassed under reduced pressure at room temperature for 3 hours, and then heated at 80°C for 2 hours. Thereafter, it was peeled off from the glass plate and heated under reduced pressure at 100°C, 150°C, 200°C, and 250°C for 2 hours each to obtain a polyimide membrane. The polyimide membrane according to Comparative Example 1 may correspond to the gas separation membrane described in Patent Document 1 formed as a flat membrane in that it does not contain mica.

[0058] Ten sheets of the polyimide membrane were prepared and alternately sandwiched with ten sheets of zeolite plates to form a cassette-structured element, which was used to form a gas separation membrane module as shown in Fig. 3. Nitrogen gas (mixed gas) containing water vapor was then supplied to this gas separation membrane module to perform water vapor permeation (separation). First, a gas separation membrane module was placed in a thermostatic chamber, and a mixed gas was supplied to the gas separation membrane module at 180°C to allow water vapor to pass through. The pressure of the supplied gas was set to 0.5 MPaG. The flow rate of water vapor was adjusted so that the amount of water supplied was 0.5 MPaG.

[0059] After 50 hours of continuous operation, the pressure gradually began to drop, so the pressure of the supply gas was adjusted to 0.5 MPaG, but the pressure continued to drop and suddenly dropped after 100 hours. From this, it was determined that the polyimide film was damaged, and operation was stopped. After operation, the cassette was disassembled and the appearance of the polyimide film was confirmed, and it was confirmed that cracks had occurred in part of the polyimide film. From the results of Comparative Example 1, it was confirmed that the desired effect could not be obtained even if plate-shaped zeolite was used, unless the scaly filler 2 was used.

[0060] In addition, a similar water vapor permeation test was carried out using mica (S-150H, manufactured by Repco Co., Ltd.) with an average particle size of 160 μm and an average aspect ratio of 80 as a scaly filler in an amount of 25 mass % relative to the polyamic acid solution. As a result, the pressure gradually decreased, so operation was stopped after 300 hours. After operation, the cassette was disassembled and the appearance of the polyimide film was checked, and it was confirmed that cracks had occurred in part of the polyimide film.

[0061] Comparative Example 2 A polyimide solution was prepared using the same method and raw materials as in Example 2. A hollow fiber membrane was obtained in the same manner as in Example 2. The polyimide membrane according to Comparative Example 2 can be equivalent to the gas separation membrane described in Patent Document 1 formed from a hollow fiber membrane in that it does not contain mica. An evaluation element with an effective length of about 5 cm was produced using 50 of the hollow fiber membranes, a stainless steel pipe, and epoxy resin as a cured resin. This element was attached to a stainless steel container to form a gas separation membrane module with the configuration shown in Figure 4. Nitrogen gas (mixed gas) containing water vapor was then supplied to this gas separation membrane module to permeate (separate) the water vapor.

[0062] First, a gas separation membrane module was placed in a thermostatic chamber, and a mixed gas was supplied to the gas separation membrane module at 180°C to allow water vapor to pass through. The pressure of the supplied gas was set to 0.5 MPaG. The flow rate of water vapor was adjusted so that the amount of water supplied was 0.5 MPaG.

[0063] After 15 hours of continuous operation, the pressure suddenly dropped, so it was determined that the hollow fiber membrane had been damaged and operation was halted. After operation was completed, the module was dismantled and the appearance of the hollow fiber membrane was checked, revealing that several hollow fibers had broken and that the hollow fiber membrane had become embrittled.

[0064] In addition, a similar water vapor permeation test was carried out using mica (M-325, manufactured by Repco Co., Ltd.) with an average particle size of 26 μm and an average aspect ratio of 20 as a scaly filler in an amount of 50% by mass relative to the polyimide acid solution. As a result, the pressure gradually decreased, so operation was stopped after 60 hours. After operation, the module was disassembled and the appearance of the hollow fiber membrane was checked, and it was confirmed that several hollow fiber membranes were broken.

[0065] The gas separation membrane, gas separation membrane module, and gas permeation device according to the present invention have been described in detail above through embodiments and examples, but the present invention is not limited to the above-mentioned embodiments and examples, and various modifications are included. For example, the above-mentioned embodiments have been described in detail to easily explain the present invention, and are not necessarily limited to those having all of the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0066] For example, the gas separation membrane may be a flat membrane or a hollow fiber membrane, or may be a pleated membrane (not shown) formed by folding a flat membrane multiple times. The pleated gas separation membrane has a larger surface area than a flat membrane, and therefore improves the treatment efficiency.

[0067] 11 is a schematic diagram showing an example of a gas separation membrane module 110 using a spiral-type gas separation membrane 10. The gas separation membrane module 110 shown in FIG 11 is formed by winding a flat gas separation membrane 10 in a spiral shape. As shown in Fig. 11, when a flat gas separation membrane 10 is wound in a spiral shape, even if the strength of each gas separation membrane 10 is not sufficiently high, the strength is increased by winding it in a spiral shape, so that it can be suitably used without a porous support 3, etc. When the gas separation membrane 10 in a gas separation membrane module 110 is in the spiral shape as shown in Fig. 11, it is preferable to alternately provide the gas separation membrane 10 and a gas flow path material 111 made of a porous material in a cylindrical sealed container 71.

[0068] One end face of the cylindrical sealed container 71 serves as a mixed gas inlet 4, and the other end face serves as a non-permeate gas outlet 6. In the gas separation membrane module 110, a cylindrical body 112 with holes on the side is disposed in the center of the spirally wound gas separation membrane 10. The cylindrical body 112 has a permeate gas outlet 5 on the other end face of the cylindrical sealed container 71.

[0069] The mixed gas flowing in from the mixed gas inlet 4 passes through the gas flow path material 111, while molecules such as water (water vapor) and hydrogen, molecules smaller than hydrogen molecules, and atoms (ions) permeate the gas separation membrane 10 and flow into the cylindrical body 112. The molecules and atoms (ions) that flow into the cylindrical body 112 pass through the cylindrical body 112 and flow out from the permeated gas outlet 5. On the other hand, water (water vapor) and molecules and atoms (ions) larger than hydrogen cannot permeate gas separation membrane 10, and so pass through gas flow path material 111 and flow out from non-permeation gas outlet 6. In other words, the gas flowing out from non-permeation gas outlet 6 may contain water (water vapor) that did not permeate gas separation membrane 10 and molecules and atoms (ions) larger than hydrogen. [Explanation of symbols]

[0070] 1 Polyimide resin 2. Scaly filler 3 Porous support 4 Mixed gas inlet 5 Permeation gas outlet 6 Non-permeable gas outlet 7. Airtight containers 8 Stacking elements 9. Resin Wall 10 Gas separation membrane 20 Gas separation membrane 30 Gas separation membrane module 40 Gas separation membrane module 50 Gas Permeation Device 60 Gas Permeation Device 71 Airtight containers 72 Yarn bundle element 110 Gas separation membrane module 111 Gas flow path material 112 Cylinder

Claims

1. A gas separation membrane comprising a polyimide resin and a scaly filler.

2. The gas separation membrane according to claim 1, The scaly filler is at least one of mica, silica, boron nitride, and glass flakes. A gas separation membrane characterized by:

3. 2. The gas separation membrane according to claim 1, The content of the scaly filler is 0.2% by mass or more and 30% by mass or less. A gas separation membrane characterized by:

4. 2. The gas separation membrane according to claim 1, The average particle size of the scaly filler is 2 μm or more and 30 μm or less. A gas separation membrane characterized by:

5. The gas separation membrane according to claim 1, The aspect ratio of the scaly filler is 10 or more and 30 or less. A gas separation membrane characterized by:

6. 2. The gas separation membrane according to claim 1, The scale-like filler is arranged in a direction perpendicular to the gas permeation direction. A gas separation membrane characterized by:

7. The gas separation membrane according to claim 1, The membrane is in the form of a hollow fiber membrane, a flat membrane, a pleated type formed by folding the flat membrane multiple times, or a spiral type formed by winding the flat membrane in a spiral shape. A gas separation membrane characterized by:

8. The gas separation membrane according to claim 1, A porous support is provided to support the gas separation membrane. A gas separation membrane characterized by:

9. 2. The gas separation membrane according to claim 1, The kinetic molecular diameter of the molecules passing through is 0.3 nm or less. A gas separation membrane characterized by:

10. A gas separation membrane according to any one of claims 1 to 9 is disposed in a sealed container having a mixed gas inlet, a permeate gas outlet, and a non-permeate gas outlet. A gas separation membrane module comprising:

11. The gas separation membrane module according to claim 10, The gas separation membrane is in the form of a hollow fiber membrane, a flat membrane, a pleated type formed by folding the flat membrane multiple times, or a spiral type formed by winding the flat membrane in a spiral shape. A gas separation membrane module comprising:

12. The present invention comprises two or more gas separation membrane modules each having the gas separation membrane according to any one of claims 1 to 9 arranged in a sealed container having a mixed gas inlet, a permeate gas outlet, and a non-permeate gas outlet.

1. A gas permeable device comprising:

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