Gas separation membranes and gas separation membrane assemblies

Abstract

Provided is a gas separation membrane and a gas separation membrane module that can prevent damage to the gas separation membrane during operation and exhibit excellent separation performance stably for a long period of time. The gas separation membrane is a gas separation membrane having a separation functional layer in at least a part thereof, and the shape of the gas separation membrane is fibrous or membranous. The separation functional layer contains a base material and particles.

Description

Technical Field

[0001] This invention relates to gas separation membranes and gas separation membrane assemblies. Background Technology

[0002] Membrane separation is a known method for selectively separating and purifying specific components from various gas mixtures. Compared to other separation and purification methods, membrane separation utilizes pressure and concentration differences, resulting in lower thermal energy consumption and energy savings, thus attracting attention. However, while gas separation processes require heat and chemical resistance, a stable supply of gas separation membranes that meet these requirements remains a challenge.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent document 1 describes a separation membrane composed of a polymer matrix and a carbon nanotube nonwoven fabric.

[0006] Patent document 2 discloses a separation membrane incorporating carbon as a matrix and various materials as reinforcing materials.

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-237127

[0008] Patent Document 2: Japanese Patent Publication No. 2011-527231 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] The separation membrane disclosed in Patent Document 1 can ensure mechanical durability by reinforcing the polymer matrix with nonwoven fabric, but it is not heat-resistant enough as a gas separation membrane due to the low heat resistance of the polymer matrix.

[0011] The separation membrane disclosed in Patent Document 2 has the following problems: the matrix and the reinforcing material are easily separated at the interface due to simple combination; it will be damaged during long-term operation; and gas leakage will lead to unstable operation.

[0012] The objective of this invention is to provide a gas separation membrane and a gas separation membrane assembly that can prevent damage to the gas separation membrane during operation and can stably maintain excellent separation performance for a long time.

[0013] Problem-solving methods

[0014] To solve the above problems, the gas separation membrane of the present invention has the following configuration. That is,

[0015] It is a gas separation membrane with at least a separation functional layer, the gas separation membrane being fibrous or membrane-like in shape, and the separation functional layer comprising a matrix and particles.

[0016] The gas separation membrane assembly of the present invention has the following configuration. That is,

[0017] It is a gas separation membrane assembly having the form of housing the aforementioned gas separation membrane in a housing.

[0018] The gas separation membrane of the present invention preferably comprises at least a portion of particles with an aspect ratio of 10 or more.

[0019] In the gas separation membrane of the present invention, the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or more relative to the reference axis is preferably 0.1 or more and 1.0 or less.

[0020] In the gas separation membrane of the present invention, the particles are preferably fibrous.

[0021] In the gas separation membrane of the present invention, the particles are preferably in the form of plates.

[0022] In the gas separation membrane of the present invention, the particle content in the separation functional layer is preferably 10% by volume or less.

[0023] In the gas separation membrane of the present invention, the orientation coefficient F of the particles with an aspect ratio of 10 or more relative to the reference axis is preferably +0.1 or more and +1.0 or less.

[0024] The gas separation membrane of the present invention preferably has a volume percentage of 1% or more of particles that exist independently without contact with other particles in the total volume of all particles.

[0025] The gas separation membrane of the present invention is preferably fibrous in shape.

[0026] In the gas separation membrane of the present invention, the carbon element ratio of the matrix is ​​preferably 70 atomic% or more and 100 atomic% or less. When the carbon element ratio of the matrix is ​​set as X (atomic%) and the carbon element ratio of the particles is set as Y (atomic%), (|XY| / X)×100 is 30% or less.

[0027] In the gas separation membrane of the present invention, the matrix is ​​preferably a carbide of a polymer compound.

[0028] The gas separation membrane of the present invention preferably comprises one or more particles selected from the group consisting of carbon black, graphite, expanded graphite, carbon nanotubes, carbon nanoribbons, carbon nanotubes, graphene, graphene oxide and fullerene.

[0029] Invention Effects

[0030] According to the present invention, a gas separation membrane and a gas separation membrane assembly are provided that can suppress damage to the gas separation membrane and can stably maintain excellent separation performance for a long time. Detailed Implementation

[0031] The present invention is a gas separation membrane, which is a gas separation membrane having at least a separation functional layer. The gas separation membrane is fibrous or membrane-like in shape, and the separation functional layer comprises a matrix and particles.

[0032] <Gas Separation Membrane>

[0033] At least a portion of the gas separation membrane of the present invention has a separation functional layer. Having a separation functional layer in at least a portion of the gas separation membrane means that the layered portion with separation function (separation functional layer) forms at least a portion of the material, while the portion without a separation functional layer is considered as a portion without separation function, and is in a state where gas flow can be controlled. The state where gas flow can be controlled means a state in which gas is substantially not allowed to pass through, meaning that, based on nitrogen, its permeability is less than 0.01 nmol / (m²). 2 sPa).

[0034] The separation functional layer constituting the gas separation membrane of the present invention is composed of a matrix and particles. The matrix in the separation functional layer refers to the sea portion of a so-called island structure. Furthermore, the particles in the separation functional layer refer to the island portion of a so-called island structure. The determination of the island structure can be appropriately applied using conventionally known methods; any method capable of reasonably separating the sea portion and the island portion can be chosen arbitrarily.

[0035] The material of the matrix is ​​not particularly limited, but the carbon element ratio X is preferably 70 atomic% or more and 100 atomic% or less. A higher carbon element ratio X results in superior film performance, chemical resistance, and heat resistance, and is therefore preferred, more preferably 80 atomic% or more. On the other hand, lower carbon content leads to greater flexibility and increased resistance to breakage, thus improving long-term durability; therefore, the carbon element ratio X of the matrix is ​​preferably 99 atomic% or less, more preferably 92 atomic% or less. There are no particular limitations on the constituent elements of the matrix other than carbon; it may contain hydrogen, oxygen, nitrogen, boron, sulfur, silicon, etc., and may also contain alkali metals, alkaline earth metals, etc. The above element ratios are determined by various analytical methods, such as energy-dispersive X-ray spectrophotometry.

[0036] There are no particular restrictions on the material of the matrix; examples include thermosetting resins, thermoplastic resins, and other polymer compounds and inorganic materials.

[0037] Here, examples of thermoplastic resins used as the matrix include, for instance, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polypropylene terephthalate (PTT), polyethylene naphthalate (PENP), liquid crystal polyester, polyethylene (PE), polypropylene (PP), polybutene, styrene resins, polyoxymethylene (POM), polyamide (PA), polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), and polyvinyl alcohol (P... Poly(VA), polyphenylene sulfide (PPS), polyphenylene ether (PPE), modified PPE, polyphenylene ether (PPO), modified PPO, polyimide (PI), polyamide-imide (PAI), polyetherimide (PEI), polysulfone (PSU), modified PSU, polyethersulfone (PES), polyketone (PK), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketone-ketone (PEKK), polyarylate (PAR), polyacrylonitrile (PAN), polyethernitrile (PEN), phenolic resins, phenoxy resins, fluorinated resins, etc. These can also be copolymers, modifiers, or resins blended from two or more of these compounds.

[0038] In addition, examples of thermosetting resins used as the matrix include unsaturated polyester resins, alkyd resins, melamine resins, urea resins, polyimide resins, diallyl phthalate resins, lignin resins, epoxy resins, and urethane resins. Copolymers, modifiers, and resins blended from two or more of these resins may also be used.

[0039] Furthermore, examples of inorganic materials used as the matrix include zeolites, silica, alumina, metallic materials, and carbon materials. As a carbon material, considering ease of controlling the carbon element ratio X of the matrix, carbides of polymeric compounds are preferred; for example, carbon materials obtained by calcining a polymeric compound containing at least one of the aforementioned thermoplastic resins and thermosetting resins are examples. Phenolic resins, polyacrylonitrile, and polyimide are particularly preferred.

[0040] Here, having separation function means having the ability to generate a difference in gas permeation rate, which means that the separation coefficient is 1.2 or higher based on the permeation rate ratio of CO2 to CH4 (CO2 / CH4).

[0041] By combining with the matrix, the particles can suppress damage to the separation functional layer. Furthermore, if the particles can effectively suppress damage to the separation functional layer, then the ability to permeate and separate gases is also preferred.

[0042] There are no particular restrictions on the material of the particles, but it can be observed that the closer the carbon ratio Y of the particles is to the carbon ratio X of the matrix, the better the adhesion to the matrix and the higher the strength. From this perspective, the (|XY| / X)×100, which is an indicator of the closeness of the carbon ratio between the matrix and the particles, is preferably 30% or less. (|XY| / X)×100 is preferably 20% or less, and more preferably 0% or more and 10% or less. Here, there are no particular restrictions on the constituent elements other than carbon, provided that the above effects are achieved. It can contain oxygen, nitrogen, boron, sulfur, silicon, etc., and can also contain alkali metals, alkaline earth metals, etc. For the above element amounts, energy dispersive X-ray spectrometry or similar methods are applied to a transmission electron microscope that can observe the small parts of the matrix and particles separately. All elements except hydrogen are taken as objects, and appropriate adjustments are made to detect signals that can be used to calculate the element ratio, thereby performing elemental analysis.

[0043] The particles used in the gas separation membrane of the present invention preferably have a carbon element ratio Y of 60 atomic% or more and 100 atomic% or less. A higher carbon element ratio Y results in superior membrane performance, chemical resistance, and heat resistance, and is therefore preferred; more preferably, it is 70 atomic% or more, and even more preferably 80 atomic% or more. On the other hand, there is a tendency for a lower carbon element ratio to result in greater softness and increased resistance to breakage; therefore, to ensure long-term durability and improve the effect of preventing membrane breakage, a carbon element ratio Y of 99 atomic% or less is more preferred.

[0044] The particles used in the gas separation membrane of the present invention can be selected from various materials such as polymers, biologically derived materials, and inorganic materials, and can be used alone or in combination. Examples of polymers used in the present invention include polyesters, polyamides, polyimides, polyethers, polyphenylene sulfides, polyetheretherketones, and copolymers based thereon.

[0045] The particles used in the gas separation membrane of the present invention are preferably inorganic materials. Inorganic materials tend to have a high elastic modulus, thus easily exhibiting a reinforcing effect when combined with a matrix. Furthermore, they tend to have high heat resistance and chemical resistance. There are no particular limitations on the inorganic materials; examples include carbon compounds such as silicon carbide, boron carbide, and carbon nitride, as well as materials primarily composed of carbon. To meet the aforementioned carbon ratio requirements, these materials can be used in combination, such as by coating the surface of the material with carbon.

[0046] Furthermore, the particles constituting the separation functional layer of the gas separation membrane of the present invention are preferably selected from one or more of the group consisting of carbon black, graphite, expanded graphite, carbon nanotubes, carbon nanoribbons, carbon nanotubes, graphene, graphene oxide, and fullerene. These materials readily allow the carbon element ratio to approach that of the matrix, thus easily exhibiting a reinforcing effect when combined with the matrix. Moreover, among these materials, from the perspective of having a large specific surface area and easily increasing the bonding interface that exhibits the reinforcing effect of the particles on the matrix constituting the separation functional layer, it is more preferable, particularly, to select one or more of the group consisting of carbon black, carbon nanotubes, carbon nanoribbons, carbon nanotubes, graphene, graphene oxide, and fullerene. From a cost perspective, it is even more preferable to select one or more of the group consisting of carbon black, carbon nanotubes, graphene, graphene oxide, and fullerene.

[0047] Furthermore, in the separation functional layer of the present invention, at least a portion of the particles preferably include particles with an aspect ratio of 10 or more. A large average aspect ratio facilitates the composite effect of the matrix and particles; therefore, the average aspect ratio of the particles is more preferably 300 or more, further preferably 800 or more, and particularly preferably 1,500 or more. While an upper limit for the average aspect ratio of the particles is not strictly necessary, considering the ease of micro-dispersion of the particles in the separation functional layer, and especially in the case of using a liquid to form the separation functional layer, ensuring the fluidity of the liquid and forming a uniform separation functional layer, the average aspect ratio of the particles in the separation functional layer is preferably 2,000 or less. Here, aspect ratio refers to the ratio (Ll / Ls) of the shortest length Ls to the longest length Ll from the three-dimensional data of a single particle extracted and dispersed in the matrix by a three-dimensional microscope. The length Ls of the shortest portion generally corresponds to the thickness of the thinnest portion in the case of graphene, and to the diameter of the finest portion in the case of carbon nanotubes. Furthermore, regarding the length Ll of the longest portion, in the case of graphene, the portion capable of measuring the longest distance is extracted and measured within a flat, plate-like shape, using the edge as a reference. For carbon nanotubes, this corresponds to the end-to-end length of a bent carbon nanotube. For three-dimensional microscopy, there are no particular limitations as long as the matrix and particles can be separated and observed. Preferably, analytical methods that allow for the separation, observation, and analysis of the matrix and particles as electronic information are selected, such as sections and views observed continuously using a scanning electron microscope while cutting the cross-section with an ion beam, or methods using a transmission electron microscope and computed tomography.

[0048] The shape of the particles in this invention is not particularly limited, but the shape of the particles is preferably fibrous or flat.

[0049] When a liquid coating process is used during the molding of the functional layer, fibrous particles have the property of easily orienting along the flow direction. Through orientation, they exhibit reinforcement in a specific direction, particularly towards the fiber axis, thus improving the bending stiffness in the direction orthogonal to the fiber axis, making them preferred. Examples of fibrous particles include, for instance, cellulose nanofibers, carbon nanofibers, carbon nanoribbons, carbon nanotubes, synthetic resin fibers, glass fibers, carbon fibers, silicon carbide fibers, metal fibers, and whiskers.

[0050] On the other hand, when a liquid coating process is used during the molding of the separated functional layers, flat particles have the property of easily undergoing planar orientation along the flow direction. When the orientation direction is the MD direction, they easily exhibit reinforcement in both the MD and TD directions, and are therefore preferred. Examples of flat particles include graphene, graphene oxide, talc, and mica.

[0051] When the separation functional layer of the present invention contains particles with an aspect ratio of 10 or higher, the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is preferably 0.1 or higher and 1.0 or lower. If the particles are oriented in a specific direction, they easily exhibit a reinforcing effect when combined with the matrix, and this is therefore a preferred approach. In this case, the direction in which the particles are oriented is arbitrary, but it is preferable to appropriately design the manufacturing method to orient them in the direction in which the reinforcing effect is most desired. When a method for forming the separation functional layer using a liquid is selected, an arbitrary orientation state can be set by forming the separation functional layer while the liquid flows along a set orientation direction.

[0052] Here, the orientation coefficient F of the particle in the separation functional layer of the present invention is represented by F = (3cos²) / (2π√(3 ... -1) / 2 represents. As the orientation angle, focusing on a single particle of the separation functional layer extracted by a three-dimensional microscope as previously described, its three-dimensional data is approximated as an ellipsoid using the least squares method. When the major axis of the resulting ellipsoid is set as D, and given that the gas separation membrane of this invention has a fibrous shape, the fiber axis is used as the reference axis, and the projection length Dcos of the major axis D of the ellipsoid relative to the reference axis is... Calculate the orientation angle Furthermore, when the gas separation membrane of the present invention is membrane-shaped, with the normal to the membrane surface as the reference axis and the major axis of the resulting ellipsoid set as D, the ellipsoid is rotated 90° from its major axis D toward the direction of its shortest minor axis, with the center of the ellipsoid as the reference. This allows the projection length Dcos of the major axis D of the ellipsoid onto the reference axis to be calculated. Calculate the orientation angle .

[0053] Here, the orientation coefficient F refers to the orientation coefficient that is considered fully oriented at +1.0, vertically oriented at -0.5, and unoriented at 0.0. It can quantitatively represent the orientation state of particles.

[0054] Here, the orientation coefficient F is calculated for particles with an aspect ratio of 10 or higher. Ten arbitrary particles with an aspect ratio of 10 or higher are selected, and for each particle, the orientation coefficient is calculated relative to the same reference axis and defined as the average value of 10 points.

[0055] When the gas separation membrane of the present invention is fibrous, if the particles in the separation functional layer are oriented in the separation functional layer, it is possible to suppress the breakage when the separation functional layer is subjected to tensile force due to airflow vibration or the like during operation. Therefore, the absolute value of the orientation coefficient F of the particles relative to the reference axis is preferably 0.1 or more and 1.0 or less, more preferably 0.2 or more and 1.0 or less.

[0056] Furthermore, when the gas separation membrane of the present invention is in the form of a membrane, if the particles in the separation functional layer are oriented in the separation functional layer, it is possible to suppress the breakage of the separation functional layer when tensile force is generated on it due to vibration of airflow during operation. Therefore, the absolute value of the orientation coefficient F of the particles relative to the reference axis is preferably 0.1 or more and 1.0 or less, more preferably 0.2 or more and 1.0 or less.

[0057] Furthermore, when the gas separation membrane of the present invention is fibrous, the orientation coefficient F of the particles relative to the reference axis is preferably +0.1 or more and +1.0 or less. The higher the orientation coefficient F, the more the particles are oriented along the fiber axis direction, which serves as the reference axis. Therefore, the particle-induced enhancement effect on the separation functional layer is more easily exhibited, especially the enhancement effect in the fiber stretching direction. Thus, a gas separation membrane capable of stable operation for extended periods without breakage or damage can be provided, which is preferred. Therefore, the orientation coefficient F is more preferably +0.2 or more and +1.0 or less, further preferably +0.5 or more and +1.0 or less, and particularly preferably +0.65 or more and +1.0 or less.

[0058] Furthermore, when the gas separation membrane of the present invention is membrane-like, the orientation coefficient F of the particles relative to the reference axis is preferably +0.1 or more and +1.0 or less. The higher the orientation coefficient F, the more the particles are oriented along the reference axis, and therefore the easier it is to exhibit the particle-induced enhancement effect on the separation functional layer, especially the excellent enhancement effect on external forces from the membrane surface in the normal direction. Therefore, a gas separation membrane capable of long-term stable operation without breakage can be provided, which is preferred. Thus, the orientation coefficient F is more preferably +0.2 or more and +1.0 or less, further preferably +0.5 or more and +1.0 or less, and particularly preferably +0.65 or more and +1.0 or less.

[0059] Furthermore, in the separation functional layer constituting the gas separation membrane of the present invention, it is preferable that the elastic modulus of the particles is higher than that of the matrix. By making the elastic modulus of the particles higher than that of the matrix, the separation functional layer is protected from damage during composite formation, thus preventing damage during operation as a gas separation membrane and enabling long-term stable use.

[0060] Here, "the elastic modulus of the particles being higher than that of the matrix" means that the ratio of the elastic modulus of the particles to the elastic modulus of the matrix (hereinafter referred to as the elastic modulus ratio) is in the range of 10 to 20,000. The higher the elastic modulus of the particles, the easier it is to obtain a reinforcing effect and prevent breakage. On the other hand, the lower the elastic modulus, the more pliable the deformation, thus mitigating instantaneous impact forces. Therefore, an elastic modulus ratio of 200 to 15,000 is more preferred.

[0061] Regarding the aforementioned elastic modulus ratio, an elastic modulus mapping analysis was performed on the cross-section of the separated functional layer using atomic force microscopy. In the elastic modulus mapping image obtained by observing a 1μm × 1μm range, the ratio of the elastic modulus of the point showing the highest elastic modulus to the point showing the lowest elastic modulus was used. The point showing the lowest elastic modulus and forming a seam was taken as the elastic modulus of the matrix. For samples with more than 10 points, the positions were changed, and the average value of the elastic modulus ratio resolved at each observation location was used as the elastic modulus ratio referred to in this invention.

[0062] Furthermore, the surface of the particles used in this invention can be chemically modified using carboxyl groups, amide groups, etc., to further improve adhesion to the matrix through chemical bonding, which is therefore preferred. On the other hand, the fewer surface functional groups the particles have, the better their chemical resistance is. Therefore, relative to all the bonding components of carbon, the ratio of O=CO components from carboxyl groups to O=CN components from amide bonds is preferably 0.1% to 30%.

[0063] Furthermore, the separation functional layer constituting the gas separation membrane of the present invention may use one type of particles or a combination of two or more types of particles. When using a combination of two or more types of particles, it is preferable to include particles with an aspect ratio of 10 or higher. The greater the amount of particles with an aspect ratio of 10 or higher added, the easier it is to obtain a composite effect between the matrix and the particles, and therefore it is preferred. In the total 100% by volume of all particles, the content of particles with an aspect ratio of 10 or higher is more preferably set to an addition amount of 50% by volume or more, and even more preferably 80% by volume or more.

[0064] In the separation functional layer constituting the gas separation membrane of the present invention, the volume percentage of particles existing independently of other particles in the total volume of all particles is preferably 1% by volume or more, more preferably 5% by volume or more. If the volume percentage of particles existing independently without contact with other particles is within the above-mentioned preferred range, it is easy to obtain a composite effect between the matrix and the particles.

[0065] Here, in the gas separation membrane of the present invention, the volume ratio of particles that exist independently without contact with other particles is determined as follows: based on the three-dimensional data of particles extracted by three-dimensional microscopy of the separation functional layer as previously described, particles that exist independently without contact with other particles are identified, and their volume percentage is calculated. It should be noted that, considering bias, cases where there are more than 10 particles in the data are used. In cases where there are no more than 10 particles in a single data set, data obtained from other observation fields are added, and the separation functional layer containing a total of more than 10 particles is observed, and the volume is calculated.

[0066] Among the particles that exist independently without contact with other particles, if there are particles with an aspect ratio of 10 or higher, it is preferred from the perspective of the adhesive interface that can easily increase the performance of the particles and thus enhance the matrix constituting the separation functional layer.

[0067] There is no particular limitation on the size of the particles in the separation functional layer, but the length Ls of the shortest portion is preferably 0.3 nm or more and 10 μm or less. When Ls is 0.3 nm or more, processing becomes easier while ensuring sufficient specific surface area. On the other hand, when Ls is 10 μm or less, the specific surface area is large, the adhesion to the substrate is improved, and therefore the strength of the separation membrane is improved. From the above perspective, the Ls of the particles is preferably 0.3 nm or more and 1 μm or less, and more preferably 1 nm or more and 100 nm or less.

[0068] The particle content in the separation functional layer constituting the gas separation membrane of the present invention is not particularly limited, but it is preferred if it is 10% or less in 100% by volume of the separation functional layer, which can sufficiently enhance the matrix. If the particle content is low, the dispersion of particles in the matrix is ​​improved, and thus a separation functional layer with excellent film thickness uniformity can sometimes be obtained. On the other hand, if the content is high, the particle content per unit volume of the separation functional layer increases, and thus a reinforcing effect is often easily exhibited, increasing the strength of the separation functional layer. Considering these aspects, the particle content in the separation functional layer is more preferably 0.3 to 9% by volume, and even more preferably 0.5 to 5% by volume.

[0069] Here, regarding the particle content in the separation functional layer constituting the gas separation membrane of the present invention, the particle content (volume %) in the separation functional layer is defined as the volume ratio of particles in the field of view to the volume of the separation functional layer, based on the three-dimensional data of particles extracted by three-dimensional microscopy of the separation functional layer as previously described.

[0070] The thickness of the separation functional layer constituting the gas separation membrane of the present invention is not particularly limited. A thicker layer provides greater resistance to damage caused by external forces, enabling stable long-term use of the separation membrane, and is therefore preferred. Conversely, a thinner layer reduces fluid permeation resistance and increases throughput per unit area, and is also preferred. Considering these aspects, the thickness of the separation functional layer is preferably in the range of 100 nm to 1,000 μm, more preferably in the range of 200 nm to 10 μm. Here, the thickness of the separation functional layer is defined by measuring the thickness of the thinnest portion constituting the separation functional layer using a microscope or the like, and is calculated as the average thickness obtained by analyzing 10 locations on the cross-section of the gas separation membrane.

[0071] The gas separation membrane of the present invention can be a so-called composite membrane, which has a support body that supports the separation functional layer in addition to the separation functional layer. If it is a composite membrane, the support body that supports the separation functional layer ensures mechanical strength and durability, prevents damage in actual use, and can operate stably for a long time. In addition, even when high pressure is applied, the support body can bear the pressure, thus providing a gas separation membrane that can operate in a high-pressure environment.

[0072] Here, there are no particular restrictions on the material used as the support, as long as it does not impede gas permeation and also functions as a support for the separation layer. Commonly known porous materials can be appropriately selected. Examples of suitable porous materials for the support include materials with independent bubbles originating from island structures, materials with structures composed of multiple interconnected particles, nonwoven fabrics formed by folding fibrous materials and bonding them appropriately as needed, and materials with continuous porous structures formed by the continuity of voids with the material constituting the support. These materials are preferably selected from the perspective of not impeding fluid permeation and fulfilling the function of supporting the separation layer. Among these, materials with continuous porous structures are more preferred because the voids are continuous with the material constituting the support, thus not impeding gas permeation and effectively dispersing the stress exerted on the separation layer by the material constituting the support, resulting in improved pressure resistance of the gas separation membrane.

[0073] The shape of the gas separation membrane of the present invention is not particularly limited and can be any shape such as fibrous or membrane. When the gas separation membrane is fibrous, it has advantages such as achieving a larger membrane area per unit volume compared to a membrane shape. Furthermore, since its resistance to forces applied along the cross-sectional direction is increased, it can also operate under high pressure, enabling highly efficient gas membrane separation, and is therefore preferred.

[0074] When the gas separation membrane of the present invention is fibrous, there are no restrictions on the shape of the fiber cross-section; it can be any shape such as a circular cross-section, a triangular cross-section or other multi-leaf cross-section, a flat cross-section, or a hollow cross-section. In particular, when the cross-section of the gas separation membrane is hollow, i.e., when the shape of the gas separation membrane is hollow fiber, it is preferable to have pressure resistance while controlling the flow of the supplied gas and the separated gas. When the gas separation membrane is hollow fiber, a higher hollow ratio results in lower pressure loss and less obstruction to gas flow; conversely, a lower hollow ratio results in higher pressure resistance, which is also preferable. Considering these aspects, the hollow ratio is preferably in the range of 10% to 90%, more preferably in the range of 20% to 60%. The hollow portion of the hollow fiber can be single or multiple.

[0075] Furthermore, the gas separation membrane assembly of the present invention is in the form of housing the gas separation membrane of the present invention within a housing. The gas separation membrane assembly forms a flow path for controlling the flow of the mixed gas and guiding the gas passing through the gas separation membrane. Additionally, for the purpose of controlling these gas flows, a housing and a sealing material are preferably used. The material of the housing is not particularly limited, but is preferably selected appropriately based on the operating environment such as pressure resistance and heat resistance; examples include metals, resins, carbon, and composites thereof.

[0076] Example

[0077] The present invention will now be described in detail with reference to embodiments and comparative examples, but the present invention is not limited to these embodiments and comparative examples. The evaluation of each embodiment and comparative example was conducted using the following methods.

[0078] (Gas separation membrane module)

[0079] Twenty gas separation membranes, each 10 cm long, are bundled together and housed in an acrylic tube (12 mm inner diameter, 3 mm wall thickness) that serves as the housing. The ends of the bundled fluid separation membranes are then fixed to the inner surface of the housing with an epoxy resin adhesive. At the same time, both ends of the housing are sealed to form a gas separation membrane assembly.

[0080] (Gas separation membrane fracture rate based on pressurization and depressurization tests)

[0081] For each embodiment and comparative example, five gas separation membrane assemblies were prepared, and it was confirmed that no gas separation membrane rupture occurred during manufacturing. Here, the presence or absence of gas separation membrane rupture was evaluated as follows: If a rupture was visually observed in the gas separation membrane through the acrylic tube serving as the housing, it was determined to be ruptured. If no rupture was visually observed, the inflow and outflow ports of the gas to be separated in the gas separation membrane assembly were sealed except for one location. The entire gas separation membrane assembly was then immersed in water with 0.2 MPaG of compressed air supplied to the unsealed inflow and outflow ports of the gas to be separated. If bubbles were observed to form from the opening of the gas separation membrane, it was determined to be ruptured; if no bubbles were observed to form, it was determined to be rupture-free.

[0082] For each gas separation membrane module without breakage, a pressurization and depressurization test was conducted 10 times, consisting of maintaining a 2.0 MPaG compressed air supply to the supply side for 1 minute and then opening to atmospheric pressure. After the pressurization and depressurization test, the gas separation membrane was again checked for breakage, and the proportion of broken modules among the 5 gas separation membrane modules was taken as the breakage rate of the gas separation membrane.

[0083] (Reduction rate of separation coefficient after pressure and depressurization test)

[0084] The gas permeation velocity of the gas separation membrane module before the pressure and depressurization test was measured, and the separation coefficient was calculated based on the permeation velocity ratio of CO2 to CH4 (CO2 / CH4). Next, a pressure and depressurization test was conducted. One gas separation membrane module that did not break during the pressure and depressurization test was selected, and the gas permeation velocity was measured again, and the separation coefficient was calculated. The reduction rate of the separation coefficient before and after the pressure and depressurization test was calculated as 1 - (separation coefficient after pressure and depressurization test / separation coefficient before pressure and depressurization test). A reduction rate less than 0.1 was classified as "Excellent," a reduction rate greater than 0.1 but less than 0.3 was classified as "Good," and a reduction rate greater than 0.3 was classified as "Pass."

[0085] Regarding the gas permeation velocity, the pressure change on the permeation side of CO2 and CH4 per unit time was measured using an external pressure method according to the pressure sensor method of JIS K 7126-1 (2006) at a measurement temperature of 25°C. Here, the pressure difference between the supply side and the permeation side was set to 0.11 MPa (82.5 cmHg). Next, the permeation velocity Q of the permeated gas was calculated using the following formula, and the separation coefficient α was calculated as the ratio of the permeation velocities of each component gas. It should be noted that STP refers to standard conditions. Furthermore, the membrane area was calculated from the outer diameter and length of the fluid separation membrane in the region facilitating gas permeation.

[0086] Permeability Q = [Gas permeation flow rate (cm)] 3·STP)] / [membrane area (cm) 2 [( ) × Time (s) × Pressure Difference (cmHg)]

[0087] Calculate the ratio of the gas permeation velocities Q of CO2 and CH4, and use (CO2 permeation velocity) / (CH4 permeation velocity) as the separation coefficient α.

[0088] [Preparation Example 1] Preparation of 10.0 wt% aromatic polyimide (PI) solution and slurry

[0089] Aromatic polyimide (hereinafter referred to as aromatic PI) "Matrimid (registered trademark)" 5218 was dissolved in N-methylpyrrolidone (NMP) to prepare a 10.0% by weight aromatic polyimide solution (hereinafter referred to as aromatic PI solution).

[0090] Here, "Matrimid (registered trademark)" 5218 is the condensation product of 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride and 5(6)-amino-1-(4'-aminophenyl)-1,3,3'-trimethylindene.

[0091] Carbon nanotube powder (CNano FT7000 series) was added to the prepared aromatic PI solution to reach 0.30% by volume, and then a dispersant was added. The mixture was stirred and dispersed using a rotation-revolution mixer to prepare a slurry.

[0092] [Preparation Example 2] Preparation of 10.0 wt% polyacrylonitrile (PAN) solution and slurry

[0093] Polyacrylonitrile (PAN) (MW 150,000) was dissolved in dimethyl sulfoxide (DMSO) to prepare a 10.0% by weight PAN solution.

[0094] Carbon nanotube powder (CNano FT7000 series) was added to the prepared PAN solution to reach 0.35% by volume, and then a dispersant was added. The mixture was stirred and dispersed using a rotation-revolution mixer to prepare a slurry.

[0095] [Preparation Example 3] Preparation of 10.0 wt% cellulose acetate solution and slurry

[0096] Cellulose acetate (55% acetylation) was dissolved in N-methylpyrrolidone (NMP) to prepare a 10.0% by weight cellulose acetate solution.

[0097] Short-cut polyethylene terephthalate (PET) fibers were added to the prepared cellulose acetate solution to reach 0.40% by volume, and then a dispersant was added. The mixture was stirred and dispersed using a rotation-revolution mixer to produce a slurry.

[0098] [Preparation Example 4] Preparation of 8.0 wt% Aromatic PI Solution and Slurry

[0099] Aromatic PI "Matrimid (registered trademark)" 5218 was dissolved in N-methylpyrrolidone (NMP) to prepare an 8.0% by weight aromatic PI solution.

[0100] Carbon nanotube powder (CNano FT7000 series) was added to the prepared aromatic PI solution to reach 0.03% by volume, and then a dispersant was added. The mixture was stirred and dispersed using a rotation-revolution mixer to prepare a slurry.

[0101] [Example 1]

[0102] 10 parts by weight of polyacrylonitrile (PAN) (150,000 MW), 10 parts by weight of polyvinylpyrrolidone (PVP) (40,000 MW) and 80 parts by weight of dimethyl sulfoxide (DMSO) were mixed and stirred at 100°C to prepare a spinning solution.

[0103] After cooling the obtained spinning solution to 25°C, a concentric three-layer spinneret is used to discharge an 80% by weight aqueous solution of DMSO from the inner tube, the above spinning solution from the middle tube, and a 90% by weight aqueous solution of DMSO from the outer tube. The solution is then introduced into a coagulation bath and wound onto a roller to obtain the precursor fiber. The precursor fiber is then dried using a circulating hot air dryer to produce a hollow fiber-like porous carbon support precursor.

[0104] Next, the porous carbon support precursor is passed through an electric furnace and heated in an air atmosphere to undergo a non-melting treatment. Then, the non-melting filament is carbonized to produce a hollow fibrous porous carbon support. Both the outer and inner surfaces (the surfaces of the hollow portions) of the produced porous carbon support are perforated. Furthermore, observation of the hollow fiber cross-section reveals a continuous porous structure.

[0105] A porous carbon support was immersed in the slurry prepared in Preparation Example 1, and then lifted at a speed of 10 mm / min using a dip-coating method. The solvent was then removed by immersion in water, and the slurry was dried using a circulating hot air dryer. This yielded a coated filament with aromatic PI containing carbon nanotubes laminated on the surface of the porous carbon support. The coated filament was further carbonized at 700°C to produce a gas separation membrane with a carbon film based on aromatic PI containing carbon nanotubes laminated on the surface of the porous carbon support.

[0106] At this point, based on the three-dimensional data extracted by three-dimensional microscopic imaging of the separation functional layer of the gas separation membrane, the particle content is 3.1% by volume, the average aspect ratio of the particles is 1,725, the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is +0.76, the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is 0.76, the volume proportion of particles with an aspect ratio of 10 or higher is 98%, and the volume proportion of particles that exist independently without contact with other particles is 43% by volume. Here, the average aspect ratio is calculated by arbitrarily selecting 10 particles that exist independently without contact with other particles, calculating the aspect ratio of each, and averaging the average. In addition, according to the elemental analysis performed using the energy-dispersive X-ray spectrophotometer attached to the transmission electron microscope, the carbon element ratio X of the matrix is ​​90.3%, the carbon element ratio Y of the particles is 98.6%, and (|XY| / X)×100 is 9.2%.

[0107] The gas separation membrane fracture rate was 0 based on the pressure reduction test, and the reduction rate of the separation coefficient after the pressure reduction test was "excellent". The evaluation results are shown in Table 1.

[0108]

[0109] [Example 2]

[0110] In the preparation of the slurry in Example 1, the slurry was prepared in such a way that the added carbon nanotube powder reached 0.02% by volume. Otherwise, the gas separation membrane module was fabricated using the same method as in Example 1.

[0111] At this point, based on the three-dimensional data extracted from the separated functional layers by imaging with a three-dimensional microscope, the particle content is 0.2% by volume, the average aspect ratio of the particles is 1,648, the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is +0.78, the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is 0.78, the volume proportion of particles with an aspect ratio of 10 or higher is 97%, and the volume proportion of particles that exist independently without contact with other particles is 35% by volume. Furthermore, based on elemental analysis performed using an energy-dispersive X-ray spectrophotometer attached to a transmission electron microscope, the carbon element ratio X of the matrix is ​​90.3%, the carbon element ratio Y of the particles is 98.5%, and (|XY| / X)×100 is 9.1%.

[0112] The breakage rate of the gas separation membrane based on the pressure reduction test was 0.2%, and the reduction rate of the separation coefficient after the pressure reduction test was "good". The evaluation results are shown in Table 1.

[0113] [Example 3]

[0114] The gas separation membrane module was fabricated using the same method as in Example 1, except that the pulling speed in the dip coating method was changed to 5 mm / min and the carbonization temperature of the coating filament was changed to 600°C.

[0115] At this point, based on the three-dimensional data extracted from the separated functional layers obtained by imaging with a three-dimensional microscope, the particle content is 3.7% by volume, the average aspect ratio of the particles is 1,773, the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is +0.57, the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is 0.57, the volume proportion of particles with an aspect ratio of 10 or higher is 99%, and the volume proportion of particles that exist independently without contact with other particles is 39% by volume. Furthermore, based on elemental analysis performed using an energy-dispersive X-ray spectrophotometer attached to a transmission electron microscope, the carbon element ratio X of the matrix is ​​86.4%, the carbon element ratio Y of the particles is 98.7%, and (|XY| / X)×100 is 14.2%.

[0116] The breakage rate of the gas separation membrane based on the pressure reduction test was 0.0, and the reduction rate of the separation coefficient after the pressure reduction test was "good". The evaluation results are shown in Table 1.

[0117] [Example 4]

[0118] As an alternative to Preparation Example 1, the slurry prepared in Preparation Example 2 was used, but the pulling speed in the dip coating method was changed to 5 mm / min, and the carbonization temperature of the coating filaments was changed to 600°C. Otherwise, the gas separation membrane module was fabricated using the same method as in Example 1.

[0119] At this point, based on the three-dimensional data extracted from the separated functional layers obtained by imaging with a three-dimensional microscope, the particle content is 3.4% by volume, the average aspect ratio of the particles is 1,680, the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is +0.54, the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is 0.54, the volume proportion of particles with an aspect ratio of 10 or higher is 98%, and the volume proportion of particles that exist independently without contact with other particles is 36% by volume. Furthermore, based on elemental analysis performed using an energy-dispersive X-ray spectrophotometer attached to a transmission electron microscope, the carbon element ratio X of the matrix is ​​78.2%, the carbon element ratio Y of the particles is 98.5%, and (|XY| / X)×100 is 26.0%.

[0120] The breakage rate of the gas separation membrane based on the pressure reduction test was 0.2%, and the reduction rate of the separation coefficient after the pressure reduction test was "good". The evaluation results are shown in Table 1.

[0121] [Example 5]

[0122] As an alternative to Preparation Example 1, the slurry prepared in Preparation Example 3 was used, the pulling speed in the dip coating method was changed to 5 mm / min, and the gas separation membrane was directly prepared without carbonization treatment of the coated filaments. Otherwise, the gas separation membrane assembly was prepared using the same method as in Example 1.

[0123] At this point, based on the three-dimensional data extracted from the separated functional layers obtained by imaging with a three-dimensional microscope, the particle content is 4.2% by volume, the average aspect ratio of the particles is 1,592, the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is +0.55, the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is 0.55, the volume proportion of particles with an aspect ratio of 10 or higher is 97%, and the volume proportion of particles that exist independently without contact with other particles is 31% by volume. Furthermore, based on elemental analysis performed using an energy-dispersive X-ray spectrophotometer attached to a transmission electron microscope, the carbon element ratio X of the matrix is ​​61.4%, the carbon element ratio Y of the particles is 71.6%, and (|XY| / X)×100 is 16.6%.

[0124] The breakage rate of the gas separation membrane based on the pressure reduction test was 0.2%, and the reduction rate of the separation coefficient after the pressure reduction test was "qualified". The evaluation results are shown in Table 1.

[0125] [Example 6]

[0126] In the preparation of the slurry in Example 1, carbon black powder was added instead of carbon nanotube powder. Otherwise, the gas separation membrane assembly was prepared using the same method as in Example 1.

[0127] At this point, based on the three-dimensional data extracted from the separated functional layers by imaging with a three-dimensional microscope, the particle content is 2.9% by volume, the average aspect ratio of the particles is 6, the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is +0.08, the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is 0.08, the volume proportion of particles with an aspect ratio of 10 or higher is 3%, and the volume proportion of particles that exist independently without contact with other particles is 35% by volume. Furthermore, based on elemental analysis using an energy-dispersive X-ray spectrophotometer attached to a transmission electron microscope, the carbon element ratio X of the matrix is ​​90.3%, the carbon element ratio Y of the particles is 99.1%, and (|XY| / X)×100 is 9.7%.

[0128] The breakage rate of the gas separation membrane based on the pressure reduction test was 0.6%, and the reduction rate of the separation coefficient after the pressure reduction test was "qualified". The evaluation results are shown in Table 1.

[0129] [Example 7]

[0130] In the preparation of the slurry in Example 1, a powder made by mixing carbon nanotubes and carbon black in a weight ratio of 2:1 was added instead of carbon nanotube powder. Otherwise, the gas separation membrane assembly was prepared using the same method as in Example 1.

[0131] At this point, based on the three-dimensional data extracted from the separated functional layers obtained by imaging with a three-dimensional microscope, the particle content is 3.4% by volume, the average aspect ratio of the particles is 1,173, the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is +0.48, the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is 0.48, the volume proportion of particles with an aspect ratio of 10 or higher is 73%, and the volume proportion of particles that exist independently without contact with other particles is 30% by volume. Furthermore, based on elemental analysis performed using an energy-dispersive X-ray spectrophotometer attached to a transmission electron microscope, the carbon element ratio X of the matrix is ​​90.3%, the carbon element ratio Y of the particles is 98.7%, and (|XY| / X)×100 is 9.3%.

[0132] The breakage rate of the gas separation membrane based on the pressure reduction test was 0.2%, and the reduction rate of the separation coefficient after the pressure reduction test was "good". The evaluation results are shown in Table 2.

[0133]

[0134] [Example 8]

[0135] In the preparation of the slurry in Example 1, a powder made by mixing carbon nanotubes and carbon black in a weight ratio of 1:2 was added instead of carbon nanotube powder. In addition, a homogenizer was used instead of a rotation-revolution mixer for stirring and dispersing during the preparation of the slurry. Otherwise, the gas separation membrane assembly was made using the same method as in Example 1.

[0136] At this point, based on the three-dimensional data extracted from the separated functional layers by imaging with a three-dimensional microscope, the particle content is 3.6% by volume, the average aspect ratio of the particles is 655, the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is +0.08, the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is 0.08, the volume proportion of particles with an aspect ratio of 10 or higher is 3%, and the volume proportion of particles that exist independently without contact with other particles is 35% by volume. Furthermore, based on elemental analysis using an energy-dispersive X-ray spectrophotometer attached to a transmission electron microscope, the carbon element ratio X of the matrix is ​​90.3%, the carbon element ratio Y of the particles is 98.7%, and (|XY| / X)×100 is 9.3%.

[0137] The breakage rate of the gas separation membrane based on the pressure reduction test was 0.4, and the reduction rate of the separation coefficient after the pressure reduction test was "good". The evaluation results are shown in Table 2.

[0138] [Example 9]

[0139] As an alternative to Preparation Example 1, the slurry prepared in Preparation Example 4 was used, and the pulling speed in the dip coating method was changed to 2 mm / min. Otherwise, the gas separation membrane module was fabricated using the same method as in Example 1.

[0140] At this point, based on the three-dimensional data extracted from the separated functional layers obtained by imaging with a three-dimensional microscope, the particle content is 0.4% by volume, the average aspect ratio of the particles is 1,581, the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is +0.18, the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is 0.18, the volume proportion of particles with an aspect ratio of 10 or higher is 98%, and the volume proportion of particles that exist independently without contact with other particles is 39% by volume. Furthermore, based on elemental analysis performed using an energy-dispersive X-ray spectrophotometer attached to a transmission electron microscope, the carbon element ratio X of the matrix is ​​90.3%, the carbon element ratio Y of the particles is 98.5%, and (|XY| / X)×100 is 9.1%.

[0141] The breakage rate of the gas separation membrane based on the pressure reduction test was 0.4, and the reduction rate of the separation coefficient after the pressure reduction test was "excellent". The evaluation results are shown in Table 2.

[0142] [Example 10]

[0143] In the preparation of the slurry in Example 1, the weight of the added carbon nanotube powder was increased, and a homogenizer was used instead of a rotation-revolution mixer during the stirring and dispersion of the slurry. Otherwise, the gas separation membrane assembly was prepared using the same method as in Example 1.

[0144] At this point, based on the three-dimensional data extracted from the separated functional layers obtained by imaging with a three-dimensional microscope, the particle content is 8.3% by volume, the average aspect ratio of the particles is 1,624, the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is +0.54, the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is 0.54, the volume proportion of particles with an aspect ratio of 10 or higher is 99%, and the volume proportion of particles that exist independently without contact with other particles is 0.7% by volume. Furthermore, based on elemental analysis performed using an energy-dispersive X-ray spectrophotometer attached to a transmission electron microscope, the carbon element ratio X of the matrix is ​​90.3%, the carbon element ratio Y of the particles is 98.6%, and (|XY| / X)×100 is 9.2%.

[0145] The breakage rate of the gas separation membrane based on the pressure reduction test was 0.4, and the reduction rate of the separation coefficient after the pressure reduction test was "good". The evaluation results are shown in Table 2.

[0146] [Example 11]

[0147] In the preparation of the slurry in Example 1, graphene powder was added to replace carbon nanotube powder. Otherwise, the gas separation membrane assembly was fabricated using the same method as in Example 1.

[0148] At this point, based on the three-dimensional data extracted from the separated functional layers by imaging with a three-dimensional microscope, the particle content is 3.2% by volume, the average aspect ratio of the particles is 592, the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is +0.62, the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or higher relative to the reference axis is 0.62, the volume proportion of particles with an aspect ratio of 10 or higher is 97%, and the volume proportion of particles that exist independently without contact with other particles is 38% by volume. Furthermore, based on elemental analysis using an energy-dispersive X-ray spectrophotometer attached to a transmission electron microscope, the carbon element ratio X of the matrix is ​​90.3%, the carbon element ratio Y of the particles is 98.1%, and (|XY| / X)×100 is 8.6%.

[0149] The breakage rate of the gas separation membrane based on the pressure reduction test was 0.0, and the reduction rate of the separation coefficient after the pressure reduction test was "good". The evaluation results are shown in Table 2.

[0150] [Comparative Example 1]

[0151] In the solution of Preparation Example 1, no carbon nanotube powder was added, but the gas separation membrane assembly was fabricated using the same method as in Example 1.

[0152] At this point, the three-dimensional data extracted by imaging the separated functional layers using a three-dimensional microscope does not contain particles.

[0153] The fracture rate of the gas separation membrane based on the pressure and depressurization test was 1.0. All five gas separation membrane modules fabricated failed to separate gas due to the presence of membrane fracture, making it impossible to evaluate the separation coefficient after the pressure and depressurization test. The evaluation results are shown in Table 2.

[0154] Industrial availability

[0155] The gas separation membrane module of the present invention can suppress the breakage of the gas separation membrane during operation without impairing the gas separation function. The application of the module of the present invention is not particularly limited. For example, it can be preferably used in systems for separating / storing carbon dioxide from exhaust gas from power plants, blast furnaces, etc., removing sulfur components from fuel gas from coal gasification combined power generation, purifying biogas and natural gas, purifying hydrogen from organic hydrides, etc.

Claims

1. A gas separation membrane, comprising at least a portion of a gas separation membrane having a separation functional layer, wherein the gas separation membrane is fibrous in shape, and the separation functional layer comprises a matrix and particles. The carbon content of the matrix is ​​70 atomic% or more and 100 atomic% or less. When the carbon content of the matrix is ​​set as X and the carbon content of the particles is set as Y, (|XY| / X)×100 is less than 30%. The units of X and Y are both atomic%. The matrix is ​​a carbide of a polymer compound. The particles are selected from one or more of the group consisting of carbon black, graphite, expanded graphite, carbon nanotubes, carbon nanoribbons, carbon nanotubes, graphene, graphene oxide and fullerene.

2. The gas separation membrane according to claim 1, wherein at least a portion of the particles comprises particles with an aspect ratio of 10 or higher.

3. The gas separation membrane according to claim 2, wherein the absolute value of the orientation coefficient F of the particles with an aspect ratio of 10 or more relative to the reference axis is 0.1 or more and 1.0 or less, with the fiber axis as the reference axis.

4. The gas separation membrane according to any one of claims 1 to 3, wherein the particles are fibrous.

5. The gas separation membrane according to any one of claims 1 to 3, wherein the particles are plate-shaped.

6. The gas separation membrane according to any one of claims 1 to 3, wherein the particle content in the separation functional layer is less than 10% by volume.

7. The gas separation membrane according to claim 2 or 3, wherein the orientation coefficient F of the particles with an aspect ratio of 10 or more relative to the reference axis is +0.1 or more and +1.0 or less, with the fiber axis as the reference axis.

8. The gas separation membrane according to any one of claims 1 to 3, wherein the volume percentage of particles that exist independently without contact with other particles in the total volume of all particles is 1% or more by volume.

9. A gas separation membrane assembly having a configuration in which the gas separation membrane of any one of claims 1 to 8 is housed within a housing.

Images