Gas storage and release material

Abstract

To provide a novel gas storage and release material that exhibits excellent storage and release characteristics for various gases, particularly hydrogen, is low in density and weight, allows pressurization, depressurization, heating and cooling operations during gas storage and release to be performed under mild conditions, can be easily synthesized by a simple method from inexpensive raw materials thereby having high versatility, exhibits excellent reproducibility of gas storage and release, has excellent safety during hydrogen storage, and has high stability and durability.SOLUTION: A gas storage and release material contains an organometallic framework that includes, as constituent elements, an aromatic hydrocarbon compound ligand, a heterocyclic compound ligand, and a metal ion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas storage and release material capable of storing and releasing various gases. [Background technology]

[0002] In order to solve environmental problems such as global warming, efforts are underway to develop clean energy sources to replace fossil fuels. Among these, hydrogen is considered one of the most promising energy sources because it is a diverse and abundant resource, has good combustion performance characteristics and calorific value, and has a low environmental impact as it does not emit carbon dioxide when generating electricity using fuel cells or internal combustion engines.

[0003] To use hydrogen as an energy source, it is necessary to build a hydrogen storage and release system that can flexibly respond to fluctuating demand. For example, it is necessary to build a hydrogen supply chain that transports hydrogen obtained by electrolyzing water using surplus electricity to utilization facilities. However, because hydrogen is a gas at room temperature and pressure, it is currently stored as high-pressure hydrogen gas in containers such as tanks and cylinders. Therefore, to use hydrogen until now, high-pressure hydrogen or liquefied hydrogen had to be transported by tank truck. Furthermore, hydrogen storage facilities required the development of large-scale infrastructure such as high-pressure hydrogen gas tanks.

[0004] When using hydrogen on-site instead of using a container-based high-pressure hydrogen gas storage and release system, hydrogen storage and release systems using hydrogen storage and release materials are being considered, which can safely store and release large quantities at low pressures through the interaction between hydrogen and materials. For example, demonstration experiments are being conducted in various locations to build a hydrogen supply chain in which hydrogen obtained by electrolyzing water using surplus electricity from renewable energy sources such as solar power and wind power is stored in gas storage and release materials contained in tanks, and the tanks are then loaded onto trucks and transported to hydrogen utilization facilities, and the use of hydrogen storage and release materials is being considered for this purpose.

[0005] Hydrogen storage materials are materials that can selectively and reversibly store and release hydrogen, and hydrogen storage alloys and functional carbon materials (graphene oxide) are considered promising. However, these hydrogen storage and release materials have problems with their hydrogen storage capacity. There is also room for improvement in terms of performance degradation due to impurity gases and increased costs associated with using rare metals and high-purity metals as raw materials. Furthermore, hydrogen storage alloys and functional carbon materials (graphene oxide) are difficult to process, requiring cooling for hydrogen storage and heating for hydrogen release. Furthermore, the high density of hydrogen storage alloys results in a large mass for the hydrogen storage material, posing a problem in terms of handling.

[0006] Patents have been filed for metal-organic frameworks. Patent Document 1 (JP 2017-527500 A) describes a specific surface area of ​​900 m 2 / g to 2500m 2 The document describes a method for preserving the freshness of fruit by enclosing an adsorbent material containing a metal-organic framework (MOF) with a carboxyl group of about 1 / g in a container and placing the container in which fruit is loaded, thereby absorbing gases that promote fruit ripening. However, the adsorbent material containing a metal-organic framework (MOF) described in Patent Document 1 has a property that its structure is destroyed by moisture, and therefore there is a problem in that the gas adsorption effect decreases in an atmosphere containing water vapor. Patent Document 2 (JP 2023-512655 A) describes that by supporting a surfactant and an enzyme on a metal-organic framework (MOF), the duration of enzyme activity can be maintained for a long time. However, the metal-organic framework (MOF) used is suitable for adsorbing small compounds but is not suitable for adsorbing macromolecules such as enzymes, which poses a problem in that the duration of enzyme activity is not much different from when the enzyme is used alone. Patent Document 3 (JP Patent Publication No. 2023-519685) describes the adsorption and removal of nitrogen dioxide (NO2), an impurity contained in an air stream, using a metal-organic framework (MOF) consisting of a nitrogen-containing compound, a nitrogen-free organic ligand, and a metal ion. However, this MOF is sensitive to heat, and there is a problem in that the MOF decomposes at temperatures above room temperature, causing it to lose its intended function. Patent Document 4 (Japanese Patent No. 7145921) describes the use of a metal-organic framework (MOF) material formed from organic ligands and metal ions to adsorb semiconductor gases in semiconductor gas-containing effluent. However, this metal-organic framework (MOF) material has the problem of being decomposed by light such as ultraviolet light, resulting in a decrease in adsorption performance. Patent Document 5 (Japanese Patent No. 5074035) discloses that gases such as methane, carbon dioxide, and propene are adsorbed into a porous polymer structure. However, the porous polymer MOF-5 disclosed in Patent Document 5 has a property that its structure is destroyed by moisture, which causes a problem of a decrease in the gas adsorption effect. Patent Document 6 (JP 2022-022982 A) discloses an organic structure composed of a mixed organic ligand of 1,3,5-benzenetricarboxylic acid and 2-methylimidazole and Zn(II) ions. This organic structure is said to have a high specific surface area and a high hydrogen adsorption capacity at 0 to 25°C and a pressure of 100 atmospheres. However, the adsorption state is unstable due to the molecular motion of hydrogen, and the adsorption rate decreases shortly after adsorption. Patent Document 7 (JP 2012-514530 A) discloses that a metal-organic structure using fullerene, a carbon material, has a high hydrogen storage rate. However, fullerene has problems such as being easily oxidized and decomposed, causing rapid deterioration, and is too costly. Patent Document 8 (JP 2008-535657 A) discloses that a metal-organic framework formed from several types of organic ligands and metal ions exhibits a high hydrogen storage rate. However, the purification of the organic ligands is difficult, and the impurities contained therein cause side reactions during the synthesis of the metal-organic framework, resulting in poor reproducibility of hydrogen storage. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2017-527500 [Patent Document 2] Special Publication No. 2023-512655 [Patent Document 3] Special Publication No. 2023-519685 [Patent Document 4] Patent No. 7145921 [Patent Document 5] Patent No. 5074035 [Patent Document 6] Japanese Patent Publication No. 2022-022982 [Patent Document 7] Special Publication No. 2012-514530 [Patent Document 8] Special Publication No. 2008-535657 Summary of the Invention [Problem to be solved by the invention]

[0008] The problem to be solved by the present invention is to provide a novel gas storage / release material that has excellent storage / release properties for various gases, particularly hydrogen, is low in density and lightweight, requires mild conditions for pressurization, decompression, heating, and cooling operations when storing and releasing gas, can be easily synthesized from inexpensive raw materials using a simple method, is highly versatile, has excellent reproducibility in gas storage / release, is excellent in safety when storing hydrogen, and is highly stable and durable. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that a gas storage / release material containing a specific organometallic framework has excellent storage / release properties for various gases, particularly hydrogen, and that the above-mentioned problems can be solved by using this material.

[0010] That is, the present invention that solves the above problems mainly includes the following configurations. [Section 1] A gas storage and release material containing a metal-organic framework including, as components, an aromatic hydrocarbon compound ligand, a heterocyclic compound ligand, and a metal ion. [Section 2] Item 2. The gas storage and release material according to item 1, wherein the aromatic hydrocarbon compound ligand is an aromatic hydrocarbon compound having an aromatic hydrocarbon ring in the molecule. [Section 3] Item 3. The gas storage and release material according to Item 1 or 2, wherein the heterocyclic compound ligand is a heterocyclic compound having a heterocycle containing one or more of nitrogen, oxygen, and sulfur as a heteroatom in the molecule. [Section 4] 4. The gas storage and release material according to any one of items 1 to 3, wherein the metal ions are ions of metals belonging to periods 2 to 6 of the periodic table. [Section 5] The metal-organic framework has structural formula (I) and / or (II); [ka] In structural formulas (I) and (II), Ar represents an aromatic hydrocarbon ring; L represents an aromatic hydrocarbon ring; 1 is a coordinating functional group, L 2 is a coordinating functional group, Ht is a heterocycle, and M is a metal ion. Item 5. The gas storage and release material according to any one of items 1 to 4, having a structure represented by the following formula: [Section 6] Item 6. The gas storage / release material according to any one of items 1 to 5, wherein the heterocyclic ring in the heterocyclic compound ligand is at least one selected from the group consisting of an imidazole ring, a furan ring, a pyrrole ring, a thiophene ring, an oxazole ring, a thiazole ring, a pyrazole ring, a γ-pyran ring, a pyridine ring, a piperidine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pteridine ring. [Section 7] The metal ion is Fe 2+ , Fe 3+ , Zn 2+ , Pb 2+ , Ni 2+ , Co 3+ , Co 2+ , Mn 2+ , Cu 2+ , Li + , Na + , Ca 2+ , Mg 2+ , Ag + and Al 3+ Item 7. The gas storage and release material according to any one of items 1 to 6, which is one or more selected from the group consisting of: [Section 8] Item 8. The gas storage and release material according to any one of items 1 to 7, wherein the aromatic hydrocarbon compound ligand comprises 5-methoxyisophthalic acid. [Section 9] Item 9. The gas storage and release material according to any one of items 1 to 8, wherein the heterocyclic compound ligand comprises 1H-imidazole-4,5-dicarboxylic acid. [Section 10] Item 10. The gas storage and release material according to any one of items 1 to 9, wherein the gas stored in the gas storage and release material is one or more selected from the group consisting of hydrogen, carbon dioxide, nitrogen, ammonia, rare gases, and hydrocarbon gases. [Section 11] Item 11. The gas storage and / or release material according to any one of items 1 to 10, wherein the gas is stored and / or released by a method comprising one or more means selected from the group consisting of pressurization, depressurization, temperature increase, temperature decrease, application of electric potential, and irradiation with an energy wave. [Section 12] Item 12. The gas storage and release material according to any one of items 1 to 11, wherein the gas storage and release material is in the form of particles, fibers, a film, a nonwoven fabric, a woven fabric, a porous body, or a molded body. [Effects of the Invention]

[0011] The present invention provides a novel gas storage / release material that has excellent storage / release properties for various gases, particularly hydrogen, is low in density and lightweight, requires mild conditions for pressurization, decompression, heating, and cooling operations when storing and releasing gas, can be easily synthesized from inexpensive raw materials by a simple method, has excellent reproducibility in gas storage / release, is excellent in safety when storing hydrogen, and is highly stable and durable.

[0012] The gas storage and release material of the present invention requires mild conditions for the pressurization, depressurization, heating, and cooling operations when storing and releasing gas, making it possible to eliminate or reduce the size of peripheral equipment that performs pressurization, depressurization, heating, cooling, etc., and also makes it easy to control the storage and release of gas, and further makes it possible to safely store hydrogen inside buildings.

[0013] The gas storage / release material containing the metal-organic framework of the present invention is lighter than a hydrogen storage alloy and therefore has excellent handleability, and various transportation equipment can be used, enabling increased transportation efficiency and reduced fuel costs during transportation. Furthermore, the gas storage / release material containing the metal-organic framework of the present invention requires mild conditions for pressurization, decompression, heating, and cooling during hydrogen storage and release. Furthermore, the gas storage / release material containing the metal-organic framework of the present invention can be easily synthesized by a simple method using commercially available, inexpensive raw material compounds, making it inexpensive and highly versatile. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a diagram showing the hydrogen storage properties of a gas storage / release material of the present invention according to Example 1 and a functional carbon material (graphene oxide) according to Comparative Example 1. [Figure 2]1 is a SEM (scanning electron microscope) photograph of the surface of the gas storage and release material of the present invention according to Example 1. [Figure 3] 2 is a GPC chart showing the results of gel permeation chromatography (GPC) measurement of the gas storage and release material of the present invention according to Example 1. [Figure 4] 2 is a DSC chart showing the results of differential scanning calorimetry (DSC analysis) of the gas storage and release material of the present invention according to Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0015] The gas storage and release material of the present invention contains an organometallic structure including, as components, an aromatic hydrocarbon compound ligand, a heterocyclic compound ligand, and a metal ion. The gas storage and release material of the present invention will be described below.

[0016] [Organometallic structure] The organometallic framework contained in the gas storage and release material of the present invention contains, as constituent elements, an aromatic hydrocarbon compound ligand, a heterocyclic compound ligand, and a metal ion. The metal-organic framework may have the structural formula (I) and / or (II); [ka] In structural formulas (I) and (II), Ar represents an aromatic hydrocarbon ring; L represents an aromatic hydrocarbon ring; 1 is a coordinating functional group, L 2 is a coordinating functional group, Ht is a heterocycle, and M is a metal ion. It is preferable that the compound has a structure represented by the following formula:

[0017] <Aromatic hydrocarbon compound ligand> The aromatic hydrocarbon compound ligand, which is a component of the organometallic framework, is a compound having at least an aromatic hydrocarbon ring and a coordinating functional group. When the aromatic hydrocarbon compound ligand has two or more aromatic hydrocarbon rings or an alicyclic ring, it may have a linking group connecting the rings. In the present invention, the aromatic hydrocarbon compound ligand is a compound that does not have a heterocycle.

[0018] The aromatic hydrocarbon ring contained in the aromatic hydrocarbon compound ligand may be one or more selected from the group consisting of aromatic monocyclic hydrocarbon rings such as a benzene ring; and aromatic fused polycyclic hydrocarbon rings such as a naphthalene ring, an anthracene ring, a fluorene ring, and a pyrene ring. The number of aromatic hydrocarbon rings in the aromatic hydrocarbon compound ligand is not particularly limited, and is, for example, 1 or more and 4 or less. In the present invention, the aromatic hydrocarbon compound ligand preferably has 1 to 4 benzene rings, more preferably 1 benzene ring, from the viewpoint of efficiently forming a hydrogen-containing space.

[0019] The alicyclic ring that the aromatic hydrocarbon compound ligand may have is not particularly limited as long as it is a ring composed only of carbon and is not an aromatic ring. For example, monocyclic cycloalkanes such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cycloundecane, and cyclododecane; cycloalkenes such as cyclopropene, cyclobutene, cyclopropene, cyclohexene, cycloheptene, and cyclooctene; polycyclic alkanes such as bicycloundecane and decahydronaphthalene (decalin); and bicyclic alkenes such as norbornene and norbornadiene; and the like.

[0020] When the aromatic hydrocarbon compound ligand has two or more aromatic hydrocarbon rings or an alicyclic ring, it may have a linking group that links the rings. Examples of the linking group include one or more selected from the group consisting of an alkylene group, an ether group, a ketone group, a sulfide group (-S-), a sulfonyl group (-SO2-), an imino group (-NH- group), an azo group (-N=N-), an amide group, and a group formed by combining two or more of these. Preferably, the linking group is one or more selected from the group consisting of an alkylene group, an ether group, an alkylene ether group, a sulfide group, an imino group, an alkyleneimino group, and the like having 1 to 6 carbon atoms, and more preferably an alkylene group having 1 to 3 carbon atoms.

[0021] The coordinating functional group of the aromatic hydrocarbon compound ligand is not particularly limited as long as it is a functional group capable of coordinating to a metal ion, and examples thereof include one or more selected from the group consisting of a carboxyl group (-COOH), a sulfonic acid group (-SO3H), a primary amino group (-NH2), a hydroxyl group (-OH), a thiol group (-SH), and a phosphate group (-PO3H2).

[0022] In the present invention, the aromatic hydrocarbon compound ligand may be a commercially available product or may be synthesized. Examples of the aromatic hydrocarbon compound ligand include the following compounds (a1) to (a19), (b1) to (b158), and (c1) to (c17).

[0023] [ka]

[0024] [ka]

[0025] [ka]

[0026] In the present invention, the aromatic hydrocarbon compound ligand is preferably, for example, one or more compounds selected from the group consisting of (a1), (a2), (a4), (a7), (a12), (a15), (a17), (a18), (b2), (b4), (c4), (c9), and (c14).

[0027] The content of the aromatic hydrocarbon compound ligand, which is a component of the metal-organic framework, is, for example, 1 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, and can be, for example, 70 mol% or less, preferably 60 mol% or less, relative to the total amount of the metal-organic framework. If it is less than 1 mol% or exceeds 70 mol%, the gas-encapsulating space in the metal-organic framework may not be formed or may shrink, which may result in a deterioration in the gas storage / release properties.

[0028] <Heterocyclic compound ligand> The heterocyclic compound ligand, which is a component of the organometallic framework, is a compound having at least a heterocycle and optionally having a coordinating functional group. When the heterocyclic compound ligand has two or more heterocycles or an alicycle, it may have a linking group connecting the rings. In the present invention, the heterocyclic compound ligand is a compound that does not have an aromatic hydrocarbon ring.

[0029] The heterocycle in the heterocyclic compound ligand is not particularly limited as long as it has one or more heteroatoms other than carbon within the ring. The ring is preferably a 3- to 9-membered ring, and these rings may be fused together. Examples of heteroatoms within the heterocycle include one or more atoms selected from the group consisting of nitrogen, oxygen, sulfur, phosphorus, boron, silicon, antimony, arsenic, bismuth, selenium, tellurium, tin, germanium, and the like. Preferably, the heterocycle is one or more atoms selected from the group consisting of nitrogen, oxygen, sulfur, phosphorus, boron, and silicon, and more preferably, one or more atoms selected from the group consisting of nitrogen, oxygen, and sulfur.

[0030] Examples of the heterocyclic ring in the heterocyclic compound ligand include one or more selected from the group consisting of a pyrrole ring, a furan ring, a thiophene ring, a phosphole ring, a borole ring, a silole ring, a stibole ring, an arsole ring, a bismol ring, a selenophene ring, a tellurophene ring, a stanol ring, an imidazole ring, a pyrazole ring, an oxazole ring, an isoxazole ring, a thiazole ring, a triazole ring, an oxadiazole ring, a thiadiazole ring, a dioxazole ring, a dithiazole ring, a tetrazole ring, a pentazole ring, a pyridine ring, a pyran ring, a thiopyran ring, a phospholine ring, a borabenzene ring, a silyne ring, a piperidine ring, a diazine ring, an oxazine ring, a thiazine ring, a triazine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pteridine ring. Preferably, it is at least one selected from the group consisting of an imidazole ring, a furan ring, a pyrrole ring, a thiophene ring, an oxazole ring, a thiazole ring, a pyrazole ring, a γ-pyran ring, a pyridine ring, a piperidine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pteridine ring.

[0031] Examples of the alicyclic ring that the heterocyclic compound ligand may have include the same rings as the alicyclic ring that the aromatic hydrocarbon compound ligand may have. When the heterocyclic compound ligand has two or more heterocycles or has an alicycle, it may have a linking group that links the rings. Examples of the linking group include the same linking groups that the aromatic hydrocarbon compound ligand may have. Examples of the coordinating functional group that the heterocyclic compound ligand may have include the same coordinating functional groups as the coordinating functional groups that the aromatic hydrocarbon compound ligand has.

[0032] In the present invention, the heterocyclic compound ligand may be a commercially available product or may be synthesized. Examples of the heterocyclic compound ligand include the following compounds (d1) to (d20), (e1) to (e20), and (f1) to (f23).

[0033] [ka]

[0034] [ka]

[0035] [ka]

[0036] In the present invention, the heterocyclic compound ligand is preferably, for example, one or more compounds selected from the group consisting of (d1), (d3), (d8), (e5) and (f14).

[0037] The content of the heterocyclic compound ligand, which is a component of the organometallic framework, is, for example, 1 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, and can be, for example, 70 mol% or less, preferably 60 mol% or less, relative to the total amount of the organometallic framework. If the content is less than 1 mol% or more than 70 mol%, the gas-encapsulating space in the organometallic framework may not be formed or may shrink, which may result in a deterioration in the gas storage / release properties.

[0038] <Metal ions> The metal ions that are components of the metal-organic framework are not particularly limited as long as they are ions of metals belonging to periods 2 to 6 of the periodic table. For example, one or more polyvalent ions of metals selected from the group consisting of Li, Na, Mg, Al, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Ba, Pb, La, Ce, Nd, and Eu can be used. Preferably, one or more polyvalent ions of metals selected from the group consisting of Li, Na, Mg, Ca, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Pd, Ag, Cd, In, Sn, and Pb can be used. More preferably, one or more polyvalent ions of metals selected from the group consisting of Fe 2+ , Fe 3+ , Zn 2+ , Pb 2+ , Ni 2+ , Co 3+ , Co2+ , Mn 2+ , Cu 2+ , Li + , Na + , Ca 2+ , Mg 2+ , Ag + and Al 3+ It is one or more selected from the group consisting of:

[0039] The content of metal ions, which are components of the metal-organic framework, relative to the total amount of the metal-organic framework is, for example, 1 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, and can be, for example, 70 mol% or less, preferably 60 mol% or less. If the content is less than 1 mol% or more than 70 mol%, the gas-encapsulating space in the metal-organic framework may not be formed or may shrink, which may result in a deterioration in the gas storage / release properties.

[0040] <Other components of metal-organic frameworks> The metal-organic framework may contain other components in addition to the aromatic hydrocarbon compound ligand, the heterocyclic compound ligand, and the metal ion, such as an alicyclic compound having no aromatic hydrocarbon ring, a non-metal ion, etc. The amount of other components present in the metal-organic framework can be, for example, less than 50 mol %, preferably less than 30 mol %, and more preferably less than 20 mol % of the metal-organic framework.

[0041] <Structure of metal-organic frameworks> The organometallic framework contained in the gas storage / release material of the present invention is constituted by forming bonds between an aromatic hydrocarbon compound ligand and a metal ion, and between a heterocyclic compound ligand and a metal ion. Preferably, the framework is constituted by ionic bonds between a coordinating functional group in the aromatic hydrocarbon compound ligand and a metal ion, and between a heterocyclic ring and / or a coordinating functional group in the heterocyclic compound ligand and a metal ion.

[0042] Examples of metal-organic frameworks include those represented by the structural formula (I) and / or (II): [ka] In structural formulas (I) and (II), Ar represents an aromatic hydrocarbon ring; L represents an aromatic hydrocarbon ring; 1 is a coordinating functional group, L 2 is a coordinating functional group, Ht is a heterocycle, and M is a metal ion. Examples include those having a structure represented by the following formula:

[0043] In structural formulas (I) and (II), the aromatic hydrocarbon ring Ar is preferably one or more rings selected from the group consisting of a benzene ring, a naphthalene ring, an anthracene ring, a fluorene ring, a pyrene ring, etc. A benzene ring is more preferred.

[0044] In the structural formulas (I) and (II), the coordinating functional group L 1 is preferably one or more selected from the group consisting of a carboxyl group (-COOH), a sulfonic acid group (-SO3H), a primary amino group (-NH2), a hydroxyl group (-OH), a thiol group (-SH), and a phosphate group (-PO3H2). More preferably, it is any one of a carboxyl group (-COOH), a sulfonic acid group (-SO3H), a primary amino group (-NH2), a hydroxyl group (-OH), and a thiol group (-SH).

[0045] In structural formulas (I) and (II), the heterocycle Ht is preferably a heterocycle containing one or more heteroatoms selected from nitrogen, oxygen, and sulfur, more preferably one or more selected from the group consisting of an imidazole ring, a furan ring, a pyrrole ring, a thiophene ring, an oxazole ring, a thiazole ring, a pyrazole ring, a γ-pyran ring, a pyridine ring, a piperidine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pteridine ring, and even more preferably an imidazole group.

[0046] In structural formula (II), coordinating functional group L 2is preferably one or more selected from the group consisting of a carboxyl group (-COOH), a sulfonic acid group (-SO3H), a primary amino group (-NH2), a hydroxyl group (-OH), a thiol group (-SH), and a phosphate group (-PO3H2). More preferably, it is any one of a carboxyl group (-COOH), a sulfonic acid group (-SO3H), a primary amino group (-NH2), a hydroxyl group (-OH), and a thiol group (-SH).

[0047] [Other components contained in gas storage and release materials] The gas storage / release material of the present invention may contain other components in addition to the organometallic framework, such as one or more selected from the group consisting of resins, fillers, various additives, etc.

[0048] The resin is not particularly limited, but examples thereof include one or more selected from the group consisting of polyolefin resins, polyester resins, polyether resins, acrylic resins, polyamide resins, polyimide resins, urethane resins, and the like. The filler is not particularly limited, but examples thereof include one or more selected from the group consisting of silica, talc, clay, calcium carbonate, barium sulfate, titanium oxide, glass flakes, carbon fiber, glass fiber, metal fiber, organic fiber, organic nanofiber, inorganic nanofiber, metal nanofiber, and the like. The various additives are not particularly limited, but examples thereof include one or more selected from the group consisting of colorants such as organic pigments, inorganic pigments, and dyes, adsorbents such as zeolites and activated carbon, plasticizers, antibacterial agents, conductive materials, antioxidants, and gas storage and release materials other than the above-mentioned gas storage and release materials.

[0049] The content of the other components in the gas storage and release material can be, for example, 99% by mass or less, preferably 90% by mass or less, and more preferably 50% by mass or less. If the content of the other components exceeds 99% by mass, the gas storage properties may not be fully exhibited.

[0050] <Shape of gas storage and release material> The gas storage and release material may have any shape, such as particles, fibers, films, nonwoven fabrics, woven fabrics, porous bodies, molded bodies, and the like. In the case of particles, the average particle diameter can be arbitrarily adjusted within the range of 0.1 μm to 20 mm. The average particle diameter of the gas storage / release material in the present invention is determined by the volume-based cumulative particle diameter D at 50% cumulative volume by a laser diffraction / scattering particle size distribution measurement method. 50 is the value. In the case of fibers, the length can be adjusted arbitrarily within the range of 1 mm to 3 m, the diameter of 0.1 mm to 5 mm, and the denier number of 0.5 d to 20 d. In the case of a film, the thickness can be adjusted arbitrarily within the range of, for example, 2 μm to 5 mm, and the width and length of the film can be set to any size. In the case of nonwoven or woven fabric, for example, the basis weight is 5 g / m 2 ~200g / m 2 The ventilation rate is in the range of 5cm 3 / cm 3 s~100cm 3 / cm 3 The range of s can be adjusted arbitrarily. In the case of a porous body, for example, an apparent density of 0.1 g / cm 3 ~1.8g / cm 3 The porosity can be adjusted arbitrarily within the range of 5 to 80 vol %. In the case of a molded article, any molding means such as extrusion molding or injection molding may be used to prepare a molded article of any shape. The gas storage / release material of the present invention is preferably in the form of particles, porous material, nonwoven fabric, film or fiber from the viewpoints of ease of production, ease of adjusting the contact area with various gases, ease of handling, etc.

[0051] <Gas stored and released by gas storage and release materials> The gas stored and released by the gas storage and release material of the present invention is not particularly limited. Examples include one or more gases selected from the group consisting of hydrogen, carbon dioxide, carbon monoxide, hydrogen sulfide, ammonia, nitrogen, nitrogen dioxide, rare gases (helium, neon, argon, krypton, radon), hydrocarbon gases (methane, ethane, propane, butane, acetylene, etc.), oxygen, and halogen gases (fluorine, chlorine). Preferably, the gas is one or more gases selected from the group consisting of hydrogen, nitrogen, carbon dioxide, argon, methane, ethane, propane, and acetylene, with hydrogen being particularly preferred.

[0052] <Method of storing and releasing gas> The method for storing (associating) and releasing (desorbing) gas in the gas storage / release material of the present invention is not particularly limited. Any known method for storing and releasing hydrogen in a gas storage / release material, particularly a hydrogen storage material, can be used. Examples of such methods include one or more means selected from the group consisting of pressurization, decompression, temperature increase (heating), temperature decrease (cooling), application of electric potential, and irradiation with energy waves (ultraviolet rays, infrared rays, electromagnetic waves, etc.).

[0053] The storage means is preferably a method including one or more means selected from the group consisting of pressurization, depressurization, temperature increase (heating), temperature decrease (cooling), application of electric potential, and ultraviolet irradiation, and more preferably a method including one or more means selected from the group consisting of pressurization, depressurization, temperature increase (heating), and temperature decrease (cooling). In the present invention, a method including pressurization means is particularly preferred. The pressure to be applied when using a pressurizing means for storage is not particularly limited, but it is preferable to apply a pressure of, for example, 0.01 MPa or more, preferably 0.05 MPa or more, and more preferably 0.1 MPa or more.

[0054] The releasing means is preferably a method including one or more means selected from the group consisting of decompression, pressurization, temperature increase (heating), temperature decrease (cooling), application of electric potential, and ultraviolet irradiation, and more preferably a method including one or more means selected from the group consisting of decompression, pressurization, temperature increase (heating), and temperature decrease (cooling). In the present invention, a method including a decompression means is particularly preferred. The gas storage (association) and release (desorption) means in the gas storage and release material of the present invention is very useful because it can store (associate) and release (desorption) gas even under mild conditions when using the above means (for example, milder conditions than those for hydrogen storage alloys). The pressure to be reduced when using a pressure reducing means as the discharging means is not particularly limited, but it is preferable to reduce the pressure to, for example, 0.01 MPa or more, preferably 0.05 MPa or more, and more preferably 0.1 MPa or more.

[0055] <Method for manufacturing gas storage and release material> The method for producing the gas storage / release material of the present invention is not particularly limited. For example, components of the metal-organic framework, such as an aromatic hydrocarbon compound ligand, a heterocyclic compound ligand, a metal ion, and other components used as needed, are mixed and reacted to form the metal-organic framework, and other components are added as needed. The other components may be present during the reaction to form the metal-organic framework. In producing the gas storage and release material, means such as heating, pressurization, cooling, decompression, and stirring may be used as necessary.

[0056] <Applications of gas storage and release materials> The gas storage and release material of the present invention can safely store gases at room temperature (25°C ± 20°C) and atmospheric pressure for long periods of time and release the stored gases by a simple means. The gas storage and release material of the present invention is particularly useful as a hydrogen storage material because it can safely store hydrogen at room temperature (25°C ± 20°C) and atmospheric pressure for long periods of time and release the stored hydrogen by a simple means. Furthermore, since it has excellent hydrogen storage and release properties even at low pressures below atmospheric pressure, where hydrogen storage alloys and functional carbon materials (such as graphene oxide) do not exhibit hydrogen storage and release properties, it is also useful as a hydrogen storage material from this point of view. Furthermore, due to its excellent moldability, it can be easily processed into any shape, and due to its light weight, it can be easily transported and stored.

[0057] For example, hydrogen is produced in a water electrolysis hydrogen production device using electricity generated using renewable energy such as wind power, wave power, geothermal power, and solar power, and the hydrogen is stored in the gas storage and release material of the present invention housed in an on-board container, etc. The container, etc. containing the gas storage and release material with stored hydrogen is loaded onto a vehicle and transported to a hot spring facility equipped with a hydrogen storage material tank and a pure hydrogen fuel cell, and the hydrogen is transferred from the gas storage and release material to these facilities. The electricity and hot water generated by the fuel cell will be used in the hot spring facility, and "heat cascade utilization" will be implemented during hydrogen transport, with the heat generated on the hydrogen storage side being used to heat the hydrogen release side. Furthermore, the heat required to release hydrogen from the hydrogen storage material tank can be provided by utilizing low-temperature waste heat from the building, improving energy efficiency. [Example]

[0058] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0059] [Example 1] <Synthesis of organometallic framework> To a 500 mL beaker, 5.0 g of 5-methoxyisophthalic acid was added, and then 80 mL of N,N-dimethylformamide and 20 mL of ethanol were added, followed by ultrasonic irradiation for 20 minutes to prepare solution A. Solution B was prepared by adding 4.0 g of 1H-imidazole-4,5-dicarboxylic acid to a 200 mL beaker, followed by adding 80 mL of N,N-dimethylformamide and 20 mL of ethanol, and irradiating the mixture with ultrasound for 20 minutes. Solution A and solution B were added to a 500 mL beaker, and solution C was prepared by irradiating them with ultrasound for 20 minutes. To a 200 mL beaker, 2.33 g of zinc acetate was added, and then 20 mL of water and 80 mL of N,N-dimethylformamide were added and dissolved to prepare solution D. Solution C and solution D were added to a 500 mL beaker and ultrasonicated for 20 minutes to prepare solution E. A 500 mL round-bottom flask equipped with a condenser was used as a reaction vessel, and Solution E was added to the reaction vessel. After stirring at 110-130°C for 12 hours, the mixture was cooled to room temperature and filtered using a glass filter G3 to separate the precipitate (crystals) from the supernatant. The resulting precipitate (crystals) was mixed with 10 mL of ethanol and washed three times to obtain the desired metal-organic framework in a powder state.

[0060] <Evaluation of hydrogen storage capacity> The hydrogen storage capacity was evaluated by the following method. The metal-organic framework obtained in Example 1 was packed into a stainless steel sample tube, and a PCT (Hydrogen Pressure-Composition-Isomers) measurement device (Microtrac, Belsop MaxG) was used to measure the reduced pressure P caused by the adsorption of hydrogen by the metal-organic framework when a constant pressure was applied to the cavity of the sample tube. The mass % of hydrogen adsorbed to the metal-organic framework was calculated using the gas equation of state (PV=nRT (P: pressure, V: volume, n: number of moles, R: gas constant, T: temperature)). This operation was repeated while gradually increasing the pressure applied to the cavity of the sample tube from 0 MPa, and the adsorption amount was plotted against the pressure. The plot was performed using a Microtrac, Belsop MaxG measurement device, and a hydrogen storage rate curve was obtained. The hydrogen storage rate curve showing the relationship between the applied pressure and the amount of stored hydrogen (mass %) for the metal-organic structure of Example 1 was as shown in FIG. It can be seen from FIG. 1 that the gas storage and release material synthesized in Example 1 has a high hydrogen storage capacity even in a low pressure region.

[0061] <Scanning electron microscope observation> The metal-organic framework synthesized in Example 1 was observed using a scanning electron microscope, and the results are shown in FIG. 2, it was confirmed that the metal-organic framework obtained in Example 1 has a large number of pores on its surface, approximately 0.1 μm to 0.3 μm in size, and that it has a porous structure with many holes that connect to the internal porous space. It can be inferred that gas molecules are adsorbed into the hydrogen-containing space inside the metal-organic framework molecules through these pores. The conditions for the scanning electron microscope observation are as follows: ·Equipment: Atomic resolution analytical electron microscope (manufactured by JEOL, JEM-ARM200F Dual-X) Measurement conditions: Acceleration voltage 300kV, measurement temperature -100℃

[0062] <Structural analysis of metal-organic frameworks> (FT-IR measurement) The FT-IR of the organometallic framework obtained in Example 1 was measured by a single-reflection ATR method using a Fourier transform infrared spectrophotometer (manufactured by JASCO Corporation, FT / IR-6800) to analyze the molecular structure. The results are as follows. CH:2922cm -1 , 2959cm -1 Phenyl ring: 1379 cm -1 , 3103cm -1 , 3252cm -1 NH:2844cm -1 CO:1461cm -1 , 1543cm -1 Zn 2+ :820cm -1

[0063] (Gel permeation chromatography (GPC) measurement) For the organometallic structure obtained in Example 1, a gel permeation chromatography (GPC) apparatus (Shimadzu Corporation) was fitted with an HPLC column (Shimadzu GLC Corporation's "Shim-pack GPC-805"), and the gas storage / release material dissolved in N,N-dimethylformamide solvent was injected to measure the column retention time. The results are shown in Figure 3. The weight average molecular weight in terms of polystyrene was calculated from the obtained column retention time by comparison with a calibration curve prepared in advance by measuring polystyrene whose molecular weight was known. The gel permeation chromatography device (manufactured by Shimadzu Corporation) had the following configuration: System: Nexera GPC system System controller: CBM-40 Liquid delivery unit: LC40D Online degassing unit: DGU-403 Autosampler: SIL-40C Column oven: CTO-40C Detector: RID-20ABLK, LabSolutions GPC software, LC workstation PC, LabSolutions LC Single LC Column: Shim-pack GPC-805 Solvent: N,N-dimethylformamide

[0064] (Structural analysis) The results of FT-IR measurement and gel permeation chromatography (GPC) measurement showed that the organometallic framework obtained in Example 1 had a weight-average molecular weight of 27,000, and the carboxyl group of 5-methoxyisophthalic acid, the carboxyl group of 1H-imidazole-4,5-dicarboxylic acid, and the N atom of the imidazole ring and Zn 2+ It was found that bonds were formed between the cations (zinc ions) to form complexes and form a polymer network structure.

[0065] (specific surface area measurement) The specific surface area of ​​the metal-organic structure obtained in Example 1 was measured using an N gas adsorption method under the following conditions. As a result, the specific surface area of ​​the metal-organic structure obtained in Example 1 was 3798 m 2 / g, and it was found that many gas species can be adsorbed. Equipment: Specific surface area analyzer (Micromeritics, 3Flex) Measurement principle: Constant volume method Adsorption gas: Nitrogen gas Analysis items: Specific surface area by BET method Measurement method: After degassing the organometallic structure obtained in Example 1 under reduced pressure at 140°C for 12 hours, the nitrogen gas adsorption isotherm was measured at liquid nitrogen temperature (77K) and the specific surface area was calculated by the BET method.

[0066] (Differential scanning calorimetry (DSC analysis)) DSC analysis (Differential Scanning Calorimetry) of the metal-organic framework obtained in Example 1 was carried out under the following conditions. As a result, the metal-organic framework obtained in Example 1 showed no mass change until the temperature exceeded 400°C, and it was found to be thermally stable up to 400°C. The DSC measurement results showed that the crystallinity was high between -100°C and -120°C. Since no particularly clear peaks were observed overall, it was found that the structure did not exhibit thermal behavior such as a glass transition phenomenon in the range of 0°C to -120°C, and that the porous structure was firmly maintained. Apparatus: Differential scanning calorimetry apparatus (TA Instruments, DSC 2500) Atmosphere: Nitrogen flow ·Temperature / Calorie Calibration: Pure water Temperature range: Approximately -120°C to 30°C Heating rate: 10℃ / min

[0067] [Comparative Example 1] 50 ml of a palladium chloride aqueous solution (5% by mass in 10% by mass HCl) was diluted 10-fold in a volumetric flask, and 30 ml of the solution was poured into a 200 ml round-bottom flask. 3.0 g of graphene oxide was added, and the round-bottom flask was immersed in an ultrasonicator (AS ONE Corporation, dual-frequency, resin housing type MCD-2P) and ultrasonicated for 2 hours. Then, 1% ammonia aqueous solution was added dropwise to the round-bottom flask until the pH indicator paper indicated a pH of 7. The resulting solution was filtered through a glass filter G3, and the powdery residue on the glass filter was washed with 10 ml of water. The resulting powder was placed in a pot mill (Kenis Corporation, MT-90 mm), placed on a benchtop pot mill stand (AS ONE Corporation, PM-001 2-7816-01), and processed at 300 rpm for 2 hours. The obtained powder was processed through a test sieve (Tokyo Screen Co., Ltd., JTS-200-45-48, mesh: plain weave, mesh size: 0.053 mm) to separate the graphene oxide, which was used as a sample for evaluating hydrogen storage and release capacity according to Comparative Example 1. The graphene oxide of Comparative Example 1 is a carbon compound formed by stacking layers of two-dimensionally extending six-membered rings made of carbon-carbon bonds, with the distance between layers ranging from 0.5 nm to 2 nm and palladium dispersed between the layers.

[0068] The hydrogen storage and release capacity of the obtained sample for evaluating hydrogen storage and release capacity was evaluated in the same manner as in Example 1. The results are also shown in Figure 1. Figure 1 shows that the gas storage and release material (metal-organic framework) according to Example 1 exhibits higher hydrogen storage and release capacity than the graphene oxide according to Comparative Example 1. This confirms that the gas storage / release material of the present invention is useful as a material capable of storing and releasing gas, particularly hydrogen.

Claims

1. A gas storage and release material containing a metal-organic framework including, as components, an aromatic hydrocarbon compound ligand, a heterocyclic compound ligand, and a metal ion.

2. 2. The gas storage and release material according to claim 1, wherein the aromatic hydrocarbon compound ligand is an aromatic hydrocarbon compound having an aromatic hydrocarbon ring in the molecule.

3. 3. The gas storage and release material according to claim 1, wherein the heterocyclic compound ligand is a heterocyclic compound having a heterocycle containing one or more of nitrogen, oxygen, and sulfur as a heteroatom in the molecule.

4. 3. The gas storage and release material according to claim 1, wherein the metal ions are ions of metals belonging to periods 2 to 6 of the periodic table.

5. The metal-organic framework is represented by structural formula (I) and / or (II); 【Chemistry 1】 (In structural formulas (I) and (II), Ar represents an aromatic hydrocarbon ring; L represents an aromatic hydrocarbon ring; １ is a coordinating functional group, L ２ is a coordinating functional group, Ht is a heterocycle, and M is a metal ion. The gas storage and release material according to claim 1 or 2, having a structure represented by:

6. 3. The gas storage and release material according to claim 1, wherein the heterocycle in the heterocyclic compound ligand is at least one selected from the group consisting of an imidazole ring, a furan ring, a pyrrole ring, a thiophene ring, an oxazole ring, a thiazole ring, a pyrazole ring, a γ-pyran ring, a pyridine ring, a piperidine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pteridine ring.

7. The metal ion is Fe ２＋ , Fe ３＋ , Zn ２＋ , Pb ２＋ , Ni ２＋ , Mn ２＋ , Cu ２＋ , Co ３＋ , Co ２＋ , Li ＋ , Na ＋ , Ca ２＋ , Mg ２＋ , Ag ＋ and Al ３＋ The gas storage and release material according to claim 1 or 2, which is one or more selected from the group consisting of:

8. 3. The gas storage and release material according to claim 1, wherein the aromatic hydrocarbon compound ligand comprises 5-methoxyisophthalic acid.

9. 3. The gas storage and release material according to claim 1, wherein the heterocyclic compound ligand comprises 1H-imidazole-4,5-dicarboxylic acid.

10. 3. The gas storage and release material according to claim 1, wherein the gas stored in the gas storage and release material is one or more selected from the group consisting of hydrogen, carbon dioxide, ammonia, nitrogen, a rare gas, and a hydrocarbon gas.

11. 3. The gas storage and / or release material according to claim 1, wherein the gas is stored and / or released by a method comprising one or more means selected from the group consisting of pressurization, depressurization, temperature increase, temperature decrease, application of an electric potential, and irradiation with an energy wave.

12. 3. The gas storage and release material according to claim 1, wherein the gas storage and release material is in the form of particles, fibers, a film, a nonwoven fabric, a woven fabric, a porous body, or a molded body.

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