JP7651811B2 - Gas Storage and Release Compounds - Google Patents

Description

The present invention relates to a gas storage and release compound capable of storing and releasing gas.

In order to solve environmental problems such as global warming, efforts are underway to develop clean energy sources to replace fossil fuels. Of 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 heat generation, and has a low environmental impact as no carbon dioxide is emitted when generating electricity using fuel cells or internal combustion engines.

To use hydrogen as an energy source, it is necessary to build a hydrogen storage and release system that can flexibly respond to changing demand. For example, it is necessary to build a hydrogen supply chain that transports hydrogen obtained by electrolyzing water using surplus electricity to facilities where it will be used.
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, in order to use hydrogen, it was necessary to transport high-pressure hydrogen or liquefied hydrogen by tank truck. In addition, hydrogen storage facilities also required the development of large-scale infrastructure such as high-pressure hydrogen gas tanks.

Instead of using a high-pressure hydrogen gas storage/release system using a container, when using hydrogen on-site, a hydrogen storage/release system using a hydrogen storage material that can safely store and release a large amount of hydrogen at low pressure by the interaction between hydrogen and the material is being considered. A hydrogen storage material is a material that can selectively and reversibly store and release hydrogen. Hydrogen storage alloys are considered to be promising hydrogen storage materials, but they 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 have poor workability, and the density of the titanium and manganese that make up the alloys is as high as 4 to 8 g/cm ³ , making the storage body heavy, and cooling is required when storing hydrogen and heating is required when releasing hydrogen, which is a problem in terms of handling.

Patent Document 1 describes a hydrogen storage material made of at least one conjugated polymer selected from the group consisting of poly(phenylacetylene)-based polymers, polythiophene-based polymers, and poly(phenylenevinylene)-based polymers, which has an electron spin density within a specific range as measured by electron spin resonance. However, the amount of hydrogen adsorbed by this hydrogen storage material per gram of polymer is low, at 0.25% by mass or less.
Patent Document 2 describes a hydrogen storage and release material obtained by coating the surface of a porous material such as magnesium aluminometasilicate with polyvinyl alcohol. However, this hydrogen storage and release material has a low hydrogen storage and release capacity and is not practical.
Patent Document 3 describes the use of hydrogen complexes of boron-based compounds such as lithium borohydride and potassium borohydride as hydrogen storage and release materials. However, in order to produce such hydrogen storage and release materials, a large amount of energy is required, such as kneading and pulverizing raw materials using a pulverizer at high temperatures.
Patent Document 4 describes a hydrogen carrier that contains a hydrogen storage portion such as a quinokido structure in the main chain and/or side chain of an organic polymer, the hydrogen storage portion generates hydrogen molecules in the presence of a catalyst and becomes a redox active portion, and the redox active portion stores hydrogen and becomes the hydrogen storage portion through reduction and contact with a proton source. However, since the use of a catalyst, reduction, and contact with a proton source are essential, the handling is poor.

In recent years, basic research on porous coordination polymers (PCPs) and metal-organic frameworks (MOFs) has become active. These are materials that have a structure in which organic compound ions and metal ions are systematically arranged three-dimensionally, utilizing the property that amphoteric compounds are coordinated in close proximity due to the interaction that occurs between negatively charged organic compound ions (monomers) and positively charged metal ions.
Patent Document 5 describes the use of a porous polymer metal complex (porous coordination polymer; PCP) having a three-dimensional network structure formed by phthalic acid-type ligands and metal ions as a gas storage/release material. However, the porous polymer metal complex described in Patent Document 5, which is composed of an organic compound such as phthalic acid and a metal ion, has a problem in terms of durability when used as a gas storage/release material, since the interaction between the organic compound and the metal ion is weak.
Patent Document 6 describes a porous polymer metal complex (porous coordination polymer; PCP) composed of a transition metal ion, an isophthalic acid ion ligand, and a pyrazine ligand. This porous polymer metal complex has the function of adsorbing various gases such as nitrogen, oxygen, or carbon monoxide, and is said to be capable of forming a gas separation membrane by using this. However, the porous polymer metal complex described in Patent Document 6 is a complex in which a metal ion is coordinated with an isophthalic acid ion ligand and a pyrazine ligand, and does not have a polymer main chain in which carbon atoms and carbon atoms or carbon atoms and nitrogen atoms are strongly covalently bonded. Since the structure of a compound having such coordinate bonds is weak, it is prone to hydrolysis by water molecules, for example, and has a problem in terms of durability. In addition, before gas adsorption is expressed, reduced pressure drying at a high temperature of 100° C. or more for three days or more is required, and a large amount of energy is required for pretreatment before use. Furthermore, although it is described that it can be applied to adsorb various gases such as nitrogen, there is no description of the storage and release properties of gases such as hydrogen.
Patent Document 7 describes a porous coordination polymer (PCP) consisting of 1,3,5-benzenetricarboxylate tris[N-(4-pyridyl)amide] and a transition metal ion.
However, the porous coordination polymer described in Patent Document 7 only has an amide group contained in the 1,3,5-benzenetricarboxylate tris[N-(4-pyridyl)amide] ligand, and is not a polyamide bond that covalently bonds monomers to form a polymer compound. Furthermore, the 1,3,5-benzenetricarboxylate tris[N-(4-pyridyl)amide] ligand and the transition metal ion are only coordinate-bonded, and the interaction is weak, and the chemical structure is completely different from that of a polyamide compound formed by a covalent bond having a high bond energy. In addition, the porous coordination polymer in Patent Document 7 is used as a catalyst for performing organic synthesis reactions of low molecules such as the Knoevenagel reaction, the aldol reaction, or the Michael addition, and there is no description of the storage and release properties of gases such as hydrogen.

JP 2018-199106 A JP 2010-89987 A Special table 2016-502968 publication International Publication No. 2015/005280 JP 2017-149683 A Patent No. 6761257 JP 2006-248989 A

The problem to be solved by the present invention is to provide a novel gas storage/release compound that has excellent storage and release properties for various gases, and a gas storage/release material that contains the gas storage/release compound.

The present inventors have conducted extensive research to solve the above problems, and as a result, have found that a gas storage/release compound having a specific structural unit and a gas storage/release material containing the gas storage/release compound have excellent storage/release properties for various gases, particularly hydrogen, and that the above problems can be solved by using the gas storage/release compound.
That is, the present invention for solving the above problems mainly includes the following configurations.
Item 1: A gas storage and release compound having a structural unit represented by formula (1).
Item 2: A method for producing a gas storage/release compound, comprising reacting at least a compound represented by formula (2) with a compound represented by formula (3).
(In formula (3), ^X1 represents any one of OH, halogen, ^OR11 ( ^R11 is an alkyl group having 1 to 6 carbon atoms), or ^NHR12 ( ^R12 is an alkyl group having 1 to 6 carbon atoms). ^{Each X2} independently represents any one of OH, halogen, ^OR21 ( ^R21 is an alkyl group having 1 to 6 carbon atoms), or ^NHR22 ( ^R22 is an alkyl group having 1 to 6 carbon atoms).)
Item 3: A gas storage and release material comprising the gas storage and release compound according to item 1.
Item 4: The gas storage and release material according to Item 3, wherein the gas is at least one selected from the group consisting of hydrogen, carbon dioxide, nitrogen, a rare gas, and a hydrocarbon gas.
Item 5: The gas storage and/or release material according to Item 3 or 4, wherein the gas is stored and/or released by a method including 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.
Item 6: The gas storage and release material according to any one of Items 3 to 5, 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.

INDUSTRIAL APPLICABILITY The present invention provides a novel gas storage/release compound having excellent storage/release properties for various gases, and a gas storage/release material containing the gas storage/release compound.
The gas storage and release compound of the present invention and the gas storage and release material containing the gas storage and release compound have particularly excellent hydrogen storage and release properties.
The gas storage/release compound of the present invention and the gas storage/release material containing the gas storage/release compound can store larger amounts of hydrogen than hydrogen storage alloys and have a lower density, require less energy when cooling to store hydrogen or when heating to release hydrogen, and are easy to control the storage and release of hydrogen.
The gas storage/release compound and the gas storage/release material containing the gas storage/release compound of the present invention can be obtained by a simple synthesis method using commercially available compounds, and are inexpensive and highly versatile. In addition, since the compound is a polymer material with a lower density than hydrogen storage alloys, it is lightweight and easy to handle, and enables efficient hydrogen transportation. Furthermore, the conditions for heating/cooling, pressurization/depressurization, etc. required for storing and releasing hydrogen can be made mild, and the compound can be used under low energy usage.
This will make it possible to safely and inexpensively build a hydrogen supply chain that transports hydrogen produced from surplus electricity to utilization facilities.

FIG. 1 is a diagram showing the hydrogen storage and release characteristics of a gas storage and release material containing the gas storage and release compound of the present invention and a hydrogen storage alloy.

The gas storing and releasing compound and the gas storing and releasing material containing the same of the present invention will be described below.
[Gas storage and release compounds]
The gas storage and release compound of the present invention has a structural unit represented by formula (1).

The structural unit represented by formula (1) can be obtained by reacting at least a compound represented by formula (2) with a compound represented by formula (3).
(In formula (3), ^X1 represents any one of OH, halogen, ^OR11 ( ^R11 is an alkyl group having 1 to 6 carbon atoms), or ^NHR12 ( ^R12 is an alkyl group having 1 to 6 carbon atoms). ^{Each X2} independently represents any one of OH, halogen, ^OR21 ( ^R21 is an alkyl group having 1 to 6 carbon atoms), or ^NHR22 ( ^R22 is an alkyl group having 1 to 6 carbon atoms).)
The compounds represented by formula (2) and formula (3) may be commercially available products or may be obtained by synthesis.

The gas storage/release compound of the present invention may contain a copolymer unit in addition to the structural unit represented by formula (1).
Copolymerization units that may be contained in the gas storage/release compound of the present invention include, for example, those represented by the following formulas (4) to (6), other than the structural units represented by formula (1) or (2).
-HN-R ³⁰ (-NH-) _w ...(4)
-OC-R ³¹ (-CO-) _x ...(5)
(-CO-) _y R ³² (-CO-) _z ...(6)
(In formulas (5) to (7), w is an integer of 1 to 3, x is an integer of 1 to 3, y is 1 or 2, z is 1 or 2, R ³⁰ is a w+1 valent organic group, R ³¹ is an x+1 valent organic group, and R ³² is a y+z valent organic group.)
The structural units represented by formula (1) and formulas (4) to (6) are bonded together by forming an amide bond (-HN-CO- or >N-CO-).
In the present invention, the structural unit represented by formula (4) can be obtained from a polyamine compound other than the compound represented by formula (2), the structural unit represented by formula (5) can be obtained from a polycarboxylic acid other than the compound represented by formula (3) or a reactive derivative thereof, and the structural unit represented by formula (6) can be obtained from a (di)amino(di)carboxylic acid, a reactive derivative thereof, or a lactam.

R ³⁰ , R ³¹ , and R ³² each independently include, for example, a divalent aliphatic hydrocarbon group having 2 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and an aromatic heterocyclic group having 6 to 20 carbon atoms and containing N and/or O and/or S. Preferred examples thereof include an alkylene group, a phenylene group, and the like having 2 to 6 carbon atoms.

R is an organic group having a valence of w+1 in formula (4). Examples of ³⁰ include aromatic diamines such as 1,4-diaminobenzene, 1,3-diaminobenzene, 1,2-diaminobenzene, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 2,3-diaminonaphthalene, 2,6-diaminotoluene, 2,4-diaminotoluene, 3,4-diaminotoluene, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylether, 4,4'-diaminodiphenylether, 4,4'-diamino-1,2-diphenylethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, and 3,3'-diaminodiphenylsulfone; ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, and 1,6-hexaaminodiamine. aliphatic diamines such as isophorone diamine, norbornane diamine, 1,2-cyclohexane diamine, 1,3-cyclohexane diamine, 1,4-cyclohexane diamine, 4,4'-diaminodicyclohexylmethane, piperazine, and the like; polyamine phenols such as 2,2-bis(3-amino-4-hydroxyphenyl)propane, 9,9-bis(3-amino-4-hydroxyphenyl)fluorene, and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, and polyfunctional amines such as 1,2,4-triaminobenzene and 3,4,4'-triaminodiphenyl ether, and the like.

As R ³¹ which is an organic group having a valence of x+1 in the formula (5), for example, a group derived from one or more polycarboxylic acid compounds selected from the group consisting of aromatic dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, benzophenone-4,4'-dicarboxylic acid, 4,4'-biphenyldicarboxylic acid, etc.; aliphatic dibasic acids such as oxalic acid, methylmalonic acid, maleic acid, fumaric acid, malic acid, tartaric acid, thiomalic acid, diglycolic acid, etc.; alicyclic dibasic acids such as 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid, norbornanedicarboxylic acid, etc.; hydrogenated trimellitic acid, pyromellitic acid, hydrogenated pyromellitic acid, benzophenonetetracarboxylic acid, etc., or reactive derivatives thereof (acid halides, esterified products, amidated products, acid anhydrides, etc.).

As R ³² which is an organic group having a y+z valence in formula (6), for example, one or more (di)amino(di)carboxylic acids selected from the group consisting of 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 10-aminocapric acid, 11-aminoundodecanoic acid, aminobenzoic acid, ε-caprolactam, ω-enantholactam, ω-undecalactam, ω-laurolactam, α-pyrrolidone, α-piperidone, etc., or reactive derivatives thereof, or groups derived from lactams are preferred.

The gas storage and release compound of the present invention may be composed only of the structural unit represented by formula (1), or may contain one or more structural units represented by formulas (4) to (6) in addition to the structural unit represented by formula (1).
The content of the structural unit represented by formula (1) relative to the total amount of all structural units in the gas storage/release compound (the structural unit represented by formula (1), the structural unit represented by formula (4), the structural unit represented by formula (5) and the structural unit represented by formula (6), hereinafter, these may be collectively referred to as "all structural units") is 1 to 100 mol%, preferably 5 to 100 mol%, more preferably 10 to 100 mol%. If it is less than 1 mol%, the gas storage/release properties may be deteriorated.

The content of the structural unit represented by formula (4) relative to the total amount of all structural units in the gas storage/release compound is 0 to 99 mol%, preferably 0 to 95 mol%, more preferably 0 to 80 mol%. If it exceeds 99 mol%, the gas storage/release properties may be deteriorated.
The content of the structural unit represented by formula (6) relative to the total amount of all structural units in the gas storage/release compound is 0 to 99 mol%, preferably 0 to 95 mol%, more preferably 0 to 80 mol%. If it exceeds 99 mol%, the gas storage/release properties may be reduced.
The content of the structural unit represented by formula (7) relative to the total amount of all structural units in the gas storage/release compound is 0 to 99 mol%, preferably 0 to 95 mol%, more preferably 0 to 80 mol%. If it exceeds 99 mol%, the gas storage/release properties may be deteriorated.

The weight average molecular weight of the gas storage and release compound of the present invention is not particularly limited, but is 10,000 to 1,000,000, preferably 70,000 to 700,000, and more preferably 80,000 to 300,000. If the weight average molecular weight is less than 10,000, the stability of the chemical bond decreases and the compound is prone to deterioration. If the weight average molecular weight exceeds 1,000,000, the surface area may become small, and the gas storage and release characteristics may deteriorate.

[Method of producing gas storage and release compound]
The gas storage/release compound can be obtained by reacting at least a polyamine component containing a compound represented by formula (2) with a polycarboxylic acid component containing a compound represented by formula (3) using a known polyamide polymerization reaction means.
(In formula (3), ^X1 represents any one of OH, halogen, ^OR11 ( ^R11 is an alkyl group having 1 to 6 carbon atoms), or ^NHR12 ( ^R12 is an alkyl group having 1 to 6 carbon atoms). ^{Each X2} independently represents any one of OH, halogen, ^OR21 ( ^R21 is an alkyl group having 1 to 6 carbon atoms), or ^NHR22 ( ^R22 is an alkyl group having 1 to 6 carbon atoms).)
The compounds represented by formula (2) and formula (3) may be commercially available products or may be obtained by synthesis.

<Polyamine component>
The compound represented by formula (2) contained in the polyamine component is a monomer that reacts with the compound represented by formula (3) to form the structural unit represented by formula (1).
The polyamine component may contain a polyamine other than the compound represented by formula (2) or a reactive derivative thereof. Examples of such polyamines include diamines, polyamine phenols, and other polyamines.
Examples of diamines include aromatic diamines such as 1,4-diaminobenzene, 1,3-diaminobenzene, 1,2-diaminobenzene, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 2,3-diaminonaphthalene, 2,6-diaminotoluene, 2,4-diaminotoluene, 3,4-diaminotoluene, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylether, 4,4'-diaminodiphenylether, 4,4'-diamino-1,2-diphenylethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, and 3,3'-diaminodiphenylsulfone; ethylenediamine, 1,3-propanediamine, and 1,4-butanediamine. One or more selected from the group consisting of aliphatic diamines such as 1,6-hexanediamine, 1,7-heptanediamine, 1,9-nonanediamine, 1,12-dodecamethylenediamine, and metaxylenediamine; alicyclic diamines such as isophoronediamine, norbornanediamine, 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 4,4'-diaminodicyclohexylmethane, and piperazine; polyamine phenols such as 2,2-bis(3-amino-4-hydroxyphenyl)propane, 9,9-bis(3-amino-4-hydroxyphenyl)fluorene, and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane; and polyfunctional amines such as 1,2,4-triaminobenzene and 3,4,4'-triaminodiphenyl ether can be used.
The polyamine or reactive derivative thereof other than the compound represented by formula (2) is a monomer that constitutes a copolymerization unit, which is a structural unit represented by formula (4).

The content of the compound represented by formula (2) in the polyamine component is 1 to 100 mol %, preferably 5 to 100 mol %, and more preferably 10 to 100 mol %. If it is less than 1 mol %, the gas storage and release properties may be reduced.

<Polycarboxylic Acid Component>
The compound represented by formula (3) contained in the polycarboxylic acid component is a monomer that reacts with the compound represented by formula (2) to form the structural unit represented by formula (1).
The polycarboxylic acid used in the present invention may contain a polycarboxylic acid other than the compound represented by formula (3) or a reactive derivative thereof (acid halide, ester, amidation product, acid anhydride, etc.). As such a polycarboxylic acid, for example, one or more selected from the group consisting of aromatic dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, benzophenone-4,4'-dicarboxylic acid, 4,4'-biphenyldicarboxylic acid, etc.; aliphatic dibasic acids such as oxalic acid, methylmalonic acid, maleic acid, fumaric acid, malic acid, tartaric acid, thiomalic acid, diglycolic acid, etc.; alicyclic dibasic acids such as 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid, norbornanedicarboxylic acid, etc.; and polybasic acids such as hydrogenated trimellitic acid, pyromellitic acid, hydrogenated pyromellitic acid, benzophenonetetracarboxylic acid, etc. may be used.
A polycarboxylic acid or a reactive derivative thereof other than the aromatic tricarboxylic acid compound represented by formula (4) or a reactive derivative thereof is a monomer that constitutes a copolymerization unit, which is a structural unit represented by formula (6).

The content of the compound represented by formula (3) in the polycarboxylic acid component is 1 to 100 mol %, preferably 5 to 100 mol %, and more preferably 10 to 100 mol %. If it is less than 1 mol %, the gas storage and release properties may be reduced.

<Other reaction components>
In the present invention, in addition to the polycarboxylic acid component and the polyamine component, (di)amino(di)carboxylic acid compounds (diaminocarboxylic acid compounds, diaminodicarboxylic acid compounds, aminodicarboxylic acid compounds), lactams, etc. can be used as other reaction components as necessary during the polyamide polymerization reaction. (Di)amino(di)carboxylic acid and lactam are monomers that constitute copolymerization units, which are structural units represented by formula (6).

As the (di)amino(di)carboxylic acid compound, for example, one or more compounds selected from the group consisting of 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 10-aminocapric acid, 11-aminoundodecanoic acid, aminobenzoic acid, diaminobenzoic acid, aminoterephthalic acid, diaminoterephthalic acid, aminoisophthalic acid, diaminoisophthalic acid, and the like can be used.
As the lactam, for example, one or more species selected from the group consisting of ε-caprolactam, ω-enantholactam, ω-undecalactam, ω-laurolactam, α-pyrrolidone, α-piperidone, and the like can be used.

<Reaction ratio of each component>
In the present invention, the reaction molar ratio of the polyamine component containing the compound represented by formula (2) to the polycarboxylic acid component containing the compound represented by formula (3) is 0.8 to 1.7 moles, preferably 0.9 to 1.6 moles, more preferably 0.95 to 1.15 moles of the polycarboxylic acid component containing the compound represented by formula (3) per mole of the polyamine component containing the compound represented by formula (2). If the amount of the polycarboxylic acid component containing the compound represented by formula (3) is more than 1.7 moles or less than 0.8 moles, the molecular weight of the gas storage and release compound is not sufficiently large, and the gas storage and release properties may be reduced.
The molar ratio of the compound represented by formula (2) to the compound represented by formula (3) is formula (2):formula (3)=1:1.6 to 1:0.8, preferably 1:1.5 to 1:0.9.
The amount of the "other reactive component" per mole of the polyamine component containing the compound represented by formula (2) is in the range of 0 to 9 moles, preferably 0 to 2 moles.

[Polymerization method]
In the present invention, as a method for reacting at least a polyamine component containing a compound represented by formula (2) with a polycarboxylic acid component containing a compound represented by formula (3), a known polyamide polymerization reaction means can be used.
for example,
(i) a method of converting a polycarboxylic acid component containing a compound represented by formula (3) into an acid chloride and reacting the acid chloride with a polyamine component containing a compound represented by formula (2) in an organic solvent or without a solvent;
(ii) a method in which a polycarboxylic acid component containing a compound represented by formula (3) is converted into a dicarboxylic acid diester, and the diester is reacted with a polyamine component containing a compound represented by formula (2) in the presence of a metal catalyst in an organic solvent or without a solvent;
(iii) a method in which a polycarboxylic acid component containing a compound represented by formula (3) is converted into a dicarboxylic acid and reacted with a polyamine component containing a compound represented by formula (2) in the presence of a carbodiimide catalyst in an organic solvent or without a solvent;
etc.
In the present invention, it is preferable to use a method in which a polycarboxylic acid component containing a compound represented by formula (3) is converted into an acid chloride and reacted with a polyamine component containing a compound represented by formula (2) in an organic solvent.

The organic solvent is not particularly limited, but a wide variety of solvents that dissolve the raw materials used can be used. For example, one or more selected from the group consisting of tetrahydrofuran, N,N'-dimethylacetamide, N-methyl-2-pyrrolidone, N,N'-dimethylformamide, N-methylcaprolactam, tetramethylurea, N,N'-dimethyl-2-imidazolidinone, γ-butyrolactone, hexamethylene phosphoramide, dimethyl sulfoxide, xylene, toluene, and the like can be used.

The present inventors speculate as follows regarding the gas storage and release compound of the present invention.
The structural unit represented by formula (1) contained in the gas storage/release compound of the present invention has a portion that generates a minute positive site (δ+) when polarized, and a portion that generates a minute negative site (δ-) when polarized. The δ+ and δ- in the polymer chains are dielectrically attracted to each other to form a network structure between the polymer chains, and the formed network structure plays a role like a hole or small chamber that holds gas molecules. It is speculated that this will result in the function of storing and releasing gas, for example, hydrogen molecules (hydrogen gas), but the present invention is not limited by this speculation.

[Gas storage and release material]
The gas storage and release material of the present invention contains one or more of the gas storage and release compounds in an amount of 1 to 100% by mass, preferably 10 to 100% by mass, and more preferably 50 to 100% by mass. If the content of the gas storage and release compound is less than 1% by mass, the gas storage properties may not be fully exhibited.
Examples of components other than the gas storing and releasing compound having a repeating unit represented by formula (1) that may be contained in the gas storing and releasing material of the present invention include resins, fillers, various additives, etc.

The resin is not particularly limited, but examples thereof include polyolefin resin, polyester resin, acrylic resin, polyamide resin, urethane resin, etc. The filler is not particularly limited, but examples thereof include silica, talc, clay, calcium carbonate, barium sulfate, titanium oxide, glass flake, carbon fiber, glass fiber, metal fiber, organic fiber, organic nanofiber, inorganic nanofiber, metal nanofiber, etc. The various additives are not particularly limited, but examples thereof include colorants such as organic pigments, inorganic pigments, and dyes, adsorbents such as zeolite and activated carbon, plasticizers, antibacterial agents, conductive materials, etc.

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 size can be adjusted arbitrarily within the range of 1 μm to 1 mm, for example.
In the case of fibers, the length can be adjusted to any value within the range of 1 mm to 10 m and the diameter can be adjusted to any value within the range of 0.1 mm to 5 mm.
In the case of a film, the thickness can be adjusted, for example, within a range of 10 μm to 1 mm. The width and length of the film can be any size. In the case of a nonwoven fabric or woven fabric, the basis weight can be adjusted, for example, within a range of 20 g/m ² to 120 g/m ² .
In the case of a porous body, the apparent density can be adjusted to within the range of 0.04 g/m ³ to 1.2 g/m ³ and the porosity can be adjusted to 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 bodies, nonwoven fabrics, films or fibers from the standpoints of ease of production, adjustment of the area in contact with gases such as hydrogen, and improved handling.

[Gas]
The gas (gas) stored and released by the gas storage and release compound or gas storage and release material of the present invention is not particularly limited. For example, it may be one or more selected from the group consisting of hydrogen, carbon dioxide, nitrogen, rare gases (helium, neon, argon, krypton, radon), hydrocarbon gases (methane, ethane, propane, butane, acetylene, etc.), oxygen, halogen gases (fluorine, chlorine), etc. Preferably, it is one or more selected from the group consisting of hydrogen, nitrogen, argon, methane, ethane, propane, and acetylene, and more preferably hydrogen.

[Method of storing and releasing gas]
The method for storing (associating) and releasing (desorbing) a gas (gas) in the gas storage/release compound or gas storage/release material of the present invention can use a known method for storing and releasing hydrogen in a gas storage/release compound or gas storage/release material, particularly a hydrogen storage material.
For example, the method may include one or more means selected from the group consisting of pressurization, depressurization, temperature increase (heating), temperature decrease (cooling), application of electric potential, and irradiation with energy waves such as ultraviolet rays and infrared rays.

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), and application of electric potential, 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 preferably used.
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), and application of electric potential, 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 preferably used.

[Uses of gas storage and release compounds or gas storage and release materials]
The gas storage/release compound or gas storage/release material of the present invention can safely store a gas (gas) at room temperature (25° C.±20° C.) and atmospheric pressure for a long period of time, and can release the stored gas (gas) by a simple means. The gas storage/release compound or gas storage/release material of the present invention is useful as a hydrogen storage material, since it can safely store hydrogen at room temperature (25° C.±20° C.) and atmospheric pressure for a long period of time, and can release the stored hydrogen by a simple means.
Furthermore, even under low pressure conditions below atmospheric pressure where hydrogen storage alloys do not exhibit hydrogen storage/release characteristics, the alloys have excellent hydrogen storage/release characteristics, and from this point of view, they are also useful as hydrogen storage materials.
Furthermore, since it has excellent moldability, it can be easily processed into any shape, and since it is lightweight, it can be easily transported and stored.

For example, electricity generated at a wind power plant is used to produce hydrogen in a water electrolysis hydrogen production device, and the hydrogen is stored in the gas storage/release compound or gas storage/release material of the present invention housed in an on-board container. The container housing the gas storage/release compound or gas storage/release material that has stored hydrogen is loaded onto a vehicle and transported to a hot spring facility that has a hydrogen storage material tank and a pure hydrogen fuel cell as its equipment, and hydrogen is transferred from the gas storage/release compound or gas storage/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 heat generated on the hydrogen storage side being used to heat the hydrogen release side. In addition, the heat required to release hydrogen from the hydrogen storage material tank can be provided by utilizing low-temperature exhaust heat from the building, improving energy efficiency.

The present invention will be described in more detail below with reference to examples. Note that the present invention is not limited in any way by these examples.

[Example]
Synthesis of Gas Storage and Release Compounds
1.5g (0.017mol) of oxamide, 2.9g (0.017mol) of diglycolyl chloride, and 15ml of dimethylsulfoxide were added to a 200ml round-bottom flask and stirred for 2 hours at 25°C using a magnetic stirrer. 5ml of methanol was added to the reaction solution to cause precipitation, and the resulting precipitate was filtered through a membrane filter with a pore size of 0.45μm to separate the precipitate from the filtrate. The precipitate was air-dried and then vacuum-dried to obtain the target gas storage/release compound.

<Structural analysis>
(FT-IR)
The gas storage/release compound thus obtained was subjected to FT-IR measurement by a single reflection ATR method using a Nicolet 6700 FT-IR device manufactured by Thermo Electron Corp. The results were as follows.
C=O: 1718, 1738 (cm ^-1 )
CH ₂ : 1483, 2868, 2942 (cm ⁻¹ )
NH: 1732, 1774 (cm ⁻¹ )
C-O-C: 1637, 1676 (cm ^-1 )

(Weight average molecular weight)
For the obtained gas storage/release compound, a TSKgel GMHHR-H(S)HT2 column was attached to a gel permeation chromatograph HLC-8321GPC/HT manufactured by Tosoh Corporation, the gas storage/release compound dissolved in o-dichlorobenzene solvent was injected, and the column retention time was measured. From the obtained column retention time, the polystyrene-equivalent molecular weight of the compound according to the example was calculated by comparison with a calibration curve previously prepared by measuring polystyrene whose molecular weight was known.

(Structural Analysis)
From the results of these FT-IR and weight average molecular weight measurements, it was confirmed that the gas storage/release compound according to the example is a polyamide compound having a structural unit represented by the following formula (1), in which polymer molecular chains form a network structure, and having a weight average molecular weight of 135,000.

[Comparative Example]
Synthesis of Gas Storage and Release Compounds
In a 200 ml round-bottom flask, 1.0 g (0.01 mol) of phenylacetylene was dissolved in 25 ml of ethanol to obtain a monomer solution.
A catalyst solution was obtained by dissolving 20 mg of titanium tetrachloride and 15 mg of methylaminoxane in 5 ml of ethanol.
The monomer solution and the catalyst solution were mixed and the mixed solution was stirred at 50° C. The resulting solution was dropped into 20 ml of methanol to obtain a precipitate. The precipitate was filtered through a glass filter G3 to obtain a yellow polyphenyleneacetylene powder.

<Evaluation of hydrogen storage and release capacity>
The hydrogen storage and release capacity of each compound obtained in the Examples and Comparative Examples was evaluated by filling a SUS sample tube with the test powder and observing the PCT curve at 25° C. using a PCT characteristic evaluation device manufactured by Suzuki Shokan Co., Ltd. The PCT characteristic measurement device is a device that measures the characteristics (P: pressure, C: storage amount (absorption amount), T: temperature) when a substance absorbs and releases hydrogen, and is also called a Sieverts apparatus.
The relationship between pressure and the amount of hydrogen stored (Adsorption: mass%) and the amount of hydrogen released (Desorption: mass%) of the gas storage and release compounds according to the Examples and Comparative Examples is as shown in Figure 1. The storage amount and release amount referred to here are the amount of hydrogen stored (absorption amount) or released relative to the mass of the gas storage and release compound, expressed as mass%.

The present inventors speculate as follows about the reason why the gas storage and release properties of the gas storage and release compounds of the Examples are high.
The gas storage/release compound (conjugated aromatic polymer; polyphenylacetylene) shown in the comparative example has a gas adsorption mechanism (hydrogen adsorption mechanism) due to electron cloud, and exhibits gas adsorption ability (hydrogen adsorption ability) under conditions of smaller electron spin density. However, the interaction between the polymer compound and hydrogen molecules is very weak.
On the other hand, the gas storage/release compound of the example (polymer compound having a structure represented by formula (1); polyamide) forms a mesh structure surrounded by dielectric carbon chains having a length of 0.8 nm to 1.5 nm (8 to 15 angstroms). Then, hydrogen molecules of about 0.2 nm (2 angstroms) at 25° C. are embedded inside the mesh structure, resulting in a relatively large interaction between the polymer and the hydrogen molecules. It is presumed that this is why the gas storage/release compound of the example exhibits excellent gas storage/release capability. However, the present invention is not bound by this presumption.

Claims (6)

A gas storage and release compound having a structural unit represented by formula (1) and a weight average molecular weight of 10,000 to 1,000,000 .

A method for producing a gas storage/release compound having a structural unit represented by formula (1), comprising reacting at least a compound represented by formula (2) with a compound represented by formula (3) .

(In formula (3), ^X1 represents any one of OH, halogen, ^OR11 ( ^R11 is an alkyl group having 1 to 6 carbon atoms), or ^NHR12 ( ^R12 is an alkyl group having 1 to 6 carbon atoms). ^{Each X2} independently represents any one of OH, halogen, ^OR21 ( ^R21 is an alkyl group having 1 to 6 carbon atoms), or ^NHR22 ( ^R22 is an alkyl group having 1 to 6 carbon atoms).) A gas storage and release material comprising the gas storage and release compound according to claim 1. The gas storage and release material according to claim 3, wherein the gas is one or more selected from the group consisting of hydrogen, carbon dioxide, nitrogen, a rare gas, and a hydrocarbon gas. The gas storage and/or release material according to claim 3 or 4, wherein the gas is stored and/or released by a method including one or more means selected from the group consisting of pressurization, depressurization, temperature increase, temperature decrease, application of electric potential, and irradiation with energy waves. The gas storage and release material according to any one of claims 3 to 5, wherein the shape of the gas storage and release material is any one of particles, fibers, films, nonwoven fabrics, woven fabrics, porous bodies, and molded bodies.