Hydrogen adsorption material and method for manufacturing hydrogen adsorption material

Abstract

The present invention provides a hydrogen adsorption material with excellent hydrogen adsorption capacity and a method for manufacturing the hydrogen adsorption material. [Solution] The hydrogen adsorption material according to the embodiment comprises a first metal ion, a second metal, and an organic ligand that links the first metal ion, wherein the first metal ion and the organic ligand form a metal-organic structure, the metal-organic structure comprises the second metal, and the second metal is at least one of an alkali metal and an alkaline earth metal.

Description

[Technical Field]

[0001] This disclosure relates to a hydrogen adsorption material and a method for producing a hydrogen adsorption material. [Background technology]

[0002] To reduce greenhouse gas emissions, the use of hydrogen, which does not emit carbon dioxide, is being considered. Efficient hydrogen storage technology is necessary for its utilization.

[0003] As a material for storing hydrogen, Patent Document 1 describes a material with a pore diameter of 2 nm or less and a pore volume of 0.3 cm³. 3 A hydrogen adsorption material is disclosed, which consists of a block of porous material and carbon material precipitated in its pores, obtained by introducing liquid organic matter into the surface and pores of a block of porous material having a concentration of 0.5 / g or less, and then firing the block of porous material at 700°C to 1000°C under an inert gas atmosphere. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2008-230930 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, there is a need for a hydrogen adsorption material that can adsorb more hydrogen than the hydrogen adsorption material described in Patent Document 1. This invention was made in view of the above circumstances, and aims to provide a hydrogen adsorption material with excellent hydrogen adsorption capacity and a method for producing a hydrogen adsorption material. [Means for solving the problem]

[0006] To solve the aforementioned problems, the present invention proposes the following means. (1) The hydrogen adsorption material according to embodiment 1 of the present invention is a hydrogen adsorption material comprising a metal-organic structure, The aforementioned metal-organic structure comprises a first metal ion and an organic ligand that links the first metal ion. The aforementioned metal-organic structure contains a second metal, The second metal is at least one of an alkali metal and an alkaline earth metal. (2) Embodiment 2 of the present invention is the hydrogen adsorption material of Embodiment 1, The metal organic framework is NU-1501-Al, NU-100, NU-1501-Fe, NU1103, BUT-22, UMCM-9, DUT-23(Cu), DUT-23(Co), SNU-70, UMCM-1, MOF-177, NH2-MOF-177, MO F-5, MFU-41-Li, NU-1102, NU-1101, IRMOF-20, MIL-101, MSC-30, AX21, MSC-20, MIL-101-NH2, NU-1500-Al, CYCU-3-Al, UMCM-4, NU-1000, Norit ROW, mBr-MOF-5, MFU-41, UiO-66, UiO-68-Ant, UiO-67, mMe-MOF-5, HKUST-1, NU-125, PCN-250, Zn2(bdc)2(dabco), rht-MOF-7, Ni2(m-dobdc), mono It is at least one of HKUST-1, Ni-MOF-74, ZIF-8, and Cu-MOF-74. (3) Embodiment 3 of the present invention is a hydrogen adsorption material according to Embodiment 1 or 2, In the UV / vis spectrum, the ratio of the absorbance at a wavelength of 500 nm to the absorbance at a wavelength of 370 nm is 0.6 or less. (4) Embodiment 4 of the present invention is a hydrogen adsorption material according to any one of Embodiments 1 to 3, In the powder X-ray diffraction pattern, the ratio of the peak intensity derived from the second metal to the peak derived from the metal-organic structure is 1.0 or less. (5) Embodiment 5 of the present invention is a hydrogen adsorption material according to any one of embodiments 1 to 4, The second metal is Li. (6) The method for producing a hydrogen adsorption material according to aspect 6 of the present invention is: A metal-organic structure comprising a first metal ion and an organic ligand that links the first metal ion, The process includes a grinding and mixing step to obtain a hydrogen adsorption material containing the second metal by grinding and mixing the second metal, The second metal is at least one of an alkali metal and an alkaline earth metal. (7) The method for producing a hydrogen adsorption material according to aspect 7 of the present invention is: A metal-organic structure comprising a first metal ion and an organic ligand that links the first metal ion, A dispersion preparation step involves mixing a solution of the second metal, obtained by dissolving the second metal in a solvent, with the other to obtain a dispersion. A solvent removal step is performed to remove the solvent from the dispersion to obtain a hydrogen adsorbent material containing the second metal, Includes, The second metal is at least one of an alkali metal and an alkaline earth metal. (8) Embodiment 8 of the present invention is a method for producing a hydrogen adsorption material according to Embodiment 6 or 7, The metal organic framework is NU-1501-Al, NU-100, NU-1501-Fe, NU1103, BUT-22, UMCM-9, DUT-23(Cu), DUT-23(Co), SNU-70, UMCM-1, MOF-177, NH2-MOF-177, MO F-5, MFU-41-Li, NU-1102, NU-1101, IRMOF-20, MIL-101, MSC-30, AX21, MSC-20, MIL-101-NH2, NU-1500-Al, CYCU-3-Al, UMCM-4, NU-1000, Norit ROW, mBr-MOF-5, MFU-41, UiO-66, UiO-68-Ant, UiO-67, mMe-MOF-5, HKUST-1, NU-125, PCN-250, Zn2(bdc)2(dabco), rht-MOF-7, Ni2(m-dobdc), mono It is at least one of HKUST-1, Ni-MOF-74, ZIF-8, and Cu-MOF-74. (9) Aspect 9 of the present invention is a method for producing a hydrogen adsorption material according to any one of aspects 6 to 8, The second metal is Li. [Effect of the Invention]

[0007] According to each of the above aspects of the present invention, it is possible to provide a hydrogen adsorption material excellent in hydrogen adsorption ability and a method for producing the hydrogen adsorption material. [Brief Description of the Drawings]

[0008] [Figure 1] Powder X-ray diffraction patterns of hydrogen adsorption material 1, hydrogen adsorption material 2, and UiO-66. [Figure 2] Powder X-ray diffraction patterns of hydrogen adsorption material 3 and UiO-66 and predicted powder X-ray diffraction pattern by crystal analysis of UiO-66. [Figure 3] Powder X-ray diffraction patterns of hydrogen adsorption material 4 and UiO-67 and predicted powder X-ray diffraction pattern by crystal analysis of UiO-67. [Figure 4] FT-IR spectra of hydrogen adsorption material 3 and UiO-66. [Figure 5] FT-IR spectra of hydrogen adsorption material 4 and UiO-67. [Figure 6] UV / vis spectra of hydrogen adsorption material 3 and UiO-66. [Figure 7] UV / vis spectra of hydrogen adsorption material 4 and UiO-67. [Modes for Carrying Out the Invention]

[0009] Hereinafter, a hydrogen adsorption material and a method for producing the hydrogen adsorption material according to an embodiment of the present invention will be described.

[0010] [Hydrogen Adsorption Material] The hydrogen adsorption material according to the embodiment includes a metal-organic framework. The metal-organic framework according to the embodiment is composed of a first metal ion and an organic ligand.

[0011] (Metal-organic framework) The metal-organic structure according to this embodiment consists of a first metal ion and an organic ligand that links the first metal ion. The metal-organic structure (hydrogen adsorption material) according to this embodiment further contains a second metal. Here, a metal-organic structure (MOF) refers to a highly periodic compound having a structure in which a metal ion and a rigid organic ligand capable of forming a coordination bond with the metal ion are crosslinked by the organic ligand.

[0012] "First metal ion" The first metal ion included in the metal-organic structure according to the embodiment is not particularly limited as long as it is a metal ion capable of forming a two-dimensional or three-dimensional structure with the organic ligand. Examples of the first metal ion include Zr ions, Cu ions, Zn ions, Co ions, In ions, Al ions, Fe ions, V ions, Mg ions, Mn ions, Ni ions, Ru ions, Mo ions, Cr ions, W ions, Rh ions, and Pd ions.

[0013] "Organic ligand" The organic ligands included in the metal-organic structure according to the embodiment are not particularly limited as long as they can form a coordination bond with the first metal ion to form a two-dimensional or three-dimensional structure. Examples of organic ligands include oxygen-containing organic ligands and nitrogen-containing organic ligands.

[0014] Examples of oxygen-containing organic ligands include acetylenedicarboxylic acid, trans,trans-muconic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-dibromoterephthalic acid, 2-hydroxyterephthalic acid, tetrahydrofuran-2,3,4,5-tetracarboxylic acid, 1,3,5-tris(4'-carboxy[1,1'-biphenyl]-4-yl)benzene, tetrafluoroisophthalic acid, 2,5-dihydroxyterephthalic acid, 2,6-naphthalenedicarboxylic acid, and 1,2,4,5-tetrakis(4-carboxyphenyl)benzene.

[0015] Examples of nitrogen-containing organic ligands include imidazole, 2-methylimidazole, 2,2'-bipyrimidyl, 1,3,5-tris[(1H-imidazole-1-yl)methyl]benzene, 1,4-di(4-pyridyl)benzene, N,N'-di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxylic acid diimide, pyrazole-3,5-dicarboxylic acid monohydrate, and 5,10,15,20-tetra(4-pyridyl)porphyrin.

[0016] Examples of organic ligands other than oxygen-containing and nitrogen-containing organic ligands include 1,3,5-triethynylbenzene and tetrakis(4-ethynylphenyl)methane.

[0017] In the hydrogen adsorption material according to the embodiment, the metal-organic structure that forms the framework, consisting of a first metal ion and an organic ligand, can be any known metal-organic structure. Examples of metal-organic structures include NU-1501-Al, NU-100, NU-1501-Fe, NU1103, BUT-22, UMCM-9, DUT-23(Cu), DUT-23(Co), SNU-70, UMCM-1, MOF-177, NH2-MOF-177, MOF-5, MFU-41-Li, NU-1102, NU-1101, IRMOF-20, MIL-101, MSC-30, AX21, MSC-20, MIL-101-NH2, NU-1500-Al, CYCU-3-Al, UMCM-4, NU-1000, and Norit. ROW, mBr-MOF-5, MFU-41, UiO-66, UiO-68-Ant, UiO-67, mMe-MOF-5, HKUST-1, NU-125, PCN-250, Zn2(bdc)2(dabco), rht-MOF-7, Ni2(m-dobdc), mono It is preferable that the material be at least one of HKUST-1, Ni-MOF-74, ZIF-8, and Cu-MOF-74.

[0018] The identification of metal-organic structures can be performed by the following method: Using a powder X-ray diffractometer (e.g., MiniFlex from Rigaku), powder X-ray diffraction measurements are performed on the sample (organometallic structure containing a second metal, hydrogen adsorption material) to obtain a powder X-ray diffraction pattern. The metal-organic structure can then be identified by assigning the resulting peaks.

[0019] "Second metal" The secondary metal is at least one of an alkali metal and an alkaline earth metal. Preferably, the secondary metal is at least one selected from the group consisting of Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, and Ra. More preferably, the secondary metal is Li. The amount of hydrogen adsorption can be improved by including the secondary metal in the metal-organic structure of the hydrogen adsorption material. Preferably, the secondary metal is atomically dispersed in the metal-organic structure. Here, atomic dispersion of an alkali metal or alkaline earth metal means that no peaks originating from elemental alkali metals, elemental alkaline earth metals, or their compounds are detected by powder X-ray diffraction. No peaks originating from elemental alkali metals, elemental alkaline earth metals, or their compounds are detected means that in the powder X-ray diffraction pattern, the diffraction intensity at the position (diffraction angle 2θ) where the peak originating from the compound appears is about the same as the noise. The appearance of a peak originating from the compound means that the diffraction intensity at the position (diffraction angle 2θ) where the peak originating from the material appears exceeds the noise range.

[0020] The molar ratio of the metal-organic structure (a metal-organic structure consisting of a primary metal ion and an organic ligand) to the secondary metal (metal-organic structure:secondary metal) is preferably 1:1.02 to 1:67. A molar ratio of 1:1.02 to 1:67 between the metal-organic structure and the secondary metal increases the amount of hydrogen adsorbed by the hydrogen adsorption material.

[0021] The molar ratio of a metal-organic structure (a metal-organic structure consisting of a primary metal ion and an organic ligand) to a secondary metal can be evaluated, for example, by the following method: A hydrogen adsorption material (a metal-organic structure containing a secondary metal) is dissolved in an acid solution and analyzed by inductively coupled plasma (ICP) emission spectroscopy. The molar ratio of the primary metal ion and secondary metal obtained, as well as the molar ratio of the metal-organic structure identified by powder X-ray diffraction, can then be determined.

[0022] "Absorbance" In the UV / vis spectrum of the hydrogen adsorption material according to the embodiment, it is preferable that the ratio of the absorbance at a wavelength of 500 nm (A500 / A370) to the absorbance at a wavelength of 370 nm (A370) is 0.6 or less. When the ratio of the absorbance at a wavelength of 500 nm to the absorbance at a wavelength of 370 nm is 0.6 or less, the second metal is uniformly dispersed atomically within the metal-organic structure. This makes it possible to further improve the hydrogen adsorption capacity of the hydrogen adsorption material.

[0023] The ratio of the absorbance at 500 nm to the absorbance at 370 nm in a hydrogen adsorption material can be measured by the following method: Using a UV-Vis spectrophotometer (e.g., JASCO V-750, integrating sphere unit), the UV / vis spectrum of the hydrogen adsorption material powder (e.g., an organometallic structure containing a secondary metal) is obtained by diffuse reflectance (measurement conditions: diffuse reflectance measurement using an integrating sphere). From the obtained UV / vis spectrum, the ratio of the absorbance at 500 nm (A500) to the absorbance at 370 nm (A500) (A500 / A370) is calculated.

[0024] "Powder X-ray diffraction" In the powder X-ray diffraction pattern of the hydrogen adsorption material according to the embodiment, it is preferable that the ratio of the peak intensity derived from the second metal (AM / AMOF) to the peak intensity derived from the metal-organic structure (AMOF) is 1.0 or less. A ratio of 1.0 or less increases the proportion of the second metal uniformly dispersed atomically within the metal-organic structure, thereby increasing the hydrogen adsorption capacity of the metal-organic structure. The lower limit of the ratio of the peak intensity derived from the second metal to the peak intensity derived from the metal-organic structure is preferably 0. More preferably, the ratio is 0.3 or less. Even more preferably, the ratio is 0.1 or less. If the ratio is 0, it means that all of the second metal in the hydrogen adsorption material according to the embodiment is atomically dispersed within the metal-organic structure. Therefore, the hydrogen adsorption capacity can be further improved. The ratio of the peak intensity derived from the second metal to the peak intensity derived from the metal-organic structure may be 0.004 or higher. The ratio of the peak intensity derived from the second metal to the peak intensity derived from the metal-organic structure may be 0.010 or higher.

[0025] In a hydrogen adsorption material, the ratio (AM / AMOF) of the peak intensity (AM) derived from the second metal to the peak intensity (AMOF) derived from the metal-organic framework can be measured by the following method. Using a powder X-ray diffractometer (e.g., MiniFlex manufactured by Rigaku), powder X-ray diffraction measurement is performed on a sample (an organometallic structure containing the second metal). Thereby, a powder X-ray diffraction pattern of the (organometallic structure containing the second metal) is obtained (measurement conditions: incident X-ray CuKα ray, scanning speed 1.0° / min, the sample is sealed in an airtight sample holder under an Ar atmosphere). In the obtained powder X-ray diffraction pattern, the ratio (AM / AMOF) of the peak intensity (AM) derived from the second metal to the peak intensity (AMOF) derived from the metal-organic framework is calculated. The peak derived from the metal-organic framework and the peak derived from the second metal are selected by the following method. Using a known database, the attribution of the peaks appearing on the powder X-ray diffraction pattern is performed. In the obtained powder X-ray diffraction pattern, when multiple peaks attributed to the metal-organic framework appear, the peak with the maximum diffraction intensity among those peaks is used as the peak derived from the metal-organic framework for the calculation of the ratio. Similarly, in the powder X-ray diffraction pattern, when multiple peaks attributed to the second metal appear, the peak with the maximum diffraction intensity among those peaks is used as the peak derived from the second metal for the calculation of the ratio. Note that the second metal may have peaks of the metal in its elemental form or compounds such as oxides of the metal. In this case, it is also judged to be attributed to the second metal. Also, when the positions of the peak derived from the metal-organic framework and the peak attributed to the second metal overlap, the peak attributed to the second metal is changed from the peak with the maximum peak intensity to the peak with the second highest intensity.

[0026] "BET specific surface area" The BET specific surface area of the hydrogen adsorption material is not particularly limited, but is preferably 400 m 2 / g or more. More preferably, it is 450 m 2 / g or more. The upper limit of the BET specific surface area of the hydrogen adsorption material is not particularly limited, but for example, 1000 m 2 / g, 2000 m 2 / g, 3000 m 2 / g, 4000 m 2 / g or 5000 m2 You can also use / g.

[0027] The specific surface area is measured using the BET (Brunauer, Emmett, Teller) method, which involves adsorbing molecules with a known adsorption area onto the sample at liquid nitrogen temperature and determining the sample's specific surface area from the amount of adsorbed molecules. Specifically, the BET specific surface area can be determined using the single-point BET method with a BET specific surface area analyzer (e.g., MicrotracBEL BELSORP MAX G). (Measurement conditions: Pre-treatment heating at 80°C for 64 hours, adsorbent is nitrogen molecules, measured at liquid nitrogen temperature.)

[0028] "Shape of hydrogen adsorption material" The shape of the hydrogen adsorption material is not particularly limited and can be, for example, in powder or pellet form. However, for ease of handling, the hydrogen adsorption material is preferably molded into pellet form.

[0029] "Other materials" The hydrogen adsorption material according to this embodiment may further contain other components (optional components). Examples of optional components include organic binders.

[0030] <First manufacturing method> A method for producing a hydrogen adsorption material according to the embodiment (first method of production) includes a grinding and mixing step to obtain a hydrogen adsorption material containing a second metal by grinding and mixing a metal-organic structure containing a first metal ion and an organic ligand that links the first metal ion, and a second metal, wherein the second metal is at least one of an alkali metal and an alkaline earth metal.

[0031] (Grinding and mixing process) In the grinding and mixing process, a hydrogen adsorption material containing a metal-organic structure and a metal-second is obtained by grinding and mixing the metal-organic structure and the metal-second. By using a structurally stable metal-organic structure, the metal-second can be added to the structure more stably than with a covalent organic structure (COF).

[0032] "Metal-organic structures used as raw materials" The metal-organic structures used as raw materials in the grinding and mixing process (raw material metal-organic structures) can be any known metal-organic structures. Examples of raw material metal-organic structures include NU-1501-Al, NU-100, NU-1501-Fe, NU1103, BUT-22, UMCM-9, DUT-23(Cu), DUT-23(Co), SNU-70, UMCM-1, MOF-177, NH2-MOF-177, MOF-5, MFU-41-Li, NU-1102, NU-1101, IRMOF-20, MIL-101, MSC-30, AX21, MSC-20, MIL-101-NH2, NU-1500-Al, CYCU-3-Al, UMCM-4, NU-1000, and Norit. ROW, mBr-MOF-5, MFU-41, UiO-66, UiO-68-Ant, UiO-67, mMe-MOF-5, HKUST-1, NU-125, PCN-250, Zn2(bdc)2(dabco), rht-MOF-7, Ni2(m-dobdc), mono It is preferable that the raw material is at least one of HKUST-1, Ni-MOF-74, ZIF-8, and Cu-MOF-74. More preferably, the raw material metal organic structure is ○○.

[0033] The raw material metal-organic structure is not limited to any compound that consists of a primary metal ion and an organic ligand that forms a coordination bond with the primary metal ion and bridges the primary metal ions, and is highly periodic. For example, the raw material metal-organic structure may be synthesized using the primary metal ion and organic ligand described later.

[0034] "First metal ion" The primary metal ion used in the synthesis of the raw material metal organic structure is not particularly limited as long as it can form a coordination bond with the organic ligand and create a two-dimensional or three-dimensional structure. Examples of such primary metal ions include Zr ions, Cu ions, Zn ions, Co ions, In ions, Al ions, Fe ions, V ions, Mg ions, Mn ions, Ni ions, Ru ions, Mo ions, Cr ions, W ions, Rh ions, and Pd ions. Zr is preferred as the primary metal ion.

[0035] "Organic ligand" The organic ligands used in the synthesis of raw material metal organic structures are not particularly limited as long as they can form a coordination bond with the first metal ion to form a two-dimensional or three-dimensional structure. Examples of such organic ligands include oxygen-containing organic ligands and nitrogen-containing organic ligands.

[0036] Examples of oxygen-containing organic ligands used in the synthesis of raw material metal organic structures include acetylenedicarboxylic acid, trans,trans-muconic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-dibromoterephthalic acid, 2-hydroxyterephthalic acid, tetrahydrofuran-2,3,4,5-tetracarboxylic acid, 1,3,5-tris(4'-carboxy[1,1'-biphenyl]-4-yl)benzene, tetrafluoroisophthalic acid, 2,5-dihydroxyterephthalic acid, 2,6-naphthalenedicarboxylic acid, and 1,2,4,5-tetrakis(4-carboxyphenyl)benzene.

[0037] Examples of nitrogen-containing organic ligands used in the synthesis of raw material metal organic structures include imidazole, 2-methylimidazole, 2,2'-bipyrimidyl, 1,3,5-tris[(1H-imidazole-1-yl)methyl]benzene, 1,4-di(4-pyridyl)benzene, N,N'-di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxylic acid diimide, pyrazole-3,5-dicarboxylic acid monohydrate, and 5,10,15,20-tetra(4-pyridyl)porphyrin.

[0038] Other organic ligands besides oxygen-containing and nitrogen-containing organic ligands used in the synthesis of raw material metal organic structures include 1,3,5-triethynylbenzene and tetrakis(4-ethynylphenyl)methane.

[0039] The raw material metal-organic structures can be synthesized by known means using first metal ions and organic ligands.

[0040] "Second metal" The secondary metal dispersed atomically in the raw material metal organic structure is at least one of an alkali metal and an alkaline earth metal. Preferably, the secondary metal is at least one selected from the group consisting of Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, and Ra. More preferably, the secondary metal is Li. The inclusion of the secondary metal in the metal organic structure can improve the amount of hydrogen adsorption. In the first manufacturing method, the secondary metal is preferably an elemental metal. By crushing and mixing the elemental metal, it becomes easier to atomically disperse the secondary metal in the raw material metal organic structure.

[0041] The molar ratio of the raw metal organic structure to the second metal (raw metal organic structure: second metal) is preferably 1:1.02 to 1:67. A molar ratio of 1:1.02 to 1:67 allows for increased hydrogen adsorption by the hydrogen adsorption material.

[0042] "Method of grinding and mixing" The method for grinding and mixing the metal-organic structure and the secondary metal is not particularly limited. When using elemental metals, it is preferable to grind and mix the metal-organic structure and the secondary metal under an inert atmosphere such as an Ar atmosphere or a nitrogen atmosphere. By grinding and mixing the elemental secondary metal in an inert atmosphere, the secondary metal can be incorporated into the metal-organic structure and dispersed atomically. The grinding and mixing method may include using a hand mill with a mortar and pestle, or using a ball mill or the like.

[0043] <Second manufacturing method> A method for producing a hydrogen adsorbent material according to another embodiment (second method of production) includes a dispersion preparation step of mixing a metal-organic structure containing a first metal ion and an organic ligand linking the first metal ion with a second metal solution obtained by dissolving the second metal in a solvent to obtain a dispersion, and a solvent removal step of removing the solvent from the dispersion to obtain a hydrogen adsorbent material containing the second metal, wherein the second metal is at least one of an alkali metal and an alkaline earth metal.

[0044] (Dispersion preparation process) In the dispersion preparation process, a metal-organic structure and a metallosecond solution, in which a metallosecond is dissolved in a solvent, are mixed to obtain a dispersion.

[0045] "Metal-organic structures used as raw materials" The metal-organic structure used as a raw material in the atomic dispersion step (raw material metal-organic structure) can be one of the known metal-organic structures described in the first manufacturing method. Alternatively, a metal-organic structure synthesized from the first metal ion and organic ligand described in the first manufacturing method may be used.

[0046] "Second metal solution" The second metal solution according to this embodiment contains a second metal and a solvent, and the second metal is dissolved in it. The solvent of the second metal solution is not particularly limited as long as it can dissolve the second metal. Examples of solvents include dimethylformamide (DMF). "Second metal" The second metal in the second metal solution is at least one of an alkali metal and an alkaline earth metal. Preferably, the second metal is at least one selected from the group consisting of Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, and Ra. From the viewpoint of solubility and hydrogen adsorption capacity, Li is more preferable as the second metal. Dissolving the second metal in the second metal solution makes it easier for the second metal to be incorporated into the raw material metal organic structure. Preferably, the second metal in the second metal solution is a metal salt or an elemental metal. More preferably, the second metal in the second metal solution is an elemental metal. Dissolving in at least one of the elemental metal state and the ionic state makes it easier for the second metal to be atomically dispersed in the raw material metal organic structure. A portion of the second metal in the solvent may be in an ionic state.

[0047] The concentration of the secondary metal in the secondary metal solution is preferably 0.5% by mass or higher. A concentration of 0.5% by mass or higher in the secondary metal solution facilitates the incorporation of the secondary metal into the metal-organic structure.

[0048] The concentration of the second metal in the second metal solution is preferably 1.0% by mass or less. A concentration of 1.0% by mass or less facilitates the atomic incorporation of the second metal into the metal-organic structure.

[0049] The molar ratio of the raw metal organic structure to the second metal (raw metal organic structure: second metal) is preferably 1:1.02 to 1:67. A molar ratio of 1:1.02 to 1:67 allows for increased hydrogen adsorption by the hydrogen adsorption material.

[0050] "Mixing method" The method for mixing the raw organometallic structure and the second metal solution is not particularly limited. The raw organometallic structure and the second metal solution may be mixed by adding the raw organometallic structure to the second metal solution and mixing with a stirrer to obtain a dispersion.

[0051] The mixing time is not particularly limited, as long as the second metal is incorporated into the raw organometallic structure. For example, the mixing time may be 1 hour or more, or 2 hours or more. The mixing time may be 48 hours or less, 24 hours or less, or 12 hours or less.

[0052] "Solvent removal process" In the solvent removal step, the solvent is removed from the dispersion to obtain a hydrogen adsorption material containing the second metal. The method for removing the solvent from the dispersion is not particularly limited, and known methods can be used. For example, the solvent may be removed by centrifuging the dispersion and washing the precipitate after centrifugation, or by filtering the dispersion using a filter and washing the metal-organic structure remaining on the filter with a solvent, or by heating the dispersion in a vacuum, or by freeze-drying.

[0053] The hydrogen adsorption material and method for producing the hydrogen adsorption material according to the embodiment have been described in detail above. The hydrogen adsorption material according to the embodiment includes a metal-organic structure consisting of a first metal ion and an organic ligand. The metal-organic structure includes a second metal, and the second metal is at least one of an alkali metal and an alkaline earth metal, and therefore has excellent hydrogen adsorption capacity.

[0054] It should be noted that the technical scope of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. Furthermore, it is possible to replace the components in the above embodiments with well-known components as appropriate, without departing from the spirit of the present invention. [Examples]

[0055] Next, embodiments of the present invention will be described. The conditions in the embodiments are merely examples of conditions adopted to confirm the feasibility and effectiveness of the present invention, and the present invention is not limited to these examples of conditions. The present invention can adopt various conditions as long as they do not depart from the spirit of the invention and achieve the objectives of the present invention.

[0056] (Preparation of hydrogen adsorption material 1) 0.505 g of the metal-organic structure (Zr6(OH)4O4(benzene-1,4-dicaroxylato), UiO-66) and 0.285 g of Li were weighed and mixed in a mortar under an argon atmosphere for 30 minutes while being ground. Then, 0.497 g of the metal-organic structure (UiO-66) (total 1.001 g) was added to the mortar and mixed for 30 minutes to obtain the final product (black, hydrogen adsorbent material 1). The molar ratio (MOF:Li) was 1.00:67.

[0057] (Preparation of hydrogen adsorption material 2) 0.505 g of the metal-organic structure (Zr6(OH)4O4(benzene-1,4-dicaroxylato), UiO-66) and 0.139 g of Li were weighed and mixed in a mortar under an argon atmosphere for 30 minutes while being ground. Then, 0.497 g of the metal-organic structure (UiO-66) (total 1.001 g) was added to the mortar and mixed for 30 minutes to obtain the final product (black, hydrogen adsorbent material 2). The molar ratio (MOF:Li) was 1.01:34.

[0058] (Preparation of hydrogen adsorption material 3) Under an argon atmosphere, solid lithium (33 mg) was added to dimethylformamide (DMF) (Li concentration 0.5 mass%), stirred for 20 hours, and filtered to obtain a Li-DMF solution. A metal-organic structure (UiO-66, 262 mg) was added to the obtained Li-DMF solution, and stirred for a further 15 hours. During stirring, the metal-organic structure changed color from yellow to brown. The obtained dispersion was centrifuged (10 K rpm, 10 min), the supernatant was removed, and the remaining precipitate was washed twice with tetrahydrofuran (THF). The final obtained powder was vacuum-dried at 120°C for 24 hours to obtain the final product (brown, hydrogen adsorption material 3). The molar ratio (MOF:Li) was 1.00:18.

[0059] (Preparation of hydrogen adsorption material 4) Under an argon atmosphere, solid lithium (30 mg) was added to dimethylformamide (DMF) (Li concentration 0.5 mass%), stirred for 20 hours, and filtered to obtain a Li-DMF solution. A metal-organic structure (UiO-67, 262 mg) was added to the obtained Li-DMF solution, and stirred for a further 15 hours. During stirring, the metal-organic structure changed color from yellow to brown. The obtained dispersion was centrifuged (10 K rpm, 10 min), the supernatant was removed, and the remaining precipitate was washed twice with tetrahydrofuran (THF). The final obtained powder was vacuum dried at 120°C for 24 hours to obtain the final product (brown, hydrogen adsorption material 4). The molar ratio (MOF:Li) was 1.00:1.02.

[0060] (Powder X-ray diffraction measurement) Powder X-ray diffraction measurements were performed on hydrogen adsorption materials 1, 2, and 3, UiO-66, and UiO-67 using a powder X-ray diffractometer (MiniFlex, Rigaku). The measurement conditions were CuKα incident X-rays, scanning speed of 1.0° / min, and the samples were sealed in an airtight sample holder under an Ar atmosphere. Figure 1 shows the obtained powder X-ray diffraction patterns for hydrogen adsorption materials 1, 2, and UiO-66. Figure 2 shows the obtained powder X-ray diffraction patterns for hydrogen adsorption materials 3 and UiO-66, as well as the powder X-ray diffraction pattern of UiO-66 predicted by crystal analysis. Figure 3 shows the obtained powder X-ray diffraction patterns for hydrogen adsorption materials 4 and UiO-67, as well as the powder X-ray diffraction pattern of UiO-67 predicted by crystal analysis. Table 1 shows the ratio of the peak intensity derived from the second metal to the peak intensity derived from the metal-organic structure. Here, the ratio of the peak intensity derived from the second metal to the peak intensity derived from the metal-organic structure for hydrogen adsorption material 1 was defined as the peak intensity at (110) around 36° / the maximum peak intensity at around 25°. For hydrogen adsorption material 3, the ratio of the peak intensity derived from the second metal to the peak intensity derived from the metal-organic structure was defined as the peak at (110) around 36° / the maximum peak intensity at around 7.4°. For hydrogen adsorption material 4, the ratio of the peak intensity derived from the second metal to the peak intensity derived from the metal-organic structure was defined as the (110) peak around 36° / the maximum peak intensity around 5.7°.

[0061] (Fourier transform infrared spectroscopy) The FT-IR spectra of hydrogen adsorption materials 1, 3, UiO-66, and UiO-67 were measured using a Fourier transform infrared spectrometer (FT-IR instrument, Bruker ALPHA II) (measurement conditions: measured using total internal reflection under an Ar atmosphere). The obtained FT-IR spectra of hydrogen adsorption materials 3 and UiO-66 are shown in Figure 4, and the FT-IR spectra of hydrogen adsorption materials 4 and UiO-67 are shown in Figure 5.

[0062] (UV-visible spectroscopy measurement) The ultraviolet-visible light spectra (UV / vis spectra) of hydrogen adsorption material 1, hydrogen adsorption material 3, UiO-66, and UiO-67 were measured using a UV-visible light spectrophotometer (V-750, manufactured by JASCO). (Measurement conditions: diffuse reflectance measurement using an integrating sphere). The obtained UV / vis spectra of hydrogen adsorption material 3 and UiO-66 are shown in Figure 6, and the UV / vis spectra of hydrogen adsorption material 4 and UiO-67 are shown in Figure 7. The ratio of the absorbance at a wavelength of 500 nm (A500) to the absorbance at a wavelength of 370 nm (A370) (A500 / A370) is shown in Table 1.

[0063] (BET specific surface area) The BET specific surface areas of hydrogen adsorption material 1, hydrogen adsorption material 3, UiO-66, and UiO-67 were determined by the BET single-point method using a BET specific surface area measuring device (e.g., MicrotracBEL BELSORP MAX G). The obtained results are shown in Table 1.

[0064] (Li / Zr) Hydrogen adsorption materials 1, 2, and 3, UiO-66, and UiO-67 were measured using inductively coupled plasma (ICP) emission spectroscopy, and the Li / Zr molar ratios were determined. The results are shown in Table 1.

[0065] (Hydrogen adsorption amount) The hydrogen adsorption amounts of hydrogen adsorption materials 1, 2, 3, UiO-66, and UiO-67 were evaluated using a high-pressure gas adsorption amount measuring device (BELSORP HP, MicrotracBEL). The measurement temperature was set to 25°C, and the pressure was increased to 11.4 MPa under the conditions of pre-treatment heating at 80°C for 32 hours. The hydrogen adsorption amount at 11.4 MPa was then measured. The results are shown in Table 1.

[0066] [Table 1]

[0067] (Confirmation of the effect of Li addition using a hand mill) Figure 1 shows the powder X-ray diffraction patterns of hydrogen adsorption material 1, hydrogen adsorption material 2, and UiO-66. The horizontal axis in Figure 1 represents the diffraction angle 2θ (°), and the vertical axis represents the diffraction intensity (au). Figure 2 shows the powder X-ray diffraction patterns of hydrogen adsorption material 3 and UiO-66, and the powder X-ray diffraction pattern of UiO-66 predicted by crystal analysis. The horizontal axis in Figure 2 represents the diffraction angle 2θ (°), and the vertical axis represents the diffraction intensity (au). Figure 4 shows the FT-IR spectra of hydrogen adsorption material 3 and UiO-66. The horizontal axis in Figure 4 represents the wavenumber (cm²). -1 The graph shows the light intensity, with the vertical axis representing absorbance (au). As shown in Figures 1 and 2, the peaks for hydrogen adsorption material 1, hydrogen adsorption material 2, and hydrogen adsorption material 3 coincided with the peak of the raw material, the metal-organic structure UiO-66. Also, as shown in Figure 4, the peak of the raw material, the metal-organic structure UiO-66, did not disappear. From the above, it was confirmed that the structure of the metal-organic structure was maintained. On the other hand, as shown in Figure 1, peaks (36°) originating from Li(110) were observed in hydrogen adsorption materials 1 and 2, but the diffraction intensity of these peaks was small. From the above, it was found that almost all Li was contained in the metal-organic structure at the atomic level by hand milling (grinding and mixing in a mortar). As shown in Figures 1 and 2, unlike hydrogen adsorption materials 1 and 2, no peaks (36°) originating from Li(110) appeared in hydrogen adsorption material 3. This confirms that using a metal solution makes it easier to incorporate Li into the metal-organic structure in clusters or atomic form smaller than the size detectable by powder X-ray diffraction.

[0068] Figure 6 shows the UV / vis spectra of hydrogen adsorption material 3 and UiO-66. The horizontal axis in Figure 6 represents wavelength (nm), and the vertical axis represents absorbance (au). As shown in Figure 6, the addition of Li revealed a new broad absorption in the visible light band. Furthermore, a comparison of hydrogen adsorption material 1 and UiO-66 in Table 1 confirmed that the amount of hydrogen adsorption increased with the addition of Li. In addition, the amount of hydrogen adsorption can be further improved by reducing the molar ratio of Li. From the above, it was confirmed that metallic Li can be dispersed atomically in a metal-organic structure by hand milling, and that the amount of hydrogen adsorption can be increased.

[0069] (Confirmation of the effect of Li addition using solution) Figure 3 shows the powder X-ray diffraction patterns of hydrogen adsorption material 4 and UiO-67, and the powder X-ray diffraction pattern of UiO-67 predicted by crystal analysis. In Figure 3, the horizontal axis represents the diffraction angle 2θ (°), and the vertical axis represents the diffraction intensity (au). Figure 5 shows the FT-IR spectra of hydrogen adsorption material 4 and UiO-67. In Figure 5, the horizontal axis represents the wavenumber (cm²). -1 The graph shows the vertical axis, and the vertical axis shows the absorbance (au). As shown in Figure 3, the peak of hydrogen adsorption material 4 coincided with the peak of the raw material, the metal-organic structure UiO-67. As shown in Figure 5, the peak of the raw material, the metal-organic structure UiO-67, did not disappear. From the above, it was confirmed that the structure of the metal-organic structure was maintained. In addition, as shown in Figures 1 and 3, unlike hydrogen adsorption materials 1 and 2, hydrogen adsorption material 4 did not show a peak (36°) derived from Li(110). From this, it was confirmed that using a metal solution makes it easier to incorporate Li atomically into the metal-organic structure.

[0070] Figure 7 shows the UV / vis spectra of hydrogen adsorption material 4 and UiO-67. In Figure 7, the horizontal axis represents wavelength (nm) and the vertical axis represents absorbance (au). As shown in Figure 7, similar to hydrogen adsorption material 1, it was confirmed that a broad absorption in the visible light band newly appears when Li is added. As shown in Table 1, it was confirmed that the amount of hydrogen adsorption of hydrogen adsorption material 4 also increases when Li is added, similar to hydrogen adsorption materials 1 and 2. From the above, it was confirmed that by adding and mixing a metal-organic structure to a Li solution, metallic Li can be dispersed atomically and the amount of hydrogen adsorption can be increased.

[0071] From the above, it was confirmed that the amount of hydrogen adsorption can be increased by including at least one of alkali metals and alkaline earth metals in the metal-organic structure.

Claims

1. A hydrogen adsorption material containing a metal-organic structure, The aforementioned metal-organic structure is First metal ion and, It consists of an organic ligand that binds to the first metal ion, The aforementioned metal-organic structure includes a second metal, The hydrogen adsorption material wherein the second metal is at least one of an alkali metal and an alkaline earth metal.

2. The metal organic framework is NU-1501-Al, NU-100, NU-1501-Fe, NU1103, BUT-22, UMCM-9, DUT-23 (Cu), DUT-23 (Co), SNU-70, UMCM-1, MOF-177, NH ２ -MOF-177, MOF-5, MFU-41-Li, NU-1102, NU-1101, IRMOF-20, MIL-101, MSC-30, AX21, MSC-20, MIL-101-NH ２ , NU-1500-Al, CYCU-3-Al, UMCM-4, NU-1000, Norit ROW, mBr-MOF-5, MFU-41, UiO-66, UiO-68-Ant, UiO-67, mMe-MOF-5, HKUST-1, NU-125, PCN-250, Zn ２ (bdc) ２ (dabco), rht-MOF-7, Ni ２ (m-dobdc), ｍｏｎｏ The hydrogen adsorption material according to claim 1, which is at least one of HKUST-1, Ni-MOF-74, ZIF-8, and Cu-MOF-74.

3. The hydrogen adsorption material according to claim 1 or 2, wherein in the UV / vis spectrum, the ratio of the absorbance at a wavelength of 500 nm to the absorbance at a wavelength of 370 nm is 0.6 or less.

4. The hydrogen adsorption material according to claim 1 or 2, wherein in the powder X-ray diffraction pattern, the ratio of the peak intensity derived from the second metal to the peak derived from the metal-organic structure is 1.0 or less.

5. The hydrogen adsorption material according to claim 1 or 2, wherein the second metal is Li.

6. A metal-organic structure comprising a first metal ion and an organic ligand that links the first metal ion, The process includes a grinding and mixing step to obtain a hydrogen adsorption material containing the second metal by grinding and mixing the second metal, A method for producing a hydrogen adsorption material, wherein the second metal is at least one of an alkali metal and an alkaline earth metal.

7. A metal-organic structure comprising a first metal ion and an organic ligand that links the first metal ion, A dispersion preparation step involves mixing a solution of the second metal, obtained by dissolving the second metal in a solvent, with the other to obtain a dispersion. A solvent removal step is performed to remove the solvent from the dispersion to obtain a hydrogen adsorbent material containing the second metal, Includes, A method for producing a hydrogen adsorption material, wherein the second metal is at least one of an alkali metal and an alkaline earth metal.

8. The metal-organic framework is NU-1501-Al, NU-100, NU-1501-Fe, NU1103, BUT-22, UCM-9, DUT-23(Cu), DUT-23(Co), SNU-70, UCM-1, MOF-177, NH ２ -MOF-177, MOF-5, MFU-41-Li, NU-1102, NU-1101, IRMOF-20, MIL-101, MSC-30, AX21, MSC-20, MIL-101-NH ２ , NU-1500-Al, CYCU-3-Al, UCM-4, NU-1000, Norit ROW, mBr-MOF-5, MFU-41, UiO-66, UiO-68-Ant, UiO-67, mMMe-MOF-5, HKUST-1, NU-125, PCN-250, Zn ２ (bdc) ２ (dabco), rht-MOF-7, Ni ２ (m-dobdc), ｍｏｎｏ The method for producing a hydrogen adsorption material according to claim 6 or 7, which is at least one of HKUST-1, Ni-MOF-74, ZIF-8, and Cu-MOF-74.

9. A method for producing a hydrogen adsorption material according to claim 6 or 7, wherein the second metal is Li.

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