Method for regenerating metal-organic structures

Abstract

This provides a new method for regenerating metal-organic structures. [Solution] The present invention provides a method for regenerating a metal-organic structure, which includes performing a degradation treatment to degrade the metal-organic structure, and applying energy to the metal-organic structure in the presence of an organic solvent or the vapor of an organic solvent after the degradation treatment.

Description

Technical Field

[0001] The present invention relates to a method for regenerating a metal-organic framework.

Background Art

[0002] A metal-organic framework (MOF) has a structure capable of incorporating a low-molecular compound therein and is sometimes called a porous coordination polymer (PCP). Due to the above structure, metal-organic frameworks are used in various applications such as catalysts, pharmaceuticals, and cosmetics. In recent years, the use of metal-organic frameworks as gas adsorbents has also been studied (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A metal-organic framework usually includes a core containing metal ions and the like, and an organic ligand coordinated to the core. When a metal-organic framework is repeatedly used for a specific application (for example, as an adsorbent), the organic ligand may come off from the core, etc., causing a change in its structure and a tendency for the amount of low-molecular compound that can be incorporated therein (adsorption amount) to decrease. Considering the high production cost of metal-organic frameworks, it is desirable to regenerate and reuse the metal-organic framework with a decreased adsorption amount.

[0005] Therefore, an object of the present invention is to provide a new method for regenerating a metal-organic framework.

Means for Solving the Problems

[0006] The present invention is Performing a degradation treatment that degrades metal-organic structures, After the degradation treatment, energy is applied to the metal-organic structure in the presence of an organic solvent or the vapor of the organic solvent. The present invention provides a method for regenerating metal-organic structures, including [specific components]. [Effects of the Invention]

[0007] According to the present invention, a novel method for regenerating metal-organic structures can be provided. [Brief explanation of the drawing]

[0008] [Figure 1] This graph shows the X-ray diffraction patterns of the initial metal-organic structure (HKUST-1), the metal-organic structure subjected to degradation treatment under condition 2, and the metal-organic structure subjected to regeneration treatment in Example A6. [Figure 2] This graph shows the X-ray diffraction patterns of the initial metal-organic structure (Mg2(dobpdc)), the metal-organic structure subjected to degradation treatment under condition 2, and the metal-organic structure subjected to regeneration treatment in Example D1. [Figure 3] This graph shows the X-ray diffraction patterns of the initial metal-organic structure (UiO-67), the metal-organic structure subjected to degradation treatment under condition 2, and the metal-organic structure subjected to regeneration treatment in Example F1. [Modes for carrying out the invention]

[0009] A method for regenerating a metal-organic structure according to a first aspect of the present invention is: Performing a degradation treatment that degrades metal-organic structures, After the degradation treatment, energy is applied to the metal-organic structure in the presence of an organic solvent or the vapor of the organic solvent. Includes.

[0010] In a second embodiment of the present invention, for example, in the regeneration method according to the first embodiment, the energy includes at least one selected from the group consisting of mechanical energy and thermal energy.

[0011] In a third aspect of the present invention, for example, in a regeneration method according to the first or second aspect, the degradation treatment includes a contact treatment in which the metal-organic structure is brought into contact with at least one selected from the group consisting of water, acid, and base.

[0012] In a fourth embodiment of the present invention, for example, in the regeneration method according to the third embodiment, the metal-organic structure is heated during the contact treatment.

[0013] In a fifth embodiment of the present invention, for example, in the regeneration method according to the fourth embodiment, the heating temperature of the metal-organic structure during the contact treatment is 50°C or higher.

[0014] In a sixth aspect of the present invention, for example, in a regeneration method according to any one of the third to fifth aspects, the contact treatment is performed by arranging the metal-organic structure in an environment with a humidity of 50% RH or higher.

[0015] In a seventh aspect of the present invention, for example, in a regeneration method according to any one of the first to sixth aspects, the BET specific surface area of ​​the metal-organic structure is reduced by performing the degradation treatment.

[0016] In the eighth aspect of the present invention, for example, in the regeneration method according to any one of the first to seventh aspects, the BET specific surface area of ​​the metal-organic structure is increased by applying the energy.

[0017] In the ninth embodiment of the present invention, for example, in the regeneration method according to any one of the first to eighth embodiments, the energy is applied to the metal-organic structure by a pulverization process using a ball mill.

[0018] In the tenth embodiment of the present invention, for example, in the regeneration method according to the ninth embodiment, the time of the crushing process is 1 minute or more.

[0019] In the 11th embodiment of the present invention, for example, in the regeneration method according to any one of the first to tenth embodiments, the organic solvent includes at least one selected from the group consisting of alcohol compounds and amide compounds.

[0020] In a twelfth aspect of the present invention, for example, in the regeneration method according to the eleventh aspect, the alcohol compound includes at least one selected from the group consisting of methanol and ethanol.

[0021] In a thirteenth aspect of the present invention, for example, in a regeneration method according to any one of the first to twelfth aspects, the energy is applied to the metal-organic structure in the presence of a solvent containing the organic solvent and water.

[0022] In a fourteenth aspect of the present invention, for example, in a regeneration method according to any one of the first to thirteenth aspects, the metal-organic structure includes a core comprising at least one selected from the group consisting of metal ions, metal clusters, and metal oxide clusters, and an organic ligand.

[0023] In a 15th embodiment of the present invention, for example, in the regeneration method according to the 14th embodiment, the core includes at least one selected from the group consisting of Cu, Mg, Co, and Zr.

[0024] In a sixteenth aspect of the present invention, for example, in the regeneration method according to the fourteenth or fifteenth aspect, the organic ligand includes a ring structure.

[0025] The details of the present invention will be described below, but the following description is not intended to limit the present invention to any particular embodiment.

[0026] The method for regenerating a metal-organic structure according to this embodiment includes performing a degradation treatment to degrade the metal-organic structure (Step I), and, after the degradation treatment, applying energy to the metal-organic structure in the presence of an organic solvent or the vapor of an organic solvent (Step II).

[0027] According to the regeneration method of this embodiment, by deliberately performing a degradation treatment before the regeneration treatment, it is possible to efficiently recover the amount of low-molecular-weight compounds that can be incorporated into the metal-organic structure (adsorption amount). In this specification, "degradation treatment" refers to a treatment that actively degrades the metal-organic structure by applying external stimuli to it, and does not include natural degradation due to storage of the metal-organic structure or use of the metal-organic structure for a specific application (e.g., as an adsorbent).

[0028] (Metal-organic structure) The metal-organic structure may include a core containing at least one selected from the group consisting of metal ions, metal clusters, and metal oxide clusters, and an organic ligand, preferably with the organic ligand coordinated to the core. The metal-organic structure preferably has a structure (porous structure) that can incorporate low molecular weight compounds inside. However, if the metal-organic structure deteriorates, its structure may change, such as when the organic ligand detaches from the core, and the above-mentioned porous structure may be lost. In this specification, even if the porous structure has been lost, it will be referred to as a "metal-organic structure" for convenience.

[0029] Examples of metals to be included in the core include alkali metals (Group 1 of the periodic table), alkaline earth metals (Group 2 of the periodic table), and transition metals (Groups 3 to 12 of the periodic table), with Cu, Zn, Pd, Mg, Al, Fe, Cr, Zr, Ni, Co, and Ca being preferred. The core may contain at least one selected from the group consisting of Cu, Al, Mg, Co, and Zr, or it may contain at least one selected from the group consisting of Cu, Mg, Co, and Zr. The core preferably contains Cu. The core may contain a single type of metal or multiple types of metals.

[0030] In the core, the metal ions are Cu 2+ Zn 2+ Mg 2+ , Al 3+ Co 2+Examples include Zn oxide clusters and Zr oxide clusters.

[0031] Organic ligands typically contain functional groups for coordinating to the core. The number of these functional groups in an organic ligand may be, for example, one or more, two or more, three or more, or even four or more. It is preferable that the organic ligand is a polydentate ligand containing two or more functional groups for coordinating to the core. The upper limit of the number of these functional groups is not particularly limited, but is, for example, 10 or less. Examples of these functional groups include carboxyl groups, hydroxyl groups, amino groups, sulfonic acid groups, and phosphate groups. These functional groups usually coordinate to the core in anionic form. The organic ligand may further contain other functional groups besides those for coordinating to the core.

[0032] The number of carbon atoms in an organic ligand is 1 or more, preferably 2 or more. The number of carbon atoms in an organic ligand may be 4 to 20. The organic ligand may contain a ring structure. The number of ring structures contained in the organic ligand may be, for example, 1 or more, 2 or more, or even 3 or more. The upper limit of the number of ring structures is, for example, 5 or less. The organic ligand preferably contains an aromatic ring as a ring structure. The aromatic ring may consist only of carbon atoms, or it may be a heteroatom-containing aromatic ring. The aromatic ring may be monocyclic or polycyclic. The number of carbon atoms in the aromatic ring is not particularly limited, for example, 4 to 14. Specific examples of aromatic rings include benzene rings and imidazole rings. In the organic ligand, the functional group for coordinating to the core may be a substituent of a ring structure.

[0033] Examples of organic ligands include carboxylic acid compounds such as citric acid, malic acid, terephthalic acid, isophthalic acid, trimesic acid (1,3,5-benzenetricarboxylic acid), 4,4'-biphenyldicarboxylic acid, 4,4'-dihydroxy-3,3'-biphenyldicarboxylic acid, and their derivatives; and heterocyclic compounds such as bipyridine, imidazole, adenine, and their derivatives (such as 2-methylimidazole).

[0034] Specific examples of metal-organic structures include HKUST-1, DUT-5, Mg2(dobpdc), ZIF-67, and UiO-67. The metal-organic structure preferably contains at least one selected from the group consisting of HKUST-1, Mg2(dobpdc), ZIF-67, and UiO-67, and more preferably contains HKUST-1.

[0035] Metal-organic structures can be synthesized using a core material and an organic ligand. Metal salts can be used as the core material. These metal salts may be organic or inorganic. Examples of metal salts include hydroxides, carbonates, acetates, sulfates, nitrates, and chlorides. The metal salts may also be in the form of secondary building units (SBUs).

[0036] The object to which the regeneration method of this embodiment is applied is preferably, in detail, particles containing a metal-organic structure. These particles may contain the metal-organic structure as the main component, or may be composed substantially only of the metal-organic structure. In this specification, "main component" means the component that is present in the largest amount by weight in the particle. The shape of the particles includes spherical, ellipsoidal, flaky, fibrous, and the like. The object to which the regeneration process of this embodiment is performed may be a molded body or sheet containing the metal-organic structure. A "molded body" is obtained by aggregating particles containing the metal-organic structure with physical force to give it a certain shape, and examples include pellets.

[0037] The metal-organic structures that undergo the regeneration method of this embodiment are typically those that have been used for specific applications. Examples of such specific applications include their use as adsorbents. When a metal-organic structure is used as an adsorbent, the substances it adsorbs include, for example, acidic gases such as carbon dioxide, hydrogen sulfide, carbonyl sulfide, sulfur oxides (SOx), hydrogen cyanide, and nitrogen oxides (NOx), with carbon dioxide being preferred. The metal-organic structures regenerated by the regeneration method of this embodiment can be reused for specific applications.

[0038] (Process I) As described above, in step I, the metal-organic structure is subjected to degradation treatment. Specifically, the metal-organic structure is degraded by applying external stimuli to it. In the degradation treatment, stimuli applied to the metal-organic structure include thermal stimulation; light stimulation; and stimuli by contact with substances such as water, acids, and bases. The degradation treatment preferably includes a contact treatment in which the metal-organic structure is brought into contact with at least one selected from the group consisting of water, acids, and bases. In the contact treatment, it is particularly preferable to bring the metal-organic structure into contact with water.

[0039] In the above contact treatment, the water brought into contact with the metal-organic structure may be a gas (water vapor) or a liquid. In particular, it is preferable to carry out the contact treatment by placing the metal-organic structure in a humidified environment. The humidity of the above environment may be, for example, 20% RH or higher, and may be 30% RH or higher, 50% RH or higher, 60% RH or higher, 70% RH or higher, or even 80% RH or higher. The upper limit of this humidity is not particularly limited, but for example, 95% RH or lower. It is preferable to carry out the contact treatment by placing the metal-organic structure in an environment of 50% RH or higher.

[0040] The contact processing time may be, for example, 1 minute or more, 10 minutes or more, 1 hour or more, 5 hours or more, or even 10 hours or more. The upper limit of the contact processing time is not particularly limited and may be, for example, 100 hours or less, or 50 hours or less.

[0041] From the viewpoint of sufficiently degrading the metal-organic structure, it is preferable to heat the metal-organic structure during the above contact treatment. In this case, the heating temperature of the metal-organic structure may be, for example, 50°C or higher, 60°C or higher, 70°C or higher, or even 80°C or higher. The upper limit of the heating temperature is not particularly limited and may be, for example, 200°C or lower, 150°C or lower, 120°C or lower, or even 100°C or lower.

[0042] In Process I, the metal-organic framework deteriorates due to the deterioration treatment. Specifically, the structure of the metal-organic framework changes, and the amount of low-molecular-weight compound that can be incorporated therein (adsorption amount) decreases. The adsorption amount by the metal-organic framework tends to correlate with the BET specific surface area. Therefore, the degree of deterioration of the metal-organic framework can be evaluated based on the BET specific surface area. In the present embodiment, it is preferable to lower the BET specific surface area of the metal-organic framework by performing the deterioration treatment. In this specification, the BET specific surface area means the BET specific surface area by nitrogen gas adsorption measured in accordance with the provisions of ISO 9277:2010.

[0043] As an example, the ratio A2 / A1 of the BET specific surface area A2 (m 2 / g) of the metal-organic framework after the deterioration treatment to the BET specific surface area A1 (m 2 / g) of the metal-organic framework before the deterioration treatment is not particularly limited, and for example, it may be 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, 3% or less, and even 1% or less. The lower the ratio A2 / A1, the more likely it is that the adsorption amount by the metal-organic framework can be efficiently recovered by the regeneration treatment. The lower limit of the ratio A2 / A1 is not particularly limited, and for example, it may be 0.01% or more, 0.1% or more.

[0044] The BET specific surface area A1 of the metal-organic framework before the deterioration treatment is, for example, 1000 m 2 / g or more, 1300 m 2 / g or more, 1500 m 2 / g or more, 1700 m 2 / g or more, and even 2000 m 2 / g or more. The upper limit of the BET specific surface area A1 is, for example, 10000 m 2 / g or less, and may be 5000 m 2 / g or less.

[0045] The BET specific surface area A2 of the metal-organic framework after the deterioration treatment is not particularly limited as long as it is smaller than the BET specific surface area A1, and for example, it is less than 1000 m 2 / g, less than 900 m 2 / g or less, 800m 2 / g or less, 700m 2 / g or less, 600m 2 / g or less, 500m 2 / g or less, 400m 2 / g or less, 300m 2 / g or less, 200m 2 / g or less, 100m 2 / g or less, 80m 2 / g or less, 50m 2 / g or less, 30m 2 Less than / g, and even 10m 2 It may be less than / g. The lower limit of the BET specific surface area A2 is, for example, 0.1m². 2 / g or more, 1m 2 It may be 1000m or more. Depending on the value of BET specific surface area A1, BET specific surface area A2 may be 1000m 2 It may be more than / g.

[0046] The regeneration method of this embodiment is typically performed on metal-organic structures that have naturally deteriorated due to use in a specific application. Therefore, the BET specific surface area A1 of the metal-organic structure before deterioration treatment is typically smaller than the BET specific surface area A0 of the metal-organic structure initially (e.g., immediately after manufacturing). BET specific surface area A0 (m 2 BET specific surface area A1(m²) for / g) 2 The ratio A1 / A0 ( / g) can be appropriately set depending on the application of the metal-organic structure, for example, 50% to 90%, or 70% to 80%. Also, the BET specific surface area A0 (m²) 2 BET specific surface area A2(m²) of the metal-organic structure after degradation treatment relative to / g) 2 The ratio A2 / A0 (per g) can be, for example, 0.01% to 70%, or it may be 0.1% to 50%.

[0047] The BET specific surface area A0 of early metal-organic structures is not particularly limited, for example, 1000 m² 2 / g or more, 1300m 2 / g or more, 1500m 2 / g or more, 1700m 2 / g or more, and even 2000m 2It may be greater than or equal to / g. The upper limit of the BET specific surface area A0 is, for example, 10,000 m². 2 It is less than / g and 5000m 2 It may be less than / g.

[0048] (Process II) As described above, in step II, energy is applied to the metal-organic structure in the presence of an organic solvent or organic solvent vapor after the degradation treatment (step I). This treatment can regenerate the metal-organic structure. In this specification, the above treatment may be referred to as the "regeneration treatment".

[0049] In the regeneration process, it is preferable to apply energy to the metal-organic structure in the presence of an organic solvent (more specifically, a solvent containing an organic solvent), and it is particularly preferable to apply energy to the metal-organic structure in the presence of a solvent containing an organic solvent and water. The organic solvent is preferably miscible with water. The organic solvent is preferably composed of at least one selected from the group consisting of alcohol compounds and amide compounds.

[0050] The alcohol compound is preferably a lower alcohol compound with 5 or fewer carbon atoms, such as methanol, ethanol, propanol, butanol, and pentanol. The alcohol compound preferably contains at least one selected from the group consisting of methanol and ethanol, and more preferably contains methanol.

[0051] As amide compounds, those with 5 or fewer carbon atoms are preferred, such as N,N-dimethylformamide.

[0052] In a solvent containing an organic solvent, the content of the organic solvent may be, for example, 40 vol% or more, and may be 50 vol% or more, 60 vol% or more, 70 vol% or more, 80 vol% or more, 90 vol% or more, or even 95 vol% or more. The solvent may consist substantially of only an organic solvent. However, the solvent may also contain water along with the organic solvent, and the content of the organic solvent may be 99 vol% or less, 90 vol% or less, 80 vol% or less, 70 vol% or less, 60 vol% or less, or even 50 vol% or less. In this specification, "content" means the volume-based content at normal temperature and pressure (25°C, 101.325 kPa).

[0053] As mentioned above, the solvent preferably contains water along with an organic solvent (especially an alcohol compound). In this case, the metal-organic structure tends to be regenerated more efficiently. The water content in the solvent is not particularly limited, for example, 1 vol% to 50 vol%. The solvent may also be substantially water-free.

[0054] The amount of solvent used is not particularly limited, and may be, for example, 0.1 mL to 100 mL per 1 g of metal-organic structure, or 1 mL to 10 mL. During the regeneration process, the metal-organic structure may not be dissolved in the solvent and may form a slurry. The pH of the solvent in contact with the metal-organic structure is preferably appropriately adjusted according to the type of metal-organic structure.

[0055] In the regeneration process, the energy applied to the metal-organic structure preferably includes at least one selected from the group consisting of mechanical energy and thermal energy, and is particularly preferably mechanical energy. In this specification, the process of applying mechanical energy to a metal-organic structure may be referred to as "mechanochemical treatment".

[0056] The method of applying mechanical energy to a metal-organic structure is not particularly limited. For example, mechanical energy can be applied to a metal-organic structure by stress such as impact force, shear force, friction force, or compressive force. In this embodiment, it is preferable to apply mechanical energy to the metal-organic structure by grinding. Examples of grinding methods include ball mills, bead mills, vibratory mills, turbo mills, mechanofusion mills, disc mills, and jet mills. The grinding may also be performed using a mixer. In this embodiment, it is preferable to apply energy (mechanical energy) to the metal-organic structure by grinding using a ball mill (especially a planetary ball mill).

[0057] When grinding a metal-organic structure, the grinding conditions are not particularly limited. For example, when using a ball mill, the rotation speed may be, for example, 10 rpm to 1000 rpm, or 100 rpm to 500 rpm. The grinding time may be, for example, 1 minute or more, 10 minutes or more, 30 minutes or more, or even 1 hour or more. The upper limit of the grinding time is not particularly limited and may be, for example, 24 hours or less, 15 hours or less, 10 hours or less, or even 5 hours or less. The internal atmosphere of the grinding apparatus may consist of air, or it may consist only of inert gases such as nitrogen or argon. When using a ball mill, frictional heat tends to be generated during the grinding process. In this case, the metal-organic structure may be cooled during the grinding process.

[0058] The method for applying thermal energy to a metal-organic structure is not particularly limited. For example, thermal energy can be applied to a metal-organic structure by bringing it into contact with a heated organic solvent or its vapor. Thermal energy may also be applied to a metal-organic structure by heating it in the presence of an organic solvent or its vapor. Heating of the metal-organic structure may be carried out using a heating device such as a heater, or by using a heat transfer medium (e.g., a high-temperature gas).

[0059] In step II, the metal-organic structure is regenerated through a regeneration process. Specifically, the structure of the metal-organic structure changes, and the amount of low-molecular-weight compounds that can be incorporated into it (adsorption amount) increases. As described above, the amount of adsorption by the metal-organic structure tends to correlate with the BET specific surface area. Therefore, the degree of regeneration of the metal-organic structure can be evaluated based on the BET specific surface area. In this embodiment, it is preferable to increase the BET specific surface area of ​​the metal-organic structure by performing a regeneration process (specifically, an operation to apply energy).

[0060] As an example, the BET specific surface area A2(m²) of a metal-organic structure after degradation treatment. 2 BET specific surface area A3(m²) of the regenerated metal-organic structure relative to / g 2 The ratio A3 / A2 of ( / g) is not particularly limited and may be, for example, 105% or more, 110% or more, 150% or more, 200% or more, 300% or more, 500% or more, 1000% or more, 3000% or more, 5000% or more, 100000% or more, 15000% or more, 20000% or more, and even 25000% or more. The upper limit of the ratio A3 / A2 is not particularly limited and may be, for example, 100000% or less, and 50000% or less.

[0061] Furthermore, the BET specific surface area A0(m²) of the early metal-organic structures 2 BET specific surface area A3(m²) of the regenerated metal-organic structure relative to / g 2 The ratio A3 / A0 ( / g) can be, for example, 5% to 110%, 10% to 100%, or even 50% to 99%. The BET specific surface area A1 (m²) of the metal-organic structure before degradation treatment. 2 BET specific surface area A3(m²) of the regenerated metal-organic structure relative to / g 2 The ratio A3 / A1 (per g) is preferably greater than 100%, for example, 105% to 200%. However, in some cases, the ratio A3 / A1 may be less than 100%.

[0062] BET specific surface area A3(m²) of the metal-organic structure after regeneration treatment 2 ( / g) is, for example, 100m 2It is 200m or more / g 2 / g or more, 300m 2 / g or more, 500m 2 / g or more, 700m 2 / g or more, 900m 2 / g or more, 1000m 2 / g or more, 1200m 2 / g or more, 1300m 2 / g or more, 1500m 2 / g or more, 1700m 2 / g or more, and even 1800m 2 It may be greater than or equal to / g. The upper limit of the BET specific surface area A3 is, for example, 10,000 m². 2 It is less than / g and 5000m 2 It may be less than / g.

[0063] According to the inventors' studies, the regeneration method of this embodiment tends to reduce the crystallinity of the metal-organic structure. Metal-organic structures with reduced crystallinity are suitable for producing films in which the occurrence of defects such as cracks is suppressed. The crystallinity of the metal-organic structure can be evaluated based on the X-ray diffraction pattern obtained by X-ray diffraction (XRD) using Cu-Kα rays. More specifically, the crystallinity of the metal-organic structure can be evaluated by the full width at half maximum of the diffraction peak with the highest intensity in the X-ray diffraction pattern.

[0064] As an example, the ratio H1 / H0 of the full width at half maximum H1 (°) of the diffraction peak with the highest intensity in the X-ray diffraction pattern of the regenerated metal-organic framework to the full width at half maximum H0 (°) of the diffraction peak with the highest intensity in the X-ray diffraction pattern of the initial metal-organic framework is, for example, 103% or more, and may be 105% or more, or even 108% or more. When the ratio H1 / H0 exceeds 100%, it can be determined that the crystallinity of the metal-organic framework has decreased by the regeneration method of the present embodiment. The upper limit of the ratio H1 / H0 is not particularly limited, and may be, for example, 250% or less, 200% or less, 150% or less, 130% or less, or even 120% or less. Note that the ratio H1 / H0 may be 100% or less in some cases. Each of the above full widths at half maximum H0 and H1 is not particularly limited, and may be, for example, from 0.30° to 1.00°, or may be from 0.30° to 0.50°.

Example

[0065] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

[0066] <HKUST-1 (particles)> [Degradation treatment (Condition 1)] First, particles composed of the metal-organic framework HKUST-1 (manufactured by Atomis, AP0002) were prepared. Next, the above particles were set in a thermo-hygrostat set at a temperature of 65°C and a humidity of 25%RH, and a contact treatment was performed for 24 hours to bring the metal-organic framework into contact with water vapor. Thereby, the degradation treatment under Condition 1 was performed.

[0067] [Degradation treatment (Condition 2)] First, particles composed of the metal-organic framework HKUST-1 (manufactured by Atomis, AP0002) were prepared. Next, the above particles were set in a thermo-hygrostat set at a temperature of 85°C and a humidity of 85%RH, and a contact treatment was performed for 24 hours to bring the metal-organic framework into contact with water vapor. Thereby, the degradation treatment under Condition 2 was performed.

[0068] [BET specific surface area] The BET specific surface area was measured for both the initial metal-organic structure and the metal-organic structure after degradation treatment using the following method. First, the metal-organic structure was pre-treated by heating and drying at 150°C for 6 hours under a vacuum atmosphere. Next, the metal-organic structure was placed in a gas adsorption measurement device (BELSORP MINI X, manufactured by Microtrac Bel), and nitrogen gas at a temperature of 77K (-196°C) was introduced into the device. The amount of gas adsorbed by the metal-organic structure was measured while changing the pressure inside the device. By plotting the relationship between the relative pressure P / P0 (P0: saturated vapor pressure of N2) and the amount of gas adsorbed by the metal-organic structure on a graph, an adsorption isotherm for nitrogen gas was created. The specific surface area was determined using the BET method with this adsorption isotherm.

[0069] [Table 1]

[0070] (Example A1) A metal-organic structure that had undergone degradation treatment under Condition 1, along with ethanol (EtOH) as a solvent, was placed in a pulverizer (ball mill type pulverizer, LP-4 manufactured by Ito Seisakusho) equipped with zirconia balls, and the metal-organic structure was subjected to pulverization. The amount of solvent used was 2 mL per 1 g of metal-organic structure. The pulverization process was carried out for 1 hour at a rotation speed of 250 rpm. Mechanical energy was applied to the metal-organic structure through the pulverization process, resulting in its regeneration.

[0071] (Examples A2-A20) Except for the changes in the degradation treatment conditions, the solvent used, and the grinding treatment time shown in Table 2, the regeneration treatment for Examples A2 to A20 was carried out in the same manner as for Example A1. In Examples A5 to A8, a mixed solvent of ethanol (EtOH) and water (H2O) (volume ratio 3:2) was used as the solvent. In Examples A15 to A20, a mixed solvent of methanol (MeOH) and water (H2O) (volume ratio 3:2) was used as the solvent.

[0072] [BET specific surface area] The BET specific surface area was measured for the regenerated metal-organic structures using the method described above. The results are shown in Table 2.

[0073] [Table 2]

[0074] As can be seen from Table 2, in Examples A1 to A20, applying energy to the metal-organic structure in the presence of an organic solvent (EtOH or MeOH) increased the BET specific surface area compared to the metal-organic structure after degradation treatment, indicating that the metal-organic structure was regenerated. Furthermore, as can be seen from Table 2, given the same regeneration treatment conditions, using a metal-organic structure with a more reduced BET specific surface area due to degradation treatment under condition 2 (temperature 85°C, humidity 85%RH) tended to result in a greater increase in the BET specific surface area after regeneration treatment.

[0075] In Examples A1 to A20, the BET specific surface area A0 (1789 m²) of the initial metal-organic structure was... 2 Since it is based on ( / g), the BET specific surface area A3 (m²) of the metal-organic structure after regeneration treatment is relative to the BET specific surface area A0. 2 Some materials have a ratio of A3 / A0 ( / g) that is less than 100%. When actually performing the regeneration method of this embodiment, it is preferable to use a metal-organic structure that has naturally deteriorated after being used for a specific application, and it is desirable that the BET specific surface area A1 of the metal-organic structure before deterioration treatment is less than the BET specific surface area A3 of the metal-organic structure after regeneration treatment. This is also true for the other embodiments described later.

[0076] [X-ray diffraction (XRD) measurement] XRD measurements were performed on the initial metal-organic structure (HKUST-1 (particles)), the metal-organic structure subjected to degradation treatment under condition 2, and the metal-organic structure subjected to regeneration treatment in Example A6. The conditions for the XRD measurements are as follows. • Measurement conditions Measurement device: SmartLab, manufactured by Rigaku Corporation. Sample: Introduce the powdered sample into the sample holder. X-ray source:CuKα X-ray voltage: 40kV X-ray current: 50mA Step width: 0.1° Scan speed: 20° / min

[0077] The data obtained from XRD measurements were analyzed using XRD analysis software (DIFFRAC.SUITE, Bruker). First, an X-ray diffraction pattern (Figure 1) was created using the XRD analysis software, and the diffraction peak with the highest intensity in the X-ray diffraction pattern was identified. In HKUST-1, the diffraction peak that appeared around 11.6° had the highest intensity. Next, a linear baseline was created in the range of 10.4° to 12.5°, and the full width at half maximum (FWHM) of the above diffraction peak was calculated. As a result, the FWHM H0 of the diffraction peak with the highest intensity in the X-ray diffraction pattern of the initial metal-organic structure was 0.348°, and the FWHM H1 of the diffraction peak with the highest intensity in the X-ray diffraction pattern of the metal-organic structure after regeneration treatment was 0.379°, with a ratio H1 / H0 of 108.9%. From these results, it can be seen that in Example A6, the crystallinity of the metal-organic structure decreased by performing the regeneration method of this embodiment.

[0078] <HKUST-1(ペレット)> [Degradation treatment (condition 2)] First, pellets composed of the metal-organic structure HKUST-1 (Atomis, AP0002) were prepared. Next, the pellets were placed in a constant temperature and humidity chamber set to 85°C and 85%RH, and a contact treatment was performed for 24 hours, bringing the metal-organic structure into contact with water vapor. This performed the degradation treatment described in Condition 2.

[0079] [BET specific surface area] The BET specific surface area was measured for the initial metal-organic structure and the metal-organic structure after degradation treatment using the method described above. The results are shown in Table 3.

[0080] [Table 3]

[0081] (Example B1) A metal-organic structure subjected to degradation treatment under condition 2 and methanol (MeOH) as a solvent were placed in a pulverizer (ball mill type pulverizer, LP-4 manufactured by Ito Seisakusho) equipped with zirconia balls, and the metal-organic structure was subjected to pulverization. The amount of solvent used was 2 mL per 1 g of metal-organic structure. The pulverization process was carried out for 1 hour at a rotation speed of 250 rpm. Mechanical energy was applied to the metal-organic structure through the pulverization process, and the metal-organic structure was regenerated.

[0082] (Examples B2-B3) Except for changing the grinding time as shown in Table 4, the regeneration process for Examples B2 and B3 was carried out in the same manner as in Example B1.

[0083] [BET specific surface area] The BET specific surface area was measured for the regenerated metal-organic structures using the method described above. The results are shown in Table 4.

[0084] [Table 4]

[0085] As can be seen from Table 4, in Examples B1 to B3, applying energy to the metal-organic structure in the presence of an organic solvent (MeOH) increased the BET specific surface area compared to the metal-organic structure after degradation treatment, and the metal-organic structure was regenerated.

[0086] <dut-5> [Degradation treatment (condition 2)] First, particles composed of the metal-organic structure DUT-5 (Atomis, AP0012) were prepared. Next, these particles were placed in a constant temperature and humidity chamber set to 85°C and 85%RH, and a contact treatment was performed for 24 hours, bringing the metal-organic structure into contact with water vapor. This performed the degradation treatment described in Condition 2.

[0087] [BET specific surface area] The BET specific surface area was measured for the initial metal-organic structure and the metal-organic structure after degradation treatment using the method described above. The results are shown in Table 5.

[0088] [Table 5]

[0089] (Example C1) A metal-organic structure subjected to degradation treatment under condition 2, along with N,N-dimethylformamide (DMF) as a solvent, was placed in a pulverizer (ball mill type pulverizer, LP-4 manufactured by Ito Seisakusho) equipped with zirconia balls, and the metal-organic structure was subjected to pulverization. The amount of solvent used was 2 mL per 1 g of metal-organic structure. The pulverization process was carried out for 1 hour at a rotation speed of 250 rpm. Mechanical energy was applied to the metal-organic structure through the pulverization process, resulting in its regeneration.

[0090] (Examples C2-C3) Except for changing the grinding time as shown in Table 6, the regeneration process for Examples C2 and C3 was carried out in the same manner as in Example C1.

[0091] [BET specific surface area] The BET specific surface area was measured for the regenerated metal-organic structures using the method described above. The results are shown in Table 6.

[0092] [Table 6]

[0093] As can be seen from Table 6, in Examples C1 to C3, applying energy to the metal-organic structure in the presence of an organic solvent (DMF) increased the BET specific surface area compared to the metal-organic structure after degradation treatment, and the metal-organic structure was regenerated.

[0094] <Mg2(dobpdc)> [Degradation treatment (condition 2)] First, particles composed of the metal-organic structure Mg2(dobpdc) (Atomis, AP0065) were prepared. Next, these particles were placed in a constant temperature and humidity chamber set to 85°C and 85%RH, and a contact treatment was performed for 24 hours, bringing the metal-organic structure into contact with water vapor. This performed the degradation treatment described in Condition 2.

[0095] [BET specific surface area] The BET specific surface area was measured for the initial metal-organic structure and the metal-organic structure after degradation treatment using the method described above. The results are shown in Table 7.

[0096] [Table 7]

[0097] (Example D1) A metal-organic structure subjected to degradation treatment under condition 2, along with N,N-dimethylformamide (DMF) as a solvent, was placed in a pulverizer (ball mill type pulverizer, LP-4 manufactured by Ito Seisakusho) equipped with zirconia balls, and the metal-organic structure was subjected to pulverization. The amount of solvent used was 2 mL per 1 g of metal-organic structure. The pulverization process was carried out for 1 hour at a rotation speed of 250 rpm. Mechanical energy was applied to the metal-organic structure through the pulverization process, resulting in its regeneration.

[0098] (Examples D2-D3) Except for changing the grinding time as shown in Table 8, the regeneration process for Examples D2 and D3 was carried out in the same manner as in Example D1.

[0099] [BET specific surface area] The BET specific surface area was measured for the regenerated metal-organic structures using the method described above. The results are shown in Table 8.

[0100] [Table 8]

[0101] As can be seen from Table 8, in Examples D1 to D3, applying energy to the metal-organic structure in the presence of an organic solvent (DMF) increased the BET specific surface area compared to the metal-organic structure after degradation treatment, and the metal-organic structure was regenerated.

[0102] [X-ray diffraction (XRD) measurement] XRD measurements were performed on the initial metal-organic structure (Mg2(dobpdc)), the metal-organic structure subjected to degradation treatment under condition 2, and the metal-organic structure subjected to regeneration treatment in Example D1. The XRD measurement conditions were the same as those described above for HKUST-1.

[0103] The data obtained from XRD measurements were analyzed using XRD analysis software (DIFFRAC.SUITE, Bruker). First, an X-ray diffraction pattern (Figure 2) was created using the XRD analysis software, and the diffraction peak with the highest intensity in the X-ray diffraction pattern was identified. In Mg2 (dobpdc), the diffraction peak that appeared around 4.7° had the highest intensity. Next, a linear baseline was created in the range of 3.6° to 5.8°, and the full width at half maximum (FWHM) of the above diffraction peak was calculated. As a result, the FWHM H0 of the diffraction peak with the highest intensity in the X-ray diffraction pattern of the initial metal-organic structure was 0.406°, and the FWHM H1 of the diffraction peak with the highest intensity in the X-ray diffraction pattern of the metal-organic structure after regeneration treatment was 0.445°, with a ratio H1 / H0 of 109.6%. From these results, it can be seen that in Example D1, the crystallinity of the metal-organic structure decreased by performing the regeneration method of this embodiment. Furthermore, the full width at half maximum (FWHM) of the diffraction peak with the highest intensity in the X-ray diffraction pattern of the metal-organic structure after degradation treatment was 0.415°.

[0104] <zif-67> [Degradation treatment (condition 2)] First, particles composed of the metal-organic structure ZIF-67 (Atomis, AP0015) were prepared. Next, these particles were placed in a constant temperature and humidity chamber set to 85°C and 85%RH, and a contact treatment was performed for 24 hours, bringing the metal-organic structure into contact with water vapor. This performed the degradation treatment described in Condition 2.

[0105] [BET specific surface area] The BET specific surface area was measured for the initial metal-organic structure and the metal-organic structure after degradation treatment using the method described above. The results are shown in Table 9.

[0106] [Table 9]

[0107] (Example E1) A metal-organic structure subjected to degradation treatment under condition 2 and methanol (MeOH) as a solvent were placed in a pulverizer (ball mill type pulverizer, LP-4 manufactured by Ito Seisakusho) equipped with zirconia balls, and the metal-organic structure was subjected to pulverization. The amount of solvent used was 2 mL per 1 g of metal-organic structure. The pulverization process was carried out for 1 hour at a rotation speed of 250 rpm. Mechanical energy was applied to the metal-organic structure through the pulverization process, and the metal-organic structure was regenerated.

[0108] (Examples E2-E3) Except for changing the grinding time as shown in Table 10, the regeneration process for Examples E2 and E3 was carried out in the same manner as in Example E1.

[0109] [BET specific surface area] The BET specific surface area was measured for the regenerated metal-organic structures using the method described above. The results are shown in Table 10.

[0110] [Table 10]

[0111] As can be seen from Table 10, in Examples E1 to E3, applying energy to the metal-organic structure in the presence of an organic solvent (MeOH) increased the BET specific surface area compared to the metal-organic structure after degradation treatment, and the metal-organic structure was regenerated.

[0112] <uio-67> [Degradation treatment (condition 2)] First, particles composed of UiO-67 (Atomis, AP0023) were prepared as the metal-organic structure. Next, the particles were placed in a constant temperature and humidity chamber set to 85°C and 85%RH, and a contact treatment was performed for 24 hours, bringing the metal-organic structure into contact with water vapor. This performed the degradation treatment described in Condition 2.

[0113] [BET specific surface area] The BET specific surface area was measured for the initial metal-organic structure and the metal-organic structure after degradation treatment using the method described above. The results are shown in Table 11.

[0114] [Table 11]

[0115] (Example F1) A metal-organic structure subjected to degradation treatment under condition 2, along with N,N-dimethylformamide (DMF) as a solvent, was placed in a pulverizer (ball mill type pulverizer, LP-4 manufactured by Ito Seisakusho) equipped with zirconia balls, and the metal-organic structure was subjected to pulverization. The amount of solvent used was 2 mL per 1 g of metal-organic structure. The pulverization process was carried out for 1 hour at a rotation speed of 250 rpm. Mechanical energy was applied to the metal-organic structure through the pulverization process, resulting in its regeneration.

[0116] (Examples F2-F3) Except for changing the grinding time as shown in Table 12, the regeneration process for Examples F2 and F3 was carried out in the same manner as in Example F1.

[0117] [BET specific surface area] The BET specific surface area was measured for the regenerated metal-organic structures using the method described above. The results are shown in Table 12.

[0118] [Table 12]

[0119] As can be seen from Table 12, in Examples F1 to F3, applying energy to the metal-organic structure in the presence of an organic solvent (DMF) increased the BET specific surface area compared to the metal-organic structure after degradation treatment, and the metal-organic structure was regenerated.

[0120] [X-ray diffraction (XRD) measurement] XRD measurements were performed on the initial metal-organic structure (UiO-67), the metal-organic structure subjected to degradation treatment under condition 2, and the metal-organic structure subjected to regeneration treatment in Example F1. The XRD measurement conditions were the same as those described above for HKUST-1.

[0121] The data obtained from XRD measurements were analyzed using XRD analysis software (DIFFRAC.SUITE, Bruker). First, an X-ray diffraction pattern (Figure 3) was created using the XRD analysis software, and the diffraction peak with the highest intensity in the X-ray diffraction pattern was identified. In UiO-67, the diffraction peak that appeared around 5.6° had the highest intensity. Next, a linear baseline was created in the range of 3° to 9°, and waveform separation was performed on the diffraction peaks to be analyzed using analysis software (OriginPro, OriginLab). The full width at half maximum (FWHM) was calculated for the diffraction peaks after waveform separation. As a result, the FWHM H0 of the diffraction peak with the highest intensity in the initial metal-organic structure's X-ray diffraction pattern was 0.430°, and the FWHM H1 of the diffraction peak with the highest intensity in the regeneration treatment's X-ray diffraction pattern was 0.844°, with a ratio H1 / H0 of 196.3%. From these results, it can be seen that in Example F1, the crystallinity of the metal-organic structure decreased by performing the regeneration method of this embodiment. Furthermore, the full width at half maximum (FWHM) of the diffraction peak with the highest intensity in the X-ray diffraction pattern of the metal-organic structure after degradation treatment was 0.663°. [Industrial applicability]

[0122] The regeneration method of this embodiment is suitable for restoring the amount of low-molecular-weight compounds (adsorption capacity) that can be incorporated into the metal-organic structure. The regenerated metal-organic structure can be used for applications such as adsorbents.

Claims

1. Performing a degradation treatment that degrades metal-organic structures, After the degradation treatment, energy is applied to the metal-organic structure in the presence of an organic solvent or the vapor of the organic solvent. A method for regenerating metal-organic structures, including [the specified element].

2. The regeneration method according to claim 1, wherein the energy includes at least one selected from the group consisting of mechanical energy and thermal energy.

3. The regeneration method according to claim 1, wherein the degradation treatment includes a contact treatment in which the metal-organic structure is brought into contact with at least one selected from the group consisting of water, acid, and base.

4. The regeneration method according to claim 3, wherein the metal-organic structure is heated during the contact process.

5. The regeneration method according to claim 4, wherein the heating temperature of the metal-organic structure during the contact treatment is 50°C or higher.

6. The regeneration method according to claim 3, wherein the contact treatment is performed by arranging the metal-organic structure in an environment with a humidity of 50% RH or higher.

7. The regeneration method according to claim 1, wherein the BET specific surface area of ​​the metal-organic structure is reduced by performing the degradation treatment.

8. The regeneration method according to claim 1, wherein the BET specific surface area of ​​the metal-organic structure is increased by applying the aforementioned energy.

9. The regeneration method according to claim 1, wherein the energy is applied to the metal-organic structure by a pulverization process using a ball mill.

10. The regeneration method according to claim 9, wherein the time for the grinding process is one minute or more.

11. The regeneration method according to claim 1, wherein the organic solvent comprises at least one selected from the group consisting of alcohol compounds and amide compounds.

12. The regeneration method according to claim 11, wherein the alcohol compound comprises at least one selected from the group consisting of methanol and ethanol.

13. The regeneration method according to claim 1, wherein the energy is applied to the metal-organic structure in the presence of a solvent containing the organic solvent and water.

14. The regeneration method according to claim 1, wherein the metal-organic structure comprises a core containing at least one selected from the group consisting of metal ions, metal clusters, and metal oxide clusters, and an organic ligand.

15. The regeneration method according to claim 14, wherein the core comprises at least one selected from the group consisting of Cu, Mg, Co, and Zr.

16. The regeneration method according to claim 14, wherein the organic ligand includes a ring structure.

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