Metal-organic framework and shaped body

Abstract

To provide a technique that makes hysteresis of gas absorption of a metal-organic framework smaller.SOLUTION: A metal-organic framework for gas adsorption has a first organic ligand that mainly constitutes the framework of the metal-organic framework and a second organic ligand different from the first organic ligand, wherein among the atoms constituting the first and second organic ligands, the atom with the highest electronegativity is included at least in the second organic ligand.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to metal-organic frameworks. [Background technology]

[0002] Metal-organic frameworks that form porous structures by utilizing coordinate bonds between metal ions and organic substances have been known. Metal-organic frameworks are also commonly called MOFs (Metal Organic Frameworks) or PCPs (Porous Coordination Polymers). Because metal-organic frameworks are in powder form, shaping them has been investigated for practical use (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4980918 [Patent Document 2] Patent No. 6272696 [Patent Document 3] Patent No. 7229654 Summary of the Invention [Problem to be solved by the invention]

[0004] MOFs are expected to be used as gas and vapor adsorption and separation systems using PSA (Pressure Swing Adsorption) and TSA (Thermal Swing Adsorption) as adsorbents for gases and vapors. However, if the gas adsorption / desorption hysteresis of MOFs is large (the gas adsorption / desorption rate is slow), the throughput per unit time decreases, which may result in an increase in the size of the gas adsorption / desorption system and an increase in system costs.

[0005] In the techniques described in Patent Documents 1 to 3, a binder is added to give shape to the metal organic framework, but the addition of the binder may increase the hysteresis of gas adsorption / desorption. Therefore, there is a need for a technique to reduce the hysteresis of gas adsorption / desorption of a powder metal organic framework. [Means for solving the problem]

[0006] The present disclosure can be realized in the following forms. (1) According to one embodiment of the present disclosure, there is provided a metal-organic framework for gas adsorption, which comprises a first organic ligand that mainly constitutes a framework of the metal-organic framework, and a second organic ligand different from the first organic ligand, and among the atoms constituting the first organic ligand and the second organic ligand, at least the atom with the highest electronegativity is contained in the second organic ligand.

[0007] This type of metal-organic framework has a second organic ligand that is different from the first organic ligand that mainly constitutes the framework of the metal-organic framework, and the second organic ligand has more gas / vapor adsorption sites than the first ligand, so that the hysteresis of gas adsorption / desorption can be reduced.

[0008] (2) In the metal organic framework of the above embodiment, the second organic ligand may have more oxygen atoms and / or more nitrogen atoms than the first organic ligand. The oxygen atoms and nitrogen atoms exhibit basicity. When the metal organic framework is used, for example, as a carbon dioxide adsorbent, the carbon dioxide interacts with the oxygen atoms and / or nitrogen atoms exhibiting basicity and is adsorbed by the metal organic framework. Therefore, the metal organic framework of this embodiment can reduce the hysteresis of gas adsorption and desorption.

[0009] (3) In the metal-organic framework of the above embodiment, the second organic ligand may have more -COOH groups and / or -COO- groups than the first organic ligand. Since the -COOH groups and -COO- groups promote the adsorption of gases and vapors, this can further reduce the hysteresis of gas adsorption / desorption.

[0010] (4) In the metal-organic framework of the above form, the metal-organic framework may be a flexible metal-organic framework having structural flexibility, which can realize more efficient gas storage and separation than a rigid metal-organic framework.

[0011] (5) In the metal organic framework of the above aspect, the gas may be carbon dioxide. When the target to be adsorbed is carbon dioxide, the effect can be obtained by reducing the hysteresis of gas adsorption and desorption.

[0012] (6) In the metal organic framework of the above embodiment, when the saturated adsorption capacity of carbon dioxide of the metal organic framework at 0.975 atm is A and the saturated adsorption capacity of carbon dioxide of the second metal organic framework having the first organic ligand instead of the second organic ligand in the metal organic framework is B, (AB) / A<0.1 may be satisfied. In this way, the adsorption and desorption capacity of the metal organic framework can be appropriately maintained.

[0013] (7) The metal organic framework of the above embodiment may have a crystal structure pattern equivalent to that of a second metal organic framework having the first organic ligand instead of the second organic ligand in the metal organic framework, thereby making it possible to appropriately maintain the adsorption and desorption amounts of the metal organic framework.

[0014] (8) According to another aspect of the present disclosure, there is provided a shaped body. The shaped body includes the metal organic framework of the above aspect. According to the shaped body of this aspect, since the hysteresis of gas adsorption / desorption of the metal organic framework is small, even if a binder is included, the hysteresis of gas adsorption / desorption of the shaped body can be reduced.

[0015] The present disclosure can be realized in various forms other than those described above, for example, in the form of a gas separation adsorbent, a gas separation system, a method for manufacturing a metal organic framework, a method for manufacturing a shaped body, a method for manufacturing a gas adsorbent, etc. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing an example of a first organic ligand L and a second organic ligand L′ of an MOF. [Figure 2] FIG. 1 is a process diagram showing an example of a method for producing an MOF. [Figure 3] FIG. 1 shows XRD of COO-grouped MOF powder. [Figure 4] FIG. 1 shows IR of a MOF powder to which COO-groups have been added. [Figure 5] FIG. 1 is a process diagram showing an example of a method for producing a shaped body. [Figure 6] FIG. 10 is a diagram showing the composition of each sample and whether or not an increase in hysteresis in gas adsorption / desorption can be suppressed. [Figure 7] FIG. 1 shows the CO2 adsorption / desorption capacity of powder samples. [Figure 8] FIG. 1 shows the CO2 adsorption / desorption capacity of shaped body samples. [Figure 9] FIG. 1 is a diagram showing the structural formulas of a portion of the particle interfaces of samples S1 and S3. [Figure 10] FIG. 1 is an explanatory diagram conceptually showing the interactions between oxygen, nitrogen and CO2. [Figure 11] FIG. 1 is an explanatory diagram conceptually showing interactions between oxygen, nitrogen, and polar molecules. DETAILED DESCRIPTION OF THE INVENTION

[0017] <Embodiment> A. Metal-organic framework (MOF) composition: A metal-organic framework according to an embodiment of the present disclosure is a metal-organic framework for gas adsorption, which comprises a first organic ligand that mainly constitutes the framework of the metal-organic framework, and a second organic ligand different from the first organic ligand, and among the atoms constituting the first organic ligand and the second organic ligand, the atom with the highest electronegativity is at least contained in the second organic ligand. Here, "mainly" means that the amount of the first organic ligand is the majority, i.e., 51% or more.

[0018] FIG. 1 is a diagram showing an example of the first organic ligand L and the second organic ligand L' of the MOF of this embodiment. When the MOF is an ELM (Elastic Layer-structured MOF), the organic ligand (first organic ligand L) is 4,4'-bipyridine. In MOF No. 1 of this embodiment, pyridine carboxylic acid (isonicotinic acid) is added, and the second organic ligand L' is pyridine carboxylic acid. The atoms constituting the first organic ligand L are carbon (C), nitrogen (N), and hydrogen (H). On the other hand, the atoms constituting the second organic ligand L' are carbon (C), nitrogen (N), hydrogen (H), and oxygen (O). Of carbon (C), nitrogen (N), hydrogen (H), and oxygen (O), oxygen (O) has the highest electronegativity. That is, in the example of MOF No. 1 shown in FIG. 1, the atom with the highest electronegativity (O) among the atoms constituting the first organic ligand L and the second organic ligand L' is contained in the second organic ligand L'. Similarly, in MOF No. 2, the atom with the highest electronegativity (O) among the atoms constituting the first organic ligand L and the second organic ligand L' is contained in the second organic ligand L'. In MOFs Nos. 3 and 4, the atom with the highest electronegativity (N) among the atoms constituting the first organic ligand L and the second organic ligand L' is contained in both the first organic ligand L and the second organic ligand L'.

[0019] When the MOF is, for example, UIO-66, the second organic ligand L' can be, for example, 2-aminoterephthalic acid, which has a functional group containing nitrogen (N) or oxygen (O) in terephthalic acid.

[0020] The metal-organic framework of this embodiment has a second organic ligand different from the first organic ligand that mainly constitutes the framework of the metal-organic framework, and the second organic ligand has more gas / vapor adsorption sites than the first ligand, so that the hysteresis of gas adsorption / desorption can be reduced. Note that if all of the first organic ligands that mainly constitute the framework of the metal-organic framework are changed to second organic ligands, it may become difficult to maintain the structure of the metal-organic framework, so the metal-organic framework has a first organic ligand that mainly constitutes the framework of the metal-organic framework and a second organic ligand different from the first organic ligand.

[0021] The type of MOF is not particularly limited. For example, ELMs with 4,4'-bipyridine as an organic ligand, such as ELM-11, ELM-12, and ELM-31, or rigid MOFs such as UIO and MIL-101, to which a second ligand has been added, can be used. Flexible MOFs with flexible structures are preferred. This allows for more efficient gas storage and separation than rigid MOFs.

[0022] There are no particular limitations on the gas to be adsorbed by MOFs, and various gases such as carbon dioxide and water vapor can be adsorbed. Carbon dioxide is preferably the gas to be adsorbed. Carbon dioxide has an electron-poor region in which the bonding electrons are strongly attracted to the oxygen side, making it more likely to interact with base sites (unshared electron pairs). Carbon dioxide is more suitable because it is adsorbed by MOFs due to the interaction between this electron-poor region and base sites (atoms with the highest electronegativity).

[0023] When the saturated adsorption amount of carbon dioxide of the MOF at 0.975 atm is A and the saturated adsorption amount of carbon dioxide of the second MOF having the first organic ligand instead of the second organic ligand in the MOF is B, it is preferable that (AB) / A<0.1. In this way, the adsorption and desorption amounts of the metal-organic framework can be maintained appropriately.

[0024] The MOF may have a crystal structure pattern equivalent to that of a second MOF having a first organic ligand instead of the second organic ligand, which allows the adsorption and desorption amounts of the metal-organic framework to be maintained appropriately.

[0025] The highly electronegative atom of the second organic ligand is not particularly limited, and can be one having a donor electron, such as a halogen atom. The second organic ligand preferably has more oxygen atoms and / or nitrogen atoms than the first organic ligand. The oxygen atoms and nitrogen atoms exhibit basicity. When the metal-organic framework is used, for example, as a carbon dioxide adsorbent, the carbon dioxide interacts with the oxygen atoms and nitrogen atoms exhibiting basicity and is adsorbed by the metal-organic framework. Therefore, the metal-organic framework of this form can reduce the hysteresis of gas adsorption and desorption.

[0026] The second organic ligand preferably has more -COOH groups and / or -COO- groups than the first organic ligand, which promotes gas and vapor adsorption, thereby further reducing the hysteresis of gas adsorption and desorption.

[0027] The organic ligands of MOFs can be identified by infrared absorption spectrometry (IR) and gas chromatography-mass spectrometry (GC / MS).

[0028] B. Preparation of MOFs: Figure 2 is a process diagram showing an example of a method for producing an MOF. Figure 2 shows ELM-11 as an example of an MOF. ELM-11 has a structure in which the organic ligand 4,4'-bipyridine and the metal ion copper tetrafluoroborate are crystallized through coordinate bonds.

[0029] In step P202, precursor solutions (precursor solution 1 and precursor solution 2) are prepared. Precursor solution 1 is a solution in which 4,4'-bipyridine (bpy) and isonicotinic acid are dissolved in methanol, and precursor solution 2 is a solution in which Cu(BF4)2 is dissolved in ultrapure water.

[0030] In step P204, precursor solution 1 is added dropwise to precursor solution 2 prepared in step P202 while stirring (at room temperature). For example, the addition time is 2 hours and the stirring speed is 800 rpm. This step allows isonicotinic acid to be coordinated to the MOF particles.

[0031] In step P206, the liquid phase synthesized in step P204 is filtered, and the powder is extracted and washed. In step P208, the powder extracted in step P206 is dried in vacuum at room temperature to recover pre-ELM-11 (water-adsorbed state). Note that the method for producing MOF is not limited to the method shown in FIG. 2, and various known methods can be used for production.

[0032] Figure 3 shows the XRD (X-ray diffraction) of the MOF powder to which COO- groups have been added, and Figure 4 shows the IR of the MOF powder to which COO- groups have been added. The Pre-ELM-11 stable phase and Pre-ELM-11 metastable phase shown in Figure 3 are cif file data of the structure in which water molecules are adsorbed to ELM-11 before thermal dehydration. "No isonicotinic acid added" shows pre-ELM-11 prepared without adding isonicotinic acid to the precursor solution 1 prepared in the above step P202. Figure 4 shows pre-ELM-11 prepared by changing whether or not isonicotinic acid is added to the precursor solution 1 prepared in the above step P202. The concentration of isonicotinic acid added is 32 mM. mM is 10 -3 3 and 4, the MOF powder to which COO-groups have been added is shown at the top, and below that, for comparison, MOF powder to which COO-groups have not been added and the like are shown.

[0033] As shown in Figure 3, both pre-ELM-11 prepared by the above method and pre-ELM-11 to which COO-groups had been added retained the structure of pre-ELM-11. In other words, it was confirmed that the pre-ELM-11 structure was maintained even after the addition of COO-groups.

[0034] In Figure 4, the peak position indicating the C=O stretching derived from COOH is indicated by band P, and the peak position of COO - The peak position showing the antisymmetric stretching due to ions is shown in band Q, and the peak position showing the symmetric stretching is shown in band R. Bands P, Q, and R are cited from the following reference 1. Reference 1: Bunseki Kagaku Vol. 56 No. 6 99. 2 (2007) 457-464

[0035] As shown in Figure 4, the MOFs prepared by the above method (both with and without isonicotinic acid) did not detect a peak corresponding to the COOH-derived C=O stretching detected in isonicotinic acid. Furthermore, the MOFs with isonicotinic acid added showed a peak corresponding to the COO stretching not detected in isonicotinic acid. - A peak corresponding to the symmetric stretching of ions was detected, confirming that the MOF prepared by the above method contained COO- groups.

[0036] The results in Figures 3 and 4 confirmed that the above production method allows the addition of COO- groups while maintaining the structure of pre-ELM-11.

[0037] C. Formed bodies comprising metal-organic frameworks: Another embodiment of the present disclosure provides a shaped object containing a MOF having the above-described second ligand. Because the hysteresis loop of the gas adsorption / desorption of the MOF particles is small, the shaped object can exhibit small gas adsorption / desorption hysteresis loop even when a binder is included.

[0038] D. Manufacturing method of the shaped body: 5 is a process diagram showing an example of a method for producing a shaped object. In step P102, the following items (1) to (4) are prepared. (1) MOF precursor (e.g., pre-ELM-11 with COO-groups) (2) Silane coupling agents (e.g., silane KMB-3066 ((CH3O)3Si(CH2)6Si(OCH3)3)) (3) Binder (organic binder) (4) Solvent (e.g., ethanol water (ethanol:water = 90:10 wt%)) (1) may be prepared in step P102 or may be prepared in advance. An example of the method for preparing the MOF precursor is as described above.

[0039] In step P104, the above (1) to (4) are mixed and stirred in a capped glass bottle using a stirrer and a magnetic starter at a predetermined rotation speed for a predetermined time. This process finely pulverizes the raw material powder, silane coupling agent, and binder, and mixes them with the solvent (ethanol water) to produce a slurry. For example, the rotation speed can be 800 rpm and the stirring time can be 24 hours.

[0040] In step P106, the lid of the glass bottle containing the slurry obtained in step P104 is removed, and the slurry is stirred at a rotation speed of 800 rpm and dried in a draft chamber to sufficiently volatilize the ethanol and turn it into a powder.

[0041] In step P108, the powder obtained in step P106 is placed in a mold and pressed using a uniaxial press to obtain a green compact. Depending on the shape of the pressing mold used in step P110, the final MOF shaped body can be molded into any desired shape. For example, it can be molded into a rectangular column, a cylindrical column, a pellet, or the like.

[0042] In step P110, the green compact is removed, completing the MOF-containing shaped object 1. The method for producing the MOF-containing shaped object 1 is not limited to the method shown in FIG. 1, and various known methods can be used. [Example]

[0043] Samples of MOFs and shaped bodies containing MOFs were prepared, and whether the increase in hysteresis was suppressed was evaluated. In this example, a regular pre-ELM-11 product (also called a product without COOH groups) and a product with COOH groups were used as the MOFs. For the shaped bodies, KBM-3066 (manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the silane coupling agent, and ethyl cellulose was used as the organic binder. Samples of the shaped bodies were prepared using the manufacturing method of the above embodiment (Figure 5).

[0044] [Sample preparation] Synthesis of pre-ELM-11 (regular product) Precursor solution 1 was prepared by dissolving 5.34 g of 4,4'-bipyridine in 16.88 g of methanol. Precursor solution 2 was prepared by dissolving 8.76 g of a 45 wt % copper tetrafluoroborate aqueous solution in 14.7 g of ultrapure water (step P202). Using a syringe pump, precursor solution 1 was added dropwise over 2 hours to precursor solution 2 that was being stirred with a magnetic stirrer at 800 rpm, and stirring was continued for 24 hours (step P204). The resulting powder was then collected by suction filtration (step P206) and vacuum dried for one day to volatilize the remaining solvent, yielding pre-ELM-11 (step P208).

[0045] Pre-ELM-11 (COO-group added product) Precursor solution 1A was prepared by dissolving 5.34 g of 4,4'-bipyridine and 0.0843 g of isonicotinic acid with a COOH group in methanol. Using precursor solution 1A instead of precursor solution 1, the same procedure as above was carried out to obtain pre-ELM-11, which had isonicotinic acid with a COO- group (deprotonated during the synthesis process).

[0046] - Preparation of powder for MOF shaped body Xg of pre-ELM-11 powder (regular product) or pre-ELM-11 powder with isonicotinic acid (COO-group-added product), Yg of silane coupling agent KBM-3066, and Zg of binder powder were added to a water and ethanol mixed solvent (water:ethanol = 10:90 wt%) and stirred at 800 rpm for 24 hours to prepare powder for MOF shaped bodies (steps P102 to P106). Powders for MOF shaped bodies with different compositions were prepared by varying the ratio of X, Y, and Z. Samples S2 and S4 have an X:Y:Z ratio of 90:5:5.

[0047] - Preparation of MOF excipients Using a press jig with a diameter of 3 mm, the powder for the MOF shaped body prepared above was uniaxially pressed at a pressure of 114 MPa to produce a cylindrical MOF shaped body with a diameter of 3 mm and a height of 2 to 3 mm (steps P108 and P110).

[0048] [CO2 adsorption / desorption characteristics evaluation] Each sample was evaluated for CO2 adsorption and desorption properties. This was performed using an Anton Paar AutoSorb iQ high-vacuum physical adsorption analyzer. To remove the adsorbed water from the MOF-shaped pre-ELM-11, the sample was pretreated by vacuum heating at 130°C for 5 hours. The evaluation conditions were a temperature of 0°C, equilibration time of 10 minutes, tolerance of 0, and measurement points at CO2 partial pressures ranging from 0.025 to 0.975 atm in 0.025 atm increments. From the measurement results, a CO2 adsorption isotherm was plotted with the vertical axis representing the amount of CO2 adsorbed divided by the total sample weight and the horizontal axis representing the CO2 partial pressure, and the CO2 adsorption and desorption properties were evaluated.

[0049] Figure 6 shows the composition of each sample and whether or not the increase in gas adsorption / desorption hysteresis is suppressed. Samples S1 and S3 are MOF powders, and samples S2 and S4 are shaped bodies. For shaped body samples S2 and S4, the silane coupling agent used was KBM-3066 (manufactured by Shin-Etsu Chemical Co., Ltd.), which has bistrimethoxy groups at both ends. The MOFs in samples S1 and S2 are standard ELM-11 (without COO-groups), while the MOFs in samples S3 and S4 are ELM-11 with COO-groups. The ratio of ELM-11 (X): silane coupling agent (Y): binder (Z) shown in Figure 6 indicates the mixing ratio when the shaped body samples were prepared. This ratio approximately corresponds to the mass ratio of ELM-11 (MOF) contained in the shaped body to the silicon-based binder and organic binder, which are the products obtained after the reaction of the silane coupling agent with the silane coupling agent. As shown in Fig. 6, the increase in hysteresis of gas adsorption / desorption was suppressed in sample S3 compared to sample S1 (shown as ◯ in Fig. 6), and the increase in hysteresis of gas adsorption / desorption was suppressed in sample S4 compared to sample S2 (shown as ◯ in Fig. 6).

[0050] Figure 7 shows the CO2 adsorption / desorption capacity of powder samples. In Figure 7, CO2 adsorption isotherms are plotted with the vertical axis representing (CO2 adsorption amount) / (total weight of sample) and the horizontal axis representing CO2 partial pressure. STP on the vertical axis indicates that the values ​​are converted to standard conditions.

[0051] As shown in the figure, it was confirmed that sample S3 to which isonicotinic acid was added exhibited a smaller CO2 adsorption / desorption hysteresis than sample S1 to which isonicotinic acid was not added.

[0052] Fig. 8 is a diagram showing the CO2 adsorption / desorption capacity of a shaped body sample. In Fig. 8, CO2 adsorption isotherms are plotted with the vertical axis representing (CO2 adsorption amount) / (total weight of sample) and the horizontal axis representing CO2 partial pressure.

[0053] As shown in the figure, it was confirmed that even in the shaped body samples, sample S4 to which isonicotinic acid was added had a smaller CO2 adsorption / desorption hysteresis than sample S2 to which isonicotinic acid was not added.

[0054] Figure 9 shows the structural formulas of part of the particle interface of samples S1 and S3. As shown in the figure, the addition of isonicotinic acid appears to have increased the number of CO2 adsorption sites on the particle surface in sample S3. It is believed that the increased CO2 concentration in the gas phase / particle surface may have improved the adsorption rate.

[0055] Figure 10 is an explanatory diagram conceptually showing the interaction between oxygen, nitrogen, and CO2. CO2 does not have any vacant orbitals, but it has an electron-poor region where the bonding electrons are strongly attracted to the oxygen (O) side, making it more likely to interact with basic sites (lone electron pairs). It is thought that CO2 is adsorbed to nitrogen (N) or oxygen (O), which exhibit basicity, due to the interaction between this electron-poor region and basic sites.

[0056] Figure 11 is an explanatory diagram conceptually showing the interactions between oxygen, nitrogen, and polar molecules. It is thought that polar molecules such as H2O also interact with nitrogen (N) and oxygen (O) and are adsorbed.

[0057] The present disclosure is not limited to the above-described embodiments, and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0058] The present disclosure can also be realized in the following forms. [Application example 1] A metal-organic framework for gas adsorption, comprising: a first organic ligand that mainly constitutes the skeleton of the metal organic framework; a second organic ligand different from the first organic ligand; and an atom having the highest electronegativity among atoms constituting the first organic ligand and the second organic ligand is contained in at least the second organic ligand; Metal-organic structures. [Application example 2] The metal organic framework according to Application Example 1, the second organic ligand has more oxygen atoms and / or more nitrogen atoms than the first organic ligand; Metal-organic structures. [Application example 3] The metal organic framework according to Application Example 1 or Application Example 2, the second organic ligand has more —COOH groups and / or —COO— groups than the first organic ligand; Metal-organic structures. [Application example 4] The metal organic framework according to any one of Application Examples 1 to 3, The metal-organic framework is a flexible metal-organic framework having structural flexibility. Metal-organic structures. [Application example 5] The metal organic framework according to any one of Application Examples 1 to 4, The gas is carbon dioxide. Metal-organic structures. [Application Example 6] The metal organic framework according to any one of Application Examples 1 to 5, The saturated adsorption amount of carbon dioxide of the metal organic framework at 0.975 atm is defined as A, When the saturated adsorption amount of carbon dioxide at 0.975 atm of a second metal-organic framework having the first organic ligand instead of the second organic ligand in the metal-organic framework is B, (AB) / A<0.1 That is, Metal-organic structures. [Application Example 7] The metal organic framework according to any one of Application Examples 1 to 6, has a crystal structure pattern equivalent to that of a second metal organic framework having the first organic ligand instead of the second organic ligand in the metal organic framework; Metal-organic structures. [Application Example 8] A shaped body, The metal organic framework according to any one of Application Examples 4 to 7 is included. Forming body. [Explanation of symbols]

[0059] 1...Formed body 10…MOF (metal organic framework) L...first organic ligand L'...Second organic ligand

Claims

1. A metal-organic framework for gas adsorption, comprising: a first organic ligand that mainly constitutes the skeleton of the metal organic framework; a second organic ligand different from the first organic ligand; and an atom having the highest electronegativity among atoms constituting the first organic ligand and the second organic ligand is contained in at least the second organic ligand; Metal-organic structures.

2. The metal-organic framework according to claim 1, the second organic ligand has more oxygen atoms and / or more nitrogen atoms than the first organic ligand; Metal-organic structures.

3. The metal-organic framework according to claim 1, the second organic ligand has more —COOH groups and / or —COO— groups than the first organic ligand; Metal-organic structures.

4. The metal-organic framework according to claim 1, The metal-organic framework is a flexible metal-organic framework having structural flexibility. Metal-organic structures.

5. The metal-organic framework according to claim 4, The gas is carbon dioxide. Metal-organic structures.

6. The metal-organic framework according to claim 4, The saturated adsorption amount of carbon dioxide of the metal organic framework at 0.975 atm is defined as A, When the saturated adsorption amount of carbon dioxide at 0.975 atm of the second metal-organic framework having the first organic ligand instead of the second organic ligand in the metal-organic framework is B, (A-B) / A<0.1 That is, Metal-organic structures.

7. The metal-organic framework according to claim 4, has a crystal structure pattern equivalent to that of a second metal-organic framework having the first organic ligand instead of the second organic ligand in the metal-organic framework; Metal-organic structures.

8. A shaped body, The metal organic framework according to any one of claims 4 to 7, Forming body.

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