JP6555861B2 - Coordinating complex containing fluorine or salt thereof, gas adsorbent and production method thereof, gas separation device and gas storage device using the same - Google Patents

Description

  The present invention relates to a metal complex having a coordinating functional group, a gas adsorbent prepared from the material as a raw material, its use as a gas adsorbent, and a gas separation apparatus and a gas storage apparatus using the same.

  The gas adsorbent has a characteristic of storing a large amount of gas at a low pressure as compared with pressurized storage and liquefied storage. For this reason, in recent years, development of a gas storage device and a gas separation device using a gas adsorbent has been active. As the gas adsorbent, activated carbon, zeolite and the like are known. Recently, a method of absorbing gas in a porous polymer metal complex has also been proposed.

  A porous polymer metal complex (hereinafter also referred to as PCP (Porous Coordination Polymer) in the present specification) is a crystalline solid obtained from a metal ion and an organic ligand. Due to the variety of combinations and polymer skeleton structures, it has the potential to develop various gas adsorption characteristics. However, these conventionally proposed gas adsorbents are not sufficiently satisfactory in terms of the amount of gas adsorption and workability, and the development of gas adsorbents with better characteristics is desired. . (Patent Documents 1-2, Non-Patent Documents 1-2)

  There are very few examples of PCP containing a plurality of types of metal ions, and it is hardly known what raw materials should be reacted under what conditions. In a normal PCP synthesis, that is, a one-step reaction in which a metal ion and a ligand are reacted at the same time, even if two types of metal ions are used, either one type of metal ions is taken in, or PCP composed of metal ions A It is very difficult to make a PCP containing only two kinds of metal ions, ie, only a mixture of PCPs consisting of and metal ions B is produced.

  It is also possible to prepare a material containing a plurality of types of metal ions by adding a metal ion different from the metal ions used for the synthesis of the first complex in a subsequent reaction. Metal ions contain multiple types of metal ions because they have a major effect on the physical properties of PCP, especially gas adsorption, both by direct effects due to affinity with gas molecules and by indirect effects through the pore structure of PCP. The material thus obtained can be expected to have different physical properties from those of a material containing a single metal ion.

In many cases of PCP synthesis, a PCP having a polymer network is synthesized by reacting a metal ion with a ligand having a plurality of coordination points. On the other hand, a method of synthesizing PCP by a method of adding a metal salt or a ligand to a complex that is not a polymer is known. According to this method, there is a possibility that a PCP that could not be prepared by the conventional method of reacting a metal ion with a ligand can be synthesized. (Non-patent documents 3 to 7)
(Patent Documents 8 to 12)

  There are very few examples of PCP synthesis using precursors, and little is known about what raw materials should be reacted under what conditions.

  In addition, slidability, water repellency, etc. are known as general influences on fluorine materials in which attempts have been made to introduce fluorine atoms into the ligand to control the gas adsorption characteristics of the porous body. However, in the example of the porous polymer metal complex into which fluorine is introduced as described above, improvement of hydrogen adsorption characteristics by fluorine atoms is described. These do not coincide with the physical properties caused by the above-mentioned fluorine atoms, and the principle by which the introduction of fluorine atoms improves the hydrogen adsorption characteristics is not described in detail. That is, the introduction of fluorine atoms is a porous polymer. It is not clear how it affects the gas adsorption properties of metal complexes. (Non-patent documents 13 to 16)

  There are few synthesis examples of PCP and gas adsorbents using fluorine-containing ligands, and fluorine-containing ligands contain PCP and gas adsorbents using precursors and contain multiple types of metal ions. It is not known how it will affect the synthesis of the adsorbent.

JP 2000-109493 A Japanese Patent No. 4427236

Susumu Kitagawa, Integrated Metal Complex, Kodansha Scientific, 2001, pages 214-218 Robson et al., Angew. Chem. Int. Ed. 1998, 37, 1460 ± 1494 Ferey et al., Angew. Chem. Int. Ed. 2004, 43, 6285 Eddaoudi et al., J. AM. CHEM. SOC. 2008, 130, 1560 Eddaoudi et al., Angew. Chem. Int. Ed. 2007, 46, 3278 Yaghi et al., Angew. Chem. Int. Ed. Engl., 2006,45, 2528-2533 Rosseinsky et al., Science (2007) 315, 977 Dinca et al., Chem. Sci., 2012,3, 2110 Kitagawa et al., Inorg. Chem. 2005, 44, 133 Kitagawa et al., J. Am. Chem. Soc .. 2008, 130, 4475 Loye et al., Inorg. Chem. (00) 1943 Ferey et al., Angew. Chem. Int. Ed. Engl., 2007, 46, 5877 Omary et al., J. Am. Chem. Soc., 2007,129, 15454 Omary et al., Angew. Chem. Int. Ed. 2009, 48, 2500 Li et al., J. Am. Chem. Soc., 2004, 126, 1308 Ferey et al., J. Am. Chem. Soc., 2010, 132, 1127-1136

The present invention relates to a fluorine-containing metal complex having a coordinating functional group (coordination point) that can be used to synthesize a gas adsorbent that is not limited to a porous polymer metal complex (PCP), and uses the same. It is to provide a gas adsorbent having excellent characteristics. Another object of the present invention is to provide a gas storage device and a gas separation device that contain a gas adsorbent having the above-mentioned characteristics.
As will be described later (for example, see paragraph [0031]), the metal complex of the present invention has a coordinating functional group (carboxyl group) not involved in coordination. In this specification, a state having a coordinating functional group (carboxyl group) not involved in coordination is referred to as “having a coordination point”. Therefore, the metal complex of the present invention may be referred to as “a fluorine-containing metal complex having a coordination point” or “a metal complex having a coordination point”.

  As a result of intensive studies to solve the above-described problems, the present inventors have found that an aromatic ligand containing at least one perfluoroalkyl group and two carboxyl groups, When the transition metal ion is reacted, a fluorine-containing complex having a coordinating carboxyl group that does not participate in the coordination to the transition metal ion (i.e. It has been found that a material having gas adsorption characteristics can be prepared by synthesizing a fluorine complex) and further reacting by adding a metal ion to the complex, and the present invention has been completed.

  That is, the present invention provides a coordination point obtained by reacting a divalent transition metal ion, an aromatic ligand containing at least one perfluoroalkyl group and two carboxyl groups in the presence of water. The present invention relates to a gas adsorbing material prepared using the present material, its use as a gas adsorbing material, and a gas storage device and a gas separating device containing the gas adsorbing material therein.

That is, the present invention is as follows.
(1) The following formula (I)
[M ₂ X ₄ ] (I)
(In the formula, M is one kind of metal ion selected from divalent transition metal ions , and X is an isophthalate containing at least one perfluoroalkyl group having 1 to 10 carbon atoms and two carboxyl groups. An aromatic ligand selected from acid or terephthalic acid.)
Wherein the four aromatic ligands coordinate to the divalent transition metal ion to form a paddle wheel structure, and the four aromatics In each group ligand, one of the two carboxyl groups is coordinated to the divalent transition metal ion, and the other carboxyl group is coordinated to the divalent transition metal ion. A fluorine-containing metal complex or a salt thereof.

  (2) The fluorine-containing metal complex or a salt thereof according to (1), wherein M is selected from zinc ion, cobalt ion, copper ion, and nickel ion.

( 3 ) A perfluoroalkyl group having 1 to 10 carbon atoms is CF ₃ , C ₂ F ₅ , n-C ₃ F ₇ , n-C ₄ F ₉ , n-C ₅ F ₁₁ , n-C ₈ F. _The fluorine-containing metal complex or the salt thereof according to (1 ) or (2), which is selected from ₁₇ , n-C ₁₀ F ₂₁ .

(4) Organic solvent molecules and water molecules are coordinated, and the formula (II)
[M ₂ X ₄ Lz] (II)
(In the formula, M is one kind of metal ion selected from divalent transition metal ions , and X is an isophthalate containing at least one perfluoroalkyl group having 1 to 10 carbon atoms and two carboxyl groups. An aromatic ligand selected from acid or terephthalic acid, L is an organic solvent molecule or water molecule, and z is 0 to 4 but not 0.)
Wherein the four aromatic ligands coordinate to the divalent transition metal ion to form a paddle wheel structure, and the four aromatics In each group ligand, one of the two carboxyl groups is coordinated to the divalent transition metal ion, and the other carboxyl group is coordinated to the divalent transition metal ion. A fluorine-containing metal complex or a salt thereof.

( 5 ) The fluorine-containing metal complex or a salt thereof according to ( 4 ) above, wherein L is a water molecule.

(6) A gas adsorbent obtained by reacting the fluorine-containing metal complex or the salt thereof according to any one of (1) to (5) above with a divalent transition metal salt .

( 7 ) A method for preparing a gas adsorbent by reacting the fluorine-containing metal complex or the salt thereof according to any one of (1) to ( 5 ) above with a divalent transition metal salt.

( 8 ) The gas adsorbent according to ( 7 ) above, wherein a fluorine-containing metal complex or a salt thereof is reacted with a metal salt different from the divalent transition metal constituting the fluorine-containing metal complex or the salt thereof. How to prepare.

( 9 ) A gas separator using the gas adsorbent described in ( 6 ) above.

( 10 ) A gas storage device using the gas adsorbent described in ( 6 ) above.

  A gas adsorbent can be prepared using the fluorine-containing metal complex of the present invention. The adsorbent prepared from the fluorine-containing metal complex of the present invention can prepare a material that adsorbs and releases a large amount of gas and performs selective gas adsorption. In addition, it is possible to manufacture a gas storage device and a gas separation device in which a gas adsorbing material prepared from the fluorine-containing metal complex of the present invention is housed.

  If the adsorbent prepared from the fluorine-containing metal complex of the present invention is used, for example, as a gas separation apparatus of a pressure swing adsorption method (hereinafter abbreviated as “PSA method”), very efficient gas separation is possible. . In addition, the time required for pressure change can be shortened, contributing to energy saving. Furthermore, since it can contribute to the miniaturization of the gas separation device, it is possible to increase the cost competitiveness when selling high-purity gas as a product. Since the cost required for the equipment that requires high purity gas can be reduced, the manufacturing cost of the final product can be reduced.

  Another use of the adsorbent prepared from the fluorine-containing metal complex of the present invention is a gas storage device. When the gas adsorbent of the present invention is applied to a gas storage device (business gas tank, consumer gas tank, vehicle fuel tank, etc.), it is possible to dramatically reduce the pressure during transportation and storage. . As an effect resulting from the ability to reduce the gas pressure during transportation or storage, firstly, improvement in the degree of freedom of shape can be mentioned. In the conventional gas storage device, the gas adsorption amount cannot be maintained high unless the pressure during storage is maintained. However, in the gas storage device of the present invention, a sufficient gas adsorption amount can be maintained even if the pressure is lowered.

  When applied to a gas separation device or gas storage device, there is no need to use a special device for the shape of the container, the material of the container, the type of gas valve, etc., and those used in the gas separation device and gas storage device Can be used. However, improvement of various devices is not excluded, and any device is included in the technical scope of the present invention as long as the adsorbent prepared from the fluorine-containing metal complex of the present invention is used. Is.

The structure of the fluorine-containing metal complex of the present invention is shown. A structure in which water molecules are coordinated to the fluorine-containing metal complex of the present invention is shown.

The present invention relates to the following formula (I)
[M ₂ X ₄ ] (I)
(In the formula, M is one metal ion selected from divalent transition metal ions , and X is an aromatic containing at least one perfluoroalkyl group having 1 to 10 carbon atoms and two carboxyl groups. Group ligand.)
Wherein four aromatic ligands coordinate to a divalent transition metal ion to form a paddle wheel structure, and four aromatic coordinations. In each of the children, one of the two carboxyl groups is coordinated to a divalent transition metal ion, and the other carboxyl group is not coordinated to a divalent transition metal ion. Provided is a fluorine-containing metal complex or a salt thereof.

The fluorine-containing metal complex of the present invention will be described with reference to FIG. 1 using a fluorine-containing complex obtained from a copper ion and an isophthalic acid derivative having a C ₂ F ₅ group at the 5-position. In FIGS. 1 and 2, carbon atoms are white, copper ions as representative examples of divalent transition metal ions are black, oxygen atoms are dark gray, fluorine atoms are light gray, but hydrogen atoms are simple. Is omitted. Two copper ions are coordinated to four carboxyl groups of four ligands to form a so-called paddle wheel type complex. One of the two carboxyl groups of each isophthalic acid type ligand is coordinated to the copper ion, but the other carboxyl group is not involved in the coordination and a new metal ion is added. If so, it can participate in further complexation reactions. Usually, this vacant carboxyl group and copper ions react to obtain a polymerized PCP, but the ligand used in the synthesis in the present invention has a perfluoroalkyl group, and the reaction solvent Since water contains water, it is presumed that a fluorine-containing complex having a coordination point is obtained instead of PCP from the balance of hydrophobicity and hydrophilicity. Further, the carboxyl group constituting the coordination point of the fluorine-containing metal complex of the present invention can form a salt.

  In FIG. 2, water molecules (only oxygen atoms are shown because hydrogen atoms are omitted in FIG. 2) are arranged above and below the copper ions of the paddle wheel structure of the fluorine-containing metal complex shown in FIG. The structure that is positioned is shown. Since the fluorine-containing metal complex of the present invention is obtained by reacting water in a reaction solvent, the fluorine-containing metal complex obtained at the time of synthesis is often obtained by coordination of water molecules with copper ions. . The water molecules coordinated to the copper ions are easily desorbed.

In addition, the fluorine-containing metal complex of the present invention is coordinated with a water molecule in a solvent used for synthesis, an organic solvent molecule, or a water molecule in the air.
[M ₂ X ₄ Lz] (II)
(In the formula, M is one metal ion selected from divalent transition metal ions , and X is an aromatic containing at least one perfluoroalkyl group having 1 to 10 carbon atoms and two carboxyl groups. L is an organic solvent molecule used in the synthesis as described later and water molecules in the air. Z is in the range of 0 to 4 but not 0.) It may change to a complex complex. In the formula (II), as described above, L may be a water molecule contained in the solvent at the time of synthesis. z is a numerical value representing the average content of the ligand L in the fluorine-containing metal complex of the present invention present in a solid or solution state. The structure of the fluorine-containing metal complex represented by the formula (II) is the same as that shown in FIG.

  However, the coordinating molecules represented by L in these complex complexes are only weakly bonded to metal ions, and are removed by pretreatment such as vacuum drying when used as a gas adsorbent. To the original complex of formula (I). Therefore, even a complex represented by the formula (II) can be regarded as essentially the same as the fluorine-containing metal complex of the present invention.

  The metal ion used to form the fluorine-containing metal complex of the present invention is a divalent transition metal ion. The divalent transition metal ion stably forms the above coordination structure. Specific examples of divalent transition metal ions include cobalt ions, nickel ions, zinc ions, and copper ions. From the viewpoint of chemical stability of the obtained fluorine-containing metal complex, copper ions and zinc ions are preferable. Copper ions are particularly preferred from the viewpoint of yield.

  The bidentate aromatic ligand having at least one perfluoroalkyl group and two carboxyl groups forming the fluorine-containing metal complex of the present invention will be described. The bidentate ligand may be a linear ligand such as terephthalic acid or a bent ligand such as isophthalic acid. The linear ligand such as terephthalic acid may be one having a side chain containing a fluorine atom at the 2-position or one having side chains containing a fluorine atom at the 2-position and the 5-position. Examples of the bent type ligand such as isophthalic acid include an isophthalic acid type ligand having a side chain containing a fluorine atom at the 5-position.

The perfluoroalkyl group of these ligands may be a linear or branched perfluoroalkyl group having 1 to 10 carbon atoms, but CF ₃ , C is particularly preferable in terms of excellent gas separation characteristics. _{2 F 5, n-C 3} F 7, n-C 4 F 9, n-C 5 F 11, n-C 8 F 17, n-C 10 F 21 group is preferred. As a method for introducing a perfluoroalkyl group into the benzene ring, for example, Shibasaki et al., Chem. Asian J. 2006, 1, 314-321 can be referred to.

  The fluorine-containing metal complex of the present invention represented by the formula (I) or (II) is an aromatic ligand containing at least one divalent transition metal ion, at least one perfluoroalkyl group and two carboxyl groups. Can be produced by mixing in a solvent containing water.

  Since the fluorine-containing compound has high hydrophobicity and low affinity with an aqueous solvent, an aromatic ligand containing at least one perfluoroalkyl group and two carboxyl groups is divalent in the presence of water. When reacted with a transition metal ion, only one carboxyl group of the aromatic ligand reacted with the divalent transition metal ion (hydrophobic part), and the other carboxyl group protruded around this (hydrophilic part) It is thought that a complex is formed. The conditions for reacting such an aromatic ligand containing two carboxyl groups with a divalent transition metal ion are typical conditions for the synthesis of PCP. Usually, both carboxyl groups react. However, in the reaction of the present invention, as described above, one carboxyl group exists without reacting, and this plays an important role in the preparation of a material having adsorption ability. Such a phenomenon occurs because the reaction is performed under special conditions such as a hydrophobic fluorine-containing group, a hydrophilic carboxyl group, and a solvent containing water.

  Good results can be obtained by using a mixed solvent of a proton solvent such as alcohols and an amide solvent such as dimethylformamide as a solvent that can be used together with water. Protonic solvents such as alcohols and amide solvents such as dimethylformamide and dimethylacetamide dissolve divalent transition metal salts well, and further, by coordinating or hydrogen bonding to divalent transition metal ions and counter ions. Side reactions are suppressed by stabilizing divalent transition metal salts and suppressing rapid reaction with ligands. Examples of alcohols include aliphatic monohydric alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol and 2-butanol, and aliphatic dihydric alcohols such as ethylene glycol. Methanol, ethanol, 1-propanol, 2-propanol, and ethylene glycol are preferable because they are inexpensive and have high solubility of the divalent transition metal salt. Moreover, these alcohols may be used alone or in combination. Examples of amide solvents include dimethylformamide, diethylformamide, dibutylformamide, dimethylacetamide and the like. Dimethylformamide and diethylformamide are preferred in that the solubility of the divalent transition metal salt is high.

  The mixing ratio of the alcohols and the amide solvent is arbitrary from 99: 1 to 1:99 (volume ratio). From the viewpoint that the solubility of both the ligand and the metal salt is increased and the generation of by-products can be suppressed, the mixing ratio is 90:10 to 10:90 (volume ratio), and the reaction can be accelerated. 20-20: 80 (volume ratio) is preferable.

  As the organic solvent, another kind of organic solvent can be mixed and used in the mixed solvent of the alcohol and the amide solvent. The mixing ratio of the mixed solvent composed of the alcohol and the amide solvent to another organic solvent is preferably 30% or more from the viewpoint of improving the solubility of the metal salt and the ligand.

  In order to produce the fluorine-containing metal complex of the present invention, it is important that water is contained during the reaction, regardless of which solvent is used. The water content is 1 to 100% by volume, but 20 to 100% by volume, and more preferably 40 to 100% by volume is preferable in order to synthesize the fluorine-containing metal complex with high yield. The addition of water inhibits the formation of PCP and forms a fluorine-containing metal complex having a vacant carboxyl group.

  As a raw material for supplying a divalent transition metal ion, a divalent transition metal salt can be used. The copper lead salt which is a representative example of the divalent transition metal salt used in the method of the present invention may be any salt containing divalent copper ions, but has high solubility in a solvent. Copper nitrate, copper acetate, copper sulfate, copper formate, copper chloride, copper bromide, copper borofluoride are preferred, and copper nitrate, copper sulfate, copper borofluoride are particularly preferred in terms of high reactivity. .

  The zinc salt used in the method of the present invention may be a salt containing a divalent zinc ion. However, zinc nitrate, zinc acetate, zinc sulfate, silver salt are highly soluble in a solvent. Zinc acid, zinc chloride, and zinc bromide are preferable, and zinc nitrate and zinc sulfate are particularly preferable because of high reactivity.

  The cobalt salt used in the method of the present invention may be a salt containing a divalent cobalt ion, but in terms of high solubility in a solvent, cobalt nitrate, cobalt acetate, cobalt sulfate, silver Cobalt acid, cobalt chloride, and cobalt bromide are preferable, and cobalt nitrate and cobalt sulfate are particularly preferable in terms of high reactivity.

  The nickel salt used in the method of the present invention may be a salt containing a divalent nickel ion, but in terms of high solubility in a solvent, nickel nitrate, nickel acetate, nickel sulfate, silver Nickel acid nickel, nickel chloride, and nickel bromide are preferable, and nickel nitrate and nickel sulfate are particularly preferable in terms of high reactivity.

  The bidentate aromatic ligand having at least one perfluoroalkyl group and two carboxyl groups used for producing the fluorine-containing metal complex of the present invention is the bidentate aromatic coordination described above. A child can be used.

  In the method for producing a fluorine-containing metal complex of the present invention, a base can be added as a reaction accelerator. The base is presumed to accelerate the reaction by converting the carboxyl group of the ligand into an anion. Examples of the base include lithium hydroxide, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide and the like as inorganic bases. Examples of the organic base include triethylamine, diethylisopropylamine, pyridine, 2,6-lutidine and the like. Lithium hydroxide, sodium carbonate, sodium hydroxide, and pyridine are preferred because of their high reaction acceleration. The addition amount is preferably 0.1 to 6.0 mol in terms of the effect of accelerating the reaction with respect to the total moles of isophthalic acid used, and more preferably 0.5 to less in terms of side reactions. 4.0 moles.

  In the method for producing a fluorine-containing metal complex of the present invention, an organic acid can be added as a reaction control agent. It is considered that the organic acid controls the proper progress of the reaction by controlling the dissociation of the carboxyl group of the ligand as an acid. Aliphatic organic acids include monovalent acids such as acetic acid and propionic acid, divalent acids such as oxalic acid and malonic acid, and bicyclo [2,2,2] -octane-1,4-dicarboxylic acid. A cyclic carboxylic acid is mentioned. Examples of the aromatic organic acid include monovalent acids such as benzoic acid and 4-methylbenzoic acid. Of these, acetic acid, benzoic acid, and bicyclo [2,2,2] -octane-1,4-dicarboxylic acid, which have high solubility and are not highly coordinated to the divalent transition metal ion, are preferable. The amount added is preferably 0.1 to 12.0 mol in terms of the effect of the reaction with respect to the total mol of the ligand used, and more preferably 0.5 in terms of few side reactions. To 8.0 moles.

  In the reaction of the ligand with the divalent transition metal salt solution and the ligand, the divalent transition metal salt, ligand, These solutions may be mixed after preparing the ligands separately as solutions. The solution may be mixed by adding the ligand solution to the divalent transition metal salt solution or vice versa. Moreover, after laminating | stacking a bivalent transition metal salt solution and a ligand solution, you may mix by the method by natural diffusion. As a mixing method, it is not always necessary to use a solution, for example, a method in which a solid ligand is added to a divalent transition metal salt solution and a solvent is simultaneously added, or a divalent transition metal salt is charged into a reaction vessel. After that, various methods can be used so long as the reaction finally takes place in a solvent, such as injecting a solid or solution of the ligand and further injecting a solution for dissolving the divalent transition metal salt. A method is possible. However, the method of dropping and mixing the divalent transition metal salt solution and the ligand solution is industrially the most convenient and preferable. In any method, it is preferable to keep the reaction of the ligand and the divalent transition metal ion at an appropriate rate by allowing the reaction solution to stand after preparation.

  The concentration of the solution to be used is preferably 10 μmol / L to 4 mol / L, more preferably 100 μmol / L to 2 mol / L in the case of a divalent transition metal salt solution. The organic solution of the ligand is preferably 10 μmol / L to 3 mol / L, and more preferably 100 μmol / L to 2 mol / L. Even if the reaction is carried out at a concentration lower than this, the desired product can be obtained, but this is not preferable because the production efficiency is lowered. Further, at a concentration higher than this, the adsorption ability may be lowered.

  The mixing ratio of the divalent transition metal salt and ligand used in the reaction of the present invention is preferably a molar ratio of divalent transition metal: ligand of 1: 5 to 5: 1, and 1: 3. It is more preferably within a range of a molar ratio of ˜3: 3. In other ranges, the yield of the target product decreases, and unreacted raw materials remain, making it difficult to take out the target product.

  The reaction can be carried out using an ordinary glass-lined SUS reaction vessel and a mechanical stirrer. After completion of the reaction, since the fluorine-containing metal complex of the present invention is a crystalline solid, it is possible to produce a high-purity target substance by separating the target substance and the raw material by filtration and drying.

  Whether or not the fluorine-containing metal complex of the present invention is obtained by the above reaction can be confirmed by analyzing the reflection obtained by single crystal X-ray crystal analysis. The gas adsorption capacity of the gas adsorbent prepared using the fluorine-containing metal complex obtained by the above reaction can be measured using a commercially available gas adsorption apparatus.

  Since the coordination point of the fluorine-containing metal complex of the present invention consists of a carboxyl group, it is clear that a salt in which the hydrogen atom of the carboxyl group is substituted with a metal ion can be formed (hereinafter, including such a salt, simply “ (It is called a "fluorine-containing metal complex having a coordination point").

  The adsorbent prepared using the fluorine-containing metal complex of the present invention as a raw material can be prepared as follows.

  To the fluorine-containing metal complex, a metal salt is added, heated in a solvent, and the solid obtained after the reaction is filtered.

  As the metal salt, ions of transition metals such as copper, zinc, iron, nickel and cobalt, alkaline earth metals such as magnesium and calcium, and other divalent or higher metal ions such as aluminum and scandium can be used. The type of metal ion may be the same as or different from the metal ion contained in the fluorine-containing metal complex.

  The metal salt may be any salt containing the target metal ion, but in terms of high solubility in a solvent, nitrate, acetate, sulfate, formate, chloride, bromide, Borofluoride is preferred, and nitrate, sulfate, and borofluoride are particularly preferred in terms of high reactivity.

  Preferred metal ions for reacting with a fluorine-containing metal complex to form a gas adsorbent include divalent transition metal ions. Since the divalent transition metal ion stably forms a coordination structure similar to that of the fluorine-containing metal complex of the present invention, it can be easily reacted with the fluorine-containing metal complex of the present invention to prepare an adsorbent. . Specific examples of divalent transition metal ions include cobalt ions, nickel ions, zinc ions, and copper ions. From the viewpoint of chemical stability of the obtained fluorine-containing metal complex, copper ions and zinc ions are preferable. Copper ions are particularly preferred from the viewpoint of yield.

  The molar ratio of the fluorine-containing metal complex to the metal salt used for the reaction is preferably 10: 1 to 1:10, and more preferably 3: 1 to 1: 3 from the viewpoint of high yield.

  In particular, a divalent transition metal ion different from the divalent transition metal ion contained in the fluorine-containing metal complex is used as the metal ion used when forming the gas adsorbent by reacting with the fluorine-containing metal complex of the present invention. Thus, the obtained gas adsorbent (the gas adsorbent obtained in the present invention is not limited to PCP, but may be PCP) is the ligand used to form the fluorine-containing metal complex of the present invention. It is possible that the gas adsorbent (PCP) is different from the gas adsorbent (PCP) obtained directly from (for example, isophthalic acid derivatives and terephthalic acid derivatives) and various other divalent transition metal ions. This is a unique effect of the fluorine-containing metal complex of the present invention. Specifically, the fluorine-containing metal complex using the first divalent transition metal ion and the second divalent transition metal ion are reacted to form the first divalent transition metal ion and the second 2 It is possible that valent transition metal ions can be formed in a certain proportion (eg, 1: 1) and in a regular order (eg, alternating) to form a placed PCP.

  The divalent transition metal salt used in the method for preparing the adsorbent by reacting the fluorine-containing metal complex of the present invention with the divalent transition metal salt was used in the synthesis of the fluorine-containing metal complex of the present invention. And reference is made to the above description in connection with the synthesis of the fluorine-containing metal complex of the present invention.

  As the solvent used for forming the gas adsorbent by reacting the fluorine-containing metal complex of the present invention with a transition metal ion, the same organic solvent as used for the production of the fluorine-containing metal complex of the present invention may be used. it can. In the production of the gas adsorbent, water may be contained in addition to the organic solvent as the solvent. When water is contained, the range of 1 to 30% by mass in the solvent is preferable.

  A base or an organic acid can be added as a reaction accelerator. The base and organic acid that can be used in the method for preparing the adsorbent of the present invention can be the same as the base and organic acid used in the synthesis of the fluorine-containing metal complex of the present invention. Reference is made to the description given above in connection with the synthesis of fluorine-containing metal complexes.

In order to prepare the adsorbent of the present invention, the method of reacting (mixing) the fluorine-containing metal complex of the present invention with a metal ion can be the same as in the synthesis of the fluorine-containing metal complex of the present invention. The methods described above in connection with the synthesis of the fluorine-containing metal complexes of the invention can be used.
In any reaction (mixing) method, it may be preferable to keep the reaction of the fluorine-containing metal complex and the metal ion at an appropriate rate by allowing the reaction solution to stand after preparation. Here, the standing temperature is preferably −20 ° C. to 180 ° C., and −20 ° C. to 150 ° C. in that generation of by-products can be suppressed. The standing time is preferably 1 hour to 3 months, and more preferably 4 hours to 2 months from the viewpoint that there are few by-products.

  The concentration of the solution used for preparing the adsorbent of the present invention can also be the same as in the synthesis of the fluorine-containing metal complex of the present invention.

  The reaction for preparing the adsorbent of the present invention can be carried out using an ordinary glass-lined SUS reaction vessel and a mechanical stirrer. After completion of the reaction, since the adsorbent prepared from the fluorine-containing metal complex of the present invention is a crystalline solid, the target substance and raw material are separated by filtration and drying to produce a high-purity target substance. It is possible.

  The gas adsorption capacity of the gas adsorbent obtained by the above reaction can be measured using a commercially available gas adsorption apparatus.

  The fluorine-containing metal complex of the present invention is a complex having in its molecule a very hydrophobic portion called a fluorine-containing group and a very hydrophilic portion called a carboxyl group. In order to synthesize such a complex with high yield, it is necessary to prevent all carboxyl groups on the ligand from reacting with a divalent transition metal ion to form PCP. It is estimated that the contained water plays an important role. However, the present invention is not limited by theory, and the characteristics of the fluorine-containing metal complex of the present invention are not limited by this theory.

The method for preparing a fluorine-containing metal complex having a coordination point according to the present invention has various conditions and cannot be determined uniquely, but here, it will be described based on examples.
For powder X-ray diffraction measurement, a powder X-ray apparatus DISCOVER D8 with GADDS manufactured by Bruker AX Co., Ltd. was used.

Example 1
Copper nitrate trihydrate 0.01 mmol, 5-pentafluoroethylisophthalic acid (isophthalic acid having a normal C ₂ F ₅ group at the 5-position) 0.01 mmol, water 5 mL of Teflon (registered trademark) Placed in a container and heated at 150 ° C. for 2 days.

  After coating the obtained single crystal with Palaton so as not to be exposed to the atmosphere, a single crystal measuring device manufactured by Rigaku Co., Ltd. )) (Irradiation time 8 seconds, d = 45 mm, 2θ = −20, temperature = −180 ° C.), and the obtained diffraction image is analyzed with analysis software, analysis software “CrystalStructure” manufactured by Rigaku Corporation. As a result, it was found that a fluorine-containing metal complex as shown in FIG. 1 was obtained (a = 11.6112 (18), b = 11.6857 (17), c = 17. 521 (3); α = 91.993 (2), β = 101.470 (3), γ = 90.664 (3); space group = P1).

(Preparation of adsorbent from fluorine-containing metal complex)
200 mg of the solid obtained in the same manner as above, 1.0 mmol of zinc nitrate trihydrate, 7 mL of dimethylformamide, and 7 mL of ethanol were placed in a pressure vessel made of Teflon (registered trademark) and reacted at 120 ° C. for 24 hours. The obtained solid was filtered, washed with ethanol, and vacuum dried at room temperature to obtain 156 mg of a blue-green solid. As a result of analysis by fluorescent X-ray, copper ions and zinc ions were contained in substantially equal amounts.

Example 2
0.01 mmol of zinc nitrate trihydrate, 0.01 mmol of 5-heptadecafluorooctylisophthalic acid (isophthalic acid having a normal C ₈ F ₁₇ group at the 5-position), ethanol / water (mixing volume ratio 1/1) 5 mL was placed in a pressure vessel made of Teflon (registered trademark) and heated at 150 ° C. for 2 days. From the obtained single crystal, it was found by X-ray diffraction analysis that a fluorine-containing metal complex similar to that shown in FIG. 1 was obtained. (A = 12.2633 (9), b = 10.9835 (7), c = 16.635 (6); α = 92.588 (4), β = 103.522 (6), γ = 88. 376 (7); space group = P1)

(Preparation of adsorbent from fluorine-containing metal complex)
200 mg of the solid obtained by the same method as above, 1.0 mmol of copper nitrate trihydrate, 7 mL of dimethylformamide, and 7 mL of ethanol were placed in a pressure vessel made of Teflon (registered trademark) and reacted at 120 ° C. for 24 hours. The obtained solid was filtered, washed with ethanol, and vacuum dried at room temperature to obtain 156 mg of a blue-green solid. As a result of analysis by fluorescent X-rays, almost equal amounts of zinc ions and copper ions were contained.

Example 3
Copper nitrate trihydrate 0.01 mmol, 5-trifluoromethylisophthalic acid (isophthalic acid having a normal CF ₃ group at the 5-position) 0.01 mmol, methanol / water (mixing volume ratio 1/1) 5 mL, water 0.01 mmol of lithium oxide was put in a Teflon (registered trademark) pressure vessel and heated at room temperature for 1 day. From the obtained single crystal, it was found by X-ray diffraction analysis that the same fluorine-containing metal complex as shown in FIG. 1 was obtained (a = 13.2572 (8), b = 13.6356 (7)). , c = 17.7465 (7); α = 91.855 (9), β = 102.454 (3), γ = 92.745 (9); space group = P1)

(Preparation of adsorbent from fluorine-containing metal complex)
200 mg of the solid obtained in the same manner as above, 1.0 mmol of zinc nitrate trihydrate, 7 mL of dimethylformamide, and 7 mL of ethanol were placed in a pressure vessel made of Teflon (registered trademark) and reacted at 120 ° C. for 24 hours. The obtained solid was filtered, washed with ethanol, and vacuum dried at room temperature to obtain 156 mg of a blue-green solid. As a result of analysis by fluorescent X-ray, copper ions and zinc ions were contained in substantially equal amounts.

Example 4
A pressure vessel made of Teflon (registered trademark) containing 0.01 mmol of nickel nitrate trihydrate, 0.01 mmol of 5-undecafluoropentaterephthalic acid (terephthalic acid having a C ₅ F ₁₁ group at the 5-position) and 5 mL of water And heated at 150 ° C. for 2 days. From the obtained single crystal, it was found by X-ray diffraction analysis that a fluorine-containing metal complex similar to that shown in FIG. 1 was obtained except that isophthalic acid was replaced with terephthalic acid. (A = 13.3345 (4), b = 12.2754 (7), c = 17.976 (4); α = 91.987 (7), β = 102.634 (8), γ = 92. 048 (3); space group = P1).

(Preparation of adsorbent from fluorine-containing metal complex)
200 mg of the solid obtained by the same method as above, 1.0 mmol of copper nitrate trihydrate, 7 mL of dimethylformamide, and 7 mL of ethanol were placed in a pressure vessel made of Teflon (registered trademark) and reacted at 120 ° C. for 24 hours. The obtained solid was filtered, washed with ethanol, and vacuum dried at room temperature to obtain 156 mg of a blue-green solid. As a result of analysis by fluorescent X-ray, nickel ions and copper ions were contained in substantially equal amounts.

Comparative Example 1
The reaction was carried out in the same manner as in Example 1, except that 0.01 mmol of zinc nitrate trihydrate was also present as a metal salt. As a result of analysis by fluorescent X-ray, copper ions and zinc ions were contained at a ratio of about 3: 1.

<Results of gas adsorption>
The gas adsorption property of the obtained solid was evaluated using a BET automatic adsorption device (Bell Mini II manufactured by Nippon Bell Co., Ltd.) (measuring temperature: 195K and 273K for carbon dioxide, 77K for oxygen and nitrogen). Prior to the measurement, the sample was vacuum-dried at 423 K for 6 hours to remove solvent molecules that may remain in a trace amount.

  Table 1 shows gas adsorption characteristic absorption of adsorbents prepared from the fluorine-containing metal complexes obtained in Examples 1 to 4.

  None of them adsorbs almost nitrogen, but absorbs carbon dioxide and oxygen well, and has a relatively large amount of carbon dioxide adsorbed at room temperature, indicating that it can be used as a gas separation and storage material.

  In the fluorine-containing metal complex of the present invention, a large number of micropores formed by ligand alignment are present inside the substance. Taking advantage of this porosity, specific adsorption of gas having affinity for fluorine atoms such as carbon dioxide and especially oxygen is possible, and it can be suitably used for separation and storage of these gases.

Claims (10)

The following formula (I)
[M ₂ X ₄ ] (I)
(In the formula, M is one kind of metal ion selected from divalent transition metal ions , and X is an isophthalate containing at least one perfluoroalkyl group having 1 to 10 carbon atoms and two carboxyl groups. An aromatic ligand selected from acid or terephthalic acid.)
Wherein the four aromatic ligands coordinate to the divalent transition metal ion to form a paddle wheel structure, and the four aromatics In each group ligand, one of the two carboxyl groups is coordinated to the divalent transition metal ion, and the other carboxyl group is coordinated to the divalent transition metal ion. A fluorine-containing metal complex or a salt thereof.   The fluorine-containing metal complex or a salt thereof according to claim 1, wherein M is selected from zinc ion, cobalt ion, copper ion and nickel ion. A perfluoroalkyl group having 1 to 10 carbon atoms is CF ₃ , C ₂ F ₅ , n-C ₃ F ₇ , n-C ₄ F ₉ , n-C ₅ F ₁₁ , n-C ₈ F ₁₇ , n. selected from -C ₁₀ F _21, a fluorine-containing metal complex or salt thereof according to claim 1 or 2. Organic solvent molecules and water molecules coordinate to formula (II)
[M ₂ X ₄ Lz] (II)
(In the formula, M is one kind of metal ion selected from divalent transition metal ions , and X is an isophthalate containing at least one perfluoroalkyl group having 1 to 10 carbon atoms and two carboxyl groups. An aromatic ligand selected from acid or terephthalic acid, L is an organic solvent molecule or water molecule, and z is 0 to 4 but not 0.)
Wherein the four aromatic ligands coordinate to the divalent transition metal ion to form a paddle wheel structure, and the four aromatics In each group ligand, one of the two carboxyl groups is coordinated to the divalent transition metal ion, and the other carboxyl group is coordinated to the divalent transition metal ion. A fluorine-containing metal complex or a salt thereof.   The fluorine-containing metal complex or a salt thereof according to claim 4, wherein L is a water molecule.   A gas adsorbent obtained by reacting the fluorine-containing metal complex according to any one of claims 1 to 5 or a salt thereof with a divalent transition metal salt.   A method for preparing a gas adsorbent by reacting the fluorine-containing metal complex according to any one of claims 1 to 5 or a salt thereof with a divalent transition metal salt.   The method for preparing a gas adsorbent according to claim 7, wherein a fluorine-containing metal complex or a salt thereof is reacted with a metal salt different from a divalent transition metal constituting the fluorine-containing metal complex or a salt thereof.   A gas separator using the gas adsorbent according to claim 6.   A gas storage device using the gas adsorbent according to claim 6.