JP5516141B2 - Polymer metal complex, gas adsorbent, gas separation device and gas storage device - Google Patents

Description

  The present invention relates to a polymer metal complex and its use as a gas adsorbent, and a gas separation device and a gas storage device using the same.

  Gas storage using a gas adsorbent has a characteristic that a large amount of gas can be stored at a low pressure as compared with pressurized storage or 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 (Patent Document 1, Non-Patent Document 1).

  However, conventionally proposed gas adsorbents are not sufficiently satisfactory in terms of gas adsorption amount and workability, and development of gas adsorbents having more excellent characteristics is desired. In particular, an increase in the amount of adsorbed gas is an important issue.

  In order to increase the gas adsorption amount, methods such as reducing the pore diameter and increasing the pore volume have been employed (Non-patent Document 2). However, when the pore diameter is simply reduced and the pore volume is increased, the gas adsorption force becomes too strong, that is, adsorption occurs at a low pressure (for example, a relative pressure of 0.1 or less). In this case, there is a problem that it is difficult to desorb the adsorbed gas due to an excessively strong adsorption force.

  On the other hand, polymer metal complexes that cause a dynamic structural change due to an external stimulus have been reported (Non-patent Documents 3 and 4). Among these dynamic structural change metal complexes, when a polymer metal complex having a polymer structure and a complex having pores inside is used as a gas adsorbent, gas is not adsorbed up to a certain pressure, A peculiar phenomenon (gate phenomenon) that gas adsorption starts when a certain pressure is exceeded is observed. As for desorption of gas, the gas is not desorbed up to a certain pressure, but a phenomenon in which the gas is desorbed abruptly when the pressure becomes lower than a certain pressure has been observed at the same time. Such a material has been increasingly used as a gas adsorbent because it can absorb and desorb gas at an appropriate pressure (Non-patent Documents 5 and 6).

  Polymer metal complexes that have a structure in which two-dimensional planes are stacked and cause dynamic structural changes are used for gas adsorption and separation. Does not desorb gas, but the phenomenon of abrupt desorption of gas when the pressure falls below a certain pressure is the gas adsorption, separation, and storage, such as the ability to hold gas at a low pressure and discharge the gas at a relatively high gas pressure. It can be said that it is a preferable property as a material.

  Polymer metal complexes that have a structure in which two-dimensional planes are stacked and cause dynamic structural changes include sites with weak interactions such as hydrogen bonds and π-π interactions in the molecule. Is considered to cause structural changes. However, it is not well understood what factors actually cause such an unusual phenomenon. By the way, depending on the gas pressure, gas adsorption starts when the pressure exceeds a certain pressure, or gas is not desorbed up to a certain pressure, but suddenly desorbs when the pressure falls below a certain pressure. As to whether the gas is adsorbed, various types are conceivable as shown in FIG. 1A or FIG. 1B, for example.

  1A and 1B both show a phenomenon in which gas adsorption starts when a certain pressure is exceeded, and can be regarded as so-called gate adsorption. By the way, in FIG. 1A, the amount of adsorption gradually increases as the gas pressure increases, whereas in FIG. 1B, the amount of adsorption increases rapidly as the gas pressure increases. In the substance showing the adsorption mode as shown in FIG. 1A, it is necessary to increase the gas pressure to some extent in order to adsorb a large amount of gas, while in the substance showing the steep adsorption mode as shown in FIG. There is an advantage that a large amount of gas can be adsorbed and desorbed with slight gas pressure fluctuation. However, as mentioned above, polymer metal complexes that have a structure in which two-dimensional planes are stacked and cause dynamic structural changes have many unclear points in the mechanism of gas adsorption and desorption, and what composition and structure should be used. Thus, it is not known whether the adsorption mode as shown in FIG. 1B can be realized (Non-patent Documents 7 and 8).

In Non-Patent Document 9, a metal complex having Cu as a central metal and bipyridine and CF ₃ BF ₃ as ligands is under investigation. However, the conventional polymer metal complex including the polymer metal complex described in Non-Patent Document 9 has a sufficiently large slope of the adsorption isotherm when the horizontal axis is pressure and the vertical axis is the amount of adsorption. It cannot be said that further improvement is desired.

JP 2000-109493 A

Susumu Kitagawa, Integrated Metal Complex, Kodansha Scientific, 2001, pages 214-218 Matzger, A.J. et al., Angew. Chem. Int. Ed., (2008), 47, 677. Kazuhiro Uemura, Susumu Kitagawa, Future Materials (2002) December issue, 44 Ryotaro Matsuda, Susumu Kitagawa, Petrotec (2003) Vol. 26, No. 2, pages 97-104 Kitagawa, S. et al., Angewandte Chem. Int. Ed. (2003) 428 Seki, K. et al., Phys. Chem. Chem. Chem. Phys., (2002) 4, 1968 kondoh, et ak., Eur. J. Chem. 2009, 15, 7549 Nano Letters 2006. 6. 11. 2581 Hirofumi Kanoh et al., Journal of Colloid and Science 334 (2009) p.1-7

  The present invention has been made in view of the above circumstances, and a polymer metal complex capable of adsorbing and desorbing a large amount of gas at a lower pressure and a slight gas pressure fluctuation, with a sufficiently large inclination of the adsorption isotherm, and An object of the present invention is to provide a gas adsorbent provided with the polymer metal complex. 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 a result of intensive research to solve the above-mentioned problems, the present inventors have found that a two-dimensional planar case-type crystal structure has a high concentration containing a counter ion having fluorine atoms at both ends. It has been found that a molecular metal complex has a gas storage capacity under specific conditions, and also has the ability to rapidly adsorb and desorb gas by an external stimulus, and its adsorption mode is steep at an appropriate pressure. I found. Furthermore, polymer metal complex having this feature, on both ends as the raw material and the counter ions having a fluorine atom PF ₆ ^- a metal salt containing both ions by using as a raw material, can be more easily synthesized As a result, the present invention has been completed.

That is, the present invention has a two-dimensional planar case-type crystal structure, contains a counter ion having fluorine atoms at both ends, and has an absorption intensity of 1056 cm ⁻¹ and an absorption intensity of 1614 cm ⁻¹ by infrared spectroscopy. Is a polymer metal complex having a ratio equal to or higher than a certain value, and also relates to a gas adsorbent having a polymer metal complex, a gas storage device containing the gas adsorbent therein, and a gas separation device .

That is, the present invention is as described in [1] to [7] below.
[1] A two-dimensional planar lattice stacked crystal structure having a unit structure of the following formula (1), wherein the absorption intensity at 1056 cm ⁻¹ by infrared spectroscopy is 1.4 times or more the absorption intensity at 1614 cm ^−1. A polymeric metal complex characterized in that
[X (CF ₃ BF ₃ ) ₂ L ₂ ] (1)
(Wherein, X is a divalent ion of cobalt, nickel, or copper, and L is an organic ligand.)
[2] The polymer metal according to [1], wherein the organic ligand L is one or more of 4,4′-bipyridine, 3,3′-bipyridine, and 3,4′-bipyridine. Complex.
[3] _CF 3 BF ₃ ion and PF ₆ ^- ions, characterized in that the metal salt is synthesized as a raw material that includes [1] or [2] polymer metal complex according.
_{[4] (CF 3 BF 3} ) - ion and PF ₆ ^- molar ratio of _ions, (CF 3 _BF 3) ^- with respect to ions 100, PF ₆ ^- ions, characterized in that 7.5 or less [ [3] The polymer metal complex according to [3].
[5] A gas adsorbent comprising the polymer metal complex according to any one of [1] to [4].
[6] A pressure swing adsorption type gas separation apparatus comprising the gas adsorbent according to [5].
[7] A gas storage device in which the gas adsorbent according to [5] is accommodated.

In the polymer metal complex of the present invention, the absorption intensity at 1056 cm ⁻¹ by infrared spectroscopy is more than 1.4 times the absorption intensity at 1614 cm ⁻¹ , so that a larger amount of gas than a conventional polymer metal complex is used at a slight gas pressure. It is possible to adsorb and desorb under fluctuations. In addition, it is possible to provide a gas storage device and a gas separation device in which a gas adsorbent comprising the polymer metal complex of the present invention is housed.

  The polymer metal complex of the present invention can be applied to various uses by utilizing the special properties relating to gas adsorption and desorption. For example, when applied to a gas adsorbent in a pressure swing adsorption method (hereinafter referred to as “PSA method”) gas separation device, by utilizing the characteristics of the gas adsorbent of the present invention, very efficient gas separation can be achieved. 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 application of the polymer 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 such as a commercial gas tank, a consumer gas tank, or a vehicle fuel tank, the gas storage pressure during transportation or storage can be dramatically reduced. Is possible.
As an effect resulting from the fact that the gas storage pressure during transportation or storage can be reduced, an improvement in the degree of freedom of the shape of the gas storage device is first 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. For this reason, the pressure resistance of a container can be made low and the shape of a gas storage apparatus can be designed freely to some extent.
This effect is great when the gas storage device of the present invention is used as a fuel gas tank for vehicles such as automobiles. When the gas storage device of the present invention is used as a fuel tank, restrictions on pressure resistance are relaxed as described above, and the shape can be designed freely to some extent. Specifically, the shape of the gas storage device can be adjusted so as to fit the shape of wheels, seats, and the like in the vehicle. As a result, it is possible to obtain various benefits such as miniaturization of the vehicle, securing of luggage space, and improvement of fuel consumption by reducing the weight of the vehicle.

  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 apparatuses is not excluded, and any apparatus is included in the technical scope of the present invention as long as the gas polymer metal complex of the present invention is used.

FIG. 1A is a graph showing the relationship between the relative pressure during gas adsorption and the amount of gas adsorption, and shows a relatively gentle adsorption isotherm. FIG. 1B is a graph showing the relationship between the relative pressure during gas adsorption and the amount of gas adsorption, and shows a relatively steep adsorption isotherm. FIG. 2A is a schematic plan view showing the structure of the polymer metal complex of the present invention. FIG. 2B is a schematic perspective view showing the structure of the polymer metal complex of the present invention. FIG. 3 is a graph showing the relationship between the relative pressure during gas adsorption and the gas adsorption amount, and is a schematic diagram for explaining the adsorption start pressure, the adsorption completion pressure, and the maximum gas adsorption amount.

  The polymer metal complex of the present invention has a unit structure represented by the following formula (1) and has a two-dimensional planar lattice stacked crystal structure. In formula (1), X is a divalent ion of cobalt, nickel, or copper, and L is an organic ligand.

[X (CF ₃ BF ₃ ) ₂ L ₂ ] (1)

  X may be any of cobalt, nickel, and copper, but copper ions are preferred from the viewpoint of easily forming a polymer metal complex by mixing with a ligand.

Further, the counter ion represented by (CF ₃ BF ₃ ) ⁻ in the formula (1) is a counter ion having a plurality of fluorine atoms at both ends. This counter ion refers to an ion having two or more atoms in the center and a plurality of fluorine atoms at both ends. The general formula is represented by the following formula (2).

F _m -A-B-F _n (2)

In formula (2), m and n are the number of fluorines, and A and B represent atomic groups. A and B may be the same atomic group or different atomic groups. Since m and n vary depending on the valences of A and B, they cannot be determined uniquely, but they must be 2 or more. When n is 1, slipping between layers of the laminate due to structural change is insufficient, but abrupt structural change occurs and steep gas adsorption occurs only by changing the number of fluorine from one to two. . However, even if the fluorine is changed from 2 to 3, or 4, the structure does not change suddenly, and the gas adsorption effect is not as sharp as when the number is changed from 1 to 2. Therefore, the number of two or more may be determined according to the required amount of gas adsorption. Specific examples of the formula (2) include CHF ₂ BHF ₂ ⁻ , CF ₃ BHF ₂ ⁻ , CHF ₂ BF ₃ ⁻ , CF ₃ BF ₃ ^{− and the} like. However, in the present invention, the absorption and emission characteristics are steep. To CF ₃ BF ₃ ⁻ .

A and B are not directly bonded and may contain some functional group. Examples of such anions include (CF ₃ CH ₂ BF ₃ ) ⁻ , (CF ₃ CF ₂ BF ₃ ) ⁻ , (CF ₃ CF ₂ CF ₂ BF ₃ ) ⁻ , (CF ₃ SO ₂ BF ₃ ) ⁻ Etc. In the present invention, it is defined as (CF ₃ CF ₂ BF ₃ ) ^{− in} that the number of fluorine atoms is large from the viewpoint of easily causing a structural change and the water solubility does not become too low.

(CF ₃ BF ₃ ) ⁻ may be finally present in the structure of the polymer metal complex of the present invention. That is, for example, as in the case of using Cu (CF ₃ BF ₃ ) ₂ as the raw material metal salt, these ions may be present alone in the reaction process, or Cu (BF ₄ ) As in the case of using ₂ and KCF ₃ BF ₃ together, these ions may coexist with another anion in the reaction process.

Specific examples of a metal salt containing an anion having a plurality of fluorine atoms at both ends, which can be used in the present invention, include a salt containing an anion having a plurality of fluorine atoms at both ends. Cu (CF ₃ BF ₃ ) ₂ , Ni (CF ₃ BF ₃ ) ₂ , Co (CF ₃ BF ₃ ) ₂ , Cu (CF ₃ CH ₂ BF ₃ ) ₂ , Ni (CF ₃ CH ₂ BF ₃ ) ₂ , Examples thereof include Co (CF ₃ CH ₂ BF ₃ ) ₂ .

Further, as described above, it is also possible to produce the polymer metal complex of the present invention by coexisting an anion having a plurality of fluorine atoms at both ends with another anion, in which case Alkali metal salts such as NaCF ₃ BF ₃ , KCF ₃ BF ₃ , NaCF ₃ CH ₂ BF ₃ , KCF ₃ CH ₂ BF _{3 and the} like containing a counter ion having a plurality of fluorine atoms, and Cu (BF ₄ ) ₂ , Cu (CF ₃ SO ₃ ) ₂ , Ni (BF ₄ ) ₂ , Ni (CF ₃ SO ₃ ) ₂ , Co (BF ₄ ) ₂ , Co (CF ₃ SO ₃ ) _2, etc. an ion, BF ₄ ^- or _(CF 3 _SO 3) ^- may be used in combination salt formed from counterions such.

  Thus, when two types of salts are mixed and used, in order to ensure that the necessary amount of anions each having a plurality of fluorine atoms at both ends is incorporated into the polymer metal complex, both ends are used. The amount of the anion having a plurality of fluorine atoms must be 1 mol or more, preferably 2 mol or more, relative to the other anions that coexist. When only 1 mole or less is used, anions other than the anions each having a plurality of fluorine atoms at both ends may be incorporated into the polymer metal complex and the purity may be lowered.

  L in the formula (1) is an organic ligand, and a ligand having two coordination sites at relatively distant positions in the molecule, that is, 4,4′-bipyridine, 3,3′- Bipyridine and 3,4'-bipyridine may be mentioned. In the present invention, 4,4'-bipyridine is preferable because it easily forms a polymer complex.

In the synthesis of the polymer metal complexes of the present invention, PF ₆ ^- ions, to coexist in the anion with each end a plurality of fluorine atoms it is preferred from the viewpoint of adsorption characteristics control. Specific coexistence method, anions and PF ₆ having a plurality of fluorine atoms respectively (1) at both ends ^- to use a metal salt containing both ions. (2) a metal salt containing an anion each having a plurality of fluorine atoms at both ends, PF ₆ ^- using a plurality of types of metal salts containing ions. Either method may be used.

To give a specific example of the method (2), a metal ion intended to be incorporated into a polymer metal complex such as Cu (CF ₃ BF ₃ ) ₂ and a plurality of fluorine atoms at both ends are provided. to a salt with an anion, as the Cu _{(PF 6) 2,} or a method of adding a salt of the same metal ions and PF _6, NaPF ₆ and an alkali metal ion and PF _6, such as KPF ₆ ^- ion PF ₆ that include methods to add proper amount of salt comprising ^- ions in the reaction solution, it is sufficient to substantially coexist and anion having each end a plurality of fluorine atoms, coexistence method and addition method It is not limited to.

PF ₆ ^- The amount of ions coexist, the anions present invention having a respective plurality of fluorine atoms at both ends _(CF 3 _BF 3) ^- and PF ₆ ^- molar ratio of ions 100: 7.5 to 100: 0.3 is preferable, and more preferably 100: 3.5 to 100: 0.7%. Suitable amount PF ₆ ^- the coexistence of ions, the response of the amount of gas adsorption-desorption to gas pressure change in the polymer metal complex obtained becomes steeper.

PF ₆ ^- as a mechanism to respond in the amount of gas adsorption-desorption to gas pressure change in the polymer-metal complex becomes steeper the coexistence of ions, when the polymer metal complex of interest is formed in solution, a small amount It is presumed that the presence of these different ions controls the orientation of the anion having a plurality of fluorine atoms at both ends, thereby forming a polymer metal complex with higher steric uniformity. Thus, PF ₆ ^- ions, as a cofactor of the microstructure control of the polymer-metal complex, to act at the time of manufacture, finally PF in the obtained polymer metal complex ₆ ^- exist ions There is no need to be.

In the synthesis of the polymer metal complex, PF ₆ ^- By the coexistence of ions, absorption intensity of 1056cm ^-1 in infrared spectroscopy is more than 1.4 times the absorption intensity of 1614cm ^-1.
That is, in the infrared spectroscopic data measured by the diamond single reflection ATR method, the absorption intensity of 1056 cm ⁻¹ attributed to (CF ₃ BF ₃ ) ⁻ ion is the absorption intensity of 1614 cm ⁻¹ attributed to bpy ( When both are 1.4 times or more of T% (uncorrected), steeper gas adsorption occurs. This as a result of the microstructure i.e. ions sequence of polymer metal complex is controlled, (CF ₃ BF ₃₎ ^- is presumed that the strength of the ion is strengthened.

Since the polymer metal complex of the present invention is a porous body, when it touches an organic molecule such as water, alcohol or ether, it contains water or an organic solvent in the pore, or in some cases, between the metal ion and the ligand. Receives insertion of water or organic solvent.
For example, it may be changed to a complex complex having a unit structure represented by the following formula (3). However, organic molecules such as water, alcohol, and ether in these complex complexes are only weakly bonded to the polymer metal complex, and are removed by pretreatment such as drying under reduced pressure when used as a gas adsorbent. It returns to the complex having the unit structure represented by the original formula (1). Therefore, even a complex having a unit structure represented by the formula (3) can be regarded as essentially the same as the polymer metal complex of the present invention. In formula (3), L is an organic ligand, Z is an organic molecule such as water, alcohol or ether, and m is 0.5 or more.

[X (CF ₃ BF ₃ ) ₂ L ₂ Z _m ] (3)

The polymer metal complex of the present invention has a two-dimensional planar lattice stacked crystal structure composed of a metal complex having the unit structure shown in (1) above. The metal complex having the unit structure shown in the above (1) is a complex having the metal X as a central element, and (CF ₃ BF ₃ ) and L are coordinated to the metal M two by two. Metals M and L form a planar lattice structure, and L is coordinated above and below the metal M. A plurality of planar lattice structures are stacked on each other to form a two-dimensional planar lattice stacked crystal structure. When planar lattice structures are stacked on each other, it is estimated that a ligand L included in the planar lattice structure interacts with another planar lattice structure to form a two-dimensional planar lattice stacked crystal structure. The It is estimated that a space is formed between the metal complexes, and gas molecules are adsorbed in this space. In addition, in this specification, a substance having a two-dimensional planar lattice layered crystal structure consisting of a metal complex because a large number of molecules consisting of a metal complex gather and coordinate with each other like a polymer compound to form a crystal structure. Is called a polymer metal complex.

"Two-dimensional laminated structure"
As described above, the two-dimensional laminated structure of the polymer metal complex referred to in the present invention is a square lattice composed of metal ions and ligands, which is the basic unit of the polymer metal complex as shown in FIG. 2A. The thing which spread on the two-dimensional plane points out what was laminated | stacked as shown to FIG. 2B.

  Here, for the sake of simplification, the lattice is shown to be composed of a square, but it may be a rectangle, a tall shape, or the like as long as it can be regarded as a topologically identical square. In addition, the plane does not mean a geometrically strict plane, and it is only necessary to form a plane on which each layer can be substantially stacked. In FIG. 2B, only three layers are extracted for simplification, but the number of layers is not particularly limited as long as a polymer complex that is substantially unnecessary for the solvent is formed. .

"Gas adsorbent"
The gas adsorbent of the present invention is a gas adsorbent in which an adsorption / desorption isotherm relating to at least one gas exhibits a hysteresis loop. That is, the gas pressure-gas adsorption amount curve at the time of adsorption is different from the gas pressure-gas adsorption amount curve at the time of desorption.

  The peculiarity of the hysteresis loop composed of the gas pressure-gas adsorption amount curve of the gas adsorbent of the present invention will be described with reference to the drawings.

  In the conventional gas adsorbent, the gas adsorption amount increases as the gas pressure increases, and the pressure-adsorption amount curve during adsorption coincides with the pressure-adsorption amount curve during desorption. On the other hand, in the gas adsorbent of the present invention, the pressure-adsorption amount curve at the time of gas adsorption shows a hysteresis loop.

The mechanism by which such a hysteresis loop appears has not yet been fully understood. As a possible mechanism, it is considered that a lattice layer of a 2D square grid composed of metal ions and a ligand is laminated, and that these layers have an important function (see Zawarotoko, MJ, Crystal Engineering 2 (1999), 37).
In the case where the layers are deviated and laminated, there is no substantial pore in the compound, and gas adsorption does not occur. On the other hand, when the layers are stacked without shifting, vacancies occur and gas adsorption occurs. That is, the mechanism of rapid gas adsorption can be estimated as follows.
When there is no gas or when the pressure is low, the layers are laminated, and when the gas pressure is increased, a phase transition occurs in the laminated structure where the layers are displaced, and the gas is rapidly adsorbed in the pores, It is stabilized with. On the other hand, it is considered that the mechanism of rapid gas release becomes unstable due to a decrease in gas pressure, a phase transition opposite to the above occurs, and gas is released.
And, since the pore structure of the complex changes between gas adsorption and gas release, a hysteresis loop occurs (Seiichi Kondo, Tatsuo Ishikawa, Ikuo Abe, Adsorption Chemistry, Maruzen Co., Ltd., pages 53-57). ).

According to this estimation, the interaction between the layers has a great influence on the likelihood of misalignment. In fact, many polymer metal complexes in which a so-called 2D square grid lattice layer is laminated are known, but almost all of them do not absorb gas, or even if absorbed, rapid absorption of gas such as the compound of the present invention. And no hysteresis loop of gas adsorption / desorption with release (for example, Kitagawa, S., Chemistry-A European Journal (2002), 8 (16), 3586-3600, Zaworotko, MJ, Chem. Commun. ( 1999) 1327, Roye, H.-C., Angewandte Chem. Int. Ed. (2002) 583, Kitagawa, S., J. Am. Chem. Soc., (2002) 2568).
For this reason, it is considered that metal ions and counterions play an important role as control factors for the shift between layers for the gas adsorption ability development as in the present invention, but the detailed mechanism is unknown.

The polymer metal complex having a unit structure represented by the formula (1) of the present invention is obtained by dissolving a metal salt containing X and CF ₃ BF ₃ and an organic ligand in a solvent and mixing them in a solution state. Can be manufactured.

As a solvent for dissolving the metal salt, good results can be obtained by using a proton solvent such as water or alcohol. Protonic solvents such as water and alcohol dissolve nickel salts well, stabilize metal salts by coordinating and hydrogen bonding to metal ions and counter ions, and suppress rapid reactions with ligands. In order to suppress side reactions.
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 preferred because they are inexpensive and have high solubility of nickel salts. These alcohols may be used alone or in combination.

  It is also preferable to use a mixture of water and the alcohol as a solvent. The mixing ratio is arbitrary from 1: 100 to 100: 0 (volume ratio). The mixing ratio of alcohols is preferably 30% or more from the viewpoint of improving the solubility of the ligand and the metal salt.

  Moreover, it is also possible to mix and use organic solvents other than alcohol with water, alcohol, or the mixed solvent of water-alcohol. The organic solvent to be mixed is a solvent miscible with water, such as acetonitrile, tetrahydrofuran, acetone, 1,4-dioxane, dimethylformamide, dimethyl sulfoxide, and the like. These may be used singly or in combination of two or more. Of these, acetone, 1,4-dioxane, dimethylformamide, dimethyl sulfoxide and acetonitrile give good results. The mixing ratio of the organic solvent is 50 mol% or less, preferably 30 mol% or less.

  On the other hand, the solvent for dissolving the organic ligand includes alcohol solvents such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol and ethylene glycol, acyclic and cyclic such as ether and tetrahydrofuran. Aliphatic ethers, ketones such as acetone, esters such as ethyl acetate, aliphatic nitriles such as acetonitrile, halogenated solvents such as dichloromethane, aromatic solvents such as benzene and toluene, formamides such as dimethylformamide, dimethyl sulfoxide The sulfoxides such as can be widely exemplified. These may be used singly or in combination of two or more. In terms of cost and solubility, methanol, ethanol, 2-propanol, acetonitrile, acetone and the like are preferable.

  The method for mixing the metal salt solution and the organic ligand solution may be the addition of the organic ligand solution to the metal salt solution or vice versa. The mixing is not necessarily performed in a solution. For example, a method of adding a solid organic ligand to a metal salt solution and simultaneously adding a solvent, or after charging a metal salt into a reaction vessel, Various methods are possible as long as the reaction finally takes place substantially in a solvent, such as injecting a solid or solution of the above, and then injecting a solution for dissolving the metal salt. However, the method of dropping and mixing a metal salt solution and an organic ligand solution is industrially the most convenient and preferable.

  The concentration of the solution is 40 mmol / L to 4 mmol / L, preferably 80 mmol / L to 2 mmol / L for the metal salt solution. The concentration of the organic solution of the ligand is 40 mmol / L to 3 mmol / L, preferably 80 mmol / L to 1.8 mmol / 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. On the other hand, a concentration higher than this is not preferable because the adsorption ability is lowered.

  The reaction temperature is -20 to 120 ° C, preferably 25 to 90 ° C. If it is carried out at a lower temperature than this, the solubility of the raw material is lowered, which is not preferable. Although it is possible to carry out the reaction at a higher temperature using an autoclave or the like, there is no substantial meaning because the yield does not improve for the energy cost such as heating.

  The mixing ratio of the metal salt and the organic ligand used in the reaction of the present invention is in the range of 3: 1 to 1: 5, preferably 1.5: 1 to 1: 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, the target substance and raw material can be separated by filtration and drying to produce a target substance with high purity.

  The gas adsorbent using the polymer metal complex of the present invention is a material in which the adsorption / desorption isotherm relating to the gas exhibits a hysteresis loop, but it is sufficient that the hysteresis loop is expressed for at least one kind of gas. The hysteresis loop may not be shown.

The gas that the gas adsorbent of the present invention needs to exhibit a hysteresis loop varies depending on the application of the gas adsorbent of the present invention.
For example, when the gas adsorbent of the present invention is used in a methane gas storage device, it is necessary to show a hysteresis loop for methane gas.
Further, when the gas adsorbent of the present invention is used in a gas separation device that separates hydrogen gas from a mixed gas of hydrogen and oxygen, it is necessary to show a hysteresis loop for each gas.

  Generally speaking, if the gas adsorbent of the present invention is used for storage or separation of gas used in various applications, the gas in which the gas adsorbent of the present invention exhibits a hysteresis loop is hydrogen, hydrocarbon (methane , Ethane, propane, butane, isobutane, etc.), carbon monoxide, carbon dioxide, oxygen, nitrogen and the like. Of course, a hysteresis loop may be shown for these two or more gases so that a mixture of a plurality of hydrocarbon gases such as LNG can be stored.

  In addition, if the gas adsorbent of the present invention is used for gas removal, the gas in which the gas adsorbent of the present invention exhibits a hysteresis loop includes hydrogen sulfide, sulfur oxide (SOx), nitrogen oxide (NOx), and Ammonia is preferred. Of course, a hysteresis loop may be shown for these two or more gases. A hysteresis loop may be shown for gases other than those exemplified above.

The material used as the gas adsorbent of the present invention may be selected according to the gas to be stored and the pressure required during adsorption. Although not particularly limited, [Cu (CF ₃ BF ₃ ) ₂ (bpy) ₂ ] _n (wherein bpy represents 4,4′-bipyridine) can be exemplified as a specific example.

[Combination of adsorbents]
The gas adsorbent of the present invention (hereinafter referred to as adsorbent A) may be used alone as an adsorbent, or may be used in combination with other adsorbents. When combined and used, the gas adsorbent having very good adsorption characteristics should be used in combination with the adsorbent B that exhibits the behavior that the adsorption isotherm and desorption isotherm coincide with each other. Can do.

  Here, the adsorbent B is a material that exhibits a behavior in which an adsorption isotherm and a desorption isotherm relating to gas coincide with each other. That is, as shown in FIG. 3, the gas pressure-gas adsorption amount curve at the time of adsorption is substantially the same as the gas pressure-gas adsorption amount curve at the time of desorption. The adsorbent B is not particularly limited as long as it has such characteristics, and a physical adsorbent, a chemical adsorbent, and a physicochemical adsorbent formed by combining these can be used.

A physical adsorbent refers to an adsorbent that adsorbs molecules to be adsorbed using weak force such as interaction between molecules. Examples of the physical adsorbent include activated carbon, silica gel, activated alumina, zeolite, clay, super adsorbent fiber, and metal complex.
A chemical adsorbent refers to an adsorbent that adsorbs molecules to be adsorbed by chemical bonds. Examples of the chemical adsorbent include calcium carbonate, calcium sulfate, potassium permanganate, sodium carbonate, potassium carbonate, sodium phosphate, and activated metal.
The physicochemical adsorbent refers to an adsorbent that has an adsorption mechanism for both the physical adsorbent and the chemical adsorbent. Two or more of these may be used in combination. However, the technical scope of the present invention is not limited to these specific examples.
The shape of the adsorbent B is not particularly limited, but generally, a powdery material having an average particle diameter of 500 to 5000 μm is used.

As the adsorbent B, activated carbon is preferable in consideration of manufacturing cost and gas adsorption performance. Activated carbon is relatively inexpensive and has a large amount of gas adsorption per mass. In addition, activated carbon has poor cycle characteristics related to gas adsorption and desorption, and when adsorption and desorption is repeated, the amount of gas adsorption tends to be remarkably reduced. For this reason, in the past, it was difficult to use in gas storage devices and gas separation devices despite the large amount of gas adsorption per mass. In this regard, when used as the adsorbent B of the present invention, the excellent gas adsorption performance of the activated carbon can be sufficiently extracted. Moreover, since activated carbon has the tendency for adsorption amount to increase, so that a specific surface area is large, it is preferable that the specific surface area of activated carbon is 1000 m < ² > / g or more.

  Moreover, it is preferable that the structure of the adsorbent B to be used is appropriately controlled according to the gas to be adsorbed. For example, the pores contained in the activated carbon can be classified into super micropores (up to 0.8 nm), micropores (0.8 to 2 nm), mesopores (2 to 50 nm), and macropores (50 nm to) depending on the size of the pores. . Gases that are easily adsorbed differ depending on the size of the pores, and methane gas is easily adsorbed to micropores. Therefore, when it is desired to adsorb methane gas, the pore distribution of the activated carbon may be controlled so that the proportion of micropores is increased.

When the adsorbent A and the adsorbent B of the present invention are combined, it is preferable to cover the adsorbent B with the adsorbent A, and more preferably, there is no crack or incomplete coating, and the adsorbent B touches the outside air. It is preferable to coat completely so that there is no.
However, even if some cracks and the like are present, if the adsorbent B obstructs free gas adsorption and the adsorbent B covered with the adsorbent A exhibits a hysteresis loop with respect to gas adsorption, the present invention can be used. It is included in the technical scope.
Preferably, the adsorbent B is coated with 5 to 50% by volume of the adsorbent A with respect to the adsorbent B. Further, the thickness of the adsorbent A covering the adsorbent B needs to be determined according to the type of the adsorbent A, but if the adsorbent A is too thin, the gas adsorption characteristics to the adsorbent B may not be sufficiently controlled. There is. On the other hand, if the adsorbent A is too thick, gas adsorption to the adsorbent B is difficult to occur, and the gas adsorption amount as a whole may be reduced.
Considering these, it is preferable that the average thickness of the adsorbent A is 10 to 100 μm. The thickness of the adsorbent A can be controlled by adjusting the amount of adsorbent A used. Note that the thickness of the adsorbent A can be calculated from a cross-sectional photograph taken using an electron microscope.

  As a method of combining the adsorbents A and B, (1) the adsorbent B that does not dissolve in the solution is added to the solution in which the adsorbent A is dissolved, and then the adsorbent A is crystal-grown. The method of attaching the adsorbent A to the surface of the adsorbent B. (2) A method of attaching the adsorbent A to the surface of the adsorbent B by preparing a slurry containing the adsorbent A and coating and drying the slurry on the surface of the adsorbent B. Etc. can be used.

[Application to gas separation equipment]
The gas adsorbent of the present invention can be used as an adsorbent in a pressure separating adsorption (hereinafter abbreviated as “PSA”) gas separation apparatus. PSA gas separation is based on the principle of utilizing the difference between the gas pressure on the adsorbent and the gas adsorption amount.

  In an adsorbent that exhibits a behavior in which the adsorption isotherm and desorption isotherm of activated carbon or zeolite coincide with each other, the gas adsorbent has two or more kinds of gases (for example, A gas and B gas) even though there is a difference in adsorption amount. Both of them often adsorb even if there is a difference in the amount of adsorption. Therefore, when performing gas separation by the PSA method using such a conventional material, since both the A gas and the B gas are adsorbed, the off gas includes the A gas as well as the B gas. Therefore, it is extremely inefficient when only the A gas is separated, and there is a disadvantage that the loss of the A gas into the off-gas is increased in order to increase the purity of the A gas as the product gas.

  On the other hand, in the adsorbent A of the present invention, there is a phenomenon that there is a clear gas adsorption start pressure and a desorption start pressure, which differ depending on the gas type. For this reason, for example, a mixed gas of oxygen and nitrogen is exposed to the adsorbent A at a pressure higher than the pressure at which both gases adsorb to adsorb both oxygen and nitrogen, and then the oxygen is not desorbed and the gas is within a pressure range where only nitrogen is desorbed. By controlling the pressure, it is possible to separate only nitrogen gas without releasing oxygen gas. That is, the gas separation performance is dramatically improved, and it is possible to obtain extremely high purity gas without contamination by one PSA operation. However, it does not exclude performing a PSA operation of two cycles or more.

  Since the gas separation apparatus of the present invention requires a small pressure swing width as described above, it contributes to a significant downsizing of the gas separation apparatus. Further, since the pressure swing width is small, the time required for the pressure change is shortened, energy saving, and the production running cost of high-purity gas and the fixed cost of equipment can be reduced. The cost competitiveness when selling high-purity gas as a product can be enhanced, and even when high-purity gas is used in its own factory, the cost required for facilities that require high-purity gas can be reduced. Therefore, it has the effect of reducing the manufacturing cost of the final product.

[Application to gas storage equipment]
By storing the adsorbent A inside a container such as a tank, a gas storage device that is superior to the case where a conventional material is used can be obtained.

  The adsorbent A of the present invention has a gas adsorption start pressure and a desorption start pressure. The gas is abruptly stored at a pressure equal to or higher than the adsorption start pressure to the full capacity of the adsorbent, and almost all of the adsorbed gas is released at the desorption start pressure below the desorption start pressure. The adsorbent A has a characteristic that a gas storage amount is large at a low pressure as compared with a conventional material, and can be suitably used when storing gas at a low pressure.

  Furthermore, the pressure of the gas released from the conventional gas adsorbent decreases as the gas is desorbed. However, when the gas is used in an actual apparatus such as a gas engine, a problem arises in the operability of the engine at an extremely low pressure, such as 0.5 MPa or less. For this reason, in the conventional gas adsorbing material, the stored gas having a gas pressure of 0.5 MPa or less (the portion on the left side of the line) cannot be practically used, resulting in a decrease in the stored gas pressure. On the other hand, since the adsorbent A of the present invention releases almost the entire amount of gas at a higher pressure, the gas loss phenomenon does not occur, and when the adsorbent A is used in a gas storage device, the preferable capacity is large. Occurs.

  When manufacturing containers, such as a tank using the adsorbent A, as a gas storage device, conventionally well-known techniques can be used for those structures and materials, and it is not specifically limited. For example, a metal container or the like that can control the entry and exit of gas by valve control can be used. For example, it is possible to use a metal thin-walled container wrapped around a carbon fiber reinforced plastic material having excellent strength per unit density. If the container is provided with a regulating valve for controlling the internal pressure of the gas storage device, the regulating valve can be used when gas is released from the gas storage device.

  A method for accommodating the gas adsorbent A in the gas storage device can be a known method such as filling in a pressure resistant container, and is not particularly limited. What is necessary is just to determine the accommodation amount of the adsorbent A according to the gas storage capability calculated | required by a gas storage apparatus. The shape and material of the pressure vessel are not particularly limited. The gas storage device of the present invention does not need to be provided with a special pressure-resistant structure because it may be at a lower pressure in order to ensure the same storage amount as compared with the conventional type. In this respect, it can be said that there is a cost advantage.

  When the adsorbent A is in a powder form, there is a possibility that it cannot be filled well if it is stored in a container constituting the gas storage device. When using a tank having a high degree of freedom in shape, this problem may be particularly noticeable. In this case, the powder may be stored in a tablet shape. When a tablet-shaped product is used, it is excellent in handleability and is very convenient when replacing an aged compound.

The gas storage device of the present invention has various applications such as, but not limited to, business gas tanks, consumer gas tanks, and vehicle fuel tanks. As an effect resulting from the ability to reduce the gas pressure at the time of conveyance 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 without maintaining the pressure during storage.
However, in the gas storage device of the present invention, a sufficient gas adsorption amount can be maintained even if the pressure is lowered. For this reason, the pressure resistance of a container can be made low and the shape of a gas storage apparatus can be designed freely to some extent. This effect is great when the gas storage device of the present invention is used as a fuel gas tank for vehicles such as automobiles. In a conventional fuel gas tank, the shape of the fuel gas tank is determined regardless of the shape of the vehicle. This inevitably results in a considerable amount of dead space. In addition, a special device is required to maintain a high pressure. In this regard, when the gas storage device of the present invention is used as a fuel gas tank, the restrictions on pressure resistance are relaxed as described above, so that the shape can be designed to some extent freely. Specifically, the shape of the gas storage device can be adjusted so as to fit the shape of wheels, seats, and the like in the vehicle. As a result, it is possible to obtain various benefits such as miniaturization of the vehicle, securing of luggage space, and improvement of fuel consumption by reducing the weight of the vehicle.

The method for preparing the polymer metal complex varies depending on the type of the gas adsorbent and cannot be uniquely determined. Here, [Cu (CF ₃ BF ₃ ) ₂ (bpy) ₂ ] (in the formula, bpy represents 4,4′-bipyridine.) A main example of a method for synthesizing a metal complex having a unit structure is described.
Infrared spectroscopic analysis was performed by attaching a once-reflective ATR attachment of Diamond Crystal of Sensor Technologies to a system 2000 manufactured by PerkinElmer.

"Example 1"
Put Cu (CF ₃ BF ₃ ) ₂ aqueous solution (80 mM, 6.25 mL) in a test tube, add NaPF ₆ (10 μmol) to dissolve, and slowly layer acetone solution of bpy (80 mM, 12.5 mL). After standing for 2 weeks, the precipitated blue crystals were filtered under reduced pressure and dried under reduced pressure to obtain blue polymer metal complex crystals.

As a result of X-ray crystal structure analysis, it was found that the obtained crystal had a two-dimensional planar structure.
Next, the crystals were dried at 100 ° C. for 3 hours under reduced pressure of 3 Pa, 1.00 g was weighed under an argon stream, and the powder was dissolved in 1 mol / L aqueous ammonia and extracted with dichloromethane. Dichloromethane was distilled off with a rotary evaporator, and the obtained bpy was quantitatively analyzed using a gas chromatograph mass spectrometer (Shimadzu Corporation QP5050A). Further, the content of copper in the aqueous ammonia layer was measured by ICP emission method. Further, the content of fluorine atoms in the aqueous ammonia layer was examined by distillation separation spectrophotometry. Further, the content of boron atoms in the aqueous ammonia layer was examined by ICP emission method, and as a result, it was found to be 3.02% by mass. It was found that the composition of the crystal obtained by combining these was [Cu (CF ₃ BF ₃ ) ₂ (bpy) ₂ ].

"Example 2"
Put Cu (BF ₄ ) ₂ aqueous solution (80 mM, 6.25 mL) in a test tube, add KCF ₃ BF ₃ (1.0 mmol) to dissolve, add NaPF ₆ (7.5 μmol) to dissolve, and further bpy Acetone solution (80 mM, 12.5 mL) was slowly layered and allowed to stand for 2 weeks. The precipitated blue crystals were filtered under reduced pressure and dried under reduced pressure to obtain blue polymer metal complex crystals.

As a result of X-ray crystal structure analysis, it was found that the obtained crystal had a two-dimensional planar structure.
When elemental analysis was performed in the same manner as in Example 1, it was found that the composition of the obtained crystal was [Cu (CF ₃ BF ₃ ) ₂ (bpy) ₂ ].

"Example 3"
Put Cu (BF ₄ ) ₂ aqueous solution (80 mM, 6.25 mL) in a test tube, add KCF ₃ BF ₃ (2.0 mmol) to dissolve, add NaPF ₆ (5.0 μmol) to dissolve, and further bpy Acetone solution (80 mM, 12.5 mL) was slowly layered and allowed to stand for 2 weeks. The precipitated blue crystals were filtered under reduced pressure and dried under reduced pressure to obtain blue polymer metal complex crystals.

As a result of X-ray crystal structure analysis, it was found that the obtained crystal had a two-dimensional planar structure.
Further, when elemental analysis was performed in the same manner as in Example 1, it was found that the composition of the obtained crystal was [Cu (CF ₃ BF ₃ ) ₂ (bpy) ₂ ].

Example 4
Put Cu (CF ₃ BF ₃ ) ₂ aqueous solution (80 mM, 6.25 mL) in a test tube, add NaPF ₆ (1.5 μmol) to dissolve, and slowly add bpy in acetone (80 mM, 12.5 mL). After standing for 2 weeks, the deposited blue crystals were filtered under reduced pressure and dried under reduced pressure to obtain blue polymer metal complex crystals.

As a result of X-ray crystal structure analysis, it was found that the obtained crystal had a two-dimensional planar structure.
Further, when elemental analysis was performed in the same manner as in Example 1, the composition of the obtained crystal was [Cu (CF ₃ BF ₃ ) ₂ (bpy) ₂ ], and it was found that PF ₆ ions were not included. It was.

"Example 5"
Put Cu (BF4) ₂ aqueous solution (80 mM, 6.25 mL) in a test tube, add NaPF ₆ (3.5 μmol) to dissolve, and slowly layer bpy in acetone (80 mM, 12.5 mL). After standing for 2 weeks, the precipitated blue crystals were filtered under reduced pressure and dried under reduced pressure to obtain blue polymer metal complex crystals.

As a result of X-ray crystal structure analysis, it was found that the obtained crystal had a two-dimensional planar structure.
Further, when elemental analysis was performed in the same manner as in Example 1, the composition of the obtained crystal was [Cu (CF ₃ BF ₃ ) ₂ (bpy) ₂ ], and it was found that PF ₆ ions were not included. It was.

"Example 6"
Put Cu (BF4) ₂ aqueous solution (80 mM, 6.25 mL) in a test tube, add NaPF ₆ (17.5 μmol) to dissolve, and slowly layer a bpy acetone solution (80 mM, 12.5 mL). After standing for 2 weeks, the precipitated blue crystals were filtered under reduced pressure and dried under reduced pressure to obtain blue polymer metal complex crystals.

As a result of X-ray crystal structure analysis, it was found that the obtained crystal had a two-dimensional planar structure.
When elemental analysis was performed in the same manner as in Example 1, the composition of the obtained crystal was [Cu (CF ₃ BF ₃ ) ₂ (bpy) ₂ ], and it was found that PF ₆ ions were not included.

`` Example 7 ''
Put Cu (BF4) ₂ aqueous solution (80 mM, 6.25 mL) in a test tube, add NaPF ₆ (37.5 μmol) to dissolve, and slowly layer bpy in acetone (80 mM, 12.5 mL). After standing for 2 weeks, the precipitated blue crystals were filtered under reduced pressure and dried under reduced pressure to obtain blue polymer metal complex crystals.

As a result of X-ray crystal structure analysis, it was found that the obtained crystal had a two-dimensional planar structure.
Further, when elemental analysis was performed in the same manner as in Example 1, the composition of the obtained crystal was [Cu (CF ₃ BF ₃ ) ₂ (bpy) ₂ ], and it was found that PF ₆ ions were not included. It was.

"Example 8"
A blue polymer metal complex crystal was obtained in the same manner as in Example 7 except that 3,3′-bipyridine was used instead of 4,4′-bipyridine.
As a result of X-ray crystal structure analysis, it was found that the obtained crystal had a two-dimensional planar structure.
Moreover, when performing the same elemental analysis as in Example 1, the composition of the obtained crystals was _{[Cu (CF 3 BF 3)} 2 (3,3'-bpy) 2], PF 6 - ions include I understood that it was not.

"Example 9"
A blue polymer metal complex crystal was obtained in the same manner as in Example 7 except that 3,4′-bipyridine was used instead of 4,4′-bipyridine.
As a result of X-ray crystal structure analysis, it was found that the obtained crystal had a two-dimensional planar structure.
Moreover, when performing the same elemental analysis as in Example 1, the composition of the obtained crystals was _{[Cu (CF 3 BF 3)} 2 (3,4'-bpy) 2], PF 6 - ions include I understood that it was not.

"Example 10"
1 g of zeolite 13X was mixed with 10 g of the polymer metal complex obtained in Example 1 to obtain an adsorbent of Example 10.

"Comparative Example 1"
Tube was charged with _Cu (CF 3 _{BF 3) 2} aqueous solution (80 mM, 6.25 mL), further 4,4'-bpy ethanol solution (80 mM, 12.5 mL) was slowly layered, 2 weeks after standing The deposited blue crystals were filtered under reduced pressure and dried under reduced pressure to obtain blue polymer metal complex crystals.

As a result of X-ray crystal structure analysis, it was found that the obtained crystal had a two-dimensional planar structure.
Moreover, when performing the same elemental analysis as in Example 1, the composition of the obtained crystals was _{[Cu (CF 3 BF 3)} 2 (bpy) 2], PF 6 - that ions are not included all right.

"Adsorption characteristics evaluation"
The gas adsorption property of the obtained polymer metal complex was evaluated by a nitrogen gas adsorption method. The gas adsorption measurement was performed at a temperature of 77K using a gas adsorption device Bell Soap Mini II manufactured by Bell Japan. Prior to measurement, a vacuum drying pretreatment was performed at 90 ° C. for 3 hours. As a result, the maximum gas adsorption amount of the polymer metal complexes obtained in Examples 1 to 7 was 180 mL / g.

As shown in Table 1, it shows the polymer metal complexes are both steep gas adsorption characteristics obtained in Examples 1 to 9, PF ₆ ^- was obtained in Example 4-7 is a condition in which ions coexist The polymer metal complex was found to exhibit particularly steep gas adsorption characteristics. Moreover, about the adsorbent of Example 10, when the polymeric metal complex of Example 1 and zeolite were mixed, it turned out that the maximum adsorption amount increases, without losing steep gas adsorbability.

  Here, the steep gas adsorption characteristic is the amount of increase in gate adsorption (the value obtained by dividing the maximum adsorption amount by the difference between the adsorption completion pressure and the adsorption start pressure (the slope of the adsorption curve, (mL / g · (P / P0))) is large, that is, a large increase in adsorption amount is obtained with a small fluctuation in adsorption pressure, and all pressures are expressed as relative pressures when the saturated vapor pressure is 1.

  The adsorption start pressure and the adsorption completion pressure are obtained from the first derivative curve of the adsorption curve. That is, the first derivative curve of the adsorption curve shown in FIG. 3 is a curve having a peak near the pressure at which the adsorption amount varies greatly. In this specification, the pressure at the rising point of the peak of the first derivative curve is expressed as the adsorption start pressure. And the pressure at the end point of the peak is the adsorption completion pressure.

The ionic strength is shown in Table 1. Here ionic strength and is, in the infrared spectral data measured by the diamond single reflection ATR _method, (CF 3 _BF 3) ^- the absorption intensity of 1056cm ^-1, which is attributed to the ion, 4,4'-bpy , 3,3′-bpy or 3,4′-bpy divided by 1614 cm ⁻¹ absorption intensity (both T%, uncorrected). The crystals produced by the methods of Examples 1 to 9 were all found to have an ionic strength of 1.4 or more.

  On the other hand, when the gas adsorption characteristics of Comparative Example 1 were evaluated in the same manner as in the Examples, the results were as shown in Table 1 below. The ionic strength was less than 1.4 and the slope of the adsorption curve was small.

  In the polymer metal complex of the present invention, a large number of micropores formed by alignment of ligands are present inside the substance. Utilizing this porosity, it can be used for adsorption and removal of various substances. For example, removal of toxic substances in the air, purification of water by removing unnecessary substances such as inorganic and organic substances in the water, or adsorption of useful substances in the air and water and taking them out, the useful substances air and water Can be recovered.

Claims (6)

It is a two-dimensional planar lattice stacked type crystal structure having a unit structure of the following formula (1), and the absorption intensity at 1056 cm ⁻¹ by infrared spectroscopy is 1.4 times or more the absorption intensity at 1614 cm ^−1. A polymer metal complex.
[X (CF ₃ BF ₃ ) ₂ L ₂ ] (1)
(Wherein X is a divalent ion of cobalt, nickel or copper, L is an organic ligand, and 4,4′-bipyridine, 3,3′-bipyridine, 3,4 '- Ru der any one or more of the bipyridine). _(CF 3 _BF 3) ^- ion and PF ₆ ^- polymeric metal complexes according to claim 1, wherein the metal salt contains ions was synthesized as a raw material. _(CF 3 _BF 3) ^- ion and PF ₆ ^- molar ratio of _ions, (CF 3 _BF 3) ^- with respect to ions 100, PF ₆ ^- claim 2, wherein the ions are characterized in that 7.5 or less Polymer metal complex. A gas adsorbent comprising the polymer metal complex according to any one of claims 1 to 3 . A pressure swing adsorption type gas separation apparatus comprising the gas adsorbent according to claim 4 . A gas storage device in which the gas adsorbent according to claim 4 is housed.

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