JP2012180321A - Metal complex, and separation material comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal complex having excellent gas separation capability.SOLUTION: This metal complex includes 5-nitroisophthalic acid, a nickel ion and a compound expressed by general formula (I), wherein R, R, R, R, R, R, Rand Reach the same or different and represents a hydrogen atom, a (substituted) alkyl group or a halogen atom, or Rand R, or Rand Rmay get together and form an alkenylene group which may have a substituent.

Description

  The present invention relates to a metal complex and a separating material comprising the same. More specifically, the present invention relates to a metal complex comprising 5-nitroisophthalic acid, nickel ions, and a specific organic ligand capable of bidentate coordination with the nickel ions. The metal complex of the present invention is carbon dioxide, hydrogen, carbon monoxide, oxygen, nitrogen, hydrocarbon having 1 to 4 carbon atoms, rare gas, hydrogen sulfide, ammonia, sulfur oxide, nitrogen oxide, siloxane, water vapor or organic It is preferable as a separating material for separating steam, and particularly preferable as a separating material such as methane and carbon dioxide, hydrogen and carbon dioxide, nitrogen and carbon dioxide, methane and ethane, or air and methane.

  So far, various adsorbents have been developed in fields such as deodorization and exhaust gas treatment. Activated carbon is a representative example, and is widely used in various industries such as air purification, desulfurization, denitration, and removal of harmful substances by utilizing the excellent adsorption performance of activated carbon. In recent years, the demand for nitrogen has increased for semiconductor manufacturing processes, etc., and as a method for producing such nitrogen, a method of producing nitrogen from air by pressure swing adsorption method or temperature swing adsorption method using molecular sieve charcoal is used. Has been. Molecular sieve charcoal is also applied to various gas separation and purification such as hydrogen purification from methanol cracked gas.

  When separating mixed gas by pressure swing adsorption method or temperature swing adsorption method, generally, molecular sieve charcoal or zeolite is used as the separation adsorbent, and separation is performed by the difference in the equilibrium adsorption amount or adsorption rate. . However, when separating the mixed gas based on the difference in the amount of equilibrium adsorption, the conventional adsorbents cannot selectively adsorb only the gas to be removed, so the separation factor becomes small, and the size of the apparatus is inevitable. . In addition, when separating the mixed gas based on the difference in adsorption speed, only the gas to be removed can be adsorbed depending on the type of gas, but it is necessary to perform adsorption and desorption alternately, and in this case, the apparatus still has to be large. I didn't get it.

  On the other hand, polymer metal complexes that cause a dynamic structural change by an external stimulus have been developed as adsorbents that give better adsorption performance (see Non-Patent Document 1 and Non-Patent Document 2). When this new dynamic structure change polymer metal complex is used as a gas adsorbent, a unique phenomenon is observed in which gas adsorption does not adsorb up to a certain pressure, but gas adsorption starts when a certain pressure is exceeded. Yes. In addition, a phenomenon has been observed in which the adsorption start pressure varies depending on the type of gas.

  When this phenomenon is applied to, for example, an adsorbent in a pressure swing adsorption type gas separation apparatus, very efficient gas separation is possible. In addition, the pressure swing width can be narrowed, contributing to energy saving. Furthermore, since it can contribute to miniaturization of the gas separation device, it is possible to increase cost competitiveness when selling high-purity gas as a product, of course, even when high-purity gas is used inside its own factory 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.

  However, the present situation is that cost reduction by further downsizing of the apparatus is required, and in order to achieve this, further improvement in adsorption performance and storage performance is required.

  A polymer metal complex composed of an isophthalic acid derivative, a metal ion, and 4,4′-bipyridyl has been disclosed (see Patent Document 1). However, 5-nitroisophthalic acid is not disclosed as an example of an isophthalic acid derivative, and no mention is made of the effect of metal ions on the adsorption performance.

  A polymer metal complex composed of 5-nitroisophthalic acid, zinc ion, and 4,4'-bipyridyl is known (see Patent Document 2). However, no mention is made of the effect of metal ions other than zinc ions on the adsorption performance.

  A polymer metal complex composed of an isophthalic acid derivative, a metal ion, and 4,4′-bipyridyl has been disclosed (see Patent Document 3). However, 5-nitroisophthalic acid is not disclosed as an example of an isophthalic acid derivative, and no mention is made of the effect of metal ions on the adsorption performance.

JP 2008-24784A JP 2010-158617 A JP 2010-180202 A

Kazuhiro Uemura, Susumu Kitagawa, Future Materials, Volume 2, 44-51 (2002) Ryotaro Matsuda, Susumu Kitagawa, Petrotech, Vol. 26, 97-104 (2003)

  Accordingly, an object of the present invention is to provide a metal complex that can be used as a gas separation material that exhibits higher selectivity than conventional ones.

  The present inventors have intensively studied and found that the above object can be achieved by a metal complex comprising 5-nitroisophthalic acid, a nickel ion, and an organic ligand capable of bidentate coordination with the nickel ion. The headline, the present invention has been reached.

That is, according to the present invention, the following is provided.
(1) 5-nitroisophthalic acid, nickel ion, and the following general formula (I);

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are the same or different and each represents a hydrogen atom, an alkyl group which may have a substituent or a halogen atom. Or R ² and R ³ , or R ⁶ and R ⁷ may be combined to form an alkenylene group which may have a substituent. A metal complex comprising an organic ligand (I) capable of coordination.
(2) A separating material comprising the metal complex according to (1).
(3) The separator is carbon dioxide, hydrogen, carbon monoxide, oxygen, nitrogen, hydrocarbon having 1 to 4 carbon atoms, rare gas, hydrogen sulfide, ammonia, sulfur oxide, nitrogen oxide, siloxane, water vapor or The separating material according to (3), which is a separating material for separating organic vapor.
(4) The separation material according to (3), wherein the separation material is a separation material for separating methane and carbon dioxide, hydrogen and carbon dioxide, nitrogen and carbon dioxide, methane and ethane, or air and methane.
(5) The metal complex according to (1), wherein 5-nitroisophthalic acid, a nickel salt, and an organic ligand (I) capable of bidentate coordination with the nickel ion are reacted and precipitated in a solvent. Manufacturing method.

  According to the present invention, a metal complex comprising 5-nitroisophthalic acid, nickel ions, and an organic ligand (I) capable of bidentate coordination with the nickel ions can be provided.

  Since the metal complex of the present invention is excellent in the separation performance of various gases, carbon dioxide, hydrogen, carbon monoxide, oxygen, nitrogen, hydrocarbons having 1 to 4 carbon atoms, rare gas, hydrogen sulfide, ammonia, sulfur oxidation It can be used as a separating material for separating substances, nitrogen oxides, siloxane, water vapor or organic vapor.

3 is a powder X-ray diffraction pattern of the metal complex obtained in Synthesis Example 1. FIG. 3 is a powder X-ray diffraction pattern of the metal complex obtained in Comparative Synthesis Example 1. FIG. 4 is a powder X-ray diffraction pattern of the metal complex obtained in Comparative Synthesis Example 2. FIG. 4 is a powder X-ray diffraction pattern of the metal complex obtained in Comparative Synthesis Example 3. FIG. 6 is a powder X-ray diffraction pattern of the metal complex obtained in Comparative Synthesis Example 4. FIG. For the metal complex obtained in Synthesis Example 1, a breakthrough curve at 273 K, 0.7 MPaG, and a space velocity of 6 min ⁻¹ was measured using a mixed gas of methane and carbon dioxide having a volume ratio of methane: carbon dioxide = 60: 40. It is the result. For the metal complex obtained in Comparative Synthesis Example 1, a breakthrough curve at 273 K, 0.7 MPaG, and a space velocity of 6 min ⁻¹ was obtained using a mixed gas of methane and carbon dioxide having a volume ratio of methane: carbon dioxide = 60: 40. It is the result of measurement. For the metal complex obtained in Comparative Synthesis Example 2, a breakthrough curve at 273 K, 0.7 MPaG and a space velocity of 6 min ⁻¹ was obtained using a mixed gas of methane and carbon dioxide having a volume ratio of methane: carbon dioxide = 60: 40. It is the result of measurement. For the metal complex obtained in Comparative Synthesis Example 3, a breakthrough curve at 273 K, 0.7 MPaG and a space velocity of 6 min ⁻¹ was obtained using a mixed gas of methane and carbon dioxide having a volume ratio of methane: carbon dioxide = 60: 40. It is the result of measurement. For the metal complex obtained in Comparative Synthesis Example 4, a breakthrough curve at 273 K, 0.7 MPaG, and a space velocity of 6 min ⁻¹ was obtained using a mixed gas of methane and carbon dioxide having a volume ratio of methane: carbon dioxide = 60: 40. It is the result of measurement. About the metal complex obtained in Synthesis Example 1, the result of measurement of a breakthrough curve at 273 K, 0.7 MPaG, and a space velocity of 6 min ⁻¹ using a mixed gas of methane and ethane having a volume ratio of methane: ethane = 90: 10 It is. For the metal complex obtained in Comparative Synthesis Example 3, a breakthrough curve at 273 K, 0.7 MPaG, and a space velocity of 6 min ⁻¹ was measured using a mixed gas of methane and ethane having a volume ratio of methane: ethane = 90: 10. It is a result.

  The metal complex of the present invention comprises 5-nitroisophthalic acid, nickel ions, and an organic ligand (I) capable of bidentate coordination with the nickel ions.

  The metal complex is produced by reacting 5-nitroisophthalic acid, a nickel salt, and an organic ligand (I) capable of bidentate coordination in a solvent under normal pressure for several hours to several days and depositing them. be able to. For example, an aqueous solution or an organic solvent solution of nickel salt and an organic solvent solution containing 5-nitroisophthalic acid and an organic ligand (I) capable of bidentate coordination are mixed and reacted under normal pressure. Obtainable.

  As the nickel salt used for the production of the metal complex, organic acid salts such as acetate and formate, and inorganic acid salts such as hydrochloride, hydrobromide, sulfate, nitrate and carbonate can be used.

  The organic ligand (I) capable of bidentate coordination used in the present invention has the following general formula (I):

It is represented by In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are the same or different and each represents a hydrogen atom, an alkyl group which may have a substituent or a halogen atom. Or, R ² and R ³ , or R ⁶ and R ⁷ may be combined to form an alkenylene group which may have a substituent.

Of the substituents that can constitute R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ , the alkyl group preferably has 1 to 5 carbon atoms. Examples of the alkyl group include a straight or branched alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, and a pentyl group, and a halogen atom. Examples of are fluorine atom, chlorine atom, bromine atom and iodine atom. Examples of the substituent that the alkyl group may have include an alkoxy group (methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, tert-butoxy group, etc. ), Amino group, monoalkylamino group (such as methylamino group), dialkylamino group (such as dimethylamino group), formyl group, epoxy group, acyloxy group (acetoxy group, n-propanoyloxy group, n-butanoyloxy) Group, pivaloyloxy group, benzoyloxy group, etc.), alkoxycarbonyl group (methoxycarbonyl group, ethoxycarbonyl group, n-butoxycarbonyl group, etc.), carboxylic acid anhydride group (—CO—O—CO—R group) (R is And an alkyl group having 1 to 5 carbon atoms). 1-3 are preferable and, as for the number of the substituents of an alkyl group, one is more preferable.

The alkenylene group preferably has 2 carbon atoms. When the alkenylene group has 2 carbon atoms, R ² and R ³ , or R ⁶ and R ⁷ together with the carbon atom to which they are bonded form a 6-membered ring (benzene).

  Examples of the substituent that the alkenylene group may have include an alkoxy group (methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, tert-butoxy group, etc. ), Amino group, monoalkylamino group (such as methylamino group), dialkylamino group (such as dimethylamino group), formyl group, epoxy group, acyloxy group (acetoxy group, n-propanoyloxy group, n-butanoyloxy) Group, pivaloyloxy group, benzoyloxy group, etc.), alkoxycarbonyl group (methoxycarbonyl group, ethoxycarbonyl group, n-butoxycarbonyl group, etc.), carboxylic acid anhydride group (—CO—O—CO—R group) (R is And an alkyl group having 1 to 5 carbon atoms).

  Examples of the bidentate organic ligand (I) include 4,4′-bipyridyl, 2,2′-dimethyl-4,4′-bipyridine, and diazapyrene. '-Bipyridyl is preferred. Here, an organic ligand capable of bidentate coordination means a neutral ligand having two sites that are coordinated to nickel ions by an unshared electron pair.

  The mixing ratio of 5-nitroisophthalic acid to the bidentate organic ligand (I) when producing the metal complex is as follows: 5-nitroisophthalic acid: bidentate organic ligand (I ) = 1: 5 to 8: 1 molar ratio is preferable, and 1: 3 to 6: 1 molar ratio is more preferable. Even if the reaction is carried out in a range other than this, the desired metal complex can be obtained, but this is not preferable because the yield is lowered and the side reaction is also increased.

  The mixing ratio of the nickel salt to the bidentate organic ligand (I) when producing the metal complex is as follows: nickel salt: bidentate organic ligand (I) = 3: 1 to 1 : Within the range of the molar ratio of 3: 3, and more preferably within the range of the molar ratio of 2: 1 to 1: 2. In other ranges, the yield of the target metal complex decreases, and purification of the metal complex obtained by leaving unreacted raw materials becomes difficult.

  The molar concentration of 5-nitroisophthalic acid in the mixed solution for producing the metal complex is preferably 0.01 to 5.0 mol / L, more preferably 0.05 to 2.0 mol / L. Even if the reaction is performed at a concentration lower than this, the desired metal complex can be obtained, but this is not preferable because the yield decreases. If the concentration is higher than this, the solubility is lowered and the reaction does not proceed smoothly.

  The molar concentration of the nickel salt in the mixed solution for producing the metal complex is preferably 0.01 to 5.0 mol / L, and more preferably 0.05 to 2.0 mol / L. Even if the reaction is performed at a concentration lower than this, the desired metal complex can be obtained, but this is not preferable because the yield decreases. Further, at a concentration higher than this, unreacted nickel salt remains, and purification of the obtained metal complex becomes difficult.

  The molar concentration of the bidentate organic ligand (I) in the mixed solution for producing the metal complex is preferably 0.01 to 5.0 mol / L, and preferably 0.05 to 2.0 mol / L. More preferred. Even if the reaction is performed at a concentration lower than this, the desired metal complex can be obtained, but this is not preferable because the yield decreases. If the concentration is higher than this, the solubility is lowered and the reaction does not proceed smoothly.

  As a solvent used for producing the metal complex, an organic solvent, water, or a mixed solvent thereof can be used. Specifically, methanol, ethanol, propanol, diethyl ether, dimethoxyethane, tetrahydrofuran, hexane, cyclohexane, heptane, benzene, toluene, methylene chloride, chloroform, acetone, ethyl acetate, acetonitrile, N, N-dimethylformamide, water or These mixed solvents can be used. The reaction temperature is preferably 253 to 423K.

  A metal complex having good crystallinity has high purity and good adsorption performance. The completion of the reaction can be confirmed by quantifying the remaining amount of the raw material by gas chromatography or high performance liquid chromatography. After completion of the reaction, the obtained mixed solution is subjected to suction filtration to collect a precipitate, washed with an organic solvent, and then vacuum dried at about 373 K for several hours to obtain the metal complex of the present invention.

  In the metal complex of the present invention obtained as described above, a two-dimensional sheet in which one-dimensional chains composed of the dicarboxylic acid compound (I) and nickel ions are connected by a bidentate ligand is formed. These two-dimensional sheets are accumulated to form a three-dimensional structure having pores (one-dimensional channels).

  Since the three-dimensional structure in the metal complex can be changed in the synthesized crystal, the structure and size of the pores change with the change. The conditions for changing the structure depend on the type of substance to be adsorbed, the adsorption pressure, and the adsorption temperature. That is, in addition to the difference in the interaction between the pore surface and the substance (the strength of the interaction is proportional to the magnitude of the Lennard-Jones potential of the substance), the degree of structural change varies depending on the adsorbed substance, and thus high selectivity is achieved. To express. In the present invention, 5-nitroisophthalic acid is used to control the charge density on the pore surface, and nickel ions are used to control the ease of structural change and to exhibit high mixed gas separation performance. it can. After the adsorbed substance is desorbed, it returns to its original structure, so the pore size also returns.

  Although the selective adsorption mechanism is estimated, even if it does not follow the mechanism, it is included in the technical scope of the present invention as long as it satisfies the requirements defined in the present invention.

  Since the metal complex of the present invention is excellent in the separation performance of various gases, carbon dioxide, hydrogen, carbon monoxide, oxygen, nitrogen, C 1-4 hydrocarbons (methane, ethane, ethylene, acetylene, etc.), Noble gas (such as helium, neon, argon, krypton, xenon), hydrogen sulfide, ammonia, sulfur oxide, nitrogen oxide, siloxane (such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane), water vapor or organic vapor Preferred as a separation material for separation, especially carbon dioxide in methane, carbon dioxide in hydrogen, carbon dioxide in nitrogen, ethane in methane or methane in air, etc., pressure swing adsorption method or temperature swing adsorption method It is suitable for separation. The organic vapor means a vaporized organic substance that is liquid at normal temperature and pressure. Examples of such organic substances include alcohols such as methanol and ethanol; amines such as trimethylamine; aldehydes such as acetaldehyde; aliphatic hydrocarbons having 5 to 16 carbon atoms; aromatic hydrocarbons such as benzene and toluene; acetone And ketones such as methyl ethyl ketone; halogenated hydrocarbons such as methyl chloride and chloroform.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. Analysis and evaluation in the following examples and comparative examples were performed as follows.

(1) Measurement of powder X-ray diffraction pattern Using an X-ray diffractometer, a range of diffraction angle (2θ) = 5 to 50 ° was scanned at a scanning speed of 1 ° / min, and measured by a symmetric reflection method. Details of the measurement conditions are shown below.
<Analysis conditions>
Apparatus: RINT2400 manufactured by Rigaku Corporation
X-ray source: CuKα (λ = 1.5418Å) 40 kV 200 mA
Goniometer: Vertical goniometer Detector: Scintillation counter Step width: 0.02 °
Slit: Divergent slit = 0.5 °
Receiving slit = 0.15mm
Scattering slit = 0.5 °

(2) Measurement of breakthrough curve A pressure-resistant glass container having an internal volume of 10 mL connected to a cylinder with a stainless tube equipped with a gas flow meter and valves was prepared. The measurement was performed by putting a sample in a pressure-resistant glass container, drying it at 373 K and 7 Pa for 3 hours, removing adsorbed water, etc., and then circulating a mixed gas. At this time, the outlet gas was sampled every 2 minutes and analyzed by gas chromatography to calculate the composition of the outlet gas (the inlet gas composition was measured in advance using gas chromatography). Details of the measurement conditions are shown below.
<Measurement conditions>
Apparatus: GC-14B manufactured by Shimadzu Corporation
Column: Universe Co., Ltd. Unibeads C 60/80
Column temperature: 200 ° C
Carrier gas: Helium injection amount: 1.0 mL
Detector: TCD

<Synthesis Example 1>
Under a nitrogen atmosphere, 12.3 g (42 mmol) of nickel nitrate hexahydrate, 8.92 g (42 mmol) of 5-nitroisophthalic acid, and 6.60 g (42 mmol) of 4,4′-bipyridyl were added to 500 mL of N, N-dimethylformamide. Dissolved and stirred at 393K for 24 hours. The precipitated metal complex was collected by suction filtration, and then washed with ethanol three times. Then, it dried at 373 K and 50 Pa for 8 hours, and obtained 17.4 g (yield 97%) of the target metal complex. The powder X-ray diffraction pattern of the obtained metal complex is shown in FIG.

<Comparative Synthesis Example 1>
In a nitrogen atmosphere, 12.1 g (42 mmol) of manganese nitrate hexahydrate, 8.92 g (42 mmol) of 5-nitroisophthalic acid and 6.60 g (42 mmol) of 4,4′-bipyridyl were added to 500 mL of N, N-dimethylformamide. Dissolved and stirred at 393K for 24 hours. The precipitated metal complex was collected by suction filtration, and then washed with ethanol three times. Then, it dried at 373K and 50 Pa for 8 hours, and obtained 16.0 g (yield 90%) of the target metal complex. The powder X-ray diffraction pattern of the obtained metal complex is shown in FIG.

<Comparative Synthesis Example 2>
Under a nitrogen atmosphere, 4.91 g (17 mmol) of cobalt nitrate hexahydrate, 3.57 g (17 mmol) of 5-nitroisophthalic acid and 2.64 g (17 mmol) of 4,4′-bipyridyl were added to 200 mL of N, N-dimethylformamide. Dissolved and stirred at 393K for 24 hours. The precipitated metal complex was collected by suction filtration, and then washed with ethanol three times. Then, it dried at 373 K and 50 Pa for 8 hours, and obtained the target metal complex 6.68g (yield 93%). The powder X-ray diffraction pattern of the obtained metal complex is shown in FIG.

<Comparative Synthesis Example 3>
In a nitrogen atmosphere, 12.6 g (42 mmol) of zinc nitrate hexahydrate, 8.92 g (42 mmol) of 5-nitroisophthalic acid and 6.60 g (42 mmol) of 4,4′-bipyridyl were added to 500 mL of N, N-dimethylformamide. Dissolved and stirred at 393K for 24 hours. The precipitated metal complex was collected by suction filtration, and then washed with ethanol three times. Then, it dried at 373 K and 50 Pa for 8 hours, and obtained 15.5 g (yield 85%) of the target metal complex. The powder X-ray diffraction pattern of the obtained metal complex is shown in FIG.

<Comparative Synthesis Example 4>
Under a nitrogen atmosphere, 4.91 g (17 mmol) of nickel nitrate hexahydrate, 3.32 g (17 mmol) of 5-methoxyisophthalic acid and 2.64 g (17 mmol) of 4,4′-bipyridyl were added to 200 mL of N, N-dimethylformamide. Dissolved and stirred at 393K for 24 hours. The precipitated metal complex was collected by suction filtration, and then washed with ethanol three times. Then, it dried at 373 K and 50 Pa for 8 hours, and obtained the target metal complex 6.54g (yield 95%). FIG. 5 shows a powder X-ray diffraction pattern of the obtained metal complex.

<Example 1>
For the metal complex obtained in Synthesis Example 1, the separation performance at 273 K, 0.7 MPaG, and a space velocity of 6 min ⁻¹ was measured using a mixed gas of methane and carbon dioxide having a volume ratio of methane: carbon dioxide = 60: 40. . The results are shown in FIG.

<Comparative Example 1>
For the metal complex obtained in Comparative Synthesis Example 1, the separation performance at 273 K, 0.7 MPaG, and space velocity 6 min ⁻¹ was measured using a mixed gas of methane and carbon dioxide having a volume ratio of methane: carbon dioxide = 60: 40. did. The results are shown in FIG.

<Comparative example 2>
For the metal complex obtained in Comparative Synthesis Example 2, the separation performance at 273 K, 0.7 MPaG, and space velocity 6 min ⁻¹ was measured using a mixed gas of methane and carbon dioxide having a volume ratio of methane: carbon dioxide = 60: 40. did. The results are shown in FIG.

<Comparative Example 3>
For the metal complex obtained in Comparative Synthesis Example 3, the separation performance at 273 K, 0.7 MPaG, and a space velocity of 6 min ⁻¹ was measured using a mixed gas of methane and carbon dioxide having a volume ratio of methane: carbon dioxide = 60: 40. did. The results are shown in FIG.

<Comparative example 4>
For the metal complex obtained in Comparative Synthesis Example 4, the separation performance at 273 K, 0.7 MPaG, and space velocity 6 min ⁻¹ was measured using a mixed gas of methane and carbon dioxide having a volume ratio of methane: carbon dioxide = 60: 40. did. The results are shown in FIG.

  From the comparison between FIG. 6 and FIGS. 7 to 10, the metal complex of the present invention can concentrate methane to 99.5% or more and has a long breakthrough time of carbon dioxide, so it is excellent as a separator for methane and carbon dioxide. It is clear that

<Example 2>
For the metal complex obtained in Synthesis Example 1, the separation performance at 273 K, 0.7 MPaG, and the space velocity of 6 min ⁻¹ was measured using a mixed gas of methane and ethane having a volume ratio of methane: ethane = 90: 10. The results are shown in FIG.

<Comparative Example 5>
For the metal complex obtained in Comparative Synthesis Example 3, the separation performance at 273 K, 0.7 MPaG, and a space velocity of 6 min ⁻¹ was measured using a mixed gas of methane and ethane having a volume ratio of methane: ethane = 90: 10. The results are shown in FIG.

  From the comparison of FIG. 11 and FIG. 12, it is clear that the metal complex of the present invention is excellent as a separator for methane and ethane because it can concentrate methane to 99.5% or more and has a long breakthrough time of ethane. It is.

Claims (5)

5-nitroisophthalic acid, nickel ion, and the following general formula (I);

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are the same or different and each represents a hydrogen atom, an alkyl group which may have a substituent or a halogen atom. Or R ² and R ³ , or R ⁶ and R ⁷ may be combined to form an alkenylene group which may have a substituent. A separation material comprising the metal complex according to claim 1.   The separation material is carbon dioxide, hydrogen, carbon monoxide, oxygen, nitrogen, hydrocarbon having 1 to 4 carbon atoms, rare gas, hydrogen sulfide, ammonia, sulfur oxide, nitrogen oxide, siloxane, water vapor or organic vapor. The separation material according to claim 2, which is a separation material for separation.   The separation material according to claim 2, wherein the separation material is a separation material for separating methane and carbon dioxide, hydrogen and carbon dioxide, nitrogen and carbon dioxide, methane and ethane, or air and methane.   The method for producing a metal complex according to claim 1, wherein 5-nitroisophthalic acid, a nickel salt, and an organic ligand capable of bidentate coordination with the nickel ion are reacted and precipitated in a solvent.

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