JP2004161675A - Three-dimensional metal complex, adsorbent material and separating material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adsorbent material capable of selectively adsorbing a substance such as a gas, or a separating material with high separating performance. <P>SOLUTION: A metal complex composed of 2,5-dihydroxybenzoic acid, at least one metal atom selected from copper, rhodium, chromium, molybdenum, palladium, zinc and tungsten atoms, and an organic ligand capable of assuming a bidentate configuration on the metal atom, is provided. The adsorbent or separating material comprises the metal complex. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a three-dimensional metal complex, an adsorbent comprising the complex, and a separating material.
[0002]
[Prior art]
When a gas is separated from a mixed gas by a pressure swing method or a temperature swing method, generally, activated carbon, zeolite, or the like is used as a separation adsorbent, and separation is performed based on a difference in the equilibrium adsorption amount or the adsorption speed (for example, , Non-Patent Document 1).
[0003]
However, in the case of separation based on the difference in the equilibrium adsorption amount, the conventional adsorbent cannot selectively adsorb only one substance (gas), so that the separation coefficient becomes small and the apparatus becomes large. . On the other hand, when separation is performed by the difference in adsorption speed, depending on the type of gas, only one substance (gas) can be adsorbed. .
[0004]
[Non-patent document 1]
Y. Takeuchi, “Handbook of Latest Adsorption Technology”, 1st edition, NTT Co., Ltd., January 11, 1999, p. 84-163
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide an adsorbent capable of selectively adsorbing a substance such as a gas and a separating material having high separation performance.
[0006]
[Means for Solving the Problems]
By using a new external-field-responsive metal complex whose pore size (structure) changes depending on the type of substance to be adsorbed, the adsorption pressure, the adsorption temperature, etc., both the pressure swing method and the temperature swing method They have found that the substance can be selectively adsorbed, and have completed the present invention.
[0007]
That is, the present invention provides a three-dimensional metal complex, an adsorbent, a separation material, an adsorption storage device, and a separation device as described below.
Item 1. Metals comprising 2,5-dihydroxybenzoic acid, at least one metal selected from copper, rhodium, chromium, molybdenum, palladium, zinc and tungsten, and an organic ligand capable of bidentate coordination with the metal Complex.
Item 2. 2,5-dihydroxybenzoic acid, at least one metal salt selected from copper salts, rhodium salts, chromium salts, molybdenum salts, palladium salts, zinc salts and tungsten salts, and organic coordination capable of bidentate coordination Item 7. The metal complex according to item 1, which is obtained by reacting with an element in a solvent to cause precipitation.
Item 3. The organic ligand is pyrazine, 4,4′-bipyridyl, trans-1,2-bis (4-pyridyl) ethylene, 4,4′-azopyridine, 4,4′-bipyridylethane, 4,4′-bis Item 3. The metal complex according to Item 1 or 2, which is at least one selected from bipyridylphenylene and N- (4-pyridyl) isonicotinamide.
Item 4. Item 4. The metal complex according to item 3, wherein the organic ligand is 4,4′-bipyridyl.
Item 5. Item 5. The metal complex according to any one of Items 1 to 4, wherein the metal is copper and the organic ligand is 4,4′-bipyridyl.
Item 6. Items 1 to 5 which are porous metal complexes that adsorb a gas or a liquid, wherein the integrated structure of the metal complex changes and the pore size changes depending on the kind of the substance to be adsorbed, the adsorption pressure or the adsorption temperature. The metal complex according to any one of the above.
Item 7. Item 7. An adsorbent comprising the metal complex according to any one of Items 1 to 6.
Item 8. Item 7. A separation material comprising the metal complex according to any one of Items 1 to 6.
Item 9. Item 9. The separation material according to item 8, for separating carbon dioxide, hydrogen, carbon monoxide, oxygen, nitrogen, a hydrocarbon having 1 to 4 carbon atoms, ammonia, water vapor, or organic vapor.
Item 10. Item 9. The separation material according to item 8, for separating carbon dioxide in methane, carbon dioxide in nitrogen, oxygen in air or methane in natural gas.
Item 11. Item 8. An adsorption storage device using the adsorbent according to Item 7.
Item 12. Item 11. A separation device using the separation material according to any one of Items 8 to 10.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The metal complex of the present invention comprises 2,5-dihydroxybenzoic acid, at least one metal selected from copper, rhodium, chromium, molybdenum, palladium, zinc and tungsten, and an organic compound capable of bidentate coordination with the metal. And a ligand.
[0009]
[Production of metal complex]
To produce the metal complex of the present invention, 2,5-dihydroxybenzoic acid and at least one metal salt selected from copper, rhodium, chromium, molybdenum, palladium, zinc and tungsten salts And an organic ligand capable of bidentate coordination are reacted in a solvent for several hours to several days to precipitate.
[0010]
For example, when an aqueous solution or an organic solution of a metal salt and an organic solution containing 2,5-dihydroxybenzoic acid and an organic ligand capable of bidentate coordination are mixed and reacted, good crystallinity (purity) is obtained. Metal complex which has high adsorption performance and good adsorption performance).
[0011]
The precipitate is collected from the obtained mixture by suction filtration, washed with methanol, and then dried under vacuum at about 100 ° C. for several hours to produce a crystal of an external-field-responsive metal complex.
[0012]
The molar concentration of 2,5-dihydroxybenzoic acid is preferably from 0.01 to 0.5 mol / l, more preferably from 0.05 to 0.3 mol / l.
[0013]
As the metal salt, a metal salt selected from a copper salt, a rhodium salt, a chromium salt, a molybdenum salt, a palladium salt, a zinc salt and a tungsten salt can be used, and a copper salt is preferable. In addition, as these metal salts, organic acid salts such as acetate and formate, and inorganic acid salts such as sulfate, nitrate and carbonate can be used. The molar concentration of the metal salt is about 1/2 of the 2,5-dihydroxybenzoic acid, preferably 0.002 to 0.25 mol / l, more preferably 0.02 to 0.15 mol / l.
[0014]
Organic ligands capable of bidentate coordination include pyrazine, 4,4′-bipyridyl, trans-1,2-bis (4-pyridyl) ethylene, 4,4′-azopyridine, and 4,4′-bipyridylethane And 4,4'-bisbipyridylphenylene and N- (4-pyridyl) isonicotinamide, and 4,4'-bipyridyl is preferred. The molar concentration of the organic ligand capable of bidentate coordination is approximately the same as that of the metal salt, and is preferably 0.002 to 0.25 mol / l, more preferably 0.02 to 0.15 mol / l.
[0015]
As the solvent, an organic solvent, water, or a mixed solvent thereof can be used. Specifically, alcohols such as methanol, ethanol, and propanol, diethyl ether, benzene, toluene, acetonitrile, tetrahydrofuran, dimethylformamide, hexane, acetone, water, and a mixed solvent thereof can be used.
[0016]
The reaction temperature is preferably about −20 to 100 ° C., and the reaction is performed even at room temperature.
[0017]
[Structure of metal complex]
In the metal complex of the present invention obtained as described above, as shown in FIG. 1, two oxygens of a carboxyl group and two oxygens of a dihydroxy group of 2,5-dihydroxybenzoic acid are converted into metal ions (for example, , A copper ion) to form a two-dimensional sheet in which one-dimensional chains coordinated by an organic ligand capable of bidentate coordination (for example, 4,4′-bipyridyl) are formed. Then, these two-dimensional sheets are stacked to form a packing structure. Micropores (channels) are generated in the a-axis direction. FIG. 1 schematically shows the structure of a metal complex composed of 2,5-dihydroxybenzoic acid, copper ions, and 4,4′-bipyridyl as an organic ligand for convenience.
[0018]
[Adsorption and desorption mechanism]
The metal complex of the present invention has a pillar layer structure of a π stack in which two-dimensional sheets are engaged with each other, and has pores (channels) in the a-axis direction.
[0019]
For example, when the metal complex of the present invention is composed of 2,5-dihydroxybenzoic acid, copper, and 4,4′-bipyridyl as an organic ligand, the pore size of this structure is about 3 μm. 0.0 × 3.6 °, and generally cannot adsorb molecules larger than these pores. However, the packing structure in which these two-dimensional sheets are accumulated in the metal complex of the present invention can be changed even in the crystal after synthesis, and accordingly, the structure and size of the pores are also changed. That is, as a result of adsorbing the substance, the structure can be changed to a pore structure having a more stable energy state. The conditions under which this structure changes depend on the type of the substance to be adsorbed, the adsorption pressure, and the adsorption temperature. In this way, the pores are enlarged, and large molecules are adsorbed on the enlarged pores. After the adsorbed substance is desorbed, the structure returns to its original structure, so that the pore size also returns to its original state. FIG. 2 schematically shows the mechanism by which the size of the integrated structure and the pores changes by adsorption and desorption.
[0020]
In the metal complex of the present invention, the accumulation structure of the metal complex changes and the pore size changes depending on the kind of the substance to be adsorbed, the adsorption pressure or the adsorption temperature. It starts and reaches the maximum adsorption amount instantly. The starting pressure of the adsorption differs depending on the type of the substance to be adsorbed or the adsorption temperature.
[0021]
Therefore, the adsorbent comprising the metal complex of the present invention can selectively adsorb substances such as gas. Further, the separation material comprising the metal complex of the present invention has excellent separation performance.
[0022]
The separation material of the present invention efficiently separates carbon dioxide, hydrogen, carbon monoxide, oxygen, nitrogen, hydrocarbons having 1 to 4 carbon atoms (methane, ethane, ethylene, etc.), ammonia, water vapor, or organic vapor. Can be. The organic vapor means a vaporized gas of an organic substance which is liquid at normal temperature and normal 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 compounds such as benzene, toluene and aniline; And ketones such as methyl ethyl ketone; fluorinated hydrocarbons; and halogenated hydrocarbons such as methyl chloride and chloroform. The separation material of the present invention is particularly suitable for separating carbon dioxide in methane, carbon dioxide in nitrogen, oxygen in air, methane in natural gas, and the like by a pressure swing method or a temperature swing method.
[0023]
The adsorption storage device using the adsorbent of the present invention has excellent adsorption efficiency. Further, the separation device using the separation material of the present invention has excellent separation efficiency.
[0024]
【The invention's effect】
The adsorbent comprising the metal complex of the present invention can selectively adsorb substances such as gas.
[0025]
Further, the separation material comprising the metal complex of the present invention has excellent separation performance. In particular, it is suitable for separation by a pressure swing method or a temperature swing method.
[0026]
【Example】
Hereinafter, the present invention will be described in detail with reference to Examples. The present invention is not limited to the embodiments.
[0027]
Example 1
0.13 g (0.56 mmol) of copper nitrate is dissolved in 20 ml of water, and 0.50 g (3.2 mmol) of 2,5-dihydroxybenzoic acid and 0.13 g (0.8 mmol) of 4,4′-bipyridyl are dissolved in diethyl ether. Dissolved in 20 ml. The reaction was allowed to proceed for 1 week at room temperature while diffusing the diethyl ether solution into the aqueous copper nitrate solution. Thereafter, the precipitate was filtered by suction, washed with methanol three times, and dried by heating at 100 ° C. for about 2 hours under vacuum to obtain 0.18 g of the target metal complex (single crystal).
[0028]
FIG. 3 shows the structure of this metal complex obtained by X-ray analysis. (A), (b), and (c) in FIG. 3 show the structures of the metal complex viewed from different directions.
[0029]
Example 2
With respect to the metal complex obtained in Example 1, adsorption and desorption isotherms of various gases (nitrogen, oxygen, methane, carbon dioxide (carbon dioxide)) at room temperature (298 K) were measured by a gravimetric method. The results are shown in FIGS. As is clear from the figure, the start of the adsorption depends on the adsorption pressure, and the adsorption starts suddenly at a predetermined pressure and reaches the maximum adsorption amount instantaneously. This pressure varied depending on the type of gas.
[0030]
By utilizing this feature, gas separation with higher separation performance can be performed than in the case where a conventional separation material is used.
[0031]
Example 3
With respect to the metal complex obtained in Example 1, adsorption and desorption isotherms of methane gas at various temperatures were measured by a gravimetric method. FIG. 8 shows the result. From FIG. 8, it has been found that the starting point of adsorption (pressure at which adsorption starts) depends on the temperature and can be controlled.
[0032]
By utilizing this feature, gas separation with high separation performance can be performed by the temperature swing method as compared with the case where a conventional separation material is used.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the structure of a metal complex of the present invention.
FIG. 2 is a schematic diagram showing a mechanism of adsorption and desorption in the metal complex of the present invention.
FIG. 3 is a view showing the structure of the metal complex of the present invention obtained by X-ray analysis.
FIG. 4 is a graph showing a nitrogen adsorption / desorption isotherm for the metal complex of the present invention.
FIG. 5 is a graph showing adsorption and desorption isotherms of oxygen for the metal complex of the present invention.
FIG. 6 is a graph showing the adsorption / desorption isotherm of methane for the metal complex of the present invention.
FIG. 7 is a graph showing adsorption and desorption isotherms of carbon dioxide for the metal complex of the present invention.
FIG. 8 is a graph showing adsorption / desorption isotherms at various temperatures for the metal complex of the present invention.

Claims (12)

A metal comprising 2,5-dihydroxybenzoic acid, at least one metal selected from copper, rhodium, chromium, molybdenum, palladium, zinc and tungsten, and an organic ligand capable of bidentate coordination with the metal Complex. 2,5-dihydroxybenzoic acid, at least one metal salt selected from copper salts, rhodium salts, chromium salts, molybdenum salts, palladium salts, zinc salts and tungsten salts, and organic coordination capable of bidentate coordination The metal complex according to claim 1, wherein the metal complex is obtained by reacting with an element in a solvent to cause precipitation. The organic ligand is pyrazine, 4,4′-bipyridyl, trans-1,2-bis (4-pyridyl) ethylene, 4,4′-azopyridine, 4,4′-bipyridylethane, 4,4′-bis The metal complex according to claim 1, wherein the metal complex is at least one selected from bipyridylphenylene and N- (4-pyridyl) isonicotinamide. The metal complex according to claim 3, wherein the organic ligand is 4,4'-bipyridyl. The metal complex according to any one of claims 1 to 4, wherein the metal is copper and the organic ligand is 4,4'-bipyridyl. A porous metal complex for adsorbing a gas or a liquid, wherein the integrated structure of the metal complex changes and the pore size changes depending on the kind of the substance to be adsorbed, the adsorption pressure or the adsorption temperature. 5. The metal complex according to any one of 5. An adsorbent comprising the metal complex according to claim 1. A separating material comprising the metal complex according to claim 1. The separation material according to claim 8, for separating carbon dioxide, hydrogen, carbon monoxide, oxygen, nitrogen, a hydrocarbon having 1 to 4 carbon atoms, ammonia, water vapor, or organic vapor. 9. The separation material according to claim 8, for separating carbon dioxide in methane, carbon dioxide in nitrogen, oxygen in air or methane in natural gas. An adsorption storage device using the adsorbent according to claim 7. A separation device comprising the separation material according to claim 8.

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