JPH09227572A - Gas-storing organometallic complex, its production, gas-storing apparatus and automobile furnished with gas-storing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new metal complex having gas-storing property, a gas- storing apparatus using the gas-storing property of the complex and an automobile furnished with the gas-storing apparatus. SOLUTION: This three-dimensional organic metal complex is composed of a bivalent metal ion, an organic ligand capable of forming a bidentate coordination and 2,3-pyrazinedicarboxylic acid and has a laminar structure. The complex can adsorb and store gas molecules in the space of crystal lattice. A compound having a relatively rigid molecular skeleton such as pyrazine and 4,4'- bipyridyl and having coordinating atoms on both ends is used as the organic ligand capable of forming a bidentate coordination. The gas-storing apparatus is composed of a pressure vessel having a gas-inlet and outlet port and a gas- storing three-dimensional organic metal complex composed of a bivalent metal ion, an organic ligand capable of forming a bidentate coordination and 2,3- pyrazinedicarboxylic acid, having a laminar structure and held in the space of the vessel. The automobile is furnished with the gas-storing apparatus.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel metal complex, which has voids capable of accommodating molecules in its crystal structure,
It relates to metal complexes having the ability to store gas. An object of the present invention is to provide a metal complex which has a novel structure as a metal complex and can be used for a new application or can realize a higher function. The present invention also provides
The present invention also relates to a gas storage device using the metal complex, and a transportation means, particularly an automobile, equipped with the gas storage device. Further, the metal complex according to the present invention can be used for a reaction catalyst, a carrier thereof, a treating agent for adsorbing and removing a specific component in a gas composition, and a treating apparatus.

[0002]

2. Description of the Related Art As a technique for storing flammable gas,
Simply pressurize, compress the volume and fill the cylinder at high pressure, cool to liquefy and fill the insulated container,
There is known a method in which a gas, such as acetylene, which can be compressed only at a relatively low pressure is dissolved in a solvent such as acetone and then filled in a cylinder. As a transportation means that uses gas as an energy source, a passenger car using LP gas filled in a cylinder as a fuel is known.

[0003]

In the method of storing gas, in the method of simply pressurizing, a special pressurizing device for increasing the pressure is required, and it is used for hydrogen gas, methane gas and the like. 20 MPa (200 kgf / c
In order to secure the ability to withstand a high pressure of up to m ² ), the weight of the cylinder becomes extremely heavy and it is difficult to handle and convey. Further, the liquefying method also requires a special compression device and cooling device, and the container also needs a special structure in order to ensure heat retention performance. Furthermore, those that use solvents
In addition to the solvent vapor being mixed in the gas, the transport weight is added by the amount of the solvent, which is wasteful and can be used only for a special gas. In recent years, porous alloys for storing hydrogen have been developed, but they are expensive and the kinds of gas components are limited.

On the other hand, as a dicarboxylic acid copper complex,
A complex having a layered structure has been found, and the applications utilizing the structure are expected to have functions such as storage by gas adsorption / occlusion, a catalyst, and a molecular sieve. These complexes are
It has been elucidated that it has a space in its crystal structure and can adsorb and store various gas components depending on the size of the space and the characteristics of the constituents, and further development of various metal complexes is expected. To be done. Further, in the present invention, LP
A gas transportation other than gas can also be used as an energy source, and a transportation means equipped with a lightweight storage device is also provided.

[0005]

The present invention relates to a divalent metal ion, a bidentate coordinating organic ligand having an atom capable of coordinating with the metal ion at both ends of a rigid skeleton, and 2 , 3
-It relates to an organometallic complex composed of pyrazine dicarboxylic acid, having a layered structure and capable of storing gas. The bidentate-coordinating organic ligand which comprises the metal complex and has atoms capable of coordinating with the metal ion at both ends of the rigid skeleton is pyrazine, 4,4′-bipyridyl, trans-1,
Organic coordination selected from 2-bis (4-pyridyl) ethylene, 1,4-dicyanobenzene, 4,4′-dicyanobiphenyl, 1,2-dicyanoethylene, 1,4-bis (4-pyridyl) benzene Is a child.

As such a complex, copper ion (Cu ²⁺ ) is used as a divalent metal ion.

Embedded image Cu ₂ (bpy) (byzdc) ₂ (bpy is 4,4′-bipyridyl, byzdc is 2,3
-Represents pyrazine dicarboxylic acid. ) A metal complex represented by

The organic ligand used in the present invention has a rigid molecular structure, and its action forms a space in the crystal lattice capable of adsorbing and storing gas. "Rigid molecular structure"
And does not include a rotatable bond such as C-C bond,
Therefore, it means a molecular structure in which the distance between the atoms capable of coordinating to the metal does not change. A ligand having an atom such as nitrogen capable of coordinating with a metal ion at both ends of such a molecule is preferable. It is particularly preferable that the coordinable atoms are present in the molecule of the organic ligand at both ends thereof in point symmetry within the molecule.

The metal complex of the present invention comprises a solution of a divalent metal ion, a bidentate coordinating organic ligand having atoms capable of coordinating with the metal ion at both ends of a rigid skeleton, and 2, Three
It is obtained by mixing and reacting a solution of pyrazinedicarboxylic acid at a predetermined ratio, and is synthesized by selecting conditions suitable for crystal growth.

The invention also relates to a gas storage device. An example is shown in FIG. 3, and will be described based on this figure. In the gas storage device 1, a divalent metal ion is placed in a space 5 formed inside a pressure resistant container 2 provided with gas inlets and outlets 4a and 4b. A bidentate-coordinating organic ligand having atoms capable of coordinating with the metal ion at both ends of a rigid skeleton, and 2,3-
It is composed of pyrazine dicarboxylic acid and has a layered structure,
It is configured by housing a three-dimensional organometallic complex 3 capable of storing gas. Such a storage device can be filled with a gas by using a simple filling device, and can store a large amount of gas in a state of low internal pressure because it contains a metal complex having a gas adsorbing ability, The structure of the storage device itself can be designed to be simple and lightweight, and it becomes possible to easily transport methane, natural gas, etc., which are fuels for the internal combustion engine, the fuel cell and the like. Therefore, such a storage device is
It can be used as an energy supply source for transportation means such as automobiles and ships, and auxiliary equipment such as generators and refrigerators used therefor.

The gas-storable metal complex used in the gas storage device is pyrazine, 4,4'-bipyridyl, trans-1, as a bidentate coordinating organic ligand.
Organic coordination selected from 2-bis (4-pyridyl) ethylene, 1,4-dicyanobenzene, 4,4′-dicyanobiphenyl, 1,2-dicyanoethylene, 1,4-bis (4-pyridyl) benzene It is preferable to use a child. This is because the metal complex using such a ligand can form a crystal lattice space capable of adsorbing gas. Of these metal complexes, those having a chemical structure represented by the above [Chemical Formula 3] are particularly preferable. The reason is that 4,4'-bipyridyl forms a crystal lattice space suitable for adsorptive storage of methane due to its chemical structure.
In addition, 1,4-bis (4-pyridyl) benzene also forms a preferable complex for the same reason.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a divalent metal ion, a bidentate-coordinating organic ligand having atoms capable of coordinating to the metal ion at both ends of a rigid skeleton, and 2,3 -A three-dimensional organometallic complex composed of pyrazine dicarboxylic acid, having a layered structure and capable of storing gas. Such a metal complex forms a relatively large space between layers based on its layered structure, and since the space has a size capable of accommodating gas molecules, it is presumed that gas adsorption and storage performance can be obtained. To be done.

Bidentate-coordinating organic ligands constituting the metal complex of the present invention include pyrazine, 4,4'-bipyridyl, trans-1,2-bis (4-pyridyl) ethylene, 1, and 1.
An organic ligand selected from 4-dicyanobenzene, 4,4′-dicyanobiphenyl, 1,2-dicyanoethylene, and 1,4-bis (4-pyridyl) benzene is preferable. Such a ligand has an atom capable of coordinating with a metal ion, preferably a nitrogen atom, at both ends of the molecule, and since the molecule has rigidity, both ends thereof, preferably the position of point symmetry in the molecule. The nitrogen atoms present in each coordinate to different metal ions, the (metal ion-ligand) repeating structure is formed in the crystal lattice of the complex, and such lattices are optionally stacked. It is believed that the formation of the structure forms a gas-storable layered structure. Since the distance between the atoms coordinated to the metal, here the nitrogen atom, in the ligand is determined by this ligand, the size of the adsorbed molecule can be changed by selecting the ligand, Therefore, it becomes possible to select a gas component that can be stored. It may also change depending on the anion of the metal salt that is the raw material compound.

Suitable metal ions for the complex include alkaline earth metal ions such as beryllium, magnesium, calcium, strontium and barium, Group VIII metal ions such as iron, cobalt, nickel and palladium, copper, zinc and cadmium. Metal ions such as mercury, lead and manganese can be used. Sulfates, nitrates, perchlorates, tetrafluoroborates, hexafluorophosphates, halogens, carbonates, formates and acetates of these metal ions can be used. Etc. can be used as a raw material of the metal ion. In particular, those using copper ions as metal ions are preferable, and in this case, the raw material used is copper sulfate,
Inorganic salts such as copper nitrate and copper carbonate, and organic salts such as copper formate and copper acetate can be used.

The metal complex is obtained by mixing a solution of a metal ion salt, a solution of an organic ligand, and a solution of 2,3-pyrazinedicarboxylic acid, reacting them, and complexing them. Are mixed so that the ratio becomes a predetermined ratio, and the mixture is stirred uniformly and then reacted under predetermined conditions to form a crystal of a complex. The reaction conditions differ depending on the combination of the metal ion and the ligand, but even if the powder is apparent, a sufficient space in the crystal cannot be obtained unless the crystal grows to a certain size. Preferably, the reaction is carried out for a long time under conditions close to room temperature. If necessary, the reaction may be promoted by heating and the solvent may be evaporated. Reaction temperature is -10 ℃
-100 ° C, preferably 10 ° C-60 ° C.

In the present invention, the solvent for dissolving the metal salt is preferably water, acetone, alcohols such as methanol and ethanol, and other solvents capable of dissolving the metal salt without being strongly coordinated with the metal, either alone or Use by mixing. Further, as a solvent for dissolving the organic ligand, a solvent that does not strongly coordinate to a metal can be used. In addition to water, ketones such as acetone, MEK and MIBK, esters such as ethyl acetate and butyl acetate, and methanol. And alcohols such as ethanol, acetonitrile, tetrahydrofuran,
Organic solvents such as dioxane, dimethylformamide, dimethylacetamide, toluene and hexane are used alone or in combination.

The above-mentioned solvents used for producing the metal complex of the present invention may be those which are uniformly miscible with each other or those which are phase-separated without being miscible with each other.
In the case of “mixing”, for example, water and acetone, water and ethanol, and other combinations that are uniformly compatible at any ratio, as well as water and methyl ethyl ketone (which are compatible only within a certain composition range). A combination such as MEK) may be used. The solvent is selected in consideration of the solubility of the raw material compound, the compatibility of the solvent itself, the solubility of the complex formed, the influence on the reaction and the like. When a combination of solvents such as water and hexane that completely phase separates, crystals are formed at the separated interfaces.

The obtained complex is filtered by a conventional method and dried. Drying is preferably carried out by heating under reduced pressure.
If the drying is insufficient, solvent molecules remain in the crystal lattice space, the gas adsorption performance is not sufficiently exhibited, and the solvent content of the gas desorbed after adsorption increases. When using a low-volatile solvent such as water, wash with a highly volatile organic solvent compatible with the water, further, an organic solvent azeotropic with a low-volatile solvent such as water, For example, ethanol for water,
It is also a preferred embodiment to wash with a hydrophilic solvent such as acetone and then dry.

Next, a gas storage device using the complex of the present invention will be described with reference to FIG. The gas storage device 2 is
It is a closed container provided with a gas inlet / outlet, and preferably a pressure resistant container. The gas inlets / outlets 4a and 4b may be separately attached to the container body, and may also serve as one or two.
A heavy pipe structure may be used. The pressure indicator can be attached freely. In the space inside the container body, a three-dimensional organometallic complex 3 composed of metal ions, an organic ligand capable of bidentate coordination, and 2,3-pyrazinedicarboxylic acid, having a layered structure and capable of storing gas is provided. It is configured to be stored. Inside the container body, a compartment 5, a shelf 6, etc. are provided in order to improve the contact between the stored complex and the gas and the flow of the gas. When the complex is a powder, the compartment 5 is made of a mesh material. , It is preferable to manufacture the shelves 6 and the like.
Alternatively, molding into pellets is also a preferred embodiment.
It is also preferable to provide a device for heating / cooling for promoting the adsorption and desorption of the gas component to be stored in the complex, on the outer peripheral portion of the container body or, if necessary, inside thereof. Note that FIG.
In the above example, the space 7 is provided in order to improve the flow of gas.

The metal complex housed in the gas storage container is the complex described in claim 1 or 2, and by using such a complex, the gas can be stored at a relatively low pressure, and the container is filled with the gas. It does not require a special pressurizing device or cooling device, nor does it need a special heat insulating container to store and transport gas. The filling of the gas storage container according to the present invention with gas is performed by feeding the gas into the storage container via a suitable gas pressurizing device. At this time, since the adsorption of the gas to the metal complex is usually an exothermic reaction, it is preferable to cool the container at the same time. When the stored gas is taken out from the gas storage container of the present invention, the pressure on the take-out side is set to a relatively low pressure with respect to the storage device, and at the same time, the storage device is heated to promote it.

FIG. 4 exemplifies a schematic configuration of a gas vehicle 9 equipped with the gas storage device 1. In this example, the gas vehicle 9 includes, as a fuel supply source, a gas storage device 1 in which the gas-storing metal complex of the present invention is stored, and a flammable gas such as natural gas stored in the gas storage device 1 is used. The engine 10 is provided as an internal combustion engine that uses fuel. In addition to this example, an automobile using a fuel cell using gas fuel as an energy source and a motor as a drive source is also possible. The gas storage device used in the automobile shown in FIG. 4 is an embodiment different from that shown in FIG.

[0021]

Embodiments of the present invention will be described below. (Complex Synthesis Example 1) In a 50 ml aqueous solution of 0.02 M copper sulfate,
50 ml of a mixed solvent solution of 0.01 M of bipyridyl and 0.02 M of 2,3-pyrazinedicarboxylic acid in ethanol / water = 1/1 was added and mixed, and the mixture was left at room temperature for 1 day to form a blue precipitate. After suction filtration, vacuum drying at room temperature gave 0.35 g of the target complex. Elemental analysis of this complex has revealed that the composition formula is represented by [Cu ₂ (bpy) (pyzdc) ₂ ] _n .

The crystal was analyzed by X-ray diffraction and the structure was analyzed. As a result, the layer structure formed by Cu and pyzdc was found to be b.
It is presumed that they are connected by py to form a multi-layered structure to form a crystal, and a space capable of storing gas is formed between the layers. FIG. 1 schematically shows this layer structure.

(Measurement of Gas Storage Capacity 1) Obtained in Complex Synthesis Example 1,

## STR00004 ## The methane adsorption capacity of the complex having the composition Cu ₂ (bpy) (pyzdc) ₂ was measured. The experimental conditions were as follows: gas used: methane (purity 99.99%) temperature: 25 ° C. time: until equilibrium was reached (several seconds). The results are shown in FIG. From this result,
It can be seen that the metal complex having the composition shown in 1) has selectivity for the adsorption of methane.

[0024]

[Brief description of drawings]

FIG. 1 is a schematic diagram of a crystal structure of a complex having a Cu ₂ (bpy) (pyzdc) ₂ composition.

FIG. 2 is a graph showing measurement performance of methane gas adsorption characteristics of a metal complex using Cu.

FIG. 3 is a schematic diagram of a gas storage device.

FIG. 4 is a model diagram of a gas vehicle.

[Explanation of symbols]

 1 Gas Storage Device 2 Pressure Vessel 3 Metal Complex 4a Gas Outlet 4b Gas Inlet 5 Section 6 Shelf Member 7 Space 9 Automotive 10 Internal Combustion Engine

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C10L 3/06 6958-4H C10L 3/00 D F01K 27/00 6958-4H A

Claims (10)

[Claims] 1. A divalent metal ion, a bidentate-coordinating organic ligand having an atom capable of coordinating with the metal ion at both ends of a rigid skeleton, and 2,3-pyrazinedicarboxylic acid. A gas-storable organometallic complex. 2. The organic ligand capable of bidentate coordination is pyrazine, 4,4′-bipyridyl, trans-1,2-bis (4-pyridyl) ethylene, 1,4-dicyanobenzene, 4, The gas-storable organometallic complex according to claim 1, which is an organic ligand selected from 4'-dicyanobiphenyl, 1,2-dicyanoethylene, and 1,4-bis (4-pyridyl) benzene. 3. Cu ₂ (bpy) (pyzdc) ₂ (bpy is 4,4′-bipyridyl, pyzdc is 2,3)
-Represents pyrazine dicarboxylic acid. The gas-storing organometallic complex according to claim 1, which is represented by the formula (1). 4. A solution of a divalent metal ion, a solution of a bidentate-coordinating organic ligand having atoms capable of coordinating with the metal ion at both ends of a rigid skeleton, and 2,3-pyrazine. A solution of a dicarboxylic acid is mixed at a predetermined ratio and reacted, which is composed of a divalent metal ion, a bidentate-coordinable organic ligand, and 2,3-pyrazinedicarboxylic acid,
A method for producing an organometallic complex having a layered structure and capable of storing gas. 5. An organic ligand capable of bidentate coordination is pyrazine, 4,4′-bipyridyl, trans-1,2-bis (4-pyridyl) ethylene, 1,4-dicyanobenzene, 4,4. A gas-storable metal having a layered structure according to claim 4, which uses an organic ligand selected from'-dicyanobiphenyl, 1,2-dicyanoethylene, 1,4-bis (4-pyridyl) benzene. Method for producing complex. 6. A solution of Cu ions as divalent metal ions, a solution of 4,4′-bipyridyl as an organic ligand capable of bidentate coordination, and a solution of 2,3-pyrazinedicarboxylic acid at a predetermined ratio. 5. The method for producing a gas-storable organometallic complex having a layered structure according to claim 4, wherein the method is carried out by mixing. 7. A bidentate coordination having a divalent metal ion and an atom capable of coordinating with the metal ion at both ends of a rigid skeleton in a space formed inside a pressure-resistant container having a gas inlet / outlet port. A gas storage device, which is composed of a possible organic ligand and 2,3-pyrazinedicarboxylic acid, has a layered structure, and stores a gas-storable organometallic complex. 8. A gas storable metal complex, wherein the organic ligand capable of bidentate coordination is pyrazine, 4,4′-bipyridyl, trans-1,2-bis (4-pyridyl) ethylene, 1, 8. An organic ligand selected from 4-dicyanobenzene, 4,4'-dicyanobiphenyl, 1,2-dicyanoethylene, 1,4-bis (4-pyridyl) benzene is used. Gas storage device. 9. The gas storable metal complex is represented by the following formula: Cu ₂ (bpy) (pyzzdc) ₂ (bpy is 4,4′-bipyridyl, pyzdc is 2,3
-Represents pyrazine dicarboxylic acid. 8. The gas storage device according to claim 7, which is represented by 10. An automobile equipped with the gas storage device according to claim 7, 8 or 9, and moving by using gas supplied from the gas storage device as an energy source.