JP2002204953A - Production method and use method for gas adsorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for industrially advantageously producing a porous complex synthesized from copper ions and trimesic acids or their derivatives; and a method for separating and recovering and a method for storing a gas (especially, a methane or carbon dioxide gas) using the complex. SOLUTION: An adsorbent comprising a porous complex is produced by reacting copper ions with trimesic acids or their derivatives in a reaction solvent comprising a mixture of an alcohol and water. This adsorbent can be used for separating and recovering a methane or carbon dioxide gas from a gas mixture containing a methane or carbon dioxide gas by PSA or TSA and for storing a methane or carbon dioxide gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a gas adsorbent synthesized from copper ions and trimesic acids. The present invention also relates to a method for separating and recovering gas using the gas adsorbent thus obtained and a method for storing gas.

[0002]

[Prior Art] <Zeolite, molecular sieve activated carbon> PS
As the adsorbent for A, zeolite and activated carbon having molecular sieve have been widely used.

<Complex of benzenetricarboxylic acid> Several studies have been made on metal complexes of benzenetricarboxylic acid including trimesic acid. Hereinafter, a few documents describing complexes close to the complexes used in the present invention are listed as related documents.

(Literature 1) Polish chemical journal "PO
LISH JOURNAL OF CHEMISTRY (FORMERLY ROCZNIKI CHEMI
I), 60, 697 (1986) "(Reference 1) discloses a paper entitled" Production and properties of a complex of copper (II) with benzenetricarboxylic acid ". According to this article, copper (II) hemimellitate, trimesate and trimellitate are
Obtained as a hydrate salt with a metal to ligand ratio of 3: 2. There is no description about gas adsorption or description of a porous complex.

In an experiment, a complex of copper (II) and hemimellitic acid, trimesic acid or trimellitic acid was prepared by adding an equivalent of a 0.1 M solution of cupric nitrate to a hot solution of an ammonium salt of tricarboxylic acid (pH 5 to 5.5). 333-343K (60-70 ° C) in the mother liquor
The mixture is heated for 0.5 hours, filtered, washed with distilled water to remove NH ₄ ⁺ ions, and dried at 303 K (30 ° C.) until a constant weight is obtained.

The infrared absorption spectrum and powder X-ray diffraction pattern of the complex obtained are also shown. This complex is dehydrated by heating and, depending on the heating rate, is directly CuO
Or with the intermediate formation of Cu ₂ O.

(References 2, 2 ') "J. Am. Chem. Soc., 1
996, 118, 9096-9101 ”(Reference 2) includes“ 1, 3, 5
-Construction of Porous Solid from Hydrogen-Bonded Metal Complex of Benzenetricarboxylic Acid ". Here, M (II) (M = Co, Ni, Zn) acetate hydrate and 1,3,5-benzenetricarboxylic acid (BT
The aqueous mixture with (C) was placed in a furnace, heated to 140 ° C. and reacted at this temperature for 24 hours to obtain M ₃ (BTC) ₂・ 12
A substance that has been formulated as H ₂ O has been obtained and has been analyzed in detail. The obtained metal complex adsorbs and desorbs water and ammonia. However, in this document, Cu
There is no description of the complex of

[0008] Regarding this document 2 (and related documents), see "Synthesis of molecular zeolite-organic / inorganic hybrid zeolite" in "Science and Industry, 71 (10), 434-448 (1997)" (reference 2 '). The commentary titled "-" also mentions
This complex does not exchange with oxygen, nitrogen, carbon monoxide, and the like, but can reversibly adsorb and desorb water, ammonia, and the like.

(Previous Application) The applicant of the present invention has filed Japanese Patent Application No. Hei 11-1.
No. 38328 (JP-A-2000-327628) and
Complex synthesized from copper ions and trimesic acids
And [Cu_Three(C ₉H_ThreeO₆)_Two]_n A structural formula with the basic unit as
And the main spacing d in powder X-ray diffraction is
Filed an application for a porous complex qualitatively 7.60Å
You. This complex has N_Two Gas or O_Two Can adsorb gas
it can. The specific surface area of this complex, according to its example,
398, 586, 399m^Two/ g.

[0010]

Conventionally, zeolite and molecular sieve activated carbon which have been widely used as adsorbents for PSA use a special device (such as an autoclave) for synthesizing them at high temperature and high pressure. However, it cannot be denied that it is disadvantageous as a device for synthesis.

There are three types of benzenetricarboxylic acids: hemimelitic acid, trimesic acid, and trimellitic acid. Now, when benzenetricarboxylic acid is represented by BTC and a divalent metal is represented by M, the complex of the above-mentioned literature 1 and literatures 2 and 2 ′ is represented by “M ₃ (BT
C) ₂ · mH ₂ O ”. m is 1,
2, 3, 4, 5, 6, 12, and the like.

Reference 1 merely mentions the basic properties of the complex obtained therefrom, but does not mention its use. The literature 2,2 ', where together with the basic properties of the resulting complex, since there are mentioned per adsorption and desorption of water and NH ₃ gas, have been suggested use as adsorbents.

By the way, the results of X-ray diffraction of the complex of Reference 1
About the data recorded in the X-RAY POWDER DATA FILE.
You can know. According to this, the complex of the literature 1 is used.
Chi Cu _Three(C₉H_ThreeO₆)_Three・ 3H_TwoO, Cu_Three(C₉H_ThreeO₆)_TwoOf the complex represented by
Of the interplanar spacing d in powder X-ray diffraction, the main one is
They are 9.37Å and 8.93Å respectively. If [Cu_Three(C₉H_ThreeO₆)_Two] _n 
Even if it has a structural formula with a basic unit of
If something different is obtained, the complex will be
The structure of the complex is different from that of the complex 1;
The properties are different, and the application field can be expected to expand. The sentence
Complexes 2 and 2 'have a metal component of Co, Ni or Zn.
The substance is a phase complex with the Cu-based complex intended in the present invention.
Wrong.

By the way, methane can be used as a low-pollution automotive fuel, and about 10,000 vehicles equipped with a compressed gas container called CNG are running in Japan at this stage. However, because of high-pressure filling (normally 200 kg / cm ² filling), fuel capacity and safety issues still remain. Efforts to reduce internal pressure are ongoing.

Regarding carbon dioxide gas, development of a liquid layer and a solid layer absorbent for separation / selective absorption means as a first step is progressing in connection with measures to prevent global warming.

Under such a background, the present invention provides a method for industrially advantageously producing a porous complex synthesized from copper ions and trimesic acids, and further provides a gas using the complex ( In particular, it is an object of the present invention to provide a method for separating and recovering methane gas or carbon dioxide gas) and a method for storing the same.

[0017]

The process for producing a gas adsorbent according to the present invention comprises reacting copper ions with trimesic acids in a mixed solvent of alcohol and water as a reaction solvent to form a porous complex from a porous complex. Which is characterized by producing an adsorbent.

The gas separation and recovery method of the present invention uses the adsorbent obtained above to separate and recover a specific gas from a mixed gas by PSA or TSA (particularly from a mixed gas containing methane gas or carbon dioxide gas). (Separation and recovery of these gases).

The gas storage method of the present invention is characterized in that a gas (in particular, methane gas or carbon dioxide gas) is stored using the adsorbent obtained above.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

<Production Method of Adsorbent> The porous complex of the present invention is a reaction product of copper ions (copper salts) and trimesic acids.

As the copper ion source, cupric salts such as cupric acetate, cupric nitrate, cupric chloride and cupric sulfate are preferably used. However, in some cases, cuprous salts can also be used.

As the trimesic acid, trimesic acid (that is, 1,3,5-benzenetricarboxylic acid) is preferably used, and in some cases, at least one of H at positions 2, 4, and 6 of the benzene ring of trimesic acid is an alkyl. A derivative substituted with a group, an alkoxy group, a halogen, or the like can also be used.

The reaction is carried out in a solvent in which both the copper salt and trimesic acid are dissolved. In the present invention, a mixed solvent of alcohol and water is used as the reaction solvent at this time. Trimesic acids are poorly soluble in water, but that water is used in combination with alcohol.

Here, the alcohol has 1 to 1 carbon atoms.
About 5 alcohols are used singly or as a mixture of two or more kinds. In view of miscibility with water and cost, methanol, ethanol, isopropanol or n-propanol is suitable, and methanol is particularly important. .

The mixing ratio of alcohol and water is from 1:10 to 1 by volume in order to obtain a complex having a high specific surface area.
It is preferable to set 0: 1. A more preferred range is 1: 7 to 7: 1, and a particularly preferred range is 1: 5 to 5: 1. When the volume ratio of the two is out of the above range, the specific surface area of the obtained complex tends to be low.

Other solvents, for example, ketones, ethers, esters, cellosolves, polyhydric alcohols, hydrocarbons and the like may not be used because the solubility of the raw material copper salt may be deteriorated. Although it is advantageous, it may be used in combination with the above alcohol in some cases.

The amount of the solvent to be used is not particularly limited, but is preferably about 10 to 2000 times, especially about 30 to 1000 times, the total amount of the copper salt and trimesic acid on a weight basis. This is preferred in terms of ease of operation.

The molar ratio between the copper salt and trimesic acid is Cu
The standard is 2 moles of trimesic acid with respect to 3 moles of ion, but either of them may be used in excess or large excess. Preferably, excess trimesic acid,
A complex having a larger specific surface area is obtained. From the viewpoint of Cu ions, the ligand is exchanged for trimesic acids. Therefore, the latter trimesic acids are usually used in an equivalent amount (2 moles of trimesic acids per 3 moles of Cu ions) or in excess. For example, it is more advantageous to use about 2 to 10 moles of trimesic acid per 3 moles of Cu ions.
Even if trimesic acid is used in a large excess, it is advantageous in terms of the reaction, but it cannot be said that it is economically good.

The reaction temperature is 30 to 300 ° C., preferably 40 to 300 ° C.
The temperature is often 200 ° C., especially 50 to 180 ° C., but it is usually preferable to carry out the reaction at the reflux temperature. When the reaction temperature is too low, the reaction rate becomes slow, and when the reaction temperature is too high, the product may be decomposed.

As for the reaction pressure, normal pressure is sufficient, but pressurized conditions may be employed.

The reaction time varies greatly depending on the reaction temperature, and thus cannot be unconditionally determined. However, when the reaction is carried out at a reflux temperature, the reaction time is often from about 1,2 hours to one day and night. Preferably it is 3 hours or less.

After completion of the reaction, the product (complex) can be easily isolated by filtering the precipitate. After isolation of the product, washing with water or an organic solvent is performed as necessary.

It is particularly preferred that the isolated complex be immediately desolvated by heating it under reduced pressure. The heating temperature is preferably about 50 to 350 ° C. If left for several days without removing the solvent, the crystal structure of the complex changes, and the specific surface area is greatly reduced. On the other hand, when the solvent is removed, the complex is stabilized and the porous structure is maintained. Thereby, the target complex (porous complex) is obtained.

The complex thus obtained is represented by ([Cu ₃ (C
₉ H ₃ O ₆ ) ₂ ] · m (H ₂ O)) _n , having a structural formula of _n as a basic unit, and having a main plane distance d in powder X-ray diffraction of substantially 7.60 °
It is.

This complex is porous and has a large specific surface area of, for example, 900 m ² / g or more according to the BET method, and can be used as a gas adsorbent. In addition, applications such as catalysts, desiccants, separation materials, analysis materials, and battery materials can be expected.

<Method of Separating and Recovering Gas> A specific gas can be separated and recovered from a mixed gas by PSA or TSA using the adsorbent obtained above. This adsorbent is
Since it has a property of adsorbing and desorbing methane gas or carbon dioxide gas, it is particularly important for adsorption and desorption of methane gas or carbon dioxide gas from a mixed gas containing methane gas or carbon dioxide gas.

<Gas storage method> The adsorbent obtained above has a property of adsorbing a large amount of methane gas or carbon dioxide gas, and is used for storing gas (particularly, methane gas or carbon dioxide gas). Is also useful. The adsorbent storing these gases can be used, for example, as a supply source of fuel gas for automobiles and source gas of fuel cells.

[0039]

The present invention will be further described with reference to the following examples.

<Measurement method> The specific surface area was measured by Micromeritics.
BET at liquid nitrogen temperature using AccuSorb 2100E
It was measured and calculated by the method.

The gas adsorption amount is measured by a sample container containing a sample, a manifold whose volume has been measured in advance, and a pressure gauge (using a high-precision pressure measuring module manufactured by Yokogawa Electric Corporation).
And a gas absorption measuring device consisting of valves and piping (Fig. 4)
Measured using The measuring method is as follows. First, a helium gas is charged into a manifold portion, introduced into a sample container, and dead volume due to pressure drop is measured. Next, after the target gas was similarly filled in the manifold portion, the gas was introduced into the sample container, and the gas absorption was calculated from the pressure drop. The whole apparatus was put in a thermostat and measured at a constant temperature of 25.0 ° C.

EXAMPLE 1 Cupric acetate monohydrate 203.2 was placed in a 300 ml three-necked flask.
mg (1.018 mmol), and add 80 ml of methanol and 2
A mixed solvent with 0 ml was added to dissolve. 144.5 mg (0.688 mmol) of trimesic acid was added to 40 ml of methanol and 10 ml of water.
A solution dissolved in a mixed solvent with was added, and the flask was heated to start refluxing. The ratio of methanol to water in the mixed solvent is 4: 1 by volume. After cooling the next day, the precipitate was filtered and dried by blowing nitrogen gas for several hours.
322.0 mg of a dark blue complex were obtained. The complex is placed under vacuum 2
Heat treatment at 00 ° C for 2 hours, BET method (using nitrogen gas)
The specific surface area was measured to be 964 m ²
/ g.

The complex after the above-mentioned filtration and drying with nitrogen gas was stored at room temperature for 1 week without heat treatment, and then heat-treated at 200 ° C. for 2 hours under vacuum to reduce the specific surface area. Upon measurement, the specific surface area was reduced to 9 m ² / g.

EXAMPLE 2 Cupric acetate monohydrate 205.2 was placed in a 300 ml three-necked flask.
mg (1.028 mmol), and add 80 ml of methanol and 4
A mixed solvent with 0 ml was added to dissolve. 150.4 mg (0.716 mmol) of trimesic acid was added to 20 ml of methanol and 10 ml of water.
A solution dissolved in a mixed solvent with was added, and the flask was heated to start refluxing. The ratio of methanol to water in the mixed solvent is 2: 1 by volume. After cooling the next day, the precipitate was filtered and dried by blowing nitrogen gas for several hours.
335.5 mg of a dark blue complex were obtained. The complex is placed under vacuum 2
Heat treatment at 00 ° C for 2 hours, BET method (using nitrogen gas)
When the specific surface area was measured by
m ² / g.

EXAMPLE 3 Cupric acetate monohydrate 201.0 was placed in a 300 ml three-necked flask.
mg (1.007 mmol), methanol 40 ml and water 8
A mixed solvent with 0 ml was added to dissolve. 141.5 mg (0.673 mmol) of trimesic acid was added to 10 ml of methanol and 20 ml of water.
A solution dissolved in a mixed solvent with was added, and the flask was heated to start refluxing. The ratio of methanol to water in the mixed solvent is 1: 2 by volume. After cooling the next day, the precipitate was filtered and dried by blowing nitrogen gas for several hours.
229.0 mg of a deep blue complex were obtained. This complex was heat-treated under vacuum at 200 ° C. for 2 hours, and the specific surface area was measured by the BET method (using nitrogen gas).
It was 69 m ² / g.

Example 4 Cupric acetate monohydrate 409.6 was placed in a 300 ml three-necked flask.
mg (2.052 mmol), 33 ml of methanol and 6
A mixed solvent with 7 ml was added and dissolved. To this, 285.0 mg (1.356 mmol) of trimesic acid was added to 33 ml of methanol and 67 ml of water.
A solution dissolved in a mixed solvent with was added, and the flask was heated to start refluxing. The ratio of methanol to water in the mixed solvent is 1: 2 by volume. After 3 hours, the mixture was cooled, the precipitate was filtered, and dried by blowing nitrogen gas for several hours to obtain 672.7 mg of a light blue complex. This complex was immediately heat-treated under vacuum at 200 ° C. for 2 hours, and the specific surface area was measured by a BET method (using nitrogen gas) to find that the specific surface area was 1,385 m ² / g.

FIG. 1 shows the result of measuring the gas absorption of this complex. As shown in the adsorption isotherm in FIG. 1, this complex is 145 ml / methane at 1.0 MpaG and 25 ° C. for methane gas.
g, carbon dioxide gas is 0.7 MpaG, 312m at 25 ℃
l / g was absorbed, and in all cases, when the pressure was reduced, the entire amount was desorbed.

Example 5 200.8 cupric acetate monohydrate was placed in a 300 ml three-necked flask.
mg (1.006 mmol), 25 ml of methanol and 7
A mixed solvent with 5 ml was added to dissolve. 140.7 mg (0.670 mmol) of trimesic acid was added to 10 ml of methanol and 30 ml of water.
A solution dissolved in a mixed solvent with was added, and the flask was heated to start refluxing. The ratio of methanol to water in the mixed solvent is 1: 3 by volume. After cooling the next day, the precipitate was filtered and dried by blowing nitrogen gas for several hours.
297.8 mg of a deep blue complex were obtained. This complex was heat-treated at 200 ° C. for 2 hours under vacuum, and the specific surface area was measured by the BET method (using nitrogen gas).
It was 44 m ² / g.

Comparative Example 1 Cupric acetate monohydrate 200.2 was placed in a 300 ml three-necked flask.
mg (1.003 mmol) was added and dissolved by adding 100 ml of ethanol. A solution of 420.8 mg (2.002 mmol) of trimesic acid dissolved in 50 ml of ethanol was added thereto, and the mixture was heated under reflux for one week. Then, the heating was stopped, the mixture was cooled, and the precipitate was filtered and dried by blowing nitrogen gas to obtain 156.3 mg of a blue precipitate. This complex was heat-treated at 120 ° C. for 1 hour under vacuum, and the specific surface area was measured by the BET method (using nitrogen gas).
It was 8 m ² / g.

Comparative Example 2 A cupric acetate monohydrate (1.0443) was placed in a 300 ml three-necked flask.
g (5.231 mmol) was added and dissolved by adding 200 ml of methanol. A solution prepared by dissolving 2.1160 g (10.069 mmol) of trimesic acid in 70 ml of ethanol was added thereto, and the mixture was heated under reflux for one week. Then heating was stopped, cooled, and the precipitate was filtered and dried by blowing nitrogen gas.
0.7507 g of a blue precipitate was obtained. This complex is placed under vacuum
Heat treatment at 20 ° C for 1 hour, BET method (using nitrogen gas)
The specific surface area was determined to be 338 m ²
/ g.

Reference Example 1 The specific surface area of the molecular sieves 5A (manufactured by Bayrit) was measured by the BET method (using nitrogen gas).
It was 360 m ² / g. Further, when the gas absorption amount of this molecular sieve 5A was measured, as shown in the adsorption isotherm in FIG.
45 ml / g at ℃, 0.4 MpaG, 25 for carbon dioxide gas
At 112C / 112 ml / g were absorbed.

Reference Example 2 The amount of gas adsorbed on activated carbon ("Shirasagi" manufactured by Takeda Pharmaceutical Co., Ltd.) was measured. As shown in the adsorption isotherm in FIG. 3, methane gas was 0.4 MpaG, 62 ml at 25 ° C. / g,
120 ml / g at 0.4 MpaG, 25 ° C for carbon dioxide gas
Was absorbed.

<Summary> Examples 1 to 5 and Comparative Examples 1 to
Table 1 shows the results of No. 2. From Table 1, in Examples 1 to 5 using a mixed solvent of alcohol and water as the solvent,
It can be seen that an adsorbent comprising a porous complex having a remarkably large specific surface area can be obtained as compared with Comparative Examples 1 and 2 using only alcohol as a solvent.

[0054]

[Table 1]

As described in the section of Example 1, the product after the completion of the reaction was isolated and immediately heated under reduced pressure to remove the solvent, and the specific surface area was 964 m ² / g. In contrast, the specific surface area without such desolvation was only 9 m ² / g, indicating that it was important to desolvate after isolating the product.

Further, when the adsorbent obtained in Example 4 was compared with the zeolite of Reference Example 1 and the activated carbon of Reference Example 2, as shown in FIGS. 1 and 2, the adsorption of methane gas and carbon dioxide gas was confirmed. It can be seen that there is a large difference in terms of sex.

[0057]

According to the present invention, an adsorbent comprising a porous complex having an extremely large specific surface area is obtained by reacting copper ions with trimesic acids in a mixed solvent of alcohol and water.

For this reason, this adsorbent can be used for a method for separating and recovering a specific gas from a mixed gas (particularly, PSA or TSA from a mixed gas containing methane gas or carbon dioxide gas).
Is suitable for a method of separating and recovering methane gas or carbon dioxide gas), and is also suitable for a method of storing gas (particularly, a method of storing methane gas or carbon dioxide gas).

[Brief description of the drawings]

FIG. 1 is an adsorption isotherm of methane gas and carbon dioxide gas of the complex of Example 4.

FIG. 2 is an adsorption isotherm of methane gas and carbon dioxide gas of the molecular sieve 5A of Reference Example 1.

FIG. 3 is an adsorption isotherm of activated carbon of Reference Example 2 for methane gas and carbon dioxide gas.

FIG. 4 is an explanatory diagram of a gas absorption amount measuring device used in an experiment.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shinichi Ando 2-4-1-11 Utsuhoncho, Nishi-ku, Osaka-shi, Osaka Inside Taiyo Toyo Oxygen Co., Ltd. (72) Inventor Takashi Sekiya 2-Utsuhoncho, Nishi-ku, Osaka-shi, Osaka No. 4-11 Taiyo Toyo Oxygen Co., Ltd. F term (reference) 4D012 BA01 4G066 AA15A AA32A AA47A AA53A AB03A AB07A AB24B BA26 CA35 CA56 DA04 FA03 FA21 FA35 FA37

Claims (10)

[Claims] 1. A gas adsorbent comprising reacting copper ions with trimesic acids in a mixed solvent of alcohol and water as a reaction solvent to produce an adsorbent comprising a porous complex. Manufacturing method. 2. The method according to claim 1, wherein the porous complex is ([Cu ₃ (C ₉ H ₃ O ₆ ) ₂ ] · m (H
_{2. The} method according to claim 1, wherein the compound has a structural formula having ₂ O)) _n as a basic unit. 3. The porous complex having a specific surface area of 9 by a BET method.
2. The method according to claim 1, wherein the amount is at least 00 m ² / g. 4. The process for producing a gas adsorbent according to claim 1, wherein the isolated product is desolvated after the reaction. 5. The method for producing a gas adsorbent according to claim 4, wherein the desolvation method is performed by heating under reduced pressure. 6. The method for producing a gas adsorbent according to claim 1, wherein the mixing ratio of the alcohol and water is 1:10 to 10: 1 by volume. 7. A method for producing PS using the adsorbent obtained in claim 1.
A method for separating and recovering a specific gas from a mixed gas using A or TSA. 8. The method for separating and recovering gas according to claim 7, wherein methane gas or carbon dioxide gas is separated and recovered from the mixed gas containing methane gas or carbon dioxide gas by PSA or TSA. 9. A method for storing gas, comprising using the adsorbent obtained in claim 1 to store gas. 10. The gas storage method according to claim 9, wherein the gas to be stored is methane gas or carbon dioxide gas.