JP2934763B2 - Oxygen adsorbent - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an oxygen adsorbing / desorbing agent, and particularly to an oxygen adsorbing agent suitable as an adsorbent when separating oxygen in air by an adsorption method such as a pressure or temperature fluctuation type. It relates to a desorbing agent.

[Prior art] A pressure fluctuation type air separation method (PSA) that separates oxygen by varying the pressure or temperature using an adsorbent that preferentially adsorbs oxygen or nitrogen when separating and sampling oxygen in the air. ) Or a temperature-varying air separation method (TSA) is known. As the adsorbent, a natural or synthetic zeolite that preferentially adsorbs nitrogen, carbon molecular sieves in which oxygen adsorbs faster than nitrogen, and improved ones thereof are used.

[Problems to be solved by the invention]

However, in each of the above, it is difficult to obtain high-purity oxygen because both of them adsorb both oxygen and nitrogen, and to obtain high-purity oxygen, the yield must be sacrificed.

In addition, various complexes are known to have oxygen adsorbing ability. However, they usually have a problem that they do not react with oxygen unless the temperature is lower than room temperature or deteriorate in a solution state.

Therefore, the present invention reacts only reversibly with oxygen at room temperature,
An object of the present invention is to provide an oxygen adsorbing / desorbing agent which does not deteriorate even when repeatedly used and can obtain high-purity oxygen in a high yield and with a low power consumption.

[Means for solving the problem]

In order to achieve the above object, the oxygen adsorbent of the present invention is characterized in that an axis ligand is dispersed and fixed in an ion exchange resin by ionic or covalent bond, and the axis ligand has a complex having an oxygen adsorption ability. It is characterized by being fixed by a coordination bond, and in particular, the axial ligand is an axial ligand in which the oxygen adsorbing ability of the complex is increased by coordinating to a complex having an oxygen adsorbing ability. It is characterized by the following.

The ion exchange resin is used as a carrier for fixing a complex that selectively adsorbs and desorbs oxygen.
The axial ligand is used to increase the oxygen adsorbing ability of the complex, but also plays a role as a chain for fixing the complex to the ion exchange resin.
Various types of these can be used depending on the bonding structure between the ion exchange resin and the axial ligand. The axial ligand is, for example, a complex having a 6-coordinate structure,
A ligand coordinated to the sixth or sixth coordination locus, which is referred to as axial base or axial ligand in English.

First, the above-mentioned axial ligand is pyridine, imidazole, alkylamine or a derivative thereof, and those having an ionic bond or a functional group such as a vinyl group are used.

This functional group is necessary to disperse and fix the axial ligand in the ion exchange resin. Examples of the axial ligand having an ionic bond as a functional group include 3-methyl-1,
1'-dodecyldiimidazolium iodide; 1- (3-aminopropyl) imidazole hydrochloride; Sodium 4-pyridineethanesulfonic acid; 4-picolylamine hydrochloride; And the like.

These axial ligands having an ionic bond are coordinated by the lone electron pair of the nitrogen atom of the imidazole or pyridine group being donated as the central metal of the complex, but the moiety having the ionic bond has the nitrogen atom described above. When it is close to an atom, the electron pair donating property of the nitrogen atom is weakened. As a result, the oxygen-adsorbing ability of the complex may also be weakened. Therefore, a structure having at least one alkyl carbon between the complex and the ion-binding portion of imidazole or pyridine is preferable.
More preferably, it has three or more alkyl carbons, and the most preferred structure has 10 or more alkyl carbons.

Examples of the axial ligand having a vinyl group as a functional group include 4-vinylpyridine; 1-vinylimidazole; And the like.

Examples of the axial ligand having a hydroxyl group as a functional group include 4- (imidazol-1-yl) phenol; 3-pyridinepropanol; 8- (imidazol-1-yl) octanol; And the like.

Examples of the axial ligand having an amine as a functional group include 1- (3-aminopropyl) imidazole; 4-aminopyridine; And the like.

Next, various types of ion exchange resins can be used for dispersing and fixing the axial ligand having an ionic bond as a functional group.

For example, when an imidazole group or a pyridine group is present in the cation portion, as in the case of 1- (3-aminopropyl) imidazole hydrochloride, a cation exchange resin is used, and as in the case of the sodium 4-pyridineethanesulfonate, When a pyridine group or an imidazole group is present in the anion part, an anion exchange resin is used.

When using a cation exchange resin, it is desirable to use a cation exchange resin having a sodium-type functional group. At this time, if a cation exchange resin having a proton functional group is used, protons remaining in the resin after the reaction may react with the complex to deteriorate the complex. Therefore, when using a proton type cation exchange resin,
It is desirable to perform ion exchange with a cation such as Na ⁺ to convert to a cation type other than proton.

In the case where the functional group of the axial ligand is 4-vinylpyridine or the like in which the functional group is a vinyl group, this is fixed by a covalent bond. For example, by reacting an axial ligand having a vinyl group with a monomer such as styrene to synthesize a copolymer, a porous polymer resin in which the axial ligand is dispersed and fixed can be obtained. This synthesis can be easily carried out according to a conventional method. In addition to a crosslinking agent such as divinylbenzene, a polymerization initiator such as azobisisobutyronitrile, a dispersion / suspension stabilizer such as polyvinyl alcohol, and amyl alcohol It is necessary to add a polymer precipitant such as

A cation exchange resin having a sulfone group can be used as the ion exchange resin for dispersing and fixing an axial ligand having a marine group or an amine as a functional group. When this type of resin is treated with, for example, phosphorus pentachloride, the above sulfone group is converted to sulfonyl chloride according to the following formula.

(In the above formula, R represents a resin.) Since this sulfonyl chloride easily reacts with a hydroxyl group or an amine, the axial ligand can be dispersed and fixed in the cation exchange resin by this reaction. For example, in the case of 8- (imidazol-1-yl) octanol, it is fixed by the following reaction.

(In the above formula, R represents a resin.) In the case of the 1- (3-aminopropyl) imidazole, the immobilization is carried out by the reaction of the following formula.

(In the above formula, R represents a resin.) In addition to the ion exchange resin, any type of ion exchange resin having a functional group capable of reacting with the functional group contained in the axial ligand is generally used. But you can use it.

In this way, the complex having oxygen adsorption ability is coordinated to the axis ligand of the ion exchange resin containing the axis ligand in which the axis ligand is dispersed and fixed in advance, and the axis ligand is dispersed and fixed in the resin.

As the complex having the oxygen adsorption ability, those generally known as oxygen carriers and the like can be used, and by performing a coordination bond with the axial ligand of the axial ligand-containing ion exchange resin, One that reversibly adsorbs and desorbs oxygen at room temperature and near normal pressure is selected. Examples of such a complex having an oxygen adsorption ability include a general formula; (In the above formula, R ¹ , R ² , and R ³ each represent hydrogen or an alkoxy group such as OCH ₃ or an alkyl group such as CH ₃ or a phenyl group; R ⁴ represents hydrogen or a methyl group or a phenyl group;
R ⁵ , R ⁶ , R ⁷ and R ⁸ each represent hydrogen, an alkyl group such as CH ₃ or a phenyl group. A) a complex represented by the formula or a general formula; (Wherein, R ¹ and R ² each represent hydrogen, a methyl group or a phenyl group.) A complex represented by the following general formula: (In the above formula, R ¹ represents hydrogen or a phenyl group, and R ² represents hydrogen or an alkyl group such as CH _3. ).

Each of these complexes has a four-coordinate structure, and usually has a six-coordinate structure and is stable. Therefore,
When the axial ligand is coordinated to the fifth coordination site of this complex, the oxygen adsorbing ability of the sixth coordination site increases, and oxygen is adsorbed here.

As the complex, generally, any complex can be used as long as it has an oxygen adsorption ability when the axial ligand is coordinated to the fifth coordination site. It is preferable to use one having a solubility in a polar solvent described later of 0.1 M or more. Specifically, (N, N'-bis (4-methoxysalicylaldehyde) dimethylethylenediamine) cobalt; Or (N, N'-bis (4-methoxysalicylaldehyde) tetramethylethylenediamine) cobalt; Etc. can be raised.

In order to coordinate the complex with the axial ligand, it is necessary to bring the axial ligand dispersed and fixed in the ion-exchange resin close to the complex. That is, it is necessary to make the complex movable in the ion-exchange resin and contact the axial ligand in the resin.

The contact between the two is carried out by dissolving the complex in a polar solvent to prepare a complex solution, immersing the axial ligand-containing ion-exchange resin in the complex solution, and dissolving the complex solution in 50 to 15 times.
It can be carried out by swelling the ion exchange resin by heating to a temperature of 0 ° C, preferably 70 to 130 ° C. Thereby, the complex can move in the resin, and the coordination bond between the axial ligand fixed inside the resin and the complex becomes possible.

Examples of the polar solvent include γ-butyrolactone; Dimethyl sulfoxide; Dimethylformamide; (CH ₃ ) ₂ NCHO 1-methyl-2-pyrrolidinone (N-methylpyrrolidinone); Sulfolane; However, in order to reduce evaporation loss of the polar solvent during heating, it is preferable to use one having a high boiling point.

Further, since the complex solution is heated, a dimerization reaction of the complex occurs due to oxygen that is a solvent in the complex solution, and the oxygen adsorbing ability of the complex may be deactivated. Therefore, when the axial ligand-containing ion exchange resin is immersed in the complex solution and heated, it is preferable to make the solution oxygen-free by bubbling an inert gas such as an argon gas.

At this time, if the heating temperature of the complex solution is less than 70 ° C., the swelling of the ion exchange resin is insufficient, and it is difficult to sufficiently coordinate the axial ligand and the complex. 13
When the temperature exceeds 0 ° C., the decomposition of the complex occurs, the loss of evaporation of the polar solvent increases, and the energy for heating is wasted.

As described above, by heating the complex solution to coordinate the axial ligand in the ion exchange resin with the complex, the oxygen adsorbing / desorbing agent of the present invention can be obtained. The complex not coordinated with the ligand remains in the ion exchange resin due to physical adsorption. This complex that could not coordinate has not only weak oxygen adsorption capacity, but also inhibits the movement and diffusion of oxygen in the oxygen adsorbent during oxygen adsorption separation, deteriorating the performance of the oxygen adsorbent. There is a possibility that it will be done.

Therefore, it is preferable to remove the complex remaining in the ion exchange resin by physical adsorption after performing the above-mentioned coordination bond. The removal of the complex can be carried out by separating the obtained oxygen adsorbing / desorbing agent from the complex solution and washing with an appropriate solvent such as acetone.

Then, by drying the oxygen adsorbing / desorbing agent after washing by vacuum drying or the like, the polar solvent or the above-mentioned cleaning solvent contained in the obtained oxygen adsorbing / desorbing agent is removed, and the swollen resin returns to its original state. It is possible to obtain an oxygen adsorbing / desorbing agent in which a complex which contracts and has an oxygen adsorbing ability is dispersed and fixed in an ion exchange resin.

The axial ligands, ion exchange resin resins and complexes containing these functional groups are given as examples and do not limit the scope of the present invention, and various ones can be used depending on the conditions.

(Operation)

When the above-mentioned complex alone is in a solution, 25 ° C.
In the vicinity of room temperature before and after, usually, it does not show oxygen adsorption ability enough to separate oxygen. In addition, a degradation known as the dimerization reaction occurs.

However, in the oxygen adsorbing / desorbing agent of the present invention, since the complex is dispersed and fixed in the ion exchange resin, thermal vibration of the complex is suppressed, and as a result, the complex is put at a low temperature, and the Shows sufficient oxygen adsorption capacity to allow separation. Furthermore, since it is dispersed and fixed, a dimerization reaction is prevented, and deterioration of the complex is eliminated.

The oxygen adsorbing / desorbing agent can easily desorb and release oxygen by heating or reducing the pressure after adsorbing oxygen, and can repeatedly adsorb and desorb oxygen.

〔Example〕

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples.

Comparative Example 1 1,2-diamino-2-methylpropane; (CH ₃ ) ₂ C (NH ₂ ) CH ₂ NH ₂ 4.41 g (0.05 mol) dissolved in 20 ml of ethanol at a temperature of 90
C. in a solution of 4-methoxysalicylaldehyde; 15.22 g (0.05 mol) was added and reacted, bis (4-methoxysalicylaldehyde) dimethylethylenediamine; Was obtained as a yellow solution.

An aqueous solution of 12.45 g (0.05 mol) of cobalt acetate tetrahydrate was added thereto to obtain a dark-lit precipitate. This is allowed to cool, vacuum-dried after suction filtration, and a complex having oxygen adsorbing ability; (N, N'-bis (4-methoxysalicylaldehyde) dimethylethylenediamine) cobalt (hereinafter referred to as Co (4-Me
23 g of OSal) Dmen) were obtained (about 85% yield).

0.3 g of Cc (4-MeOSal) Dmen synthesized in this way was γ-
It was dissolved in 10 ml of butyrolactone to obtain a 0.072M complex solution. Into this complex solution, 2 g (dry weight) of a porous copolymer granular resin having a diameter of about 1 mm obtained by copolymerizing 4-vinyl lysine and styrene by an ordinary method is immersed in an oxygen-free atmosphere, and heated to 90 ° C. to obtain an argon gas. The mixture was refluxed for 4 hours under a gas stream.

After cooling, the complex solution and the resin were separated, and the resin was washed with acetone to remove the physically adsorbed complex.
Vacuum drying for 15 hours in the porous copolymer granular resin
1.7g of oxygen adsorbent with Co (4-MeOSal) Dmen dispersed and fixed
I got

The adsorption amounts of oxygen and nitrogen gas in the obtained oxygen adsorbing / desorbing agent were measured by an electronic balance by a gravimetric method. As a result, the nitrogen gas adsorption amount was so small that it could not be measured, but the oxygen gas adsorption capacity was 1.9 mg / g of granular resin at an oxygen partial pressure of 500 Torr and an adsorption temperature of -20 ° C, as shown in the figure. there were. Note that the porous copolymer granular resin composed of 4-vinylpyridine and styrene has no ability to adsorb oxygen and nitrogen gas.

Comparative Example 2 30 g of 2,3-dimethyl-2,3-dinitrobutane; (CH ₃ ) ₂ C (NO ₂ ) C (CH ₃ ) ₂ NO ₂ was used as a catalyst, using tin (300 g) as a catalyst in a usual manner. Treatment with an aqueous hydrochloric acid solution provided 10.9 g of tetramethylethylenediamine; (CH ₃ ) ₂ C (NH ₂ ) C (CH ₃ ) ₂ NH ₂ (yield 55).
%).

This was mixed with 15.22 g of 4-methoxysalicylaldehyde and 12.4 g of cobalt acetate tetrahydrate in the same manner as in Comparative Example 1.
5 g and a complex having oxygen adsorption capacity (N, N'-bis (4-methoxysalicylaldehyde) tetramethylethylenediamine) cobalt (hereinafter referred to as Co (4-MeOSal) Tm
en) (17.6 g, 80% yield).

0.88 g of Co (4-MeOSal) Tmen synthesized in this way
-Methyl-2-pyrrolidine was dissolved in 5.0 ml to obtain a 0.40 M complex solution.

The same procedure as in Comparative Example 1 was followed to prepare 4-vinylpyridine / styrene porous copolymer particle resin in 1 g (dry weight).
Co (4-MeOSal) Tmen is dispersed and fixed, and oxygen adsorbing and desorbing agent 0.8g
I got

The oxygen gas adsorption / desorption amount of the obtained oxygen adsorption / desorption agent was measured using an electronic balance. In this measurement, the temperature is between -20 ° C and +50
The temperature was changed between ° C and the amount of oxygen absorbed / desorbed based on the temperature change was measured.

As a result, when the oxygen partial pressure was 500 Torr, the amount of adsorbed and desorbed oxygen was 0.8 mg per 1 g of the granular resin.

This temperature fluctuation type oxygen adsorption / desorption test was repeated 200 times, but the oxygen adsorption / desorption amount did not change.

Example 1 First, 1,1'-dodecamethylenediimidazole was prepared by a conventional method; And a toluene solution of 5.38 g (3.75 × 10 ⁻³ mol) of iodomethane in a toluene solution (200 ml) of 22.7 g (7.50 × 10 ⁻³ mol) of 1,1′-dodecamethylenediimidazosol
After 0 ml was added dropwise and reacted overnight at 50 ° C., a white tea solid was separated by filtration and washed with toluene. Then, it was vacuum-dried at 100 ° C. to obtain 15.0 g of 3-methyl-1,1′-dodecyldiimidazolium iodide as an axial ligand (yield: 90).
%).

On the other hand, 10 g of a proton-type cation exchange resin, trade name Amberlyst [15] (manufactured by Tokyo Organic Chemical Industry Co., Ltd.)
Ion exchange was performed with 00 equivalents (176 g) of sodium hydroxide under distilled water to obtain a sodium-type cation exchange resin. Then, 0.5 g of this sodium-type cation exchange resin was added to 2.5
An equivalent amount (3.47 g) of the 3-methyl-1,1'-dodecyldiimidazolium iodide was ion-exchanged under distilled water. From the sodium ion concentration measurement of the filtrate, the ion exchange rate is 48%
Met.

Then, it was synthesized in Comparative Example 2 (Co (4-MeOSal)
1.324 g of Tmen was dissolved in 10 ml of 1-methyl-2-pyrrolidinone to prepare a 0.30 M complex solution. In this complex solution, 0.5 g of the ion exchange resin introduced with the above-mentioned axial ligand was immersed under argon gas, and refluxed at 100 ° C. for 3 days.

Thereafter, Co (4) was added to the ion exchange resin in the same procedure as in Comparative Example 1.
-MeOSal) An oxygen storage / desorption agent having Tmen embedded therein was obtained.

As a result of measuring the oxygen gas adsorption amount in the obtained oxygen adsorbing and desorbing agent, when the oxygen partial pressure was 300 Torr and the adsorption temperature was 25 ° C., 1 g of the resin was
It showed 15.3 mg oxygen adsorption per sample.

Example 2 After drying 20 g of the cation exchange resin used in Example 1, it was put into a mixed solvent of 125 g of phosphorus pentachloride / 250 g of phosphorus oxychloride and reacted under nitrogen at 100 to 110 ° C. for 48 hours to obtain a sulfonyl chloride type. Was converted to a cation exchange resin.

Next, 8- (imidazole-1-yl) octanol was synthesized by a conventional method, and the obtained 8- (imidazole-1-yl) was obtained.
-Yl) octanol (7 g) was dissolved in 1-methyl-2-pyrrolidinone and added dropwise to the above-mentioned sulfonyl chloride-type resin (2.0 g) at 0 ° C under nitrogen, followed by reaction at 80 ° C for 3 hours to give 8- (imidazole-1- Il) Octanol by covalent bond,
It was dispersed and fixed in the resin.

Then, the complex Co (4-MeOSa) synthesized in Comparative Example 2 was used.
l) Tmen was dissolved in 1-methyl-2-pyrrolidinone to prepare a 0.3 M solution of the complex. In the solution, 2 g of an exchange resin in which the ligands were dispersed and fixed were immersed, and refluxed at 100 ° C. for 24 hours in an argon gas atmosphere.

Hereinafter, Co was added to the ion exchange resin in the same procedure as in Comparative Example 1.
An oxygen adsorption / desorption agent having (4-MeOSal) Tmen embedded therein was obtained.

As a result of measuring the amount of oxygen gas adsorbed on the obtained oxygen adsorbent, when the oxygen partial pressure was 300 Torr and the adsorption temperature was 25 ° C, fat
The amount of adsorbed oxygen was 7.62 mg / g.

〔The invention's effect〕

As described above, in the oxygen adsorbing / desorbing agent of the present invention, the complex that resorbs and desorbs oxygen reversibly is fixed by coordination bonding to the axial ligand dispersed and fixed in a large amount in the ion exchange resin. Therefore, a large amount of complex is held in the ion-exchange resin, and since the ion-exchange resin is porous, gas enters and exits the complex portion quickly, so that the oxygen adsorption capacity can be improved. it can. In addition, since each of the complexes is fixed to the axial ligand, the complex is not deteriorated by a dimerization reaction, and excellent oxygen adsorption ability can be maintained for a long time. Furthermore, since it absorbs and desorbs only oxygen, by using it as an adsorbent for PSA or TSA, high-purity oxygen can be obtained in a high yield, and power consumption can be reduced.

[Brief description of the drawings]

The figure shows the oxygen adsorption capacity of the oxygen adsorbing / desorbing agent produced in Comparative Example 1.

Continuation of front page (56) References JP-A-53-123392 (JP, A) JP-A-54-38287 (JP, A) JP-A-55-27028 (JP, A) JP-A-63-93789 (JP) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B01J 20/26

Claims (2)

(57) [Claims] An axial ligand is dispersed and fixed in an ion exchange resin by an ionic bond or a covalent bond, and a complex having an oxygen adsorption ability is fixed to the axial ligand by a coordinate bond. Oxygen adsorbent. 2. The axial ligand according to claim 1, wherein the axial ligand is an axial ligand which, when coordinated with a complex having an oxygen adsorbing ability, increases the oxygen adsorbing ability of the complex. Oxygen adsorbent.