JPH09151195A - Complex solution for separating oxygen and separation of oxygen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject solution by dissolving a specific cobalt Schiff base complex in an organic solvent, capable of making the complex be bonded to oxygen by adsorption of oxygen, precipitating the resultant substance as a solid and separating oxygen from an oxygen-containing gas such as air in high efficiency. SOLUTION: This complex solution for separating oxygen is obtained by dissolving a cobalt Schiff base complex of the formula [R1 is a (substituted) phenylene, a (substituted) pyridylene or a (substituted) alkylene; R2 to R5 are each H, a (substituted) phenyl, a (substituted) alkyl, a halogen or a (substituted) alkoxy; Me is methyl] in an organic solvent (e.g. o-dichlorobenzene) in 0.1-1mol/l concentration of the cobalt Schiff base complex, causes a phase separation due to the binding of the complex to oxygen resulting from adsorption of oxygen to cause precipitation as a solid phase and is capable of separating oxygen from an oxygen-containing gas such as air in high efficiency.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a complex solution for oxygen separation using a cobalt Schiff base complex and an oxygen separation method, and more particularly to a complex for oxygen separation capable of separating oxygen from an oxygen-containing gas such as air with high efficiency. The present invention relates to an oxygen separation method capable of separating oxygen from an oxygen-containing gas such as air with high efficiency by a temperature fluctuation method using a solution and the complex solution for oxygen separation.

[0002]

2. Description of the Related Art Conventionally, as a method for separating and producing oxygen in air on an industrial scale, air is pressurized, cooled, expanded, liquefied, and subjected to multi-stage rectification processes. There is a cryogenic separation method that separates However, this method requires a large amount of energy input. It is suitable for mass production of high-purity oxygen or nitrogen, but is not suitable for small-quantity production. In recent years, using adsorbents such as zeolite or carbon molecular sieves,
There is an adsorption separation method for separating and producing oxygen or nitrogen by selectively adsorbing nitrogen or oxygen on the adsorbent. This method has the advantages of a simple operation and a short start-up time, and is suitable for producing a relatively small volume of oxygen or nitrogen. However, this adsorption separation method is not suitable for large-volume production. Further, there is a disadvantage that the apparatus becomes large as compared with the production amount of the product. Particularly when producing oxygen, there is a disadvantage that the maximum oxygen concentration is only 95%.

In order to overcome these drawbacks, recently, several methods have been proposed for separating oxygen using a complex that reacts reversibly only with oxygen. This method is carried out, for example, by contacting the complex solution with air at a low temperature of 5 ° C. or lower, as described in JP-A-58-20296.
Oxygen in the air is absorbed by the complex solution, then oxygen is released from the complex solution at a high temperature of 25 ° C or higher, and this is collected as product oxygen. The complex solution is cooled again to a low temperature of 5 ° C or lower. Absorb oxygen. Hereinafter, oxygen can be continuously collected by repeating the same process (temperature fluctuation type chemical absorption method). Another method of the oxygen separation method is that the complex solution is kept at a constant temperature under a high oxygen partial pressure by changing the oxygen bonding ratio to the complex according to the magnitude of the oxygen partial pressure in the gas phase. There is a pressure fluctuation type chemical absorption method in which oxygen is absorbed and the oxygen absorbed under a low oxygen partial pressure is desorbed to separate and collect oxygen. In any case, in this type of method, the complex solution is always treated as a uniform liquid.

[0004]

However, the complex solutions used in these chemical absorption methods have the following disadvantages. The conventional complex solution has poor oxygen adsorption / desorption conditions, and is cooled to 5 ° C. or less during oxygen adsorption and 60 ° C. during oxygen desorption.
It must be heated as described above, and a great deal of heating and
Cooling energy is required. Also, the conventional complex solution is
Since the complex has a low oxygen absorption ability, the utilization efficiency of the complex is low. When the complex solution absorbs oxygen from atmospheric pressure air even when cooled to 0 ° C., the oxygen bond ratio to the complex is only 20 to 40%. Did not. Further, when the composition of the complex solution is determined,
The oxygen absorption temperature and the oxygen release temperature were determined at the same time, and these temperatures could not be changed. For this reason, it was not possible to sufficiently utilize environmental heat and exhaust heat.

[0005] Further, the conventional complex solution has a problem in that the steric hindrance of the complex is insufficient, so that the complex is dimerized as oxygen is repeatedly absorbed and desorbed, and the oxygen absorbing ability is reduced. Was. Further, the solvent of the complex solution has a large polarity, for example, 1-methyl to increase the oxygen absorption rate.
-2-pyrrolidinone (dipole moment 4.09 Debye)
And many of them were hydrophilic. Therefore, the oxygen separation device required equipment for removing moisture in the raw material gas. Incidentally, the unit Debye of the dipole moment is 3.34 × 10 ⁻³⁰ C−.
m (MKS). In addition, the conventional complex solution has a low saturation solubility of the complex, so a large amount of solvent is required to obtain a practical amount of generated oxygen, and a large amount of the complex solution must be circulated and used. It will lead to conversion.

The present invention has been made in view of the above circumstances, and provides a complex solution for oxygen separation capable of separating oxygen from an oxygen-containing gas such as air with high efficiency, and a temperature fluctuation method using the complex solution for oxygen separation. It is an object of the present invention to provide an oxygen separation method capable of separating oxygen from an oxygen-containing gas such as air with high efficiency.

[0007]

The invention according to claim 1 is
Formula (A)

[0008]

Embedded image

(Wherein R 1 is one selected from the group consisting of a substituted or unsubstituted phenylene group, a substituted or unsubstituted pyridylene group, a substituted or unsubstituted alkylene group,
R2 to R6 are one selected from the group consisting of hydrogen, a substituted or unsubstituted phenyl group, a substituted or unsubstituted alkyl group, a halogen, and a substituted or unsubstituted alkoxy group;
e represents a methyl group), and a cobalt Schiff base complex represented by the formula: is dissolved in an organic solvent, and the complex is bonded to oxygen by adsorption of oxygen to cause phase separation in which a solid phase is deposited to form a complex for oxygen separation. It is a solution. The invention according to claim 2 is the complex solution for oxygen separation according to claim 1, wherein the organic solvent is a hydrophobic solvent. The invention according to claim 3 is characterized in that the concentration of the cobalt Schiff base complex is 0.1 to 1 mol / l.
Is a complex solution for separating oxygen. The invention according to claim 4 is
Contacting the mixed solution containing oxygen or oxygen with the complex solution for oxygen separation according to any one of claims 1 to 3,
It is an oxygen separation method comprising an oxygen adsorption step of depositing the complex bound to oxygen as a solid phase and an oxygen desorption step of heating the deposited oxygen-bonded complex to desorb oxygen. In the invention according to claim 5, the oxygen adsorption step is performed at -10 to 50C.
5. The oxygen separation method according to claim 4, wherein the oxygen desorption step is performed in a temperature range of 10 to 80 ° C. 6.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The complex used in the complex solution for separating oxygen of the present invention has a structure represented by the above formula (A). This complex has a higher solubility in common organic solvents than conventional complexes. In addition, this complex has high stability due to the introduction of a large substituent that becomes a steric hindrance.

The complex solution for oxygen separation of the present invention is obtained by dissolving the complex (A) in an organic solvent. When this cobalt Schiff base complex binds to oxygen, it forms a solid phase and precipitates in a solution, and when it is heated to desorb oxygen, a phase separation phenomenon occurs in which it becomes a liquid phase. That is, when air or an oxygen-containing gas is brought into contact with a complex solution comprising a cobalt Schiff base complex, a specific axial ligand, and a solvent, and the complex solution absorbs oxygen, the oxygen-bonded complex to which oxygen is bound becomes solid. As a phase, it precipitates out of the solution and solidifies and precipitates, and this is converted into a liquid phase by heating to remove absorbed oxygen, thereby obtaining oxygen and regenerating the complex solution.

When the phase separation phenomenon is utilized in the oxygen separation, for example, when oxygen is absorbed from the air at atmospheric pressure at a temperature of 20 ° C., 90% or more of the complex is bound with oxygen to be solidified. When the solid phase body is heated to a temperature of 40 to 50 ° C., most of the absorbed oxygen is released to become a liquid phase. As a result, the energy for cooling the complex solution can be reduced, and the utilization efficiency of the complex can be improved. Furthermore, when a mixed solvent of a good solvent that easily causes a phase separation phenomenon and a poor solvent that hardly causes a phase separation phenomenon is used as a solvent for the complex solution, the phase separation elimination temperature can be changed by changing their composition, so that environmental heat or waste heat Can be used, and the energy efficiency of oxygen separation can be significantly improved. Further, the oxygen-bonded complex solidified and precipitated by the phase separation has lower reactivity than the oxygen-bonded complex dissolved in the solution, and the reaction rate of dimerization becomes negligibly slow.
As a result, the complex solution can be used repeatedly over a long period of time. The fact that the oxygen-bonded complex solidifies and precipitates due to the phase separation phenomenon means that it is excluded from the reaction system of the oxygen bond, and the unbonded complex in the complex solution also undergoes phase separation by the oxygen bond. Be excluded outside. Therefore, if there is a solid-state oxygen-unbound complex exceeding the solubility of the oxygen-unbound complex, the oxygen-unbound complex can be sequentially dissolved in the solution to react with oxygen. Therefore, it is possible to use the complex at a concentration equal to or higher than the solubility in the reaction, and it is possible to increase the oxygen transport amount to a desired amount.
Further, the conditions concerning the solubility of the solvent are relaxed, so that a hydrophobic solvent can be employed.

As the organic solvent used in the complex solution for separating oxygen of the present invention, various solvents including a hydrophobic solvent and a hydrophilic solvent can be used. By using a hydrophobic solvent among these organic solvents, the operation of removing water contained in a raw material mixed gas such as raw material air can be omitted. Therefore, as the organic solvent used in the complex solution for oxygen separation of the present invention, an organic solvent having high hydrophobicity is preferable. Such an organic solvent may be appropriately selected from chain hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, and hydrophobic hydrocarbon compounds containing O, N and S. For example, C ₅ to hexane, cyclohexane, etc.
Saturated hydrocarbon compound C _12, 1,2-dichlorobenzene, 1,2-dibromobenzene, 3,4-dichlorotoluene, 2,4-dichlorotoluene, 2,3-dichlorotoluene, 2,6-dichlorotoluene, 2-chloroparaxylene, 4-chloroparaxylene, 1-chloronaphthalene, 1,2,3,4-tetrahydronaphthalene, 1-methylnaphthalene, 2-ethylnaphthalene, 1,2,3-
Trimethylbenzene, 1,2,3,5-tetramethylbenzene, 1,4-diisopropylbenzene, tertiary amylbenzene, normal amylbenzene, phenylcyclohexane, 4-tertiarybutyltoluene, methylbenzoate, normal propylbenzoate, Thioanisole, indane and the like.

In the complex solution for oxygen separation of the present invention, the concentration of the complex (A) is in the range of 0.1 to 1 mol / l, the viscosity (fluidity) of the complex solution, In consideration of the contact property of the complex solution and the transport property of the complex solution, the content is preferably 0.1 to 0.3 mol / l.

The complex solution for oxygen separation according to the present invention comprises a cobalt Schiff base complex represented by the above formula (A) and a solvent, and an oxygen-bonded complex bonded to oxygen at the time of oxygen absorption precipitates as a solid phase. It is such that phase separation occurs.

A cobalt Schiff base complex containing an axial ligand is active toward oxygen, and is expressed by the following formula (1).
₂ ) reacts with.

[0017]

(Equation 1)

In the formula, L · Co represents a cobalt Schiff base complex containing an axial ligand. (S) shown in the alphabet represents a solid state, (l) represents a liquid state, and (g) represents a gas state. When a highly polar solvent is used, oxygen binding is carried out in the complex solution while maintaining a liquid phase without causing a phase change.

It is considered that the phase separation occurs by the following mechanism. It is known that the charge density on cobalt moves toward oxygen molecules when oxygen is bound in the cobalt Schiff base complex. As a result, a dipole moment is generated, and the polarity of the Co—O ₂ bond increases. Such a change in polarity of the complex due to the oxygen bond greatly affects the solubility of the complex in a solvent. When the polarity of the solvent of the complex solution is small, the solubility of the complex bound to oxygen is lower than that of the complex not bound to oxygen because the polarity of the complex to which oxygen is bound is large.

The amount of oxygen-bound complex formed when the complex solution absorbs oxygen is determined by the oxygen affinity and oxygen partial pressure of the complex. In this case, the amount of the oxygen-bonded complex formed is large, the solubility of the generated oxygen-bonded complex in the solvent is sufficiently small, and the solvent of the oxygen-bonded complex generated from the amount of the oxygen-bonded complex generated by the complex solution absorbing oxygen is generated. It is considered that when the solubility in is small, the oxygen-bonded complex formed cannot exist in the state of being dissolved in the solvent, but solidifies and precipitates as shown in the following formula (2).

[0021]

(Equation 2)

Here, l and g indicate a liquid phase and a gas phase as described above, and s indicates a solid phase.

When such a phase separation phenomenon occurs, the oxygen-bonded complex no longer dissolves in the solution but precipitates, so that the reaction of the above formula (2) shifts the equilibrium in the direction of solidification and precipitation. As a result, in order to compensate for the concentration of the oxygen-bound complex in the solution that has been reduced by the solidification precipitation, the reaction proceeds in a direction in which the oxygen and the uncoordinated oxygen complex combine with oxygen to form the oxygen-bound complex. When the oxygen-bonded complex is formed in the solution, solidification and precipitation occur again, and oxygen and the uncoordinated oxygen complex are consumed. In the solution, almost 100% of the phase-separated solution is occupied by the oxygen-bonded complex. Is believed to be.

On the other hand, when the temperature of the phase separation solution is increased,
Since the solubility of the oxygen-bound complex in the solvent increases, the oxygen-bound complex starts to dissolve in the solution. When the solution temperature rises sufficiently, the solidified precipitate completely disappears from the solution. At that time, contrary to the above description, when the temperature is increased, the dissolved amount of the oxygen-bonded complex decreases, and the equilibrium shifts in the direction of releasing oxygen.
As a result, oxygen is generated together with the elimination of phase separation, and an oxygen complex in which oxygen is not coordinated can be obtained again in the solution.

The temperature of the complex solution when the solubility of the oxygen-bonded complex in the solvent and the equilibrium production concentration of the oxygen-bonded complex in the solution are the same is defined as the phase separation temperature. When the phase separation occurs at a temperature lower than the phase separation temperature, the solution described above can absorb a large amount of oxygen because the solution is occupied by almost 100% of the oxygen-bonded complex. Next, when the temperature of the complex solution exceeds the phase separation temperature, the phase separation is eliminated and a homogeneous solution is obtained. For that purpose, it is necessary that the concentration of the oxygen-bonded complex in the complex solution returns to the solubility in the homogeneous solution. This is because the equilibrium shifts in the direction in which the solidified oxygen-bonded complex dissolves, and then oxygen is released from the dissolved oxygen-bonded complex, causing a reaction to return to oxygen and the uncoordinated oxygen complex. To solve. Therefore, oxygen is released from the solution at once. Thus, oxygen separation can be performed with a small temperature difference near the phase separation temperature. Further, in a complex solution in which phase separation occurs, an unbound oxygen-bound complex in an excess solid phase more than the solubility can be sequentially dissolved in a solvent and reacted with oxygen. This is due to the complex Co dissolved in the solvent.
When (l) is consumed by reacting with oxygen, the oxygen-unbound complex Co (s) in the solution dissolves to form an oxygen-unbound complex dissolved in the solvent and reacts with oxygen O ₂ , which is chemically converted. When represented by a reaction formula, the following formula (3) is obtained. This is because this is repeated. Then, since this is repeated, the excess oxygen-unbound complex in the solid phase state can be sequentially dissolved in the solvent and reacted with oxygen.

[0026]

(Equation 3)

Therefore, in a complex solution in which phase separation occurs, the reaction of the above formula (3) occurs, and thus a complex having solubility or higher can be added to make an oxygen absorbing solution. Therefore, the amount of oxygen transported from the absorption tower to the stripping tower can be increased to a desired amount. Further, the conditions of the solvent regarding the solubility are relaxed, so that a hydrophobic solvent can be employed.

According to the present invention, oxygen is efficiently separated and collected by utilizing the above-described phase separation. In order to satisfy the conditions for phase separation, the solubility of the oxygen-bonded complex is low and the true oxygen affinity is low. It is necessary to select a combination of the complex, the axial ligand, and the solvent that increases the size. The cobalt Schiff base complex according to the present invention is a salicylaldehyde-based Schiff base complex in which the central metal represented by the formula (A) is cobalt.

There are two types of oxygen-bonded complexes: a monomer in which one molecule of oxygen is bonded to one molecule of the complex, and a dimer in which one molecule of oxygen is bonded to two molecules of the complex. Monomers can reversibly bind or release oxygen, while dimers cannot reversibly bind or release oxygen. Therefore, in order to prevent dimerization of the complex, a steric hindrance group may be added to the Schiff base so that the complexes cannot approach each other. In the cobalt Schiff base complex according to the present invention, it is effective that R5, R6, R7 and R8 are methyl groups. Hereinafter, tetramethylethylenediamine in which four methyl groups are added to the diamine portion is referred to as Tmen.

In the oxygen separation method according to the present invention, an oxygen or oxygen-containing mixed gas is brought into contact with the above-described complex solution for oxygen separation to bond oxygen to the cobalt Schiff base complex in the complex solution for oxygen separation. The method includes an adsorption step and an oxygen desorption step of heating a complex solution for oxygen separation containing an oxygen-bonded complex to desorb oxygen. The oxygen adsorption step is -10 to
It is performed in a temperature range of 50 ° C., and the oxygen desorption step is 10 to 8
It is preferable to carry out in a temperature range of 0 ° C. In this temperature range, oxygen adsorption / desorption of the complex solution for oxygen separation can be performed efficiently, and dimerization of the complex does not progress, and stable operation can be performed for a long period of time.

By using the above-described complex solution for oxygen separation and performing oxygen separation by a temperature fluctuation method, the heating and cooling energy required for adsorbing and desorbing oxygen is required as compared with the conventional oxygen separation using the complex solution for oxygen separation. And oxygen can be produced at low cost.

In the oxygen separation method, the pressure in the oxygen adsorption step and the oxygen desorption step is not particularly limited, but is usually carried out at a pressure of 100 Torr or more, preferably about atmospheric pressure.

In the above-described oxygen separation method according to the present invention, a source gas containing oxygen such as air is supplied to an adsorption / desorption tank containing a complex solution for oxygen separation, oxygen is adsorbed on the complex solution for oxygen separation, and then the complex is separated. Batch type (batch type) for heating the solution to desorb oxygen and recover oxygen, or circulating a complex solution for oxygen separation in the adsorption tank and desorption tank, and raw material containing oxygen such as air in the adsorption tank The gas may be supplied, oxygen may be adsorbed on the oxygen separation complex solution, the complex solution may be heated in a desorption tank to desorb oxygen, and oxygen may be recovered using any continuous oxygen separation device. .

[0034]

The present invention will be described below in detail with reference to examples. (Complex used) The cobalt Schiff base complex (A) used in this example is obtained by reacting a diol compound with 2-chloromethyl-3-chloro-propene to obtain a dichloro derivative, and then obtaining a hydroxyl group at the 2-position and a 3-position at the 2-position. Is reacted with a salicylaldehyde derivative having a hydrogen atom in the presence of a base to thermally decompose an ether compound to obtain a bissalicylaldehyde derivative, followed by Tmen (2,3-diamino-
2,3-Dimethylbutane) was synthesized by performing a complex formation reaction with cobalt. The synthesized complex according to the present invention is represented by the above formula (A), and as shown in Table 1, R1 is a paraphenylene group, R2,
R3 and R5 are hydrogen, and R4 and R6 are methoxy groups.
Is a complex of Note that the following embodiments are merely examples of the present invention, and the present invention is not limited to the following embodiments.

[0035]

[Table 1]

Example 1 Confirmation of Phase Separation of Complex Solution A complex solution having a predetermined concentration of 15 m was prepared from the complex 1 and the solvent.
1 was prepared in a vial container. Put this in a thermostat,
Oxygen was introduced into the gas phase of the vial vessel from a low pressure to a gradually increasing pressure, and oxygen was absorbed in the complex solution. The complex that absorbed and bound oxygen was solidified and precipitated in the solution, and the time at which the oxygen-bound complex precipitated was defined as the phase separation start time.
Specifically, a predetermined amount of the complex is placed in a vial container at room temperature, a predetermined amount of a solvent is added, and the complex is fixed so as to be immersed in a thermostat. The temperature of the thermostat may be room temperature or adsorption temperature. Next, the gaseous phase portion of the vial container is evacuated by a vacuum pump, and stirred after a bubble is no longer generated from the solution to obtain a uniform solution. The gas phase in the vial container may be purged with nitrogen, a rare gas, or the like, or may be combined with vacuum exhaust and purge, instead of being evacuated with a vacuum pump. Thereby, oxygen in the complex solution is removed. In order to more completely remove oxygen from the homogeneous solution, the solution is cooled, solidified and evacuated, or evacuated while stirring the solution.

After the oxygen in the solution was completely removed, the temperature of the thermostat was set to a predetermined absorption temperature, oxygen was absorbed, and phase separation was performed. When phase separation occurs, the solution precipitates and becomes a suspended solution, and the color of the solution becomes darker as it is suspended. The presence or absence of phase separation was confirmed by the pressure condition. Table 2 shows the results. In Table 2, o-D was used as the solvent.
CB, 2-Etnp, and Indane are o-dichlorobenzene, 2-ethylnaphthalene, and indane, respectively. Among the above solvents, o-dichlorobenzene is a polar solvent, and 2-ethylnaphthalene and indane are nonpolar solvents. Further, when the temperature was lowered after the experiment and reached room temperature, the solution returned to a homogeneous solution. Thus, it was confirmed that the phase separation was also affected by the temperature.

[0038]

[Table 2]

As is apparent from Table 2, each of the complex solutions prepared using the above-mentioned complex 1 shows a phase separation in which the complex bonded to oxygen is precipitated as a solid phase by absorbing oxygen. . In addition, since this phase separation is in a range suitable for actual oxygen separation conditions (absorption temperature and pressure), when performing an oxygen separation operation using these complex solutions, phase separation of the oxygen-bonded complex occurs. Thus, it is understood that it is possible to increase the oxygen adsorption / desorption amount.

Example 2 Measurement of Oxygen Affinity The temperature in the constant temperature bath was maintained at a temperature at which the complex phase-separated, and oxygen was introduced into the vial container to cause phase separation. The amount of oxygen absorbed at that time was determined and defined as the amount of oxygen absorbed (mol).
The value obtained by dividing the oxygen absorption amount by the amount (mol) of all the complexes used in the preparation of the complex solution, that is, the total amount of cobalt ions was determined. In Example 2, two of the complexes described in the specification of Japanese Patent Application Laid-Open No. 7-165776 filed by the present applicant were referred to as Comparative Examples 1 and 2, and were compared with the complex 1 according to the present invention. did.

Co4,6DMeOsalTmen of Comparative Example 1 was N, N '
-Bis (4,6-dimethoxysalicylidene) 1,1,2,2-
Tetramethylethylene diaminocobalt (II).
Co4,6DtBusalTmen of Comparative Example 2 was N, N'-bis (4,6
-Ditert-butylsalicylidene) 1,1,2,2-tetramethylethylenediaminocobalt (II).

In Table 3, NMP of the solvent is N-
Methylpyrrolidone and o-DCB represent o-dichlorobenzene. In addition, MeIm of the axial ligand represents methylimidazole, and DMAP represents 4-dimethylaminopyridine, and the concentration of the axial ligand was 1.5 equivalent.

[0043]

[Table 3]

As a result of absorbing oxygen into each of the complex solutions shown in Table 3, the solution of Complex 1 according to the present invention showed phase separation.
The complex solutions of Comparative Examples 1 and 2 were homogeneous solutions showing no phase separation even after oxygen absorption. As is clear from Table 3, the value of the amount of oxygen absorbed / the total amount of Co in the solution of the complex 1 according to the present invention is larger than that of the complex solutions of Comparative Examples 1 and 2, which are homogeneous solutions. It can be seen that the solution of complex 1 has an increased oxygen affinity due to phase separation. In addition, it was confirmed that a solution of the complex 1 according to the present invention can use a hydrophobic solvent.

Example 3 Confirmation of Reversibility of Oxygen Adsorption and Desorption of Complex Solution After reaching the state in which phase separation occurred in Example 2, the temperature of the thermostat was set to 40 ° C., Was desorbed. At this time, the amount of desorbed oxygen was measured and defined as the amount of desorbed oxygen. About the solution of the complex 1 according to the present invention,
Table 4 summarizes the oxygen absorption amount obtained in Example 2, the oxygen desorption amount obtained as described above, and the oxygen desorption amount / oxygen absorption amount.

[0046]

[Table 4]

As shown in Table 4, since the ratio of the amount of oxygen desorbed to the amount of oxygen absorbed is almost 1 in the solution of complex 1 according to the present invention, these complex solutions may have reversibility of oxygen absorption and desorption. Recognize.

[Example 4] Comparison of safety of used solvents Table 5 shows toxicity data of various solvents.

[0049]

[Table 5]

Among the various solvents shown in Table 5, n-hexane and cyclohexane are particularly low-toxic, and the complex 1 according to the present invention can be used by dissolving in these low-toxic solvents. The complex solution obtained by dissolving the complex 1 according to the present invention in these solvents can improve the safety during handling.

Table 6 shows the toxicity values of the axial ligands suitably used in the complexes of Comparative Examples 1 and 2.

[0052]

[Table 6]

The conventional complex required an axial ligand having a small LD50 value as shown in Table 6 when preparing a complex solution for oxygen separation, but the complex according to the present invention requires such an axial ligand. Since the use of the ligand can be omitted, the complex solution according to the present invention can improve the handling safety.

[0054]

As described above, since the complex solution for oxygen separation according to the present invention contains the cobalt Schiff base complex represented by the formula (A), it has excellent oxygen adsorption / desorption performance and solubility in a solvent. And high stability. In addition, the complex solution for oxygen separation according to the present invention can use a safe and inexpensive hydrophobic solvent and does not require the addition of a shaft ligand, so that it is easy to handle, and the water content in the raw material gas is reduced. No pre-treatment equipment is required to remove the water. Further, since the cobalt Schiff base complex according to the present invention binds to oxygen and precipitates as a solid phase, dimerization due to steric hindrance and phase separation of the complex can be prevented, and the amount of generated oxygen can be increased.

Furthermore, the complex solution for oxygen separation according to the present invention can perform oxygen separation by reducing the temperature difference at the time of oxygen desorption, so that the heat energy required for cooling and heating at the time of oxygen absorption and desorption can be reduced. Can be. Further, the oxygen separation method according to the present invention uses the above-described complex solution for oxygen separation,
By separating oxygen from an oxygen-containing gas such as air by a temperature fluctuation method, oxygen can be separated with high efficiency.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (74) One of the above agents, Attorney Masatake Shiga (2 outside) (72) Inventor Kazuhisa Hiratani 1-1, Higashi, Tsukuba-shi, Ibaraki Institute of Industrial Science and Technology ( 72) Inventor Toshikazu Takahashi, 1-1, Higashi, Tsukuba-shi, Ibaraki Institute of Industrial Science and Technology (72) Inventor, Kazuyuki Kasuga, 1-1, Higashi, 1-1, Tsukuba-shi, Ibaraki Institute of Industrial Technology (72) ) Inventor Riichi Nakatsuji 1-16-7 Nishi-Shimbashi, Minato-ku, Tokyo, Japan Oxygen Co., Ltd. (72) Inventor Ichiro Nakayama 1-16-7 Nishi-Shimbashi, Minato-ku, Tokyo, Japan 72) Inventor Ayumu Okamoto 1-16-7 Nishishinbashi, Minato-ku, Tokyo Within Nihon Oxygen Co., Ltd. (72) Inventor Nobuyoshi Ito 1-16-7 Nishishinbashi, Minato-ku, Tokyo In Japan Oxygen Co., Ltd. (72) Inventor Taizo Ichida 2-4-11 Tsutohoncho, Nishi-ku, Osaka City, Osaka Prefecture In Taiyo Toyo Oxygen Co., Ltd. (72) Inventor Makoto Uchino 2-chome, Nishiku-ku, Osaka City, Osaka Prefecture 4-11 No. 11 Taiyo Toyo Oxygen Co., Ltd. (72) Inventor Takayoshi Adachi 2-4-11 Tsutohoncho, Nishi-ku, Osaka City Osaka Prefecture

Claims (5)

[Claims] 1. A compound of the formula (A) (Wherein R 1 is one selected from the group consisting of a substituted or unsubstituted phenylene group, a substituted or unsubstituted pyridylene group, a substituted or unsubstituted alkylene group, and R 2 to R 6 are
Which is one selected from the group consisting of hydrogen, substituted or unsubstituted phenyl group, substituted or unsubstituted alkyl group, halogen, substituted or unsubstituted alkoxy group, and Me represents a methyl group. Is dissolved in an organic solvent, and the complex is combined with oxygen by adsorption of oxygen to cause phase separation to precipitate as a solid phase. 2. The complex solution for oxygen separation according to claim 1, wherein the organic solvent is a hydrophobic solvent. 3. The concentration of the cobalt Schiff base complex is 0.1 to 1 mol / l.
Or the complex solution for oxygen separation according to 2. 4. An oxygen in which air or a mixed gas containing oxygen is brought into contact with the complex solution for oxygen separation according to any one of claims 1 to 3 to precipitate the complex bound with oxygen as a solid phase. An oxygen separation method comprising an adsorption step and an oxygen desorption step of heating a deposited oxygen-bonded complex to desorb oxygen. 5. The oxygen separation method according to claim 4, wherein the oxygen adsorption step is performed in a temperature range of −10 to 50 ° C., and the oxygen desorption step is performed in a temperature range of 10 to 80 ° C.