JPS62241551A - Selective separating agent for carbon dioxide - Google Patents

Abstract

PURPOSE:To perform a reversible reaction with carbon dioxide in a dry state by preparing a selective separating agent for carbon dioxide wherein a copper (II) salt complex shown in the specified general formula is made to a high molecular constitutional unit. CONSTITUTION:A low molecular ligand soln. is mixed with a copper (II) salt soln. in 1 to 1 (molar ratio) and a high molecular ligand soln. is dropt. Then a potassium hydroxide soln. is added in two times mol for copper (II) and thereby a copper (II) complex shown in a general formula is obtained (at least one of R1, R2 and R3 shows hydroxyalkyl group and the other shows hydrogen atom and hydrocarbon group and R4, R5 and R6 show alkylene group and R7 shows a high molecular structural unit and also R1 and R6 may form a heterocyclic ring contg. nitrogen atom). This copper (II) complex is used as a selective separating agent for carbon dioxide.

Description

[Detailed description of the invention] Noichi who caught 1L in production The present invention relates to a carbon dioxide selective separation agent.

Conventional techniques and problems that 111 attempts to solve Conventional carbon dioxide separation and recovery methods include chemical absorption methods,
There are physical adsorption methods and membrane separation methods.

Carbon dioxide absorbents used industrially in chemical absorption methods include those that utilize aqueous solutions of ethanolamines and aqueous solutions of alkali metal carbonates. All of these absorb carbon dioxide at low temperatures, release the carbon dioxide by heating, and recover the original absorbent [Kirk Othmer, Encyclopedia of Chemical Technology].

3rd edition, Wiley Interscience (KIRK-O
TIIMER, Encyclopedia of Che
mical Technology.

3rdEd,,υ1ley-Interscance
) 197g, pp732-735).

This method requires a large amount of energy for heating and cooling when regenerating the absorbent by heating or recovering the amine by partial distillation.

In the physical adsorption method, zeolite is used as an adsorbent, and carbon dioxide is adsorbed onto the zeolite at high pressure, and then desorbed at low pressure (PSA).
There is a method by which carbon dioxide is recovered. This PSA method works effectively for relatively high-pressure carbon dioxide, but for low-concentration carbon dioxide, the adsorption capacity is extremely low, resulting in a high concentration of carbon dioxide remaining in the gas being processed. Become.

In addition, as a membrane separation method, carbon dioxide is separated from lower hydrocarbons using a prism separator (trademark) using polysulfone hollow fibers manufactured by Monsanto Corporation in the United States [Chemical Engineering Progress].

October issue-, p27 (1982), CEP, Oct.

p27 (1982)) and separation of carbon dioxide using asymmetric cellulose acetate-1~ membranes manufactured by Separex Corporation in the United States [
Hydrocarbon Processing, September issue, (Hydr
ocarbon Processing, 5ept,
), p249 (1982)). These membranes are
Focusing on the high membrane permeability to carbon dioxide that these polymeric materials inherently possess, we attempted to improve the permeation rate by making them thinner and put them into practical use. The separation coefficient of carbon dioxide with respect to methane gas of these membranes is on the order of several tens, and is 25 in the case of the Separex membrane system (trademark of Separex Corporation).

Polymer materials generally have a higher permeability coefficient for carbon dioxide than other gases, and practical membranes can be obtained even if these materials are used as they are. There has been little development of high-quality materials.

Under these circumstances, carbon dioxide separation methods have been studied that utilize the fact that carbon dioxide forms an equilibrium relationship with bicarbonate ions and carbonate ions in the presence of water.

For example, a membrane (liquid membrane) in which a porous cellulose acetate membrane was impregnated with an aqueous cesium bicarbonate solution was used. There are studies on the separation of carbon dioxide from oxygen [Recent Advances in Separation Science, Volume 1 (Ward, RecentDevelopo).
pment in 5eparation 5cien
ce, vol, I) p 157 (1972)). Here, the permeability coefficient of carbon dioxide is 75 x 10-'am
'(STP)・cm/cm2・5ee2・cml(g(
25℃), and the permeability coefficient ratio for oxygen is 150.
It was 0. Furthermore, by adding sodium arsenate, the permeability coefficient of carbon dioxide is 214X10-'am3 (STP).
cm/am machine 5ec2+cmHg, the permeability coefficient ratio for oxygen reached 4,100.

There is also a study in which inorganic salts were dissolved in polyethylene glycol with a molecular weight of about 300, and the permeation of carbon dioxide against oxygen and nitrogen was investigated [Kawakami et al., Journal of the Chemical Society of Japan, No. 6.
p847 (1983)).

Here, the permeability coefficient of carbon dioxide before and after addition of inorganic salt is
51 X 10-"0m3(STP) ・cm/am"
・5ec2・cmHg to 310 x 10-”0m
3 (STP) ・cm/cm2・sec" ・cmHg
It has been reported that the permeability coefficient ratio to nitrogen has improved to about 19 or 6110. In addition, a membrane (110 μm) made of a strong cation exchange resin made of polytetrafluoroethylene grafted with sulfonated polystyrene and impregnated with an aqueous ethylenediamine solution has a permeability coefficient ratio of approximately 600 for carbon dioxide to nitrogen [Journal of the Japan Society of Materials Science (Journal of Materials Science, Japan]
Le Blanc Jr., William J., Wa.
rd et al, Journal of M
embrana 5science), Volume 6, 339
(1980)].

In the case of the aforementioned cesium bicarbonate aqueous solution and ion exchange membrane, carbon dioxide saturated with water is used as the supply gas because they only work in the presence of water, and cannot work in a dry state.

In addition, liquid membrane systems in which a porous membrane is impregnated with liquid have a problem in retaining the separation material, and when used at high pressure, the liquid may flow out and the separation ability may be lost.

On the other hand, in the copper(II)-alkanolamine complex, bis(2-aminoethanolado)copper(II) and bis(2-pyridyl-methanolado)copper(II) react reversibly with carbon dioxide in an ethanol solution. It is known that [I
Iarukichi Hashimoto at al.
, Tohoku University Technology Report
s, Tohoku Univ+) 48. No.1
゜1 (1983)), but these complexes contain f in addition to the nitrogen atom and hydroxyl group that form the chelate ε1↑
It is a complex that does not have a hydroxyl group of i'Mt, and it only undergoes a reversible reaction with carbon dioxide in a polar solvent such as ethanol or dimethylformamide, but as shown below,
It is not stable in the nonpolar solvents chloroform and orthodichlorobenzene, has limited solubility, and is not reversible. Furthermore, it has not been possible to carry out a reversible reaction with carbon dioxide in a dry state.

Means for Solving the Problems As a result of repeated research aimed at creating a polymer complex capable of reversibly reacting with carbon dioxide in a dry state, the present inventor discovered that copper(II)-alkanolamine The present invention was achieved by discovering that a novel polymer complex having a complex in its side chain can achieve the above object.

That is, the present invention relates to the general formula (I) -(RJ- K3 (wherein, at least one of R1, R2 and R1 represents a hydroxyalkyl group, the others represent a hydrogen atom or a hydrocarbon residue, and R4, R5 and RG represents an alkylene group,
R7 represents a polymer structural unit. Also R1. R, can form a heterocycle containing a nitrogen atom, in which case R4 represents an alkylene group bonded to the heterocycle, and R1
, R4 and RG may form a ship base together with the nitrogen atom. ] It is related with the carbon dioxide selective separation agent containing the copper (II) complex represented by these.

In the polymer complex of the present invention, the hydroxyalkyl group from R to R3 is -(CH,)n-OH (II is 2 to 6
), and the hydroxyalkyl group includes 2-hydroxyethyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 4-hydroxybutyl group, 5-hydroxypentyl group, 6-hydroxypropyl group, Hydroxyhexyl group, etc., and 2-(2-hydroxyethoxy)ethyl group can also be included in this category.

Other hydrocarbon residues include alkyl groups, aryl groups, etc., and the alkyl groups include those having 1 to 3 carbon atoms,
Examples of the aryl group include a methyl group, an ethyl group, a propyl group, and examples of the aryl group include a benzyl group, a 4-vinylbenzyl group, a phenyl group, and a 2-hydroxy-3-(4-vinylphenoxy)propyl group. It will be done.

The alkylene groups of R4 and R6 have 2 to 3 carbon atoms, such as ethylene group, 1,2-propylene group, etc., and RG is -
(CR2) is represented by m - (m is an integer of 1 to 6), and is, for example, methylene, ethylene, trimethylene, hexamethylene, etc. Further, R5 may be polyoxyethylene.

In addition, R7 (polymer structural unit) in the formula is:

Any material may be used as long as it forms a membrane or film-formable polymer. For example -+(CR2)
P CHO, ((CR2)P q HO3-.

R R (where p and r are integers of 1 or more, R represents a self-substituent group)
etc., and there are structural units shown below.

-4CH, CHO+, -+C:H2CH).

In addition, the above-mentioned structural units may contain structural units exemplified below in the form of copolymerization,
It is not particularly limited to these. Further, the separation material may contain a mixture of polymers composed of structural units exemplified below. Copolymerization of these structural units facilitates the formation of a side chain complex when a relatively large low molecular weight ligand is used, and also facilitates the movement of the side chain complex in the membrane. Furthermore, even when polymers of these structural units are used in the form of a mixture, the degree of polymerization and structure are selected so that the side chain complexes can move easily.

(II is an integer from 0 to 6, and R is the degree of polymerization of these polymer structural units, which is 10 or more and 10°Oo
It is below O.

As described above, the separating agent of the present invention has a low molecular weight ligand having a hydroxyalkyl group consisting of R2, R3 and R9, and R
□1R41RG and a polymeric ligand consisting of R7.

Examples of low molecular weight ligands include jetanolamine, triethanolamine, 3-((2-hydroxyethyl)aminoco-1-propanol, 3.3'-((2-hydroxyethyl)imino)bis-1-propanol). Tools, 4-[(2
-hydroxyethyl)aminoco-1-butanol, 4
．． 4'-[(2-hydroxyethyl)imino]bis-1
-butanol, 5-((2-hydroxyethyl)aminoco-1-pentanol, 5.5'-((2-hydroxyethyl)imino)bis-1-pentanol, 6-((2
-hydroxyethyl)amino]-[-hexanol,
6. s'-[(2-hydroxyethyl)imino]bis-1-hexanol, 2-([2-(2-hydroxyethoxy)ethyl]amino]-ethanol, 2.2'-((
2-(2-hydroxyethoxy)ethyl]amino]-bis-ethanol, 2-[bis[2-(2-hydroxyethoxy)ethyl]amino]ethanol, 2.2'-((
6-Hydroxyhexane-1-yl)iminotubis-
Ethanol, 2.2'-((5-hydroxypentane-
1-yl) iminotubis-ethanol, 2,2'-[
(4-hydroxybutan-1-yl)iminotubis-
Ethanol, 2.2'-[(3-hydroxypropane-
1-yl)iminotubis-ethanol, 4-((2-hydroxyethyl)methylaminoco-1-butanol, 5-((2-hydroxyethyl)
Methylaminoco-1-pentanol, 6-((2-hydroxyethyl)methylaminoco-1-hexanol, and ligands in which the methyl group of these ligands is replaced with a short-chain alkyl ethyl group or n-propyl group) can be mentioned.

Also, 2,2'-(methylimino)bis-ethanol,
3-((2-hydroxyethyl)methylaminoco-1-
One example is the property tool.

In addition, as the polymeric ligand consisting of R,, R4, R, and R7 in the formula, 2,2'-(methylimino)bis-ethanol, 3-((2-hydroxyethyl)methylaminoco-1-propatol) methyl groups substituted with the side chains of the polymer structural units listed above, and relatively short alkyl groups such as N-methylethanolamine, N-ethylethanolamine, and N-n-propylethanolamine. Also included are ethanolamine derivatives having one group in which the hydrogen atom on the nitrogen is substituted with the side chain of the above-mentioned polymer structural unit.

When R1 and RG form a heterocycle containing a nitrogen atom, and R4 represents an alkylene group bonded to the heterocycle, examples of the heterocycle containing a nitrogen atom consisting of RG include pyridine, imidazole, etc. , R4 is a methylene group, and the side chain of the polymer structural unit has a 2-hydroxymethylpyridyl group, a 2-hydroxymethylimidazolyl group, etc.
Examples include a ligand having an aromatic heterocycle and having an alcoholic hydroxyl group at the 2-position relative to nitrogen.

Also R1. The Schiff base formed by R4 and R1+ together with the nitrogen atom is represented by the following formula, and represents an N droxyalkyl group, and R4R4 represents an ethylene group having 2 to 3 carbon atoms or a HO1,2-propylene group. ) Examples of alkyl groups include methyl group and ethyl group, and examples of hydroxyalkyl groups include 2-hydroxyethyl group,
Examples include 3-hydroxypropyl group.

Examples of the ligand having this include those of the following formula.

Examples of the polymer steel (u) complex of the present invention are as follows.

FiOCH,CH; ``C)ll shout OH'' The polymer steel (II) complex of the present invention can be produced by the following method.

The low-molecular ligand solution is mixed with @(II) salt solution in a 1:1 (molar ratio), and the polymer ligand (copper (II) versus side chain (7) HO-C-C -Equimolar of N) is added dropwise. Next, a solution of potassium hydroxide or sodium hydroxide is added twice in mole to copper (■) to synthesize. Note that half of the potassium hydroxide may be added before adding the polymeric ligand, or the polymeric ligand may be added in the form of perchlorate or hydrochloride; in this case, A solution of potassium hydroxide or sodium hydroxide is added 3 times the mole of copper (II).

In this case, one-third of potassium hydroxide or sodium hydroxide may be added before adding the polymeric ligand.

As the copper (TI) salt used in the synthesis of these complexes, steel (II) perchlorate hexahydrate, cupric chloride anhydride, etc. are preferably used.

In addition, regarding the solvent during synthesis, the ligand and the target
Alcohols such as methanol, ethanol, n-propanol, and a mixed solvent of ethanol and hexane are also used depending on the solvent.

The polymeric copper (■) complex of the present invention is formed into a film by the following method.

1. Membrane formation on a polymer non-porous film Here, the polymer non-porous film is a polytetrafluoroethylene polyolefin, such as polystyrene, polypropylene, polyethylene, ethylene-propylene copolymer, polybutadiene, poly(meth)acrylic. Acid esters such as polyethyl methacrylate, ethyl methacrylate-2-ethylhexyl methacrylate copolymer, polyurethane,
It is a film of polycarbonate, polysulfone, polyethersulfone, cellulose ester, polyester, or polyamide, and preferably one that does not react with the polymer steel (II) complex.

Alcohols such as methanol, ethanol, and n-propanol, and chlorinated hydrocarbons such as chloroform and dichloromethane are used alone or in combination depending on the solubility of the complex and the film, and polymer steel ([1 ) Make a complex solution, develop and dry.

When a polymeric copper (II) complex ethanol solution is applied to a polyolefin or polytetrafluoroethylene film, the surface of the film is subjected to plasma treatment, corona discharge treatment, etc. to improve wettability to the complex solution before use.

2. Formation of a film of polymeric steel (II) Iff The above solution is spread on mercury and dried, or a concentrated solution of the complex is spread on a polyolefin film or tetrafluoroethylene film (untreated) and then dried. Place under a nitrogen stream to rapidly evaporate the solvent and dry. After drying, it is peeled off from the mercury and the polyolefin film or tetrafluoroethylene film to form a film.

3. Film formation on a microporous polymer film (including impregnated and partially impregnated films) The microporous polymer film here is a film made of the film material shown in 1. After immersing this microporous polymer film in the solution shown in 1.

The film is pulled up and dried under a stream of dry nitrogen.

Further, a microporous polymeric film is placed on a polytetrafluoroethylene plate, a complex solution is spread thereon, and after drying, it is peeled off from the plate and used. When using a microporous membrane of polyolefin, such as polypropylene, polyethylene, or tetrafluoroethylene, it is necessary to perform plasma treatment or the like as shown in 1 to improve wettability.

In the carbon dioxide separation agent of the present invention, the copper (II) complex portion of the copper (II) complex forms a four-coordinate chelate complex by mixing a high molecular weight ligand and a low molecular weight ligand with respect to copper (TI). In addition, it is presumed that the hydroxyl group at the end of the hydroxyalkyl group is coordinated to some extent in the axial position, and as a result, the complex exists stably even in a film state and is thought to react reversibly with carbon dioxide.

EXAMPLE 1 Examples of the present invention are listed below, but it goes without saying that the present invention is not limited to these.

, 1.8 J1 Ethylene oxide □-shrimp chlorohydrin alternating copolymer (styrene equivalent molecular weight measured by G, P, C, approximately 17
5,000. 13.7g (confirmed to be a 1:1 copolymer by C-NMR) was placed in a 300mQ four-loop flask equipped with a nitrogen inlet tube, a stirrer, and a condenser.
150 mQ of dimethylacetamide was added and dissolved at 60°C for about 4 hours. Next, N-methylethanolamine 3
7.5 g (5 times the mole relative to the chlorine atoms in the polymer) was added, the temperature was raised to 100°C, and the reaction was carried out for 12 hours.

After cooling the reaction mixture, it was added dropwise to a large amount of diisopropyl ether to precipitate a polymer. The ether layer was removed by decantation, and the polymer was dissolved again in methanol. A large amount of diisopropyl ether was gradually added thereto, and after reprecipitation, the polymer was made into an ethanol solution. After ethanol was distilled off using an evaporator set at 30°C, the mixture was further dried under reduced pressure. The amount of polymer obtained was 16.58 g.

99.5% ethanol was added to make a 10.0% by weight ethanol solution.

Using this solution, phenolphthalein was used as an indicator and 0. While titrating with IN alcoholic potassium hydroxide, a certain amount of the solution was made into an aqueous solution using a pH meter, and the pH was adjusted to 0. Titration was performed with IN hydrochloric acid. The mass per mole of amine residue was 216.4.

Also, according to 1H-NMR of a deuterated chloroform solution of the polymer neutralized with sodium hydroxide, the δ value was determined.

Methyl group proton at 2.32 ppm, methylene proton directly bonded to nitrogen at 2.54 Ppm, 2.75
Methylene proton of chloromethyl group in ppm, 3.6p
A main chain proton and a methylene proton directly bonded to the oxygen of the hydroxyethyl group were observed near pm.

From these results, the polymeric ligand purified with ether (
Polymer ligand 1) is shown as follows.

18.5 g of polyepichlorohydrin polymer (styrene equivalent molecular weight approximately 180,000) was mixed with dimethylacetic acid 1-amide 20 in the same manner as shown in the process
Dissolve in 0 mfl, N-methylethanolamine 45.
After adding 1 g of the mixture and reacting at 80°C for 25 hours, the reaction was further continued at 100°C for 9 hours. 50 ml of reaction mixture
It was purified twice with 0 m Q diethyl ether and dried under reduced pressure. 99.5% ethanol was added to this to make a 10.0% by weight ethanol solution. As a result of the measurement, the amount per mole of amine was 168.6.

Furthermore, according to 13C-NMR of a deuterated chloroform solution of the polymer neutralized with sodium hydroxide, the δ value was 43.42.
ppm is the carbon of the methyl group, 58.80 ppm is the carbon of methylene bonded to the nitrogen atom, 59.91 ppm is the carbon of methylene bonded to the oxygen atom of the hydroxyethyl group, 7
A main chain carbon signal was observed at 0.69 ppm. Carbon signal of chloromethyl group (45,41ppm
) was not flHI9, but in the IR spectrum it was 7
A slight absorption based on C-CQ stretching vibration was observed at 40Qm-''.

From these results, the ether-purified polymeric ligand (referred to as polymeric ligand 2) is shown as follows.

(Polymer ligand 2) Example 1 Polymer ligand 1 obtained in the synthesis 1 of the polymer ligand,
A polymer complex was synthesized using triethanolamine, silver (II) perchlorate hexahydrate, hydrochloric acid, and potassium hydroxide. The blending amount is shown in Formulation 1.

Prescription 1 Solution number Compound name Number of moles Weight f(g
) Ethanol (g) a Triethanolamine 0.81 1.49 20b Silver (II) perchlorate hexahydrate /J 3.705
30C potassium hydroxide (85%) II
O, 66020d Lowt% polymeric ligand 1 ethanol solution ” 21.6
4 22e Hydrochloric acid (35.2%)
0.00835 0.1366 22f
Potassium hydroxide 0.02 1.32 40 solution was prepared by placing a magnetic stirrer in a 300 mA eggplant flask and stirring and dissolving under nitrogen. This solution had a slightly cloudy pale blue color. Solution a was gradually added dropwise while stirring.

At the end of the dropwise addition, a relatively clear cobalt blue solution was obtained. Next, C was added. It had a pale green-blue color. then e to d
In addition, the polymeric ligand 1 is in the form of an ammonium salt. This polymeric ligand monohydrochloride solution was gradually added. As the mixture was added, a yellow-green precipitate formed. Next, I added f.

As the solution was added, it took on a dull yellow-green color and finally became a cobalt blue solution. A fine white precipitate was formed here. After filtering the precipitate, concentrate the solution using an evaporator.
It was stored in a refrigerator (5°C) and salt was precipitated. After drying the supernatant liquid under reduced pressure, chelate titration was performed with EDTA.

The copper content was 13.1% by weight (calculated value 13.6%).

The obtained polymeric copper (■) complex is as follows.

Table 1 shows changes in the visible absorption spectrum of the ethanol solution of this complex due to carbon dioxide injection and the amount of carbon dioxide absorbed. In addition, a small amount of the complex was applied to a quartz plate, dried under nitrogen, and further dried under reduced pressure, and changes in the visible absorption spectrum in a carbon dioxide atmosphere were measured. Although it was left in a carbon dioxide atmosphere for 1 hour, almost no spectral change was observed in the visible region.

However, an increase in absorbance was observed near 350 nm. This quartz plate was left at a constant current of 41 in the spectrophotometer, and nitrogen was flowed through it at a flow rate of 10 omQ per minute for 3 hours, but almost no spectral change was observed. The spectral concubine results are shown in Table 2.

The side having fine pores of a polytetrafluoroethylene porous membrane with a pore size of 0.1 μm was plasma treated in air at 0.4 mmHg, and a 20% by weight ethanol solution of the complex was cast thereon. The film was left under dry nitrogen for several days,
Dry. Observation of the cross section using an optical microscope revealed that the complex was impregnated to a depth of approximately 15 μm from the surface of the porous membrane.

This was taken as the film thickness of this complex film.

The permeability coefficient of this film for carbon dioxide and nitrogen is calculated as a mixed gas of carbon dioxide and nitrogen (COz / Nz = 1.0
3), a+11 was determined by the low vacuum method. The results are shown in Table 3. After the gas permeation experiment was completed, the film, which had been left on the device for several days, was taken out and had a green color. When this was left in a nitrogen atmosphere, it returned to its original blue color in about 3 days, suggesting that it was reacting reversibly with carbon dioxide.

Example 2 183.0 g (3 mol) of ethanolamine, 108.6 g (1 mol) of 4-chloro-1-butanol and 300 cc of ethanol were mixed at 75° C. in the presence of sodium hydroxide for 50 minutes.
4-((2-hydroxyethyl)aminogo-1-butanol was obtained by distillation after neutralization (0,
1 mm Hg -144°C), the distillate was 61.45
g, the purification yield was 61.2%.

Next, 59.85 g (0.45 mol) of 4-((2-hydroxyethyl)aminogo-1-butanol) was added to a 200 ml tube equipped with a condenser, stirrer, thermometer, and nitrogen inlet tube.
The mixture was placed in four mQ flasks and heated to 85°C, and 16.29 g (0.15 mol) of 4-chloro-1-butanol was added dropwise over 30 minutes. After the dropwise addition was completed, the temperature was kept at 85°C for another 3 hours, and 80 cc of ethanol and 6.31 g of sodium hydroxide were added.
was added, neutralized and cooled, and then filtered. After distilling off the ethanol, the mixture was placed in a distillation flask, and the oil bath was set at 190°C to distill off 4-[(2-hydroxyethyl)aminogo-1-butanol. The residue was separated by column chromatography and 4.4'-((2-hydroxyethyl)
Imino]bis-1-butanol was obtained.

This 4.4'-((2-hydroxyethyl)imino)
Bis-1-butanol, polymeric ligand 1 (obtained from the synthesis of the polymeric ligand described above), copper(II) perchlorate 6
A complex was obtained in the same manner as in Example 1 using a hydrate, hydrochloric acid and potassium hydroxide. The color of the solution was purple. The copper content was 12.2% by weight (calculated value: 12.8% by weight) by chelate titration with EDTA. Obtained polymeric copper(II)
The complexes are as follows.

Table 1 shows the visible absorption spectrum measurement results and carbon dioxide absorption measurement results of this complex. Table 2 shows the results of measuring changes in the visible absorption spectrum of the film applied to a quartz plate.

The film on the quartz plate showed a large spectral change while placed in a carbon dioxide atmosphere for 1 hour, and then by placing it in a nitrogen atmosphere for 3 hours, there was a clear tendency for the spectral shape to return to its original shape, indicating reversibility. (See Figures 1 and 2).

Further, in the same manner as in Example 1, the gas permeability of the membrane cast as a polytetrafluoroethylene porous membrane was measured. The film thickness was 5 μm. In addition, a complex containing 30% by weight of polyethylene glycol having an average molecular weight of 300 was similarly formed into a film,
Gas permeability was measured. The film thickness was 55 μm.

Unlike in Example 1, both films rested on porous membranes.

The gas permeation measurement results are shown in Table 3.

Example 3 Triethanolamine, polymeric ligand 2 (obtained in the synthesis of polymeric ligand 2), perchloric acid steel (II).
A polymer complex was synthesized by carrying out the same operation as in Example 1 using hexahydrate and potassium hydroxide in the amounts shown in Formulation 2. The precipitated salt was filtered using a G-4 glass filter. The dry weight of salt is 3. Log (calculated value 3.15g)
The recovery rate was 99%.・Spinning 2 Solution number Compound name Number of moles Weight (g
) Ethanol (g) a Triethanolamine 0.01 1.49 10b Perchlorate steel (II) hexahydrate TI 3.705
16C potassium hydroxide (85%) t
r O, 66015d ICNα polymeric ligand 2 ethanol n ■ hard IE
#16.86 17e Potassium hydroxide (
85%) 0.964 23 From this, it was considered that the polymer complex was obtained almost quantitatively. Cast the concentrated complex solution on a Teflon plate,
The complex crystallized when left in a nitrogen atmosphere. Example 1
No crystallization was observed in the complex.

Further, this complex was dried under reduced pressure, and a 1H solution of deuterated chloroform was added.
-NMR spectra were measured. For comparison, the measured values of triethanolamine and polymer are shown. The chemical shift due to the δ value of triethanolamine shows that the methylene proton bonded to the nitrogen atom is seen as a triplet at 2.60 ppm, and the methylene proton bonded to the oxygen atom is seen as a triplet. The methylene proton present is seen as a triplet at 3.61 ppm.

The proton of the hydroxyl group is observed at 5.10 ppm. Regarding polymeric ligands, the methyl group proton is 2
- 32 ppm (value of polymeric ligand 1, same applies below), methylene proton bonded to nitrogen is found at 2.54 ppm.

On the other hand, the 1H-NMR signal of a heavy chloroform solution of this polymer steel (II) # is a signal at 1.28 ppm that is thought to be due to the proton of the methyl group, and a signal at 2.05 ~
At 3.15 ppm, a free hydroxyalkyl group appears to have a tendency to coordinate to copper ([[) at the center of the complex, and a group of splitting peaks at 2.05-2° soppm and a group of split peaks at 2.80-3 The signal of the methylene proton bonded to the nitrogen atom in A signal was observed, and the number of protons in the methyl group was 3.40 to about 4.5p.
Calculating the number of protons over pm is 7.5, and the number of protons between 2.05 and 3°15 ppm is 5.
．． There were 6 pieces. In addition to this, approximately 13 ppm and -10,
4 protons were observed at 5ppm, -3p
The ratio was 3 pieces per pm and 1 piece per -10.5 ppm. The protons of the ligands in the ring-forming part, including copper (I[), are largely shifted toward the lower magnetic field side and are not observed in the measurement tube 1 ffl (-13 ppm to +12 ppm). The polymer steel (II) complexes obtained from these are as follows.

30% by weight of polyethylene glycol having an average molecular weight of 300 was added to this complex, which was cast onto a polytetrafluoroethylene porous membrane, and the gas permeability was measured. The entire porous membrane was impregnated with the complex, and the membrane thickness was 60 μm.

The results are shown in Table 3.

The visible absorption spectra of the complexes of Examples 1 and 2 are approximately 5
Under a nitrogen atmosphere so that the amount of
It was dissolved in 9.5% ethanol in a 25 cc volumetric flask, and its visible absorption spectrum was measured using an 11 quartz cell (the maximum absorption wavelength of this spectrum is defined as λmax).

After the measurement, the solution was returned to the volumetric flask, and carbon dioxide was blown into it through the syringe needle at a flow rate of 100 cc per minute for 1 minute, and the visible spectrum was measured again (the maximum absorption wavelength of this spectrum is defined as λ+eax CO2). The spectra between them were compared, the absorbance difference in the visible region was determined, and the wavelength showing the maximum value was determined.

Among these, the peak of the absorption band that appeared due to the reaction with carbon dioxide was designated as λb.

Transfer the solution to the volumetric flask again and turn on nitrogen at 1 minute per minute for 6 minutes.
00cc was injected and the spectrum change was examined. The peak that appears when nitrogen is injected is designated as λa. An isosbestic point (referred to as 1) was observed in these series of measurements.

The spectral recovery rate (referred to as R) was determined based on how much the absorbance at λb decreased due to nitrogen injection, and was used as a measure of the reversibility of the reaction.

Measurement of carbon dioxide absorption amount The complexes of Examples 1 and 2 were added to 99.5% ethanol for about 2 hours.
Dissolve 5.0 cc of this solution in a nitrogen atmosphere so that the concentration is 10-" (The internal pressure is always kept the same as atmospheric pressure).

Next, 10.0 cc of carbon dioxide was added using a gastight syringe (dead volume 0.12 cc), and after 10 minutes and 2
The gas composition on the solution after 0 minutes is determined by gas chromatography to determine the amount of carbon dioxide absorbed by the solution. The amount of carbon dioxide absorbed by ethanol was measured to determine the amount of carbon dioxide absorbed by the complex itself.

The amount of carbon dioxide absorbed by ethanol was in good agreement with the theoretical value. After the carbon dioxide absorption experiment, further into the solution.

Blow in carbon dioxide for 1 minute and measure the visible absorption spectrum. The absorbance at λb was determined, and the rate of change in the spectrum was determined using the following equation.

Here, Aλb is the absorbance at λb of the solution after the carbon dioxide absorption experiment, Aλb 1nitial is the absorbance at λb of the solution that has not absorbed carbon dioxide, and A, tbco□ is the absorbance at λb of the solution after the carbon dioxide absorption experiment. The absorbance of the solution at λb is shown. S, C, R, are spectral change rates.

Further, the recovery rate of the spectrum at λb when nitrogen was blown for 6 minutes after this carbon dioxide injection was determined by the following equation.

R = 100-S, C, R.

Here, R indicates the spectral recovery rate.

The polymer steel (II) complex of the present invention absorbs carbon dioxide,
It reacts reversibly with carbon dioxide in an ethanol solution (see Table 1), and also reacts with carbon dioxide in a dry film as shown in the visual reversible color change shown in Example 1 and in Example 2 of Table 2. It reacts reversibly with carbon.

The polymer steel (II) complex of the present invention is further softened by adding polyethylene glycol having an average molecular weight of 300 (permeability coefficient ratio of carbon dioxide to nitrogen is 19).
Carbon dioxide separation performance (P・α”′C, P・α50°C
(see Table 3).

The polymer steel (II) complex of the present invention is a conventionally known copper (If) complex.
-Alkanolamine complexes allow reactions with carbon dioxide to be carried out reversibly even in the absence of solvents, where reactions with carbon dioxide cannot be carried out reversibly.

The polymer steel (II) complex of the present invention can be used as a carbon dioxide selective separation membrane, and in that case, the separation performance can be further improved by adding a softener.

[Brief explanation of drawings]

FIG. 1 is a diagram showing changes in the visible absorption spectrum of the polymer steel (II) complex obtained in Example 2 when it was left under carbon dioxide for 1 hour, and FIG. ) The complex was left under carbon dioxide for 1 hour and then further nitrogenated for 3 hours.
FIG. 3 is a diagram showing changes in visible absorption spectrum when left for a period of time.

Claims (1)

[Claims] (1) A carbon dioxide selective separation agent containing a copper (II) complex represented by the general formula (I) as a polymer constituent unit. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, at least one of R_1, R_2 and R_3 represents a hydroxyalkyl group, the others represent a hydrogen atom or a hydrocarbon residue, R_4, R_5 and R_6 represents an alkylene group, R_7 represents a polymer structural unit. R_1 and R_6 can also form a heterocycle containing a nitrogen atom, in which case R_4 represents an alkylene group bonded to the heterocycle, and R_1 , R_4 and R_6 may form a Schiff base together with the nitrogen atom.]