JP2006297278A - Gas absorbent, its manufacturing method and gas-absorbing method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas absorbent having good gas-absorbing performance and causing no leaching of a polyvalent metal (A) contained in the gas absorbent in the liquid when used in a liquid. <P>SOLUTION: The problem of the leaching is solved by providing a gas absorbent consisting of a metal complex (D) composed of a polyvalent metal (A), a polycarboxylic acid (B) of a molecular weight below 500 and a polymer (C) of a molecular weight of ≥500 having a carboxyl group. The gas absorbent most preferably consists of the metal complex composed of divalent copper, trimesic acid and polyacrylic acid. The gas absorbent is preferably employed to absorb a gas dissolved in a liquid. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gas absorbent comprising a metal complex comprising a polyvalent metal, a polyvalent carboxylic acid, and a polymer having a carboxyl group. Further, the present invention relates to a method for producing a gas absorbent in which a metal complex is formed by reacting a polyvalent metal salt, a polyvalent carboxylic acid, and a polymer having a carboxyl group. Furthermore, it is related with the gas absorption method which makes the said gas absorbent absorb the gas dissolved in a liquid.

  Various compounds are synthesized by chemical reactions using transition metals or their compounds as catalysts. Examples of such a catalytic reaction include a hydroformylation reaction, a hydrogenation reaction, a polymerization reaction, and an addition reaction.

  For example, Patent Document 1 discloses that a hydroformylation reaction is performed by reacting 3-methyl-3-buten-1-ol with carbon monoxide and hydrogen in the presence of a specific rhodium compound. A method for producing 3-methylpentane-1,5-diol in which a hydrogenation reaction is carried out in the presence of water, a hydrogenation catalyst and a solid acid is disclosed. The rhodium compound is recovered from the reaction system after the hydroformylation reaction, and a hydrogenation catalyst is added separately.

  As described above, many methods for obtaining a target compound by performing a different catalytic reaction using a compound obtained by performing a certain catalytic reaction have been adopted. At this time, after the compound obtained by the first catalytic reaction is separated from the reaction system by distillation or the catalyst is filtered off, the second catalytic reaction may be performed using the compound and the new catalyst. It is common.

  Here, some types of catalysts can be used for a plurality of chemical reactions. For example, the rhodium compound can be used as a catalyst for hydroformylation reaction and hydrogenation reaction. However, after the hydroformylation reaction, when the hydrogenation reaction is carried out using the reaction solution as it is without performing any special treatment other than degassing, the carbon monoxide gas still dissolved in the reaction solution , Side reaction products were obtained, and the catalyst was inactivated. For example, a problem occurs when a compound having a terminal double bond and an internal double bond is subjected to a hydroformylation reaction of the terminal double bond and then a hydrogenation reaction of an unreacted internal double bond. That is, when hydrogen gas is pressurized to advance the hydrogenation reaction, carbon monoxide gas dissolved in the reaction solution reacts with the internal double bond, and a side reaction product in which a carbonyl group is introduced inside Things could be obtained. For this reason, it has been required to separate and remove the gas dissolved in the reaction solution.

  Conventionally, as a method of separating and removing a specific gas component in a liquid, a method of absorbing and removing the gas by bringing the liquid into contact with a gas absorbent typified by zeolite and activated carbon has been adopted. However, these gas absorbents have a small amount of gas absorption, particularly when the gas dissolved in the solution has a low concentration. Moreover, if the absorption and release of gas were repeated, the absorption and release performance deteriorated and could not be used repeatedly.

  On the other hand, Patent Document 2 discloses a porous complex having a specific structural formula and a powder X-ray diffraction pattern synthesized from copper ions and trimesic acids. It is described that the porous complex can be used as an adsorbent because it has a large specific surface area and absorbs nitrogen gas and oxygen gas. However, there is no description of removing the gas dissolved in the liquid, and no consideration is given to problems that occur when used in the liquid.

JP-A 61-249940 JP 2000-327628 A

  Therefore, the present inventors examined the possibility of application of the porous complex in order to separate and remove the gas dissolved in the reaction solution, and although the gas absorption performance is good, from the porous complex It has been found that the problem that the copper component elutes in the liquid occurs. The elution of the copper component is expected to reduce the gas absorption performance. Moreover, since the eluted copper component may affect the subsequent chemical reaction or reduce the catalytic activity, it is necessary to prevent this.

  The present invention has been made to solve the above-mentioned problems, and has a good gas absorption performance. Further, when used in a liquid, the polyvalent metal (A) component contained in the gas absorbent is a liquid. It aims at providing the gas absorbent which does not elute in. It is another object of the present invention to provide a method for producing such a gas absorbent and a gas absorption method using the same.

  The above-mentioned problem is gas absorption comprising a metal complex (D) comprising a polyvalent metal (A), a polyvalent carboxylic acid (B) having a molecular weight of less than 500, and a polymer (C) having a carboxyl group having a molecular weight of 500 or more. It is solved by providing an agent.

  At this time, the polyvalent metal (A) is preferably divalent copper, and the polyvalent carboxylic acid (B) is a carboxylic acid having carboxyl groups at the 1-position, 3-position and 5-position of the benzene ring. preferable. The polymer (C) is preferably poly (meth) acrylic acid.

  In the infrared absorption spectrum of the metal complex (D), the absorbance of the absorption peak derived from the carboxyl group coordinated to the polyvalent metal (A) among the absorption peaks derived from the carboxyl group of the polymer (C) is The absorbance of an absorption peak derived from a carboxyl group that is not coordinated to the polyvalent metal (A) is preferably larger.

  The X-ray diffraction pattern of the metal complex (D) preferably has a peak derived from the crystal structure. At this time, compared to the X-ray diffraction pattern of the metal complex consisting only of the same polyvalent metal (A) and the same polyvalent carboxylic acid (B), the peak top of the main peak is on the narrow angle side, and the main peak It is preferable that the full width at half maximum of is wide. The gas absorbent is preferably formed by coating the metal complex (D) with the polymer (E).

  Moreover, the said subject made the metal complex (A) by making the salt of polyvalent metal (A), polyvalent carboxylic acid (B) of molecular weight less than 500, and the polymer (C) which has a carboxyl group of molecular weight 500 or more react. It is also solved by providing a method for producing a gas absorbent characterized by producing D).

At this time, it is preferable to add a salt of the polyvalent metal (A) to a solution in which the polyvalent carboxylic acid (B) and the polymer (C) are dissolved, and react them. It is also preferable to react in a mixed solvent of alcohol and water. The molar ratio (b / c) between the carboxyl group amount (b) of the polyvalent carboxylic acid (B) and the carboxyl group amount (c) of the polymer (C) is 99.9 / 0.1 to 50/50. Preferably there is. Further, when the valence of the polyvalent metal (A) is m, the total amount of carboxyl groups (b + c) of the polyvalent carboxylic acid (B) and the polymer (C) with respect to the amount (a) of the polyvalent metal (A). It is also preferable that the molar ratio [(b + c) / a] satisfies the following formula (1).
0.2 m ≦ (b + c) / a ≦ 50 m (1)

  A preferred embodiment is a gas absorption method characterized by absorbing a gas dissolved in a liquid using the gas absorbent. The liquid is preferably a coordinating organic compound, and preferably absorbs at least one gas selected from carbon monoxide, carbon dioxide, methane, and ethane. Further, it is preferable to absorb the gas at a pressure of atmospheric pressure to 1 MPa and a temperature of -40 to 100 ° C.

  It is a preferred embodiment of the present invention to absorb a gas that dissolves in the liquid and inhibits a chemical reaction using the gas absorbent. At this time, the chemical reaction is preferably a catalytic reaction. It is also preferable to absorb a gas that dissolves in the liquid and inhibits the chemical reaction in advance before the chemical reaction is performed.

  According to the gas absorbent of the present invention, the gas absorption performance is good, and the polyvalent metal (A) component contained in the gas absorbent is not eluted into the liquid when used in the liquid. A gas absorbent can be provided. Moreover, according to the manufacturing method of the gas absorbent of this invention, the suitable manufacturing method of such a gas absorbent can be provided. Furthermore, a gas absorption method using the gas absorbent can be provided.

  The gas absorbent of the present invention comprises a metal complex (D) comprising a polyvalent metal (A), a polyvalent carboxylic acid (B) having a molecular weight of less than 500, and a polymer (C) having a carboxyl group having a molecular weight of 500 or more. A gas absorbent. Details will be described below.

  Although the manufacturing method of such a gas absorbent of this invention is not specifically limited, It has a polyvalent metal (A) salt, polyvalent carboxylic acid (B) having a molecular weight of less than 500, and a carboxyl group having a molecular weight of 500 or more. A method of reacting the polymer (C) to form a metal complex is preferred.

  The polyvalent metal (A) is not particularly limited as long as it is a metal having a valence of 2 or more, but together with the polyvalent carboxylic acid (B), a regular network serving as a basic skeleton of the gas absorbent of the present invention. It forms a structure and develops gas absorption performance. Examples of the divalent polyvalent metal (A) include chromium, cobalt, nickel, copper, zinc, molybdenum, ruthenium, rhodium, palladium and tungsten. Examples of the trivalent polyvalent metal (A) include lanthanum, scandium, and yttrium. Etc. are exemplified. It is also possible to consist of a plurality of kinds of metals having the same valence. In order to stably maintain the network structure of the metal complex, it is preferable that the polyvalent metal (A) has an affinity for the gas molecule to be absorbed and does not easily become zero valent. Among these, divalent copper is particularly preferable. This is because a metal complex having high network structure stability and good gas absorption performance can be obtained, and is easily available industrially and has excellent storage stability. In addition, since divalent copper has good affinity with carbon monoxide gas and carbon dioxide gas, it is particularly preferably used when it is desired to absorb these gases.

  The salt of the polyvalent metal (A) used in producing the metal complex (D) is not particularly limited, and mineral salts such as sulfates and nitrates, carboxylates such as formates and acetates, Examples thereof include carbonates and the like, and hydrates and complex salts of amines and the like. Among them, acetates that are easily available industrially and have high storage stability are preferably used. On the other hand, when the obtained gas absorbent is used in a liquid, halogen is eluted into the liquid, which may increase the irritation of the liquid or react with the liquid. Preferably there is. Further, when the halogen is eluted into the liquid, the metal material used for the container or the like may be corroded, or may have an adverse effect when a chemical reaction is performed in the liquid.

  The polyvalent carboxylic acid (B) is a carboxylic acid having a molecular weight of less than 500 and having two or more carboxyl groups in the molecule. The polyvalent carboxylic acid (B), together with the polyvalent metal (A), exhibits gas absorption performance by forming a regular network structure that is the basic skeleton of the gas absorbent of the present invention. When the molecular weight of the polyvalent carboxylic acid exceeds 500, it becomes difficult to form a network structure, and the gas absorption performance decreases. The molecular weight of the polyvalent carboxylic acid (B) is preferably 400 or less, more preferably 300 or less, and usually 100 or more.

  Here, the polyvalent carboxylic acid (B) is not particularly limited as long as the number of carboxyl groups in the molecule is 2 or more, a dicarboxylic acid having 2 carboxyl groups in the molecule, a tricarboxylic acid having 3 carboxyl groups, and the like. Is exemplified. Among these, tricarboxylic acid is preferable. This is because the resulting metal complex has a strong network structure, and is often resistant to heat and maintains good gas absorption performance even in a liquid and can be reused repeatedly.

  Dicarboxylic acids include saturated divalent fatty acids such as succinic acid and adipic acid; unsaturated divalent fatty acids such as fumaric acid and acetylenedicarboxylic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; isophthalic acid, terephthalic acid, biphenyldicarboxylic acid Acid, triphenyl dicarboxylic acid, biphenyl amide dicarboxylic acid, biphenyl ester dicarboxylic acid, biphenyl acetyl dicarboxylic acid, stilbene dicarboxylic acid, trans dicarboxylic acid, biphenyl ethylene dicarboxylic acid, aromatic dicarboxylic acid such as 2,6-naphthalenedicarboxylic acid, etc. Can be mentioned.

  Examples of the tricarboxylic acid include carboxylic acids having a carboxyl group at the 1st, 3rd and 5th positions of the benzene ring such as trimesic acid; a carboxylic acid having a carboxylic group at the 1st, 2nd and 3rd positions of the benzene ring such as hemimellitic acid. A carboxylic acid having a carboxyl group at the 1-position, 2-position and 4-position of a benzene ring such as trimellitic acid; a carboxylic acid having a carboxyl group at the 1-position, 3-position and 5-position of a cyclohexane ring; A carboxylic acid having a carboxyl group at the 1-position and the 3-position; a carboxylic acid having a carboxyl group at the 1-position, 2-position and 4-position of the cyclohexane ring; a carboxylic acid having a carboxyl group at the 2-position, 4-position and 6-position of the piperidine ring; Carboxylic acids having carboxyl groups at the 2-position, 3-position and 4-position of the piperidine ring; carboxy at the 2-position, 3-position and 5-position of the piperidine ring A carboxylic acid having a group.

  Especially, it is preferable that polyvalent carboxylic acid (B) is carboxylic acid which has a carboxyl group in 1-position, 3-position, and 5-position of a benzene ring. This is because the three carboxyl groups are arranged at an angle of 120 ° to each other, so that a three-dimensional network configuration can be easily formed and a metal complex (D) having good gas absorption performance can be obtained.

  In this case, in the carboxylic acid, at least one hydrogen atom of the benzene ring may be substituted with an alkyl group, a halogen group or the like. However, when using a gas absorbent in a liquid, the halogen will elute into the liquid, causing corrosion of the metal material used in the container, etc., or adversely affecting the chemical reaction in the liquid. Therefore, it is preferably not substituted with a halogen group. In addition, since there is a possibility that the substituent may inhibit the invasion of gas molecules into the network structure, it is preferable that none of the hydrogen atoms is substituted in order to obtain a metal complex having good gas absorption performance. . That is, trimesic acid is optimal.

  The gas absorbent of the present invention comprises a metal complex comprising a polymer (C) having a carboxyl group having a molecular weight of 500 or more in addition to the polyvalent metal (A) and the polyvalent carboxylic acid (B). Usually, by combining a polymer with the polyvalent metal (A) and the polyvalent carboxylic acid (B), the regular network structure is disturbed, and the gas absorption performance is expected to be greatly reduced. However, surprisingly, even when the polymer (C) having a carboxyl group having a molecular weight of 500 or more is incorporated into the structure, it can maintain a regular network structure and has excellent gas absorption performance. It was found. Moreover, at this time, the carboxyl group in the polymer (C) is coordinated to the polyvalent metal (A) as a carboxy anion, so that the polyvalent metal (A) is firmly fixed to the polymer (C). Therefore, it was found that elution of the polyvalent metal (A) component into the liquid is greatly suppressed.

  The polymer (C) is not particularly limited as long as the molecular weight of the polymer is 500 or more and the polymer has a carboxyl group. When the molecular weight of the polymer is less than 500, it is difficult to suppress elution of the polyvalent metal (A) component when used in a liquid. More preferably, it is 1,000 or more, More preferably, it is 2,000 or more. The molecular weight of the polymer (C) is preferably 1,000,000 or less. When it exceeds 1,000,000, the viscosity of the solution in which the polymer (C) is dissolved becomes too high, and it may be difficult to produce the metal complex (D). More preferably, it is 500,000 or less. Here, the molecular weight of the polymer (C) is a weight average molecular weight determined by gel permeation measurement.

  It does not specifically limit as a polymer (C) which has a carboxyl group, Usually, the polymer containing the repeating unit which has a carboxyl group is illustrated. The repeating unit having a carboxyl group is not particularly limited, and examples thereof include (meth) acrylic acid units, fumaric acid units, maleic acid units, itaconic acid units, and 4-vinylbenzoic acid units. The polymer (C) is preferably a polymer consisting essentially of a repeating unit having one kind of carboxyl group from the standpoint of regularity, but comprising a repeating unit having two or more kinds of carboxyl groups. Copolymers and copolymers containing a repeating unit having a carboxyl group and a repeating unit having no carboxyl group can also be used. At this time, the copolymer may be a block copolymer or a random copolymer, but is preferably a block copolymer from the viewpoint of regularity. In the case of a block copolymer containing a repeating unit having a carboxyl group and a repeating unit having no carboxyl group, the polymer chain portion composed of a monomer having no carboxyl group does not participate in the formation of the network structure. Therefore, as a result of obtaining a more porous metal complex (D), more excellent gas absorption performance may be exhibited. For example, as such a polymer (C), a (meth) acrylic acid-styrene block copolymer is illustrated.

  Examples of the polymer (C) in which the repeating unit is a (meth) acrylic acid unit include poly (meth) acrylic acid, acrylic acid-methacrylic acid copolymer, and co-polymerization of (meth) acrylic acid and other monomers. Polymer: The polymer (C) in which the repeating unit is a fumaric acid unit includes polyfumaric acid, a copolymer of fumaric acid and other monomers, and the polymer in which the repeating unit is a maleic acid unit includes polymaleic acid , Copolymers of maleic acid and other monomers, hydrolyzed polymers of styrene-maleic anhydride copolymer; polymers having repeating units of itaconic acid units include polyitaconic acid, itaconic acid and other single monomers Examples thereof include a copolymer with a body. Among them, the polymer (C) in which the repeating unit is a (meth) acrylic acid unit is preferable because it can be easily taken into the network structure in the metal complex and can maintain good gas absorption performance. From the viewpoint of industrial availability, storage stability, and cost, poly (meth) acrylic acid, and most preferably polyacrylic acid is more preferable.

  The method for reacting the salt of the polyvalent metal (A), the polyvalent carboxylic acid (B), and the polymer (C) is not particularly limited, but it is preferable to react these in a solution. Among them, it is preferable to add a salt of the polyvalent metal (A) to a solution in which the polyvalent carboxylic acid (B) and the polymer (C) are dissolved, and react them. By adding a salt of the polyvalent metal (A) to a solution in which the polyvalent carboxylic acid (B) and the polymer (C) are dissolved, the polyvalent metal of the carboxyl group (B) possessed by the polyvalent carboxylic acid (B) ( A competitive reaction occurs between the coordination to A) and the coordination of the carboxyl group of the polymer (C) to the polyvalent metal (A). Thereby, it is possible to obtain a metal complex (D) having a regular network structure and suppressing elution of the polyvalent metal (A) when used in a liquid. At this time, the salt of the polyvalent metal (A) may be added in advance dissolved in another solvent. On the other hand, when the polyvalent carboxylic acid (B) and the polymer (C) are added to the solution in which the salt of the polyvalent metal (A) is dissolved, the reaction with the polyvalent carboxylic acid (B) takes precedence, and The coalescence (C) may be difficult to be taken in. Thereby, there is a possibility that the effect of suppressing elution of the polyvalent metal (A) when used in a liquid may be reduced.

  The solvent used in the reaction of the polyvalent metal (A) salt, the polyvalent carboxylic acid (B) having a molecular weight of less than 500, and the polymer (C) having a carboxyl group having a molecular weight of 500 or more is a polyvalent metal (A ), The polyvalent carboxylic acid (B), and the polymer (C) are not particularly limited. It is preferable that all of these compounds are easily dissolved, the resulting metal complex (D) is difficult to dissolve, and the solvent does not hinder the formation of the network. As the solvent, water; monohydric alcohol such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, neopentyl alcohol; ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, Polyhydric alcohols such as trimethylolpropane; ketones such as diethyl ketone, methyl ethyl ketone, and cyclohexanone; ethers such as diethyl ether, dibutyl ether, methyl butyl ether, and furan; esters such as ethyl acetate and butyl acetate; cellosolves and the like are used. The solvent may be a mixed solvent of two or more kinds, and may contain a hydrocarbon such as benzene, toluene, xylene, n-hexane, cyclohexane, etc., which are poor solvents.

  Among these, in consideration of the solubility of the salt of the polyvalent metal (A), the polyvalent carboxylic acid (B) and the polymer (C), the reaction is preferably performed in a mixed solvent of alcohol and water. As the alcohol, it is preferable to use an alcohol having 1 to 5 carbon atoms alone or in combination of two or more, but considering miscibility with water and cost, methanol, ethanol, n-propanol or At least one alcohol selected from the group consisting of isopropanol is more preferable, and methanol is particularly preferable. Moreover, it is preferable that the mixing ratio of alcohol and water is 1: 10-10: 1 by volume ratio. This is because a metal complex (D) having higher gas absorption performance can be obtained. More preferably, it is 1: 7-7: 1, More preferably, it is 1: 5-5: 1. The mixed solvent of alcohol and water may be used in combination with other solvents such as ketones, ethers, esters, cellosolves, polyhydric alcohols, hydrocarbons, etc., but the solubility of the divalent copper salt of the raw material is not limited. May be worse.

  The amount of solvent used is not particularly limited, but it is preferable to use a weight of 10 to 2000 times the total weight of the salt of the polyvalent metal (A), the polyvalent carboxylic acid (B) and the polymer (C). It is more preferable to use a weight of 30 to 1000 times from the viewpoint of easy control of the reaction.

Usually, when the valence of the polyvalent metal (A) is m, 1 mol of the polyvalent metal (A) reacts with m mol of carboxyl groups. Using this ratio as a guide, the salt of the polyvalent metal (A) is reacted with the polyvalent carboxylic acid (B) and the polymer (C), but either one may be used in excess of the ratio. When the valence of the polyvalent metal (A) is m, the total amount of carboxyl groups (b + c) of the polyvalent carboxylic acid (B) and the polymer (C) with respect to the amount (a) of the polyvalent metal (A). The molar ratio [(b + c) / a] preferably satisfies the following formula (1).
0.2 m ≦ (b + c) / a ≦ 50 m (1)

  When the molar ratio [(b + c) / a] is less than 0.2 m, the polyvalent metal (A) is taken into the obtained metal complex, which may not be removed even by washing. More preferably, it is m or more. Moreover, it is more suitable that it is m or more also from a viewpoint from which the metal complex (D) which has the outstanding gas absorption performance is obtained. The molar ratio [(b + c) / a] being m or more means that the total amount of carboxyl groups (b + c) is equal to or more than the amount of carboxyl groups that react with the polyvalent metal (A) without excess or deficiency. Means that. On the other hand, when the molar ratio [(b + c) / a] exceeds 50 m, it is advantageous in terms of reaction, but may be disadvantageous economically. More preferably, it is 40 m or less, More preferably, it is 20 m or less, Most preferably, it is 10 m or less.

  The ratio of the polyvalent carboxylic acid (B) and the polymer (C) is not particularly limited, but the carboxyl group amount (b) of the polyvalent carboxylic acid (B) and the carboxyl group amount (c) of the polymer (C). And the molar ratio (b / c) is preferably 99.9 / 0.1 to 50/50. When the molar ratio (b / c) exceeds 99.9 / 0.1, the polymer (C) is hardly taken into the network structure of the metal complex, thereby preventing the elution of the polyvalent metal (A). May become difficult. More preferably, it is 99/1 or less, More preferably, it is 95/5 or less. On the other hand, if it is less than 50/50, a regular network structure is not sufficiently formed, and the gas absorption performance may be insufficient. More preferably, it is 55/45 or more, and still more preferably 60/40 or more.

  The temperature at which the salt of the polyvalent metal (A), the polyvalent carboxylic acid (B) having a molecular weight of less than 500 and the polymer (C) having a carboxyl group having a molecular weight of 500 or more are reacted is 30 to 300 ° C. preferable. If it is lower than 30 ° C, the reaction rate may be very slow. More preferably, it is 40 degreeC or more, More preferably, it is 50 degreeC or more. On the other hand, if it exceeds 300 ° C., the metal complex produced may be decomposed. More preferably, it is 200 degrees C or less, More preferably, it is 180 degrees C or less. Particularly preferred is the reflux temperature of the solvent used. A normal pressure is sufficient as the reaction pressure, but pressurizing conditions may be adopted. The reaction time is appropriately selected depending on the reaction temperature, but is usually 1 to 20 hours.

  After completion of the reaction, the reaction is cooled as necessary to obtain the metal complex (D) as a precipitate. The metal complex (D) can be easily isolated by filtering or decanting the precipitate. Thereafter, washing with water or an organic solvent is performed as necessary. It is preferable to remove the solvent of the isolated metal complex (D) by heating it immediately under reduced pressure. If left undissolved for several days, the network structure of the metal complex (D) may change and the gas absorption performance may be reduced. However, if the solvent is removed, the structure of the metal complex (D) is stable. It is because it becomes. The heating temperature is preferably 50 to 250 ° C.

  The gas absorbent comprising the metal complex (D) obtained as described above has good gas absorption performance, and even when used in a liquid, elution of the polyvalent metal (A) component is greatly suppressed. Is.

  In the infrared absorption spectrum of the metal complex (D), the absorbance of the absorption peak derived from the carboxyl group coordinated to the polyvalent metal (A) among the absorption peaks derived from the carboxyl group of the polymer (C) is The absorbance of an absorption peak derived from a carboxyl group that is not coordinated to the polyvalent metal (A) is preferably larger. This means that the majority of the carboxyl groups of the polymer (C) are coordinated to the polyvalent metal (A) as a carboxy anion. Therefore, since the polyvalent metal (A) is fixed to many carboxyl groups in the polymer (C) existing in the network structure, when used in a liquid, the polyvalent metal (A) component is eluted. Is effectively suppressed. More preferably, an absorption peak derived from a carboxyl group that is not coordinated to the polyvalent metal (A) is hardly observed. Since the polyvalent metal (A) is fixed to most of the carboxyl groups in the polymer (C), elution of the polyvalent metal (A) component is particularly effectively suppressed when used in a liquid. .

  The X-ray diffraction pattern of the metal complex (D) preferably has a peak derived from the crystal structure. Generally, when the polymer (C) is incorporated into a crystal structure derived from a regular network structure, the regular network structure is destroyed and the crystallinity is disturbed, resulting in a decrease in gas absorption performance. That is expected. However, the gas absorbent of the present invention is considered to have high gas absorption performance by maintaining a regular network structure even when the polymer (C) is incorporated into the crystal structure.

  At this time, in the X-ray diffraction pattern of the metal complex (D), the X-ray diffraction pattern of the metal complex consisting only of the same polyvalent metal (A) and the same polyvalent carboxylic acid (B) having a molecular weight of less than 500; In comparison, it is preferable that the peak top of the main peak is on the narrow angle side and the half width of the main peak is wide. Here, the main peak refers to the peak with the highest intensity, and the half width refers to the width of the peak at a height that is half the height of the peak of the main peak. The fact that the peak top of the main peak is on the narrow-angle side suggests that the polymer (C) is incorporated into the crystal structure of the metal complex (D), thereby loosening the crystal lattice, and that the half-width is wide. This suggests that the regularity of the crystal is slightly disturbed.

  The gas absorbent of the present invention is preferably formed by coating the metal complex (D) particles with the polymer (E). This is because by covering the metal complex (D) particles with a polymer, elution of the polyvalent metal (A) component contained in the metal complex can be more effectively suppressed. Although gas molecules can pass through the coating layer of the polymer (E) relatively easily, it is considered that the polyvalent metal (A) accompanied by the ligand and solvent molecules cannot pass through easily.

  Further, it is more preferable that substantially the entire surface of the metal complex (D) particles is coated with the polymer (E). This is because, when used in a liquid, the effect of suppressing elution of the polyvalent metal (A) component is enhanced. The fact that the entire surface of the particle is coated with the polymer (E) should be confirmed by observation with a scanning electron microscope (SEM) that the presence of the exposed metal complex is hardly observed. Is possible.

  The polymer (E) is not particularly limited as long as it can coat the metal complex particles and does not dissolve in the liquid when the gas absorbent is used in the liquid.

  The method for coating the metal complex particles with the polymer (E) is not particularly limited, and various techniques that have been studied and reported in various fields including pharmaceuticals can be used. For example, a method in which polymer (E) and metal complex particles are mixed in a solution, a method in which a solution in which polymer (E) is dissolved or dispersed is sprayed on the surface of metal complex particles, and a monomer is polymerized on the surface of metal complex particles. And a method of accommodating a metal complex in a capsule made of a polymer (E) formed in advance. In particular, a coating layer excellent in adhesion to the particle surface of the metal complex is easily formed, and a metal complex in which the entire surface of the particle is substantially coated is easily obtained. A method of polymerizing monomers is preferably used.

  As a specific example of the method of mixing the polymer (E) and metal complex particles in the solution, the metal complex is stirred and dispersed in the solution containing the polymer (E), cooled, and then the polymer (E) is poor. Dispersion by stirring a metal complex in a solution containing polymer (E) by adding a solvent and curing the swollen polymer (E) (Microcapsules and Nanoparticles in Medicine and Pharmacy; CRC Press: Boca Raton, 1992) An example is a method in which the polymer (E) is cured by being dropped and cooled in a poor solvent for the polymer (E).

  The monomer used when the monomer is polymerized on the surface of the metal complex particle is not particularly limited, and is a methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid. (Meth) acrylic ester monomers such as 2-ethylhexyl, dodecyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, polyethylene glycol di (meth) acrylate; styrene, α-methylstyrene, p-hydroxystyrene, Styrenic monomers such as p-methoxystyrene, p-styrenesulfonic acid and sodium salt or potassium salt thereof; methyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl A And vinyl ether monomers such as dodecyl vinyl ether; (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, diacetone (meth) acrylamide, (meth) Acrylamidepropanesulfonic acid and its salts, (Meth) acrylamidopropyldimethylamine and its salts or quaternary salts thereof, (Meth) acrylamide monomers such as N-methylol (meth) acrylamide and its derivatives; Nitriles such as (meth) acrylonitrile Allyl compounds such as allyl acetate and allyl chloride; maleic acid and salts or esters thereof; itaconic acid and salts or esters thereof; vinylsilyl compounds such as vinyltrimethoxysilane; Nil and the like are used. Two or more types of monomers can also be used. The monomer may be a macromonomer having an unsaturated double bond at the end of the polymer chain. Among these, it is preferable to use a (meth) acrylic acid ester monomer. This is because the polymer (E) obtained by polymerizing the (meth) acrylic acid ester monomer has good adhesion to the surface of the metal complex particles. In addition, the use of a monomer having two or more double bonds in the molecule such as polyethylene glycol di (meth) acrylate provides a coating layer made of a crosslinked polymer (E), and a polyvalent metal (A ) It is desirable that the elution of the component can be satisfactorily suppressed.

  The method for polymerizing the monomer on the surface of the metal complex (D) particles is not particularly limited, and a known method can be employed. For example, a method in which particles of a metal complex (D) and a polymerization initiator are added to a solution in which a monomer is dissolved or dispersed, and the mixture is heated while stirring to cause polymerization to proceed on the particle surface.

  The gas absorbent formed by coating the particles of the metal complex (D) with the polymer (E) may be one in which each particle is coated with the polymer (E), or the coated particle is a polymer. A plurality of aggregates connected in (E) may be used, or the whole aggregate composed of a plurality of particles may be covered. The gas absorbent is provided, for example, as a particle having a particle size of nanometer order to several tens of μm or an aggregate thereof.

  The method for absorbing the gas using the gas absorbent of the present invention is not particularly limited, but it is a preferred embodiment to absorb the gas dissolved in the liquid. This is because even when used in a liquid, the practical benefit of using the gas absorbent of the present invention that the elution of the polyvalent metal (A) can be suppressed is great.

  The liquid is not particularly limited, but is preferably a coordination compound. The coordinating compound here means a compound capable of coordinating with the polyvalent metal (A), and includes an organic compound and water. Since the coordination compound easily exchanges ligands with the polyvalent carboxylic acid (B) in the metal complex (D), the network structure is broken and the polyvalent metal (A) component is easily eluted. In addition, the coordination compound is coordinated with the eluted polyvalent metal (A), so that stabilization by solvation occurs and elution is promoted. Therefore, the actual profit which uses the gas absorbent of this invention increases. Among them, a coordinating organic compound is preferable. On the other hand, since water is strongly absorbed in the metal complex, there is a possibility that the gas absorption performance may be easily lost or reused after that. Therefore, it is preferable that it is not water.

  Examples of the coordinating organic compound include alcohols such as methanol, ethanol, isopropanol, and tert-butanol; ketones such as acetone, methyl ethyl ketone, and diisopropyl ketone; carboxylates such as methyl formate, methyl acetate, ethyl acetate, and butyl acetate; ethylene Carbonates such as carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate; ethers such as diethyl ether, diisopropyl ether, dibutyl ether, 1,2-dimethoxyethane, anisole, tetrahydrofuran, 1,4-dioxolane; formic acid, acetic acid, propionic acid And the like. In addition, amide compounds such as formamide, acetamide, N, N-dimethylformamide and N, N-dimethylacetamide; nitrile compounds such as acetonitrile, propionitrile and benzonitrile; nitro compounds such as nitrobenzene, nitromethane and nitroethane; sulfolane, 3 -Sulfur oxides such as methylsulfolane and dimethyl sulfoxide; Phosphate esters and the like; Organic halides such as chloroform and methylene chloride; Alkenes such as 1-pentene and cyclopentene; Alkynes such as 1-hexyne; Benzene, toluene, xylene and the like The aromatic hydrocarbons are exemplified. The liquid may be a mixed liquid of two or more kinds.

  The gas to be absorbed using the gas absorbent is not particularly limited, and examples thereof include nitrogen, oxygen, carbon monoxide, carbon dioxide, methane, ethane, and the like. Among these, it is preferable to absorb at least one gas selected from carbon monoxide, carbon dioxide, methane, and ethane. This is because it is difficult to obtain sufficient absorption performance in conventional gas absorbents such as zeolite and activated carbon. More preferably, the gas is carbon monoxide or carbon dioxide. A plurality of gases may be absorbed.

  Although the pressure at the time of absorbing gas is not specifically limited, It is preferable that it is atmospheric pressure or more and 1 Mpa or less. If it is less than atmospheric pressure, it may be unfavorable from the viewpoint of gas absorption efficiency. More preferably, it is 0.11 MPa or more, More preferably, it is 0.15 MPa or more. On the other hand, if it exceeds 1 MPa, although the gas absorption efficiency increases, there is a possibility that it is not necessarily preferable from an economic point of view, such as a large apparatus. More preferably, it is 0.95 MPa or less, More preferably, it is 0.90 MPa or less. In addition, when absorbing gas dissolved in the liquid, it is desirable from the viewpoint of absorption efficiency that the gas is absorbed under the above-mentioned pressure conditions after once depressurizing and removing the gas dissolved in the liquid to some extent.

  Although the temperature which makes gas absorb is not specifically limited, It is preferable that it is -40-100 degreeC. When it is less than −40 ° C., it may not be preferable from the viewpoint of absorption efficiency. More preferably, it is -20 degreeC or more, More preferably, it is -10 degreeC or more. On the other hand, when it exceeds 100 ° C., the absorption efficiency is lowered and the network structure in the metal complex may not be maintained. More preferably, it is 90 degrees C or less, More preferably, it is 80 degrees C or less.

  The method for absorbing the gas in the liquid is not particularly limited as long as the gas absorbent can be brought into contact with the liquid containing the gas. For example, a method of dispersing a gas absorbent in a liquid, a method of circulating a liquid by filling a column, piping, a filter, etc. with a gas absorbent, a liquid fixed on a substrate fixed using an appropriate binder The method of making it contact is mentioned. When the gas absorbent is dispersed in the liquid, after absorbing the gas, the gas absorbent is separated by filter filtration or the like, if necessary.

  In a preferred embodiment, the gas absorbed by the gas absorbent inhibits the chemical reaction. This is because the chemical reaction can be performed using a liquid that does not contain a gas that inhibits the chemical reaction and that suppresses the elution of the polyvalent metal (A) component. Here, the gas that inhibits a chemical reaction refers to a gas that generates a side reaction product or significantly reduces the reaction rate.

  The chemical reaction is not particularly limited as long as the chemical reaction is inhibited by the gas dissolved in the liquid. For example, amination reaction, aromatization reaction, autothermal reforming, carbonylation reaction, decarbonylation reaction, reductive carbonylation reaction, carboxylation reaction, reductive carboxylation reaction, reductive coupling reaction, hydrogenation Decomposition reaction, cyclization reaction, cyclo-oligomerization reaction, epoxidation reaction, Fischer-Tropsch reaction, dehydration reaction, hydrogenation reaction, dehydrogenation reaction, hydrocarboxylation reaction, hydroformylation reaction, hydrogenolysis reaction, hydrometallation reaction , Hydrosilylation reaction, hydrolysis reaction, hydrotreating reaction, hydrodesulfurization / hydrodenitrogenation reaction (HDS / HDN), isomerization reaction, metathesis, telomerization, water gas conversion reaction (WGS), and reverse aqueous Gas conversion reaction (RWGS) etc. are mentioned.

  At this time, the chemical reaction is preferably a catalytic reaction. In the catalytic reaction, depending on the type of dissolved gas, problems such as reduced catalytic activity and side reaction products are likely to occur. Therefore, it is possible to sufficiently obtain the benefits of employing the above gas absorption method. It is. The catalytic reaction is not particularly limited as long as the catalytic reaction is inhibited by the gas dissolved in the liquid. As the catalyst, a transition metal or a compound thereof is often used. Examples of the catalytic reaction include a hydroformylation reaction using a rhodium compound as a catalyst, but are not particularly limited.

  Moreover, before making a chemical reaction, it is a preferable embodiment to absorb the gas which dissolves in the said liquid and inhibits a chemical reaction previously using the said gas absorbent. By absorbing such gas in advance, it becomes possible to remove the gas from the liquid sufficiently and efficiently, preventing side reactions and allowing the chemical reaction to proceed smoothly.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to these. The measuring method of infrared absorption spectrum and X-ray diffraction pattern, SEM observation method, measuring method of halogen content in the filtrate, and measuring method of elution rate of copper ions in the filtrate are as follows.

[Measurement method of infrared absorption spectrum]
An infrared absorption spectrum (diffuse reflection method) was measured using a Fourier transform infrared spectrophotometer “JIR-5500” manufactured by JEOL Ltd. with the measurement sample placed directly on the sample stage.

[Measurement method of X-ray diffraction pattern]
Wide angle X-ray diffraction was performed using a rotating anti-cathode X-ray diffractometer “RINT-2400” manufactured by Rigaku Corporation to obtain an X-ray diffraction pattern. Detailed measurement conditions are described below.
X-ray source: CuKα ray X-ray wavelength: λ = 1.5405４０
Output: 40 kV, 100 mA
Detector: Scintillation counter scanning speed: 1 ° / min Integration time: FT = 0 sec
Step size: 0.02 ° / step measurement range (2θ): 5-80 °
Measurement attachment: powder sample table

[SEM observation method of gas absorbent]
Using an ion sputtering apparatus, a sample was placed on a provided metal plate and coated with platinum to prepare a sample for SEM observation. A scanning electron microscope “S-4000” manufactured by Hitachi, Ltd. was used, SEM observation was performed with an acceleration voltage of 4 kV and a magnification of 25000 times, and photographs were taken.

[Measurement method of halogen content in filtrate]
The measurement sample was burned with a trace amount chlorine / sulfur analyzer “TOX-10Σ” manufactured by Mitsubishi Chemical, and the generated gas was absorbed into ion-exchanged water to prepare an analysis sample. Using an ion chromatograph “DX-120” manufactured by Dionex, the halogen content (ppm) in the filtrate was measured using an aqueous solution of sodium carbonate / sodium bicarbonate as an eluent.

[Measurement method of elution rate of copper ions in filtrate]
2 g of the filtrate was collected in a platinum crucible, and the ash obtained by evaporating to dryness and igniting at 600 ° C. was dissolved in hydrochloric acid and diluted with ion-exchanged water to prepare an analytical sample. The weight of the copper element was measured at an RF output of 1150 W using an ICP emission analyzer “IRIS AP” manufactured by Jarrel Ash. From this, the total weight Wa (g) of the copper element contained in the filtrate (60 g) was calculated. On the other hand, the total weight Wb (g) of the copper element contained in the gas absorbent before the test was calculated from the assumed composition of the gas absorbent. Using these values, the elution rate S (%) of copper ions into the filtrate was determined from the following formula (2).
S = (Wa / Wb) × 100 (%) (2)

Example 1
[Production method of gas absorbent]
(P-1)
In a three-necked flask having an internal volume of 500 mL equipped with a stirrer, a dropping funnel and a thermometer, 1.73 g of trimesic acid [carboxyl group amount (b): 24.7 mmol] and 0.44 g of polyacrylic acid having a weight average molecular weight of 250,000 [ Carboxyl group amount (c): 6.1 mmol] and methanol / water mixed solvent (volume ratio 1/2) 300 mL were charged and stirred. The obtained mixed solution was heated to 85 ° C. and stirred, and then 3.08 g of copper (II) acetate monohydrate [amount of salt of polyvalent metal (A) (a): 15. 4 mmol] of methanol / water mixed solvent (volume ratio 1/2) was added dropwise over 15 minutes. After completion of the dropping, the temperature inside the flask was kept at 85 ° C. and stirring was continued for 18 hours. The internal temperature of the reaction solution was cooled to 5 ° C., and the solid precipitated in the reaction system was filtered and washed with 20 mL of a methanol / water mixed solvent (volume ratio 1/2). It vacuum-dried for time, and obtained 2.22 g of metal complexes (D-1). For the metal complex (D-1), measurement of an infrared absorption spectrum, measurement of an X-ray diffraction pattern, and SEM observation were performed. Moreover, this metal complex (D-1) was used as the gas absorbent (P-1).

[Gas absorption, halogen content in filtrate, elution rate of copper ions in filtrate]
In a sealed container having a volume of 110 mL, 1.0 g of the gas absorbent (P-1) was dispersed in 60 g of propylene carbonate, and carbon monoxide gas was supplied into the container. After the supply is stopped when the internal pressure reaches 0.2 MPa, the amount of carbon monoxide gas absorbed in the dispersion (mL) from the pressure change until the pressure in the container decreases and becomes constant. ) Was calculated. The inside of the container was kept at 25 ° C. The amount of gas absorption was measured for carbon dioxide, methane and ethane gases in the same manner as described above. Thereafter, the dispersion was filtered, and the halogen content in the filtrate was measured. Further, the composition of the gas absorbent (P-1) is such that 1 mole of divalent copper reacts with 2 moles of carboxyl groups, and trimesic acid and polycarboxylic acid are mixed in the same ratio as the charging ratio (P-1). ), The elution rate of copper ions in the filtrate was determined. The results are shown in Table 1. Moreover, when the dispersion liquid in which carbon dioxide gas was absorbed was decompressed, it was confirmed that the entire amount of carbon dioxide gas was released. This suggests that the gas absorbent is reusable.

Example 2
[Production method of gas absorbent]
(P-2)
Disperse 1.0 g of the metal complex (D-1) obtained in Example 1 in 20 mL of a methanol-water mixed solvent (volume ratio 1: 2), purge the system with nitrogen, and heat to 85 ° C. with stirring. did. To this, 1.5 g of polyethylene glycol dimethacrylate having a molecular weight of 550 and 25 mg (0.1 mmol) of benzoyl peroxide were added and stirred at 85 ° C. for 30 minutes. The internal temperature of the reaction solution is cooled to 5 ° C., the solid in the system is filtered off, washed with 20 mL of a methanol / water mixed solvent (volume ratio 1/2), and vacuum dried at 150 ° C. for 2 hours to obtain 1.8 g of solid. Got. The solid was used as a gas absorbent (P-2).

[Gas absorption, halogen content in filtrate, elution rate of copper ions in filtrate]
The gas absorption amount and the halogen content in the filtrate were measured by the same method as in Example 1 except that 1.8 g of the gas absorbent (P-2) obtained by the above method was used. Assuming that 1.0 g of the metal complex (D-1) is coated with 0.8 g of polymer, the gas absorbent (P-2) has an elution rate of copper ions in the filtrate. Asked. The results are shown in Table 1. Moreover, when the dispersion liquid in which carbon dioxide gas was absorbed was decompressed, it was confirmed that the entire amount of carbon dioxide gas was released. This suggests that the gas absorbent is reusable.

Comparative Example 1
[Production method of gas absorbent]
(P-3)
In a three-necked flask with an internal volume of 500 mL equipped with a stirrer, a dropping funnel and a thermometer, 2.18 g of trimesic acid [carboxyl group amount (b): 31.1 mmol] and a methanol / water mixed solvent (volume ratio 1/2) 300 mL of a mixed solvent was charged and stirred. The obtained mixed solution was heated to 85 ° C. and stirred while the solution was mixed with 3.08 g of copper (II) acetate monohydrate [amount of salt of polyvalent metal (A) (a): 15.4 mmol. ] 150 mL of a methanol / water mixed solvent (volume ratio 1/2) was added dropwise over 15 minutes. After completion of the dropping, the temperature inside the flask was kept at 85 ° C. and stirring was continued for 18 hours. The internal temperature of the reaction solution was cooled to 5 ° C., and the solid precipitated in the reaction system was filtered and washed with 20 mL of a methanol / water mixed solvent (volume ratio 1/2). It vacuum-dried for the time, and 2.50g metal complex (D-3) was obtained. For the metal complex (D-3), measurement of an infrared absorption spectrum, measurement of an X-ray diffraction pattern, and SEM observation were performed. Moreover, this metal complex (D-3) was used as the gas absorbent (P-3).

[Gas absorption, halogen content in filtrate, elution rate of copper ions in filtrate]
The gas absorption amount and the halogen content in the filtrate were measured by the same method as in Example 1 except that the gas absorbent (P-3) obtained by the above method was used. The gas absorbent composition formula (P-3) on the assumption that _{Cu 3 {C 6 H 3 (} COO) 3} 2, was determined the elution of copper ions into the filtrate solution. The results are shown in Table 1. Moreover, when the dispersion liquid in which carbon dioxide gas was absorbed was decompressed, it was confirmed that the entire amount of carbon dioxide gas was released.

  The gas absorbent (P-1) (Example 1) which is a metal complex (D-1) obtained using polyacrylic acid is a gas which is a metal complex (D-3) which does not use polyacrylic acid. As compared with the case of the absorbent (P-3) (Comparative Example 1), it was found that the elution of copper ions is effectively suppressed while the absorption performance is almost the same in any gas. Moreover, it turned out that the elution of a copper ion is further suppressed by the gas absorbent (P-1) which coat | covered the surface of the particle | grains of the metal complex (D-1) obtained using polyacrylic acid. .

  Infrared absorption spectrum measurement results, X-ray diffraction pattern measurement results, and SEM observation results for the metal complex (D-1), metal complex (D-3), and other compounds described below will be described in detail below.

<Infrared absorption spectrum>
The measurement results of infrared absorption spectra of metal complex (D-1), metal complex (D-3), trimesic acid, polyacrylic acid, copper polyacrylate and copper (II) acetate monohydrate are shown in FIG. Shown in ~ 6. The copper (II) polyacrylate is a methanol / water mixed solution of polyacrylic acid having a molecular weight of 25000 (volume ratio 1/2), and a methanol / water mixed solution of copper acetate (II) and monohydrate ( The compound obtained by dripping the volume ratio 1/2) and drying the precipitated solid was used. In both the trimesic acid and polyacrylic acid spectra, an absorption peak (C = O stretching absorption) derived from a free carboxyl group was observed in the vicinity of 1700 cm- ¹ . On the other hand, in the spectra of copper (II) acrylate and copper (II) acetate monohydrate, absorption peaks derived from carboxyl groups (carboxyanions) coordinated to divalent copper (C = O) flexible absorbing) are near each 1550 cm ^-1, were observed at about 1600 cm ^-1. On the other hand, in the spectrum of the metal complex (D-1), whereas the absorption peak near 1700 cm ^-1 was hardly observed, an absorption peak was observed at around 1550 cm ^-1. Also in the spectrum of the metal complex (D-3), similarly to the metal complex (D-1), whereas the absorption peak near 1700 cm ^-1 was hardly observed, strong absorption peak around 1600 cm ^-1 It was observed. From these, it was suggested that most of the carboxyl groups of polyacrylic acid constituting the metal complex (D-1) are coordinated to divalent copper as a carboxy anion.

<X-ray diffraction pattern>
The measurement result of the X-ray-diffraction pattern of a metal complex (D-1) and a metal complex (D-3) is shown in FIG.7 and FIG.8. The main peak of the X-ray diffraction pattern of the metal complex (D-1) was at 11.52 ° (2θ), and the half width was determined to be 0.202 °. On the other hand, the main peak of the X-ray diffraction pattern of the metal complex (D-3) was at 11.62 ° (2θ), and the half width was determined to be 0.167 °. From this, it was found that the use of polyacrylic acid shifts the main peak to the narrow angle side and widens the half width. This suggests that the incorporation of polyacrylic acid into the network structure widens the interplanar spacing d of the crystal structure, loosens the lattice, and slightly disturbs the regularity of the crystal. The main interplanar spacing d of the crystal structures of the metal complex (D-1) and the metal complex (D-3) was determined to be 7.68 mm and 7.61 mm, respectively.

<SEM observation>
SEM observation photographs of the metal complexes (D-1) and (D-3) are shown in FIGS. 9 and 10, respectively. From this, it is suggested that the metal complex (D-1) has a crystal structure similarly to the metal complex (D-3).

It is an infrared absorption spectrum of a metal complex (D-1). It is an infrared absorption spectrum of a metal complex (D-3). It is an infrared absorption spectrum of trimesic acid. It is an infrared absorption spectrum of polyacrylic acid. It is an infrared absorption spectrum of poly (copper acrylate). It is an infrared absorption spectrum of copper (II) acetate monohydrate. It is an X-ray diffraction pattern of a metal complex (D-1). It is an X-ray-diffraction pattern of a metal complex (D-3). It is a SEM observation photograph of a metal complex (D-1). It is a SEM observation photograph of a metal complex (D-3).

Claims (20)

A gas absorbent comprising a metal complex (D) comprising a polyvalent metal (A), a polyvalent carboxylic acid (B) having a molecular weight of less than 500, and a polymer (C) having a carboxyl group having a molecular weight of 500 or more. The gas absorbent according to claim 1, wherein the polyvalent metal (A) is divalent copper. The gas absorbent according to claim 1 or 2, wherein the polyvalent carboxylic acid (B) is a carboxylic acid having a carboxyl group at the 1-position, 3-position and 5-position of the benzene ring. The gas absorbent according to any one of claims 1 to 3, wherein the polymer (C) is poly (meth) acrylic acid. In the infrared absorption spectrum of the metal complex (D), the absorbance of the absorption peak derived from the carboxyl group coordinated to the polyvalent metal (A) among the absorption peaks derived from the carboxyl group of the polymer (C) is The gas absorbent according to any one of claims 1 to 4, which has a larger absorbance than an absorption peak derived from a carboxyl group that is not coordinated to the polyvalent metal (A). The gas absorbent according to any one of claims 1 to 5, wherein the X-ray diffraction pattern of the metal complex (D) has a peak derived from a crystal structure. In the X-ray diffraction pattern of the metal complex (D), compared to the X-ray diffraction pattern of the metal complex consisting only of the same polyvalent metal (A) and the same polyvalent carboxylic acid (B), the peak of the main peak The gas absorbent according to claim 6, wherein the top is on the narrow angle side and the half width of the main peak is wide. The gas absorbent according to any one of claims 1 to 7, wherein the metal complex (D) particles are coated with a polymer (E). Characterized by reacting a salt of a polyvalent metal (A), a polyvalent carboxylic acid (B) having a molecular weight of less than 500, and a polymer (C) having a carboxyl group having a molecular weight of 500 or more to form a metal complex. A method for producing a gas absorbent. The method for producing a gas absorbent according to claim 9, wherein a salt of the polyvalent metal (A) is added to a solution in which the polyvalent carboxylic acid (B) and the polymer (C) are dissolved, and these are reacted. The method for producing a gas absorbent according to claim 9 or 10, wherein the reaction is carried out in a mixed solvent of alcohol and water. The molar ratio (b / c) between the carboxyl group amount (b) of the polyvalent carboxylic acid (B) and the carboxyl group amount (c) of the polymer (C) is 99.9 / 0.1 to 50/50. The manufacturing method of the gas absorbent in any one of Claims 9-11. When the valence of the polyvalent metal (A) is m, the total amount of carboxyl groups (b + c) of the polyvalent carboxylic acid (B) and the polymer (C) with respect to the amount (a) of the polyvalent metal (A). The manufacturing method of the gas absorbent according to any one of claims 9 to 12, wherein the molar ratio [(b + c) / a] satisfies the following formula (1).
0.2 m ≦ (b + c) / a ≦ 50 m (1) A gas absorption method comprising absorbing a gas dissolved in a liquid using the gas absorbent according to any one of claims 1 to 8. The gas absorption method according to claim 14, wherein the liquid is a coordinating organic compound. The gas absorption method according to claim 14 or 15, wherein at least one gas selected from the group consisting of carbon monoxide, carbon dioxide, methane and ethane is absorbed. The gas absorption method according to any one of claims 14 to 16, wherein the gas is absorbed at a pressure of from atmospheric pressure to 1 MPa and a temperature of from -40 to 100 ° C. The gas absorption method according to claim 14, wherein a gas that dissolves in the liquid and inhibits a chemical reaction is absorbed. The gas absorption method according to claim 18, wherein the chemical reaction is a catalytic reaction. The gas absorption method according to claim 18 or 19, wherein a gas that dissolves in the liquid and inhibits the chemical reaction is absorbed in advance before the chemical reaction is performed.