JP5292679B2 - Method for producing porous metal complex as hydrogen storage material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a porous metal complex in a manner capable of realizing a shortened reaction time and an increased yield. <P>SOLUTION: The method is one for producing a porous metal complex containing a three-dimensional porous skeletal structure of a metal complex provided with a central metal and organic ligands each having a heterocyclic skeleton and a carboxylate group and comprises preparing a salt of the organic ligand as a heterocyclic metal carboxylate, preparing a salt of the central metal as a second metal salt, and reacting the heterocyclic metal carboxylate with the second metal salt. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a method for producing a porous metal complex, a porous metal complex, an adsorbing material, a separating material, a gas adsorbing material, and a hydrogen adsorbing material.

  In recent years, development competition for solid polymer fuel cells to be installed in fuel cell vehicles has been actively developed. In order to put such a fuel cell vehicle into practical use, it is desired to develop an efficient hydrogen storage method using a hydrogen storage material that is low-cost, lightweight, and has a high storage density.

Thus, a hydrogen storage material using a porous organometallic complex having a skeleton structure in which a two-dimensional lattice structure composed of metal ions and organic ligands is three-dimensionally stacked as a unit motif has been proposed (Patent Document 1, Patent). It is attracting attention as a gas adsorbent such as methane, nitrogen and hydrogen. Among them, for example, an organometallic complex using a nitrogen-containing heterocyclic skeleton such as tetrazine and triazine as an organic ligand has been found to be suitable as a hydrogen storage material because of its improved affinity with hydrogen (patent) Reference 3, Non-Patent Document 1, Non-Patent Document 2).
JP 2001-348361 A US Patent Application Publication No. 2003/0004364 JP-A-2005-93181 M. Eddaoudi, H.Li, OMYaghi, “J.Am.Chem.Soc.” , 2000, No. 122, p. 1391-1397 NL Rosi et al., “Science”, 2003, No. 300, p. 1127-1129

  However, the heterocyclic carboxylic acid compound serving as the organic ligand has low solubility in the solvent used to obtain the organometallic complex, and the amount of solvent required increases. The amount that can be synthesized at one time is limited, and increasing the amount requires a large amount of solvent. In addition, the heterocyclic carboxylic acid compound has low reactivity with a metal salt, and a long reaction time is required to obtain an organometallic complex. Increasing the reaction temperature to shorten the reaction time increases the number of side reactions, which may reduce the yield of the target organometallic complex. In a compound in which the intermediate is unstable, the yield is more markedly reduced, and there is a problem in terms of cost and mass productivity.

This invention is made | formed in order to solve the said subject, The manufacturing method of the porous metal complex which concerns on this invention is equipped with a central metal and the organic ligand which has a heterocyclic skeleton and a carboxylate group. a method of manufacturing a porous metal complex containing three-dimensional porous skeletal structure of a metal complex, preparing a salt of an organic ligand as heterocyclic carboxylic acid metal salts, metal centers salts second a step of preparing a metal salt, wherein the step of reacting a heterocyclic carboxylic acid metal salt and the second metal salt, and, in the above reaction, 2 Zahaii possible bridging ligands are added to the central metal, The heterocyclic carboxylic acid metal salt has the following general formula (I)
(XOOC) n1-R- (COOX ′) n2 (I)
(Wherein R includes a heterocyclic ring, X and X ′ represent Na or K, n1 and n2 represent integers, and 1 ≦ n1 ≦ 8 and 0 ≦ n2 ≦ 8). Including a carboxylic acid derivative , the central metal is Cu or Rh, the heterocyclic carboxylic acid metal salt is a sodium salt or K salt of tetrazine dicarboxylic acid or thiophene dicarboxylic acid, and the bridging ligand is triethylenediamine. characterized in that there.

  The porous metal complex according to the present invention is obtained by the method for producing a porous metal complex according to the present invention.

  The adsorbent according to the present invention includes the porous metal complex according to the present invention.

  The separating material according to the present invention includes the porous metal complex according to the present invention.

  The gas adsorbent according to the present invention includes the porous metal complex according to the present invention.

  The hydrogen adsorbent according to the present invention includes the porous metal complex according to the present invention.

  According to the present invention, the heterocyclic carboxylic acid metal salt is more easily dissociated than the heterocyclic carboxylic acid and has a higher solubility, so that the amount of the required solvent is less than that of the conventional one, and the reaction time can be shortened. In addition, since the heterocyclic carboxylic acid metal salt is easily dissociated, the reactivity with the second metal salt is high, the reaction temperature can be lowered, the productivity per unit time can be expected to increase, and the production cost can be reduced. it can.

  According to the present invention, a porous metal complex can be obtained efficiently and inexpensively.

  According to the present invention, since the porous metal complex according to the present invention is used, an inexpensive adsorbent, separation material, gas adsorbent and hydrogen adsorbent can be obtained efficiently.

  Hereinafter, a method for producing a porous metal complex, a porous metal complex, an adsorbing material, a separating material, a gas adsorbing material, and a hydrogen adsorbing material according to embodiments of the present invention will be described.

1st embodiment The manufacturing method of the porous metal complex (porous cross-linked metal complex) which concerns on 1st embodiment of this invention is demonstrated. FIG. 1 is a schematic diagram showing a crystal structure 1 (hereinafter often referred to as a three-dimensional porous skeleton structure 1) as an example of a porous metal complex according to an embodiment of the present invention. This crystal structure 1 is a binuclear complex having two copper ions as a central metal 2, and a heterocyclic carboxylate ion composed of a substituent having a structure represented by R around the central metal 2 is used as an organic ligand. The coordination bond 3 is formed by coordination. Each heterocyclic carboxylate ion has two carboxylate groups and coordinates two copper ions in four lattices by coordinating to the central metal 2 copper ion via the two oxygen atoms of the carboxylate group. A lattice-like two-dimensional structure (heterocyclic carboxylic acid metal complex) M1 in which a ring (void) as a point is condensed is formed. This two-dimensional lattice structure M1 is laminated as a unit motif, that is, a basic repetitive pattern, and each two-dimensional lattice structure M1 is composed of a three-dimensional porous skeleton structure by crosslinking with triethylenediamine as a bridging ligand 4. A crosslinked metal complex is formed. The triethylenediamine that is the bridging ligand 4 is a bidentate ligand that is coordinated to the copper ion that is the central metal 2 by two coordination groups. In this structure, there is a gap GP1 defined by the central metal 2 and the coordination coupling portion 3, each gap row of the plurality of two-dimensional structures M1 is aligned in the c-axis direction, and a plurality of one-dimensional channels are formed. Forming.

  The two-dimensional lattice structure M1 of the three-dimensional porous skeleton structure 1 of the porous metal complex having such a structure is prepared by preparing a salt of an organic ligand as a heterocyclic carboxylic acid metal salt, Prepared as a second metal salt and produced by reacting a heterocyclic carboxylic acid metal salt and a second metal salt. By adding a bridging ligand capable of bidentate coordination to the central metal to the reaction liquid after reacting the heterocyclic carboxylic acid metal salt and the second metal salt, the bridging ligand 4 is complexed with the central metal 2. The two-dimensional structure M1 formed by the organic ligand having a ring skeleton and a carboxylate group is cross-linked to form a three-dimensional porous skeleton structure 1. In this reaction, the compound that becomes an organic ligand is easily dissociated by making it into a metal salt, and the solubility in the solvent is increased. Therefore, the amount of solvent required is smaller than in the conventional case, and the reaction time can be shortened. . Moreover, since the heterocyclic carboxylic acid metal salt and the second metal salt are easily dissociated, the reactivity is high, a reduction in the reaction temperature, an increase in productivity per unit time and a yield can be expected, and the production cost can be reduced.

  As an example, FIG. 2A shows a chemical reaction according to the first embodiment of the present invention, and FIG. 2B shows a chemical reaction in a conventional example. As shown in FIG. 2B, in the conventional example, a heterocyclic carboxylic acid is used as a compound that becomes an organic ligand, and is reacted with a metal salt that becomes a central metal in a solvent. In this reaction, since the dissociation constant of the heterocyclic carboxylic acid in the solvent is low and the solubility is low, the reaction completion time is long and the reaction yield is low. On the other hand, when a heterocyclic carboxylic acid metal salt is used as a compound that becomes an organic ligand as shown in FIG. 2 (a), this compound is readily soluble in a solvent and easily ionized to react. Advances. For this reason, the reaction is completed in a shorter time than the conventional example, and the reaction yield is higher than that of the conventional example.

  The heterocyclic carboxylic acid metal salt preferably contains an alkali metal or alkaline earth metal salt. When the heterocyclic carboxylic acid metal salt is an alkali metal or alkaline earth metal salt, the heterocyclic carboxylic acid metal salt is dissociated into a carboxylate group and a metal ion in a solvent as compared with deprotonation of the carboxylic acid. It's easy to do. For this reason, the heterocyclic carboxylic acid metal salt is more easily dissociated than the heterocyclic carboxylic acid and has a higher solubility, so that the amount of solvent required is smaller than that of the conventional one, and the reaction time can be shortened. In addition, since the heterocyclic carboxylic acid metal salt is easily dissociated, the reactivity with the second metal salt is high, the reaction temperature can be lowered, the productivity per unit time can be expected to increase, and the production cost can be reduced. it can.

Heterocyclic carboxylic acid metal salts have the following general formula (I)
(XOOC) n1-R- (COOX ′) n2 (I)
(However, R includes a heterocyclic ring, X represents a hydrogen atom, an alkali metal or an alkaline earth metal, X ′ represents an alkali metal or an alkaline earth metal which is the same as or different from X, and n1 and n2 represent integers. 1 ≦ n1 ≦ 8, 0 ≦ n2 ≦ 8)).

  In the above general formula (I), X preferably consists of Na (sodium) or K (potassium). When X is Na or K, a porous metal complex can be obtained efficiently and inexpensively as compared with the conventional case. R preferably contains an aryl group or an arylene group, and the aryl group and the arylene group may have a substituent. R preferably contains an element selected from an element group containing N, O, S, P, B, As, Si, Sb, and Hg in the ring skeleton.

のいずれか一つで表される構造を有する置換基を含むことが好ましい。一般式（II）〜（XXVII）において、カルボキシレート基は環のどの位置に結合していても良く、このカルボキシレート基の２つの酸素原子が中心金属に配位することにより二次元格子構造Ｍ１を形成する。また、異なる複素環カルボン酸有機配位子を用いることができるため、水素とのアフィニティや細孔の形、径を変化させた多孔性の架橋金属錯体を、従来に比べ、安価で高効率に製造することができる。 This R is represented by the following general formulas (II) to (XXVII)

It preferably contains a substituent having a structure represented by any one of the above. In the general formulas (II) to (XXVII), the carboxylate group may be bonded to any position of the ring, and the two oxygen atoms of the carboxylate group are coordinated to the central metal, whereby the two-dimensional lattice structure M1 Form. In addition, since different heterocyclic carboxylic acid organic ligands can be used, porous cross-linked metal complexes with changed affinity for hydrogen, pore shape, and diameter can be manufactured at lower cost and higher efficiency. Can be manufactured.

  The second metal salt preferably includes a metal selected from a metal group including a divalent to tetravalent metal. In particular, the second metal salt preferably includes a divalent metal. In this case, since the second metal salt is dissociated in the solvent and the metal is ionized, the reaction with the heterocyclic carboxylic acid metal salt is promoted. For this reason, compared with the past, reaction time can also be shortened, reaction temperature can be lowered, and yield can be increased. In addition, it is more preferable that this 2nd metal salt contains the metal selected from the metal group containing Cu, Zn, Mo, Ru, Cr, Ni, and Rh. Moreover, it is preferable that a 2nd metal salt contains the metal salt selected from the metal salt group containing nitrate, a sulfate, acetate, carbonate, and a formate.

  The preparation of the heterocyclic carboxylic acid metal salt includes dissolving the heterocyclic carboxylic acid metal salt in a first solvent to obtain a first solution, and the preparation of the second metal salt includes the second metal salt. The reaction includes dissolving the second solvent to obtain a second solution, and the reaction includes mixing the first and second solutions. By mixing the first and second solutions, the heterocyclic carboxylate ion generated by the dissociation of the heterocyclic carboxylic acid metal salt reacts with the metal ion generated by the dissociation of the second metal salt, and a two-dimensional lattice structure M1 is generated. Furthermore, by adding a bridging ligand, a crosslinking reaction by the two-dimensional lattice structure M1 and the bridging ligand proceeds, and a crosslinked metal complex having a three-dimensional porous skeleton structure is formed.

  Note that any one of the preparation of the heterocyclic carboxylic acid metal salt, the preparation of the second metal salt, and the reaction may include irradiating the first or second solution with ultrasonic waves. In this case, since the reaction between the heterocyclic carboxylic acid metal salt and the second metal salt or the reaction between the heterocyclic carboxylic acid metal salt and the bridging ligand is promoted, the reaction time is reduced as compared with the conventional case. The reaction temperature can be lowered and the reaction yield can be increased.

  One of the first and second solvents is selected from the solvent group comprising N, N′-dimethylformamide, N, N′-diethylformamide, water, alcohols, tetrahydrofuran, benzene, toluene, hexane, acetone and acetonitrile. It is preferable to contain a solvent. As the alcohol, for example, methanol, ethanol, propanol or the like can be used. These solvents dissolve the heterocyclic carboxylic acid metal salt and the second metal salt, but do not dissolve the target metal complex, so that the target product can be obtained efficiently. Among these, one of the first and second solvents preferably includes a solvent selected from a solvent group including N, N′-dimethylformamide, N, N′-diethylformamide, water, and alcohols. Further, the first and second solvents may be the same solvent.

  The porous metal complex preferably has a pH of 8 to 10 when dissolved in 1 [L] water at a rate of 500 [mg]. When the pH is in the range of 8 to 10, the heterocyclic carboxylic acid metal salt and the second metal salt are easily dissociated in the solvent, so that the solubility in the solvent is increased and the reaction is promoted. Further, in order to adjust the pH to 8 or less, a compound washing step is required, which causes high cost. On the other hand, when the pH is 10 or more, residual ions may adversely affect the performance of the adsorbent, separation material, and gas adsorbent using the porous metal complex.

  The reaction is carried out by dissolving sodium nitrate, sodium sulfate, sodium acetate, sodium carbonate, sodium formate, potassium nitrate, potassium sulfate having a concentration of 10-500 [ppm] when dissolved in 1 [L] water at a rate of 500 [mg]. Preferably, the method includes obtaining a metal salt as a by-product selected from the group of metal salts comprising potassium acetate, potassium carbonate and potassium formate. Since these by-products have a high reaction rate, the reaction between the heterocyclic carboxylic acid metal salt and the second metal salt is promoted. For this reason, it becomes possible to decrease the reaction time, decrease the reaction temperature, and increase the reaction yield.

  The porous metal complex produced by this method for producing a porous metal complex includes a central metal and an organic ligand having a carboxylate group, and the organic ligand is coordinated around the central metal. Each organic ligand has two carboxylate groups, and each carboxylate group is coordinated to a different central metal via two oxygen atoms, thereby forming a ring (void) having a central metal as a lattice point. A condensed lattice-like two-dimensional structure is formed. This two-dimensional lattice structure is laminated as a unit motif, that is, a basic repeating pattern, and each two-dimensional lattice structure is crosslinked with a bridging ligand to form a three-dimensional porous skeleton structure. A bridging ligand is a bidentate ligand that is coordinated to the central metal by two coordination groups. In this structure, each gap row of a plurality of two-dimensional structures is aligned in a row, so that a plurality of one-dimensional channels are formed.

  In this porous metal complex, a three-dimensional porous skeleton structure in which unit motifs of a two-dimensional lattice structure are stacked is a skeleton part that defines voids, and the pore diameter of each void is 0.3 to 2.0 [nm. ]. A gas or liquid molecule smaller than the pore diameter can be taken into the skeleton structure. This skeletal structure is strong because it is formed by a coordinate bond which is a relatively strong bond, and the skeletal structure is stably maintained even if gas or liquid molecules are removed. For this reason, it is possible to reversibly take in gas or liquid molecules. In addition, this porous metal complex contains the said by-product as a residue. When the by-product is included as a residue, it indicates that the starting materials are a heterocyclic carboxylic acid metal salt and a second metal salt.

  In the method for producing a porous metal complex (porous cross-linked metal complex) described above, the heterocyclic carboxylic acid metal salt and the second metal salt are easily dissociated and have high solubility. The reaction time can be shortened. Moreover, since the heterocyclic carboxylic acid metal salt and the second metal salt are easily dissociated, the reactivity is high, a reduction in the reaction temperature, an increase in productivity per unit time and a yield can be expected, and the production cost can be reduced. Thus, a porous metal complex can be obtained efficiently and inexpensively by this production method. Moreover, when an adsorbent, a separating material, a gas adsorbent and a hydrogen adsorbent are produced using the porous metal complex obtained by this production method, it can be obtained efficiently and inexpensively compared to the conventional case.

Second Embodiment Next, a method for producing a porous metal complex (porous crosslinked metal complex) according to a second embodiment of the present invention will be described. The method for producing a porous metal complex according to the present embodiment comprises preparing the three-dimensional porous skeleton structure 1 of the porous metal complex shown in FIG. 1 using the salt of the organic ligand as the heterocyclic carboxylic acid metal salt. The central metal 2 salt is prepared as the second metal salt, the heterocyclic carboxylic acid metal salt and the second metal salt are reacted, and in this reaction, a bridging ligand capable of bidentate coordination with the central metal is formed. By simultaneously adding the heterocyclic carboxylic acid metal salt and the second metal salt. In the present embodiment, a two-dimensional lattice structure M1 is obtained by adding a bridging ligand 4 capable of bidentate coordination to the central metal 2 during the reaction between the heterocyclic carboxylic acid metal salt and the second metal salt. At the same time, the bridging ligand 4 bridges the two-dimensional lattice structure M1 to form the three-dimensional porous skeleton structure 1. In this reaction, the compound that becomes the organic ligand is made into a metal salt, so that the compound is easily dissociated and the solubility in the solvent is increased. Can be shortened. Moreover, since the heterocyclic carboxylic acid metal salt and the second metal salt are easily dissociated, the reactivity is high, a reduction in the reaction temperature, an increase in productivity per unit time and a yield can be expected, and the production cost can be reduced.

  Further, conventionally, when the two-dimensional lattice structure M1 is cross-linked by the bridging ligand 4, the two-dimensional lattice structure M1 formed from a metal ion and an organic ligand is formed, and then the two-dimensional lattice structure is formed. In many cases, M1 is laminated three-dimensionally and a two-step synthesis method is used in which the bridging ligand 4 bonds the two-dimensional lattice structure M1. On the other hand, in the second embodiment, by adding a compound that becomes the bridging ligand 4 when the heterocyclic carboxylic acid metal salt and the second metal salt are reacted, simultaneously with the formation of the two-dimensional lattice structure M1. The two-dimensional lattice structures M1 can be connected by the bridging ligand 4. For this reason, the synthesis process can be shortened to one stage, productivity and yield per unit time can be expected, and the manufacturing cost can be reduced.

  Here, as an example of the second embodiment, FIG. 3A shows a chemical reaction according to the second embodiment, and FIG. 3B shows a chemical reaction in a conventional example. As shown in FIG. 3B, in the conventional example, a heterocyclic carboxylic acid is used as a compound that becomes an organic ligand, and is reacted with a metal salt that becomes a central metal in a solvent. In this reaction, since the dissociation constant of the heterocyclic carboxylic acid in the solvent is low and the solubility is low, the reaction completion time is long and the reaction yield is low. In addition, a heterocyclic carboxylic acid and a metal salt are reacted to form a metal complex having a two-dimensional lattice structure, and a compound serving as a bridging ligand is further added to the reaction solution to form a bridging metal complex. Take the synthesis method. On the other hand, as shown in FIG. 3 (a), when a heterocyclic carboxylic acid metal salt is used as a compound to be an organic ligand, this compound is readily soluble in a solvent and easily ionized. Since the reaction proceeds, the reaction is completed in a shorter time than the conventional example, and the reaction yield is higher than that of the conventional example. Further, since the heterocyclic carboxylic acid metal salt, the second metal salt, and the bridging ligand are reacted at the same time, the bridging reaction by the bridging ligand proceeds simultaneously with the formation of the metal complex composed of the two-dimensional lattice structure M1, and the bridging metal A complex is formed. In this way, the synthesis process can be shortened to one stage, productivity and yield per unit time can be expected, and manufacturing costs can be reduced.

  The heterocyclic carboxylic acid metal salt preferably contains an alkali metal or alkaline earth metal salt. When the heterocyclic carboxylic acid metal salt is an alkali metal or alkaline earth metal salt, the heterocyclic carboxylic acid metal salt is dissociated into a carboxylate group and a metal ion in a solvent as compared with deprotonation of the carboxylic acid. It's easy to do. For this reason, the heterocyclic carboxylic acid metal salt is more easily dissociated than the heterocyclic carboxylic acid and has a higher solubility, so that the amount of solvent required is smaller than that of the conventional one, and the reaction time can be shortened. In addition, since the heterocyclic carboxylic acid metal salt is easily dissociated, the reactivity with the second metal salt is high, the reaction temperature can be lowered, the productivity per unit time can be expected to increase, and the production cost can be reduced. it can.

Heterocyclic carboxylic acid metal salts have the following general formula (I)
(XOOC) n1-R- (COOX ′) n2 (I)
(However, R includes a heterocyclic ring, X represents a hydrogen atom, an alkali metal or an alkaline earth metal, X ′ represents an alkali metal or an alkaline earth metal which is the same as or different from X, and n1 and n2 represent integers. 1 ≦ n1 ≦ 8, 0 ≦ n2 ≦ 8)).

  In the above general formula (I), X preferably contains Na (sodium) or K (potassium). When X is Na or K, a porous metal complex can be obtained efficiently and inexpensively as compared with the conventional case. R preferably contains an aryl group or an arylene group, and the aryl group and the arylene group may have a substituent. R preferably contains an element selected from an element group containing N, O, S, P, B, As, Si, Sb, and Hg in the ring skeleton.

のいずれか一つで表される構造を有する置換基を含むことが好ましい。一般式（II）〜（XXVII）において、カルボキシレート基は環のどの位置に結合していても良く、このカルボキシレート基の２つの酸素原子が中心金属に配位することにより二次元格子構造を形成する。また、異なる複素環カルボン酸有機配位子を用いることができるため、水素とのアフィニティや細孔の形、径を変化させた複素環カルボン酸金属錯体を、従来に比べ、安価で高効率に製造することができる。 This R is represented by the following general formulas (II) to (XXVII)

It preferably contains a substituent having a structure represented by any one of the above. In the general formulas (II) to (XXVII), the carboxylate group may be bonded to any position of the ring, and the two oxygen atoms of the carboxylate group are coordinated to the central metal to form a two-dimensional lattice structure. Form. In addition, since different heterocyclic carboxylic acid organic ligands can be used, heterocyclic carboxylic acid metal complexes with different affinity for hydrogen, pore shape, and diameter can be used at lower cost and higher efficiency. Can be manufactured.

  The second metal salt preferably includes a metal selected from a metal group including a divalent to tetravalent metal. In particular, the second metal salt preferably includes a divalent metal. In this case, since the second metal salt is dissociated in the solvent and the metal is ionized, the reaction with the heterocyclic carboxylic acid metal salt is promoted. For this reason, compared with the past, reaction time can also be shortened, reaction temperature can be lowered, and yield can be increased. In addition, it is more preferable that this 2nd metal salt contains the metal selected from the metal group containing Cu, Zn, Mo, Ru, Cr, Ni, and Rh. Moreover, it is preferable that a 2nd metal salt contains the metal salt selected from the metal salt group containing nitrate, a sulfate, acetate, carbonate, and a formate.

  The preparation of the heterocyclic carboxylic acid metal salt includes dissolving the heterocyclic carboxylic acid metal salt in a first solvent to obtain a first solution, and the preparation of the second metal salt includes the second metal salt. The reaction includes dissolving the second solvent to obtain a second solution, and the reaction includes mixing the first and second solutions. The reaction also includes adding a bridging ligand capable of bidentate coordination to the second metal salt. By mixing the heterocyclic carboxylic acid metal salt and the second solution, the heterocyclic carboxylic acid ion generated by the dissociation of the heterocyclic carboxylic acid metal salt reacts with the metal ion generated by the dissociation of the second metal salt, A two-dimensional lattice structure M1 is formed. Further, by adding a bridging ligand at the same time in the reaction, the bridging reaction by the bridging ligand of the two-dimensional lattice structure M1 proceeds simultaneously with the formation of the two-dimensional lattice structure M1, and a crosslinked metal complex is formed. For this reason, the synthesis process can be shortened to one stage, productivity and yield per unit time can be expected, and the manufacturing cost can be reduced. The bridging ligand may be added at the stage of obtaining the first and second solutions.

  Note that any one of the preparation of the heterocyclic carboxylic acid metal salt, the preparation of the second metal salt, and the reaction may include irradiating the first or second solution with ultrasonic waves. In this case, since the reaction between the heterocyclic carboxylic acid metal salt and the second metal salt or the reaction between the heterocyclic carboxylic acid metal salt and the bridging ligand is promoted, the reaction time is reduced as compared with the conventional case. The reaction temperature can be lowered and the reaction yield can be increased.

  In addition, one of the first and second solvents is from a solvent group including N, N′-dimethylformamide, N, N′-diethylformamide, water, alcohols, tetrahydrofuran, benzene, toluene, hexane, acetone, and acetonitrile. It is preferred to include a selected solvent. As the alcohol, for example, methanol, ethanol, propanol or the like can be used. These solvents dissolve the heterocyclic carboxylic acid metal salt and the second metal salt, but do not dissolve the target metal complex, so that the target product can be obtained efficiently. Among these, one of the first and second solvents preferably includes a solvent selected from a solvent group including N, N′-dimethylformamide, N, N′-diethylformamide, water, and alcohols. Further, the first and second solvents may be the same solvent.

  The porous metal complex preferably has a pH of 8 to 10 when dissolved in 1 [L] water at a rate of 500 [mg]. When the pH is in the range of 8 to 10, the heterocyclic carboxylic acid metal salt and the second metal salt are easily dissociated in the solvent, so that the solubility in the solvent is increased and the reaction is promoted. Further, in order to adjust the pH to 8 or less, a compound washing step is required, which causes high cost. On the other hand, when the pH is 10 or more, residual ions may adversely affect the performance of the adsorbent, separation material, and gas adsorbent using the porous metal complex.

  The reaction is carried out by dissolving sodium nitrate, sodium sulfate, sodium acetate, sodium carbonate, sodium formate, potassium nitrate, potassium sulfate having a concentration of 10-500 [ppm] when dissolved in 1 [L] water at a rate of 500 [mg]. Preferably, the method includes a step of obtaining a metal salt as a by-product selected from a group of metal salts containing potassium acetate, potassium carbonate, and potassium formate. Since these by-products have a high reaction rate, the reaction between the heterocyclic carboxylic acid metal salt and the second metal salt is promoted. For this reason, it becomes possible to decrease the reaction time, decrease the reaction temperature, and increase the reaction yield.

  The porous metal complex produced by this method for producing a porous metal complex includes a central metal and an organic ligand having a carboxylate group, and the organic ligand is coordinated around the central metal. Each organic ligand has two carboxylate groups, and each carboxylate group is coordinated to a different central metal via two oxygen atoms, thereby forming a ring (void) having a central metal as a lattice point. A condensed lattice-like two-dimensional structure is formed. This two-dimensional lattice structure is laminated as a unit motif, that is, a basic repeating pattern, and each two-dimensional lattice structure is crosslinked with a bridging ligand to form a three-dimensional porous skeleton structure. A bridging ligand is a bidentate ligand that is coordinated to the central metal by two coordination groups. In this structure, each gap row of a plurality of two-dimensional structures is aligned in a row, so that a plurality of one-dimensional channels are formed.

  In this porous metal complex, a three-dimensional porous skeleton structure in which unit motifs of a two-dimensional lattice structure are stacked is a skeleton part that defines voids, and the pore diameter of each void is 0.3 to 2.0 [nm. ]. A gas or liquid molecule smaller than the pore diameter can be taken into the skeleton structure. This skeletal structure is strong because it is formed by a coordinate bond which is a relatively strong bond, and the skeletal structure is stably maintained even if gas or liquid molecules are removed. For this reason, it is possible to reversibly take in gas or liquid molecules. In addition, this porous metal complex contains the said by-product as a residue. When the by-product is included as a residue, it indicates that the starting materials are a heterocyclic carboxylic acid metal salt and a second metal salt.

  In the method for producing a porous metal complex (porous cross-linked metal complex) described above, the heterocyclic carboxylic acid metal salt and the second metal salt are easily dissociated and have high solubility. The reaction time can be shortened. Moreover, since the heterocyclic carboxylic acid metal salt and the second metal salt are easily dissociated, the reactivity is high, a reduction in the reaction temperature, an increase in productivity per unit time and a yield can be expected, and the production cost can be reduced. In addition, since the heterocyclic carboxylic acid metal salt, the second metal salt, and the bridging ligand are reacted at the same time, the crosslinking reaction with the bridging ligand proceeds simultaneously with the formation of the metal complex having a two-dimensional lattice structure. A crosslinked metal complex is formed. For this reason, the synthesis process can be shortened to one stage, productivity and yield per unit time can be expected, and the manufacturing cost can be reduced. Thus, a porous metal complex can be obtained efficiently and inexpensively by this production method. Moreover, when an adsorbent, a separating material, a gas adsorbent and a hydrogen adsorbent are produced using the porous metal complex obtained by this production method, it can be obtained efficiently and inexpensively compared to the conventional case.

  Hereinafter, although the manufacturing method of the porous metal complex which concerns on embodiment of this invention is demonstrated more concretely by Example 1- Example 8 and Comparative Example 1- Comparative Example 2, the scope of the present invention is limited to these. Is not to be done.

1. Preparation Example _{1 {Cu (OOC-C 2} N 4 -COO) -1 / 2C 6 H 12 N 2} Synthesis heterocyclic carboxylic acid derivatives of _n samples 1,2,4,5-tetrazine-3,6 -Disodium dicarboxylate, copper sulfate pentahydrate as the second metal salt, and triethylenediamine as the bridging ligand. First, a methanol solution containing copper sulfate pentahydrate 2.50 [g] was added to a methanol solution containing 2.14 [g] tetrazine dicarboxylate while filtering. After heating and stirring, a toluene solution containing 0.56 [g] of triethylenediamine was added to the resulting reaction mixture, and the mixture was further heated and stirred. The precipitated solid was collected by suction filtration and vacuum dried to obtain the desired product.

Example _{2 {Rh (OOC-C 2} N 4 -COO) -1 / 2C 6 H 12 N 2} as a synthetic heterocyclic carboxylic acid derivatives of _n 1,2,4,5 tetrazine-3,6-dicarboxylic acid Disodium, rhodium acetate dihydrate as the second metal salt, and triethylenediamine as the bridging ligand were used. First, a methanol solution containing rhodium acetate dihydrate 4.78 [g] was added to a methanol solution containing 2.14 [g] tetrazine dicarboxylate while filtering. After heating and stirring, a toluene solution containing 0.56 [g] of triethylenediamine was added to the resulting reaction mixture, and the mixture was further heated and stirred. The precipitated solid was collected by suction filtration and vacuum dried to obtain the desired product.

Example _{3 {Cu (OOC-C 2} N 4 -COO) -1 / 2C 6 H 12 N 2} as a synthetic heterocyclic carboxylic acid derivatives of _n 1,2,4,5 tetrazine-3,6-dicarboxylic acid Tetrazine dicarboxylate dipotassium synthesized by ion exchange of copper sulfate pentahydrate as the second metal salt and triethylenediamine as the bridging ligand were used. First, a methanol solution containing 2.50 [g] copper sulfate pentahydrate was added to a methanol solution containing 2.46 [g] tetrazine dicarboxylate while filtering. After heating and stirring, a toluene solution containing 0.56 [g] of triethylenediamine was added to the resulting reaction mixture, and the mixture was further heated and stirred. The precipitated solid was collected by suction filtration and vacuum dried to obtain the desired product.

Example _{4 {Cu (OOC-C 4} SH 2 -COO) -1 / 2C 6 H 12 N 2} n synthesized thiophene dicarboxylic acid by ion exchange of the synthetic heterocyclic carboxylic acid derivatives of 2,5-thiophene dicarboxylic acid Disodium was used as the second metal salt, copper sulfate pentahydrate, and triethylenediamine as the bridging ligand. First, a methanol solution containing copper sulfate pentahydrate 2.50 [g] was added to a methanol solution containing 2.16 [g] thiophene dicarboxylate while filtering. After heating and stirring, a toluene solution containing 0.56 [g] of triethylenediamine was added to the resulting reaction mixture, and the mixture was further heated and stirred. The precipitated solid was collected by suction filtration and vacuum dried to obtain the desired product.

Example _{5 {Cu (OOC-C 2} N 4 -COO) -1 / 2C 6 H 12 N 2} as a synthetic heterocyclic carboxylic acid derivatives of _n 1,2,4,5 tetrazine-3,6-dicarboxylic acid Disodium was used as the second metal salt, copper sulfate pentahydrate, and triethylenediamine as the bridging ligand. Tetrazine dicarboxylate disodium 2.14 [g], copper sulfate pentahydrate 2.50 [g] and triethylenediamine 0.56 [g] were dissolved in methanol, and the mixture was allowed to stand at room temperature after stirring. The precipitated solid was collected by suction filtration and vacuum dried to obtain the desired product.

Example _{6 {Rh (OOC-C 2} N 4 -COO) -1 / 2C 6 H 12 N 2} as a synthetic heterocyclic carboxylic acid derivatives of _n 1,2,4,5 tetrazine-3,6-dicarboxylic acid Disodium, rhodium acetate dihydrate as the second metal salt, and triethylenediamine as the bridging ligand were used. Disodium tetrazine dicarboxylate 2.14 [g], rhodium acetate dihydrate 2.39 [g], and triethylenediamine 0.56 [g] were dissolved in methanol, and the mixture was allowed to stand at room temperature after stirring. The precipitated solid was collected by suction filtration and vacuum dried to obtain the desired product.

Example _{7 {Cu (OOC-C 2} N 4 -COO) -1 / 2C 6 H 12 N 2} as a synthetic heterocyclic carboxylic acid derivatives of _n 1,2,4,5 tetrazine-3,6-dicarboxylic acid Tetrazine dicarboxylate dipotassium synthesized by ion exchange of copper sulfate pentahydrate as the second metal salt and triethylenediamine as the bridging ligand were used. Tetrazine dicarboxylate dipotassium 2.46 [g], copper sulfate pentahydrate 2.50 [g] and triethylenediamine 0.56 [g] were dissolved in methanol, and stirred and allowed to stand at room temperature. The precipitated solid was collected by suction filtration and vacuum dried to obtain the desired product.

Example _{8 {Cu (OOC-C 4} SH 2 -COO) -1 / 2C 6 H 12 N 2} n synthesized thiophene dicarboxylic acid by ion exchange of the synthetic heterocyclic carboxylic acid derivatives of 2,5-thiophene dicarboxylic acid Disodium was used as the second metal salt, copper sulfate pentahydrate, and triethylenediamine as the bridging ligand. Disodium thiophene dicarboxylate 2.16 [g], copper sulfate pentahydrate 2.50 [g] and triethylenediamine 0.56 [g] were dissolved in methanol, and the mixture was allowed to stand at room temperature after stirring. The precipitated solid was collected by suction filtration and vacuum dried to obtain the desired product.

Comparative Example _{1 {Cu (OOC-C 2} N 4 -COO) -1 / 2C 6 H 12 N 2} use 1,2,4,5-tetrazine-3,6-dicarboxylic as synthetic heterocyclic carboxylic acid _n It was. First, tetrazine dicarboxylic acid 0.58 [g] and copper sulfate pentahydrate 0.85 [g] were dissolved in absolute ethanol, and the reaction solution was heated and stirred at room temperature to 40 [° C.] for several days. An anhydrous toluene solution of triethylenediamine 0.19 [g] was added to the obtained reaction mixture, and the mixture was heated and stirred at 120 [° C.] for 3 [hour] using an autoclave. The obtained precipitate was filtered, washed with methanol, and dried under reduced pressure at 100 [° C.] to obtain the desired product.

With Comparative Example _{2 {Cu (OOC-C 4} SH 2 -COO) -1 / 2C 6 H 12 N 2} 2,5- thiophene dicarboxylic acid as a synthetic heterocyclic carboxylic acid _n. First, 0.59 [g] thiophene dicarboxylic acid and 0.85 [g] copper sulfate pentahydrate were dissolved in absolute ethanol, and the reaction solution was heated and stirred at room temperature to 40 [° C.] for several days. An anhydrous toluene solution of triethylenediamine 0.19 [g] was added to the obtained reaction mixture, and the mixture was heated and stirred at 120 [° C.] for 3 [hour] using an autoclave. The obtained precipitate was filtered, washed with methanol, and dried under reduced pressure at 100 [° C.] to obtain the desired product.

2. Measurement of gas storage capacity
The gas storage capacity was measured for the samples obtained in Example 1 and Example 2. The measurement method followed the hydrogen storage / release measurement test of JIS H7201. After weighing the sample and placing it in a pressure-resistant sample tube for measurement and evacuating it at 200 [° C.] for 3 [hours] to release the gas remaining in the sample tube and obtaining the origin where hydrogen is not occluded Measurements were made. The measurement temperature was 25 [° C.]. Thereafter, the pressure was reduced to atmospheric pressure, and the amount of hydrogen released was confirmed.

3. Confirmation of crystal structure To confirm the crystal structure of the synthesized sample, an X-ray diffractometer (MXP 18VAHF) manufactured by Max Science was used, and measurement was performed at a voltage of 40 [kV], a current of 300 [mA], and an X-ray wavelength of CuKα. .

4). Confirmation of composition The composition of the synthesized sample was confirmed by elemental analysis. The method described in JPI-5S-65-2004 was used for confirmation of carbon, hydrogen, and nitrogen, and inductively coupled plasma emission spectroscopy was used for confirmation of metal elements.

Table 1 shows the metal complexes, bridging ligands, heterocyclic carboxylic acid derivatives, second metal salts, reaction yields and reaction end times synthesized in Examples 1 to 8, Comparative Examples 1 and 2. Shown in Table 2 shows the hydrogen storage capacity and measurement pressure of the samples obtained in Example 1, Example 2, and Comparative Example 1.

  First, Example 1 to Example 4 and Comparative Example 1 to Comparative Example 2 in which a heterocyclic carboxylic acid derivative is reacted with a second metal salt and a cross-linking ligand is added to the reaction solution to react are considered. . In Comparative Example 1, tetrazine carboxylic acid, which is a heterocyclic carboxylic acid, is used as a carboxylic acid derivative and reacted with copper sulfate pentahydrate in anhydrous ethanol. In this reaction, since the dissociation constant of tetrazinecarboxylic acid with respect to the solvent was low and the solubility was low, the reaction completion time was long and the reaction yield was low as shown in Table 1. On the other hand, Example 1 uses disodium tetrazine carboxylate, which is a heterocyclic carboxylic acid metal salt. Since disodium tetrazinecarboxylate is readily soluble in a solvent, the reaction proceeds easily by ionization, and the reaction time is shortened. Further, in Comparative Example 1, in order to coordinate triethylenediamine serving as a bridging ligand to a copper ion as a central metal, a reaction product of tetrazinecarboxylic acid and copper sulfate pentahydrate is reacted with triethylenediamine. Furthermore, during the reaction, the reaction hardly proceeded unless the temperature and pressure were increased by an autoclave. In contrast, in Example 1, the reaction proceeded without using an autoclave, and triethylenediamine as a bridging ligand was coordinated to a copper ion as a central metal. Thus, in Example 1, the reaction was milder than in Comparative Example 1, and the reaction was completed in a short time, and the reaction yield was higher than that in Comparative Example 1.

  In FIG. 4, the relationship between the reaction rate and reaction yield in Example 1, Example 2, and Comparative Example 1 is shown. Here, the reaction rate indicates the reciprocal of the reaction time, and the reaction rate increases as it goes to the right. Comparing Example 1 and Comparative Example 1, as shown in Table 1, the reaction time of Example 1 was 8 hours, the reaction time of Comparative Example 1 was 339 hours, and the reaction rate of Example 1 was the same as that of Comparative Example 1. The reaction yield was 42.4 times (= 339 hours / 8 hours) and the reaction yield was 1.3 times. Thus, it was found that when a heterocyclic carboxylic acid metal salt was used as the heterocyclic carboxylic acid derivative, the reaction time was shorter than that of using the heterocyclic carboxylic acid, and the yield could be increased. .

  In both Example 2 using rhodium acetate as the second metal salt and Example 3 using dipotassium tetrazine dicarboxylate as the carboxylic acid derivative, the yield was higher than that in Comparative Example 1, and the carboxylic acid derivative As a result, the effect of using disodium tetrazinecarboxylate was observed. When the values obtained in Example 4 and Comparative Example 2 were compared, as shown in Table 1, the reaction time of Example 4 was 13 hours, the reaction time of Comparative Example 2 was 339 hours, and thiophene dicarboxylic acid as a carboxylic acid derivative. When dipotassium was used, the reaction time of Example 4 was 26.1 times (= 339 hours / 13 hours) and the yield was 1.3 times higher than that of Comparative Example 2. The effect by using dipotassium acid was seen. The hydrogen storage capacities in Example 1 and Example 2 at 10 [MPa] are 0.63 [wt%] and 0.66 [wt%], respectively, and 0.52 [wt%] of Comparative Example 1 ] Higher than.

  Next, Example 5 to Example 8 in which the heterocyclic carboxylic acid metal salt, the second metal salt, and the bridging ligand are reacted at the same time are considered. In Example 5, since disodium tetrazinecarboxylate is easily soluble in a solvent, the reaction proceeds easily by ionization. In Example 5, the reaction proceeded without using an autoclave. Further, tetrazine carboxylic acid, copper sulfate pentahydrate and triethylenediamine were reacted at the same time. In Example 1, the synthesis process was in two stages. However, in Example 5, the synthesis process could be shortened to one stage. As described above, in Example 5, the reaction was completed in a shorter time than in Example 1, and the reaction yield was higher than in Example 1.

  In FIG. 5, the relationship between the reaction rate and reaction yield in Example 5, Example 7, and Comparative Example 1 is shown. When Example 5 was compared with Comparative Example 1, the reaction rate of Example 5 was 67.8 times that of Comparative Example 1, and the reaction yield was 1.3 times. Moreover, when Example 7 and Comparative Example 1 were compared, the reaction rate of Example 7 was 42.4 times that of Comparative Example 1, and the reaction yield was 1.2 times. Thus, it was found that when the heterocyclic carboxylic acid metal salt, the second metal salt, and the bridging ligand were reacted at the same time, the reaction rate was further increased and the reaction yield was increased.

  Similar to Example 5, the reaction time was shorter in Example 6 in which the heterocyclic carboxylic acid derivative, the second metal salt, and the bridging ligand were reacted at the same time than in Example 2. Moreover, also in Example 7, reaction time became shorter than Example 3, and the reaction yield also became high. In Example 8, the reaction time was shorter than in Example 4. Comparing the values obtained in Example 8 and Comparative Example 2, when dipotassium thiophene dicarboxylate was used as the carboxylic acid derivative, Example 8 had a reaction time of 33.9 times that of Comparative Example 2, The yield was as high as 1.3 times, and an effect due to the use of dipotassium thiophene dicarboxylate was observed.

  From the results of Examples 1 to 8, Comparative Example 1 and Comparative Example 2, in the method for producing a porous metal complex according to the embodiment of the present invention, the heterocyclic carboxylic acid metal salt is compared with the heterocyclic carboxylic acid. It was found that the reaction time can be shortened and the yield can be increased as compared with the conventional method because it is easily dissociated in a solvent and has high solubility. It was also found that the reaction time can be further shortened and the yield can be increased by simultaneously reacting the heterocyclic carboxylic acid metal salt, the second metal salt, and the bridging ligand.

  Although the present embodiment has been described above, it should not be understood that the description and the drawings, which form part of the disclosure of the above embodiment, limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

It is a schematic diagram which shows the three-dimensional structure of a porous metal complex. (A) It is a figure which shows an example of the chemical reaction which concerns on 1st embodiment of this invention. (B) It is a figure which shows the chemical reaction in a prior art example. (A) It is a figure which shows an example of the chemical reaction which concerns on 2nd embodiment of this invention. (B) It is a figure which shows the chemical reaction in a prior art example. It is a graph which shows the relationship between the reaction rate and reaction yield in Example 1, Example 2, and Comparative Example 1. It is a graph which shows the relationship between the reaction rate and reaction yield in Example 5, Example 7, and Comparative Example 1.

Explanation of symbols

1 Three-dimensional porous skeleton structure 2 Central metal 3 Coordination bond 4 Bridged ligand M1 Two-dimensional lattice structure

Claims (9)

A method for producing a porous metal complex which is a hydrogen storage material comprising a three-dimensional porous skeleton structure of a metal complex comprising a central metal and an organic ligand having a heterocyclic skeleton and a carboxylate group,
Preparing a salt of the organic ligand as a heterocyclic carboxylic acid metal salt ;
Preparing the salt of the central metal as a second metal salt ;
Anda step of reacting said heterocyclic carboxylic acid metal salt and the second metal salt,
The heterocyclic carboxylic acid metal salt has the following general formula (I)
(XOOC) n1-R- (COOX ′) n2 (I)
(Wherein R includes a heterocyclic ring, X and X ′ represent Na or K, n1 and n2 represent integers, and 1 ≦ n1 ≦ 8 and 0 ≦ n2 ≦ 8). Including carboxylic acid derivatives ,
In the reaction, a bridging ligand capable of bidentate coordination is added to the central metal,
The central metal is Cu or Rh;
The heterocyclic carboxylic acid metal salt is tetrazine dicarboxylic acid or thiophene dicarboxylic acid Na salt or K salt;
The method for producing a porous metal complex which is a hydrogen storage material, wherein the bridging ligand is triethylenediamine . In the reaction, the method for producing a porous metal complex is a hydrogen storage material of claim 1, wherein the addition of the crosslinking ligands simultaneously. The second metal salt, nitrate, hydrogen according to claim 1 or claim 2, characterized in that it comprises a metal salt selected from metal salts group include sulfate, acetate, carbonate and formate A method for producing a porous metal complex which is an occlusion material. The preparation of the heterocyclic carboxylic acid metal salt includes dissolving the heterocyclic carboxylic acid metal salt in a first solvent to obtain a first solution,
The preparation of the second metal salt includes dissolving the second metal salt in a second solvent to obtain a second solution;
The method for producing a porous metal complex as a hydrogen storage material according to claim 1, wherein the reaction includes mixing the first and second solutions. One of the first and second solvents is selected from a solvent group comprising N, N′-dimethylformamide, N, N′-diethylformamide, water, alcohols, tetrahydrofuran, benzene, toluene, hexane, acetone and acetonitrile. The manufacturing method of the porous metal complex which is the hydrogen storage material of Claim 4 characterized by the above-mentioned. The one of the first and second solvents includes a solvent selected from a solvent group including N, N′-dimethylformamide, N, N′-diethylformamide, water, and alcohols. 6. A method for producing a porous metal complex which is the hydrogen storage material according to 5 . Any one of the preparation of the heterocyclic carboxylic acid metal salt, the preparation of the second metal salt, and the reaction includes irradiating the first or second solution with ultrasonic waves. The manufacturing method of the porous metal complex which is a hydrogen storage material as described in any one of Claims 4 thru | or 6 . Wherein the porous metal complex is 1 to any one of claims 1 to 7, characterized in that it has a pH of 8-10 when dissolved in a ratio of 500 [mg] of water [L] The manufacturing method of the porous metal complex which is a hydrogen storage material of description. The reaction includes sodium nitrate, sodium sulfate, sodium acetate, sodium carbonate, sodium formate, potassium nitrate, sulfuric acid having a concentration of 10-500 [ppm] when dissolved in 1 [L] water at a rate of 500 [mg]. potassium, potassium acetate, selected from a metal salt group containing potassium carbonate and potassium formate, according to any one of claims 1 to 8, characterized in that it comprises obtaining a metal salt as a by-product A method for producing a porous metal complex which is a hydrogen storage material.

Images