Methods for separating metal ions

Abstract

This invention provides a method for separating metal ions that can selectively separate specific metal ions from a liquid containing multiple types of metal ions. [Solution] A method for separating metal ions, comprising the steps of: preparing a liquid containing multiple types of metal ions and a nitrogen-containing cyclic compound containing a 12-membered ring to an 18-membered ring containing two or more nitrogen atoms; and reacting the nitrogen-containing cyclic compound with a first metal ion contained in the liquid to form a first metal complex.

Description

Technical Field

[0001] The present disclosure relates to a method for separating metal ions.

Background Art

[0002] Lithium-ion batteries (LIBs) contain a large number of precious metals such as nickel, cobalt, and manganese, and the metal content of discarded LIBs is much higher than that in ores. Therefore, the recycling value of these metals is very high, and it is of great significance in solving resource shortages.

[0003] For example, after discharging used lithium-ion secondary batteries, methods for recovering valuable metals such as nickel, cobalt, and manganese from the positive electrode in lithium-ion secondary batteries have been studied (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005]

[0006]

[0007] In the above-mentioned Patent Document 1, it is described that a member containing valuable metals such as the positive electrode is taken out from the used battery after discharging, and black mass is obtained by heat treatment, pulverization, etc. of the member, and after acid-dissolving the black mass, solvent extraction is performed using an extractant to separate valuable metals. However, in the method as described above, many types of metals contained in the positive electrode and the like are included in the solution. Therefore, there is a problem that it is difficult to selectively separate metal ions from a solution with a complex composition by an efficient and environmentally friendly method.This disclosure is made in view of the above, and aims to provide a method for separating metal ions that can selectively separate specific metal ions from a liquid containing multiple types of metal ions. [Means for solving the problem]

[0008] <1> A step of preparing a liquid containing multiple types of metal ions and nitrogen-containing cyclic compounds containing 12-membered to 18-membered rings with two or more nitrogen atoms, A step of reacting the nitrogen-containing cyclic compound with a first metal ion contained in the liquid to form a first metal complex, A method for separating metal ions containing [a specific substance]. <2> The first metal complex comprises the first metal ion, an anion, and the nitrogen-containing cyclic compound. <1> The method for separating metal ions as described in [reference]. <3> The aforementioned multiple types of metal ions are transition metal ions. <1> or <2> The method for separating metal ions as described in [reference]. <4> The nitrogen-containing cyclic compound is a compound represented by the following general formula (1). <1> ~ <3> A method for separating metal ions as described in any one of the following.

[0009] [ka]

[0010] In general formula (1), R1 to R4 each independently have 2 to 4 atoms forming a ring structure represented by general formula (1), and the atoms are linking groups consisting of 2 to 4 carbon atoms and 0 or 1 nitrogen, oxygen, or sulfur atom (however, the total number of carbon atoms and nitrogen, oxygen, or sulfur atoms is 2 to 4), the carbon atoms forming the ring structure in R1 may form a 5-membered ring or a 6-membered ring together with at least one of the carbon atoms forming the ring structure in R2 and the carbon atoms forming the ring structure in R4, and the carbon atoms forming the ring structure in R3 may form a 5-membered ring together with the carbon atoms forming the ring structure in R2 and R4 R5 to R8 may each independently be a hydrogen atom or a monovalent substituent, and each comprises only one of the dotted bond between R1 and the nitrogen atom and the dotted bond between R5 and the nitrogen atom, and each comprises only one of the dotted bond between R2 and the nitrogen atom and the dotted bond between R6 and the nitrogen atom, and each comprises only one of the dotted bond between R3 and the nitrogen atom and the dotted bond between R7 and the nitrogen atom, and each comprises only one of the dotted bond between R4 and the nitrogen atom and the dotted bond between R8 and the nitrogen atom. <5> The nitrogen-containing cyclic compound is a compound represented by the following general formula (1-A) or a compound represented by the general formula (1-B). <1> ~ <4> A method for separating metal ions as described in any one of the following.

[0011] [ka]

[0012] In general formulas (1-A) and (1-B), R1 to R4 each independently have 2 to 4 atoms forming a ring structure represented by general formula (1-A) or general formula (1-B), and the atoms are linking groups consisting of 2 to 4 carbon atoms and 0 or 1 nitrogen, oxygen, or sulfur atom (where the total of carbon atoms and nitrogen, oxygen, or sulfur atoms is 2 to 4). The carbon atoms forming the ring structure in R1 may form a 5-membered ring or a 6-membered ring together with at least one of the carbon atoms forming the ring structure in R2 and the carbon atoms forming the ring structure in R4, and the carbon atoms forming the ring structure in R3 may form a 5-membered ring or a 6-membered ring together with at least one of the carbon atoms forming the ring structure in R2 and the carbon atoms forming the ring structure in R4. <6> The nitrogen-containing cyclic compound is at least one selected from the group consisting of compounds represented by the following general formulas: (1-1), (1-2), (1-3), (1-4), (1-5), (1-6), and (1-7). <1> ~ <5> A method for separating metal ions as described in any one of the following.

[0013] [ka]

[0014] [ka]

[0015] In general formula (1-1), R 11 ~R 16 Each of these independently represents a substituent, and each of n independently represents a value from 0 to 2. In general formula (1-2), R 21 ~R 24 Each of these independently represents a substituent, and each of n independently represents a value from 0 to 2. In general formula (1-3), R 31 ~R 34each independently represents a substituent, n each independently represents 0 to 4, In general formula (1-4), R 41 ~R 46 each independently represents a substituent, n each independently represents 0 to 2, R 47 and R 48 represent *-CR1R2-* (where R1 and R2 are each independently a hydrogen atom or a monovalent substituent, and * represents the bonding position), *-NR3-* (where R3 is a hydrogen atom or a monovalent substituent, and * represents the bonding position), a sulfur atom, an oxygen atom, or a carbonyl group, In general formula (1-5), R 51 ~R 56 each independently represents a substituent, n each independently represents 0 to 2, R 57 and R 58 are each independently a hydrogen atom or a monovalent substituent, In general formula (1-6), R 61 ~R 64 each independently represents a substituent, n each independently represents 0 to 3, R 65 and R 66 represent *-CR4R5-* (where R4 and R5 are each independently a hydrogen atom or a monovalent substituent, and * represents the bonding position), *-NR6-* (where R6 is a hydrogen atom or a monovalent substituent, and * represents the bonding position), a sulfur atom, an oxygen atom, or a carbonyl group, In general formula (1-7), R 71 ~R 74 each independently represents a substituent, n each independently represents 0 to 3, R 75 and R 76 each independently represents *-CR7-* (where R7 is a hydrogen atom or a monovalent substituent, and * represents the bonding position) or a nitrogen atom. <7> In the step of forming the first metal complex, the method for separating metal ions according to any one of <1> to <6> in which the liquid is heated. <8> In the step of forming the first metal complex, the method for separating metal ions according to <7> in which the liquid is irradiated with microwaves and heated, or the liquid is heated in a bead bath. <9> The process involves recovering the first metal complex, The process further includes a step of reacting a second metal ion contained in the liquid from which the first metal complex was recovered with the nitrogen-containing cyclic compound to form a second metal complex. <1> ~ <8> A method for separating metal ions as described in any one of the following. [Effects of the Invention]

[0016] This disclosure provides a method for separating metal ions that can selectively separate specific metal ions from a liquid containing multiple types of metal ions. [Brief explanation of the drawing]

[0017] [Figure 1] These are the XRD pattern measurement results for precipitate 1, cobalt complex, manganese complex, and H2HAM. [Figure 2] These are the XRD pattern measurement results for precipitate 3, cobalt complex, nickel complex, manganese complex, and H2HAM. [Modes for carrying out the invention]

[0018] In this disclosure, the term "process" includes not only processes that are independent of other processes, but also processes that cannot be clearly distinguished from other processes, provided that the purpose of such process is achieved. In this disclosure, the numerical range indicated using "~" includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages within this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in numerical ranges described within this disclosure, the upper or lower limit of that range may be replaced with the values ​​shown in the examples. In this disclosure, each component may contain multiple types of the corresponding substance. If multiple types of the substance corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple types of substances present in the composition, unless otherwise specified.

[0019] [Method for separating metal ions] The present disclosure is a method for separating metal ions, comprising the steps of: preparing a liquid containing multiple types of metal ions and a nitrogen-containing cyclic compound containing a 12-membered ring to an 18-membered ring containing two or more nitrogen atoms; and reacting the nitrogen-containing cyclic compound with a first metal ion contained in the liquid to form a first metal complex.

[0020] In the separation method of this disclosure, a nitrogen-containing cyclic compound is reacted with a first metal ion (a specific metal ion) contained in a liquid containing multiple types of metal ions and the aforementioned nitrogen-containing cyclic compound. As a result, the nitrogen-containing cyclic compound and the first metal ion react to form a first metal complex. For example, the first metal complex has low solubility and therefore forms a precipitate in the liquid, which can be separated or recovered. Furthermore, even when multiple metal ions are contained in the liquid, a precipitate containing the first metal complex, which is a complex of a specific metal ion, can be obtained with high purity. This makes it possible to selectively separate a specific metal ion from a liquid containing multiple types of metal ions.

[0021] Multiple types of metal ions may be two or more types of metal ions, or they may be three or four or more types of metal ions. Multiple types of metal ions may be transition metal ions.

[0022] Transition metals are metallic elements that lie between Group 3 and Group 12 of the periodic table. Examples of transition metals include titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, and silver.

[0023] The multiple types of metal ions may be nickel ions, cobalt ions, and manganese ions, or nickel ions and cobalt ions, nickel ions and manganese ions, or cobalt ions and manganese ions.

[0024] The first metal complex may contain a first metal ion, an anion, and a nitrogen-containing cyclic compound. The first metal complex may have the first metal ion coordinated within the ring structure of the nitrogen-containing cyclic compound. In this disclosure, the chemical structures of the first metal complex, the second metal complex described later, and the metal complex m can be confirmed by single-crystal X-ray structural analysis.

[0025] The aforementioned anions are not particularly limited, but include trifluoromethanesulfonate ion (CF3SO3 ー ), bis(trifluoromethanesulfonyl)amide anion (TFSA), tetrafluoroborate (BF4 ー ), hexafluorophosphate (PF6 ー ), hexafluoroantimonate (SbF6 ー ), perchlorate ion (ClO4 ー ), fluorosulfonate ion (FSO3 ー ), chloride ions (Cl - ), bromide ions (Br - ), iodide ion (I - ), nitrate ion (NO3 - ), sulfate ions (SO4 - Examples include:

[0026] In a liquid containing multiple types of metal ions and nitrogen-containing cyclic compounds, there may be one or more anions present. For example, the anion may be trifluoromethanesulfonate ion (CF3SO3 ー ) or bis(trifluoromethanesulfonyl)amide anion (TFSA) may also be used.

[0027] The nitrogen-containing cyclic compound may be a nitrogen-containing cyclic compound containing a 12-membered ring to an 18-membered ring containing two or more nitrogen atoms, or a nitrogen-containing cyclic compound containing a 12-membered ring to an 18-membered ring containing four to eight nitrogen atoms. The nitrogen-containing cyclic compound may also be a 14-membered ring or a 16-membered ring. The 12-membered to 18-membered rings in nitrogen-containing cyclic compounds may be formed by carbon atoms and nitrogen atoms, or by carbon atoms, nitrogen atoms and other atoms (e.g., sulfur atoms, oxygen atoms, etc.).

[0028] The nitrogen-containing cyclic compound may also be a compound represented by the following general formula (1).

[0029] [ka]

[0030] In general formula (1), R1 to R4 each independently have 2 to 4 atoms forming a ring structure represented by general formula (1), and the atoms are linking groups consisting of 2 to 4 carbon atoms and 0 or 1 nitrogen, oxygen, or sulfur atom (however, the total number of carbon atoms and nitrogen, oxygen, or sulfur atoms is 2 to 4), the carbon atoms forming the ring structure in R1 may form a 5-membered ring or a 6-membered ring together with at least one of the carbon atoms forming the ring structure in R2 and the carbon atoms forming the ring structure in R4, and the carbon atoms forming the ring structure in R3 may form a 5-membered ring together with the carbon atoms forming the ring structure in R2 and R4 R5 to R8 may each independently be a hydrogen atom or a monovalent substituent, and each comprises only one of the dotted bond between R1 and the nitrogen atom and the dotted bond between R5 and the nitrogen atom, and each comprises only one of the dotted bond between R2 and the nitrogen atom and the dotted bond between R6 and the nitrogen atom, and each comprises only one of the dotted bond between R3 and the nitrogen atom and the dotted bond between R7 and the nitrogen atom, and each comprises only one of the dotted bond between R4 and the nitrogen atom and the dotted bond between R8 and the nitrogen atom.

[0031] In general formula (1), for example, a compound having a bond represented by a dotted line between R1 and a nitrogen atom is a compound represented by the following general formula (1'), where R 5 It does not exist. On the other hand, in general formula (1), for example, a compound having a bond represented by the dotted line between R5 and the nitrogen atom is a compound represented by the following general formula (1"), and R 1 The bond between and N is a single bond.

[0032] [ka]

[0033] In other words, the two dotted lines connecting to the nitrogen atom in general formula (1) represent, independently, the existence of only one of them. Similarly, for R2 and R6 and the nitrogen atom, R3 and R7 and the nitrogen atom, and R4 and R8 and the nitrogen atom, independently, only one of either a double bond or a substituent exists that connects to the nitrogen atom. Therefore, for the four nitrogen atoms shown in general formula (1), the number of double bonds formed by each nitrogen atom is between 0 and 4, and the number of substituents attached to each nitrogen atom (the actual number of R5 to R8) is between 0 and 4, so the sum of the number of double bonds and substituents is 4.

[0034] The nitrogen-containing cyclic compound may be a compound represented by the general formula (1-A) or the general formula (1-B) shown below. Metal ions are more likely to coordinate within the ring structure of the compound represented by general formula (1-A) or the general formula (1-B). Furthermore, compounds represented by general formula (1-A) or general formula (1-B) are equivalent to forms that the compound represented by general formula (1) can take.

[0035] [ka]

[0036] In general formulas (1-A) and (1-B), R1 to R4 each independently have 2 to 4 atoms forming a ring structure represented by general formula (1-A) or general formula (1-B), and the atoms are linking groups consisting of 2 to 4 carbon atoms and 0 or 1 nitrogen, oxygen, or sulfur atom (where the total of carbon atoms and nitrogen, oxygen, or sulfur atoms is 2 to 4). The carbon atoms forming the ring structure in R1 may form a 5-membered ring or a 6-membered ring together with at least one of the carbon atoms forming the ring structure in R2 and the carbon atoms forming the ring structure in R4, and the carbon atoms forming the ring structure in R3 may form a 5-membered ring or a 6-membered ring together with at least one of the carbon atoms forming the ring structure in R2 and the carbon atoms forming the ring structure in R4.

[0037] In general formulas (1-A) and (1-B), R1 to R4 may each independently form a ring structure represented by general formula (1-A) or general formula (1-B) with 2 or 3 atoms, and these atoms may be 2 or 3 carbon atoms, or 0 or 1 nitrogen or sulfur atom (provided that the total number of carbon atoms and nitrogen or sulfur atoms is 2 or 3). The aforementioned linking group may include carbon atoms constituting a carbonyl group as carbon atoms forming the ring structure.

[0038] The nitrogen-containing cyclic compound may be at least one selected from the group consisting of compounds represented by the following general formulas: (1-1), (1-2), (1-3), (1-4), (1-5), (1-6), and (1-7). Metal ions are more likely to coordinate within the ring structure of the compounds represented by the aforementioned general formulas (1-1) to (1-7).

[0039] [ka]

[0040] [ka]

[0041] In general formula (1-1), R 11 ~R 16 Each of these independently represents a substituent, and each of n independently represents a value from 0 to 2. In general formula (1-2), R 21 ~R 24 Each of these independently represents a substituent, and each of n independently represents a value from 0 to 2. In general formula (1-3), R 31 ~R 34 Each of these independently represents a substituent, and each of n independently represents a value from 0 to 4. In general formula (1-4), R 41 ~R 46 Each of these independently represents a substituent, and each of these independently represents 0 to 2, R 47 and R 48 *-CR1R2-* (where R1 and R2 are independently hydrogen atoms or monovalent substituents, and * represents the bond position), *-NR3-* (where R3 is a hydrogen atom or monovalent substituent, and * represents the bond position), sulfur atom, oxygen atom, or carbonyl group. In general formula (1-5), R 51 ~R 56 Each of these independently represents a substituent, and each of these independently represents 0 to 2, R 57 and R 58 Each of these is independently a hydrogen atom or a monovalent substituent. In general formula (1-6), R 61 ~R 64 Each of these independently represents a substituent, and each of these independently represents 0 to 3, R 65 and R 66 *-CR4R5-* (where R4 and R5 are independently hydrogen atoms or monovalent substituents, and * represents the bond position), *-NR6-* (where R6 is a hydrogen atom or monovalent substituent, and * represents the bond position), sulfur atom, oxygen atom, or carbonyl group. In general formula (1-7), R 71 ~R 74Each of these independently represents a substituent, and each of these independently represents 0 to 3, R 75 and R 76 Each of these independently represents either *-CR7-* (where R7 is a hydrogen atom or a monovalent substituent, and * indicates a bond position) or a nitrogen atom.

[0042] In general formulas (1-1) to (1-7), the substituents can be any alkyl group, aryl group, halogen atom, nitro group, cyano group, carbonyl group, hydroxyl group, alkoxy group, etc.

[0043] In general formulas (1-4) to (1-7), R 47 and R 48 , R 57 and R 58 , R 65 and R 66 , and R 75 and R 76 Examples of monovalent substituents in this compound include, independently, alkyl groups, aryl groups, halogen atoms, nitro groups, cyano groups, carbonyl groups, hydroxyl groups, and alkoxy groups.

[0044] In general formulas (1-1), (1-2), (1-4), and (1-5), n may be independently 0 or 1. In general formulas (1-3), (1-6), and (1-7), n may be independently 0 to 2, or 0 or 1.

[0045] The method for separating metal ions according to this disclosure includes the step of preparing a liquid containing multiple types of metal ions and a nitrogen-containing cyclic compound containing a 12-membered to 18-membered ring with two or more nitrogen atoms. For example, the aforementioned nitrogen-containing cyclic compound may be added to the liquid containing multiple types of metal ions.

[0046] A liquid containing multiple types of metal ions may be a solution in which multiple types of metal ions are dissolved in a solvent, or a solution in which multiple metal compounds are dissolved in a solvent. The solvent may be ethylene glycol, propylene glycol, or the like, due to its high boiling point. The metal compound may be a compound containing the aforementioned metal ions and anions.

[0047] In a liquid containing multiple types of metal ions and the aforementioned nitrogen-containing cyclic compound, the ratio of moles of the multiple types of metal ions to moles of the nitrogen-containing cyclic compound is not particularly limited. From the viewpoint of selectively reacting the nitrogen-containing cyclic compound with the first metal ion (a specific metal ion) contained in the liquid, the ratio of moles of the first metal ion (a specific metal ion) to moles of the nitrogen-containing cyclic compound, i.e., first metal ion:nitrogen-containing cyclic compound, may be 0.5:2 to 2:1, or 0.8:1.2 to 1.2:0.8.

[0048] The method for separating metal ions according to this disclosure includes the step of reacting the nitrogen-containing cyclic compound with a first metal ion contained in the liquid to form a first metal complex. For example, the nitrogen-containing cyclic compound and the first metal ion contained in the liquid may be reacted by heating a liquid containing the nitrogen-containing cyclic compound and a plurality of types of metal ions.

[0049] From the viewpoint of forming the first metal complex in a short time, it is preferable to heat the liquid by irradiating it with microwaves in the step of forming the first metal complex. This makes it possible to form the first metal complex in a short time of about 10 minutes to 1 hour. Alternatively, the liquid may be heated using a bead bath or the like in the step of forming the first metal complex. The metal complex to be formed may be selected by changing the heating method, such as heating the liquid by irradiating it with microwaves or heating the liquid using a bead bath or the like. For example, using a bead bath or the like may facilitate thermodynamic reactions, while using microwaves may facilitate kinetic reactions. The type of metal complex that is easily formed may also change depending on the type of reaction, and by appropriately changing the heating method, the type of metal complex to be separated, the order in which the metal complexes are separated, etc., may be changed.

[0050] The method for separating metal ions according to this disclosure may further include the steps of recovering the first metal complex and reacting the second metal ions contained in the liquid from which the first metal complex was recovered with the nitrogen-containing cyclic compound to form a second metal complex. This allows for the sequential separation of the generated metal complexes (e.g., precipitates), enabling the recovery of different types of metal complexes in high purity.

[0051] In the step of recovering the first metal complex, for example, the precipitate of the first metal complex generated in the step of forming the first metal complex can be separated.

[0052] The method for separating metal ions according to this disclosure includes a step of reacting a second metal ion contained in the liquid from which the first metal complex was recovered with the nitrogen-containing cyclic compound to form a second metal complex. In this step, for example, a precipitate containing the second metal complex, which is a complex of the second metal ion, may be obtained by heating or performing other operations on the liquid prepared by adding the nitrogen-containing cyclic compound to the liquid from which the first metal complex was recovered, in the same manner as in the step of forming the first metal complex.

[0053] From the viewpoint of selectively reacting the nitrogen-containing cyclic compound with the second metal ion contained in the liquid, the ratio of moles of the second metal ion to the moles of the nitrogen-containing cyclic compound, i.e., the ratio of second metal ion to nitrogen-containing cyclic compound, may be 0.5:2 to 2:1, or 0.8:1.2 to 1.2:0.8. The nitrogen-containing cyclic compound may be added to the liquid from which the first metal complex has been recovered so as to achieve the aforementioned molar ratio.

[0054] When the metal ion separation method of this disclosure selectively separates m or more types of metal ions (where m is an integer of 3 or more), the method may further include the steps of: recovering the second to m-1 metal complexes; and reacting the third to m metal ions contained in the liquid from which the second to m-1 metal complexes were recovered with the nitrogen-containing cyclic compound to form the third to m metal complexes. This allows for the sequential separation of the generated metal complexes (e.g., precipitates), enabling the recovery of m different types of metal complexes in high purity.

[0055] The metal ion separation method of this disclosure can yield a metal complex obtained by reacting a nitrogen cyclic compound with a metal ion. The metal ion may be separated from the metal complex, the metal complex may be reacted with other raw materials to obtain a metal compound, or the metal complex may be used as is. For example, the metal complex may be used as an electrode catalyst to reduce carbon dioxide to carbon monoxide, or as a platinum substitute catalyst in fuel cells. [Examples]

[0056] The above embodiments will be described in more detail below based on the examples, but the above embodiments are not limited to the following examples.

[0057] [Synthesis of CoN4 complex 1] A 14-membered ring nitrogen compound (H2HAM) represented by the following chemical formula was reacted with bis(trifluoromethanesulfonic acid)cobalt(II) (also known as Co(CF3SO3)2 or Co(OTf)2) to obtain a cobalt complex. Specifically, a mixture was obtained by adding H2HAM (0.6375 g, 1.65 mmol) and Co(OTf)2 (0.5918 g, 1.66 mmol) to 15 mL of ethylene glycol, which was used as a solvent. Next, the mixture was irradiated with microwaves at 200°C for 10 minutes to synthesize a cobalt complex. The yield was 1.1624 g (1.56 mmol), and the yield rate was 94.7%.

[0058] [ka]

[0059] The cobalt complex obtained in synthesis 1 described above was subjected to single-crystal X-ray structural analysis to confirm its chemical structure. As a result, it was found that the cobalt complex is a compound ([Co(H2HAM)(OTf)2]) in which the cobalt ion is located in the space surrounded by four nitrogen atoms in H2HAM, and the (OTf) anion is coordinated in the vertically upward and vertically downward directions of the H2HAM plane.

[0060] [Synthesis of CoN4 complex 2] Using the same raw materials as in Synthesis 1 described above, a cobalt complex was obtained by a different synthesis method. Specifically, 5 mL of ethylene glycol, the solvent, was mixed with H2HAM (0.1166 g, 0.30 mmol) and Co(OTf)2 (0.1092 g, 0.31 mmol) to obtain a mixture. This mixture was then heated under reflux for 22 hours to synthesize the cobalt complex. The yield was 0.2105 g (0.28 mmol), and the yield was 93.8%.

[0061] The cobalt complex obtained in Synthesis 2 was subjected to single-crystal X-ray structural analysis to confirm its chemical structure. As a result, it was found that the cobalt complex obtained in Synthesis 2 was ([Co(H2HAM)(OTf)2]), similar to that in Synthesis 1.

[0062] [Reaction of H2HAM in a solution containing Co ions and Mn ions (using microwaves)] To 15 mL of ethylene glycol, the solvent, 0.0706 g (0.1827 mmol) of H2HAM, 0.0650 g (0.1820 mmol) of Co(OTf)2, and 0.642 g (0.1818 mmol) of bis(trifluoromethanesulfonic acid) manganese(II) (also known as Mn(CF3SO3)2 or Mn(OTf)2) were added to obtain a mixture. At this time, the molar ratio of H2HAM, Co(OTf)2, and Mn(OTf)2 was 1:1:1. The mixture was subjected to microwave irradiation at 200°C for 10 minutes, repeating this process five times, and finally irradiated at 220°C for 10 minutes. The resulting precipitate was centrifuged and washed three times with acetone. Precipitate 1, dried after washing, was confirmed to be a cobalt complex ([Co(H2HAM)(OTf)2]) by XRD and XRF measurements described later, with a yield of 0.1279 g and a yield of 90.5%.

[0063] [XRD measurement] The X-ray diffraction (XRD) pattern of precipitate 1 obtained as described above was measured using an X-ray diffractometer (Rigaku Corporation Desktop X-ray Diffractometer MiniFlex). The measurement conditions were as follows. X-ray: CuKα ray (wavelength: 1.54Å) Output: 40kV, 30mA Scanning speed: 10 degrees / minute Step angle: 0.01deg Measurement range (2θ): 5deg~60deg

[0064] The XRD pattern measurement results are shown in Figure 1. In Figure 1, MAT-n-030 is the XRD pattern of precipitate 1, and for comparison, the XRD patterns of the cobalt complex, manganese complex, and H2HAM are also shown. The chemical structure of the manganese complex obtained from the reaction of H2HAM and Mn(OTf)2 has been confirmed to be [Mn(H2HAM)(OTf)2] by single-crystal X-ray crystallography. As shown in Figure 1, the XRD patterns of precipitate 1 and the cobalt complex are the closest, suggesting that the cobalt complex preferentially forms as precipitate 1.

[0065] [XRF measurement] Precipitate 1, obtained as described above, was subjected to X-ray fluorescence analysis (XRF) using a Shimadzu EDX-8000 X-ray fluorescence analyzer under the following conditions. X-ray output 50kV, 39mA Measurement area 5mmφ Measurement time: 100 seconds The analysis revealed that Mn was present at 0.057 atomic percent and Co at 99.943 atomic percent, confirming that the majority of precipitate 1 was a cobalt complex.

[0066] [Reaction of H2HAM in a solution containing Co ions and Mn ions (using a bead bath)] To 10 mL of ethylene glycol, the solvent, 0.1501 g (0.3884 mmol) of H2HAM, 20.1397 g (0.3913 mmol) of Co(OTf), and 20.1429 g (0.4047 mmol) of Mn(OTf) were added to obtain a mixture. At this time, the molar ratio of H2HAM, Co(OTf)2, and Mn(OTf)2 was 1:1:1. The mixture was heated in a bead bath at 200°C for 24 hours. The resulting precipitate was centrifuged and then washed three times with acetone. Precipitate 2, which was dried after washing, was confirmed to be a cobalt complex ([Co(H2HAM)(OTf)2]) by XRF measurement in the same manner as precipitate 1. The analysis revealed that Mn was present at 0.920 atomic percent and Co at 99.080 atomic percent, confirming that the majority of precipitate 2 was a cobalt complex.

[0067] [Reaction of H2HAM in a solution containing Co ions, Ni ions, and Mn ions (using microwaves)] To 15 mL of ethylene glycol, the solvent, 0.0509 g (0.1317 mmol) of H2HAM, 0.0466 g (0.1305 mmol) of Co(OTf)2, 0.0463 g (0.1298 mmol) of bis(trifluoromethanesulfonic acid) nickel(II) (also known as Ni(CF3SO3)2 or Ni(OTf)2), and 0.0458 g (0.1297 mmol) of Mn(OTf)2 were added to obtain a mixture. At this time, the molar ratio of H2HAM, Co(OTf)2, Ni(OTf)2, and Mn(OTf)2 was 1:1:1:1. The mixture was irradiated with microwaves at 200°C for 10 minutes, repeating this process three times, and finally irradiated at 220°C for 10 minutes. The resulting precipitate was centrifuged and washed three times with acetone. After washing and drying, precipitate 3 was confirmed to be a cobalt complex ([Co(H2HAM)(OTf)2]) by XRD and XRF measurements described later, with a yield of 0.0874 g and a yield of 89.7%.

[0068] [XRD measurement and XRF measurement] XRD and XRF measurements were performed on precipitate 3, obtained as described above, under the same conditions as for precipitate 1. The XRD pattern measurement results are shown in Figure 2. In Figure 2, MAT-n-032 is the XRD pattern of precipitate 3, and for comparison, the XRD patterns of the cobalt complex, nickel complex, manganese complex, and H2HAM are also shown. The chemical structure of the nickel complex obtained from the reaction of H2HAM and Ni(OTf)2 has been confirmed to be [Ni(H2HAM)](OTf)2 by single-crystal X-ray crystallography. In the nickel complex, the anionic portion was liberated from Ni, and the cation and anionic portions were clearly separated. As shown in Figure 2, it was confirmed that the XRD pattern of precipitate 3 is similar to that of the cobalt complex or the nickel complex. Next, XRF analysis of precipitate 3 revealed that Mn was 0.050 atomic%, Co was 91.551 atomic%, and Ni was 8.399 atomic%, confirming that the majority of precipitate 3 is a cobalt complex.

[0069] [Reaction of H2HAM in a solution containing Co ions, Ni ions, and Mn ions (using a bead bath)] To 10 mL of ethylene glycol, the solvent, 0.1503 g (0.3890 mmol) of H2HAM, 20.1402 g (0.3927 mmol) of Co(OTf), 20.1433 g (0.4016 mmol) of Ni(OTf), and 20.1379 g (0.3906 mmol) of Mn(OTf) were added to obtain a mixture. At this time, the molar ratio of H2HAM, Co(OTf)2, Ni(OTf)2, and Mn(OTf)2 was 1:1:1:1. The mixture was heated in a bead bath at 200°C for 24 hours. The resulting precipitate was centrifuged and then washed three times with acetone. Precipitate 4, which was dried after washing, was confirmed to be a cobalt complex ([Co(H2HAM)(OTf)2]) by XRF measurement in the same manner as precipitate 1. The analysis revealed that Mn was 2.688 atomic%, Co was 92.542 atomic%, and Ni was 4.770 atomic%, confirming that the majority of precipitate 4 was a cobalt complex.

[0070] [Reaction of H2HAM in a solution containing Ni and Mn ions (using microwaves)] To 15 mL of ethylene glycol, the solvent, 0.0710 g (0.1837 mmol) of H2HAM, 20.0686 g (0.1923 mmol) of Ni(OTf), and 20.680 g (0.1926 mmol) of Mn(OTf) were added to obtain a mixture. At this time, the molar ratio of H2HAM, Ni(OTf)2, and Mn(OTf)2 was 1:1:1. The mixture was repeatedly irradiated with microwaves at 200°C for 10 minutes. After heating, the mixture was allowed to stand, and a precipitate formed. The obtained precipitate was centrifuged and then washed three times with acetone. Precipitate 5, which was dried after washing, was confirmed to be a nickel complex ([Ni(H2HAM)](OTf)2) by XRF measurement in the same manner as precipitate 1. The analysis revealed that Mn was present at 0.073 atomic percent and Ni at 99.927 atomic percent, confirming that the majority of precipitate 5 was a nickel complex.

[0071] [Reaction of H2HAM in a solution containing Ni and Mn ions 1 (using a bead bath)] To 4 mL of ethylene glycol, the solvent, 0.1540 g (0.3985 mmol) of H2HAM, 20.1428 g (0.4002 mmol) of Ni(OTf), and 20.1413 g (0.4002 mmol) of Mn(OTf) were added to obtain a mixture. At this time, the molar ratio of H2HAM, Ni(OTf)2, and Mn(OTf)2 was 1:1:1. The mixture was heated in a bead bath at 200°C for 24 hours. The resulting precipitate was centrifuged and then washed three times with acetone. Precipitate 6, which was dried after washing, was confirmed to have a manganese complex ([Mn(H2HAM)(OTf)2]) as its main component by XRF measurement, in the same manner as with precipitate 1. The analysis revealed that Mn was present at 81.082 atomic percent and Ni at 18.918 atomic percent, confirming that the majority of precipitate 6 was a manganese complex. As mentioned above, when microwaves were used, the majority of precipitate 5 was a nickel complex, but when a bead bath was used this time, the majority of precipitate 6 was a manganese complex.

[0072] [Reaction of H2HAM in a solution containing Co ions and Ni ions (using a bead bath)] To 10 mL of ethylene glycol, the solvent, 0.1499 g (0.3879 mmol) of H2HAM, 20.1390 ​​g (0.3893 mmol) of Co(OTf), and 20.1397 g (0.3915 mmol) of Ni(OTf) were added to obtain a mixture. At this time, the molar ratio of H2HAM, Co(OTf)2, and Ni(OTf)2 was 1:1:1. The mixture was heated in a bead bath at 200°C for 24 hours. The resulting precipitate was centrifuged and then washed three times with acetone. Precipitate 7, which was dried after washing, was confirmed to be a cobalt complex ([Co(H2HAM)(OTf)2]) by XRF measurement in the same manner as precipitate 1. The analysis revealed that Mn was 0.038 atomic%, Co was 93.308 atomic%, and Ni was 6.654 atomic%, confirming that the majority of precipitate 7 was a cobalt complex.

[0073] [Reaction of H2HAM in a solution containing Ni and Mn ions (2: using a bead bath)] To 5 mL of ethylene glycol, the solvent, 0.1009 g (0.2611 mmol) of H2HAM, 0.0938 g (0.2629 mmol) of Ni(OTf)2, and 0.1601 g (0.2602 mmol) of manganese bis(trifluoromethanesulfonyl)amide (also known as Mn(TFSA)2) were added to obtain a mixture. At this time, the molar ratio of H2HAM, Ni(OTf)2, and Mn(TFSA)2 was 1:1:1. The mixture was heated in a bead bath at 200°C for 24 hours. The resulting precipitate was centrifuged and then washed three times with acetone. Precipitate 8, which was dried after washing, was confirmed to be a manganese complex by XRF measurement in the same manner as precipitate 1. The analysis revealed that Mn was present at 95.701 atomic percent and Ni at 4.299 atomic percent, confirming that the majority of precipitate 8 was a manganese complex.

[0074] [Reaction of H2HAM in a solution containing Mn ions, Ni ions, and Co ions (using a bead bath)] To 5 mL of ethylene glycol, the solvent, 0.1000 g (0.2588 mmol) of H2HAM, 20.0938 g (0.2629 mmol) of Ni(OTf), 20.0948 g (0.2655 mmol) of Co(OTf), and 20.1612 g (0.2620 mmol) of Mn(TFSA) were added to obtain a mixture. At this time, the molar ratio of H2HAM, Ni(OTf)2, Co(OTf)2, and Mn(TFSA)2 was 1:1:1:1. The mixture was heated in a bead bath at 200°C for 24 hours. The resulting precipitate was centrifuged and then washed three times with acetone. Precipitate 9, which was dried after washing, was confirmed to be a cobalt complex by XRF measurement in the same manner as precipitate 1. The analysis revealed that Mn was 0.212 atomic%, Co was 94.328 atomic%, and Ni was 5.460 atomic%, confirming that the majority of precipitate 9 was a cobalt complex.

[0075] From the above results, it was confirmed that the H2HAM ligand selectively captures Co ions among Co ions, Ni ions, and Mn ions, yielding a precipitate. Furthermore, it was confirmed that by removing the precipitate containing the selectively captured Co ions and using the H2HAM ligand again, it is possible to selectively capture Ni ions (when using microwaves) or Mn ions (when using a bead bath) and obtain a precipitate. Therefore, by sequentially reacting metal ions in a liquid with the H2HAM ligand to precipitate them as complexes and then separating them, metal ions can be selectively separated with high purity. Furthermore, it was found that Co ions can be separated and recovered as a complex in a short time using a microwave reaction.

Claims

1. A step of preparing a liquid containing multiple types of metal ions and nitrogen-containing cyclic compounds containing 12-membered to 18-membered rings with two or more nitrogen atoms, A step of reacting the nitrogen-containing cyclic compound with a first metal ion contained in the liquid to form a first metal complex, A method for separating metal ions containing [a specific substance].

2. The method for separating metal ions according to claim 1, wherein the first metal complex comprises the first metal ion, an anion, and the nitrogen-containing cyclic compound.

3. The method for separating metal ions according to claim 1, wherein the plurality of metal ions are transition metal ions.

4. The method for separating metal ions according to claim 1, wherein the nitrogen-containing cyclic compound is a compound represented by the following general formula (1). 【Chemistry 1】 In general formula (1), R ８ , ７ , ４ , ６ , ３ , ５ , ２ , １ ~R ４ each independently represents a linking group in which the number of atoms forming a ring structure represented by general formula (1) is 2 to 4, and the atoms are 2 to 4 carbon atoms and 0 or 1 nitrogen atom, oxygen atom or sulfur atom (however, the total of carbon atoms and nitrogen atoms, oxygen atoms or sulfur atoms is 2 to 4), and the carbon atoms forming the ring structure contained in R １ may form a 5-membered or 6-membered ring together with at least one of the carbon atoms forming the ring structure contained in R ２ and the carbon atoms forming the ring structure contained in R ４ and may form a 5-membered or 6-membered ring together with at least one of the carbon atoms forming the ring structure contained in R ３ and the carbon atoms forming the ring structure contained in R ２ and may form a 5-membered or 6-membered ring together with at least one of the carbon atoms forming the ring structure contained in R ４ and may form a 5-membered or 6-membered ring together with at least one of the carbon atoms forming the ring structure contained in R ５ ~R ８ each independently represents a hydrogen atom or a monovalent substituent, and only one of the bonds represented by the dotted line between R １ and the nitrogen atom and the bond represented by the dotted line between R ５ and the nitrogen atom is included, and only one of the bonds represented by the dotted line between R ２ and the nitrogen atom and the bond represented by the dotted line between R ６ and the nitrogen atom is included, and only one of the bonds represented by the dotted line between R ３ and the nitrogen atom and the bond represented by the dotted line between R ７ and the nitrogen atom is included, and only one of the bonds represented by the dotted line between R ４ and the nitrogen atom and the bond represented by the dotted line between R ８ and the nitrogen atom is included.

5. The method for separating metal ions according to claim 1, wherein the nitrogen-containing cyclic compound is a compound represented by the following general formula (1-A) or a compound represented by the general formula (1-B). 【Chemistry 2】 In general formula (1-A) and general formula (1-B), R １ ~R ４ Each of these is a linking group in which the number of atoms forming a ring structure represented independently by general formula (1-A) or general formula (1-B) is 2 to 4, and the atoms are 2 to 4 carbon atoms and 0 or 1 nitrogen, oxygen, or sulfur atom (however, the total number of carbon atoms and nitrogen, oxygen, or sulfur atoms is 2 to 4), R １ The carbon atoms that form the ring structure contained in R ２ The carbon atoms and R that form the ring structure contained in the above-mentioned ring structure ４ R may form a five-membered ring or a six-membered ring together with at least one of the carbon atoms that form the ring structure contained in R. ３ The carbon atoms that form the ring structure contained in R ２ The carbon atoms and R that form the ring structure contained in the above-mentioned ring structure ４ It may form a five-membered ring or a six-membered ring together with at least one of the carbon atoms that form the ring structure contained in the material.

6. The method for separating metal ions according to claim 1, wherein the nitrogen-containing cyclic compound is at least one selected from the group consisting of the compound represented by the following general formulas (1-1), (1-2), (1-3), (1-4), (1-5), (1-6), and (1-7). 【Transformation 3】 【Chemistry 4】 In general formula (1-1), R １１ ~R １６ Each of these independently represents a substituent, and each of these independently represents a value from 0 to 2. In general formula (1-2), R ２１ ~R ２４ Each of these independently represents a substituent, and each of these independently represents a value from 0 to 2. In general formula (1-3), R ３１ ~R ３４ Each of these independently represents a substituent, and each of these independently represents a value from 0 to 4. In general formula (1-4), R ４１ ~R ４６ Each of these independently represents a substituent, and each of these independently represents 0 to 2, R ４７ and R ４８ *-CR １ R ２ - * (R １ and R ２ Each is independently a hydrogen atom or a monovalent substituent, and * indicates the bond position), *-NR ３ - * (R ３ is a hydrogen atom or a monovalent substituent, where * indicates the bond position), a sulfur atom, an oxygen atom, or a carbonyl group. In general formula (1-5), R ５１ ~R ５６ Each of these independently represents a substituent, and each of these independently represents 0 to 2, R ５７ and R ５８ Each of these is independently a hydrogen atom or a monovalent substituent. In general formula (1-6), R ６１ ~R ６４ Each of these independently represents a substituent, and each of these independently represents 0 to 3, R ６５ and R ６６ *-CR ４ R ５ - * (R ４ and R ５ Each is independently a hydrogen atom or a monovalent substituent, and * indicates the bond position), *-NR ６ - * (R ６ is a hydrogen atom or a monovalent substituent, where * indicates the bond position), a sulfur atom, an oxygen atom, or a carbonyl group. In general formula (1-7), R ７１ ~R ７４ Each of these independently represents a substituent, and each of these independently represents 0 to 3, R ７５ and R ７６ Each of these is independently, *-CR ７ - * (R ７ is a hydrogen atom or a monovalent substituent (where * indicates a bond position) or a nitrogen atom.

7. The method for separating metal ions according to claim 1, wherein the step of forming the first metal complex is to heat the liquid.

8. The method for separating metal ions according to claim 7, wherein in the step of forming the first metal complex, the liquid is heated by irradiating it with microwaves, or the liquid is heated in a bead bath.

9. The process involves recovering the first metal complex, A method for separating metal ions according to any one of claims 1 to 8, further comprising the step of reacting a second metal ion contained in the liquid from which the first metal complex has been recovered with the nitrogen-containing cyclic compound to form a second metal complex.

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