Hollow manganese-based lithium ion sieve composite material and preparation method and application thereof

Abstract

The present application relates to the technical field of lithium ion adsorption material, in particular to a kind of hollow manganese-based lithium ion sieve composite material and its preparation method and application.The preparation method includes the following steps: (1) ZIF-67 is dispersed in solvent, manganese salt is added, stirring reaction is carried out, after reaction is finished, filtration, washing and drying are carried out to obtain hollow manganese-based material;(2) the hollow manganese-based material is taken, nitrate and lithium salt are added, after being mixed sufficiently, calcination is carried out, and excess molten salt is removed, to obtain the hollow manganese-based lithium ion sieve composite material.The lithium ion adsorption capacity of the hollow manganese-based lithium ion sieve composite material prepared by the method is large, manganese loss is small, and the cycle stability of lithium absorption and lithium desorption is good.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion adsorption materials technology, and more specifically, to a hollow manganese-based lithium-ion sieve composite material, its preparation method, and its application. Background Technology

[0002] Lithium is an important strategic resource and one of the most ideal materials for new energy development. Natural lithium resources consist of minerals and brines. Extracting lithium from ores is relatively complex and energy-intensive, while extracting lithium from brines is simpler and easier to operate. Lithium extraction from brines mainly relies on adsorbents.

[0003] In the existing technology, the main adsorbents for extracting lithium from brine are manganese-based materials and titanium-based materials. Compared with titanium-based materials, manganese-based materials have a faster adsorption rate, are non-toxic, have low production costs, have high selectivity for lithium ions, and cause less environmental pollution. However, the chemical properties of traditional manganese-based ion sieves are unstable. During the acid modification process, Mn(II) is easily dissolved by the acid, resulting in manganese loss and reduced adsorption capacity, i.e., poor cycle stability.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The primary objective of this invention is to provide a method for preparing hollow manganese-based lithium-ion sieve composite materials. This method uses ZIF-67 as a template and employs Mn... 2+ H produced by hydrolysis + Etching ZIF-67 causes it to release Co. 3+ The formation of hollow materials provides more sites for lithium ion adsorption, and the spatial confinement effect of molten salt materials is used to achieve homogeneous distribution of Mn / Co species, reduce manganese dissolution, enhance structural stability, and improve the cycle stability of lithium adsorption and delithiation of hollow manganese-based lithium ion sieve composite materials.

[0006] The second objective of this invention is to provide a hollow manganese-based lithium-ion sieve composite material, prepared by the method described above, wherein the hollow manganese-based lithium-ion sieve composite material has a large lithium-ion adsorption capacity, low manganese dissolution, and good cycle stability in lithium adsorption and delithiation.

[0007] A third objective of this invention is to provide the application of the hollow manganese-based lithium ion sieve composite material described above in the extraction of lithium.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0009] A method for preparing a hollow manganese-based lithium-ion sieve composite material includes the following steps:

[0010] (1) Disperse ZIF-67 in a solvent, add manganese salt, stir to react, and after the reaction is completed, filter, wash and dry to obtain hollow manganese-based material;

[0011] (2) Take the hollow manganese-based material prepared in step (1), add nitrate and lithium salt, mix thoroughly and calcine to remove excess molten salt, and obtain the hollow manganese-based lithium ion sieve composite material.

[0012] Preferably, the preparation method of ZIF-67 includes the following steps:

[0013] Cobalt nitrate was dissolved in an aqueous solution containing CTAB, and then an aqueous solution containing 2-methylimidazole was added. The mixture was stirred and reacted for 20-40 minutes. After solid-liquid separation, the mixture was washed and dried to obtain ZIF-67.

[0014] More preferably, the molar ratio of cobalt nitrate to 2-methylimidazole is 1:8 to 15.

[0015] Preferably, the molar ratio of the manganese salt to the cobalt nitrate is 10 to 50:1.

[0016] Preferably, the solvent includes water, and the ZIF-67 is dispersed in the solvent at a mass concentration of 10-20%.

[0017] Preferably, the manganese salt includes at least one of manganese nitrate, manganese chloride, or manganese sulfate.

[0018] Preferably, in step (1), the washing process involves first washing with water and then washing with alcohol.

[0019] Preferably, the nitrate includes potassium nitrate or sodium nitrate.

[0020] Preferably, the molar ratio of the nitrate to the manganese salt is 10 to 15:1.

[0021] Preferably, the lithium salt includes lithium carbonate or lithium chloride.

[0022] Preferably, the molar ratio of the lithium salt to the manganese salt is 0.5 to 1:1.

[0023] Preferably, the mixing includes grinding, and the grinding time is 0.5 to 1 hour.

[0024] Preferably, the calcination temperature is 600–800°C, and the calcination time is 1–4 hours.

[0025] Preferably, in step (2), the method for removing excess molten salt includes soaking, filtering, and drying with deionized water.

[0026] A hollow manganese-based lithium ion sieve composite material is prepared by the method described above.

[0027] The application of hollow manganese-based lithium ion sieve composite materials as described above in the extraction of lithium.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) This invention uses ZIF-67 as a template. Thanks to the special three-dimensional tunnels of MOF, it can only allow Li ions with smaller ionic radii to pass through. + Through, while other metal ions (Na) + K + Mg 2+ (e.g.) Due to their large ionic radius and the fact that they can only adhere to the surface of materials and cannot be adsorbed, the selectivity of composite materials is effectively improved.

[0030] (2) The method of the present invention uses Mn 2+ H produced by hydrolysis + This process further etches ZIF-67, causing ZIF-67 to release Co. 3+ Meanwhile, OH - With H + Increased due to consumption, then Co 3+ With Mn 2+ Co-precipitation occurs to form a precipitate around the ZIF-67 nanocubes. As the reaction proceeds, the internal ZIF-67 becomes fragile, and Co... 3+ It continues to release outwards, eventually forming a hollow material, providing more sites for the adsorption of lithium ions.

[0031] (3) The method of the present invention utilizes the unique spatial confinement effect of molten salt material to prevent the mutual linkage between Mn / Co species particles, realize the homogeneous distribution of Mn / Co species, and the Co-O bond energy is greater than the Mn-O bond energy, effectively suppressing Jahn-Teller distortion, reducing manganese dissolution, enhancing structural stability, and improving the cycle stability of lithium adsorption and delithiation of hollow manganese-based lithium ion screen composite material.

[0032] (4) The hollow manganese-based lithium ion sieve composite material provided by the present invention has the advantages of large lithium ion adsorption capacity, small manganese dissolution loss, and good cycle stability of lithium adsorption and delithiation. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 The graphs show the adsorption performance test results of the lithium-ion sieves prepared in the various embodiments and comparative examples of this invention. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0036] The first aspect of the present invention provides a method for preparing a hollow manganese-based lithium-ion sieve composite material, comprising the following steps:

[0037] (1) Disperse ZIF-67 in a solvent, add manganese salt, stir to react, and after the reaction is completed, filter, wash and dry to obtain hollow manganese-based material;

[0038] (2) Take the hollow manganese-based material prepared in step (1), add nitrate and lithium salt, mix thoroughly and calcine to remove excess molten salt, and obtain the hollow manganese-based lithium ion sieve composite material.

[0039] Metal-organic frameworks (MOFs) offer advantages such as controllable morphology, tunable pore size, and variable composition. Using MOFs as precursors and undergoing appropriate processing, hollow nanomaterials can be obtained. Hollow nanomaterials possess advantages such as high specific surface area and unique hollow structure, providing more sites for lithium ion adsorption and exhibiting resistance to deformation during lithium ion adsorption and desorption.

[0040] This invention uses ZIF-67 as a template and utilizes the unique three-dimensional tunnels of MOFs to improve the lithium-ion adsorption selectivity of the composite material; through Mn 2+ H produced by hydrolysis + Etching ZIF-67 causes it to release Co. 3+The hollow material provides more sites for lithium ion adsorption. The prepared hollow material is mixed with nitrate and lithium salt and then calcined. During the calcination process, the nitrate forms a molten liquid, which prevents the Mn / Co species particles from bonding together, achieving a homogeneous distribution of Mn / Co species. Moreover, the Co-O bond energy is greater than the Mn-O bond energy, which effectively suppresses Jahn-Teller distortion, reduces manganese dissolution, enhances structural stability, and improves the cycle stability of lithium adsorption and delithiation in the hollow manganese-based lithium ion sieve composite material. During the calcination process, the lithium salt forms a lithium ion sieve precursor with manganese.

[0041] In some specific embodiments of the present invention, the preparation method of ZIF-67 includes the following steps:

[0042] Cobalt nitrate is dissolved in an aqueous solution containing CTAB, and then an aqueous solution containing 2-methylimidazole is added. The mixture is stirred and reacted for 20-40 minutes, for example, any value or a range of any two values ​​from 20 min, 25 min, 30 min, 35 min, and 40 min. After solid-liquid separation, the mixture is washed and dried to obtain ZIF-67. As an example, the washing is water washing.

[0043] In some specific embodiments of the present invention, the molar ratio of cobalt nitrate to 2-methylimidazole is 1:8 to 15, for example, any one value or a range of any two values ​​from 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15.

[0044] This invention rationally controls the molar ratio of cobalt nitrate and the organic ligand 2-methylimidazole, making the pore size of the prepared ZIF-67 more suitable for lithium ion adsorption. Too high or too low a ratio will affect the adsorption capacity and selectivity of lithium ions.

[0045] In some specific embodiments of the present invention, the molar ratio of the manganese salt to the cobalt nitrate is 10 to 50:1, for example, any one value or a range of any two values ​​from 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1.

[0046] Excessive manganese salts will reduce the Co content in the prepared composite material, thereby affecting the structural stability of the composite material and increasing manganese dissolution loss; insufficient manganese salts will prevent the formation of hollow materials and reduce the adsorption capacity of lithium ions. Therefore, it is necessary to reasonably control the ratio range of manganese salts and cobalt nitrate.

[0047] In some specific embodiments of the present invention, the solvent includes water. To avoid impurities, as an example, deionized water is used. After the ZIF-67 is dispersed in the solvent, the mass concentration of the ZIF-67 is 10-20%, for example, any value or a range of any two values ​​from 10%, 12%, 14%, 15%, 16%, 18%, to 20%. If the ZIF-67 concentration is too high, the ion exchange effect is poor and a good hollow structure cannot be formed; if the concentration is too low, a large amount of water is required.

[0048] In some specific embodiments of the present invention, the manganese salt includes at least one of manganese nitrate, manganese chloride, or manganese sulfate.

[0049] In some specific embodiments of the present invention, in step (1), the washing step is water washing followed by alcohol washing. Since calcination is to be carried out subsequently, if only water washing is used, the surface tension of the water is large, which will cause the material particles after calcination to become larger; in addition, the washing process usually needs to be carried out multiple times, so simply using alcohol washing will increase the amount of alcohol used, resulting in increased costs. Therefore, the present invention adopts the method of water washing followed by alcohol washing, which reduces costs and avoids the material particles from becoming larger during the calcination process due to water washing.

[0050] In some specific embodiments of the present invention, the number of water washes can be multiple, such as 2 times, 3 times, 4 times, 5 times, 6 times, etc., and the number of alcohol washes can also be multiple, such as 2 times, 3 times, 4 times, etc.

[0051] In some specific embodiments of the present invention, the alcohol used in the alcohol washing includes low-boiling-point alcohols such as methanol or ethanol.

[0052] In some specific embodiments of the present invention, the nitrate includes potassium nitrate or sodium nitrate.

[0053] In some specific embodiments of the present invention, the molar ratio of the nitrate to the manganese salt is 10 to 15:1, for example, any one value or a range of any two values ​​from 10:1, 11:1, 12:1, 13:1, 14:1, to 15:1.

[0054] In some specific embodiments of the present invention, the lithium salt includes lithium carbonate or lithium chloride.

[0055] In some specific embodiments of the present invention, the molar ratio of the lithium salt to the manganese salt is 0.5 to 1:1, for example, any one value or a range of any two values ​​among 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, and 1:1.

[0056] In some specific embodiments of the present invention, the mixing includes grinding mixing, which can make the materials more thoroughly mixed. The grinding time is 0.5 to 1 hour, for example, any one value or a range of any two values ​​from 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours, to 1 hour.

[0057] In some specific embodiments of the present invention, the calcination temperature is 600 to 800°C, for example, any one value or a range of any two values ​​among 600°C, 650°C, 700°C, 750°C, and 800°C; the calcination time is 1 to 4 hours, for example, any one value or a range of any two values ​​among 1 hour, 2 hours, 3 hours, and 4 hours.

[0058] Excessive calcination temperature will cause the material to sinter, reduce the specific surface area, increase the pore size, and hinder the adsorption of lithium ions; excessively low calcination temperature will prevent the homogeneous distribution of Co and Mn.

[0059] In some specific embodiments of the present invention, step (2) of the method for removing excess molten salt includes soaking, filtering and drying with deionized water.

[0060] A second aspect of the present invention provides a hollow manganese-based lithium ion sieve composite material, which is prepared by the preparation method of the hollow manganese-based lithium ion sieve composite material described in any one of the foregoing embodiments.

[0061] The hollow manganese-based lithium ion sieve composite material provided by this invention has a large lithium ion adsorption capacity, low manganese dissolution, and good cycle stability during lithium adsorption and delithiation.

[0062] A third aspect of the present invention provides the application of the hollow manganese-based lithium ion sieve composite material as described above in the extraction of lithium.

[0063] The following detailed description of some embodiments of the present invention is provided in conjunction with specific application examples. Unless otherwise specified, all raw materials used in the embodiments are commercially available.

[0064] Example 1

[0065] (1) Preparation of ZIF-67:

[0066] Dissolve 1 mmol of cobalt nitrate in 10 ml of deionized water containing 1 mg of CTAB, then add 100 ml of deionized water containing 11 mmol of 2-methylimidazole, stir for 30 minutes, filter, wash with water, and dry to obtain ZIF-67.

[0067] (2) Preparation of hollow manganese-based materials

[0068] The prepared ZIF-67 was dispersed in deionized water to achieve a ZIF-67 mass concentration of 10%. Then, 15 mmol of manganese nitrate was added, and the mixture was stirred for 12 hours. The mixture was then filtered, washed, first with water five times, then with ethanol twice, and finally dried to obtain the hollow manganese-based material.

[0069] (3) Preparation of hollow manganese-based lithium ion sieve composite materials

[0070] 150 mmol of potassium nitrate and 8 mmol of lithium carbonate were added to the prepared hollow manganese-based material and ground for 0.5 h. Then, it was calcined at 750 °C for 2 h. Finally, it was impregnated with deionized water to remove salt, filtered, and dried to obtain the hollow manganese-based lithium ion sieve composite material.

[0071] Example 2

[0072] (1) Preparation of ZIF-67:

[0073] Dissolve 1 mmol of cobalt nitrate in 10 ml of deionized water containing 1 mg of CTAB, then add 100 ml of deionized water containing 11 mmol of 2-methylimidazole, stir for 30 minutes, filter, wash with water, and dry to obtain ZIF-67.

[0074] (2) Preparation of hollow manganese-based materials

[0075] The prepared ZIF-67 was dispersed in deionized water to achieve a ZIF-67 mass concentration of 10%. Then, 10 mmol of manganese chloride was added, and the mixture was stirred for 20 hours. After filtration and washing, the mixture was first washed with water five times and then with ethanol twice. Finally, it was dried to obtain the hollow manganese-based material.

[0076] (3) Preparation of hollow manganese-based lithium ion sieve composite materials

[0077] 150 mmol of potassium nitrate and 8 mmol of lithium carbonate were added to the prepared hollow manganese-based material and ground for 1 hour. Then, it was calcined at 750°C for 3 hours. Finally, it was impregnated with deionized water to remove salt, filtered, and dried to obtain the hollow manganese-based lithium ion sieve composite material.

[0078] Example 3

[0079] (1) Preparation of ZIF-67:

[0080] Dissolve 1 mmol of cobalt nitrate in 10 ml of deionized water containing 1 mg of CTAB, then add 100 ml of deionized water containing 11 mmol of 2-methylimidazole, stir for 30 minutes, filter, wash with water, and dry to obtain ZIF-67.

[0081] (2) Preparation of hollow manganese-based materials

[0082] The prepared ZIF-67 was dispersed in deionized water to achieve a ZIF-67 mass concentration of 15%. Then, 40 mmol of manganese nitrate was added, and the mixture was stirred for 12 hours. The mixture was then filtered, washed, first with water five times, then with ethanol twice, and finally dried to obtain the hollow manganese-based material.

[0083] (3) Preparation of hollow manganese-based lithium ion sieve composite materials

[0084] 400 mmol of potassium nitrate and 20 mmol of lithium chloride were added to the prepared hollow manganese-based material and ground for 0.5 h. Then, it was calcined at 700 °C for 4 h. Finally, it was impregnated with deionized water for desalination, filtered, and dried to obtain the hollow manganese-based lithium ion sieve composite material.

[0085] Example 4

[0086] Example 4 is similar to Example 1, except that the amount of 2-methylimidazole added is 8 mmol, and the other conditions are the same as in Example 1.

[0087] Example 5

[0088] Example 5 is similar to Example 1, except that the amount of 2-methylimidazole added is 15 mmol, and the other conditions are the same as in Example 1.

[0089] Comparative Example 1

[0090] Traditional manganese-based lithium ion sieves:

[0091] 1 mmol of lithium carbonate and 1 mmol of manganese dioxide were thoroughly ground for 0.5 h, and then calcined at 750 °C for 2 h. After the reaction was completed, lithium manganese oxide was obtained.

[0092] Experimental Example

[0093] Take 0.1 g of lithium-ion sieve material from each of the above examples and comparative examples, and place it in 10 mL of 1.0 mol / L hydrochloric acid solution. Stir for 24 h to remove lithium ions from the precursor. Then wash with deionized water until neutral and dry. Finally, place the dried product in a lithium-containing solution and stir for 24 h. Use ICP to detect the metal ion concentration and calculate the metal ion adsorption capacity, manganese dissolution loss, and partition coefficient (Kd). The results of lithium-ion adsorption capacity and manganese dissolution loss are shown in Table 1. According to Kd=(C0-C i )·V / (m·C i Calculate the partition coefficient Kd of each ion in the solution, where C0 is the initial concentration of the ions, C i V is the equilibrium concentration of ions, V is the volume of the solution, and m is the mass of the lithium ion sieve material. The distribution coefficients of each ion are shown in Table 2.

[0094] Table 1

[0095] name Lithium-ion adsorption capacity (mg / g) Manganese dissolution loss (%) Example 1 433.21 0.11 Example 2 405.32 0.11 Example 3 358.19 0.12 Example 4 385.72 0.12 Example 5 394.35 0.11 Comparative Example 1 103.33 0.36

[0096] As shown in Table 1, the hollow manganese-based lithium-ion sieve composite material prepared by the method of this invention exhibits significantly improved lithium-ion adsorption capacity and significantly reduced manganese dissolution loss compared to traditional manganese-based lithium-ion sieves. Figure 1 As shown, the hollow manganese-based lithium ion sieve composite material prepared by the method of the present invention has significantly improved lithium ion adsorption capacity and cycling stability for lithium adsorption and delithiation.

[0097] Table 2

[0098]

[0099] As can be seen from the data in Table 2, the lithium ion partition coefficient of the hollow manganese-based lithium ion sieve composite material prepared by the method of the present invention is much higher than that of other coexisting ions in the brine, indicating that it can selectively adsorb lithium ions and has excellent adsorption selectivity.

[0100] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing a hollow manganese-based lithium-ion sieve composite material, characterized in that, Includes the following steps: (1) Disperse ZIF-67 in a solvent, add manganese salt, stir to react, and after the reaction is completed, filter, wash and dry to obtain hollow manganese-based material; (2) Take the hollow manganese-based material prepared in step (1), add nitrate and lithium salt, mix thoroughly and calcine, soak in deionized water, filter and dry to remove excess molten salt, and the hollow manganese-based lithium ion screen composite material is obtained. The nitrates include potassium nitrate or sodium nitrate.

2. The preparation method of the hollow manganese-based lithium ion sieve composite material according to claim 1, characterized in that, The preparation method of ZIF-67 includes the following steps: Cobalt nitrate was dissolved in an aqueous solution containing CTAB, and then an aqueous solution containing 2-methylimidazole was added. The mixture was stirred and reacted for 20-40 minutes. After solid-liquid separation, the mixture was washed and dried to obtain ZIF-67.

3. The preparation method of the hollow manganese-based lithium ion sieve composite material according to claim 2, characterized in that, Includes at least one of the following features (1) to (2): (1) The molar ratio of cobalt nitrate to 2-methylimidazole is 1:8~15; (2) The molar ratio of the manganese salt to the cobalt nitrate is 10~50:

1.

4. The preparation method of the hollow manganese-based lithium ion sieve composite material according to claim 1, characterized in that, The solvent includes water, and after the ZIF-67 is dispersed in the solvent, the mass concentration of the ZIF-67 is 10~20%.

5. The preparation method of the hollow manganese-based lithium ion sieve composite material according to claim 1, characterized in that, Includes at least one of the following features (1) to (5): (1) The manganese salt includes at least one of manganese nitrate, manganese chloride, or manganese sulfate; (2) In step (1), the washing process is first water washing followed by alcohol washing; (3) The molar ratio of the nitrate to the manganese salt is 10~15:1; (4) The lithium salt includes lithium carbonate or lithium chloride; (5) The molar ratio of the lithium salt to the manganese salt is 0.5 to 1:

1.

6. The preparation method of the hollow manganese-based lithium ion sieve composite material according to claim 1, characterized in that, The mixing includes grinding and mixing, and the grinding and mixing time is 0.5~1h.

7. The preparation method of the hollow manganese-based lithium ion sieve composite material according to claim 1, characterized in that, The calcination temperature is 600~800℃, and the calcination time is 1~4h.

8. A hollow manganese-based lithium-ion sieve composite material, characterized in that, The hollow manganese-based lithium ion sieve composite material was prepared using the method described in any one of claims 1 to 7.

9. The application of the hollow manganese-based lithium ion sieve composite material according to claim 8 in the extraction of lithium.

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