Lithium adsorbent and method for manufacturing same

Abstract

The present invention relates to a lithium adsorbent and a method for manufacturing same, wherein the lithium adsorbent comprises a layered double hydroxide (LDH) composed of an aluminum-based material, a spacer being included between layers of the layered double hydroxide.

Description

Lithium adsorbent and method for manufacturing the same

[0001] The present invention relates to a lithium adsorbent, and more specifically, to a lithium adsorbent that is stable at high temperatures and a method for manufacturing the same.

[0002] The present invention claims priority based on Korean Patent Application No. 10-2024-0191945 filed on December 19, 2024, the entire contents of said application incorporated herein by reference.

[0003] Lithium is used as an essential raw material in various industrial fields, such as secondary batteries, ceramics, glass, pharmaceuticals, and process chemistry. In particular, the importance of lithium is becoming increasingly prominent due to the rising demand for electric vehicles and storage systems. Consequently, efficient recovery and refining technologies for lithium resources are becoming critical.

[0004] The primary sources of lithium are extracted from brine, ore, and recycled battery materials. While methods for recovering lithium from brine include evaporation and chemical processes, most methods involve removing impurities from brine mixed with other substances to obtain a high-concentration lithium solution, which is then used to produce useful lithium compounds.

[0005] Recently, there has been active research aimed at recovering lithium from geothermal brine or oil well brine using direct lithium extraction technology (DLE technology). A representative method among the aforementioned direct lithium extraction technologies is the use of lithium adsorbents.

[0006] Lithium adsorbents are advantageous for lithium recovery compared to evaporation methods, which require a long time, or chemical methods, which consume a large amount of auxiliary materials and generate byproducts, because they can selectively recover only lithium from brine mixed with impurities. Aluminum (Al)-based adsorbents are primarily used as the aforementioned lithium adsorbents. In the above aluminum-based adsorbents, Cl ions may be inserted between Al(OH)3 layers, and Li ions may be inserted and adsorbed within the layers.

[0007] However, the above-mentioned aluminum-based adsorbent has a problem in that Cl within the adsorbent is detached and reverts to Al(OH)3 (Gibbsite) under high-temperature conditions, such as high-temperature brine.

[0008] Therefore, further research is needed on adsorbents usable at high temperatures to adsorb and desorb lithium from low-concentration unconventional lithium resources, such as oil field brine or geothermal brine.

[0009] The technical problem that the present invention aims to solve is to provide a structurally stable lithium adsorbent that maintains interlayer spacing at high temperatures.

[0010] According to one embodiment of the present invention, the lithium adsorbent comprises a layered double hydroxide (LDH) composed of an aluminum-based material, and may include a spacer between the layers of the double hydroxide.

[0011] In one embodiment, the lithium adsorbent may satisfy the following Equation 1 for XRD peak values.

[0012] <Equation 1>

[0013] 0.350 ≤ I2 / I1 ≤ 0.440

[0014] (In Equation 1 above, I1 and I2 represent the peak intensities at XRD peak values ​​when 2θ is 11–11.6 and when 2θ is 20–21, respectively.)

[0015] In one embodiment, when the lithium adsorbent is immersed in distilled water at 85°C for 24 hours, the following Equation 2 can be satisfied.

[0016] <Equation 2>

[0017] 0.430 ≤ I2 / I1 ≤ 0.600

[0018] (In Equation 2 above, I1 and I2 represent the peak intensities at XRD peak values ​​when 2θ is 11–11.6 and when 2θ is 20–21, respectively.)

[0019] In one embodiment, the spacer may include at least one salt selected from phosphate, sulfate, hydrochloride, and nitrate. In one embodiment, the spacer may include PO4.

[0020] In one embodiment, the layer spacing of the double-layer hydroxide may be 7.6 to 7.9 Å. In one embodiment, when the lithium adsorbent is immersed in distilled water at 85°C for 24 hours, the layer spacing of the double-layer hydroxide may be 7.6 to 7.9 Å.

[0021] In one embodiment, the structure having a layer spacing of 4.7 to 4.9 Å and the structure having a layer spacing of 6.0 to 6.2 Å of the double-layer hydroxide may each be 5% or less based on 100% of the lithium adsorbent. In one embodiment, the lithium adsorbent may not include a structure having the said layer spacing.

[0022] In one embodiment, the lithium adsorbent may be represented by the following chemical formula 1.

[0023] [Chemical Formula 1]

[0024] Li·Al x (OH) y ·AnH2O

[0025] (In the above chemical formula 1, A is F - , Cl - , Br - , NO3 - , HCO3 - , and OH - At least one of the following, and 0 <x<5, 0<y<15, 및 0<n<10이다)

[0026] According to another embodiment of the present invention, a method for manufacturing a lithium adsorbent may include the steps of mixing an aluminum-based raw material, sodium hydroxide, and a lithium-based raw material to obtain a mixed solution, separating a solid from the mixed solution, and adding an acidic solution having a pH in the range of 5 to 10 to the solid. In one embodiment, the step of mixing an aluminum-based raw material, sodium hydroxide, and a lithium-based raw material to obtain a mixed solution may include the step of dissolving the aluminum-based raw material and sodium hydroxide in water or brine, and the step of adding the lithium-based raw material to the dissolved mixed aqueous solution.

[0027] In one embodiment, the acid solution with a pH in the range of 5 to 10 may be formed by mixing an acid solution with a pH of 3 or lower and a basic solution with a pH of 10 or higher. In one embodiment, the acid solution may be obtained by neutralizing phosphoric acid and sodium hydroxide.

[0028] In one embodiment, the step of dissolving the aluminum-based raw material and sodium hydroxide in water or brine may be performed at a temperature of 40°C or lower. In one embodiment, the molar ratio of the sodium hydroxide to the aluminum-based raw material (mol of sodium hydroxide / mol of aluminum-based raw material) may be 1.5 to 5.5.

[0029] In one embodiment, the step of separating solids from the mixed solution may include the step of separating the mixed solution into solids and liquid phases, and the step of drying the solids separated from the liquid phase. In one embodiment, the step of drying the solids may be performed at 60 to 150°C.

[0030] In one embodiment, after the step of adding an acid solution with a pH in the range of 5 to 10 to the solid, the method may include the step of drying the solid at 150°C or higher. In one embodiment, the aluminum salt may include one or more selected from the group consisting of aluminum chloride, aluminum sulfate, and aluminum acetate.

[0031] According to one embodiment of the present invention, a lithium adsorbent provides a structurally stabilized lithium adsorbent under harsh conditions, such as high-temperature environments, by minimizing the formation of structures such as Al(OH)3 or AlOOH through a parameter for XRD peak values ​​satisfying a predetermined value.

[0032] According to another embodiment of the present invention, a method for manufacturing a lithium adsorbent enables the production of a structurally stabilized lithium adsorbent under harsh conditions, such as a high-temperature environment, by reacting it with an acidic solution having a pH of a predetermined range.

[0033] FIG. 1 illustrates a lithium adsorbent according to one embodiment of the present invention.

[0034] FIG. 2 is a graph showing the interlayer spacing of a lithium adsorbent according to an embodiment and a comparative example of the present invention.

[0035] FIGS. 3 to 6 show the XRD patterns of a lithium adsorbent according to an embodiment and a comparative example of the present invention.

[0036] FIG. 7 is a schematic diagram of the manufacturing process of a lithium adsorbent according to a comparative example of the present invention.

[0037] FIG. 8 is a schematic diagram of the manufacturing process of a lithium adsorbent according to an embodiment of the present invention.

[0038] FIG. 9 is a schematic diagram of the manufacturing process of a lithium adsorbent according to a comparative example of the present invention.

[0039] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0040] In the present invention, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0041] FIG. 1 illustrates a lithium adsorbent according to one embodiment of the present invention.

[0042] Referring to FIG. 1, the lithium adsorbent comprises a layered double hydroxide (LDH) composed of an aluminum-based material. In one embodiment, the lithium adsorbent may include a spacer between the layers of the double hydroxide. Specifically, the spacer may be positioned between the layers of the double hydroxide structure and may be positioned in a space region where lithium is adsorbed. By including the spacer, the lithium adsorbent of the present invention may have improved high-temperature stability.

[0043] In one embodiment, the spacer may include at least one salt selected from phosphate, sulfate, hydrochloride, and nitrate. Specifically, the spacer may include PO4. By including the spacer in the lithium adsorbent, there is an advantage that it does not easily dissociate by forming a very strong bond with the OH of Al(OH)3 within the lithium adsorbent. Specifically, the O of PO4 and the H of Al(OH)3 form hydrogen bonds, preventing easy dissociation, and the spacer maintains the interlayer spacing, thereby providing stability even under low concentration and high temperature conditions where Li and Cl are prone to dissociation.

[0044]

[0045]

[0046] Specifically, the lithium adsorbent of the present invention may have an XRD peak value satisfying the following Equation 1.

[0047] <Equation 1>

[0048] 0.350 ≤ I2 / I1 ≤ 0.440

[0049] (In Equation 1 above, I1 and I2 represent the peak intensities at XRD peak values ​​when 2θ is 11–11.6 and when 2θ is 20–21, respectively.)

[0050]

[0051] The above Equation 1 may serve as an indicator of the possibility of lithium adsorption at high temperatures. Specifically, the peak intensity of Equation 1 may satisfy the aforementioned range, thereby not including Al(OH)3 and AlOOH structures. Specifically, if the above structure is included in the lithium adsorbent, Cl may be detached from the lithium adsorbent at high temperatures to form Al(OH)3 (Gibbsite), or two layers of Al(OH)3 may undergo dehydration polymerization to form AlOOH (Boehmite). When the above Gibbsite and Boehmite structures are formed, there is a problem that it is difficult for Li and Cl to be adsorbed again.

[0052] In this way, the present invention can provide a lithium adsorbent that satisfies Equation 1 above, thereby minimizing the formation of the Gibbsite and Boehmite structures, which suppresses structural collapse even under harsh conditions such as high temperature, has excellent structural stability, and has high affinity for lithium and excellent adsorption efficiency.

[0053] The above Equation 1 can satisfy 0.350 to 0.440, specifically 0.380 to 0.420, and more specifically 0.400 to 0.410. If the above Equation 1 falls outside the aforementioned range, there is a problem in that the Gibbsite and Boehmite structures are formed at high temperatures, thereby compromising the structural stability of the lithium adsorbent.

[0054] In one embodiment, when the lithium adsorbent of the present invention is immersed in distilled water at 85°C for 24 hours, it can satisfy Formula 2 below.

[0055] <Equation 2>

[0056] 0.430 ≤ I2 / I1 ≤ 0.600

[0057] (In Equation 2 above, I1 and I2 represent the peak intensities at XRD peak values ​​when 2θ is 11–11.6 and when 2θ is 20–21, respectively.)

[0058] The above Equation 2 may be 0.430 to 0.600, specifically 0.435 to 0.500, and more specifically 0.440 to 0.450. By satisfying the above range, the excellent lithium adsorption capacity can be maintained without structural collapse under high temperature conditions. If the above Equation 2 deviates from the above range at high temperatures, the above Gibbsite and Boehmite structures are expressed in the lithium adsorbent, and there is a problem in that lithium cannot be re-adsorbed by the above structure.

[0059] The above double-layer hydroxide (LDH) may refer to an interlayer structure formed by a cation metal hydroxide layer and an anion and water molecules located between the layers. The lithium adsorbent of the present invention has a double-layer hydroxide structure, and because the interlayer anions are exchanged with lithium ions to selectively adsorb lithium, the adsorption capacity for lithium can be increased.

[0060] In one embodiment, the layer spacing of the double-layer hydroxide may be 7.6 to 7.9 Å. The layer spacing may be 7.67 to 7.80 Å, specifically 7.69 to 7.79 Å. In one embodiment, when the lithium adsorbent is immersed in distilled water at 85°C for 24 hours, the layer spacing of the double-layer hydroxide may be 7.6 to 7.9 Å. The layer spacing may be 7.72 to 7.80 Å.

[0061] The layer spacing of the above double-layer hydroxide may be the average value measured over 10 layers. Specifically, the layer spacing can be measured using XRD analysis. By satisfying the aforementioned range for the layer spacing of the above double-layer hydroxide, there is an advantage in that lithium adsorption is facilitated under low concentration and high temperature conditions. If the layer spacing is lower than the aforementioned range, it corresponds to the range of general aluminum-based lithium adsorbents, which leads to a problem of structural collapse at high temperatures. If the layer spacing is higher than the aforementioned range, the layer spacing is excessively high, which leads to a problem of reduced lithium adsorption capacity.

[0062] In one embodiment, the lithium adsorbent may have a structure in which the layer spacing of the double layer hydroxide is 4.7 to 4.9 Å and a structure in which the layer spacing is 6.0 to 6.2 Å, each of which may be 5% or less based on 100% of the lithium adsorbent. Specifically, the structure in which the layer spacing of the double layer hydroxide is 4.7 to 4.9 Å refers to an Al(OH)3 structure, and the structure in which the layer spacing of the double layer hydroxide is 6.0 to 6.2 Å refers to an AlOOH structure.

[0063] In one embodiment, the lithium adsorbent may not contain Al(OH)3 and AlOOH. As described above, the lithium adsorbent may not contain the Al(OH)3 structure and the AlOOH structure to a minimum. Specifically, by not containing the aforementioned structures at all, the lithium adsorbent can minimize structural deformation at high temperatures.

[0064] In one embodiment, the lithium adsorbent may include Formula 1.

[0065] Li·Al x (OH) y ·AnH2O

[0066] (In the above chemical formula 1, A is at least one of the halogen elements, and 0 <x<5, 및 0<n<10이다.)

[0067] According to another embodiment of the present invention, a method for manufacturing a lithium adsorbent may include the steps of mixing an aluminum-based raw material, sodium hydroxide, and a lithium-based raw material to obtain a mixed solution, separating a solid from the mixed solution, and adding an acid solution with a pH in the range of 5 to 10 to the solid. The inventors have discovered that by treating the solid extracted from the solution mixed with the aluminum-based raw material, sodium hydroxide, and lithium-based raw material with an acid solution with a pH in the aforementioned range, the dissolution of Al(OH)3 is prevented, thereby allowing the structure to remain stable even under harsh conditions such as high temperatures. Specifically, in manufacturing an aluminum-based lithium adsorbent, Al(OH)3 has a problem of being vulnerable to acid because it has a metal hydroxide (M-OH) structure. However, as in the present invention, by introducing an acid neutralized to a neutral range, a material is formed in which the spacer of the present invention, which is introduced from the neutralized acid, can form a strong bond with the end portion of Al(OH)3, thereby maintaining the interlayer spacing even at relatively high temperatures and maintaining structural stability.

[0068] The step of obtaining a mixed solution by mixing an aluminum-based raw material, sodium hydroxide, and a lithium-based raw material may sequentially perform the step of dissolving the aluminum-based raw material and sodium hydroxide in water or brine and the step of adding the lithium-based raw material to the dissolved mixed aqueous solution.

[0069] The above aluminum-based raw material may include one or more selected from the group consisting of aluminum chloride, aluminum sulfate, and aluminum acetate. Specifically, the aluminum salt of the above aluminum-based raw material may specifically be aluminum chloride. When the aluminum salt is aluminum chloride, a lithium adsorbent having a stable and uniform structure can be manufactured. More specifically, the aluminum chloride may be included, for example, in the form of a hydrate (AlCl3·6H2O).

[0070] The step of dissolving the aluminum-based raw material and sodium hydroxide in water or brine may involve dissolving the aluminum-based raw material in the water or brine and then slowly adding the sodium hydroxide. For example, the sodium hydroxide (NaOH) may be in powder form, and the water-soluble aluminum salt, which is the aluminum-based raw material, may be dissolved in water, and then the powdered sodium hydroxide may be added and slowly added.

[0071] In one embodiment, the molar ratio of sodium hydroxide to the aluminum-based raw material (mol of sodium hydroxide / mol of aluminum-based raw material) may be 1.5 to 5.5. Specifically, the molar ratio may be 2.0 to 4.0. By satisfying the aforementioned range, an aluminum hydroxide precipitate can be easily produced.

[0072] In one embodiment, the step of dissolving the aluminum-based raw material and sodium hydroxide in water or brine can be performed at a temperature of 40°C or lower. By controlling the temperature to the above range, the aluminum salt and sodium hydroxide can react easily.

[0073] In the step of adding the lithium-based raw material to the dissolved mixed aqueous solution, the lithium-based raw material may be a lithium salt and may include one or more selected from the group consisting of lithium chloride, lithium nitrate, lithium sulfate, and lithium acetate. The lithium salt provides lithium ions during the reaction process and is inserted into the aluminum-based layered double hydroxide composite structure, thereby being used to impart the function of selectively adsorbing lithium ions.

[0074] Specifically, the lithium salt may be lithium chloride. When the lithium salt is lithium chloride, it has the advantage of enabling a uniform supply of lithium ions during the lithium adsorbent formation reaction because it has higher solubility compared to other lithium salts. Therefore, the lithium salt can increase the synthesis efficiency of the lithium adsorbent and obtain a lithium adsorbent with a uniform particle size. In addition, it has the advantage of enhancing economic feasibility due to its relatively low cost.

[0075] The above aluminum salt, the above sodium hydroxide, and the above lithium salt may be mixed according to a stoichiometric ratio. Specifically, the above aluminum salt, the above aluminum fluoride salt, and the above lithium salt may be added according to a stoichiometric ratio to satisfy the compositional formula of Chemical Formula 1 described above.

[0076] The above mixed solution may further include a solvent. The solvent may include one or more selected from the group consisting of water, ethanol, methanol, and butanol. The solvent may be, for example, deionized water. The deionized water may be included in an amount of 5 to 20 parts by weight, preferably 5 to 10 parts by weight, per 100 parts by weight of the total mixed solution.

[0077] When the above deionized water is included within the above range, the mixed solution has an appropriate viscosity, which not only improves processability but also facilitates the reaction within the mixed solution, thereby enabling the acquisition of a uniform form of lithium adsorbent.

[0078] In one embodiment, the step of adding the lithium-based raw material to the dissolved mixed aqueous solution may involve adding water or brine and the lithium-based raw material to a mixed aqueous solution in which an aluminum salt and sodium hydroxide are dissolved and mixed, and then carrying out the reaction in a temperature range of 50 to 150 °C. In one embodiment, the reaction may be carried out within 1 to 3 hours, specifically within 1.5 to 2.5 hours. Under the aforementioned reaction conditions, a lithium adsorbent in which lithium is embodied in a uniform form can be obtained.

[0079] The step of separating solids from the above mixed solution may include the step of separating the mixed solution into solids and liquid phases and the step of drying the solids separated from the liquid phase. Specifically, after obtaining the above mixed solution, the mixed solution may be filtered to separate the solids and the solution.

[0080] In one embodiment, the solid-liquid separation step is a step of filtering solids, which may be performed using a membrane filter, filter paper, vacuum filtration device, pressure filtration device, etc., but is not limited thereto. By including the filtration step, the purity of the mixed solution can be improved, thereby improving the quality of the lithium adsorbent finally produced, which is desirable.

[0081] In one embodiment, the step of drying the solid separated from the liquid may be performed at a temperature of 50 to 150 ℃. Specifically, the drying step may be performed at a temperature of 60 to 100 ℃. By performing drying within the aforementioned temperature range, the solution remaining in the solid can be easily removed. Furthermore, when the temperature of the drying step satisfies the above range, the composition of the adsorbent does not change, and a lithium adsorbent with excellent adsorption performance can be manufactured.

[0082] The step of adding an acid solution with a pH in the range of 5 to 10 to the solid can be formed by mixing an acid solution with a pH of 3 or lower and a basic solution with a pH of 10 or higher. Specifically, the method may include a step of mixing an acid solution and a basic solution to add the solid to an acid solution in the neutral range. By acid treating the solid, spacers can be placed within the lithium adsorbent so that the structure can be maintained even in a high-temperature environment; however, if acid treatment is not performed on the solid, the spacers are not formed, and there is a problem that the structure of the lithium adsorbent collapses under harsh conditions.

[0083] In one embodiment, the acid solution may be obtained by neutralizing phosphoric acid and sodium hydroxide. Specifically, when the solid is treated at a very low or very high pH level, H2O is generated in the lithium adsorbent during the acid treatment process, and the H2O undergoes an acid-catalyzed dehydration condensation reaction, and if two OH groups are reduced to only one O and the entire OH layer is condensed, there is a problem in that 2Al(OH)3 is reduced to only Al2O2(OH)2 in equivalent terms, resulting in the formation of AlOOH.

[0084] In one embodiment, after the step of adding an acid solution with a pH in the range of 5 to 10 to the solid, the method may include the step of drying the solid at 150°C or higher. The drying step may be a step of more easily placing spacers in the interlayer structure after the acid mixing step. Specifically, high energy is required to place, for example, PO4 in the interlayer structure, and the step of drying the solid at 150°C or higher may be a step of supplying said energy.

[0085] The drying step may be performed at 150 to 300 ℃, specifically 150 to 250 ℃, more specifically 180 to 220 ℃. For example, a pressure vessel may be used for the drying step to prevent H2O from escaping.

[0086]

[0087] Preferred embodiments and comparative examples of the present invention are described below. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0088]

[0089] Experimental Example 1: Whether or not a spacer is included

[0090] <Example 1>

[0091] 1.45 mol of water-soluble aluminum salt AlCl3·6H2O was dissolved in 1 kg of water. Then, 4.35 mol of powdered NaOH was slowly added over 30 minutes. The temperature was maintained at 20 ℃. Subsequently, 4 kg of water and 0.72 mol of LiCl were added, and the mixture was reacted at 80 ℃ for 2 hours.

[0092] The reaction product that underwent the aforementioned reaction was filtered using a filter press. Subsequently, the filtrate was dried at 80°C for at least 8 hours.

[0093] A dilute sodium phosphate solution was added to the dried solid. The dilute sodium phosphate solution refers to a solution prepared by neutralizing phosphoric acid (H3PO4) with sodium hydroxide (NaOH) to adjust the pH to approximately 8, and then diluting it 25 times with distilled water. At this time, 25 ml of the dilute sodium phosphate solution was added per 100 g of the dried solid, and the mixture was dried at 200 ℃ for at least 12 hours to produce the lithium adsorbent of the present invention.

[0094]

[0095] <Comparative Example 1> - Case without phosphoric acid (general aluminum-based)

[0096] 1.45 mol of water-soluble aluminum salt AlCl3·6H2O was dissolved in 1 kg of water. Then, 4.35 mol of powdered NaOH was slowly added over 30 minutes. The temperature was maintained at 20 ℃. Subsequently, 4 kg of water and 0.72 mol of LiCl were added, and the mixture was reacted at 80 ℃ for 2 hours.

[0097] The reaction product that underwent the aforementioned reaction was filtered using a filter press. Subsequently, the filtrate was dried at 80°C for at least 8 hours.

[0098]

[0099] Experimental Example 2: Specification of Spacer Types

[0100] <Comparative Example 2> - Case where phosphoric acid was added as is (Prior Art 1)

[0101] 0.562 mol of the water-soluble aluminum salt AlCl3·6H2O was dissolved in 326 ml of water. Subsequently, 1.688 mol of powdered NaOH was slowly added over 30 minutes. The temperature was maintained at 20 ℃. Afterward, 1646 ml of water and 0.281 mol of LiCl were added, and the mixture was reacted at 80 ℃ for 2 hours.

[0102] The reactant that underwent the aforementioned reaction was filtered using a filter press. Subsequently, the filtrate was dried by performing a hydrothermal reaction at 80°C for 8 hours.

[0103] A lithium adsorbent was prepared by adding 0.33 g of phosphoric acid and 8.2 g of water to 35.5 g of dried solid, and then performing a hydrothermal reaction at 200 ℃ for 6 hours.

[0104]

[0105] <Comparative Example 3> - Case where phosphorus chloride was added (Prior Art 2)

[0106] 0.562 mol of the water-soluble aluminum salt AlCl3·6H2O was dissolved in 326 ml of water. Subsequently, 1.688 mol of powdered NaOH was slowly added over 30 minutes. The temperature was maintained at 20 ℃. Afterward, 1646 ml of water and 0.281 mol of LiCl were added, and the mixture was reacted at 80 ℃ for 2 hours.

[0107] A step of filtering the reactant obtained from the aforementioned reaction was performed using a filter press. Subsequently, a step of drying the filtrate at 80°C for 8 hours was performed to produce a solid lithium adsorbent.

[0108] 5 g of polystyrene was dissolved in 250 g of dichloroethane. Then, 2.5 g of anhydrous iron chloride (FeCl3) was dissolved, and then 0.5 g of phosphorus trichloride (PCl3) was dissolved to prepare a solvent separately.

[0109] Afterwards, 20 g of the lithium adsorbent that had undergone the drying step in the above solvent was added, mixed, and then filtered to produce a lithium adsorbent.

[0110]

[0111] Evaluation Example 1: XRD Pattern

[0112] The lithium adsorbents prepared according to the examples and comparative examples were analyzed by XRD. Specifically, the lithium adsorbents prepared according to the examples and comparative examples were immersed in distilled water at 85°C for 24 hours, and the XRD patterns before and after immersion were analyzed.

[0113] FIG. 2 is a graph showing the interlayer spacing of a lithium adsorbent according to an embodiment and a comparative example of the present invention.

[0114] Referring to Figure 2, the interlayer spacing of the lithium adsorbent was determined by using the XRD 2 theta, derived from the result of Bragg's law, nλ=2d*sin(theta), and by converting d using the Cu Ka1 wavelength of 1.540 Å.

[0115] When comparing Example 1, a lithium adsorbent containing a spacer, with Comparative Example 1, a lithium adsorbent not containing a spacer at all, it can be confirmed that the rightmost peaks are approximately 7.7 Å and approximately 7.5 Å, respectively. Generally, the interlayer spacing (which is half the c-direction lattice constant) of the LiCl·2Al(OH)3·0.25H2O structure is 7.15 to 7.40 Å, and it can be confirmed that the interlayer spacing of Example 1 is considerably wide. In addition, the interlayer spacing of gibbsite is approximately 4.8 Å and that of boehmite is approximately 6.1 Å, but it can be confirmed that only Comparative Example 1 exhibited a peak around approximately 4.8 Å.

[0116] FIGS. 3 to 6 show the XRD patterns of a lithium adsorbent according to an embodiment and a comparative example of the present invention.

[0117] FIG. 3 is the XRD pattern of a lithium adsorbent according to Example 1, FIG. 4 is Comparative Example 1, FIG. 5 is Comparative Example 2, and FIG. 6 is Comparative Example 3.

[0118] Referring to Fig. 3, when the lithium adsorbent prepared from Example 1 was immersed in distilled water at 85°C for 24 hours, the position of the first peak in the XRD pattern was confirmed to be 11.46 (2θ) before immersion and 11.42 (2θ) after immersion. When the interlayer spacing was calculated from the XRD pattern, it was confirmed to be 7.71 Å before immersion and 7.74 Å after immersion.

[0119] Examining the ratio of peak heights appearing at 11 to 11.6 (2θ) and 20 to 21 (2θ) in the XRD pattern, it was confirmed to be 0.409 before immersion and 0.447 after immersion. Quantification from the XRD pattern indicates that before immersion, LiAl2(OH)6Cl(H2O) 1.099 It is 100%, and even after immersion, LiAl2(OH)6Cl(H2O) 1.099 It was confirmed that it was 100%.

[0120] Referring to Fig. 4, when the lithium adsorbent prepared from Comparative Example 1 was immersed in distilled water at 85°C for 24 hours, the position of the first peak in the XRD pattern was confirmed to be 11.70 (2θ) before immersion and 11.66 (2θ) after immersion. When the interlayer spacing was calculated from the XRD pattern, it was confirmed to be 7.55 Å before immersion and 7.58 Å after immersion.

[0121] Examining the ratio of peak heights appearing at 11 to 11.6 (2θ) and 20 to 21 (2θ) in the XRD pattern, it was confirmed to be 0.343 before immersion and 0.627 after immersion. Quantification from the XRD pattern indicates that before immersion, LiAl2(OH)6Cl(H2O) 1.099 It is 100%, and after immersion, LiAl2(OH)6Cl(H2O) 1.099 It was confirmed that it is 58.6% and Al(OH)3 is 41.2%.

[0122] Referring to Fig. 5, when the lithium adsorbent prepared from Comparative Example 2 was immersed in distilled water at 85°C for 24 hours, the position of the first peak in the XRD pattern was confirmed to be 11.46 (2θ) before immersion and 11.42 (2θ) after immersion. When the interlayer spacing was calculated from the XRD pattern, it was confirmed to be 7.71 Å before immersion and 7.74 Å after immersion.

[0123] Examining the ratio of peak heights appearing at 11 to 11.6 (2θ) and 20 to 21 (2θ) in the XRD pattern, it was confirmed to be 0.255 before immersion and 0.426 after immersion. Quantification from the XRD pattern indicates that before immersion, LiAl2(OH)6Cl(H2O) 1.099 Ga is 74.3%, AlOOH is 26.4%, and after immersion, LiAl2(OH)6Cl(H2O) 1.099 It was confirmed that it is 75.1% and AlOOH is 25.4%.

[0124] Referring to Fig. 6, when the lithium adsorbent prepared from Comparative Example 3 was immersed in distilled water at 85°C for 24 hours, the position of the first peak in the XRD pattern was confirmed to be 11.54 (2θ) before immersion and 11.46 (2θ) after immersion. When the interlayer spacing was calculated from the XRD pattern, it was confirmed to be 7.66 Å before immersion and 7.71 Å after immersion.

[0125] Examining the ratio of peak heights appearing at 11 to 11.6 (2θ) and 20 to 21 (2θ) in the XRD pattern, it was confirmed to be 0.442 before immersion and 3.429 after immersion. Quantification from the XRD pattern indicates that before immersion, LiAl2(OH)6Cl(H2O) 1.099 It was confirmed that the amount was 100%, and after immersion, the amount of Al(OH)3 was 100%.

[0126] Table 1 below shows the XRD pattern, interlayer spacing, presence or absence of Al(OH)3 and AlOOH, and adsorbent fraction according to the embodiments and comparative examples of the present invention.

[0127] Specifically, based on the XRD patterns of Figures 3 to 6, the interlayer spacing, the presence or absence of Al(OH)3 and AlOOH were calculated, and the adsorbent fraction was also measured. Specifically, since 2 theta(θ) of the XRD is the result of Bragg's law, nλ=2d*sin(theta), the interlayer spacing was confirmed by converting it to d using the Cu Ka1 wavelength of 1.540 Å.

[0128] Acid Solution pH XRD Characteristics Product Features Left Peak* Interlayer Interval Peak Ratio** Before Immersion (2θ) After Immersion (2θ) Before Immersion (Å) After Immersion (Å) Before Immersion After Immersion Presence / Absence of Al(OH)3 [%] Presence / Absence of AlOOH Adsorbent Fraction Example 1 8.0 11.46 11.42 7.717.74 0.40 90.44 7--100 Comparative Example 1 -11.70 11.66 7.55 7.58 0.34 30.62 74 1.2-58.6 Comparative Example 2 1.0 11.46 11.42 7.717.74 0.25 50.426 -25.47 5.1 Comparative Example 3 -11.54 11.46 7.66 7.71 0.44 23.42 9100-0 *Left Peak: Among XRD patterns First peak from the left** Peak ratio: Refers to the ratio of the second peak to the first peak (First peak: peak values ​​at 11-11.6 2θ, Second peak: peak values ​​at 20-21 2θ)

[0129] Referring to Table 1, and referring to Example 1 and Comparative Example 1, it was confirmed that depending on the presence or absence of a spacer, a layer spacing sufficient to enable the adsorption of Li or Cl at high temperatures is maintained, and it was confirmed that Al(OH)3 and AlOOH, which cause structural changes in the adsorbent, are not formed. Furthermore, looking at Example 1, Comparative Example 2, and Comparative Example 3, in the case of Example 1, which includes PO4 as the type of spacer, it was confirmed that compared to Comparative Example 2 and Comparative Example 3, the peak ratio satisfies the range of the present invention, the layer spacing is large, and Al(OH)3 and AlOOH are not formed. Figure 7 is a schematic diagram of the manufacturing process of a lithium adsorbent according to a comparative example of the present invention.

[0130] Figure 7 is a schematic diagram of the manufacturing process of a lithium adsorbent prepared according to Comparative Example 1. Specifically, referring to Comparative Example 1, Li in LiCl enters the gaps of the Al layer, while Cl enters between the layers. Al(OH)3 has a structure similar to Mg(OH)2, and since Al, a trivalent cation, replaces Mg, a divalent cation, charge balance is achieved by filling only 2 / 3 of the metal sites, leaving the remaining 1 / 3 empty. Li enters the empty space of the 1 / 3, and since it is difficult for other metals to enter that space, it can possess Li selectivity.

[0131] At this time, as LiCl is inserted, large Cl ions enter between the layer structures, increasing the interlayer spacing. To form this structure, the structure is changed into a lithium adsorbent (LDH) by reacting at 80°C for 2 hours under conditions of high LiCl concentration.

[0132] However, in the case of LiCl, since it is not chemically bonded, there is a problem where Li and Cl detach if an external environment with low levels of Li or Cl is maintained. Since the aforementioned adsorbent manufacturing process is required for the detached Li and Cl to be reinserted into the lithium adsorbent, there is a problem in that they cannot spontaneously return to the lithium adsorbent structure during the adsorption-desorption process, which is difficult for additional bonding due to lower Li concentrations or high flow rates.

[0133] Therefore, it can be confirmed that the rate of transformation into Al(OH)3 (Gibbsite structure) gradually increases.

[0134] FIG. 8 is a schematic diagram of the manufacturing process of a lithium adsorbent according to an embodiment of the present invention.

[0135] FIG. 8 is a schematic diagram of the manufacturing process of a lithium adsorbent according to Example 1. Specifically, referring to Example 1, if an additional acid treatment step is included in Comparative Example 1, PO4 or SO4 does not easily dissociate because they form very strong bonds with the OH of Al(OH)3. Specifically, PO is a chemical bond, and the O of PO4 and the H of Al(OH)3 form hydrogen bonds, so they do not easily dissociate. In addition, since the size of PO4 or SO4 is larger than that of Cl, the interlayer spacing is maintained even if Cl is detached due to their introduction. As the interlayer spacing is maintained, the adsorption function is maintained again even if Li or Cl is supplied.

[0136] Therefore, it can be confirmed that they possess stability even under low-concentration, high-temperature conditions where Li and Cl are prone to dissociation.

[0137] FIG. 9 is a schematic diagram of the manufacturing process of a lithium adsorbent according to a comparative example of the present invention.

[0138] FIG. 9 is a schematic diagram of the manufacturing process of a lithium adsorbent according to Comparative Example 3. Specifically, referring to Comparative Example 3, when phosphoric acid is added as H3PO4, PO4 3-In addition to H + A large amount of ions is also supplied. The above hydrogen (H + The ions react with the OH of aluminum hydroxide. In this process, H2O is generated, and acid-catalyzed dehydration condensation occurs with the H2O. Two OH atoms are reduced to one O atom, and when the entire OH layer is condensed, 2Al(OH3) is reduced to only Al2O2(OH)2, which remains as AlOOH based on the chemical formula.

[0139] In this way, regarding the layer structure, it was confirmed that the two layers were reduced to one layer, PO4 was detached, and Li and Cl were also difficult to retain.

[0140] Referring again to FIGS. 7 to 9, it was confirmed that in the case of a lithium adsorbent, when a Gibbsite structure or AlOOH is formed, an excessively large change occurs in the structure, and consequently, the adsorption of Li and Cl is not easy. In the present invention, it was confirmed that structural stability can be maintained at high temperatures by manufacturing a lithium adsorbent without a Gibbsite structure or AlOOH.

[0141]

[0142] Evaluation Example 2: Adsorbent structure retention test under harsh conditions

[0143] Adsorbent: Structural changes were confirmed by immersing the adsorbent in a lithium-containing solution at a ratio of 1:100 for 8 hours for 3 days. The crystalline phase of the structural changes was confirmed using an XRD pattern.

[0144] Conditions: Room temperature, total 3 days; 60℃ 8hr / d, total 3 days; 85℃ 8hr / d, total 3 days Example 1: Distilled water LDH 100% LDH 100% LDH 100% Li 0.15 g / LLDH 100% LDH 100% LDH 100% Li 0.50 g / LLDH 100% LDH 100% LDH 100% Li 1.00 g / LLDH 100% LDH 100% LDH 100% Comparative Example 1: Distilled water LDH 100% LDH 100% LDH 58.6% Al(OH)3 41.2% Li 0.15 g / LLDH 100% LDH 100% LDH 80.3% Al(OH)3 19.9% ​​Li 0.50 g / LLDH 100% LDH 100%LDH 100%Li 1.00 g / LLDH 100%LDH 100%LDH 100%Comparative example 2 Distilled waterLDH 47.1%, AlOOH 50.3%Al(OH)32.7%LDH 57.4%,AlOOH 38.4%Al(OH)34.3%LDH 48.1%,AlOOH 39.6%Al(OH)312.4%Li 0.15 g / LLDH 82.3%,AlOOH 16.7%Al(OH)31.1%LDH 76.8%,AlOOH 23.1%Al(OH)30.3%LDH 41.8%,AlOOH 52.3%Al(OH)37.4%Li 0.50 g / LLDH 69.1%, AlOOH 30.4%Al(OH)31.3%LDH 76.7%,AlOOH 22.7%Al(OH)30.7%LDH 50.5%,AlOOH 45.2%Al(OH)34.3%Li 1.00 g / LLDH 48.7%,AlOOH 46.2%Al(OH)35.2%LDH 77.8%,AlOOH 22.3%Al(OH)30.2%LDH 67.0%,AlOOH 32.4%Al(OH)31.3%Comparative Example 3Distilled waterLDH 74.3%,AlOOH 26.3%LDH 68.3%,AlOOH 32.4%LDH 75.1%,AlOOH 25.4%Li 0.15 g / LLDH 75.1%,AlOOH 25.0%LDH 89.7%,AlOOH 10.3%LDH 93.4%,AlOOH 6.6%Li 0.50 g / LLDH 65.4%,AlOOH 35.8%LDH 72.9%,AlOOH 27.6%LDH 98.0%,AlOOH 2.0%Li 1.00 g / LLDH 91.3%, AlOOH 9.3%LDH 77.7%,AlOOH 22.5%LDH 82.5%,AlOOH 18.5%.

[0145] Referring to Table 2 above, the results of the examination on the potential for degradation due to long-term use of the lithium adsorbent under harsh conditions were confirmed. It was confirmed that Comparative Example 1 undergoes a change in crystal structure at 85°C. It was confirmed that Comparative Example 2 has a high Al(OH)3 content of 12.4% at 85°C. It was confirmed that Comparative Example 3 undergoes a change in structure due to the formation of AlOOH at 85°C. In contrast, it was confirmed that Example 1 maintains the structure of LDH even at high temperatures. The present invention is not limited to the above examples but can be manufactured in various different forms, and those skilled in the art will understand that the present invention can be implemented in other specific forms without altering the technical concept or essential features of the invention. Therefore, the examples described above should be understood as illustrative in all respects and not restrictive.

Claims

1. Includes a layered double hydroxide (LDH) composed of an aluminum-based material, and A lithium adsorbent comprising spacers between the layers of the above double-layer hydroxide.

2. In Paragraph 1, When the above lithium adsorbent was immersed in 85°C distilled water for 24 hours, A lithium adsorbent satisfying the following Equation 2. <Equation 2> 0.430 ≤ I2 / I1 ≤ 0.600 (In Equation 2 above, I1 and I2 represent the peak intensities at XRD peak values ​​when 2θ is 11–11.6 and when 2θ is 20–21, respectively.) 3. In Paragraph 1, A lithium adsorbent whose XRD peak value satisfies Equation 1 below. <Equation 1> 0.350 ≤ I2 / I1 ≤ 0.440 (In Equation 1 above, I1 and I2 represent the peak intensities at XRD peak values ​​when 2θ is 11–11.6 and when 2θ is 20–21, respectively.) 4. In Paragraph 1, The above spacer is a lithium adsorbent comprising at least one salt among phosphate, sulfate, hydrochloride, and nitrate.

5. In Paragraph 1, The above spacer is a lithium adsorbent containing PO4.

6. In Paragraph 1, A lithium adsorbent having a layer spacing of 7.6 to 7.9 Å for the above double-layer hydroxide.

7. In Paragraph 6, When the above lithium adsorbent was immersed in 85°C distilled water for 24 hours, A lithium adsorbent having a layer spacing of 7.6 to 7.9 Å for the above double-layer hydroxide.

8. In Paragraph 1, A lithium adsorbent in which the layer spacing of the above double-layer hydroxide is 4.7 to 4.9 Å and the layer spacing is 6.0 to 6.2 Å, each in an amount of 5% or less based on 100% of the lithium adsorbent.

9. In Paragraph 1, Lithium adsorbent not containing Al(OH)3 and AlOOH.

10. In Paragraph 1, A lithium adsorbent represented by the following chemical formula 1. [Chemical Formula 1] Li·Al x (OH) y AnH2O (In the above chemical formula 1, A is F - , Cl - , Br - , NO3 - , HCO3 - , and OH - At least one of the following, and 0 <x<5, 0<y<15, 및 0<n<10이다) 11. A step of obtaining a mixed solution by mixing an aluminum-based raw material, sodium hydroxide, and a lithium-based raw material; A step of separating solids from the above mixed solution; and A step of adding an acid solution with a pH in the range of 5 to 10 to the above solid; A method for manufacturing a lithium adsorbent comprising 12. In Paragraph 11, The step of obtaining a mixed solution by mixing an aluminum-based raw material, sodium hydroxide, and a lithium-based raw material is, A step of dissolving the above aluminum-based raw material and sodium hydroxide in water or brine; and A method for manufacturing a lithium adsorbent comprising the step of adding the lithium-based raw material to a dissolved mixed aqueous solution.

13. In Paragraph 11, A method for manufacturing a lithium adsorbent in which an acidic solution with a pH in the range of 5 to 10 is formed by mixing an acidic solution with a pH of 3 or lower and a basic solution with a pH of 10 or higher.

14. In Paragraph 13, A method for manufacturing a lithium adsorbent in which the above acid solution is obtained by neutralizing phosphoric acid and sodium hydroxide.

15. In Paragraph 12, The step of dissolving the above aluminum-based raw material and sodium hydroxide in water or brine is, A method for manufacturing a lithium adsorbent performed at a temperature of 40 ℃ or lower.

16. In Paragraph 11, A method for manufacturing a lithium adsorbent in which the molar ratio of sodium hydroxide to the aluminum-based raw material (mol of sodium hydroxide / mol of aluminum-based raw material) is 1.5 to 5.

5.

17. In Paragraph 11, The step of separating solids from the above mixed solution is, A step of separating the above mixed solution into solid and liquid phases; and A step of drying the above-mentioned solid material separated into solid and liquid forms; A method for manufacturing a lithium adsorbent comprising 18. In Paragraph 17, A method for manufacturing a lithium adsorbent in which the step of drying the above solid is performed at 60 to 150 ℃.

19. In Paragraph 11, After the step of adding an acid solution with a pH in the range of 5 to 10 to the above solid, A method for manufacturing a lithium adsorbent comprising the step of drying the above solid at 150°C or higher.

20. In Paragraph 11, A method for manufacturing a lithium adsorbent comprising one or more aluminum salts selected from the group consisting of aluminum chloride, aluminum sulfate, and aluminum acetate.

Images