Metal oxygen anion doped aluminum lithium extraction adsorbent as well as preparation method and application thereof

Abstract

The invention provides a metal oxygen anion doped aluminum lithium extraction adsorbent and a preparation method and application thereof, and particularly relates to the technical field of lithium adsorbents. In the metal oxygen negative ion doped aluminum lithium extraction adsorbent, the aluminum lithium extraction adsorbent has a lithium aluminum hydrotalcite structure, and metal oxygen negative ions are doped in plate layers and interlayers of the lithium aluminum hydrotalcite structure; the metal oxygen negative ions are composite negative ions composed of metal elements and oxygen atoms. The metal oxygen negative ion doped aluminum lithium extraction adsorbent can still keep the normal-temperature adsorption capacity of 93% or above under the low-temperature condition of-5 DEG C, the normal-temperature adsorption capacity retention rate of the metal oxygen negative ion doped aluminum lithium extraction adsorbent is remarkably superior to that of an undoped material of 63.9%, and finally the low-temperature applicability and high adsorption performance of the material are synergistically improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium adsorbent preparation, in particular to a metal-oxygen negative ion doped aluminum lithium extraction adsorbent and a preparation method and application thereof. BACKGROUND

[0002] Lithium, as a key metal element in the modern energy system, plays an irreplaceable strategic role in the fields of new energy vehicles, large-scale energy storage systems, consumer electronics, and aerospace. With the acceleration of the global energy structure towards low-carbon transformation, the demand for lithium resources continues to rise, and has become one of the strategic mineral resources. At present, global lithium resources are mainly hosted in three geological types: salt lake type (brine lithium), pegmatite type (such as spodumene), and sedimentary rock type (such as lepidolite). Among them, salt lake brine type lithium resources account for about 70% of the total global reserves, and are the main source of future lithium supply in China and even the world.

[0003] China has abundant salt lake resources, mainly concentrated in basins and high-altitude areas such as plateaus. These areas are generally characterized by low lithium concentration, high magnesium-lithium ratio, and extreme climate conditions, which pose great challenges to lithium extraction processes. Among the many lithium extraction technology routes, adsorption method is considered one of the most promising technology paths for typical high magnesium-lithium ratio salt lakes in China due to its good adaptability to complex brine systems, high selectivity, low energy consumption, environmental friendliness, and ease of continuous operation.

[0004] In the adsorption method lithium extraction technology, aluminum-based lithium ion adsorbent, especially materials based on lithium aluminum layered double hydroxide (LiAl-LDHs) structure, has become the only salt lake lithium extraction adsorbent system currently achieving industrial application due to its simple synthesis process, low cost, strong reversibility of adsorption-desorption process, and good cycle stability.

[0005] However, although existing aluminum-based adsorbents exhibit certain lithium extraction capacity at room temperature, they still face significant technical bottlenecks in actual application scenarios, especially in the low-temperature environment widely existing in the high-cold regions of western China. Research data shows that in the environment below 0℃, the lithium adsorption capacity of conventional LiAl-LDHs generally decreases by 20%~40%, and the adsorption rate also slows down significantly, which seriously restricts the production efficiency in winter and the annual capacity utilization rate.

[0006] In view of this, the present application is proposed. SUMMARY

[0007] The present application aims to provide a metal-oxygen negative ion doped aluminum lithium extraction adsorbent and a preparation method and application thereof, which aims to solve at least one of the above technical problems in the prior art.

[0008] In order to achieve the above object of the present application, the following technical solutions are adopted: The first aspect of the present application provides a metal-oxygen anion doped aluminum lithium extraction adsorbent, the aluminum lithium extraction adsorbent has a lithium aluminum hydrotalcite structure, and the metal-oxygen anion is doped in the plate layer and the interlayer of the lithium aluminum hydrotalcite structure; the metal-oxygen anion is a complex anion composed of a metal element and an oxygen atom.

[0009] Further, the metal element includes W, Mo, Mn, Fe, Cr, Ti or Co.

[0010] Preferably, the metal-oxygen anion includes at least one of WO4 2- , MnO4 - , FeO4 2- , TiO3 2- , CrO4 2- , CoO4 2- , [PMo 12 O 40 ] 3- .

[0011] Further, the doping amount of the metal-oxygen anion is 0.4-10wt%.

[0012] The second aspect of the present application provides a preparation method of the metal-oxygen anion doped aluminum lithium extraction adsorbent, comprising the following steps: A. dissolving a soluble lithium source and a soluble aluminum source in water to obtain a first solution; dissolving a soluble metal-oxygen anion source in water to obtain a second solution; B. mixing the first solution and the second solution to obtain a precursor solution; C. keeping stirring, and adding lye into the precursor solution until the pH value reaches 6.0-10.0, continuing to stir to perform aging, and obtaining a white slurry; D. transferring the white slurry into a reaction kettle to perform hydrothermal reaction, cooling, washing and drying after completion to obtain the metal-oxygen anion doped aluminum lithium extraction adsorbent.

[0013] Further, the soluble lithium source includes at least one of lithium chloride, lithium nitrate, lithium sulfate, lithium carbonate and lithium hydroxide.

[0014] Preferably, the soluble aluminum salt includes at least one of aluminum chloride, aluminum nitrate and aluminum sulfate.

[0015] Preferably, the soluble metal-oxygen anion source includes at least one of sodium tungstate, potassium permanganate, sodium ferrate, sodium titanate, titanium acid and phosphomolybdic acid.

[0016] Preferably, the concentration of the aluminum source in the first solution is 2~10 mol / L.

[0017] Preferably, the molar ratio of the lithium source to the aluminum source is (0.4~1):1.

[0018] Preferably, the molar ratio of the metal oxygen negative ion source to the aluminum source is (0.01~0.2):1, calculated by metal element.

[0019] Preferably, the second solution also includes an alkaline compound.

[0020] Preferably, the alkaline compound includes at least one of sodium hydroxide, lithium hydroxide, sodium carbonate, and ammonia.

[0021] Further, in step C, the alkali in the alkaline solution includes at least one of sodium hydroxide, lithium hydroxide, sodium carbonate, and ammonia.

[0022] Preferably, the concentration of the alkaline solution is 0.5~10 mol / L.

[0023] Preferably, the aging time is 0.5 to 2 hours.

[0024] Furthermore, the hydrothermal reaction is carried out at a temperature of 90~180℃ for a time of 6~48h.

[0025] Furthermore, in step D, the lining of the reactor is made of polytetrafluoroethylene.

[0026] Furthermore, in step D, the drying temperature is 60~120℃.

[0027] Preferably, the preparation method further includes a pulverization process after drying.

[0028] The third aspect of this invention provides the application of the aforementioned metal oxygen anion-doped aluminum-based lithium extraction adsorbent in the field of low-temperature lithium extraction, wherein the low-temperature lithium extraction temperature is <0℃.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects: The metal-oxygen negative ion doped aluminum lithium extraction adsorbent provided by the application realizes multiple performance optimization through the introduction of metal-oxygen negative ions. On the one hand, the strong electronegativity of the metal-oxygen negative ions can enhance the electrostatic interaction between the layer and the lithium ions, effectively reduce the activation energy required for the dehydration of lithium ions from the hydrated state to the naked ion, and thus alleviate the problem of blocked dehydration kinetics at low temperatures. On the other hand, after the large-size characteristic of the metal-oxygen negative ions is inserted between the layers, the material layer spacing can be expanded, the ion transmission channel can be optimized, and thus the diffusion resistance of lithium ions in a high-viscosity environment at low temperatures can be reduced and the mass transfer efficiency can be improved. At the same time, the metal-oxygen negative ions can also stabilize the layered structure of the material and improve the cycle stability. The doped adsorbent can still maintain an adsorption capacity of more than 93% at a low temperature of -5 DEG C, which is significantly better than the adsorption capacity retention rate of 63.9% of the undoped material at room temperature, and finally realizes the synergistic improvement of the low-temperature applicability and high adsorption performance of the material.

[0030] The preparation method provided by the application realizes the uniform doping and stable intercalation of metal-oxygen negative ions in the layer and interlayer of lithium aluminum hydrotalcite by blending raw materials and using alkaline solution for controllable co-precipitation, combined with hydrothermal crystallization and post-processing technology. The method is simple in process, mild in conditions, good in repeatability, and easy to realize industrialization.

[0031] The application provided by the application ensures the stable operation of the low-temperature lithium extraction process from the material level, solves the technical bottleneck of difficult lithium extraction in the "winter rest period" of high-cold area salt lakes, breaks the seasonal limitation of lithium extraction projects, and significantly improves the all-year operability of salt lake lithium extraction. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the present application clearer, the following will describe the technical solutions in the embodiments of the present application in conjunction with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application.

[0033] In the following, the terms "include", "have", and their synonymous words used in various embodiments of the present application are only intended to indicate specific features, numbers, steps, operations, elements, components, or combinations of the foregoing, and should not be understood as excluding the existence or possibility of adding one or more features, numbers, steps, operations, elements, components, or combinations of the foregoing.

[0034] A first aspect of the present application provides a metal-oxygen negative ion doped aluminum lithium extraction adsorbent, the aluminum lithium extraction adsorbent has a lithium aluminum hydrotalcite structure, and the metal-oxygen negative ion is doped in the layer and interlayer of the lithium aluminum hydrotalcite structure; the metal-oxygen negative ion is a composite anion composed of a metal element and an oxygen atom.

[0035] The metal oxyanion doped aluminum lithium extraction adsorbent provided by the application realizes multiple performance optimization through the introduction of metal oxyanions. On the one hand, the strong electronegativity of the metal oxyanions can enhance the electrostatic interaction between the layer and the lithium ions, effectively reduce the activation energy required for the dehydration of lithium ions from the hydrated state to the naked ion, and thus alleviate the problem of blocked dehydration kinetics at low temperatures; on the other hand, after the large size characteristics of the metal oxyanions are inserted between the layers, the material layer spacing can be expanded, the ion transmission channel can be optimized, and thus the diffusion resistance of lithium ions in a high-viscosity environment at low temperature can be reduced and the mass transfer efficiency can be improved. At the same time, the metal oxyanions can also stabilize the layered structure of the material and improve the cycle stability. The doped adsorbent can still maintain an adsorption capacity of more than 93% at room temperature under the condition of low temperature of -5℃, which is significantly better than the room temperature adsorption capacity retention rate of 63.9% of the undoped material, and finally realizes the synergistic improvement of the low-temperature applicability and high adsorption performance of the material.

[0036] Further, the metal element includes W, Mo, Mn, Fe, Cr, Ti or Co.

[0037] Preferably, the metal oxyanion includes at least one of WO4 2- , MnO4 - , FeO4 2- , TiO3 2- , CrO4 2- , CoO4 2- , [PMo 12 O 40 ] 3-

[0038] Further, the doping amount of the metal oxyanion is 0.4-10wt%.

[0039] Typically but not limitedly, the doping amount of the metal oxyanion may be, for example, 0.4wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%, or any value within the range of 0.4-10wt%.

[0040] The second aspect of the application provides a preparation method of the metal oxyanion doped aluminum lithium extraction adsorbent, comprising the following steps: A. dissolving a soluble lithium source and a soluble aluminum source in water to obtain a first solution; dissolving a soluble metal oxyanion source in water to obtain a second solution; B. mixing the first solution and the second solution to obtain a precursor solution; ​C. Keep stirring, and add alkali solution into the precursor solution until the pH value reaches 6.0-10.0, and continue to stir to age, to obtain a white slurry; D. Transfer the white slurry into a reaction kettle to perform hydrothermal reaction, and after completion, cool, wash and dry to obtain the metal-oxygen anion doped aluminum lithium extraction adsorbent.

[0041] The preparation method provided by the application realizes uniform doping and stable intercalation of metal-oxygen anions in the layers and interlayers of lithium-aluminum hydrotalcite by blending raw materials, controllable co-precipitation with alkali solution, hydrothermal crystallization and post-processing.

[0042] In step C, the pH value of the precursor solution is adjusted to 6.0-10.0 by adding alkali solution to create a suitable reaction environment, so as to promote the co-precipitation reaction of metal ions in the lithium source, aluminum source and metal-oxygen anion source, and form precursor particles with the basic structure of layered double hydroxide (LiAl-LDHs); under continuous stirring, the crystal nucleus of the precipitated particles can grow fully, the crystallinity can be improved, and the metal-oxygen anions can be more uniformly doped or intercalated into the layer structure and interlayer region of hydrotalcite, so that a white slurry with uniform composition and stable structure is obtained, which lays a good foundation for the subsequent hydrothermal crystallization process.

[0043] In step D, the white slurry is subjected to hydrothermal reaction in a sealed reaction kettle, the high-temperature and high-pressure conditions are used to promote the further crystallization and structural rearrangement of the precursor, the layered structure of lithium-aluminum hydrotalcite is more complete and ordered, and the interaction between the metal-oxygen anions and the layer plate is enhanced, so that the stable doping and uniform distribution of the metal-oxygen anions in the layers and interlayers are realized; the hydrothermal process can also effectively regulate the crystallinity, particle morphology and interlayer spacing of the material, and optimize its physical and chemical properties. After the reaction is completed, impurity ions are removed by cooling and washing, and then the metal-oxygen anion doped aluminum lithium extraction adsorbent powder with stable structure and high purity is obtained by drying, so that the low-temperature adsorption performance and cycle stability of the material are significantly improved.

[0044] Further, the soluble lithium source includes at least one of lithium chloride, lithium nitrate, lithium sulfate, lithium carbonate and lithium hydroxide.

[0045] Preferably, the soluble aluminum salt includes at least one of aluminum chloride, aluminum nitrate and aluminum sulfate.

[0046] Preferably, the soluble metal-oxygen anion source includes at least one of sodium tungstate, potassium permanganate, sodium ferrate, sodium titanate, titanic acid and phosphomolybdic acid.

[0047] Preferably, the concentration of the aluminum source in the first solution is 2-10 mol / L. Typically but not exclusively, the concentration may, for example, be 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L or 10 mol / L, or any value within the range of 2-10 mol / L.

[0048] Preferably, the molar ratio of the lithium source to the aluminum source is (0.4-1):1. Typically but not exclusively, the molar ratio may, for example, be 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1:1, or any value within the range of 0.4-1:1.

[0049] Preferably, the molar ratio of the metal oxyanion source to the aluminum source, in terms of metal elements, is (0.01-0.2):1. Within this molar ratio range, effective doping of metal oxyanions into the lithium-aluminum hydrotalcite structure can be achieved, while avoiding excessive doping that would damage the main structure of the material. This ratio range can ensure sufficient metal oxyanions into the layer or interlayer to enhance the lithium ion adsorption capacity by its strong electronegativity, expand the interlayer spacing to improve the ion transport channel, and improve the adsorption kinetics performance of the material at low temperature; it can also prevent lattice distortion, phase separation or hinder the formation of hydrotalcite ordered layered structure due to excessive doping, thereby ensuring the material has good crystallinity, structural stability and cycle performance, achieving the synergistic optimization of low-temperature applicability and high adsorption capacity.

[0050] Typically but not exclusively, the molar ratio of the metal oxyanion source to the aluminum source may, for example, be 0.01:1, 0.02:1, 0.05:1, 0.08:1, 0.1:1, 0.12:1, 0.15:1, 0.18:1 or 0.2:1, or any value within the range of 0.01-0.2:1.

[0051] Preferably, the second solution further includes an alkaline compound to prevent certain metal oxyanion sources from hydrolyzing, precipitating or being structurally unstable under acidic or neutral conditions, thereby ensuring that the metal oxyanions remain in a dissolved state and chemically stable before participating in the reaction; at the same time, the pre-introduction of alkaline substances helps to adjust the initial pH value of the overall precursor system, making the subsequent pH control process more stable and controllable, promoting the uniform progress of the coprecipitation reaction, and facilitating the more effective doping of metal oxyanions into the layer or interlayer of lithium-aluminum hydrotalcite, thereby improving the structural uniformity and doping efficiency of the material.

[0052] Preferably, the alkaline compound includes at least one of sodium hydroxide, lithium hydroxide, sodium carbonate and ammonia.

[0053] Further, in step C, the base in the base solution includes at least one of sodium hydroxide, lithium hydroxide, sodium carbonate, and ammonia water.

[0054] Preferably, the concentration of the base solution is 0.5-10 mol / L. Typically but not exclusively, the concentration may, for example, be 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, or 10 mol / L, or any value within the range of 0.5-10 mol / L.

[0055] Preferably, the aging time is 0.5-2 h. Typically but not exclusively, the time may, for example, be 0.5 h, 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h, or 2 h, or any value within the range of 0.5-2 h.

[0056] Further, the temperature of the hydrothermal reaction is 90-180℃, and the time is 6-48 h. Typically but not exclusively, the temperature of the hydrothermal reaction may, for example, be 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, or 180℃, or any value within the range of 90-180℃; the time of the hydrothermal reaction may, for example, be 6 h, 10 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, 45 h, or 48 h, or any value within the range of 6-48 h.

[0057] Further, in step D, the inner lining of the reaction kettle is polytetrafluoroethylene, which ensures the stability of the reaction system during the hydrothermal reaction, avoids the introduction of impurities or causes equipment corrosion due to the chemical reaction between metal ions or alkaline medium and the reactor; at the same time, the surface of polytetrafluoroethylene is smooth and non-adhesive, which is conducive to the complete removal of the reaction product and subsequent cleaning, reduces sample loss and cross contamination, and thus ensures the purity, structural uniformity, and experimental repeatability of the prepared metal oxyanion-doped aluminum-based lithium-adsorbing adsorbent.

[0058] Further, in step D, the drying temperature is 60-120℃. Typically but not exclusively, the temperature may, for example, be 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, or 120℃, or any value within the range of 60-120℃.

[0059] Preferably, the preparation method further includes a crushing process after drying, and the product is sieved through a 100-mesh sieve after crushing, so as to make the particle size of the product uniform, improve the flowability and packing performance of the product in actual application, and at the same time ensure stable specific surface area and ion diffusion rate in the adsorption process.

[0060] The third aspect of the present application provides the application of the metal-oxygen negative ion doped aluminum lithium extraction adsorbent in the field of low-temperature lithium extraction, and the temperature of the low-temperature lithium extraction is <0 ℃.

[0061] The application of the present application has the advantages of the metal-oxygen negative ion doped aluminum lithium extraction adsorbent, ensures the stable operation of the low-temperature lithium extraction process from the material level, solves the technical bottleneck of the difficulty of lithium extraction in the "winter rest period" of the salt lake in the alpine region, breaks the seasonal restriction of the lithium extraction project, and significantly improves the all-year operability of the salt lake lithium extraction.

[0062] The present application will be further described below through specific examples and comparative examples, but it should be understood that these examples are only for more detailed description and should not be understood as limiting the present application in any form. The raw materials used in the examples and comparative examples of the present application are prepared according to the conventional conditions or the conditions recommended by the manufacturer if no specific conditions are indicated. The reagents or instruments used are conventional products that can be purchased on the market if no manufacturer is indicated.

[0063] Example 1 This example provides a tungstate doped aluminum lithium extraction adsorbent (W-LiAl-LDHs), and the specific preparation method is as follows: 1. 24.15 g of aluminum chloride hexahydrate (AlCl3.6H2O) and 4.25 g of anhydrous lithium chloride were dissolved in 200 mL of deionized water to obtain a lithium-aluminum mixed solution; 3.3 g of sodium tungstate (Na2WO4.2H2O) was dissolved in 50 mL of deionized water, and then added to the above lithium-aluminum mixed solution, and stirred uniformly to obtain a precursor solution.

[0064] 2. Under vigorous stirring, 5 mol / L sodium hydroxide solution was slowly added dropwise, and the pH value was adjusted to 6.0 to stop the dropwise addition, and then the stirring and aging were continued at room temperature for 30 min.

[0065] 3. The obtained white slurry was transferred to a 500 mL reaction kettle, sealed, and placed in an oven at 150 ℃ for reaction for 24 h. After the reaction was completed, it was naturally cooled to room temperature, washed with pure water for 3 times, and then the filter cake after washing was placed in a 120 ℃ oven for drying for 12 h. After being ground through a 100 mesh sieve, a white powder of tungstate doped aluminum lithium extraction adsorbent was obtained and marked as W-LiAl-LDHs.

[0066] Example 2 This example provides a high-manganese doped aluminum lithium adsorbent (Mn-LiAl-LDHs), and the difference from example 1 is that 1.6 g of potassium permanganate (KMnO4) is used instead of sodium tungstate, and the remaining steps and raw materials are the same as those of example 1, which will not be described here.

[0067] Example 3 This embodiment provides a titanate-doped aluminum-based lithium adsorbent (Ti-LiAl-LDHs). The difference from Example 1 is that 0.58 g of titanic acid (H4TiO4) is used instead of sodium tungstate. The remaining steps and raw materials are the same as in Example 1, and will not be repeated here.

[0068] Example 4 This embodiment provides a ferrate-doped aluminum-based lithium adsorbent (Fe-LiAl-LDHs), and the specific preparation method is as follows: 1. Weigh 48.3g of aluminum chloride hexahydrate (AlCl3·6H2O) and 8.00g of anhydrous lithium chloride and dissolve them in 200mL of deionized water to obtain a lithium-aluminum mixture; separately, dissolve sodium ferrate (Na2FeO4) in 5 mol / L sodium hydroxide solution, mix and stir evenly to obtain an alkaline precursor solution, wherein the ferrate concentration is 2 mol / L.

[0069] 2. While stirring vigorously, slowly add 5 mol / L sodium hydroxide solution dropwise, adjust the pH value to 10.0 and stop adding. Continue stirring and aging at room temperature for 30 minutes.

[0070] 3. The obtained white slurry was transferred to a 500 mL reaction vessel, sealed, and placed in an oven at 160 °C for 12 h. After the reaction was completed, it was naturally cooled to room temperature. The product was washed three times with pure water, and the washed filter cake was dried in an oven at 120 °C for 12 h. After grinding through a 100 mesh sieve, a yellow powdery aluminum-based lithium extraction adsorbent doped with ferrate was obtained and labeled as Fe-LiAl-LDHs.

[0071] Example 5 This embodiment provides a phosphomolybdate-doped aluminum-based lithium adsorbent (PMo-LiAl-LDHs). Unlike Example 1, it uses 3.8 g of phosphomolybdic acid (H3[PMo]). 12 O 40 The remaining steps and raw materials are the same as in Example 1, and will not be repeated here.

[0072] Example 6 This embodiment provides a tungstate-doped aluminum-based lithium extraction adsorbent (W-LiAl-LDHs). The difference from Example 1 is that the amount of sodium tungstate used is 0.33g. The remaining steps and raw materials are the same as in Example 1, and will not be repeated here.

[0073] Example 7 This embodiment provides a permanganate-doped aluminum-based lithium adsorbent (Mn-LiAl-LDHs). The difference from Example 2 is that the amount of potassium permanganate used is 3.2g. The remaining steps and raw materials are the same as in Example 2, and will not be repeated here.

[0074] Example 8 This example provides a tungstate doped aluminum lithium extraction adsorbent (W-LiAl-LDHs), which is different from Example 1 in that the hydrothermal temperature in step 3 is 180°C, and the time is 6h, and the remaining steps and raw materials are the same as Example 1, which will not be repeated here.

[0075] Example 9 This example provides a tungstate doped aluminum lithium extraction adsorbent (W-LiAl-LDHs), which is different from Example 1 in that the hydrothermal temperature in step 3 is 90°C, and the time is 48h, and the remaining steps and raw materials are the same as Example 1, which will not be repeated here.

[0076] Comparative Example 1 This comparative example provides an aluminum lithium extraction adsorbent (LiAl-LDHs), which is different from Example 1 in that no sodium tungstate is added in step 1, and the lithium aluminum mixed solution is directly used as the precursor solution. The remaining raw materials and preparation methods are the same as Example 1, which will not be repeated here.

[0077] Comparative Example 2 This comparative example provides a tungstate physically doped aluminum lithium extraction adsorbent (W physically doped LiAl-LDHs), and the specific preparation method is as follows: 1. 24.15g of aluminum chloride hexahydrate (AlCl3.6H2O) and 4.25g of anhydrous lithium chloride were dissolved in 200mL of deionized water to obtain a lithium aluminum mixed solution.

[0078] 2. Under vigorous stirring, 5mol / L sodium hydroxide solution was slowly added to the lithium aluminum mixed solution, and the pH value was adjusted to 6.0 to stop the addition, and the stirring was continued at room temperature for 30min.

[0079] 3. The obtained white slurry was transferred to a 500mL reaction kettle, sealed and placed in an oven at 150°C for 24h. After the reaction was completed, it was naturally cooled to room temperature, and the product was washed with pure water for 3 times. The washed filter cake was placed in a 120°C oven for drying for 12h, and then ground through a 100 mesh sieve to obtain a white powder aluminum lithium extraction adsorbent, which was marked as LiAl-LDHs.

[0080] 4. 3.3g of sodium tungstate (Na2WO4.2H2O) was mixed with the above obtained LiAl-LDHs by dry masking to obtain W physically doped LiAl-LDHs.

[0081] Comparative Example 3 The comparative example provides an iodate-doped aluminum lithium extraction adsorbent (I-LiAl-LDHs), which is different from example 1 in that 2.14 g of KIO3 is used instead of sodium tungstate, and the remaining steps and raw materials are the same as in example 1, which will not be repeated here.

[0082] Test example 1 5 g samples of lithium adsorbents of examples and comparative examples were respectively activated in 5 L pure water for 2 h, and the Li + After desorption equilibrium, the sample was filtered and dried. 1 g of the activated sample was placed in 100 mL of a certain simulated salt lake brine (Li + The concentration was 170 mg / L) for static adsorption and desorption experiments, and the mass adsorption capacity of the sample for lithium was tested after the adsorption was stable.

[0083] Two groups of different adsorption temperature experiments were set up, one group was carried out at 25°C, and the other group was carried out at -5°C low temperature.

[0084] After 2 h of adsorption, the supernatant was taken, and the ion concentration changes before and after adsorption were determined by inductively coupled plasma optical emission spectrometer (ICP-OES), and the adsorption capacity was calculated. The data obtained are recorded in Table 1.

[0085] Table 1

[0086] As can be seen from Table 1, the various metal oxyanion-doped adsorbents prepared in the present application can still maintain an adsorption capacity of more than 90% at -5°C low temperature environment, which is significantly better than the undoped control sample (only 63.9%). Especially the high ferrate-doped sample shows the highest adsorption capacity at room temperature and low temperature, which shows that this doping strategy not only effectively overcomes the industry problem of performance decay at low temperature, but also further improves the comprehensive performance of the adsorbent, and has good industrial application prospect.

[0087] Finally, it should be pointed out that the above-described examples are only specific embodiments of the present application, which are used to illustrate the technical solutions of the present application, but not to limit it. Although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that any person skilled in the art can modify or easily think of changes to the technical solutions described in the foregoing examples within the technical scope disclosed by the present application, or make equivalent substitutions for some technical features; and these modifications, changes or substitutions do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A metal oxyanion-doped aluminum-based lithium extraction adsorbent, characterized in that, The aluminum-based lithium extraction adsorbent has a lithium-aluminum hydrotalcite structure, and metal-oxygen anions are doped in the plate layer and interlayer of the lithium-aluminum hydrotalcite structure. The metal-oxygen anion is a composite anion composed of a metal element and oxygen atoms.

2. The metal oxyanion-doped aluminum-based lithium-adsorbing agent according to claim 1, characterized by, The metal element includes W, Mo, Mn, Fe, Cr, Ti or Co. Preferably, the metal oxyanion comprises at least one of WO4 2- , MnO4 - , FeO4 2- , TiO3 2- , CrO4 2- , CoO4 2- , [PMo 12 O 40 ] 3- .

3. The metal oxyanion-doped aluminum-based lithium-adsorbing agent according to claim 1, characterized by, The doping amount of the metal-oxygen anion is 0.4-10 wt%.

4. A method for producing the metal-oxygen anion-doped aluminum-based lithium extraction adsorbent according to any one of claims 1 to 3, characterized by, The method comprises the following steps: A. Dissolving a soluble lithium source and a soluble aluminum source in water to obtain a first solution; Dissolving a soluble metal-oxygen anion source in water to obtain a second solution; B. Mixing the first solution and the second solution to obtain a precursor solution; C. While stirring, adding a lye to the precursor solution until the pH value reaches 6.0-10.0, and continuing to stir to age, to obtain a white slurry; D. Transferring the white slurry to a reaction kettle for hydrothermal reaction, cooling, washing and drying after completion to obtain the metal-oxygen anion-doped aluminum-based lithium extraction adsorbent.

5. The production method according to claim 4, characterized by, The soluble lithium source includes at least one of lithium chloride, lithium nitrate, lithium sulfate, lithium carbonate and lithium hydroxide; Preferably, the soluble aluminum salt includes at least one of aluminum chloride, aluminum nitrate and aluminum sulfate; Preferably, the soluble metal-oxygen anion source includes at least one of sodium tungstate, potassium permanganate, sodium ferrite, sodium titanate, titanic acid and phosphomolybdic acid; Preferably, the concentration of the aluminum source in the first solution is 2-10 mol / L; Preferably, the molar ratio of the lithium source to the aluminum source is (0.4-1):1; Preferably, the molar ratio of the metal-oxygen anion source to the aluminum source, in terms of metal elements, is (0.01-0.2):1; Preferably, the second solution further includes an alkaline compound; Preferably, the alkaline compound includes at least one of sodium hydroxide, lithium hydroxide, sodium carbonate and ammonia water.

6. The preparation method according to claim 4, characterized in that, In step C, the alkali in the lye includes at least one of sodium hydroxide, lithium hydroxide, sodium carbonate and ammonia water; Preferably, the concentration of the lye is 0.5-10 mol / L; Preferably, the aging time is 0.5-2 h.

7. The method of any one of claims 4 to 6, wherein the method further comprises the step of: In step D, the temperature of the hydrothermal reaction is 90-180℃, and the time is 6-48 h.

8. The method of any one of claims 4-6, wherein the compound is prepared by the method of any one of claims 1-3. In step D, the inner lining of the reaction kettle is polytetrafluoroethylene.

9. The method of any one of claims 4 to 6, wherein the compound is prepared by the method of any one of claims 1 to 3. In step D, the drying temperature is 60-120℃; Preferably, the preparation method further comprises a crushing process after drying.

10. Use of the metal oxyanion-doped aluminum-based lithium extraction adsorbent according to any one of claims 1 to 3 in the field of low-temperature lithium extraction, characterized in that, The low-temperature lithium extraction temperature is <0℃.

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