Aluminum-based lithium ion sieve, and preparation method and application thereof

Abstract

The present application relates to brine lithium extraction material technical field, provide a kind of aluminium base lithium ion sieve and its preparation method and application.The aluminium base lithium ion sieve has the following general formula:LiCl·xLa(OH)3·mAl(OH)3·nH2O;Formula, 0.01≤x≤0.08, 1.5≤m≤10, 2≤n≤9.The preparation method of the aluminium base lithium ion sieve includes: aluminium source, lithium source, lanthanum source and alcohol are dissolved in water and are ultrasonically treated to obtain mixed salt solution, lye is ultrasonically treated for standby;Mixed salt solution and lye are treated under the action of double-frequency ultrasonic, and co-precipitation reaction occurs, to obtain aluminium base lithium ion sieve precursor;Aluminium base lithium ion sieve precursor is further activated to obtain aluminium base lithium ion sieve.The aluminium base lithium ion sieve has excellent adsorption performance, less carbonate impurity content and large specific surface area, and can maintain long-period stability during the operation of high-sulfur type salt lake brine.

Description

Technical Field

[0001] This invention relates to the field of materials technology for lithium extraction from brine, and more specifically, to an aluminum-based lithium-ion sieve, its preparation method, and its application. Background Technology

[0002] Over the past decade, the rapid rise of the electric vehicle and lithium-ion battery industries has driven a surge in demand for lithium resources. Currently, the main sources of lithium products on the market are high-grade lithium ore and brine from salt lakes. The ease of operation and cost-effectiveness of lithium extraction processes from brine make it a promising technology both economically and scientifically. To date, various technologies for recovering lithium from brine have been developed, including membrane methods, solvent extraction methods, and adsorption methods. Among these, adsorption methods are particularly popular due to their ease of operation and tolerance to Li-. + Its high selectivity and environmental friendliness have made it popular in the market.

[0003] Currently, lithium adsorbents based on metal inorganic materials are mainly manganese-based lithium ion sieves, titanium-based lithium ion sieves, and aluminum-based lithium ion sieves. Manganese-based and titanium-based lithium ion sieves exhibit excellent Li-... + While manganese-based lithium ion sieves exhibit good adsorption capacity and selectivity, in practical applications, they suffer significant manganese ion dissolution losses during desorption in acidic liquids, resulting in low recyclability. Titanium-based lithium ion sieves, on the other hand, have high production costs. In contrast, aluminum-based lithium ion sieves (Li / Al-LDHs) possess stable adsorption performance, with negligible dissolution losses during pure water desorption. The chemical formula for aluminum-based lithium ion sieves is generally LiCl·mAl(OH)3·nH2O. They exhibit excellent lithium selectivity and a good adsorption capacity (4-8 mg / g), making them a widely used inorganic lithium metal adsorbent. However, due to the presence of certain oxygen-containing anions (such as SO42-), they may experience significant manganese ion dissolution losses. 2- CO3 2- Compared to chloride ions, which have a stronger affinity for aluminum-based lithium-ion sieves and readily enter the interlayer structure of the adsorbent via ion exchange, leading to difficulties in pure water desorption and a significant decrease in the adsorption performance of the aluminum-based lithium-ion sieve. Currently, most lithium-containing salt lakes worldwide are sulfate-type salt lakes, thus greatly limiting the application of this type of aluminum-based lithium-ion sieve.

[0004] Currently, the synthesis of aluminum-based lithium-ion sieves mainly employs three strategies: hydrothermal method, mechanochemical method, and coprecipitation method. The hydrothermal method produces aluminum-based lithium-ion sieves with excellent crystal structure and uniform particle size distribution, but it is costly. The mechanochemical method reduces the use of solvents in the synthesis, but it cannot guarantee the uniformity of the particle size of the resulting aluminum-based lithium-ion sieves. The coprecipitation method can directly produce powder materials with relatively uniform particle size distribution; however, insufficient micro-mixing during the coprecipitation process can lead to impure phases in the resulting powder material, low specific surface area, insufficient exposure of lithium active sites, and low lithium adsorption capacity.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide an aluminum-based lithium-ion sieve, its preparation method, and its application. The aluminum-based lithium-ion sieve provided by this invention has a high specific surface area, uniform particle size distribution, low carbonate impurity content, and excellent adsorption performance. It can maintain long-term stability during operation in high-sulfur salt lake brine, thus broadening the application scenarios of aluminum-based lithium-ion sieves.

[0007] This invention is implemented as follows:

[0008] In a first aspect, the present invention provides an aluminum-based lithium ion sieve, wherein the aluminum-based lithium ion sieve has the following general formula: LiCl·xLa(OH)3·mAl(OH)3·nH2O; where 0.01≤x≤0.08, 1.5≤m≤10, and 2≤n≤9;

[0009] The aluminum-based lithium ion sieve contains carbonate impurities, with a content of 0.01wt%-0.15wt% of the aluminum-based lithium ion sieve.

[0010] The specific surface area of ​​the aluminum-based lithium-ion sieve is 60 m². 2 / g-95m 2 / g;

[0011] The structured water content in the aluminum-based lithium ion screen is 18wt%-25wt%.

[0012] In an optional embodiment, the aluminum-based lithium-ion sieve satisfies at least one of the following conditions ①-②:

[0013] ①The aluminum-based lithium ion sieve has an adsorption capacity of 0.1 mg / g-9 mg / g for sulfate ions;

[0014] ②The aluminum-based lithium ion sieve has an adsorption capacity of 9.80 mg / g-16.5 mg / g for lithium ions.

[0015] In a second aspect, the present invention provides a method for preparing an aluminum-based lithium-ion sieve as described in the first aspect, comprising the following steps:

[0016] S1. Dissolve aluminum source, lithium source, lanthanum source and alcohol in water and sonicate to obtain a mixed salt solution; dissolve alkali in water and sonicate to obtain an alkaline solution.

[0017] S2. The mixed salt solution and alkali solution are added to the reactor in a co-flow manner, and dual-frequency ultrasonic treatment is turned on to carry out co-precipitation reaction to obtain aluminum-based lithium ion sieve precursor.

[0018] S3. The aluminum-based lithium ion sieve precursor is activated to obtain the aluminum-based lithium ion sieve.

[0019] In an optional embodiment, the alcohol includes at least one of methanol, ethanol, polyethylene glycol, or ethylene glycol.

[0020] In an optional implementation, in step S1, the conditions for ultrasonic treatment are: ultrasonic frequency of 5 kHz-50 kHz, ultrasonic power of 30 W-100 W, and ultrasonic power density of 3 W / cm². 2 -10W / cm 2 The ultrasound time is 0.2h-2h, and the temperature is 25℃-60℃.

[0021] In an optional implementation, in step S2, the dual-frequency ultrasound processing involves simultaneously using low-frequency ultrasound and high-frequency ultrasound.

[0022] And / or, the low-frequency ultrasound has an ultrasonic frequency of 20kHz-40kHz, an ultrasonic power of 200W-500W, and an ultrasonic power density of 20W / cm³. 2 -50W / cm 2 ;

[0023] And / or, the high-frequency ultrasound has an ultrasonic frequency of 40kHz-60kHz, an ultrasonic power of 400W-800W, and an ultrasonic power density of 50W / cm³. 2 -100W / cm 2 ;

[0024] The frequency of the low-frequency ultrasound is lower than that of the high-frequency ultrasound.

[0025] In an optional implementation, in step S1, the method for preparing the mixed salt solution or the alkaline solution satisfies at least one of the following conditions ③-⑤:

[0026] ③ The volume fraction of the alcohol in the mixed salt solution is 5%-60%;

[0027] ④ The molar ratio of lithium ions, aluminum ions and lanthanum ions in the mixed salt solution is (0.15-10):1:(0.01-0.15), and / or the concentration of lithium ions in the mixed salt solution is 0.05mol / L-8mol / L;

[0028] ⑤ The alkali in the alkaline solution is at least one of sodium hydroxide, potassium hydroxide, or ammonia, and the concentration of the alkali in the alkaline solution is 0.5 mol / L-15 mol / L.

[0029] In an optional implementation, step S2 satisfies at least one of the following conditions ⑥-⑨:

[0030] ⑥ The flow rate of the mixed salt solution is 10 mL / min-60 mL / min;

[0031] ⑦ The flow rate of the alkaline solution is 5 mL / min-80 mL / min;

[0032] ⑧ The reaction temperature for the coprecipitation reaction is 25℃-100℃;

[0033] ⑨ The pH of the reaction solution at the end of the coprecipitation reaction is 4.0-8.0.

[0034] In an optional implementation, in step S3, the activation treatment refers to placing the aluminum-based lithium ion sieve precursor in an activation solution and stirring for 10-24 hours; and / or, the activation solution is pure water.

[0035] Thirdly, the present invention provides an application of the aluminum-based lithium ion sieve as described in the first aspect, wherein the aluminum-based lithium ion sieve is used for lithium adsorption in the liquid phase.

[0036] The present invention has the following beneficial effects:

[0037] (1) The aluminum-based lithium ion sieve provided by the present invention has lanthanum doping, which can complex with chloride ions to enhance the affinity of the aluminum-based lithium ion sieve for chloride ions. This is beneficial to reduce the adsorption of other oxygen-containing ions (such as sulfate and borate) by the aluminum-based lithium ion sieve, broaden the application of aluminum-based lithium ion sieve in lithium extraction from sulfate-type salt lakes, and improve the extraction efficiency of lithium ions.

[0038] (2) In the preparation of the aluminum-based lithium-ion sieve, the mixed salt solution is degassed by ultrasonic treatment, reducing the carbon dioxide concentration in the mixed salt solution and thus reducing the carbonate impurity content in the aluminum-based lithium-ion sieve. In addition, in the coprecipitation reaction system, the hydration degree of the aluminum-based lithium-ion sieve is improved by adding alcohol, thereby increasing the adsorption capacity of the aluminum-based lithium-ion sieve. Furthermore, in the coprecipitation reaction process, the coprecipitation reaction is promoted by dual-frequency ultrasound. The ultrasonic jet generated by high-frequency ultrasound is beneficial to the thorough mixing of the mixed salt solution and alkali solution at the microscopic level; the cavitation bubbles generated by low-frequency ultrasound are beneficial to promote the primary nucleation of the coprecipitation reaction and accelerate the coprecipitation reaction. The dual-frequency ultrasound treatment combining high-frequency and low-frequency ultrasound results in the prepared aluminum-based lithium-ion sieve having a large specific surface area, which can fully contact the lithium extraction solution and increase the lithium extraction efficiency. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of a self-assembled dual-frequency ultrasonic device according to an embodiment of the present invention;

[0041] Figure 2 This is a SEM image of the aluminum-based lithium-ion sieve prepared in Example 1 of the present invention;

[0042] Figure 3 The image shows the XRD pattern of the aluminum-based lithium-ion sieve precursor prepared in Example 1 of this invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0044] The following is a detailed description of the aluminum-based lithium-ion sieve, its preparation method, and its application provided by the present invention.

[0045] This invention provides a method for preparing an aluminum-based lithium-ion sieve, comprising the following steps:

[0046] S1. Dissolve aluminum source, lithium source, lanthanum source and alcohol in water and sonicate to obtain a mixed salt solution; dissolve alkali in water and sonicate to obtain an alkaline solution.

[0047] S2. The mixed salt solution and the alkaline solution are added to the reactor in a co-flow manner, and dual-frequency ultrasonic treatment is turned on to carry out a co-precipitation reaction to obtain an aluminum-based lithium ion sieve precursor.

[0048] S3. The aluminum-based lithium ion sieve precursor is activated to obtain an aluminum-based lithium ion sieve.

[0049] Specifically, the present invention will describe each of the above steps one by one.

[0050] S1: Dissolve aluminum source, lithium source, lanthanum source and alcohol in water, and sonicate in an ultrasonic water bath to obtain a mixed salt solution; dissolve alkali in water, and sonicate in an ultrasonic water bath to obtain an alkali solution.

[0051] The present invention does not limit the mixing method and mixing order of aluminum source, lithium source, lanthanum source and alcohol, including but not limited to dissolving aluminum source, lithium source, lanthanum source and alcohol in water to prepare corresponding solutions, and then mixing them in proportion to form a mixed salt solution.

[0052] It should be noted that, because carbon dioxide is readily soluble in water, a certain concentration of carbonate ions will dissolve in the solution prepared under normal conditions. The insertion of lithium ions gives the layered aluminum-based lithium-ion sieve a positive charge. To maintain charge balance, anions in the solution enter the interlayer structure of the aluminum-based lithium-ion sieve. Compared to chloride ions, the divalent anion carbonate ion has a higher affinity, making it easier for carbonate ions to enter and remain in the interlayer structure of the aluminum-based lithium-ion sieve. This increases the difficulty of ion exchange between lithium ions in the interlayer and the external environment, leading to difficulties in lithium desorption. In this invention, ultrasonic treatment is used when preparing mixed salt and alkali solutions. The high-frequency vibration of ultrasound releases the dissolved carbon dioxide gas in the solution, thereby reducing the concentration of carbon dioxide in the solution. In other words, it reduces the concentration of carbonate ions in the solution, thus reducing the impact of carbonate ions on the performance of the aluminum-based lithium-ion sieve.

[0053] Since carbonate adsorbed on aluminum-based lithium ion sieves will escape as carbon dioxide under heat treatment, this invention uses a carbon-sulfur analyzer to test the content of carbonate impurities in aluminum-based lithium ions.

[0054] In some embodiments, the aluminum source is any one or a combination of at least two of aluminum hydroxide, aluminum chloride, aluminum nitrate, or aluminum sulfate.

[0055] In some embodiments, the lithium source is any one or a combination of at least two of lithium hydroxide, lithium chloride, lithium nitrate, or lithium sulfate.

[0056] In some embodiments, the lanthanum source is any one or a combination of at least two of lanthanum hydroxide, lanthanum chloride, or lanthanum sulfate.

[0057] In some embodiments, the molar ratio of lithium ions, aluminum ions and lanthanum ions in the mixed salt solution is (0.15-10):1:(0.01-0.15), preferably (0.3-1):1:(0.035-0.1), and more preferably 0.51:1:0.05.

[0058] In some embodiments, the concentration of lithium ions in the mixed salt solution is 0.05 mol / L to 8 mol / L, preferably 0.4 mol / L to 3 mol / L, and more preferably 1.0 mol / L.

[0059] The lithium / aluminum molar ratio in the mixed brine affects the performance of aluminum-based lithium ion sieves. If the value is too low, the resulting aluminum-based lithium ion sieve will have a low number of lithium active sites, resulting in a low adsorption capacity. If the value is too high, the lithium ion intercalation efficiency will be low, leading to a waste of raw materials.

[0060] The lanthanum / aluminum molar ratio in the mixed salt solution affects the performance of aluminum-based lithium-ion sieves. If the value is too low, lanthanum does not significantly promote the affinity of chloride ions in the resulting aluminum-based lithium-ion sieve; if the value is too high, it leads to excessive distortion of the crystal structure of the resulting aluminum-based lithium-ion sieve, resulting in a decrease in adsorption capacity.

[0061] Alcohols in the mixed salt solution can form hydrogen bond networks with water, which is beneficial for improving the hydration level of aluminum-based lithium ion sieves. Density functional theory (DFT) calculations show that, under conditions of high interaction energy, LiCl more easily enters the interlayer structure of aluminum-based ion sieves with abundant interlayer water. This means that the amount of structural water contained in aluminum-based lithium ion sieves is positively correlated with adsorption capacity; higher structural water content means lower mass transfer resistance of hydrated lithium ions, which is more conducive to the adsorption process and endows aluminum-based ion sieves with higher lithium adsorption capacity.

[0062] In some embodiments, the alcohol may be at least one of methanol, ethanol, polyethylene glycol, or ethylene glycol.

[0063] In some embodiments, the volume fraction of alcohol in the mixed salt solution is 5%-60%.

[0064] The volume fraction of alcohol in the mixed salt solution affects the performance of aluminum-based lithium ion sieves. If the volume fraction is too low, it will not have a significant impact on the synthesis of aluminum-based lithium ion sieves. If the volume fraction is too high, it will cause the synthesized primary particles to be excessively bonded and aggregated, and the crystallinity of the crystals will decrease, which will directly affect the adsorption performance of the synthesized aluminum-based lithium ion sieves.

[0065] In some embodiments, the ultrasonic frequency of the ultrasonic treatment is 5 kHz-50 kHz, the ultrasonic power is 30 W-100 W, and the ultrasonic power density is 3 W / cm³. 2 -10W / cm 2 The ultrasonic time is 0.2h-2h, and the ultrasonic temperature is 25℃-60℃; preferably, the ultrasonic frequency is 10KHz-25KHz, the ultrasonic power is 60W-90W, and the ultrasonic power density is 6W / cm³. 2 -9W / cm 2 The ultrasonic time is 0.5-1 hour, and the ultrasonic temperature is 25-30℃; more preferably, the ultrasonic frequency is 20kHz, the ultrasonic power is 80W, and the ultrasonic power density is 8W / cm³. 2 The ultrasound time was 0.5 hours and the ultrasound temperature was 25°C.

[0066] S2: The mixed salt solution and alkali solution are added to the reactor in a co-current manner, and a co-precipitation reaction is carried out by dual-frequency ultrasonic treatment. After the reaction is completed, the solid product is filtered to obtain a solid product. The solid product is washed with water and dried at 40℃-95℃ for 4h-24h to obtain an aluminum-based lithium ion sieve precursor.

[0067] In some embodiments, dual-frequency ultrasonic treatment involves simultaneously employing low-frequency and high-frequency ultrasound. The high-frequency ultrasound in the dual-frequency ultrasonic treatment is provided by an ultrasonic probe, which generates an ultrasonic jet by providing a higher ultrasonic frequency, which is beneficial for thoroughly mixing the mixed salt solution and alkali solution at the microscopic level. The low-frequency ultrasound in the dual-frequency ultrasonic treatment is provided by an ultrasonic water bath, which can generate cavitation bubbles. The bursting of these bubbles leads to local supersaturation, which has a beneficial effect on the primary nucleation of the coprecipitation reaction, accelerating the coprecipitation reaction and resulting in faster particle formation without the need for aging. At the same time, the presence of cavitation bubbles gives the aluminum-based lithium ion sieve a higher surface area, allowing it to fully contact the lithium-containing solution and improve its adsorption performance.

[0068] In some embodiments, the low-frequency ultrasound has an ultrasonic frequency of 20kHz-40kHz, an ultrasonic power of 200W-500W, and an ultrasonic power density of 20W / cm². 2 -50 W / cm 2 High-frequency ultrasound has an ultrasonic frequency of 40kHz-60kHz, an ultrasonic power of 400W-800W, and an ultrasonic power density of 50W / cm³. 2 -100 W / cm 2 In this invention, low-frequency ultrasound and high-frequency ultrasound are relative concepts; in other words, the ultrasonic frequency of low-frequency ultrasound is lower than that of high-frequency ultrasound.

[0069] In some embodiments, the concentration of alkali in the alkaline solution is 0.5 mol / L-15 mol / L, preferably 3 mol / L-8 mol / L, and more preferably 5 mol / L.

[0070] In the preparation of coprecipitation reaction, the concentration of alkali solution is the key to preparing aluminum-based lithium-ion sieves with uniform particle size distribution. If the value is too low, the particle size distribution of the product will be uneven and the phase purity will be low; if the value is too high, the product particles will be larger and the specific surface area will decrease.

[0071] In some embodiments, the flow rate of the mixed salt solution is 10 mL / min to 60 mL / min, preferably 10 mL / min to 30 mL / min, and more preferably 20 mL / min.

[0072] In some embodiments, the flow rate of the alkali solution is 5 mL / min to 80 mL / min, preferably 8 mL / min to 50 mL / min, and more preferably 28 mL / min.

[0073] In some embodiments, the reaction temperature for the coprecipitation reaction is 25°C-100°C.

[0074] In some embodiments, the pH of the reaction solution at the end of the coprecipitation reaction is 4.0-8.0, preferably 5.0-6.5, and more preferably 6.0.

[0075] S3: The aluminum-based lithium ion sieve precursor is activated in pure water and then dried in an oven to obtain the aluminum-based lithium ion sieve.

[0076] The aluminum-based lithium-ion sieve precursor was activated to allow some of the Li in its structure to be released. + The lithium ion is eluted in the activation solution to create Al-O octahedral vacancies, thus forming an aluminum-based lithium ion sieve; Li in the brine + It can be embedded in these holes, and due to the memory effect and steric hindrance effect, it is effective for Li + The selectivity is very high, and its adsorption and desorption of lithium is as follows:

[0077]

[0078] The features and performance of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0079] Example 1

[0080] This embodiment provides an aluminum-based lithium-ion sieve, the preparation method of which includes:

[0081] S1. Weigh AlCl3·6H2O (analytical grade), LiCl·H2O (analytical grade), LaCl3·6H2O (analytical grade), and ethylene glycol to prepare a 400 mL mixed salt solution for ultrasonic treatment; wherein the volume fraction of ethylene glycol in the mixed salt solution is 18%, and the molar ratio of lithium ions, aluminum ions, and lanthanum ions is 0.51:1:0.05, Li... + The concentration is 1.0 mol / L. A 5 mol / L NaOH solution is prepared and ultrasonically treated to prepare the alkali solution.

[0082] The above ultrasonic treatment conditions are as follows: ultrasonic frequency 20 kHz, ultrasonic power 80 W, and ultrasonic power density 8 W / cm³. 2 The ultrasound time was 0.5 hours and the ultrasound temperature was 25℃.

[0083] S2, such as Figure 1 As shown, Figure 1 This is a schematic diagram of a self-assembled dual-frequency ultrasonic device, in which a water bath provides low-frequency ultrasound and an ultrasonic probe provides high-frequency ultrasound. Solution A and solution B are a mixed salt solution or an alkaline solution, respectively.

[0084] An ultrasonic water bath and ultrasonic probe were turned on to provide dual-frequency ultrasound. A mixed salt solution and an alkali solution were delivered dropwise into a three-necked flask in a co-current manner via a peristaltic pump. The reaction temperature of the materials in the three-necked flask was controlled at 45°C. The reaction was carried out until the pH reached 6.0 to obtain a suspension. The solid product obtained after filtering the suspension was placed in a 45°C oven and dried for 20 hours to obtain an aluminum-based lithium ion sieve precursor. The flow rate of the mixed salt solution was 20 mL / min, and the flow rate of the alkali solution was 28 mL / min.

[0085] The ultrasonic conditions for the ultrasonic water bath are: ultrasonic frequency of 20 kHz, ultrasonic power of 200 W, and ultrasonic power density of 20 W / cm³. 2 The ultrasonic probe's ultrasonic conditions are: ultrasonic frequency 60kHz, ultrasonic power 500W, and ultrasonic power density 62.5W / cm². 2 .

[0086] S3. The aluminum-based lithium-ion sieve precursor and pure water (solid-liquid ratio 1g:100mL) were placed in a shaker for activation (temperature 25℃, duration 24h, shaking speed 180rpm). After activation, the mixture was filtered, and the resulting solid phase was dried in an oven to obtain the aluminum-based lithium-ion sieve. The obtained aluminum-based lithium-ion sieve was subjected to SEM and XRD tests, as shown... Figure 2 and Figure 3 As shown, from Figure 2 It can be seen that the prepared aluminum-based lithium-ion sieve has a narrow particle size distribution, no particle agglomeration or adhesion, and good dispersibility; from Figure 3 It can be seen that the peak shapes of the obtained aluminum-based lithium ion sieve and lithium aluminum layered hydroxide LiCl·mAl(OH)3·nH2O are matched. The diffraction peak intensity is high and the full width at half maximum is narrow, indicating that the crystal structure is good and the phase is single, with no impurity peaks of other substances appearing.

[0087] Example 2

[0088] This embodiment provides an aluminum-based lithium-ion sieve, the preparation method of which includes:

[0089] S1. Weigh AlCl3·6H2O (analytical grade), LiCl·H2O (analytical grade), LaCl3·6H2O (analytical grade), and polyethylene glycol to prepare a 400 mL mixed salt solution for ultrasonic treatment; wherein the volume fraction of polyethylene glycol (degree of polymerization 6000) in the mixed salt solution is 5%, and the molar ratio of lithium ions, aluminum ions, and lanthanum ions is 10:1:0.01, Li... + The concentration is 0.05 mol / L. A 0.5 mol / L NaOH solution is prepared and ultrasonically treated to prepare the alkali solution.

[0090] The above ultrasonic processing conditions are as follows: ultrasonic frequency 50 kHz, ultrasonic power 30 W, and ultrasonic power density 3 W / cm³. 2The ultrasound duration was 2 hours, and the ultrasound temperature was 60℃.

[0091] S2. Turn on the ultrasonic water bath and ultrasonic probe to provide dual-frequency ultrasound. A mixed salt solution and alkali solution are delivered dropwise into a three-necked flask via a peristaltic pump in a parallel flow. The reaction temperature in the three-necked flask is controlled at 100℃. The reaction proceeds until the pH reaches 4.0, yielding a suspension. The solid product obtained after filtering the suspension is dried in a 45℃ oven for 20 hours to obtain the aluminum-based lithium-ion sieve precursor. The flow rate of the mixed salt solution is 10 mL / min, and the flow rate of the alkali solution is 80 mL / min.

[0092] The ultrasonic conditions for the ultrasonic water bath are: ultrasonic frequency of 40 kHz, ultrasonic power of 350 W, and ultrasonic power density of 20 W / cm³. 2 The ultrasonic probe's ultrasonic conditions are: ultrasonic frequency 50kHz, ultrasonic power 400W, and ultrasonic power density 50W / cm³. 2 .

[0093] S3. The aluminum-based lithium ion sieve precursor and pure water (solid-liquid ratio 1g:100mL) were placed in a shaker for activation (temperature 25℃, duration 24h, shaking speed 180rpm). After activation, the mixture was filtered, and the filtered solid phase was dried in an oven to obtain the aluminum-based lithium ion sieve.

[0094] Example 3

[0095] This embodiment provides an aluminum-based lithium-ion sieve, the preparation method of which includes:

[0096] S1. Weigh AlCl3·6H2O (analytical grade), LiCl·H2O (analytical grade), LaCl3·6H2O (analytical grade), and ethanol to prepare a 400 mL mixed salt solution for ultrasonic treatment; wherein the volume fraction of ethanol in the mixed salt solution is 60%, and the molar ratio of lithium ions, aluminum ions, and lanthanum ions is 0.15:1:0.15, Li... + The concentration is 8.0 mol / L. A 15 mol / L NaOH solution is prepared and ultrasonically treated to prepare the alkali solution.

[0097] The above ultrasonic treatment conditions are as follows: ultrasonic frequency 5 kHz, ultrasonic power 100 W, and ultrasonic power density 10 W / cm³. 2 The ultrasonic time was 0.2 hours and the ultrasonic temperature was 45℃.

[0098] S2. Turn on the ultrasonic water bath and ultrasonic probe to provide dual-frequency ultrasound. A mixed salt solution and alkali solution are delivered dropwise into a three-necked flask via a peristaltic pump in a parallel flow. The reaction temperature in the three-necked flask is controlled at 25℃. The reaction proceeds until the pH reaches 8.0, yielding a suspension. The resulting solid product is filtered and dried in a 45℃ oven for 20 hours to obtain the aluminum-based lithium-ion sieve precursor. The flow rate of the mixed salt solution is 60 mL / min, and the flow rate of the alkali solution is 5 mL / min.

[0099] The ultrasonic conditions for the ultrasonic water bath are: ultrasonic frequency of 30 kHz, ultrasonic power of 500 W, and ultrasonic power density of 50 W / cm³. 2 The ultrasonic probe's ultrasonic conditions are: ultrasonic frequency 40kHz, ultrasonic power 800W, and ultrasonic power density 100W / cm³. 2 .

[0100] S3. The aluminum-based lithium ion sieve precursor and pure water (solid-liquid ratio 1g:100mL) were placed in a shaker for activation (temperature 25℃, duration 24h, shaking speed 180rpm). After activation, the mixture was filtered, and the filtered solid phase was dried in an oven to obtain the aluminum-based lithium ion sieve.

[0101] Example 4

[0102] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Example 1, except that in step S1, the molar ratio of lithium ions, aluminum ions and lanthanum ions in the mixed salt solution is 0.51:1:0.1.

[0103] Example 5

[0104] This embodiment provides a method for preparing an aluminum-based lithium ion sieve, which is basically the same as that in Example 1, except that in step S1, the molar ratio of lithium ions, aluminum ions and lanthanum ions in the mixed salt solution is 0.51:1:0.035.

[0105] Example 6

[0106] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Example 1, except that in step S1, the volume fraction of ethylene glycol in the mixed salt solution is 6%.

[0107] Example 7

[0108] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Example 1, except that in step S1, the volume fraction of ethylene glycol in the mixed salt solution is 60%.

[0109] Example 8

[0110] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Example 1, except that in step S1, the molar ratio of lithium ions, aluminum ions and lanthanum ions in the mixed salt solution is 0.3:1:0.035.

[0111] Example 9

[0112] This embodiment provides a method for preparing an aluminum-based lithium ion sieve, which is basically the same as that in Example 1, except that in step S1, the molar ratio of lithium ions, aluminum ions and lanthanum ions in the mixed salt solution is 1:1:0.035.

[0113] Example 10

[0114] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Example 1, except that the flow rate of the alkaline solution is 50 mL / min in step S2.

[0115] Example 11

[0116] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Example 1, except that the flow rate of the alkaline solution is 8 mL / min in step S2.

[0117] Example 12

[0118] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Example 1, except that in step S2, the flow rate of the mixed salt solution is 30 mL / min.

[0119] Example 13

[0120] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Example 1, except that in step S2, the flow rate of the mixed salt solution is 10 mL / min.

[0121] Comparative Example 1

[0122] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Embodiment 1, except that there is no ultrasonic treatment step in step S1.

[0123] Comparative Example 2

[0124] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Embodiment 1, except that the dual-frequency ultrasonic treatment step is not performed in step S2.

[0125] Comparative Example 3

[0126] This embodiment provides a method for preparing an aluminum-based lithium ion sieve, which is basically the same as that in Embodiment 1, except that in step S2, only an ultrasonic water bath is used for ultrasonic treatment.

[0127] Comparative Example 4

[0128] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Embodiment 1, except that in step S2, only an ultrasonic probe is used for ultrasonic treatment.

[0129] Comparative Example 5

[0130] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Example 1, except that lanthanum ion doping is not performed in step S1.

[0131] Comparative Example 6

[0132] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Example 1, except that ethylene glycol is not added in step S1.

[0133] Comparative Example 7

[0134] This embodiment provides a method for preparing an aluminum-based lithium-ion sieve, which is basically the same as that in Embodiment 1, except that ultrasonic treatment is not performed in step S1 and dual-frequency ultrasonic treatment is not performed in step S2.

[0135] Experimental Example 1: Particle Size Distribution and Specific Surface Area Test

[0136] After thorough grinding, the dried samples were analyzed for particle size distribution (μm) using a laser particle size analyzer, and the specific surface area (BET) was analyzed using a Canta AUTOSORB IQ specific surface area analyzer. 2 The / g) test results are shown in Table 1.

[0137] Experimental Example 2: Adsorption Performance Test

[0138] An aluminum-based lithium ion sieve and simulated salt lake brine (solid-liquid ratio 1g:100mL) were placed in a shaker for lithium adsorption (temperature 40℃, duration 24h, shaking speed 180rpm). After the lithium adsorption was completed, the simulated salt lake brine filtrate was filtered and sampled for testing.

[0139] The simulated salt lake brine composition is: 0.32 g / L Li + 75.0 g / L Na + 18.0 g / L SO4 2- 20.0g / LK + 135.0g / L Cl - .

[0140] Based on the lithium ion concentration in the simulated brine filtrate from the salt lake obtained through ICP testing, the adsorption capacity of the aluminum-based lithium ion sieve was calculated using the following formula:

[0141]

[0142] Where Q is the lithium adsorption capacity (mg / g) of the aluminum-based lithium ion sieve, and C0 is the initial Li- adsorption capacity in the simulated salt lake brine. + Concentration (mg / L), C t The simulated Li content in the brine filtrate of the salt lake after t hours + Concentration (mg / L), t for this test was 24 hours, V was the volume of the simulated salt lake brine (L), and Ax was the mass of the aluminum-based lithium ion sieve (g). Similarly, the sulfate adsorption capacity of the aluminum-based lithium ion sieve was obtained, and the test results are shown in Table 2.

[0143] Experimental Example 3: Raw Material Utilization Rate

[0144] The filtrate after the coprecipitation reaction was completed was analyzed using inductively coupled plasma atomic emission spectrometry (ICP) to determine the concentrations of Li and Al ions, and to obtain C. 1-Li and C 1-Al The concentrations of Li and Al ions in the mixed salt solution, C 0-Li and C 0-Al The raw material utilization rate Z is calculated using the following formula: The test results are shown in Table 2.

[0145] Experimental Example 4: Test of Structural Water Content and Carbonate Impurity Content

[0146] (1) After drying the aluminum-based lithium ion sieve to constant weight, take an aluminum-based lithium ion sieve with a mass of m0, place it in an oven at 250℃ to remove structural water, bake for 24 hours, weigh it to obtain a mass of m1, and calculate the content of structural water A (wt%) in the aluminum-based lithium ion sieve using the following formula: The test results are shown in Table 2.

[0147] (2) After drying the aluminum-based lithium ion sieve to constant weight, the content of carbonate impurities in the aluminum-based lithium ion sieve was tested using a carbon-sulfur analyzer. The test results are shown in Table 2.

[0148] Table 1: Particle size distribution (μm) and specific surface area BET (m²) of aluminum-based lithium-ion sieves 2 / g)

[0149]

[0150]

[0151] Table 2 Adsorption performance of aluminum-based lithium ion sieves

[0152]

[0153]

[0154] As shown in Table 1, Examples 1 and Comparative Examples 2-4 reveal that the synthesis method using dual-frequency ultrasound results in a product with a narrow particle size distribution and a smaller median particle size. Smaller particle sizes lead to a larger specific surface area, meaning more lithium active sites are exposed, thus significantly increasing the adsorption capacity of the aluminum-based lithium ion sieve for lithium. In dual-frequency ultrasound, both low-frequency and high-frequency ultrasound must be present simultaneously to achieve the aforementioned effect.

[0155] As shown in Table 2, Examples 1-13 and Comparative Examples 1-4 and 7, the aluminum-based lithium-ion sieve obtained by the dual-frequency ultrasonic synthesis method has a lower carbonate impurity content. In all examples, the carbonate impurity content is below 0.15 wt%, which means that the amount of carbonate entering the reaction system from the air during the synthesis process is significantly reduced. Consequently, the carbonate content in the interlayer of the aluminum-based lithium-ion sieve is lower, making ion exchange between lithium ions and the external environment easier and thus improving the adsorption capacity of the aluminum-based lithium-ion sieve. Examples 1, 4-5 and Comparative Example 5 show that lanthanum doping increases the affinity of the aluminum-based lithium-ion sieve for chloride ions and reduces the adsorption of sulfate ions. Simultaneously, the lanthanum doping ratio affects the adsorption performance of this invention. When the lanthanum doping ratio is appropriate, the aluminum-based lithium-ion sieve has a lower adsorption of sulfate ions, which will avoid "sulfate poisoning" during long-term operation. Examples 1, 6-7, and Comparative Example 6 show that ethylene glycol, due to its small molecular size, can form a hydrogen bond network with water molecules. The addition of ethylene glycol increases the hydration level of the aluminum-based lithium ion sieve. Higher interlayer water content means lower mass transfer resistance for hydrated lithium ions, thus endowing the aluminum-based ion sieve with a higher lithium adsorption capacity. Examples 1 and 8-9 show that a suitable lithium / aluminum ratio can maximize raw material utilization and improve adsorption capacity. Under ultrasound-assisted synthesis conditions, a suitable ratio can achieve the goal of low-waste green production and the preparation of high-capacity aluminum-based lithium ion sieves. Examples 1 and 10-13 show that the flow rates of the alkaline solution and the mixed salt solution are crucial to this invention. Their flow rates determine the pH changes in the microenvironment, thereby affecting the adsorption capacity of the aluminum-based lithium ion sieve.

[0156] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An aluminum-based lithium-ion sieve, characterized in that, The aluminum-based lithium-ion sieve has the following general formula: LiCl·xLa(OH)3·mAl(OH)3·nH2O; where 0.01≤x≤0.08, 1.5≤m≤10, and 2≤n≤9; The aluminum-based lithium-ion sieve contains carbonate impurities, with a content of 0.01wt%-0.15wt% of the aluminum-based lithium-ion sieve. The structured water content in the aluminum-based lithium ion screen is 18 wt%-25 wt%. The specific surface area of ​​the aluminum-based lithium-ion sieve is 60 m². 2 / g -95 m 2 / g.

2. The aluminum-based lithium-ion sieve according to claim 1, characterized in that, The aluminum-based lithium-ion sieve satisfies at least one of the following conditions ①-②: ①The aluminum-based lithium ion sieve has an adsorption capacity of 0.1 mg / g - 9 mg / g for sulfate ions; ②The aluminum-based lithium ion sieve has an adsorption capacity of 9.80 mg / g-16.5 mg / g for lithium ions.

3. A method for preparing an aluminum-based lithium-ion sieve according to claim 1, characterized in that, Includes the following steps: S1. Dissolve aluminum source, lithium source, lanthanum source and alcohol in water and sonicate to obtain a mixed salt solution; dissolve alkali in water and sonicate to obtain an alkaline solution. S2. The mixed salt solution and the alkaline solution are added to the reactor in a co-flow manner, and dual-frequency ultrasonic treatment is turned on to carry out a co-precipitation reaction to obtain an aluminum-based lithium ion sieve precursor. S3. The aluminum-based lithium ion sieve precursor is activated to obtain an aluminum-based lithium ion sieve.

4. The method for preparing the aluminum-based lithium-ion sieve according to claim 3, characterized in that, The alcohol includes at least one of methanol, ethanol, polyethylene glycol, or ethylene glycol.

5. The method for preparing the aluminum-based lithium-ion sieve according to any one of claims 3-4, characterized in that, In step S1, the ultrasonic frequency of the ultrasonic treatment is 5 kHz-50 kHz, the ultrasonic power is 30 W-100 W, and the ultrasonic power density is 3 W / cm². 2 -10W / cm 2 The ultrasound time is 0.2h-2h, and the ultrasound temperature is 25℃-60℃.

6. The method for preparing the aluminum-based lithium-ion sieve according to claim 5, characterized in that, In step S2, the dual-frequency ultrasound processing involves simultaneously using low-frequency ultrasound and high-frequency ultrasound. And / or, the low-frequency ultrasound has an ultrasonic frequency of 20 kHz - 40 kHz, an ultrasonic power of 200 W - 500 W, and an ultrasonic power density of 20 W / cm³. 2 -50W / cm 2 ; And / or, the high-frequency ultrasound has an ultrasonic frequency of 40 kHz - 60 kHz, an ultrasonic power of 400 W - 800 W, and an ultrasonic power density of 50 W / cm². 2 -100W / cm 2 ; The frequency of the low-frequency ultrasound is lower than that of the high-frequency ultrasound.

7. The method for preparing the aluminum-based lithium-ion sieve according to claim 6, characterized in that, In step S1, the method for preparing the mixed salt solution or the alkaline solution satisfies at least one of the following conditions ③-⑤: ③ The volume fraction of the alcohol in the mixed salt solution is 5%-60%; ④ The molar ratio of lithium ions, aluminum ions and lanthanum ions in the mixed salt solution is (0.15-10):1:(0.01-0.15), and / or the concentration of lithium ions in the mixed salt solution is 0.05 mol / L - 8 mol / L; ⑤ The alkali in the alkaline solution is at least one of sodium hydroxide, potassium hydroxide, or ammonia, and the concentration of the alkali in the alkaline solution is 0.5 mol / L - 15 mol / L.

8. The method for preparing the aluminum-based lithium-ion sieve according to claim 7, characterized in that, Step S2 satisfies at least one of the following conditions ⑥-⑨: ⑥ The flow rate of the mixed salt solution is 10 mL / min-60 mL / min; ⑦ The flow rate of the alkaline solution is 5 mL / min-80 mL / min; ⑧ The reaction temperature for the coprecipitation reaction is 25℃-100℃; ⑨ The pH of the reaction solution at the end of the coprecipitation reaction is 4.0-8.

0.

9. The method for preparing the aluminum-based lithium-ion sieve according to claim 8, characterized in that, In step S3, the activation treatment refers to placing the aluminum-based lithium ion sieve precursor in an activation solution and stirring for 10-24 hours; and / or, the activation solution is pure water.

10. An application of the aluminum-based lithium-ion sieve according to claim 1, characterized in that, The aluminum-based lithium-ion sieve is used for lithium adsorption in the liquid phase.

Images