Titanium lithium ion sieve and preparation method thereof
A titanium-based lithium-ion sieve modified with tungsten and carbon quantum dots was prepared by a high-temperature solid-state method, which solved the problems of low adsorption capacity and high titanium dissolution rate of H2TiO3 type lithium-ion sieves and achieved a highly efficient lithium-ion adsorption effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTHWEST PETROLEUM UNIV
- Filing Date
- 2026-01-16
- Publication Date
- 2026-04-10
AI Technical Summary
Existing H2TiO3 type titanium-based lithium ion sieves suffer from problems such as low adsorption capacity, slow adsorption rate, and high titanium dissolution rate in practical applications.
A titanium-based lithium-ion sieve synergistically modified with tungsten and carbon quantum dots was prepared by a high-temperature solid-state method. The mixture of lithium source, anatase titanium dioxide, tungsten source and carbon quantum dots was pre-sintered and then calcined at high temperature. Subsequently, it was eluted in sodium thiosulfate aqueous solution to prepare W/CQDs-H2TiO3 type lithium-ion sieve.
It improved the lithium-ion adsorption rate and adsorption capacity, reduced the titanium dissolution rate, reached adsorption equilibrium within 6 hours, with a maximum adsorption capacity of 40.06 mg/g and a titanium dissolution rate of 0.52%.
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Figure CN121823645A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion adsorption technology, specifically to a titanium-based lithium-ion sieve and its preparation method. Background Technology
[0002] As a 21st-century energy metal, lithium has wide applications in medicine, ceramics, electric vehicles, and other fields. According to the latest data, lithium resources are mainly stored in lithium ores and liquid lithium resources worldwide. With the rapid development of the new energy industry, the global lithium market has experienced a surge in demand. Compared to lithium ores, liquid lithium resources have attracted increasing attention due to their abundant reserves and ease of extraction. Currently, the main methods developed for extracting lithium from liquid resources include precipitation, electrochemical methods, membrane separation, and adsorption. Among these, adsorption methods have received widespread attention due to their simple process, low energy consumption, environmental friendliness, and high selectivity.
[0003] Lithium-ion sieves are among the most attractive adsorbents due to their high adsorption capacity. Commonly used ion sieve adsorbents include titanium-based and manganese-based lithium-ion sieves. Manganese-based lithium-ion sieves suffer from significant manganese loss during elution, affecting their adsorption performance. In contrast, titanium-based lithium-ion sieves not only possess high theoretical adsorption capacity and ion selectivity but are also environmentally friendly and have stable cycling structures, making them considered the most valuable lithium adsorbents for research. Titanium-based lithium-ion sieves are mainly divided into layered H₂TiO₃ type and spinel-structured H₄Ti₅O₃ type. 12 H₂TiO₃ lithium ion sieves are a type of lithium ion sieve, with layered structures exhibiting high adsorption capacity and wide applicability. However, in practical applications, it has been found that H₂TiO₃ lithium ion sieves suffer from problems such as actual adsorption capacity being far lower than theoretical adsorption capacity, slow adsorption rate, and performance degradation with increasing cycle number. Therefore, how to prepare an H₂TiO₃ lithium ion sieve with high adsorption capacity, fast adsorption rate, and low titanium dissolution rate has become an urgent problem to be solved. Summary of the Invention
[0004] To address at least one of the aforementioned problems, this invention provides a titanium-based lithium-ion sieve and its preparation method.
[0005] The technical solution of this invention to solve the above problems is as follows: a method for preparing titanium-based lithium-ion sieves, comprising the following steps: Lithium source, anatase titanium dioxide, tungsten source and carbon quantum dots (CQDs) are mixed evenly and pre-sintered at 290~350℃ for 50~80min, then heated to 550~750℃ and calcined for 1.5~3h, and then naturally cooled to obtain the precursor. Take the precursor, elute it in an aqueous sodium thiosulfate solution, and dry the eluted solid phase to obtain the product.
[0006] In one embodiment of the present invention, the molar ratio of the lithium source, anatase titanium dioxide, and tungsten source is 2:(1-x):x, where x = 0.02~0.15, and the mass of the carbon quantum dot is 5~25% of the sum of the masses of the lithium source, anatase titanium dioxide, and tungsten source.
[0007] In one embodiment of the present invention, the concentration of the sodium thiosulfate aqueous solution is 0.4~1.2 mol / L, and the concentration of the precursor in the sodium thiosulfate aqueous solution is 0.5~4 g / L.
[0008] One embodiment of the present invention is that the elution time of the elution operation is 4 to 8 hours.
[0009] One embodiment of the present invention comprises the following steps for preparing anatase titanium dioxide: tetrabutyl titanate is added dropwise to a mixed solvent of ethanol / water while stirring continuously. After the addition is complete, the mixture is aged for 8-16 hours and then dried to obtain an intermediate. The intermediate is then calcined at 350-600°C for 1-5 hours to obtain the final product. In this step, the role of ethanol in the mixed solvent of ethanol / water is to ensure sufficient dispersion of the raw materials, while the role of water is to promote the hydrolysis of tetrabutyl titanate. Therefore, the amount of water added only needs to meet the hydrolysis requirements of tetrabutyl titanate. Furthermore, anatase titanium dioxide can be prepared using other existing methods or commercially available anatase titanium dioxide products; this step only provides a simplified preparation method.
[0010] One embodiment of the present invention comprises the following steps: calcining biomass under an inert atmosphere at 200-400°C to obtain biochar; then adding the biochar to a mixed solution of sodium hydroxide and hydrogen peroxide, stirring continuously for 8 hours; after stirring, adjusting the pH to 8-9 with acid, and performing dialysis; after dialysis, collecting the solid phase and freeze-drying to obtain the final product; wherein the mass ratio of hydrogen peroxide to biochar is 5-30:1, and the molar ratio of hydrogen peroxide to sodium hydroxide is 1-10:1. In this step, the selected biomass can be fruit peel, lignin, plant straw, etc.; other carbon quantum dot preparation methods can also be used, such as hydrothermal methods, solvothermal methods, etc.
[0011] In one embodiment of the present invention, the lithium source is one of lithium acetate, lithium carbonate, or lithium hydroxide, and the tungsten source is one of tungstate or tungsten oxide. However, preferably, lithium acetate is chosen as the lithium source, and tungsten tungstate (e.g., sodium tungstate) is chosen as the tungsten source.
[0012] Another object of the present invention is to provide a titanium-based lithium-ion sieve, which is prepared by any of the methods described above.
[0013] The beneficial effects of this invention are as follows: This invention prepares a titanium-based lithium-ion sieve (W / CQDs-H2TiO) synergistically modified with tungsten and carbon quantum dots via a high-temperature solid-state method, which can be used for the extraction of liquid lithium resources. Compared with traditional titanium-based lithium-ion sieve adsorbents, W / CQDs-H2TiO3 achieves higher adsorption rate and adsorption capacity, as well as lower titanium dissolution loss. It reaches adsorption equilibrium in 6 hours, with a maximum adsorption capacity of 40.06 mg / g and a titanium dissolution loss of 0.52%. Attached Figure Description
[0014] Figure 1 The XRD patterns of the precursors prepared in Example 2, Comparative Example 1, and Comparative Example 2 are shown.
[0015] Figure 2 The image shows the EDS diagram of the precursor obtained in Example 1.
[0016] Figure 3 The graph shows the cycle performance test results of the lithium-ion sieve prepared in Example 2. Detailed Implementation
[0017] The specific embodiments of the present invention will be clearly and completely described below with reference to examples. Obviously, the described examples are only some embodiments of the present invention, and not all embodiments.
[0018] Unless otherwise specified, all pharmaceutical agents used in the following examples are conventional commercial products.
[0019] Unless otherwise specified, all operations used in the following embodiments are conventional operations in the art.
[0020] The anatase titanium dioxide used in the following examples is prepared by the following method: In a mixed solvent of ethanol (40 mL) and water (3.6 mL), 5.7718 g of tetrabutyl titanate was added dropwise while stirring continuously. After the addition was complete, the mixture was aged for 12 h and then dried at 60 °C to obtain an intermediate. The intermediate was then calcined at 450 °C for 3 h to obtain the final product.
[0021] Of course, there are many methods for preparing anatase titanium dioxide in the prior art. This embodiment only provides one of the preparation methods. Anatase titanium dioxide obtained by other methods can also be applied to this invention.
[0022] The carbon quantum dots used in the following examples are prepared using the following methods: Peach gum was calcined at 300℃ under an inert atmosphere to obtain biochar. The biochar was then added to a mixed solution of sodium hydroxide and hydrogen peroxide and stirred continuously for 8 hours. After stirring, acid was added to adjust the pH to 8, and dialysis was performed. After dialysis, the solid phase was collected and freeze-dried to obtain the final product.
[0023] In the above-mentioned preparation process of carbon quantum dots, peach gum is only the biomass with better results obtained by the inventors. Other biomass, such as fruit peel, lignin, and plant straw, can also be used to prepare carbon quantum dots. At the same time, the preparation method of carbon quantum dots is not limited to the above-mentioned calcination and alkalization steps. Hydrothermal method, solvothermal method, etc. can also be used. The carbon quantum dots finally obtained can all be applied to this invention.
[0024] In the following examples, the method for testing the lithium ion adsorption capacity is as follows: a lithium ion solution with a concentration of 200 mg / L is prepared using lithium chloride, and its pH is adjusted to 12. 50 mL of the lithium ion solution is taken, and the lithium ion sieve prepared in the following examples or comparative examples is added at a concentration of 1 g / L. The solution is shaken at room temperature for a period of time at a shaking frequency of 150 rpm / min. After shaking is completed, the lithium ion concentration c in the solution is measured. The formula for calculating the adsorption capacity is: q = 200 - c, where q represents the adsorption capacity, mg / g. In the following embodiments, the method for testing the titanium dissolution rate is as follows: The lithium-ion sieve after adsorbing lithium ions undergoes solid-liquid separation. The solid phase is dried and then eluted with a 0.8 mol / L Na₂S₂O₈ solution for 8 hours. The amount of solid phase added to the Na₂S₂O₈ solution is 2 g / L. After elution, the concentration of titanium ions in the Na₂S₂O₈ solution is measured and calculated using the following formula: , C represents the titanium dissolution rate. Ti4+ Let M be the concentration of titanium ions in the Na2S2O8 solution, M be the mass of titanium ions in the precursor (the product of the mass of the ion sieve precursor and the proportion of titanium in the precursor), and V be the volume of the Na2S2O8 solution.
[0025] To further illustrate the method and product of the present invention, specific embodiments and test examples are given below.
[0026] Example 1, Preparation of precursor: 1g of lithium acetate, 0.5568g of anatase titanium dioxide, 0.2436g of Na2WO4·6H2O and 0.1372g of carbon quantum dots were added to 10mL of anhydrous ethanol and stirred continuously for 3h to mix evenly. After stirring, the mixture was sonicated for 10min. The ethanol was evaporated and dried at 60℃. After drying, the mixture was placed in a muffle furnace, heated to 290℃ and held for 1h, then heated to 600℃ and held for 2h. After cooling to room temperature, the precursor was obtained. Preparation of lithium ion sieve: Take 0.2g of precursor and add it to 100mL of 0.8mol / L Na2S2O8 solution for elution for 8h. After elution, filter to obtain solid phase, wash with deionized water and dry to obtain lithium ion sieve.
[0027] During the lithium ion adsorption test, the shaking time was 6 hours. The adsorption capacity of the lithium ion sieve in this embodiment was measured to be 37.11 mg / g, and the titanium dissolution rate was 0.68%.
[0028] X-ray diffraction analysis was performed on the precursor of this embodiment, and the final results are as follows: Figure 1 As shown in LWTOC; where, Figure 1 The image in the center is the main test image. The image on the left is a magnified view of the yellow highlighted part of the center image, and the image on the right is a magnified view of the green highlighted part of the center image. Compared with Li₂TiO₃, it can be seen that the introduction of tungsten and carbon quantum dots did not change the crystal structure of the titanium-based ion sieve matrix. Compared with LWTO, and with the addition of carbon quantum dots, the main diffraction peaks (002) and (-133) shifted to a lower 2θ, indicating that W and C were successfully loaded.
[0029] EDS analysis was performed on the precursor of this embodiment, and the final results are as follows: Figure 2 As shown in a and b, the signals for C, O, Ti, and W are the same, indicating that the elements are evenly distributed in the precursor, further demonstrating the successful loading of W and C; Figure 2 As shown in b, this further illustrates the successful loading of W and C in the embodiments of the present invention.
[0030] Example 2 differs from Example 1 in that the temperature in the preparation of the precursor is changed from 600°C to 650°C, while the rest are the same.
[0031] During the lithium ion adsorption test, the shaking time was 6 hours. The adsorption capacity of the lithium ion sieve in this embodiment was measured to be 40.06 mg / g, and the titanium dissolution rate was 0.52%.
[0032] Its cycle performance was tested: adsorption and elution were repeated 5 times (referring to the method in the titanium dissolution rate test), and the results are as follows. Figure 3 As shown, from Figure 3 As can be seen, after 5 cycles, the adsorption capacity was 36.03 mg / g, a decrease of only 7.6%. This indicates that the lithium-ion sieve prepared in this embodiment of the invention can be reused, greatly reducing the cost of use.
[0033] Example 3 differs from Example 2 in that the amount of carbon quantum dots added is 0.1829g, while all other aspects are the same.
[0034] During the lithium ion adsorption test, the shaking time was 6 hours. The adsorption capacity of the lithium ion sieve in this embodiment was measured to be 36.88 mg / g, and the titanium dissolution rate was 0.59%.
[0035] Comparative Example 1: Compared with Example 1, the difference is that Na2WO4·6H2O and carbon quantum dots were not added during the preparation of the precursor, while the rest were the same.
[0036] During the lithium ion adsorption test, the shaking time was 24 hours. The adsorption capacity of the lithium ion sieve in this embodiment was measured to be 30.79 mg / g, and the titanium dissolution rate was 1.58%.
[0037] X-ray diffraction analysis was performed on the precursor of this comparative example, and the final results are as follows: Figure 1 As shown in the figure, the diffraction peaks of Li2TiO3 correspond well with those of pure Li2TiO3 phase (JCPDS33-0831), and there are no impurity peaks.
[0038] Comparative Example 2: Compared with Example 1, the difference is that no carbon quantum dots were added during the preparation of the precursor, but all other aspects are the same.
[0039] During the lithium ion adsorption test, the shaking time was 24 hours. The adsorption capacity of the lithium ion sieve in this embodiment was measured to be 32.53 mg / g, and the titanium dissolution rate was 1.21%.
[0040] X-ray diffraction analysis was performed on the precursor of this comparative example, and the final results are as follows: Figure 1 As shown in the LWTO diagram, it can be seen from the figure that tungsten doping did not change the structure of LTO. At the same time, with the doping of tungsten, the main diffraction peaks (002) and (-133) shifted to a lower 2θ, which, based on Bragg's law, indicates that the introduction of tungsten caused crystal expansion.
[0041] The present invention has been disclosed above with preferred embodiments. However, those skilled in the art should understand that these embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Further improvements can be made without departing from the principles of the invention, and these improvements should also be considered as protections of the present invention.
Claims
1. A method for preparing a titanium-based lithium-ion sieve, characterized in that, Includes the following steps: Lithium source, anatase titanium dioxide, tungsten source and carbon quantum dots are mixed evenly and pre-sintered at 290~350℃ for 50~80min, then heated to 550~750℃ and calcined for 1.5~3h, and then naturally cooled to obtain the precursor. Take the precursor, elute it in an aqueous sodium thiosulfate solution, and dry the eluted solid phase to obtain the product.
2. The method for preparing a titanium-based lithium-ion sieve according to claim 1, characterized in that, The molar ratio of the lithium source, anatase titanium dioxide, and tungsten source is 2:(1-x):x, where x = 0.02~0.15, and the mass of the carbon quantum dot is 5~25% of the sum of the masses of the lithium source, anatase titanium dioxide, and tungsten source.
3. The method for preparing a titanium-based lithium-ion sieve according to claim 1, characterized in that, The concentration of the sodium thiosulfate aqueous solution is 0.4~1.2 mol / L, and the concentration of the precursor in the sodium thiosulfate aqueous solution is 0.5~4 g / L.
4. The method for preparing a titanium-based lithium-ion sieve according to claim 1, characterized in that, The elution time for the elution operation is 4 to 8 hours.
5. The method for preparing a titanium-based lithium-ion sieve according to claim 1, characterized in that, The preparation method of the anatase titanium dioxide includes the following steps: adding tetrabutyl titanate dropwise to a mixed solvent of ethanol / water while stirring continuously, aging for 8-16 hours after the addition is complete, and then drying to obtain an intermediate; taking the intermediate and calcining it at 350-600℃ for 1-5 hours to obtain the final product.
6. The method for preparing a titanium-based lithium-ion sieve according to claim 1, characterized in that, The preparation method of the carbon quantum dots includes the following steps: biomass is calcined in an inert atmosphere at 200-400℃ to obtain biochar, and then the biochar is added to a mixed solution of sodium hydroxide and hydrogen peroxide, and stirred continuously for 8 hours. After stirring, acid is added to adjust the pH to 8-9, and dialysis is performed. After dialysis, the solid phase is taken and freeze-dried to obtain the final product. The mass ratio of hydrogen peroxide to biochar is 5-30:1, and the molar ratio of hydrogen peroxide to sodium hydroxide is 1-10:
1.
7. The method for preparing a titanium-based lithium-ion sieve according to claim 1, characterized in that, The lithium source is one of lithium acetate, lithium carbonate, or lithium hydroxide, and the tungsten source is one of tungstate or tungsten oxide.
8. A titanium-based lithium-ion sieve, prepared by the method described in any one of claims 1 to 7.