High-temperature-resistant lithium-extraction adsorbent with high adsorption and anti-dissolution loss and use thereof

Abstract

The application belongs to the technical field of salt lake lithium extraction adsorbents, and particularly relates to a titanium-based salt lake lithium extraction adsorbent resistant to high temperature, high adsorption and anti-dissolution loss and application thereof. The adsorbent is prepared by mixing a titanium-silicon molecular sieve with a zinc source, a boron source, a second silicon source, a second titanium source and an aluminum source, ball-milling at 80-120 DEG C and drying to obtain an adsorbent raw powder, and then performing slurry hanging treatment on a polyurethane porous sponge skeleton to obtain the adsorbent. + The saturated adsorption capacity is greater than 45 mg / g, and the saturated adsorption capacity is greater than 40 mg / g after 300 cycles.

Description

Technical Field

[0001] This invention belongs to the technical field of lithium extraction adsorbents from salt lakes, specifically relating to a high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes and its applications. Background Technology

[0002] With the growth of new energy vehicles and the energy storage industry, lithium resources, as a key raw material, are becoming increasingly prominent. Salt lake brines are an important part of global lithium resources, and the efficient and environmentally friendly extraction of lithium from salt lake brines with high magnesium-to-lithium ratios and complex compositions has become a focus of global technological competition.

[0003] Adsorption methods are considered one of the most promising technologies for lithium extraction from salt lakes due to their high selectivity for lithium ions, environmental friendliness, and short process flow. Among these, titanium-based lithium ion sieves (such as spinel-type lithium titanate Li4Ti5O) are particularly valuable. 12 and its protonation product H4Ti5O 12 Metatitanic acid (H2TiO3, etc.) is due to its excellent Li + / Mg 2+ Titanium-based lithium-ion sieves have attracted much attention due to their selectivity (separation coefficients can reach over 1000), good chemical stability, and low cost. However, existing titanium-based lithium-ion sieves still face many challenges in industrial applications: First, titanium-based lithium-ion sieves prepared by traditional solid-phase or liquid-phase methods are mostly micron or nano-sized powders. Direct application in adsorption towers can cause filtration difficulties, bed compaction, pipe blockage, and severe fluid pressure drop. Although granulation by adding organic or inorganic binders is a common solution, binders often block some adsorption active sites, leading to a decrease in adsorption capacity and adsorption rate. Furthermore, the stability of the binder itself (especially in acidic eluents and high-temperature brine) also limits the adsorbent's lifespan. Second, high-temperature environments, such as geothermal brine, place stringent demands on the structural stability of the adsorbent.

[0004] Prolonged thermal cycling between high-temperature brine and acidic eluent can easily lead to thermal stress in the adsorbent material, causing lattice distortion, microcracks, and even structural collapse, resulting in a rapid decline in adsorption performance. Furthermore, during the long-term "adsorption-elution" cycle, especially in the acidic elution step, the framework of the titanium-based lithium ion sieve inevitably undergoes trace dissolution, known as "titanium loss." Although some studies have reported low loss rates, after hundreds of cycles, the accumulated titanium loss still damages the crystal structure of the adsorbent, reducing its active sites, decreasing structural stability, and ultimately shortening its lifespan. CN202411408716.5 (A titanium-based adsorbent material for lithium extraction from salt lakes and its preparation method) provides a titanium-based adsorbent material that requires multiple magnetic field sintering techniques. Although this improves the adsorption capacity, the highest adsorption capacity does not exceed 35 mg / g, and it is difficult to apply to operating temperatures above 80℃ (most are 30℃~60℃). CN202411411927.4 (A titanium-based particulate adsorbent and its preparation method) provides a titanium-based adsorbent material that requires preparation using a microwave combined with ultrasonication method. It has the advantage of resistance to solvent damage, but it is also difficult to apply to operating temperatures above 80℃ and its adsorption capacity is only ≥10mg / g. CN202410249795.3 (A lithium-ion adsorbent and its preparation method and application) provides a titanium-based adsorbent material that requires the use of binders, pore-forming agents, and ion atomization technology for preparation. It has the advantage of resistance to solvent damage, but it is also difficult to apply to operating temperatures above 80℃ and its adsorption capacity does not exceed 5mg / L.

[0005] Therefore, developing a granular titanium-based lithium-ion sieve adsorbent that combines high mechanical strength, excellent thermal shock resistance, long-term stable operation in high-temperature environments, and extremely low titanium dissolution rate is a key technical challenge that urgently needs to be solved to promote the industrial application of adsorption-based lithium extraction technology from salt lakes. Summary of the Invention

[0006] To address the above problems, the purpose of this invention is to provide a high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes and its applications.

[0007] First, this invention provides a high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes, belonging to a composite adsorbent based on titanium-based adsorbents. The preparation method of the composite adsorbent includes the following steps: Step S1: Preparation of titanium-silicon-lithium molecular sieve: At room temperature, a first silicon source, a first titanium source, a lithium source, a structure directing agent, an alkali source, and deionized water are added to a reaction vessel. After stirring at 30℃~50℃ for 0.5h~2h, the mixture is crystallized at 150℃~180℃ for 70h~120h. After filtration and washing, the mixture is dried at 80℃~120℃ for 8h~12h, then calcined at 550℃~650℃ for 5h~10h, and cooled to room temperature to obtain a titanium-silicon-lithium molecular sieve.

[0008] Step S2: Preparation of titanium-silicon molecular sieve: At room temperature, the titanium-silicon lithium molecular sieve obtained in step S1, acid source and deionized water are added to the reaction vessel and stirred at 60℃~80℃ for 8h~12h. After filtration, washing and drying, it is calcined at 400℃~500℃ for 4~10h and then cooled to room temperature to obtain titanium-silicon molecular sieve.

[0009] Step S3: Preparation of adsorbent raw material powder: At room temperature, the titanium-silicon molecular sieve, zinc source, boron source, second silicon source, second titanium source and aluminum source obtained in step S2 are mixed and ball-milled, dried at 80℃~120℃ for 8h~12h, ball-milled and dried again, then ground and sieved to obtain adsorbent raw material powder.

[0010] Step S4: Preparation of polyurethane porous sponge skeleton: At room temperature, after cleaning and dust removal, the polyurethane porous sponge is soaked in an alkaline solution at 30℃~40℃ for 5h~10h. The soaked polyurethane porous sponge is then washed with deionized water until the cleaning solution is neutral, dried at 80℃~120℃ for 8h~12h, and then soaked in an organic solution at 30℃~40℃ for 5h~10h. After soaking, it is taken out and dried at 80℃~120℃ for 8h~12h to obtain the polyurethane porous sponge skeleton.

[0011] Step S5: Preparation of composite adsorbent: At room temperature, the adsorbent raw material powder, binder and deionized water obtained in step S3 are stirred and mixed to obtain a mixed slurry. The polyurethane porous sponge skeleton obtained in step S4 is immersed in the mixed slurry for 24h to 48h, dried at 80℃ to 120℃ for 12h to 24h, calcined at 600℃ to 800℃ for 5h to 10h, and then cooled to room temperature to obtain the composite adsorbent.

[0012] Preferably, in step S1, the first silicon source is selected from silica sol or fumed silica; the first titanium source is selected from tetraethyl titanate or tetraisopropyl titanate; the lithium source is selected from lithium nitrate or lithium hydroxide; the structure directing agent is selected from tetrapropylammonium hydroxide or N,N,N-trimethyl-1-adamantyl ammonium hydroxide; the alkali source is selected from ethylenediamine or tetramethylammonium hydroxide; and the mass ratio of the first silicon source: first titanium source: lithium source: structure directing agent: alkali source: deionized water is (40-70):(1-3):1:(1-3):(1-6):(600-1200).

[0013] Preferably, in step S2, the acid source is selected from citric acid or malic acid; the mass ratio of the titanium-silicon-lithium molecular sieve: acid source: deionized water is 1:(10-20):(300-500).

[0014] Preferably, in step S3, the zinc source is selected from zinc oxide or zinc hydroxide; the boron source is selected from borax or boron phosphate; the second silicon source is selected from silicon dioxide or sodium silicate; the second titanium source is selected from titanium dioxide or titanium dioxide; the aluminum source is selected from alumina or aluminum hydroxide; the mass ratio of the titanium-silicon molecular sieve: zinc source: boron source: second silicon source: titanium source: aluminum source is 1:(0.2~0.25):(0.4~0.5):(0.05~0.13):(0.05~0.1):(0.05~0.1); the ball milling is carried out using a planetary ball mill for mixing and ball milling, and in the ball milling, the mass ratio of powder: agate balls: water is 1:(3~5):(2~4), the ball mill speed is 400rpm~600rpm, and the ball milling time is 3h~5h; the grinding and sieving is done with a 40-60 mesh sieve.

[0015] Preferably, in step S4, the polyurethane porous sponge is selected from polyurethane porous sponge with a viscosity of 30 PPI to 40 PPI; the alkaline solution is selected from 2 wt% to 5 wt% NaOH solution; and the organic solution is selected from 3 wt% to 10 wt% polyvinyl alcohol aqueous solution or polyethylene glycol aqueous solution.

[0016] Preferably, in step S5, the binder is selected from starch or dextrin powder; the mass ratio of the adsorbent raw material powder: binder: deionized water is 1:(1-3):(10-20).

[0017] Research and testing have shown that the aforementioned adsorbent Li + The saturated adsorption capacity is greater than 45 mg / g, and after 300 cycles, the saturated adsorption capacity is greater than 40 mg / g.

[0018] Secondly, this invention provides the application of the aforementioned adsorbent for high-temperature lithium extraction.

[0019] The silica mentioned above refers to ordinary block or granular silica (generally micron-sized), while the aforementioned fumed silica refers to extremely fine powdered silica (generally nano-sized) prepared by vapor deposition.

[0020] The adsorbent of the present invention has the following beneficial effects:

[0021] The adsorbent of this invention has advantages over traditional titanium-based adsorbents, including high temperature resistance (adapted to adsorption at 80℃), high adsorption capacity, and long lifespan (Li). + It has the advantages of saturated adsorption capacity greater than 45 mg / g, and saturated adsorption capacity greater than 40 mg / g after 300 cycles of use, and resistance to solvent damage.

[0022] The beneficial effects are attributed to the addition of zinc, boron, second silicon, second titanium, and aluminum sources, as well as the specific preparation method, in step S3 of the adsorbent raw material powder preparation. They also benefit from the polyurethane porous sponge framework, which not only provides the adsorbent with a rich pore structure but also offers excellent protection. Furthermore, the one-step sintering of the adsorbent raw material powder and the polyurethane porous sponge framework after coating with a slurry significantly improves the distribution characteristics of the adsorbent powder and the bonding performance and stability of the adsorbent with the ZnO-B2O3-SiO2-TiO2-Al2O3 framework matrix.

[0023] The ZnO-B2O3-SiO2-TiO2-Al2O3 composite system (containing a ZnBSiTiAl mixed oxide structure, not specifically referring to the decoupled composition of ZnO-B2O3-SiO2-TiO2-Al2O3; the same applies below) can serve as a bonding and supporting framework matrix for titanium-based lithium-ion sieves. Its sintering temperature is designed between 600 and 800℃, a temperature sufficient to soften and flow the glassy phase, achieving effective coating and bonding of the titanium-based lithium-ion sieve, while avoiding unnecessary phase transformations or oxidation between the titanium-based lithium-ion sieve and titanium metal that may occur at excessively high temperatures.

[0024] The low-melting-point glassy phase softens and coats the titanium-based lithium-ion sieve particles, while also facilitating microscopic chemical reactions at the interface, forming an interfacial transition layer. This chemical bonding exhibits higher bonding strength compared to traditional physical mixing or organic bonding. By controlling the chemical composition of the ZnO-B2O3-SiO2-TiO2-Al2O3 composite system, its thermal expansion coefficient can be matched with that of the titanium-based lithium-ion sieve, in Li... + / H + Ion exchange causes a slight volume change in the lattice of titanium-based lithium ion sieves, and thermal expansion and contraction caused by thermal cycling effectively bind the active particles and inhibit irreversible lattice distortion, thus ensuring the long-term stability of titanium-based adsorbents for high-temperature lithium extraction.

[0025] The ZnO-B2O3-SiO2-TiO2-Al2O3 composite system can form a microporous network during sintering, providing a smooth macroscopic channel for lithium ions to diffuse from the brine bulk to the active sites inside the adsorbent. Simultaneously, the unique electronic structure of the interface region may lower the diffusion barrier for lithium ions across the interface, thus jointly promoting adsorption kinetics at high temperatures. Furthermore, the high-temperature operation itself accelerates ion diffusion, resulting in a shorter time for the titanium-based adsorbent used for high-temperature lithium extraction in this invention to reach adsorption equilibrium, thereby improving the lithium extraction efficiency per unit time.

[0026] The ZnO-B2O3-SiO2-TiO2-Al2O3 composite system and the dense interface layer together form a physical barrier, which greatly reduces the direct contact area between the acidic eluent and the active material of the titanium-based lithium ion sieve, thereby inhibiting the dissolution of titanium and ensuring that the titanium dissolution rate is extremely low after hundreds of cycles. Attached Figure Description

[0027] Figure 1 The image shows the appearance of the titanium-based lithium extraction adsorbent prepared in Example 1.

[0028] Figure 2 Electron microscopy characterization of the titanium-based lithium extraction adsorbent prepared in Example 1. Detailed Implementation

[0029] The technical concept, solution, and effects of the present invention are described in detail below through specific embodiments. These embodiments are merely illustrative examples and are not intended to limit the scope of protection of the present invention. The raw materials used in the following embodiments and comparative examples are all commercially available; for example, polyurethane porous sponges were purchased from Jiangsu Water Elf Environmental Protection New Materials Co., Ltd. (specifications: 30 PPI and 40 PPI). In the product performance tests of the following embodiments and comparative examples:

[0030] (1) Determination of saturated adsorption capacity (mg / g) and saturated adsorption time (h):

[0031] Condition A is as follows: test temperature 80℃, test solution preparation: prepare 0.05 mol / L LiCl solution, adjust the pH to about 12 with LiOH solution, and take 100 mL of the above solution into a stoppered shaker flask (the concentration of Li+ in the test solution is about 0.42 mg / mL).

[0032] Condition B is as follows: Test temperature 30℃; Preparation of test solution: Prepare a 0.05 mol / L LiCl solution, adjust the pH to approximately 12 with LiOH solution, and pour 100 mL of the above solution into a stoppered shaker flask (the test solution contains Li...). + The concentration is approximately 0.42 mg / mL.

[0033] At different test temperatures, 0.1 g of the adsorbent to be tested was added to the test solution (100 mL), and adsorption was carried out by shaking on a shaker to detect Li. + Adsorption experiments. Parallel sampling and testing samples were set up at different time points. The samples were filtered at different time points to obtain adsorbed filtrates. The ion content was measured using inductively coupled plasma atomic emission spectrometry (ICP-AES), and the adsorption capacity of the Li-based titanium adsorbent materials for lithium extraction from salt lakes provided in each example and comparative example was calculated according to Formula I:

[0034] Formula I: Adsorption capacity = (Li in the test solution before adsorption) +Concentration - Li in the test solution after adsorption + Concentration) x test solution volume / 0.1.

[0035] The maximum adsorption capacity is the saturated adsorption capacity, and the time corresponding to the saturated adsorption capacity is the saturated adsorption time.

[0036] (2) Determination of saturated adsorption capacity and calculation of solubility loss rate after recycling:

[0037] The cyclical use condition A is: Li + The adsorption temperature is 80℃, and the acid leaching regeneration temperature is 25℃.

[0038] The recycling condition B is: Li + The adsorption temperature is 30℃, and the acid leaching regeneration temperature is 25℃.

[0039] At 25℃, 0.5g of saturated high-temperature lithium extraction adsorbent was added to 250mL of 0.5mol / L hydrochloric acid solution. The adsorbent was regenerated by acid leaching for 2 hours with stirring. After regeneration, a cyclic adsorption experiment was conducted to test the cyclic adsorption performance of the adsorbent. The adsorption capacity was calculated using Formula I.

[0040] The formula for calculating the dissolution rate is:

[0041] Formula II: Titanium-based adsorbent solubility loss rate = Ti concentration in desorption solution × desorption solution volume / (adsorbent mass × Ti content in adsorbent) × 100%. The Ti concentration in the desorption solution is determined according to the method in GB / T30902-2014. For specific test methods, please refer to the performance test method in CN117899804A.

[0042] (3) Determination and calculation method of desorption rate for repeated use: For specific test methods, please refer to the performance test method in CN117899804A. For repeated use conditions, please refer to "(2) Determination of saturated adsorption capacity and calculation of solubility loss rate after repeated use". Calculate the Li desorption capacity and desorption rate measured each time according to formulas III and IV. The Li desorption capacity and desorption rate of each sample are based on the arithmetic mean of multiple cycles (300 or 30 cycles).

[0043] Formula III: Li desorption capacity (mg / g) = (Li concentration in the desorption solution × 0.25) ÷ 0.5;

[0044] Formula IV: Li desorption rate (%) = (Li desorption capacity ÷ Li adsorption capacity) × 100%.

[0045] The unit conversions in the above formulas are common knowledge. For example, when the solution volume is calculated in L and the adsorption capacity is in mg / g, the Li concentration in the desorption solution should be mg / L.

[0046] Example 1: A high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes and its preparation.

[0047] Step S1: Preparation of lithium titanium-silicon molecular sieve: At room temperature, 400g silica sol, 10g tetraethyl titanate, 10g lithium nitrate, 10g tetrapropylammonium hydroxide, 10g ethylenediamine and 6000g deionized water were added to a reaction vessel. After stirring at 30℃ for 2h, the mixture was crystallized at 150℃ for 120h. After filtration and washing, the mixture was dried at 80℃ for 12h and then calcined at 550℃ for 10h. The mixture was then cooled to room temperature to obtain lithium titanium-silicon molecular sieve.

[0048] Step S2: Preparation of titanium-silicon molecular sieve: At room temperature, 10g of titanium-silicon lithium molecular sieve, 100g of citric acid and 3000g of deionized water were added to the reaction vessel and stirred at 60℃ for 12h. After filtration, washing and drying, the mixture was calcined at 400℃ for 10h and then cooled to room temperature to obtain titanium-silicon molecular sieve.

[0049] Step S3: Preparation of adsorbent raw material powder: At room temperature, 10g of titanium silica molecular sieve, 2g of zinc oxide, 4g of borax, 0.5g of silica, 0.5g of titanium dioxide, and 0.5g of alumina were mixed and ball-milled in a planetary ball mill at a powder:agate ball:water mass ratio of 1:3:2, a ball mill speed of 400 rpm, and a ball milling time of 5h. After mixing and ball milling, the mixture was dried at 80℃ for 12h. The mixture was then ball-milled and dried again in a planetary ball mill at a powder:agate ball:water mass ratio of 1:3:2, a ball mill speed of 400 rpm, and a ball milling time of 5h. Finally, the mixture was ground through a 40-mesh sieve to obtain the adsorbent raw material powder.

[0050] Step S4: Preparation of polyurethane porous sponge skeleton: At room temperature, after cleaning and dust removal, the 30 PPI polyurethane porous sponge is immersed in a 2 wt% NaOH solution at 30°C for 10 h. The immersed polyurethane porous sponge is then washed with deionized water until the cleaning solution is neutral and dried at 80°C for 12 h. It is then immersed in a 3 wt% polyvinyl alcohol aqueous solution at 30°C for 10 h. After immersion, it is taken out and dried at 80°C for 12 h to obtain the polyurethane porous sponge skeleton.

[0051] Step S5: Preparation of composite adsorbent: At room temperature, 10g of adsorbent raw material powder, 10g of starch, and 100g of deionized water are stirred and mixed to obtain a mixed slurry. The polyurethane porous sponge skeleton is immersed in the mixed slurry for 24h, dried at 80℃ for 24h, calcined at 600℃ for 10h, and then cooled to room temperature to obtain the composite adsorbent. Figure 1 and Figure 2 The images shown are an external view and a micrograph of the product, revealing its loose, porous structure. The densely packed pores, with their relatively large diameters, are unlikely to become clogged, thus maintaining good adsorption performance.

[0052] Example 2: A high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes and its preparation.

[0053] Step S1: Preparation of lithium titanium silicon molecular sieve: At room temperature, 700g of fumed silica, 30g of tetraisopropyl titanate, 10g of lithium hydroxide, 30g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide, 60g of tetramethyl ammonium hydroxide and 12000g of deionized water were added to a reaction vessel. After stirring at 50℃ for 0.5h, the mixture was crystallized at 180℃ for 72h. After filtration and washing, the mixture was dried at 120℃ for 8h and then calcined at 650℃ for 5h. The mixture was then cooled to room temperature to obtain lithium titanium silicon molecular sieve.

[0054] Step S2: Preparation of titanium-silicon molecular sieve: At room temperature, 10g of titanium-silicon lithium molecular sieve, 200g of malic acid and 5000g of deionized water were added to the reaction vessel and stirred at 80℃ for 8h. After filtration, washing and drying, the mixture was calcined at 500℃ for 4h and then cooled to room temperature to obtain titanium-silicon molecular sieve.

[0055] Step S3: Preparation of adsorbent raw material powder: At room temperature, 10g of titanium silicate molecular sieve, 2.5g of zinc hydroxide, 5g of boron phosphate, 1.3g of sodium silicate, 1g of titanium dioxide, and 1g of aluminum hydroxide were mixed and ball-milled in a planetary ball mill at a powder:agate ball:water mass ratio of 1:5:4, a ball mill speed of 600 rpm, and a ball milling time of 3 hours. After mixing and ball milling, the mixture was dried at 120℃ for 8 hours. The mixture was then ball-milled and dried again in a planetary ball mill at a powder:agate ball:water mass ratio of 1:5:4, a ball mill speed of 600 rpm, and a ball milling time of 3 hours. Finally, the mixture was ground through a 60-mesh sieve to obtain the adsorbent raw material powder.

[0056] Step S4: Preparation of polyurethane porous sponge skeleton: At room temperature, after cleaning and dust removal, the 40PPI polyurethane porous sponge is immersed in a 5wt% NaOH solution at 40℃ for 5h. The immersed polyurethane porous sponge is then washed with deionized water until the cleaning solution is neutral and dried at 120℃ for 8h. It is then immersed in a 10wt% polyethylene glycol aqueous solution at 40℃ for 5h. After immersion, it is taken out and dried at 120℃ for 8h to obtain the polyurethane porous sponge skeleton.

[0057] Step S5: Preparation of composite adsorbent: At room temperature, 10g of adsorbent raw material powder, 30g of dextrin powder and 200g of deionized water are stirred and mixed to obtain a mixed slurry. The polyurethane porous sponge skeleton is immersed in the mixed slurry for 48h, dried at 120℃ for 12h, calcined at 800℃ for 5h, and then cooled to room temperature to obtain the composite adsorbent.

[0058] Example 3: A high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes and its preparation.

[0059] Step S1: Preparation of lithium titanium-silicon molecular sieve: At room temperature, 600g silica sol, 20g tetraisopropyl titanate, 10g lithium nitrate, 20g N,N,N-trimethyl-1-adamantyl ammonium hydroxide, 40g ethylenediamine and 8000g deionized water were added to a reaction vessel. After stirring at 40℃ for 1.2h, the mixture was crystallized at 160℃ for 90h. After filtration and washing, the mixture was dried at 100℃ for 10h and then calcined at 600℃ for 8h. The mixture was then cooled to room temperature to obtain lithium titanium-silicon molecular sieve.

[0060] Step S2: Preparation of titanium-silicon molecular sieve: At room temperature, 10g of titanium-silicon lithium molecular sieve, 150g of malic acid and 4000g of deionized water were added to the reaction vessel and stirred at 70℃ for 10h. After filtration, washing and drying, the mixture was calcined at 450℃ for 8h and then cooled to room temperature to obtain titanium-silicon molecular sieve.

[0061] Step S3: Preparation of adsorbent raw material powder: At room temperature, 10g of titanium silica molecular sieve, 2.2g of zinc oxide, 4.5g of boron phosphate, 1g of silica, 0.8g of titanium dioxide, and 0.8g of alumina were mixed and ball-milled in a planetary ball mill at a powder:agate ball:water mass ratio of 1:4:3, a ball mill speed of 500 rpm, and a ball milling time of 4 hours. After mixing and ball milling, the mixture was dried at 100℃ for 10 hours. The mixture was then ball-milled and dried again in a planetary ball mill at a powder:agate ball:water mass ratio of 1:4:3, a ball mill speed of 500 rpm, and a ball milling time of 4 hours. Finally, the mixture was ground through a 60-mesh sieve to obtain the adsorbent raw material powder.

[0062] Step S4: Preparation of polyurethane porous sponge skeleton: At room temperature, after cleaning and dust removal, the 40 PPI polyurethane porous sponge is immersed in a 3 wt% NaOH solution at 35°C for 8 hours. The immersed polyurethane porous sponge is then washed with deionized water until the cleaning solution is neutral and dried at 100°C for 10 hours. It is then immersed in a 5 wt% polyvinyl alcohol aqueous solution at 35°C for 8 hours. After immersion, it is removed and dried at 100°C for 10 hours to obtain the polyurethane porous sponge skeleton.

[0063] Step S5: Preparation of composite adsorbent: At room temperature, 10g of adsorbent raw material powder, 20g of dextrin powder and 150g of deionized water are stirred and mixed to obtain a mixed slurry. The polyurethane porous sponge skeleton is immersed in the mixed slurry for 36h, dried at 100℃ for 18h, calcined at 700℃ for 8h, and then cooled to room temperature to obtain the composite adsorbent.

[0064] Example 4: Performance Testing of Titanium-Based Lithium Extraction Adsorbent from Salt Lakes

[0065] For the purpose of performance testing and comparison, the following comparative adsorbents and their preparation methods, tested during the research and development process, are provided:

[0066] Comparative Example 1: The adsorbent in this comparative example is a titanium-silicon molecular sieve prepared according to steps S1 and S2 of Example 1.

[0067] Comparative Example 2: The difference between the adsorbent in this comparative example and that in Example 1 is that the calcination temperature in step S5 is 1200℃.

[0068] Comparative Example 3: The difference between the adsorbent in this comparative example and Example 1 is that step S4 (no polyurethane porous sponge skeleton is added) is omitted in the preparation. Therefore, step S5 is as follows: At room temperature, 10g of adsorbent raw material powder, 10g of starch and 100g of deionized water are stirred and mixed to obtain a mixed slurry. After drying at 80°C for 24h, it is calcined at 600°C for 10h and then cooled to room temperature to obtain the adsorbent.

[0069] Comparative Example 4:

[0070] Step S1: Preparation of lithium titanium-silicon molecular sieve: At room temperature, 400g silica sol, 10g tetraethyl titanate, 10g lithium nitrate, 10g tetrapropylammonium hydroxide, 10g ethylenediamine and 6000g deionized water were added to a reaction vessel. After stirring at 30℃ for 2h, the mixture was crystallized at 150℃ for 120h. After filtration and washing, the mixture was dried at 80℃ for 12h and then calcined at 550℃ for 10h. The mixture was then cooled to room temperature to obtain lithium titanium-silicon molecular sieve.

[0071] Step S2: Preparation of titanium-silicon molecular sieve: At room temperature, 10g of titanium-silicon lithium molecular sieve, 100g of citric acid and 3000g of deionized water were added to the reaction vessel and stirred at 60℃ for 12h. After filtration, washing and drying, the mixture was calcined at 400℃ for 10h and then cooled to room temperature to obtain titanium-silicon molecular sieve.

[0072] Step S3: Preparation of raw material powder for the ZnO-B2O3-SiO2-TiO2-Al2O3 composite system: At room temperature, 2g of zinc oxide, 4g of borax, 0.5g of silicon dioxide, 0.5g of titanium dioxide, and 0.5g of aluminum oxide were mixed and ball-milled using a planetary ball mill at a powder-to-agate-ball-to-water mass ratio of 1:3:2, a mill speed of 400 rpm, and a milling time of 5 hours. After mixing and ball-milling, the mixture was dried at 80℃ for 12 hours. The mixture was then ball-milled and dried again using a planetary ball mill at a powder-to-agate-ball-to-water mass ratio of 1:3:2, a mill speed of 400 rpm, and a milling time of 5 hours. Finally, the mixture was ground through a 40-mesh sieve to obtain the raw material powder for the ZnO-B2O3-SiO2-TiO2-Al2O3 composite system.

[0073] Step S4: Preparation of polyurethane porous sponge skeleton: At room temperature, after cleaning and dust removal, the 30 PPI polyurethane porous sponge is immersed in a 2 wt% NaOH solution at 30°C for 10 h. The immersed polyurethane porous sponge is then washed with deionized water until the cleaning solution is neutral and dried at 80°C for 12 h. It is then immersed in a 3 wt% polyvinyl alcohol aqueous solution at 30°C for 10 h. After immersion, it is taken out and dried at 80°C for 12 h to obtain the polyurethane porous sponge skeleton.

[0074] Step S5: Preparation of ZnO-B2O3-SiO2-TiO2-Al2O3-polyurethane porous sponge skeleton: At room temperature, 10g of ZnO-B2O3-SiO2-TiO2-Al2O3 composite system raw material powder, 10g of starch, and 100g of deionized water were stirred and mixed to obtain a mixed slurry. The polyurethane porous sponge skeleton was immersed in the mixed slurry for 24h, dried at 80℃ for 24h, calcined at 600℃ for 10h, and then cooled to room temperature to obtain ZnO-B2O3-SiO2-TiO2-Al2O3-polyurethane porous sponge skeleton.

[0075] Step S5: Preparation of composite adsorbent: At room temperature, 10g of titanium silicon lithium molecular sieve, 10g of starch, and 100g of deionized water are stirred and mixed evenly to obtain a mixed slurry. The ZnO-B2O3-SiO2-TiO2-Al2O3-polyurethane porous sponge skeleton is immersed in the mixed slurry for 24h, dried at 80℃ for 24h, calcined at 600℃ for 10h, and then cooled to room temperature to obtain the composite adsorbent.

[0076] Table 1 Performance parameters of different adsorbents

[0077]

[0078] As shown in Table 1, compared with the Example 1 sample, although the saturated adsorption capacity of the Comparative Example 1 sample also reached 48 mg / g, the saturated adsorption capacity after 300 cycles decreased significantly to 14 mg / g. The desorption rate also decreased slightly, and the titanium dissolution rate was much higher than that of the Example 1 sample. Furthermore, the titanium dissolution rate at high temperature adsorption was higher than that at low temperature adsorption, indicating that the ZnO-B2O3-SiO2-TiO2-Al2O3 and polyurethane porous sponge system of the Examples can effectively protect the titanium-silicon molecular sieve, avoiding titanium dissolution during the long-term "adsorption-elution" cycle of the pure titanium-silicon molecular sieve.

[0079] Compared with the sample of the example, the sample Li of Comparative Example 2 + The saturated adsorption capacity is too low; this may be due to the collapse of the titanium-silicon molecular sieve structure caused by high-temperature calcination, which severely affects its Li- content. + Adsorption performance.

[0080] Compared to the sample in the examples, the sample in Comparative Example 3 showed a saturated adsorption capacity of less than 45 mg / g, and a saturated adsorption capacity of less than 40 mg / g after 300 cycles. This indicates that the pores left by the polyurethane porous sponge skeleton during the calcination process of the ZnO-B2O3-SiO2-TiO2-Al2O3 system provide unobstructed macroscopic channels for lithium ion diffusion, thereby increasing the saturated adsorption capacity of the adsorbent and shortening the adsorption equilibrium time.

[0081] Compared to the sample in the examples, although the initial saturated adsorption capacity of the sample in Comparative Example 4 was comparable to that of the examples, the saturated adsorption capacity decreased significantly after long-term cycling. This indicates that the steps and positional relationships between the ZnO-B2O3-SiO2-TiO2-Al2O3 system and the polyurethane porous sponge have a significant impact on product performance. The preparation method of this invention can ensure the long-term stability of the adsorbent.

[0082] The comparative samples exhibited problems such as excessively low saturated adsorption capacity under different temperature test conditions, low saturated adsorption capacity after different number of cycles, or excessively high solubility, indicating poor high-temperature resistance, stability, or service life. In contrast, the sample in the example showed high saturated adsorption capacity under test conditions of 30℃ and 80℃, with minimal decrease in saturated adsorption capacity after different number of cycles and extremely low solubility, demonstrating excellent high-temperature resistance and good stability.

Claims

1. A high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes, wherein the adsorbent is a composite adsorbent based on titanium-based adsorbents, characterized in that... The preparation method of the composite adsorbent includes the following steps: Step S1: Preparation of titanium-silicon-lithium molecular sieve: At room temperature, the first silicon source, the first titanium source, the lithium source, the structure directing agent, the alkali source and deionized water are added to the reaction vessel. After stirring at 30℃~50℃ for 0.5h~2h, the mixture is crystallized at 150℃~180℃ for 70h~120h. After filtration and washing, the mixture is dried at 80℃~120℃ for 8h~12h, and then calcined at 550℃~650℃ for 5h~10h. After cooling to room temperature, titanium-silicon-lithium molecular sieve is obtained. Step S2: Preparation of titanium-silicon molecular sieve: At room temperature, the titanium-silicon lithium molecular sieve obtained in step S1 is added to a reaction vessel along with an acid source and deionized water. The mixture is stirred at 60℃~80℃ for 8h~12h. After filtration, washing, and drying, the mixture is calcined at 400℃~500℃ for 4~10h and then cooled to room temperature to obtain the titanium-silicon molecular sieve. Step S3: Preparation of adsorbent raw material powder: At room temperature, the titanium-silicon molecular sieve obtained in step S2 is mixed with zinc source, boron source, second silicon source, second titanium source, and aluminum source and ball-milled. The mixture is then dried at 80℃~120℃ for 8h~12h, ball-milled again, dried, ground, and sieved to obtain adsorbent raw material powder. The mass ratio of the titanium-silicon molecular sieve:zinc source:boron source:second silicon source:second titanium source:aluminum source is 1:(0.2~0.25):(0.4~0.5):(0.05~0.13):(0.05~0.1):(0.05~0.1). Step S4: Preparation of polyurethane porous sponge skeleton: At room temperature, after cleaning and dust removal, the polyurethane porous sponge is soaked in an alkaline solution at 30℃~40℃ for 5h~10h. The soaked polyurethane porous sponge is then washed with deionized water until the cleaning solution is neutral, dried at 80℃~120℃ for 8h~12h, and then soaked in an organic solution at 30℃~40℃ for 5h~10h. After soaking, it is taken out and dried at 80℃~120℃ for 8h~12h to obtain the polyurethane porous sponge skeleton. Step S5: Preparation of composite adsorbent: At room temperature, the adsorbent raw material powder, binder and deionized water obtained in step S3 are stirred and mixed to obtain a mixed slurry. The polyurethane porous sponge skeleton obtained in step S4 is immersed in the mixed slurry for 24h to 48h, dried at 80℃ to 120℃ for 12h to 24h, calcined at 600℃ to 800℃ for 5h to 10h, and then cooled to room temperature to obtain the composite adsorbent.

2. The high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes according to claim 1, characterized in that, In step S1, the first silicon source is selected from silica sol or fumed silica; the first titanium source is selected from tetraethyl titanate or tetraisopropyl titanate; the lithium source is selected from lithium nitrate or lithium hydroxide; the structure directing agent is selected from tetrapropylammonium hydroxide or N,N,N-trimethyl-1-adamantyl ammonium hydroxide; the alkali source is selected from ethylenediamine or tetramethylammonium hydroxide; the mass ratio of the first silicon source: first titanium source: lithium source: structure directing agent: alkali source: deionized water is (40~70):(1~3):1:(1~3):(1~6):(600~1200).

3. The high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes according to claim 1, characterized in that, In step S2, the acid source is selected from citric acid or malic acid; the mass ratio of the titanium-silicon-lithium molecular sieve, acid source and deionized water is 1:(10~20):(300~500).

4. The high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes according to claim 1, characterized in that, In step S3, the zinc source is selected from zinc oxide or zinc hydroxide; the boron source is selected from borax or boron phosphate; the second silicon source is selected from silicon dioxide or sodium silicate; the second titanium source is selected from titanium dioxide or titanium dioxide; the aluminum source is selected from alumina or aluminum hydroxide; the ball milling is performed using a planetary ball mill for mixing and ball milling, and in the ball milling, the mass ratio of powder: agate balls: water is 1:(3~5):(2~4), the ball mill speed is 400 rpm~600 rpm, and the ball milling time is 3h~5h; the grinding and sieving is done with a 40 mesh~60 mesh sieve.

5. The high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes according to claim 1, characterized in that, In step S4, the polyurethane porous sponge is selected from polyurethane porous sponge with a concentration of 30 PPI to 40 PPI; the alkaline solution is selected from 2 wt% to 5 wt% NaOH solution; and the organic solution is selected from 3 wt% to 10 wt% polyvinyl alcohol aqueous solution or polyethylene glycol aqueous solution.

6. The high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes according to claim 1, characterized in that, In step S5, the binder is selected from starch or dextrin powder; the mass ratio of the adsorbent raw material powder: binder: deionized water is 1:(1~3):(10~20).

7. A high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes according to any one of claims 1 to 6, characterized in that, The adsorbent Li + The saturated adsorption capacity is greater than 45 mg / g, and after 300 cycles, the saturated adsorption capacity is greater than 40 mg / g.

8. The application of the high-temperature resistant, high-adsorption, and solvent-resistant titanium-based lithium extraction adsorbent from salt lakes as described in any one of claims 1 to 6 as a high-temperature lithium extraction adsorbent.

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