Titanium adsorbent and preparation method thereof

Abstract

The preparation method comprises the following steps: uniformly mixing a lithium titanate precursor with a filling agent to obtain mixed powder, adding an adhesive, a pore forming agent and a solvent into the mixed powder, uniformly mixing to obtain mixed slurry, extruding the mixed slurry, shaping, and activating in sulfuric acid to obtain the titanium adsorbent. And the filling agent is aluminum powder or zinc powder. The titanium adsorbent can keep the structure stable after being activated by sulfuric acid, and the service life of the titanium adsorbent is prolonged.

Description

Technical Field

[0001] The present application relates to the field of adsorbents, and in particular to a titanium-based adsorbent and a preparation method thereof. Background Art

[0002] As global energy demand grows and the resulting environmental pollution creates a growing gap in demand for clean energy, rechargeable batteries, a typical energy storage device, are experiencing rapid growth. Lithium-ion batteries, due to their lightweight construction, are widely used in the new energy vehicle industry. However, the overwhelming demand for these batteries has led to a shortage of lithium. As the availability of terrestrial lithium ore resources decreases, the focus of lithium resource acquisition is shifting from terrestrial ores to salt lake brines, seawater, and lithium recovery solutions. Against this backdrop, liquid-phase lithium extraction technology is rapidly developing, with adsorption methods, among others, attracting high hopes due to their environmental friendliness, simplicity, high selectivity, and high recovery rates.

[0003] However, the three commonly used adsorbents - aluminum-based adsorbents, titanium-based adsorbents and manganese-based adsorbents - all have intolerance to sulfuric acid systems, that is, they have lifespan limitations when used long-term in a sulfuric acid environment. This means that in subsequent large-scale industrial applications, a series of problems such as reduced efficiency or even failure will occur.

[0004] Therefore, the research and development of a class of sulfate-resistant lithium ion sieve adsorbents is of great significance for the large-scale application of adsorption methods. Among them, titanium-based adsorbents have significant advantages such as high adsorption capacity and high selectivity. In addition, most of the common sulfuric acid system lithium extraction solutions are alkaline, which is extremely suitable for the use scenarios of titanium-based adsorbents. Summary of the Invention

[0005] The purpose of this application is to provide a titanium-based adsorbent with a stable structure and a preparation method thereof.

[0006] To achieve the above objectives, the technical solution adopted in this application is: to provide a titanium-based adsorbent, the preparation raw materials include: lithium titanate precursor, filler, adhesive, pore-forming agent and solvent, the filler is aluminum powder or zinc powder, and the titanium-based adsorbent is activated by sulfuric acid for adsorption.

[0007] As a preference, the titanium-based adsorbent is in the form of spherical particles of 0.5 to 3 mm.

[0008] The present application also provides a method for preparing a titanium-based adsorbent, comprising mixing a lithium titanate precursor and a filler to obtain a mixed powder, adding an adhesive, a pore-forming agent, and a solvent to the mixed powder, and mixing them evenly to obtain a mixed slurry, extruding and shaping the mixed slurry, and then activating it in sulfuric acid to obtain the titanium-based adsorbent, wherein the filler is aluminum powder or zinc powder.

[0009] As another preference, the mass ratio of the lithium titanate precursor to the filler is (16-19): (1-4).

[0010] As another preference, the mass ratio of the lithium titanate precursor to the filler is 9:1.

[0011] As another preferred embodiment, the mass ratio of the mixed powder, the binder, the pore-forming agent and the solvent is (15-20): (1-5): (1-5): (5-15).

[0012] As another preference, the mass ratio of the mixed powder, the binder, the pore-forming agent and the solvent is 17:3:2:10.

[0013] As another preference, the concentration of the sulfuric acid is 0.01-0.05 mol / L.

[0014] As another preferred embodiment, the mixed slurry is extruded and granulated by a screw to obtain spherical particles with a diameter of 0.5 to 3 mm.

[0015] More preferably, the binder is polytetrafluoroethylene, the pore-forming agent is sodium chloride, and the solvent is N-methyl-2-pyrrolidone.

[0016] Compared with the prior art, the present invention has the following advantages: (1) The present application uses a lithium titanate precursor, a filler, an adhesive and a pore-forming agent to prepare a titanium-based adsorbent, which can reduce the damage to the material structure of the titanium-based adsorbent caused by the sulfuric acid acidification process and significantly extend the service life of the titanium-based adsorbent.

[0017] (2) The titanium-based adsorbent of the present application has a good lithium ion adsorption effect, is simple to prepare, and is low-cost, making it suitable for promotion to large-scale industrial applications. DETAILED DESCRIPTION

[0018] Below, the present application is further described in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0019] The terms "comprises" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, product or apparatus.

[0020] The present application provides a titanium-based adsorbent, the preparation raw materials of which include: a lithium titanate precursor, a filler, an adhesive, a pore-forming agent and a solvent.

[0021] The present application adds fillers to the raw materials for preparing titanium-based adsorbents, which slows down the structural damage of sulfuric acid molecules to the active components in the adsorbent in a sulfuric acid environment, maintains a good lithium ion adsorption effect, and greatly extends the service life of the adsorbent.

[0022] The filler is aluminum powder or zinc powder, commonly used in the industry. The mass ratio of lithium titanate precursor to filler is (16-19): (1-4).

[0023] The mass ratio of lithium titanate precursor to filler will affect the adsorption performance and dissolution rate of the titanium-based adsorbent. If less filler is added during the preparation process, the stability of the titanium-based adsorbent structure will be affected. If excessive filler is added, the number of active sites in the adsorbent may be reduced, thereby reducing the lithium ion adsorption capacity.

[0024] The titanium-based adsorbent of the present application significantly improves the stability of the adsorbent while retaining the inherent high adsorption activity of lithium titanate as sites to the maximum extent, achieving highly selective adsorption of lithium ions, which is crucial for the efficient extraction of lithium from salt lake brine or recovered liquid with complex components, and ensures the purity and recovery rate of the final lithium product.

[0025] In addition, the titanium-based adsorbent of the present application has a high resolution rate, and the adsorbed lithium ions can be efficiently eluted using low-concentration sulfuric acid, thereby regenerating the adsorbent, reducing acid consumption and subsequent neutralization treatment costs, and also indicating that the activation and filling additions do not block the lithium ion diffusion channels or form sites that are difficult to resolve.

[0026] In some preferred embodiments, the mass ratio of the lithium titanate precursor to the filler is 9:1.

[0027] In some embodiments, the binder is polytetrafluoroethylene, the pore-forming agent is sodium chloride, and the solvent is N-methyl-2-pyrrolidone.

[0028] In some preferred embodiments, the titanium-based adsorbent is in the form of 0.5-3 mm spherical particles, and preferably, the size of the titanium-based adsorbent is in the form of 1-2 mm spherical particles.

[0029] From the perspective of performance advantages, the titanium-based adsorbent of the present application has outstanding performance in many aspects. First, in terms of structural stability, by adding aluminum powder or zinc powder as a filler, during sulfuric acid activation and subsequent use, the filler can react moderately with sulfuric acid to form a protective interface layer, effectively slowing down the erosion of sulfuric acid molecules on the active ingredients of the lithium titanate precursor, thereby enabling the adsorbent to maintain a stable structure in the sulfuric acid system for a long time. Performance test data show that compared with the control example without the addition of filler, the titanium-based adsorbent prepared in the present application has a significantly reduced annualized dissolution loss rate, among which the optimal embodiment reduces the annualized dissolution loss rate by about 79%, which means that the service life of the adsorbent has been extended several times, greatly reducing the replacement cost and maintenance costs in industrial applications.

[0030] The present application also provides a method for preparing a titanium-based adsorbent: a lithium titanate precursor and a filler are mixed evenly to obtain a mixed powder, an adhesive, a pore-forming agent and a solvent are added to the mixed powder, and the mixture is mixed evenly to obtain a mixed slurry; the mixed slurry is extruded, shaped and activated in sulfuric acid to obtain a titanium-based adsorbent.

[0031] In some embodiments, the filler is aluminum powder or zinc powder, and the mass ratio of the lithium titanate precursor to the filler is (16-19): (1-4).

[0032] Preferably, the mass ratio of the lithium titanate precursor to the filler is 9:1.

[0033] In some preferred embodiments, the mass ratio of the mixed powder, binder, pore former and solvent is (15-20): (1-5): (1-5): (5-15).

[0034] In some preferred embodiments, the mass ratio of the mixed powder, binder, pore former and solvent is 17:3:2:10.

[0035] In some embodiments, the binder is polytetrafluoroethylene (PTFE), the pore-forming agent is sodium chloride, and the solvent is N-methyl-2-pyrrolidone (NMP). The addition of PTFE ensures sufficient mechanical strength for the adsorbent during molding. The pore-forming agent creates a rich pore structure within the adsorbent, which facilitates the rapid diffusion and adsorption of lithium ions. The solvent, N-methyl-2-pyrrolidone (NMP), dissolves the binder and adjusts the viscosity of the slurry for subsequent extrusion molding.

[0036] In some preferred embodiments, the concentration of sulfuric acid is 0.01-0.05 mol / L.

[0037] In some preferred embodiments, the mixed slurry is extruded and granulated by a screw to obtain a spherical granular titanium-based adsorbent, the adsorbent particle size of which is 0.5-3 mm, preferably 1-2 mm.

[0038] This molding process is crucial to the performance of the adsorbent. Spherical particles not only have a large specific surface area, which is conducive to improving adsorption efficiency, but their regular shape can also reduce fluid resistance in industrial applications, making it easier to fill and operate the adsorption column.

[0039] The formed particles are then activated in a sulfuric acid solution at a concentration of 0.01-0.05 mol / L. This activation process is a critical step that optimizes the adsorbent's surface structure and chemical properties, creating more active sites and significantly improving its lithium ion adsorption capacity.

[0040] The preparation method of the titanium-based adsorbent of the present application has a simple and easy-to-understand preparation process, does not require the purchase of additional equipment, uses cheap and readily available raw materials, has a high success rate, and is suitable for large-scale application in industrial production.

[0041] The titanium-based adsorbent of the present application, as well as the titanium-based adsorbent prepared by the above-mentioned preparation method, is suitable for adsorbing lithium ions in a sulfuric acid system, and has the advantages of high lithium ion selectivity, stable structure, and high cost performance.

[0042] Example 1 800 g of lithium titanate precursor was mixed with 200 g of aluminum powder to obtain a mixed powder. 180 g of PVDF, 120 g of NaCl, and 600 g of NMP solvent were then added and mixed to obtain a mixed slurry. This was then extruded and shaped to obtain adsorbent particles, which were white, spherical particles measuring 1 to 2 mm in diameter. 500 g of the activated adsorbent particles were stirred in 5 L of 0.05 mol / L sulfuric acid solution for 2 h. The activated adsorbent particles were then acidified in the sulfuric acid solution and dried at 50°C for later use. The lithium titanate precursor was manufactured in-house.

[0043] Example 2 900 g of lithium titanate precursor and 100 g of aluminum powder were mixed to obtain a mixed powder. 180 g of PVDF, 120 g of NaCl, and 600 g of NMP solvent were then added and mixed to obtain a mixed slurry. This was then extruded and shaped to obtain adsorbent particles, which were white, spherical particles with a diameter of 1-2 mm. 500 g of the activated adsorbent particles were stirred in 5 L of 0.05 mol / L sulfuric acid solution for 2 h. The activated adsorbent particles were acidified in the sulfuric acid solution and then dried at 50°C for later use. The lithium titanate precursor was manufactured in-house.

[0044] Example 3 950 g of lithium titanate precursor and 50 g of aluminum powder were mixed to obtain a mixed powder. 180 g of PVDF, 120 g of NaCl, and 600 g of NMP solvent were then added and mixed to obtain a mixed slurry. This was then extruded and shaped to obtain adsorbent particles, which were white, spherical particles measuring 1 to 2 mm. 500 g of the activated adsorbent particles were stirred in 5 L of 0.05 mol / L sulfuric acid solution for 2 h. The activated adsorbent particles were acidified in the sulfuric acid solution and then dried at 50°C for later use. The lithium titanate precursor was manufactured in-house.

[0045] Example 4 900 g of lithium titanate precursor and 100 g of zinc powder were mixed to obtain a mixed powder. 180 g of PVDF, 120 g of NaCl, and 600 g of NMP solvent were then added and mixed to obtain a mixed slurry. This was then extruded and shaped to obtain adsorbent particles, which were white, spherical particles with a diameter of 1-2 mm. 500 g of the activated adsorbent particles were stirred in 5 L of 0.05 mol / L sulfuric acid solution for 2 h. The activated adsorbent particles were acidified in the sulfuric acid solution and then dried at 50°C for later use. The lithium titanate precursor was manufactured in-house.

[0046] Comparative Example 1 1000 g of lithium titanate precursor was mixed with 180 g of PVDF, 120 g of NaCl, and 600 g of NMP solvent to obtain a mixed slurry. This was then extruded and shaped to obtain adsorbent particles, which were white, spherical particles with a diameter of 1 to 2 mm. 500 g of the activated adsorbent particles were stirred in 5 L of 0.05 mol / L sulfuric acid solution for 2 h. The activated adsorbent particles were acidified in the sulfuric acid solution and then dried at 50°C for later use. The lithium titanate precursor was manufactured in-house.

[0047] Performance evaluation The adsorbents prepared in Examples 1 to 4 and Comparative Example 1 were subjected to performance evaluation tests in a lithium precipitation mother liquor. The lithium precipitation mother liquor had the following composition: lithium ions: 2137 mg / L; sodium ions: 68590 mg / L; potassium ions: 275 mg / L; calcium ions: 85 mg / L; magnesium ions: 114 mg / L; sulfate: 143520 mg / L; and solution pH = 12.70.

[0048] The adsorbent particles to be tested were loaded into a dedicated resin column for a single-column experiment. Multiple cycles of adsorption and desorption testing were performed using an adsorption-wash-desorption-acid-wash method. During the adsorption phase, 300 g of acidified adsorbent was loaded into the resin column. 3 L of lithium precipitation mother liquor was pumped through the column at a flow rate of 15 mL / min using a peristaltic pump. Samples were taken before and after adsorption. Washing stage: 1.2 L of pure water was driven through the column by a peristaltic pump at a flow rate of 10 mL / min to wash away the residual brine on the adsorbent surface; Desorption stage: 2 L of 0.05 mol / L sulfuric acid solution was circulated through the column at a rate of 100 mL / min, and the pH of the feed solution was maintained at 1.20 by adding 4 mol / L sulfuric acid solution; Acid Wash Phase: 1.2 L of pure water was pumped through the column at a flow rate of 10 mL / min via a peristaltic pump to remove any residual acid from the adsorbent surface. After each phase, the column was drained before proceeding to the next phase. The adsorption phase marked the beginning of a new experiment, while the acid wash phase concluded a new experiment.

[0049] The lithium precipitation mother liquor, adsorption tail liquid and desorption liquid were tested using the test method recorded in the national standard GB / T 30902-2014. + 、Ti 4+ The adsorption capacity, desorption capacity and dissolution loss rate are calculated by the following formula; The relevant calculation formula is as follows: Adsorption capacity = (c 沉锂母液Li - c 吸附尾液Li ) × V 沉锂母液 / m 吸附剂 , g / g Desorption capacity = c 解吸液Li × V 解吸液 / m 吸附剂 , g / g Single dissolution loss rate = c 解吸液Ti × V 解吸液 / (m 前驱体 × 0.436) × 100%, % Annualized dissolution loss rate = single dissolution loss × 300 × 2, % c 沉锂母液Li ——Li concentration in lithium precipitation mother liquor, g / L c 吸附尾液Li ——Li concentration in adsorption tail liquid, g / L V 沉锂母液 ——Volume of lithium precipitation mother liquor, L m 吸附剂 ——Mass of adsorbent, g m 前驱体 ——Mass of lithium titanate precursor, g c 解吸液Li ——Li concentration of desorption solution, g / L V 解吸液 ——Desorption liquid volume, L 0.436——Titanium content per gram of lithium titanate precursor, g / g After 30 rounds of adsorption and desorption, the average values ​​were calculated and shown in Table 1 below.

[0050] Table 1 Adsorption / desorption performance and dissolution loss rate of adsorbent materials of Examples 1 to 4 and Comparative Example 1

[0051] Analyzing the annualized dissolution loss results of the examples and the comparative examples in Table 1, the annualized dissolution loss of the titanium-based adsorbents prepared in each example is much smaller than that of the comparative example. The optimal test result of Example 1 reduces the annualized dissolution loss of the titanium-based adsorbent by approximately 79%. The above shows that the present application can significantly extend the service life of the adsorbent by adding a filler to the titanium-based adsorbent, which is conducive to promoting the subsequent large-scale application of titanium-based adsorbents in the field of lithium extraction.

[0052] Based on the single dissolution test data, the titanium-based adsorbent prepared in the examples of this application exhibited significantly less dissolution than the adsorbent material prepared in the comparative examples. The highest single dissolution rate was 0.019%, which was still approximately 44% lower than that of the comparative example. The titanium-based adsorbent prepared in this application maintained structural stability in sulfuric acid systems, facilitating large-scale applications.

[0053] From the analysis of adsorption capacity and desorption capacity, the adsorbent prepared in each embodiment of the present application has a good lithium ion adsorption effect, and the addition of the filler has little effect on the lithium ion adsorption effect of the titanium-based adsorbent. Moreover, at the same ratio of lithium titanate precursor and filler in Example 1 and Example 3, the adsorption effect of using zinc powder as a filler is slightly better than that of using aluminum powder as a filler, and the dissolution rate of the adsorbent using aluminum powder as a filler is lower than that using zinc powder as a filler.

[0054] Analysis of the performance test results of Examples 1 to 5 shows that adjusting the mass ratio of the lithium titanate precursor to the filler in Examples 1 to 3 has a certain effect on the adsorption capacity and dissolution rate of the titanium-based adsorbent. The preferred mass ratio of the lithium titanate precursor to the filler is 9:1.

[0055] The above describes the basic principles, main features, and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-described embodiments. The above-described embodiments and the specification merely illustrate the principles of the present application. Various changes and improvements may be made to the present application without departing from the spirit and scope of the present application. These changes and improvements fall within the scope of the present application for which protection is sought. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.

Claims

1. A titanium-based adsorbent, characterized in that: The preparation raw materials include: lithium titanate precursor, filler, adhesive, pore-forming agent and solvent. The filler is aluminum powder or zinc powder. The titanium-based adsorbent is activated by sulfuric acid and used for adsorption.

2. The titanium-based adsorbent according to claim 1, wherein The titanium-based adsorbent is in the form of spherical particles with a size of 0.5 to 3 mm.

3. A method for preparing a titanium-based adsorbent, characterized in that: A lithium titanate precursor and a filler are mixed evenly to obtain a mixed powder, an adhesive, a pore-forming agent and a solvent are added to the mixed powder, and mixed evenly to obtain a mixed slurry, and the mixed slurry is extruded, shaped and then activated in sulfuric acid to obtain a titanium-based adsorbent, wherein the filler is aluminum powder or zinc powder.

4. The preparation method according to claim 3, wherein The mass ratio of the lithium titanate precursor to the filler is (16-19): (1-4).

5. The preparation method according to claim 4, wherein The mass ratio of the lithium titanate precursor to the filler is 9:

1.

6. The preparation method according to claim 3, wherein The mass ratio of the mixed powder, the binder, the pore-forming agent and the solvent is (15-20): (1-5): (1-5): (5-15).

7. The preparation method according to claim 6, wherein The mass ratio of the mixed powder, the binder, the pore-forming agent and the solvent is 17:3:2:

10.

8. The preparation method according to claim 3, wherein The concentration of the sulfuric acid is 0.01-0.05 mol / L.

9. The preparation method according to claim 3, wherein The mixed slurry is extruded and granulated by a screw to obtain spherical particles with a diameter of 0.5-3 mm.

10. The preparation method according to claim 3, wherein The adhesive is polytetrafluoroethylene, the pore-forming agent is sodium chloride, and the solvent is N-methyl-2-pyrrolidone.

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