Preparation method of manganese ion sieve coupled porous ceramic molded lithium extraction adsorbent

Abstract

The invention discloses a preparation method of a manganese ion sieve coupled porous ceramic molded lithium extraction adsorbent, and relates to the technical field of ion sieve adsorption materials. The invention relates to a preparation method of a manganese-series ion sieve coupled porous ceramic molded lithium extraction adsorbent. The preparation method comprises the following steps: a, preparing two groups of manganese-series lithium ion sieve precursor solutions; b, stirring the precursor solution and porous ceramic at a constant temperature for 4-12 hours, and drying in a vacuum drying oven for 12 hours to remove moisture, so as to obtain a dried precursor and a loaded ceramic chip; c, calcining the loaded ceramic chip to obtain a crystalline manganese ion sieve; and d, putting the crystalline manganese ion sieve into an acid solution, and oscillating at constant temperature for 6-12 hours to obtain the manganese ion sieve coupled porous ceramic formed lithium extraction adsorbent. According to the manganese ion sieve coupled porous ceramic formed lithium extraction adsorbent, a sol-gel method is adopted, the load uniformity is optimized, and the specific surface area utilization rate is increased.

Description

Technical Field

[0001] This invention relates to the field of ion sieve adsorption materials technology, specifically to a method for preparing a manganese-based ion sieve coupled with porous ceramic-formed lithium extraction adsorbent. Background Technology

[0002] Lithium, hailed as an "energy metal," is a strategically vital mineral resource widely used in new energy (such as lithium-ion batteries), aerospace (light alloys), nuclear industry (coolants), and chemical industries. With the explosive growth of the lithium battery new energy industry, lithium demand is growing at an average annual rate exceeding 25%. Globally, lithium mines primarily consist of spodumene, lepidolite, and petalite, with Australia being a leading supplier (possessing some of the world's largest lithium reserves, primarily pegmatite-type deposits). Chile is also one of the world's richest lithium-producing countries. my country is a major lithium-producing nation, with abundant salt lake lithium resources possessing very high mining value.

[0003] Traditional lithium extraction processes from salt lakes typically involve evaporating and concentrating the brine (utilizing the difference in solubility between lithium and other salts to crystallize and precipitate lithium stepwise), or further extraction and separation using methods such as membrane separation, electrodialysis, granulation, carrier loading, and multi-stage extraction. However, the raw brine contains a variety of ions, making methods like membrane separation and extraction difficult to apply. Adsorption methods, on the other hand, exhibit high selectivity and adsorption capacity for lithium ions in solution. Therefore, direct extraction of lithium from salt lake brine using adsorption is the most feasible method. Ion sieve adsorbents offer significant advantages over other inorganic adsorbents in terms of adsorption capacity and selectivity for lithium ions. Ion sieve adsorbents can be classified into aluminum-based, titanium-based, and manganese-based adsorbents. Compared to the former two, manganese-based adsorbents combine high selectivity, high adsorption capacity, low toxicity, low cost, and excellent chemical stability.

[0004] Manganese-based adsorbents suffer from structural instability during lithium desorption, are prone to manganese dissolution in brine, and are generally micro- or nano-sized fine particles, making liquid-solid separation difficult and causing adhesion during lithium extraction. Furthermore, their flowability and permeability are extremely poor in fixed-bed adsorption operations, resulting in high bed resistance, which greatly limits their industrial-scale application. Summary of the Invention

[0005] The purpose of this invention is to address the problems of existing powdered manganese ion sieves, such as easy detachment, uneven load distribution, high mass transfer resistance, poor chemical stability, and poor cycle stability. This invention provides a manganese ion sieve coupled with porous ceramic-formed lithium extraction adsorbent. By enhancing structural stability, optimizing load uniformity, and improving mass transfer efficiency, it resolves the contradiction between "load stability" and "high mass transfer efficiency," making it suitable for lithium extraction in complex systems such as high magnesium-to-lithium ratio salt lakes and seawater.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing a manganese-based ion sieve coupled with porous ceramic-formed lithium extraction adsorbent, comprising the following steps:

[0007] a. Prepare two sets of manganese-based lithium ion sieve precursor solutions;

[0008] b. Stir the precursor solution with porous ceramic at a constant temperature for 4-12 hours, and dry it in a vacuum drying oven for 12 hours to remove moisture, to obtain a dried precursor and a loaded ceramic sheet.

[0009] c. Calcine the loaded ceramic sheet to obtain a crystalline manganese-based ion sieve;

[0010] d. The crystalline manganese-based ion sieve is placed in an acidic solution and shaken at a constant temperature for 6-12 hours to obtain a manganese-based ion sieve coupled with porous ceramic forming lithium extraction adsorbent.

[0011] Furthermore, the two sets of manganese-based lithium ion sieve precursor solutions in step a include the LMO group and the LMO-M group;

[0012] The LMO group consists of LiNO3, Mn(CH3COO)2·4H2O and citric acid;

[0013] The LMO-M group is an LMO group doped with metal M.

[0014] Furthermore, in step b, the temperature of the constant-temperature stirring is 60-80℃, and the temperature of the vacuum drying oven is 120℃.

[0015] Furthermore, in step c, a muffle furnace is used for calcination at 400-600℃ for 3-12 hours.

[0016] Furthermore, step c is performed in an air atmosphere.

[0017] Furthermore, the isothermal oscillation temperature in step d is 30°C.

[0018] Furthermore, the acidic solution in step d is a 0.5-1.0 mol / L aqueous HCl solution.

[0019] Furthermore, the adsorbent can adsorb lithium ions from lithium chloride.

[0020] Furthermore, the concentration of the lithium chloride is 250 mg / L to 5 g / L.

[0021] Furthermore, the pH of the solution in which the adsorbent adsorbs lithium ions from lithium chloride is 4-10.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] (1) Improve adsorption capacity, enhance structural stability, and increase cycle life;

[0024] (2) The sol-gel method is used to optimize the uniformity of loading and improve the utilization rate of specific surface area;

[0025] (3) Improve mass transfer efficiency, regulate the bonding performance between porous ceramics and manganese-based ion sieves, and shorten the Li + Diffusion pathway. Attached Figure Description

[0026] Figure 1 This is a technical roadmap for the present invention.

[0027] Figure 2 The XRD spectra of LMO, LMO-Al, HMO and HMO-Al of this invention are shown.

[0028] Figure 3 This is a schematic diagram of the cubic crystal structure of spinel-type LiMn2O4 of the present invention.

[0029] Figure 4 The image shows the SEM spectra of the purified PCMs of this invention.

[0030] Figure 5 The image shows the SEM spectra of the LMO / PCMs of this invention.

[0031] Figure 6 The values ​​represent the average adsorption capacities of LMO / PCMs and LMO-Al / PCMs of this invention at different pH values. Detailed Implementation

[0032] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example:

[0034] A method for preparing a manganese-based ion sieve coupled with porous ceramic-formed lithium extraction adsorbent:

[0035] a. Preparation of precursor solutions: LMO group: using LiNO3, Mn(CH3COO)2·4H2O and citric acid, with a molar ratio of Li:Mn:citric acid = 1:2:1.5; LMO-M group (M is Al-doped): adding Al(NO3)3·9H2O to the LMO group, with a doping amount of 5% of the molar amount of Mn. Solutions are prepared using deionized water, magnetically stirred until completely dissolved, and the pH adjusted to neutral (approximately 7.0).

[0036] b. Immerse the porous ceramic in the precursor solution and stir in a constant temperature water bath at 70℃ for 8 hours. Then place it in a vacuum drying oven and dry it at 120℃ for 12 hours to remove moisture and obtain the dried precursor.

[0037] c. Place the loaded ceramic sheets together in a muffle furnace and calcine at 500°C for 8 hours in air atmosphere to obtain a crystalline manganese ion sieve.

[0038] d. A crystalline manganese-based ion sieve was immersed in a 0.75 mol / L HCl aqueous solution and shaken in a constant temperature shaking tank at 30℃ for 9 hours to obtain a manganese-based ion sieve coupled with porous ceramic forming lithium extraction adsorbent.

[0039] Structural characterization:

[0040] The stability of the spinel framework was verified by analyzing the crystal structure of the adsorbent using X-ray diffraction (XRD).

[0041] Test samples: LMO (undoped and unwashed), LMO-Al (Al-doped and unwashed), HMO (undoped and washed), HMO-Al (Al-doped and washed). Results are as follows: Figure 2 As shown.

[0042] Result: As Figure 2 As shown, all samples exhibit spinel characteristic peaks at 2θ≈20°, 35°, 40°, 50°, 60°, and 70°, indicating that Al doping did not disrupt the crystal structure (space group Fd-3m). After acid washing (HMO and HMO-Al), the main peak intensity decreased (e.g., the 35° peak weakened), indicating that Li... + Deintercalation leads to lattice shrinkage or increased defects, but the integrity of the framework is maintained.

[0043] The crystal structure of spinel-type LiMn2O4, in which Li + Occupying a tetrahedral position (8a), Mn 3+ / Mn 4+ Occupying an octahedral position (16d), O 2- This forms a skeletal framework, creating three-dimensional diffusion channels (Li + (Migration along the path 8a→16c→8a). The results are as follows: Figure 3 As shown.

[0044] Morphological characteristics:

[0045] Scanning electron microscopy (SEM) was used to observe the morphology of the porous ceramic support and adsorbent, and to evaluate the loading uniformity and pore structure.

[0046] Porous ceramic supports (PCMs): Purified PCMs exhibit a uniform fibrous / tubular pore structure with interconnected pore sizes and a high specific surface area (measured ≥220 μm).2 / g), imparting excellent mechanical strength and thermal stability, and optimizing the uniformity of precursor loading. Results are as follows: Figure 4 As shown.

[0047] Adsorbent HMO-Al / PCMs: After acid washing, the samples (HMO-Al / PCMs) exhibited a fibrous network structure, with interwoven fibers forming a three-dimensional framework. The surface was rough and the pores were uniformly distributed (porosity ≥70%). Results are as follows... Figure 5 As shown.

[0048] Adsorption performance test:

[0049] Test conditions: LiCl solution concentration gradients of 250 mg / L, 1 g / L, and 5 g / L; pH gradients of 4, 7, and 10; constant temperature of 30℃; shaking time of 12 h. Results are as follows: Figure 6 As shown.

[0050] Result: As Figure 6 As shown, HMO-Al / PCMs exhibited the highest adsorption capacity at pH 7 (average ≥25 mg / g) and remained stable within the pH range of 4-10 (capacity decay ≤10%). At high LiCl concentrations (5 g / L), the capacity increased by 30%, indicating that the optimized adsorbent is suitable for high magnesium-to-lithium ratio brine lakes. The Al-doped sample showed a 15% higher capacity than the undoped sample, confirming that doping improved cycle stability.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a manganese-based ion sieve coupled with porous ceramic-formed lithium extraction adsorbent, characterized in that, Includes the following steps: a. Prepare two sets of manganese-based lithium ion sieve precursor solutions; b. Stir the precursor solution with porous ceramic at a constant temperature for 4-12 hours, and dry it in a vacuum drying oven for 12 hours to remove moisture, to obtain a dried precursor and a loaded ceramic sheet. c. Calcine the loaded ceramic sheet to obtain a crystalline manganese-based ion sieve; d. The crystalline manganese-based ion sieve is placed in an acidic solution and shaken at a constant temperature for 6-12 hours to obtain a manganese-based ion sieve coupled with porous ceramic forming lithium extraction adsorbent.

2. The preparation method of a manganese-based ion sieve coupled porous ceramic-formed lithium extraction adsorbent according to claim 1, characterized in that, The two sets of manganese-based lithium ion sieve precursor solutions in step a include the LMO group and the LMO-M group. The LMO group consists of LiNO3, Mn(CH3COO)2·4H2O and citric acid; The LMO-M group is an LMO group doped with metal M.

3. The preparation method of a manganese-based ion sieve coupled porous ceramic-formed lithium extraction adsorbent according to claim 1, characterized in that, In step b, the temperature for constant temperature stirring is 60-80℃, and the temperature of the vacuum drying oven is 120℃.

4. The preparation method of a manganese-based ion sieve coupled porous ceramic-formed lithium extraction adsorbent according to claim 1, characterized in that, In step c, calcination is carried out in a muffle furnace at 400-600℃ for 3-12 hours.

5. The preparation method of a manganese-based ion sieve coupled porous ceramic-formed lithium extraction adsorbent according to claim 1, characterized in that, Step c is performed in an air atmosphere.

6. The preparation method of a manganese-based ion sieve coupled porous ceramic-formed lithium extraction adsorbent according to claim 1, characterized in that, The isothermal oscillation temperature in step d is 30℃.

7. The preparation method of a manganese-based ion sieve coupled porous ceramic-formed lithium extraction adsorbent according to claim 1, characterized in that, The acidic solution in step d is a 0.5-1.0 mol / L HCl aqueous solution.

8. The preparation method of a manganese-based ion sieve coupled porous ceramic-formed lithium extraction adsorbent according to claim 1, characterized in that, The adsorbent can adsorb lithium ions from lithium chloride.

9. The preparation method of a manganese-based ion sieve coupled porous ceramic-formed lithium extraction adsorbent according to claim 8, characterized in that, The concentration of lithium chloride is 250 mg / L to 5 g / L.

10. The preparation method of a manganese-based ion sieve coupled porous ceramic-formed lithium extraction adsorbent according to claim 8, characterized in that, The pH of the solution in which the adsorbent adsorbs lithium ions from lithium chloride is 4-10.

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