Core-shell type HMO-UiO-66 composite adsorbent and preparation method thereof

Abstract

The invention discloses a core-shell HMO-coated UiO-66 composite adsorbent and a preparation method thereof, and relates to the technical field of functional adsorption materials. Comprising the following steps: constructing a Zr-based MOF material UiO-66 shell layer on the surface of a manganese lithium ion sieve H1. 6Mn1. 6O4 through an in-situ growth method to form the HMO-coated UiO-66 composite material with a core-shell structure. Through core-shell structure design, the core H1. 6Mn1. 6O4 gives full play to the high adsorption capacity of Li < + >, and meanwhile, the shell UiO-66 provides more lithium ion transmission paths by virtue of the high specific surface area and rich pore structure, so that the adsorption capacity of the material in liquid lithium resources is effectively improved. In addition, a UiO-66 shell layer serves as a physical barrier, erosion of a solution to inner core manganese active sites is slowed down in the acid desorption process, dissolution of manganese is inhibited, the manganese dissolution loss rate is reduced, the structural stability of the material is improved, and the cycle service life of the material is prolonged.

Description

Technical Field

[0001] This invention relates to the field of functional adsorption materials technology, specifically to a core-shell type HMO@UiO-66 composite adsorbent, its preparation method, and its application. Background Technology

[0002] Lithium, as an "energy metal," is a core material in new energy fields such as power lithium batteries and large-scale energy storage systems. Currently, proven lithium resources mainly exist in pegmatite-type hard-rock lithium deposits and brine lithium deposits in closed basins, with brine lithium resources accounting for over 60% of global lithium resources. Furthermore, the ocean contains 230 billion tons of lithium, meaning seawater may also become an effective supplier of lithium resources in the future. Therefore, achieving efficient extraction of liquid lithium resources is an inevitable choice to meet future lithium demand and optimize the lithium supply structure. Manganese-based lithium ion sieves have attracted much attention in adsorption methods due to their large adsorption capacity, but they suffer from manganese loss during adsorption-desorption processes, especially under acidic desorption environments where manganese in the framework is easily reduced and dissolved into the solution. This not only leads to adsorbent structural collapse, continuous decline in adsorption capacity, and shortened service life, but also causes secondary pollution of the lithium extraction solution, significantly increasing operating costs and severely restricting its large-scale industrial application. Therefore, it is essential to develop a novel lithium ion adsorbent that combines high adsorption capacity with low manganese loss characteristics. CN118988265A discloses a LiAl-LDHs@Al-MOFs lithium extraction adsorbent. First, an alkaline solution is reacted with an aluminum and lithium-containing metal salt solution under controlled temperature and pH conditions and then dried to obtain uneluted LiAl-LDH. After elution with deionized water, the eluted LiAl-LDH adsorbent is obtained. It is then mixed with an aluminum source and an organic ligand in a solvent, and an Al-MOFs coating layer is grown in situ on its surface through a hydrothermal reaction. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a core-shell type HMO@UiO-66 composite adsorbent. The adsorbent prepared by this method can suppress manganese dissolution to ensure the stability of the material structure, and simultaneously improve its lithium adsorption capacity, thereby achieving efficient and stable lithium extraction performance.

[0004] To achieve the above objectives, the present invention provides a method for preparing a core-shell type HMO@UiO-66 composite adsorbent, characterized by comprising the following steps:

[0005] S1. Disperse lithium-ion sieve HMO powder in an organic solvent and sonicate for 10 min to obtain HMO dispersion;

[0006] S2. Dissolve the zirconium source and organic ligand in N,N-dimethylformamide solvent containing a regulator, and stir until completely dissolved to obtain a mixed solution;

[0007] S3. Add the HMO dispersion obtained in step S1 to the mixed solution obtained in step S2, and stir continuously to mix it thoroughly to obtain the precursor reaction solution.

[0008] S4. The precursor reaction solution obtained in step S3 is subjected to a solvothermal reaction at 100~140 °C for 12~30 h. After the reaction is completed, the solution is cooled and washed 3~5 times with N,N-dimethylformamide and ethanol in sequence. After drying, the core-shell type HMO@UiO-66 composite adsorbent is obtained.

[0009] Furthermore, the lithium-ion sieve HMO powder in S1 is H 1.6 Mn 1.6 O4, with N,N-dimethylformamide as the organic solvent.

[0010] Furthermore, the H 1.6 Mn 1.6 O4 lithium ion sieve powder is composed of lithium ion sieve precursor Li 1.6 Mn 1.6 O4 is obtained by acid washing; wherein the acid washing solution used is HCl acid washing solution with a concentration of 0.25~1 mol / L and a solid-liquid ratio of 1 g: (0.25~1) L. Preferably, the hydrochloric acid solution has a concentration of 0.5 mol / L and a solid-liquid ratio of 1 g: 0.25 L.

[0011] Furthermore, in S2, the zirconium source is zirconium chloride; the organic ligand is terephthalic acid; and the regulator is acetic acid.

[0012] Furthermore, the molar ratio of zirconium source to organic ligand in S2 is 1:(1~2).

[0013] Furthermore, the lithium ion sieve H in the HMO dispersion 1.6 Mn 1.6 The molar ratio of O4 to zirconium chloride (a zirconium source) and terephthalic acid (an organic ligand) is (1-2):(1-2):(1-2), for example, 1:2:2, 1:1:1, 2:1:1, 1:1:2, 2:1:2.

[0014] Furthermore, in the precursor reaction system of S3, the volume ratio of N,N-dimethylformamide solvent to acetic acid regulator is 7.5:1. For example, the amount of N,N-dimethylformamide solvent used is 60 mL, and the amount of acetic acid used is 8 mL.

[0015] Furthermore, the temperature of the solvothermal reaction in S4 is 120 °C, and the reaction time is 24 h; the drying is vacuum drying at 100 °C for 12 h.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) This invention utilizes a manganese-based lithium ion sieve H 1.6 Mn 1.6 Zr-based metal-organic framework UiO-66 is grown in situ on the O4 surface to construct a core-shell HMO@UiO-66 composite structure, which organically combines lithium-ion sieve and MOF material. It combines the high adsorption characteristics of manganese-based lithium-ion sieve for Li⁺ with the advantages of UiO-66's high specific surface area and rich pore structure, effectively improving the stability of the adsorption material and the adsorption capacity of Li⁺ in liquid lithium resources.

[0018] (2) This invention utilizes UiO-66 as the outer shell to support the kernel H 1.6 Mn 1.6 O4 acts as an effective physical shield and interface buffer. Under harsh conditions such as acidic desorption, it can slow down the direct contact between the solution and the manganese active sites, inhibit the reduction and dissolution of Mn in the framework, reduce the manganese loss rate, and ensure the integrity and stability of the adsorbent structure. This can extend the cycle life of the material and reduce secondary pollution during the lithium extraction process.

[0019] (3) The preparation method provided by the present invention only uses common zirconium salts, organic ligands and organic solvents to construct the core-shell structure in situ under medium and low temperature solvothermal conditions. The process route is clear, with few steps and easy control of conditions, which is conducive to realizing the industrial application of the core-shell HMO@UiO-66 composite adsorbent in the field of extraction of liquid lithium resources such as salt lake brine. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the preparation process of the composite adsorbent of the present invention.

[0021] Figure 2 The images show the SEM microstructure and EDS elemental distribution of the final HMO@UiO-66 composite adsorbent. Detailed Implementation

[0022] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0023] Example 1

[0024] S1. 0.45 mmol of lithium-ion sieve H after acid washing. 1.6 Mn 1.6O4 powder was dispersed in 10 mL of N,N-dimethylformamide solvent and sonicated for 10 min to obtain a uniform HMO dispersion. The acid washing conditions were 0.5 mol / L hydrochloric acid solution with a solid-liquid ratio of 1 g: 0.25 L.

[0025] S2. Dissolve 0.9 mmol zirconium chloride and 0.9 mmol terephthalic acid in 50 mL of N,N-dimethylformamide solvent, add 8 mL of acetic acid as a conditioner, and stir until completely dissolved to obtain a mixed solution.

[0026] S3. Slowly add the HMO dispersion obtained in step S1 to the mixed solution obtained in step S2, and stir continuously for 30 min to ensure thorough mixing, thereby obtaining the precursor reaction solution.

[0027] S4. The precursor reaction solution obtained in step S3 was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene and subjected to a solvothermal reaction at 100 °C for 12 h. After the reaction was completed, the mixture was naturally cooled to room temperature and washed 3-5 times each with N,N-dimethylformamide and ethanol, and finally vacuum dried at 100 °C for 12 h to obtain the core-shell type HMO@UiO-66 composite adsorbent.

[0028] Lithium extraction from simulated salt lake brine: 1 g of HMO@UiO-66 composite adsorbent and pure HMO before composite were weighed and added to 1000 ml of simulated brine with a lithium ion concentration of 150 mg / L and a pH of 12. Adsorption was carried out at room temperature with a stirring speed of 800 r for 24 h. After adsorption was complete, samples were taken and the concentration of remaining lithium ions in the adsorbate was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). To accurately evaluate the adsorption performance of the composite adsorbent HMO@UiO-66, the adsorption capacity of the composite adsorbent was normalized based on the mass ratio of its active component HMO. This is because, under equal mass conditions, the effective content of HMO in the composite adsorbent is necessarily lower than that in the pure HMO sample.

[0029] After completing one adsorption process, the adsorbent was filtered, dried, and collected, and then desorbed for 24 h under 0.5 M hydrochloric acid solution and 0.5 L of acid washing solution. The manganese ion content in the remaining desorbent after this desorption was measured by inductively coupled plasma atomic emission spectrometry (ICP).

[0030] Adsorbent Initial adsorption capacity (mg / g HMO) Manganese dissolution rate (%) HMO@UiO-66 composite adsorbent 28.56 1.07 HMO 25.64 2.24

[0031] Example 2

[0032] S1. 1.8 mmol of acid-washed lithium-ion sieve H 1.6 Mn 1.6O4 powder was dispersed in 10 mL of N,N-dimethylformamide solvent and sonicated for 10 min to obtain a uniform HMO dispersion. The acid washing conditions were 0.5 mol / L hydrochloric acid solution with a solid-liquid ratio of 1 g: 0.25 L.

[0033] S2. Dissolve 0.9 mmol zirconium chloride and 1.8 mmol terephthalic acid in 50 mL of N,N-dimethylformamide solvent, add 8 mL of acetic acid as a regulator, and stir until completely dissolved to obtain a mixed solution.

[0034] S3. Slowly add the HMO dispersion obtained in step S1 to the mixed solution obtained in step S2, and stir continuously for 30 min to ensure thorough mixing, thereby obtaining the precursor reaction solution.

[0035] S4. The precursor reaction solution obtained in step S3 was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene and subjected to a solvothermal reaction at 140 °C for 30 h. After the reaction was completed, the mixture was naturally cooled to room temperature and washed 3-5 times each with N,N-dimethylformamide and ethanol, and finally vacuum dried at 100 °C for 12 h to obtain the core-shell type HMO@UiO-66 composite adsorbent.

[0036] Lithium extraction from simulated salt lake brine: 1g of HMO@UiO-66 composite adsorbent and pure HMO before composite were weighed and added to 1000ml of simulated brine with a lithium ion concentration of 150 mg / L and a pH of 12. Adsorption was carried out at room temperature with a stirring speed of 800 r for 24 h. After adsorption, samples were taken and the concentration of remaining lithium ions in the adsorbate was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). After one adsorption process, desorption was performed in 0.5L of 0.5M hydrochloric acid solution for 24 h. Samples were taken and the manganese ion content in the remaining desorbate was determined by ICP-OES. The initial adsorption capacity of the HMO@UiO-66 composite adsorbent was 28.28 mg / g, and the manganese dissolution rate was 1.65%.

[0037] Example 3

[0038] S1. 0.9 mmol of lithium-ion sieve H after acid washing 1.6 Mn 1.6 O4 powder was dispersed in 10 mL of N,N-dimethylformamide solvent and sonicated for 10 min to obtain a uniform HMO dispersion. The acid washing conditions were 0.5 mol / L hydrochloric acid solution with a solid-liquid ratio of 1 g: 0.25 L.

[0039] S2. Dissolve 0.9 mmol zirconium chloride and 0.9 mmol terephthalic acid in 50 mL of N,N-dimethylformamide solvent, add 8 mL of acetic acid as a conditioner, and stir until completely dissolved to obtain a mixed solution.

[0040] S3. Slowly add the HMO dispersion obtained in step S1 to the mixed solution obtained in step S2, and stir continuously for 30 min to ensure thorough mixing, thereby obtaining the precursor reaction solution.

[0041] S4. The precursor reaction solution obtained in step S3 was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene and subjected to a solvothermal reaction at 120 °C for 24 h. After the reaction was completed, the mixture was naturally cooled to room temperature and washed 3-5 times each with N,N-dimethylformamide and ethanol, and finally vacuum dried at 100 °C for 12 h to obtain the core-shell type HMO@UiO-66 composite adsorbent.

[0042] Lithium extraction from simulated salt lake brine: 1g of HMO@UiO-66 composite adsorbent and pure HMO before composite were weighed and added to 1000ml of simulated brine with a lithium ion concentration of 150 mg / L and a pH of 12. Adsorption was carried out at room temperature with a stirring speed of 800 r for 24 h. After adsorption, samples were taken and the concentration of remaining lithium ions in the adsorbate was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). After one adsorption process, desorption was performed in 0.5L of 0.5M hydrochloric acid solution for 24 h. Samples were taken and the manganese ion content in the remaining desorbate was determined by ICP-OES. The initial adsorption capacity of the HMO@UiO-66 composite adsorbent was 37.24 mg / g, and the manganese dissolution rate was 1.00%.

[0043] Example 4

[0044] S1. 1.8 mmol of acid-washed lithium-ion sieve H 1.6 Mn 1.6 O4 powder was dispersed in 10 mL of N,N-dimethylformamide solvent and sonicated for 10 min to obtain a uniform HMO dispersion. The acid washing conditions were 0.5 mol / L hydrochloric acid solution with a solid-liquid ratio of 1 g: 0.25 L.

[0045] S2. Dissolve 0.9 mmol zirconium chloride and 0.9 mmol terephthalic acid in 50 mL of N,N-dimethylformamide solvent, add 8 mL of acetic acid as a conditioner, and stir until completely dissolved to obtain a mixed solution.

[0046] S3. Slowly add the HMO dispersion obtained in step S1 to the mixed solution obtained in step S2, and stir continuously for 30 min to ensure thorough mixing, thereby obtaining the precursor reaction solution.

[0047] S4. The precursor reaction solution obtained in step S3 was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene and subjected to a solvothermal reaction at 120 °C for 24 h. After the reaction was completed, the mixture was naturally cooled to room temperature and washed 3-5 times each with N,N-dimethylformamide and ethanol, and finally vacuum dried at 100 °C for 12 h to obtain the core-shell type HMO@UiO-66 composite adsorbent.

[0048] Lithium extraction from simulated salt lake brine: 1 g of HMO@UiO-66 composite adsorbent and pure HMO before composite were weighed and added to 1000 ml of simulated brine with a lithium ion concentration of 150 mg / L and a pH of 12. Adsorption was carried out at room temperature with a stirring speed of 800 r for 24 h. After adsorption, samples were taken and the concentration of remaining lithium ions in the adsorbate was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). After one adsorption process, desorption was performed in 0.5 L of 0.5 M hydrochloric acid solution for 24 h. Samples were taken and the manganese ion content in the remaining desorbate was determined by ICP-OES. The initial adsorption capacity of the HMO@UiO-66 composite adsorbent was 35.24 mg / g, and the manganese dissolution rate was 1.47%.

[0049] Example 5

[0050] S1. 0.9 mmol of lithium-ion sieve H after acid washing 1.6 Mn 1.6 O4 powder was dispersed in 10 mL of N,N-dimethylformamide solvent and sonicated for 10 min to obtain a uniform HMO dispersion. The acid washing conditions were 0.5 mol / L hydrochloric acid solution with a solid-liquid ratio of 1 g: 0.25 L.

[0051] S2. Dissolve 0.9 mmol zirconium chloride and 1.8 mmol terephthalic acid in 50 mL of N,N-dimethylformamide solvent, add 8 mL of acetic acid as a regulator, and stir until completely dissolved to obtain a mixed solution.

[0052] S3. Slowly add the HMO dispersion obtained in step S1 to the mixed solution obtained in step S2, and stir continuously for 30 min to ensure thorough mixing, thereby obtaining the precursor reaction solution.

[0053] S4. The precursor reaction solution obtained in step S3 was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene and subjected to a solvothermal reaction at 120 °C for 24 h. After the reaction was completed, the mixture was naturally cooled to room temperature and washed 3-5 times each with N,N-dimethylformamide and ethanol, and finally vacuum dried at 100 °C for 12 h to obtain the core-shell type HMO@UiO-66 composite adsorbent.

[0054] Lithium extraction from simulated salt lake brine: 1g of HMO@UiO-66 composite adsorbent and pure HMO before composite were weighed and added to 1000ml of simulated brine with a lithium ion concentration of 150 mg / L and a pH of 12. Adsorption was carried out at room temperature with a stirring speed of 800 r for 24 h. After adsorption, samples were taken and the concentration of remaining lithium ions in the adsorbate was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). After one adsorption process, desorption was performed in 0.5L of 0.5M hydrochloric acid solution for 24 h. Samples were taken and the manganese ion content in the remaining desorbate was determined by ICP-OES. The initial adsorption capacity of the HMO@UiO-66 composite adsorbent was 31.96 mg / g, and the manganese dissolution rate was 1.31%.

Claims

1. A method for preparing a core-shell type HMO@UiO-66 composite adsorbent, characterized in that, Includes the following steps: S1. Disperse lithium-ion sieve HMO powder in an organic solvent and sonicate for 10 min to obtain HMO dispersion; S2. Dissolve the zirconium source and organic ligand in N,N-dimethylformamide solvent containing a regulator, and stir until completely dissolved to obtain a mixed solution; S3. Add the HMO dispersion obtained in step S1 to the mixed solution obtained in step S2, and stir continuously to mix it thoroughly to obtain the precursor reaction solution. S4. The precursor reaction solution obtained in step S3 is subjected to a solvothermal reaction at 100~140 °C for 12~30 h. After the reaction is completed, the solution is cooled and washed 3~5 times with N,N-dimethylformamide and ethanol in sequence. After drying, the core-shell type HMO@UiO-66 composite adsorbent is obtained.

2. The method according to claim 1, characterized in that, The lithium-ion sieve HMO powder in S1 is H 1.6 Mn 1.6 O4, with N,N-dimethylformamide as the organic solvent.

3. The method according to claim 1, characterized in that, The H 1.6 Mn 1.6 O4 lithium ion sieve powder is composed of lithium ion sieve precursor Li 1.6 Mn 1.6 O4 is obtained by acid washing; wherein the acid washing solution used in the acid washing treatment is HCl acid washing solution with a concentration of 0.25~1 mol / L and a solid-liquid ratio of 1 g: (0.25~1) L.

4. The method according to claim 3, characterized in that, The hydrochloric acid solution concentration is 0.5 mol / L, and the solid-liquid ratio is 1 g:0.25 L.

5. The method according to claim 1, characterized in that, The zirconium source in S2 is zirconium chloride; the organic ligand is terephthalic acid; and the regulator is acetic acid.

6. The method according to claim 1, characterized in that, The lithium ion sieve H in the HMO dispersion 1.6 Mn 1.6 The molar ratio of O4 to zirconium chloride (zirconia source) and organic ligand terephthalic acid is (1-2):(1-2):(1-2).

7. The method according to claim 1, characterized in that, In the precursor reaction system of S3, the volume ratio of N,N-dimethylformamide solvent to acetic acid regulator is 7.5:

1. For example, the amount of N,N-dimethylformamide solvent used is 60 mL, and the amount of acetic acid used is 8 mL.

8. The method according to claim 1, characterized in that, The solvothermal reaction in S4 is carried out at a temperature of 120 °C for 24 h; the drying is carried out under vacuum at 100 °C for 12 h.

9. The core-shell HMO@UiO-66 composite adsorbent prepared according to any one of claims 1-8.

10. The application of the core-shell type HMO@UiO-66 composite adsorbent prepared according to any one of claims 1-8, for the extraction of liquid lithium resources from salt lake brine, adsorbing lithium ions under alkaline conditions and desorbing them under acidic conditions.

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