Modified lithium-extraction adsorbent, and preparation method and use thereof
By employing a combination structure of multi-level porous zeolite and dendritic fiber silica in the lithium-ion adsorbent, the problems of lithium-ion selectivity and recovery purity are solved, achieving efficient and low-cost lithium-ion recovery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUANGDONG BRUNP RECYCLING TECH CO LTD
- Filing Date
- 2024-02-21
- Publication Date
- 2026-07-10
AI Technical Summary
Existing lithium-ion adsorbents have poor selectivity for lithium, resulting in low purity of recovered lithium ions and poor control over energy consumption and costs.
A modified lithium-extraction adsorbent with a multi-level porous zeolite adsorbent as the core and a dendritic fiber silica shell is used to improve the selectivity and adsorption efficiency of lithium ions through the synergistic effect of mesoporous and microporous structures, and to enhance hydrophilicity through surface carboxylation modification.
It improves the selectivity and recovery purity of lithium ions, reduces energy consumption and cost, and enhances lithium extraction performance.
Smart Images
Figure CN117839623B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion resource extraction technology, and relates to a modified lithium extraction adsorbent, its preparation method and uses. Background Technology
[0002] Currently, with the rapid and large-scale development of the lithium-ion energy storage field, the demand for lithium resources is increasing. Lithium extraction technology refers to the methods of extracting lithium from various lithium-containing raw materials. Liquid lithium ore resources are a new type of lithium-containing raw material, especially high-lithium salt lake brines or seawater. Salt lake brine-type lithium ore resources are abundant, which helps to avoid the impact of the depletion of traditional ore-based raw material resources.
[0003] To separate and extract lithium ions from liquid lithium ore, researchers have developed various lithium extraction methods, such as precipitation, extraction, ion exchange adsorption, electrodialysis, and evaporation crystallization. Among these, adsorption is a relatively ideal lithium extraction technology, characterized by its simple operation, low energy consumption, and environmental friendliness, making it more suitable for large-scale separation and enrichment of lithium ions in liquids.
[0004] Adsorption methods utilize selective adsorbents to adsorb lithium ions. Based on an ion exchange mechanism, after the target lithium ions are extracted (delithiated state), they can be reintroduced and react to form a composite material (lithiated state). Therefore, a key to successful adsorption methods lies in the selection and use of high-performance lithium-ion adsorbents.
[0005] Currently, lithium-ion adsorbents mainly include ion sieve adsorbents, aluminum salt adsorbents, and mineral adsorbents such as zeolites. Ion sieve adsorbents are characterized by high selectivity and large adsorption capacity, but they suffer from severe solubility loss and poor long-term performance. Aluminum salt adsorbents are environmentally friendly and safe with a wide range of applications, but their adsorption capacity is relatively small. Zeolite adsorbents, on the other hand, have a high cation exchange capacity and a large specific surface area, offering advantages in energy consumption and cost control during production and application. Furthermore, due to the abundant open framework structure and numerous pores within zeolite adsorbents, their high cation exchange capacity and specific surface area result in lower energy consumption and less waste generation during production and adsorption applications, contributing to environmental protection and cost control. However, compared to other types of adsorbents, zeolite adsorbents have poor selectivity for lithium adsorption, thus requiring modification treatment. Summary of the Invention
[0006] In view of the problems existing in the prior art, the purpose of this invention is to provide a modified lithium extraction adsorbent, its preparation method and uses. The modified lithium extraction adsorbent includes a core and a shell. The core includes a delithiated multi-level porous zeolite adsorbent, and the shell includes dendritic fiber silica. The multi-level porous zeolite adsorbent forms a three-dimensional network cross-linked porous structure with a high specific surface area. The mesoporous structure allows lithium ions to reach the adsorption active sites more quickly during adsorption, while the microporous structure improves the selectivity for lithium ions. The surface is coated with nanoporous dendritic fiber silica with a large specific surface area. Its synergistic effect with the microporous-mesoporous zeolite further improves the selectivity of the zeolite adsorbent for lithium ions, thereby improving the purity of recovered lithium.
[0007] To achieve this objective, the present invention adopts the following technical solution:
[0008] In a first aspect, the present invention provides a modified lithium extraction adsorbent comprising a core and a shell, wherein the core comprises a delithiated multi-level porous zeolite adsorbent, and the shell comprises dendritic fibrous silica.
[0009] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following technical solutions.
[0010] As a preferred technical solution of the present invention, the multi-level pores include mesopores and micropores;
[0011] Preferably, the pore size of the mesopore is 10-40 nm, such as 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm or 40 nm, etc., and the pore size of the micropore is ≤2 nm, such as 0.1 nm, 0.5 nm, 1 nm, 1.5 nm or 2 nm, etc., but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0012] Preferably, the pore volume of the mesopore is 0.18–0.25 cm³. 3 / g, for example 0.18cm 3 / g, 0.2cm 3 / g, 0.22cm 3 / g or 0.25cm 3 / g, etc., wherein the pore volume of the micropores is 0.25–0.32 cm³. 3 / g, 0.25cm 3 / g, 0.28cm 3 / g, 0.3cm 3 / g or 0.32cm 3 / g, etc., but not limited to the listed values; other unlisted values within the above range also apply.
[0013] Preferably, the average particle size of the kernel is 500 to 1000 nm, such as 500 nm, 600 nm, 700 nm, 800 nm, 900 nm or 1000 nm, but is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0014] Preferably, the thickness of the outer shell is 50 to 200 nm, such as 50 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm or 200 nm, but is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0015] Preferably, the outer surface of the dendritic fiber silica away from the core has carboxyl groups.
[0016] Preferably, the dendritic fiber silica has a three-dimensional porous structure with a central radial direction and a pore size of 1 to 5 nm, such as 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm or 5 nm, but is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0017] In a second aspect, the present invention provides a method for preparing the modified lithium extraction adsorbent described in the first aspect, the method comprising:
[0018] An aluminum source, a first silicon source, a lithium salt, and a mesoporous directing agent are mixed, and then a gelation reaction, a crystallization reaction, a first calcination, and delithiation are carried out in sequence to obtain a delithiated multi-level porous zeolite adsorbent.
[0019] The delithiated multi-level porous zeolite adsorbent is mixed with a template agent, a catalyst, a second silicon source, and a structural aid in a microemulsion, and then subjected to a hydrolysis-condensation reaction and a second calcination to form dendritic fiber silica, thereby obtaining a modified lithium extraction adsorbent.
[0020] The preparation method of this invention introduces a certain amount of mesoporous structure into zeolite by using a mesoporous guiding agent, increasing pore volume and making the internal channels orderly interconnected. During adsorption, this allows lithium ions to more easily enter the interior of the zeolite crystal and quickly reach the active center, improving diffusion mass transfer efficiency, adsorption capacity, and adsorption efficiency. Simultaneously, by using lithium salt as a microporous template agent, lithium ions are embedded within it. After subsequent delithiation, the removed lithium ions can form specific microporous structures, making them selective for lithium ions. Furthermore, under the combined action of the template agent and structural aids, and the catalytic action of the catalyst, the second silicon source undergoes hydrolysis and condensation on the surface of the microemulsion, forming dendritic fiber silica that coats the hierarchical porous zeolite adsorbent. The structural aid can adjust the pore structure and pore size of the dendritic fiber silica. The synergistic effect of the channels formed by the dendritic fiber silica with the mesopores and micropores of the core further improves the selectivity for lithium ions, thereby increasing the purity of recovered lithium.
[0021] As a preferred embodiment of the present invention, the aluminum source includes sodium aluminate; the first silicon source includes sodium silicate.
[0022] Preferably, the lithium salt includes a water-soluble lithium salt, such as lithium nitrate and / or lithium chloride.
[0023] Preferably, the mesoporous guiding agent comprises at least one of (3-epoxyethylmethoxypropyl)trimethoxysilane (GPTMS), diphenyldimethoxysilane (DMDPS), or 3-aminopropyltriethoxysilane (APTES).
[0024] Preferably, the amount of aluminum source and first silicon source fed is controlled according to the molar ratio of Al to Si of 1:(0.1 to 0.25), such as 1:0.1, 1:0.12, 1:0.14, 1:0.16, 1:0.18, 1:0.2, 1:0.22, 1:0.24 or 1:0.25, etc., but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0025] Preferably, the amount of aluminum source and lithium salt fed is controlled according to the molar ratio of Al to Li of 1:(0.15~0.5), such as 1:0.15, 1:0.18, 1:0.2, 1:0.23, 1:0.25, 1:0.28, 1:0.3, 1:0.33, 1:0.35, 1:0.38, 1:0.4, 1:0.43, 1:0.45, 1:0.48 or 1:0.5, etc., but is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0026] Preferably, the amount of aluminum source and mesoporous directing agent fed is controlled according to a molar ratio of Al to mesoporous directing agent of 1:(0.05~0.1), such as 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09 or 1:0.1, but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0027] As a preferred embodiment of the present invention, the pH range of the gelation reaction is 11 to 12, such as 11, 11.2, 11.4, 11.6, 11.8 or 12, the temperature is 45 to 60°C, such as 45°C, 50°C, 55°C or 60°C, and the time is 1 to 3 hours, such as 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours, but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0028] Preferably, the gelation reaction is carried out under stirring.
[0029] Preferably, the temperature of the crystallization reaction is 140–160°C, such as 140°C, 145°C, 150°C, 155°C, or 160°C, and the time is 24–48 hours, such as 24 hours, 28 hours, 32 hours, 36 hours, 40 hours, 44 hours, or 48 hours, but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0030] Preferably, the crystallization reaction is carried out in a hydrothermal reactor.
[0031] Preferably, after the crystallization reaction, the product is washed and filtered before the first calcination is performed.
[0032] Preferably, the temperature of the first calcination is 500-600℃, such as 500℃, 520℃, 540℃, 560℃, 580℃ or 600℃, and the time is 4-6h, such as 4h, 4.5h, 5h, 5.5h or 6h, but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0033] Preferably, the first calcination is carried out in an air atmosphere.
[0034] Preferably, the delithiation method includes acid treatment.
[0035] Preferably, the acid solution used in the acid treatment includes hydrochloric acid and / or oxalic acid.
[0036] Preferably, the concentration of the acid solution used for acid treatment is 0.1 to 1 mol / L, such as 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.8 mol / L, or 1 mol / L, and the acid treatment time is 1 to 2 hours, such as 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, or 2 hours, but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0037] As a preferred technical solution of the present invention, the preparation method includes preparing a delithiated multi-level porous zeolite adsorbent, template agent and catalyst into an aqueous suspension, then adding a second silicon source, structural aid and oil phase solvent to mix, forming the microemulsion and carrying out the hydrolysis condensation reaction.
[0038] Preferably, the feed amount is controlled according to the mass ratio of the delithiated multi-level porous zeolite adsorbent in the microemulsion to water of 1:(50-60), such as 1:50, 1:51, 1:52, 1:53, 1:54, 1:55, 1:56, 1:57, 1:58, 1:59 or 1:60, but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0039] Preferably, the feed amount is controlled according to the mass ratio of the delithiated hierarchical porous zeolite adsorbent to the oil phase solvent in the microemulsion as 1:(40-50), for example, 1:40, 1:41, 1:42, 1:43, 1:44, 1:45, 1:46, 1:47, 1:48, 1:49 or 1:50, but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0040] As a preferred embodiment of the present invention, the template agent comprises hexadecyltrimethylammonium bromide (CTAB).
[0041] Preferably, the catalyst comprises triethanolamine.
[0042] Preferably, the second silicon source comprises tetraethyl orthosilicate.
[0043] Preferably, the structural additive includes propionaldehyde.
[0044] Preferably, the feeding amount is controlled according to the mass ratio of the delithiated multi-level porous zeolite adsorbent and the template agent as 1:(1.5~2); 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2, etc., but not limited to the listed values. Other unlisted values within the above range are also applicable.
[0045] Preferably, the feed amount is controlled according to the mass ratio of the delithiated hierarchical porous zeolite adsorbent to the catalyst of 1:(1.1 to 1.3), such as 1:1.1, 1:1.15, 1:1.2, 1:1.25 or 1:1.3, but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0046] Preferably, the feeding amount is controlled according to the mass ratio of the delithiated multi-level porous zeolite adsorbent to the second silicon source of 1:(4-5), such as 1:4, 1:4.2, 1:4.4, 1:4.6, 1:4.8 or 1:5, but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0047] Preferably, the feeding amount is controlled according to the mass ratio of the delithiated multi-level porous zeolite adsorbent and the structural aid is 1:(0.5~1), for example, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9 or 1:1, etc., but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0048] Preferably, the temperature of the hydrolysis-condensation reaction is 65-85°C, such as 65°C, 70°C, 75°C, 80°C or 85°C, and the time is 12-24h, such as 12h, 14h, 16h, 18h, 20h, 22h or 24h, but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0049] Preferably, the second calcination temperature is 500-600℃, such as 500℃, 520℃, 540℃, 560℃, 580℃ or 600℃, and the time is 1-3h, such as 1h, 1.5h, 2h, 2.5h or 3h, but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0050] The second calcination in the preparation method of the present invention can remove the template agent.
[0051] As a preferred embodiment of the present invention, the preparation method further includes carboxylating the obtained modified lithium-extraction adsorbent.
[0052] Preferably, the carboxylation treatment method includes mixing and reacting the modified lithium-extracting adsorbent with succinic anhydride and N,N-dimethylformamide in an aqueous solution.
[0053] Preferably, the amount of modified lithium-extracting adsorbent and water in the aqueous solution is controlled according to a solid-liquid ratio of 1 mg:(3-5) mL, such as 1 mg:3 mL, 1 mg:3.5 mL, 1 mg:4 mL, 1 mg:4.5 mL or 1 mg:5 mL, but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0054] Preferably, the feed amounts of the modified lithium-extracting adsorbent, succinic anhydride, and N,N-dimethylformamide are controlled according to a mass ratio of 1:(0.05~0.1):(15~20), such as 1:0.05:15, 1:0.08:15, 1:0.1:15, 1:0.05:17, 1:0.08:17, 1:0.1:17, 1:0.05:20, 1:0.08:20, or 1:0.1:20, but are not limited to the listed values. Other unlisted values within the above range are also applicable.
[0055] Preferably, the mixing reaction time is 3 to 4 hours, such as 3 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, or 4 hours, but it is not limited to the listed values. Other unlisted values within the above range are also applicable.
[0056] As a preferred technical solution of the present invention, the preparation method includes:
[0057] A solution containing an aluminum source and a solution containing a first silicon source were mixed, and a soluble lithium salt was added to obtain a mixed solution A. During stirring, a mesoporous directing agent was added to mixed solution A, with the addition amount controlled according to the molar ratio of Al, Si, Li, and the mesoporous directing agent being 1:(0.1–0.25):(0.15–0.5):(0.05–0.1). Then, sodium hydroxide solution was added to control the pH of the system to 11–12. The mixture was stirred at 45–60°C to carry out a gelation reaction for 1–3 hours, followed by standing and aging. A lithium-containing silica-alumina gel was obtained; the lithium-containing silica-alumina gel was placed in a hydrothermal reactor and crystallized at 140–160 °C for 24–48 h; the product was washed, filtered, and then calcined in air at 500–600 °C for 4–6 h to obtain a lithium-containing zeolite adsorbent; the obtained lithium-containing zeolite adsorbent was placed in a 0.1–1 mol / L hydrochloric acid and / or oxalic acid solution and stirred for 1–2 h for acid treatment; after delithiation, the delithiated multi-level porous zeolite adsorbent was obtained by filtration.
[0058] A delithiated hierarchical porous zeolite adsorbent was dispersed in deionized water, and a template agent and catalyst were added. The feed amount was controlled according to the mass ratio of the delithiated hierarchical porous zeolite adsorbent, template agent, catalyst and deionized water as 1:(1.5~2):(1.1~1.3):(50~60). The mixture was stirred to obtain an aqueous suspension. Then, a second silicon source, structural aid and oil phase solvent were added to the above aqueous suspension under stirring conditions. The feed amount was controlled according to the mass ratio of the delithiated hierarchical porous zeolite adsorbent, second silicon source, structural aid and oil phase solvent as 1:(4~5):(0.5~1):(40~50). The mixture was stirred to form a microemulsion and carried out a hydrolysis condensation reaction at 65~85℃ for 12~24h. The product was washed and then calcined at 500~600℃ for 1~3h to form dendritic fiber silica and coat the delithiated hierarchical porous zeolite adsorbent to obtain a modified lithium extraction adsorbent.
[0059] The modified lithium-extracting adsorbent was dispersed in deionized water, and then a mixture of succinic anhydride and N,N-dimethylformamide was added. The amount of modified lithium-extracting adsorbent and deionized water was controlled at a solid-liquid ratio of 1 mg:(3-5) mL. The amount of modified lithium-extracting adsorbent, succinic anhydride and N,N-dimethylformamide was controlled at a mass ratio of 1:(0.05-0.1):(15-20). The mixture was then stirred and reacted for 3-4 hours. Finally, the product was filtered and washed to complete the carboxylation treatment.
[0060] Thirdly, the present invention provides an application of the modified lithium extraction adsorbent described in the first aspect, the application including lithium extraction from salt lakes.
[0061] Compared with existing technical solutions, the present invention has at least the following beneficial effects:
[0062] The modified lithium extraction adsorbent of this invention forms a three-dimensional network cross-linked porous structure within the hierarchical porous zeolite adsorbent, giving it a high specific surface area. The mesoporous structure allows lithium ions to reach the adsorption active sites more quickly during adsorption, while the microporous structure improves the selectivity for lithium ions. Simultaneously, by coating the surface with nanoporous dendritic fiber silica with a large specific surface area, its synergistic effect with the microporous-mesoporous zeolite further enhances the selectivity of the zeolite adsorbent for lithium ions, thereby improving the purity of recovered lithium.
[0063] This invention improves the hydrophilicity of modified lithium extraction adsorbents by adding carboxyl-modified groups to the surface of dendritic fiber silica, thereby increasing permeability and improving the lithium extraction performance of the modified lithium extraction adsorbents. Attached Figure Description
[0064] Figure 1 This is a TEM image of the modified lithium extraction adsorbent prepared in Example 1;
[0065] Figure 2 The image shows the XRD pattern of the modified lithium-extraction adsorbent prepared in Example 1. Detailed Implementation
[0066] The technical solution of the present invention will be further illustrated below through specific embodiments.
[0067] Those skilled in the art will understand that the embodiments described are merely illustrative of the invention and should not be construed as limiting the invention.
[0068] Example 1
[0069] This embodiment provides a modified lithium extraction adsorbent, the preparation method of which includes:
[0070] (1) Preparation of multi-level porous zeolite adsorbent
[0071] Aluminum source sodium aluminate solution and first silicon source sodium silicate solution were mixed at an Al / Si molar ratio of 1:0.18, and lithium salt lithium nitrate was added to obtain mixed solution A. During stirring, mesoporous directing agent (3-epoxyethylmethoxypropyl)trimethoxysilane (GPTMS) was added to solution A, and the molar ratio of aluminum source, lithium salt and mesoporous directing agent was controlled at 1:0.3:0.075. Sodium hydroxide solution was added to control the pH of the system to 11.5. The mixture was stirred at 55℃ for 2 h to carry out the gelation reaction, and then allowed to stand for 48 h to obtain lithium-containing silica-alumina gel.
[0072] The obtained lithium-containing silica-alumina gel was placed in a hydrothermal reactor and crystallized at 150°C for 36 hours. The product was washed with deionized water, filtered, and then calcined at 550°C for 5 hours in air to obtain a lithium-containing zeolite adsorbent.
[0073] The obtained lithium-containing zeolite adsorbent was placed in a 0.5 mol / L hydrochloric acid solution and stirred for 1.5 h for acid treatment. After delithiation, the delithiated hierarchical porous zeolite adsorbent was obtained by filtration, with an average particle size of 800 nm, a mesopore size of 22.2 nm, a micropore size of 1.4 nm, and a mesopore volume of 0.20 cm³. 3 / g, micropore volume is 0.29cm³ 3 / g.
[0074] (2) Preparation of dendritic fiber silica-coated hierarchical porous zeolite adsorbent
[0075] A delithiated hierarchical porous zeolite adsorbent was dispersed in deionized water. A template agent, hexadecyltrimethylammonium bromide, and a catalyst, triethanolamine, were added. The feed ratio of the delithiated hierarchical porous zeolite adsorbent, template agent, catalyst, and deionized water was controlled at 1:1.75:1.2:55. The mixture was thoroughly mixed to obtain a suspension. Subsequently, under stirring conditions, a structural aid, propionaldehyde, an oil phase solvent, cyclohexane, and a second silicon source, tetraethyl orthosilicate, were added to the suspension. The delithiated hierarchical porous zeolite adsorbent was then further mixed with the delithiated hierarchical porous zeolite adsorbent. The mass ratio of the second silicon source, structural additive, and oil phase solvent was controlled at 1:4.5:0.7:45. The mixture was stirred at 75°C for 18 hours to form a microemulsion. After the reaction was completed, the product was washed with deionized water and then calcined at 550°C for 2 hours to form dendritic fiber silica, which was then coated with a multi-level porous zeolite adsorbent to obtain a modified lithium extraction adsorbent. The dendritic fiber silica coating layer had a thickness of 125 nm and a pore size of 2.5 nm.
[0076] (3) Carboxylation treatment of the dendritic fiber silica surface of the modified lithium extraction adsorbent.
[0077] The modified lithium-extraction adsorbent was dispersed in deionized water at a solid-liquid ratio of 1g:4mL. Then, succinic anhydride and N,N-dimethylformamide were added, and the amounts of the modified lithium-extraction adsorbent, succinic anhydride, and N,N-dimethylformamide were controlled at a mass ratio of 1:0.07:17. The mixture was then stirred and reacted for 3.5h. Finally, the product was filtered and washed with deionized water to complete the carboxylation treatment.
[0078] Example 2
[0079] This embodiment provides a modified lithium extraction adsorbent, the preparation method of which includes:
[0080] (1) Preparation of multi-level porous zeolite adsorbent
[0081] Aluminum source sodium aluminate solution and first silicon source sodium silicate solution were mixed at an Al / Si molar ratio of 1:0.1, and lithium salt lithium nitrate was added to obtain mixed solution A. During stirring, mesoporous directing agent (3-epoxyethylmethoxypropyl)trimethoxysilane (GPTMS) was added to solution A, and the molar ratio of aluminum source, lithium salt and mesoporous directing agent was controlled at 1:0.15:0.05. Sodium hydroxide solution was added to control the pH of the system to 11.5. The mixture was stirred at 45℃ for 3 h to carry out the gelation reaction, and then allowed to stand and age for 48 h to obtain lithium-containing silica-alumina gel.
[0082] The obtained lithium-containing silica-alumina gel was placed in a hydrothermal reactor and crystallized at 140°C for 48 hours. The product was washed with deionized water, filtered, and then calcined at 500°C in air for 6 hours to obtain a lithium-containing zeolite adsorbent.
[0083] The obtained lithium-containing zeolite adsorbent was placed in a 0.1 mol / L hydrochloric acid solution and stirred for 2 hours for acid treatment. After delithiation, the delithiated hierarchical porous zeolite adsorbent was obtained by filtration, with an average particle size of 500 nm, a mesopore size of 10 nm, a micropore size of 1.8 nm, and a mesopore volume of 0.18 cm³. 3 / g, micropore volume is 0.25cm³ 3 / g.
[0084] (2) Preparation of dendritic fiber silica-coated hierarchical porous zeolite adsorbent
[0085] Delithiated hierarchical porous zeolite adsorbent was dispersed in deionized water, and a template agent, hexadecyltrimethylammonium bromide, and a catalyst, triethanolamine, were added. The feed amount was controlled according to the mass ratio of delithiated hierarchical porous zeolite adsorbent, template agent, catalyst, and deionized water of 1:1.5:1.1:50. After mixing evenly, a suspension was obtained. Subsequently, under stirring conditions, a structural aid, propionaldehyde, an oil phase solvent, cyclohexane, and a second silicon source, tetraethyl orthosilicate, were added to the above suspension. The mass ratio of adjuvant, second silicon source, structural additive and oil phase solvent is 1:4:0.5:40. The feed amount is controlled and mixed into a microemulsion. The mixture is stirred at 65°C for 24 hours for hydrolysis and polycondensation reaction. After the reaction is completed, the product is washed with deionized water and then calcined at 550°C for 2 hours to form dendritic fiber silica and coat it with multi-level porous zeolite adsorbent to obtain modified lithium extraction adsorbent. The dendritic fiber silica coating layer has a thickness of 50 nm and a pore size of 1 nm.
[0086] (3) Carboxylation treatment of the dendritic fiber silica surface of the modified lithium extraction adsorbent.
[0087] The modified lithium-extraction adsorbent was dispersed in deionized water at a solid-liquid ratio of 1g:3mL. Then, succinic anhydride and N,N-dimethylformamide were added, and the amount of the modified lithium-extraction adsorbent, succinic anhydride and N,N-dimethylformamide was controlled at a mass ratio of 1:0.05:15. The mixture was then stirred and reacted for 3 hours. Finally, the product was filtered and washed with deionized water to complete the carboxylation treatment.
[0088] Example 3
[0089] This embodiment provides a modified lithium extraction adsorbent, the preparation method of which includes:
[0090] (1) Preparation of multi-level porous zeolite adsorbent
[0091] Aluminum source sodium aluminate solution and first silicon source sodium silicate solution were mixed at an Al / Si molar ratio of 1:0.1, and lithium salt lithium nitrate was added to obtain mixed solution A. During stirring, mesoporous directing agent (3-epoxyethylmethoxypropyl)trimethoxysilane (GPTMS) was added to solution A, and the molar ratio of aluminum source, lithium salt and mesoporous directing agent was controlled at 1:0.5:0.1. Sodium hydroxide solution was added to control the pH of the system to 12. The mixture was stirred at 60℃ for 1 h to carry out the gelation reaction, and then allowed to stand and age for 48 h to obtain lithium-containing silica-alumina gel.
[0092] The obtained lithium-containing silica-alumina gel was placed in a hydrothermal reactor and crystallized at 160°C for 24 hours. The product was washed with deionized water, filtered, and then calcined at 600°C for 4 hours in air to obtain a lithium-containing zeolite adsorbent.
[0093] The obtained lithium-containing zeolite adsorbent was placed in a 1 mol / L hydrochloric acid solution and stirred for 1 hour for acid treatment. After delithiation, the delithiated multi-level porous zeolite adsorbent was obtained by filtration, with an average particle size of 1000 nm, a mesopore size of 40 nm, a micropore size of 1.0 nm, and a mesopore volume of 0.25 cm³. 3 / g, micropore volume is 0.32cm³ 3 / g.
[0094] (2) Preparation of dendritic fiber silica-coated hierarchical porous zeolite adsorbent
[0095] A delithiated hierarchical porous zeolite adsorbent was dispersed in deionized water, and a template agent, hexadecyltrimethylammonium bromide, and a catalyst, triethanolamine, were added. The feed amount was controlled according to the mass ratio of the delithiated hierarchical porous zeolite adsorbent, template agent, catalyst, and deionized water of 1:2:1.3:60. The mixture was stirred to obtain a suspension. Then, under stirring conditions, a structural aid, propionaldehyde, an oil phase solvent, cyclohexane, and a second silicon source, tetraethyl orthosilicate, were added to the above suspension. The feed amount was controlled according to the mass ratio of the delithiated hierarchical porous zeolite adsorbent, the second silicon source, the structural aid, and the oil phase solvent of 1:5:1:50. The mixture was stirred to form a microemulsion and carried out a hydrolysis-condensation reaction at 85°C for 12 hours. After the reaction was completed, the product was washed with deionized water and then calcined at 550°C for 2 hours to form dendritic fiber silica, which coated the hierarchical porous zeolite adsorbent, thus obtaining a modified lithium extraction adsorbent. The thickness of the dendritic fiber silica coating layer was 200 nm, and the pore size was 5 nm.
[0096] (3) Carboxylation treatment of the dendritic fiber silica surface of the modified lithium extraction adsorbent.
[0097] The modified lithium-extraction adsorbent was dispersed in deionized water at a solid-liquid ratio of 1g:5mL. Then, succinic anhydride and N,N-dimethylformamide were added, and the amount of the modified lithium-extraction adsorbent, succinic anhydride and N,N-dimethylformamide was controlled at a mass ratio of 1:0.1:20. The mixture was then stirred and reacted for 4 hours. Finally, the product was filtered and washed with deionized water to complete the carboxylation treatment.
[0098] Example 4
[0099] This embodiment provides a modified lithium-extraction adsorbent. In step (2), the amount of propionaldehyde used as a structural aid is adjusted so that the mass ratio of the delithiated multi-level porous zeolite adsorbent to the structural aid is changed from 1:0.7 to 1:0.1. Apart from this, the other conditions are exactly the same as in Example 1.
[0100] Example 5
[0101] This embodiment provides a modified lithium-extraction adsorbent. In step (2), the amount of propionaldehyde used as a structural aid is adjusted so that the mass ratio of the delithiated multi-level porous zeolite adsorbent to the structural aid is changed from 1:0.7 to 1:1.5. Apart from this, the other conditions are exactly the same as in Example 1.
[0102] Example 6
[0103] This embodiment provides a modified lithium extraction adsorbent, the preparation method of which does not involve carboxylation treatment, that is, only steps (1) and (2) are performed, but step (3) is not performed. Apart from this, the other conditions are exactly the same as those in Example 1.
[0104] Comparative Example 1
[0105] This comparative example provides a modified lithium extraction adsorbent, the preparation method of which does not involve the preparation of dendritic fiber silica, that is, only step (1) is performed, and steps (2) and (3) are not performed. Apart from this, the other conditions are exactly the same as those in Example 1.
[0106] Comparative Example 2
[0107] This comparative example provides a modified lithium-extraction adsorbent, the preparation method of which does not use lithium salt lithium nitrate in step (1), and other conditions are exactly the same as in Example 1.
[0108] Comparative Example 3
[0109] This comparative example provides a modified lithium extraction adsorbent, the preparation method of which does not use the mesoporous directing agent (3-epoxyethylmethoxypropyl)trimethoxysilane in step (1), except that the other conditions are exactly the same as in Example 1.
[0110] Testing and Characterization
[0111] I. Figure 1 The image shows a TEM image of the modified lithium-extraction adsorbent prepared in Example 1. As can be seen from the image, the silica coating on the surface of the zeolite adsorbent is distributed in a dendritic pattern.
[0112] Figure 2 The image shows the XRD pattern of the modified lithium extraction adsorbent prepared in Example 1. As can be seen from the image, the lithium extraction adsorbent has high zeolite crystallinity, and peaks of amorphous silica appear in the small-angle region, which are dendritic silica coatings on the zeolite surface.
[0113] II. Lithium extraction tests were conducted on the modified lithium-extraction adsorbents obtained in the examples and comparative examples: The adsorbents were placed in brine with concentrations of sodium ions (23.0 g / L), magnesium ions (28.3 g / L), lithium ions (0.5 g / L), boron ions (3.85 g / L), calcium ions (32 g / L), and carbonate ions (17.8 g / L), respectively. Adsorption experiments were performed at 15°C, with a stirring speed of 300 r / min and an adsorption time of 2 h. After filtration, 0.5 mol / L hydrochloric acid was used for desorption at 300 r / min and a desorption time of 2 h. The Li content in the solutions before and after adsorption in the examples and comparative examples was determined using an atomic absorption spectrophotometer. + The concentration is used to calculate the adsorption capacity using the following formula: Q t =(C0-C t )×V / m, where Q t It is the adsorption of Li + Adsorption capacity; C0 and C t Li at the initial stage of solution and after adsorption, respectively + Concentration, V is the volume of the solution; m is the weight of the adsorbent.
[0114] The test results are recorded in Table 1.
[0115] Table 1
[0116]
[0117] As can be seen from Table 1, compared with the comparative example, the zeolite adsorbent prepared by the embodiment of the present invention has a higher Li content. + The adsorption capacity is above 6.73 mg / g, which is high. The content of impurity ions in the eluent is low, and the selectivity for lithium ions is high.
[0118] As can be seen from the above, the modified lithium extraction adsorbent of this invention forms a three-dimensional network cross-linked porous structure within the hierarchical porous zeolite adsorbent, giving it a high specific surface area. The mesoporous structure allows lithium ions to reach the adsorption active sites more quickly during adsorption, while the microporous structure improves the selectivity for lithium ions. Simultaneously, the surface is coated with nanoporous dendritic fiber silica with a large specific surface area, and its synergistic effect with the microporous-mesoporous zeolite further enhances the selectivity of the zeolite adsorbent for lithium ions, thereby improving the purity of recovered lithium. This invention, by imbuing the surface of the dendritic fiber silica with carboxyl-modified groups, can effectively improve the hydrophilicity of the modified lithium extraction adsorbent, increasing permeability and improving its lithium extraction performance.
[0119] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0120] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.
[0121] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.
Claims
1. A method for preparing a modified lithium extraction adsorbent, characterized in that, The preparation method includes: An aluminum source, a first silicon source, a lithium salt, and a mesoporous directing agent are mixed, and then a gelation reaction, a crystallization reaction, a first calcination, and delithiation are carried out in sequence to obtain a delithiated multi-level porous zeolite adsorbent; the mesoporous directing agent includes at least one of (3-epoxyethylmethoxypropyl)trimethoxysilane, diphenyldimethoxysilane, or 3-aminopropyltriethoxysilane. The delithiated hierarchical porous zeolite adsorbent is mixed with a template agent, a catalyst, a second silicon source, and a structural aid in a microemulsion, and then subjected to a hydrolysis-condensation reaction and a second calcination to form dendritic fiber silica, thereby obtaining a modified lithium-extraction adsorbent; the template agent includes hexadecyltrimethylammonium bromide; the catalyst includes triethanolamine; and the structural aid includes propionaldehyde. The modified lithium extraction adsorbent comprises a core and a shell. The core comprises a delithiated multi-level porous zeolite adsorbent, and the shell comprises dendritic fibrous silica.
2. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The lithium salt includes lithium nitrate and / or lithium chloride.
3. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The amount of aluminum source and the first silicon source fed in is controlled according to the molar ratio of Al to Si of 1:(0.1~0.25).
4. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The amount of aluminum source and lithium salt fed is controlled according to the molar ratio of Al to Li of 1:(0.15~0.5).
5. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The amount of aluminum source and mesoporous directing agent fed in is controlled according to the molar ratio of Al to mesoporous directing agent of 1:(0.05~0.1).
6. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The gelation reaction has a pH range of 11-12, a temperature of 45-60℃, and a time of 1-3 hours.
7. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The crystallization reaction is carried out at a temperature of 140~160℃ for 24~48h.
8. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, After the crystallization reaction, the product is washed and filtered before undergoing the first calcination.
9. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The first calcination temperature is 500~600℃ and the time is 4~6h.
10. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The delithiation method includes acid treatment.
11. The method for preparing the modified lithium extraction adsorbent according to claim 10, characterized in that, The concentration of the acid solution used in the acid treatment is 0.1~1 mol / L, and the acid treatment time is 1~2 h.
12. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The preparation method includes preparing a delithiated multi-level porous zeolite adsorbent, template agent and catalyst into an aqueous suspension, then adding a second silicon source, structural aid and oil phase solvent to mix and form the microemulsion and carry out the hydrolysis condensation reaction.
13. The method for preparing the modified lithium extraction adsorbent according to claim 12, characterized in that, The feed amount is controlled according to the mass ratio of the delithiated multi-level porous zeolite adsorbent and water in the microemulsion being 1:(50~60).
14. The method for preparing the modified lithium extraction adsorbent according to claim 12, characterized in that, The feed amount is controlled according to the mass ratio of the delithiated multi-level porous zeolite adsorbent and the oil phase solvent in the microemulsion being 1:(40~50).
15. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The second silicon source includes tetraethyl orthosilicate.
16. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The feeding amount is controlled according to the mass ratio of the delithiated multi-level porous zeolite adsorbent and the template agent being 1:(1.5~2).
17. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The feed amount is controlled according to the mass ratio of the delithiated multi-level porous zeolite adsorbent to the catalyst being 1:(1.1~1.3).
18. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The feeding amount is controlled according to the mass ratio of the delithiated multi-level porous zeolite adsorbent and the second silicon source being 1:(4~5).
19. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The feeding amount is controlled according to the mass ratio of the delithiated multi-level porous zeolite adsorbent and the structural aid being 1:(0.5~1).
20. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The hydrolysis-condensation reaction is carried out at a temperature of 65-85℃ for 12-24 hours.
21. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The second calcination temperature is 500~600℃, and the time is 1~3h.
22. The method for preparing the modified lithium extraction adsorbent according to claim 1, characterized in that, The preparation method further includes carboxylating the obtained modified lithium-extraction adsorbent.
23. The method for preparing the modified lithium extraction adsorbent according to claim 22, characterized in that, The carboxylation treatment method includes mixing and reacting a modified lithium-extracting adsorbent with succinic anhydride and N,N-dimethylformamide in an aqueous solution.
24. The method for preparing the modified lithium extraction adsorbent according to claim 23, characterized in that, The amount of modified lithium-extracting adsorbent and water in the aqueous solution is controlled according to a solid-liquid ratio of 1 mg:(3~5) mL.
25. The method for preparing the modified lithium extraction adsorbent according to claim 23, characterized in that, The feed amounts of the modified lithium-extracting adsorbent, succinic anhydride, and N,N-dimethylformamide are controlled according to a mass ratio of 1:(0.05~0.1):(15~20).
26. The method for preparing the modified lithium extraction adsorbent according to claim 23, characterized in that, The mixing reaction takes 3-4 hours.
27. A modified lithium extraction adsorbent, characterized in that, The modified lithium-extraction adsorbent obtained by the preparation method according to any one of claims 1-26 comprises a core and a shell, wherein the core comprises a delithiated multi-level porous zeolite adsorbent and the shell comprises dendritic fiber silica.
28. The modified lithium extraction adsorbent according to claim 27, characterized in that, The hierarchical pores include mesopores and micropores; the pore size of the mesopores is 10~40nm, the pore size of the micropores is ≤2nm, and / or, the pore volume of the mesopores is 0.18~0.25cm³. 3 / g, wherein the pore volume of the micropores is 0.25~0.32cm³. 3 / g.
29. The modified lithium extraction adsorbent according to claim 27, characterized in that, The average particle size of the kernel is 500~1000nm.
30. The modified lithium extraction adsorbent according to claim 27, characterized in that, The thickness of the outer shell is 50~200nm.
31. The modified lithium extraction adsorbent according to claim 27, characterized in that, The dendritic fiber silica has carboxyl groups on its outer surface away from the core.
32. The modified lithium extraction adsorbent according to claim 27, characterized in that, The dendritic fiber silica has a three-dimensional porous structure with a central radial direction and a pore size of 1~5nm.
33. The use of the modified lithium extraction adsorbent according to any one of claims 27-32, characterized in that, The applications include lithium extraction from salt lakes.