Manganese-titanium-based composite lithium ion sieve, preparation method and application

Abstract

The invention provides a manganese-titanium-based composite lithium ion sieve, a preparation method and application, and the manganese-titanium-based composite lithium ion sieve is formed by depositing and growing a layer of titanium-based lithium ion sieve precursor LTO on the surface of a spherical porous / hollow modified manganese-based lithium ion sieve precursor LMO through a sol-gel method, calcining and pickling. The manganese-titanium-based composite lithium ion sieve HMO-coated HTO can realize complementary advantages of HMO and HTO, has relatively strong hydrophilicity, relatively high specific surface area, relatively strong dispersity, relatively high adsorption capacity, excellent cycling stability and excellent adsorption rate, can be used as a high-selectivity adsorbent, and is used for extracting lithium from lithium-containing solutions such as salt lake brine and seawater and recycling lithium in waste lithium batteries. In addition, the manganese-titanium-based composite lithium ion sieve HMO-coated HTO can perform double screening and targeted adsorption on Li < + > in a lithium-containing solution.

Description

Technical Field

[0001] The present invention belongs to the technical field of ion sieves and relates to a manganese-titanium-based composite lithium ion sieve, a preparation method and an application thereof. Background Art

[0002] Lithium is a metallic element, known as a green energy metal and white oil, and is widely used in energy storage, chemicals, batteries, ceramics, and pharmaceuticals. With the rapid development of industries such as lithium-ion batteries, demand for lithium has skyrocketed, leading to an acceleration in the mining of lithium ore resources. However, dwindling lithium ore reserves and the high energy consumption, high costs, and environmental pollution associated with mining have hindered further development. In contrast, extracting lithium from liquid lithium resources shows tremendous potential.

[0003] Among the many brine lithium extraction technologies, lithium ion sieve adsorption is considered one of the most promising methods due to its low energy consumption and environmental friendliness. Currently, the most studied lithium ion sieves are manganese-based lithium ion sieves HMO and titanium-based lithium ion sieves HTO. HMO has the characteristics of low synthetic raw material cost, high theoretical adsorption capacity, and good selectivity, but its actual adsorption capacity is often lower than the theoretical value, and during the adsorption / desorption process, disproportionation reaction / Jahn-Teller reaction causes manganese dissolution / crystal distortion, which in turn causes the collapse of active sites. HTO exhibits excellent stability and adsorption capacity due to the high titanium-oxygen bond energy and low solubility, but it is relatively expensive and has a slow adsorption rate. As can be seen, both HMO and HTO have certain defects, which limit their industrial development.

[0004] Based on this, some researchers have combined HMO and HTO to make their advantages complement each other. For example, the patent with publication number CN 115646474A discloses that manganese carbonate, nano-titanium dioxide and lithium source are calcined to obtain manganese-titanium-based composite lithium ion sieve nanospheres HMTO with a high degree of manganese-titanium mixing. These nanospheres show relatively uniform spherical morphology, narrow size distribution, small average particle size and large specific surface area. When the composite lithium ion sieve is used for Li + When HMTO is used as an adsorbent, although it can show a high adsorption capacity, its adsorption rate is slow and there is a more obvious manganese dissolution problem during the cycle, and the process cost is high. For example, the patent with publication number CN 118594468 A discloses a H 1.6 Mn 1.6 O4@H2TiO3 composite lithium ion sieves are being developed to improve their adsorption capacity and cycling stability. However, there is still a gap between the actual adsorption capacity of this composite lithium ion sieve and its theoretical adsorption capacity, and the synthesis process is extremely complex and requires demanding conditions. Furthermore, the introduction of a carbon source and a surface soft template during the synthesis process to create pores in the lithium ion sieve releases greenhouse gases during subsequent calcination, impacting the environment. Summary of the Invention

[0005] The purpose of the present invention is to provide a manganese-titanium based composite lithium ion sieve, a preparation method and an application thereof, so as to solve the problems of slow adsorption rate, poor cycle stability and low adsorption capacity of the existing composite lithium ion sieve.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The present application provides a manganese-titanium-based composite lithium ion sieve, abbreviated as HMO@HTO. The composite lithium ion sieve HMO@HTO has a spherical core-shell structure, with the core being a modified manganese-based lithium ion sieve and the shell being a titanium-based lithium ion sieve.

[0007] In this application, the pore size of the composite lithium ion sieve HMO@HTO is 1-150nm, the average particle size is 100nm-1μm, and the specific surface area is 30-130m 2 g -1 , the water contact angle is 0-30°, and the coating thickness of the titanium-based lithium ion sieve is 1-100nm. More preferably, the composite lithium ion sieve HMO@HTO in this application has a pore size of 1-30nm, an average particle size of 300-600nm, and a specific surface area of 100-130m 2 g -1 , the water contact angle is 0-15°, and the coating layer thickness of the titanium-based lithium ion sieve is 5-30nm.

[0008] The present application provides a method for preparing a manganese-titanium-based composite lithium ion sieve, which comprises depositing and growing a layer of titanium-based lithium ion sieve precursor LTO on the surface of a spherical porous / hollow manganese-based lithium ion sieve precursor LMO to form a composite lithium ion sieve precursor LMO@LTO. After acid washing, the composite lithium ion sieve precursor LMO@LTO is obtained to obtain a manganese-titanium-based composite lithium ion sieve HMO@HTO with a spherical core-shell structure.

[0009] Specifically, the preparation process of manganese-titanium based composite lithium ion sieve HMO@HTO includes: S01: At room temperature, a manganese source, a precipitant and a surfactant are co-precipitated in a mixed solvent, and the precipitate is dried, crushed and calcined to obtain porous / hollow manganese dioxide.

[0010] At room temperature, the manganese source, precipitant and surfactant are dissolved in a mixed solvent respectively, stirred and dissolved to form a manganese source solution, a precipitant solution and a surfactant solution. The precipitant solution and the surfactant solution are added to the manganese source solution and co-precipitated at room temperature. 2+ The molar ratio of the surfactant to the precipitant is 1:5-1:1, and the mass of the surfactant is 1-60% of the mass of the manganese source.

[0011] The precipitate formed by coprecipitation is dried at a temperature of 50-100° C. for 2-24 hours to obtain a dried product. The dried product is crushed and calcined at a temperature of 350-450° C. for 3-6 hours to obtain porous / hollow manganese dioxide.

[0012] In this application, the manganese source is one or more water-soluble manganese salts used to provide Mn 2+ , such as manganese sulfate, manganese chloride, manganese nitrate, etc. The precipitant is a salt that ionizes carbonate, which is used to precipitate manganese ions in the manganese source into manganese carbonate, such as ammonium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, etc. The surfactant is used to form spherical micelles of manganese carbonate, reduce surface tension, and introduce hydrophilic groups. The surfactant in this application is selected from one or more of sodium dodecyl sulfate (SDS), sodium dodecyl sulfonate (SDA), sodium hexadecyl sulfate (SLD) and potassium dodecyl sulfate (PLS). The mixed solvent is used to increase steric hindrance to make the manganese carbonate particles more uniform. In this application, the mixed solvent is an ethanol-water solution, wherein the volume ratio of ethanol to water is 1:3-1:1.

[0013] S02: The porous / hollow manganese dioxide and the first lithium source are subjected to wet grinding, drying, hydrothermal reaction, drying, and calcination to obtain a modified manganese-based lithium ion sieve precursor.

[0014] A porous / hollow manganese dioxide is placed in a mortar as a self-sacrificial template. A first lithium source and anhydrous ethanol are added and wet-grinded until dry. This allows for better mixing of the manganese dioxide and the first lithium source, thereby shortening the hydrothermal reaction time and lowering the hydrothermal reaction temperature. The molar ratio of lithium to manganese in the first lithium source and the porous / hollow manganese dioxide is 1.1.

[0015] The ground mixture is dried at 50-100°C for 2-24 hours and then hydrothermally reacted at 120-200°C for 6-24 hours to obtain a hydrothermal reaction product. The hydrothermal reaction product is dried at 50-100°C for 2-24 hours and then calcined at 450-650°C for 3-6 hours to obtain a spherical porous / hollow modified manganese-based lithium ion sieve precursor LMO.

[0016] S03: adding tetrabutyl titanate, a second lithium source, and glacial acetic acid to the modified manganese-based lithium ion sieve precursor, and using a sol-gel method to deposit and grow a titanium-based lithium ion sieve precursor on the surface of the modified manganese-based lithium ion sieve, and obtaining a composite lithium ion sieve precursor after calcination.

[0017] Using a spherical modified manganese-based lithium ion sieve precursor (LMO) as a substrate, anhydrous ethanol, tetrabutyl titanate, and a second lithium source were added and stirred evenly. The molar ratio of lithium to titanium in the second lithium source and tetrabutyl titanate was 1.1. Glacial acetic acid was then added dropwise as a gelling agent to facilitate the deposition and growth of the titanium-based lithium ion sieve precursor (LTO) on the surface of the spherical modified manganese-based lithium ion sieve precursor (LMO). The composite lithium ion sieve precursor (LMO@LTO) was obtained by calcining at a temperature of 450-650°C for 3-6 hours.

[0018] In the present application, the first lithium source and the second lithium source are one or more water-soluble / insoluble lithium salts or bases, such as lithium hydroxide, lithium nitrate, lithium chloride, lithium sulfate, lithium carbonate, lithium fluoride, lithium phosphate, etc.

[0019] S04: The composite lithium ion sieve precursor is ground, pickled with hydrochloric acid, washed with water until neutral, and then dried to obtain a manganese-titanium-based composite lithium ion sieve.

[0020] The ground composite lithium ion sieve precursor LMO@LTO was mixed with 0.1-0.5M hydrochloric acid at a solid-liquid ratio of 1g:50-100mL for acid washing, filtered, washed with water until neutral, and dried at a temperature of 50-100°C for 2-24h to obtain a manganese-titanium-based composite lithium ion sieve HMO@HTO.

[0021] In the present application, the mass of the titanium-based lithium ion sieve precursor is 1-50%, preferably 3-12% of the mass of the modified manganese-based lithium ion sieve precursor. The hydrochloric acid can be analytically pure hydrochloric acid, industrially rich hydrochloric acid, etc.

[0022] The manganese-titanium based composite lithium ion sieve HMO@HTO prepared by the above method can be used as a highly selective adsorbent for extracting lithium from lithium-containing solutions such as salt lake brine and seawater, recovering lithium from waste lithium batteries, and targeted dual screening of Li + .

[0023] The present invention has the following beneficial effects: (1) In the present application, a layer of titanium-based lithium ion sieve precursor LTO is deposited on the surface of a spherical porous / hollow modified manganese-based lithium ion sieve precursor LMO by a sol-gel method, and after calcination and acid washing, a manganese-titanium-based composite lithium ion sieve HMO@HTO with a spherical core-shell multi-level pore structure is obtained.

[0024] (2) The manganese-titanium-based composite lithium ion sieve HMO@HTO is prepared by using manganese source, precipitant and surfactant to prepare manganese dioxide without introducing carbon source, thus realizing green preparation; at the same time, a hydrothermal reaction at a lower temperature and in a shorter time is achieved under the wet grinding precursor, thus realizing the mild preparation of the composite lithium ion sieve.

[0025] (3) The pore size of the manganese-titanium based composite lithium ion sieve HMO@HTO is 1-150nm, the average particle size is 100nm-1μm, and the specific surface area is 30-130m 2 g -1 , the water contact angle is 0-30°, the coating layer thickness of the titanium-based lithium ion sieve is 1-100nm, and it has strong hydrophilicity, high specific surface area and strong dispersibility.

[0026] (4) The manganese-titanium-based composite lithium ion sieve HMO@HTO can achieve the complementary advantages of HMO and HTO, and has a high adsorption capacity, excellent cycle stability and adsorption rate. It can be used as a highly selective adsorbent for lithium extraction from lithium-containing solutions such as salt lake brine and seawater, and for recycling lithium from waste lithium batteries.

[0027] (5) When conducting lithium adsorption experiments in pure lithium solution, the maximum adsorption capacity of the manganese-titanium-based composite lithium ion sieve HMO@HTO reached 60-80 mg g -1 , which is 30-60% higher than that of traditional single manganese-based (HMO) or titanium-based (HTO) lithium ion sieves; the manganese-titanium-based composite lithium ion sieve HMO@HTO can also quickly reach adsorption equilibrium in 3.5 hours. At the same time, the fifth adsorption capacity is 90.41% of the first adsorption capacity, with excellent stability.

[0028] (6) In the experiment of extracting lithium from simulated salt lake brine, the selectivity coefficient of the manganese-titanium based composite lithium ion sieve HMO@HTO for lithium and magnesium is It can reach 800-1000, which is 80-120% higher than the traditional single manganese-based (HMO) or titanium-based (HTO) lithium ion sieve.

[0029] (7) In the manganese-titanium-based composite lithium ion sieve HMO@HTO, the outer titanium-based lithium ion sieve can + Achieve one-time screening, the inner spherical porous / hollow modified manganese-based lithium ion sieve can further screen Li + Realize secondary screening and realize Li + In addition, under double screening, the manganese-titanium-based composite lithium ion sieve HMO@HTO can target the adsorption of Li + , improve selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a TEM image of the manganese-titanium-based composite lithium ion sieve HMO@HTO in Example 1 when magnified to 200 nm; Figure 2 This is a TEM image of the manganese-titanium-based composite lithium ion sieve HMO@HTO in Example 1 when magnified to 500 nm; Figure 3This is a water contact angle detection diagram of the manganese-titanium based composite lithium ion sieve HMO@HTO in Example 1; Figure 4 The nitrogen adsorption and desorption and pore size distribution curves of the manganese-titanium based composite lithium ion sieve HMO@HTO in Example 1 are shown; Figure 5 This is an XRD comparison diagram of the manganese-titanium based composite lithium ion sieve HMO@HTO and the composite lithium ion sieve precursor LMO@LTO in Example 1; Figure 6 This is a comparison chart of the equilibrium adsorption capacity of the manganese-titanium based composite lithium ion sieve HMO@HTO in Example 1, the pure manganese-based lithium ion sieve HMO in Comparative Example 1, and the pure titanium-based lithium ion sieve HTO in Comparative Example 2; Figure 7 The manganese-titanium based composite lithium ion sieve HMO@HTO in Example 1 and the pure manganese-based lithium ion sieve HMO in Comparative Example 1 were used to treat Li + Cycle comparison chart when Figure 8 This is a comparison chart of the adsorption capacity of various ions of the manganese-titanium based composite lithium ion sieve HMO@HTO in Example 1 and the pure manganese-based lithium ion sieve HMO in Comparative Example 1 in simulated salt lake brine. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further explained and illustrated by means of specific embodiments below.

[0032] Example 1 The present invention provides a manganese-titanium-based composite lithium ion sieve HMO@HTO. The preparation method of the composite lithium ion sieve HMO@HTO includes: S101: Dissolve 3.38g of manganese sulfate, 7.9g of ammonium bicarbonate, and 1.69g of SDS in an ethanol-water solution at room temperature, stirring to dissolve, to form a manganese sulfate solution, an ammonium bicarbonate solution, and an SDS solution, wherein the volume ratio of ethanol to water is 1:3. The ammonium bicarbonate solution and the SDS solution are added to the manganese sulfate solution and coprecipitated at room temperature. The coprecipitated precipitate is dried at 60°C for 6 hours to obtain a dried product. The dried product is pulverized and placed in a calcining furnace. The temperature is increased to 400°C at a heating rate of 5°C / min and calcined for 4 hours to obtain porous / hollow manganese dioxide.

[0033] S102: Place 2.78g of porous / hollow manganese dioxide as a self-sacrificial template in a mortar, add 1.48g of lithium hydroxide and anhydrous ethanol for wet grinding until ground to dry. The ground mixture is dried at 60°C for 6 hours and then transferred to a reactor. The temperature is raised to 120°C at a heating rate of 5°C / min for hydrothermal reaction for 12 hours to obtain a hydrothermal reaction product. The hydrothermal reaction product is dried at 60°C for 6 hours and then transferred to a tubular furnace. The temperature is raised to 500°C at a heating rate of 5°C / min and then calcined for 5 hours to obtain a spherical porous / hollow modified manganese-based lithium ion sieve precursor LMO.

[0034] S103: 3.26g of spherical modified manganese-based lithium ion sieve precursor LMO was added to the substrate, along with anhydrous ethanol, 300μL of tetrabutyl titanate, and 0.0823g of lithium hydroxide, and stirred evenly. Five drops of glacial acetic acid were added as a gelling agent to gel the mixture, stirring until dry. The mixture was then transferred to a tube furnace. The mixture was heated to 500°C at a heating rate of 5°C / min and calcined for 5h to obtain the composite lithium ion sieve precursor LMO@LTO.

[0035] S104: The ground composite lithium ion sieve precursor LMO@LTO was mixed with 0.2M hydrochloric acid at a solid-liquid ratio of 1 g:50 mL for pickling, filtered, washed with water until neutral, and dried at 60°C for 6 hours to obtain a manganese-titanium-based composite lithium ion sieve HMO@HTO.

[0036] Example 2 The present invention provides a manganese-titanium-based composite lithium ion sieve HMO@HTO. The preparation method of the composite lithium ion sieve HMO@HTO includes: S201: Dissolve 3.96g of manganese chloride, 7.9g of ammonium bicarbonate, and 1.69g of SDS in an ethanol-water solution at room temperature, stirring to dissolve, to form a manganese sulfate solution, an ammonium bicarbonate solution, and an SDS solution, wherein the volume ratio of ethanol to water is 1:2. The ammonium bicarbonate solution and the SDS solution are added to the manganese sulfate solution to effect coprecipitation at room temperature. The coprecipitated precipitate is dried at 80°C for 4 hours to obtain a dried product. The dried product is pulverized and placed in a calcining furnace. The temperature is increased to 350°C at a heating rate of 5°C / min and calcined for 5 hours to obtain porous / hollow manganese dioxide.

[0037] S202: Place 2.7g of porous / hollow manganese dioxide as a self-sacrificial template in a mortar, add 1.3g of lithium carbonate and anhydrous ethanol for wet grinding until it is ground to dry. The ground mixture is dried at 80°C for 4h and then transferred to a reactor. The temperature is raised to 160°C at a heating rate of 5°C / min for hydrothermal reaction for 15h to obtain a hydrothermal reaction product. The hydrothermal reaction product is dried at 80°C for 4h and then transferred to a tubular furnace. The temperature is raised to 600°C at a heating rate of 5°C / min and then calcined for 4h to obtain a spherical porous / hollow modified manganese-based lithium ion sieve precursor LMO.

[0038] S203: Using 3.26g of spherical modified manganese-based lithium ion sieve precursor LMO as the substrate, add anhydrous ethanol, 600μL of tetrabutyl titanate, and 0.1646g of lithium hydroxide and stir evenly. Add 5 drops of glacial acetic acid as a gelling agent to gel, stir until dry, and transfer to a tube furnace. Heat to 600℃ at a heating rate of 5℃ / min and calcine for 4h to obtain the composite lithium ion sieve precursor LMO@LTO.

[0039] S204: The ground composite lithium ion sieve precursor LMO@LTO was mixed with 0.5M hydrochloric acid at a solid-liquid ratio of 1 g:50 mL, and then acid-washed. After filtering, the mixture was washed with water until neutral, and dried at 80°C for 4 hours to obtain a manganese-titanium-based composite lithium ion sieve HMO@HTO.

[0040] Example 3 The present invention provides a manganese-titanium-based composite lithium ion sieve HMO@HTO. The preparation method of the composite lithium ion sieve HMO@HTO includes: S301: Dissolve 1.845g of manganese chloride, 1.69g of manganese sulfate, 7.9g of ammonium bicarbonate, and 1.69g of SLD in an ethanol-water solution at room temperature, stirring to dissolve, to form a manganese solution, an ammonium bicarbonate solution, and an SLD solution. The volume ratio of ethanol to water is 1:1. The ammonium bicarbonate solution and the SLD solution are added to the manganese solution to cause coprecipitation at room temperature. The coprecipitated precipitate is dried at 100°C for 2 hours to obtain a dried product. This dried product is pulverized and placed in a calcining furnace. The temperature is increased to 450°C at a heating rate of 5°C / min and calcined for 3 hours to obtain porous / hollow manganese dioxide.

[0041] S302: 2.78g of porous / hollow manganese dioxide was placed in a mortar as a self-sacrificial template, and 1.3g of lithium carbonate and anhydrous ethanol were added for wet grinding until it was ground to dryness. The ground mixture was dried at a temperature of 100°C for 4 hours and then transferred to a reactor. The temperature was raised to 200°C at a heating rate of 5°C / min for a hydrothermal reaction for 6 hours to obtain a hydrothermal reaction product. The hydrothermal reaction product was dried at a temperature of 100°C for 2 hours and then transferred to a tubular furnace. The temperature was raised to 650°C at a heating rate of 5°C / min and then calcined for 3 hours to obtain a spherical porous / hollow modified manganese-based lithium ion sieve precursor LMO.

[0042] S303: 3.26g of spherical modified manganese-based lithium ion sieve precursor LMO was added to anhydrous ethanol, 900μL of tetrabutyl titanate, and 0.2469g of lithium hydroxide, and stirred evenly. Five drops of glacial acetic acid were added as a gelling agent to gel the mixture. The mixture was stirred until dry and transferred to a tube furnace. The temperature was increased to 650°C at a heating rate of 5°C / min and then calcined for 3h to obtain the composite lithium ion sieve precursor LMO@LTO.

[0043] S304: The ground composite lithium ion sieve precursor LMO@LTO was mixed with 0.2M hydrochloric acid according to a solid-liquid ratio of 1g:100mL for acid washing, filtered, washed with water until neutral, and dried at 100°C for 2h to obtain a manganese-titanium-based composite lithium ion sieve HMO@HTO.

[0044] Comparative Example 1 This comparative example provides a pure manganese-based lithium ion sieve HMO, and the preparation method of the manganese-based lithium ion sieve HMO comprises: D101: Dissolve 3.38g of manganese sulfate, 7.9g of ammonium bicarbonate, and 1.69g of SDS in an ethanol-water solution at room temperature. Stir and dissolve to form a manganese sulfate solution, an ammonium bicarbonate solution, and an SDS solution, respectively. The volume ratio of ethanol to water is 1:3. The ammonium bicarbonate solution and the SDS solution are added to the manganese sulfate solution to cause coprecipitation at room temperature. The coprecipitated precipitate is dried at 60°C for 6 hours to obtain a dried product. This dried product is pulverized and placed in a calcining furnace. The temperature is increased to 400°C at a heating rate of 5°C / min and calcined for 4 hours to obtain porous / hollow manganese dioxide.

[0045] D102: 2.78g of porous / hollow manganese dioxide was placed in a mortar as a self-sacrificial template, and 1.48g of lithium hydroxide and anhydrous ethanol were added for wet grinding until it was dry. The ground mixture was dried at 60°C for 6 hours and then transferred to a reactor. The temperature was raised to 120°C at a heating rate of 5°C / min for hydrothermal reaction for 12 hours to obtain a hydrothermal reaction product. The hydrothermal reaction product was dried at 60°C for 6 hours and then transferred to a tubular furnace. The temperature was raised to 500°C at a heating rate of 5°C / min and then calcined for 5 hours to obtain a spherical porous / hollow modified manganese-based lithium ion sieve precursor LMO.

[0046] D103: The manganese-based lithium ion sieve precursor LMO was mixed with 0.2M hydrochloric acid at a solid-liquid ratio of 1g:50mL for acid washing. After filtering, the mixture was washed with water until neutrality was achieved. The mixture was dried at 60°C for 6h to obtain pure manganese-based lithium ion sieve HMO.

[0047] Comparative Example 2 This comparative example provides a pure titanium-based lithium ion sieve HTO, and the preparation method of the titanium-based lithium ion sieve HTO comprises: D201: Add 300 μL of tetrabutyl titanate and 0.0823 g of lithium hydroxide to anhydrous ethanol and stir thoroughly. Add 5 drops of glacial acetic acid as a gelling agent to gel the mixture. Stir until dry and transfer to a tube furnace. Heat the mixture to 500°C at a rate of 5°C / min and calcine for 5 hours to obtain the titanium-based ion-sieve precursor LTO.

[0048] D202: The titanium-based lithium ion sieve precursor LTO was mixed with 0.2M hydrochloric acid at a solid-liquid ratio of 1g:50mL for acid washing, filtered, washed with water until neutral, and dried at 60°C for 6h to obtain pure titanium-based lithium ion sieve HTO.

[0049] The manganese-titanium based composite lithium ion sieve HMO@HTO prepared in Example 1 of the present application was subjected to TEM detection at different magnifications, water contact angle, nitrogen adsorption and desorption, and pore size distribution detection to obtain the attached Figure 1-4 .

[0050] By the attached Figure 1 、 2 It can be seen that the manganese-titanium based composite lithium ion sieve HMO@HTO prepared in Example 1 of the present application is a spherical hollow / porous core-shell structure with an average particle size of 100nm-1μm, a pore size of 1-150nm, and a specific surface area of 30-130m 2 g -1 Among them, the part outside the outer green line is the titanium-based lithium ion sieve HTO, and the part inside the outer green line is the manganese-based lithium ion sieve HMO.

[0051] By the attached Figure 3It can be seen that the water contact angle of the manganese-titanium-based composite lithium ion sieve HMO@HTO prepared in Example 1 of the present application is 0-30°, which indicates that the composite lithium ion sieve HMO@HTO has strong hydrophilicity.

[0052] By the attached Figure 4 It can be seen that the manganese-titanium-based composite lithium ion sieve HMO@HTO prepared in Example 1 of the present application has a multi-level pore structure.

[0053] The present application also conducted XRD tests on the composite lithium ion sieve precursor LMO@LTO and the prepared manganese-titanium based composite lithium ion sieve HMO@HTO in the preparation process of Example 1, and obtained the attached Figure 5 . Figure 5 It can be seen that both the composite lithium ion sieve precursor LMO@LTO and the manganese-titanium-based composite lithium ion sieve HMO@HTO contain LMO and LTO, and lithium is removed after acid washing.

[0054] In addition, the prepared manganese-titanium-based composite lithium ion sieve HMO@HTO was subjected to adsorption capacity experiments, cycle experiments, and simulated salt lake lithium extraction experiments, and the specific contents are as follows: 1. Adsorption capacity experiment The preparation volume is 90 mL, the pH is 12.0, and the concentration is 1 g / L -1 The initial lithium solution was divided into three parts on average. 0.2 g of the manganese-titanium composite lithium ion sieve HMO@HTO in Example 1, the pure manganese-based lithium ion sieve HMO in Comparative Example 1, and the pure titanium-based lithium ion sieve HTO in Comparative Example 2 were added to the three initial lithium solutions respectively. The adsorption was carried out at 35°C for 12 hours. After the adsorption, the samples were filtered, washed, and dried. The mass of the lithium ion sieve before and after adsorption was calculated to obtain the adsorbed lithium ion sieve. Figure 6 The equilibrium adsorption capacity is shown.

[0055] By the attached Figure 6 It can be seen that the equilibrium adsorption capacities of the manganese-titanium based composite lithium ion sieve HMO@HTO in Example 1, the pure manganese-based lithium ion sieve HMO in Comparative Example 1, and the pure titanium-based lithium ion sieve HTO in Comparative Example 2 are 65 mg g -1 , 55mg g -1 and 48 mg g -1 , and the manganese-titanium based composite lithium ion sieve HMO@HTO in Example 1 has a great influence on Li + It has a larger adsorption capacity. This shows that HMO and HTO in the composite lithium ion sieve can synergistically extract lithium with significant results.

[0056] 2. Cycle experiment The volume is 100 mL, the pH is 12.0, and the concentration is 1 g / L -1The initial lithium solution was divided into two parts on average. 0.2g of the manganese-titanium composite lithium ion sieve HMO@HTO in Example 1 and the pure manganese-based lithium ion sieve HMO in Comparative Example 1 were added to the two initial lithium solutions respectively, and adsorbed at 35°C for 6 hours. After the adsorption, the sample was filtered, washed and dried, and the mass before and after the adsorption of the lithium ion sieve was calculated to obtain the adsorption capacity. After the lithium ion sieve was desorbed, it was adsorbed at 35°C for 6 hours, and this cycle was repeated 5 times to obtain the adsorption capacity. Figure 7 .

[0057] By the attached Figure 7 It can be seen that compared with the pure manganese-based lithium ion sieve HMO in Comparative Example 1, the manganese-titanium-based composite lithium ion sieve HMO@HTO in Example 1 of the present application has a better effect on Li + The maximum adsorption capacity reaches 60-80 mg g -1 , increased by 30-60%; at the same time, the manganese-titanium-based composite lithium ion sieve HMO@HTO can quickly reach adsorption equilibrium in 3.5 h, and the fifth adsorption capacity is 90.41% of the first adsorption capacity, which shows that the outer layer coating of titanium-based lithium ion sieve HTO can improve the stability of the manganese-titanium-based composite lithium ion sieve HMO@HTO, making it have better cycle stability.

[0058] 3. Simulated salt lake lithium extraction experiment In order to verify that the manganese-titanium based composite lithium ion sieve HMO@HTO prepared in this application example can target the adsorption of Li + In this application, the composition of the brine of Xitaijinaier Salt Lake is simulated, and 100mL of simulated salt lake brine is prepared. The simulated salt lake brine is divided into two parts, and 0.2g of the manganese-titanium based composite lithium ion sieve HMO@HTO in Example 1 and the pure manganese-based lithium ion sieve HMO in Comparative Example 1 are added to the two parts of the simulated salt lake brine, and adsorbed at 35°C for 6h. After the adsorption is completed, the sample is filtered, washed and dried, and the mass of the lithium ion sieve before and after adsorption is calculated to obtain the adsorption mass. Figure 8 The adsorption capacity shown and the adsorption related data of different ions shown in Table 1.

[0059] Table 1: Parameters of simulated salt lake brine From Table 1 and Appendix Figure 8 It can be seen that compared with the pure manganese-based lithium ion sieve HMO in comparative example 1, the manganese-titanium-based composite lithium ion sieve HMO@HTO in example 1 has better adsorption performance, even in the presence of a large amount of Li + 、Na + , K + , Ca 2+ Mg 2+ In the simulated salt lake brine containing impurity ions such as Li+ Highly selective adsorption effect. In addition, the separation coefficients in Table 1 show that the separation coefficient of the manganese-titanium-based composite lithium ion sieve HMO@HTO in Example 1 for each ion is greater than the separation coefficient of the pure manganese-based lithium ion sieve HMO in Comparative Example 1, and has an excellent distribution coefficient. This is because during the adsorption process of the manganese-titanium-based composite lithium ion sieve HMO@HTO, the lithium ion sieve undergoes two layers of screening, namely, the outer layer of titanium-based lithium ion sieve HTO and the inner layer of manganese-based lithium ion sieve HMO. That is, the outer layer of titanium-based lithium ion sieve HTO performs the initial screening of various ions in the simulated salt lake brine through the size exclusion effect, and the inner layer of manganese-based lithium ion sieve HMO performs the secondary screening through the ion embedding energy barrier. This dual screening mechanism enables the manganese-titanium-based composite lithium ion sieve HMO@HTO to exhibit excellent selectivity.

[0060] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A manganese-titanium based composite lithium ion sieve, characterized in that: The core of the composite lithium ion sieve is a modified manganese-based lithium ion sieve, and the outer shell is a titanium-based lithium ion sieve.

2. The manganese-titanium based composite lithium ion sieve according to claim 1, characterized in that: The composite lithium ion sieve has a spherical core-shell structure, a pore size of 1-150 nm, an average particle size of 100 nm-1 μm, and a specific surface area of 30-130 m 2 g -1 , the water contact angle is 0-30°, and the coating layer thickness of the titanium-based lithium ion sieve is 1-100 nm.

3. The method for preparing the manganese-titanium based composite lithium ion sieve according to claim 1 or 2, characterized in that: include: S01: At room temperature, a manganese source, a precipitant, and a surfactant are co-precipitated in a mixed solvent. The precipitate is dried, crushed, and calcined to obtain porous / hollow manganese dioxide; S02: The porous / hollow manganese dioxide and the first lithium source are subjected to wet grinding, drying, hydrothermal reaction, drying, and calcination to obtain a modified manganese-based lithium ion sieve precursor; S03: adding tetrabutyl titanate, a second lithium source, and glacial acetic acid to the modified manganese-based lithium ion sieve precursor, and depositing and growing a titanium-based lithium ion sieve precursor on the surface of the modified manganese-based lithium ion sieve precursor by a sol-gel method, and obtaining a composite lithium ion sieve precursor after calcination; S04: The composite lithium ion sieve precursor is ground, pickled with hydrochloric acid, washed with water until neutral, and then dried to obtain a manganese-titanium-based composite lithium ion sieve.

4. The method for preparing the manganese-titanium based composite lithium ion sieve according to claim 3, characterized in that: The manganese source is one or more water-soluble manganese salts, the precipitant is a salt that ionizes carbonate, the surfactant includes one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium hexadecyl sulfate and potassium dodecyl sulfate, and the mixed solvent is an ethanol-water solution; the first lithium source and the second lithium source are both one or more water-soluble / insoluble lithium-containing salts or alkalis.

5. The method for preparing the manganese-titanium based composite lithium ion sieve according to claim 3, characterized in that: The molar ratio of manganese ions to precipitant in the manganese source is 1:5-1:1, and the mass of the surfactant is 1-60% of the mass of the manganese source; the molar ratio of lithium element to manganese element in the first lithium source and porous / hollow manganese dioxide is 1.1, the molar ratio of lithium element to titanium element in the second lithium source and tetrabutyl titanate is 1.1, and the mass of the titanium-based lithium ion sieve precursor is 1-50% of the mass of the modified manganese-based lithium ion sieve precursor.

6. The method for preparing the manganese-titanium based composite lithium ion sieve according to claim 3, characterized in that: In S01, the drying temperature is 50-100° C. and the drying time is 2-24 hours; the calcination temperature is 350-450° C. and the calcination time is 3-6 hours.

7. The method for preparing the manganese-titanium based composite lithium ion sieve according to claim 3, characterized in that: In S02, the baking and drying temperature is 50-100°C and the time is 2-24h; the hydrothermal reaction temperature is 120-200°C and the reaction time is 6-24h; the calcination temperature is 450-650°C and the calcination time is 3-6h.

8. The method for preparing the manganese-titanium based composite lithium ion sieve according to claim 3, characterized in that: In S03, the calcination temperature is 450-650°C and the calcination time is 3-6 hours; in S04, the drying temperature is 50-100°C and the drying time is 2-24 hours.

9. The method for preparing the manganese-titanium based composite lithium ion sieve according to claim 3, characterized in that: The concentration of the hydrochloric acid is 0.1-0.5M, and the solid-liquid ratio of the composite lithium ion sieve precursor to the hydrochloric acid is 1g:50-100mL.

10. The manganese-titanium based composite lithium ion sieve according to claim 1 or 2 or the manganese-titanium based composite lithium ion sieve prepared by the preparation method according to any one of claims 3 to 9 is used for extracting lithium from lithium-containing solutions such as salt lake brine and seawater, recovering lithium from waste lithium batteries, and targeted dual screening of lithium + .

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