A supported ionic-sieve adsorbent, its preparation method and use

Abstract

The application provides a supported ion sieve adsorbent and a preparation method and application thereof, and the preparation method comprises the following steps: (1) mixing a titanium source, ammonia water, triethanolamine and a phosphate with a first solvent, adding a manganese-based ion sieve precursor, and calcining after heating to obtain a titanium dioxide coated manganese-based ion sieve; (2) dispersing the titanium dioxide coated manganese-based ion sieve in ethylenediamine to form a first suspension, and adding lithium element for selective reduction; (3) mixing the selectively reduced titanium dioxide coated manganese-based ion sieve with a second solvent, and then dropping the mixture onto the surface of a hydroxylated silicon dioxide carrier, and obtaining the supported ion sieve adsorbent after microwave irradiation. In the application, the manganese-based lithium ion sieve is coated with titanium dioxide in situ in advance, part of the titanium dioxide is selectively reduced to generate a large amount of hydroxyl groups, and the hydroxyl groups are condensed with the hydroxylated silicon dioxide carrier through microwave irradiation, so that the dissolution loss of manganese is inhibited, the combination strength of the lithium ion sieve and the substrate is high, and the cycle performance is good.

Description

Technical Field

[0001] This invention belongs to the field of lithium extraction technology from salt lakes, and relates to a supported ion sieve adsorbent, its preparation method and application. Background Technology

[0002] Lithium is widely recognized as a driving force in global progress, with applications in mobile phones, computers, home appliances, and aerospace. Global consumption of lithium products continues to increase annually, leading to a supply shortage in the lithium resource market. Lithium exists in nature in both liquid and solid forms. Solid lithium is found in various ores, but its reserves account for less than 30% of total reserves. Mining these ores requires significant energy consumption, and the calcination process generates pollutants, resulting in adverse environmental impacts and low production capacity. In contrast, lithium found in oceans and salt lake brines is not only abundant and easy to mine, but its cost advantage is also attracting increasing attention from the industry.

[0003] Lithium extraction from salt lake brine has evolved through various methods, including adsorption, extraction, membrane methods, electrodialysis, and electrochemical methods. Among these, adsorption has been commercially applied due to its high selectivity and ease of recovery. Common adsorption methods utilize ion sieve-type oxide adsorbents, broadly categorized as aluminum-based, manganese-based, and titanium-based. These adsorbents exist in powder form, which makes uniform distribution and prone to clumping during actual use, resulting in poor permeability and flowability, hindering industrial applications. Therefore, ion sieves are often processed into molded packing materials. Existing granulation and casting methods use polymer bonding, which not only clogs ion sieve channels, leading to a significant reduction in adsorption capacity, but also introduces excessive amounts of inactive substances during the molding process, severely impacting the overall adsorption performance of the material.

[0004] CN110773112A discloses a modified manganese-based lithium-ion sieve and its preparation method. The modified manganese-based lithium-ion sieve comprises a manganese-based lithium-ion sieve and alumina coated on its surface. The preparation method of the modified manganese-based lithium-ion sieve includes the following steps: adding an aluminum source and a manganese-based lithium-ion sieve precursor to a reaction medium to obtain a suspension; adjusting the pH of the suspension to above 9 using an alkaline solution, and then performing solid-liquid separation; calcining the obtained solid phase at 350–500°C to obtain the modified manganese-based lithium-ion sieve precursor; and acid washing the modified manganese-based lithium-ion sieve precursor to obtain the modified manganese-based lithium-ion sieve.

[0005] CN116966880A discloses a method for preparing hydrogel granular manganese-based lithium ion sieves, comprising the following steps: mixing lithium hydroxide monohydrate, manganese carbonate, and water, then removing water by rotary evaporation, calcining, and annealing to obtain a precursor for manganese-based lithium ion sieves; dissolving the precursor in dilute hydrochloric acid solution, stirring, centrifuging, and drying to obtain a manganese-based lithium ion sieve; adding carboxymethyl cellulose to the manganese-based lithium ion sieve and water, stirring, heating, adding acrylic acid, sodium p-styrene sulfonate, a crosslinking agent, and an initiator, stirring thoroughly, reacting to obtain a hydrogel colloid containing manganese-based lithium ion sieves, drying, and obtaining hydrogel granular manganese-based lithium ion sieves.

[0006] The above scheme uses a complex method to prepare modified lithium-ion sieves to solve the problem of manganese loss. However, the above method still has its limitations. The overall adsorption performance of the material decreases, and the lithium adsorption capacity declines significantly during the recycling process. Summary of the Invention

[0007] The purpose of this invention is to provide a supported ion sieve adsorbent, its preparation method, and its application. In this invention, a manganese-based lithium ion sieve is first coated with titanium dioxide in situ, and then a portion of the titanium dioxide is selectively reduced to generate a large amount of hydroxyl groups (Ti-OH). These hydroxyl groups are then microwave-condensed with a hydroxylated silica support to obtain a supported ion sieve adsorbent. This not only inhibits the dissolution of manganese, but also exhibits high bonding strength between the lithium ion sieve and the substrate, resulting in good cycle performance.

[0008] To achieve this objective, the present invention employs the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a supported ion sieve adsorbent, the method comprising the following steps:

[0010] (1) Mix titanium source, ammonia, triethanolamine and phosphate with the first solvent, add manganese ion sieve precursor, heat treatment to obtain gel, calcine the gel to obtain titanium dioxide coated manganese ion sieve precursor.

[0011] (2) The titanium dioxide-coated manganese ion sieve precursor is dispersed in ethylenediamine (EDA) to form a first suspension. After adding elemental lithium, the mixture is stirred and reacted to obtain a selectively reduced titanium dioxide-coated manganese ion sieve.

[0012] (3) Selectively reduced titanium dioxide coated manganese ion sieve is mixed with a second solvent to obtain a second suspension. The second suspension is dropped onto the surface of the hydroxylated modified silica support and then irradiated with microwave to obtain the supported ion sieve adsorbent.

[0013] This invention first prepares a titanium dioxide-coated manganese-based ion sieve. The titanium dioxide synthesized in situ on the manganese-based ion sieve precursor acts as a coating, which can inhibit the dissolution of manganese and enhance the circulation capacity of the ion sieve. During the synthesis process, a small amount of phosphate is added so that the synthesized titanium dioxide has both anatase and rutile phases. Then, the rutile phase is selectively reduced to an amorphous state, thereby generating a large number of hydroxyl groups (Ti-OH). Further, through microwave irradiation-induced condensation with the hydroxylated silica support, the titanium dioxide-coated manganese-based ion sieve is covalently linked to the silica support. This achieves the molding effect of ion sieve channels without adhesives or clogging. Moreover, the microwave irradiation method does not require high-temperature calcination and can be quickly loaded onto various silica-containing substrates according to local conditions. The covalent bond makes it more stable, and the ion sieve material will not fall off in large quantities even after repeated washing over a long period of time.

[0014] Preferably, the titanium source in step (1) includes tetrabutyl titanate and / or isopropyl titanate.

[0015] Preferably, the mass ratio of the titanium source and triethanolamine in step (1) is (10-30):1, for example: 10:1, 15:1, 20:1, 25:1 or 30:1, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0016] Preferably, the molar ratio of phosphate in the phosphate and titanium in the titanium source in step (1) is (0.4 to 1.3):100, for example: 0.4:100, 0.6:100, 0.8:100, 1:100 or 1.3:100, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0017] Preferably, in step (1), the first solvent comprises anhydrous ethanol.

[0018] Preferably, the manganese-based ion sieve precursor in step (1) includes LiMn2O4 and Li 1.33 Mn 1.67 O4 or Li 1.6 Mn 1.6 Any one or at least two of O4.

[0019] Preferably, the mass ratio of the manganese-based ion sieve precursor to the titanium source in step (1) is 1:(0.05 to 0.2), for example: 1:0.05, 1:0.08, 1:0.1, 1:0.15 or 1:0.2, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 1:(0.08 to 0.15).

[0020] Preferably, the heat treatment in step (1) includes heating and stirring and heating and aging.

[0021] Preferably, the heating and stirring temperature is 40-60°C, for example: 40°C, 45°C, 50°C, 55°C or 60°C, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Preferably, the heating aging temperature in step (1) is 65 to 85°C, for example: 65°C, 70°C, 75°C, 80°C or 85°C.

[0023] Preferably, the heating aging time in step (1) is 18 to 36 hours, for example: 18 hours, 24 hours, 28 hours, 32 hours or 36 hours, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] Preferably, the calcination temperature in step (1) is 500 to 700°C, for example: 500°C, 550°C, 600°C, 650°C or 700°C, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] Preferably, the calcination time in step (1) is 6 to 8 hours, for example: 6 hours, 6.5 hours, 7 hours, 7.5 hours or 8 hours, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] Preferably, the calcination treatment in step (1) is followed by washing and drying.

[0027] Preferably, the detergent used for washing includes deionized water and / or distilled water.

[0028] Preferably, the washing is performed 3 to 4 times, for example, 3 or 4 times.

[0029] Preferably, the drying time is 6 to 12 hours, for example: 6 hours, 8 hours, 9 hours, 10 hours or 12 hours, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] Preferably, the condition for adding elemental lithium in step (2) is an ice bath.

[0031] Preferably, the molar ratio of titanium to lithium in the titanium dioxide-coated manganese ion sieve precursor in step (2) is 1:(0.8 to 1.2), for example: 1:0.8, 1:0.9, 1:1, 1:1.1 or 1:1.2, etc.

[0032] Preferably, the stirring reaction time in step (2) is 36 to 48 hours.

[0033] Preferably, after the stirring reaction in step (2), the mixture is filtered, washed with water, dried and acid-soaked.

[0034] Preferably, the acid solution used for acid leaching includes 0.2 to 1 mol / L hydrochloric acid (0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L or 1 mol / L, etc., not limited to the listed values, other unlisted values ​​within this range are also applicable).

[0035] Preferably, the acid leaching time is 8 to 15 hours, for example: 8 hours, 9 hours, 10 hours, 12 hours or 15 hours, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] Preferably, in step (3), the second solvent comprises anhydrous ethanol.

[0037] Preferably, the mixture in step (3) is subjected to ultrasonic treatment.

[0038] Preferably, the ultrasonic treatment time is 30 to 60 minutes, for example: 30 minutes, 35 minutes, 40 minutes, 50 minutes or 60 minutes, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] Preferably, the concentration of the suspension in step (3) is 1 to 5 g / L, for example: 2 g / L, 3 g / L, 4 g / L, 4.5 g / L or 5 g / L, etc., not limited to the listed values, other unlisted values ​​within this range are also applicable, preferably 2 to 4 g / L.

[0040] Preferably, the hydroxylation modification process in step (3) includes plasma treatment of the silica support.

[0041] Preferably, the silica carrier includes any one or a combination of at least two of the following: a silica substrate, a silica base plate, or a porous silica tube. Typical but non-limiting combinations include combinations of silica substrate and silica base plate, combinations of silica substrate and porous silica tube, or combinations of silica substrate, silica base plate, and porous silica tube, etc.

[0042] Preferably, the frequency of the plasma treatment is 50 to 60 Hz, for example: 50 Hz, 52 Hz, 55 Hz, 58 Hz or 60 Hz, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] Preferably, the power of the plasma treatment is 150 to 250W, for example: 150W, 180W, 200W, 220W or 250W, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Preferably, the oxygen flow rate of the plasma treatment is 40-60 cc / min, for example: 40 cc / min, 45 cc / min, 50 cc / min, 55 cc / min or 60 cc / min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Preferably, the power of microwave irradiation in step (3) is 500 to 700W, for example: 500W, 550W, 600W, 650W or 700W, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0046] Preferably, the microwave irradiation time in step (3) is 1 to 5 minutes, for example: 1 minute, 2 minutes, 3 minutes, 4 minutes or 5 minutes, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] In a second aspect, the present invention provides a supported ion sieve adsorbent, which is prepared by the method described in the first aspect.

[0048] Thirdly, the present invention provides an application of the supported ion sieve adsorbent as described in the second aspect, wherein the supported ion sieve adsorbent is used for lithium extraction from salt lakes.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] (1) In this invention, after pre-coating the manganese-based lithium ion sieve with titanium dioxide in situ, a portion of the titanium dioxide is selectively reduced to generate a large amount of hydroxyl groups (Ti-OH), which are then microwave-condensed with the hydroxylated silica carrier to obtain a supported ion sieve adsorbent. This not only inhibits the dissolution of manganese, but also has a high bonding strength between the lithium ion sieve and the substrate, resulting in good cycle performance.

[0051] (2) The supported ion sieve adsorbent prepared by the method of the present invention has an equilibrium adsorption capacity of more than 22.91 mg / g, a manganese loss of less than 0.84% ​​after 5 cycles, and an adsorption capacity retention rate of more than 85.27%. By adjusting the ratio of each raw material and the reaction conditions, the equilibrium adsorption capacity of the supported ion sieve adsorbent can reach 27.58 mg / g, the manganese loss after 5 cycles can reach 0.21%, and the adsorption capacity retention rate can reach 91.68%. Attached Figure Description

[0052] Figure 1 This is a SEM image of the supported ion sieve adsorbent prepared in Example 1.

[0053] Figure 2This is an XPS image of TiO2, selectively reduced TiO2, and selectively reduced TiO2 loaded onto the interface of hydroxylated silica.

[0054] Figure 3 This is the XRD pattern of the titanium dioxide-coated manganese-based ion sieve precursor obtained during the preparation of the supported ion sieve adsorbent described in Example 1. Detailed Implementation

[0055] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0056] Example 1

[0057] This embodiment provides a supported ion sieve adsorbent, and the preparation method of the supported ion sieve adsorbent is as follows:

[0058] (1) Add 2 mL of 35% ammonia to 50 mL of anhydrous ethanol, then add 4 g of tetrabutyl titanate, 0.3 g of triethanolamine, potassium phosphate, phosphate, and Ti. 4+ The molar ratio of the two materials was 0.8:100. After stirring uniformly for 15 min, the manganese-based ion sieve precursor LiMn2O4 was added. The mass ratio of the manganese-based ion sieve precursor to the titanium source was 1:0.1. The mixture was heated to 50℃ and stirred vigorously to form a colloid. Then, it was aged in an oven at 65℃ for 24 h. Subsequently, it was placed in a muffle furnace and calcined at 500℃ for 8 h. It was washed repeatedly with deionized water and distilled water 3-4 times and dried at 65℃ for 10 h to obtain titanium dioxide-coated manganese-based ion sieve precursor LiMn2O4@TiO2.

[0059] (2) A suspension was formed by mixing LiMn2O4@TiO2 and EDA at a solid-liquid ratio of 1g:200mL. Lithium metal particles (TiO2:Li = 1:1) were rapidly added under ice bath conditions. The suspension was then transferred to a room temperature environment and stirred under a nitrogen atmosphere for 40h. After the reaction was completed, the suspension was filtered, washed with deionized water, dried in a vacuum oven, and then dispersed in 0.5mol / L dilute hydrochloric acid and stirred at room temperature for 12h. After filtration and washing, the suspension was dried under vacuum at 60℃ to obtain LiMn2O4@selectively reduced TiO2.

[0060] (3) Take a 1.5cm square silica substrate, wash it three times with deionized water and dry it. Treat it with O2 plasma for 30s at 55Hz, 200W and 50cc / min to obtain surface hydroxylated silica. Place the LiMn2O4@selective reduction TiO2 ion sieve in anhydrous ethanol and sonicate to form a 3g / L suspension. Take 0.5mL of the suspension and drop it onto the hydroxylated silica substrate. Microwave irradiation power of 600W reacts for 2min to obtain the supported ion sieve adsorbent.

[0061] SEM images of the prepared supported ion sieve adsorbent are shown below. Figure 1 As shown.

[0062] Example 2

[0063] This embodiment provides a supported ion sieve adsorbent, and the preparation method of the supported ion sieve adsorbent is as follows:

[0064] (1) Add 2 mL of 35% ammonia to 50 mL of anhydrous ethanol, then add 3 g of tetrabutyl titanate, 0.3 g of triethanolamine, potassium phosphate, phosphate, and Ti. 4+ The molar ratio was 0.4:100. After stirring uniformly for 20 minutes, the manganese-based ion sieve precursor Li was added. 1.33 Mn 1.67 O4, a manganese-based ion sieve precursor, and a titanium source were mixed at a mass ratio of 1:0.15. The mixture was heated to 40°C and vigorously stirred to form a colloid. It was then aged in an oven at 70°C for 20 hours, followed by calcination in a muffle furnace at 600°C for 7 hours. The mixture was then washed repeatedly with deionized and distilled water 3-4 times and dried at 65°C for 6 hours to obtain titanium dioxide-coated manganese-based ion sieve precursor Li. 1.33 Mn 1.67 O4@TiO2.

[0065] (2) Li 1.33 Mn 1.67 O4@TiO2 and EDA were mixed at a solid-liquid ratio of 1 g: 200 mL to form a suspension. Lithium metal particles (TiO2:Li = 1:0.8) were rapidly added under ice bath conditions. The mixture was then transferred to a room temperature environment under a nitrogen atmosphere and stirred for 36 h. After the reaction was complete, the mixture was filtered, washed with deionized water, dried in a vacuum oven, and then dispersed in 0.2 mol / L dilute hydrochloric acid. The mixture was stirred at room temperature for 15 h, filtered, washed, and then dried under vacuum at 60 °C to obtain Li. 1.33 Mn 1.67 O4@selective reduction of TiO2.

[0066] (3) A 1.5cm square silica substrate was washed three times with deionized water and dried. It was then treated with O2 plasma for 20s at 50Hz, 250W, and a flow rate of 60cc / min to obtain surface-hydroxylated silica. Li 1.33 Mn 1.67 The O4@selective reduction TiO2 ion sieve was ultrasonically dissolved in anhydrous ethanol to form a 2 g / L suspension. 0.8 mL of the suspension was then dropped onto a hydroxylated silica substrate and reacted with microwave irradiation at 500 W for 5 min to obtain the supported ion sieve adsorbent.

[0067] Example 3

[0068] This embodiment provides a supported ion sieve adsorbent, and the preparation method of the supported ion sieve adsorbent is as follows:

[0069] (1) Take 50 ml of anhydrous ethanol and add 2 mL of 35% ammonia water. Then add 9 g of tetrabutyl titanate, 0.3 g of triethanolamine, potassium phosphate, phosphate, and Ti. 4+ The molar ratio was 1.3:100. After stirring uniformly for 20 minutes, the manganese-based ion sieve precursor Li was added. 1.6 Mn 1.6 O4, a manganese-based ion sieve precursor, and a titanium source were mixed at a mass ratio of 1:0.08. The mixture was heated to 60°C and vigorously stirred to form a colloid. It was then aged in an oven at 85°C for 18 hours, followed by calcination in a muffle furnace at 700°C for 6 hours. The mixture was then washed repeatedly with deionized water and distilled water 3-4 times and dried at 65°C for 12 hours to obtain titanium dioxide-coated manganese-based ion sieve precursor Li. 1.6 Mn 1.6 O4@TiO2.

[0070] (2) Li 1.6 Mn 1.6 O4@TiO2 and EDA were mixed at a solid-liquid ratio of 1 g: 200 mL to form a suspension. Lithium metal particles (TiO2:Li = 1:0.8) were rapidly added under ice bath conditions. The mixture was then transferred to a room temperature environment under a nitrogen atmosphere and stirred for 36 h. After the reaction was complete, the mixture was filtered, washed with deionized water, dried in a vacuum oven, and then dispersed in 0.2 mol / L dilute hydrochloric acid. The mixture was stirred at room temperature for 15 h, filtered, washed, and then dried under vacuum at 60 °C to obtain Li. 1.6 Mn 1.6 O4@selective reduction of TiO2.

[0071] (3) A 1.5cm square silica substrate was washed three times with deionized water and dried. It was then treated with O2 plasma for 40s at 60Hz, 150W, and a flow rate of 40cc / min to obtain surface-hydroxylated silica. Li... 1.6 Mn1.6 The O4@selective reduction TiO2 ion sieve was ultrasonically prepared in anhydrous ethanol to form a 4 g / L suspension. 0.4 mL of the suspension was then dropped onto a hydroxylated silica substrate and reacted with microwave irradiation at 700 W for 1 min to obtain the supported ion sieve adsorbent.

[0072] Example 4

[0073] The only difference between this embodiment and Embodiment 1 is that the mass ratio of the manganese-based ion sieve precursor and the titanium source in step (1) is 1:0.05. All other conditions and parameters are exactly the same as in Embodiment 1.

[0074] Example 5

[0075] The only difference between this embodiment and Embodiment 1 is that the mass ratio of the manganese-based ion sieve precursor and the titanium source in step (1) is 1:0.2. All other conditions and parameters are exactly the same as in Embodiment 1.

[0076] Example 6

[0077] The only difference between this embodiment and Embodiment 1 is that the molar ratio of phosphate in the phosphate and titanium in the titanium source in step (1) is 0.2:100. All other conditions and parameters are exactly the same as in Embodiment 1.

[0078] Example 7

[0079] The only difference between this embodiment and Embodiment 1 is that the molar ratio of phosphate in the phosphate and titanium in the titanium source in step (1) is 1.5:100. All other conditions and parameters are exactly the same as in Embodiment 1.

[0080] Example 8

[0081] The only difference between this embodiment and Embodiment 1 is that the molar ratio of titanium to lithium in the titanium dioxide-coated manganese ion sieve precursor in step (2) is 1:0.5. All other conditions and parameters are exactly the same as in Embodiment 1.

[0082] Example 9

[0083] The only difference between this embodiment and embodiment 1 is that the molar ratio of titanium to lithium in the titanium dioxide-coated manganese ion sieve precursor in step (2) is 1:1.5. All other conditions and parameters are exactly the same as in embodiment 1.

[0084] Example 10

[0085] The only difference between this embodiment and Embodiment 1 is that the concentration of the suspension in step (3) is 1 g / L, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0086] Example 11

[0087] The only difference between this embodiment and Embodiment 1 is that the concentration of the suspension in step (3) is 5 g / L, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0088] Comparative Example 1

[0089] This comparative example provides a supported ion sieve adsorbent, and the preparation method of the supported ion sieve adsorbent is as follows:

[0090] (1) Weigh lithium chloride and manganese nitrate and prepare a mixed solution with a Li / Mn ratio of 0.6, wherein the concentration of lithium ions is 2 mol / L, and stir evenly for 30 min;

[0091] (2) Take a 1.5cm square silica substrate, clean it in an ultrasonic bath for 30 minutes, wash it with deionized water, and dry it in an oven for 10 hours. Then immerse it in the mixed solution prepared in step (1) for 3 hours, take it out and dry it in an oven at 120℃ for 3 hours, and calcine it at 450℃ in air atmosphere for 8 hours to obtain a silica ion sieve loaded with LiMn2O4;

[0092] (3) The supported ion sieve was acid-washed with 0.3 mol / L dilute hydrochloric acid solution and dried under vacuum overnight at 60°C to obtain the supported ion sieve adsorbent.

[0093] Comparative Example 2

[0094] This comparative example provides a supported ion sieve adsorbent, and the preparation method of the supported ion sieve adsorbent is as follows:

[0095] (1) Add 2 mL of 35% ammonia to 50 mL of anhydrous ethanol, then add 4 g of tetrabutyl titanate, 0.3 g of triethanolamine, potassium phosphate, phosphate, and Ti. 4+ The molar ratio of the two components was 0.8%. After uniform stirring for 15 min, the manganese-based ion sieve precursor LiMn2O4 was added. The mass ratio of the manganese-based ion sieve precursor to the titanium source was 1:0.1. The mixture was heated to 50℃ and stirred vigorously to form a colloid. It was then aged in an oven at 65℃ for 30 h, and then calcined in a muffle furnace at 500℃ for 6 h. It was washed repeatedly with deionized water and distilled water 3-4 times, and dried overnight at 65℃ to obtain titanium dioxide-coated manganese-based ion sieve precursor LiMn2O4@TiO2. It was then dispersed in a 0.3 mol / L dilute hydrochloric acid solution and stirred at room temperature for 14 h. After that, it was taken out, filtered and washed until the pH of the washing solution was neutral. It was then dried under vacuum overnight at 60℃ to obtain HMn2O4@TiO2 ion sieve.

[0096] (2) Take a square silica substrate with a length of 1.5cm, wash it three times with deionized water and dry it. Then treat it with O2 plasma for 30s to obtain surface hydroxylated silica.

[0097] (3) The HMn2O4@TiO2 ion sieve was placed in anhydrous ethanol and sonicated to form a 3 mg / mL suspension. 0.5 mL of the suspension was taken out and dropped onto the hydroxylated silica substrate. The substrate was irradiated with microwave power of 600 W for 2 min to obtain the supported ion sieve adsorbent.

[0098] Performance testing:

[0099] 1. Adsorption capacity test: Weigh the supported ion sieves prepared in the above examples and comparative examples and disperse them in a lithium-containing solution (Li). + The concentration was 100 mg / L, the solid-liquid ratio was 1:100, and the solution was placed on a constant temperature shaker (150 r / min) at 25℃ for 14 h for adsorption. The lithium ion content in the solution was measured, and the adsorption amount was calculated using the formula shown below:

[0100]

[0101] Q e (mg / g) represents the equilibrium adsorption capacity, C0 and C e Li + The initial and equilibrium concentrations (mg / L) are given, V(L) is the volume of the mixed solution, and m(g) is the mass of the ion sieve adsorbent (the mass of the silica substrate after loading the ion sieve minus the mass of the silica substrate).

[0102] 2. Manganese dissolution rate test: The ion sieve adsorbent was placed in 200 mL of 0.5 mol / L HCl solution and stirred continuously at 300 r / min for 12 h at room temperature. The manganese dissolution loss of the lithium adsorbent during the acid washing treatment was measured. The Mn dissolution loss rate was calculated using the following formula:

[0103]

[0104] Where R Mn V3 represents the dissolution rate of manganese ions, and V3 represents the volume of the solution (L). Mn (mg / L) represents the concentration of manganese ions in the solution, m Mn (mg) represents the total amount of manganese in the adsorbent.

[0105] 3. Adsorption capacity retention test: The above adsorption-acid washing step was repeated 5 times. Acid washing was performed by desorbing the adsorbed lithium ion sieve with 0.5 mol / L HCl in a constant temperature shaker at 25℃ (150 r / min) for 8 h. The adsorption capacity obtained after the fifth cycle was measured as a percentage of the first cycle adsorption capacity. The test results are shown in Table 1.

[0106] Table 1

[0107]

[0108]

[0109] As shown in Table 1, based on Examples 1-3, different supported manganese-based ion sieves all exhibited good lithium extraction performance, especially in terms of adsorption capacity and adsorption capacity retention. Example 3 showed the highest adsorption capacity at 27.58 mg / g because its ion sieve precursor to titanium source mass ratio of 1:0.08 was relatively low, resulting in a high proportion of active material in the ion sieve and excellent adsorption performance. Conversely, a low proportion of titanium source led to a thinner titanium dioxide coating, making it prone to manganese dissolution and resulting in poor cycling performance.

[0110] A comparison of Examples 1 and 4-5 shows that the mass ratio of the manganese-based ion sieve precursor to the titanium source affects the performance of the supported ion sieve adsorbent described in this invention. Controlling the mass ratio of the manganese-based ion sieve precursor to the titanium source to 1:0.08–0.15 yields a better-performing supported ion sieve adsorbent. If the amount of titanium source introduced is too high, the proportion of active material is low, resulting in a lower adsorption capacity of the ion sieve. Conversely, if the amount of titanium source introduced is too low, the coating layer thickness is low, the manganese dissolution rate is high, and the adsorption capacity retention rate is low.

[0111] A comparison of Examples 1 and 6-7 shows that the molar ratio of phosphate in the phosphate to titanium in the titanium source affects the performance of the supported ion sieve adsorbent described in this invention. Controlling the molar ratio of phosphate in the phosphate to titanium in the titanium source to (0.4-1.3):100 results in a better performance of the supported ion sieve adsorbent. If too much phosphate is introduced, it can easily affect the crystallinity of titanium dioxide and the coating effect. If too little phosphate is introduced, it is insufficient to simultaneously form rutile and anatase phases in titanium dioxide, and selective reduction will naturally be impossible in the later stages.

[0112] A comparison of Examples 1 and 8-9 shows that, in the preparation process of the supported ion sieve adsorbent of the present invention, the molar ratio of titanium to lithium in the titanium dioxide-coated manganese ion sieve precursor affects its performance. Controlling the molar ratio of titanium to lithium in the titanium dioxide-coated manganese ion sieve precursor at 1:(0.8-1.2) yields a supported ion sieve adsorbent with better performance. If too much lithium is introduced, it will be wasteful; if too little lithium is introduced, it will not be enough to completely convert the rutile phase into an amorphous state and generate enough Ti-OH to be loaded on the silica.

[0113] A comparison of Examples 1 and 10-11 shows that the concentration of the suspension affects the performance of the supported ion sieve adsorbent described in this invention. Controlling the suspension concentration at 2-4 g / L yields a better performance of the supported ion sieve adsorbent. If the suspension concentration is too high, the ion sieve fails to properly load onto the substrate, resulting in a thicker loading layer, higher manganese dissolution rate, and lower adsorption capacity retention. Conversely, if the suspension concentration is too low, the ion sieve can fully react and load onto the substrate, resulting in a higher cycle capacity retention.

[0114] Comparing Example 1 and Comparative Example 1, it can be seen that without titanium dioxide as a coating layer intermediate for loading, the distortion and dissolution of manganese cannot be suppressed, resulting in a high manganese loss rate of the ion sieve after 5 cycles and an adsorption capacity of only 82.35%.

[0115] As can be seen from the comparison between Example 1 and Comparative Example 2, without selective reduction modification of titanium dioxide, the suspension was directly prepared and microwave-loaded onto silicon dioxide. Due to the lack of reactive chemical bonds, the ion sieve could not be fully loaded onto the substrate, resulting in severe losses. The adsorption capacity, manganese dissolution, and cycle capacity retention all showed mediocre performance.

[0116] XPS was performed on the following three stages of products (TiO2, selectively reduced TiO2, and selectively reduced TiO2 loaded onto the hydroxylated silica interface), and the test results are as follows: Figure 2 As shown:

[0117] (1) Take 50 ml of anhydrous ethanol, add 2 mL of 35% ammonia, 4 g of tetrabutyl titanate, 0.3 g of triethanolamine, potassium phosphate, phosphate, and Ti. 4+ The molar ratio was 0.8%. The mixture was heated to 50°C and stirred vigorously to form a colloid. It was then aged in an oven at 65°C for 24 hours, followed by calcination in a muffle furnace at 500°C for 6 hours. After washing, it was dried at 65°C overnight to obtain TiO2.

[0118] (2) TiO2 and anhydrous ethylenediamine were mixed in a solid-liquid ratio of 1 g: 200 mL to form a suspension. Lithium metal particles were rapidly added under ice bath conditions, with a Ti / Li ratio of 0.8. The mixture was transferred to room temperature and stirred under a nitrogen atmosphere for 40 h. After the reaction was completed, the mixture was filtered, washed, and dried in a vacuum oven at 65 °C to obtain selectively reduced TiO2.

[0119] (3) Selectively reduced TiO2 was placed in anhydrous ethanol and sonicated to form a 3 mg / mL suspension. 0.5 mL of the suspension was taken out and dispersed on a hydroxylated silica substrate and microwaved at 600 W for 2 min.

[0120] The titanium dioxide-coated manganese-based ion sieve precursor obtained during the preparation of the supported ion sieve adsorbent described in Example 1 was subjected to XRD testing. The test results are as follows: Figure 3 As shown, combined with Figure 2-3 It can be seen that the introduction of phosphate groups into TiO2 coated in situ by manganese-based ion sieves results in the TiO2 coating layer simultaneously possessing rutile and anatase phases. Selective reduction of the TiO2 containing both rutile and anatase phases causes the rutile phase to disappear, replaced by an amorphous Ti-OH groups. Under microwave irradiation, the hydroxylated silica and Ti-OH groups form covalent bonds Ti-O-Si, tightly loaded onto the support.

[0121] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a supported ion sieve adsorbent, characterized in that, The preparation method includes the following steps: (1) Mix titanium source, ammonia, triethanolamine and phosphate with the first solvent, add manganese ion sieve precursor, heat treatment to obtain gel, calcine the gel to obtain titanium dioxide coated manganese ion sieve precursor. (2) The titanium dioxide-coated manganese ion sieve precursor is dispersed in ethylenediamine to form a first suspension. After adding elemental lithium, the mixture is stirred and reacted to obtain a selectively reduced titanium dioxide-coated manganese ion sieve. (3) The selectively reduced titanium dioxide coated manganese ion sieve is mixed with a second solvent to obtain a second suspension. The second suspension is dropped onto the surface of the hydroxylated modified silica support and then irradiated with microwave to obtain the supported ion sieve adsorbent.

2. The preparation method according to claim 1, characterized in that, The titanium source in step (1) includes tetrabutyl titanate and / or isopropyl titanate.

3. The preparation method according to claim 1, characterized in that, The mass ratio of the titanium source and triethanolamine in step (1) is (10~30):

1.

4. The preparation method according to claim 1, characterized in that, The molar ratio of phosphate in the phosphate and titanium in the titanium source in step (1) is (0.4~1.3):

100.

5. The preparation method according to claim 1, characterized in that, Step (1) The first solvent includes anhydrous ethanol.

6. The preparation method according to claim 1, characterized in that, The manganese-based ion sieve precursor in step (1) includes LiMn2O4 and Li 1.33 Mn 1.67 O4 or Li 1.6 Mn 1.6 Any one or at least two of O4.

7. The preparation method according to claim 1, characterized in that, The mass ratio of the manganese-based ion sieve precursor to the titanium source in step (1) is 1:(0.05~0.2).

8. The preparation method according to claim 7, characterized in that, The mass ratio of the manganese-based ion sieve precursor to the titanium source in step (1) is 1:(0.08~0.15).

9. The preparation method according to claim 1, characterized in that, The heat treatment in step (1) includes heating and stirring and heating and aging.

10. The preparation method according to claim 9, characterized in that, The heating and stirring temperature is 40~60℃.

11. The preparation method according to claim 9, characterized in that, The heating and aging temperature is 65~85℃.

12. The preparation method according to claim 9, characterized in that, The heating and aging time is 18~36 hours.

13. The preparation method according to claim 1, characterized in that, The calcination temperature in step (1) is 500~700℃.

14. The preparation method according to claim 1, characterized in that, The calcination process in step (1) takes 6 to 8 hours.

15. The preparation method according to claim 1, characterized in that, After the calcination treatment described in step (1), the product is washed and dried.

16. The preparation method according to claim 15, characterized in that, The detergent used for washing includes deionized water and / or distilled water.

17. The preparation method according to claim 15, characterized in that, The washing process is performed 3 to 4 times.

18. The preparation method according to claim 15, characterized in that, The drying time is 6-12 hours.

19. The preparation method according to claim 1, characterized in that, The condition for adding elemental lithium in step (2) is an ice bath.

20. The preparation method according to claim 1, characterized in that, In step (2), the molar ratio of titanium to lithium in the titanium dioxide-coated manganese ion sieve precursor is 1:(0.8~1.2).

21. The preparation method according to claim 1, characterized in that, The stirring reaction time in step (2) is 36~48h.

22. The preparation method according to claim 1, characterized in that, After the stirring reaction described in step (2), the mixture is filtered, washed with water, dried, and acid-soaked.

23. The preparation method according to claim 22, characterized in that, The acid solution used for the acid leaching treatment includes 0.2~1 mol / L hydrochloric acid.

24. The preparation method according to claim 22, characterized in that, The acid leaching treatment time is 8-15 hours.

25. The preparation method according to claim 1, characterized in that, Step (3) The second solvent includes anhydrous ethanol.

26. The preparation method according to claim 1, characterized in that, Step (3) involves ultrasonic treatment after mixing.

27. The preparation method according to claim 26, characterized in that, The ultrasonic treatment time is 30-60 minutes.

28. The preparation method according to claim 1, characterized in that, The concentration of the suspension in step (3) is 1~5 g / L.

29. The preparation method according to claim 28, characterized in that, The concentration of the suspension in step (3) is 2~4 g / L.

30. The preparation method according to claim 1, characterized in that, The hydroxylation modification process in step (3) includes plasma treatment of the silica support.

31. The preparation method according to claim 30, characterized in that, The silica carrier includes any one or a combination of at least two of the following: silica substrate, silica base plate, or porous silica tube.

32. The preparation method according to claim 30, characterized in that, The plasma treatment frequency is 50~60Hz.

33. The preparation method according to claim 30, characterized in that, The power of the plasma treatment is 150~250W.

34. The preparation method according to claim 30, characterized in that, The oxygen flow rate for plasma treatment is 40~60cc / min.

35. The preparation method according to claim 1, characterized in that, The power of microwave irradiation in step (3) is 500~700W.

36. The preparation method according to claim 1, characterized in that, The microwave irradiation time in step (3) is 1~5 min.

37. A supported ion sieve adsorbent, characterized in that, The supported ion sieve adsorbent is prepared by the preparation method according to any one of claims 1-36.

38. An application of the supported ion sieve adsorbent as described in claim 37, characterized in that, The supported ion sieve adsorbent is used for lithium extraction from salt lakes.

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