Composite manganese lithium ion sieve, preparation method and application thereof

Abstract

The invention discloses a composite manganese lithium ion sieve, a preparation method and application thereof, and the preparation method comprises the following preparation steps: S1, reacting corn straw pith in a first solution, and removing lignin to obtain a first product; s2, preparing a second solution containing lithium ions and manganese ions, dipping the first product in the second solution, and separating and drying solids after a period of time to obtain a second product; and S3, calcining the second product in an inert atmosphere to obtain the composite manganese lithium ion sieve. The corn straw is used as one of the preparation raw materials, the yield of the corn straw is huge, the raw materials are convenient to obtain and are not limited by regions and seasons, large-scale stable supply can be achieved, and the production cost is remarkably reduced.

Description

Technical Field

[0001] The present application relates to the technical field of material synthesis, and in particular to a composite manganese-based lithium ion sieve, a preparation method and applications thereof. Background Art

[0002] In recent years, the rapid development of new energy vehicles, portable electronic devices, and large-scale energy storage systems has led to a surge in market demand for lithium-ion batteries. However, global lithium reserves are limited and unevenly distributed, and traditional lithium mining is inefficient and costly, leading to a persistent shortage of lithium-ion batteries. Despite the rapid growth in lithium demand, the existing lithium supply system is unable to meet the needs of the rapidly expanding industry, and lithium resource shortages have become a major bottleneck restricting the development of the global new energy industry.

[0003] Salt lake brines contain abundant lithium resources, accounting for over 60% of the world's total lithium resources. Therefore, salt lake lithium extraction technology has become a core direction for alleviating lithium resource shortages. Compared with lithium extraction from solid lithium ore, salt lake lithium extraction offers significant advantages, including large resource reserves, low production costs, and environmental friendliness. Efficient salt lake lithium extraction technology can convert lithium ions in brine into high-purity lithium products, which is of great strategic significance for ensuring a stable global supply of lithium resources and promoting the sustainable development of the new energy industry. However, salt lake lithium extraction technology still faces many challenges, especially the performance of the adsorbent, which directly affects the lithium extraction efficiency and product quality. There is an urgent need to develop high-performance adsorption materials.

[0004] Existing adsorbents for lithium extraction from salt lakes, such as inorganic adsorbents, organic adsorbents, and composite adsorbents, all have certain limitations in practical applications. Inorganic adsorbents lack selectivity, organic adsorbents have poor stability, and composite adsorbents have complex preparation processes. Manganese-based adsorbents, with their unique ion exchange properties, high selectivity, and good chemical stability, have shown great potential in the field of lithium extraction from salt lakes. Research on manganese-based adsorbents can not only effectively reduce the magnesium-to-lithium ratio in brine and improve the purity of lithium extraction, but also adapt to complex salt lake brine systems, improving adsorption efficiency and recycling performance. In addition, manganese ore resources are abundant and low-cost. Research on manganese-based adsorbents can help reduce the production cost of lithium extraction from salt lakes and achieve efficient and economical extraction of lithium resources. Therefore, conducting research on manganese-based adsorbents is of great practical significance and necessity for breaking through the existing technical bottlenecks of lithium extraction from salt lakes and promoting the development of the lithium resources industry. Summary of the Invention

[0005] The purpose of this application is to provide a new type of composite manganese-based lithium ion sieve, which is prepared from corn straw pith and has low cost and good adsorption properties.

[0006] To achieve the above objectives, the technical solution adopted in this application is: to provide a preparation method of a composite manganese-based lithium ion sieve, comprising the following preparation steps: S1: reacting corn straw pith in a first solution to obtain a first product after removing lignin; S2: preparing a second solution containing lithium ions and manganese ions, immersing the first product in the second solution, separating and drying the solid after a period of time to obtain a second product; S3: calcining the second product under an inert atmosphere to obtain the composite manganese-based lithium ion sieve.

[0007] Preferably, the first solution is a mixed solution of alkali and an oxidant, and the first solution is used to remove lignin from the corn straw pith.

[0008] As another preference, the base is NaOH, KOH or Na2CO3; the concentration of the base in the first solution is 2-10 wt%; and the oxidant is H2O2 or Na2SO3.

[0009] As another preferred embodiment, in step S1, the corn straw pith is crushed into 1-5 mm particles and then immersed in the first solution, and the amount of corn straw pith added is 5%-10% of the mass of the first solution.

[0010] As another preferred embodiment, the corn stalk pith reacts with the first solution under heating, the reaction temperature is 80-100° C., and the reaction time is 2-6 hours.

[0011] As another preference, in the second solution, the molar ratio of the lithium ions to the manganese ions is (1-1.05):2.

[0012] As another preferred embodiment, in step S3, the calcination temperature is 300-600° C., and the calcination time is 12-36 hours.

[0013] More preferably, other soluble metal salts are added to the second solution, and the other soluble transition metal salts are any one of aluminum salts, titanium salts, niobium salts, cobalt salts or nickel salts.

[0014] The present application also provides a manganese-based lithium ion sieve, which uses corn straw pith carbide as a carrier, and the carrier is loaded with lithium manganese oxide.

[0015] The present application also provides a manganese-based adsorbent, which is prepared by acidifying any of the above-described composite manganese-based lithium ion sieves.

[0016] Compared with the prior art, the present invention has the following advantages: (1) This application uses corn stalks as one of the raw materials for preparation. Corn stalks have a huge output and are easy to obtain. They are not restricted by region or season, and can achieve large-scale stable supply and significantly reduce production costs. (2) The composite manganese-based adsorbent prepared in this application has high performance and stable structure, can quickly extract lithium ions from brine and achieve low dissolution loss, and has great market application potential; (3) This application forms a three-dimensional macroporous channel by carbonizing the pith of corn straw, which significantly improves the mass transfer efficiency and reduces the adsorption of magnesium ions. DETAILED DESCRIPTION

[0017] Below, the present application is further described in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0018] The terms "comprises" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, product or apparatus.

[0019] The present application provides a method for preparing a composite manganese-based lithium ion sieve, comprising the following preparation steps: S1: reacting corn straw pith in a first solution to remove lignin to obtain a first product; S2: preparing a second solution containing lithium ions and manganese ions, immersing the first product in the second solution, separating and drying to obtain a second product; S3: calcining the second product under an inert atmosphere to obtain a composite manganese-based lithium ion sieve.

[0020] This application uses corn straw as one of the raw materials for the preparation. Corn straw is abundant in production, readily available, and not restricted by geography or season, enabling a large-scale and stable supply. Corn straw is often considered agricultural waste and even requires additional processing costs. Using corn straw as one of the reaction raw materials can significantly reduce the initial cost of material preparation.

[0021] Furthermore, corn straw is a natural biomass material that degrades naturally after disposal, reducing the burden on the environment. Converting agricultural waste into high-value-added adsorbent materials achieves the goal of "turning waste into treasure," reducing air pollution from straw burning and landfill waste, and providing a new avenue for the resourceful utilization of agricultural waste.

[0022] In some embodiments, the first solution is a mixed solution of alkali and an oxidant, and the corn stalk pith is completely immersed in the first solution to remove lignin through high-temperature reaction while retaining the cellulose skeleton.

[0023] In some preferred embodiments, the base may be NaOH, KOH or Na2CO3, and the concentration of the base in the first solution is 2-10 wt%.

[0024] In some preferred embodiments, the oxidizing agent is H2O2 or Na2SO3.

[0025] In some embodiments, the corn straw pith is crushed into 1-5 mm particles. The corn straw pith in a granular state can increase the contact area with the first solution, making the reaction more complete and the lignin removal more thorough.

[0026] In some embodiments, the amount of corn straw pith added is 5% to 10% of the mass of the first solution. An excess amount of the first solution needs to be added to the pulverized corn straw pith to ensure that the lignin in the corn straw pith is completely removed.

[0027] In some embodiments, the crushed corn stalk pith is immersed in the first solution, the temperature is raised to 80-100° C. and the reaction is maintained for 2-6 hours to further ensure the reaction effect.

[0028] Corn straw pith can simultaneously form natural 2-50 nm mesopores and <2 nm micropores while removing lignin, and expand the specific surface area to 400-800 m 2 / g, suitable for subsequent doping of lithium ions and manganese ions.

[0029] In the second solution, the molar ratio of lithium ions to manganese ions is (1-1.05):2, and the molar ratio of lithium to manganese is precisely controlled to preferably form a spinel-shaped manganese-based lithium ion sieve.

[0030] In some embodiments, other soluble metal salts, such as aluminum salts, titanium salts, niobium salts, cobalt salts, and nickel salts, can be added to the second solution. Doping other metal ions into the lithium manganese oxide lattice can improve the lattice strength of the material, reduce manganese dissolution loss, and increase the adsorption capacity and adsorption rate.

[0031] In some embodiments, in step S2, the first product is immersed in a second solution and ultrasonically assisted to allow the lithium and manganese ions to penetrate the cellulose backbone. Preferably, the ultrasonication time is 30 to 120 minutes. The ultrasonic-assisted impregnation process further improves ion permeability, thereby increasing the uniformity of the distribution of lithium and manganese ions in the carrier and improving adsorption.

[0032] In some embodiments, the second product is calcined under an inert atmosphere at a temperature of 300-600° C. for a time of 12-36 hours.

[0033] Corn straw pith has a naturally loose honeycomb structure with a pore size of approximately 50 to 300 µm. After calcining and carbonizing the second product containing the corn straw pith skeleton, a three-dimensional macroporous channel is formed, significantly improving mass transfer efficiency. The permeability of the carbonized corn straw pith material is 3 to 5 times higher than that of traditional activated carbon, making it more suitable for the dynamic adsorption of Li in salt lake brine. + .

[0034] In addition, the carbonization of corn straw pith forms a through three-dimensional macroporous channel and a mesoporous and microporous structure with a pore size distribution, which blocks magnesium ions outside the pores. The diffusion rate of magnesium ions is significantly lower than that of lithium ions, reducing the adsorption of magnesium ions and improving the lithium-magnesium ratio.

[0035] The preparation method of the present application uses environmentally friendly, cheap and easily available raw materials, which can greatly reduce production costs. The preparation steps are simple and easy to understand, no additional reaction equipment needs to be purchased, the reaction temperature is low, and safety is high.

[0036] The present application provides a composite manganese-based lithium ion sieve, using corn straw pith carbide as a carrier, on which lithium manganese oxide is loaded, which can be expressed as LiMn2O4@C.

[0037] The present application also provides a composite manganese-based lithium ion adsorbent, which is obtained by acidification of the composite manganese-based lithium ion sieve described above and can be used to adsorb lithium ions, and is particularly suitable for lithium extraction from salt lakes.

[0038] The composite manganese-based lithium ion adsorbent provided in the present application has good lithium ion adsorption and structural stability. It can still maintain a good adsorption effect and a low dissolution rate after multiple uses, and is suitable for large-scale promotion in lithium extraction from salt lakes.

[0039] The composite manganese-based lithium ion adsorbent of the present application has multi-dimensional advantages in raw materials, processes, and performance. It not only provides a practical technical solution to alleviate the global shortage of lithium resources, but also sets an example for green and low-carbon development through the resource utilization of agricultural waste. Its large-scale application in the fields of lithium extraction from salt lakes and resource recycling will effectively promote the sustainable development of the new energy industry.

[0040] Example 1 A composite manganese-based lithium ion sieve was prepared according to the following method: S1: Grind the recycled waste corn stalks into about 3 mm, mix 5% NaOH and 3% H2O2 solutions evenly to prepare a first solution, completely immerse the pulverized corn stalks in the first solution, heat to 90°C and react for 4 hours to remove lignin and retain the cellulose skeleton, wash the solid with deionized water until neutral, filter and dry to obtain the first product; S2: Dissolve 1 mmol LiNO3 and 2 mmol Mn(NO3)2 in 50 mL deionized water to prepare a second solution, disperse 25 g of the first product in the second solution, and mix them thoroughly by ultrasonication for 30 min. Separate the products and vacuum dry them to obtain the second product. S3: The second product was heated at a rate of 5 °C / min under nitrogen atmosphere, after being kept at 300 °C for 6 hours, to 500 °C and kept at this temperature for 16 hours to obtain LiMn2O4@C.

[0041] Activation step: The composite manganese-based lithium ion sieve was activated by acid leaching with 500 mL of 0.05 mol / L hydrochloric acid, and a 4 mol / L HCl solution was added dropwise to the activation solution, and the pH was maintained at about 1.25 for activation for 1 hour, and the composite manganese-based adsorbent was obtained by washing.

[0042] Example 2 Nitrogen was replaced by helium, and the other preparation steps were consistent with those in Example 1.

[0043] Example 3 The first solution was prepared by replacing 5% NaOH with 5% KOH, and the other preparation steps were consistent with those in Example 1.

[0044] Example 4 1 mmol LiNO3, 1.5 mmol Mn(NO3)2, and 0.5 mmol Co(NO3)2 were dissolved in 50 mL deionized water to prepare a second solution. The other preparation steps were consistent with those in Example 1.

[0045] Example 5 1 mmol LiNO3, 1.5 mmol Mn(NO3)2, and 0.5 mmol Ni(NO3)2 were dissolved in 50 mL deionized water to prepare a second solution. The other preparation steps were consistent with those in Example 1.

[0046] Comparative Example 1 1 mmol LiNO3 and 2 mmol Mn(NO3)2 were mixed in a high-speed mixer, and heated at a rate of 5°C / min under a nitrogen atmosphere. The mixture was kept at 300°C for 6 hours and then heated to 500°C for 16 hours to obtain the adsorption material of Comparative Example 1.

[0047] Comparative Example 2 The corn stalks in Example 1 were replaced with rice husks of lower cost as the template, and the other preparation steps were consistent with those in Example 1.

[0048] Performance Testing The activated composite manganese adsorbent material was placed in 1 L of original brine (Dongtai brine) and stirred for static adsorption for 1.5 h, then filtered and washed, and acid-leached with 500 mL of 0.05 mol / L hydrochloric acid. 4 mol / L HCl solution was added dropwise to maintain the pH at around 1.25 for activation and desorption for 10 min. After the cycle was repeated for the fifth time, the adsorption and desorption were stable, and the saturated adsorption capacity was tested. The relevant calculation formulas are as follows: Adsorption capacity = (c 卤水Li -c 尾液Li ) × V 卤水 / m 吸附剂 Desorption capacity = c 解吸液Li ×V 解吸液 / m 吸附剂 Dissolution rate = c 解吸液Li ×V 解吸液 / (m 吸附剂 ×0.522)×100% c 卤水Li ----Li concentration in brine, g / L c 尾液Li ----Li concentration in adsorption tail liquid, g / L V 卤水 ----Brine volume, L m 吸附剂 ----Mass of adsorbent, g c 解吸液Li ----Li concentration of desorption solution, g / L V 解吸液 ----Desorption liquid volume, L The adsorption test results and average dissolution rate calculation results of Examples 1 to 5 and Comparative Examples 1 to 2 are recorded in Table 1 below.

[0049] Table 1 Adsorption performance test results of each embodiment and each comparative example

[0050] Analysis of the performance test results of Example 1 and Example 2 shows that different inert gas calcinations have little effect on the performance of the composite manganese-based adsorbent, and the preparation process of the present application has strong stability.

[0051] Analysis of the performance test results of Example 1 and Example 3 shows that the composite manganese adsorbent prepared by configuring the sodium hydroxide solution and the oxidant into the first solution has better adsorption performance. It is speculated that the configured first solution has a better removal effect on lignin and provides more adsorption sites.

[0052] Analysis of the performance test results of Example 1 and Example 4 shows that in addition to adding lithium salt and manganese salt to the second solution, the additional addition of soluble metal salt can further improve the adsorption performance of the composite manganese-based adsorbent. The adsorption performance of the adsorbent is obviously better than that of the control group without adding soluble metal salt, the lithium-magnesium ratio is enhanced, and the average dissolution loss rate is reduced.

[0053] Analysis of the performance test results of Example 4 and Example 5 shows that, in addition to lithium salt and manganese salt, the effect of additionally adding cobalt salt is better than that of adding nickel salt. The higher adsorption performance is reflected in a larger adsorption capacity, a higher lithium-magnesium ratio and a lower average dissolution rate over 5 rounds, which may be related to the cobalt ions enhancing the lattice stability and optimizing the ion exchange sites.

[0054] Analysis of the performance test results of Example 1 and Comparative Example 1 shows that the composite manganese-based adsorbent prepared by the preparation method of the present application has better performance, with an initial adsorption performance of 30 mg / g, which is about 1.6 times the initial adsorption performance of the adsorbent in Comparative Example 1, an increase of 136% in the lithium-magnesium ratio, and a reduction of about 27% in the average dissolution loss rate over five rounds.

[0055] The performance test results of Example 1 and Comparative Example 2 were analyzed. Comparative Example 2 also used an organic carbon source. It was speculated that the uneven pore structure and low specific surface area of ​​the rice husk may lead to reduced mass transfer efficiency and low adsorption performance.

[0056] In summary, the composite manganese-based adsorbent prepared in this application has high performance and stable structure, can quickly extract lithium ions from brine and achieve low dissolution loss, and has great market application potential.

[0057] The above describes the basic principles, main features, and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-described embodiments. The above-described embodiments and the specification merely illustrate the principles of the present application. Various changes and improvements may be made to the present application without departing from the spirit and scope of the present application. These changes and improvements fall within the scope of the present application for which protection is sought. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a composite manganese-based lithium ion sieve, characterized in that: The method comprises the following preparation steps: S1: reacting corn straw pith in a first solution to remove lignin to obtain a first product; S2: preparing a second solution containing lithium ions and manganese ions, immersing the first product in the second solution, separating and drying the solid after a period of time to obtain a second product; S3: calcining the second product under an inert atmosphere to obtain the composite manganese-based lithium ion sieve.

2. The preparation method according to claim 1, wherein The first solution is a mixed solution of alkali and oxidant, and the first solution is used to remove lignin in the corn straw pith.

3. The preparation method according to claim 2, wherein The base is NaOH, KOH or Na2CO3, and the concentration of the base in the first solution is 2-10 wt%; the oxidant is H2O2 or Na2SO3.

4. The preparation method according to claim 1, wherein In step S1, the corn straw pith is crushed into 1-5 mm particles and then immersed in the first solution. The amount of corn straw pith added is 5%-10% of the mass of the first solution.

5. The preparation method according to claim 1, wherein The corn stalk pith reacts with the first solution under heating, the reaction temperature is 80-100° C., and the reaction time is 2-6 hours.

6. The preparation method according to claim 1, wherein In the second solution, the molar ratio of the lithium ions to the manganese ions is (1-1.05):

2.

7. The preparation method according to claim 1, wherein In step S3, the calcination temperature is 300-600° C., and the calcination time is 12-36 hours.

8. The preparation method according to any one of claims 1 to 7, wherein Other soluble metal salts are further added to the second solution, wherein the other soluble transition metal salts are any one of aluminum salts, titanium salts, niobium salts, cobalt salts or nickel salts.

9. A manganese-based lithium ion sieve, characterized in that: Corn stalk pith carbide is used as a carrier, and lithium manganese oxide is loaded on the carrier.

10. A manganese-based adsorbent, characterized in that: The composite manganese-based lithium ion sieve prepared by any one of the preparation methods of claims 1 to 8 is obtained by acidification; or the manganese-based lithium ion sieve according to claim 9 is obtained by acidification.

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