Composite manganese lithium ion sieve, preparation method and application thereof

Abstract

The application discloses a composite manganese lithium ion sieve, a preparation method and application thereof, and the preparation method comprises the following steps: S1, reacting corn straw pith in a first solution, and obtaining a first product after removing lignin; S2, configuring a second solution containing lithium ions and manganese ions, immersing the first product in the second solution, separating and drying solid matters after a period of time, and obtaining a second product; and S3, calcining the second product in an inert atmosphere, and obtaining the composite manganese lithium ion sieve. The corn straw is used as one of preparation raw materials, the yield of the corn straw is huge, the raw material is convenient to obtain, is not limited by regions and seasons, can realize large-scale stable supply, and can significantly reduce production cost.

Description

TECHNICAL FIELD

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

[0002] In recent years, the rapid development of new energy vehicles, portable electronic devices and large-scale energy storage systems has led to an explosive growth in the market demand for lithium ion batteries. However, the global lithium resource reserves are limited and unevenly distributed, and the traditional lithium ore mining efficiency is low and the cost is high, which leads to a continuous shortage of lithium ion supply. The rapid growth of lithium demand has made the existing lithium resource supply system difficult to meet the demand of the rapid development of the industry, and the shortage of lithium resources has become an important bottleneck restricting the development of the global new energy industry.

[0003] Salt lake brine contains rich lithium resources, accounting for more than 60% of the total global lithium resources, so the lithium extraction technology from salt lake has become the core direction to alleviate the shortage of lithium resources. Compared with solid lithium ore lithium extraction, lithium extraction from salt lake has the advantages of large resource reserves, low production cost and environmental friendliness. Through efficient lithium extraction technology from salt lake, lithium ions in brine can be converted into high-purity lithium products, which has important strategic significance for ensuring the stable supply of global lithium resources and promoting the sustainable development of the new energy industry. However, the current lithium extraction technology from salt lake still faces many challenges, especially the performance of the adsorbent directly affects the lithium extraction efficiency and product quality, and it is urgent to develop high-performance adsorbent materials.

[0004] Existing lithium extraction adsorbents from salt lake, such as inorganic adsorbents, organic adsorbents and composite material adsorbents, have certain limitations in practical application. The inorganic adsorbent has insufficient selectivity, the organic adsorbent has poor stability, and the composite material adsorbent has a complex preparation process. Manganese-based adsorbents have great potential in the field of lithium extraction from salt lake due to their unique ion exchange performance, high selectivity and good chemical stability. Research on manganese-based adsorbents can not only effectively reduce the magnesium-lithium ratio in brine and improve the purity of lithium extraction, but also adapt to complex salt lake brine systems, improve adsorption efficiency and cyclic performance. In addition, manganese ore resources are abundant and low in cost, and research on manganese-based adsorbents can help reduce the production cost of lithium extraction from salt lake and realize efficient and economical extraction of lithium resources. Therefore, the research on manganese-based adsorbents has important practical significance and necessity for breaking through the bottleneck of existing lithium extraction technology from salt lake and promoting the development of lithium resource industry. SUMMARY

[0005] The purpose of the present 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.

[0006] To achieve the above object, the technical scheme adopted by the present application is to provide a preparation method of a composite manganese 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: configuring 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 lithium ion sieve.

[0007] As a preferred, the first solution is a mixed solution of alkali and oxidizing agent, and the first solution is used to remove lignin in the corn straw pith.

[0008] As another preferred, the alkali is NaOH, KOH or Na2CO3, and the concentration of the alkali in the first solution is 2-10 wt%; the oxidizing agent is H2O2 or Na2SO3.

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

[0010] As another preferred, the corn straw pith and the first solution are reacted under heating, the reaction temperature is 80-100 ℃, and the reaction time is 2-6 hours.

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

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

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

[0014] The present application also provides a manganese lithium ion sieve, which is prepared by using corn straw pith carbide as a carrier and loading lithium manganese oxide on the carrier.

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

[0016] Compared with the prior art, the present application has the beneficial effects that:

[0017] (1) The corn straw is used as one of the raw materials for preparation, the yield of the corn straw is huge, the raw material is easy to obtain, is not limited by region and season, can realize large-scale stable supply, and significantly reduces the production cost;

[0018] (2) The composite manganese adsorbent prepared in the application has high performance and stable structure, can quickly extract lithium ions in brine and realize low solution loss, and has great market application potential;

[0019] (3) The corn straw pith is carbonized in the application, forming a through three-dimensional macroporous channel, significantly improving the mass transfer efficiency and reducing the adsorption of magnesium ions. DETAILED DESCRIPTION

[0020] In the following, the application will be further described in conjunction with specific embodiments, and it should be noted that the embodiments described below or the technical features between the embodiments can be combined in any manner to form new embodiments without conflict.

[0021] The terms "comprise" and "have" and any variation thereof in the specification and claims of the application are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units does not have to be limited to the clearly listed steps or units, but can include other steps or units that are not clearly listed or inherent to the process, method, product or device.

[0022] The application provides a preparation method of a composite manganese lithium ion sieve, comprising the following preparation steps:

[0023] S1: reacting the corn straw pith in a first solution to obtain a first product after removing lignin;

[0024] S2: preparing a second solution containing lithium ions and manganese ions, immersing the first product in the second solution, and obtaining a second product after separation and drying;

[0025] S3: calcining the second product under an inert atmosphere to obtain a composite manganese lithium ion sieve.

[0026] The corn straw is used as one of the raw materials for preparation, the yield of the corn straw is huge, the raw material is easy to obtain, is not limited by region and season, can realize large-scale stable supply. The corn straw is usually regarded as agricultural waste, and even needs additional cost for treatment. Using the corn straw as one of the reaction raw materials can greatly reduce the initial cost of material preparation.

[0027] In addition, corn stalks are natural biomass materials that can be naturally degraded after being discarded, reducing the burden on the environment. Converting agricultural waste into high-value adsorption materials realizes the transformation of waste into treasure, reduces air pollution caused by straw burning and land resource waste caused by landfill, and provides a new way for the resource utilization of agricultural waste.

[0028] In some embodiments, the first solution is a mixed solution of alkali and oxidizing agent, and the corn stalk pith is completely soaked in the first solution to remove lignin through high-temperature reaction and retain the cellulose skeleton.

[0029] In some preferred embodiments, the alkali can be NaOH, KOH or Na2CO3, and the concentration of the alkali in the first solution is 2-10 wt%.

[0030] In some preferred embodiments, the oxidizing agent is H2O2 or Na2SO3.

[0031] In some embodiments, the corn stalk pith is crushed into 1-5 mm particles, and the granular corn stalk pith can increase the contact area with the first solution, making the reaction more complete and the lignin removal more thorough.

[0032] In some embodiments, the amount of corn stalk pith added is 5-10% of the mass of the first solution. An excess of the first solution needs to be added to the crushed corn stalk pith to ensure that the lignin in the corn stalk pith is completely removed.

[0033] In some embodiments, the crushed corn stalk pith is soaked in the first solution, heated to 80-100°C and maintained for 2-6 hours to further ensure the reaction effect.

[0034] The corn stalk pith can form natural mesopores of 2-50 nm and micropores of <2 nm at the same time as the lignin is removed, and the specific surface area can be expanded to 400-800 m 2 / g, which is suitable for subsequent doping of lithium ions and manganese ions.

[0035] 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 accurately controlled to preferably form spinel-like manganese-based lithium ion sieves.

[0036] 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, and doping other metal ions into the lithium manganate lattice can increase the lattice strength of the material, reduce manganese loss while improving adsorption capacity and adsorption rate.

[0037] In some embodiments, in the S2 step, the first product is immersed in the second solution and assisted by ultrasonic to make lithium ions and manganese ions penetrate into the cellulose skeleton. Preferably, the ultrasonic time is 30-120 minutes. Through the ultrasonic-assisted immersion process, the ion penetration rate is further improved, the uniformity of the distribution of lithium and manganese ions in the carrier is improved, and the adsorption is improved.

[0038] In some embodiments, the second product is calcined under an inert atmosphere, the calcination temperature is 300-600 ℃, and the calcination time is 12-36 hours.

[0039] The corn straw pith has a natural loose honeycomb structure with a pore size of about 50-300 µm. After the second product containing the corn straw pith skeleton is calcined and carbonized, a through three-dimensional macroporous channel is formed, significantly improving the mass transfer efficiency. The permeability of the carbonized corn straw pith material is 3-5 times higher than that of traditional activated carbon, and is more suitable for dynamically adsorbing Li + .

[0040] In addition, the carbonized corn straw pith forms a through three-dimensional macroporous channel and a pore size distribution of mesoporous and microporous structures, which blocks magnesium ions outside the pore channel. 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.

[0041] The preparation method of the present application has environmentally friendly, cheap and easily available raw materials, which can greatly reduce the production cost, the preparation steps are simple and easy to understand, no additional reaction equipment needs to be purchased, the reaction temperature is low, and the safety is high.

[0042] The present application provides a composite manganese-based lithium ion sieve, in which corn straw pith carbonide is used as a carrier, and lithium manganese oxide is loaded on the carrier, which can be represented as LiMn2O4@C.

[0043] The present application also provides a composite manganese-based lithium ion adsorbent, which is obtained by acidizing the above-mentioned composite manganese-based lithium ion sieve and can be used for adsorbing lithium ions, and is particularly suitable for lithium extraction from salt lakes.

[0044] The composite manganese-based lithium ion adsorbent provided by the present application has good lithium ion adsorption and structural stability, and can maintain good adsorption effect and low dissolution loss rate after multiple uses, and is suitable for large-scale promotion in lithium extraction from salt lakes.

[0045] The composite manganese-based lithium ion adsorbent of the present application has multi-dimensional advantages in raw materials, process and performance, not only provides a feasible technical solution to alleviate the global lithium resource shortage, but also sets an example for green and low-carbon development through resource utilization of agricultural waste. The large-scale application of the composite manganese-based lithium ion adsorbent in the fields of lithium extraction from salt lakes and resource recycling will effectively promote the sustainable development of the new energy industry.

[0046] Example 1

[0047] A composite manganese lithium ion sieve is prepared according to the following method:

[0048] S1: The recycled waste corn straw is crushed to about 3 mm, 5% NaOH and 3% H2O2 solution are mixed uniformly to prepare a first solution, the crushed corn straw is completely immersed in the first solution, heated to 90 DEG C and reacted for 4 hours to remove lignin and retain the cellulose skeleton, the solid is washed with deionized water to neutral, filtered and dried to obtain a first product;

[0049] S2: 1 mmol LiNO3 and 2 mmol Mn(NO3)2 are dissolved in 50 mL deionized water to prepare a second solution, 25 g of the first product is dispersed in the second solution, and the mixture is mixed by ultrasonic for 30 min, the product is separated and vacuum dried to obtain a second product;

[0050] S3: The second product is heated to 500 DEG C at a heating rate of 5 DEG C / min under a nitrogen atmosphere, and then held at 500 DEG C for 16 hours to obtain LiMn2O4@C.

[0051] Activation step: the composite manganese lithium ion sieve is activated by acid immersion with 500 mL of 0.05 mol / L hydrochloric acid, and 4 mol / L HCl solution is added dropwise to the activation solution, and the pH is maintained at about 1.25 for 1 h, and the composite manganese adsorbent is obtained by washing.

[0052] Example 2

[0053] The nitrogen is replaced by helium, and the other preparation steps are consistent with the preparation steps in Example 1.

[0054] Example 3

[0055] The 5% NaOH is replaced by 5% KOH to prepare the first solution, and the other preparation steps are consistent with the preparation steps in Example 1.

[0056] Example 4

[0057] 1 mmol LiNO3, 1.5 mmol Mn(NO3)2 and 0.5 mmol Co(NO3)2 are dissolved in 50 mL deionized water to prepare a second solution, and the other preparation steps are consistent with the preparation steps in Example 1.

[0058] Example 5

[0059] Dissolve 1 mmol LiNO3 and 1.5 mmol Mn(NO3)2 and 0.5 mmol Ni(NO3)2 in 50 mL deionized water to configure a second solution, and other preparation steps remain the same as in Example 1.

[0060] Comparative Example 1

[0061] Dissolve 1 mmol LiNO3 and 2 mmol Mn(NO3)2 by high-speed mixing, and then heat to 300°C at a heating rate of 5°C / min under a nitrogen atmosphere, and then heat to 500°C at a heating rate of 5°C / min under a nitrogen atmosphere after holding at 300°C for 6 hours, to obtain the adsorbent material of Comparative Example 1.

[0062] Comparative Example 2

[0063] Replace the corn straw in Example 1 with rice husk which is less expensive as a template, and other preparation steps remain the same as in Example 1.

[0064] Performance Test

[0065] After the activated composite manganese adsorbent material is placed in 1 L of raw brine (Dongtai brine) and stirred for static adsorption for 1.5 h, it is then filtered and washed, and then immersed in 500 mL of 0.05 mol / L hydrochloric acid, and then 4 mol / L HCl solution is added dropwise to maintain a pH of about 1.25, and then activated desorption is performed for 10 min, and then the cycle is repeated to the 5th cycle, and then the adsorption and desorption are stable, and then the saturated adsorption capacity is tested, and the relevant calculation formula is as follows:

[0066] Adsorption capacity = (c 卤水Li -c 尾液Li ) × V 卤水 / m 吸附剂

[0067] Desorption capacity = c 解吸液Li × V 解吸液 / m 吸附剂

[0068] Dissolution loss rate = c 解吸液Li × V 解吸液 / (m 吸附剂 × 0.522) × 100%

[0069] c 卤水Li -- Li concentration in brine, g / L

[0070] c 尾液Li -- Li concentration in adsorption tail liquid, g / L

[0071] V 卤水 -- Brine volume, L

[0072] m 吸附剂Adsorbent mass, g

[0073] c 解吸液Li Desorption solution Li concentration, g / L

[0074] V 解吸液 Desorption solution volume, L

[0075] The adsorption test results and average solution loss rate calculation results of Examples 1-5 and Comparative Examples 1-2 are recorded in Table 1 below.

[0076] Table 1: Adsorption performance test results of each example and each comparative example

[0077]

[0078] Analyzing the performance test results of Example 1 and Example 2, different inert gas calcination has little effect on the performance of the composite manganese-based adsorbent. The preparation process of the present application is stable.

[0079] Analyzing the performance test results of Example 1 and Example 3, the sodium hydroxide solution and the oxidizing agent are configured into the first solution, and the prepared composite manganese-based adsorbent has better adsorption performance. It is speculated that the first solution configured has better lignin removal effect, providing more adsorption sites.

[0080] Analyzing the performance test results of Example 1 and Example 4, in addition to adding lithium salt and manganese salt in the second solution, additional soluble metal salt is added, which can further improve the adsorption performance of the composite manganese-based adsorbent. The adsorption performance of the adsorbent is obviously better than the control group without adding soluble metal salt, the lithium-magnesium ratio is enhanced, and the average solution loss rate is reduced.

[0081] Analyzing the performance test results of Example 4 and Example 5, in addition to lithium salt and manganese salt, the effect of adding cobalt salt is better than adding nickel salt, and higher adsorption performance is reflected in larger adsorption capacity, higher lithium-magnesium ratio and lower 5-round average solution loss rate. It may be related to the enhancement of cobalt ion lattice stability and optimization of ion exchange sites.

[0082] Analyzing the performance test results of Example 1 and Comparative Example 1, the composite manganese-based adsorbent prepared by the preparation method of the present application has better performance, the initial adsorption performance reaches 30 mg / g, which is about 1.6 times the initial adsorption performance of the adsorbent of Comparative Example 1, the lithium-magnesium ratio is increased by 136%, and the 5-round average solution loss rate is reduced by about 27%.

[0083] Analyzing the performance test results of Example 1 and Comparative Example 2, Comparative Example 2 also uses an organic carbon source. It is speculated that the pore structure of rice husk is uneven and the specific surface area is low, which leads to a decrease in mass transfer efficiency and low adsorption performance.

[0084] In summary, the composite manganese adsorbent prepared in the application has high performance and stable structure, can quickly extract lithium ions in brine and achieve low solution loss, and has great market application potential.

[0085] The above describes the basic principles, main features and advantages of the application. Those skilled in the art should understand that the application is not limited to the above examples, and the above examples and descriptions in the specification are only the principles of the application. Without departing from the spirit and scope of the application, various changes and improvements can be made to the application, and these changes and improvements all fall within the scope of the claimed application. The scope of protection claimed by the 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 preparation steps include the following: S1: The corn stalk pith is reacted in a first solution to remove lignin and obtain a first product; the first solution is a mixed solution of alkali and oxidant, and the first solution is used to remove lignin from the corn stalk pith; S2: Prepare a second solution containing lithium ions and manganese ions, immerse the first product in the second solution, separate and dry the solid after a period of time to obtain the second product; S3: The second product is calcined in an inert atmosphere to obtain the composite manganese-based lithium ion sieve.

2. The preparation method according to claim 1, characterized in that, The alkali is NaOH, KOH, or Na2CO3, and the concentration of the alkali in the first solution is 2-10 wt%; the oxidant is H2O2 or Na2SO3.

3. The preparation method according to claim 1, characterized in that, In step S1, the corn stalk pith is crushed into 1-5 mm particles and then soaked in the first solution. The amount of corn stalk pith added is 5%-10% of the mass of the first solution.

4. The preparation method according to claim 1, characterized in that, The corn stalk pith reacts with the first solution under heating at a temperature of 80-100°C for 2-6 hours.

5. The preparation method according to claim 1, characterized in that, In the second solution, the molar ratio of lithium ions to manganese ions is (1~1.05):

2.

6. The preparation method according to claim 1, characterized in that, In step S3, the calcination temperature is 300~600 ℃ and the calcination time is 12~36 hours.

7. The preparation method according to any one of claims 1 to 6, characterized in that, Other soluble metal salts are also 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.

8. A composite manganese-based lithium ion sieve, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 7.

9. A manganese-based adsorbent, characterized in that, The composite manganese-based lithium ion sieve prepared by any one of the preparation methods described in claims 1 to 7 is obtained by acidification; or the composite manganese-based lithium ion sieve described in claim 8 is obtained by acidification.

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