Carbon-coated lithium ion sieve and preparation method thereof

Abstract

The application discloses a kind of carbon-coated lithium ion sieve and preparation method thereof, comprising: lithium titanate is dispersed in bituminous solution, and mixed liquor is obtained;The mixed liquor is dried under vacuum condition, and precursor is obtained;The precursor is calcined, and carbon-coated lithium titanate composite material is obtained, after the carbon-coated lithium titanate composite material is pickled, centrifuged and dried, carbon-coated lithium ion sieve is obtained.Industrial waste garbage extract bituminous and lithium titanate are used as raw materials, carbon-coated lithium titanate composite material is prepared by simple high-temperature calcination, and carbon-coated lithium ion sieve is obtained by acid washing and separation. The outer layer of the ion sieve is composed of a porous carbon layer, which can provide a large number of active sites, promote the diffusion of lithium-containing brine, and facilitate lithium ion adsorption, thereby increasing the adsorption capacity. At the same time, the carbon layer protection can enhance the stability of lithium ion sieve, especially the acid resistance, reduce the solution loss, and facilitate the multiple cycle use of lithium ion sieve.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium extraction, in particular to a carbon-coated lithium ion sieve and a preparation method thereof. BACKGROUND

[0002] In recent years, with the rapid development of the new energy vehicle industry, the demand for lithium resources is increasing. Among them, salt lake lithium resources have attracted widespread attention due to their abundant reserves. However, the development of salt lake lithium is limited by the characteristics of high magnesium-lithium ratio in China. Therefore, the separation technology of Mg 2+ / Li + is attracting more and more attention.

[0003] The adsorption method is suitable for high magnesium-lithium ratio salt lake brine due to its simple process, green environment-friendly advantages, etc. In the process of extracting lithium, Li + is captured by an adsorbent with high lithium selectivity, and then through desorption, Li + is separated from other coexisting ions. Therefore, the adsorbent needs to have the following characteristics. First, the stability of the lithium adsorption material should be high, so that it can maintain the stability of the structure in the high salinity brine system and the strong acid elution system. Second, the selectivity of the lithium adsorption material should be high. The adsorbents currently used can be divided into aluminum salt adsorbents and lithium ion sieves. The aluminum salt adsorbent has high selectivity and large lithium adsorption capacity, and has been successfully applied to industrial production. However, due to the difficulty in separating and recycling the powder adsorbent, the preparation process is complicated in industrial application, and the adsorption performance is sharply reduced, which can only reach 4-6mg / g, and it is not suitable for alkaline salt lakes rich in hydroxide. Lithium ion sieves can be divided into two types according to their chemical composition: lithium manganese oxide type (LMO) and lithium titanium oxide type (LTO). LMO type ion sieve has the characteristics of high lithium adsorption capacity and good lithium selectivity, and is currently a popular selective lithium adsorbent. However, it faces the problem of Mn dissolution loss in the desorption process, which may pollute the environment in industrial production. Although LTO type ion sieve also has the problem of dissolution loss, and the dissolution loss of titanium species in LTO will reduce its adsorption capacity.

[0004] Therefore, the prior art still needs to be further improved and improved. SUMMARY

[0005] In view of the shortcomings of the prior art, the purpose of the present application is to provide a carbon-coated lithium ion sieve and a preparation method thereof, which aims to solve the problem of reduced adsorption capacity caused by dissolution loss of the existing lithium ion sieve.

[0006] A preparation method of a carbon-coated lithium ion sieve, comprising:

[0007] dispersing lithium titanate in a bitumen solution to obtain a mixed solution;

[0008] drying the mixture under vacuum to obtain a precursor;

[0009] calcining the precursor to obtain a carbon-coated lithium titanate composite, and performing acid washing, centrifugal collection of solid product, water washing, and drying treatment on the carbon-coated lithium titanate composite to obtain a carbon-coated lithium ion sieve.

[0010] Optionally, the method for preparing the carbon-coated lithium ion sieve, wherein the lithium titanate is selected from any one of Li2TiO3, Li4Ti5O 12 , and LiTi2O4.

[0011] Optionally, the method for preparing the carbon-coated lithium ion sieve, wherein the concentration of the asphaltenes in the asphaltenes solution is 0.05 g / mL-0.5 g / mL.

[0012] Optionally, the method for preparing the carbon-coated lithium ion sieve, wherein the mass ratio of the asphaltenes to the lithium titanate in the mixture is 1:1-1:5.

[0013] Optionally, the method for preparing the carbon-coated lithium ion sieve, wherein the precursor is calcined, and the calcination temperature is 480°C-580°C.

[0014] Optionally, the method for preparing the carbon-coated lithium ion sieve, wherein the carbon-coated lithium titanate composite is subjected to acid washing, and the acid washing time is 5-7 hours, and the acid washing temperature is 25-60°C.

[0015] Optionally, the method for preparing the carbon-coated lithium ion sieve, wherein the carbon-coated lithium titanate composite is subjected to acid washing, and the concentration of the acid used for acid washing is 0.2 M-2 M.

[0016] Optionally, the method for preparing the carbon-coated lithium ion sieve, wherein the vacuum degree under the vacuum condition is -1 bar.

[0017] A carbon-coated lithium ion sieve, wherein the carbon-coated lithium ion sieve is prepared by the method described above.

[0018] Beneficial Effects: Compared with existing technologies, the preparation method of the carbon-coated lithium-ion sieve of the present invention obtains a carbon-coated titanium-based lithium-ion sieve by mixing lithium titanate with asphaltene and then performing simple high-temperature calcination. The outer layer of this ion sieve is composed of a porous carbon layer, which provides a large number of active sites, promotes the diffusion of lithium-containing brine, facilitates lithium-ion adsorption, and increases its adsorption capacity. Simultaneously, the carbon layer protection enhances the stability of the lithium-ion sieve, especially its acid resistance, reduces dissolution loss, and facilitates multiple recycling of the lithium-ion sieve. Furthermore, the preparation method shown in this invention is simple, low-cost, and beneficial for the resource utilization of industrial solid waste. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the preparation method of carbon-coated lithium-ion sieve in the embodiment.

[0020] Figure 2 This is a SEM image of the carbon-coated lithium-ion sieve prepared in Example 1.

[0021] Figure 3 The Li-coated lithium-ion sieve prepared in Example 1 + Ti 4+ Elution rate. Detailed Implementation

[0022] This invention provides a carbon-coated lithium-ion sieve and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0023] To address the problem that existing ion sieves are not suitable for lithium extraction from alkaline salt lake brines rich in hydroxide ions.

[0024] This embodiment provides a method for preparing a carbon-coated lithium-ion sieve, such as... Figure 1 As shown, the preparation method of the carbon-coated lithium-ion sieve includes: adding asphaltene to toluene and dissolving it fully by a combination of ultrasound and heating to obtain an asphaltene solution. A certain amount of lithium titanate is weighed and added to the asphaltene solution under ultrasonic and magnetic stirring conditions to obtain a mixture. The mixture is placed in a vacuum drying oven and dried to obtain a precursor. The obtained precursor is then placed in a tube furnace and heated to 480℃-580℃ under inert gas protection, and naturally cooled to room temperature to obtain a carbon-coated lithium titanate composite material (LTO@C). The carbon-coated lithium titanate composite material is added to HCl and placed in a shaker for acid washing. The solid product is then collected by centrifugation and washed three times with water to remove surface-adsorbed lithium ions. Finally, it is vacuum dried to obtain the product carbon-coated lithium-ion sieve (HTO@C).

[0025] In the embodiment, the raw materials bitumen and lithium titanate can be extracted from industrial waste, so that the preparation cost can be reduced, and the industrial solid waste resource utilization is facilitated. The lithium titanate used can be any one of Li2TiO3, Li4Ti5O 12 、LiTi2O4.

[0026] The carbon-coated lithium ion sieve and the preparation method thereof provided by the application will be further explained and described through specific preparation examples.

[0027] Example 1

[0028] 10 grams of bitumen was weighed and added to 200 mL of toluene (the solid-liquid ratio of bitumen and toluene was 50 g / L), and the bitumen was fully dissolved by the combination of ultrasonic and heating, so that the concentration of bitumen in toluene was 0.05 g / ml.

[0029] The mass ratio of bitumen to lithium titanate was 1:3, Li2TiO3 was weighed and slowly dispersed into the bitumen solution under ultrasonic action, and then magnetically stirred for 2 h, and then placed in a vacuum drying box, and the precursor was obtained under the condition of 60℃ and vacuum. The precursor was placed in a tube furnace, protected by nitrogen, heated to 480℃ at a rate of 5℃ / min, and kept for 6 h, and then naturally cooled to room temperature to obtain a carbon-coated lithium titanate composite material (LTO@C). According to the solid-liquid ratio of 10 g / L, the composite material was added to 0.2M HCl, and placed in a shaker at 25℃ and 250r for 5h. Then the solid product was collected by centrifugation, and washed with water for 3 times to remove the surface adsorbed lithium ions, and finally vacuum dried to obtain the product (HTO@C). The SEM characterization diagram is shown in Figure 1. Figure 2 .

[0030] Using HTO@C as the adsorbent, the lithium extraction research was carried out

[0031] A certain concentration of LiCl solution was prepared, 50 mL was poured into a 100 mL conical flask containing 100 mg of adsorbent. The conical flask was placed in a constant temperature water bath shaker, and the adsorption experiment was carried out under the condition of temperature (50℃) and oscillation speed (250rpm) for 10h.

[0032] The results show that (1) the carbon-coated lithium ion sieve has excellent selectivity for lithium ions, and the adsorption amount of the main interference substance magnesium ions can be ignored. (2) The carbon coating can effectively protect the ion sieve, improve its acid resistance, reduce the dissolution loss of titanate, and the elution rate is as follows Figure 3(3) In the LiCl solution with pH = 12 and lithium ion content of 300 mg / L, the lithium ion adsorption capacity of HTO@C can be as high as 30.9 mg / L, which is 4.3% higher than that of uncoated lithium titanate ion sieve (HTO) of the same mass.

[0033] Example 2

[0034] 20 grams of asphaltene was weighed into 200 mL of toluene (the solid-liquid ratio of asphaltene and toluene was 50 g / L), and the asphaltene was fully dissolved by the combination of ultrasonic and heating, so that the concentration of asphaltene in toluene was 0.1 g / ml.

[0035] The mass ratio of asphaltene to lithium titanate was 1:1, and Li4Ti5O 12 was slowly dispersed into the asphaltene solution under ultrasonic action, and after magnetic stirring for 2 h, the precursor was obtained in a vacuum drying box under the condition of 60°C and vacuum. The precursor was placed in a tube furnace, and nitrogen was passed through the tube furnace at a rate of 10°C / min to heat to 500°C, and the temperature was kept for 6 h, and then the temperature was naturally cooled to room temperature to obtain a carbon-coated lithium titanate composite material (LTO@C). According to the solid-liquid ratio of 10 g / L, the composite material was added to 1M HCl, and placed in a shaking bed at 40°C and 250 r for 6 h. Then the solid product was collected by centrifugation, and washed with water for 3 times to remove the surface adsorbed lithium ions, and finally vacuum dried to obtain the product (HTO@C).

[0036] Example 3

[0037] 100 grams of asphaltene was weighed into 200 mL of toluene (the solid-liquid ratio of asphaltene and toluene was 50 g / L), and the asphaltene was fully dissolved by the combination of ultrasonic and heating, so that the concentration of asphaltene in toluene was 0.5 g / ml.

[0038] The mass ratio of asphaltene to lithium titanate was 1:5, and LiTi2O4 was weighed, and slowly dispersed into the asphaltene solution under ultrasonic action, and after magnetic stirring for 3 h, the precursor was obtained in a vacuum drying box under the condition of 70°C and vacuum. The precursor was placed in a tube furnace, and nitrogen was passed through the tube furnace at a rate of 10°C / min to heat to 580°C, and the temperature was kept for 6 h, and then the temperature was naturally cooled to room temperature to obtain a carbon-coated lithium titanate composite material (LTO@C). According to the solid-liquid ratio of 20 g / L, the composite material was added to 2M HCl, and placed in a shaking bed at 60°C and 250 r for 10 h. Then the solid product was collected by centrifugation, and washed with water for 3 times to remove the surface adsorbed lithium ions, and finally vacuum dried to obtain the product (HTO@C).

[0039] In summary, the present application provides a carbon-coated lithium ion sieve and a preparation method thereof, comprising: dispersing lithium titanate in a bituminous solution to obtain a mixed solution; drying the mixed solution under vacuum conditions to obtain a precursor; and performing acid washing, centrifugation and drying treatment on the carbon-coated lithium titanate composite material to obtain the carbon-coated lithium ion sieve. The present application provides a novel preparation method of a bituminous modified and derivatized carbon-coated lithium ion sieve. The technology uses industrial waste garbage extract bitumen and lithium titanate as raw materials, and prepares a carbon-coated lithium titanate composite material through simple high-temperature calcination, and obtains a carbon-coated lithium ion sieve by acid washing and separation. The outer layer of the ion sieve is composed of a porous carbon layer, which can provide a large number of active sites, promote the diffusion of lithium-containing brine, and is beneficial to lithium ion adsorption and improves the adsorption capacity. At the same time, the carbon layer protection can enhance the stability of the lithium ion sieve, especially the acid resistance, reduce the solution loss, and is beneficial to the multiple recycling use of the lithium ion sieve. In addition, the preparation method shown in the present application has the advantages of simple process, low cost, and is beneficial to the resource utilization of industrial solid waste.

[0040] It should be understood that the application of the present application is not limited to the above examples, and those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the appended claims of the present application.

Claims

1. A method for preparing carbon-coated lithium ion-sieve, characterized in that, The application relates to a preparation method of a carbon-coated lithium ion sieve. The lithium titanate is dispersed in a bitumastic solution to obtain a mixed solution; The mixed solution is dried under vacuum conditions to obtain a precursor; The precursor is calcined to obtain a carbon-coated lithium titanate composite material, the carbon-coated lithium titanate composite material is subjected to acid pickling, centrifugal collection of a solid product, water washing and drying treatment to obtain a carbon-coated lithium ion sieve. the lithium titanate is selected from any one of Li2TiO3, Li4Ti5O 12 and LiTi2O4; The carbon-coated lithium titanate composite material is subjected to acid pickling, wherein the acid pickling time is 5-7 hours, and the temperature during the acid pickling is 25-60 DEG C. The carbon-coated lithium titanate composite material is subjected to acid pickling, wherein the concentration of the acid used for the acid pickling is 0.2M-2M.

2. The method for preparing a carbon-coated lithium-ion sieve according to claim 1, characterized in that, The concentration of the bitumastic in the bitumastic solution is 0.05g / mL-0.5g / mL.

3. The method for preparing a carbon-coated lithium-ion sieve according to claim 1, characterized in that, The mass ratio of the bitumastic to the lithium titanate in the mixed solution is 1:1-1:

5.

4. The method of claim 1, wherein the carbon-coated lithium-ion-sieve is prepared by the steps of: The precursor is calcined, wherein the calcination temperature is 480 DEG C-580 DEG C.

5. The method of claim 1, wherein the carbon-coated lithium-ion-sieve is prepared by the steps of: mixing a lithium-ion-sieve and a carbon source; and heating the mixture at a temperature of 300-1,000°C for 1-10 hours in an inert gas atmosphere. The vacuum degree under the vacuum conditions is -1bar.

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