Strong-covalence manganese oxide-based Fenton-like catalyst based on waste high-manganese ternary lithium battery recycling as well as preparation method and application of strong-covalence manganese oxide-based Fenton-like catalyst

Abstract

The invention provides a strong-covalence manganese oxide-based Fenton-like catalyst based on waste high-manganese ternary lithium battery recycling as well as a preparation method and application of the strong-covalence manganese oxide-based Fenton-like catalyst. Based on the electronegativity difference between metal elements, the MnOx-based Fenton-like catalyst is modified by using Co and Ni with high electronegativity as doping agents, the Mn-O covalence in MnOx is enhanced, the oxidation-reduction cycle of Mn is accelerated, and the activity of the MnOx-based Fenton-like catalyst is greatly improved. Furthermore, a recycling process is adopted, the waste high-manganese ternary LIBs are taken as a raw material, an acid leaching system is optimized, the high-covalence manganese oxide-based Fenton-like catalyst is prepared, high-value Li is recycled, and the problems that a traditional recycling process is tedious and complex, high in energy consumption and low in product additional value are effectively solved; a new thought is provided for preparation of the high-activity Fenton-like catalyst, and a new application way is provided for sustainable recycling of the waste high-manganese ternary LIBs.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of resource utilization of waste lithium batteries, and relates to a strong covalent manganese oxide-based Fenton catalyst based on resource utilization of waste high-manganese ternary lithium batteries and a preparation method and application thereof. BACKGROUND

[0002] With the green and low-carbon transformation of energy, the consumption of lithium batteries (LIBs) has shown explosive growth. At present, ternary LIBs are widely used due to their high energy density. The safety of traditional ternary LIBs is poor, and in large-capacity batteries, the positive active material is often a high-manganese ternary positive active material formed by mixing traditional ternary positive active materials with lithium manganate. The high-manganese ternary positive active material can effectively improve the safety of ternary LIBs and promote their large-scale application. However, the service life of ternary LIBs is generally 6-8 years, and when they reach the service life, a large amount of waste high-manganese ternary LIBs will be generated. Waste high-manganese ternary LIBs contain a large amount of Mn, Co and Ni, which are both strategic resources and heavy metal elements, and if they are not properly treated, they will cause serious environmental pollution and resource waste. Therefore, it is of great practical significance to treat and dispose of waste high-manganese ternary LIBs.

[0003] Hydrometallurgical technology is one of the commonly used resource utilization technologies for waste ternary LIBs. After acid leaching treatment of the positive electrode material of waste ternary LIBs, the technology realizes high-purity resource utilization of metal elements through multi-step extraction separation-purification process. However, the complex and lengthy separation-purification process and the large amount of organic extractant input will significantly increase the cost of resource utilization of waste ternary LIBs. In addition, for waste high-manganese ternary LIBs, the Mn content is high, but the market average price is low, and if the multi-step extraction separation-purification method is still used to obtain high-purity low-value Mn resource products, the resource recovery cost will inevitably be further increased. In view of the multi-valence and environmental friendly characteristics of Mn, it is a feasible strategy to convert low-value Mn into high-value manganese oxide (MnO x ) based Fenton catalyst for activating persulfate (PMS) to degrade organic pollutants in water. Generally speaking, the efficient redox cycle of Mn reaction sites is the key to maintaining its high Fenton-like activity. However, the redox potential of Mn(IV) / Mn(III) (0.95 V vs NHE) is significantly lower than that of HSO5 - / SO5 - (1.11 V vs NHE), which makes it impossible to regenerate Mn(III) (i.e. reduction of PMS to Mn(IV)) thermodynamically, which seriously restricts the redox cycle of Mn and greatly reduces its catalytic activity. Existing studies have shown that MnO xIn the PMS-AOPs, enhancing the Mn-O covalence can reduce the charge transfer energy between Mn and O species, thereby overcoming the HSO5 - The thermodynamic limitation of reducing Mn(IV) to Mn(III). Therefore, enhancing the Mn-O covalence is an effective method to solve the limitation of the Mn site redox cycle. SUMMARY

[0004] To solve the above technical problems, the purpose of the present application is to provide a strong covalence manganese oxide-based Fenton-like catalyst based on the resource utilization of waste high-manganese ternary lithium batteries and a preparation method and application thereof. Based on the difference in electronegativity between Mn (1.55) and Co (1.88) and Ni (1.91), a small amount of high-electronegativity Co and Ni in the waste high-manganese ternary LIBs is used as a dopant to modify the MnOx-based Fenton-like catalyst derived from waste high-manganese ternary LIBs, thereby enhancing the Mn-O covalence in MnOx, accelerating the Mn(II) / Mn(III) / Mn(IV) self-oxidation and reduction cycle, and achieving a substantial increase in the activity of the MnOx-based Fenton-like catalyst. In addition, while realizing the high-value conversion of low-value Mn in waste high-manganese ternary LIBs, the present application also realizes the effective recovery of Li, effectively alleviating the problems of long and complex separation-purification process, high energy consumption, and low product added value in the traditional resource utilization process of waste ternary LIBs.

[0005] The purpose of the present application can be achieved by the following scheme: In a first aspect, the present application provides a strong covalence manganese oxide-based Fenton-like catalyst, which is a MnO x , 0 < x ≤ 2; the M element includes Co and Ni, wherein the molar ratio of Co to Mn is 1:7~1:10, and the molar ratio of Ni to Mn is 1:3~1:5.

[0006] Based on the difference in electronegativity between Mn (1.55) and Co (1.88) and Ni (1.91), the present application effectively enhances the Mn-O covalence in MnO x , accelerates the oxidation and reduction cycle of Mn(II) / Mn(III) / Mn(IV), and thereby substantially increases the Fenton-like activity thereof.

[0007] In a second aspect, the present application provides a method for preparing a strong covalence manganese oxide-based Fenton-like catalyst based on the resource utilization of waste high-manganese ternary LIBs, comprising the following steps: S1, placing waste high-manganese ternary LIBs black powder in an acid leaching system composed of acid and reducing agent to leach metal elements; S2, filtering the leaching solution, adding a precipitating agent to the obtained filtrate, and performing solid-liquid separation to obtain a Li-rich solution and a Mn-rich residue containing a small amount of Co and Ni; S3, the Mn-rich slag containing a small amount of Co and Ni is subjected to a calcination reaction and grinding, to obtain the strong covalent manganese oxide-based Fenton-like catalyst.

[0008] As an embodiment of the present application, in step S1, the waste high-manganese ternary LIBs black powder is a pre-processed waste high-manganese ternary LIBs black powder, and the pre-processing includes discharging, crushing, and sieving.

[0009] Further, the pre-processing specifically includes the following steps: Step 1, the waste high-manganese ternary LIBs is placed in a NaCl solution with a mass fraction of 1-10 wt%, and subjected to a discharging reaction; the discharging reaction time is 6-48 h, and the mass ratio of the waste high-manganese ternary LIBs to the NaCl solution is 1:10-1:30; Step 2, the discharged waste high-manganese ternary LIBs is crushed in a crusher; Step 3, the crushed product is sieved in a sifter to obtain a waste high-manganese ternary LIBs black powder.

[0010] As an embodiment of the present application, in step S1, in the acid leaching system, the acid includes one or more of sulfuric acid, nitric acid, hydrochloric acid, citric acid, maleic acid, tartaric acid, and malic acid, and the reducing agent includes one or more of hydrogen peroxide, glucose, sodium bisulfite, and ascorbic acid.

[0011] As an embodiment of the present application, in step S1, in the acid leaching system, the concentration of the acid is 0.1-3 mol / L, and the dosage of the reducing agent is 0.1-2 g of reducing agent per g of black powder.

[0012] As an embodiment of the present application, in step S1, the leaching temperature is 50-100 ℃, and the leached metal elements include Li, Mn, Co, and Ni.

[0013] As an embodiment of the present application, in step S2, the precipitant includes any one of oxalic acid, oxalate, hydroxide, and carbonate; if the precipitant is oxalic acid or oxalate, the molar ratio of the metal elements to the precipitant is 1:1-1:3; if the precipitant is hydroxide or carbonate, the pH is adjusted to be greater than 8.

[0014] Further, the precipitant includes any one of oxalic acid, sodium oxalate, potassium oxalate, sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

[0015] In one embodiment of the present invention, in step S3, the calcination reaction temperature is 250-800 °C, and the time is 60-600 min. Preferably, the calcination reaction temperature is 250-500 °C. In some preferred embodiments, the calcination reaction temperature is 300-500 °C. If the temperature is too low, the metal salt precursor will not be completely pyrolyzed and a stable metal oxide cannot be formed; if the temperature is too high, the formed metal oxide will agglomerate due to its excessive surface energy, greatly reducing the specific surface area and total pore volume of the Fenton-like catalyst, thereby significantly reducing the exposure of reactive sites and thus reducing the catalytic activity and degradation performance of the Fenton-like catalyst.

[0016] Thirdly, the present invention provides the application of the strongly covalent manganese oxide-based Fenton catalyst in the catalytic activation of sulfate degradation of organic pollutants in water.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention is based on the difference in electronegativity between metal elements, using highly electronegative Co and Ni as dopants to dop MnO. x Modification of basic Fenton catalysts to enhance MnO x The covalent nature of Mn-O accelerates the redox cycle of Mn, thereby significantly improving the activity of MnOx-based Fenton catalysts.

[0018] 2. This invention employs a resource-based process, using waste high-manganese ternary LIBs as raw materials. Li, Mn, Co, and Ni elements are leached out through an acid leaching system, and a precipitant is added to obtain a Li-rich solution and a Mn-rich slag containing small amounts of Co and Ni. Further calcination of the Mn-rich slag yields a strongly covalent manganese oxide-based Fenton-like catalyst. This achieves the high-value utilization of high-content, low-value Mn in waste high-manganese ternary LIBs, while also recovering high-value Li. This effectively alleviates the problems of lengthy and complex separation-purification processes, high energy consumption, and low product added value in traditional waste ternary LIBs resource utilization. It not only provides a new approach for the preparation of highly active Fenton-like catalysts but also offers a new application pathway for the sustainable resource utilization of waste high-manganese ternary LIBs.

[0019] 3. The strong covalent manganese oxide-based Fenton catalyst of the present invention can be used to catalyze the degradation of organic pollutants in water by sulfate activation, thereby achieving efficient degradation of organic pollutants in water. Attached Figure Description

[0020] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1To investigate the effect of different calcination temperatures on the degradation performance of organic pollutants by Fenton-like catalysts in Examples 1-4; Figure 2 To investigate the effect of Fenton-like catalysts in Example 1 and Comparative Examples 1-5 on the degradation performance of organic pollutants. DETAILED DESCRIPTION

[0021] The present application will be described in detail below with reference to the accompanying drawings and specific examples. The following examples are implemented under the technical scheme of the present application, and detailed implementation and specific operation processes are provided, which will help those skilled in the art to further understand the present application. It should be pointed out that the protection scope of the present application is not limited to the following examples, and several adjustments and improvements made under the concept of the present application also belong to the protection scope of the present application.

[0022] The waste old high manganese ternary LIBs black powder in the examples and comparative examples of the present application is a pre-treated waste old high manganese ternary LIBs black powder, including discharging, crushing and screening, and the specific steps are as follows: Step 1, placing the waste old high manganese ternary LIBs in a NaCl solution with a mass fraction of 5 wt%, and carrying out a discharging reaction, the discharging time is 20 h, and the mass ratio of the waste old high manganese ternary LIBs to the NaCl solution is 1:20; Step 2, placing the discharged waste old high manganese ternary LIBs in a crusher for crushing; Step 3, placing the crushed product in a screening machine for screening to obtain a waste old high manganese ternary LIBs black powder.

[0023] Example 1 (1) placing the pre-treated waste old high manganese ternary LIBs black powder in an acid leaching system composed of citric acid and hydrogen peroxide at 80 °C, and carrying out leaching of metal elements, wherein the concentration of citric acid is 1.5 mol / L, and the concentration of hydrogen peroxide is 0.6 g reductant / g black powder; (2) performing suction filtration on the leaching solution obtained in (1), and adding oxalic acid to the obtained filtrate, and after the reaction is completed, performing solid-liquid separation on the obtained system, wherein the molar ratio of metal elements to oxalate is 1:1, the liquid is a Li-rich solution, and the solid is a Mn-rich residue containing a small amount of Co and Ni; (3) placing the Mn-rich residue obtained in (2) in a muffle furnace for calcination reaction, the calcination temperature is 300 °C, and the calcination time is 120 min; (4) obtaining a strong covalent MnO x base Fenton-like catalyst (MnNiCoO xLIBs-300 °C, where x is 4 / 3, the molar ratio of Co to Mn is 1:7.28, and the molar ratio of Ni to Mn is 1:3.82.

[0024] (5) The prepared strong covalent MnOx-based Fenton-like catalyst (MnNiCoO x -LIBs-300 °C) was used to degrade bisphenol A in the presence of potassium peroxymonosulfate composite salt to measure its Fenton-like activity, and it was found that the degradation rate of bisphenol A reached 100% within 25 min, and the rate constant was 0.225 min -1 .

[0025] Example 2 (1) At 80 °C, the pre-processed waste high-manganese ternary LIBs black powder was placed in an acid leaching system composed of citric acid and hydrogen peroxide for metal element leaching, wherein the concentration of citric acid was 1.5 mol / L, and the concentration of hydrogen peroxide was 0.6 g reducing agent / g black powder; (2) The leaching solution obtained in (1) was suction filtered, and oxalic acid was added to the obtained filtrate, and after the reaction was completed, the obtained system was subjected to solid-liquid separation, wherein the molar ratio of metal elements to oxalate was 1:1, the liquid was a Li-rich solution, and the solid was a Mn-rich residue containing a small amount of Co and Ni; (3) The Mn-rich filter residue obtained in (2) was placed in a muffle furnace for calcination, and the calcination temperature was 400 °C and the calcination time was 120 min; (4) After the obtained system in (3) was ground, a strong covalent MnO x -based Fenton-like catalyst (MnNiCoO x -LIBs-400 °C, where x is 4 / 3, the molar ratio of Co to Mn is 1:7.28, and the molar ratio of Ni to Mn is 1:3.82.

[0026] (5) The prepared strong covalent MnO x -based Fenton-like catalyst (MnNiCoO x -LIBs-400 °C) was used to degrade bisphenol A in the presence of potassium peroxymonosulfate composite salt to measure its Fenton-like activity, and it was found that the degradation rate of bisphenol A reached 100% within 25 min, and the rate constant was 0.209 min -1 .

[0027] Example 3 (1) At 80 °C, the pre-processed waste high-manganese ternary LIBs black powder was placed in an acid leaching system composed of citric acid and hydrogen peroxide for metal element leaching, wherein the concentration of citric acid was 1.5 mol / L, and the concentration of hydrogen peroxide was 0.6 g reducing agent / g black powder; (2) The leaching solution obtained in (1) is subjected to suction filtration, and oxalic acid is added to the obtained filtrate. After the reaction is completed, solid-liquid separation is performed on the obtained system, wherein the molar ratio of metal elements to oxalate is 1:1, the liquid is a Li-rich solution, and the solid is a Mn-rich residue containing a small amount of Co and Ni; (3) The Mn-rich residue obtained in (2) is placed in a muffle furnace for calcination reaction, the calcination temperature is 500 °C, and the calcination time is 120 min; (4) After the obtained system in (3) is ground, a strong covalent MnO x -based Fenton-like catalyst (MnNiCoO x -LIBs-500 °C is obtained, wherein x is 4 / 3, the molar ratio of Co to Mn is 1:7.28, and the molar ratio of Ni to Mn is 1:3.82.

[0028] (5) The strong covalent MnO x -based Fenton-like catalyst (MnNiCoO x -LIBs-500 °C) is used to degrade bisphenol A in the presence of a potassium peroxymonosulfate composite salt to measure its Fenton-like activity. It is found that the degradation rate of bisphenol A reaches 98.1% within 25 min, and the rate constant is 0.154 min -1 .

[0029] Example 4 (1) The pre-treated waste high-manganese ternary LIBs black powder is placed in an acid leaching system composed of citric acid and hydrogen peroxide at 80 °C for metal element leaching, wherein the concentration of citric acid is 1.5 mol / L, and the concentration of hydrogen peroxide is 0.6 g reductant / g black powder; (2) The leaching solution obtained in (1) is subjected to suction filtration, and oxalic acid is added to the obtained filtrate. After the reaction is completed, solid-liquid separation is performed on the obtained system, wherein the molar ratio of metal elements to oxalate is 1:1, the liquid is a Li-rich solution, and the solid is a Mn-rich residue containing a small amount of Co and Ni; (3) The Mn-rich residue obtained in (2) is placed in a muffle furnace for calcination reaction, the calcination temperature is 600 °C, and the calcination time is 120 min; (4) After the obtained system in (3) is ground, a strong covalent MnO x -based Fenton-like catalyst (MnNiCoO x -LIBs-600 °C is obtained, wherein x is 4 / 3, the molar ratio of Co to Mn is 1:7.28, and the molar ratio of Ni to Mn is 1:3.82.

[0030] (5) The strong covalent MnO x -based Fenton-like catalyst (MnNiCoO xFenton activity, it was found that the degradation rate of bisphenol A reached 73.7% in 25 min, and the rate constant was 0.055 min -1 .

[0031] Figure 1 Effects of different calcination temperatures on the degradation performance of organic pollutants in Examples 1-4.

[0032] Comparative Example 1 (1) The manganese oxalate dihydrate was placed in a muffle furnace for calcination reaction, the calcination temperature was 300 °C, and the calcination time was 120 min; (2) The system obtained in (1) was ground to obtain MnO x Fenton catalyst (MnO x , where x is 4 / 3).

[0033] (3) The prepared MnO x In the presence of potassium peroxymonosulfate composite salt, the degradation of bisphenol A was carried out to measure its Fenton activity, and it was found that the degradation rate of bisphenol A reached 77.9% in 25 min, and the rate constant was 0.068 min -1 .

[0034] Comparative Example 2 (1) The cobalt oxalate dihydrate was placed in a muffle furnace for calcination reaction, the calcination temperature was 300 °C, and the calcination time was 120 min; (2) The system obtained in (1) was ground to obtain Co3O4 Fenton catalyst (Co3O4).

[0035] (3) The prepared Co3O4 was used to degrade bisphenol A in the presence of potassium peroxymonosulfate composite salt to measure its Fenton activity, and it was found that the degradation rate of bisphenol A reached 87.9% in 25 min, and the rate constant was 0.087 min -1 .

[0036] Comparative Example 3 (1) The nickel oxalate dihydrate was placed in a muffle furnace for calcination reaction, the calcination temperature was 300 °C, and the calcination time was 120 min; (2) The system obtained in (1) was ground to obtain NiO Fenton catalyst (NiO).

[0037] (3) The prepared NiO was used to degrade bisphenol A in the presence of potassium peroxymonosulfate composite salt to measure its Fenton activity, and it was found that the degradation rate of bisphenol A reached 42.0% in 25 min, and the rate constant was 0.024 min -1 .

[0038] Comparative Example 4 (1) Nickel oxalate and manganese oxalate dihydrate were mechanically mixed and then placed in a muffle furnace for calcination reaction. The calcination temperature was 300 °C and the calcination time was 120 min. The molar ratio of Ni to Mn was 1:3.82. (2) The system obtained in (1) was ground to obtain MnNiO x Fenton-like catalyst (MnNiO) x (where x is 4 / 3).

[0039] (3) The prepared MnNiO x Bisphenol A was degraded in the presence of potassium persulfate complex salt to determine its Fenton-like activity. The results showed that the degradation rate of bisphenol A reached 92.9% within 25 min, with a rate constant of 0.113 min. -1 .

[0040] Comparative Example 5 (1) Cobalt oxalate dihydrate and manganese oxalate dihydrate were mechanically mixed and then placed in a muffle furnace for calcination reaction. The calcination temperature was 300 °C and the calcination time was 120 min. The molar ratio of Co to Mn was 1:7.28. (2) The system obtained in (1) was ground to obtain MnCoO x Fenton-like catalyst (MnCoO) x (where x is 4 / 3).

[0041] (3) The prepared MnCoO x Bisphenol A was degraded in the presence of potassium peroxymonosulfate complex salt to determine its Fenton-like activity. The results showed that the degradation rate of bisphenol A reached 89.1% within 25 min, with a rate constant of 0.095 min. -1 .

[0042] Depend on Figure 2 It can be seen that the Fenton-like catalyst (MnNiCoO) prepared in Example 1... x -LIBs) exhibit significantly higher degradation performance for organic pollutants than Comparative Examples 1-5, indicating that this invention utilizes highly electronegative Co and Ni as dopants to degrade MnO x Modification of MnOx-based Fenton catalysts can significantly improve their activity.

[0043] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A strongly covalent manganese oxide-based Fenton-like catalyst, characterized in that, The catalyst is MnO doped with M elements x 0 < x < 2; the M elements include Co and Ni, wherein the molar ratio of Co to Mn is 1:7~1:10, and the molar ratio of Ni to Mn is 1:3~1:

5.

2. A method for the preparation of the strongly covalent manganese oxide-based Fenton-like catalyst according to claim 1 based on the valorization of spent high-manganese ternary LIBs, characterized by, The method comprises the following steps: S1, placing waste high-manganese ternary LIBs black powder in an acid leaching system composed of acid and reducing agent to leach metal elements; S2, filtering the leaching solution, adding a precipitant to the obtained filtrate, and performing solid-liquid separation to obtain a Li-rich solution and a Mn-rich residue containing a small amount of Co and Ni; S3, performing a calcination reaction on the Mn-rich residue containing a small amount of Co and Ni, and grinding to obtain the strong covalent manganese oxide-based Fenton-like catalyst.

3. The method of claim 2, wherein, In step S1, the waste high-manganese ternary LIBs black powder is a waste high-manganese ternary LIBs black powder after pretreatment, and the pretreatment comprises the following steps: Step 1, placing waste high-manganese ternary LIBs in a NaCl solution with a mass fraction of 1-10 wt% to perform a discharge reaction; the time of the discharge reaction is 6-48 h, and the mass ratio of waste high-manganese ternary LIBs to the NaCl solution is 1:10-1:30; Step 2, crushing the waste high-manganese ternary LIBs after discharge; Step 3, screening the crushed product to obtain the waste high-manganese ternary LIBs black powder.

4. The method of claim 2, wherein, In step S1, in the acid leaching system, the acid comprises one or more of sulfuric acid, nitric acid, hydrochloric acid, citric acid, maleic acid, tartaric acid, and malic acid, and the reducing agent comprises one or more of hydrogen peroxide, glucose, sodium bisulfite, and ascorbic acid.

5. The method of claim 2, wherein, In step S1, in the acid leaching system, the concentration of the acid is 0.1-3 mol / L, and the dosage of the reducing agent is 0.1-2 g of reducing agent per g of black powder.

6. The method of claim 2, wherein, In step S1, the metal elements include Li, Mn, Co, and Ni; and the leaching temperature is 50-100 ℃.

7. The method of claim 2, wherein, In step S2, the precipitant comprises any one of oxalic acid, oxalate, hydroxide, and carbonate; wherein if the precipitant is oxalic acid or oxalate, the molar ratio of the metal elements to the precipitant is 1:1-1:3; and if the precipitant is hydroxide or carbonate, the pH is adjusted to be greater than 8.

8. The method of claim 7, wherein, In step S2, the precipitant comprises any one of oxalic acid, sodium oxalate, potassium oxalate, sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

9. The method of claim 2, wherein, In step S3, the temperature of the calcination reaction is 250-800 ℃, and the time is 60-600 min.

10. Use of the strong covalent manganese oxide-based Fenton-like catalyst according to claim 1 or prepared by the method according to any one of claims 2-9 in catalyzing activation of sulfate to degrade organic pollutants in water.

Images