A method for treating a double fluorosulfonylimine heavy residue

Abstract

The application provides a treatment method of bisfluorosulfone imide heavy residue, which comprises the following steps: reacting a raw material system comprising bisfluorosulfone imide heavy residue and an acidic aqueous solution to obtain a fluorine-containing acid liquid and an amino sulfonic acid crude product; wherein the fluorine-containing acid liquid can be used as a by-product acid to save treatment costs; the amino sulfonic acid crude product can also be directly sold as a product to reduce treatment costs, bring economic benefits, and realize resource recycling of the bisfluorosulfone imide heavy residue.

Description

Technical Field

[0001] This invention belongs to the field of bis(fluorosulfonyl)imide heavy residue recovery technology, specifically relating to a method for treating bis(fluorosulfonyl)imide heavy residue. Background Technology

[0002] Difluorosulfonylimide, as a raw material for the preparation of lithium bisfluorosulfonylimide, is widely used in lithium-ion batteries. Difluorosulfonylimide is obtained through purification methods, which produce bisfluorosulfonylimide residue. This residue is a viscous liquid with poor flowability, and its main components are bisfluorosulfonylimide, fluorosulfonic acid, and their small amounts of salts. Among them, bisfluorosulfonylimide and fluorosulfonic acid account for more than 95%. As the market demand for lithium bisfluorosulfonylimide increases, the production of lithium bisfluorosulfonylimide by enterprises continues to increase, which will generate more bisfluorosulfonylimide residue.

[0003] Therefore, there is an urgent need to develop a treatment method for bis(fluorosulfonyl)imide heavy slag to achieve the resource-based recycling and utilization of the heavy slag. Summary of the Invention

[0004] This invention provides a method for treating bis(fluorosulfonyl)imide heavy residue, which enables the resource-based recycling of the heavy residue and reduces processing costs.

[0005] This invention provides a method for treating bis(fluorosulfonyl)imide heavy residue, comprising the following steps:

[0006] The raw material system, consisting of bis(fluorosulfonyl)imide heavy residue and acidic aqueous solution, is reacted to obtain a fluorinated acid solution and crude aminosulfonic acid.

[0007] Further, the bis(fluorosulfonyl)imide heavy residue is added to the acidic aqueous solution to carry out the reaction, and the addition time is 0.5-3 hours.

[0008] Furthermore, the acidic aqueous solution is at least one of sulfuric acid aqueous solution, nitric acid aqueous solution, and hydrochloric acid aqueous solution.

[0009] Furthermore, the acidic aqueous solution contains 50-98% acid by mass.

[0010] Furthermore, the mass ratio of the difluorosulfonamide heavy residue to the acidic aqueous solution is 1:(1-10).

[0011] Furthermore, the reaction temperature is 30-100°C; and / or,

[0012] The reaction time is 1-10 hours.

[0013] Furthermore, the reaction process is accompanied by stirring at a speed of 100-500 rpm.

[0014] Furthermore, it also includes:

[0015] The crude aminosulfonic acid product is leached with the acidic washing solution to obtain the aminosulfonic acid product and the leached acid solution.

[0016] Furthermore, the rinsing treatment is performed 3-8 times; and / or,

[0017] In the rinsing process, the amount of acidic washing solution used is 1-5 times the mass of the difluorosulfonyl imide heavy slag.

[0018] Furthermore, it also includes: using at least one of the fluorinated acid solution and the rinsed acid solution as a raw material in the preparation of phosphorus pentafluoride.

[0019] This invention provides a method for processing bis(fluorosulfonyl)imide heavy residue. By reacting a raw material system comprising bis(fluorosulfonyl)imide heavy residue and an acidic aqueous solution, a fluorinated acid solution and crude aminosulfonic acid are obtained. The fluorinated acid solution can be used as a by-product acid, saving processing costs. The crude aminosulfonic acid can also be sold directly as a product, reducing processing costs and bringing economic benefits, thus realizing the resource-based recycling of bis(fluorosulfonyl)imide heavy residue. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] On one hand, the present invention provides a method for treating bis(fluorosulfonyl)imide heavy residue, comprising the following steps:

[0022] The raw material system, consisting of bis(fluorosulfonyl)imide heavy residue and acidic aqueous solution, is reacted to obtain a fluorinated acid solution and crude aminosulfonic acid.

[0023] The bis(fluorosulfonyl)imide heavy residue in this invention refers to the heavy residue generated during the purification process of bis(fluorosulfonyl)imide raw material. Its main components are bis(fluorosulfonyl)imide and its trace salts, as well as fluorosulfonic acid and its trace salts. In the bis(fluorosulfonyl)imide heavy residue, the proportion of bis(fluorosulfonyl)imide and fluorosulfonic acid is more than 95%. The bis(fluorosulfonyl)imide heavy residue is a viscous liquid with extremely poor fluidity. Currently, there is no existing technology that can utilize bis(fluorosulfonyl)imide resources.

[0024] This invention generates fluorosulfonic acid, aminosulfonic acid, and hydrogen fluoride by reacting a raw material system comprising bis(fluorosulfonyl)imide heavy residue and an acidic aqueous solution. The reaction principle is shown in Formula 1.

[0025]

[0026] Specifically, the acidic aqueous solution dissolves the heavy sludge of difluorosulfonylimide, dispersing it in the solution and allowing it to react fully with the water. The resulting fluorosulfonic acid is a liquid phase that dissolves directly in the acidic aqueous solution. The generated hydrogen fluoride further dissolves in the acidic aqueous solution to form acid. A very small amount of hydrogen fluoride may overflow from the system; optionally, the hydrogen fluoride tail gas can be treated with an alkaline solution. The generated aminosulfonic acid is a solid phase that forms a precipitate in the raw material system and can be separated from the liquid by filtration.

[0027] This invention provides a method for processing bis(fluorosulfonyl)imide heavy residue. By reacting a raw material system comprising bis(fluorosulfonyl)imide heavy residue and an acidic aqueous solution, a fluorinated acid solution and crude aminosulfonic acid are obtained. The fluorinated acid solution can be used as a by-product acid, saving processing costs. The crude aminosulfonic acid can also be sold directly as a product, reducing processing costs and bringing economic benefits, thus realizing the resource-based recycling of bis(fluorosulfonyl)imide heavy residue.

[0028] Furthermore, the raw material system can be tested by ion chromatography. When the anion content of difluorosulfonyl imide in the raw material system is 0, it can be determined that the reaction is complete, and at this time, difluorosulfonyl imide has been completely converted.

[0029] The above reaction is carried out by adding the heavy residue of difluorosulfonamide to an acidic aqueous solution for a feeding time of 0.5-3 hours.

[0030] By adding the bis(fluorosulfonyl)imide heavy residue to an acidic aqueous solution and further limiting the feeding time to 0.5-3 hours, it is beneficial to control the reaction rate, ensure the reaction proceeds fully, and further improve the safety of the treatment method provided by the present invention.

[0031] This invention does not limit the specific type of acidic aqueous solution; any acidic aqueous solution capable of dissolving and dispersing the bis(fluorosulfonyl)imide heavy residue in the raw material system is acceptable.

[0032] Furthermore, the acidic aqueous solution is at least one of sulfuric acid aqueous solution, nitric acid aqueous solution, and hydrochloric acid aqueous solution.

[0033] The inventors discovered that when the acidic aqueous solution is sulfuric acid, nitric acid, or hydrochloric acid, it can promote the complete reaction of the difluorosulfonamide heavy residue. Furthermore, when the acidic aqueous solution is sulfuric acid, the safety of the treatment method can be further improved, the reaction process is more gentle, and the introduction of other impurities and the generation of other by-products can be further avoided.

[0034] Specifically, the acid content in the acidic aqueous solution is 50-98% by mass.

[0035] It is understandable that using a concentrated acid solution is more conducive to the dissolution and dispersion of the bis(fluorosulfonyl)imide heavy residue. When the mass percentage of acid in the acidic aqueous solution is 50-98%, it can further promote the reaction and is more conducive to the dissolution of the generated hydrogen fluoride to form fluorosulfonic acid.

[0036] Optionally, the mass ratio of the bis(fluorosulfonyl)imide heavy residue to the acidic aqueous solution is 1:(1-10).

[0037] The mass ratio of bis(fluorosulfonyl)imide heavy residue to acidic aqueous solution is an important factor affecting the reaction. Through research, the inventors found that when the mass ratio of bis(fluorosulfonyl)imide heavy residue to acidic aqueous solution is 1:(1-10), the reaction can be further promoted to proceed fully, so that the bis(fluorosulfonyl)imide heavy residue can react completely, thereby further improving the resource utilization of the treatment method.

[0038] In one specific embodiment, the reaction temperature is 30-100°C;

[0039] By further limiting the reaction temperature of the treatment method, the reaction rate can be further controlled, thus promoting the reaction.

[0040] In another specific embodiment, the reaction time is 1-10 hours;

[0041] It is understandable that reaction time is an important factor in chemical reactions. The inventors discovered that by further limiting the reaction time to 1-10 hours, the extent of the reaction and the amount of products generated can be further controlled, which is more conducive to the resource utilization of difluorosulfonyl imide.

[0042] Optionally, the reaction is accompanied by stirring at a speed of 100-500 rpm;

[0043] To promote mixing and diffusion among the reactants and to ensure that bis(fluorosulfonyl)imide is more uniformly dispersed in the raw material system for reaction, the stirring speed can be further limited to 100-500 rpm.

[0044] Furthermore, it also includes:

[0045] The crude aminosulfonic acid was leached with an acidic washing solution to obtain the aminosulfonic acid product and the acidic solution after leaching.

[0046] After the reaction is complete, a fluorinated acid solution and crude aminosulfonic acid will be obtained. In order to further separate the products and make better use of resources, an acidic washing solution can be used to rinse the crude aminosulfonic acid to remove the residual fluorinated acid in the crude aminosulfonic acid, so as to obtain aminosulfonic acid product and acid solution after rinsing.

[0047] The acidic washing solution used in the rinsing process is used to remove residual fluoride ions from the crude aminosulfonic acid. The acidic washing solution can be at least one of sulfuric acid aqueous solution, nitric acid aqueous solution, and hydrochloric acid aqueous solution. The acidic washing solution used in the rinsing process can be the same type as or different from the acidic aqueous solution in the above reaction. When the acidic washing solution used in the rinsing process is the same type as the acidic aqueous solution in the above reaction, no other impurities will be introduced, which is beneficial for further recovery of fluoride from the acidic solution after rinsing.

[0048] Specifically, after the reaction is complete, the mixture is filtered, and the solid-phase aminosulfonic acid filter cake is washed several times with an acidic aqueous solution to obtain aminosulfonic acid product and acid solution after washing. Optionally, the acid solution after washing can be detected by ion chromatography to determine whether the solid-phase aminosulfonic acid product contains fluorine. Through washing treatment, fluorine-free aminosulfonic acid product can be obtained, improving the recycling value of the product and facilitating better resource utilization of difluorosulfonylimide.

[0049] It is understood that aminosulfonic acid products contain a small amount of acidic washing liquid and impurities, therefore the mass fraction of aminosulfonic acid in aminosulfonic acid products is 70-95%. Therefore, it is possible to purify aminosulfonic acid products. This invention does not limit the purification method of aminosulfonic acid products. This method is a commonly used method in the field and will not be described in detail here. Taking sulfuric acid as an example of acidic washing liquid, optionally, taking advantage of the solubility characteristics of aminosulfonic acid itself, fluorinated sulfuric acid is prepared into a sulfuric acid solution with a concentration of 71.8%. Based on the principle that the solubility of aminosulfonic acid in a 71.8% sulfuric acid solution is '0', aminosulfonic acid is precipitated out, achieving the purpose of separation from sulfuric acid.

[0050] In one specific embodiment, the rinsing treatment is performed 3-8 times;

[0051] In another specific embodiment, during the rinsing process, the amount of acidic washing solution used is 1-5 times the mass of the difluorosulfonylimide heavy slag.

[0052] The process involves using an acidic washing solution for rinsing to remove fluorosulfonic acid from the aminosulfonic acid product. When the number of rinsing cycles is further limited to 3-8 times, and / or the amount of acidic washing solution used is 1-5 times the mass of the difluorosulfonylimide residue, fluorine in the difluorosulfonylimide can be further removed, resulting in fluorine-free aminosulfonic acid.

[0053] In one embodiment, the method further includes using at least one of the fluorinated acid solution and the rinsed acid solution as a raw material in the preparation of phosphorus pentafluoride.

[0054] Since both the fluorinated acid solution obtained from the reaction and the acid solution obtained after rinsing contain fluorine, they can be used as byproducts in the production of phosphorus pentafluoride, further improving the resource utilization of difluorosulfonyl imide and reducing processing costs.

[0055] The following detailed description of a method for treating bis(fluorosulfonyl)imide heavy residue provided by the present invention is provided through specific embodiments.

[0056] Example 1

[0057] (1) Add 300g of 95% sulfuric acid aqueous solution to a 500ml PTFE three-necked reaction flask, and then add 100g of bis(fluorosulfonyl)imide heavy residue to the above three-necked reaction flask at the same rate. Place the flask in an 80℃ constant temperature magnetic heating stirrer and start stirring to carry out the reaction at a speed of 200rpm. The tail gas is absorbed by the alkaline solution. When the anion content in the raw material system is 0, the reaction is stopped. After filtration, a fluorinated acid solution and crude aminosulfonic acid are obtained.

[0058] (2) The crude aminosulfonic acid was rinsed three times with 100g of 95% sulfuric acid washing solution to obtain the aminosulfonic acid product and the acid solution after rinsing.

[0059] Example 2

[0060] The difference between this embodiment and Embodiment 1 is that the concentration of the sulfuric acid aqueous solution is 70%.

[0061] Example 3

[0062] The difference between this embodiment and Embodiment 1 is that the concentration of the sulfuric acid aqueous solution is 50%.

[0063] Example 4

[0064] The difference between this embodiment and embodiment 1 is that in step (1), 500g of sulfuric acid aqueous solution is added.

[0065] Example 5

[0066] The difference between this embodiment and embodiment 1 is that in step (1), 800g of sulfuric acid aqueous solution is added.

[0067] Example 6

[0068] The difference between this embodiment and embodiment 1 is that in step (1), 1000g of sulfuric acid aqueous solution is added.

[0069] Example 7

[0070] The difference between this embodiment and embodiment 1 is that the reaction temperature in step (1) is 30°C.

[0071] Example 8

[0072] The difference between this embodiment and embodiment 1 is that the reaction temperature in step (1) is 70°C.

[0073] Example 9

[0074] The difference between this embodiment and embodiment 1 is that the reaction temperature in step (1) is 100°C.

[0075] Example 10

[0076] The difference between this embodiment and embodiment 1 is that in step (2), the number of rinses is 5.

[0077] Example 11

[0078] The difference between this embodiment and embodiment 1 is that in step (2), the number of rinses is 7.

[0079] Example 12

[0080] The difference between this embodiment and embodiment 1 is that in step (2), the number of rinses is 8.

[0081] Example 13

[0082] The difference between this embodiment and embodiment 1 is that in step (2), 300g of sulfuric acid washing solution is added during the rinsing process.

[0083] Example 14

[0084] The difference between this embodiment and embodiment 1 is that in step (2), 500g of sulfuric acid washing solution is added during the rinsing process.

[0085] Example 15

[0086] The difference between this embodiment and Embodiment 1 is that the concentration of the sulfuric acid aqueous solution is 45%.

[0087] Example 16

[0088] The difference between this embodiment and embodiment 1 is that in step (1), 50g of sulfuric acid aqueous solution is added.

[0089] Example 17

[0090] The difference between this embodiment and embodiment 1 is that the reaction temperature in step (1) is 20°C.

[0091] Example 18

[0092] The difference between this embodiment and embodiment 1 is that in step (2), the number of rinses is 6.

[0093] Example 19

[0094] The difference between this embodiment and embodiment 1 is that in step (2), 50g of sulfuric acid washing solution is added during the rinsing process.

[0095] Example 20

[0096] The difference between this embodiment and Embodiment 1 is that both the acidic aqueous solution and the acidic washing solution are 95% nitric acid aqueous solutions.

[0097] Example 21

[0098] The difference between this embodiment and embodiment 1 is that step (2) is omitted.

[0099] Example 22

[0100] The difference between this embodiment and Example 1 is that the concentration of the sulfuric acid aqueous solution is 98%; in step (1), 500g of sulfuric acid aqueous solution is added, the reaction temperature is 90℃, and the reaction time is 1h; in step (2), the number of rinsing times is 1.

[0101] Example 23

[0102] The difference between this embodiment and embodiment 1 is that the concentration of the sulfuric acid aqueous solution is 90%; in step (1), 800g of sulfuric acid aqueous solution is added, the reaction temperature is 100℃, and the reaction time is 4h; in step (2), the number of rinsing times is 3.

[0103] Example 24

[0104] The difference between this embodiment and Example 1 is that the concentration of the sulfuric acid aqueous solution is 85%; in step (1), 1000g of sulfuric acid aqueous solution is added, the reaction temperature is 90℃, and the reaction time is 6h; in step (2), the number of rinsing times is 5.

[0105] Example 25

[0106] The difference between this embodiment and Example 1 is that the concentration of the sulfuric acid aqueous solution is 80%; in step (1), 1000g of sulfuric acid aqueous solution is added, the reaction temperature is 90℃, and the reaction time is 10h; in step (2), the number of rinsing times is 2.

[0107] Example 26

[0108] The difference between this embodiment and Example 1 is that the concentration of the sulfuric acid aqueous solution is 70%; in step (1), 600g of sulfuric acid aqueous solution is added, the reaction temperature is 70℃, and the reaction time is 2h; in step (2), the number of rinsing times is 2.

[0109] Example 27

[0110] The difference between this embodiment and Example 1 is that the concentration of the sulfuric acid aqueous solution is 60%; in step (1), 400g of sulfuric acid aqueous solution is added, the reaction temperature is 80℃, and the reaction time is 3h; in step (2), the number of rinsing times is 2.

[0111] Example 28

[0112] The difference between this embodiment and Example 1 is that the concentration of the sulfuric acid aqueous solution is 50%; in step (1), 300g of sulfuric acid aqueous solution is added, the reaction temperature is 60℃, and the reaction time is 5h; in step (2), the number of rinsing times is 2.

[0113] Example 29

[0114] The difference between this embodiment and Embodiment 1 is that the reaction temperature is 120℃.

[0115] Experimental Example 1

[0116] The content of bis(fluorosulfonyl)imide anions in the bis(fluorosulfonyl)imide residue was determined by ion chromatography to obtain the bis(fluorosulfonyl)imide content. Then, the content of aminosulfonate in the aminosulfonic acid product obtained in the above examples was determined by ion chromatography. The content was compared with the theoretical amount of aminosulfonic acid from the complete reaction of bis(fluorosulfonyl)imide to calculate the recovery rate of the bis(fluorosulfonyl)imide residue.

[0117] The content of aminosulfonate in the aminosulfonic acid product was detected by ion chromatography, and the mass fraction of the aminosulfonic acid product was calculated. The experimental parameters and results in the above examples are shown in Table 1.

[0118] The amounts of acidic aqueous solutions used are multiples of the mass of the acidic aqueous solution and the heavy residue of difluorosulfonyl imide; the concentration of acidic aqueous solution indicates the mass percentage of acid in the acidic aqueous solution and acidic washing solution; since aminosulfonic acid products may contain a small amount of acidic aqueous solution and impurities, the mass fraction of aminosulfonic acid products indicates the mass percentage of aminosulfonic acid in them.

[0119] Table 1

[0120]

[0121]

[0122] As shown in the table, the method for treating bis(fluorosulfonyl)imide heavy residue provided by this invention, by reacting a raw material system including bis(fluorosulfonyl)imide heavy residue and an acidic aqueous solution, can obtain a fluorinated acid solution that can be used as a by-product acid, and the aminosulfonic acid product can also be directly sold as a product, reducing processing costs and realizing the resource-based recycling of bis(fluorosulfonyl)imide heavy residue. Specifically, the reaction time can be controlled by adjusting factors such as the concentration, amount, and reaction time of the acidic aqueous solution to improve the processing effect, or the requirements for reaction time and product purity can be reduced to decrease the amount of raw materials used and the energy consumption of the reaction.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for treating bis(fluorosulfonyl)imide heavy residue, characterized in that, Includes the following steps: The raw material system, consisting of bis(fluorosulfonyl)imide heavy residue and acidic aqueous solution, is reacted to obtain a fluorinated acid solution and crude aminosulfonic acid.

2. The processing method according to claim 1, characterized in that, The bis(fluorosulfonyl)imide heavy residue is added to the acidic aqueous solution to carry out the reaction, and the addition time is 0.5-3 hours.

3. The processing method according to claim 1 or 2, characterized in that, The acidic aqueous solution is at least one of sulfuric acid aqueous solution, nitric acid aqueous solution and hydrochloric acid aqueous solution.

4. The processing method according to any one of claims 1-3, characterized in that, The acidic aqueous solution contains 50-98% acid by mass.

5. The processing method according to any one of claims 1-4, characterized in that, The mass ratio of the difluorosulfonylimide heavy residue to the acidic aqueous solution is 1:(1-10).

6. The processing method according to any one of claims 1-5, characterized in that, The reaction temperature is 30-100℃; and / or, The reaction time is 1-10 hours.

7. The processing method according to any one of claims 1-6, characterized in that, The reaction is accompanied by stirring at a speed of 100-500 rpm.

8. The processing method according to any one of claims 1-7, characterized in that, Also includes: The crude aminosulfonic acid was leached with an acidic washing solution to obtain the aminosulfonic acid product and the leached acid solution.

9. The processing method according to claim 8, characterized in that, The rinsing treatment is performed 3-8 times; and / or, In the rinsing process, the amount of acidic washing solution used is 1-5 times the mass of the difluorosulfonyl imide heavy slag.

10. The processing method according to claim 8 or 9, characterized in that, Also includes: At least one of the fluorinated acid solution and the rinsed acid solution is used as a raw material in the preparation of phosphorus pentafluoride.

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