Preparation method of bis(fluorosulfonyl)imide

Abstract

The present application relates to a method for preparing bisfluorosulfonyl imide, comprising the following steps: subjecting bischlorosulfonyl imide and hydrogen fluoride to a primary fluorination reaction, wherein the initial molar ratio of the bischlorosulfonyl imide to the hydrogen fluoride is 1:0.4 to 1:1.9, to obtain a fluorination reaction liquid; subjecting the fluorination reaction liquid to a final fluorination reaction with hydrogen fluoride, wherein the initial molar ratio of the bischlorosulfonyl imide to the hydrogen fluoride in the fluorination reaction liquid is ≤1:2, to obtain bisfluorosulfonyl imide. The preparation method subjects bischlorosulfonyl imide to a multi-stage fluorination reaction with hydrogen fluoride, wherein in the primary fluorination reaction, an excess of bischlorosulfonyl imide is subjected to a fluorination reaction with a small amount of hydrogen fluoride, and in the final fluorination reaction, a bischlorosulfonyl imide in the fluorination reaction liquid is subjected to a fluorination reaction with an excess of hydrogen fluoride, thereby improving the purity and yield of the bisfluorosulfonyl imide and realizing continuous production.

Description

Technical Field

[0001] The present application relates to the technical field of chemical synthesis, and in particular to a method for preparing bis(fluorosulfonyl)imide. Background Art

[0002] High-purity lithium bis(fluorosulfonyl)imide (LiFSI) has excellent conductivity and high thermal stability without decomposition below 200°C. It is considered to be a new type of fluorine-containing lithium salt that may become the main component of the next generation electrolyte because its chemical stability is better than that of the current mainstream lithium battery electrolyte lithium hexafluorophosphate (LiPF6). The most critical step in the preparation of high-purity lithium bis(fluorosulfonyl)imide is to prepare high-purity synthetic intermediate bis(fluorosulfonyl)imide (HFSI). However, the bis(fluorosulfonyl)imide obtained by traditional synthesis methods has low purity, is difficult to purify, and has a long reaction time, making it difficult to achieve continuous production. Summary of the invention

[0003] Based on this, it is necessary to provide a method for preparing bisfluorosulfonyl imide, which has high purity, short reaction time and can realize continuous production.

[0004] In one aspect of the present application, a method for preparing bis(fluorosulfonyl)imide is provided, comprising the following steps:

[0005] Carrying out a primary fluorination reaction between bischlorosulfonyl imide and hydrogen fluoride, wherein the initial molar ratio of the bischlorosulfonyl imide to the hydrogen fluoride is 1:0.4 to 1:1.9, to obtain a fluorination reaction liquid;

[0006] The fluorination reaction liquid is subjected to a final fluorination reaction with hydrogen fluoride, wherein the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride in the fluorination reaction liquid is ≤1:2, and bisfluorosulfonyl imide is obtained.

[0007] The preparation method controls the feed molar ratio of bischlorosulfonyl imide to hydrogen fluoride, and conducts a multi-stage fluorination reaction between bischlorosulfonyl imide and hydrogen fluoride, reduces the amount of hydrogen fluoride in the primary fluorination reaction, and conducts a fluorination reaction between excess bischlorosulfonyl imide and a small amount of hydrogen fluoride, wherein the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride in the primary fluorination reaction is 1:0.4-1:1.9, and after the primary fluorination reaction at this ratio, the system no longer contains or substantially does not contain hydrogen fluoride, and only produces hydrogen chloride gas, thereby eliminating the need for a fluorination reaction. The hydrogen fluoride separation and recovery step is eliminated, and hydrogen chloride can be directly absorbed by water to form a hydrochloric acid solution with a higher purity; in the final fluorination reaction, the bischlorosulfonyl imide in the fluorination reaction liquid is subjected to a fluorination reaction with excess hydrogen fluoride, so that the bischlorosulfonyl imide in the fluorination reaction liquid is completely converted into bisfluorosulfonyl imide, thereby improving the purity and yield of bisfluorosulfonyl imide, and also eliminating the condensation recovery steps and equipment required for condensing a large amount of hydrogen fluoride in the traditional process, thereby improving production efficiency and also improving the purity of the by-product hydrochloric acid. The remaining hydrogen fluoride after the reaction can also be directly recycled to the primary fluorination reaction, which not only realizes continuous production, but also reduces pollution and raw material loss, and further improves the yield of bisfluorosulfonyl imide.

[0008] The above preparation method has a more thorough reaction, a high raw material conversion rate, and a high purity of the synthesized bis(fluorosulfonyl)imide. The above preparation method has a high reaction mass transfer and heat transfer efficiency, and a short reaction time, which can be shortened from 24h~48h of the traditional process to 5~8h. The above preparation method can be converted from an intermittent reaction to a continuous reaction, and the product can be continuously fed and discharged after meeting the detection requirements, with a high safety factor.

[0009] In some embodiments, in the primary fluorination reaction, the initial molar ratio of the bischlorosulfonyl imide to the hydrogen fluoride is 1:0.8 to 1:1.1.

[0010] In some embodiments, in the final fluorination reaction, the initial molar ratio of bis(chlorosulfonyl)imide to hydrogen fluoride in the fluorination reaction solution is 1:2 to 1:8.

[0011] In some embodiments, the mass content of monofluoromonochlorosulfonyl imide in the fluorination reaction solution before the final fluorination reaction is controlled to be ≤10%, and / or the mass content of bisfluorosulfonyl imide is controlled to be ≥90%.

[0012] In some embodiments, the mass content of monofluorochlorosulfonyl imide in the fluorination reaction liquid obtained by the final fluorination reaction is controlled to be ≤100 ppm.

[0013] In some embodiments, the primary fluorination reaction is performed twice or more in sequence;

[0014] In the first primary fluorination reaction, bischlorosulfonyl imide and hydrogen fluoride are subjected to a fluorination reaction, wherein the initial molar ratio of the bischlorosulfonyl imide to the hydrogen fluoride is 1:0.4 to 1:1.9, to obtain a first fluorination reaction liquid;

[0015] In the second primary fluorination reaction, the first fluorination reaction liquid is subjected to a fluorination reaction with hydrogen fluoride, and the initial molar ratio of the bischlorosulfonyl imide in the first fluorination reaction liquid to the hydrogen fluoride is 1:0.8-1:1.9.

[0016] In some embodiments, the mass content of monofluoromonochlorosulfonyl imide in the first fluorination reaction solution is controlled to be ≥60%, and / or the mass content of bischlorosulfonyl imide is controlled to be ≤40%.

[0017] In some embodiments, the ratio of the total mole of bischlorosulfonyl imide added in the primary fluorination reaction and the final fluorination reaction to the total mole of hydrogen fluoride is 1:2-1:8.

[0018] In some embodiments, the reaction temperature of the primary fluorination reaction and the final fluorination reaction are both 60°C to 150°C.

[0019] In some embodiments, the hydrogen fluoride obtained after the final fluorination reaction is recycled to the primary fluorination reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a schematic diagram of the structure of a device for preparing bis(fluorosulfonyl)imide according to one embodiment.

[0021] Description of reference numerals:

[0022] 1. First fluorination reactor; 2. Intermediate fluorination reactor; 3. Final fluorination reactor; 4. Distillation unit; 5. Rectification unit; 6. Tail gas absorption unit. DETAILED DESCRIPTION

[0023] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to relevant embodiments. Preferred embodiments of the present invention are given below, but the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0025] The traditional preparation method of bisfluorosulfonyl imide is to synthesize bisfluorosulfonyl imide by reacting fluorosulfonyl isocyanate or urea with fluorosulfonic acid. The bisfluorosulfonyl imide obtained by this process is usually contaminated by excess fluorosulfonic acid, and the boiling points of bisfluorosulfonyl imide and fluorosulfonic acid are close, which makes purification difficult and costly. Therefore, at present, bischlorosulfonyl imide (HClSI) is usually synthesized first, and then bischlorosulfonyl imide and a fluorination agent are subjected to a fluorine-chlorine exchange reaction to obtain bisfluorosulfonyl imide. The process for synthesizing bisfluorosulfonyl imide is usually to first add bischlorosulfonyl imide to the reactor, and then continuously introduce excess hydrogen fluoride into the reactor. After the reaction is completed, the crude bisfluorosulfonyl imide is obtained by a light removal process. However, during the reaction, the intermediate product monofluoro-chlorosulfonyl imide is difficult to be completely converted into bisfluorosulfonyl imide, resulting in an extremely long reaction time, low product purity, and difficulty in purification. A large amount of hydrogen fluoride is required. If hydrogen fluoride needs to be recovered and reused, the problem of separation from hydrogen chloride needs to be solved, which makes it difficult to achieve continuous production. The researchers tried to pre-mix bischlorosulfonyl imide and excess hydrogen fluoride and then pass them into a tubular reactor for reaction, and then pass them into a reactor for reaction. After the reaction was completed, the crude bischlorosulfonyl imide was obtained through a light removal process. However, in the later stage of the reaction in the reactor, the mass transfer and heat transfer were poor and the reaction rate was extremely slow, which made the process reaction time long and the product purity low. The excess hydrogen fluoride and the generated hydrogen chloride were mixed together and difficult to separate, and the hydrogen fluoride could not be recovered and reused. The consumption of hydrogen fluoride was large, and it was difficult to achieve continuous production. If you want to produce lithium bisfluorosulfonyl imide products that meet battery-grade standards, the quality of bisfluorosulfonyl imide is the key. Therefore, it is urgent to develop a method for preparing bisfluorosulfonyl imide that has a thorough reaction, short reaction time, high product purity, and can be industrialized.

[0026] Based on this, the present application provides a method for preparing bis(fluorosulfonyl)imide, comprising the following steps:

[0027] Carrying out a primary fluorination reaction between bischlorosulfonyl imide and hydrogen fluoride, wherein the initial molar ratio of the bischlorosulfonyl imide to the hydrogen fluoride is 1:0.4 to 1:1.9, to obtain a fluorination reaction liquid;

[0028] The fluorination reaction liquid is subjected to a final fluorination reaction with hydrogen fluoride, wherein the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride in the fluorination reaction liquid is ≤1:2, and bisfluorosulfonyl imide is obtained.

[0029] The preparation method controls the feed molar ratio of bischlorosulfonyl imide to hydrogen fluoride, and conducts a multi-stage fluorination reaction between bischlorosulfonyl imide and hydrogen fluoride, reduces the amount of hydrogen fluoride in the primary fluorination reaction, and conducts a fluorination reaction between excess bischlorosulfonyl imide and a small amount of hydrogen fluoride, wherein the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride in the primary fluorination reaction is 1:0.4-1:1.9, and after the primary fluorination reaction at this ratio, the system no longer contains or substantially does not contain hydrogen fluoride, and only produces hydrogen chloride gas, thereby eliminating the need for a fluorination reaction. The hydrogen fluoride separation and recovery step is eliminated, and hydrogen chloride can be directly absorbed by water to form a hydrochloric acid solution with a higher purity; in the final fluorination reaction, the bischlorosulfonyl imide in the fluorination reaction liquid is subjected to a fluorination reaction with excess hydrogen fluoride, so that the bischlorosulfonyl imide in the fluorination reaction liquid is completely converted into bisfluorosulfonyl imide, thereby improving the purity and yield of bisfluorosulfonyl imide, and also eliminating the condensation recovery steps and equipment required for condensing a large amount of hydrogen fluoride in the traditional process, thereby improving production efficiency and also improving the purity of the by-product hydrochloric acid. The remaining hydrogen fluoride after the reaction can also be directly recycled to the primary fluorination reaction, which not only realizes continuous production, but also reduces pollution and raw material loss, and further improves the yield of bisfluorosulfonyl imide.

[0030] The above preparation method has a more thorough reaction, a high raw material conversion rate, and a high purity of the synthesized bis(fluorosulfonyl)imide. The above preparation method has a high reaction mass transfer and heat transfer efficiency, and a short reaction time, which can be shortened from 24h~48h of the traditional process to 5~8h. The above preparation method can be converted from an intermittent reaction to a continuous reaction, and the product can be continuously fed and discharged after meeting the detection requirements, with a high safety factor.

[0031] As an example, in the primary fluorination reaction, the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride can be 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, 1.25, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8 and 1:1.9, or it can be within the range formed by any two of the above point values ​​as end values.

[0032] Furthermore, in the primary fluorination reaction, the preferred initial molar ratio of bis(chlorosulfonyl)imide to hydrogen fluoride is 1:0.8 to 1:1.1. The yield of bis(fluorosulfonyl)imide obtained at this ratio is higher, reaching more than 95%; the bis(fluorosulfonyl)imide obtained at this ratio has better quality and higher purity, meeting the production requirements of bis(fluorosulfonyl)imide lithium products of battery grade standards.

[0033] Furthermore, in the primary fluorination reaction, the preferred initial molar ratio of bis(chlorosulfonyl)imide to hydrogen fluoride is 1:0.9 to 1:1.1. The yield of bis(fluorosulfonyl)imide obtained at this ratio is higher, up to more than 98%; the bis(fluorosulfonyl)imide obtained at this ratio has better quality, higher purity, and shorter production time.

[0034] As an example, in the final stage fluorination reaction, the initial molar ratio of bis(chlorosulfonyl)imide to hydrogen fluoride in the fluorination reaction liquid can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5.0, 1:5.5, 1:6.0, 1:7.0, 1:8.0, 1:9.0, 1:10, or can be within the range consisting of any two of the above point values ​​as end values.

[0035] In some embodiments, in the final fluorination reaction, the initial molar ratio of bis(chlorosulfonyl)imide to hydrogen fluoride in the fluorination reaction solution is 1:2 to 1:8. The bis(fluorosulfonyl)imide obtained at this ratio has higher purity and yield, and the preparation time is shorter.

[0036] Furthermore, in the final fluorination reaction, the initial molar ratio of bis(chlorosulfonyl)imide to hydrogen fluoride in the fluorination reaction solution is 1:2 to 1:6. The bis(fluorosulfonyl)imide obtained at this ratio has higher purity and yield, shorter preparation time, is more conducive to directly recycling hydrogen fluoride to the primary fluorination reaction, reduces raw material loss, and further improves the yield of bis(fluorosulfonyl)imide.

[0037] Furthermore, in the final stage fluorination reaction, the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride in the fluorination reaction solution is preferably 1:3 to 1:5.

[0038] In some embodiments, the mass content of monofluoro-monochlorosulfonyl imide in the fluorination reaction solution before the final fluorination reaction is controlled to be ≤10%, and / or the mass content of bisfluorosulfonyl imide is ≥90%. The content of components in the fluorination reaction solution can be detected by ion chromatography.

[0039] It is understandable that the primary fluorination reaction can be carried out one or more times in sequence until most of the reaction solution is bis(fluorosulfonyl)imide and a small part is monofluoro-chlorosulfonylimide, and then excess hydrogen fluoride is added to carry out the final fluorination reaction.

[0040] In some embodiments, the mass content of monofluorochlorosulfonyl imide in the fluorination reaction liquid obtained by the final fluorination reaction is controlled to be ≤100 ppm.

[0041] In some embodiments, the primary fluorination reaction is performed twice or more in sequence;

[0042] In the first primary fluorination reaction, bischlorosulfonyl imide and hydrogen fluoride are subjected to a fluorination reaction, wherein the initial molar ratio of the bischlorosulfonyl imide to the hydrogen fluoride is 1:0.4 to 1:1.9, to obtain a first fluorination reaction liquid;

[0043] In the second primary fluorination reaction, the first fluorination reaction liquid is subjected to a fluorination reaction with hydrogen fluoride, and the initial molar ratio of the bischlorosulfonyl imide in the first fluorination reaction liquid to the hydrogen fluoride is 1:0.8-1:1.9.

[0044] As an example, in the first primary fluorination reaction, the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride can be 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, 1.25, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8 and 1:1.9, or it can be within the range of any two of the above point values ​​as end values. In the intermediate fluorination reaction, the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride in the first fluorination reaction solution is preferably 1:0.9 to 1:1.1.

[0045] As an example, in the second primary fluorination reaction, the initial molar ratio of the bischlorosulfonyl imide in the first fluorination reaction liquid to the hydrogen fluoride can be 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, 1.25, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8 and 1:1.9, or can be within the range of any two of the above point values ​​as end values. The initial molar ratio of the bischlorosulfonyl imide in the first fluorination reaction liquid to the hydrogen fluoride is preferably 1:1 to 1:1.5.

[0046] In some embodiments, the mass content of monofluoromonochlorosulfonyl imide in the first fluorination reaction solution is controlled to be ≥60%, and / or the mass content of bischlorosulfonyl imide is controlled to be ≤40%.

[0047] Understandably, the first fluorination reaction liquid obtained by the first primary fluorination reaction is mostly monofluoro-chlorosulfonyl imide, unreacted bischlorosulfonyl imide and hydrogen chloride obtained by the reaction. The second primary fluorination reaction is an intermediate fluorination reaction, and one or more intermediate fluorination reactions can be carried out after the first primary fluorination reaction, until most of the reaction liquid is bisfluorosulfonyl imide and a small part is monofluoro-chlorosulfonyl imide, and then excess hydrogen fluoride is added to carry out the final fluorination reaction. In the intermediate fluorination reaction, the molar ratio of bischlorosulfonyl imide to hydrogen fluoride is 1:0.8~1:1.9, and the preferred molar ratio is 1:1~1:1.5.

[0048] In some embodiments, the ratio of the total mole of bischlorosulfonyl imide added in the primary fluorination reaction and the final fluorination reaction to the total mole of hydrogen fluoride is 1:2-1:8.

[0049] As an example, the ratio of the total mole of bischlorosulfonyl imide added in the primary fluorination reaction and the final fluorination reaction to the total mole of hydrogen fluoride can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5.0, 1:5.5, 1:6.0, 1:6.5, 1:7.0, 1:7.5 and 1:8.0, or it can be within the range of any two of the above point values ​​as end values. The ratio of the total mole of bischlorosulfonyl imide added in the primary fluorination reaction and the final fluorination reaction to the total mole of hydrogen fluoride is preferably 1:2 to 1:5.

[0050] In some embodiments, the reaction temperature of the primary fluorination reaction is 60°C to 150°C.

[0051] In some embodiments, the reaction temperature of the final fluorination reaction is 60°C to 150°C.

[0052] As an example, the reaction temperature of the primary fluorination reaction or the final fluorination reaction can be 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C, 100°C, 101°C, 102°C, 103°C, 104°C, 105°C, 106°C, 107°C, 108°C, 109°C, 110°C, 111°C, 112°C, 113°C, 114°C, 115°C, 116°C, 117°C, 118°C, 119°C, 120°C, 121°C, 122°C, 123°C, 124°C, 125°C, 126°C, 127°C, 128°C, 129°C, 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, 139°C, 140°C, 141°C, 142°C, 143°C, 144°C, 145°C, 146°C, 147°C, 148°C, 149°C and 150°C can also be within the range consisting of any two of the above point values ​​as end values. The reaction temperature of the primary fluorination reaction or the final fluorination reaction is preferably 80°C to 130°C.

[0053] In some embodiments, the total reaction time of the first stage fluorination reaction and the final stage fluorination reaction is 5 h to 8 h.

[0054] In some embodiments, a purification step is also included, and the purification of bis(fluorosulfonyl)imide is carried out by distillation, the light fraction is hydrogen fluoride, the distillation temperature is 60-150°C, and the vacuum degree is -0.01MPa to -0.05MPa. The middle fraction is bis(fluorosulfonyl)imide, the distillation temperature is 60-150°C, and the vacuum degree is -0.05MPa to -0.1MPa. The heavy fraction is heavy slag, which is disposed of separately.

[0055] In some of the embodiments, the tail gas produced by the primary fluorination reaction is mainly hydrogen chloride, which can be directly absorbed by the tail gas system and then prepared into a by-product hydrochloric acid solution.

[0056] In some embodiments, the hydrogen fluoride obtained after the final fluorination reaction is recycled to the primary fluorination reaction. Excess hydrogen fluoride in the final fluorination reaction can be directly recycled to the primary fluorination reaction, so that the preparation method of the present application further realizes continuous production.

[0057] In some embodiments, the hydrogen fluoride obtained after the final fluorination reaction is recycled to the first primary fluorination reaction.

[0058] In some embodiments, see Figure 1 The bis(fluorosulfonyl)imide preparation equipment comprises a first fluorination reactor 1, an intermediate fluorination reactor 2 and a final fluorination reactor 3 which are connected in series in sequence; the discharge port of the first fluorination reactor 1 is connected to the feed port of the intermediate fluorination reactor 2, the discharge port of the intermediate fluorination reactor 2 is connected to the feed port of the final fluorination reactor 3, the discharge port of the final fluorination reactor 3 is connected to a distillation device 4, and the distillation device 4 is connected to a rectification device 5; the first fluorination reactor 1, the intermediate fluorination reactor 2 and the final fluorination reactor 3 are respectively provided with a raw gas inlet for introducing hydrogen fluoride.

[0059] Furthermore, the first fluorination reactor 1, the intermediate fluorination reactor 2 and the final fluorination reactor 3 are respectively connected to a tail gas absorption device 6. The tail gas absorption device 6 is used to absorb the by-product hydrochloric acid by using water to absorb the hydrogen chloride gas.

[0060] Furthermore, all levels of equipment must be resistant to corrosive substances such as hydrogen fluoride and hydrogen chloride, can be sampled, and have the same output per hour.

[0061] It is understood that the first fluorination reactor 1 and the final fluorination reactor 3 require excellent mass transfer and heat transfer, and the reaction speed is very fast, and continuous reaction can be carried out. Microchannel reactors and tubular reactors can be used; the intermediate fluorination reactor 2 requires a large capacity and better mass transfer and heat transfer, and a reaction kettle can be used; when used in combination in this way, the first fluorination reactor 1 and the intermediate fluorination reactor 2 have a very fast reaction speed after being used in combination, and continuous reaction can be carried out. At the same time, the capacity is large, but the reaction is not thorough, the purity of the reactants is not high, or the reaction time is sharply increased. When the final fluorination reactor 3 is added for reaction, due to the excellent mass transfer and heat transfer, the reaction can be quickly reacted to reach the target purity.

[0062] In some embodiments, the intermediate fluorination reactor 2 is a plurality of fluorination reactors connected in series.

[0063] In some of the embodiments, the first fluorination reactor, the intermediate fluorination reactor and the final fluorination reactor may all be tubular reactors, microchannel reactors or reactors.

[0064] In some embodiments, the tubular reactor includes at least one of a horizontal tubular reactor, a single-pass vertical tubular reactor, a coiled tubular reactor, a serpentine tubular reactor, a U-shaped tubular reactor, and a multi-tube parallel tubular reactor.

[0065] Furthermore, the diameter of the tubular reactor is 0.1m-1.0m, and the length of the pipeline is 0.5m-20m. The tubular reactor can be equipped with a stirring device.

[0066] In some embodiments, the fluorination continuous reactor adopts a monolithic microchannel reactor or a layered microchannel reactor.

[0067] Furthermore, the flow rate index of the microchannel reactor is 0.01 L / min ~10 L / min.

[0068] In some embodiments, the fluorination continuous reactor is a vertical reactor having a diameter of 0.1 m to 2.0 m and a volume of 0.05 m 3 ~20m 3 .

[0069] In some embodiments, the tail gas outlet of the final fluorination reactor 3 is connected to the feed gas inlet of the first fluorination reactor 1 .

[0070] In some embodiments, the first fluorination reactor 1 adopts an integral microchannel reactor, the intermediate fluorination reactor 2 adopts a fluorine-lined reactor, and the final fluorination reactor 3 adopts a horizontal tubular reactor. The combination of the microchannel reactor and the reactor has a fast reaction speed, can react continuously, and has a large capacity at the same time.

[0071] In some embodiments, the first fluorination reactor 1 is a monolithic microchannel reactor, the intermediate fluorination reactor 2 is a fluorine-lined reactor, and the final fluorination reactor 3 is a coil reactor.

[0072] In some embodiments, the first fluorination reactor 1 is a dynamic tubular reactor, the intermediate fluorination reactor 2 is a fluorine-lined reactor, and the final fluorination reactor 3 is a coil reactor.

[0073] In some embodiments, the first fluorination reactor 1 is a dynamic tubular reactor, the intermediate fluorination reactor 2 is a fluorine-lined reactor, and the final fluorination reactor 3 is an integral microchannel reactor.

[0074] In some embodiments, bischlorosulfonimide is introduced by a metering pump.

[0075] The following are specific embodiments.

[0076] Example 1

[0077] use Figure 1 The preparation equipment shown includes a first fluorination reactor 1, an intermediate fluorination reactor 2 and a final fluorination reactor 3 connected in series; the discharge port of the first fluorination reactor 1 is connected to the feed port of the intermediate fluorination reactor 2, the discharge port of the intermediate fluorination reactor 2 is connected to the feed port of the final fluorination reactor 3, the discharge port of the final fluorination reactor 3 is connected to a distillation device 4, and the distillation device 4 is connected to a rectification device 5; the first fluorination reactor 1, the intermediate fluorination reactor 2 and the final fluorination reactor 3 are respectively provided with a raw gas inlet for introducing hydrogen fluoride. The first fluorination reactor 1, the intermediate fluorination reactor 2 and the final fluorination reactor 3 are respectively connected to a tail gas absorption device 6. Among them, the first fluorination reactor 1 adopts an integral structure microchannel reactor, the intermediate fluorination reactor 2 adopts a fluorine-lined reactor, and the final fluorination reactor 3 adopts a horizontal tubular reactor.

[0078] A method for preparing bisfluorosulfonyl imide, comprising the following specific steps:

[0079] The first primary fluorination reaction: 107 g (0.5 mol) of bischlorosulfonyl imide and 8 g (0.4 mol) of anhydrous hydrogen fluoride are continuously introduced into a monolithic microchannel reactor which has been replaced with an inert gas at least three times beforehand, and the reaction temperature is maintained at 90°C. The water in the reaction tail gas is absorbed as a by-product of hydrochloric acid; wherein, in the reaction liquid after the reaction, the mass content of monofluorochlorosulfonyl imide is ≥60%, and the mass content of bischlorosulfonyl imide is ≤40%;

[0080] Second primary fluorination reaction: put the reaction liquid of the first primary fluorination reaction into a 500mL fluorine-lined reactor for reaction, and continuously introduce 10g (0.5mol) of anhydrous hydrogen fluoride into the 500mL fluorine-lined reactor for reaction for 5 hours, maintaining the reaction temperature at 110°C; wherein, in the reaction liquid after the reaction, the mass content of monofluoromonochlorosulfonyl imide in the fluorination reaction liquid is ≤10%, and the mass content of bisfluorosulfonyl imide is ≥90%;

[0081] Final fluorination reaction: the reaction liquid of the second primary fluorination reaction and 6 g (0.3 mol) of anhydrous hydrogen fluoride are continuously introduced into a horizontal tubular reactor, the reaction temperature is maintained at 120°C, and the reaction is performed for about 0.1 hour. The sampling test is qualified, and the anhydrous hydrogen fluoride feed is closed to terminate the reaction; wherein, the last crude product sampling test of the reaction liquid requires that the content of monofluoromonochlorosulfonyl imide is ≤100ppm, and this is the time to stop the reaction. Since the crude product test time is added to the time during the reaction stop process, when the test result of the mass content of monofluoromonochlorosulfonyl imide ≤100ppm is known, the reaction liquid has reacted for more than 0.5 hours, so the final product does not contain monofluoromonochlorosulfonyl imide;

[0082] Purification: Bis(chlorosulfonyl)imide is removed from the light fraction by a distillation system, the light fraction is hydrogen fluoride, the temperature is 80°C, and the vacuum is -0.02MPa. Purification is carried out by a rectification system, the heavy fraction is heavy slag, and the light fraction is bis(fluorosulfonyl)imide, the rectification temperature is 90°C, and the vacuum is -0.095MPa.

[0083] Example 2

[0084] use Figure 1 The preparation equipment shown in the figure. Among them, the first fluorination reactor 1 adopts an integral structure microchannel reactor, the intermediate fluorination reactor 2 adopts a fluorine-lined reactor, and the final fluorination reactor 3 adopts a coil reactor.

[0085] A method for preparing bisfluorosulfonyl imide, comprising the following specific steps:

[0086] The first primary fluorination reaction: 107 g (0.5 mol) of bis(chlorosulfonyl)imide and 10 g (0.5 mol) of anhydrous hydrogen fluoride are continuously introduced into a monolithic microchannel reactor that has been replaced with an inert gas at least three times beforehand for 0.15 hours, the reaction temperature is maintained at 100° C., and the reaction tail gas water is absorbed as a by-product of hydrochloric acid;

[0087] Second primary fluorination reaction: the reaction liquid of the first primary fluorination reaction was placed in a 500 mL fluorine-lined reactor for reaction, and 10 g (0.5 mol) of anhydrous hydrogen fluoride was continuously introduced into the 500 mL fluorine-lined reactor for reaction for 5 hours, and the reaction temperature was maintained at 110° C.;

[0088] Final fluorination reaction: The reaction liquid of the second primary fluorination reaction and 6 g (0.3 mol) of anhydrous hydrogen fluoride are continuously introduced into the coil reactor, and the reaction temperature is maintained at 120°C. After reacting for about 0.2 hours, sampling is performed and the test is qualified, and the anhydrous hydrogen fluoride feed is closed to end the reaction;

[0089] Purification: Bis(chlorosulfonyl)imide is removed from the light fraction by a distillation system, the light fraction is hydrogen fluoride, the temperature is 80°C, and the vacuum is -0.02MPa. Purification is carried out by a rectification system, the heavy fraction is heavy slag, and the light fraction is bis(fluorosulfonyl)imide, the rectification temperature is 100°C, and the vacuum is -0.095MPa.

[0090] Example 3

[0091] use Figure 1 The preparation equipment shown in the figure. Among them, the first fluorination reactor 1 adopts a dynamic tubular reactor, the intermediate fluorination reactor 2 adopts a fluorine-lined reactor, and the final fluorination reactor 3 adopts a coil reactor.

[0092] A method for preparing bisfluorosulfonyl imide, comprising the following specific steps:

[0093] The first primary fluorination reaction: 107 g (0.5 mol) of bis(chlorosulfonyl)imide and 10 g (0.5 mol) of anhydrous hydrogen fluoride are continuously introduced into a dynamic tubular reactor which has been replaced with an inert gas at least three times beforehand for 0.2 hours, the reaction temperature is maintained at 100° C., and the reaction tail gas water is absorbed as a by-product of hydrochloric acid;

[0094] Second primary fluorination reaction: the reaction liquid of the first primary fluorination reaction was placed in a 500 mL fluorine-lined reactor for reaction, and 12 g (0.6 mol) of anhydrous hydrogen fluoride was continuously introduced into the 500 mL fluorine-lined reactor for reaction for 6 hours, and the reaction temperature was maintained at 110° C.;

[0095] Final fluorination reaction: The reaction liquid of the second primary fluorination reaction and 6 g (0.3 mol) of anhydrous hydrogen fluoride are continuously introduced into the coil reactor, and the reaction temperature is maintained at 120°C. After reacting for about 0.2 hours, sampling is performed and the test is qualified, and the anhydrous hydrogen fluoride feed is closed to end the reaction;

[0096] Purification: Bis(chlorosulfonyl)imide is delighted by a distillation system, the light fraction is hydrogen fluoride, the temperature is 80°C, and the vacuum is -0.02MPaMPa. Purification is carried out by a rectification system, the heavy fraction is heavy slag, the light fraction is bis(fluorosulfonyl)imide, the rectification temperature is 110°C, and the vacuum is -0.099MPa.

[0097] Example 4

[0098] use Figure 1The preparation equipment shown in the figure. Among them, the first fluorination reactor 1 adopts a dynamic tubular reactor, the intermediate fluorination reactor 2 adopts a fluorine-lined reactor, and the final fluorination reactor 3 adopts a coil reactor.

[0099] A method for preparing bisfluorosulfonyl imide, comprising the following specific steps:

[0100] The first primary fluorination reaction: 107 g (0.5 mol) of bis(chlorosulfonyl)imide and 8 g (0.4 mol) of anhydrous hydrogen fluoride are continuously introduced into a dynamic tubular reactor which has been replaced with an inert gas at least three times beforehand for 0.1 hour, the reaction temperature is maintained at 90°C, and the reaction tail gas water is absorbed as a by-product of hydrochloric acid;

[0101] Second primary fluorination reaction: the reaction liquid of the first primary fluorination reaction was placed in a 500 mL fluorine-lined reactor for reaction, and 8 g (0.4 mol) of anhydrous hydrogen fluoride was continuously introduced into the 500 mL fluorine-lined reactor for reaction for 5 hours, and the reaction temperature was maintained at 110° C.;

[0102] Final fluorination reaction: The reaction liquid of the second primary fluorination reaction and 6 g (0.3 mol) of anhydrous hydrogen fluoride are continuously introduced into the coil reactor, and the reaction temperature is maintained at 120°C. After reacting for about 0.2 hours, sampling is performed and the test is qualified, and the anhydrous hydrogen fluoride feed is closed to end the reaction;

[0103] Purification: Bis(chlorosulfonyl)imide is delighted by a distillation system, the light fraction is hydrogen fluoride, the temperature is 80°C, and the vacuum is -0.02MPaMPa. Purification is carried out by a rectification system, the heavy fraction is heavy slag, the light fraction is bis(fluorosulfonyl)imide, the rectification temperature is 110°C, and the vacuum is -0.099MPa.

[0104] Example 5

[0105] use Figure 1 The preparation equipment shown in the figure. Among them, the first fluorination reactor 1 adopts a dynamic tubular reactor, the intermediate fluorination reactor 2 adopts a fluorine-lined reactor, and the final fluorination reactor 3 adopts an integral structure microchannel reactor.

[0106] A method for preparing bisfluorosulfonyl imide, comprising the following specific steps:

[0107] The first primary fluorination reaction: 107 g (0.5 mol) of bis(chlorosulfonyl)imide and 8 g (0.4 mol) of anhydrous hydrogen fluoride are continuously introduced into a dynamic tubular reactor which has been replaced with an inert gas at least three times beforehand for 0.2 hours, the reaction temperature is maintained at 110°C, and the reaction tail gas water is absorbed as a by-product of hydrochloric acid;

[0108] Second primary fluorination reaction: the reaction liquid of the first primary fluorination reaction was placed in a 500 mL fluorine-lined reactor for reaction, and 10 g (0.5 mol) of anhydrous hydrogen fluoride was continuously introduced into the 500 mL fluorine-lined reactor for reaction for 6 hours, and the reaction temperature was maintained at 110° C.;

[0109] Final fluorination reaction: The reaction liquid of the second primary fluorination reaction and 8 g (0.4 mol) of anhydrous hydrogen fluoride are continuously introduced into the integral structure microchannel reactor, the reaction temperature is maintained at 120°C, and after reacting for about 0.2 hours, the sample is taken for testing and if it is qualified, the anhydrous hydrogen fluoride feed is closed and the reaction is terminated;

[0110] Purification: Bis(chlorosulfonyl)imide is delighted by a distillation system, the light fraction is hydrogen fluoride, the temperature is 80°C, and the vacuum is -0.02MPaMPa. Purification is carried out by a rectification system, the heavy fraction is heavy slag, the light fraction is bis(fluorosulfonyl)imide, the rectification temperature is 110°C, and the vacuum is -0.099MPa.

[0111] Example 6

[0112] Example 6 is substantially the same as Example 1, except that in the first primary fluorination reaction, the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride is 1:0.6.

[0113] Example 7

[0114] Example 7 is substantially the same as Example 1, except that in the first primary fluorination reaction, the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride is 1:1.9.

[0115] Comparative Example 1

[0116] Comparative Example 1 is substantially the same as Example 1, except that in the first primary fluorination reaction, the initial molar ratio of bischlorosulfonyl imide to the hydrogen fluoride is 1:0.2.

[0117] Comparative Example 2

[0118] Comparative Example 2 is basically the same as Example 1, except that: all the bischlorosulfonyl imide participating in the reaction is premixed with all the hydrogen fluoride, and then the fluorination reaction is carried out in three stages in the first fluorination reactor 1, the intermediate fluorination reactor 2 and the final fluorination reactor 3 in Example 1 respectively. (The amount of bischlorosulfonyl imide and hydrogen fluoride is the same as the total amount of the first primary fluorination reaction, the second primary fluorination reaction and the final fluorination reaction in Example 1).

[0119] The components of the bis(fluorosulfonyl)imide prepared in Examples 1 to 5 were tested, and the test results are shown in Table 1 below.

[0120] Table 1

[0121]

[0122] "ND" in Table 1 means not detected.

[0123] The purity and yield of the bis(fluorosulfonyl)imide obtained in Examples 1 to 7 and Comparative Examples 1 to 2 were tested. The test results are shown in Table 2 below.

[0124] Table 2

[0125]

[0126] It can be seen from the data in Table 1 above that the bisfluorosulfonyl imide prepared in Examples 1 to 5 has a low moisture content, a very low content of free acid, chloride ion, sulfate and fluoride ion, and no impurity metal ions are detected. Therefore, when the bisfluorosulfonyl imide lithium prepared by the bisfluorosulfonyl imide of the present application is used as an electrolyte additive for a lithium ion battery, a battery with excellent performance can be obtained, which improves the safety of the battery, the high rate charge and discharge performance and the reversible capacity.

[0127] From the data in Table 2, it can be seen that in Examples 1 to 7, by controlling the feed molar ratio of bischlorosulfonyl imide to hydrogen fluoride, the amount of hydrogen fluoride used in the primary fluorination reaction is reduced, and the excess bischlorosulfonyl imide is subjected to a fluorination reaction with a small amount of hydrogen fluoride. The initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride in the primary fluorination reaction is 1:0.4 to 1:1.9. At this ratio, it is not only beneficial to improve the purity of the final product, but also no longer contains hydrogen fluoride after the primary fluorination reaction, only hydrogen chloride gas is produced, and hydrogen chloride can be directly absorbed into a hydrochloric acid solution with higher purity, which can eliminate the condensation recovery device required for condensing a large amount of hydrogen fluoride in the traditional process. Among them, when the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride in the primary fluorination reaction is 1:0.8 to 1:1.1, the yield and purity of the bischlorosulfonyl imide obtained are higher.

[0128] It can be seen from Example 5 that when the three fluorination reactions are carried out through the first primary fluorination reaction, the second primary fluorination reaction and the final fluorination reaction, the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride in the first primary fluorination reaction is 1:0.8~1:1.1, the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride in the second primary fluorination reaction is 1:0.8~1:1.9, and the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride in the final fluorination reaction is 1:2~1:8, the effect is particularly outstanding, and the yield of bischlorosulfonyl imide is as high as 99.1%.

[0129] It can be seen from Examples 1 to 7 and Comparative Example 1 that when the initial molar ratio of bischlorosulfonyl imide to the hydrogen fluoride is not within the scope of the present application, the purity of bisfluorosulfonyl imide decreases sharply; it can be seen from Examples 1 to 7 and Comparative Example 2 that when the scheme is adjusted, even if the total reaction time is extended to 30 hours, the purity is only 98.5124%, because the boiling point of hydrogen fluoride is 19.4° C., which is much lower than the reaction temperature. When all the hydrogen fluoride is introduced together, it is very easy to gasify and enter the condensation recovery system, and the contact time of the reactants is greatly reduced.

[0130] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0131] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing bis(fluorosulfonyl)imide, characterized in that: The following steps are involved: Carrying out a primary fluorination reaction between bischlorosulfonyl imide and hydrogen fluoride, wherein the initial molar ratio of the bischlorosulfonyl imide to the hydrogen fluoride is 1:0.4 to 1:1.9, to obtain a fluorination reaction liquid; The fluorination reaction liquid is subjected to a final fluorination reaction with hydrogen fluoride, wherein the initial molar ratio of bischlorosulfonyl imide to hydrogen fluoride in the fluorination reaction liquid is ≤1:2, and bisfluorosulfonyl imide is obtained.

2. The method for preparing bis(fluorosulfonyl)imide according to claim 1, characterized in that: In the primary fluorination reaction, the initial molar ratio of the bischlorosulfonyl imide to the hydrogen fluoride is 1:0.8 to 1:1.

1.

3. The method for preparing bis(fluorosulfonyl)imide according to claim 1, characterized in that: In the final fluorination reaction, the initial molar ratio of bis(chlorosulfonyl)imide to hydrogen fluoride in the fluorination reaction solution is 1:2 to 1:

8.

4. The method for preparing bis(fluorosulfonyl)imide according to claim 1, characterized in that: The mass content of monofluoromonochlorosulfonyl imide in the fluorination reaction solution before the final fluorination reaction is controlled to be ≤10%, and / or the mass content of bisfluorosulfonyl imide is controlled to be ≥90%.

5. The method for preparing bis(fluorosulfonyl)imide according to claim 1, characterized in that: The mass content of monofluoromonochlorosulfonyl imide in the fluorination reaction liquid obtained by the final fluorination reaction is controlled to be ≤100ppm.

6. The method for preparing bis(fluorosulfonyl)imide according to claim 1, characterized in that: The primary fluorination reaction is carried out successively twice or more; In the first primary fluorination reaction, bischlorosulfonyl imide and hydrogen fluoride are subjected to a fluorination reaction, wherein the initial molar ratio of the bischlorosulfonyl imide to the hydrogen fluoride is 1:0.4 to 1:1.9, to obtain a first fluorination reaction liquid; In the second primary fluorination reaction, the first fluorination reaction liquid is subjected to a fluorination reaction with hydrogen fluoride, and the initial molar ratio of the bischlorosulfonyl imide in the first fluorination reaction liquid to the hydrogen fluoride is 1:0.8-1:1.

9.

7. The method for preparing bisfluorosulfonyl imide according to claim 6, characterized in that: The mass content of monochlorofluorosulfonyl imide in the first fluorination reaction liquid is controlled to be ≥60%, and / or the mass content of bischlorosulfonyl imide is controlled to be ≤40%.

8. The method for preparing bisfluorosulfonyl imide according to any one of claims 1 to 7, characterized in that: The ratio of the total mole of bischlorosulfonyl imide added in the primary fluorination reaction and the final fluorination reaction to the total mole of hydrogen fluoride is 1:2-1:

8.

9. The method for preparing bisfluorosulfonyl imide according to any one of claims 1 to 7, characterized in that: The reaction temperatures of the primary fluorination reaction and the final fluorination reaction are both 60°C to 150°C.

10. The method for preparing bisfluorosulfonyl imide according to any one of claims 1 to 7, characterized in that: The hydrogen fluoride obtained after the final fluorination reaction is recycled to the primary fluorination reaction.

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