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CN-122010741-A - Method for recycling triethylamine in preparation process of difluoro sulfonimide triethylamine salt

CN122010741ACN 122010741 ACN122010741 ACN 122010741ACN-122010741-A

Abstract

The invention discloses a method for recycling triethylamine in the preparation process of difluoro sulfonimide triethylamine salt, which comprises the following steps of (a) taking sulfuryl fluoride, ammonia gas and triethylamine as raw materials, reacting in an organic solvent to obtain reaction liquid containing difluoro sulfonimide triethylamine salt and triethylamine hydrofluoric acid salt, (b) adding a phase transfer catalyst and inorganic alkaline substances, carrying out heat preservation reaction, (c) filtering to obtain solid fluoride salt and filtrate, and (d) carrying out vacuum evaporation concentration on the filtrate to obtain concentrate and a recycling solvent containing triethylamine, wherein the recycling solvent containing triethylamine is used for the next reaction. Under the action of a phase transfer catalyst, the added inorganic alkaline substance reacts with triethylamine hydrofluoric acid salt to generate solid fluoride salt, triethylamine is dissociated, the triethylamine can be recovered through vacuum evaporation and concentration, the operation is simple, the industrial implementation is convenient, the triethylamine recovery cost is greatly reduced, and the wastewater treatment difficulty is also reduced.

Inventors

  • LIU CHENGFENG
  • JIANG QINGLONG
  • ZHOU KAI

Assignees

  • 临海市利民化工有限公司

Dates

Publication Date
20260512
Application Date
20260203

Claims (9)

  1. 1. A method for recovering triethylamine in the preparation process of difluoro sulfonimide triethylamine salt is characterized by comprising the following steps of (a) taking sulfuryl fluoride, ammonia gas and triethylamine as raw materials, carrying out reaction in an organic solvent to obtain reaction liquid containing difluoro sulfonimide triethylamine salt and triethylamine hydrofluoric acid salt, (b) controlling the temperature to be not higher than 40 ℃, adding a phase transfer catalyst and an inorganic alkaline substance into the reaction liquid, carrying out heat preservation reaction for 0.5-10 hours, (C) filtering to obtain solid fluoride salt and filtrate, d) controlling the temperature to be not higher than 50 ℃, carrying out vacuum evaporation concentration on the filtrate to obtain concentrate and a recovery solvent containing triethylamine, washing the concentrate to obtain the difluoro sulfonimide triethylamine salt, and using the recovery solvent containing triethylamine for the next batch of reaction.
  2. 2. The method for recovering triethylamine in the preparation process of bis (fluorosulfonyl) imide triethylamine salt according to claim 1, wherein the phase transfer catalyst in the step (b) is polyethylene glycol or crown ether, and the addition weight of the phase transfer catalyst is 0.002% -0.1% of the weight of the reaction solution.
  3. 3. The method for recovering triethylamine in a process for preparing a bis-fluorosulfonyl imide triethylamine salt according to claim 2, wherein the polyethylene glycol is one or more of polyethylene glycol-400, polyethylene glycol-600 and polyethylene glycol-800, and the crown ether is one or more of 18-crown ether-6 and 15-crown ether-5.
  4. 4. The method for recovering triethylamine in the preparation process of the bis (fluorosulfonyl) imide triethylamine salt according to claim 1, wherein the inorganic alkaline substance in the step (b) is one or more of calcium hydroxide, calcium oxide, magnesium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate and ammonia gas, and the molar ratio of the inorganic alkaline substance to sulfuryl fluoride in the step (a) is 0.5-1.5:1.
  5. 5. The process for recovering triethylamine in a bis-fluorosulfonyl imide triethylamine salt production process according to claim 1, wherein the filtration in step (c) is one of suction filtration, press filtration or centrifugal filtration.
  6. 6. The method for recovering triethylamine in the preparation process of bis (fluorosulfonyl) imide triethylamine salt according to claim 1, wherein the temperature of vacuum evaporation concentration in the step (d) is 15-50 ℃ and the vacuum degree is-0.1-0.08 MPa.
  7. 7. The method for recovering triethylamine in the preparation process of bis (fluorosulfonyl) imide triethylamine salt according to claim 1, wherein the temperature of the water washing in the step (d) is 5-20 ℃, the water consumption is 0.2-1.0 times of the weight of the concentrate, the water washing mode is multi-stage cross flow or countercurrent, and the water washing times are 1-4 times.
  8. 8. The process for recovering triethylamine in the preparation of a bis-fluorosulfonyl imide triethylamine salt according to claim 1, wherein the recovered solvent containing triethylamine in step (d) is used directly in the next reaction without treatment.
  9. 9. The method for recovering triethylamine according to claim 1, wherein the organic solvent is one or more of acetonitrile, tetrahydrofuran and toluene.

Description

Method for recycling triethylamine in preparation process of difluoro sulfonimide triethylamine salt Technical Field The invention belongs to the technical field of chemical synthesis, and relates to a method for recovering triethylamine in a preparation process of difluoro sulfonimide triethylamine salt. Background Lithium bis (fluorosulfonyl imide), abbreviated as LiFSI, is a white powdery solid with good thermal stability, is a key base material for lithium ion battery electrolytes, and is considered to be one of the most likely lithium salts to replace lithium hexafluorophosphate. The electrolyte has better conductivity than lithium hexafluorophosphate, has good compatibility with graphite, silicon negative electrode and lithium iron phosphate positive electrode, can improve the cycle and rate capability of the battery, can improve the discharge performance in a low-temperature environment, and can maintain the capacitance retention rate at high temperature. Lithium bis (fluorosulfonyl) imide can be prepared by reacting an organic base salt of bis (fluorosulfonyl) imide with a lithium source. The organic base salt of the bis-fluorosulfonyl imide can be prepared by reacting sulfuryl fluoride with ammonia in the presence of an organic base. For example, chinese patent CN102378755A discloses a method for preparing bis-fluorosulfonyl imide triethylamine salt, which uses sulfuryl fluoride and ammonia gas as raw materials, acetonitrile as solvent, and makes reaction in the presence of triethylamine, so that the target product with purity of more than 99% can be obtained. Chinese patent CN110217764a discloses a method for preparing organic alkali salt of difluoro-sulfonyl imide, which is characterized in that ammonia reacts with sulfuryl fluoride in organic solvent in the presence of organic alkali and fluoride salt, so as to prepare organic alkali salt of difluoro-sulfonyl imide, and the fluoride salt is sodium fluoride, potassium fluoride, etc., which can effectively avoid the generation of dark impurities, improve the purity of difluoro-sulfonyl imide salt and also improve the reaction rate. Chinese patent CN116283601A uses sulfuryl fluoride and ammonium salt as reaction raw materials, and uses aprotic polar solvent and organic alkaline acid-binding agent to make them undergo the process of reaction in high-pressure reactor so as to obtain the difluoro sulfimide organic ammonium salt, and the ammonium salt is ammonium fluoride, ammonium chloride and ammonium bromide. Chinese patent CN120329199A adopts ammonia gas, sulfuryl fluoride and liquid organic alkali as reaction raw materials, and under the condition of no solvent or a small amount of solvent, the raw materials react by pressurization to generate organic alkali salt of difluoro sulfimide, so that a product with lower chromaticity can be obtained. The above-described methods for preparing organic base salts of bis-fluorosulfonyl imides are all carried out in the presence of an organic base. The organic base has two functions, namely, the organic base is combined with the difluoro sulfonimide generated by the reaction to form target product difluoro sulfonimide organic base salt, and the organic base hydrofluoric acid salt is generated by reacting with byproduct hydrogen fluoride generated by the reaction as an acid binding agent. Since 1 mole of bis (fluorosulfonyl) imide generates 2 moles of hydrogen fluoride, 3 moles of organic base are consumed for generating 1 mole of bis (fluorosulfonyl) imide organic base salt, which is the target product, and 2 moles of organic base hydrofluoric acid salt are generated at the same time, in order to ensure the selectivity of the reaction. The generated organic alkali hydrofluoric acid salt enters the wastewater along with the water washing process, so that the cost of subsequent treatment and recovery is increased, and the consumption of a large amount of organic alkali also increases the raw material cost. Of all the organic base salts of the difluoro-sulfonimide, the difluoro-sulfonimide triethylamine salt has the most wide application, and a large amount of triethylamine is consumed in the preparation process, so that the development of a method for recovering triethylamine in the preparation process of the difluoro-sulfonimide triethylamine salt is urgent. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a method for recycling triethylamine in the preparation process of difluoro sulfonimide triethylamine salt. The method for recycling triethylamine in the preparation process of the difluoro sulfonimide triethylamine salt comprises the following steps of (a) taking sulfuryl fluoride, ammonia gas and triethylamine as raw materials, reacting in an organic solvent to obtain reaction liquid containing difluoro sulfonimide triethylamine salt and triethylamine hydrofluoric acid salt, (b) controlling the temperature to be not higher than 40 ℃, adding a phase transfer c