A method and apparatus for continuously preparing purified bisfluorosulfonylimide

Abstract

The application belongs to the technical field of chemical raw material preparation and relates to a preparation device and method of sodium bisfluorosulfonylimide, which comprises a bischlorosulfonylimide feeding pump, a hydrogen fluoride feeding pump, a feeding mixer, a tube reactor, a flash tank, a compressor, a compressor outlet condenser, a hydrogen fluoride recovery buffer tank, a recovered hydrogen fluoride conveying pump, a thin film evaporator feeding pump, a thin film evaporator, a gas phase condenser, a No.1 vacuum pump, a low-boiling-liquid receiving tank, an evaporator liquid buffer tank, a molecular distillation feeding pump, a molecular distillation evaporator, a No.2 vacuum pump, a heavy component buffer tank, an HFSI buffer tank, an HFSI conveying pump and a heavy component conveying pump. The application adopts a tube reactor, shortens the reaction time, improves the production efficiency and makes the quality of the produced HFSI more stable. The heating of the tube reactor is more uniform, and the occurrence of side reactions, such as product decomposition and polymerization, caused by local overheating of the kettle reactor is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chemical raw materials, and relates to a preparation device and method of sodium bisfluorosulfonylimide. BACKGROUND

[0002] Lithium bisfluorosulfonylimide (LiFSI) is a new type of electrolyte lithium salt suitable for lithium battery electrolyte, is environment-friendly, and has high safety performance. Compared with lithium hexafluorophosphate (LiPF6) which is the most widely used in current commercial application, LiFSI has advantages in thermal stability (above 200 DEG C) and conductivity, and has industrial production conditions. It is currently recognized as the best substitute for LiPF6 at home and abroad, and has good development prospects. At present, the synthesis of lithium bisfluorosulfonylimide generally needs to go through three main stages of bis(chlorosulfonyl)imide synthesis, bis(chlorosulfonyl)imide fluorination reaction to prepare bis(fluorosulfonyl)imide, and preparation of bis(fluorosulfonyl)imide alkali metal salt.

[0003] In the prior art, the synthesis of bisfluorosulfonylimide mostly uses a kettle type reactor. Since the kettle type reactor is a batch reaction, there are problems of low production efficiency and poor stability of different batches of products. The kettle type reactor is mostly jacket-heated, and local overheating is easy to occur, which leads to side reactions of product polymerization and affects the quality of HFSI. In the fluorination reaction process of the current hydrogen fluoride process, a large amount of HF and HCL mixed gas is generated. The existing tail gas treatment process mostly uses water absorption combined with alkali absorption for treatment. This treatment method generates a large amount of mixed acid, has high treatment difficulty, and increases production cost. The existing HFSI purification mostly uses a kettle type rectifying column for batch rectification purification, and continuous rectification purification cannot be realized. The production efficiency is low, the yield of target product HFSI is low, and the kettle type rectification causes long heating time due to low heat exchange efficiency. HFSI is easy to polymerize, which affects the quality of prepared LiFSI. SUMMARY

[0004] In order to solve the problems in the background art of the application, the purpose of the application is to provide a continuous, high production efficiency, low energy consumption, high yield, high purity and low cost bisfluorosulfonylimide preparation and purification method and device. The application can realize continuous production of high-purity bisfluorosulfonylimide.

[0005] The scheme is as follows:

[0006] A method for preparing and purifying bisfluorosulfonylimide by a continuous method, comprising the following steps:

[0007] S10: Bisfluorosulfonylimide preparation: bis(chlorosulfonyl)imide is controlled to have a feed ratio of 1:1-3 through a bis(chlorosulfonyl)imide feed pump and a hydrogen fluoride feed pump, is uniformly mixed through a raw material mixer, and then is fed into a tubular reactor. After reaction, it is fed into a flash tank;

[0008] S20: hydrogen fluoride recovery: the gaseous phase after flashing enters a compressor, most of the hydrogen fluoride is liquefied and then enters a hydrogen fluoride recovery buffer tank for reuse, and the hydrogen chloride non-condensable gas carries a small amount of HF into a falling film water absorption system to produce 31% hydrochloric acid as a byproduct;

[0009] S30: bis-fluorosulfonyl imide purification: the liquid phase in the flash tank is pumped into a thin film evaporator by a thin film evaporator feed pump, and the low-boiling substances are cooled by a compressor outlet condenser and then enter a low-boiling substance receiving tank;

[0010] S40: the bottom liquid of the thin film evaporator enters an evaporator liquid buffer tank, is pumped into a molecular distillation evaporator by a molecular distillation feed pump, the molecular distillation evaporator is connected to heating steam and refrigerated water, a 2# vacuum pump is started to perform reduced pressure distillation, the distilled HFSI enters an HFSI buffer tank, and HFSI with a purity of >99.99% is obtained, and the distilled heavy components enter a heavy component buffer tank.

[0011] Preferably, in S10, the reaction process controls the reaction temperature to be 50-200℃, the reaction pressure to be 1.0-2.0 MPa, and the reaction time to be 8-15 h.

[0012] Preferably, in S20, the compressor outlet pressure is controlled to be 0.5-1.0 MPa, and the temperature after cooling is controlled to be -15-25℃.

[0013] Preferably, in S30, a 1# vacuum pump is started to control the pressure of the thin film evaporator to be -0.08~-0.095 MPa.

[0014] Preferably, in S30, the thin film evaporator is connected to low-pressure steam to control the temperature of the gas phase to be 80-120℃ to remove low-boiling substances.

[0015] Preferably, in S40, when the 2# vacuum pump is started to perform reduced pressure distillation, the pressure is controlled to be -0.09~-0.1 MPa, and the evaporation temperature is controlled to be 80-120℃.

[0016] A device for preparing and purifying bis-fluorosulfonyl imide in a continuous method is suitable for the method described above, and comprises a bis-chlorosulfonyl imide feed pump, a hydrogen fluoride feed pump, a feed mixer, a tubular reactor, a flash tank, a compressor, a compressor outlet condenser, a hydrogen fluoride recovery buffer tank, a recovered hydrogen fluoride delivery pump, a thin film evaporator feed pump, a thin film evaporator, a gas phase condenser, a 1# vacuum pump, a low-boiling substance receiving tank, an evaporator liquid buffer tank, a molecular distillation feed pump, a molecular distillation evaporator, a 2# vacuum pump, a heavy component buffer tank, an HFSI buffer tank, an HFSI delivery pump, and a heavy component delivery pump.

[0017] The beneficial effects of the present application are as follows:

[0018] 1. The method and device for preparing purified bisfluorosulfonylimide by a continuous method, which adopts a column-tube continuous flow reactor, shortens the reaction time, improves the production efficiency, and makes the output HFSI quality more stable. The column-tube reactor is heated more uniformly, and the occurrence of side reactions such as product decomposition and polymerization caused by local overheating of the kettle reactor is reduced.

[0019] 2. The fluorinated tail gas generated by the fluorination reaction is compressed and matched with deep cooling to recover part of the hydrogen fluoride, reduce the production cost, and reduce the amount of mixed acid generated, obtain a higher-purity hydrochloric acid byproduct, and bring economic benefits.

[0020] 3. Bisfluorosulfonylimide purification uses a thin film evaporator to replace the traditional kettle rectification kettle to remove a large amount of low-boiling substances, has higher heat exchange efficiency, and reduces steam energy consumption.

[0021] 4. Bisfluorosulfonylimide heavy component and decolorization removal uses a molecular distillation evaporator to realize separation under high vacuum by relying on the difference in the average free path of molecular motion of different substances, shortens the heating time, reduces the polymerization of bisfluorosulfonylimide, and improves the yield and quality. BRIEF DESCRIPTION OF DRAWINGS

[0022] The application will be further described below in conjunction with the drawings.

[0023] Figure 1 is a schematic diagram of the preparation device in the application;

[0024] In the figure: dichlorosulfonylimide feed pump 1, hydrogen fluoride feed pump 2, feed mixer 3, column-tube reactor 4, flash tank 5, compressor 6, compressor outlet condenser 7, hydrogen fluoride recovery buffer tank 8, recovered hydrogen fluoride delivery pump 9, thin film evaporator feed pump 10, thin film evaporator 11, gas phase condenser 12, 1# vacuum pump 13, low-boiling substance receiving tank 14, evaporator feed liquid buffer tank 15, molecular distillation feed pump 16, molecular distillation evaporator 17, 2# vacuum pump 18, heavy component buffer tank 19, HFSI buffer tank 20, HFSI delivery pump 21, and heavy component delivery pump 22. DETAILED DESCRIPTION

[0025] In order to make the technical means, creative features, purposes and effects achieved by the application easy to understand, the application will be further described below in conjunction with specific embodiments.

[0026] For example, Figure 1As shown, the device for preparing and purifying bisfluorosulfonylimide by a continuous method provided by the present application is suitable for the method for preparing and purifying bisfluorosulfonylimide by a continuous method, and comprises a bischlorosulfonylimide feeding pump 1, a hydrogen fluoride feeding pump 2, a feeding mixer 3, a tube reactor 4, a flash tank 5, a compressor 6, a compressor outlet condenser 7, a hydrogen fluoride recovery buffer tank 8, a recovered hydrogen fluoride conveying pump 9, a thin film evaporator feeding pump 10, a thin film evaporator 11, a gas phase condenser 12, a 1# vacuum pump 13, a low-boiling substance receiving tank 14, an evaporator feed liquid buffer tank 15, a molecular distillation feeding pump 16, a molecular distillation evaporator 17, a 2# vacuum pump 18, a heavy component buffer tank 19, an HFSI buffer tank 20, an HFSI conveying pump 21 and a heavy component conveying pump 22.

[0027] The present application comprises the following steps when preparing and purifying bisfluorosulfonylimide by a continuous method:

[0028] S10: Bisfluorosulfonylimide preparation: Bischlorosulfonylimide is mixed with hydrogen fluoride in a 1:1-3 ratio by the bischlorosulfonylimide feeding pump 1 and the hydrogen fluoride feeding pump 2, uniformly mixed in the feeding mixer 3 and then fed into the tube reactor 4, and then fed into the flash tank 5 after the reaction is completed.

[0029] S20: Hydrogen fluoride recovery: The gaseous phase after flashing is fed into the compressor 6, most of the hydrogen fluoride is liquefied and then fed into the hydrogen fluoride recovery buffer tank 8 for reuse, and the hydrogen chloride non-condensable gas carries a small amount of HF into the falling film water absorption system to produce 31% hydrochloric acid as a byproduct.

[0030] S30: Bisfluorosulfonylimide purification: The liquid phase in the flash tank 5 is pumped into the thin film evaporator 11 by the thin film evaporator feeding pump 10, and the low-boiling substance is cooled in the low-boiling substance receiving tank 14 after being cooled by the compressor outlet condenser 7.

[0031] S40: The bottom feed liquid of the thin film evaporator 11 is fed into the evaporator feed liquid buffer tank 15, pumped into the molecular distillation evaporator 17 by the molecular distillation feeding pump 16, heated steam and chilled water are introduced into the molecular distillation evaporator 17, the 2# vacuum pump 18 is started to perform reduced pressure distillation, the distilled HFSI is fed into the HFSI buffer tank 20, and HFSI with a purity of >99.99% is obtained, and the distilled heavy component is fed into the heavy component buffer tank 19.

[0032] In some embodiments, in S10, the reaction process controls the reaction temperature to be 50-200℃, the reaction pressure to be 1.0-2.0 MPa, and the reaction time to be 8-15h.

[0033] In some embodiments, in S20, the outlet pressure of the compressor 6 is controlled to be 0.5-1.0 MPa, and the temperature after cooling is controlled to be -15-25℃.

[0034] In some embodiments, in S30, the 1# vacuum pump 13 is started to control the thin film evaporator pressure to -0.08 to -0.095 Mpa.

[0035] In some embodiments, in S30, the thin film evaporator 11 is connected to low-pressure steam to control the gas phase temperature to 80-120 DEG C to remove low-boiling substances.

[0036] In some embodiments, in S40, when the 2# vacuum pump 18 is started for vacuum distillation, the pressure is controlled to -0.09 to -0.1 Mpa, and the evaporation temperature is 80-120 DEG C.

[0037] In order to highlight the advantages of the continuous method for preparing and purifying bisfluorosulfonylimide and the device, the present application is compared with the traditional batch kettle reaction device for purifying bisfluorosulfonylimide. The following comparison data are obtained. From the data, it can be seen that the continuous method for preparing and purifying bisfluorosulfonylimide and the device provided by the present application have the advantages of higher HFSI yield and HFSI purity, and lower energy consumption.

[0038]

[0039]

[0040] The basic principles, main features and advantages of the present application are shown and described. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A process for the preparation of purified bisfluorosulfonylimide by a continuous process, characterized in that: The method comprises the following steps: S10: Bisfluorosulfone imide preparation: Bischlorosulfone imide is fed into a column reactor in a 1:1-3 ratio through a bischlorosulfone imide feeding pump and a hydrogen fluoride feeding pump, mixed uniformly in a raw material mixer, and then fed into a flash tank after the reaction is completed; S20: Hydrogen fluoride recovery: The gaseous phase after flashing is fed into a compressor, most of the hydrogen fluoride is liquefied and then fed into a hydrogen fluoride recovery buffer tank for reuse, and the hydrogen chloride non-condensable gas carries a small amount of HF into a falling film water absorption system to produce 31% hydrochloric acid as a byproduct; S30: Bisfluorosulfone imide purification: The liquid phase in the flash tank is pumped into a thin film evaporator through a thin film evaporator feeding pump, and the low-boiling substances are cooled in a compressor outlet condenser and then fed into a low-boiling substance receiving tank; S40: The bottom liquid of the thin film evaporator is fed into an evaporator liquid buffer tank, pumped into a molecular distillation evaporator through a molecular distillation feeding pump, heated steam and chilled water are introduced into the molecular distillation evaporator, a 2# vacuum pump is started to perform reduced pressure distillation, the distilled HFSI is fed into an HFSI buffer tank, and HFSI with a purity greater than 99.99% is obtained, and the distilled heavy components are fed into a heavy component buffer tank; In S10, the reaction process controls the reaction temperature to be 50-200°C, the reaction pressure to be 1.0-2.0 MPa, and the reaction time to be 8-15 h; In S20, the compressor outlet pressure is controlled to be 0.5-1.0 MPa, and the temperature after cooling is controlled to be -15-25°C; In S30, a 1# vacuum pump is started to control the pressure of the thin film evaporator to be -0.08~-0.095 Mpa; In S30, low-pressure steam is introduced into the thin film evaporator to control the temperature of the gaseous phase to be 80-120°C to remove low-boiling substances; In S40, when the 2# vacuum pump is started to perform reduced pressure distillation, the pressure is controlled to be -0.09~-0.1 Mpa, and the evaporation temperature is controlled to be 80-120°C.

2. A device for continuously preparing purified bisfluorosulfone imide, which is suitable for the method for continuously preparing purified bisfluorosulfone imide in claim 1, and comprises a bischlorosulfone imide feeding pump, a hydrogen fluoride feeding pump, a feeding mixer, a column reactor, a flash tank, a compressor, a compressor outlet condenser, a hydrogen fluoride recovery buffer tank, a recovered hydrogen fluoride conveying pump, a thin film evaporator feeding pump, a thin film evaporator, a gaseous phase condenser, a 1# vacuum pump, a low-boiling substance receiving tank, an evaporator liquid buffer tank, a molecular distillation feeding pump, a molecular distillation evaporator, a 2# vacuum pump, a heavy component buffer tank, an HFSI buffer tank, an HFSI conveying pump, and a heavy component conveying pump.

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