WO2023142028A1 - 一种在双氟磺酰亚胺锂的生产中回收原辅材料的方法 - Google Patents

一种在双氟磺酰亚胺锂的生产中回收原辅材料的方法 Download PDF

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WO2023142028A1
WO2023142028A1 PCT/CN2022/074936 CN2022074936W WO2023142028A1 WO 2023142028 A1 WO2023142028 A1 WO 2023142028A1 CN 2022074936 W CN2022074936 W CN 2022074936W WO 2023142028 A1 WO2023142028 A1 WO 2023142028A1
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water
phase
triethylamine
passed
dichloromethane
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PCT/CN2022/074936
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French (fr)
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程思聪
黄起森
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宁德时代新能源科技股份有限公司
时代思康新材料有限公司
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Priority to EP22922540.4A priority Critical patent/EP4273100A4/en
Priority to PCT/CN2022/074936 priority patent/WO2023142028A1/zh
Priority to US18/364,732 priority patent/US20240017999A1/en
Publication of WO2023142028A1 publication Critical patent/WO2023142028A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/082—Compounds containing nitrogen and non-metals and optionally metals
    • C01B21/087—Compounds containing nitrogen and non-metals and optionally metals containing one or more hydrogen atoms
    • C01B21/093—Compounds containing nitrogen and non-metals and optionally metals containing one or more hydrogen atoms containing also one or more sulfur atoms
    • C01B21/0935—Imidodisulfonic acid; Nitrilotrisulfonic acid; Salts thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
    • B01D17/02—Separation of non-miscible liquids
    • B01D17/0217—Separation of non-miscible liquids by centrifugal force
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
    • B01D17/02—Separation of non-miscible liquids
    • B01D17/04—Breaking emulsions
    • B01D17/045—Breaking emulsions with coalescers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B01D3/143—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step
    • B01D3/148—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step in combination with at least one evaporator
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0057—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes
    • B01D5/006—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes with evaporation or distillation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/082—Compounds containing nitrogen and non-metals and optionally metals
    • C01B21/086—Compounds containing nitrogen and non-metals and optionally metals containing one or more sulfur atoms
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D3/00—Halides of sodium, potassium or alkali metals in general
    • C01D3/02—Fluorides
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/38—Separation; Purification; Stabilisation; Use of additives
    • C07C17/392—Separation; Purification; Stabilisation; Use of additives by crystallisation; Purification or separation of the crystals
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
    • C07C209/82—Purification; Separation; Stabilisation; Use of additives
    • C07C209/86—Separation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C68/00—Preparation of esters of carbonic or haloformic acids
    • C07C68/08—Purification; Separation; Stabilisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • This application relates to a method for recovering raw and auxiliary materials in the production of lithium bisfluorosulfonyl imide, in particular to a method for recovering triethylene in the waste liquid produced in the production of lithium bisfluorosulfonyl imide through different recovery sections.
  • Amines, fluorides, ester solvents, crystallization liquids and/or dichloromethane off-gas methods are examples of the compounds listed above.
  • Lithium bisfluorosulfonyl imide (chemical formula Li[N(SO 2 F) 2 ], English abbreviation LiFSI) is an important new material containing fluorine. Due to its special molecular structure, there is a lower binding energy between Li + and FSI - , which is conducive to the dissociation of Li + , so adding LiFSI to the electrolyte can obtain higher conductivity. At the same time, LiFSI also has the characteristics of high thermal stability, wide electrochemical window, and low corrosion rate. Especially in power batteries, it can improve the cycle performance and rate performance of power batteries, and is expected to become a new electrolyte lithium salt for lithium-ion batteries. . In 2012, Nippon Shokubai demonstrated LiFSI for the first time, and realized industrial production in 2013. At present, Japanese and Korean battery companies have mixed LiFSI and LiPF 6 in high-end occasions.
  • LiFSI cannot be used on a large scale at present, mainly due to the high production cost due to the limitation of synthesis process conditions.
  • the synthesis process there are disadvantages such as cumbersome process, long process, low product conversion rate, high energy consumption and environmental pollution.
  • an electrolyte for lithium-ion secondary batteries it needs to meet stringent requirements such as high purity and anhydrous. Especially after the water is introduced, it is difficult to completely remove it by raising the temperature to bring water, drying and dehydrating until it decomposes, and even if it can be removed, it will need to lose a large yield.
  • This application is carried out in view of the above-mentioned subject, and its purpose is to provide a kind of method that reclaims raw and auxiliary materials in the production of bisfluorosulfonyl imide lithium, to improve the raw and auxiliary materials in the production of bisfluorosulfonyl imide lithium.
  • the first aspect of the present application provides a method for recovering raw and auxiliary materials in the production of lithium bisfluorosulfonyl imide
  • the production of lithium bisfluorosulfonyl imide includes making sulfuryl fluoride, triethyl Reaction 1, in which the amine is reacted with ammonia gas, and Reaction 2, in which the reaction product is subsequently basified,
  • the methods include:
  • Recovery section A the product mixture produced by reaction 1 is separated into an oil phase comprising (SO 2 F-NH-SO 2 F) ⁇ Et 3 N and an aqueous phase comprising triethylamine hydrogen fluoride salt and impurity ions;
  • the oil phase of 2 F-NH-SO 2 F) Et 3 N is subjected to the alkalization process according to Reaction 2, and the water phase containing triethylamine hydrogen fluoride salt and impurity ions is passed into the alkalization kettle to be mixed with the alkali metal hydroxide Mix and react under stirring, then pass the solution obtained after the reaction in the alkalization tank into the layered tank for phase separation;
  • the upper oil phase is an organic phase containing water and triethylamine, which is separated and stored in the oil phase in secondary stratification tanks;
  • Recovery section B The product mixture obtained by the alkalization process according to Reaction 2 is passed through the evaporator to remove triethylamine and part of the water, and the evaporated triethylamine and water are passed into the condenser to condense and stand for liquid separation ;
  • the upper strata triethylamine solution obtained after the liquid separation is transferred to a triethylamine transfer tank, and is separated into an aqueous phase and an oil phase through a centrifuge, and the oil phase is an organic phase comprising water and triethylamine;
  • Phase and the organic phase comprising water and triethylamine obtained in the recovery section A are passed into a single-effect evaporation system to obtain a water-containing triethylamine phase; then dehydration by a dehydration tower and removal by distillation in a rectification tower Residual moisture, high-purity triethylamine.
  • the recovery method is part of a complete process for the production and purification of lithium bisfluorosulfonyl imide, which includes multiple recovery sections, corresponding to the separation and recovery of different raw and auxiliary materials. There can also be material exchanges and mergers between recycling sections.
  • the purity of the high-purity triethylamine obtained by the method is above 95% by weight; optionally, the purity is above 98% by weight, above 99% by weight or above 99.5% by weight.
  • the product mixture obtained by the alkalization process is evaporated to a mixture containing triethylamine and water through an evaporator, and after the mixture is condensed in a condenser, it is heated to 30-55 °C temperature and let stand to separate layers.
  • the product mixture produced in reaction 1 in recovery section A is separated by layering with a static mixer or extraction through an extraction column.
  • the lower aqueous phase obtained by phase separation in the stratified tank of the recovery section A mainly contains an alkali metal fluoride solution and a small amount of triethylamine; it is combined with the recovery section B in a single-effect evaporation system, The lower water phase obtained in the dehydration tower and the rectification tower is combined in the brine tank; after the liquid in the brine tank is passed into the stripper for stripping, the light phase obtained mainly contains triethylamine and water, and is returned to the recovery In the oil phase secondary stratification tank of section A; the heavy component obtained after stripping mainly contains alkali metal fluoride solution, and the heavy component is passed into a double-effect evaporator to evaporate to obtain a high-concentration alkali metal fluoride solution.
  • the alkali metal is Li, Na or K.
  • the production of the lithium bisfluorosulfonyl imide also includes a dehydration process using an ester solvent, and the water-containing ester solvent evaporated by evaporation is recovered through the recovery section C, and the recovery section C: the water-containing The ester solvent is passed into the ester solvent buffer tank, mixed with the lithium hydroxide solution in the pipeline mixer, and then separated by the coalescing separator; the oil phase obtained after separation is mainly the ester solvent, which is passed into the ester solvent for storage Can.
  • the water phase obtained after being separated by the coalescing separator is added to the lithium hydroxide solution to adjust the pH value, and then enters the stripping tower for stripping through the preheater, and the obtained oil phase is a water-containing ester solvent, and returns to the ester solvent Buffer tank; the obtained water phase and residual liquid are passed into the sewage treatment device for post-treatment.
  • the ester solvent includes ethyl methyl carbonate EMC, diethyl carbonate DEC and dimethyl carbonate DMC.
  • the production of lithium bisfluorosulfonyl imide also includes a crystallization process in which the crystallization liquid is used to dissolve the ester solvent and precipitate the product LiFSI crystals, and the separated crystallization liquid washing oil phase contains dichloromethane , ester solvent, water and salt; the crystallization liquid is recovered through the recovery section D, and the recovery section D: the water washing oil phase of the crystallization liquid is passed into a dehydration tower, and the tower top condensate contains dichloromethane and water, and is separated After the layer, the water phase of the upper layer is passed into the sewage collection tank for post-treatment, and the dichloromethane in the lower layer is all refluxed; the tower bottom liquid of the dehydration tower is passed into a single-effect evaporation system, and the gas phase obtained by evaporation is passed into a rectification tower for rectification.
  • Dichloromethane is obtained from the overhead condensate of the rectification tower, collected into the dichloromethane blending tank, lithium hydroxide is added to the tank, the pH value is adjusted through the pump circulation pipeline and the phases are separated, and the obtained water phase is separated Carry out aftertreatment, the oil phase that obtains is passed into dichloromethane storage tank.
  • ethanol is separated from the middle of the rectification tower for post-treatment; the ester solvent is obtained from the condensate in the middle and lower part of the rectification tower, and the ester solvent is passed into the ester solvent storage tank for dehydration process return Use; Separation of the raffinate obtained from the bottom of the rectifying tower for post-treatment.
  • the liquid phase obtained from the single-effect evaporation system is vacuum-concentrated, and the obtained condensate contains dichloromethane and ester solvents, and is sent back to the dehydration tower; the vacuum-concentrated concentrate is separated for post-processing.
  • the method also includes a recovery section E to recover the waste gas containing dichloromethane produced in each stage, recovery section E: the waste gas containing dichloromethane produced in each stage is cooled and passed into the third stage Adsorption is carried out in the adsorption resin, after the adsorption is saturated, steam desorption is used, and then collected by condensation, the collected liquid containing dichloromethane and water is left to stand and layered, and the upper aqueous phase contains a small amount of dichloromethane, which is used as waste water after separation. Treatment; the lower oil phase is dichloromethane containing a small amount of water, which is passed into a dehydration device for dehydration and then reused.
  • the water content in the dichloromethane containing trace moisture is 1000-2000 ppm, and the dehydration is performed until the water content is 50-200 ppm. In any embodiment, the dehydration is performed through 4A molecular sieves.
  • At least one or more raw and auxiliary materials used in the production of lithium bisfluorosulfonyl imide can be recycled in multiple different recovery sections, and the produced The three waste materials are post-treated, thereby enabling the production of lithium bisfluorosulfonyl imide to have significantly improved economy and environmental friendliness.
  • Fig. 1 is a schematic process flow diagram of stage ⁇ of the process for producing lithium bisfluorosulfonyl imide in an embodiment of the present application.
  • Fig. 2 is a schematic process flow diagram of the ⁇ stage of the process for producing lithium bisfluorosulfonyl imide in an embodiment of the present application.
  • Fig. 3 is a schematic process flow diagram of recovery section A (alkalinization of ⁇ water) in an embodiment of the present application.
  • Fig. 4 is a schematic process flow diagram of recovery section B (triethylamine recovery) in an embodiment of the present application.
  • Fig. 5 is a schematic process flow diagram of recovery section C (recovery of ester solvent, taking DEC as an example) in an embodiment of the present application.
  • Fig. 6 is a schematic process flow diagram of recovery section D (recovery of crystallization liquid) in one embodiment of the present application.
  • Fig. 7 is a schematic process flow diagram of recovery section E (dichloromethane waste gas recovery) in an embodiment of the present application.
  • any lower limit can be combined with any upper limit to form an unexpressed range; and any lower limit can be combined with any other lower limit to form an unexpressed range, just as any upper limit can be combined with any other upper limit to form an unexpressed range.
  • each individually disclosed point or individual value may serve as a lower or upper limit by itself in combination with any other point or individual value or with other lower or upper limits to form an unexpressly recited range.
  • LiFSI Due to its special molecular structure, LiFSI can be added to the electrolyte to obtain higher conductivity. At the same time, LiFSI also has the characteristics of high thermal stability, wide electrochemical window, and low corrosion rate. Especially in power batteries, it can improve the cycle performance and rate performance of power batteries. Excellent choice.
  • the synthesis and purification of LiFSI in the prior art has many problems in industrialized large-scale production. The synthesis process is cumbersome, the process is long, the product conversion rate is low, and the consumption of raw and auxiliary materials is large and difficult to recycle, so the economy is not high.
  • the present invention aims to solve at least some of these problems and proposes a new process for producing LiFSI and a method for recovering raw and auxiliary materials.
  • the process of producing LiFSI mainly includes the following steps:
  • the material composition mainly includes (SO 2 F-NH-SO 2 F) ⁇ Et 3 N, acetonitrile, triethylamine hydrogen fluoride salt, triethylamine (a small amount) and impurity ions.
  • the impurity ions mainly include F - , SO 4 2- , FSO 3 - and Cl - .
  • Evaporation put the product mixture (material ⁇ 1) into the evaporator to evaporate, and separate the acetonitrile solvent.
  • a falling film evaporator can be used to heat the material, a gas-liquid separator is used to separate the liquid from the vapor, and a condenser is used to condense the vapor of acetonitrile (containing a small amount of triethylamine), which is reused in the first step of synthesis.
  • the material composition mainly includes (SO 2 F-NH-SO 2 F) ⁇ Et 3 N, triethylamine hydrogen fluoride salt, acetonitrile (trace amount) and impurity ions.
  • Scheme 1 extraction tower, the bottom enters the light phase (low density), the top exits the light phase, the top enters the heavy phase, the bottom exits the heavy phase, and the middle stirs in a spiral shape; Scheme 2, static mixer and phase separation tank.
  • the extracted oil phase material ⁇ 3 mainly contains (SO 2 F-NH-SO 2 F) ⁇ Et 3 N, while the extracted water phase (material ⁇ water) mainly contains triethylamine hydrogen fluoride salt and impurity ions (such as F - , SO 4 2- , FSO 3 - , Cl - ).
  • an extraction column is used for extraction to achieve better separation of impurity ions (such as F ⁇ ).
  • the content of impurity ions in the oil phase obtained by extraction with a static mixer is 5-30 times, optionally 10-20 times, the content of impurity ions in the oil phase obtained by extraction with an extraction tower .
  • the impurity ion is F - .
  • the stage of synthesis-evaporation-extraction is called the ⁇ stage, and its specific process can refer to the process flow diagram in Figure 1 of the present application.
  • LiFSI lithium bisfluorosulfonimide
  • the reaction mixture obtained in Reaction 2 (material ⁇ 1) was dehydrated using an evaporator.
  • the ester solvent is used to carry water, and no chemical reaction is involved. Because the water absorption of lithium salt is very strong, it is unrealistic to reduce the water to the target requirement simply by evaporation. Adding a large amount of ester solvent can weaken the adsorption of lithium salt to water, and the water can be reduced to the target requirement during the process of evaporating the ester solvent while adding the ester solvent.
  • the ester solvent can be reused after being purified in the recovery section.
  • the ester solvent may include ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC) and the like.
  • Precipitation Precipitate the material (material ⁇ 2) after evaporation and dehydration in the evaporator. Precipitation does not involve a reaction, but simply evaporates the ester solvent. Because the lithium salt is dissolved in the ester solvent, if the ester solvent is not evaporated to a certain extent (such as from 60%-65% to 30%), then the later stage cannot be crystallized or the crystallization rate is very low. The ester solvent can be reused after being purified in the recovery section. After the precipitation process, a crude lithium bisfluorosulfonyl imide (material ⁇ 3) with a low water content (for example, less than 3000ppm) is obtained. In the production of lithium bisfluorosulfonyl imide of the present application, the stage of alkalization-dehydration-desolventization is called the ⁇ stage, and its specific process can refer to the process flow diagram in Figure 2 of the present application.
  • Crystallization means that when a substance is in a non-equilibrium state, another phase will be precipitated, and this phase will be precipitated in the form of crystals.
  • the material ⁇ 3 is passed into the crystallization kettle, and dichloromethane is added. Utilize dichloromethane to dissolve the ester solvent without dissolving LiFSI, so that LiFSI is supersaturated and precipitated in the ester solvent, and the crystal nucleus grows. Pass the resulting mixture into a two-in-one device with filter and washing functions to wash off other impurities attached to the surface of the LiFSI crystal. After the crystallization liquid is purified by the recovery section, the ester solvent and dichloromethane can be reused.
  • the washed material is passed into the drying tank. After heating the nitrogen, pass it into the drying kettle. The material is fluidized under the action of stirring and air flow. In the large-area gas-solid two-phase contact, the moisture of the material evaporates rapidly, and the high-humidity nitrogen gas is discharged from the kettle to make the material meet the drying requirements.
  • the above-mentioned crystallization and drying steps may not be performed, and the material ⁇ 3 is directly put into the dissolution process.
  • ester solvents such as ethyl methyl carbonate (EMC) or dimethyl carbonate (DMC) can be selected to dissolve the above dried crystals (for the crystallization method) or crude products (for the non-crystallization method) as required.
  • acid removal if the HF content in the detection solution exceeds the standard (such as standard HF ⁇ 50 ⁇ g/g), use LiOH to remove acid)
  • water removal if the moisture content in the detection solution exceeds the standard (such as standard moisture ⁇ 20 ⁇ g/g).
  • Solution Pass through a molecular sieve, adjust the concentration, filter through a filter element and store it (for example, in barrels or tank cars).
  • LiFSI lithium bisfluorosulfonyl imide
  • various reaction raw materials and processing aids need to be used, such as triethylamine as reactant and solvent, ester solvent (such as diethyl carbonate DEC) for dehydration process, Dichloromethane (DCM) etc. are used for crystallization liquid, and various by-products and impurity ions are also produced, mainly F- produced in reaction 1 and alkali metal fluorides obtained after the alkalization process.
  • Recovery section A (alpha water alkalization): the product mixture produced by reaction 1 in the ⁇ stage of LiFSI production is separated into an oil phase mainly comprising (SO 2 F-NH-SO 2 F) ⁇ Et 3 N and an oil phase mainly comprising Aqueous phase of triethylamine hydrogen fluoride salt and impurity ions.
  • the separation of this step can be carried out by layering with a static mixer and a layered tank or by extracting through an extraction tower.
  • the obtained oil phase material ⁇ 3, mainly containing (SO 2 F-NH-SO 2 F) ⁇ Et 3 N
  • impurity ions mainly F -
  • the content of impurity ions in the oil phase obtained by stratification with a static mixer is 5-30 times the content of impurity ions in the oil phase obtained by extraction with an extraction tower, optionally 10- 20 times.
  • the concentration of F- in the oil phase obtained after extracting the product mixture through the extraction tower is 100-200 ppm; optionally, 100-160 ppm.
  • the F - concentration in the oil phase obtained by the stratification of the static mixer and the stratification tank can be as high as 1000-2000ppm.
  • the oil phase (material ⁇ 3) containing (SO 2 F-NH-SO 2 F) ⁇ Et 3 N was subjected to an alkalization process according to Reaction 2, and the water phase (material ⁇ water ) containing triethylamine hydrogen fluoride salt and impurity ions was ) into the alkalization kettle.
  • a certain amount of alkali metal hydroxide is added to the alkalization kettle, alpha water is pumped in according to the pH value, stirring is started, and alpha water and alkali metal hydroxide are mixed and reacted under normal temperature and pressure under stirring.
  • the range of pH value can be selected in the range of 8-14, such as 9-12.
  • the reaction time may be 0.5-6 hours, optionally 1-4 hours.
  • the alkali metal hydroxide may be selected from LiOH, NaOH or KOH; optionally, the alkali metal hydroxide is KOH. Then pass the solution obtained after the reaction in the alkalization kettle into the layered tank for phase separation. For example, when the alkali metal hydroxide is KOH, the resulting KF is easily soluble in water. Since triethylamine and KF aqueous solution have different densities and are immiscible, they can be separated by static layering.
  • the oil phase of the upper layer is an organic phase containing triethylamine and part of water, which is separated and stored in the oil phase secondary layering tank, and the subsequent oil containing triethylamine and part of water is obtained in the recovery section B. Combination of materials.
  • the lower layer is an aqueous phase mainly comprising an alkali metal fluoride solution, which may also contain a small amount of triethylamine.
  • the specific process flow of recovery section A is shown in Figure 3 of the present
  • Triethylamine recovery the product mixture obtained after the alkalization reaction 2 in the ⁇ section of LiFSI production is removed by an evaporator to remove triethylamine and part of the water, and the distilled triethylamine and The water is passed into the condenser to condense and stand for liquid separation.
  • Triethylamine is easily miscible with water when it is less than 18.5°C, and slightly soluble in water at a temperature of 30°C-55°C.
  • the centrifuge may be a disc centrifuge.
  • the oil phase is an organic phase comprising water and triethylamine; the organic phase and the organic phase comprising water and triethylamine obtained in recovery section A (stored in the oil phase secondary stratification tank) are all passed into Single-effect evaporation system for evaporation.
  • a single-effect evaporator can be selected for the single-effect evaporation system, and the required heating steam consumption can be calculated according to the production flux and operating parameters.
  • the single-effect evaporator refers to a single evaporator, and the secondary steam generated when the solution is evaporated is no longer used.
  • a water-containing triethylamine phase is obtained, and then the remaining water is further removed by dehydration in a dehydration tower and rectification in a rectification tower to finally obtain high-purity triethylamine.
  • the triethylamine obtained after rectification is passed into a triethylamine preparation tank for thorough stirring, and then stored in a triethylamine storage tank.
  • the purity of the obtained high-purity triethylamine is above 95% by weight; optionally, the purity is above 98% by weight, above 99% by weight or above 99.5% by weight.
  • the obtained triethylamine can be directly used back in the production of lithium bisfluorosulfonimide (LiFSI) of the present invention, for example, added to the reactor of Reaction 1, or transported to a special liquid material packaging barrel or tank truck for Takeaway.
  • LiFSI lithium bisfluorosulfonimide
  • the triethylamine used in the production of LiFSI can be recovered and reused in a high proportion, and the purity of the recovered triethylamine product is also high, which can significantly improve the production of LiFSI Raw material utilization and economy.
  • the aqueous phase separated by the centrifuge in the recovery section B is passed into the alkalinization process of Reaction 2 for alkali preparation, or passed into the extraction process as washing water, or passed into a sewage treatment device for treatment.
  • the materials used in each stage can be recycled or post-treated, which can significantly improve environmental protection.
  • the lower aqueous phase obtained by phase separation in the stratified tank of recovery section A mainly comprises alkali metal fluoride solution and a small amount of triethylamine;
  • the lower water phase is obtained by evaporation in the rectification tower, which also mainly contains alkali metal fluoride solution and a small amount of triethylamine.
  • the two streams of materials are combined in a brine tank, and then the liquid in the brine tank is passed into a stripping tower for stripping. By stripping, the liquid material can be separated into a light phase and a heavy phase.
  • the light phase mainly contains triethylamine and water, which are condensed and recovered, and returned to the oil phase secondary stratification tank of the recovery section A.
  • the recombination obtained after stripping is divided into an aqueous phase, mainly comprising alkali metal fluoride solution.
  • the heavy component is taken out from the stripping tower kettle, passed into a double-effect evaporator for evaporation, and the evaporated water is condensed to obtain a high-concentration alkali metal fluoride solution.
  • the double-effect evaporator connects two single-effect evaporators in series, uses the secondary steam generated by the first-effect evaporator as a heating source, and introduces it into another effect evaporator, as long as the pressure in the evaporator and the boiling point of the solution are controlled, so that If it is properly reduced, the secondary steam generated by the first effect evaporator can be used for heating.
  • the concentration of the alkali metal fluoride solution can be increased from 25% by weight to more than 50% by weight, or even more than 55% by weight, by evaporation in a double-effect evaporator.
  • the obtained high-concentration alkali metal fluoride solution can be transported to special liquid material packaging drums or tank trucks for external sale.
  • the difference in solubility of alkali metal fluorides at different temperatures can be utilized, and the alkali metal fluorides can be crystallized and precipitated by cooling the crystallization kettle, and then the alkali metal fluorides can be extracted by centrifugation.
  • the alkali metal can be Li, Na or K; correspondingly, the alkali metal fluoride is LiF, NaF or KF.
  • the alkali metal fluoride is KF.
  • the specific process flow of recovery section B is shown in Figure 4 of the present application.
  • Recovery section C the ⁇ section of the production of lithium bisfluorosulfonylimide includes a dehydration process, wherein the ester solvent is added to the evaporator and mixed with the alkalized reaction mixture from reaction 2, through Evaporation of the ester solvent takes the water away, and at the same time, new ester solvent is continuously replenished, thereby achieving continuous water removal.
  • the ester solvent may include, for example, ethyl methyl carbonate EMC, diethyl carbonate DEC, dimethyl carbonate DMC, and the like. The following uses diethyl carbonate DEC as an example to illustrate the recycling of ester solvents in detail; it can be understood that these descriptions are also applicable to other suitable ester solvents.
  • the water-containing DEC evaporated from the evaporator is passed into the condenser for condensation, and the obtained condensate is introduced into the condensate collection tank.
  • the condensed water-containing DEC is pumped into the DEC buffer tank, mixed with the lithium hydroxide solution through the pipeline mixer, and then separated by the coalescing separator, and the obtained oil phase is DEC, which is passed into the DEC storage tank.
  • the recovered DEC can be reused in the dehydration process (beta stage).
  • the water phase obtained after being separated by the coalescing separator is passed into a neutralization tank, and a lithium hydroxide solution is added to the tank to adjust the pH value.
  • the adjusted pH may be 8-14, optionally 9-12.
  • the material in the neutralization tank is passed through the preheater into the stripping tower for stripping, and the obtained oil phase is water-containing DEC, which is returned to the DEC buffer tank; the obtained water phase and raffinate are passed into the sewage treatment device for post-treatment.
  • the lithium hydroxide solution passed into the line mixer to be mixed with the aqueous DEC can be obtained from the lithium hydroxide solution of the ⁇ stage, can also be obtained by directly adding deionized water and lithium hydroxide, or obtained from a mixture of the two.
  • the lithium hydroxide solution can be pre-stored in a lithium hydroxide batching tank, and then passed into a pipeline mixer to mix with water-containing DEC.
  • the lithium hydroxide solution can be directly pumped from the lithium hydroxide batching tank into the neutralization tank to adjust the pH value of the aqueous phase obtained after being separated by the coalescing separator.
  • the purity of the DEC in the liquid stream passed to the DEC storage tank may be above 95% by weight; alternatively, the purity may be above 98% by weight, or above 99% by weight.
  • the specific process flow of the recovery section C is shown in Figure 5 of the present application, in which DEC is specifically used as an example of the ester solvent.
  • Recovery section D (recovery of crystallization liquid): In the process of producing lithium bisfluorosulfonyl imide by crystallization process, it is also necessary to recycle or reuse the used crystallization liquid.
  • the main component of the crystallization liquid used is dichloromethane (DCM). Pass the crude lithium bisfluorosulfonyl imide (stream ⁇ 3) that has been processed through the precipitation process into a crystallization kettle, and add dichloromethane crystallization liquid into it.
  • Dichloromethane is used to dissolve DEC but not LiFSI, so that LiFSI is supersaturated and precipitated in DEC, and crystal nuclei grow.
  • the water-washed oil phase containing crystallization liquid separated from the two-in-one device contains methylene chloride, water, ester solvents and impurity salts such as LiF.
  • the water-washed oil phase (dichloromethane, diethyl carbonate, water, salt, etc.) is pumped into a dehydration tower for dehydration.
  • the condensate at the top of the tower is mainly dichloromethane and water, which is subjected to liquid separation treatment, and the separated water is collected in the sewage collection tank, and all the separated dichloromethane is returned to the tower.
  • the bottom liquid of the dehydration tower is passed into a single-effect evaporation system, and the gas phase obtained by evaporation is passed into a rectification tower for rectification, and dichloromethane is obtained from the overhead condensate of the rectification tower, and collected in a dichloromethane blending tank , add lithium hydroxide to the tank, adjust the pH value and separate phases through the pump circulation pipeline, separate the obtained water phase for post-treatment, and pass the obtained oil phase into the dichloromethane storage tank.
  • the recovered dichloromethane can be reused in the crystallization process.
  • the ethanol is separated from the middle of the rectification tower for post-treatment; the ester solvent is obtained from the condensate in the middle and lower part of the rectification tower, which is passed into the ester solvent storage tank for the dehydration process to return Use; Separation of the raffinate obtained from the bottom of the rectifying tower for post-treatment.
  • the liquid phase obtained from the single-effect evaporation system is vacuum-concentrated, and the obtained condensate contains dichloromethane and ester solvents, and is sent back to the dehydration tower; the vacuum-concentrated concentrate is separated for post-processing.
  • the specific process flow of recovery section D is shown in Figure 6 of the present application.
  • dichloromethane exhaust gas recovery dichloromethane is a volatile liquid. During the crystallization process and subsequent crystallization liquid recovery process, due to the temperature rise, the exhaust gas discharged from each stage contains a certain amount of dichloromethane. Chloromethane. The dichloromethane discharged through the waste gas also needs centralized treatment and recovery. After cooling the waste gas with dichloromethane from each process flow (such as the two-in-one equipment in the crystallization process, the dehydration tower and the rectification tower), it is passed into the third-stage adsorption resin for adsorption, and it is used after the adsorption is saturated.
  • dichloromethane exhaust gas recovery dichloromethane exhaust gas recovery
  • the steam is desorbed, and then collected by condensation, and the collected liquid containing dichloromethane and water is left to stand for stratification.
  • the upper water phase contains a small amount of dichloromethane, which is separated as waste water for post-treatment; the lower oil phase is the water containing a small amount of water.
  • Dichloromethane is passed into a dehydration device for dehydration to a certain limit and then reused.
  • the exhaust gas with dichloromethane can be cooled by normal temperature water.
  • the tertiary adsorption resin can be a polar adsorption resin, such as an adsorption resin with polar functional groups such as amide groups, cyano groups, and phenolic hydroxyl groups.
  • the dehydration is performed through 4A molecular sieves.
  • the 4A molecular sieve has a pore size of 4A, which can absorb water molecules but not dichloromethane, so as to realize the dehydration of the dichloromethane oil phase containing a small amount of water.
  • the water content in the dichloromethane oil phase containing trace moisture is 1000-2000ppm, and the dehydration is carried out to a water content of 50-200ppm; alternatively, the dehydration is carried out to a water content of 50-100ppm.
  • the specific process flow of recovery section E is shown in Figure 7 of the present application.
  • LiFSI lithium bisfluorosulfonyl imide
  • LiFSI lithium bisfluorosulfonyl imide
  • the obtained reaction mixture stream ⁇ 1 (comprising 40% by weight of (SO 2 F—NH—SO 2 F) ⁇ Et 3 N, 18% by weight of triethylamine hydrogen fluoride salt and 6% by weight of triethylamine) Filter through a tetrafluoro filter bag with a pore size of 5 ⁇ m to filter out the solid by-product sulfonamide. Pump the filtrate into the falling film evaporator (the temperature of the hot water bucket is 75°C), and remove the solvent in the filtrate under the vacuum degree of -0.02MPa (the front stage of the vacuum pump is condensed with 0°C water, and the latter stage is condensed with -15°C water).
  • stream ⁇ 2 comprising (SO 2 F—NH—SO 2 F) ⁇ Et 3 N and triethylamine hydrogen fluoride salt (which contained 70% by weight of (SO 2 F—NH—SO 2 F) ⁇ Et 3 N, 28% by weight of triethylamine hydrogen fluoride) and condensate containing acetonitrile.
  • the condensate is recycled for the synthesis in the first step of the synthesis tank.
  • the lower oil phase ⁇ 3 is sent to the alkalization step. It was detected that the oil phase ⁇ 3 also contained 100ppm of F - .
  • the upper water phase ⁇ water is sent to the recovery workshop for treatment (recovery workshop section A).
  • alpha water is pumped into a 100m 3 alkalization tank, and stirring is started.
  • potassium hydroxide solution (5mol/L) in the alkalization kettle, adjust the pH value of the liquid in the alkalization kettle and keep it in the range of 8-10.
  • pump the alkalization tank solution into the layered tank for 2 hours of phase separation.
  • the water phase is potassium fluoride solution (containing a small amount of triethylamine), which is separated and pumped to recovery section B;
  • the oil phase is the organic phase of water and triethylamine, which is separated and pumped to recovery section B.
  • the oil phase ⁇ 3 containing (SO 2 F-NH-SO 2 F) ⁇ Et 3 N was directly basified in evaporator B (hot water barrel steam heating temperature 35°C), and lithium hydroxide aqueous solution (concentration 5mol/L, Wherein the volume ratio of the stream ⁇ 3 to the lithium hydroxide aqueous solution is 1.1:1) while constantly stirring. After 1 hour of reaction, the mixture stream ⁇ 1-1 (crude lithium salt) was obtained. Use 35°C hot water for heating and turn on the vacuum. Keep the vacuum degree in the kettle at -0.08MPa, and the steaming time is about 6 hours.
  • the front and rear stages of the vacuum pump use 25°C water and 0°C water to carry out five-stage condensation respectively, and the condensate is left to stand and separated.
  • the condensed water of the lower layer is returned to the alkalization process to prepare an aqueous solution of lithium hydroxide. Due to the decomposition of some products during the evaporation process, it is necessary to continuously add lithium hydroxide solution (concentration is 5mol/L) to keep the pH at about 8.
  • the supernatant is an aqueous solution of triethylamine, which is pumped to the recovery workshop for recovery (recovery section B).
  • the triethylamine aqueous solution is passed into the triethylamine transfer tank, and is separated into a water phase and an oil phase by a disc centrifuge.
  • the oil phase is an organic phase containing water and triethylamine; the organic phase is combined with the organic phase containing water and triethylamine obtained in recovery section A and passed into a single-effect evaporator for evaporation to obtain a water-containing triethylamine phase .
  • dehydration through the dehydration tower and rectification through the rectification tower to remove the remaining water respectively to obtain high-purity triethylamine.
  • the recovery rate of the recovered triethylamine was calculated to be 93%, and the purity was 99.2% by weight through gas chromatography quantitative analysis.
  • the chromatographic parameters are set as follows: column oven temperature 40-260°C, detector type FID/TCD, detector temperature 300°C, air pressure 0.4MPa, hydrogen flow rate 30ml/min, air flow rate 400ml/min.
  • the lower aqueous phase obtained by phase separation in the layered tank of recovery section A mainly contains KF solution and a small amount of triethylamine. It is combined with the lower water phase obtained in the single-effect evaporation system, dehydration tower and rectification tower in the recovery section B in the brine tank. After the liquid in the brine tank is passed into the stripping tower for stripping, the light phase obtained mainly contains triethylamine and water, and is returned to the oil phase secondary stratification tank of recovery section A; The fraction mainly contains KF solution, and the heavy component is passed into a double-effect evaporator for evaporation to obtain a high-concentration KF solution.
  • the recovery rate of KF in the recovered high-concentration KF solution was 88%, and the concentration was 56.8% by weight through ion chromatography quantitative analysis.
  • the chromatographic parameters are set as follows: column temperature 30-45°C, detector DS5 conductivity detector, analytical column Shodex IC SI-90 4E, 4.6 ⁇ 250mm, guard column Shodex IC SI-90G, 4.6 ⁇ 10mm, eluent flow rate 1.0mL/min, regeneration solution flow rate 1.0mL/min.
  • the aqueous solution of the product lithium bisfluorosulfonyl imide (referred to as ⁇ 1-2) continues to evaporate in the falling film evaporator C (hot water tank steam heating temperature 50°C).
  • metering pumps diethyl carbonate (DEC) control the flowmeter so that the volume ratio of DEC to material flow ⁇ 1-2 is 0.6:1)
  • vacuum -0.08MPa
  • the condensate is an aqueous solution containing DEC.
  • the DEC-containing aqueous solution is stored in a collection tank and sent to a recovery workshop for recovery (recovery section C).
  • the stream ⁇ 2 (it comprises the bisfluorosulfonyl imide lithium of 70% by weight and the diethyl carbonate of 29% by weight and the water of 1% by weight ).
  • an aqueous solution of lithium hydroxide (concentration 5 mol/L) was metered in such that the pH of the stream ⁇ 2 was kept at 8.
  • the stream obtained after being evaporated by the falling film evaporator C is filtered, and the by-product lithium compound is filtered out to obtain a filtrate containing 1% by weight of water, 30% by weight of diethyl carbonate and 69% by weight of lithium difluorosulfonimide beta 2-1.
  • the filtrate ⁇ 2-1 is then pumped into the scraper evaporator D (hot water barrel steam heating temperature 75°C), heated and evaporated in a vacuum (vacuum degree -0.08MPa) for dehydration.
  • the condensate mainly includes DEC and a small amount of water, and the condensate is sent to the recovery workshop for recovery (recovery section C).
  • Lithium bisfluorosulfonimide ⁇ 3 (comprising 85% by weight of lithium bisfluorosulfonylimide and 15% by weight of diethyl carbonate) with a water content of 3000 ppm was obtained after evaporation for 6 hours.
  • the aqueous DEC is passed into the DEC buffer tank, and mixed with a 50% by weight lithium hydroxide solution in a pipeline mixer, so that its pH value is adjusted to 8-9.
  • the combined liquid streams are then separated by a coalescer.
  • the oil phase obtained after separation is mainly DEC, which is passed into the DEC storage tank.
  • the purity of DEC in the liquid material obtained in the DEC storage tank was 98.6% by weight through gas chromatography quantitative analysis.
  • the crystallization liquid washing oil phase (dichloromethane, DEC, water, salt, etc.) is pumped into the dehydration tower for dehydration.
  • the condensate at the top of the tower is mainly dichloromethane and water, which is subjected to liquid separation treatment, and the separated water is collected in the sewage collection tank, and all the separated dichloromethane is returned to the tower.
  • the bottom liquid of the dehydration tower is passed into the single-effect evaporator, and the gas phase obtained by evaporation is passed into the rectification tower for rectification, and dichloromethane is obtained from the overhead condensate of the rectification tower, and collected in the dichloromethane deployment tank .
  • the gas mainly contains methylene chloride waste gas and evaporated water. Pass the collected exhaust gas into the methylene chloride absorption and recovery device, and first cool it with normal temperature water. After cooling, it is passed into the third-stage adsorption resin for adsorption, and after the adsorption is saturated, it is desorbed with steam. After condensing, it was collected, and the collected dichloromethane and water were left to stand and separated.
  • the upper liquid water contains a small amount of dichloromethane, which is used as wastewater for post-treatment; the lower liquid dichloromethane contains about 1800ppm of water, which is pumped into a 4A molecular sieve dehydration device for dehydration to below 150ppm before reuse.
  • the recovery rate of KF in the obtained KF solution is 79%, and the concentration is 42.8% by weight through ion chromatography quantitative analysis.

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Abstract

本申请涉及一种在双氟磺酰亚胺锂的生产中回收原辅材料的方法。所述方法包括一个或多个不同的回收工段A、B、C、D和/或E，分别对应于在双氟磺酰亚胺锂的生产中使用的原辅材料例如三乙胺、氟离子、酯类溶剂、析晶液等的回收和后处理。本申请的回收原辅材料的方法使得双氟磺酰亚胺锂的生产具有明显改善的经济性和环保性。

Description

一种在双氟磺酰亚胺锂的生产中回收原辅材料的方法 技术领域
本申请涉及一种在双氟磺酰亚胺锂的生产中回收原辅材料的方法，尤其涉及一种通过不同的回收工段回收在生产双氟磺酰亚胺锂所产生废液中的三乙胺、氟化物、酯类溶剂、析晶液和/或二氯甲烷废气的方法。
背景技术
双氟磺酰亚胺锂(化学式Li[N(SO 2F) 2]，英文缩写LiFSI)是一种重要的含氟新材料。由于其特殊的分子结构，Li +与FSI -之间具有较低的结合能，有利于Li +的解离，因而在电解液中添加LiFSI，能获得较高的电导率。同时，LiFSI还具有热稳定性高、电化学窗口较宽、腐蚀速率较低的特性，尤其在动力电池中，可改善动力电池的循环性能以及倍率性能，有望成为锂离子电池的新型电解质锂盐。2012年日本触媒首次展示LiFSI，并于2013年实现产业化生产。目前日韩电池企业已在高端场合，将LiFSI和LiPF 6混合使用。
LiFSI目前尚无法大规模使用，其原因主要是由于合成工艺条件的限制导致了生产成本高昂。在合成过程中，存在着工艺繁琐、流程较长、产品转化率低、能耗较大和环境污染等缺点。另外，作为锂离子二次电池电解质，需要满足高纯度、无水等苛刻要求。尤其是水分引入后，通过升温带水、干燥除水直至分解都很难彻底除去，即使能除去也需损失较大的收率。
另外，在对LiFSI进行工业化合成以及提纯过程中，需要对使用的原辅材料进行充分地回收利用，并且尽可能降低三废(废水、废气和固体废弃物)的产生。
发明内容
本申请是鉴于上述课题而进行的，其目的在于提供一种在双氟磺酰亚胺锂的生产中回收原辅材料的方法，以提高在双氟磺酰亚胺锂的生产中原辅材料的回收利用度并改善生产双氟磺酰亚胺锂的经济性和环保性。
为了达到上述目的，本申请第一方面提供一种在双氟磺酰亚胺锂的生产中回收原辅材料的方法，所述双氟磺酰亚胺锂的生产包括使硫酰氟、三乙胺与氨气反应的反应1以及随后对反应产物进行碱化的反应2，
反应1：SO 2F 2+NH 3+Et 3N→(SO 2F-NH-SO 2F)·Et 3N+Et 3N·(HF) n(n＝1-12)，
反应2：(SO 2F-NH-SO 2F)·Et 3N+LiOH→(SO 2F-N-SO 2F) -Li ++Et 3N+H 2O，
所述方法包括：
回收工段A:将反应1产生的产物混合物分离为包含(SO 2F-NH-SO 2F)·Et 3N的油相和包含三乙胺氟化氢盐以及杂质离子的水相；将包含(SO 2F-NH-SO 2F)·Et 3N的油相根据反应2进行碱化工艺，而将包含三乙胺氟化氢盐以及杂质离子的水相通入碱化釜中与碱金属氢氧化物在搅拌下混合并反应，然后将碱化釜中反应后得到的溶液通入分层罐中分相；上层的油相为包含水和三乙胺的有机相，将其分离出并储存于油相二次分层罐中；以及
回收工段B：将根据反应2进行碱化工艺得到的产物混合物通过蒸发器移除三乙胺和部分的水，并将蒸出的三乙胺和水通入冷凝器中冷凝并静置分液；将分液后得到的上层三乙胺溶液转入三乙胺中转罐，经离心机分离为水相和油相，所述油相为包含水和三乙胺的有机相；将所述有机相与 所述回收工段A中得到的包含水和三乙胺的有机相一起通入单效蒸发系统，得到含水的三乙胺相；然后分别通过脱水塔脱水和通过精馏塔精馏移除剩余水分，得到高纯度三乙胺。
在任意实施方式中，所述回收方法是作为双氟磺酰亚胺锂的生产和提纯的一整套流程的一部分，其包含了多个回收工段，对应于不同的原辅材料的分离和回收。各回收工段之间也可以存在物质交流以及合并。
在任意实施方式中，所述方法得到的高纯度三乙胺的纯度为95重量％以上；可选的，所述纯度为98重量％以上，99重量％以上或者99.5重量％以上。在任意实施方式中，在所述回收工段B中将碱化工艺得到的产物混合物通过蒸发器蒸出包含三乙胺和水的混合物，将该混合物在冷凝器中冷凝后，加热至30-55℃的温度并静置分层。在任意实施方式中，回收工段A中反应1产生的产物混合物通过静态混合器分层或通过萃取塔萃取来分离。
在任意实施方式中，所述回收工段A的分层罐中通过分相得到的下层水相主要包含碱金属氟化物溶液以及少量三乙胺；将其与回收工段B中在单效蒸发系统、脱水塔和精馏塔中得到的下层水相合并于盐水罐中；将所述盐水罐中的液体通入汽提塔汽提后，得到的轻相主要包含三乙胺和水，返回至回收工段A的油相二次分层罐中；汽提后得到的重组分主要包含碱金属氟化物溶液，将所述重组分通入双效蒸发器中蒸发，得到高浓度碱金属氟化物溶液。在任意实施方式中，所述碱金属为Li、Na或K。
在任意实施方式中，所述双氟磺酰亚胺锂的生产还包括使用酯类溶剂进行的脱水工艺，通过蒸发蒸出的含水酯类溶剂通过回收工段C进行回收，回收工段C：将含水酯类溶剂通入酯类溶剂缓冲罐中，与氢氧化锂溶液在管道混合器中混合，然后经聚结分离器分离；分离后得到的油相主要为酯类溶剂，通入酯类溶剂储存罐。进一步地，经聚结分离器分离后得到 的水相加入氢氧化锂溶液调节pH值后，经预热器进入汽提塔汽提，得到的油相为含水的酯类溶剂，返回酯类溶剂缓冲罐；得到的水相及残液通入污水处理装置进行后处理。
在任意实施方式中，所述酯类溶剂包括碳酸甲乙酯EMC、碳酸二乙酯DEC以及碳酸二甲酯DMC。
在任意实施方式中，所述双氟磺酰亚胺锂的生产还包括使用析晶液溶解酯类溶剂并析出产物LiFSI晶体的析晶工艺，分离出的析晶液水洗油相包含二氯甲烷、酯类溶剂、水和盐；所述析晶液通过回收工段D进行回收，回收工段D：将所述析晶液水洗油相通入脱水塔，塔顶冷凝液包含二氯甲烷和水，分层后上层的水相通入污水收集池进行后处理，下层的二氯甲烷全部回流；将所述脱水塔的塔釜液通入单效蒸发系统，蒸发得到的气相通入精馏塔精馏，从精馏塔的塔顶冷凝液中得到二氯甲烷，收集至二氯甲烷调配罐，向所述罐中加入氢氧化锂，通过泵循环管路调节pH值并分相，得到的水相分离进行后处理，得到的油相通入二氯甲烷储存罐。
在任意实施方式中，从所述精馏塔的中部得到乙醇分离进行后处理；从所述精馏塔的中下部冷凝液中得到酯类溶剂，通入酯类溶剂储存罐中供脱水工艺回用；从所述精馏塔的塔釜得到的残液分离进行后处理。
在任意实施方式中，从单效蒸发系统中得到的液相经过真空浓缩，得到的冷凝液包含二氯甲烷和酯类溶剂，送回脱水塔；真空浓缩的浓缩液分离进行后处理。
在任意实施方式中，所述所述方法还包含回收工段E来回收各阶段产生的包含二氯甲烷的废气，回收工段E：将各阶段产生的包含二氯甲烷的废气冷却后通入三级吸附树脂中进行吸附，吸附饱和后使用蒸汽脱附，然后通过冷凝收集，收集得到的包含二氯甲烷和水的液体静置分层，上层水相中含有微量二氯甲烷，作为废水分离进行后处理；下层油相为含有微量 水分的二氯甲烷，通入脱水装置中进行脱水后进行回用。
在任意实施方式中，所述含有微量水分的二氯甲烷中的水含量为1000-2000ppm，并且所述脱水进行至水含量为50-200ppm。在任意实施方式中，所述脱水通过4A分子筛进行。
通过如上所述回收原辅材料的方法，可以在多个不同的回收工段将在双氟磺酰亚胺锂的生产中使用的至少一种或多种原辅材料进行回收利用，并且对产生的三废物质进行后处理，由此使得双氟磺酰亚胺锂的生产具有明显改善的经济性和环境友好性。
附图说明
为了更清楚地说明本申请的技术方案，下面将对本申请实施例中所需要使用的附图作简单的介绍。显而易见地，下面所描述的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。
图1是本申请的一个实施方式中生产双氟磺酰亚胺锂的工艺的α段的工艺流程示意图。
图2是本申请一个实施方式中生产双氟磺酰亚胺锂的工艺的β段的工艺流程示意图。
图3是本申请一个实施方式中回收工段A(α水碱化)的工艺流程示意图。
图4是本申请一个实施方式中回收工段B(三乙胺回收)的工艺流程示意图。
图5是本申请一个实施方式中回收工段C(酯类溶剂回收，以DEC为例)的工艺流程示意图。
图6是本申请一个实施方式中回收工段D(析晶液回收)的工艺流程 示意图。
图7是本申请一个实施方式中回收工段E(二氯甲烷废气回收)的工艺流程示意图。
具体实施方式
为了简明，本申请具体地公开了一些数值范围。然而，任意下限可以与任意上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，每个单独公开的点或单个数值自身可以作为下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
双氟磺酰亚胺锂(LiFSI)由于其特殊的分子结构，使得在电解液中添加LiFSI，能获得较高的电导率。同时，LiFSI还具有热稳定性高、电化学窗口较宽、腐蚀速率较低的特性，尤其在动力电池中，可改善动力电池的循环性能以及倍率性能，因此是锂离子电池的电解质锂盐的极佳选择。现有技术中合成以及提纯LiFSI在工业化大规模生产中存在诸多问题，其合成过程工艺繁琐、流程较长、产品转化率低，并且原辅材料消耗量大且难以回收，因此经济性不高。本发明旨在解决这些问题中的至少一些，并提出了新的生产LiFSI的工艺以及回收原辅材料的方法。
生产LiFSI的工艺主要包括以下步骤：
合成：使硫酰氟、氨气、三乙胺充分混合，使硫酰氟、氨气充分反应，而三乙胺既当溶剂又参与反应。还可使用其他有机溶剂，如乙腈，作为反应的溶剂。主反应为SO 2F 2+NH 3+Et 3N→(SO 2F-NH-SO 2F)·Et 3N+Et 3N·(HF) n(n＝1-12)。
当反应釜内温度过高时，会发生以下副反应而影响收率：NH 3+SO 2F 2+Et 3N→NH 2-SO 2-NH 2(磺酰胺，固体)+Et 3N·(HF) n(三乙胺氟化氢盐，溶于CH 3CN中，n＝1-12)。反应后可采用例如5μm四氟过滤袋将副产物磺酰胺固体过滤掉。
合成工序后，物料组成主要包括(SO 2F-NH-SO 2F)·Et 3N、乙腈、三乙胺氟化氢盐、三乙胺(少量)以及杂质离子。所述杂质离子主要包含F -、SO 4 2-、FSO 3 -以及Cl -。
蒸发：将产物混合物(物料α1)通入蒸发器蒸发，分离出乙腈溶剂。可使用降膜蒸发器给物料加热，通过气液分离器使液体与蒸汽分离，再使用冷凝器冷凝蒸汽乙腈(含少量三乙胺)，回用于第一步的合成。
蒸发工序后，物料组成主要包括(SO 2F-NH-SO 2F)·Et 3N、三乙胺氟化氢盐、乙腈(微量)以及杂质离子。
萃取：将蒸发得到的浓缩液(物料α2)用水洗涤，将易溶于水的杂质(主要为三乙胺氟化氢盐)洗除。为此可使用两种方案：
方案一、萃取塔，底部进轻相(密度小)，上部出轻相，顶部进重相，底部出重相，中间搅拌为呈螺旋状；方案二、静态混合器和分相槽。萃取油相(物料α3)主要包含(SO 2F-NH-SO 2F)·Et 3N，而萃取水相(物料α水)主要包含三乙胺氟化氢盐和杂质离子(如F -、SO 4 2-、FSO 3 -、Cl -)。在一些实施方案中，采用萃取塔进行萃取，可实现对于杂质离子(例如F -)的更好地分离。在一些实施方案中，通过静态混合器萃取而得到的油相中的杂质离子的含量为萃取塔萃取而得到的油相中的杂质离子含量的5-30倍，可选地为10-20倍。可选地，所述杂质离子为F -。在本申请的双氟磺酰亚胺锂的生产中合成-蒸发-萃取的阶段称为α段，其具体流程可参照本申请图1的工艺流程图。
碱化：将萃取后得到的萃取油相(物料α3)与氢氧化锂水溶液混合并充分反应。所述反应为反应2：(SO 2F-NH-SO 2F)·Et 3N+LiOH→(SO 2F-N-SO 2F) -Li ++Et 3N+H 2O。反应原理为强碱置换弱碱，LiOH碱性高于(SO 2F-NH-SO 2F)·Et 3N中的三乙胺，使得三乙胺被置换出。通过降膜蒸发除去三乙胺，同时LiOH与(SO 2F-NH-SO 2F)·Et 3N产生反应生成锂盐(双氟磺酰亚胺锂，简称为LiFSI)。
脱水：将反应2得到的反应混合物(物料β1)使用蒸发器脱水。采用酯类溶剂带水，不涉及化学反应。因锂盐的吸水性非常强，若单纯靠蒸发来将水分降低至目标要求是不现实的。补加大量酯类溶剂可以减弱锂盐对水的吸附性，一边补加酯类溶剂，一边蒸发酯类溶剂的过程中可以将水分降低至目标要求。酯类溶剂经过回收段提纯处理后可以回用。所述酯类溶剂可包括碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)等。脱水过程中(SO 2F-N-SO 2F) -Li +也在分解，生成副产物LiF、Li 2SO 4、氨基磺酸锂等。在接下来的脱溶工序前要把固体副产物过滤或离心出来(例如使用离心沉降除固渣，如刮刀离心机或碟式离心机)。
脱溶：将蒸发脱水后的物料(物料β2)在蒸发器中进行脱溶。脱溶不涉及到反应，只是为了将酯类溶剂蒸发出去。因为锂盐是溶解于酯类溶剂的，若不将酯类溶剂蒸发到一定程度(如从60％-65％到30％)，则后期无法析晶或析晶率很低。酯类溶剂经过回收段提纯处理后可以回用。脱溶工序后得到含水量较低(例如低于3000ppm)的双氟磺酰亚胺锂粗品(物料β3)。在本申请的双氟磺酰亚胺锂的生产中碱化-脱水-脱溶的阶段称为β段，其具体流程可参照本申请图2的工艺流程图。
析晶：析晶指的是当物质在处于非平衡态时，会析出另外的相，该相以晶体的形式被析出。将物料β3通入析晶釜，并加入二氯甲烷。利用二氯甲烷溶解酯类溶剂而不溶解LiFSI，使得LiFSI在酯类溶剂中过饱和析 出，晶核生长。将得到的混合物通入带过滤洗涤功能的二合一设备中，将附着在LiFSI晶体表面的其他杂质洗掉。析晶液经过回收段提纯处理后，酯类溶剂和二氯甲烷可以回用。
干燥：将洗涤后的物料通入干燥釜。将氮气加热后，通入干燥釜内。物料在搅拌和气流作用下形成流态化，在大面积气固两相接触中，物料水分快速蒸发，高湿度氮气排出釜内，使物料达到干燥要求。
在一些实施方案中，可以不进行上述析晶和干燥步骤，而将物料β3直接投入溶解工序。
溶解：在溶解工序中，可根据需要选择用酯类溶剂如碳酸甲乙脂(EMC)或碳酸二甲酯(DMC)溶解以上干燥的晶体(对于析晶方法)或粗产物(对于不析晶方法)，除酸(若检测溶液中HF含量超标(如标准HF≤50μg/g)，用LiOH进行除酸)，除水(若检测溶液中水分含量超标(如标准水分≤20μg/g)。溶液过分子筛，调浓，过滤芯过滤后进行储存(例如装桶或装槽罐车)。
以上就是本发明中生产双氟磺酰亚胺锂(LiFSI)的一般性流程。在LiFSI的合成和提纯的过程中，需要用到多种反应原料以及加工助剂，如作为反应物和溶剂的三乙胺、用于脱水工序的酯类溶剂(如碳酸二乙脂DEC)、用于析晶液的二氯甲烷(DCM)等，并且还会产生多种副产物以及杂质离子，主要为反应1中产生的F -以及随后在碱化工序后得到的碱金属氟化物。这些原辅材料构成本发明中LiFSI生产的相当一部分成本，因此需要尽可能地回收再利用，并且由于环保的因素，产生的副产物和杂质也需要尽可能地处理及回收。在此基础上，本发明人提出了针对该生产工艺中使用的原辅材料进行回收利用的方法。所述方法包含了多个不同的回收工段，这些回收工段与生产LiFSI的工艺流程紧密结合并整合于其中，实现了对于主要的原辅材料的分阶段的分离和回收。下文根据附图中的回 收工段A-E中的工艺流程示意图对在双氟磺酰亚胺锂的生产中回收原辅材料的方法进行详细描述。
回收工段A(α水碱化)：将在LiFSI生产的α段中的反应1产生的产物混合物分离为主要包含(SO 2F-NH-SO 2F)·Et 3N的油相和主要包含三乙胺氟化氢盐以及杂质离子的水相。这一步的分离可通过静态混合器与分层槽分层或通过萃取塔萃取进行。出人意料地，发现当通过萃取塔萃取反应1的产物混合物时，得到的油相(物料α3，主要包含(SO 2F-NH-SO 2F)·Et 3N)中的杂质离子(主要为F -)的含量显著低于通过静态混合器与分层槽分层得到的油相中的杂质离子。在一些实施方案中，通过静态混合器分层而得到的油相中的杂质离子的含量为通过萃取塔萃取而得到的油相中的杂质离子含量的5-30倍，可选地为10-20倍。在一些实施方案中，通过萃取塔萃取产物混合物后得到的油相中F -的浓度为100-200ppm；可选的，为100-160ppm。与之相比，通过静态混合器与分层槽分层而得到的油相中的F -的浓度可高达1000-2000ppm。
将包含(SO 2F-NH-SO 2F)·Et 3N的油相(物料α3)根据反应2进行碱化工艺，而将包含三乙胺氟化氢盐以及杂质离子的水相(物料α水)通入碱化釜中。具体来说，加入一定量碱金属氢氧化物至碱化釜中，根据pH值泵入α水，开启搅拌，常温常压下使α水与碱金属氢氧化物在搅拌下混合并反应。pH值范围可选定在8-14范围内，例如9-12。反应时间可为0.5-6小时，可选地为1-4小时。所述碱金属氢氧化物可选自LiOH、NaOH或KOH；可选地，所述碱金属氢氧化物为KOH。然后将碱化釜中反应后得到的溶液通入分层罐中分相。例如，在碱金属氢氧化物为KOH的情况下，生成的KF易溶于水。由于三乙胺与KF水溶液密度不同且不相溶，可以通过静置分层来进行分离。上层的油相为包含三乙胺和部分水的有机相，将其分离出并储存于油相二次分层罐中，后续与回收工段B中得到的 同样包含三乙胺和部分水的油相物料合并。下层为主要包含碱金属氟化物溶液的水相，其中还可包含少量的三乙胺。回收工段A的具体工艺流程如本申请的图3所示。
回收工段B(三乙胺回收)：在LiFSI生产的β段中的碱化反应2结束后得到的产物混合物通过蒸发器移除三乙胺和部分的水，并将蒸出的三乙胺和水通入冷凝器中冷凝并静置分液。三乙胺在小于18.5℃时易与水互溶，而在30℃-55℃温度下微溶于水。利用此特性，将所述低温冷凝回收的三乙胺和水的混合液加热至30℃-55℃，可选地为40℃-45℃后静置分层，除去下层水分，达到初步除水的目的。
将分液后得到的上层三乙胺溶液转入三乙胺中转罐中，经离心机分离为水相和油相。所述离心机可为碟片式离心机。所述油相为包含水和三乙胺的有机相；将该有机相与回收工段A中得到的包含水和三乙胺的有机相(储存于油相二次分层罐中)均通入单效蒸发系统进行蒸发。所述单效蒸发系统可以选择单效蒸发器，根据生产通量和操作参数可计算出需要的加热蒸汽消耗量。单效蒸发器是指单一的蒸发器，它在进行溶液蒸发时所产生的二次蒸汽不再利用。蒸发后得到含水的三乙胺相，然后分别通过脱水塔脱水和通过精馏塔精馏进一步移除剩余水分，最终得到高纯度三乙胺。在一些实施方案中，将精馏后得到的三乙胺通入三乙胺调配罐中充分搅拌，然后储存于三乙胺储存罐中。在一些实施方案中，得到的高纯度三乙胺的纯度为95重量％以上；可选的，所述纯度为98重量％以上、99重量％以上或者99.5重量％以上。所得到的三乙胺可以直接回用于本发明的双氟磺酰亚胺锂(LiFSI)的生产中，例如加入反应1的反应釜中，或输送至特制液料包装桶或槽车，进行外售。通过回收工段A与回收工段B的结合，可以将LiFSI的生产中使用的三乙胺以很高的比例回收再利用，并且 回收的三乙胺产品的纯度也很高，这样可以明显改善LiFSI生产的原材料利用度和经济性。
在一些实施方案中，回收工段B中通过离心机分离出的水相通入反应2的碱化工艺中配碱，也可以通入萃取工艺中作为水洗水，或者通入污水处理装置进行处理。在本发明的方法中，各阶段用到的物质均可以进行回收利用或者后处理，可显著改善环保性。
在一些实施方案中，在回收工段A的分层罐中通过分相得到的下层水相主要包含碱金属氟化物溶液以及少量三乙胺；在回收工段B中在单效蒸发系统、脱水塔和精馏塔中通过蒸发得到下层水相，其同样主要包含碱金属氟化物溶液以及少量三乙胺。将这两股物料合并于盐水罐中，然后将所述盐水罐中的液体通入汽提塔汽提。通过汽提，所述液体物料可分为轻相和重相。所述轻相主要包含三乙胺和水，将其进行冷凝回收，返回至回收工段A的油相二次分层罐中。汽提后得到的重组分为含盐水相，主要包含碱金属氟化物溶液。将所述重组分从汽提塔塔釜中采出，通入双效蒸发器中蒸发，并冷凝蒸出的水分，得到高浓度碱金属氟化物溶液。双效蒸发器是将两个单效蒸发器串联起来，将第一效蒸发器产生的二次蒸汽当作加热源，引入另一效蒸发器，只要控制蒸发器内的压力和溶液沸点，使其适当降低，则可利用第一效蒸发器产生的二次蒸汽进行加热。在一些实施方案中，通过双效蒸发器蒸发，可将碱金属氟化物溶液的浓度从25重量％提高到50重量％以上，甚至55重量％以上。得到的高浓度碱金属氟化物溶液可输送至特制液料包装桶或槽车，进行外售。
在一些实施方案中，可利用碱金属氟化物在不同温度下溶解度差异，通过在结晶釜降温，让碱金属氟化物结晶析出，再经过离心分离，把碱金属氟化物提取出来。所述碱金属可为Li、Na或K；相应地，所述碱金属氟化物为LiF、NaF或KF。
在一些实施方案中，所述碱金属氟化物为KF。通过对碱金属氟化物的回收，可进一步提高LiFSI生产的经济性以及环保性。回收工段B的具体工艺流程如本申请的图4所示。
回收工段C(酯类溶剂回收)：在双氟磺酰亚胺锂的生产的β工段包含脱水工序，其中将酯类溶剂加入蒸发器中与碱化后的来自反应2的反应混合物混合，通过蒸发酯类溶剂将水带走，同时不断补充新的酯类溶剂，从而实现连续除水。所述酯类溶剂可包含例如碳酸甲乙酯EMC、碳酸二乙酯DEC、碳酸二甲酯DMC等。下文以碳酸二乙酯DEC为例，详细阐述酯类溶剂的回收利用；可以理解的是，这些描述对于其他合适的酯类溶剂也适用。从蒸发器蒸出的含水DEC通入冷凝器中冷凝，得到的冷凝液导入冷凝液收集罐中。将冷凝后的含水DEC泵入DEC缓冲罐中，与氢氧化锂溶液经管道混合器混合，然后经聚结分离器分离后，得到的油相为DEC，通入DEC储存罐。所述回收的DEC可以供脱水工序(β段)回用。经聚结分离器分离后得到的水相通入中和罐，向该罐中加入氢氧化锂溶液调节pH值。例如，调节后的pH值可为8-14，可选地为9-12。然后将中和罐中的物料经预热器通入汽提塔汽提，得到的油相为含水的DEC，返回DEC缓冲罐；得到的水相及残液通入污水处理装置进行后处理。通入管道混合器与含水DEC混合的氢氧化锂溶液可来自于β段的氢氧化锂溶液，也可通过直接加入去离子水和氢氧化锂得到，或者得自于二者的混合物。所述氢氧化锂溶液可以预先储存于氢氧化锂配料罐中，然后再通入管道混合器与含水DEC混合。另外，可直接从所述氢氧化锂配料罐将氢氧化锂溶液泵入中和罐中，来调节经聚结分离器分离后得到的水相的pH值。通入DEC储存罐中的液体料流中的DEC的纯度可达95重量％以上； 可选地，纯度可达98重量％以上，或99重量％以上。回收工段C的具体工艺流程如本申请的图5所示，其中具体以DEC作为酯类溶剂的实例。
回收工段D(析晶液回收)：在采用析晶工艺来生产双氟磺酰亚胺锂的流程中，还需要对使用的析晶液进行回收处理或再利用。所用的析晶液主要成分为二氯甲烷(DCM)。将经过脱溶工艺处理的双氟磺酰亚胺锂粗品(料流β3)通入析晶釜中，向其中加入二氯甲烷析晶液。利用二氯甲烷溶DEC而不溶LiFSI，使得LiFSI在DEC过饱和析出，晶核生长。将得到的混合物通入带过滤洗涤功能的二合一设备中，将附着在LiFSI晶体表面的其他杂质洗掉。从所述二合一设备中分离出来的含有析晶液的水洗油相中包含二氯甲烷、水、酯类溶剂以及杂质盐如LiF。将所述水洗油相(二氯甲烷、碳酸二乙酯、水、盐等)泵入脱水塔中脱水。塔顶冷凝液主要是二氯甲烷和水，进行分液处理，将分出的水收集至污水收集池，分出的二氯甲烷全部回流至塔中。将所述脱水塔的塔釜液通入单效蒸发系统，蒸发得到的气相通入精馏塔精馏，从精馏塔的塔顶冷凝液中得到二氯甲烷，收集至二氯甲烷调配罐，向所述罐中加入氢氧化锂，通过泵循环管路调节pH值并分相，得到的水相分离进行后处理，得到的油相通入二氯甲烷储存罐。所述回收的二氯甲烷可以供析晶工艺回用。
在一些实施方案中，从所述精馏塔的中部得到乙醇分离进行后处理；从所述精馏塔的中下部冷凝液中得到酯类溶剂，通入酯类溶剂储存罐中供脱水工艺回用；从所述精馏塔的塔釜得到的残液分离进行后处理。在一些实施方案中，从单效蒸发系统中得到的液相经过真空浓缩，得到的冷凝液包含二氯甲烷和酯类溶剂，送回脱水塔；真空浓缩的浓缩液分离进行后处理。回收工段D的具体工艺流程如本申请的图6所示。
回收工段E(二氯甲烷废气回收)：二氯甲烷为易挥发的液体，在析晶工艺以及后续的析晶液回收流程中，由于温度升高使得各阶段排出的废气中包含一定量的二氯甲烷。这些通过废气排出的二氯甲烷也需要集中处理和回收。将来自各工艺流程(例如所述析晶工艺中的二合一设备、脱水塔以及精馏塔)的带有二氯甲烷的废气冷却后通入三级吸附树脂中进行吸附，吸附饱和后使用蒸汽脱附，然后通过冷凝收集，收集得到的包含二氯甲烷和水的液体静置分层，上层水相中含有微量二氯甲烷，作为废水分离进行后处理；下层油相为含有微量水分的二氯甲烷，通入脱水装置中进行脱水至一定限度后进行回用。所述带有二氯甲烷的废气可通过常温水进行冷却。所述三级吸附树脂可以选择极性吸附树脂，例如带有酰胺基、氰基、酚羟基等极性功能基团的吸附树脂。
在一些实施方案中，所述脱水通过4A分子筛进行。所述4A分子筛的孔径为4A，其可吸附水分子而不吸附二氯甲烷，从而实现对含有微量水分的二氯甲烷油相的脱水。在一些实施方案中，所述含有微量水分的二氯甲烷油相中的水含量为1000-2000ppm，并且所述脱水进行至水含量为50-200ppm；可选地，所述脱水进行至水含量为50-100ppm。回收工段E的具体工艺流程如本申请的图7所示。
以上是对于在双氟磺酰亚胺锂(LiFSI)的生产中通过回收工段A、B、C、D和/或E对其中使用的原辅材料进行回收利用以及对产生的三废进行后处理的方法流程。可以理解的是，这些不同的工段可以彼此自由组合，以实现对不同目标物质的处理。另外，所得到的各目标物质如三乙胺或二氯甲烷，既可以回用到LiFSI的生产中，也可以制成可外售的产品。
所述在双氟磺酰亚胺锂(LiFSI)的合成和提纯过程中的对原辅材料进行回收的方法，使LiFSI的生产成本降低并减少了三废的产生，所用原料得到充分地回用，副产物提纯后也能产生额外的经济效益，适合工业化生产。通过回收循环使用原辅材料，降低了原辅材料的消耗，提高反应原料的利用率，减少化合物的排放处理费用，有效降低了生产成本，提高了经济效益。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
实施例1
1.三乙胺回收
用泵将40m 3三乙胺、35m 3乙腈分别泵入100m 3的合成釜中。将釜温降低至15℃，然后通入120kg氨气，最后同时通入氨气(2000kg)和硫酰氟(26000kg)，保持釜内压力不高于0.4MPa，并将釜内温度维持不高于15℃。持续反应4h后，将釜内压力降低至0.1MPa，停止搅拌。将所获得的反应混合物料流α1(其包含40重量％的(SO 2F-NH-SO 2F)·Et 3N、18重量％的三乙胺氟化氢盐和6重量％的三乙胺)经过孔径为5μm的四氟过滤袋进行过滤，过滤出固体副产品磺酰胺。将滤液泵入降膜蒸发器(热水桶温度为75℃)中，在-0.02MPa的真空度(真空泵前级用0℃水冷凝，后级用-15℃水冷凝)下将滤液中的溶剂蒸出，得到包含(SO 2F-NH-SO 2F)·Et 3N及三乙胺氟化氢盐的料流α2(其包含70重量％的(SO 2F-NH-SO 2F)·Et 3N、 28重量％的三乙胺氟化氢盐)以及含有乙腈的冷凝液。所述冷凝液被回收用于第一步的合成釜合成。将料流α2泵送至转盘萃取塔(搅拌频率15±1HZ；流量控制，去离子水：α2＝1.2±0.1(重量比))，在萃取塔中与去离子水充分混合后(通过流量计将去离子水与料流α2的质量比控制在1.2:1)，得到作为上层液的含三乙胺氟化氢盐的水相α水(其包含77重量％的水和22重量％的三乙胺氟化氢盐)，以及作为下层液的含(SO 2F-NH-SO 2F)·Et 3N的油相α3(其还包含15重量％的水)。将下层油相α3送至碱化步骤。经检测，油相α3还含有100ppm的F -。
将上层水相α水送至回收车间进行处理(回收工段A)。在回收工段A中，将α水泵入100m 3的碱化釜中，开启搅拌。向碱化釜中加入氢氧化钾溶液(5mol/L)，调节碱化釜中的液体的pH值保持在8-10范围内。常温常压下反应2h后，将碱化釜溶液泵入分层罐进行分相2h。水相为氟化钾溶液(含少量三乙胺)，分离并泵送至回收工段B；油相为水和三乙胺的有机相，分离并泵送至回收工段B。
含(SO 2F-NH-SO 2F)·Et 3N的油相α3直接在蒸发器B(热水桶蒸汽加热温度35℃)中碱化，滴加氢氧化锂水溶液(浓度5mol/L，其中料流α3与氢氧化锂的水溶液的体积比例为1.1：1)的同时不断搅拌。反应1小时后得到混合物料流β1-1(锂盐粗品)。使用35℃热水进行加热，并开启真空。保持釜内真空度-0.08MPa，蒸出时间约6h。真空泵前后级分别用25℃的水和0℃水进行五级冷凝，冷凝液静置分液。下层液冷凝水回用于碱化工序配制氢氧化锂的水溶液。因蒸发过程中，有部分产品分解，需不断加入氢氧化锂溶液(浓度为5mol/L)，保持pH在8左右。上层液为三乙胺水溶液，泵去回收车间进行回收(回收工段B)。在回收工段B中，将三乙胺水溶液通入三乙胺中转罐，经碟片式离心机分离为水相和油相。油相为包含水和三乙胺的有机相；将该有机相与回收工段A中得到的包含 水和三乙胺的有机相合并一起通入单效蒸发器蒸发，得到含水的三乙胺相。然后分别通过脱水塔脱水和通过精馏塔精馏移除剩余水分，得到高纯度三乙胺。回收得到的三乙胺的回收率经计算为93％，纯度经气相色谱定量分析为99.2重量％。色谱参数设定为：柱箱温度40-260℃，检测器类型FID/TCD，检测器温度300℃，空气压力0.4MPa、氢气流量30ml/min，空气流量400ml/min。
2.KF回收
回收工段A的分层罐中通过分相得到的下层水相主要包含KF溶液以及少量三乙胺。将其与回收工段B中在单效蒸发系统、脱水塔和精馏塔中得到的下层水相合并于盐水罐中。将所述盐水罐中的液体通入汽提塔汽提后，得到的轻相主要包含三乙胺和水，返回至回收工段A的油相二次分层罐中；汽提后得到的重组分主要包含KF溶液，将所述重组分通入双效蒸发器中蒸发，得到高浓度KF溶液。回收的高浓度KF溶液中KF的回收率为88％，浓度经离子色谱定量分析为56.8重量％。色谱参数设定为：色谱柱温度30-45℃，检测器DS5电导检测器，分析柱Shodex IC SI-90 4E，4.6╳250mm，保护柱Shodex IC SI-90G，4.6╳10mm，淋洗液流速1.0mL/min，再生液流速1.0mL/min。
3.DEC回收
经过蒸发器B后得到产品双氟磺酰亚胺锂的水溶液(简称为β1-2)在降膜蒸发器C(热水桶蒸汽加热温度50℃)中继续蒸发。同时计量泵入碳酸二乙酯(DEC)(控制流量计，使DEC与料流β1-2的体积比为0.6:1)，继续真空(-0.08MPa)加热蒸发，真空泵前后级分别用常温水和 0℃水进行五级冷凝，冷凝液为含DEC的水溶液。将所述含DEC的水溶液储存于收集罐中送到回收车间回收(回收工段C)。
经过降膜蒸发器C蒸发后得到包含双氟磺酰亚胺锂的料流β2(其包含70重量％的双氟磺酰亚胺锂和29重量％的碳酸二乙酯和1重量％的水)。在降膜蒸发器C蒸发的过程中，计量加入氢氧化锂水溶液(浓度5mol/L)，使料流β2的pH保持在8。
将经降膜蒸发器C蒸发后所得的料流进行过滤，过滤出副产品锂化合物，得到含1重量％水、30重量％碳酸二乙酯和69重量％的双氟磺酰亚胺锂的滤液β2-1。将滤液β2-1再泵入刮板蒸发器D(热水桶蒸汽加热温度75℃)中，真空(真空度-0.08MPa)加热蒸发脱水。冷凝液主要包含DEC及少量水，将所述冷凝液送至回收车间回收(回收工段C)。在蒸发6小时后得到含水量3000ppm的双氟磺酰亚胺锂β3(其包含85重量％的双氟磺酰亚胺锂和15重量％的碳酸二乙酯)。
在回收工段C中，将含水DEC通入DEC缓冲罐中，与50重量％浓度的氢氧化锂溶液在管道混合器中混合，使得其pH值调节为8-9。然后将混合后的液体料流经聚结分离器分离。分离后得到的油相主要为DEC，通入DEC储存罐。DEC储存罐中得到的液体物料中DEC纯度经气相色谱定量分析为98.6重量％。
3.析晶液回收
将β3泵入析晶釜中，以20L/h速度泵入二氯甲烷，搅拌混合后，泵入带过滤洗涤功能的二合一设备，将二氯甲烷(含DEC)送至回收车间回收(回收工段D)，剩余的双氟磺酰亚胺锂晶体通过重力落入二合一设备下层的干燥釜中，在干燥器中通入氮气吹扫晶体以进行干燥，干燥温度为60℃。干燥冷凝后，冷凝液包含99.5％二氯甲烷和0.5％水，将所述冷凝液 送至析晶工序循环利用。在晶体水分降至目标要求(50ppm)后，将得到的粉料产品送至溶解工段。
在溶解工段中，将70L碳酸甲乙酯和0.1kg氢氧化锂加入30kg双氟磺酰亚胺锂β3中。然后使用碟片式离心机进行离心(转速为1500rpm)，除去固体，然后将滤液g-1(HF≤50μg/g)送至脱水釜，脱水釜中加入20kg分子筛，搅拌转速800，处理时间2h。然后使用过滤器过滤掉分子筛，将所得滤液g-2(水含量≤20μg/g)送至产品调配釜。最后进行除磁(通过除磁过滤器，8000高斯)并过滤(分别通过1微米过滤器、0.5微米过滤器、0.1微米过滤器)，得到浓度为28重量％的双氟磺酰亚胺锂的碳酸甲乙酯溶液，最后进行罐装。
在回收工段D中，析晶液水洗油相(二氯甲烷、DEC、水、盐等)泵入脱水塔中脱水。塔顶冷凝液主要是二氯甲烷和水，进行分液处理，将分出的水收集至污水收集池，分出的二氯甲烷全部回流至塔中。将所述脱水塔的塔釜液通入单效蒸发器，蒸发得到的气相通入精馏塔精馏，从精馏塔的塔顶冷凝液中得到二氯甲烷，收集至二氯甲烷调配罐。向所述罐中加入50重量％浓度的氢氧化锂溶液，通过泵循环管路调节pH值至9-10并分相。得到的水相分离进行后处理，得到的油相通入二氯甲烷储存罐。塔中采出乙醇装桶去处理。塔中下部采出DEC，用泵送至DEC储罐，供脱水工序(β段)回用。釜残装桶去处理；单效蒸发的液相再经过真空浓缩，进一步回收二氯甲烷、碳酸二乙酯DEC送回脱水塔，浓缩液装桶去处理。通入二氯甲烷储存罐的油相中二氯甲烷的纯度经气相色谱定量分析为99.2重量％。
4.回收二氯甲烷废气
使用收集管从析晶工序中在二合一设备以及在回收工段D中的脱水塔和精馏塔顶部收集挥发的气体，气体中主要含有二氯甲烷废气以及蒸发的水。将收集到的废气通入二氯甲烷吸收回收装置，先用常温水进行冷却。冷却后通入三级吸附树脂中进行吸附，吸附饱和后使用蒸汽脱附。冷凝后收集，对收集得到的二氯甲烷、水进行静置分层。上层液水中含有微量二氯甲烷，作为废水进行后处理；下层液二氯甲烷中含有约1800ppm的水分，泵入4A分子筛脱水装置中进行脱水至150ppm以下后进行回用。
实施例2
实施例2以与实施例1相同的方式进行，区别在于在生产双氟磺酰亚胺锂的α段中，将α2料流用泵输送至静态混合器(长度与管径之比L/D＝10；流量控制，去离子水：α2＝1.2±0.1(重量比))而不是萃取塔，使其在静态混合器中与去离子水充分混合后，送至分层槽，静置分层2h。
最终在回收工段B的汽提塔中得到的重组分通过双效蒸发器蒸发后，得到的KF溶液中KF的回收率为79％，浓度经离子色谱定量分析为42.8重量％。
虽然已经参考实施例对本申请进行了描述，但在不脱离本申请的范围的情况下，可以对其进行各种改进并且可以用等效物替换其中的部件。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (19)

  1. 一种在双氟磺酰亚胺锂的生产中回收原辅材料的方法，所述双氟磺酰亚胺锂的生产包括使硫酰氟、三乙胺与氨气反应的反应1以及随后对反应产物进行碱化的反应2，
    反应1：SO 2F 2+NH 3+Et 3N→(SO 2F-NH-SO 2F)·Et 3N+Et 3N·(HF) n(n＝1-12)，
    反应2：(SO 2F-NH-SO 2F)·Et 3N+LiOH→(SO 2F-N-SO 2F) -Li ++Et 3N+H 2O，
    所述方法包括：
    回收工段A:将反应1产生的产物混合物分离为包含(SO 2F-NH-SO 2F)·Et 3N的油相和包含三乙胺氟化氢盐以及杂质离子的水相；将包含(SO 2F-NH-SO 2F)·Et 3N的油相根据反应2进行碱化工艺，而将包含三乙胺氟化氢盐以及杂质离子的水相通入碱化釜中与碱金属氢氧化物在搅拌下混合并反应，然后将碱化釜中反应后得到的溶液通入分层罐中分相；上层的油相为包含水和三乙胺的有机相，将其分离出并储存于油相二次分层罐中；以及
    回收工段B：将根据反应2进行碱化工艺得到的产物混合物通过蒸发器移除三乙胺和部分的水，并将蒸出的三乙胺和水通入冷凝器中冷凝并静置分液；将分液后得到的上层三乙胺溶液转入三乙胺中转罐，经离心机分离为水相和油相，所述油相为包含水和三乙胺的有机相；将所述有机相与所述回收工段A中得到的包含水和三乙胺的有机相一起通入单效蒸发系统，得到含水的三乙胺相；然后分别通过脱水塔脱水和通过精馏塔精馏移除剩余水分，得到高纯度三乙胺。
  2. 根据权利要求1所述的方法，其中所述方法得到的高纯度三乙胺的纯度为95重量％以上；可选的，所述三乙胺的纯度为98重量％以上、99重量％以上或者99.5重量％以上。
  3. 根据权利要求1或2所述的方法，其中所述杂质离子包含F -、SO 4 2-、FSO 3 -以及Cl -。
  4. 根据权利要求1至3中任一项所述的方法，其中在所述回收工段B中将碱化工艺得到的产物混合物通过蒸发器蒸出包含三乙胺和水的混合物，将所述混合物在冷凝器中冷凝后，加热至30℃-55℃的温度，可选地40℃-45℃的温度，并静置分层。
  5. 根据权利要求1至4中任一项所述的方法，其中所述回收工段A中分离反应1产生的产物混合物为通过静态混合器分层或通过萃取塔萃取。
  6. 根据权利要求5所述的方法，其中所述静态混合器分层而得到的油相中的杂质离子的含量为通过所述萃取塔萃取而得到的油相中的杂质离子含量的5-30倍，可选地为10-20倍；可选地，所述杂质离子为F -。
  7. 根据权利要求1至6中任一项中所述的方法，其中所述离心机为碟片式离心机。
  8. 根据权利要求1至7中任一项所述的方法，其中所述回收工段B中通过离心机分离出的水相通入反应2的碱化工艺中配碱，通入萃取工艺中作为水洗水，或者通入污水处理装置进行处理。
  9. 根据权利要求1至8中任一项所述的方法，其中所述回收工段A的分层罐中通过分相得到的下层水相主要包含碱金属氟化物溶液以及少量三乙胺；将其与所述回收工段B中在单效蒸发系统、脱水塔和精馏塔中得到的下层水相合并于盐水罐中；将所述盐水罐中的液体通入汽提塔汽提后，得到的轻相主要包含三乙胺和水，返回至回收工段A的油相二次分层罐中；汽提后得到的重组分主要包含碱金属氟化物溶液，将所述重组分通入双效蒸发器中蒸发，得到高浓度碱金属氟化物溶液。
  10. 根据权利要求1至9中任一项所述的方法，其中所述碱金属为Li、Na或K。
  11. 根据权利要求1至10中任一项所述的方法，其中所述双氟磺酰亚胺锂的生产还包括使用酯类溶剂进行的脱水工艺，通过蒸发和冷凝得到的含水酯类溶剂通过回收工段C进行回收：
    回收工段C：将含水酯类溶剂通入酯类溶剂缓冲罐中，与氢氧化锂溶液在管道混合器中混合，然后经聚结分离器分离后，得到的油相为酯类溶剂，并将所述油相通入酯类溶剂储存罐。
  12. 根据权利要求11所述的方法，其中经聚结分离器分离后得到的水相加入氢氧化锂溶液调节pH值后，经预热器进入汽提塔汽提，得到的油相为含水的酯类溶剂，返回酯类溶剂缓冲罐；得到的水相及残液通入污水处理装置进行后处理。
  13. 根据权利要求11或12所述的方法，其中所述酯类溶剂包括碳酸甲乙酯EMC、碳酸二乙酯DEC以及碳酸二甲酯DMC。
  14. 根据权利要求1至13中任一项所述的方法，其中所述双氟磺酰亚胺锂的生产还包括使用析晶液溶解酯类溶剂并析出产物LiFSI晶体的析晶工艺，通过蒸发和冷凝得到的析晶液水洗油相包含二氯甲烷、酯类溶剂、水和盐；所述析晶液通过回收工段D进行回收：
    回收工段D：将所述析晶液水洗油相通入脱水塔，塔顶冷凝液包含二氯甲烷和水，分层后上层的水相通入污水收集池进行后处理，下层的二氯甲烷全部回流；
    将所述脱水塔的塔釜液通入单效蒸发系统，蒸发得到的气相通入精馏塔精馏，从精馏塔的塔顶冷凝液中得到二氯甲烷，收集至二氯甲烷调配罐，向所述罐中加入氢氧化锂，通过泵循环管路调节pH值并分相，得到的水相分离进行后处理，得到的油相通入二氯甲烷储存罐。
  15. 根据权利要求14所述的方法，其中从所述精馏塔的中部得到乙醇分离进行后处理；从所述精馏塔的中下部冷凝液中得到酯类溶剂，通入酯 类溶剂储存罐中供脱水工艺回用；从所述精馏塔的塔釜得到的残液分离进行后处理。
  16. 根据权利要求14所述的方法，其中从单效蒸发系统中得到的液相经过真空浓缩，得到的冷凝液包含二氯甲烷和酯类溶剂，送回脱水塔；真空浓缩的浓缩液分离进行后处理。
  17. 根据权利要求1至16中任一项所述的方法，其中所述方法还包含回收工段E回收各阶段产生的包含二氯甲烷的废气：
    回收工段E：将各阶段产生的包含二氯甲烷的废气冷却后通入三级吸附树脂中进行吸附，吸附饱和后使用蒸汽脱附，然后通过冷凝收集，收集得到的包含二氯甲烷和水的液体静置分层，上层水相中含有微量二氯甲烷，作为废水分离进行后处理；下层油相为含有微量水分的二氯甲烷，通入脱水装置中进行脱水后进行回用。
  18. 根据权利要求17所述的方法，其中所述含有微量水分的二氯甲烷中的水含量为1000-2000ppm，并且所述脱水进行至水含量为50-200ppm。
  19. 根据权利要求17所述的方法，其中所述脱水为通过4A分子筛进行。
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