Fluorine-containing imidazole ionic liquid, preparation method thereof and application of fluorine-containing imidazole ionic liquid in boron isotope separation

Abstract

This invention belongs to the field of boron isotope separation technology, and relates to a fluorinated imidazole ionic liquid, its preparation method, and its application in boron isotope separation. The ionic liquid is based on fluorinated imidazole cations and specific fluorinated anions, with the general chemical formula [R1R2ImR3]. + [RfX] ‑ The structure is designable, non-volatile, and low in toxicity; its properties can be enhanced through targeted molecular design. 10 BF3 / 11 The selective complexation ability of BF3, with a separation coefficient α of 1.035–1.050, is 15%–30% higher than that of traditional processes. Its preparation method is mild and easily scalable, with product purity ≥99.9%. When applied to the separation of BF3 systems, it can stably obtain high abundance. 11 B≥99.9% and 10 Products with a boron content of ≥99% have an ionic liquid regeneration rate of ≥99% and are recyclable with no byproducts. This enables efficient and green separation of boron isotopes, meeting the needs of high-end fields such as the nuclear industry and semiconductors, and has extremely high industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of boron isotope separation technology, and particularly relates to a fluorinated imidazole ionic liquid, its preparation method, and its application in boron isotope separation, especially suitable for boron trifluoride (BF3) systems. 10 B and 11 Efficient separation of B. Background Technology

[0002] Boron exists in two stable isotopes, namely 10 B (natural abundance approximately 19.8%) and 11 B (natural abundance approximately 80.2%) and the other two have drastically different applications in the nuclear industry, semiconductors, and medical fields: 10 Boron has an extremely strong ability to capture thermal neutrons. It is not only a core component of nuclear reactor control rods and neutron shielding materials, but also a key raw material for tumor treatment in boron neutron capture therapy (BNCT). It also plays an important role in fields such as water quality testing and geological science. 11 B can be used as an ultra-high purity dopant source in semiconductor manufacturing processes, an additive for high-temperature resistant steel, and a fuel for thermonuclear reactions, and is in urgent demand in the field of advanced electronic devices.

[0003] Currently, the mainstream industrial method for boron isotope separation is the chemical exchange distillation of BF3-anisole complex. This method has advantages such as high single-stage separation factor and operation at ambient temperature and pressure, but it also has technical drawbacks: First, anisole is volatile and toxic, with a water content of approximately 0.03%~0.05%. During high-temperature pyrolysis, BF3 reacts with trace amounts of water to generate hydrofluoric acid and boric acid, which catalyze the decomposition of anisole to produce byproducts, affecting separation efficiency and product purity, and can also clog equipment, affecting production continuity. Second, after high-temperature pyrolysis, approximately 3% of the enriched boron isotopes remain in the complex, causing backmixing with the new feed. Furthermore, the reversibility of the complex is unstable, and temperature fluctuations can easily lead to premature dissociation, exacerbating backmixing and increasing product abundance fluctuations. Third, traditional complexing agents are susceptible to... 10 BF3 and 11 BF3 has limited selective complexing ability and a low separation coefficient, resulting in a long separation process, high energy consumption, difficulty in recycling anisole, difficulty in removing impurities, and an increase in continuous cycle loss rate. This necessitates the addition of impurity removal equipment, increasing investment and operating costs.

[0004] Ionic liquids, as a novel type of green solvent, possess advantages such as extremely low vapor pressure, excellent thermal and chemical stability, and strong structural designability, and have already seen initial applications in the field of isotope separation. CN120247773A discloses ionic liquids prepared from haloethers, nitrogen-containing compounds, and fluorine-containing inorganic salts, and uses them as complexing agents for boron isotope separation. However, this type of ionic liquid still introduces ether structures, limiting its environmental friendliness, and suffers from problems such as low complexation selectivity and insufficient structural tunability, making it difficult to meet the requirements for efficient separation.

[0005] Addressing the core pain points of the existing technologies, this invention abandons ether components and designs fluorinated imidazole ionic liquids in a targeted manner. By forming a clear N→B coordination bond through the N atom of the imidazole ring, combined with the regulatory effect of fluorinated groups, it precisely solves the problems of low complexation selectivity, poor stability, and insufficient environmental friendliness, while achieving a significant improvement in separation performance. This fills the gap in the dedicated design and application of fluorinated imidazole ionic liquids in boron isotope separation. Summary of the Invention

[0006] This invention addresses the technical problems of existing boron isotope separation complexing agents (such as anisole) having high toxicity and numerous side reactions, as well as the insufficient complexing performance and poor stability of conventional ionic liquids. It provides a specifically designed fluorinated imidazole-based ionic liquid, its preparation method, and its application in boron isotope separation, to achieve… 10 B and 11 B's efficient, green, and continuous separation.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A fluorinated imidazole ionic liquid, with fluorinated cations and fluorinated anions as its core components, has the general chemical formula: [R1R2ImR3]. + [RfX] - Where [R1R2ImR3] + It is an imidazole cation (Im is an imidazole ring), and R1, R2, and R3 are C1-C 12 Alkyl or C2-C 12 The fluoroalkyl group, and at least one of them, is a fluoroalkyl group (straight-chain or branched, with a fluorine substitution degree of 10% to 100%, preferably perfluoroalkyl or monofluorosubstituted alkyl), and Im is preferably an imidazole ring structure derived from 1-methylimidazolium or 1-ethylimidazolium; [RfX] - The fluorinated imidium ion in this invention is selected from perfluorobutane sulfonate (C4F9SO3). - ), perfluoropentanoate (C4F9CO2) - ), tetrafluoroborate (BF4) - ), hexafluorophosphate (PF6) - ), bis(trifluoromethanesulfonyl)imide salt (NTf2) - A mixture of one or more of the following.

[0008] Furthermore, Im is preferably one or a mixture of several of 1-methyl-3-trifluoroethylimidazolium trifluoromethanesulfonate ([MeCF3CH2Im]OTf), 1-ethyl-3-difluoromethylimidazolium tetrafluoroborate ([EtCF2HIm]BF4), and 1-propyl-3-fluoroethylimidazolium bis(trifluoromethanesulfonyl)imide ([PrCF2HCH2Im]NTf2).

[0009] All fluorinated imidazole ionic liquids of this invention are electron-rich compounds, capable of acting as electron donors and stably complexing with BF3. The nitrogen atom of the core imidazole ring in the cation contains a lone pair of electrons, which can form an N→B coordination bond with electron-deficient BF3 to generate a complex. Although the fluorinated alkyl group on the cation is an electron-withdrawing group, it does not affect its electron-rich nature and can synergistically regulate polarity, spatial structure, and complexation selectivity with the fluorinated anion, thereby enhancing its complexation ability with BF3. Furthermore, these ionic liquids exhibit excellent thermal and chemical stability, are non-volatile, and have low toxicity, enabling the realization of… 10 BF3 / 11 BF3's efficient and green separation.

[0010] This invention provides a method for preparing fluorinated imidazole ionic liquids, comprising the following steps: S1. Intermediate Synthesis: Using 1-methylimidazole or 1-ethylimidazole as raw materials, it is mixed with fluorinated haloalkanes (perfluorobutyl bromide, trifluoroethyl bromide, etc.) at a molar ratio of 1:(1.1~1.3) in acetonitrile as solvent. The reaction is carried out at a constant temperature, and a fluorinated imidazole cationic intermediate is generated through a nucleophilic substitution reaction. Acetonitrile is removed by vacuum distillation to obtain an intermediate with a purity ≥99%.

[0011] S2. Ion exchange reaction: The above intermediate is mixed with fluorine-containing inorganic salts (NaBF4, KPF6, etc.) at a molar ratio of 1:(1~1.2) in acetone as solvent. The mixture is stirred at a constant temperature, filtered to remove impurities, distilled under reduced pressure to remove acetone, and then dried under vacuum to obtain the high-purity target product.

[0012] Furthermore, the reaction temperature for S1 is 60℃~70℃ and the reaction time is 15h~20h; the reaction temperature for S2 is 25℃~35℃ and the reaction time is 25h~30h. This method uses readily available raw materials, operates under mild conditions, is scalable, produces products with a purity ≥99.9%, and allows for the recovery of organic solvents, demonstrating significant innovation.

[0013] Furthermore, the S2 vacuum drying temperature is 80℃~100℃, the pressure is 0.08MPa~0.1MPa, and the time is 8h~12h.

[0014] This invention provides a fluorinated imidazole ionic liquid as a complexing agent for use in the BF3 system. 10 B and 11 The separation of B, specifically applied in the following steps: S1. Raw material pretreatment: Industrial grade BF3 is subjected to adsorption to remove impurities, resulting in refined BF3 with a purity ≥99.5% and impurities ≤50ppm; S2. Complexation reaction: Add the fluorinated imidazole ionic liquid into the complexation tower, control the temperature and pressure of the complexation tower, and contact the BF3 raw gas obtained in S1 with the fluorinated imidazole ionic liquid in a countercurrent manner at a volume ratio of (1~5):1 for 10min~30min to generate BF3-fluorinated imidazole ionic liquid complex. 10 BF3 preferentially accumulates in the liquid phase. 11 BF3 remains in the gas phase; S3. Distillation Separation: The complex obtained in S2 is fed into a distillation exchange column. The temperature and pressure of the distillation column are controlled. Uncomplexed... 11 BF3 is discharged from the top of the column and collected by condensation to obtain high abundance. 11 Product B (abundance ≥ 99.9%) S4. Cracking and Regeneration: The bottom residue from the distillation column in S3... 10 The BF3-fluorinated imidazole ionic liquid complex was fed into a pyrolysis tower, and the temperature and pressure of the pyrolysis tower were controlled. The reaction was carried out for 20-40 minutes to obtain... 10 BF3 gas and fluorinated imidazole ionic liquids; S5. Product Collection and Recycling: The products generated from the pyrolysis of S4... 10 BF3 gas was collected by condensation to obtain high abundance. 10 Product B (abundance ≥99%): The fluorinated imidazole ionic liquid regenerated after pyrolysis is cooled and returned to the complexation tower for recycling. The regeneration rate is ≥99%, and it can be continuously recycled more than 100 times without significant performance degradation. Furthermore, in S2, the temperature of the complexation tower is 30℃~40℃ and the pressure is 0.15MPa~0.25MPa; in S3, the temperature of the distillation exchange tower is 50℃~70℃ and the pressure is 0.08MPa~0.15MPa; in S4, the temperature of the cracking tower is 140℃~160℃ and the pressure is 0.03MPa~0.08MPa.

[0015] Furthermore, to improve separation efficiency, a multi-stage complexation-distillation-cracking coupled system can be used to remove the waste gas discharged from the top of the previous stage distillation exchange column. 11 BF3 gas is passed into the next stage complexing column, where it is again complexed and distilled with fresh fluorinated imidazole ionic liquid. 11 B abundance remained stable at 99.9%; the B produced by the previous stage pyrolysis tower 10 BF3 gas is passed into the next stage pyrolysis tower for further pyrolysis, which can further remove residual gases. 11 B, making 10 B abundance remained stable at 99%.

[0016] To measure the degree of separation, the separation factor is generally used for comparison. The separation factor is defined as follows: The application method of this invention is simple to operate, highly continuous, and effective against fluorinated imidazole ionic liquids. 10 BF3 / 11 The separation coefficient α of BF3 can reach 1.035~1.050, which is 15%~30% higher than that of traditional anisole complexing agents (separation coefficient α≈1.025). The energy consumption of the separation process is reduced by more than 30%, with no by-products generated and waste approaching zero, realizing green and efficient separation of boron isotopes. At the same time, the fluorinated imidazole ionic liquid can be recycled, which significantly reduces the separation cost and is suitable for industrial-scale application.

[0017] The advantages of this invention are: 1. The fluorinated imidazole ionic liquid of this invention, through the introduction of fluorinated groups, can regulate its polarity, spatial structure, and complexation selectivity, thereby enhancing its complexation ability with BF3; simultaneously, it can improve thermal and chemical stability, enabling it to withstand high pyrolysis temperatures without the formation of byproducts; it reduces surface energy and viscosity to improve fluidity and compatibility with BF3, and accelerates gas-liquid mass transfer efficiency; and it achieves [further benefits] through steric hindrance effect. 10 BF3 and 10 The differentiated complexation of BF3 improves separation selectivity and separation coefficient; in addition, it can suppress hydrolysis side reactions, reduce the generation of HF and boric acid to protect equipment, and ensure the structural stability and near-zero loss of the ionic liquid during long-term cyclic use. This ionic liquid combines the advantages of high selectivity, high stability, and environmental friendliness. It is non-volatile and low in toxicity, avoiding the toxicity and volatility problems of traditional complexing agents while solving the shortcomings of insufficient complexing performance of conventional ionic liquids. It has a high separation coefficient and the product abundance can meet the needs of high-end fields. 2. The preparation method of the fluorinated imidazole ionic liquid of the present invention is mild, the raw materials are readily available, and it can be produced on a large scale; the product has high purity, the preparation process is green and environmentally friendly, the organic solvent can be recycled and reused, and the production cost is reduced. 3. The application of this fluorinated imidazole ionic liquid for boron isotope separation is simple to operate, highly continuous, low in energy consumption, and produces no byproducts. The ionic liquid can be recycled for a long time, effectively solving the pain points of many side reactions and high energy consumption in traditional separation processes, and has extremely high industrial application value. 4. Fluoroimidazole ionic liquids can not only be used for boron isotope separation in the BF3 system, but can also be extended to the isotope separation of other boron compounds (such as boric acid and borate), providing a new solution for the upgrading of boron isotope separation technology. Attached Figure Description

[0018] Figure 1 The process flow diagram of separating boron isotopes using ionic liquid as a complexing agent in this invention. Detailed Implementation

[0019] Example 1: Preparation of 1-methyl-3-trifluoroethylimidazolium trifluoromethanesulfonate ([MeCF3CH2Im]OTf) S1. Intermediate synthesis: 1 mol of 1-methylimidazole and 1.1 mol of trifluoroethyl bromide (CF3CH2Br) were added to about 320 mL of acetonitrile. After mixing evenly, the mixture was reacted at 60 °C for 15 h. After the reaction was completed, the acetonitrile was removed by vacuum distillation to obtain the 1-methyl-3-trifluoroethylimidazole bromide intermediate. S2. Ion exchange reaction: 1 mol of the above intermediate was added to 1.05 mol of sodium trifluoromethanesulfonate (CF3SO3Na), and mixed thoroughly in approximately 400 mL of acetone. The mixture was then reacted at 30 °C for 28 h. After the reaction, the sodium bromide precipitate was removed by filtration, the acetone was removed by vacuum distillation, and the product was then vacuum dried at 85 °C and 0.09 MPa for 10 h to obtain the fluorinated imidazole ionic liquid 1-methyl-3-trifluoroethylimidazolium trifluoromethanesulfonate. The purity of the product was determined by high-performance liquid chromatography (HPLC). A C18 column was used, the mobile phase was acetonitrile-water (8:2, v / v), the detection wavelength was 254 nm, and the flow rate was 1.0 mL / min. The purity was found to be 99.93%.

[0020] Example 2: Preparation of 1-ethyl-3-difluoromethylimidazolium tetrafluoroborate ([EtCF2HIm]BF4) S1. Intermediate synthesis: Take 1 mol of 1-ethylimidazole and 1.1 mol of difluoromethyl bromide (CF2HBr), add about 300 mL of acetonitrile, mix well, and react at 65 °C for 20 h; after the reaction is completed, remove acetonitrile by vacuum distillation to obtain 1-ethyl-3-difluoromethylimidazole bromide intermediate; S2. Ion exchange reaction: 1 mol of the above intermediate was added to 1.03 mol of NaBF4 and mixed thoroughly in approximately 380 mL of acetone. The mixture was then reacted at 28 °C for 30 h. After the reaction, the sodium bromide precipitate was removed by filtration, the acetone was removed by vacuum distillation, and the product was then vacuum dried at 85 °C and 0.085 MPa for 11 h to obtain the fluorinated imidazole ionic liquid 1-ethyl-3-difluoromethylimidazolium tetrafluoroborate. The purity of the product was determined by high performance liquid chromatography (HPLC). A C18 column was used, the mobile phase was acetonitrile-water (8:2 v / v), the detection wavelength was 254 nm, and the flow rate was 1.0 mL / min. The purity was found to be 99.94%.

[0021] Example 3: Application of fluoroimidazole-containing ionic liquids in boron isotope separation (multi-stage coupling) Using 1-ethyl-3-difluoromethylimidazolium tetrafluoroborate prepared in Example 2 as a complexing agent, boron isotope separation was performed using a three-stage complexation-distillation-cracking coupling system, with the specific steps as follows: A. The BF3 feed gas is passed through a molecular sieve bed and an activated carbon bed for adsorption to remove impurities, avoid impurities from interfering with the complexation reaction, affecting the separation efficiency and product purity, and prevent impurities from damaging the equipment, thus obtaining refined BF3 feed gas (purity 99.6%, total impurity content 32ppm). B. First-stage complexation-distillation: Fluoroimidazole-containing ionic liquid is added to the first-stage complexation column, with the temperature controlled at 32℃ and the pressure at 0.18MPa. The volume ratio of BF3 feed gas to ionic liquid is 2:1, and the contact time is 15min. The complexed liquid phase is then fed into the first-stage distillation exchange column, with the temperature controlled at 55℃ and the pressure at 0.1MPa. The product is discharged from the top of the column. 11 BF3 gas (abundance 99.5%), the bottom material of the tower is sent to the secondary complexing tower; C. Two-stage complexation-distillation: The two-stage complexation column operates at a temperature of 38℃ and a pressure of 0.22MPa, while the top of the first-stage distillation column... 11 BF3 gas is introduced into a two-stage complexing column to complex with fresh ionic liquid; the complexed liquid phase is then fed into a two-stage distillation exchange column, where the temperature is controlled at 65℃ and the pressure at 0.13MPa, and the product is discharged from the top of the column. 11 BF3 gas (abundance 99.9%), the bottom material of the tower is fed into a three-stage complexing tower; D. Three-stage complexation-distillation-cracking: The three-stage complexation column operates at a temperature of 36℃ and a pressure of 0.2MPa, while the top of the two-stage distillation column... 11 BF3 gas is introduced into a three-stage complexing column to complex with fresh ionic liquid; the complexed liquid phase is then fed into a three-stage distillation exchange column, with the temperature controlled at 62℃ and the pressure at 0.11MPa, and discharged from the top of the column. 11 BF3 product; the bottom material of the three-stage distillation column is fed into the cracking column, and the temperature is controlled at 155℃ and the pressure at 0.06MPa for 35 minutes to obtain... 10 BF3 products; detected using inductively coupled plasma mass spectrometry (ICP-MS). 10 B. 11 Abundance of B, specific detection conditions and procedures: Take a small amount 10 BF3 / 11 BF3 product was diluted with methanol to a concentration of 1-5 μg / mL, and then diluted to a 10 mL volumetric flask. The solution was shaken well and set aside. The radio frequency power was set to 1500 W, the nebulizing gas flow rate to 0.8 L / min, the auxiliary gas flow rate to 0.2 L / min, and the cooling gas flow rate to 12 L / min. The detection wavelengths were as follows: 10 B (10.003amu) 11B (11.009 amu) was calibrated using boron standard solutions (concentrations of 1 μg / mL and 5 μg / mL). After calibration, the sample solution was injected for detection. Each sample was detected in parallel three times. The isotopic abundance was calculated by comparing the detection peak area with the standard curve. The detection results were 99% and 99.9%, respectively.

[0022] E. Recycling: The fluorinated imidazole ionic liquids regenerated from each pyrolysis tower were cooled and returned to the corresponding complexing towers for recycling. The regeneration rate was ≥99.2%. After 120 consecutive cycles, the thermal stability of the ionic liquids after recycling was tested by differential scanning calorimetry (DSC), and it was found that there was no significant degradation in the performance of the ionic liquids.

[0023] Testing revealed that the fluoroimidazole-based ionic liquid in this embodiment... 10 BF3 / 11 The separation coefficient α of BF3 is 1.048, the separation efficiency is 30% higher than that of traditional processes, energy consumption is reduced by 38%, and product abundance ( 11 B 99.9% 10 B (99%) meets the needs of high-end applications in semiconductors and nuclear-grade applications.

[0024] Comparative Example 1 Using traditional anisole as a complexing agent, a boron isotope separation comparison experiment was conducted according to the process parameters in Example 3.

[0025] The comparison results show that even through process optimization, it is possible to... 11 The purity of B has been increased to 99.9%. 10 While the purity of component B has been increased to 99%, the core problems of low separation coefficient, numerous side reactions, insufficient complexing agent circulation rate, high energy consumption, and toxic emissions remain unresolved due to the inherent limitations of the anisole complexing agent itself. In contrast, the fluorinated imidazole ionic liquid of this invention optimizes complexing performance through synergistic optimization of fluorinated groups, requiring no auxiliary reagents or additional process units, and can be directly adapted to existing production lines (only the complexing agent needs to be replaced). Combined with the three-stage coupling system of Example 3, high-purity separation can be stably achieved. 11 B abundance 99.9%, 10 With a boron abundance of 99%, and a higher separation coefficient, no byproducts, recyclability, and lower energy consumption, it is significantly superior to the traditional anisole process and can effectively solve the core pain points of existing boron isotope separation technologies.

Claims

1. A fluorinated imidazole ionic liquid, characterized in that: Its general chemical formula is: [R1R2ImR3] + [RfX] - Where [R1R2ImR3] + It is an imidazole cation, and R1, R2, and R3 are C1-C. 12 Alkyl or C2-C 12 The fluorinated alkyl group, and at least one of them is a fluorinated alkyl group; [RfX] - It is a fluorine-containing anion and is selected from one or more of perfluorobutane sulfonate, perfluorovalerate, tetrafluoroborate, hexafluorophosphate, and bis(trifluoromethanesulfonyl)imide salt.

2. The fluorinated imidazole ionic liquid as described in claim 1, characterized in that: The fluorinated alkyl group is straight-chain or branched, and the degree of fluorine substitution is 10~100%.

3. The fluorinated imidazole ionic liquid as described in claim 1, characterized in that: The Im is an imidazole ring structure derived from 1-methylimidazole or 1-ethylimidazole.

4. The fluorinated imidazole ionic liquid as described in claim 3, characterized in that: Im is one or more of 1-methyl-3-trifluoroethylimidazolium trifluoromethanesulfonate, 1-ethyl-3-difluoromethylimidazolium tetrafluoroborate, and 1-propyl-3-fluoroethylimidazolium bis(trifluoromethanesulfonyl)imide salt.

5. The method for preparing an ionic liquid according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Intermediate synthesis: Using 1-methylimidazole or 1-ethylimidazole as raw materials, it is mixed with fluorinated haloalkanes in a molar ratio of 1:(1.1~1.3) and subjected to a nucleophilic substitution reaction to generate a fluorinated imidazole cationic intermediate. The solvent is removed by vacuum distillation to obtain an intermediate with a purity ≥99%. S2. Ion exchange reaction: The above intermediate is mixed with a fluorine-containing inorganic salt at a molar ratio of 1:(1~1.2) and stirred to react. The mixture is then filtered to remove impurities, the solvent is removed by vacuum distillation, and the product is dried under vacuum to obtain the target product.

6. The method for preparing ionic liquid as described in claim 5, characterized in that: The reaction in step S1 is carried out at a temperature of 60℃~70℃ for 15h~20h, and the solvent is acetonitrile.

7. The method for preparing ionic liquid as described in claim 5, characterized in that: In step S2, the reaction temperature is 25℃~35℃, the time is 25h~30h, the solvent is acetone, and the vacuum drying temperature is 80℃~100℃, the pressure is 0.08MPa~0.1MPa, and the time is 8h~12h.

8. The method for preparing ionic liquid as described in claim 5, characterized in that: The fluorinated haloalkane is perfluorobutyl bromide or trifluoroethyl bromide; the fluorinated inorganic salt is NaBF4 or KPF6.

9. The application of the ionic liquid according to any one of claims 1-4, characterized in that: It is used as a complexing agent in the BF3 system. 10 B and 11 The specific application method for separating B includes the following steps: (1) Raw material pretreatment: Industrial grade BF3 is purified by adsorption to remove impurities, resulting in refined BF3 with a purity ≥99.5% and impurities ≤50ppm; (2) Complexation reaction: Add the fluorinated imidazole ionic liquid to the complexation tower, and contact the BF3 obtained in step (1) with the fluorinated imidazole ionic liquid in a countercurrent manner at a volume ratio of (1~5):1 for 10min~30min to generate BF3-fluorinated imidazole ionic liquid complex. 10 BF3 is enriched in the liquid phase. 10 BF3 remains in the gas phase; (3) Distillation separation: The complex obtained in step (2) is sent to a distillation exchange column, and the uncomplexed... 10 BF3 is discharged from the top of the column and collected by condensation to obtain 11B product with an abundance of ≥99.9%; (4) Cracking and regeneration: The bottom of the distillation column in step (3) is cracked and regenerated. 10 The BF3-fluorinated imidazole ionic liquid complex was fed into a pyrolysis tower and reacted for 20-40 minutes to obtain... 10 BF3 gas and fluorinated imidazole ionic liquids; (5) Product collection and recycling: The products generated from the pyrolysis in step (4) 10 BF3 gas is collected by condensation to obtain 10B product with an abundance of ≥99%; the fluorinated imidazole ionic liquid regenerated after pyrolysis is cooled and returned to the complexation tower for recycling.

10. The application of the ionic liquid as described in claim 9, characterized in that: In step (2), the temperature of the complexation tower is 30℃~40℃ and the pressure is 0.15MPa~0.25MPa; in step (3), the temperature of the distillation exchange tower is 50℃~70℃ and the pressure is 0.08MPa~0.15MPa; in step (4), the temperature of the cracking tower is 140℃~160℃ and the pressure is 0.03MPa~0.08MPa.

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