JP5824013B2 - Method for producing phosphorus pentafluoride and hexafluorophosphate - Google Patents

Description

  The present invention relates to a method for producing phosphorus pentafluoride and hexafluorophosphate. More specifically, a method for producing hexafluorophosphate useful as an electrolyte for a storage element, a catalyst for an organic synthesis reaction, and the like, and a method for producing phosphorus pentafluoride used as a starting material for hexafluorophosphate production About.

Lithium ion secondary batteries are positioned as key devices in hybrid vehicles and electric vehicles that are expected as trump cards for reducing CO ₂ emissions. As an electrolyte of the lithium ion secondary battery, lithium hexafluorophosphate having high safety and excellent electrical characteristics can be given. The hexafluorophosphate containing lithium hexafluorophosphate is manufactured using phosphorus pentafluoride “PF ₅ ” as a starting material. The phosphorus pentafluoride is used as a fluorinating agent for various chemical reactions in the chemical industry and is a gaseous substance at room temperature.

On the other hand, silver hexafluorophosphate “AgPF ₆ ” and potassium hexafluorophosphate “KPF ₆ ” which are a kind of hexafluorophosphate are counters that generate an acid necessary for the initiation and proliferation reaction of photopolymerization. It is attracting attention as an ion. In addition, ammonium hexafluorophosphate “NH ₄ PF ₆ ” is useful as a raw material used in the production of pharmaceutical intermediates. Furthermore, quaternary ammonium salts such as triethylmethylammonium hexafluoride phosphate and tetraethylammonium hexafluoride phosphate are useful as an electrolyte for an electric double layer capacitor that is expected as a high-power storage element.

In this way, hexafluorophosphate is used as an indispensable substance according to functions required in various fields, and PF ₅ is very useful as a raw material for producing the hexafluorophosphate. It is an important substance. However, in the case of producing hexafluorophosphate using PF ₅ , a common problem is the production cost of PF ₅ . In particular, high-purity PF ₅ used for the production of high-quality hexafluorophosphate that can be used for electrolytes such as lithium ion secondary batteries is extremely expensive.

The preparation method of PF ₅ and hexafluorophosphate are described in various documents as exemplified below.

Patent Document 1 discloses a method for producing PF ₅ by thermally decomposing a raw material. For example, in the case of thermal decomposition of LiPF ₆ (the following formula 1), LiPF ₆ undergoes slight thermal decomposition around 120 ° C. and completely pyrolyzes around 200-250 ° C. Thereafter, LiF powder remains. In the case of NH ₄ PF ₆ , thermal decomposition occurs at about 250 ° C., NaPF ₆ at about 400 ° C., and KPF ₆ and CsPF ₆ at 600 ° C. to 700 ° C. The production of PF ₅ is difficult. As a result, an expensive heat-resistant specification manufacturing facility is required, and the manufacturing cost increases. Therefore, the manufacturing method disclosed in Patent Document 1 is not industrially reasonable.

Further, fluorination of phosphorus using ClF ₃ in a liquid hydrogen fluoride medium (see Non-Patent Document 1 below) and fluorination of phosphorus using a fluorine gas (Patent Document 2 and Non-Patent Documents below) 2) has a problem that it is very difficult to control the reaction because the reaction proceeds explosively. Furthermore, since expensive fluorine gas is used, the obtained PF ₅ is naturally expensive.

Patent Document 3 describes fluorination of phosphoryl trifluoride “POF ₃ ” using HF in the presence of sulfur trioxide. However, this reaction has a problem that the yield is inferior, sulfuric acid is generated, and corrosivity is extremely high in the presence of HF.

Patent Document 4 discloses a method of reacting hexafluorophosphoric acid (HPF ₆ ) with a sulfur-based acid under high pressure. However, as in Patent Document 3, sulfuric acid is generated and corrosion is extremely high in the presence of HF, and water or fluorosulfuric acid (HSO ₃ F) reacts with PF ₅ even if fuming sulfuric acid is used. However, the problem is that the generated PF ₅ is decomposed into POF ₃ .

Non-Patent Document 3 describes that LiPF ₆ is produced by dissolving lithium chloride in HF and adding phosphorus pentachloride thereto. In Patent Document 5, phosphorus pentachloride and HF gas are reacted in the range of 60 to 165 ° C., and PF ₅ obtained is added to an anhydrous HF solution of an alkali metal fluoride to obtain hexafluorophosphate. There is a description of manufacturing.

However, in the production methods disclosed in Non-Patent Document 3 and Patent Document 5, phosphorus pentachloride is a solid with a high hygroscopic property, and therefore, due to the poor handling property, the raw material is charged into the production facility. However, the workability is poor and it is difficult to mechanize. In addition, when a phosphorus halide represented by phosphorus pentachloride is used as a raw material, a large amount of hydrogen halide is by-produced. For this reason, there is an inconvenience that a long exhaust gas treatment facility is required. Furthermore, water contained in phosphorus pentachloride is mixed into the reaction system, and a part of the generated PF ₅ reacts with the mixed water to generate phosphorus oxyfluoride such as POF ₃ or PO ₂ F as a by-product. As a result, for example, when the hexafluorophosphate is LiPF ₆ , an oxyfluorophosphoric acid compound such as LiPOF ₄ or LiPO ₂ F ₂ is generated to contaminate the product, and finally the productivity of LiPF ₆ is increased. It is getting worse. In addition, when LiPF ₆ produced by this method is used as an electrolyte for a lithium battery, the oxyfluorophosphoric acid compound causes problems such as damage to battery characteristics.

In order to improve the above problem, for example, Patent Document 6 discloses the following manufacturing method. First, PF ₅ is produced by reacting phosphorus pentachloride with anhydrous HF. Next, the mixed gas of PF ₅ and hydrogen chloride is cooled to a temperature not higher than the boiling point of phosphorus oxyfluoride and not lower than the boiling point of PF ₅ , specifically to −40 ° C. to −84 ° C. After separating phosphorus, it is reacted with lithium fluoride dissolved in anhydrous HF. In this method, a small amount of phosphorus oxyfluoride is separated from a mixed gas of a large excess of hydrogen chloride and PF ₅ . However, phosphorus oxyfluoride cannot be completely separated, and the separation operation is extremely difficult. Further, for example, POF ₃ as phosphorus oxyfluoride has a problem that the boiling point and the freezing point are close to each other, so that there is a concern that the collecting device is clogged. For this reason, it is inadequate to apply the said manufacturing method to industrial implementation.

Further, Patent Document 7 discloses a method for producing PF ₅ using the chloride (phosphorus trichloride or phosphorus pentachloride) as a phosphorus raw material. In this production method, PF _{5 is} produced. Is mixed with hydrogen chloride. Since the boiling point of PF ₅ is −84.8 ° C., whereas the boiling point of hydrogen chloride is −84.9 ° C., it is impossible to separate hydrogen chloride from PF _{5 by} a simple method.

The production methods of PF ₅ and hexafluorophosphate described above have various problems such as poor workability, reaction under severe conditions, use of expensive raw materials, and treatment of by-products. . For this reason, the manufacturing cost is high. In particular, high-quality PF ₅ is expensive because it is difficult to manufacture. As a result, hexafluorophosphate produced using PF ₅ as a raw material is also expensive. Therefore, in order to produce an inexpensive and high-quality hexafluorophosphate, it is important to produce an inexpensive and high-quality PF ₅ . In other words, it is necessary to adopt a method in which adverse effects due to the mixing of impurities, particularly moisture, can be suppressed, and a raw material considering the working environment can be used as a starting raw material.

JP 2000-154209 A JP 2001-122605 A French Patent No. 2,082,502 Special table 2005-507849 Japanese Patent Laid-Open No. 06-056413 JP-A-5-279003 JP-A-11-92135

Clifford, Beachel, Jack, Inorg. Nucl. Chem (1957), 5, 57-70. Gros, Hayman, Stuart, Trans. Faraday Soc. (1996), 62 (10), 2716-18. Fluorine Chemistry Vol. 1 (1950)

  An object of this invention is to provide the manufacturing method of phosphorus pentafluoride which can manufacture high quality phosphorus pentafluoride from a cheap and low quality raw material while suppressing manufacturing cost. Further, by using phosphorus pentafluoride obtained by the method for producing phosphorus pentafluoride as a raw material, hexafluoride capable of producing high-quality hexafluorophosphate while suppressing the production cost. It aims at providing the manufacturing method of a phosphate. Furthermore, another object of the present invention is to provide an electrolytic solution to which the high-quality hexafluorophosphate obtained by the method for producing hexafluorophosphate is applied, and a power storage device including the electrolytic solution. To do.

  The inventors of the present application have studied a method for producing phosphorus pentafluoride and hexafluorophosphate in order to solve the conventional problems. As a result, the inventors have found that the object of the present invention can be achieved by adopting the following configuration, and have completed the present invention.

  That is, in order to solve the above-described problem, the method for producing phosphorus pentafluoride according to the present invention brings a carrier gas into contact with a raw material containing at least a phosphorus atom and a fluorine atom. It is characterized by extracting and separating phosphorus fluoride.

  In the above method, a carrier gas is brought into contact with a raw material containing at least phosphorus atoms and fluorine atoms. Thereby, phosphorus pentafluoride can be separated and extracted from the raw material accompanying the carrier gas. The extracted phosphorus pentafluoride is high in purity because it does not contain impurities such as oxyfluorophosphoric acid compounds, metals, and moisture. As a result, extremely good quality phosphorus pentafluoride can be easily obtained as a raw material for hexafluorophosphate while suppressing the manufacturing cost.

  The fluorine atom in the raw material is preferably contained as hydrogen fluoride.

  As the carrier gas, hydrogen fluoride gas can be used. As a result, the raw material containing at least phosphorus atoms and fluorine atoms reacts with a part of the hydrogen fluoride gas to generate phosphorus pentafluoride.

  By heating or reducing the pressure of the raw material, phosphorus pentafluoride can be evaporated from the raw material together with hydrogen fluoride gas.

  In addition, in order to solve the above-described problem, the method for producing phosphorus pentafluoride according to the present invention brings hydrogen fluoride gas as a carrier gas into contact with a raw material containing at least phosphorus atoms, thereby bringing the fluorine into contact. It is characterized by extracting and separating phosphorus pentafluoride into hydrogen fluoride gas.

  In the above method, hydrogen fluoride as a carrier gas is brought into contact with a raw material containing at least phosphorus atoms. As a result, the raw material containing phosphorus atoms reacts with part of the hydrogen fluoride gas to produce phosphorus pentafluoride. This phosphorus pentafluoride is generated along with hydrogen fluoride gas. The extracted phosphorus pentafluoride is high in purity because it does not contain impurities such as oxyfluorophosphoric acid compounds, metals, and moisture. As a result, extremely good quality phosphorus pentafluoride can be easily obtained as a raw material for hexafluorophosphate while suppressing the manufacturing cost.

  It is preferable that polyatomic ions containing phosphorus atoms and fluorine atoms exist at least in the raw material after contacting with the carrier gas.

The polyatomic ions, PF ₆ ^- is preferably an ion.

  In the method, it is preferable to reuse the raw material in which the phosphorus pentafluoride is generated.

  Moreover, in order to solve the said subject, the manufacturing method of the hexafluorophosphate of this invention WHEREIN: The phosphorus pentafluoride obtained by the manufacturing method of the phosphorus pentafluoride described above, and fluoride. It reacts according to the following chemical reaction formula to produce hexafluorophosphate.

  Phosphorus pentafluoride obtained by the above-mentioned production method does not contain impurities such as moisture compared to the conventional production method and is high purity, so that a hydrolyzate of hexafluorophosphate is produced. Can be suppressed. That is, in the above method, a high purity hexafluorophosphate that does not contain a hydrolyzate can be produced.

  The reaction between phosphorus pentafluoride and fluoride includes a first step in which phosphorus pentafluoride gas is dissolved in a solvent, and a fluoride that is stoichiometrically equivalent to or lower than phosphorus pentafluoride in the solvent. In addition to the second step of producing a hexafluorophosphate solution, and circulating the hexafluorophosphate solution to the first step, the hexafluorophosphate is substituted for the solvent. It is preferable to perform at least the third step of dissolving phosphorus pentafluoride gas in this solution.

  Fluorides are generally poorly soluble in anhydrous HF solvents and organic solvents having a low dielectric constant. Therefore, when fluoride is added to these solvents prior to absorption of phosphorus pentafluoride gas, a suspended (slurry) state is obtained. For this reason, when phosphorus pentafluoride is absorbed, clogging with solid fluoride occurs inside the apparatus, which hinders operation. However, in the above-described method, first, phosphorus pentafluoride gas is absorbed in the solvent in the first step, and then fluoride is added to the solvent in the second step. Thus, hexafluorophosphate is synthesized in a solvent as shown in Formula 1. Furthermore, since the amount of fluoride added is stoichiometrically equivalent to or less than phosphorus pentafluoride, all of the fluoride reacts with phosphorus pentafluoride. As a result, a non-slurry hexafluorophosphate solution with no unreacted fluoride remaining is obtained. Thereby, the hexafluorophosphate solution can be circulated in the first step, and phosphorus pentafluoride gas can be dissolved in the hexafluorophosphate solution instead of the solvent (third step). . That is, with the above method, various apparatuses including an absorption tower can be used, and continuous operation is also possible, thereby improving the productivity of hexafluorophosphate.

  In the above method, a hydrogen fluoride solution can be used as the solvent.

  Moreover, an organic solvent can also be used as the solvent.

  Here, the organic solvent is preferably at least one of a non-aqueous organic solvent and a non-aqueous ionic liquid. Thereby, phosphorus pentafluoride can be absorbed, without inducing hydrolysis like an anhydrous HF solvent. In addition, when phosphorous pentafluoride or hexafluorophosphate is hydrolyzed, it is difficult to react with acidic substances such as oxyfluorophosphoric acid, HF, and phosphoric acid, or with the above solvents. A dissolved component is produced. When an electrolytic solution containing these acidic substances and insoluble components is used in a power storage element, it has adverse effects such as corrosion of the power storage element and deterioration of electrical characteristics. For this reason, it is preferable to use a solvent having a low moisture concentration. From such a viewpoint, the water concentration of the organic solvent is preferably 100 ppm by weight or less, more preferably 10 ppm by weight or less, and particularly preferably 1 ppm by weight or less.

  The first step and the third step are preferably performed using an absorption tower. According to the production method of the present invention, the fluoride is added after the phosphorus pentafluoride gas is dissolved in the solvent and the hexafluorophosphate solution, so that the suspension (slurry) state does not occur. For this reason, in the first step and the third step, for example, even if an absorption tower is used, it is possible to prevent clogging in the interior and to enable continuous operation. As a result, the productivity of hexafluorophosphate can be improved.

  Of the phosphorus pentafluoride gas, it is preferable that unreacted phosphorus pentafluoride gas is absorbed and recovered by the absorption liquid and reused. Thereby, loss of phosphorus pentafluoride gas as a raw material can be prevented, and the production efficiency can be improved.

  In order to solve the above-described problems, an electrolytic solution according to the present invention includes hexafluorophosphate obtained by the above-described method for producing hexafluorophosphate.

  Moreover, in order to solve the said subject, the electrical storage element which concerns on this invention is equipped with the electrolyte solution as described above, It is characterized by the above-mentioned. A lithium ion secondary battery etc. are mentioned as an electrical storage element of this invention.

  The present invention has the following effects by the means described above.

  That is, according to the present invention, high-quality phosphorus pentafluoride can be produced at low cost, with a low moisture concentration and high purity, using low-quality raw materials without requiring complicated processing operations and special equipment. Further, by using the high-quality phosphorus pentafluoride obtained by the present invention, it is possible to easily produce a low-quality and high-quality hexafluorophosphate without using a complicated apparatus. Furthermore, by applying the high-grade hexafluorophosphate obtained by the present invention to the electrolytic solution, a power storage device having high safety and excellent electrical characteristics can be obtained.

It is explanatory drawing which shows roughly the manufacturing apparatus of phosphorus pentafluoride which concerns on embodiment of this invention. It is a conceptual diagram showing the manufacturing apparatus of phosphorus pentafluoride used in Examples 7-10 and Comparative Example 2. It is a conceptual diagram showing the manufacturing apparatus of phosphorus pentafluoride used in Examples 1-6 and Comparative Example 1. It is explanatory drawing which shows roughly sectional drawing of the lithium ion secondary battery of this invention.

(Method for producing phosphorus pentafluoride)
One embodiment of the present invention will be described below.

  The method for producing phosphorus pentafluoride according to the present embodiment is performed by bringing a carrier gas into contact with a raw material containing at least phosphorus atoms and fluorine atoms.

  The raw material containing at least phosphorus atoms and fluorine atoms may be in any state of liquid, gas, and solid. Moreover, it is good also as a solution by dissolving in water, an anhydrous hydrogen fluoride solvent, and an organic solvent.

The substance containing a phosphorus atom in the raw material is not particularly limited as a substance containing a phosphorus atom. For example, white phosphorus, red phosphorus, black phosphorus, phosphorus trichloride (PCl ₃ ), phosphorus tribromide (PBr) ₃ ), phosphine (PH ₃ ), phosphorous acid, phosphorus pentoxide (P ₂ O ₅ ), orthophosphoric acid (H ₃ PO ₄ ), polyphosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, isophosphoric acid, Phosphonic acid, phosphinic acid, phosphenic acid, diphophonic acid, cyanophosphoric acid, cyanophosphonic acid, diethyldithiophosphinic acid, chlorophenylphosphonic acid, trimethyl phosphate, phenylselenophosphinic acid = o-methyl, pyrophosphonic acid, phosphorus oxychloride (POCl ₃ ), phosphorus oxybromide (POBr _3), oxyhalides such as oxy so phosphorus (POI ₃₎ or phosphorus oxyfluoride (POF ₃₎ Cali , Phosphorus pentasulfide (P ₂ S _5), Chiofu' phosphorus (PSF _3), trichlorophosphine sulfide (PSCl _3), phosphonium nitrile Floyd (PNF _2), phosphonium nitrile chloride (PNCl _2), phosphorus pentachloride, pentabromide Phosphorus, phosphorus pentaiodide, HPF ₆ , LiPF ₆ , NaPF ₆ , KPF ₆ , RbPF ₆ , CsPF ₆ , NH ₄ PF ₆ , AgPF ₆ , Mg (PF ₆ ) ₂ , Ca (PF ₆ ) ₂ , Ba (PF ₆ ) ₂ , Zn (PF ₆ ) ₂ , Cu (PF ₆ ) ₂ , Pb (PF ₆ ) ₂ , Al (PF ₆ ) ₃ , Fe (PF ₆ ) _{3 and the} like. These phosphorus compounds can be used alone or in combination of two or more.

  Examples of the substance containing a fluorine atom in the raw material include HF. In this case, HF may be used in the form of anhydrous hydrogen fluoride, or may be used after being dissolved in water, an organic solvent, or a mixed solvent of water and an organic solvent. Moreover, it does not specifically limit as HF, For example, commercially available hydrofluoric acid, such as an industrial grade, a general grade, and a semiconductor grade, can be used as it is, or it can adjust density | concentration suitably. Among these, the use of a semiconductor grade is preferable from the viewpoint of a small amount of impurities, and anhydrous hydrogen fluoride, industrial grade, and general grade are preferable from the viewpoint of cost. As the impurity concentration, each metal impurity is preferably 1000 ppm by weight or less.

  Further, the content of phosphorus atoms contained in the raw material is not particularly limited, but is preferably 0.01% by weight to 25% by weight, more preferably 0.01% by weight to 15% by weight, The weight percentage is particularly preferably 10% by weight or more. If the phosphorus atom content is less than 0.01% by weight, the yield of phosphorus pentafluoride may decrease. On the other hand, when the content of phosphorus atoms exceeds 25% by weight, the viscosity increases when the raw material is a solution. As a result, there may be inconveniences when transporting the liquid. In addition, gas may be generated to cause inconvenience.

  The content of fluorine atoms contained in the raw material is not particularly limited, but is preferably 0.03% by weight or more, and more preferably 0.3% by weight or more.

The proportion of fluorine atoms in the raw material is preferably present in a chemical equivalent or more with respect to the number of phosphorus atoms within the numerical range of the fluorine atom content. If the proportion of fluorine atoms in the raw material is less than the chemical equivalent, the concentration of PF ₅ that can be produced in the raw material may be 0.05% by weight or less. As a result, the vapor pressure of PF ₅ becomes too low and the amount of carrier gas necessary to obtain a desired amount of PF ₅ increases. As a result, a large extraction device is required, which is inconvenient.

  When polyatomic ions containing phosphorus atoms and fluorine atoms are present in the raw material, the concentration is 0.03% to 50% by weight, preferably 0.5% to 20% by weight in the liquid state It is good to use in. The substance containing a phosphorus atom does not need to be completely dissolved in the solution, and may be in a suspended state.

  A method for producing the raw material by mixing a substance containing a phosphorus atom and a substance containing a fluorine atom is not particularly limited. For example, a continuous type or a batch type may be used. Moreover, after putting the substance containing a phosphorus atom in a mixing tank, you may throw in and manufacture the substance containing fluorine atoms, such as HF. The order of input may be reversed.

  Although it does not specifically limit as a temperature at the time of mixing the substance containing a phosphorus atom and the substance containing a fluorine atom, It is preferable to exist in the range of -50-200 degreeC. When the temperature is lower than −50 ° C., a composition containing a substance containing a phosphorus atom and a substance containing a fluorine atom may solidify. On the other hand, if the temperature exceeds 200 ° C., a special device is required in terms of heat resistance and the like, which may not be preferable.

About the water | moisture content in the said raw material, it is so preferable that the vapor | steam pressure of the said water | moisture content is low. This is because when moisture is extracted into the carrier gas, hydrolysis of PF ₅ extracted at the same time is induced. From such a viewpoint, the water concentration in the raw material is preferably 5% by weight or less, more preferably 0.5% by weight or less, and particularly preferably 0.05% by weight or less.

The raw material does not need to be highly pure and may contain metal impurities. Further, it may contain an oxygen-containing impurity such as sulfate radical, moisture, or an oxyfluorophosphoric acid compound. In the production method of the present invention, these impurities are not extracted into the carrier gas even when in contact with the carrier gas, and as a result, the produced PF ₅ is not contaminated. That is, the method for producing phosphorus pentafluoride according to the present invention does not require the use of complicated and sophisticated purification methods even when using low-quality raw materials that are easily available, and high-quality PF ₅ can be obtained. . Incidentally, the PF ₅ high-quality, for example, when used as a raw material for high-quality LiPF _6, water concentration in PF ₅ is 50 wt ppm or less, and the concentration of various metal impurities is 1 ppm by weight or less Is considered to mean. In addition, for example, in the case of LiPF ₆ , hexafluorophosphate is used as an electrolyte for a lithium ion secondary battery. Purity, moisture, metal impurities, free hydrofluoric acid affecting the stability of the battery In addition, strict standards for insoluble residues, etc. are required, and extremely high purity and high quality are required. Specifically, in the case of LiPF _6, a high-quality product having a purity of 99.9% or more, a moisture concentration of 50 ppm by weight or less, a concentration of various metal impurities of 1.0 ppm by weight or less, and a free hydrofluoric acid concentration of 50 ppm by weight or less. LiPF ₆ is used.

As the carrier gas to be brought into contact with the raw material, a gas inert to the raw material is suitable. Specifically, for example, HF gas, N ₂ gas, He gas, Ar gas, dry air, carbon dioxide gas and the like can be exemplified. Of these, HF gas is preferred in the present invention. The HF gas can be easily liquefied by cooling or pressurizing. For this reason, when HF gas is used as the carrier gas, there is an advantage that it can be easily separated from the PF ₅ gas. Further, when the HF gas is liquefied and recovered and then gasified by means such as heating, it can be reused again as a carrier gas. The HF gas may be mixed with other gases listed above.

  The carrier gas has a water content of preferably 1 wt% or less, more preferably 100 wt ppm or less, and particularly preferably 10 wt ppm or less. When the water content exceeds 1% by weight, the water content in the extracted phosphorus pentafluoride also increases. If this phosphorus pentafluoride is used as a raw material for hexafluorophosphate, a hydrolyzate of hexafluorophosphate is generated by the contained water, which is not preferable.

  The method of bringing the carrier gas into contact with the raw material is not particularly limited, and a commonly used tank-type or tower-type gas-liquid contact device is preferably used. For example, as shown in FIG. 1 (a), it is carried out by bubbling a carrier gas into the raw material or a solution thereof. The phosphorus pentafluoride extracted together with the carrier gas contains almost no water, whereby high-quality phosphorus pentafluoride is obtained and is suitable as a raw material for hexafluorophosphate.

  When HF gas is used as the carrier gas, as shown in FIG. 1B, when HF gas as the carrier gas is introduced into a container filled with the raw material, a part of the HF gas reacts with the raw material and Phosphorus fluoride gas is generated. This phosphorus pentafluoride gas can be extracted into HF gas. It is also effective to condense and separate the HF gas from the exhausted gas using a heat exchanger or the like and return it to a container in which the raw material and the carrier gas are in contact. Thereby, the raw material and HF gas can be further reacted, and the extraction amount of phosphorus pentafluoride can be further increased.

  Moreover, when using HF gas as carrier gas, as shown in FIG.1 (c), HF gas may be previously melt | dissolved in the said raw material, and this mixed solution may be heated and distilled. Thereby, phosphorus pentafluoride can be extracted and separated together with the evaporation of HF gas. In this case, in the mixed solution after further dissolving the HF gas, the concentration of HF with respect to the combined weight of HF and moisture is preferably 90% by weight or more, more preferably 95% by weight or more, It is particularly preferably 98% by weight or more.

  Further, in the mixed solution after further dissolving the HF gas, the concentration of polyatomic ions including phosphorus atoms and fluorine atoms is preferably 0.03% by weight to 50% by weight, and 0.5% by weight. More preferably, it is -20% by weight. Further, the substance containing phosphorus atoms does not need to be completely dissolved in the mixed solution, and may be in a suspended state.

Furthermore, when the raw material contains a large amount of HF as a substance containing fluorine atoms, as shown in FIG. 1D, the raw material is heated to extract and separate phosphorus pentafluoride from the generated HF gas. be able to. In this method, the generated HF gas acts as a carrier gas. Further, in this method, another carrier gas prepared separately may be brought into contact with the raw material, and HF gas and PF ₅ may be extracted and separated from the other carrier gas. In addition, when HF is contained in the raw material in a large amount, HF is in a range of 10 to 5000 times, preferably in a range of 50 to 500 times in terms of molar ratio to phosphorus atoms in the raw material. It means that there is.

  The method for heating the raw material containing phosphorus atoms and fluorine atoms is not particularly limited, and a tank-type heating device or a distillation tower-type heating device equipped with a commonly used heat exchanger is related to a batch type or a continuous type. It is preferably used.

  The amount of carrier gas used is preferably in the range of 10 to 5000 times, more preferably in the range of 50 to 500 times the molar ratio of phosphorus atoms in the raw material. If the amount used exceeds the upper limit, the extraction efficiency of phosphorus pentafluoride increases, but the energy cost increases, which is not preferable. On the other hand, if the amount used is less than the lower limit, the extraction amount of phosphorus pentafluoride decreases, and phosphorus is discharged out of the reaction system.

  As temperature at the time of making carrier gas contact the said raw material, -50 degreeC-100 degreeC is preferable, -10-50 degreeC is more preferable, 0 degreeC-30 degreeC is especially preferable. If it is lower than −50 ° C., the vapor pressure of phosphorus pentafluoride is lowered, so that the extraction efficiency is disadvantageously deteriorated. On the other hand, when the temperature exceeds 100 ° C., water may enter the system, resulting in a disadvantage that hydrolysis of phosphorus pentafluoride occurs. In the case of the distillation method shown in FIGS. 1C and 1D, the heating temperature needs to be equal to or higher than the boiling point of the hydrogen fluoride solution. More specifically, for example, when carried out at 1 atm, it is preferably in the range of 19.5 to 50 ° C, more preferably in the range of 20 to 30 ° C.

  The pressure when the carrier gas is brought into contact with the raw material is preferably 1 KPa to 5 MPa, more preferably 10 KPa to 1 MPa, and particularly preferably 0.05 MPa to 0.5 MPa. If it is less than 1 KPa, there is a disadvantage that the cost is excessive because a long vacuum facility is required. On the other hand, if it exceeds 5 MPa, there is a disadvantage that the high-pressure device becomes excessive.

  Moreover, the manufacturing method of phosphorus pentafluoride which concerns on this invention may manufacture phosphorus pentafluoride by making carrier gas contact the raw material containing a phosphorus atom. In this case, HF gas is used as the carrier gas. When the HF gas comes into contact with a raw material containing phosphorus atoms, a reaction occurs between them, and phosphorus pentafluoride is extracted as a carrier gas. Furthermore, the HF gas can separate and extract phosphorus pentafluoride that does not contain moisture.

When the carrier gas contains phosphorus oxyfluoride such as POF ₃ in addition to phosphorus pentafluoride, the carrier gas is preferably brought into contact with anhydrous hydrogen fluoride. At this time, it is more preferable to contact with liquid anhydrous hydrogen fluoride. As a result, as shown in the following chemical reaction formula, phosphorus oxyfluoride such as POF ₃ can be reacted with anhydrous hydrogen fluoride to newly generate PF ₅ .

  The carrier gas used for the production of phosphorus pentafluoride is preferably reused. For example, when HF gas is used as the carrier gas, HF gas containing phosphorus pentafluoride is condensed to separate phosphorus pentafluoride and HF. The condensed and recovered HF may be heated and evaporated to be reused as a carrier gas or may be used as a raw material for fluorine atoms. The temperature for condensing the HF gas is preferably -80 ° C to 100 ° C, more preferably -50 ° C to 50 ° C, and particularly preferably -10 to 20 ° C.

  Further, it is preferable to separate and recover the phosphorus component and the fluorine component from the raw material after the phosphorus pentafluoride is separated. The collected phosphorus component is concentrated and can be reused as a raw material for phosphorus atoms. As the separation operation, for example, a conventionally known method such as distillation can be employed. The fluorine component may be recovered and reused as a raw material for fluorine atoms, recovered as HF, used as it is as industrial hydrofluoric acid, or may be used after adjusting the concentration as appropriate. Further, when the amount is very small, it may be discharged by direct drainage treatment.

When the extraction of PF ₅ from the raw material containing the phosphorus atom and a fluorine atom into the carrier gas proceeds, in some cases it may PF ₅ is re-dissolved in the raw material. For this reason, as the extraction of PF ₅ proceeds, the extraction amount of PF ₅ decreases. In order to suppress this, it is effective to perform a continuous operation.

The continuous operation can be realized by continuously supplying the raw material to a contact device with a carrier gas and continuously extracting the extracted raw material from the contact device. By performing this continuous operation, PF ₅ can be produced quantitatively.

When HF accompanies PF _{5 in the} carrier gas, it is effective to condense and separate HF with a heat exchanger or the like and return it to the contact device between the raw material and the carrier gas. However, a small amount of PF ₅ may be contained in the refluxed HF. In this case, HF containing a small amount of PF ₅ may be refluxed as it is, or may be refluxed after being supplied to a separately prepared separator and separating PF ₅ .

In the above case, it is not always necessary to isolate PF ₅ , and it may be used in the next step as it is depending on the purpose of use.

However, when a carrier gas other than HF gas is used, the amount of fluorine atoms in the raw material is reduced by extracting PF ₅ from the raw material, while the vapor pressure of moisture in the raw material is reduced. It may rise and contaminate the extracted PF ₅ or induce hydrolysis. In such a case, it is preferable to supply HF to the carrier gas / raw material contact device in a timely manner.

The material of the apparatus used in the method for producing PF _{5 according to} the present invention is not particularly limited, and general-purpose materials such as carbon steel and stainless steel can be suitably used. Further, a high-grade material such as high alloy steel may be used as needed, or a resin material such as a fluororesin or a vinyl chloride resin, or a resin lining material coated with them may be used. Furthermore, these materials may be used in appropriate combination.

(Method for producing hexafluorophosphate)
Next, by contacting the high-quality PF ₅ gas obtained by the above method with fluorides (AFs), hexafluorophosphate is produced according to the following chemical reaction formula. Further, it is possible to high-quality PF ₅ obtained in this paper is taken up in an organic solvent to obtain a high-purity PF ₅ complex. The organic solvent is not particularly limited, and examples thereof include methanol, tetrahydrofuran, diethyl ether, tetrahydrothiophene, triethylamine, propylene carbonate, dimethyl carbonate, and diethyl carbonate. Furthermore, a hexafluorophosphoric acid solution containing no water can be obtained by adding a chemical equivalent of HF to the PF ₅ complex.

Specific production methods of the hexafluorophosphate include (1) a method of reacting a solid fluoride with PF ₅ gas, and (2) a fluoride dissolved or suspended in anhydrous HF as a solvent. Examples thereof include a method of reacting PF ₅ gas, or (3) a method of reacting fluoride and PF ₅ gas in an organic solvent.

The reaction temperature between the fluoride and the PF ₅ gas is preferably −50 ° C. to 200 ° C., more preferably −10 to 100 ° C., and particularly preferably 0 ° C. to 50 ° C. If it is lower than −50 ° C., the reaction may not easily proceed. On the other hand, when it exceeds 200 ° C., the produced hexafluorophosphate may be decomposed. In the case of the method of reacting anhydrous HF containing the fluoride (including acid fluoride) (2) with the PF ₅ gas obtained by the present invention, the decomposition reaction of the produced hexafluorophosphate is suppressed. In order to achieve this, it is preferable to carry out a reaction such as cooling and react at a boiling point or lower (for example, 19.5 ° C. or lower, preferably 0 to 10 ° C. at 1 atmosphere).

From the viewpoint of improving the purity and yield of hexafluorophosphate, it is preferable to react an excess amount of PF ₅ gas with fluoride “AFs”. Specifically, for example, the weight ratio is preferably 1 to 10 times, more preferably 1.01 to 5 times, and particularly preferably 1.05 to 2 times that of AFs. If the amount of the PF ₅ gas used exceeds 10 times, the yield of hexafluorophosphate increases, but excess PF ₅ gas may flow out of the reaction system and decrease the yield of phosphorus. . On the other hand, if the amount used is less than 1 time, the yield of hexafluorophosphate decreases, which is not preferable.

In order to reduce the loss of PF _{5 in} the above, water or an HF aqueous solution of 0 to 80% by weight or M salt (M salt is Li, Na, K, Rb, Cs, NH ₄ , Ag, Mg, Water in which at least one of carbonate, hydroxide and halide selected from the group consisting of Ca, Ba, Zn, Cu, Pb, Fe and Al is dissolved or 0 to A gas containing excess PF ₅ flowing out from the reaction system is absorbed by using an 80 wt% HF aqueous solution as an absorbing solution, and M (PF ₆ ) _S (1 ≦ s ≦ 3) or H _x PO _y F _z (0 ≦ x ≦ 3, 1 ≦ y ≦ 4, 0 ≦ z ≦ 6). Furthermore, the surplus which flows out of a reaction system in the water which dissolved the fluoride of MF _S * r (HF) (1 <= s <= 3, 0 <= r <= 6) or 0-80 weight% HF aqueous solution is especially preferable among them. to absorb the PF ₅ laden _{gas, M (PF 6) S ·} r (HF), may be recovered as a (1 ≦ s ≦ 3,0 ≦ r ≦ 6), or HPF _6. Here, MF _s · r (HF) may be obtained by the reaction of the M salt and hydrofluoric acid.

The PF ₅ absorber described above is not particularly limited, and for example, a known absorber using a packed tower, a multistage tower, a spray tower, or the like can be preferably used.

Further, as described above, when a fluoride and PF ₅ gas are reacted in an organic solvent, first, the PF ₅ gas is dissolved in the organic solvent, and then the organic solvent is dissolved in the organic solvent. A method of reacting fluoride and PF ₅ gas in an organic solvent by adding fluoride is preferred. A manufacturing apparatus applied to this method is shown in FIG. The manufacturing apparatus shown in the figure includes a first absorption tower 1 and a second absorption tower 5, a first tank 2, a second tank 6, a third tank 10, pumps 3, 7, 11 and a first cooler. 4 and the 2nd cooler 8, the deaeration tower 9, the air pump 12, and the condenser 13 are provided.

A predetermined amount of organic solvent is put into the first tank 2 and the second tank 6. The pumps 3 and 7 supply the liquid in the first tank 2 and the second tank 6 to the first absorption tower 1 and the second absorption tower 5, respectively, and perform circulation operation. Next, PF ₅ gas is supplied to the bottom of the second absorption tower 5. PF ₅ may be 100%, or may be appropriately diluted by mixing an inert gas. Heat generation in the first absorption tower 1 and the second absorption tower 5 can be reduced by mixing the inert gas. Furthermore, the not particularly restricted but includes inert gas, for example N _2, Ar, dry air, carbon dioxide, and the like. The moisture in the inert gas used for dilution is preferably low moisture of 100 ppm by weight or less, more preferably 10 ppm by weight or less, and more preferably 1 ppm by weight or less so as not to induce hydrolysis of PF _5. It is particularly preferred that The PF ₅ gas is dissolved in the organic solvent by making countercurrent contact with the organic solvent in the first absorption tower 1 and the second absorption tower 5 (first step). The heat absorbed by the organic solvent of PF ₅ is removed by the first cooler 4 and the second cooler 8 provided in the circulation line, and is maintained at an appropriate operating temperature.

Next, the organic solvent in which the PF ₅ gas is dissolved is supplied to the second tank 6. The second tank 6 is supplied with a stoichiometric amount of fluoride equivalent to or less than PF ₅ . Thus, PF ₅ and fluoride reacts, hexafluorophosphate is produced (second step). The following reaction formula shows the reaction between PF ₅ and lithium fluoride.

The hexafluorophosphate solution generated in the second tank 6 is sent out by a pump 7 through a pipe and supplied to the top of the second absorption tower 5. PF ₅ supplied to the bottom of the column is absorbed in the hexafluorophosphate solution in the second absorption column (third step). Subsequently, the hexafluorophosphate is increased to a desired concentration by continuously reacting with fluoride in the second tank 6. By performing such a circulation operation, when a predetermined concentration is reached, a part of the solution from the pump 7 is extracted as a product. Simultaneously with the extraction of the product, the supply of the organic solvent from the outside to the first absorption tower 1 is started, and the liquid supply destination of the pump 3 is switched from the first absorption tower 1 to the second absorption tower 5 to obtain hexafluorophosphate. The continuous production of the solution is performed. At this time, the absorption liquid may be supplied to the second absorption tower 5 while continuing to circulate a part of the absorption liquid to the first absorption tower 1 at the same time.

The supply amount of the fluoride to the second tank 6 is the stoichiometric amount with respect to PF ₅ dissolved in the organic solvent in order to avoid the presence of the fluoride that is hardly soluble in the organic solvent in a slurry state. Are preferably equivalent or less. Thereby, it is possible to avoid clogging or the like due to the slurry-like fluoride in the apparatus. A method of making PF ₅ stoichiometrically excessive with respect to fluoride can be realized by always supplying a stoichiometric excess of PF ₅ with respect to fluoride. PF ₅ must be discharged out of the system in any step, which is not preferable because it causes loss of raw materials. A method by which PF ₅ and fluoride are supplied in a stoichiometrically equivalent manner to a liquid that has previously absorbed an excessive amount of PF ₅ suitable for operation is more preferable.

The fluoride added in the second step is not limited to LiF, but NaF, KF, RbF, CsF, NH ₄ F, AgF, CaF ₂ , MgF ₂ , BaF ₂ , ZnF ₂ , CuF ₂ , PbF ₂ , AlF _3, FeF _3, and the like. These fluorides may be used alone or in combination of two or more depending on the purpose.

Further, the hexafluorophosphate solution in which PF ₅ is excessively dissolved produced in the second step is supplied to the top of the second absorption tower 5 in the third step. Also supplied to the deaeration tower 9. Further, the hexafluorophosphate solution sent to the deaeration tower 9 is depressurized by the air pump 12, and the PF ₅ gas is distilled off. As a result, the solution is adjusted to a hexafluorophosphate solution in which PF ₅ and fluoride are stoichiometrically equivalent, and the solution is extracted from the third tank 10 as a product. Although it is possible to prepare a hexafluorophosphate solution by adding a fluoride that is stoichiometrically equivalent to PF ₅ dissolved in excess, excess PF ₅ is distilled off under reduced pressure from the viewpoint of continuous productivity. It is preferable. Further, in order to increase the efficiency of removing PF ₅ by decompression, the deaeration tower 9 may be provided with a heater and heated.

The distilled PF ₅ gas is supplied to the bottom of the second absorption tower 5 by the air pump 12. Furthermore, it is recovered and reused by making countercurrent contact with the organic solvent and / or hexafluorophosphate solution in the second absorption tower 5. When PF ₅ used as a raw material contains a small amount of HF, the hexafluorophosphate solution is depressurized with an air pump 12 to distill off the HF, and then condensed by the condenser 13 to be removed. It doesn't matter. The liquid (drain) condensed in the condenser 13 contains an organic solvent, HF, and PF _5. However, the liquid may be discarded after being treated as it is, or HF, PF _5, or the organic solvent may be recovered as necessary. You can reuse it. As a recovery method, a normal method such as distillation or extraction can be used.

  As described above, in the present invention, a high-purity hexafluorophosphate can be continuously produced with high yield by circulating a hexafluorophosphate solution.

  In the present invention, it is preferable to use an absorption tower from the viewpoint of industrial production efficiency, but this does not exclude the use of surface absorption or bubbling. Further, the first absorption tower 1 and the second absorption tower 5 can use any type of absorption device such as a packed tower, a plate tower, and a wet wall tower. Furthermore, the type of absorption may be either countercurrent or cocurrent.

In the first and third steps, the concentration of the PF ₅ gas in the organic solvent and hexafluorophosphate solution is preferably 15% by weight or less, more preferably 10% by weight or less, and more preferably 5% by weight or less. Is particularly preferred. When the PF ₅ gas concentration in the organic solvent exceeds 15% by weight, the reaction between the organic solvent and PF ₅ occurs, and the organic solvent may be colored, modified, or solidified. In addition, the heat of absorption becomes large and it may be difficult to control the liquid temperature.

In the first step and the third step, the gas-liquid contact temperature between the PF ₅ gas, the organic solvent and the hexafluorophosphate solution is preferably -40 to 100 ° C, and preferably 0 to 60 ° C. It is more preferable that If the gas-liquid contact temperature is lower than -40 ° C, the organic solvent may solidify, and continuous operation cannot be performed. On the other hand, if the gas-liquid contact temperature exceeds 100 ° C., the vapor pressure of PF _{5 in} the organic solvent and hexafluorophosphate solution becomes too high, or the absorption efficiency decreases, or the reaction between the organic solvent and PF ₅ There is a disadvantage that occurs.

  The organic solvent is preferably at least one of a non-aqueous organic solvent and a non-aqueous ionic liquid. Furthermore, aprotic is preferable. Since it is not capable of donating hydrogen ions when it is aprotic, the solution of hexafluorophosphate obtained by the production method of the present invention is applied as it is to the electrolyte of a storage element such as a lithium ion secondary battery. be able to.

  The non-aqueous organic solvent is not particularly limited, for example, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl acetate, ethyl acetate, γ-butyl lactone, acetonitrile, Examples include dimethylformamide, 1,2-dimethoxyethane, methanol, isopropanol and the like. Among these organic solvents, from the viewpoint of continuous production, the produced hexafluorophosphate is difficult to precipitate, that is, the hexafluorophosphate is highly soluble in ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, Methyl ethyl carbonate, acetonitrile and 1,2-dimethoxyethane are preferred. These organic solvents may be used alone or in combination of two or more.

  Furthermore, examples of the non-aqueous and aprotic organic solvent include a cyclic carbonate ester, a chain carbonate ester, a carboxylic acid ester, a nitrile, an amide or an ether compound. These non-aqueous aprotic organic solvents may be used alone or in combination of two or more.

  Further, the non-aqueous ionic liquid is not particularly limited. For example, a fluoride complex salt or fluoride salt such as quaternary ammonium or quaternary phosphonium, among others, a quaternary ammonium cation includes a tetraalkylammonium cation, Examples include imidazolium cation, pyrazolium cation, pyridinium cation, triazolium cation, pyridazinium cation, thiazolium cation, oxazolium cation, pyrimidinium cation, and pyrazinium cation. Furthermore, examples of the quaternary phosphonium cation include a tetraalkylphosphonium cation. These non-aqueous ionic liquids may be used alone or in combination of two or more, or may be used by dissolving in the non-aqueous organic solvent.

  The organic solvent may be a non-aqueous organic solvent or a non-aqueous ionic liquid, or a mixture of two or more.

In addition, it is preferable that the excess phosphorus component-containing gas used in the production of hexafluorophosphate, specifically, PF ₅ gas is absorbed in the absorption liquid and recovered and reused. Examples of the absorbing liquid include water, hydrofluoric acid aqueous solution, and M salt (M is Li, Na, K, Rb, Cs, NH ₄ , Ag, Mg, Ca, Ba, Zn, Cu, Pb, Fe, and Al). A solution containing at least one selected from the group consisting of at least one selected from the group consisting of: More specifically, 0 to 80% by weight of water or aqueous hydrogen fluoride solution, or M salt (M salt is Li, Na, K, Rb, Cs, NH ₄ , Ag, Mg, Ca, Ba, Zn, Cu , Pb, Fe and Al, carbonates, hydroxides, and halides containing at least one selected from the group consisting of Pb, Fe, and Al) may be used. By absorbing the PF ₅ gas into the absorbing solution, M (PF ₆ ) _s (where 1 ≦ s ≦ 3) and / or H _x PO _y F _z (where 0 ≦ x ≦ 3, 1 ≦ y ≦ 4, 0 ≦ z ≦ 6). Thereby, even when an excessive amount of PF ₅ gas is used, loss of the raw material can be suppressed.

  In addition, the phosphorus component-containing gas generated during the production of hexafluorophosphate, specifically, phosphorus pentafluoride and HF gas are introduced into the phosphorus pentafluoride extraction device and reused as a carrier gas. May be. Thereby, even when an excessive amount of phosphorus pentafluoride gas is used, loss of the raw material can be suppressed.

  Moreover, the HF gas generated during the production of hexafluorophosphate may be reused as a carrier gas, or the hydrogen fluoride collected and recovered by absorption in water is a raw material containing phosphorus atoms. You may use for reaction with.

Further, PF ₅ flowing out from the second absorption tower 5 in the manufacture of in hexafluorophosphate to above, as shown in FIG. 2, the PF ₅ in the first absorption tower 1 connected in series to recover. The organic solvent containing PF ₅ obtained in the first absorption tower 1 is supplied to the second absorption tower 5. PF ₅ that could not be absorbed by the first absorption tower 1 may be recovered and reused by the absorption method described above. Thereby, even when an excessive amount of PF ₅ gas is used, the entire amount is used and the loss of the raw material can be suppressed.

  The reaction apparatus used for this invention will not be specifically limited if it consists of a material which has tolerance with respect to the said composition, Stainless steel or carbon steel is used suitably. However, there is a risk of corrosion due to leakage of anhydrous HF or a composition comprising the above composition or exposure to air. When the reactor is corroded, the resulting product is also contaminated by the corroded material, which causes the metal content of the product to increase. For this reason, it is preferable to use a reactor made of a fluororesin, vinyl chloride, or polyethylene that is resistant to the composition, or that is lined with these.

  Hereinafter, preferred embodiments of the present invention will be described in detail by way of example. However, the materials, blending amounts, and the like described in the examples are not intended to limit the scope of the present invention only to them, but are merely illustrative examples, unless otherwise specified. All examples and comparative examples were performed at atmospheric pressure.

Example 1
The following implementation was performed using the apparatus shown in FIG.

100 g of commercially available phosphoric anhydride (P ₂ O ₅ ) was placed in a 5 L fluororesin (PFA) reaction tank together with a rotor, and anhydrous hydrogen fluoride (HF) gas as a carrier gas was introduced thereto at 10 L / min. . The reaction tank was connected to a reflux tower (20 mmφ × 2 m) made of SUS316. While maintaining the temperature of the PFA reactor at 25 ° C. with a heating medium, the reflux tower was cooled with −50 ° C. brine. Furthermore, the inside of the reaction vessel was stirred with a magnetic stirrer. After a while, HF reflux started. Thereafter, gas generation was confirmed from the top of the reflux tower.

Gas was generated from the reflux tower, and after 5 minutes, the gas was analyzed with a Fourier transform infrared spectrophotometer (FTIR). As a result, it was confirmed that it was PF ₅ and a small amount of HF. It was confirmed that there was no generation of an oxyfluorophosphoric acid compound such as POF ₃ and PO ₂ F. Further, after absorbing 20 g of the generated gas in 500 g of ultrapure water, the metal impurity concentration in this ultrapure water was analyzed using an induction plasma mass spectrometer (ICP-MS). As a result, it was included in PF ₅ gas. It was confirmed that the concentration of the metal impurities is 0.5 ppm by weight or less.

(Example 2)
200 g of a commercially available 75% phosphoric acid (H ₃ PO ₄ ) aqueous solution and 2000 g of commercially available hydrofluoric acid (HF) are put together with a rotor in a 5 L fluororesin (PFA) reaction tank (cooled with a refrigerant), and then transferred to a carrier. N ₂ gas as a gas was introduced at 0.2 l / min. The reaction tank was connected to a reflux tower (20 mmφ × 2 m) made of SUS316. While the temperature of the PFA reaction vessel was heated to 45 ° C. with a heating medium, the reflux tower was cooled with −30 ° C. brine. Further, the reaction solution was stirred with a magnetic stirrer. As the temperature of the reaction vessel rose after a while, the reflux of HF started. The temperature of the reaction solution at that time was 23 ° C. Thereafter, gas generation was confirmed from the top of the reflux tower.

Ten minutes after gas began to be generated from the reflux tower, this gas was analyzed with a Fourier transform infrared spectrophotometer (FTIR). As a result, it was confirmed that they were PF ₅ , N ₂ and a small amount of HF. It was confirmed that there was no generation of an oxyfluorophosphoric acid compound such as POF ₃ or PO ₂ F. Furthermore, after absorbing the generated gas 20g ultra-pure water 0.5 kg, the ultra-pure inductive plasma mass spectrometer the metal impurity concentration in water (ICP-MS) Analysis using a, PF ₅ gas It was confirmed that the concentration of metal impurities contained in was 0.5 ppm by weight or less.

(Example 3)
Commercially available potassium hexafluorophosphate (KPF ₆ ) 50 g and anhydrous hydrogen fluoride (HF) 2000 g together with a rotor were placed in a 5 L fluororesin (PFA) reaction vessel and connected to a SUS316 reflux tower (20 mmφ × 2 m). . The PFA reaction tank was heated to 45 ° C. with a heating medium, and at the same time, the reflux tower was cooled with −50 ° C. brine. Further, the reaction solution was stirred with a magnetic stirrer. Reflux of HF started as the bath temperature rose. The temperature of the internal reaction solution at that time was 21 ° C.

After 5 minutes, gas was generated from the reflux tower. This gas was analyzed by FTIR. As a result, it was confirmed that it was PF ₅ and a small amount of HF. Furthermore, after absorbing the generated gas 10g ultra-pure water 0.5 kg, the ultra-pure inductive plasma mass spectrometer the metal impurity concentration in water (ICP-MS) Analysis using a, PF ₅ gas It was confirmed that the concentration of metal impurities contained in was 0.5 ppm by weight or less.

Example 4
330 g of lithium hexafluorophosphate (LiPF ₆ ) and 2000 g of anhydrous HF were placed in a 5 L-PFA reaction vessel together with a rotor, and connected to a reflux tower (20 mmφ × 2 m) made of SUS316. The PFA reaction vessel was heated to 80 ° C. with a heating medium, and at the same time, the reflux tower was cooled with 0 ° C. brine. Further, the reaction solution was stirred with a magnetic stirrer. Reflux of HF started as the bath temperature rose. The temperature of the internal reaction liquid at that time was 30 ° C.

When the gas generated from the reflux tower was analyzed by FTIR, it was confirmed that the gas was PF ₅ and a small amount of HF. At the same time, the generated gas was absorbed in pure water for 4 hours, the P content of the absorbing solution was measured, and the weight of the generated PF ₅ gas was calculated. As a result, it was 205 g, and 75% was generated.

(Example 5)
90 g of ammonium hexafluorophosphate (NH ₄ PF ₆ ) and 2000 g of anhydrous HF were placed in a 5 L-PFA reaction tank together with a rotor, and the reaction solution was stirred with a magnetic stirrer. In the present Example 5, it carried out without installing a reflux tower. The generated gas was analyzed by FTIR and simultaneously absorbed in pure water. When the PFA reaction tank was heated to 65 ° C. with a heating medium, hydrogen fluoride evaporated and reacted vigorously with pure water as the absorbing solution. As a result of FTIR analysis of the generated gas, it was confirmed that the gas was PF ₅ and a large amount of HF. It was made to absorb in ultrapure water for 6 hours, the P content of the absorbing solution was measured, and the generated PF ₅ gas weight was calculated. As a result, the weight of PF ₅ gas was 43 g, and the yield was 62%. Further, the metal impurity concentration of the absorbing water was analyzed using ICP-MS, it was confirmed metal impurity concentration in PF ₅ gas is 0.5 ppm by weight or less.

(Example 6)
Cesium hexafluorophosphate (CsPF ₆ ) 1.5 kg, lithium fluoride (LiF) 140 g and anhydrous hydrogen fluoride (HF) 18 kg together with a rotor are placed in a 20 L-PTFE reactor, and a SUS316 reflux tower (20 mmφ × 2 m) Connected to. Separately, 210 g of silver fluoride (AgF) and 500 g of anhydrous HF were dissolved in a 3 L-PFA reaction tank together with a rotor, the outlet of the reflux tower was connected to the 3 L-PFA reaction tank, and the generated gas was in the 3 L-PFA reaction tank. I was able to absorb it. The 20 L-PFA reaction tank was heated to 70 ° C. with a heating medium, and the 3 L-PFA reaction tank was cooled with an ice bath. The reflux tower was cooled with 0 ° C. brine. The two reaction vessels were each stirred.

Gradually, the temperature of the 20 L-PFA reactor rose and the internal temperature reached 23 ° C., and the reflux of HF started. At substantially the same time, the temperature of the 3L-PFA reactor rose from 0 ° C to 5 ° C. After carrying out the reaction for 6 hours, the 3 L-PFA reaction tank was removed from the reflux tower, cooled to −40 ° C., and crystallized for 48 hours. Next, the supernatant liquid of the 3L-PFA reaction tank was slowly withdrawn, and solid-liquid separation was performed. After separation, N ₂ was introduced into the bottle at 3 L / min and air-dried. Thereafter, drying was performed for 3 hours with a dryer at 85 ° C., and 395 g of crystals were obtained.

When the obtained crystal was analyzed by XRD, it was assigned to silver hexafluorophosphate (AgPF ₆ ). The water content was 30 ppm by weight or less, and the free hydrofluoric acid concentration was 50 ppm by weight or less. The moisture content was measured with a moisture meter, and the free hydrofluoric acid concentration was determined by titration with sodium hydroxide.

(Example 7)
In this example, phosphorus pentafluoride was manufactured using the manufacturing apparatus shown in FIG.

[Step I]
1.2 kg of acidic potassium fluoride (KHF ₂ ) was placed in a 10 L-PTFE reactor, and 5.25 kg of semiconductor grade 75% HF was slowly added while cooling in an ice bath. Further, 1.3 kg of 85% by weight phosphoric acid (H ₃ PO ₄ ) was added over 30 minutes. The mixture was stirred for 6 hours in a water bath at + 20 ° C. to carry out reaction and crystallization. Next, the obtained precipitate was separated by suction filtration. The recovered crystals were washed with water and then dried at 105 ° C. for 6 hours. The yield of the obtained crystal was 1.35 kg (yield 65%). Furthermore, when XRD measurement of the obtained crystal was performed, it was found to be KPF ₆ .

[Step II]
1.2 kg of KPF ₆ and ₆ kg of anhydrous hydrogen fluoride (HF) obtained above were placed in a 10 L-PTFE reaction tank together with a rotor, and connected to a reflux tower (20 mmφ × 2 m) made of SUS316. Furthermore, 95 g of LiF and 1200 g of anhydrous HF were separately dissolved in a 2 L-PTFE reaction tank together with a rotor. The outlet of the reflux tower was connected to a 2L-PTFE reaction tank so that the generated PF ₅ gas could be absorbed by the 2L-PTFE reaction tank. Furthermore, in order to absorb exhaust gas, a 3L-PTFE reaction tank was connected to the subsequent stage of the 2L-PTFE reactor. In this 3L-PTFE reaction vessel, a solution in which 50 g of KF. (HF) was dissolved in HF having a concentration of 50% by weight and a weight of 2 kg was used.

  The 10 L-PTFE reaction vessel was heated with a water bath at 85 ° C., and the 2 L-PTFE reaction vessel and the 3 L-PTFE reaction vessel were cooled with an ice bath. The reflux tower was cooled with 0 ° C. brine. Each of the three reaction vessels was stirred.

  Gradually, the temperature of the 10 L-PTFE reaction vessel gradually increased, the internal temperature reached 25 ° C., and the reflux of HF started. At the same time, the temperature of the 2L-PTFE reactor rose from 0 ° C. to 8 ° C., and the solution gradually became cloudy.

[Step III]
After the reaction was performed for 8 hours, the 2L-PTFE reaction vessel was removed from the reflux tower, and the mixture was stirred for 4 hours while cooling to -40 ° C. The obtained crystals were subjected to solid-liquid separation by filtration, and the obtained crystals were transferred to a 1 L-PFA container, and N ₂ was introduced at room temperature at a flow rate of 3 L / min for 4 hours and allowed to air dry. Thereafter, the 1 L-PFA container was dried at 85 ° C. for 3 hours, and 350 g of crystals could be obtained.

When the obtained crystal was analyzed, it was assigned to LiPF ₆ and had a water content of 50 ppm by weight or less and a free hydrofluoric acid concentration of 50 ppm by weight or less.

[Step IV]
Withdrawn liquid from 3L-PTFE reaction vessel was subjected to ion chromatography analysis, PF ₆ ^- ions were detected. This indicates that exhaust gas can be trapped and the trap liquid can be reused as a raw material.

[Step V]
Further, the 10 L-PTFE reaction tank after the reaction is removed from the reflux tower, the solution is concentrated with a water bath at 35 ° C., and a HF solution containing viscous KPF ₆ / KF · v (HF) (v ≧ 0) is recovered. did. This solution could be reused in Step I.

(Example 8)
20 kg of anhydrous hydrogen fluoride solution was placed in a fluororesin reaction tank connected to the bottom with a metering pump for extraction. While cooling this anhydrous hydrogen fluoride solution to 10 ° C., 1 kg of diphosphorus pentoxide was dissolved. Further, an anhydrous hydrogen fluoride solution in which diphosphorus pentoxide was dissolved was supplied to a phosphorus pentafluoride generation tank (made of fluororesin, capacity 10 L). The supply was quantitatively performed at a rate of 8 kg / hr. In addition, as the phosphorus pentafluoride generation tank, a tank in which a 0 ° C. condenser and a −50 ° C. cooler were connected in series was used. On the other hand, anhydrous hydrogen fluoride gas at 25 ° C. generated in a carrier gas generation tank was bubbled and supplied to the anhydrous hydrogen fluoride solution in the phosphorus pentafluoride generation tank. Anhydrous hydrogen fluoride gas was supplied at a rate of 40 kg / hr.

Further, in the phosphorus pentafluoride generation tank, the anhydrous hydrogen fluoride solution was extracted using a pump so that the liquid level of the anhydrous hydrogen fluoride solution was kept constant. The extraction speed was about 8 kg / hr. The liquid temperature of the condensate produced by the condensation by the condenser was 20 ° C., and this condensate was recycled as it was to the carrier gas generation tank. After 30 minutes, PF ₅ gas accompanied by a very small amount of HF was constantly generated from the outlet of the cooler at a rate of 5.5 g / min.

  Next, the following operation was performed using the apparatus shown in FIG. After charging 2603 mL of commercially available battery grade diethyl carbonate (water concentration 9 ppm by weight) into the first tank 2 and the second tank 6 made of fluororesin, circulating operation in each absorption tower and tank using the pumps 3 and 7 Started. At this time, the flow rates of the pump 3 and the pump 7 were both 1 L / min. Moreover, the 1st tank 2 and the 2nd tank 6 were made constant temperature of 20 degreeC using the 1st cooler 4 and the 2nd cooler 8, respectively.

  Subsequently, the phosphorus pentafluoride gas containing hydrogen fluoride was supplied to the bottom of the second absorption tower 5 at 5.5 g / min. After absorbing this phosphorus pentafluoride gas in the organic solvent for 2 minutes, lithium fluoride was started to be supplied to the second tank 6 at 1.13 g / min. Sixty minutes after starting the supply of lithium fluoride, the product started to be extracted at 44.9 ml / min. Simultaneously with the extraction of the product, the organic solvent is supplied to the first absorption tower 1 at 43.4 ml / min, and the supply destination of the liquid in the pump 3 is switched from the first absorption tower 1 to the second absorption tower 5. Driving.

  By continuously operating for 60 minutes, 2,947.5 g of the solution was continuously supplied to the deaeration tower 9, and the pressure was reduced by the air pump 12, whereby the phosphorus pentafluoride gas excessively dissolved in the solution was distilled off. . After the distillation, the solution was extracted from the third tank 10 to obtain 2,911.5 g of a lithium hexafluorophosphate solution. Further, the accompanying diethyl carbonate and HF were removed from the distilled phosphorus pentafluoride gas by the condenser 13. Thereafter, phosphorus pentafluoride gas was bubbled into and absorbed in an absorption solution containing a separately prepared diethyl carbonate solution.

  The diethyl carbonate solution of lithium hexafluorophosphate thus obtained had an insoluble component of 10 ppm by weight or less, a free acid of 10 ppm by weight or less, and a water content of 10 ppm by weight or less. Moreover, the obtained diethyl carbonate solution of lithium hexafluorophosphate was further depressurized at 40 ° C. to distill off the diethyl carbonate to obtain a white solid. As a result of XRD analysis of the white solid, it was assigned to lithium hexafluorophosphate.

Example 9
First, the same operation as in Example 8 was performed to generate PF ₅ gas containing a very small amount of HF. Next, the following operation was performed using the apparatus shown in FIG. After charging 2603 mL of commercially available battery grade diethyl carbonate (water concentration 9 ppm by weight) into the first tank 2 and the second tank 6 made of fluororesin, circulating operation in each absorption tower and tank using the pumps 3 and 7 Started. At this time, the flow rates of the pump 3 and the pump 7 were both 1 L / min. Moreover, the 1st tank 2 and the 2nd tank 6 were made constant temperature of 20 degreeC using the 1st cooler 4 and the 2nd cooler 8, respectively.

  Subsequently, the phosphorus pentafluoride gas containing hydrogen fluoride was supplied to the bottom of the second absorption tower 5 at 5.5 g / min. After absorbing this phosphorus pentafluoride gas in the organic solvent for 2 minutes, lithium fluoride was started to be supplied to the second tank 6 at 1.13 g / min. 80 minutes after the start of supply of lithium fluoride, the product started to be extracted at 35.9 ml / min. Simultaneously with the extraction of the product, the organic solvent is supplied to the first absorption tower 1 at 32.5 ml / min, and the supply destination of the liquid in the pump 3 is switched from the first absorption tower 1 to the second absorption tower 5. Driving.

  By continuous operation for 60 minutes, 2,380.4 g of the solution was continuously supplied to the deaeration tower 9, and the pressure was reduced by the air pump 12, whereby the phosphorus pentafluoride gas excessively dissolved in the solution was distilled off. . After the distillation, the solution was extracted from the third tank 10 to obtain 2,350.5 g of a lithium hexafluorophosphate solution. Further, the accompanying diethyl carbonate and HF were removed from the distilled phosphorus pentafluoride gas by the condenser 13. Thereafter, phosphorus pentafluoride gas was bubbled into and absorbed in an absorption solution containing a separately prepared diethyl carbonate solution.

  Further, 709.5 g of ethylene carbonate (moisture concentration of 7 ppm by weight) was added to 2,350.5 g of the obtained lithium carbonate hexafluorophosphate in diethyl carbonate solution to obtain a diethyl carbonate / ethylene carbonate solution of lithium hexafluorophosphate. Got. The insoluble component of the obtained solution was 10 ppm by weight or less, the free acid was 10 ppm by weight or less, and the water content was 10 ppm by weight or less.

  Next, using the solution thus obtained, a coin-type non-aqueous electrolyte lithium secondary battery shown in FIG. 4 was manufactured, and the performance as an electrolyte was evaluated by a charge / discharge test. Specifically, the procedure was as follows.

<Creation of negative electrode>
Natural graphite and binder polyvinylidene fluoride (PVdF) were mixed at a weight ratio of 9: 1, and N-methylpyrrolidone was added thereto to obtain a paste. This paste was uniformly applied onto a copper foil having a thickness of 22 μm using an electrode applicator. This was vacuum-dried at 120 ° C. for 8 hours, and a negative electrode 22 having a diameter of 16 mm was obtained with an electrode punching machine.

<Creation of positive electrode>
LiCoO ₂ powder, acetylene black as a conductive additive, and PVdF as a binder were mixed at a weight ratio of 90: 5: 5, and N-methylpyrrolidone was added to this mixture to obtain a paste. This paste was uniformly applied onto a copper foil having a thickness of 22 μm using an electrode applicator. This was vacuum-dried at 120 ° C. for 8 hours, and a positive electrode 21 having a diameter of 16 mm was obtained with an electrode punching machine.

<Creation of coin-type non-aqueous electrolyte lithium ion secondary battery>
After placing the positive electrode 21 on the bottom surface of the positive electrode can 24 and placing the porous porous separator 23 thereon, the non-aqueous electrolyte prepared in Example 8 was injected and the gasket 26 was inserted. After that, the negative electrode 22, the spacer 27, the spring 28, and the negative electrode can 25 are sequentially placed on the separator 23, and the opening of the positive electrode can 24 is bent inward using a coin type battery caulking machine. Sealed to prepare a non-aqueous electrolyte lithium ion secondary battery. Subsequently, charging was performed at a constant current of 0.4 mA. When the voltage reached 4.1 V, charging was performed at a constant voltage of 4.1 V for 1 hour. Discharging was performed at a constant current of 1.0 mA, and discharging was performed until the voltage reached 3.0V. When the voltage reached 3.0 V, 3.0 V was maintained for 1 hour, and a charge / discharge test was performed by a charge / discharge cycle. As a result, the charge / discharge efficiency was almost 100%. When charge / discharge was repeated 150 cycles, the charge capacity did not change.

(Example 10)
First, the same operation as in Example 8 was performed to generate PF ₅ gas containing a very small amount of HF. Next, the following operation was performed using the apparatus shown in FIG. After charging 2603 mL of commercially available battery grade diethyl carbonate (water concentration 550 ppm by weight) mixed with water into the first tank 2 and the second tank 6 made of fluororesin, each of the absorption towers and tanks using the pumps 3 and 7 Circulation operation at has started. At this time, the flow rates of the pump 3 and the pump 7 were both 1 L / min. Moreover, the 1st tank 2 and the 2nd tank 6 were made constant temperature of 20 degreeC using the 1st cooler 4 and the 2nd cooler 8, respectively.

  Subsequently, the phosphorus pentafluoride gas containing hydrogen fluoride was supplied to the bottom of the second absorption tower 5 at 5.5 g / min. After absorbing this phosphorus pentafluoride gas in the organic solvent for 2 minutes, lithium fluoride was started to be supplied to the second tank 6 at 1.13 g / min. Sixty minutes after starting the supply of lithium fluoride, the product started to be extracted at 44.9 ml / min. Simultaneously with the extraction of the product, the organic solvent is supplied to the first absorption tower 1 at 43.4 ml / min, and the supply destination of the liquid in the pump 3 is switched from the first absorption tower 1 to the second absorption tower 5. Driving.

  By continuously operating for 60 minutes, 2,947.5 g of the solution was continuously supplied to the deaeration tower 9, and the pressure was reduced by the air pump 12, whereby the phosphorus pentafluoride gas excessively dissolved in the solution was distilled off. . After the distillation, the solution was extracted from the third tank 10 to obtain 2,911.5 g of a lithium hexafluorophosphate solution. Further, the accompanying diethyl carbonate and HF were removed from the distilled phosphorus pentafluoride gas by the condenser 13. Thereafter, phosphorus pentafluoride gas was bubbled into and absorbed in an absorption solution containing a separately prepared diethyl carbonate solution.

  The insoluble component of the lithium hexafluorophosphate diethyl carbonate solution thus obtained was 82 ppm by weight, and the free acid was 380 ppm by weight.

  Next, in the same manner as in Example 9, a coin-type non-aqueous electrolyte lithium ion secondary battery was produced using a diethyl carbonate solution of lithium hexafluorophosphate. Further, in the same manner as in Example 7, the performance as an electrolytic solution was evaluated by a charge / discharge test. As a result, the charging / discharging efficiency was 80%, and when charging / discharging was repeated 150 cycles, a decrease in charging capacity could be suppressed to about 20%.

(Comparative Example 1)
200 g of KPF ₆ and 200 g of anhydrous HF were placed in a 5 L-PFA reaction vessel together with a rotor, and connected to a reflux tower (20 mmφ × 2 m) made of SUS316. Furthermore, it connected to the absorption tank which put the pure water with the PFA piping from the reflux tower upper part. The reflux tower was cooled with 0 ° C. brine while the PFA reactor was kept at 15 ° C. with an ice bath. Further, the reaction solution was stirred with a magnetic stirrer. The temperature inside the reaction vessel was 14.2 ° C., and no boiling of the reaction solution occurred in this state, and no reflux was observed.

After 4 hours, the absorption liquid in the absorption tank was analyzed for P by ICP-AES, and the generated PF ₅ gas weight was determined to be 0 g and was not generated at all.

(Comparative Example 2)
In Comparative Example 2, lithium hexafluorophosphate was produced using the apparatus shown in FIG.

  First, 2603 mL of commercially available battery grade diethyl carbonate (moisture concentration 9 ppm by weight) is charged into the first tank 2 and the second tank 6 made of fluororesin, respectively, and then pumps 3 and 7 are used for each absorption tower and tank. Circulation operation started. At this time, the flow rates of the pump 3 and the pump 7 were both 1 L / min. Moreover, the 1st tank 2 and the 2nd tank 6 were made constant temperature of 20 degreeC using the 1st cooler 4 and the 2nd cooler 8, respectively.

  Next, the HF-containing phosphorus pentafluoride gas obtained in Example 7 was supplied to the bottom of the second absorption tower 5 at 5.5 g / min. After absorbing this phosphorus pentafluoride gas in the organic solvent for 2 minutes, lithium fluoride was started to be supplied to the second tank 6 at 1.34 g / min. Sixty minutes after the start of the supply of lithium fluoride, the second absorption tower 5 was clogged with slurry-like lithium fluoride, making it difficult to operate.

(Comparative Example 3)
This example is an example showing a conventional example described in Patent Document 4.

790 g (9.4 mol) of polyphosphoric acid was added to a 5 L-PFA reaction vessel, and 1235 g (61.7 mol) of anhydrous HF was added with stirring while being kept at 25 ° C. by cooling. Further, 150 g of anhydrous HF was added to obtain a 25% excess of HF in the solution. The reaction vessel was connected to a reflux tower (cooled to −50 ° C.), the temperature was kept at 32 ° C., and 1781 g (14.5 mol) of fuming sulfuric acid (65% SO ₃ ) was added over 3 hours. The generated gas was analyzed by FTIR. As a result, POF ₃ contained a very small amount of PF ₅ .

(result)
As is clear from Examples 1 to 5, a carrier gas is brought into contact with various raw materials containing phosphorus atoms and fluorine atoms, or with various raw materials containing phosphorus atoms, whereby high-grade five fluorine atoms are contained in the carrier gas. Phosphorus bromide could be extracted and separated. As a result, it was confirmed that high-quality phosphorus pentafluoride could be produced without generating a large amount of by-product gas as compared with the conventional method.

  Further, as is clear from Examples 7 to 10, as a result of producing lithium hexafluorophosphate using phosphorus pentafluoride gas obtained by the production method of the present invention as a raw material, high quality with low moisture and high purity was obtained. Lithium hexafluorophosphate could be produced by a relatively easy and simple method. Furthermore, as a result of applying lithium hexafluorophosphate obtained by the method to an electrolyte of a coin-type non-aqueous electrolyte lithium ion secondary battery, lithium ions that suppress a decrease in charge capacity even after repeated charge and discharge It was confirmed that a secondary battery was obtained.

  According to the present invention, it is possible to produce high-quality phosphorus pentafluoride at low cost, with low moisture concentration and high purity, using low-quality raw materials, without requiring complicated processing operations and special equipment. In addition, by using the high-quality phosphorus pentafluoride obtained by the present invention as a raw material, an inexpensive and high-quality hexafluorophosphate can be easily produced without using a complicated apparatus. Furthermore, the high-quality hexafluorophosphate obtained by the present invention can be suitably used as an electrolyte solution for a storage element, a catalyst for an organic synthesis reaction, and the like. In particular, among hexafluorophosphates, lithium hexafluorophosphate, sodium hexafluorophosphate, potassium hexafluorophosphate, etc. are electrolytes for power storage elements for personal computers, mobile phones, hybrid vehicles, etc. Can be used as Further, silver hexafluorophosphate is used as a counter ion for generating an acid necessary for the initiation / proliferation reaction of photopolymerization. Furthermore, ammonium hexafluorophosphate is useful as a raw material used in the production of pharmaceutical intermediates.

DESCRIPTION OF SYMBOLS 1 1st absorption tower 2 1st tank 3 Pump 4 Cooler 5 2nd absorption tower 6 2nd tank 7 Pump 8 Cooler 9 Deaeration tower 10 3rd tank 12 Air pump 13 Condenser 21 Positive electrode 22 Negative electrode 23 Porous separator 24 Positive electrode can 25 Negative electrode can 26 Gasket 27 Spacer 28 Spring

Claims (12)

By bringing a carrier gas containing hydrogen fluoride gas into contact with a contact object containing a phosphorus atom-containing substance containing phosphorus atoms, phosphorus pentafluoride is extracted and separated in the carrier gas,
The phosphorus atom-containing material is white phosphorus, red phosphorus, black phosphorus, phosphorus trichloride (PCl ₃ ), phosphorus tribromide (PBr ₃ ), phosphine (PH ₃ ), phosphorous acid , HPF ₆ , LiPF ₆ , NaPF. ₆ , KPF ₆ , RbPF ₆ , CsPF ₆ , NH ₄ PF ₆ , AgPF ₆ , Mg (PF ₆ ) ₂ , Ca (PF ₆ ) ₂ , Ba (PF ₆ ) ₂ , Zn (PF ₆ ) ₂ , Cu (PF ₆ ) A method for producing phosphorus pentafluoride, comprising at least one selected from the group consisting of ₂ , Pb (PF ₆ ) ₂ , Al (PF ₆ ) ₃ and Fe (PF ₆ ) ₃ . The said contact object in after contact with at least the carrier gas, there is a polyatomic ions containing phosphorus atoms and fluorine atoms, the manufacturing method of phosphorus pentafluoride according to claim 1. The method for producing phosphorus pentafluoride according to claim 2, wherein the polyatomic ions include PF ₆ ^- ions.   The manufacturing method of the phosphorus pentafluoride of any one of Claims 1-3 which reuses the said contact target object which generate | occur | produced the said phosphorus pentafluoride. 5. Phosphorus pentafluoride obtained by the method for producing phosphorus pentafluoride according to claim 1, and fluoride are reacted according to the following chemical reaction formula to obtain hexafluorophosphate. A method for producing hexafluorophosphate, which is produced.

The reaction between phosphorus pentafluoride and fluoride is
A first step of dissolving phosphorus pentafluoride gas in a solvent;
A second step of adding a stoichiometrically equivalent or less fluoride to the phosphorus pentafluoride to the solvent to produce a solution of hexafluorophosphate;
At least a third step of dissolving phosphorus pentafluoride gas in the hexafluorophosphate solution instead of the solvent by circulating the hexafluorophosphate solution in the first step. Item 6. A method for producing a hexafluorophosphate according to Item 5.   The method for producing hexafluorophosphate according to claim 6, wherein a hydrogen fluoride solution is used as the solvent.   The method for producing hexafluorophosphate according to claim 6, wherein an organic solvent is used as the solvent.   The method for producing hexafluorophosphate according to claim 8, wherein the organic solvent contains at least one of a non-aqueous organic solvent and a non-aqueous ionic liquid.   The method for producing hexafluorophosphate according to any one of claims 6 to 9, wherein a solvent having a water concentration of 100 ppm by weight or less is used.   The method for producing hexafluorophosphate according to any one of claims 6 to 10, wherein the first step and the third step are performed using an absorption tower. The method for producing a hexafluorophosphate according to any one of claims 6 to 11, wherein an unreacted phosphorus pentafluoride gas in the phosphorus pentafluoride gas is absorbed and recovered by an absorption liquid and reused. .

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