Method for producing alkali metal halide and method for producing halide

Abstract

To provide a method for producing an alkali metal halide by decomposing a halogen-containing organic compound in relatively simple and mild conditions, and a method for producing a halide.SOLUTION: A method for producing an alkali metal halide comprises a step of reacting a liquid or solid halogen-containing organic compound with a molten alkali metal hydroxide.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing an alkali metal halide and a method for producing a halide. [Background technology]

[0002] The C-F bond has the following characteristics: (1) very strong bond energy; (2) small polarizability. As a result, organic fluorine compounds with C-F bonds have extremely weak intermolecular forces. Furthermore, they can exhibit unique heat resistance, flame resistance, chemical resistance, weather resistance, non-adhesiveness, water repellency, low refractive index, low dielectric constant, and other properties not seen in other organic compounds. These properties have been highly evaluated, and organic fluorine compounds are used for a wide variety of purposes in a wide range of fields.

[0003] However, when organic fluorine compounds are considered as a target for waste treatment, they have a problem that decomposition and incineration are not easily progressed due to the above-mentioned chemical characteristics. Furthermore, when organic fluorine compounds are considered as a target for chemical recycling, severe decomposition conditions are required for decomposition of the organic fluorine compounds.

[0004] To address such problems, Patent Document 1 discloses a method in which an aqueous solution of an excess of an oxidizing agent (potassium permanganate or hydrogen peroxide) relative to an organic fluorine compound is placed in a high-temperature / pressurized sealed container, and the organic fluorine compound is reacted at 250 to 350°C for 6 to 24 hours to decompose the organic fluorine compound into fluoride ions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-104578 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the method of Patent Document 1 requires (1) subcritical water; (2) an excess of an oxidizing agent; and (3) a long reaction time, and there is room for further improvement.

[0007] The above problem is not limited to organic fluorine compounds. Organic compounds containing halogens other than fluorine, such as chlorine and bromine (hereinafter, halogen-containing organic compounds), are also known to be thermally stable and difficult to treat, such as by decomposition or incineration. Many of the conventional methods for decomposing such compounds require harsh conditions, leaving room for improvement.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing an alkali metal halide by decomposing a halogen-containing organic compound under relatively simple and mild conditions, and a method for producing a halide. [Means for solving the problem]

[0009] In order to solve the above problems, one aspect of the present invention includes the following aspects.

[0010] [1] A method for producing an alkali metal halide, comprising the step of reacting a liquid or solid halogen-containing organic compound with a molten alkali metal hydroxide.

[0011] [2] A method for producing an alkali metal halide according to [1], comprising the steps of: mixing the alkali metal hydroxide with the halogen-containing organic compound to obtain a mixture, and heating the mixture at a temperature equal to or higher than the melting point of the alkali metal hydroxide to melt the alkali metal hydroxide, in that order, prior to the reacting step.

[0012] [3] The method for producing an alkali metal halide according to [1] or [2], wherein the halogen-containing organic compound is a fluorine-containing resin.

[0013] [4] A method for producing a halide, comprising the steps of: dissolving an alkali metal halide produced by the method according to any one of [1] to [3] in a polar solvent; and reacting the solution in which halide ions derived from the alkali metal halide are dissolved with a solution containing ions of an alkaline earth metal.

[0014] [5] The method for producing a halide according to [4], wherein the halogen-containing organic compound is a fluorine-containing resin, and the alkaline earth metal ion is a calcium ion. Effect of the Invention

[0015] According to the present invention, there are provided a method for producing an alkali metal halide by decomposing a halogen-containing organic compound under relatively simple and mild conditions, and a method for producing a halide. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 shows the results of powder X-ray diffraction analysis of the precipitate obtained in Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, a method for producing an alkali metal halide and a method for producing a halide according to an embodiment of the present invention will be described.

[0018] <Method of producing alkali metal halide> (Overview of the formation of alkali metal halides) In one embodiment, a method for producing an alkali metal halide includes reacting a halogen-containing organic compound with a molten alkali metal hydroxide.

[0019] It is conventionally believed that the following reaction occurs in molten alkali metal hydroxide:

[0020] First, hydroxide ions are converted into oxide ions O in the molten alkali metal hydroxide.2- is generated.

[0021] [ka]

[0022] Furthermore, the generated oxide ions O 2- reacts with oxygen in the air to produce peroxide ions, O2 2- and superoxide ion O2 - Form.

[0023] [ka]

[0024] [ka]

[0025] It is believed that the extremely strong oxidizing power of the oxide ions generated from the molten alkali metal hydroxide and the peroxide ions and superoxide ions generated by further oxidizing the oxide ions function sufficiently as oxidizing agents in the decomposition of halogen-containing organic compounds.

[0026] It is believed that the halogen-containing organic compounds are decomposed into halide ions and carbon dioxide by oxide ions, peroxide ions, and superoxide ions that function as oxidizing agents. The resulting halide ions are bound to alkali metal ions derived from the alkali metal hydroxide and fixed as water-soluble alkali metal halides. It is believed that the alkali metal halides are produced by the above-mentioned mechanism, but the present invention is not limited to the above-mentioned assumed mechanism.

[0027] When the reaction product (alkali metal halide) obtained by reacting a halogen-containing organic compound with an alkali metal hydroxide is allowed to stand until it reaches room temperature, a mixture containing the solid reaction product (alkali metal halide) can be obtained.

[0028] In the method for producing an alkali metal halide, the melting point of the alkali metal hydroxide may be lower or higher than the melting point of the halogen-containing organic compound. The method for measuring the melting point of the alkali metal hydroxide will be described later.

[0029] In the method for producing an alkali metal halide, a mixture may be obtained by first mixing a solid alkali metal hydroxide that has not been melted with a halogen-containing organic compound. The mixture may then be heated to a temperature equal to or higher than the melting point of the alkali metal hydroxide to melt the alkali metal hydroxide, and the molten alkali metal hydroxide may be reacted with the halogen-containing organic compound. By producing an alkali metal halide as described above, it may be possible to produce an alkali metal halide with a higher yield than by melting an alkali metal hydroxide and then mixing the halogen-containing organic compound.

[0030] (Reaction conditions of alkali metal hydroxide and halogen-containing organic compound) The reaction temperature at which the molten alkali metal hydroxide and the halogen-containing organic compound are heated to react with each other is equal to or higher than the melting point of the alkali metal hydroxide used, and may be, for example, 170°C or higher, 190°C or higher, 250°C or higher, 300°C or higher, 350°C or higher, 400°C or higher, 450°C or higher, or 500°C or higher. The reaction proceeds more easily at higher temperatures, so the upper limit of the reaction temperature is not limited, but is, for example, 600°C or lower, 550°C or lower, or 500°C or lower depending on the performance of the heater used. Here, the upper limit of the reaction temperature is preferably lower from the viewpoints of ease of operation, low energy consumption, etc.

[0031] The reaction between the molten alkali metal hydroxide and the halogen-containing organic compound may be carried out in a vessel open to the atmosphere, such as a crucible. Known heating means may be used, such as an electric furnace.

[0032] The reaction time for heating the molten alkali metal hydroxide and the halogen-containing organic compound to react with each other is, for example, 0.5 hours or more and 3 hours or less. The upper and lower limits of the reaction time may be selected from the group consisting of 1 hour, 1.5 hours, 2 hours, and 2.5 hours.

[0033] As long as the relationship that the lower limit is smaller than the upper limit is satisfied, for example, "1.5 hours" may be selected as the upper limit and the reaction time may be set to 1 hour or more and 1.5 hours or less. Also, "1.5 hours" may be selected as the lower limit and the reaction time may be set to 1.5 hours or more and 2 hours or less.

[0034] Here, the reaction time refers to the time to maintain the reaction temperature after the set reaction temperature is reached. In addition, when the reaction is carried out by increasing the temperature in multiple stages (for example, in two stages), the time to increase the temperature to the second stage after the reaction at the first stage temperature is not considered as the reaction time.

[0035] (alkali metal hydroxides) Examples of the alkali metal hydroxides used include sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, and cesium hydroxide. Taking into consideration versatility, high practicality, and melting point, sodium hydroxide or potassium hydroxide may be used. Sodium hydroxide or potassium hydroxide may be used alone. Alternatively, a eutectic of two or more alkali metal hydroxides may be used. The method for measuring the melting point of the alkali metal hydroxide will be described later.

[0036] An example of a eutectic containing two or more alkali metal hydroxides is a eutectic of sodium hydroxide and potassium hydroxide. The mixing ratio of the two or more alkali metal hydroxides in the eutectic is not particularly limited.

[0037] The melting points of sodium hydroxide and potassium hydroxide are 318°C and 360°C, respectively. It is known that when a eutectic of sodium hydroxide and potassium hydroxide is formed in a molar ratio of 1:1, the melting point of the eutectic is 170°C (J. Am. Chem. Soc., 110, 5214, 1988). It is also known that when a eutectic of sodium hydroxide and potassium hydroxide is formed in a molar ratio of 49:51, the melting point of the eutectic is 190°C (Kotsu Butsuri, 45(8), 49, 2008).

[0038] When sodium hydroxide is used alone, the reaction temperature is, for example, 350°C or more and 600°C or less. The upper and lower limit values ​​of the reaction temperature may be a combination of one or two selected from the group consisting of 400°C, 450°C, 500°C, and 550°C. As long as the relationship that the lower limit value is smaller than the upper limit value is satisfied, for example, "400°C" may be selected as the upper limit value and the reaction temperature may be 350°C or more and 400°C or less. Also, "400°C" may be selected as the lower limit value and the reaction temperature may be 400°C or more and 600°C or less.

[0039] When potassium hydroxide is used alone, the reaction temperature is, for example, 400°C or more and 600°C or less. The upper and lower limit values ​​of the reaction temperature may be a combination of one or two selected from the group consisting of 450°C, 500°C, and 550°C. As long as the relationship that the lower limit value is smaller than the upper limit value is satisfied, for example, "450°C" may be selected as the upper limit value and the reaction temperature may be 400°C or more and 450°C or less. Also, "450°C" may be selected as the lower limit value and the reaction temperature may be 450°C or more and 600°C or less.

[0040] In addition, when a eutectic of sodium hydroxide and potassium hydroxide is used, the reaction temperature is, for example, 170°C or more and 600°C or less. The upper limit and lower limit of the reaction temperature may be one or two selected from the group consisting of 190°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, and 550°C. As long as the relationship that the lower limit is smaller than the upper limit is satisfied, for example, "190°C" may be selected as the upper limit, and the reaction temperature may be 170°C or more and 190°C or less. In addition, "190°C" may be selected as the lower limit, and the reaction temperature may be 190°C or more and 600°C or less.

[0041] (Measuring method for melting point of alkali metal hydroxide) The melting point of the alkali metal hydroxide may be a literature value known from literature, etc., or may be an actually measured value. Regarding the measurement method, the melting point can be measured, for example, by using a simple melting point measurement device (ATM-01, AS ONE Corporation).

[0042] (Halogen-containing organic compounds) In this specification, the halogen-containing organic compound to be decomposed is a compound containing a halogen atom in the molecule. The decomposition target may be one type of compound or a mixture of multiple compounds. The halogen-containing organic compound applicable to the manufacturing method of this embodiment is a compound containing at least one halogen atom in the molecule. The compound may be a low molecular weight compound or a high molecular weight compound. Examples of halogen include fluorine, chlorine, bromine, and iodine.

[0043] Examples of halogen-containing organic low molecular weight compounds include polychlorinated biphenyls. Examples of halogen-containing organic polymer compounds include halogen-containing resins. The resins may be homopolymers or copolymers. Examples of halogen-containing resins include fluorine-containing resins, chlorine-containing resins, and bromine-containing resins.

[0044] Examples of fluorine-containing resins include polytetrafluoroethylene (PTFE) (melting point 327°C), polychlorotrifluoroethylene (PCTFE) (melting point 210°C), polyvinylidene fluoride (PVDF) (melting point 156°C to 170°C), and vinylidene fluoride-hexafluoropropylene copolymer (VDF-HFP) (melting point 116°C to 135°C).

[0045] Examples of chlorine-containing resins include polyvinyl chloride (-(CH2CHCl)n-) and polyvinylidene chloride (-(CH2Cl2)n-).

[0046] The halogen-containing organic compound to be decomposed may be liquid or solid. If the decomposition target is gas, it is not easy to mix with the alkali metal hydroxide. Considering the ease of handling the compound and the ease of decomposition treatment, it is preferable that the halogen-containing organic compound is liquid or solid. More preferably, the halogen-containing organic compound is solid. The decomposition target may be pulverized before the reaction. It is believed that pulverization increases the reaction efficiency.

[0047] According to the above process, an alkali metal halide can be produced. By heating an alkali metal hydroxide to a temperature equal to or higher than the melting point of the alkali metal hydroxide and maintaining it in a molten state, the molten alkali metal hydroxide can be used as a reactant for the halogen-containing organic compound to be decomposed, and at the same time, as a solvent for maintaining the reaction.

[0048] <Method of producing halide> (Overview of halide formation) In one embodiment, the method for producing a halide includes dissolving the alkali metal halide produced by the above-mentioned method for producing an alkali metal halide in a polar solvent, and then reacting the solution in which the halide ions are dissolved (i.e., the solution in which the alkali metal halide is dissolved) with a solution containing an alkaline earth metal ion. It is presumed that the alkaline earth metal ion and the halide ion are combined by the above-mentioned reaction to produce an alkaline earth metal halide.

[0049] The polar solvent for dissolving the halide ions is, for example, water. The amount of the polar solvent used for dissolution can be appropriately adjusted.

[0050] Before reacting the solution containing the halide ions with the solution containing the alkaline earth metal ions, the pH of the solution containing the halide ions may be adjusted. An example of a reagent for adjusting the pH is 0.1M (mol / L) nitric acid. The pH after the adjustment is preferably in the range of 6.0 to 7.0.

[0051] After adjusting the pH, the solution may be filtered through a glass filter or the like to remove solid impurities, and then the solution in which the halide ions are dissolved may be reacted with a solution containing alkaline earth metal ions.

[0052] The alkaline earth metal ions to be reacted are, for example, magnesium ions, calcium ions, and barium ions. The ions to be reacted are not limited to alkaline earth metal ions. If the ions to be reacted are ions that generate halides that are poorly soluble in water, the halides can be easily collected. The type of halogen contained in the decomposition target may be preliminarily confirmed, and the type of alkaline earth metal may be selected according to the confirmation results.

[0053] The reaction products containing the obtained halides can be identified using a powder X-ray diffractometer. The detected X-ray diffraction pattern can be compared with the JCPDS card in which the diffraction patterns of known substances are registered, allowing the obtained halides to be identified. The measurement conditions for identifying the reaction products using a powder X-ray diffractometer are described below.

[0054] The yield of the halide can be calculated by quantifying the content of the halide ions in the reaction product containing the obtained halide. The yield of the halide can be calculated from the content of the halide ions obtained by the measurement and a theoretical value based on the estimated reaction. The method for measuring the halide ions will be described later.

[0055] (Conditions for using powder X-ray diffraction equipment) The powder X-ray diffraction apparatus used is, for example, an X-ray diffraction apparatus RINT RAPID II (Rigak Co., Ltd.). The measurement conditions are, for example, a characteristic X-ray source of CuK α The voltage and current of the X-ray tube are 40 kV and 30 mA, respectively.

[0056] (Method for determining halide ions) The amount of halide ions can be determined, for example, by ion chromatography (JIS K0102.34.3). For fluoride ions, the amount of lanthanum-alizarin complexone absorptiometry (JIS K0102.34.1) can be determined.

[0057] According to the above steps, a halide can be produced.

[0058] <Examples of methods for producing alkali metal halides and halides> When the decomposition target used in the method for producing an alkali metal halide is a fluorine-containing resin, an alkali metal fluoride is produced as the alkali metal halide. When the alkali metal fluoride is dissolved in water, fluoride ions are generated.

[0059] The ions to be reacted with the generated fluoride ions are preferably calcium ions, and the solution containing calcium ions is preferably an aqueous calcium chloride solution.

[0060] By mixing an aqueous solution of an alkali metal fluoride with an aqueous solution of calcium chloride, fluoride ions and calcium ions are bonded to each other to obtain poorly soluble calcium fluoride.

[0061] According to the above-mentioned method for producing alkali metal halide and halide, halogen-containing organic compounds having bonds such as C-F bonds, which are stable and difficult to decompose, can be decomposed easily under milder conditions than before. Furthermore, the decomposed halogen can be fixed as an alkaline earth metal halide and can be reused as a halogen source.

[0062] In particular, for fluorine compounds, the production areas of calcium fluoride, the raw material, are limited. By using the above-mentioned method, calcium fluoride can be obtained simply and stably from fluorine-containing resins that have been discarded in the past.

[0063] Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. The configurations and combinations of the manufacturing methods shown in the above-described embodiment are merely examples, and various modifications can be made based on the design, specifications, etc., without departing from the spirit of the present invention. EXAMPLES

[0064] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the following, Examples 3, 4, 6, and 11 to 14 are considered as reference examples.

[0065] <Experiment 1> (method) The reagents used are as follows. The raw material polytetrafluoroethylene was polytetrafluoroethylene (bead-shaped, melting point 327°C, Sigma-Aldrich). The maximum diameter of the beads was approximately 2 mm. The alkali metal hydroxide was sodium hydroxide (granular, melting point 318°C, Fujifilm Wako Pure Chemical Industries, Ltd.) or potassium hydroxide (granular, melting point 360°C, Fujifilm Wako Pure Chemical Industries, Ltd.).

[0066] First, about 0.3 g (about 3 mmol) or about 0.5 g (about 5 mmol) of polytetrafluoroethylene and an alkali metal hydroxide were weighed into a magnetic crucible (capacity 30 ml) and placed in an electric furnace (small electric furnace (Hi-Cera Kiln) NHK-120H-II, Nitto). The electric furnace was then heated from room temperature to a predetermined reaction temperature, and the reaction was carried out at the predetermined reaction temperature for a certain reaction time. The heating rate was about 15°C / min.

[0067] The amounts of reagents used, the types of reagents, the molar ratio of PTFE to alkali metal hydroxide, the reaction temperature, and the reaction time are shown in Table 1.

[0068] It is believed that the alkali metal hydroxide melts due to heating, and the reaction shown in formula (1) below occurs. After the reaction time had elapsed, the heating was stopped, the lid of the electric furnace was opened, and the furnace was left to cool to room temperature.

[0069] [ka]

[0070] Next, the solid reaction product at room temperature was dissolved in distilled water to obtain a transparent aqueous solution, which was then adjusted to a pH value of 6.0 to 7.0 using 0.1 M (mol / L) nitric acid, and passed through a glass filter.

[0071] Next, an aqueous solution of calcium chloride was added dropwise to obtain a precipitate. The concentration of the aqueous calcium chloride solution was 0.1M (mol / L). It is estimated that the reaction of the following formula (2) occurs when the aqueous calcium hydroxide solution is added dropwise. "aq" indicates that the solution is an aqueous solution, and "s" indicates that the solution is a solid.

[0072] [ka]

[0073] The precipitate was then filtered off using a glass filter, washed with distilled water, and dried. The weight of the glass filter before use was defined as w0, and the weight of the glass filter including the precipitate after filtration and drying was defined as w. The difference between the weights, Δw=w-w0, was defined as the total weight of the precipitate.

[0074] The precipitate was analyzed using a powder X-ray diffractometer (RINT RAPID II, Rigaku Co., Ltd.) equipped with a curved imaging plate detector, and was confirmed to be calcium fluoride. α The voltage and current of the X-ray tube were set to 40 kV and 30 mA, respectively. The fluoride ion content in the precipitate was determined by Heisei Riken Co., Ltd. using an ultraviolet-visible spectrophotometer (UV-1800, Shimadzu Corporation) according to the lanthanum-alizarin complexone absorptiometry method (JIS K0102.34.1). It was assumed that the decomposition of polytetrafluoroethylene (PTFE) proceeded according to the above formulas (1) and (2), and the yield of calcium fluoride was calculated based on the stoichiometry.

[0075] In Example 1, 0.3 g (3.1 mmol) of PTFE and 2.0 g (51.2 mmol) of sodium hydroxide as an alkali metal hydroxide were used, and the molar ratio (MOH / C2F4) was 16.5. The reaction temperature was 500°C, and the reaction time was 3 hours. MOH refers to alkali metal hydroxide. C2F4 refers to PTFE.

[0076] Example 2 was the same as Example 1, except that 0.5 g (5.0 mmol) of PTFE and 3.3 g (81.6 mmol) of sodium hydroxide were used as the alkali metal hydroxide, and the molar ratio (MOH / C2F4) was 16.3.

[0077] Example 3 was the same as Example 1, except that 0.5 g (4.9 mmol) of PTFE and 4.4 g (78.7 mmol) of potassium hydroxide as the alkali metal hydroxide were used, the molar ratio was 16.1, and the reaction temperature was 450°C.

[0078] Example 4 was the same as Example 1, except that 0.5 g (5.1 mmol) of PTFE and 4.5 g (79.5 mmol) of potassium hydroxide as the alkali metal hydroxide were used, resulting in a molar ratio of 15.7.

[0079] (result) The yield of calcium fluoride is shown in Table 1. In Examples 1 to 4, calcium fluoride was obtained.

[0080] FIG. 1 shows the results of powder X-ray diffraction analysis of the precipitate obtained in Example 1. The X-ray diffraction pattern shown in FIG. 1 was compared with a JCPDS card in which the diffraction patterns of known substances are registered. As a result, the position and intensity of each peak matched those of JCPDS 35-816 (bars in the figure) in which calcium fluoride (fluorite) is registered, and the product obtained in Example 1 was identified as calcium fluoride. Furthermore, no peaks other than those of calcium fluoride were observed in this diffraction pattern. Therefore, it was revealed that the product obtained contains almost no impurities.

[0081] [Table 1]

[0082] <Experiment 2> (method) The procedure was the same as in Experiment 1, except that the alkali metal hydroxide was first heated to a set reaction temperature to melt it, and then approximately 0.5 g (approximately 5 mmol) of polytetrafluoroethylene was added to the molten alkali metal hydroxide and allowed to react for a certain reaction time.

[0083] The amounts of reagents used, the types of reagents, the molar ratio of PTFE to alkali metal hydroxide, the reaction temperature, and the reaction time are shown in Table 2.

[0084] In Example 5, 0.5 g (5.1 mmol) of PTFE and 3.2 g (81.0 mmol) of sodium hydroxide as an alkali metal hydroxide were used, resulting in a molar ratio of 16.0. The reaction temperature was 500° C., and the reaction time was 3 hours.

[0085] Example 6 was the same as Example 5, except that 0.5 g (5.1 mmol) of PTFE and 4.5 g (80.4 mmol) of potassium hydroxide as the alkali metal hydroxide were used, resulting in a molar ratio of 15.9.

[0086] (result) The yields of calcium fluoride are shown in Table 2. In Examples 5 and 6, calcium fluoride was obtained.

[0087] Compared with the results of Experiment 1, there was no significant difference in the yield of calcium fluoride. However, there was a tendency for calcium fluoride to be obtained in a higher yield when polytetrafluoroethylene and an alkali metal hydroxide were mixed and then heated to melt the alkali metal hydroxide (Experiment 1).

[0088] [Table 2]

[0089] <Experiment 3> In experiment 3, the reaction time was examined when producing alkali metal fluorides and calcium fluoride using polytetrafluoroethylene as a raw material.

[0090] (method) The same procedure as in Experiment 1 was followed except that the reaction time after the reaction temperature reached 500°C was changed to examine the effect on the yield. The reaction time was examined from 0.5 hours to 3 hours.

[0091] The amounts of reagents used, the types of reagents, the molar ratio of PTFE to alkali metal hydroxide, the reaction temperature, and the reaction time are shown in Table 3.

[0092] In Example 7, 0.5 g (5.0 mmol) of PTFE and 3.2 g (80.4 mmol) of sodium hydroxide as an alkali metal hydroxide were used, resulting in a molar ratio of 16.0. The reaction temperature was 500° C., and the reaction time was 0.5 hours.

[0093] Example 8 was the same as Example 7, except that 0.5 g (5.1 mmol) of PTFE and 3.3 g (81.9 mmol) of sodium hydroxide as the alkali metal hydroxide were used, the molar ratio was 16.1, and the reaction time was 1 hour.

[0094] Example 9 was the same as Example 7, except that 0.5 g (5.0 mmol) of PTFE and 3.3 g (81.6 mmol) of sodium hydroxide as the alkali metal hydroxide were used, resulting in a molar ratio of 16.3, and the reaction time was 2 hours.

[0095] Example 10 was the same as Example 7, except that 0.5 g (5.0 mmol) of PTFE and 3.3 g (81.6 mmol) of sodium hydroxide as the alkali metal hydroxide were used, the molar ratio was 16.3, and the reaction time was 3 hours.

[0096] Example 11 was the same as Example 7, except that 0.5 g (5.0 mmol) of PTFE and 4.5 g (80.4 mmol) of potassium hydroxide as the alkali metal hydroxide were used, resulting in a molar ratio of 16.0.

[0097] Example 12 was the same as Example 7, except that 0.5 g (5.0 mmol) of PTFE and 4.5 g (80.0 mmol) of potassium hydroxide as the alkali metal hydroxide were used, the molar ratio was 15.8, and the reaction time was 1 hour.

[0098] Example 13 was the same as Example 7, except that 0.5 g (5.0 mmol) of PTFE and 4.5 g (80.7 mmol) of potassium hydroxide as the alkali metal hydroxide were used, the molar ratio was 16.1, and the reaction time was 2 hours.

[0099] Example 14 was the same as Example 7, except that 0.5 g (5.1 mmol) of PTFE and 4.5 g (79.5 mmol) of potassium hydroxide as the alkali metal hydroxide were used, the molar ratio was 15.7, and the reaction time was 3 hours.

[0100] (result) The yield of calcium fluoride is shown in Table 3. Calcium fluoride was obtained in Examples 7 to 14. It was confirmed that, regardless of the type of alkali metal hydroxide, the longer the reaction time, the higher the yield tended to be.

[0101] [Table 3]

[0102] <Test 4> In experiment 4, the production of alkali metal fluorides and calcium fluoride was investigated using various fluorine-containing resins as raw materials.

[0103] (method) The same procedure as in Experiment 1 was repeated except that various amounts of various fluororesins were used as raw materials and a eutectic of sodium hydroxide and potassium hydroxide was also used as the alkali metal hydroxide.

[0104] The amounts of reagents used, the types of reagents, the molar ratio of the fluororesin to the raw material polymer, the reaction temperature, and the reaction time are shown in Table 4.

[0105] In Example 15, 0.5 g (5.0 mmol) of PTFE was used as the raw material, and 3.3 g (81.6 mmol) of sodium hydroxide was used as the alkali metal hydroxide, resulting in a molar ratio of 16.3. The reaction temperature was 500° C., and the reaction time was 3 hours.

[0106] In Example 16, 0.4 g (3.0 mmol) of PCTFE was used as the raw material, and 2.5 g (62.1 mmol) of sodium hydroxide was used as the alkali metal hydroxide, resulting in a molar ratio of 20.6. The reaction temperature was 350° C., and the reaction time was 3 hours.

[0107] In Example 17, 0.6 g (5.0 mmol) of PCTFE was used as the raw material, and a eutectic of sodium hydroxide and potassium hydroxide in a molar ratio of approximately 1:1 (2.1 g (53.0 mmol) of sodium hydroxide and 2.9 g (51.5 mmol) of potassium hydroxide) was used as the alkali metal hydroxide, resulting in a molar ratio of 20.8. The reaction temperatures were 190°C and 300°C, and the reaction times were 0.5 hours and 3 hours. In detail, the mixture was heated at 190°C for 30 minutes, and then heated at 300°C for 3 hours. The heating rate from 190°C to 300°C was also about 15°C / min.

[0108] In Example 18, 0.7 g (10.3 mmol) of PVDF was used as the raw material, and 2.5 g (62.5 mmol) of sodium hydroxide was used as the alkali metal hydroxide, resulting in a molar ratio of 6.1. The reaction temperature was 400° C., and the reaction time was 3 hours.

[0109] In Example 19, 1.07 g of VDF-HFP was used as the raw material, and 3.3 g (82.1 mmol) of sodium hydroxide was used as the alkali metal hydroxide. The reaction temperature was 400° C., and the reaction time was 3 hours.

[0110] In Example 20, 1.08 g of VDF-HFP was used as the raw material, and a eutectic of sodium hydroxide and potassium hydroxide in a molar ratio of approximately 1:1 (sodium hydroxide 2.2 g (53.9 mmol) and potassium hydroxide 2.9 g (51.8 mmol)) was used as the alkali metal hydroxide. The reaction temperature was 250° C., and the reaction time was 3 hours.

[0111] (result) The yields of calcium fluoride are shown in Table 4. Calcium fluoride was obtained in Examples 15 to 20. When VDF-HFP was used as the raw material, the yield could not be calculated because the composition of the VDF-HFP used was unknown, but 1.13 g (Example 19) and 0.63 g (Example 20) of calcium fluoride were obtained.

[0112] [Table 4]

[0113] According to the above-mentioned method, a halogen-containing organic compound can be decomposed relatively simply and under mild conditions to produce an alkali metal halide and a halide.

Claims

1. The method includes reacting a liquid or solid halogen-containing organic compound with a molten alkali metal hydroxide, Prior to the reacting step, mixing the unmelted solid alkali metal hydroxide with the halogen-containing organic compound to obtain a mixture; and heating the mixture at a temperature equal to or higher than the melting point of the alkali metal hydroxide to melt the alkali metal hydroxide in an open-to-air container, The method for producing an alkali metal halide, wherein the alkali metal hydroxide is sodium hydroxide.

2. 2. The method for producing an alkali metal halide according to claim 1, wherein the halogen-containing organic compound is a fluorine-containing resin.

3. A step of dissolving the alkali metal halide produced by the method according to claim 1 or 2 in water; reacting an aqueous solution having dissolved therein halide ions derived from the alkali metal halide with an aqueous solution containing ions of an alkaline earth metal.

4. the halogen-containing organic compound is a fluorine-containing resin, The method for producing a halide according to claim 3, wherein the alkaline earth metal ion is a calcium ion.

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