Method for producing halogenated alkene and method for producing silicon tetrafluoride

Abstract

This method for producing a halogenated alkene comprises converting a fluorine-containing halogenated C2-4 alkane into a fluorine-containing halogenated C2-4 alkene in a gas phase in the presence of silicon oxide particles and a fluorine-containing alkali metal salt.

Description

Method for producing alkene halides, and method for producing silicon tetrafluoride 【0001】 This disclosure relates to a method for producing alkene halides and a method for producing silicon tetrafluoride. 【0002】 In recent years, alkenes (hydrofluoroolefins) have attracted attention as compounds with a low global warming potential. 【0003】 For example, Patent Document 1 describes a method for producing hydrofluoroolefins in which hydrofluorocarbons are converted to hydrofluoroolefins in the presence of a fluorine-containing compound having a standard boiling point higher than that of the target hydrofluoroolefin. The reaction step of this production method includes a step of contacting the hydrofluorocarbon with a catalyst. Specifically, the catalyst is alumina (Al ２ O ３ ) is used. In addition, perfluoroolefins such as tetrafluoroethylene are compounds that are widely used as monomers for fluorine-containing polymers. 【0004】 International Publication No. 2017 / 104829 【0005】 However, when hydrofluoroolefins are produced by the dehydrofluoridation reaction of hydrofluorocarbons using alumina as described in Patent Document 1, the alumina deteriorates over time due to the generated hydrogen fluoride, and the amount of hydrofluoroolefin produced decreases over time. Furthermore, Patent Document 1 does not describe the production of perfluoroolefins. 【0006】 Therefore, when investigating methods for producing halogenated alkenes (including hydrofluoroolefins and perfluoroolefins) using reagents other than alumina, it was found that depending on the type of reagent, the properties may change over time, preventing the original powder state from being maintained and potentially causing fluctuations in the reaction conditions. The objective of one embodiment of this disclosure is to provide a method for producing halogenated alkenes in which the powder state of the reagent can be maintained throughout the reaction process. 【0007】The present disclosure includes the following aspects. <1> A method for producing a halogenated alkene, comprising converting a halogenated alkane having 2 to 4 carbon atoms and containing fluorine atoms into a halogenated alkene having 2 to 4 carbon atoms and containing fluorine atoms in the gas phase in the presence of silicon oxide particles and a fluorine-containing alkali metal salt. <2> The method for producing a halogenated alkene according to <1>, wherein the conversion is carried out in an atmosphere having an oxygen content of 10,000 mass ppm or less. <3> The method for producing a halogenated alkene according to <1> or <2>, wherein the fluorine-containing alkali metal salt has a thermal decomposition temperature of 100°C or higher. <4> The method for producing a halogenated alkene according to any one of <1> to <3>, wherein the fluorine-containing alkali metal salt has a melting point of 400°C or higher. <5> Before the conversion reaction, a dry gas is passed through the reactant, and the moisture content of the dry gas after passing is 3 g / m ３ It is dried so as to be as follows. The method for producing a halogenated alkene according to any one of <1> to <4>. <6> The method for producing a halogenated alkene according to any one of <1> to <5>, wherein silicon tetrafluoride is produced. <7> In the gas phase, the halogenated alkene and hydrogen fluoride are produced by the dehydrofluorination reaction of the halogenated alkane, and silicon tetrafluoride is produced by the reaction of the produced hydrogen fluoride and silicon oxide. The method for producing a halogenated alkene according to any one of <1> to <6>. <8> The method for producing a halogenated alkene according to any one of <1> to <7>, wherein the fluorine-containing alkali metal salt contains at least one selected from the group consisting of NaF, KF, K ２ SiF ６ , LiF, CsF, and Na ２ SiF ６ . <9> The method for producing a halogenated alkene according to any one of <1> to <8>, wherein the halogenated alkane includes a halogenated alkane represented by the following formula (1), and the halogenated alkene includes a halogenated alkene represented by the following formula (2). CR １ R ２ X １ -CR ３ R ４ X ２ ...(1) CR １R ２ =CR ３ R ４ ... (2) In equations (1) and (2), R １ ~R ４ Each of these is independently a hydrogen atom, a fluorine atom, a methyl group, a fluorinated methyl group, an ethyl group, or a fluorinated ethyl group, and R １ ~R ４ The total number of fluorine atoms is 1 or more, and the number of carbon atoms is 2 to 4. In equation (1), X １ and X ２ In this, one is a hydrogen atom and the other is a fluorine atom. <10> A method for producing a halogenated alkene according to any one of <1> to <9>, wherein the halogenated alkane is converted at a temperature of 400 to 1000°C. <11> A method for producing a halogenated alkene according to any one of <1> to <10>, wherein the conversion reaction is carried out in a fluidized bed reactor. <12> A method for producing a halogenated alkene according to any one of <1> to <11>, wherein the conversion reaction is carried out while stirring silicon oxide particles and a fluorine-containing alkali metal salt. <13> A method for producing silicon tetrafluoride, wherein in the gas phase, a halogenated alkane containing a fluorine atom and having 2 to 4 carbon atoms is brought into contact with silicon oxide particles and a fluorine-containing alkali metal salt to produce silicon tetrafluoride. <14> A method for producing silicon tetrafluoride according to <13>, comprising: generating a halogenated alkene and hydrogen fluoride in the gas phase by a dehydrofluorination reaction of the halogenated alkane; and generating silicon tetrafluoride by a reaction between the generated hydrogen fluoride and silicon oxide. 【0008】 This disclosure provides a method for producing a halogenated alkene in which the powder state of the reactant can be maintained throughout the reaction process, and a method for producing silicon tetrafluoride. 【0009】In this disclosure, numerical ranges indicated using "~" mean a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In this disclosure, the amount of each component means the total amount of multiple substances if there are multiple substances corresponding to each component, unless otherwise specified. 【0010】 [Method for Producing Halide Alkenes] The method for producing halide alkenes according to this disclosure is a method for converting a halide alkane containing a fluorine atom and having 2 to 4 carbon atoms into a halide alkene containing a fluorine atom and having 2 to 4 carbon atoms in the gas phase in the presence of silicon oxide particles and a fluorine-containing alkali metal salt. Hereinafter, "halide alkane containing a fluorine atom and having 2 to 4 carbon atoms" will also be referred to as "specific halide alkane," and "halide alkene containing a fluorine atom and having 2 to 4 carbon atoms" will also be referred to as "specific halide alkene." Furthermore, silicon oxide particles and a fluorine-containing alkali metal salt will be collectively referred to as "reactants." 【0011】 According to the method for producing halogenated alkenes of this disclosure, the powder state of the reactant can be maintained throughout the reaction process. In this disclosure, "the powder state of the reactant is maintained" means "the powder state is maintained throughout" or "a small amount of the reactant is lumpy in some parts, but the powder state is maintained," and "the powder state is not maintained" means "the majority is lumpy (for example, lumpy enough to block the reactor)." Whether the powder state of the reactant is maintained is determined by whether or not the majority is lumpy. The powder state (shape of the powder, physical properties, etc.) may change as long as it exhibits the above-described powdery appearance. The reason why the above effect is achieved in the method for producing halogenated alkenes of this disclosure is not clear, but it is presumed to be as follows. 【0012】In the reaction to obtain a fluorine-containing alkene halogen from a fluorine-containing alkane halogen, hydrogen fluoride is produced. The produced hydrogen fluoride is then used as a catalyst, for example, with alumina (Al ２ O ３ When used, it reacts with alumina and produces AlF ３ It generates calcium carbonate (CaCO3) as a catalyst. ３ When using CaF ２ This generates AlF. ３ The boiling point of is 1260°C, and CaF ２ Since the boiling point of is 2533°C, these are solids in the reaction system. Therefore, the generated AlF ３ CaF ２ It remains in the reaction system and coats the reaction sites present on the catalyst surface. This coating of the catalyst's reaction sites causes a rapid decrease in the catalyst's activity. 【0013】 Alumina (Al ２ O ３ ) and calcium carbonate (CaCO3) ３ Even when reagents other than those specified are used, these reagents tend to react with the generated hydrogen fluoride, causing the reagents to fluorinate and change in quality. For example, if the reagent changes due to fluorination and becomes lumpy or liquefied, the contact state of the specific halogenated alkane, which is the raw material, with the reagent changes, which may reduce the amount of specific halogenated alkene produced. Furthermore, if the properties of the reagent change, the reaction conditions must be adjusted sequentially. 【0014】 In contrast, the method for producing halogenated alkenes according to this disclosure obtains a specific halogenated alkene from a specific halogenated alkane in the presence of silicon oxide particles and a fluorine-containing alkali metal salt. In this process, the generated hydrogen fluoride reacts with the silicon oxide particles, or the specific halogenated alkane reacts directly with the silicon oxide particles and the fluorine-containing alkali metal salt, and regardless of the reaction scheme, silicon tetrafluoride (SiF) is obtained. ４This generates silicon tetrafluoride. Since the boiling point of silicon tetrafluoride is -95°C, it is a gas within the reaction system and is released outside the reaction system. Therefore, in the method for producing alkene halogens according to this disclosure, it is believed that the coating of silicon oxide particles with by-products is suppressed, and the deterioration of the reactant over time is suppressed. 【0015】 Furthermore, in the method for producing halogenated alkenes according to this disclosure, since a fluorine-containing alkali metal salt that inherently contains the element fluorine is used, even if the fluorine-containing alkali metal salt is fluorinated, deterioration is suppressed and the powder state of the reactant can be maintained. Maintaining the powder state of the reactant suppresses fluctuations in reaction conditions, and for example, when the reaction is carried out in a fluidized bed reactor, the fluid state can be maintained. 【0016】 The method for producing the halogenated alkenes described herein will be explained in detail below. 【0017】 (Specific Halide Alkanes) In the method for producing halide alkenes according to this disclosure, specific halide alkanes are used as raw materials. Specific halide alkanes may be used alone or in combination of two or more. The number of carbon atoms in the specific halide alkanes is 2 to 4, and may be 2, 3, or 4. From the viewpoint of the boiling point range when using specific halide alkenes as refrigerants, the number of carbon atoms in the specific halide alkanes is preferably 2 or 3. Specific halide alkanes contain fluorine atoms. The number of fluorine atoms in the specific halide alkanes is preferably 2 or more. The number of hydrogen atoms in the specific halide alkanes is preferably 1 or more. Specific halide alkanes may also contain other halogen atoms besides fluorine atoms. Examples of other halogen atoms include chlorine atoms, bromine atoms, and iodine atoms, with chlorine atoms being preferred. Specific halide alkanes do not need to contain other halogen atoms. 【0018】 Examples of specific halogenated alkanes include the halogenated alkane represented by the following formula (1): CR １ R ２ X １ -CR ３ R ４ X ２ ... (1) 【0019】 In formula (1), R１ ~R ４ Each of these is independently a hydrogen atom, a fluorine atom, a methyl group, a fluorinated methyl group, an ethyl group, or a fluorinated ethyl group, and R １ ~R ４ The total number of fluorine atoms is 1 or more, and the number of carbon atoms is 2 to 4, X １ and X ２ One of them is a hydrogen atom, and the other is a fluorine atom. 【0020】 R １ and R ３ Each of these is preferably a hydrogen atom or a fluorine atom, R ２ and R ４ These are hydrogen atoms, fluorine atoms, and CH ３ ,CH ２ F, CHF ２ or CF ３ It is preferable that this be the case. 【0021】 Among the halogenated alkanes represented by formula (1), the fluorine-containing halogenated alkane with 3 carbon atoms is 1,1,1,2,2,3,3-heptafluoropropane (CF ３ CF ２ CHF ２ , HFC-227ca), 1,1,1,2,2,3-hexafluoropropane (CF ３ CF ２ CH ２ F, HFC-236cb), 1,1,2,2,3,3-Hexafluoropropane (CHF ２ CF ２ CHF ２ HFC-236ca), 1,1,2,2,3-pentafluoropropane (CHF ２ CF ２ CH ２ F, HFC-245ca), 1,1,1,2,3,3-Hexafluoropropane (CF ３ CHFCHF ２ , HFC-236ea), 1,1,1,2,3-pentafluoropropane (CF ３ CHFCH ２ F, HFC-245eb), 1,1,2,3,3-Pentafluoropropane (CHF ２ CHFCHF ２, HFC-245ea), 1,1,1,3,3-pentafluoropropane (CF ３ CH ２ CHF ２ , HFC-245fa), 1,1,2,3-tetrafluoropropane (CHF ２ CHFCH ２ F, HFC-254ea) 1,1,1,3-tetrafluoropropane (CF ３ CH ２ CH ２ F, HFC-254fb), 1,1,3,3-tetrafluoropropane (CHF ２ CH ２ CHF ２ , HFC-254fa) and 1,1,3-trifluoropropane (CHF ２ CH ２ CH ２ F, HFC-263fa) and at least one selected from the group consisting of. 【0022】 Among the halogenated alkanes represented by the formula (1), the fluorinated halogenated alkanes having 4 carbon atoms are 1,1,1,2,2,3,3,4,4-nonafluorobutane (CF ３ CF ２ CF ２ CHF ２ ), 1,1,1,2,2,3,3,4-octafluorobutane (CF ３ CF ２ CF ２ CH ２ F), 1,1,2,2,3,3,4,4-octafluorobutane (CHF ２ CF ２ CF ２ CHF ２ ), 1,1,2,2,3,3,4-heptafluorobutane (CHF ２ CF ２ CF ２ CH ２ F), 1,1,1,2,3,4,4-heptafluorobutane (CF ３ CHFCHFCF ２ H), 1,1,1,2,3,4,4,4-octafluorobutane (CF ３ CHFCHFCF ２), 1,1,1,2,2,3,4,4,4-nonafluorobutane (CF ３ CF ２ CHFCF ３ ), and 1,1,1,3,3-pentafluorobutane (CF ３ CH ２ CF ２ CH ３ At least one selected from the group consisting of ) is included. 【0023】 The alkane halide represented by formula (1) may also be the following compound: CHF ２ CH ３ : 1,1-difluoroethane (HFC-152a) CH ２ FCH ２ F: 1,2-difluoroethane (HFC-152) CF ３ CH ３ : 1,1,1-trifluoroethane (HFC-143a) CHF ２ CH ２ F: 1,1,2-trifluoroethane (HFC-143) CF ３ CH ２ F: 1,1,1,2-tetrafluoroethane (HFC-134a) CHF ２ CHF ２ : 1,1,2,2-tetrafluoroethane (HFC-134) CF ３ CHF ２ : 1,1,1,2,2-Pentafluoroethane (HFC-125) 【0024】 The specified halide alkane may include other halide alkanes other than the halide alkane represented by formula (1) (provided that it contains a fluorine atom and has 2 to 4 carbon atoms). The proportion of the halide alkane represented by formula (1) to the total amount of the specified halide alkane is preferably 30 mol% or more, and more preferably 50 mol% or more. 【0025】(Specific Halide Alkenes) In the method for producing halide alkenes according to the present disclosure, specific halide alkenes are obtained as reaction products. The specific halide alkenes may be a single type or may contain two or more types. The specific halide alkenes have 2 to 4 carbon atoms, and may have 2, 3, or 4 carbon atoms. The specific halide alkenes contain fluorine atoms. The number of fluorine atoms in the specific halide alkenes is 1 or more. The specific halide alkenes may also contain halogen atoms other than fluorine atoms. Examples of other halogen atoms include chlorine atoms, bromine atoms, and iodine atoms, with chlorine atoms being preferred. The specific halide alkenes do not have to contain other halogen atoms. 【0026】 The three-carbon halogenated alkene is preferably a fluorine-containing halogenated alkene, and hexafluoropropene (CF ２ = CFCF ３ (HFP), (E)-1,2,3,3,3-pentafluoro-1-propene(CHF=CFCF) ３ HFC-1225ye(E), (Z)-1,2,3,3,3-pentafluoro-1-propene(CHF=CFCF) ３ , HFC-1225ye(Z)), 2,3,3,3-tetrafluoropropene (CH ２ = CFCF ３ HFO-1234yf), (E)-1,3,3,3-tetrafluoro-1-propene (CHF=CHCF ３ HFO-1234ze(E)), (Z)-1,3,3,3-tetrafluoro-1-propene(CHF=CHCF ３ HFO-1234ze(Z), (E)-1,2,3,3-tetrafluoropropene(CHF=CFCHF) ２ HFO-1234ye(E), (Z)-1,2,3,3-tetrafluoropropene(CHF=CFCHF) ２ , HFO-1234ye(Z)), 3,3,3-trifluoropropene (CH ２ =CHCF ３ ,HFO-1243zf), 2,3,3-trifluoro-1-propene (CH ２ = CFCHF ２HFO-1243yf), (E)-1,3,3-trifluoro-1-propene (CHF=CHCHF ２ , HFO-1243ze(E)), and (Z)-1,3,3-trifluoro-1-propene (CHF=CHCHF ２ At least one selected from the group consisting of HFO-1243ze(Z) is mentioned. 【0027】 The halogenated alkene with 4 carbon atoms is preferably a fluorine-containing halogenated alkene, and (2E)-1,1,1,2,3,4,4,4-octafluoro-2-butene (CF ３ CF = CFCF ３ (E)-PFC-1318my), (2Z)-1,1,1,2,3,4,4,4-octafluoro-2-butene (CF ３ CF = CFCF ３ (Z)-PFC-1318my), (2E)-1,1,1,2,3,4,4-heptafluoro-2-butene (CF ３ CF = CFCHF ２ ), (2Z)-1,1,1,2,3,4,4-heptafluoro-2-butene (CF ３ CF = CFCHF ２ ), (2E)-1,1,2,3,4,4-hexafluoro-2-butene (CHF ２ CH=CFCHF ２ HFO-1336pyy(E), (2Z)-1,1,2,3,4,4-hexafluoro-2-butene(CHF ２ CH=CFCHF ２ HFO-1336pyy(Z), 1,1,2,3,4,4-hexafluoro-1,3-butadiene (CF ２ =CFCF=CF ２ FC-2316), 1,1,2,3,3,4,4-heptafluoro-1-butene (CHF ２ CF ２ CF = CF ２ , HFC-1327cyc), and 1,1,2,3,4,4,4-heptafluoro-1-butene (CF ３ CHFCF = CF ２ At least one selected from the group consisting of HFO-1327cze is mentioned. 【0028】 Examples of specific halogenated alkenes include the halogenated alkene represented by the following formula (2): CR １ R ２ =CR ３ R ４ ... (2) 【0029】 In formula (2), R １ ~R ４ Each of these is independently a hydrogen atom, a fluorine atom, a methyl group, a fluorinated methyl group, an ethyl group, or a fluorinated ethyl group, and R １ ~R ４ The total number of fluorine atoms is 1 or more, and the number of carbon atoms is 2 to 4. R in equation (2) １ ~R ４ R in equation (1) is １ ~R ４ It is synonymous with [the above]. 【0030】 R １ and R ３ Each of these is preferably a hydrogen atom or a fluorine atom, R ２ and R ４ These are hydrogen atoms, fluorine atoms, and CH ３ ,CH ２ F, CHF ２ or CF ３ It is preferable that this be the case. 【0031】 Examples of halogenated alkenes represented by formula (2) include the following compounds: CHF=CH ２ Fluoroethylene (HFO-1141) CF ２ =CH ２ : 1,1-difluoroethylene (HFO-1132a) CHF=CHF: 1,2-difluoroethylene (HFO-1132(E), HFO-1132(Z)) CHF=CF ２ Trifluoroethylene (HFO-1123) CF ２ =CF ２ : Tetrafluoroethylene (FO-1114) Note that the halogenated alkenes represented by formula (2) may include the compounds exemplified as fluorine-containing halogenated alkenes having 3 and 4 carbon atoms. 【0032】In particular, the halogenated alkene represented by formula (2) is preferably at least one selected from the group consisting of HFO-1132(E), HFO-1132(Z), and HFO-1123, from the viewpoint of usefulness as a refrigerant. Furthermore, from the viewpoint of usefulness as a resin raw material, HFO-1132a, HFO-1141, and FO-1114 are preferred. 【0033】 (Reactant) In the method for producing a halogenated alkene according to this disclosure, a specific halogenated alkane is converted to a specific halogenated alkene in the presence of a reactant. The reactant comprises silicon dioxide particles and a fluorine-containing alkali metal salt. By using silicon dioxide particles and a fluorine-containing alkali metal salt as the reactant, the powder state of the reactant can be maintained throughout the reaction process. Furthermore, using silicon dioxide particles and a fluorine-containing alkali metal salt as the reactant tends to suppress the deterioration of the reactant over time during the reaction. 【0034】 As the reactants, silicon dioxide particles and a fluorine-containing alkali metal salt are used. Since the silicon dioxide particles and the fluorine-containing alkali metal salt are introduced separately, it is easy to prepare high-purity materials for each, and the generation of unwanted by-products during the reaction is easily suppressed. Furthermore, the silicon dioxide particles and the fluorine-containing alkali metal salt may be separate raw materials, and the fluorine-containing alkali metal salt may subsequently adhere to the silicon dioxide particles, forming a single unit. 【0035】 The silicon dioxide particles may be in a crystalline or amorphous (non-crystalline) state. Examples of silicon dioxide particles include silica sand, quartz, diatomaceous earth, colloidal silica, precipitated silica, silica gel, fumed silica, and rice husks, with silica sand being preferred from the viewpoint of purity and cost. 【0036】 The shape of silicon dioxide particles is not particularly limited and may be irregular in shape, such as natural products or pulverized materials, or may be cullet-like, flaky, or spherical. They may also be molded into pellets, hollow shapes, cylindrical shapes, etc. Furthermore, silicon dioxide particles may have a porous structure (e.g., porous). These shapes may be combined as appropriate, for example, a porous cylindrical molded product. 【0037】It is preferable that the silicon dioxide particles have a low impurity content. From the viewpoint of suppressing the generation of unwanted by-products, the silicon dioxide content in the silicon dioxide particles should be low, preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. 【0038】 From the viewpoint of suppressing clogging in the reactor, the average particle size of silicon dioxide particles when introduced into the reactor is preferably 20 μm or more, and more preferably 50 μm or more. From the viewpoint of ensuring sufficient surface area for reaction sites, the average particle size of silicon dioxide particles when introduced into the reactor is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 1 mm or less. 【0039】 The average particle size of silicon dioxide particles is determined as the particle size (D50) at which the cumulative particle size distribution curve obtained by measurement using a Coulter counter reaches 50%. The aperture diameter is set appropriately according to the particle size range of the object being measured. 【0040】 From the viewpoint of maintaining the performance as a reactant at the heating temperature in the conversion reaction, the thermal decomposition temperature of the fluorine-containing alkali metal salt is preferably 100°C or higher, more preferably 150°C or higher, even more preferably 300°C or higher, particularly preferably 350°C or higher, and extremely preferably 400°C or higher. There is no particular upper limit to the thermal decomposition temperature of the fluorine-containing alkali metal salt, and it may be 1000°C or lower. The thermal decomposition temperature of the fluorine-containing alkali metal salt is measured by thermogravimetric analysis. 【0041】 Fluorine-containing alkali metal salts may react with silicon tetrafluoride produced by a conversion reaction to form reactants, and at least a portion of these reactants may revert back to the fluorine-containing alkali metal salt through thermal decomposition. Confirmation of whether the reactants have reverted to the original fluorine-containing alkali metal salt through thermal decomposition is performed by micro-Raman spectroscopy. As a micro-Raman spectroscopy instrument, for example, the LabRAM HR Evolution manufactured by Horiba, Ltd. can be used, and the measurement conditions are: excitation wavelength 532 nm, objective lens ×100_VIS_LWD, confocal aperture 100 μm, 200 μm pinhole, grating 300, and center wavenumber 1800 cm.－１ It will be implemented there. 【0042】 The fluorine-containing alkali metal salt is preferably at least one salt selected from the group consisting of Li, Na, K, Rb, and Cs, more preferably at least one salt selected from the group consisting of Na, K, and Cs, and even more preferably at least one salt selected from the group consisting of Na and K, from the viewpoint of activity, selectivity, or availability. 【0043】 Fluorine-containing alkali metal salts include NaF, KF, and K ２ SiF ６ LiF, CsF, and Na ２ SiF ６ Preferably, it contains at least one selected from the group consisting of the following, and is less reactive or non-reactive to silicon tetrafluoride while maintaining its performance as a reactant at the heating temperature in the inversion reaction, such as NaF and K ２ SiF ６ It is more preferable to include at least one selected from the group consisting of the following: 【0044】 From the viewpoint of maintaining the powder state of the reactant more favorably throughout the reaction process, the melting point of the fluorine-containing alkali metal salt is preferably 400°C or higher, more preferably 450°C or higher, even more preferably 500°C or higher, particularly preferably 600°C or higher, extremely preferably 700°C or higher, and significantly preferably 800°C or higher. When two or more fluorine-containing alkali metal salts are used in combination, the melting point of the fluorine-containing alkali metal salts refers to the melting point of the mixture. For example, the melting points of fluorine-containing alkali metal salts are LiF (848°C), NaF (993°C), KF (858°C), CsF (682°C), and Na ２ SiF ６ (Varies depending on the source, but above 400°C), K ２ SiF ６ The melting points of fluorine-containing alkali metal salts are (above 400°C, though this varies depending on the literature), a mixture of NaF and KF (718°C), a mixture of LiF and KF (492°C), and a mixture of LiF and NaF (652°C). The melting points of fluorine-containing alkali metal salts are measured by differential thermal-thermogravimetric analysis (TG-DTA). Literature values ​​may be used for the melting points of fluorine-containing alkali metal salts. 【0045】 From the viewpoint of maintaining the powder state of the reactant in a better manner throughout the reaction process, the moisture content in the reactant (total amount of silicon dioxide particles and fluorine-containing alkali metal salt) is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less. The moisture content in the reactant is measured using a Karl Fischer moisture meter or the like. Note that the moisture content in the reactant is the value immediately before the start of the reaction. 【0046】 The silicon content in the reactant may be 1 atm% or more, 5 atm% or more, or 10 atm% or more. The silicon content in the reactant may also be 90 atm% or less, or 80 atm% or less. The oxygen content in the reactant may be 1 atm% or more, 5 atm% or more, or 10 atm% or more. The oxygen content in the reactant may also be 90 atm% or less, or 80 atm% or less. The alkali metal element content in the reactant may be 1 atm% or more, 5 atm% or more, or 8 atm% or more. The alkali metal element content in the reactant may also be 90 atm% or less, or 50 atm% or less. 【0047】 The content of each element in the reactant is determined by scanning electron microscopy energy-dispersive X-ray spectroscopy (SEM-EDX analysis). 【0048】 In the reactant, the silicon content (atm%) is preferably higher than the alkali metal element content (atm%), and is preferably higher than the total content of alkaline earth metals and Group 13 elements of the periodic table. It is also preferable that silicon is the element with the highest content (atm%) among the elements excluding oxygen. Furthermore, in the reactant, the alkali metal element content (atm%) is preferably higher than the individual content of silicon, oxygen, and other elements other than alkali metal elements. In the reactant, the content of other elements is preferably 50 atm% or less, more preferably 30 atm% or less, even more preferably 10 atm% or less, and may be 0 atm% (not present). 【0049】(Reaction Scheme) In the method for producing the halogenated alkene of this disclosure, silicon tetrafluoride (SiF ４ ) is produced. In the method for producing halogenated alkenes of this disclosure, a reaction scheme is conceivable in which, in the gas phase, a specific halogenated alkane and hydrogen fluoride are produced by the dehydrofluorination reaction of a specific halogenated alkane (first step), and silicon tetrafluoride is produced by the reaction of the produced hydrogen fluoride with silicon oxide (second step). The first and second steps may proceed continuously without distinction. The method for producing halogenated alkenes of this disclosure may also be a reaction scheme other than the one described above. For example, silicon oxide or an alkali metal compound may react directly with the halogenated alkane to produce silicon tetrafluoride. In addition to silicon tetrafluoride, other compounds may also be produced. 【0050】 Below, we present an example of a reaction scheme in which a halogenated alkane represented by formula (1) is used as the specific halogenated alkane, and a halogenated alkene represented by formula (2) is obtained as the specific halogenated alkene. 【0051】 【0052】 Since the generated silicon tetrafluoride is a gas, it is released from the reaction system. Therefore, the influence of by-products on the reactants inside the reaction tube (i.e., alkali metal salts and silicon oxide) is suppressed, and the rapid decrease in the amount of alkene halide produced is prevented. 【0053】 In conventional manufacturing methods using alumina, calcium carbonate, etc. as catalysts, the generated hydrogen fluoride reacts with the catalyst as follows. 【0054】 【0055】 The generated aluminum fluoride (AlF ３ ) and calcium fluoride (CaF ２Since the substance is a solid, it is not released outside the reaction system but remains within it, coating the surfaces of the catalysts, alumina and calcium carbonate. As a result, the active sites on the surface of the catalyst are covered and the catalyst becomes inactive. Therefore, in conventional manufacturing methods, it is necessary to remove the degraded catalyst and replace it with a new one. Consequently, conventional manufacturing methods using alumina, calcium carbonate, etc. as catalysts have unstable productivity and require stopping the reaction each time the catalyst is replaced. In contrast, the method for producing alkene halides according to this disclosure has the advantage of reducing the work of removing degraded catalysts while maintaining productivity. 【0056】 Furthermore, in the method for producing alkene halides according to this disclosure, the reaction can be continued by replenishing the consumed silicon dioxide. The amount of silicon dioxide consumed can be calculated from the amount of silicon tetrafluoride released from the reaction system. Specifically, the amount of silicon tetrafluoride released can be measured by passing the released silicon tetrafluoride through water, an alkaline aqueous solution, etc., to obtain hydrogen fluoride, hexafluorosilicic acid, or salts thereof, and then titrating these. On the other hand, in conventional production methods using alumina or calcium carbonate as a catalyst, AlF ３ or CaF ２ Because the catalyst remains in place, it is difficult to estimate the amount of degraded catalyst. Therefore, it is difficult to accurately estimate the amount of catalyst to be replenished using conventional manufacturing methods. 【0057】 Furthermore, the method for producing halogenated alkenes according to this disclosure uses a fluorine-containing alkali metal salt as a reactant. Since fluorine-containing alkali metal salts such as NaF are already fluorinated, the changes caused by the generated hydrogen fluoride are suppressed, and the powder state can be maintained. On the other hand, in the case of alkali metal salts that do not contain fluorine, for example, when NaCl is used, the generated hydrogen fluoride reacts with NaCl as follows, and the hydrogen fluoride acts on NaCl to change it into NaF, causing the reactant to clump together. 【0058】 【0059】 When reacting in a fluidized bed, it is desirable that the fluidity of the catalyst does not change significantly, but in conventional methods, AlF３ or CaF ２ Because of the adhesion of the by-product SiF, the weight and density of the catalyst change, causing fluctuations in fluidity. Therefore, it is difficult to maintain an appropriate flow state. In contrast, the manufacturing method of this disclosure uses SiF as a by-product. ４ Since the hydrogen fluoride is a gas and released outside the reaction system, there is no significant change in the fluidity of the silicon dioxide particles, making it easy to maintain an appropriate flow state. Furthermore, in the manufacturing method of this disclosure, the fluorine-containing alkali metal salt is suppressed by the generated hydrogen fluoride, so changes in the properties of the reactant, such as clumping, are suppressed, and the powder state can be maintained. Therefore, significant changes in the fluidity of the reactant as a whole are suppressed, making it easy to maintain an appropriate flow state. 【0060】 (Reaction Conditions) The method for producing halogenated alkenes according to this disclosure is carried out in the gas phase because the specific halogenated alkane is a gas at room temperature and atmospheric pressure. In the method for producing halogenated alkenes according to this disclosure, the raw material gas only needs to contain the specific halogenated alkane, and may also contain components other than the specific halogenated alkane. The raw material gas may consist only of the specific halogenated alkane, or it may contain isomers, disproportionation products, impurities, etc. obtained when producing the specific halogenated alkane. From the viewpoint of suppressing side reactions, the content of the specific halogenated alkane is preferably 10 mol% or more, more preferably 30 mol% or more, and even more preferably 50 mol% or more, based on the total amount of the raw material gas. The content of the halogenated alkane represented by formula (1) may be 100 mol% of the total amount of the raw material gas. 【0061】 The reactor used to react the halogenated alkane with the reagent can be any reactor capable of withstanding the temperature and pressure described later, and its shape and structure are not particularly limited. Examples of reactors include cylindrical vertical reactors. Examples of reactor materials include glass, stainless steel, iron, nickel, chromium, and alloys mainly composed of iron, nickel, or chromium. The inside of the reactor may be coated with platinum or gold. The reactor may also be equipped with heating means such as an electric heater to heat the inside of the reactor. 【0062】The reactants may be contained in a fixed-bed, fluidized-bed, or mobile-bed reactor. If a fixed-bed reactor is used, it may be either a horizontal or vertical fixed-bed reactor. The reactor may rotate as a whole. The reaction may be a flow-through reactor or a batch reactor. 【0063】 In fixed-bed reactors, various molded bodies of reactant carriers are packed to reduce pressure loss of the reaction fluid. A moving bed reactor is another method where the reactant is packed in a similar manner to a fixed-bed reactor, moved by gravity, and then extracted from the bottom of the reactor for regeneration. In fluidized-bed reactors, the reaction fluid is used to make the reactant layer behave like a fluid, so the reactant mixes with the reaction fluid and moves within the reactor. Fixed-bed reactors are preferred because they offer a wide range of reactant shape options and suppress reactant wear. Fluidized-bed reactors are preferred because they maintain a uniform internal temperature and make it easier to avoid localized overheating. Preventing localized overheating suppresses runaway reactions such as disproportionation, and because the temperature remains constant, the reaction results tend to be more consistent. Furthermore, preventing localized overheating makes it easier to suppress agglomeration due to reactant melting. When the reactant agglomerates, the surface area of ​​the reactant decreases, and the contact efficiency with the raw material gas, i.e., the efficiency of the conversion reaction, tends to decrease. Furthermore, clumps of the reactant can block the passage of gases such as raw material gas and generated gas, which can cause the internal pressure of the reactor to rise. 【0064】 The method for producing halogenated alkenes according to this disclosure is suitably applicable to reactions in fluidized bed reactors because it suppresses changes in the properties of the reactant over time and allows the powder state to be maintained. When the reactant becomes lumpy, the internal pressure of the reaction tube tends to increase, which may promote side reactions of the product. Furthermore, maintaining the powder state reduces the need for complex equipment configurations to maintain a constant reaction. 【0065】Fixed-bed reactors include tubular reactors and tank reactors, with tubular reactors being preferred due to their ease of controlling the reaction temperature. Furthermore, multi-tube heat exchange reactors, in which many small-diameter reaction tubes are arranged in parallel and a heat transfer medium is circulated around the outside, can be employed. When multiple reactors are installed in series, multiple reactant layers will be provided. At least one reactant layer is sufficient, but two or more layers are also acceptable. 【0066】 In the case of a fluidized bed reactor, the raw material gas and diluent gas may be flowed from the bottom in the vertical direction, and the product gas may be withdrawn from the top in the vertical direction. From the viewpoint of further increasing fluidity, agitators may be installed in the fluidized bed reactor. The shape of the agitators is not limited and may be, for example, propeller blades, turbine blades, paddle blades, anchor blades, ribbon blades, double helical ribbon blades, V-shaped ribbon blades, V-shaped double helical ribbon blades, or combinations thereof. It is preferable to carry out the conversion reaction while stirring the reactants, as this suppresses localized heating and further suppresses the clumping of the reactants. When using agitators, the stirring speed is not particularly limited and may be, for example, 80 rpm or less, 60 rpm or less, 30 rpm or less, 20 rpm or less, or 5 rpm or less, or even 0 rpm, meaning that stirring is not performed even if an agitator is installed. In addition, from the viewpoint of preventing uneven flow of gas in the fluidized bed reactor, a gas dispersion plate may be provided in the fluidized bed reactor. The material of the gas dispersion plate is not particularly limited, but it is preferable to use a material with low reactivity with the source gas, generated gas, etc. Examples of gas dispersion plate materials include sintered metal. The size, arrangement position, and number of gas dispersion plates may be adjusted as appropriate according to the gas flow. 【0067】 In the method for producing halogenated alkenes according to this disclosure, the halogenated alkane is preferably converted at a temperature of 400 to 1000°C, more preferably at 450 to 900°C, and even more preferably at 500 to 800°C. When converted at 400°C or higher, the reaction proceeds appropriately and the conversion rate of the halogenated alkene is improved. On the other hand, when converted at 1000°C or lower, the decrease in selectivity due to carbon-carbon bond cleavage of the starting material and the disproportionation reaction of the reaction product (unsaturated compound) are suppressed. 【0068】 By adjusting the temperature within the above temperature range and maintaining the reaction temperature appropriately, it is possible to suppress the decrease in the conversion rate. To maintain the reaction temperature in the reactant layer at the desired temperature, for example, the reactant layer can be heated externally using a heat transfer medium, an electric furnace, or the like. 【0069】 As described above, in the method for producing alkene halogens according to this disclosure, the reaction can be continued by replenishing the consumed silicon dioxide, thereby maintaining productivity. From the viewpoint of continuing the reaction, it is preferable to continuously supply the consumed silicon dioxide. The supply location of silicon dioxide in the reactor is not particularly limited and may be from the top or bottom of the reactor. 【0070】 In the method for producing halogenated alkenes according to this disclosure, the raw material gas containing the halogenated alkane may be supplied to the reactor at room temperature, or it may be appropriately heated (preheated) before being supplied to the reactor. When preheating is performed, it is preferable to heat the raw material gas to 80°C or higher and below the reaction temperature inside the reactor before supplying it to the reactor. Setting the preheating temperature to 80°C or higher makes it less likely for the internal temperature of the reactor to drop, and makes it easier to achieve the set conversion rate. Furthermore, setting the preheating temperature below the reaction temperature inside the reactor suppresses undesirable reactions and improves the selectivity. 【0071】 The dehydrofluoride reaction in this disclosure is a reaction in which the number of molecules increases, so increasing the pressure is detrimental to the forward reaction. The pressure when reacting the halogenated alkane with the reactant is not particularly limited, but from the viewpoint of improving the conversion rate, -0.05 to 2 MPa is preferred, -0.01 to 1 MPa is more preferred, and atmospheric pressure to 0.5 MPa is even more preferred. In this disclosure, pressure means gauge pressure. 【0072】 The residence time of the halogenated alkane is preferably 0.5 to 300.0 seconds, more preferably 1.0 to 100.0 seconds, and even more preferably 1.5 to 60.0 seconds. 【0073】 The residence time (seconds) is calculated using the following formula: Residence time (seconds) = [Length of the reactor filled with reagent (cm)] / [Linear velocity (cm / second)] Linear velocity refers to the rate at which the halide alkane passes through the reagent per unit time. 【0074】 Furthermore, the average bulk density of the reactant was 0.05 g / cm³. ３ The above is preferable, and 0.1 g / cm³ ３ The above is more preferable, 0.2 g / cm³ ３ The above is even more preferable. The average bulk density of the reactant is 0.05 g / cm³. ３ The conversion rate improves when the above conditions are met. The average bulk density of the reactant is the average value of the reactant's density when no gas is flowing through the reactor. The average bulk density of the reactant is measured by the container method. In the container method, the reactant is placed in a container of known capacity until it overflows, and the excess reactant overflowing from the rim of the container is removed with a spatula or similar tool, and the mass of the reactant in the container is measured. The bulk density (g / mL) is calculated from this mass of reactant and the capacity (volume) of the container. This measurement is performed three times, and the average value is taken as the average bulk density. 【0075】 The conversion of specific halogenated alkanes may be carried out in the presence of a diluent gas. The diluent gas is preferably at least one selected from the group consisting of nitrogen, hydrogen, carbon dioxide, helium, propane, isobutane, n-butane, ethane, propylene, and fluorinated methane. Examples of fluorinated methanes include monofluoromethane, difluoromethane, trifluoromethane, and tetrafluoromethane. When a diluent gas is used, the molar ratio of the specific halogenated alkane to the diluent gas in the gas phase is preferably 0.1 to 5.0, more preferably 0.5 to 3.0, and even more preferably 0.5 to 2.0. 【0076】In general, in methods for producing alkene halides, diluent gases are used to suppress disproportionation reactions caused by high concentrations of the generated alkene halides, and also because high concentrations of certain types of alkene halides pose a risk of explosion. In the method for producing alkene halides of this disclosure, reactivity can be controlled by residence time, reaction temperature, etc., and the concentration of the specific alkene halides in the outlet gas can be controlled by these controls. In the method for producing alkene halides of this disclosure, the amount of alkene halides produced can be kept within a certain range while maintaining the amount of alkene halides produced by the above controls, so that the outlet gas can contain a certain amount or more of the specific alkane halides that are the raw materials. The specific alkane halides in the outlet gas also function as a diluent. Therefore, in the method for producing alkene halides of this disclosure, it is also possible to reduce the amount of diluent gas used. The method for producing alkene halides of this disclosure also includes a method that does not use a diluent gas. 【0077】 Furthermore, in the method for producing fluoroolefins using an alumina catalyst, as described in Patent Document 1, the conversion rate decreases when the amount of diluent is reduced, making it difficult to use the raw material gas as a diluent, and thus the use of diluent gases such as nitrogen and carbon dioxide is essential. Since diluent gases such as nitrogen and carbon dioxide have lower boiling points or are close in boiling point range to the reaction product, halogenated alkenes, energy is required to separate and purify the diluent gas from the reaction product. In the method for producing halogenated alkenes of this disclosure, even if the raw material gas is used as part or all of the diluent, the decrease in the amount of halogenated alkenes produced over time can be suppressed. Since the raw material halogenated alkanes have high boiling points and are far from the boiling point range of the reaction product, halogenated alkenes, the energy load required for separation and purification can also be reduced in the method for producing halogenated alkenes of this disclosure. 【0078】From the viewpoint of controlling the efficiency and selectivity of the reaction, the conversion of specific halogenated alkanes is preferably carried out in the gas phase in the presence of water, and the concentration of water is preferably less than 500 volume ppm relative to the total amount of the raw material gas containing the specific halogenated alkanes. The dehydrofluoride reaction in this disclosure also produces water. Therefore, it can be said that the reaction proceeds without problems even if water is present in the system. Furthermore, when hydrogen fluoride is desorbed from the raw material, or when hydrogen fluoride reacts with silicon dioxide, the presence of water molecules may allow the reaction to proceed more efficiently via a hydrogen bond network. Therefore, it is possible to add a small amount of water in the dehydrofluoride reaction in this disclosure, and it is presumed that this may yield good results. On the other hand, from the viewpoint of preventing blockage of the gas flow path due to the reaction between the generated silicon tetrafluoride and water near the outlet to produce hexafluorosilicic acid, etc., it is preferable to keep the water concentration below the above range. 【0079】 A common method for measuring the moisture content of a gas is to use a commercially available dew point meter. A moisture content of less than 500 volume ppm relative to the total amount of the specific halogenated alkane results in a high conversion rate and allows for the acquisition of the target product with high selectivity. From the viewpoint of further improving the conversion rate and obtaining the target compound with even higher selectivity, a moisture content of 300 volume ppm or less is preferable, more preferably 100 volume ppm or less, even more preferably 50 volume ppm or less, and particularly preferable 10 volume ppm or less. While a lower moisture content is preferable, from the viewpoint of reducing the cost of dehydration treatment of the specific halogenated alkane and diluent gas, and from the viewpoint of facilitating process control, a moisture content of 0.5 volume ppm or more is preferable, and more preferably 1 volume ppm or more. 【0080】 The water concentration mentioned above refers to the water content in the raw material gas when reacting a specific halogenated alkane with a reagent. Alternatively, the water concentration may be replaced with the water content in the raw material gas before it enters the reactor. 【0081】The method for producing halogenated alkenes according to this disclosure may further include a step of drying the reactant and the halogenated alkane before reacting the specific halogenated alkane with the reactant. By drying the reactant, water contained in the reactant may be removed and the water concentration adjusted to the above range. 【0082】 The method for drying the reactant is not particularly limited; it may be dried before filling the reactor, or after filling the reactor. If the reactant is dried after filling the reactor, the reactor can be preheated at the same time as drying the reactant. Specifically, the reactant may be dried by filling the reactor with the reactant and heating the reactor while circulating a diluent gas. 【0083】 When drying of the reactant is carried out by circulating a dry diluent gas (dry gas), the moisture content of the diluent gas after circulation is 3 g / m³. ３ It is preferable to dry it to the following extent: 3 g / m ３ It is more preferable to dry it to the following extent: 1 g / m ３ It is preferable to dry the gas to the following state. The moisture content of the diluted gas after circulation can be determined from the dew point. 【0084】 From the viewpoint of suppressing polymerization of the generated halogenated alkenes, the conversion of specific halogenated alkanes is preferably carried out in an atmosphere with an oxygen content of 10,000 ppm by mass or less, more preferably in an atmosphere with an oxygen content of 5,000 ppm by mass or less, and even more preferably in an atmosphere with an oxygen content of 1,000 ppm by mass or less. 【0085】 Oxygen content refers to the amount of oxygen present in the atmosphere during conversion, encompassing all gases in the site of conversion, including reaction feedstock gases and reaction products. For example, oxygen content is the ratio of the mass of oxygen present in the reactor to the total mass of gases present in the reactor during conversion. 【0086】 The oxygen content is measured using an oxygen concentration meter. Any type of oxygen concentration meter may be used, including, for example, zirconia type, magnetic type, electrochemical type, yellow phosphorus emission type, and laser spectrometer. 【0087】 In this disclosure, the conversion rate is the ratio (%) of the molar amount of specific halogenated alkane consumed in the reaction to the molar amount of specific halogenated alkane supplied to the reactor. The molar amount of the specific halogenated alkane used as a raw material consumed in the reaction is the difference between the molar amount of specific halogenated alkane supplied to the reactor and the molar amount of specific halogenated alkane contained in the gas effluent from the reactor outlet. 【0088】 Generally, a higher conversion rate is preferable from the viewpoint of productivity. However, in the case of certain halogenated alkenes that pose an explosion risk due to high concentration, it is preferable to select operating conditions that result in a conversion rate of 70% or less from the viewpoint of suppressing explosions and suppressing the disproportionation reaction of the specific halogenated alkenes. A conversion rate of 50% or less is preferable, and 30% or less is more preferable. If the conversion rate is too low, productivity will decrease and the equipment will become larger, so it is preferable to select operating conditions that result in a conversion rate of 5% or more. A conversion rate of 10% or more is preferable, and 15% or more is more preferable. 【0089】 In this disclosure, selectivity refers to the ratio (mol %) of the molar amount of the target product contained in the reactor outlet gas to the total molar amount of compounds other than the raw materials contained in the reactor outlet gas (however, compounds derived from the carbon of the specific halogenated alkane that is the raw material, excluding compounds such as silicon tetrafluoride that do not have carbon derived from the raw material). A selectivity of 100% is preferred because it eliminates the need for a purification step after the reaction, but side reactions may occur in the reaction temperature range required to obtain a desirable conversion rate. A higher selectivity is preferred because it reduces the amount of waste, lowers the energy load of the purification step after the reaction, and extends the life of the reagent. A selectivity of 90% or higher is preferred, 93% or higher is more preferred, and 95% or higher is even more preferred. 【0090】 Compounds other than the raw material compounds and target products contained in the reactor outlet gas include, for example, carbon monoxide, carbon dioxide, water, silicon tetrafluoride, and the like. 【0091】According to the method for producing halogenated alkenes of this disclosure, the decrease in the amount of specific halogenated alkenes produced is suppressed during production over a long period of time (specifically, 5 hours or more). The amount of specific halogenated alkenes produced after 5 hours is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more, compared to the amount of specific halogenated alkenes produced after 1 hour. 【0092】 The amount produced is determined by analyzing the reactor outlet gas using gas chromatography and confirming the area ratio (GCAare%) corresponding to the specific halogenated alkene. 【0093】 [Method for Producing Silicon Tetrafluoride] The method for producing silicon tetrafluoride according to this disclosure involves contacting a halogenated alkane containing a fluorine atom and having 2 to 4 carbon atoms with silicon oxide particles and a fluorine-containing alkali metal salt in the gas phase to produce silicon tetrafluoride. The above-mentioned method for producing halogenated alkenes according to this disclosure can also be said to be a method for producing silicon tetrafluoride, as silicon tetrafluoride is produced in this disclosure. Therefore, the specific halogenated alkane, silicon oxide particles, and fluorine-containing alkali metal salt in the method for producing halogenated alkenes according to this disclosure are synonymous with the specific halogenated alkane, silicon oxide particles, and fluorine-containing alkali metal salt in the above-mentioned method for producing halogenated alkenes. Furthermore, the conditions for the method for producing silicon tetrafluoride according to this disclosure are the same as those for the method for producing halogenated alkenes according to this disclosure. Therefore, the method for producing silicon tetrafluoride according to this disclosure may include, in the gas phase, generating the halide alkene and hydrogen fluoride by a dehydrofluorination reaction of the halide alkane, and generating silicon tetrafluoride by a reaction between the generated hydrogen fluoride and silicon oxide. 【0094】The silicon tetrafluoride produced can be used as a raw material for manufacturing high-performance optical fibers, as a gas for semiconductor manufacturing, etc. Furthermore, the silicon tetrafluoride released outside the reaction system can be recovered as hydrogen fluoride or fluoride salts by reacting with water or alkali. These recovered compounds can be used as etching agents or as raw materials for organofluorine compounds. For example, calcium carbonate (CaCO3) can be used as a catalyst. ３ Calcium fluoride (CaF) generated by conventional methods using ) ２ Converting fluorite into hydrogen fluoride requires the extreme condition of reacting it with sulfuric acid, and also requires the solid CaF ２ Pre-processing, such as crushing, is required. 【0095】 The present disclosure will be further described below with reference to examples, but the present disclosure is not limited to the following examples unless it exceeds the spirit of the disclosure. Examples 1-5, 8-12, 15-22, and 24-44 are examples, and Examples 6, 7, 13, 14, and 23 are comparative examples. 【0096】 (Maintaining the powder state of the reactant) One hour after the start of the reaction, the powder state of the reactant was visually checked. The evaluation criteria were as follows: A: The powder state is maintained throughout. B: A small amount has formed clumps in some areas, but the powder state is maintained. C: A large portion has formed clumps. 【0097】 (Outlet Gas Composition) One hour after the start of the reaction, the product gas (hereinafter also referred to as "reactor outlet gas") was taken out from the outlet of the reactor and analyzed by gas chromatography. Specifically, the analysis was performed using a gas chromatograph (product name "GC6850", manufactured by Agilent) with a column (product name "DB-1", manufactured by Agilent, length 60 m, inner diameter 0.25 mm, film thickness 1 μm). The table shows the area ratio (GCAare%) of the reactor outlet gas. 【0098】Furthermore, the obtained area ratio (GCAare%) was converted based on the relative sensitivity of gas chromatography, and the molar composition was determined so that the sum of the components listed in the table equaled 100 mol%. Note that the area ratio (GCAare%) values ​​listed in the table have been rounded to the nearest significant figure, so the sum of each component converted from the area ratio (GCAare%) before rounding may not equal 100 mol%. The rate of change in production amount (%) was also converted from the area ratio (GCAare%) before rounding. 【0099】 [Example 1] A reaction tube made of Inconel 600 with an inner diameter of 2.04 cm and a length of 30 cm was filled with silica sand and sodium fluoride (NaF) mixed in a mass ratio of 1 / 1 (70 g / 70 g) and placed in a tubular electric furnace. The de-HF reaction to HFO-1123 was carried out at 700°C by flowing a 1 / 1 (mol / mol) mixed gas of nitrogen / HFC-134a at the flow rate shown in Table 1. The particle size of the silica sand was 75 to 180 μm. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0100】 [Example 2] In Example 1, sodium fluoride is replaced with potassium hexafluorosilicate (K ２ SiF ６ The HF removal reaction was carried out using the same method except that a different component was used. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0101】 [Example 3] In Example 1, sodium fluoride is replaced with sodium hexafluorosilicate (Na ２ SiF ６ The HF removal reaction was carried out using the same method except that a different component was used. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0102】 [Example 4] The HF removal reaction was carried out in the same manner as in Example 1, except that sodium fluoride was replaced with lithium fluoride (LiF). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0103】[Example 5] The HF removal reaction was carried out in the same manner as in Example 1, except that sodium fluoride was replaced with cesium fluoride (CsF) and the reaction was carried out at 600°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0104】 [Example 6] The HF removal reaction was carried out in the same manner as in Example 1, except that sodium fluoride was replaced with sodium chloride (NaCl). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0105】 [Example 7] In Example 1, potassium carbonate (K ２ CO ３ The HF removal reaction was carried out using the same method except that the ion was changed to . The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0106】 Table 1 shows the reaction conditions and evaluation results for the powder state of Examples 1 to 7. Table 1 also shows the area ratio (GCA area%) and molar composition of the reactor outlet gas one hour after the start of the reaction. 【0107】 【0108】 As shown in Table 1, in Examples 1 to 5, where silicon dioxide particles and fluorine-containing alkali metal salts were used as reactants, the powder state of the reactants was maintained. In contrast, in Examples 6 and 7, where silicon dioxide particles and fluorine-free alkali metal salts were used as reactants, the powder state of the reactants was not maintained. 【0109】 [Example 8] The HF removal reaction was carried out in the same manner as in Example 2, except that HFC-134a was replaced with HFC-125. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0110】 [Example 9] The HF removal reaction was carried out in the same manner as in Example 8, except that potassium hexafluorosilicate was replaced with sodium hexafluorosilicate. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0111】[Example 10] The HF removal reaction was carried out in the same manner as in Example 8, except that potassium hexafluorosilicate was replaced with cesium fluoride and the reaction was carried out at 650°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0112】 [Example 11] The HF removal reaction was carried out in the same manner as in Example 8, except that 70 g of potassium hexafluorosilicate was replaced with cesium fluoride and sodium fluoride mixed in a mass ratio of 1 / 1 (35 g / 35 g), and the reaction was carried out at 650°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0113】 [Example 12] The HF removal reaction was carried out in the same manner as in Example 8, except that 70 g of potassium hexafluorosilicate was replaced with potassium hexafluorosilicate and potassium fluoride mixed in a mass ratio of 1 / 1 (35 g / 35 g). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0114】 [Example 13] The HF removal reaction was carried out in the same manner as in Example 8, except that potassium hexafluorosilicate was replaced with potassium carbonate. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0115】 [Example 14] The HF removal reaction was carried out in the same manner as in Example 8, except that potassium hexafluorosilicate was replaced with cesium carbonate and the reaction was carried out at 600°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0116】 Table 2 shows the reaction conditions for Examples 8 to 14, the area ratio (GCA area%) and molar composition of the reactor outlet gas one hour after the start of the reaction, and the evaluation results of the powder state. 【0117】 【0118】As shown in Table 2, even when the halogenated alkane used as a raw material was changed from HFC-134a to HFC-125, the powder state of the reactant was maintained in Examples 8 to 12, which used silicon dioxide particles and fluorine-containing alkali metal salts as reactants. On the other hand, in Examples 13 and 14, which used silicon dioxide particles and alkali metal salts that did not contain fluorine, the powder state of the reactant was not maintained even when the halogenated alkane used as a raw material was changed from HFC-134a to HFC-125. 【0119】 [Example 15] The HF removal reaction was carried out in the same manner as in Example 8, except that potassium hexafluorosilicate was replaced with sodium fluoride and the silica sand with a particle size of 75-180 μm was changed to silica sand with an average particle size of 24.3 μm. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0120】 [Example 16] The HF removal reaction was carried out in the same manner as in Example 15, except that the silica sand with a particle size of 24.3 μm was changed to silica sand with a particle size of 180 to 430 μm. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0121】 Table 3 shows the reaction conditions for Examples 15 and 16, the area ratio (GCA area%) and molar composition of the reactor outlet gas one hour after the start of the reaction, and the evaluation results of the powder state. 【0122】 【0123】 As shown in Table 3, even when the particle size of the silica sand was changed, the powdery state of the reactants was maintained in Examples 15 and 16, which used silicon oxide particles and fluorine-containing alkali metal salts as reactants. 【0124】 [Example 17] The HF removal reaction was carried out in the same manner as in Example 2, except that HFC-134a was replaced with HFC-143a. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0125】 [Example 18] The HF removal reaction was carried out in the same manner as in Example 17, except that potassium hexafluorosilicate was replaced with sodium hexafluorosilicate. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0126】 [Example 19] The HF removal reaction was carried out in the same manner as in Example 17, except that potassium hexafluorosilicate was replaced with cesium fluoride and the reaction was carried out at 600°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0127】 [Example 20] The HF removal reaction was carried out in the same manner as in Example 17, except that the potassium hexafluorosilicate and silica sand mixed in a mass ratio of 1 / 1 (70 g / 70 g) was replaced with potassium fluoride and silica sand mixed in a mass ratio of 3 / 7 (42 g / 98 g). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0128】 [Example 21] The HF removal reaction was carried out in the same manner as in Example 20, except that potassium fluoride and silica sand were mixed in a mass ratio of 1 / 9 (14 g / 126 g). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0129】 Table 4 shows the reaction conditions for Examples 17-21, the area ratio (GCA area%) and molar composition of the reactor outlet gas one hour after the start of the reaction, and the evaluation results of the powder state. 【0130】 【0131】 As shown in Table 4, even when the halogenated alkane used as a raw material was changed to HFC-143a, the powder state of the reactant was maintained in Examples 17-21, in which silicon dioxide particles and fluorine-containing alkali metal salts were used as reactants. 【0132】 (Outlet gas composition at specific reaction durations) The reactor outlet gas, taken at specific time intervals from the start of the reaction, was analyzed by gas chromatography using the method described above to determine the area ratio (GCA area%) and molar composition of the reactor outlet gas. 【0133】 (Percentage change in product amount for each reaction duration) The percentage of the amount of halide alkene produced at each reaction time was calculated, relative to the amount of halide alkene produced at 1 hour from the start of the reaction. Unless otherwise specified, the percentage change in the amount of halide alkene produced was calculated using the molar composition values ​​mentioned above. 【0134】[Example 1] For Example 1, the change rate of the outlet gas composition and production amount for each reaction duration was examined. The results are shown in Table 5. 【0135】 【0136】 [Example 22] The HF removal reaction was carried out in the same manner as in Example 1, except that sodium fluoride was replaced with potassium fluoride (KF) and the mass ratio of silica sand to potassium fluoride was set to 5 / 2. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Table 6 shows the change in the outlet gas composition and production amount for each reaction duration in Example 22. 【0137】 【0138】 [Example 23] The HF removal reaction was carried out in the same manner as in Example 1, except that silica sand and sodium fluoride were replaced with 140 g of γ-alumina (product name "N612", manufactured by JGC Catalysts & Chemicals Co., Ltd.). Table 7 shows the change in the outlet gas composition and production amount for each reaction duration in Example 23. 【0139】 Compared to Example 23 (Table 7) which uses γ-alumina, Example 1 (Table 5) which uses silica sand and sodium fluoride, and Example 22 (Table 6) which uses silica sand and potassium fluoride, show a significantly reduced decrease in the amount of product produced. Furthermore, in Examples 1 and 22, the concentration of HFO-1123 in the outlet gas composition is stably maintained. 【0140】 [Example 24] In Example 2, the reaction tube was changed to one with an inner diameter of 4.094 cm and a length of 80 cm, and a vibrometer was attached to the bottom of the reaction tube. The HF removal reaction was carried out in the same manner as in Example 2, except that the total mass of the reactants was changed from 140 g to 840 g, the total flow rate of the reaction gas was changed from 400 mL / min to 2400 mL / min, and the halogenated alkane used as a starting material was changed from HFC-134a to HFC-125. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. The composition of the outlet gas was analyzed 1 hour after the start of the reaction. In addition, the powder state of the reactants was visually checked 4 hours after the start of the reaction. The evaluation criteria for the powder state are as described above. 【0141】[Example 25] The HF removal reaction was carried out in the same manner as in Example 24, except that the reactant was changed to a mass ratio of silica sand and potassium fluoride (KF) of 9 / 1 (756 g / 84 g). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0142】 [Example 26] In Example 24, the reactants were silica sand and potassium hexafluorosilicate (K ２ SiF ６ The HF removal reaction was carried out in the same manner except that the mass ratio of ) and potassium fluoride (KF) was changed to 5:4:1 (420g, 336g, and 84g respectively). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0143】 [Example 27] The HF removal reaction was carried out in the same manner as in Example 24, except that the reactants were silica sand, sodium fluoride (NaF), and potassium fluoride (KF) in a mass ratio of 8:1:1 (672g, 84g, and 84g respectively), and the reaction temperature was changed to 600°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Note that the evaluation of the powder state in the table is based on the state 3 hours after the start of the reaction. 【0144】 [Example 28] The HF removal reaction was carried out in the same manner as in Example 27, except that the reactant was changed to a mass ratio of silica sand and potassium fluoride (KF) of 7 / 3 (588 g / 252 g). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Note that the evaluation of the powder state in the table is based on the state 4 hours after the start of the reaction. 【0145】 [Example 29] The HF removal reaction was carried out in the same manner as in Example 27, except that the reactants were changed to a mass ratio of silica sand, potassium fluoride (KF), and cesium fluoride (CsF) of 8:1:1 (672 g, 84 g, and 84 g respectively). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Note that the evaluation of the powder state in the table is based on the state 3 hours after the start of the reaction. 【0146】[Example 30] The HF removal reaction was carried out in the same manner as in Example 27, except that the reactant was changed to a 1 / 1 mass ratio of silica sand and potassium fluoride (KF) (420 g / 420 g). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Note that the evaluation of the powder state in the table is based on the reaction after 4 hours. 【0147】 [Example 31] The HF removal reaction was carried out in the same manner as in Example 27, except that the reactants were changed to silica sand, sodium fluoride (NaF), and potassium fluoride (KF) in a mass ratio of 5:1:4 (420g, 84g, and 336g respectively). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Note that the evaluation of the powder state in the table is based on the reaction after 4 hours. 【0148】 [Example 32] In Example 27, the reactants were silica sand and sodium hexafluorosilicate (Na ２ SiF ６ The HF removal reaction was carried out in the same manner, except that the mass ratio of ) and potassium fluoride (KF) was changed to 5:4:1 (420g, 336g, and 84g respectively). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Note that the evaluation of the powder state in the table is as of 4 hours after the start of the reaction. 【0149】 [Example 33] In Example 32, the reactants were silica sand and potassium hexafluorosilicate (K ２ SiF ６ The HF removal reaction was carried out in the same manner as before, except that the mass ratio of ) and potassium fluoride (KF) was 10:7:3 (420g, 294g, and 126g respectively), and the temperature was changed to 700°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Note that the evaluation of the powder state in the table is as of 3 hours after the start of the reaction. 【0150】 [Example 34] The HF removal reaction was carried out in the same manner as in Example 33, except that the reaction temperature was changed to 600°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Note that the evaluation of the powder state in the table is based on the state 3 hours after the start of the reaction. 【0151】[Example 35] The HF removal reaction was carried out in the same manner as in Example 26, except that the reaction temperature was changed to 600°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Note that the evaluation of the powder state in the table is based on the state 3 hours after the start of the reaction. 【0152】 [Example 36] The HF removal reaction was carried out in the same manner as in Example 30, except that the reaction temperature was changed to 650°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. The evaluation of the powder state in the table is as of 4 hours after the start of the reaction. In addition, the reactant was dried with nitrogen before the start of the experiment. The dew point measured before the start of the experiment (during drying) was -23°C. 【0153】 [Example 37] In Example 36, the reactant was not dried with nitrogen before the start of the experiment. The dew point before the start of the experiment was -3°C. Note that the evaluation of the powder state in the table is based on the state 4 hours after the start of the reaction. Although some of the reactant solidified during the heating process before the raw materials were distributed, the powder state 4 hours after the start of the reaction was rated B, and although a small amount had formed into clumps in some areas, it maintained a powder state. 【0154】 As shown in Tables 8 and 9, the powder state of the reactants was maintained even when two or more fluorine-containing alkali metal salts were used in combination. 【0155】 【0156】 A comparison of Example 36 and Example 37 shows that when a dry gas is passed through the reactant before the conversion reaction, the moisture content of the dry gas after the passage is 3 g / m³. ３ It can be seen that the powder state of the reactant is better maintained when dried as follows. 【0157】 [Example 38] The HF removal reaction was carried out in the same manner as in Example 30, except that the reaction temperature was changed to 700°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Note that the evaluation of the powder state in Table 11 is as of 3 hours after the start of the reaction. In addition, it was confirmed that localized superheating occurred in the internal temperature during the experiment. 【0158】[Example 39] The HF removal reaction was carried out in the same manner as in Example 38, except that the reactant was stirred during the reaction. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Note that the evaluation of the powder state in Table 11 is based on the state 21 hours after the start of the reaction. Furthermore, it was confirmed that no localized overheating of the internal temperature occurred during the experiment. 【0159】 【0160】 A comparison of Example 38 and Example 39 shows that stirring during the reaction suppresses localized overheating inside the reaction tube and maintains the powder state more effectively. 【0161】 [Example 40] The HF removal reaction was carried out in the same manner as in Example 24, except that the reactant was amorphous silica and potassium fluoride (KF) in a mass ratio of 65 / 35 (546 g / 294 g), the flow gas was changed from HFC-125 to HFC-134a, and the experiment was conducted under stirring conditions. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Table 12 shows the change in the outlet gas composition and amount produced for each reaction duration in Example 40. The powder state of the reactant after 7 hours of reaction was A (good). 【0162】 【0163】 [Example 41] The HF removal reaction was carried out in the same manner as in Example 40, except that the reactant was silica sand and potassium fluoride (KF) in a mass ratio of 50 / 50 (420 g / 420 g). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Table 13 shows the change in the outlet gas composition and amount produced for each reaction duration in Example 41. The powder state of the reactant after 5 hours of reaction was A (good). 【0164】 【0165】[Example 42] The HF removal reaction was carried out in the same manner as in Example 41, except that the reaction temperature was set to 730°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Table 14 shows the change in the outlet gas composition and amount produced for each reaction duration in Example 42. The powder state of the reactant after 12 hours of reaction was A (good). 【0166】 【0167】 [Example 43] The HF removal reaction was carried out in the same manner as in Example 42, except that the reactant was silica sand and potassium fluoride (KF) in a mass ratio of 65 / 35 (546 g / 294 g). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Table 15 shows the change in the outlet gas composition and amount produced for each reaction duration in Example 43. The powder state of the reactant after 12 hours of reaction was A (good). 【0168】 【0169】 [Example 44] The HF removal reaction was carried out in the same manner as in Example 43, except that the nitrogen was not diluted by 50%, and 100% HFC-134a was passed through. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Table 16 shows the change in the outlet gas composition and amount produced for each reaction duration in Example 44. The powder state of the reactant after 15 hours of reaction was A (good). 【0170】 【0171】 The disclosure of Japanese Patent Application No. 2024-218146 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. A method for producing a halogenated alkene, comprising converting a halogenated alkane containing a fluorine atom and having 2 to 4 carbon atoms into a halogenated alkene containing a fluorine atom and having 2 to 4 carbon atoms in the gas phase, in the presence of silicon oxide particles and a fluorine-containing alkali metal salt.

2. A method for producing an alkene halide according to claim 1, wherein the conversion is carried out in an atmosphere with an oxygen content of 10,000 ppm by mass or less.

3. The method for producing alkene halogens according to claim 1 or 2, wherein the fluorine-containing alkali metal salt has a thermal decomposition temperature of 100°C or higher.

4. The method for producing a halogenated alkene according to claim 1 or 2, wherein the fluorine-containing alkali metal salt has a melting point of 400°C or higher.

5. Before the conversion reaction, a dry gas is passed through the reactant, and the moisture content of the dry gas after the passage is 3 g / m³. ３ A method for producing an alkene halogenate according to claim 1 or 2, wherein the alkene halogenate is dried to the following extent.

6. A method for producing an alkene halide according to claim 1 or 2, wherein silicon tetrafluoride is produced.

7. A method for producing a halogenated alkene according to claim 1 or 2, comprising: generating the halogenated alkene and hydrogen fluoride in the gas phase by a dehydrofluorination reaction of the halogenated alkane; and generating silicon tetrafluoride by a reaction between the generated hydrogen fluoride and silicon oxide.

8. The fluorine-containing alkali metal salts are NaF, KF, and K ２ SiF ６ LiF, CsF, and Na ２ SiF ６ A method for producing a halogenated alkene according to claim 1 or 2, comprising at least one selected from the group consisting of the following.

9. The method for producing a halogenated alkene according to claim 1 or 2, wherein the halogenated alkane contains a halogenated alkane represented by the following formula (1), and the halogenated alkene contains a halogenated alkene represented by the following formula (2). CR １ R ２ X １ -CR ３ R ４ X ２ ・・・(1) CR １ R ２ =CR ３ R ４ ・・・(2) In formulas (1) and (2), R １ ~R ４ are each independently a hydrogen atom, a fluorine atom, a methyl group, a fluorinated methyl group, an ethyl group, or a fluorinated ethyl group, and the total number of fluorine atoms of R １ ~R ４ is 1 or more, and the number of carbon atoms is 2 to 4. In formula (1), X １ and X ２ are such that one is a hydrogen atom and the other is a fluorine atom.

10. A method for producing a halogenated alkene according to claim 1 or 2, wherein the halogenated alkane is converted at a temperature of 400 to 1000°C.

11. The method for producing a halogenated alkene according to claim 1 or 2, wherein the conversion reaction is carried out in a fluidized bed reactor.

12. The method for producing a halogenated alkene according to claim 1 or 2, wherein the conversion reaction is carried out while stirring silicon oxide particles and a fluorine-containing alkali metal salt.

13. A method for producing silicon tetrafluoride, comprising contacting a halogenated alkane containing fluorine atoms and having 2 to 4 carbon atoms with silicon oxide particles and a fluorine-containing alkali metal salt in the gas phase to produce silicon tetrafluoride.

14. A method for producing silicon tetrafluoride according to claim 13, comprising: generating a halogenated alkene and hydrogen fluoride in the gas phase by a dehydrofluorination reaction of the halogenated alkane; and generating silicon tetrafluoride by a reaction between the generated hydrogen fluoride and silicon oxide.

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