Method for producing halogenated alkene and method for producing silicon tetrafluoride

Abstract

A method for producing a halogenated alkene, the method comprising converting a halogenated alkane represented by formula (1) into a halogenated alkene represented by formula (2) and a compound represented by formula (3) in a gas phase in the presence of silicon oxide and an alkali metal element. R1-R3 each independently represent a hydrogen atom, a fluorine atom, a methyl group, a fluorinated methyl group, an ethyl group, or a fluorinated ethyl group, and the number of carbon atoms in each of formulae (1)-(3) is 2-4.

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】 The reaction to obtain alkenes from alkanes is a reaction that removes HF (hydrogen fluoride) and fluorine. ２ Because reactions can occur, high selectivity of the reaction products is required, and in particular, it is desirable to improve the proportion of the target product, the HF removal reaction product. ２ One object of this embodiment is to provide a method for producing halogenated alkenes that improves the proportion of HF-removed reaction products in the total reaction products. 【0006】 This disclosure includes the following aspects: <1> A method for producing alkenes with halides, in the gas phase, in the presence of silicon oxide and alkali metal elements, converting an alkane with a halide represented by formula (1) to an alkene with a halide represented by formula (2) and a compound represented by formula (3). In formulas (1) to (3), R １ ~R ３is independently a hydrogen atom, a fluorine atom, a methyl group, a fluorinated methyl group, an ethyl group, or a fluorinated ethyl group, and the number of carbon atoms in the halogenated alkane represented by formula (1), the halogenated alkene represented by formula (2), and the compound represented by formula (3) is 2 to 4. <2> The method for producing a halogenated alkene according to <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 a halogenated alkene according to <1> or <2>, wherein silicon tetrafluoride is generated. <4> The method for producing a halogenated alkene according to any one of <1> to <3>, wherein the molar ratio of the halogenated alkene represented by formula (2) to the compound represented by formula (3) at 1 hour from the start of the reaction is 10 or more. <5> The method for producing a halogenated alkene according to any one of <1> to <4>, wherein the alkali metal element is at least one selected from the group consisting of Li, Na, K, Rb, and Cs. <6> The method for producing a halogenated alkene according to any one of <1> to <5>, wherein the alkali metal element is at least one selected from the group consisting of Na, K, and Cs. <7> The method for producing a halogenated alkene according to any one of <1> to <6>, wherein the alkali metal element is contained as an alkali metal salt, and the anion of the alkali metal salt contains at least one selected from the group consisting of F － , SiF ６ ２－ , Cl － and CO ３ ２－ . <8> The method for producing a halogenated alkene according to <7>, wherein the anion of the alkali metal salt is at least one selected from the group consisting of F － and SiF ６ ２－ . <9> The method for producing a halogenated alkene according to <7>, wherein the alkali metal salt contains at least one selected from the group consisting of CsF, K ２ CO ３ , KF, K ２ SiF ６ , Na ２ SiF ６ , NaF, and LiF. <10> The alkali metal salt is CsF, K ２CO ３ ,KF,K ２ SiF ６ Na ２ SiF ６ A method for producing a halogenated alkene according to <7>, comprising at least one selected from the group consisting of and NaF. <11> A method for producing a halogenated alkene according to any one of <1> to <10>, wherein the silicon dioxide is contained as silicon dioxide particles. <12> A method for producing a halogenated alkene according to any one of <1> to <11>, wherein the halogenated alkane is converted at a temperature of 450 to 1000°C. <13> A method for producing a halogenated alkene according to any one of <1> to <12>, wherein the conversion reaction is carried out in a fluidized bed reactor. <14> A method for producing silicon tetrafluoride, wherein in the gas phase, a halogenated alkane represented by the following formula (1) is brought into contact with silicon dioxide and an alkali metal element to produce silicon tetrafluoride. In formula (1), R １ ~R ３ 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 the number of carbon atoms in the halogenated alkane represented by formula (1) is 2 to 4. <15> A method for producing silicon tetrafluoride according to <14>, comprising: in the gas phase, a dehydrofluorination reaction of the halogenated alkane represented by formula (1) to produce a halogenated alkene and hydrogen fluoride represented by the following formula (2); and a reaction between the produced hydrogen fluoride and silicon oxide to produce silicon tetrafluoride. In formula (2), R １ and R ２ 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 the number of carbon atoms in the halide alkene represented by formula (2) is 2 to 4. 【0007】 According to this disclosure, the HF removal reaction product and the HF removal ２ A method for producing halogenated alkenes and a method for producing silicon tetrafluoride are provided, which improve the proportion of de-HF reaction products in the total reaction products. 【0008】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. 【0009】 [Method for producing halogenated alkenes] The method for producing halogenated alkenes according to the present disclosure is a method of converting a halogenated alkane represented by the following formula (1) into a halogenated alkene represented by the following formula (2) and a compound represented by the following formula (3) in the gas phase in the presence of silicon oxide and an alkali metal element. 【0010】 【0011】 In formulas (1) to (3), R １ ~R ３ 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 the number of carbon atoms in the halogenated alkanes represented by formula (1), the halogenated alkenes represented by formula (2), and the compounds represented by formula (3) is 2 to 4. 【0012】 Hereinafter, "halogenated alkanes represented by formula (1)" will also be referred to as "specific halide alkanes," and "halogenated alkenes represented by formula (2) and compounds represented by formula (3)" will also be referred to as "specific products." Furthermore, silicon dioxide and alkali metal elements will be collectively referred to as "reactants." 【0013】 The reaction to obtain alkenes from alkanes involves a dehydrofluorination reaction and a dehydrofluorination reaction. ２Although a reaction may occur, when a halogenated alkane represented by formula (1) is used as the halogenated alkane and reacted in the gas phase in the presence of the reactant according to this disclosure, the removal of F ２ The dehydrofluorination reaction is more dominant than the reaction, and the dehydrofluorination product and the dehydrofluorination product are obtained. ２ The proportion of HF removal reaction products in the total reaction products increases. 【0014】 Furthermore, the method for producing halogenated alkenes according to this disclosure has the following advantages. In the reaction to obtain a halogenated alkene containing a fluorine atom from a halogenated alkane containing a fluorine atom, hydrogen fluoride is generated. The generated hydrogen fluoride is then used as a catalyst, for example, 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 on the catalyst surface. This coating of the catalyst's reaction sites causes a rapid decrease in catalyst activity and a reduction in the amount of product produced. 【0015】 In contrast, the method for producing alkene halides according to this disclosure yields a specific product from a specific alkane halide in the gas phase in the presence of silicon oxide and an alkali metal element. In this process, the generated hydrogen fluoride reacts with silicon oxide, or the specific alkane halide reacts directly with silicon oxide and the alkali metal element, and regardless of the reaction scheme, silicon tetrafluoride (SiF) is produced. ４) can be generated. Since the boiling point of silicon tetrafluoride is -95°C, it is a gas in the reaction system and is released outside the reaction system. Therefore, in the method for producing halogenated alkenes of this disclosure, it is thought that the coating of silicon oxide particles with by-products is suppressed and the deterioration of the reactant over time is suppressed. ４ It may also be a substance that produces silicon fluoride other than ). 【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. The specific halide alkanes are halide alkanes represented by the following formula (1). The specific halide alkanes may be used alone or in combination of two or more. 【0018】 【0019】 In formula (1), R １ ~R ３ 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 the number of carbon atoms in the halogenated alkane represented by formula (1) is 2 to 4. 【0020】 R １ ~R ３ These are, independently, a hydrogen atom, a fluorine atom, and CH4. ３ ,CH ２ F, CHF ２ or CF ３ It is preferable that this be the case. 【0021】The specific halogenated alkane has 2 to 4 carbon atoms, and may be 2, 3, or 4. From the viewpoint of the boiling point range when the specific product is used as a refrigerant, the specific halogenated alkane has 2 or 3 carbon atoms. The specific halogenated alkane contains fluorine atoms. The number of fluorine atoms in the specific halogenated alkane is preferably 2 or more. The number of hydrogen atoms in the specific halogenated alkane is preferably 1 or more. The specific halogenated alkane may 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 halogenated alkane does not have to contain other halogen atoms. 【0022】 Among the specific 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), and 1,1,2,3-tetrafluoropropane (CHF ２ CHFCH ２ At least one selected from the group consisting of F, HFC-254ea) is mentioned. 【0023】 Among the specific halogenated alkanes represented by formula (1), the fluorinated halogenated alkanes having 4 carbon atoms include 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 ), and 1,1,1,2,2,3,4,4,4-nonafluorobutane (CF ３ CF ２ CHFCF ３ ), and at least one selected from the group consisting of them. 【0024】 The halogenated alkane represented by formula (1) may also be the following compounds. CH ２ FCH ２ F: 1,2-difluoroethane (HFC-152) 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) 【0025】 The halide alkane in the raw material may also include other halide alkanes other than the specified halide alkane (provided that it contains a fluorine atom and has 2 to 4 carbon atoms). Examples of other halide alkanes include those represented by the following formula (4). 【0026】 In formula (4), R １ and R ３ 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 the number of carbon atoms in the halide alkane represented by formula (4) is 2 to 4. In formula (4), R １ and R ３ R in equation (1) is １ and R ３ It is synonymous with [the above]. 【0027】 As an example of a halogenated alkane represented by formula (4), CHF ２ CH ３ : 1,1-difluoroethane (HFC-152a), CF ３ CH ３ Examples include 1,1,1-trifluoroethane (HFC-143a). 【0028】 As a raw material, the proportion of specific halide alkanes to the total amount of halide alkanes is preferably 30 mol% or more, and more preferably 50 mol% or more. 【0029】 (Specific Products) The method for producing the halide alkene of this disclosure yields the halide alkene represented by formula (2) and the compound represented by formula (3). Other compounds other than the halide alkene represented by formula (2) and the compound represented by formula (3) may also be included. 【0030】 【0031】 In equations (2) and (3), R １ ~R ３Each 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 the number of carbon atoms in the halogenated alkene represented by formula (2) and the compound represented by formula (3) is 2 to 4. In formulas (2) and (3), R １ ~R ３ R in equation (1) is １ ~R ３ It is synonymous with [the above]. 【0032】 The compound represented by formula (3) may be an alkene halide, or it may be a compound that does not contain halogens. 【0033】 Among the halogenated alkenes represented by formula (2), the halogenated alkene with 3 carbon atoms 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. 【0034】 Among the halogenated alkenes represented by formula (2), the halogenated alkene having 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 CF2CF = 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. 【0035】 The following compounds may be used as the alkene halide represented by formula (2) and the compound represented by formula (3): 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) CH ２ =CH ２ :ethylene 【0036】 In particular, the halogenated alkene represented by formula (2) and the compound represented by formula (3) are 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. 【0037】 In the method for producing halogenated alkenes disclosed herein, F removal ２ Since the de-HF reaction is more prevalent than the reaction, the molar amount of the halide alkene represented by formula (2) produced is greater than the molar amount of the compound represented by formula (3) produced. In the method for producing halide alkenes according to this disclosure, the molar ratio of the halide alkene represented by formula (2) to the compound represented by formula (3) at 1 hour from the start of the reaction is preferably 5 or more, more preferably 7 or more, and even more preferably 10 or more. There is no particular upper limit to this molar ratio, but it may be 200 or less, or 100 or less. 【0038】 (Reagents) In the method for producing halogenated alkenes according to the present disclosure, a specific halogenated alkane is converted to a specific product in the presence of the reagents according to the present disclosure. The reagents according to the present disclosure include silicon dioxide particles and fluorine-containing alkali metal salts. 【0039】By using a reagent containing silicon dioxide and alkali metal elements, the HF removal reaction product and fluorine removal can be achieved. ２ The proportion of HF-removing reaction products in the total reaction products is improved. For example, a reagent containing silicon dioxide and alkali metal elements produces more HF-removing reaction products and HF-removing reaction products compared to reagents containing alkaline earth metal elements or iron powder, etc. ２ The proportion of HF removal reaction products in the total reaction products increases. 【0040】 Furthermore, by using a reagent containing silicon dioxide and alkali metal elements, the degradation of the reagent over time is suppressed compared to an alumina catalyst. 【0041】 The alkali metal element is preferably at least one selected from the group consisting of Li, Na, K, Rb, and Cs, and more preferably at least one selected from the group consisting of Na, K, and Cs. 【0042】Silicon oxide and alkali metal elements may be an integrated compound or composite containing both, or separate substances containing silicon oxide and alkali metal elements separately may be used, or two or more of these may be used in combination. Examples of integrated compounds or composites include glass containing silicon oxide and alkali metal oxides, sodium silicate, sodium silicate cullet, etc., in which an alkali metal-containing compound is supported on silicon oxide particles. Furthermore, solar panels can be used as integrated compounds or composites, and used solar panels may also be used. The method of using used solar panels in the method of producing halogenated alkenes of this disclosure can be said to be a new recycling method for waste solar panels, which are generally considered difficult to recycle. Because solar panels contain multiple metal components, they are difficult to recycle as glass, and furthermore, because they contain toxic metal components, landfill disposal is also difficult. For this reason, the processing of used solar panels is a major challenge. In the method of producing halogenated alkenes of this disclosure, silicon oxide contained in used solar panels can be used as a reactant, and silicon can be extracted from the system in the form of silicon tetrafluoride. Converting extracted silicon tetrafluoride into silicon oxide allows for reuse as a glass raw material, as well as conversion into other valuable materials. Furthermore, it is expected to contribute to reducing the volume of waste by decreasing the silicon oxide content in the waste. The ability to use used solar panels as a reagent offers environmental advantages. Examples of using separate substances containing silicon oxide and alkali metal elements include the combined use of silicon oxide particles and alkali metal-containing compounds. 【0043】 When silicon dioxide and alkali metal elements are integrated, their uneven distribution within the reaction system is easily suppressed. On the other hand, when silicon dioxide and alkali metal-containing compounds are used as separate substances, it is easier to prepare highly pure versions of each, and the generation of unwanted by-products in the reaction is easily suppressed. When silicon dioxide and alkali metal-containing compounds are used as separate substances, it is sufficient for the silicon dioxide particles and fluorine-containing alkali metal salt to be separate raw materials, and the fluorine-containing alkali metal salt may then adhere to the silicon dioxide particles and become integrated. 【0044】 Alkali metal elements may be included as alkali metal salts. The anion of the alkali metal salt is F － , SiF ６ ２－ , Cl － and CO ３ ２－ Preferably, it includes at least one selected from the group consisting of F － and SiF ６ ２－ It is more preferable that it be at least one selected from the group consisting of the following: 【0045】 The alkali metal-containing compound is preferably an alkali metal-containing compound containing fluorine, and more preferably an alkali metal salt containing fluorine. When the alkali metal-containing compound contains fluorine, a fluorine-free reaction product and a fluorine-free reaction product are produced. ２ The proportion of HF-dehydrogenated reaction products in the total reaction products tends to increase. The reason for this is not clear, but it is speculated as follows: When the generated hydrogen fluoride reacts with the reactant and the reactant is fluorinated, it may form lumps. However, when an alkali metal-containing compound that originally contains fluorine is used, the alteration is suppressed even if fluorination occurs, and the lumping of the reactant is suppressed. Therefore, it is thought that localized overheating due to lumping is suppressed, and the occurrence of unwanted side reactions is suppressed. 【0046】 Examples of alkali metal salts include CsF and K ２ CO ３ ,KF,K ２ SiF ６ Na ２ SiF ６ Preferably, it contains at least one selected from the group consisting of NaF and LiF, and CsF, K ２ CO ３ ,KF,K ２ SiF ６ Na ２ SiF ６ It is more preferable to include at least one selected from the group consisting of , and NaF, and CsF, K ２ CO ３ ,KF,K ２ SiF ６, and Na ２ SiF ６ It is even more preferable to include at least one selected from the group consisting of the following. When these alkali metal salts are used, the HF removal reaction product and the HF removal reaction product are ２ The proportion of HF removal reaction products in the total reaction products tends to increase. 【0047】 The shape of the glass is not particularly limited and may be irregular in shape, such as crushed material, cullet, flakes, or spheres. It may also be molded into pellets, hollow shapes, cylindrical shapes, etc. These shapes may be combined as appropriate. 【0048】 In composite materials or combined use as separate substances, silicon dioxide particles may be in a crystalline state (such as silica sand) or an amorphous state (such as amorphous silica). Examples of silicon dioxide particles include silica sand, quartz, diatomaceous earth, colloidal silica, precipitated silica, silica gel, fumed silica, amorphous silica, and rice husks, with silica sand being preferred from the viewpoint of purity and cost. 【0049】 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. 【0050】 The silicon dioxide particles preferably 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 is preferably low, preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. 【0051】From the viewpoint of suppressing clogging in the reactor, the average particle size of the glass, composite, and silicon dioxide particles at the time of reaction addition 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 the glass, composite, and silicon dioxide particles at the time of reaction addition is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 1 mm or less. 【0052】 The average particle size of glass, composites, and silicon dioxide particles is determined as the particle size (D50) at which the cumulative weight 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. 【0053】 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. 【0054】 The content of each element in the reactant is determined by scanning electron microscopy energy-dispersive X-ray spectroscopy (SEM-EDX analysis). 【0055】 The reactant may contain components other than silicon dioxide and alkali metal elements. Examples of other components include calcium, aluminum, magnesium, iron, boron, lead, and zinc. 【0056】In the reactant, the silicon content (atm%) is preferably greater than the alkali metal element content (atm%), and is preferably greater than the total content of alkaline earth metal elements, Group 13 elements of the periodic table, and iron powder. 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 greater 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). 【0057】 (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 product and hydrogen fluoride are produced by the de-HF (hydrogen fluoride) reaction of the halogenated alkane represented by formula (1) (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 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 be produced. 【0058】 Below, we present an example of a reaction scheme in which a halogenated alkane represented by formula (1) yields a halogenated alkene represented by formula (2) and silicon tetrafluoride. 【0059】 【0060】 Since the generated silicon tetrafluoride is a gas, it is released from the reaction system. Therefore, the influence of by-products on the reactants is suppressed, and the rapid decrease in the amount of alkene halide produced is prevented. 【0061】In conventional manufacturing methods using alumina, calcium carbonate, etc. as catalysts, the generated hydrogen fluoride reacts with the catalyst as follows. 【0062】 【0063】 The generated aluminum fluoride (AlF ３ ) and calcium fluoride (CaF ２ Since 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. 【0064】 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. 【0065】 Furthermore, when the reaction is carried out in a fluidized bed, it is desirable that the fluidity of the catalyst does not change significantly, but in conventional methods, the catalyst is AlF ３ or CaF ２Because 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 it is a gas and is released outside the reaction system, there is no significant change in the fluidity of silicon dioxide particles, making it easy to maintain an appropriate flow state. 【0066】 (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. Furthermore, the raw material gas may also contain halogenated alkanes other than the specific halogenated alkane (for example, fluoromethanes, halogenated alkanes represented by formula (4)). 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. 【0067】 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. 【0068】The reactant may be contained in a fixed-bed, fluidized-bed, or moving-bed reactor. If it is a fixed-bed reactor, it may be either a horizontal or vertical fixed-bed reactor. The reactor may rotate as a whole. The reaction mode may be a flow-through or batch mode. From the viewpoint of suppressing explosion due to pressure rise, a flow-through reaction mode is preferred. 【0069】 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 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 ensure 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. The method for producing alkene halides according to this disclosure is preferable to use a fluidized-bed reactor from the viewpoint of suppressing unwanted side reactions caused by localized overheating. Localized overheating can accelerate side reactions of the product. 【0070】 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. 【0071】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 extracted 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. 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. Furthermore, from the viewpoint of preventing uneven flow of gas within 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 that it be made of a material with low reactivity with the raw material gas, product gas, etc. Examples of materials for the gas dispersion plates include sintered metal. The size, placement, and number of gas dispersion plates may be adjusted as appropriate according to the gas flow. The fluidized bed reactor may be equipped with vibrators or knockers to improve fluidity. 【0072】 In the method for producing halogenated alkenes according to this disclosure, the halogenated alkane is preferably converted at a temperature of 450 to 1000°C, more preferably at 450 to 900°C, and even more preferably at 500 to 800°C. When converted at 450°C or higher, the reaction proceeds appropriately and the conversion rate to a specific product 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. 【0073】 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. 【0074】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. 【0075】 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. 【0076】 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. 【0077】 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. 【0078】 The residence time (seconds) is calculated using the following formula: Residence time (seconds) = [Length (cm) in the reactor where the reactant is packed and heated to the set temperature] / [Linear velocity (cm / second)] Linear velocity refers to the rate at which the halide alkane passes through the reactant per unit time. 【0079】 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 ３The 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. 【0080】 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 or higher, and more preferably 0.5 or higher. There is no particular upper limit to the above molar ratio, and it may be 5.0 or lower, 3.0 or lower, or 2.0 or lower. 【0081】In general, in methods for producing alkene halides, diluent gases are used to suppress disproportionation reactions caused by high concentrations of the resulting 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 a specific product in the outlet gas can be controlled by these controls. In the method for producing alkene halides of this disclosure, the amount of alkene produced can be maintained and kept within a certain range by the above controls, so that the outlet gas can contain a certain amount or more of the specific alkane used as a raw material. The specific alkane in the outlet gas also functions 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. 【0082】 Furthermore, in the method for producing hydrofluoroolefins 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 alkane has a higher boiling point and a different boiling point range than 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. 【0083】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 reaction system. Furthermore, when hydrogen fluoride is desorbed from the raw material, or when hydrogen fluoride reacts with silicon oxide, 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, the resulting silicon tetrafluoride reacts with water near the outlet to produce hexafluorosilicic acid, silicon oxide, etc., and from the viewpoint of suppressing blockage of the gas flow path due to this precipitation, it is preferable to keep the water concentration below the above range. 【0084】 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. 【0085】 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. 【0086】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. 【0087】 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. 【0088】 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. 【0089】 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. 【0090】 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. 【0091】Generally, a higher conversion rate is preferable from the viewpoint of productivity. However, in the case of halogenated alkenes, which 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 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. 【0092】 In this disclosure, selectivity refers to the ratio (mol %) of the molar amount of the specific 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 element of the specific halide alkane that is the raw material; excluding compounds such as silicon tetrafluoride that do not have the carbon element 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 necessary 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. 【0093】 Compounds other than the raw material compounds and specific products contained in the reactor outlet gas include, for example, carbon monoxide, carbon dioxide, water, silicon tetrafluoride, and the like. 【0094】 The method for producing halogenated alkenes according to this disclosure suppresses the decrease in the amount of specific products (particularly the halogenated alkene represented by formula (2)) produced during long-term production (specifically, 5 hours or more). The amount of specific products 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 products produced after 1 hour. 【0095】 The amount produced is determined by analyzing the reactor outlet gas using gas chromatography and calculating the area ratio (GCAare%) corresponding to the specific product. 【0096】[Method for Producing Silicon Tetrafluoride] The method for producing silicon tetrafluoride according to this disclosure involves contacting a halogenated alkane represented by formula (1) with silicon oxide and an alkali metal element 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. Therefore, the halogenated alkane represented by formula (1), silicon oxide, and alkali metal element in the method for producing silicon tetrafluoride according to this disclosure are synonymous with the halogenated alkane represented by formula (1), silicon oxide, and alkali metal element in the above-mentioned method for producing halogenated alkenes according to this disclosure. 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 a halogenated alkene represented by formula (2) and hydrogen fluoride by a dehydrofluorination reaction of a halogenated alkane represented by formula (1), and generating silicon tetrafluoride by a reaction between the generated hydrogen fluoride and silicon oxide. 【0097】 The generated silicon tetrafluoride can be used as a raw material for semiconductor silicon, a raw material for solar cells, a raw material for the manufacture of high-performance optical fibers, and a gas for semiconductor manufacturing. 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 such as chlorodifluoromethane and tetrafluoroethane. 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. 【0098】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 1-7, 11-17, 19, and 20 are examples, Examples 8-10 and 21 are comparative examples, and Example 18 is a reference example. 【0099】 (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. 【0100】 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%. 【0101】 Furthermore, the mole percentage values ​​listed in the table below have been rounded to the nearest significant figure, so the mole ratio calculated from the mole percentage values ​​listed in the table may differ slightly from the mole ratio listed in the table. For example, in Example 2 of Table 1, the actual mole percentages of HFO-1132a and HFO-1123 displayed by the measuring device are 0.133 mol% and 7.33 mol%, respectively, so the mole ratio is expressed as 7.33 / 0.133 = 55. As the mole ratios listed in the table are calculated using the mole percentage values ​​before rounding, the mole ratios in the examples should be those listed in the table, not those calculated from the mole percentage values ​​listed in the table. The same applies to examples other than Example 2. 【0102】[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 lithium fluoride (LiF) mixed in a mass ratio of 2 / 1 (70 g / 35 g) (35 g silica sand, 70 g lithium fluoride (LiF); in the following examples, the mass ratio of the reactants will be described with the former as the numerator and the latter as the denominator) 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 oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0103】 [Example 2] The HF removal reaction was carried out in the same manner as in Example 1, except that the silica sand and lithium fluoride (LiF) mixed in a mass ratio of 2 / 1 (70 g / 35 g) was replaced with silica sand and sodium fluoride (NaF) mixed in a mass ratio of 1 / 1 (70 g / 70 g). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0104】 [Example 3] In Example 2, 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. 【0105】 [Example 4] The HF removal reaction was carried out in the same manner as in Example 2, except that sodium fluoride was replaced with potassium fluoride (KF). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0106】 [Example 5] In Example 2, 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. 【0107】 [Example 6] In Example 2, sodium fluoride is replaced with potassium carbonate (K ２ CO ３The 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. 【0108】 [Example 7] The HF removal reaction was carried out in the same manner as in Example 2, except that sodium fluoride was replaced with cesium fluoride (CsF) and the internal temperature was set to 600°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0109】 [Example 8] In Example 1, lithium fluoride is replaced with magnesium fluoride (MgF ２ 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. 【0110】 [Example 9] In Example 2, sodium fluoride is replaced with calcium fluoride (CaF ２ The HF removal reaction was carried out in the same manner, except that the internal temperature was set to 615°C. 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 1, except that the mixture of silica sand and lithium fluoride was replaced with a mixture of hydrochloric acid-treated magnesium (10 g) and silica sand (100 g). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0112】 Tables 1 and 2 show the reaction conditions for Examples 1 to 10. Tables 1 and 2 also show the area ratio (GCA area%), mole percentage, and molar ratio of the reactor outlet gas one hour after the start of the reaction. 【0113】 【0114】 【0115】 As shown in Tables 1 and 2, Examples 1 to 7, which use silicon dioxide and alkali metal elements as reactants, have a higher molar ratio of HFO-1123 to HFO-1132a in the outlet gas composition compared to Examples 8 to 10, which do not use alkali metal elements, resulting in a higher HF removal reaction product and HF removal. ２ It can be seen that the proportion of HF removal reaction products in the total reaction products has improved. 【0116】 [Example 11] The HF removal reaction was carried out in the same manner as in Example 4, except that the reaction temperature was changed to 550°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0117】 [Example 12] The HF removal reaction was carried out in the same manner as in Example 4, 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. 【0118】 [Example 13] The HF removal reaction was carried out in the same manner as in Example 4, 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. 【0119】 [Example 14] The HF removal reaction was carried out in the same manner as in Example 7, except that the reaction temperature was changed to 450°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0120】 [Example 15] The HF removal reaction was carried out in the same manner as in Example 7, except that the reaction temperature was changed to 500°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0121】 [Example 16] The HF removal reaction was carried out in the same manner as in Example 7, except that the reaction temperature was changed to 550°C. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0122】 [Example 17] The HF removal reaction was carried out in the same manner as in Example 7, 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. 【0123】 Table 3 shows the reaction conditions for Examples 11 to 17. Table 3 also shows the area ratio (GCA area%), mole percentage, and molar ratio of the reactor outlet gas one hour after the start of the reaction. The reaction conditions for Examples 4 and 7 are also included in Table 3. 【0124】 【0125】As shown in Table 3, the amount of the target product (HF removal reaction product), HFO-1123, increases as the reaction temperature increases, but impurities (HF removal) are removed. ２ It can be seen that the production of HFO-1132a, a reaction product, also increases. ２ From the viewpoint of reducing reaction products, a lower reaction temperature is preferable, but from the viewpoint of maintaining the amount of the target product HFO-1123 produced, a reaction temperature of 450°C or higher is preferable. 【0126】 Furthermore, as shown in Table 3, even when the reaction temperature is changed, in Examples 11 to 17, which use silicon dioxide and alkali metal elements as reactants, the molar ratio of HFO-1123 to HFO-1132a in the outlet gas composition is high, and the HF removal reaction product and HF removal are high. ２ It can be seen that the proportion of HF removal reaction products in the total reaction products has improved. 【0127】 [Example 18] The HF removal reaction was carried out in the same manner as in Example 1, except that HFC-134a was replaced with HFC-152a, the reaction temperature was set to 700°C, and the reactant was changed to a mixture of silica sand (120 g) and potassium fluoride (20 g). The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. 【0128】 【0129】 In Table 4, the HFO-1141 / ethylene ratio is calculated from the area ratio (GC Area%) of the reactor outlet gas. 【0130】 As shown in Table 4, even when the starting material halogenated alkane is changed to HFC-152a, when a reagent containing silicon dioxide and alkali metal elements is used, the molar ratio of HFO-1141 to ethylene is high, resulting in a de-HF reaction product and de-F reaction product. ２ It can be seen that the proportion of HF removal reaction products in the total reaction products has improved. 【0131】 [Example 19] 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. 【0132】 【0133】 As shown in Table 5, even when the starting material halogenated alkane is changed to HFC-125, when a reagent containing silicon dioxide and alkali metal elements is used, the molar ratio of HFO-1114 to HFO-1123 is high, resulting in a de-HF reaction product and de-F reaction product. ２ It can be seen that the proportion of HF removal reaction products in the total reaction products has improved. 【0134】 (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. 【0135】 (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 mol% values ​​mentioned above. 【0136】 [Example 2] For Example 2, the rate of change in the outlet gas composition and production amount for each reaction duration was examined. The results are shown in Table 6. 【0137】 【0138】 [Example 20] The HF removal reaction was carried out in the same manner as in Example 4, except that the mass ratio of silica sand to potassium fluoride was 5 / 2. The oxygen content in the reaction atmosphere was 10,000 ppm by mass or less. Table 7 shows the change in the outlet gas composition and production amount for each reaction duration in Example 20. 【0139】 【0140】 [Example 21] The HF removal reaction was carried out in the same manner as in Example 1, except that 140 g of γ-alumina (product name "N612", manufactured by JGC Catalysts & Chemicals Co., Ltd.) was used instead of silica sand and lithium fluoride. Table 8 shows the change in the outlet gas composition and production amount for each reaction duration in Example 21. 【0141】Compared to Example 21 (Table 8) which uses γ-alumina, Example 2 (Table 6) which uses silica sand and sodium fluoride, and Example 20 (Table 7) which uses silica sand and potassium fluoride, show a significantly reduced decrease in the amount of product produced. Furthermore, in Examples 2 and 20, the concentration of HFO-1123 in the outlet gas composition is stably maintained. 【0142】 [Example 22] In Example 4, 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 reaction was carried out in the same manner as in Example 4, 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, the mass ratio of the reactants (amorphous silica and potassium fluoride (KF)) was changed to 65 / 35 (546 g / 294 g), and the reaction temperature was changed to 730 °C. Table 9 shows the results of the outlet gas composition one hour after the start of flow. 【0143】 [Example 23] The reaction was carried out in the same manner as in Example 22, except that amorphous silica in the reactant was replaced with silica sand (crystalline). Table 9 shows the results of the outlet gas composition one hour after the start of flow. 【0144】 【0145】 [Example 24] The HF removal reaction was carried out in the same manner as in Example 10, except that the mixture of silica sand and magnesium was replaced with a mixture of iron powder (40 g) and silica sand (100 g). Table 10 shows the results of the outlet gas composition one hour after the start of flow. 【0146】 [Example 25] The HF removal reaction was carried out in the same manner as in Example 24, except that the reaction temperature was set to 750°C. Table 10 shows the results of the outlet gas composition one hour after the start of flow. 【0147】 【0148】 Compared to Examples 1-7 (Table 1), which use silicon dioxide and alkali metal elements, Examples 24 and 25 (Table 10), which use a mixture of iron powder and silica sand, show a significantly lower yield. 【0149】[Example 26] The reaction was carried out in the same manner as in Example 22, except that the amorphous silica in the reactant was replaced with glass cullet derived from used solar panel cover glass. Table 11 shows the results of the outlet gas composition 5 minutes after the start of flow. 【0150】 【0151】 As shown in Table 11, using glass cullet derived from used solar panel cover glass yielded results comparable to those obtained using silica sand or silica. 【0152】 The disclosure of Japanese Patent Application No. 2024-218147 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 alkenes with a halogenated compound, comprising converting an alkane with a halogenated compound represented by formula (1) to an alkene with a halogenated compound represented by formula (2) and a compound represented by formula (3) in the gas phase in the presence of silicon oxide and an alkali metal element. In formulas (1) to (3), R １ ~R ３ 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 the number of carbon atoms in the halogenated alkanes represented by formula (1), the halogenated alkenes represented by formula (2), and the compounds represented by formula (3) is 2 to 4.

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

4. The method for producing a halogenated alkene according to claim 1 or 2, wherein the molar ratio of the halogenated alkene represented by formula (2) to the compound represented by formula (3) at one hour from the start of the reaction is 10 or more.

5. The method for producing an alkene halide according to claim 1 or 2, wherein the alkali metal element is at least one selected from the group consisting of Li, Na, K, Rb, and Cs.

6. The method for producing an alkene halide according to claim 1 or 2, wherein the alkali metal element is at least one selected from the group consisting of Na, K, and Cs.

7. The alkali metal element is included as an alkali metal salt, and the anion of the alkali metal salt is F － , SiF ６ ２－ , Cl － and CO ３ ２－ 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.

8. The anion of the alkali metal salt is F － and SiF ６ ２－ The method for producing a halogenated alkene according to claim 7, wherein the anion is at least one selected from the group consisting of 9. The alkali metal salt is CsF, K ２ CO ３ ,KF,K ２ SiF ６ Na ２ SiF ６ A method for producing a halogenated alkene according to claim 7, comprising at least one selected from the group consisting of NaF and LiF.

10. The alkali metal salt is CsF, K ２ CO ３ ,KF,K ２ SiF ６ Na ２ SiF ６ A method for producing a halogenated alkene according to claim 7, comprising at least one selected from the group consisting of and NaF.

11. The method for producing a halogenated alkene according to claim 1 or 2, wherein the silicon dioxide is included as silicon dioxide particles.

12. A method for producing a halogenated alkene according to claim 1 or 2, wherein the halogenated alkane is converted at a temperature of 450 to 1000°C.

13. 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.

14. A method for producing silicon tetrafluoride, comprising contacting a halogenated alkane represented by the following formula (1) with silicon oxide and an alkali metal element in the gas phase to produce silicon tetrafluoride. In formula (1), R １ ~R ３ 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 the number of carbon atoms in the halogenated alkane represented by formula (1) is 2 to 4.

15. A method for producing silicon tetrafluoride according to claim 14, comprising: in the gas phase, a dehydrofluorination reaction of a halogenated alkane represented by formula (1) to produce a halogenated alkene represented by the following formula (2) and hydrogen fluoride; and a reaction between the produced hydrogen fluoride and silicon oxide to produce silicon tetrafluoride. In formula (2), R １ and R ２ 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 the number of carbon atoms in the halide alkene represented by formula (2) is 2 to 4.

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