Method for producing fluorohydrocarbon

Abstract

To provide a production method by which a fluorohydrocarbon can be easily and efficiently produced in a vapor-phase flow mode without using a catalyst.SOLUTION: The method for producing a fluorohydrocarbon comprises: continuously supplying a first inert gas to a plasma device to form an electrical-discharge region; continuously circulating a feed gas comprising a second inert gas, a gaseous fluorinated inorganic compound and a compound represented by formula 1, CH3-R [where R is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, or an organic group (which is not a hydrocarbon group)], around the electrical-discharge region in the plasma device; and continuously discharging the gases from the plasma device.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing a fluorohydrocarbon. [Background technology]

[0002] Fluorinated hydrocarbons such as monofluoromethane are widely used as etching gases for semiconductor microfabrication.

[0003] As a method for producing monofluoromethane, a method is known in which methyl chloride (CHCl) and hydrogen fluoride are reacted in the gas phase in the presence of a fluorination catalyst to obtain a mixed gas containing monofluoromethane, and then the monofluoromethane is separated and purified from the mixed gas (Patent Document 1).

[0004] Furthermore, as a production method that does not use a fluorination catalyst, a gas-phase flow type monofluoromethane production method has also been proposed in which a raw material gas containing a fluorine-containing inorganic compound, a specified compound, and an inert gas is discharged while being continuously flowed, and then continuously released outside the discharge region (Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-111611 A [Patent Document 2] International Publication No. 2021 / 241371 Summary of the Invention [Problem to be solved by the invention]

[0006] The above-mentioned gas-phase flow type monofluoromethane production method does not use a fluorination catalyst, so there is no burden of preparing a fluorination catalyst, and it is possible to avoid a decrease in yield due to a decrease in catalyst activity. However, since the monofluoromethane raw material gas is flowed through the discharge region of the plasma device, there is a risk that the fluorine-containing components in the raw material gas will decompose excessively, resulting in an increase in by-products. In addition, there is a risk that the fluorine-containing components will cause corrosion when they come into contact with electrodes, etc. in the plasma device.

[0007] An object of the present invention is to provide a method for producing fluorohydrocarbons such as monofluoromethane simply and efficiently by a gas-phase flow system without using a catalyst.

[0008] The present invention has an object to advantageously solve the above-mentioned problems, and relates to a method for producing a fluorohydrocarbon, which comprises continuously supplying a first inert gas into a plasma device to form a discharge region, continuously flowing a raw material gas containing a gaseous fluorine-containing inorganic compound, a compound represented by the formula 1: CH3-R (wherein R is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom or an organic group (excluding a hydrocarbon group)), and a second inert gas around the discharge region in the plasma device, and continuously releasing the raw material gas outside the plasma device.

[0009] Here, the discharge region in the plasma device refers to a space in which the insulation of the gas is broken down by the electric field in the plasma device and a current flows. Gaseous fluorine-containing inorganic compounds are fluorine-containing inorganic compounds that are gases under standard conditions (298 K, atmospheric pressure). Inorganic compounds include compounds that contain no carbon atoms and compounds that contain one carbon atom and no hydrogen atoms. The term "fluorohydrocarbon" refers to a compound in which at least one hydrogen atom of a hydrocarbon compound has been substituted with a fluorine atom, and includes compounds in which all hydrogen atoms of the hydrocarbon compound have been substituted with fluorine atoms.

[0010] According to the method for producing fluorocarbons of the present invention, it is presumed that fluorocarbons are produced as follows. The periphery of the discharge region in the plasma device includes a region where the temperature is high due to the radiant heat of the plasma, and when a gaseous fluorine-containing inorganic compound and a compound represented by formula 1: CH3-R [wherein R is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, or an organic group (excluding a hydrocarbon group)] are supplied, at least one of fluorine ions and fluorine radicals (hereinafter also referred to as "fluorine source") is generated from the former, and active species including radicals and ions (hereinafter also referred to as "CH3 radicals, etc.") containing a partial structure of the compound of formula 1, such as CH3 radicals and CH3 ions, are generated from the compound represented by formula 1: CH3-R [wherein R is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, or an organic group (excluding a hydrocarbon group)]. Generally, gaseous fluorine-containing inorganic compounds are stable and difficult to decompose, but the periphery of the discharge region of the plasma device in the present invention refers to a region where the temperature is high due to the radiant heat of the plasma and the gaseous fluorine-containing inorganic compound can be decomposed. A raw material gas containing a gaseous fluorine-containing inorganic compound and a compound represented by formula 1 is circulated around the discharge region in the plasma device to generate the fluorine source and the active species (particularly, CH3 radicals and CH3 ions), which are then continuously released outside the plasma device, whereby the fluorine source and the active species (particularly, CH3 radicals and CH3 ions) combine to generate fluorohydrocarbons.

[0011] This production method does not require a catalyst, is simple and efficient, and since the gaseous fluorine-containing inorganic compound flows around the discharge region in the plasma device, contact of the fluorine source with electrodes, etc. can be suppressed, and corrosion can be avoided.

[0012] In the method for producing fluorohydrocarbons of the present invention, a device for generating atmospheric pressure thermal plasma is used as the plasma device, and the reaction field created by the atmospheric pressure thermal plasma can be utilized. This is advantageous in that the amount of processing per unit time can be increased with a compact device. The atmospheric pressure thermal plasma can be generated by arc discharge or high frequency discharge. Here, the discharge region of atmospheric pressure thermal plasma is the region where the insulation of the gas is broken by the electric field and current flows. In plasma devices that generate plasma using electrodes, it is the space between the opposing electrodes, but in a method of taking the flame out of the space between the electrodes such as a plasma jet, it corresponds to the flame zone, and in plasma devices that generate plasma by means other than electrodes, it is the corresponding space. Examples of plasma devices that generate plasma by means other than electrodes include inductively coupled plasma (ICP) devices. The discharge region of atmospheric pressure thermal plasma usually includes a high-temperature part that reaches 10,000K or more. The temperature around the discharge region of atmospheric pressure thermal plasma reaches 1000 to 3000K due to plasma radiation, and chemical species can undergo excitation and dissociation reactions, which can decompose gaseous fluorine-containing inorganic compounds. For example, in a plasma device that generates plasma using electrodes, the downstream periphery of the anode includes a temperature range of 1000 to 3000K, and this temperature range constitutes the periphery of the discharge region of atmospheric pressure thermal plasma.

[0013] In the method for producing fluorohydrocarbons of the present invention, the gaseous fluorine-containing inorganic compound is preferably at least one selected from the group consisting of SF4, SF6, SOF2, SO2F2, HF, NF3, CF4, COF2, BF3 and SiF4. These compounds are advantageous in that they can easily generate a fluorine source in the vicinity of the discharge region.

[0014] The first inert gas in the method for producing a fluorocarbon of the present invention is a base gas for forming a discharge region, and can be one or more gases selected from the group consisting of N2 and Ar.

[0015] The second inert gas in the method for producing fluorohydrocarbon of the present invention is a dilution gas for the gaseous fluorine-containing inorganic compound and the compound of formula 1, and can be one or more selected from the group consisting of N2 and Ar. The first inert gas and the second inert gas can be the same or different.

[0016] Furthermore, in the method for producing fluorohydrocarbons of the present invention, the content of the gaseous fluorine-containing inorganic compound and the compound of formula 1 in the raw material gas is preferably 25% by volume or more and 100% by volume or less. If the content is within the above range, the target substance, fluorohydrocarbon, can be efficiently produced.

[0017] In addition, in the method for producing fluorohydrocarbons of the present invention, the volume ratio of the gaseous fluorine-containing inorganic compound to the compound of formula 1 is preferably at least 2. When the volume ratio is at least the above lower limit, the target substance, fluorohydrocarbon, can be efficiently produced.

[0018] The process for producing a fluorohydrocarbon of the present invention can produce monofluoromethane as the target substance. Effect of the Invention

[0019] According to the present invention, it is possible to provide a method for producing fluorocarbons simply and efficiently in a gas-phase flow system without using a catalyst. Furthermore, according to the present invention, it is possible to avoid the risk of corrosion of electrodes and the like in a plasma device. The production method of the present invention is advantageous in that it is possible to avoid situations such as a decrease in yield due to a decrease in catalyst activity, and also to continuously produce fluorocarbons. [Brief description of the drawings]

[0020] [Figure 1] 1 is an example of a plasma device that can be used in the method for producing fluorohydrocarbon of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, embodiments of the present invention will be described in detail.

[0022] [Fluorine-containing gaseous inorganic compounds] The gaseous fluorine-containing inorganic compound may be any gaseous inorganic compound containing one or more fluorine atoms, typically eight or fewer fluorine atoms.

[0023] Examples of gaseous fluorine-containing inorganic compounds include SF4, SF6, SOF2, SO2F2, HF, NF3, CF4, COF2, BF3, and SiF4. From the viewpoint of ease of handling, SF6, NF3, CF4, BF3, and SiF4 are preferred. The gaseous fluorine-containing inorganic compounds may be one type or any combination of two or more types.

[0024] [Compound of Formula 1] The compound of formula 1 is a compound represented by formula 1: CH3-R (wherein R is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, or an organic group (excluding hydrocarbon groups). The compound of formula 1 may be used alone or in combination of two or more kinds.

[0025] Here, the organic group (excluding hydrocarbon groups) refers to a functional group containing at least one carbon atom (excluding those consisting only of carbon atoms and hydrogen atoms), as well as a functional group containing at least one element selected from oxygen, nitrogen, and sulfur, but containing no carbon atoms, and examples of such a functional group include an oxygen-containing organic group, a nitrogen-containing organic group, and a sulfur-containing organic group.

[0026] The oxygen-containing organic groups include hydroxyl (-OH), carboxyl (-COOH), formyl (-CHO), formyloxy (-O-CH(=O)), acyl (-CR 1 (=O)), acyloxy (-O-CR 1 (=O)), alkoxy (-OR1), alkoxycarbonyl (-C(=O)-OR 1 ) etc. Here, R 1 is alkyl, preferably C1 to C4 alkyl, more preferably methyl or ethyl.

[0027] Nitrogen-containing organic groups include unsubstituted amino (-NH2), substituted amino (-NR 2 R 3 ), nitro (-NO2), cyano (-CN), etc. 2 and R 3 are independently hydrogen or alkyl, but at least one of them is alkyl, and the alkyl is preferably C1 to C4 alkyl, more preferably methyl or ethyl.

[0028] Sulfur-containing organic groups include mercapto (-SH), sulfo (-SO3H), alkylthio (-SR 4 ) etc. Here, R 4 is alkyl, preferably C1 to C4 alkyl, more preferably methyl.

[0029] R is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxyl (-OH), an alkoxy (-OR 1 ), acyl (-CR 1 (=O)), substituted amino (-NR 2 R 3 ) (where R 1 , R 2 and R 3 is as defined above.) is preferred, and a hydrogen atom, a chlorine atom, hydroxy, methoxy, acetyl, and dimethylamino are more preferred.

[0030] Compounds of formula 1 include CH4, CH3OH, CH3Cl, CH3Br, CH3I, CH3CHO, HCOOCH3, CH3COOCH3, CH3COOC2H5, CH3NH2, (CH3)2NH, (CH3)3N, CH3CN, CH3NO2, CH3SH, CH3SCH3, CH3OCH3, CH3OC2H5, CH3COCH3, CH3COC2H5, etc., of which CH4, CH3OH, CH3Cl, CH3COCH3, CH3OCH3, and (CH3)3N are preferred from the standpoint of ease of handling, with CH3OH being more preferred.

[0031] [Second inert gas] The second inert gas may be N2, He, Ne, Ar, Xe, Kr, CO, CO2, or the like. 2 , Ar, He, CO, and CO2 are preferred, and N2 and Ar are more preferred. The inert gas may be used alone or in combination of two or more kinds.

[0032] [Raw material gas] The source gas contains a gaseous fluorine-containing inorganic compound, the compound of formula 1, and a second inert gas. The compound of formula 1 may be in any of a gaseous, liquid, and solid state under standard conditions (atmospheric pressure, 298 K), but the source gas is in a gaseous state when it is introduced around the discharge region in the plasma device.

[0033] The content ratio of the gaseous fluorine-containing inorganic compound, the compound of formula 1, and the second inert gas in the raw material gas is not particularly limited and can be adjusted to any ratio. The content ratio of the gaseous fluorine-containing inorganic compound and the compound of formula 1 in the raw material gas is preferably 25% by volume or more, more preferably 35% by volume or more, and is preferably 100% by volume or less, more preferably 60% by volume or less. The remainder of the raw material gas other than the compound of formula 1 and the second inert gas is preferably impurities that are inevitably mixed in from the surrounding environment.

[0034] [Discharge area] In the manufacturing method of the present invention, a first inert gas is continuously supplied into a plasma device to form a discharge region.

[0035] [First inert gas] The first inert gas may be N2, He, Ne, Ar, Xe, Kr, CO, CO2, or the like. 2 , Ar, He, CO, and CO2 are preferred, and N2 and Ar are more preferred. The inert gas may be used alone or in combination of two or more kinds.

[0036] [Atmospheric pressure thermal plasma] In the manufacturing method of the present invention, the reaction field created by the atmospheric pressure thermal plasma can be utilized. Specifically, a first inert gas is supplied to a plasma device that generates the atmospheric pressure thermal plasma to form a discharge region, and the outside of this region can be used as the reaction field.

[0037] Atmospheric pressure thermal plasma can be generated by electrical methods, such as arc discharge, high frequency discharge, pulse discharge, multi-phase AC discharge, etc. Plasma jets generated by arc discharge and high frequency discharge are also included.

[0038] The arc discharge may be a DC arc or an AC arc. A multiphase AC arc is preferred because it can treat a large flow rate. As for the high frequency discharge, an inductively coupled high frequency discharge plasma is advantageous in terms of efficient treatment.

[0039] [Distribution of raw gas] In the manufacturing method of the present invention, the raw material gas is circulated around the discharge region in the plasma device. As long as the effect of the present invention is not impaired, it is permitted for the raw material gas to flow into regions other than the plasma region (including the plasma region) in the plasma device. It is preferable that the entire amount of the raw material gas flows around the discharge region.

[0040] For example, the raw material gas can be circulated around the discharge region of the atmospheric pressure thermal plasma, whereby a sufficient amount of CH3 radicals can be generated from the compound of formula 1 in the raw material gas, and a sufficient amount of fluorine source can be generated from the gaseous inorganic compound, allowing efficient production of fluorohydrocarbons.

[0041] The source gas may contain the gaseous fluorine-containing inorganic compound, the compound of formula 1, and the second inert gas when it is introduced into the vicinity of the discharge region in the plasma device. The gaseous fluorine-containing inorganic compound and the compound of formula 1 may be diluted with the second inert gas and separately supplied to the vicinity of the discharge region in the plasma device to form the source gas, or the entire gas may be supplied as a premixed gas to form the source gas, or a portion of the gas may be supplied as a premixed gas separately from the remaining gas to form the source gas.

[0042] When the compound of formula 1 is a gas under normal conditions or a liquid with a sufficiently high vapor pressure that is easily vaporized by heating, etc., the compound of formula 1 can be supplied as a gas to the periphery of the discharge region in the plasma device without providing a separate vaporization chamber, etc. The supply flow rate can be controlled using a mass flow controller, etc.

[0043] When the compound of formula 1 is a liquid or solid with a low vapor pressure under standard conditions, the compound of formula 1 can be vaporized in a separately provided vaporization chamber and then fed to the gas-phase flow reactor. When the compound of formula 1 is a solid, it can be heated to become a liquid and then introduced into the vaporization chamber.

[0044] For example, the compound of formula 1 can be vaporized by introducing it in a liquid state into a vaporization chamber maintained at a temperature and pressure at which the compound of formula 1 is sufficiently vaporized. The temperature and pressure of the vaporization chamber are preferably maintained at a temperature and pressure at which the compound of formula 1 can be vaporized instantly. By using such a vaporization chamber, the compound of formula 1 can be continuously introduced into the vaporization chamber as a liquid, instantly vaporized in the vaporization chamber, and continuously supplied as a gas to the periphery of the discharge region in the plasma device. The supply flow rate can be controlled by controlling the gas vaporized in the vaporization chamber with a mass flow controller or the like, or by controlling the compound of formula 1 when it is continuously introduced into the vaporization chamber in a liquid state with a liquid mass flow controller or the like. When the vaporized compound of formula 1 is introduced into the periphery of the discharge region in the plasma device, it may be diluted with a second inert gas.

[0045] The space velocity when the source gas is introduced into the vicinity of the discharge region is not particularly limited, and is preferably 0.01 h -1 More than 0.1h is preferable. -1 More preferably, 0.3h -1 More preferably, 100,000 h -1 Less than 50000h is preferable. -1 Less than 10000h is preferable. -1If the space velocity is within the above range, it is possible to avoid difficulties in generating plasma, and fluorohydrocarbons can be produced efficiently.

[0046] In the production method of the present invention, the content ratio of the gaseous fluorine-containing inorganic compound and the compound represented by formula 1 in the raw material gas is not particularly limited and can be adjusted to any content ratio. From the viewpoint of reaction efficiency, it is preferably 25 vol% or more, more preferably 35 vol% or more, and from the viewpoints of reaction efficiency and cost, it is preferably 100 vol% or less, more preferably 60 vol% or less.

[0047] In the production method of the present invention, the volume ratio of the gaseous fluorine-containing inorganic compound to the compound of formula 1 is not particularly limited and can be adjusted to any ratio. The volume ratio of the fluorine-containing inorganic compound to the compound of formula 1 is preferably 0.8 or more from the viewpoint of suppressing the by-production of hydrocarbons, and more preferably 1.8 or more from the viewpoint of producing the target substance. The volume ratio can be 100 or less, for example, 25 or less.

[0048] The source gas is caused to flow around the discharge region of the plasma device. For example, by adjusting the introduction and discharge positions of the source gas in the plasma device, the source gas can be made to flow around the discharge region of the plasma device. In addition, by adjusting the introduction and release positions of the first inert gas, which is the base gas, the source gas can be made to flow around the discharge region of the plasma device. Since the fluorine-containing inorganic compound gas in the source gas can cause corrosion problems when it comes into contact with metal parts such as electrodes in a plasma device, it is preferable to flow the source gas in a manner that avoids contact with these parts.

[0049] [Fluorocarbons] Fluorocarbons can be obtained by continuously releasing the gas contained around the discharge region in the plasma device to the outside of the plasma device. The gas contained around the discharge region in the plasma device contains active species such as a fluorine source and CH3 radicals generated from the compound of formula 1. By continuously releasing these to the outside of the plasma device, the fluorine source and the active species such as CH3 radicals (especially CH3 radicals and CH3 ions) combine to generate fluorocarbons. The continuous release can be performed at a space velocity corresponding to the continuous flow of the raw material gas.

[0050] After the gas is discharged outside the plasma device, it may be further introduced into a heat exchanger for cooling. The type of heat exchanger is not particularly limited, and examples thereof include air-cooling and water-cooling. The discharged material may contain hydrocarbons and the like in addition to the target substance, fluorohydrocarbons, and therefore may be subjected to a separation and purification step. Examples of the separation and purification method include distillation, absorption by a solution, membrane separation, and the like.

[0051] According to the present invention, fluorocarbons can be produced, which is advantageous in that fluorocarbons having 1 to 2 carbon atoms are produced. Specific examples include CH3F, CH2F2, CHF3, CF4, and C2H2F2. Applications of monofluoromethane (CH3F) include etching gas, and applications of difluoromethane (CH2F2) and trifluoromethane (CHF3) include alternative fluorocarbon materials and etching gas. In the production of monofluoromethane, it is preferred that the gaseous fluorine-containing inorganic compound is SF6 and the compound of formula 1 is CH3OH.

[0052] [Plasma device] An example of a plasma device that can be used in the manufacturing method of the present invention is shown in Figure 1. This plasma device utilizes arc discharge.

[0053] The plasma device 1 includes a combustion tube 10 in a cooling jacket 30, and cooling water flows through the cooling jacket 30. The combustion tube 10 is preferably made of ceramic from the viewpoint of heat resistance.

[0054] A cathode 11 is provided above the combustion tube 10, and an anode 12 is provided inside the combustion tube 10. An ignition wire 34 is disposed on the cathode side. A voltage is applied between the cathode 11 and the anode 12 to cause discharge. The discharge conditions are not particularly limited, but may be, for example, a voltage of 300 to 600 V and a current of 1 to 20 A. The size of the combustion tube 10 and the distance between the electrodes may be set appropriately.

[0055] A first gas supply pipe 21 is connected to the plasma device 1 on the cathode 11 side. A base gas (first inert gas) is supplied from this supply pipe 21, and plasma is generated by discharge. The anode 12 side of the plasma generated by discharge is downstream of the plasma. The lower part of the anode 12 of the plasma device 1 (the side opposite to the cathode) includes a temperature range of 1000 to 3000 K, and constitutes the periphery of the discharge region.

[0056] The bottom of the plasma device 1 is provided with a gas recovery port 23. A second gas supply pipe 22 is inserted into the gas recovery port 23. A raw material gas is supplied from this supply pipe 22. By discharging the raw material gas toward the cathode 11 side, the raw material gas reaches the periphery of the discharge region below the anode 12 of the plasma device 1 (opposite the cathode), and active species such as CH3 radicals and a fluorine source are generated. By adjusting the length of the gas supply pipe 22 in the combustion tube 10, the supply position of the raw material gas can be adjusted so that the raw material gas reaches the periphery of the discharge region, while preventing the raw material gas from flowing into the discharge region. It is preferable to flow the raw material gas so as to avoid contact with the anode 12 from the viewpoint of preventing corrosion.

[0057] By supplying the parent gas (first inert gas) from the first gas supply pipe 21 in a direction opposite to the supply direction of the raw material gas, it is possible to prevent the raw material gas from flowing into the discharge region and to adjust the position through which the raw material gas flows.

[0058] The gas in the plasma peripheral region contains active species such as CH3 radicals generated from the fluorine source and the compound of formula 1, and this gas can be recovered outside the plasma device 1 from the gas recovery port 23. At that time, the fluorine source and the active species such as CH3 radicals (especially CH3 radicals and CH3 ions) combine to generate fluorocarbons. The recovery can be performed by connecting a vacuum pump to the gas recovery port 23, for example. EXAMPLES

[0059] The present invention will be described in more detail below with reference to examples. In the examples, a plasma device corresponding to FIG.

[0060] Example 1 A long DC arc plasma device made of Hastelloy (volume: 16 L, distance between electrodes (L1): 300 mm) was used as the plasma device 1. Inside the plasma device, a cylindrical ceramic tube made of mullite (inner diameter 42 mm, length (L2) 600 mm) was installed as the combustion tube 10. The distance (L3) from the bottom of the combustion tube 10 to the tip of the anode 12 on the plasma side was 480 mm. A second gas supply pipe 22 was introduced into the combustion tube 10 from a gas recovery port 23. The second gas supply pipe 22 in the combustion tube 10 is a ceramic pipe (length 75 mm) connected to a metal pipe (length 80 mm in the combustion tube 10. Arranged on the bottom side of the combustion tube 10), and the length (L4) from the bottom of the combustion tube 10 to the tip of the ceramic tube was 155 mm.

[0061] N2, which is the parent gas for plasma, was introduced into the combustion tube 10 through the first gas supply pipe 21 at 30.0 slm, and plasma was ignited at a current value of 10 A. The parent gas was continued to be supplied at the same amount, and CH3OH 1.0 slm and SF6 2.5 slm were introduced as raw material gases through the second gas supply pipe 22 together with N2 1.0 slm as a dilution gas, and were made to flow around the lower part of the ring of the anode 12 of the combustion tube 10.

[0062] Next, the gas downstream of the plasma was discharged out of the system through the gas recovery port 23. The recovered gas discharged out of the system was detoxified with an aqueous KOH solution and then collected in an aluminum bag.

[0063] The collected gas was analyzed by gas chromatography-mass spectrometry (GC-MS) (Agilent 7890A, manufactured by Agilent) and flame ionization gas chromatography (GC-FID) (Agilent 6890N, manufactured by Agilent). The yield of fluorocarbons was calculated from the area values ​​of each component obtained by GC-MS and GC-FID analysis. The results are shown in Table 1.

[0064] (Examples 2 to 3) The same as in Example 1, except that the flow rate of N2 as the dilution gas was changed to the amount shown in Table 1. The results are shown in Table 1. In all the examples, it was found that CS2 (carbon disulfide) was contained in the recovered gas and SF6 was decomposed.

[0065] After Examples 1 to 3 were carried out consecutively, the anode 12 was taken out of the plasma device. No corrosion was observed in the Cu of the anode 12.

[0066] (Examples 4 to 8) The flow rates of SF6 and N2 as a diluent gas were changed to the amounts shown in Table 1, and the results are shown in Table 1. In all the examples, it was found that CS2 (carbon disulfide) was contained in the recovered gas and that SF6 had decomposed.

[0067] After Examples 4 to 6 were carried out consecutively, the anode 12 was taken out of the plasma device. No corrosion was observed in the Cu of the anode 12.

[0068] (Examples 9 to 11) A long DC arc plasma device made of Hastelloy (volume: 16 L, distance between electrodes (L1): 300 mm) was used as the plasma device 2. Inside the plasma device, a cylindrical ceramic tube made of mullite (inner diameter 42 mm, length (L2) 600 mm) was installed as the combustion tube 10. The distance (L3) from the bottom of the combustion tube 10 to the tip of the anode 12 on the plasma side was 480 mm. A second gas supply pipe 22 was introduced into the combustion tube 10 from a gas recovery port 23. The second gas supply pipe 22 in the combustion tube 10 is a ceramic pipe (length 50 mm) connected to a metal pipe (length 80 mm in the combustion tube 10. Arranged on the bottom side of the combustion tube 10), and the length (L4) from the bottom of the combustion tube 10 to the tip of the ceramic tube was 130 mm.

[0069] The same as Example 1 was performed, except that plasma device 2 was used and the flow rates of SF6 and N2 as dilution gas were changed to the amounts shown in Table 1. The results are shown in Table 1. In all the examples, it was found that CS2 (carbon disulfide) was contained in the collected gas and SF6 was decomposed.

[0070] After Examples 9 to 11 were carried out consecutively, the anode 12 was taken out of the plasma device. No corrosion was observed in the Cu of the anode 12.

[0071] [Table 1]

[0072] From Table 1, it is understood that in the examples, fluorohydrocarbons can be produced without using a catalyst. [Industrial Applicability]

[0073] According to the present invention, fluorohydrocarbons can be produced simply and efficiently by a gas-phase flow method without using a catalyst. Furthermore, according to the present invention, the risk of corrosion occurring in electrodes and the like in a plasma device can be avoided. The production method of the present invention can avoid situations such as a decrease in yield due to a decrease in catalyst activity, and can continuously produce fluorohydrocarbons useful for applications such as etching gases, and has high industrial applicability. [Explanation of symbols]

[0074] 1 Plasma equipment 10 Combustion tube 11 Cathode 12 Anode 21 First gas supply pipe 22 Second gas supply pipe 23 Gas recovery port 30 Cooling jacket 31 Cooling water supply port 32 Cooling water outlet 34 Ignition wire

Claims

1. A first inert gas is continuously supplied into a plasma device to form a discharge region, and a gaseous fluorine-containing inorganic compound, Formula 1:CH, is introduced into the periphery of the discharge region in the plasma device. ３ a compound represented by the formula: R (wherein R is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, or an organic group (excluding hydrocarbon groups)) and a second inert gas are continuously flowed through the plasma device, and the compound is continuously released from the plasma device to the outside.

2. The plasma device is a device for forming atmospheric pressure thermal plasma. The method for producing a fluorohydrocarbon according to claim 1.

3. The atmospheric pressure thermal plasma is formed by arc discharge or high frequency discharge. The method for producing a fluorohydrocarbon according to claim 2.

4. The gaseous fluorine-containing inorganic compound is SF 4 , S.F. 6 , SOF 2 , S.O. 2 F 2 , H.F., N.F. 3 , C.F. 4 , COF 2 , B.F. 3 and SiF 4 At least one selected from the group consisting of The method for producing a fluorohydrocarbon according to any one of claims 1 to 3.

5. The first inert gas and the second inert gas are each independently N ２ and Ar, The method for producing a fluorohydrocarbon according to any one of claims 1 to 4.

6. the content ratio of the gaseous fluorine-containing inorganic compound and the compound represented by formula 1 in the source gas is 25 vol% or more and 100 vol% or less; The method for producing a fluorohydrocarbon according to any one of claims 1 to 5.

7. The volume ratio of the gaseous fluorine-containing inorganic compound to the compound represented by formula 1 is 2 or more; The method for producing a fluorohydrocarbon according to any one of claims 1 to 6.

8. The fluorohydrocarbon is monofluoromethane; The method for producing a fluorohydrocarbon according to any one of claims 1 to 7.

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