Method for producing hydrofluorocarbons by hydrogen reduction reaction

Abstract

A method for producing a hydrofluorocarbon (HFC) is provided, the method being excellent in terms of the conversion of a chlorofluorocarbon and reduced in the formation of by-products.　This method for producing an HFC comprises reacting a chlorofluorocarbon (1A) with hydrogen in the presence of a catalyst to produce a hydrofluorocarbon (2A) in which one or two of the chlorine atoms of the chlorofluorocarbon (1A) have each been replaced with a hydrogen atom, the reaction being conducted using a reactive mixture comprising the chlorofluorocarbon (1A), hydrogen, and hydrogen chloride and having a hydrogen chloride concentration of 100-10,000 mass ppm of the chlorofluorocarbon (1A).

Description

[Technical Field]

[0001] The present invention relates to a method for producing hydrofluorocarbons by hydrogen reduction reaction. [Background technology]

[0002] Hydrofluorocarbons (hereinafter also referred to as HFCs) are used as new cleaning agents, refrigerants, blowing agents, and aerosols, or as synthetic raw materials for these. For example, HFCs are sometimes used as synthetic raw materials for hydrofluoroolefins (hereinafter also referred to as HFOs). Specifically, for example, Patent Document 1 describes that 1-chloro-2,2,3,3-tetrafluoropropane (hereinafter also referred to as 244ca) is used as a synthetic raw material for producing 1-chloro-2,3,3-trifluoropropene (hereinafter also referred to as 1233yd). Furthermore, Patent Document 2 describes that 1-chloro-1,1,2,2-tetrafluoropropane (hereinafter also referred to as 244cc) is used as a synthetic raw material for producing 2,2,3,3-tetrafluoropropene (hereinafter also referred to as 1234yf). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 131394 [Patent Document 2] Patent No. 5348240 Summary of the Invention [Problem to be solved by the invention]

[0004] HFCs can be obtained by subjecting chlorofluorocarbons (hereinafter also referred to as CFCs) to a hydrogen reduction reaction. However, in conventional HFC production methods, it was difficult to control the hydrogen reduction reaction, making it impossible to obtain the desired HFCs. The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for producing HFCs with an excellent CFC conversion rate and with a small amount of by-products produced. [Means for solving the problem]

[0005] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by the following configuration.

[0006] [1] A method for producing a hydrofluorocarbon (2A) in which one or two chlorine atoms of the chlorofluorocarbon (1A) are substituted with hydrogen atoms by reacting a chlorofluorocarbon (1A) represented by the following formula (1A) with hydrogen in the presence of a catalyst, A method for producing a hydrofluorocarbon, characterized by reacting a reactive mixture containing a chlorofluorocarbon (1A), hydrogen, and hydrogen chloride, wherein the concentration of hydrogen chloride relative to the chlorofluorocarbon (1A) is 100 to 10,000 ppm by mass. CF2X a -R f -CX a 3(1A) (In the formula, X a are each independently a hydrogen atom, a fluorine atom, or a chlorine atom, and four X a 0 or 1 is a fluorine atom and at least one is a chlorine atom; R f is a fluoroalkylene group having one or more carbon atoms. [2] R above f is a difluoromethylene group. [3] The method according to [1] or [2], wherein the chlorofluorocarbon (1A) is at least one selected from the group consisting of 1,3-dichloro-1,1,2,2-tetrafluoropropane, 1,1-dichloro-2,2,3,3-tetrafluoropropane, 1-chloro-1,1,2,2-tetrafluoropropane, 1-chloro-2,2,3,3-tetrafluoropropane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-1,2,2,3,3-pentafluoropropane, 1-chloro-1,1,2,2,3-pentafluoropropane, 1-chloro-1,2,2,3,3-pentafluoropropane, 3,3-dichloro-1,1,1,2,2-pentafluoropropane, and 3-chloro-1,1,1,2,2-pentafluoropropane. [4] The production method according to any one of [1] to [3], wherein the hydrofluorocarbon (2A) produced is mainly composed of a hydrofluorocarbon in which one chlorine atom of the chlorofluorocarbon (1A) is substituted with a hydrogen atom. [5] The method according to any one of [1] to [4], wherein the catalyst is a metal catalyst containing at least one metal selected from platinum, palladium, rhodium, ruthenium, nickel, rhenium, molybdenum, and zirconium. [6] The method according to any one of [1] to [5], wherein the chlorofluorocarbon (1A) is reacted with hydrogen in a gas phase. [7] The production method according to any one of [1] to [6], wherein the reaction temperature is 150 to 350°C. [8] A method for producing a hydrofluorocarbon (2B) having 0 or 1 chlorine atom by reacting a chlorofluorocarbon (1B) represented by the following formula (1B) with hydrogen, The method comprises a multi-step process in which a single step of substituting one or two chlorine atoms of a chlorofluorocarbon with a hydrogen atom is repeated at least twice, A method for producing a hydrofluorocarbon having 0 or 1 chlorine atom, characterized in that at least one single step among the above multi-stage steps is a single step (Y) of reacting a reactive mixture containing a chlorofluorocarbon, hydrogen, and hydrogen chloride before the start of the reaction, in which the concentration of hydrogen chloride relative to the chlorofluorocarbon is 100 to 10,000 ppm by mass, in the presence of a catalyst. CF2X b -R f -CX b 3(1B) (In the formula, X b are each independently a hydrogen atom, a fluorine atom, or a chlorine atom, and four X b 0 or 1 is a fluorine atom, 2 to 4 are chlorine atoms, and R f is a fluoroalkylene group having one or more carbon atoms. [9] R above f is a difluoromethylene group.

[10] The method according to [8] or [9], wherein the chlorofluorocarbon (1B) is at least one selected from the group consisting of 1,3-dichloro-1,1,2,2-tetrafluoropropane, 1,1-dichloro-2,2,3,3-tetrafluoropropane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-1,2,2,3,3-pentafluoropropane, and 3,3-dichloro-1,1,1,2,2-pentafluoropropane.

[11] The production method according to any one of [8] to

[10] , wherein the hydrofluorocarbon (2B) is at least one selected from the group consisting of 1,1,2,2-tetrafluoropropane, 1,1,2,2,3-pentafluoropropane, and 1,1,1,2,2-pentafluoropropane.

[12] The production method according to any one of [8] to

[11] , wherein the main product in the single step (Y) is a compound in which one chlorine atom of a chlorofluorocarbon is substituted with a hydrogen atom.

[13] The method according to any one of [8] to

[12] , wherein in the step (Y), hydrogen is reacted in a gas phase.

[14] The method according to any one of [8] to

[13] , wherein in the single step (Y), hydrogen is reacted at a reaction temperature of 150 to 350°C.

[15] In two successive single steps: At least the latter single step is the single step (Y), The production method according to any one of [8] to

[14] , wherein at least a portion of the hydrogen chloride in the reaction mixture obtained in the previous single step is removed to prepare a reactive mixture containing chlorofluorocarbon and hydrogen before the start of the reaction from the chlorofluorocarbon, which is the hydrofluorocarbon obtained in the previous single step, and having a hydrogen chloride concentration relative to the chlorofluorocarbon of 100 to 10,000 ppm by mass, and the subsequent single step (Y) is carried out using this reactive mixture. [Effects of the Invention]

[0007] According to the present invention, a method for producing HFCs with an excellent CFC conversion rate and with a small amount of by-products produced can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0008] One of the methods for producing an HFC of the present invention (hereinafter also simply referred to as the "first production method of the present invention") is a method for producing an HFC (2A) in which one or two chlorine atoms of CFC (1A) have been substituted with hydrogen atoms by reacting a CFC (1A) represented by the following formula (1A) with hydrogen in the presence of a catalyst, and is a production method characterized by carrying out the reaction using a reactive mixture containing CFC (1A), hydrogen, and hydrogen chloride, wherein the concentration of hydrogen chloride relative to CFC (1A) is 100 to 10,000 ppm by mass. CF2X a -R f -CX a 3(1A) (In the formula, X a are each independently a hydrogen atom, a fluorine atom, or a chlorine atom, and four X a 0 or 1 is a fluorine atom and at least one is a chlorine atom; R f is a fluoroalkylene group having one or more carbon atoms. Since CFC (1A), the raw material in the first production method of the present invention, has 1 to 4 chlorine atoms, the product HFC (2A) has 0 to 3 chlorine atoms. The product HFC (2A) may consist of two or more compounds having 0 to 3 chlorine atoms, and typically consists of the main product HFC (2A) and a relatively small amount of at least one by-product HFC (2A). For example, as described below, 1,1,1,3-tetrachloro-2,2,3,3-tetrafluoropropane (hereinafter also referred to as 214cb) may produce 1,1,3-trichloro-2,2,3,3-tetrafluoropropane (hereinafter also referred to as 224ca) and 1,1,3-trichloro-2,2,3,3-tetrafluoropropane (hereinafter also referred to as 224cc).

[0009] Another method for producing an HFC of the present invention (hereinafter also simply referred to as the "second production method of the present invention") is a method for producing an HFC (2B) having 0 or 1 chlorine atom by reacting a CFC (1B) represented by the following formula (1B) with hydrogen, It has a multi-step process in which a single step of substituting one or two chlorine atoms of CFC with hydrogen atoms is repeated at least twice, This is a method for producing HFCs having 0 or 1 chlorine atom, characterized in that at least one single step among the multi-stage steps is a single step (Y) of reacting a reactive mixture in the presence of a catalyst, the reactive mixture containing CFCs, hydrogen, and hydrogen chloride before the start of the reaction, wherein the concentration of hydrogen chloride relative to the CFCs is 100 to 10,000 ppm by mass. CF2X b -R f -CX b 3(1B) (In the formula, X b are each independently a hydrogen atom, a fluorine atom, or a chlorine atom, and four X b 0 or 1 is a fluorine atom, 2 to 4 are chlorine atoms, and R f is a fluoroalkylene group having one or more carbon atoms. In the second production process of the present invention, since the number of chlorine atoms in the starting material CFC (1B) is 2 to 4 and the number of chlorine atoms in the final product HFC (2B) is 0 or 1, a multi-stage process consisting of at least two single steps is required in the case of a single step in which one chlorine atom is replaced with a hydrogen atom. At least one of the single steps in the multi-stage process is the single step (Y), and preferably two or more of the multiple single steps are the single step (Y), and more preferably all of the single steps are the single step (Y).

[0010] [CFCs and HFCs] R in CFC(1A) represented by formula (1A) and CFC(1B) represented by formula (1B) f is a fluoroalkylene group, which is an alkylene group having at least one fluorine atom. The fluoroalkylene group is preferably a linear fluoroalkylene group. f The number of carbon atoms in R is preferably 1 to 3, more preferably 1 or 2, and particularly preferably 1. f The number of fluorine atoms in R is preferably equal to or greater than the number of carbon atoms, more preferably 1.8 to 2.0 times the number of carbon atoms, and particularly preferably twice the number of carbon atoms (i.e., the fluoroalkylene group is a perfluoroalkylene group). f is most preferably a difluoromethylene group. Below, R f The present invention will be explained taking as an example the case where is a difluoromethylene group.

[0011] Four X in CFC(1A) represented by formula (1A) a In the case where one of the atoms is a fluorine atom, CF2X a -X on the side a When is a fluorine atom and -CX a 3 Xs on 3 sides a One of the atoms may be a fluorine atom. 4 x a If none of the X's are fluorine atoms, then four X's aThe number of chlorine atoms in is 1 to 4, and the number of hydrogen atoms is 0 to 3. a When any one of the groups is a fluorine atom, the number of chlorine atoms is 1 to 3, and the number of hydrogen atoms is 0 to 2. HFC(2A) produced from CFC(1A) is a compound corresponding to CFC(1A) in which one or two of its chlorine atoms have been replaced by hydrogen atoms.

[0012] Four X in CFC(1B) represented by formula (1B) b In the case where one of the atoms is a fluorine atom, CF2X b -X on the side b When is a fluorine atom and -CX b 3 Xs on 3 sides b One of the atoms may be a fluorine atom. 4 x b If none of the X's are fluorine atoms, then four X's b The number of chlorine atoms in is 2 to 4, and the number of hydrogen atoms is 0 to 2. b If any one of the atoms is a fluorine atom, the number of chlorine atoms is 2 or 3, and the number of hydrogen atoms is 0 or 1. HFC(2B) produced from CFC(1B) is a compound corresponding to CFC(1B) that has one or no chlorine atoms.

[0013] R f is a difluoromethylene group, CFCs represented by formula (1A) and CFCs represented by formula (1B), as well as compounds produced by substituting their chlorine atoms one by one with hydrogen atoms, and production flows thereof, are shown below. In the chemical formula below, the carbon atom (C) is indicated by the intersection of the bond lines, and the arrows indicate the resulting compounds. Furthermore, the symbols consisting of numbers and letters written below the compounds are abbreviations of the compounds used in this specification. For example, "254cb" refers to 1,1,2,2-tetrafluoropropane, "215ca" refers to 1,1,3-trichloro-1,2,2,3,3-pentafluoropropane, "245ca" refers to 1,1,2,2,3-pentafluoropropane, "215cb" refers to 1,1,1-trichloro-2,2,3,3,3-pentafluoropropane, and "245cb" refers to 1,1,1,2,2-pentafluoropropane.

[0014] [ka]

[0015] [First production method of the present invention] In the first production method of the present invention, the raw material CFC (1A) may consist of only one compound, or may be a mixture of two or more CFC (1A) compounds. Two types of HFC (2A) may be produced from one raw material CFC (1A) compound (for example, 224ca and 244cc are produced from 214cb), and usually, one is the main product and the other is a by-product depending on the reactivity of CFC (1A) and the reaction conditions. Furthermore, when the raw material CFC (1A) is a mixture of two or more compounds, the resulting HFC (2A) is usually also a mixture of two or more compounds. For example, a mixture of two CFC (1A) types will produce two corresponding HFC (2A) types. Furthermore, since one CFC (1A) compound can produce two or more HFC (2A) types, when CFC (1A) is a mixture of two or more compounds, the resulting HFC (2A) may be a mixture of three or more HFC (2A) types. On the other hand, the same HFC (2A) can be produced from two different CFC (1A) species (for example, 254cb can be produced from 244cc and 244ca), and a mixture of two such CFC (1A) species can be used as a raw material to produce a product containing one HFC (2A) as the main component.

[0016] In the first production method of the present invention, depending on the reaction conditions such as the molar ratio of hydrogen to CFC (1A), two chlorine atoms in CFC (1A) having two or more chlorine atoms may be replaced by two hydrogen atoms. In some cases, three or more chlorine atoms may be replaced by hydrogen atoms, but it is preferable that the number of replacements of three or more chlorine atoms is small. The fewer the number of replacements of three or more chlorine atoms, the fewer by-products are contained in the product, and the higher the selectivity for HFC (1A) in which one chlorine atom of CFC (1A) has been replaced by a hydrogen atom. The first production method of the present invention is preferably a production method in which the obtained HFC (2A) is mainly composed of an HFC in which one chlorine atom of CFC (1A) has been substituted with a hydrogen atom. Even in this case, an HFC in which two chlorine atoms of CFC (1A) have been substituted with hydrogen atoms is usually also produced as a by-product. In order to suppress the production of an HFC in which two or more chlorine atoms of CFC (1A) have been substituted with hydrogen atoms, it is preferable to optimize the reaction conditions, such as the hydrogen chloride concentration relative to CFC (1A) and the molar ratio of hydrogen to CFC (1A). However, specializing in the production of only HFC (2A) in which one chlorine atom of CFC (1A) has been substituted with a hydrogen atom may result in adverse effects such as a decrease in production rate. Therefore, it is preferable to produce an HFC in which one chlorine atom of CFC (1A) has been substituted with a hydrogen atom, which includes, as a by-product, an HFC in which two chlorine atoms of CFC (1A) have been substituted with a hydrogen atom.

[0017] CFC (1A), which is a starting material compound in the first production method of the present invention, is a compound having a chlorine atom shown at the base of the arrow in the production flow, and HFC (2A), which is a compound produced in the first production method of the present invention, is a compound having a hydrogen atom shown at the tip of the arrow in the production flow. The starting material compound CFC (1A) is preferably a CFC produced from the compound shown on the origin side of the arrow pointing to that compound in the production flow. However, the starting material compound CFC (1A) is not limited to CFCs produced from the compound shown on the origin side of the arrow pointing to that compound in the production flow. Furthermore, even if the compound is produced from a CFC shown on the origin side of the arrow pointing to that compound in the production flow, it is not limited to CFCs produced by the first production method of the present invention.

[0018] Examples of CFC (1A) that is a starting material compound in the first production method of the present invention include 214cb, 224ca, 224cc, 1,3-dichloro-1,1,2,2-tetrafluoropropane (hereinafter also referred to as 234cc), 1,1-dichloro-2,2,3,3-tetrafluoropropane (hereinafter also referred to as 234cb), 244cc, 244ca, 215ca, 1,3-dichloro-1,1,2,2,3-pentafluoropropane (hereinafter also referred to as 225cb), 1,1-dichloro-1,2,2,3,3-pentafluoropropane (hereinafter also referred to as 225cc), 1-chloro-1,1,2,2,3-pentafluoropropane (hereinafter also referred to as 235cc), 1-Chloro-1,2,2,3,3-pentafluoropropane (hereinafter also referred to as 235ca), 215cb, 3,3-dichloro-1,1,1,2,2-pentafluoropropane (hereinafter also referred to as 225ca), and 3-chloro-1,1,1,2,2-pentafluoropropane (hereinafter also referred to as 235cb) are preferred, 224ca, 224cc, 234cc, 234cb, 244cc, 244ca, 225cb, 225cc, 235cc, 235ca, 225ca, and 235cb are more preferred, and 234cc, 234cb, 244cc, 244ca, 225cb, 225cc, 235cc, 235ca, 225ca, and 235cb are even more preferred. It is also preferable to use a CFC mixture containing at least one of these CFCs as CFC(1A). For example, a CFC mixture containing 225cb and 225cc or a CFC mixture containing 225cb and 235ca can be used as CFC(1A). When CFC(1A) contains a plurality of compounds, combinations of 214cb, 224ca, 224cc, 234cc, 234cb, 244cc and 244ca, combinations of 215ca, 225cb, 225cc, 235cc and 235ca, and combinations of 215cb, 225ca and 235cb are preferred, and combinations of 234cc, 234cb, 244cc and 244ca, combinations of 225cb, 225cc, 235cc and 235ca, and combinations of 225ca and 235cb are more preferred. The HFC (2A), which is a compound produced by the first production method of the present invention, may contain two or more HFCs as described above. For example, the HFC (2A) obtained from the CFC (1A), 214cb, may contain 224ca and 244cc, and may further contain 234cc or 234cb. In this case, the obtained HFC (2A) is preferably one containing either 224ca or 244cc as a main component.

[0019] The reactive mixture (a mixture containing CFC (1A), hydrogen, and hydrogen chloride) used in the first production method of the present invention may contain compounds other than these three. The CFC (1A) may contain two or more types of CFC (1A). Examples of other compounds include impurities such as raw materials for producing CFC (1A) and by-products other than CFC (1A) produced during the production of CFC (1A). When the raw CFC (1A) contains the above impurities, CFC (1A) from which the impurities have been removed by known means such as distillation, extractive distillation, azeotropic distillation, membrane separation, two-phase separation, or adsorption may be used. However, in the case of CFC (1A) containing hydrogen chloride as a by-product, it may remain in the raw CFC (1A) as long as its content is not too high. Impurities other than hydrogen chloride are preferably compounds that are inactive in the first production method. Examples of inactive compounds include HFCs that do not contain chlorine atoms.

[0020] In the reactive mixture, CFC (1A) is preferably contained as a major component. Based on the total mass of CFC (1A) and other compounds (excluding hydrogen, hydrogen chloride, and diluents) in the reactive mixture, the content of CFC (1A) is preferably 50 mass% or more, more preferably 75 mass% or more, even more preferably 80 mass% or more, and particularly preferably 90 mass% or more. The upper limit can be 100 mass%. The diluent means an inert gas (hereinafter also referred to as a diluent gas) in a gas-phase reaction or an inert liquid medium in a liquid-phase reaction, and may be a non-reactive fluorine compound such as HFC that does not contain a chlorine atom.

[0021] (hydrogen) The amount of hydrogen (H2) in the reactive mixture is preferably 0.5 to 10.0 moles, more preferably 0.8 to 8.0 moles, and particularly preferably 1.0 to 5.0 moles, per mole of chlorine atoms contained in CFC (1A). If the amount of hydrogen is less than 0.5 moles, the production rate of HFC (2A) will be low, and if it exceeds 10.0 moles, the amount of by-products produced, such as HFCs in which three or more chlorine atoms in CFC (1A) have been replaced with hydrogen atoms, will increase. As described above, HFC (2A) is preferably an HFC in which one chlorine atom of CFC (1A) has been substituted with a hydrogen atom. In order to obtain an HFC in which one chlorine atom of CFC (1A) has been substituted with a hydrogen atom as the main product, the amount of hydrogen (H2) in the reactive mixture is preferably 0.5 to 5.0 mol, more preferably 0.8 to 3.0 mol, particularly preferably 1.0 to 2.0 mol, relative to 1 mol of chlorine atom contained in CFC (1A).

[0022] (catalyst) The catalyst used in the first production method of the present invention is not particularly limited as long as it has the effect of promoting the reaction between CFC(1A) and hydrogen. Examples of the catalyst include metals such as Group 4 elements such as zirconium, Group 6 elements such as molybdenum, Group 7 elements such as rhenium, Group 8 elements such as iron, ruthenium, and osmium, Group 9 elements such as cobalt, rhodium, and iridium, Group 10 elements such as palladium, nickel, and platinum, and Group 11 elements such as gold. The catalyst may be one of the above metals or two or more of them. A catalyst composed of two or more metals may be a mixture of two or more metals or an alloy of two or more metals.

[0023] Among these, the catalyst preferably contains at least one metal selected from platinum, palladium, rhodium, ruthenium, nickel, rhenium, molybdenum, and zirconium, from the viewpoint of improving the conversion rate of CFC (1A) and the selectivity of HFC (2A). As the catalyst, palladium and platinum are particularly preferred in terms of further improving the selectivity for HFC(2A).

[0024] In addition, in order to improve the reactivity, the catalyst is preferably used by being supported on a carrier. The carrier is not particularly limited as long as it can sufficiently support the catalyst. Two or more types of carriers may be used in combination. The carrier is preferably selected from alumina, activated carbon, zirconia, and silica. From the viewpoint of improving the conversion rate of CFC(1A) and the selectivity of HFC(2A), alumina and activated carbon are preferred, and activated carbon is more preferred.

[0025] Examples of activated carbon include activated carbon obtained from plant materials such as wood, charcoal, fruit shells, and coconut shells, and mineral materials such as peat, lignite, and coal. From the viewpoint of catalyst durability, activated carbon obtained from plant materials is preferred as the carrier for supporting the hydrogenation catalyst, with coconut shell activated carbon being particularly preferred. The activated carbon may be in any shape, including briquettes about 2 to 10 mm in length, crushed charcoal about 4 to 50 mesh, and granular charcoal.

[0026] Specific examples of a carrier carrying a catalyst (hereinafter also referred to as a catalyst carrier) include palladium-supported alumina, palladium-supported activated carbon, and platinum-supported activated carbon, which are preferred because they can maintain catalytic activity for a long period of time.

[0027] When the catalyst is used supported on a carrier, the amount of catalyst supported on the carrier is preferably 0.1.0 to 10.0 mass%, more preferably 0.5 to 3.0 mass%, more preferably 1.0 to 3.0 mass%, and most preferably 1.5 to 2.5 mass%. If the amount of catalyst supported is equal to or greater than the lower limit, the reaction rate between the raw material and hydrogen and the conversion rate of CFC (1A) can be improved. If the amount of catalyst supported is equal to or less than the upper limit, excessive temperature rise of the catalyst due to reaction heat can be easily suppressed, and the generation of by-products can be easily reduced.

[0028] (hydrogen chloride) The hydrogen chloride in the reactive mixture may be hydrogen chloride generated in the process of producing CFC (1A) and introduced into the reactive mixture together with CFC (1A), or may be introduced into the reactive mixture separately from CFC (1A). When the hydrogen chloride contained in CFC (1A) is in excess, CFC (1A) from which some of the hydrogen chloride has been removed by a known method such as alkali washing can be used.

[0029] In the reactive mixture, the hydrogen chloride concentration relative to CFC (1A) is 100 to 10,000 ppm by mass. This hydrogen chloride concentration is preferably 150 to 5,000 ppm by mass, more preferably 200 to 2,000 ppm by mass. If the hydrogen chloride concentration is equal to or less than the upper limit, hydrogen chloride is not adsorbed to the active sites of the catalyst, and the conversion rate of CFC (1A) is improved. If the hydrogen chloride concentration is equal to or greater than the lower limit, excessive substitution of chlorine atoms of CFC (1A) with hydrogen atoms can be prevented, and the desired HFC (2A) can be obtained with high purity.

[0030] (Manufacturing method) In the first production method of the present invention, a reactor is used to bring CFC (1A) into contact with hydrogen in the presence of a catalyst. For example, the reaction of CFC (1A) with hydrogen is carried out by supplying CFC (1A) and hydrogen to a reaction site provided with a catalyst. The reaction site provided with a catalyst is usually a reactor containing the catalyst. Below, a method of supplying CFC (1A) and hydrogen into a reactor containing a catalyst to cause the reaction will be described, but the present invention is not limited to this.

[0031] The first production method of the present invention can be carried out by either a gas phase reaction or a liquid phase reaction, and is preferably carried out by a gas phase reaction, since it can shorten the reaction time and suppress the production of by-products. Carrying out a gas phase reaction includes a procedure in which CFC (1A) is contacted with hydrogen in the presence of a catalyst to obtain HFC (2A). A specific procedure for the liquid phase reaction is to bring liquid CFC (1A) into contact with gaseous hydrogen using a means such as stirring in a reactor in the presence of a catalyst to obtain HFC (2A).

[0032] A specific procedure for the gas phase reaction is to supply raw materials, CFC (1A), hydrogen, and hydrogen chloride, heated to a gaseous state, into a reactor, and then bring the gaseous CFC (1A) and hydrogen into contact with a catalyst packed in the reactor to obtain HFC (2A). A gas inert to the reaction (dilution gas) may be supplied to the reactor because it is effective for adjusting the flow rate, suppressing by-products, and suppressing catalyst deactivation. Specific examples of the dilution gas include nitrogen, carbon dioxide, helium, and argon. Two or more types of dilution gases may be used in combination.

[0033] The amount of diluent gas supplied to the reactor is preferably 0.1 mole or more, more preferably 0.5 mole or more, per 1.0 mole of CFC(1A), from the viewpoints of easily maintaining a low maximum catalyst temperature, reducing the generation of by-products, suppressing catalyst deterioration, and maintaining the activity of the catalyst for a long period of time. Furthermore, from the viewpoint of the recovery rate of the diluent gas, the amount of diluent gas supplied is preferably 10.0 moles or less, more preferably 5.0 moles or less, and even more preferably 3.0 moles or less, per 1 mole of CFC(1A).

[0034] In the first production method of the present invention, the reaction temperature (temperature inside the reactor) is preferably 150°C or higher, more preferably 150 to 350°C, even more preferably 160 to 300°C, and particularly preferably 180 to 270°C, from the viewpoint of more efficiently producing HFC (2A). When the reaction temperature is equal to or higher than the lower limit, the conversion rate of CFC (1A) is good. On the other hand, when the reaction temperature is equal to or lower than the upper limit, the generation of by-products is suppressed, and catalyst deterioration can be suppressed. The temperature inside the reactor can be controlled by adjusting the temperature and pressure of the raw materials supplied to the reactor. If necessary, the inside of the reactor can be supplementarily heated by an electric heater, a microwave generator, or the like.

[0035] The contact time (reaction time) between CFC (1A) and hydrogen in the reactor is preferably about 4 to 120 seconds, more preferably about 8 to 100 seconds. If the contact time is equal to or greater than the lower limit, the conversion rate of CFC (1A) is good. Furthermore, if the reaction temperature is equal to or less than the upper limit, the generation of by-products can be suppressed. The contact time can be controlled by adjusting the supply amounts (flow rates) of CFC (1A) and hydrogen to the reactor.

[0036] The reaction pressure may be either normal pressure or elevated pressure, but from the viewpoint of ease of industrial implementation, it is preferable to carry out the reaction at normal pressure.

[0037] The reactor is not particularly limited in shape or structure, as long as it can introduce CFC (1A) and hydrogen and react with each other. Examples of such a reactor include a glass reactor, a stainless steel reactor, a glass-lined reactor, and a resin-lined reactor. The reactor is usually equipped with a temperature control unit that controls the temperature inside the reactor. The temperature control unit can be any unit that can control the reaction temperature between CFC (1A) and hydrogen. Examples of such a unit include an oil bath. The temperature control unit may be provided integrally with the reactor.

[0038] A catalyst (preferably a catalyst carrier) is accommodated in such a reactor, and a catalyst layer is formed as a reaction site. The catalyst carrier may be accommodated in either a fixed bed or a fluidized bed. In the case of a fixed bed type, either a horizontal fixed bed type or a vertical fixed bed type may be used. However, a vertical fixed bed type is preferred because it is easy to prevent the occurrence of concentration distribution of each component depending on location due to differences in specific gravity in a mixed gas composed of multiple components.

[0039] When loading a catalyst into a vertical fixed-bed reactor, the catalyst is loaded from the top of the reactor. At this time, it is necessary to ensure that the catalyst is not damaged by the impact when it reaches the bottom of the reactor. Specifically, the vertical length from the bottom of the vertical fixed-bed reactor to the loading port is h [m], and the gravitational acceleration is g [m / s 2 ], and when the maximum falling speed of the catalyst from the top of the reactor until it reaches the bottom is v [m / s], v must satisfy the following relationship. 0 <v≦(2×g×h) 0.5

[0040] When CFC (1A) and hydrogen are supplied to the reactor, they are mixed in advance and then supplied as is. When they are supplied separately, they are usually mixed near the reactor inlet and then flow from the inlet side of the reactor toward the outlet side, passing through the catalyst layer.

[0041] The production method of the present invention may be carried out in a batch system or a continuous system. When carried out in a batch system, a predetermined amount of either CFC (1A) or hydrogen is placed in a reactor as a feed material, and the other is gradually added to the feed material in the reactor. For example, a predetermined amount of CFC (1A) is placed in a reactor as a feed material, and the CFC (1A) is gradually added to hydrogen.

[0042] When the reaction is carried out continuously, CFC (1A) and hydrogen are continuously supplied into a reactor at a predetermined molar ratio and a predetermined supply rate, and the two are allowed to come into contact with each other in the reactor for a predetermined period of time. One of them may be supplied first and the other later, or both may be supplied simultaneously. When either CFC (1A) or hydrogen is supplied first, the component supplied first is retained in the reactor, and the other component is supplied to the reactor, thereby allowing the CFC (1A) and hydrogen to come into contact with the catalyst for a predetermined period of time. When CFC (1A) and hydrogen are supplied simultaneously to the reactor, the CFC (1A) and hydrogen may be supplied to the reactor from separate supply pipes, or they may be premixed and supplied from a single supply pipe. Since heat of adsorption between CFC (1A) and the catalyst is generated at the beginning of the supply of CFC (1A), it is preferable to supply CFC (1A) first and then add hydrogen after the heat of adsorption has subsided, in terms of controlling the reaction temperature. When the production method of the present invention is carried out continuously, the feed rates of CFC (1A) and hydrogen to the reactor are adjusted by adjusting the feed flow rates of each compound.

[0043] The product gas discharged from the outlet of the reactor contains HFC (hereinafter also referred to as HFC (2A)), the target substance CFC (1A) in which one or two chlorine atoms have been replaced with hydrogen atoms, as well as unreacted raw material CFC (1A) and hydrogen, various by-products, and hydrogen chloride. Examples of by-products include HFCs other than the target substance.

[0044] CFC(1A) includes 214cb, 224ca, 224cc, 234cc, 234cb, 244cc, 244ca, 215ca, 225cc, 225cb, 235cc, 235ca, 215cb, 225ca, and 235cb. As CFC (1A), 224ca, 224cc, 234cc, 234cb, 244cc, 244ca, 225cb, 225cc, 235cc, 235ca, 225ca and 235cb are preferred, and 234cc, 234cb, 244cc, 244ca, 225cb, 225cc, 235cc, 235ca, 225ca and 235cb are more preferred. When CFC(1A) contains a plurality of compounds, combinations of 214cb, 224ca, 224cc, 234cc, 234cb, 244cc and 244ca, combinations of 215ca, 225cb, 225cc, 235cc and 235ca, and combinations of 215cb, 225ca and 235cb are preferred, and combinations of 234cc, 234cb, 244cc and 244ca, combinations of 225cb, 225cc, 235cc and 235ca, and combinations of 225ca and 235cb are more preferred.

[0045] In the first production method of the present invention, the product gas is washed with an alkali to reduce the content of hydrogen chloride, and then subjected to a dehydration treatment. Components other than the desired HFC (2A) present in the outlet gas after hydrogen chloride reduction can be removed to a desired extent by distillation or the like. The separated unreacted CFC (1A) can be recycled as a raw material for producing HFC (2A) by returning it to the reactor. By recycling the unreacted raw material in this way, the overall productivity of HFC (2A) can be increased even if the conversion rate of HFC (2A) in the reaction of CFC (1A) with hydrogen is low. Furthermore, the hydrogen removed by distillation or the like can be recycled as a raw material for production by returning it to the reactor. When the outlet gas after hydrogen chloride reduction contains water and the desired HFC (2A) is recovered from the outlet gas by distillation purification, if a component having a boiling point lower than that of the desired HFC (2A) forms an azeotropic or near-azeotropic composition with water, the desired HFC (2A) can be recovered in a water-free state by distilling off the water together with the low-boiling component. When the HFC (2A) is 254cb, specific examples of the components having a boiling point lower than that of the desired HFC (2A) include 1-fluoropropane (HFC-281fa, hereinafter also referred to as 281fa), 2-fluoropropane (HFC-281ea, hereinafter also referred to as 281ea), fluoromethane, difluoromethane, 1,1,1,2-tetrafluoroethane, fluoroethane, 1,2-difluoroethane, etc.; when the HFC (2A) is 245ca, specific examples include 244cc, 254cb, fluoromethane, difluoromethane, 1,1,1,2-tetrafluoroethane, fluoroethane, 1,2-difluoroethane, etc.; and when the HFC (2A) is 245cb, specific examples include fluoromethane, difluoromethane, 1,1,1,2-tetrafluoroethane, fluoroethane, 1,2-difluoroethane, etc.

[0046] When the catalyst is removed from the reactor after the reaction in the first production method of the present invention, it is preferable to take measures to prevent the catalyst from coming into contact with air and burning. Specifically, after the reaction is completed, the reactor is thoroughly purged with hydrogen at a temperature of 150°C or higher, and then water is introduced into the reactor at a temperature of 100°C or lower so that the catalyst is removed in a hydrated state.

[0047] In the second production method of the present invention, when two consecutive steps of the multi-stage process are both single steps (Y) and the previous single step (Y) is a step consisting of the first production method of the present invention, purification by alkaline washing of the produced gas or distillation of the outlet gas is not an essential treatment.

[0048] When the first production method of the present invention is carried out in a liquid phase, the reaction of CFC (1A) with hydrogen may be carried out using a solvent or without a solvent. When the reaction of CFC (1A) with hydrogen is carried out using a solvent, the solvent may be an alcohol such as ethanol or isopropyl alcohol, or acetic acid, ethyl acetate, pyridine, or the like. When the reaction is carried out without a solvent, the CFC (1A) can be liquefied under pressure. When the production method of the present invention is carried out in a liquid phase, the reaction temperature is preferably room temperature (about 25°C) to about 150°C, and the reaction pressure is preferably normal pressure to about 5 MPa. The reaction time is usually preferably about 1 to 72 hours. When the production method of the present invention is carried out in a liquid phase as a batchwise process, the reaction time is preferably 1 to 9 hours.

[0049] [Second production method of the present invention] The second production method of the present invention is a method for producing HFC (2B) having 0 or 1 chlorine atom by reacting CFC (1B) with hydrogen, characterized in that it comprises a multi-stage process in which a single step of substituting one or two chlorine atoms of the CFC with a hydrogen atom is repeated at least twice, and at least one single step in the multi-stage process is single step (Y). The single step (Y) is a single step in which a reactive mixture containing CFC, hydrogen, and hydrogen chloride before the start of the reaction, in which the concentration of hydrogen chloride relative to CFC is 100 to 10,000 ppm by mass, is reacted in the presence of a catalyst. In the second production method of the present invention, the starting material in the first single step is CFC (1B), which is also the starting material in the second production method of the present invention, and the product in the last single step is HFC (2B), which is the target product of the second production method of the present invention. CFC (1B) has two or more chlorine atoms, and HFC (2B) has zero chlorine atoms or one chlorine atom.

[0050] In each single step of the multi-step process in the second production method of the present invention, the starting material for that single step is referred to as a CFC, and the product of that single step is referred to as an HFC. Thus, in two consecutive single steps, the product HFC in the earlier single step is the starting material CFC for the later single step. However, the CFC in the first single step is CFC(1B) as described above, and the HFC in the last single step is HFC(2B) as described above. The multi-stage process in the second production method of the present invention preferably consists of two or more consecutive single steps (Y), and more preferably all the single steps in the multi-stage process consist of the single step (Y).

[0051] The single step (Y) is a step in the first production method of the present invention, in which the starting material CFC in the single step (Y) corresponds to the CFC (1A) and the product HFC in the single step (Y) corresponds to the HFC (2A). However, if the single step (Y) is not the last single step, the product HFC including by-products in the single step (Y) can be used as the starting material CFC in the next single step without post-treatment after the reaction (for example, purification such as alkaline washing or distillation). In two successive single steps (Y), the post-treatment after the reaction in the earlier single step (Y) is similar to that described above. However, it is usually preferable to carry out post-treatment after the reaction in the earlier single step (Y) (particularly treatment for reducing hydrogen chloride such as alkaline washing) in order to adjust the hydrogen chloride concentration in the later single step (Y), and to use the HFC product of the earlier single step (Y) as the starting CFC for the later single step (Y).

[0052] When the multi-stage process includes a single step other than the single step (Y), the single step is preferably a single step of substituting one or two chlorine atoms of a CFC with a hydrogen atom, and is the same as the single step (Y) except that the hydrogen chloride concentration relative to the CFC is not 100 to 10,000 ppm by mass. "A hydrogen chloride concentration not 100 to 10,000 ppm by mass" means that the hydrogen chloride concentration is less than 100 ppm by mass or more than 10,000 ppm by mass. When a single step other than the single step (Y) is an earlier single step of two consecutive single steps, and the latter single step is the single step (Y), hydrogen chloride is also produced in this earlier single step, and the hydrogen chloride concentration relative to HFCs (compounds that will become CFCs in the latter single step (Y)) in the reaction product of the earlier single step often exceeds 10,000 ppm by mass. Therefore, in this case as well, in order to adjust the hydrogen chloride concentration in the latter single step (Y), it is preferable to carry out post-treatment after the reaction of the earlier single step and use the HFC product of the earlier single step as the starting CFC for the latter single step (Y).

[0053] Therefore, as described above, in the second production method of the present invention, when the subsequent single step (Y) of two consecutive single steps is performed, it is preferable to remove at least a portion of the hydrogen chloride in the reaction mixture obtained in the previous single step (whether it is the single step (Y) or a single step other than the single step (Y)), and prepare a reactive mixture containing CFC and hydrogen before the start of the reaction from the CFC, which is the HFC obtained in the previous single step, and having a hydrogen chloride concentration relative to the CFC of 100 to 10,000 ppm by mass, and then carry out the subsequent single step (Y).

[0054] CFC(1B) includes 214cb, 224ca, 224cc, 234cc, 234cb, 215ca, 225cc, 225cb, 215cb, and 225ca. As CFC(1B), 234cc, 234cb, 225cb, 225cc and 225ca are preferred. When CFC(1B) contains a plurality of compounds, combinations of 214cb, 224ca, 224cc, 234cc and 234cb, combinations of 215ca, 225cb and 225cc, and combinations of 215cb and 225ca are preferred, and combinations of 234cc and 234cb and combinations of 225cb and 225cc are more preferred. HFC(2B) includes 254cb, 245ca, and 245cb. However, when the second production method of the present invention is intended to produce an HFC (2B) having one chlorine atom, the raw material CFC (1B) is a CFC (1B) having three or more chlorine atoms. For example, when the purpose is to produce 244cc or 244ca, the raw material CFC (1B) is 214cb, 224ca, or 224cc, or may be a mixture containing two or more of these.

[0055] When CFC (1B) is a CFC containing hydrogen atoms (e.g., 224ca, 224cc, 234cc, 234cb, etc.), the CFC (1B) is not limited to CFCs produced by the first production method of the present invention. For example, when CFC (1B) is 224cc, the 224cc does not have to be 224cc produced from 214cb, and even if the 224cc is produced from 214cb, it does not have to be 224cc produced by the first production method of the present invention.

[0056] In the single step (Y), it is preferable that the HFC obtained is mainly composed of HFC in which one chlorine atom of the raw material CFC has been replaced with a hydrogen atom. Even in this case, HFC in which two chlorine atoms of the CFC have been replaced with hydrogen atoms is usually also produced as a by-product. In order to suppress the production of HFC in which two or more chlorine atoms of the CFC have been replaced with hydrogen atoms, it is preferable to optimize the reaction conditions, such as the concentration of hydrogen chloride relative to the CFC and the molar ratio of hydrogen to the CFC. When the raw material CFC and the product HFC in the single step (Y) are a mixture of multiple compounds, the decrease in the number of chlorine atoms in the single step (Y), i.e., the difference between the average number of chlorine atoms per molecule of the raw material CFC and the average number of chlorine atoms per molecule of the product HCF, is preferably 0.8 to 1.6, more preferably 0.9 to 1.4, and particularly preferably 1.0 to 1.2. When the single step (Y) is a single step other than the first single step of a multi-step process, the feed CFC may be a mixture containing the main component HFC (HFC containing chlorine atoms) produced in the previous single step and unreacted CFC or by-product HFC (HFC containing chlorine atoms), or it may be the main component HFC after unreacted CFC and by-product HFC have been removed. In the case of the above mixture, the average number of chlorine atoms per molecule of the feed CFC means the average number of chlorine atoms in the mixture containing unreacted CFC and by-product HFC other than the main component HFC produced in the previous single step.

[0057] The single step (Y) in the second production method of the present invention is the same as that in the first production method of the present invention, and therefore, detailed description of the single step (Y) will be omitted below. [Example]

[0058] [Experimental preparation] (234cc, 244cc, 244ca manufactured) First, anhydrous aluminum chloride (25 g), CHCl3 (500 g), and 224 Ca (100 g) were placed in a 500 mL stainless steel autoclave and degassed under reduced pressure while stirring. Tetrafluoroethylene (TFE) was then added until the pressure inside the autoclave reached 0.05 MPa, and the temperature inside the autoclave was raised to 80°C. Subsequently, TFE was further added while maintaining the pressure inside the autoclave at 0.8 MPa. A total of 0.17 kg of TFE was added to the autoclave. After stirring for another hour, the mixture was cooled to room temperature, and the reaction mixture was analyzed by gas chromatography. The conversion of CHCl3 was 33%, and the selectivity for 224ca was 84%. The reaction mixture was filtered, and the crude product obtained was mixed with 102 g of molecular sieves 5A and stirred overnight for dehydration. The crude product obtained after stirring was filtered, and the resulting crude product was purified by distillation to produce 224ca (230 g).

[0059] Using 224ca obtained by the above method as a raw material, 234cc was obtained by the following method. First, a gas-phase reactor (SUS316, diameter 25 mm, length 30 cm) consisting of a cylindrical reaction tube equipped with an electric furnace was filled with activated carbon pellets (15 g) supporting palladium at a ratio of 2.0 mass% and heated to 130 °C while flowing nitrogen (N2) gas (500 NmL / min). While maintaining the reactor at atmospheric pressure (1 atm), the catalyst was dried until the moisture content of the crude gas after passing through the reactor was 20 ppm or less. After the catalyst was dried, the nitrogen supply was stopped and the reaction tube was heated to 200 °C while supplying hydrogen (180 mL / min), and then 224 Ca (0.44 g / min) was supplied. The crude gas from the reaction tube was washed with water and then passed through an alkali washing tower and molecular sieve 5A to remove acid and moisture, after which it was collected in a cold trap. Analysis of the collected crude product by gas chromatography showed that the conversion of 224ca was 98%, with 234cc being obtained with a selectivity of 24%, 244cc being obtained with a selectivity of 70%, and 244ca being obtained with a selectivity of 5%. A total of 1,000g of 224ca was reacted as above, and 596g of crude product was obtained.

[0060] The obtained crude product was distilled under atmospheric pressure in a 25-plate rectification column to obtain 234 cc (74 g), 244 cc (216 g), and 244 ca (15 g).

[0061] (235cc, 235ca production) First, a gas-phase reactor (SUS316, diameter 25 mm, length 30 cm) consisting of a cylindrical reaction tube equipped with an electric furnace was filled with activated carbon pellets (15 g) supporting palladium at a ratio of 2.0 mass%, and the temperature was raised to 130 ° C while flowing nitrogen (N ) gas (500 NmL / min). While maintaining the reactor at atmospheric pressure (1 atm), the catalyst was dried until the moisture content of the crude gas after passing through the reactor was 20 ppm or less. After the catalyst drying was completed, the nitrogen supply was stopped, and the reaction tube was heated to 190 ° C while supplying hydrogen (180 mL / min), and then 225cb (AGC, 0.44 g / min) was supplied. The crude gas from the reaction tube was washed with water and then passed through an alkali washing tower and molecular sieve 5A to remove acid and moisture, after which it was collected in a cold trap. Analysis of the collected crude product by gas chromatography revealed that the conversion of 225cb was 60%, with 235cc and 235ca being obtained at selectivities of 70% and 20%, respectively. A total of 1,000 g of 225cb was reacted in the above manner, yielding 730 g of crude product.

[0062] The obtained crude product was distilled under atmospheric pressure in a 25-plate rectification column to obtain 235 cc (201 g) and 235 ca (80 g).

[0063] (235cb production) First, a gas-phase reactor (SUS316, diameter 25 mm, length 30 cm) consisting of a cylindrical reaction tube equipped with an electric furnace was filled with activated carbon pellets (15 g) supporting palladium at a ratio of 2.0 mass% and heated to 130 °C while flowing nitrogen (N2) gas (500 NmL / min). While maintaining the reactor at atmospheric pressure (1 atm), the catalyst was dried until the moisture content of the crude gas after passing through the reactor was 20 ppm or less. After the catalyst drying was completed, the nitrogen supply was stopped, and the reaction tube was heated to 190 °C while supplying hydrogen (180 mL / min), and then 225 Ca (AGC, 0.44 g / min) was supplied. The crude gas from the reaction tube was washed with water and then passed through an alkali washing tower and molecular sieve 5A to remove acid and moisture, after which it was collected in a cold trap. Analysis of the collected crude product by gas chromatography showed that the conversion of 225ca was 75%, and 235cb was obtained with a selectivity of 60%. A total of 1,000 g of 225ca was reacted as described above, yielding 751 g of crude product.

[0064] The resulting crude product was subjected to atmospheric distillation in a 25-plate distillation column to obtain 235cb (250 g).

[0065] [Example 1] A palladium catalyst support (2.0% by mass of palladium / 100% by mass of crushed activated carbon) was loaded into a gas-phase reactor (Inconel® 600, 26 mm diameter, 60 cm long) equipped with a salt bath furnace. The catalyst support was filled with palladium catalyst, which supported palladium at a ratio of 2.0% by mass to 100% by mass of crushed activated carbon. The reactor was heated to 200°C using a salt bath furnace. 234 cc of raw materials, hydrogen, and hydrogen chloride were added. The catalyst was contacted with the catalyst for 20 seconds so that the ratio of the molar flow rates of 234 cc to hydrogen (H2) per unit time (234 cc / H2) was 1 / 2 and the ratio of the molar flow rates of hydrogen chloride (HCl) to 234 cc per unit time (HCl / 234 cc) was the ratio specified for each condition. The product gas was then washed with water, passed through an alkali scrubber and a molecular sieve 5A, and collected in a cold trap. The collected crude product was analyzed by gas chromatography. The same experiment was also carried out using 244cc and 244ca of the raw material compound. The generated gas was analyzed using gas chromatography (GC). The column used was a DB-1301 (length 60 m × inner diameter 250 μm × thickness 1 μm, manufactured by Agilent Technologies, Inc.). From the GC analysis results, the conversion rate, selectivity, and generation rate were calculated using the following formula: Conversion rate of raw material compound (%) = {(amount of raw material compound (moles) supplied to the reactor - amount of raw material compound (moles) contained in the generated gas) / amount of raw material compound (moles) supplied to the reactor} × 100 Selectivity of product compound (%) = {amount of product compound contained in product gas (moles) / amount of raw material compound consumed in the reaction (moles)} × 100 Production rate of product compound (%) = (conversion rate of raw material compound × selectivity of product compound) × 100

[0066] The conversion rate of the raw material compounds and the selectivity of each compound produced are shown in Table 1 together with the reaction conditions (temperature of the salt bath furnace (reaction temperature), HCl concentration in the raw material).

[0067] [Table 1]

[0068] The results in Table 1 show that the HFC production process of the present invention has an excellent conversion rate of CFC (1A). Furthermore, the "Other selectivity" in the table shows that the amount of by-products produced is small.

[0069] [Examples 2-3] The reaction was carried out in the same manner as in Example 1, except that the raw material compounds and reaction conditions were changed as shown in Tables 2 and 3. The conversion rates of the raw material compounds and the selectivities of each compound produced are shown in Tables 2 and 3, along with the reaction conditions (temperature of the salt bath furnace (reaction temperature), HCl concentration in the raw materials).

[0070] [Table 2]

[0071] [Table 3]

[0072] The results in Tables 2 and 3 show that the HFC production process of the present invention has an excellent conversion rate of CFC (1A). Furthermore, the "Other selectivity" in the tables shows that the amount of by-products produced is small.

[0073] [Examples 4-5] The reaction was carried out in the same manner as in Example 1, except that the raw material compounds were changed to a mixture of 234cc, 244cc, and 244ca as shown in Table 4. The compound composition of the reaction product for each HCl concentration in the raw material is shown in Table 4.

[0074] [Table 4]

[0075] Here, 234cc is CFC(1A), and 254cb is HFC(1B) produced from 234cc, 244cc, and 244ca. 244cc and 244ca are HFC(1B) produced from 234cc, and are also CFC(1A) used to produce 254cb. The results in Table 4 show that the HFC production process of the present invention achieves an excellent conversion rate of CFC (1A), even when multiple compounds are used as raw materials. Furthermore, the other product compositions in the table show that the amount of by-products produced is small.

[0076] [Examples 6-7] The reaction was carried out in the same manner as in Example 1, except that the raw material compounds were changed to a mixture of 225cb, 235cc, and 235ca as shown in Table 5. The compound composition of the reaction product for each HCl concentration in the raw material is shown in Table 5.

[0077] [Table 5]

[0078] Here, 225cb is CFC(1A), and 245ca is HFC(1B) produced from 225cb, 235cc, and 235ca. 235cc and 235ca are HFC(1B) produced from 225cb, and are also CFC(1A) used to produce 245ca. The results in Table 5 show that the HFC production process of the present invention has an excellent conversion rate of CFC (1A), even when multiple compounds are used as raw materials. Furthermore, the other product compositions in the table show that the amount of by-products produced is small.

[0079] [Examples 8-9] The reaction was carried out in the same manner as in Example 1, except that the raw material compounds were changed to a mixture of 225ca and 235cb as shown in Table 6. Table 6 shows the compound composition of the reaction product for each HCl concentration in the raw material.

[0080] [Table 6]

[0081] Here, 225ca is CFC(1A), and 245cb is HFC(1B) produced from 225ca and 235cb. 235cb is HFC(1B) produced from 225ca, and is also CFC(1A) used to produce 245cb. The results in Table 6 show that the HFC production process of the present invention has an excellent conversion rate of CFC (1A), even when multiple compounds are used as raw materials. Furthermore, the other product compositions in the table show that the amount of by-products produced is small.

[0082] [Examples 10 and 11] The reaction was carried out in the same manner as in Example 1, using 234 cc of the raw material compound. This was the first reaction. The hydrogen chloride concentration in the collected crude product was measured by ion chromatography (Dionex ICS-5000+ Hybrid HPIC, manufactured by Thermo Fisher Scientific). The crude product was then used as the raw material compound, and the reaction temperature was set to 220°C. The second reaction was carried out in the same manner as the first reaction. The compositions of the reaction products from the first and second reactions are shown in Example 10 in Table 7. An experiment was also carried out in the same manner as in Example 10, except that the alkali washing tower was not used during the first reaction. The results are shown in Example 11 in Table 7.

[0083] [Table 7]

[0084] The results in Table 7 show that the production method of the present invention has an excellent conversion rate of CFC(1B). It is also clear that 254cb, which is HFC(2B), is selectively obtained, and the amount of by-products produced is small.

[0085] [Examples 12 and 13] The starting compound was 225cb, and the reactions were carried out in the same manner as in Examples 10 and 11. The results are shown in Examples 12 and 13 in Table 8.

[0086] [Table 8]

[0087] The results in Table 8 show that the production method of the present invention has an excellent conversion rate of CFC(1B). It is also clear that 245ca, which is HFC(2B), is selectively obtained, and the amount of by-products produced is small. The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2021-013304, filed on January 29, 2021, are hereby incorporated by reference as part of the disclosure of the specification of the present invention.

Claims

1. A method for producing a hydrofluorocarbon (2A) in which one or two chlorine atoms of the chlorofluorocarbon (1A) are substituted with hydrogen atoms, by reacting a chlorofluorocarbon (1A) represented by the following formula (1A) with hydrogen in the presence of a catalyst, comprising: the catalyst comprises palladium or platinum; A method for producing a hydrofluorocarbon, characterized by reacting a reactive mixture containing a chlorofluorocarbon (1A), hydrogen, and hydrogen chloride, wherein the concentration of hydrogen chloride relative to the chlorofluorocarbon (1A) is 100 to 10,000 ppm by mass. CF ２ X ａ -R ｆ -CX ａ ３ (1A) (In the formula, X ａ are each independently a hydrogen atom, a fluorine atom, or a chlorine atom, and four X ａ 0 or 1 is a fluorine atom and at least one is a chlorine atom; ｆ is a fluoroalkylene group having one carbon atom.

2. The R ｆ The method according to claim 1 , wherein is a difluoromethylene group.

3. The chlorofluorocarbon (1A) is 1,3-dichloro-1,1,2,2-tetrafluoropropane, 1,1-dichloro-2,2,3,3-tetrafluoropropane, 1-chloro-1,1,2,2-tetrafluoropropane, 1-chloro-2,2,3,3-tetrafluoropropane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-1,2,2,3,3-pentafluoropropane, 1-chloro-1,1,2,2,3-pentafluoropropane, 1-chloro-1,2,2,3,3-pentafluoropropane, 3,3-dichloro-1,1,1,2,2-pentafluoropropane and 3-chloro-1,1,1,2,2-pentafluoropropane. The production method according to claim 1 or 2, which is at least one selected from the group consisting of pentafluoropropane.

4. The hydrofluorocarbon (2A) produced is mainly composed of a hydrofluorocarbon in which one chlorine atom of the chlorofluorocarbon (1A) is substituted with a hydrogen atom. The production method according to any one of claims 1 to 3.

5. The method according to any one of claims 1 to 4, wherein the chlorofluorocarbon (1A) and hydrogen are reacted in a gas phase.

6. The method according to any one of claims 1 to 5, wherein the reaction temperature is 150 to 350°C.

7. A method for producing a hydrofluorocarbon (2B) having 0 or 1 chlorine atom by reacting a chlorofluorocarbon (1B) represented by the following formula (1B) with hydrogen, The method comprises a multi-step process in which a single step of substituting one or two chlorine atoms of a chlorofluorocarbon with a hydrogen atom is repeated at least twice, At least one single step in the multi-stage process is a single step (Y) in which a reactive mixture containing a chlorofluorocarbon, hydrogen, and hydrogen chloride before the start of the reaction is reacted in the presence of a catalyst, the reactive mixture having a hydrogen chloride concentration relative to the chlorofluorocarbon of 100 to 10,000 ppm by mass, A method for producing a hydrofluorocarbon having 0 or 1 chlorine atom, characterized in that the catalyst contains palladium or platinum. CF ２ X ｂ -R ｆ -CX ｂ ３ (1B) (In the formula, X ｂ are each independently a hydrogen atom, a fluorine atom, or a chlorine atom, and four X ｂ 0 or 1 of R is a fluorine atom, and 2 to 4 of R are chlorine atoms. ｆ is a fluoroalkylene group having one carbon atom.

8. The R ｆ The method according to claim 7, wherein is a difluoromethylene group.

9. The chlorofluorocarbon (1B) is at least one selected from the group consisting of 1,3-dichloro-1,1,2,2-tetrafluoropropane, 1,1-dichloro-2,2,3,3-tetrafluoropropane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-1,2,2,3,3-pentafluoropropane, and 3,3-dichloro-1,1,1,2,2-pentafluoropropane. The production method according to claim 7 or 8.

10. The production method according to any one of claims 7 to 9, wherein the hydrofluorocarbon (2B) is at least one selected from the group consisting of 1,1,2,2-tetrafluoropropane, 1,1,2,2,3-pentafluoropropane, and 1,1,1,2,2-pentafluoropropane.

11. The method according to any one of claims 7 to 10, wherein the main product in the single step (Y) is a compound in which one chlorine atom of a chlorofluorocarbon is substituted with a hydrogen atom.

12. The method according to any one of claims 7 to 11, wherein hydrogen is reacted in a gas phase in the single step (Y).

13. The method according to any one of claims 7 to 12, wherein in the single step (Y), hydrogen is reacted at a reaction temperature of 150 to 350°C.

14. In two successive single steps: At least the subsequent single step is the single step (Y), The method according to any one of claims 7 to 13, wherein at least a portion of the hydrogen chloride in the reaction mixture obtained in the previous single step is removed to prepare a reactive mixture containing chlorofluorocarbon and hydrogen before the start of the reaction from the chlorofluorocarbon, which is the hydrofluorocarbon obtained in the previous single step, and having a hydrogen chloride concentration relative to the chlorofluorocarbon of 100 to 10,000 ppm by mass, and the subsequent single step (Y) is carried out using such a reactive mixture.

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