JP7779271B2 - Method for producing hydrofluorocarbons by hydrogen reduction reaction - Google Patents

Description

The present invention relates to a method for producing hydrofluorocarbons by hydrogen reduction reaction.

Hydrofluorocarbons (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 (HFOs). Specifically, Patent Document 1 describes the use of 1-chloro-2,2,3,3-tetrafluoropropane (244ca) as a synthetic raw material for producing 1-chloro-2,3,3-trifluoropropene (1233yd). Patent Document 2 describes the use of 1-chloro-1,1,2,2-tetrafluoropropane (244cc) as a synthetic raw material for producing 2,2,3,3-tetrafluoropropene (1234yf).

International Publication No. 2018/131394 Patent No. 5348240

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 is difficult to control the hydrogen reduction reaction, and it has not been possible 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.

After extensive research to solve the above problem, the inventors discovered that the above problem can be solved by the following configuration.

[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.
CF ₂ X ^a -R ^f -CX ^a ₃ (1A)
(In the formula, X ^a each independently represents a hydrogen atom, a fluorine atom, or a chlorine atom, and 0 or 1 of the four X ^a is a fluorine atom and at least one is a chlorine atom, and R ^f is a fluoroalkylene group having 1 or more carbon atoms.)
[2] The method according to [1], wherein ^Rf is a difluoromethylene group.
[3] The production 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 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 in the presence of a catalyst, the 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.
CF ₂ X ^b -R ^f -CX ^b ₃ (1B)
(In the formula, X ^b 's are each independently a hydrogen atom, a fluorine atom, or a chlorine atom, and of the four X ^b's , 0 or 1 is a fluorine atom and 2 to 4 are chlorine atoms, and R ^f is a fluoroalkylene group having 1 or more carbon atoms.)
[9] The method according to [8], wherein ^Rf is a difluoromethylene group.
[10] The production 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 subsequent single step is the single step (Y),
The production method according to any one of [8] to [14], in which 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 the 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.

The present invention provides a method for producing HFCs with excellent CFC conversion and low production of by-products.

One of the processes for producing an HFC of the present invention (hereinafter also simply referred to as the "first production process of the present invention") is a process 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 process characterized by carrying out the reaction using a reactive mixture containing CFC (1A), hydrogen, and hydrogen chloride, in which the concentration of hydrogen chloride relative to CFC (1A) is 100 to 10,000 ppm by mass:
CF ₂ X ^a -R ^f -CX ^a ₃ (1A)
(In the formula, X ^a each independently represents a hydrogen atom, a fluorine atom, or a chlorine atom, and 0 or 1 of the four X ^a is a fluorine atom and at least one is a chlorine atom, and R ^f is a fluoroalkylene group having 1 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 be composed 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, 1,1,3-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) may be produced from 1,1,1,3-tetrachloro-2,2,3,3-tetrafluoropropane (hereinafter also referred to as 214cb).

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,
a multi-step process in which a single step of substituting one or two chlorine atoms of a CFC with a hydrogen atom is repeated at least twice,
The method for producing an HFC having 0 or 1 chlorine atom is characterized in that at least one single step among the multi-stage steps is a single step (Y) of reacting a reactive mixture containing a CFC, hydrogen, and hydrogen chloride before the start of the reaction, in which the concentration of hydrogen chloride relative to the CFC is 100 to 10,000 ppm by mass, in the presence of a catalyst.
CF ₂ X ^b -R ^f -CX ^b ₃ (1B)
(In the formula, X ^b 's are each independently a hydrogen atom, a fluorine atom, or a chlorine atom, and of the four X ^b's , 0 or 1 is a fluorine atom and 2 to 4 are chlorine atoms, and R ^f is a fluoroalkylene group having 1 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 it is more preferable that all of the single steps are the single step (Y).

CFCs and HFCs
^Rf in CFC (1A) represented by formula (1A) and CFC (1B) represented by formula (1B) is a fluoroalkylene group, i.e., an alkylene group having at least one fluorine atom. The fluoroalkylene group is preferably a linear fluoroalkylene group. The number of carbon atoms in ^Rf is preferably 1 to 3, more preferably 1 or 2, and particularly preferably 1. The number of fluorine atoms in ^Rf is preferably the same as 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). ^Rf is most preferably a difluoromethylene group.
Hereinafter, the present invention will be described taking as an example the case where ^Rf is a difluoromethylene group.

When one of the four X ^a's in CFC (1A) represented by formula (1A) is a fluorine atom, there are cases where X ^a on the CF ₂ X ^a - side is a fluorine atom, and cases where one of the three X ^a's on the -CX ^a ₃ side is a fluorine atom.
When none of the four X ^a's is a fluorine atom, the number of chlorine atoms in the four X ^a's is 1 to 4, and the number of hydrogen atoms is 0 to 3. When any one of the four X ^a's 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 the chlorine atoms have been substituted with hydrogen atoms.

When one of the four X ^b in CFC (1B) represented by formula (1B) is a fluorine atom, there are cases where X ^b on the CF ₂ X ^b - side is a fluorine atom and cases where one of the three X ^b on the -CX ^b ₃ side is a fluorine atom.
When none of the four X ^b's is a fluorine atom, the number of chlorine atoms in the four X ^b's is 2 to 4, and the number of hydrogen atoms is 0 to 2. When any one of the four X ^b's 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 chlorine atom or no chlorine atom.

When ^Rf is a difluoromethylene group, the CFCs represented by formula (1A) and formula (1B), as well as compounds produced by substituting their chlorine atoms one by one with hydrogen atoms, and their production flow are shown below.
In the following chemical formula, 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.

[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 of them is a 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 types of CFC (1A) produces two corresponding types of HFC (2A). Furthermore, since two or more types of HFC (2A) can be produced from one CFC (1A) compound, when CFC (1A) is a mixture of two or more compounds, the resulting HFC (2A) can be a mixture of three or more types of HFC (2A).
On the other hand, the same HFC (2A) may be produced from each of two different CFCs (1A) (for example, 254cb may be produced from 244cc and 244ca), and therefore, a mixture of such two CFCs (1A) may be used as a raw material to produce a product containing one HFC (2A) as a main component.

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 substituted with two hydrogen atoms. In some cases, three or more chlorine atoms may be substituted with hydrogen atoms, but it is preferable that the number of substitutions of three or more chlorine atoms is small. The fewer the number of substitutions 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) is substituted with 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 lead to 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 an HFC in which two chlorine atoms of CFC (1A) have been substituted with a hydrogen atom as a by-product.

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 on the base side 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 on the tip side of the arrow in the production flow.
The starting material compound CFC (1A) is preferably a CFC produced from a 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 a CFC produced from a 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 a CFC produced by the first production method of the present invention.

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), and 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, or 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.

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). If 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 the 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.

In the reactive mixture, CFC (1A) is preferably contained as a major component. The content of CFC (1A) relative to the total mass of CFC (1A) and other compounds (excluding hydrogen, hydrogen chloride, and diluents) in the reactive mixture 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 an HFC having no chlorine atom.

(hydrogen)
The amount of hydrogen (H ₂ ) in the reactive mixture is preferably 0.5 to 10.0 mol, more preferably 0.8 to 8.0 mol, and particularly preferably 1.0 to 5.0 mol, per mol of chlorine atoms contained in CFC (1A). If the amount of hydrogen is less than 0.5 mol, the production rate of HFC (2A) will be low, and if it exceeds 10.0 mol, the amount of by-products produced will increase, such as HFCs in which three or more chlorine atoms in CFC (1A) have been replaced with hydrogen atoms.
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 (H ₂ ) in the reactive mixture is preferably 0.5 to 5.0 mol, more preferably 0.8 to 3.0 mol, and particularly preferably 1.0 to 2.0 mol, per mol of chlorine atom contained in CFC (1A).

(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.

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).

In order to improve the reactivity of the catalyst, it is preferable to use the catalyst 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, and is more preferably alumina or activated carbon, more preferably activated carbon, from the viewpoint of improving the conversion rate of CFC (1A) and the selectivity of HFC (2A).

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 standpoint of catalyst durability, activated carbon obtained from plant materials is preferred as the substrate for supporting the hydrogenation catalyst, with coconut shell activated carbon being particularly preferred. The activated carbon may be in any shape, including formed charcoal with a length of approximately 2 to 10 mm, crushed charcoal with a mesh size of approximately 4 to 50, and granular charcoal.

Specific examples of catalyst-supported carriers (hereinafter also referred to as catalyst carriers) include palladium-supported alumina, palladium-supported activated carbon, and platinum-supported activated carbon, which are preferred because they can maintain catalytic activity for long periods of time.

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% by mass, more preferably 0.5 to 3.0% by mass, even more preferably 1.0 to 3.0% by mass, and most preferably 1.5 to 2.5% by 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 production of by-products can be reduced.

(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 excessive, CFC (1A) from which part of the hydrogen chloride has been removed by a known method such as alkali washing can be used.

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, and more preferably 200 to 2,000 ppm by mass. If the hydrogen chloride concentration is below the upper limit, hydrogen chloride does not adsorb to the active sites of the catalyst, improving the conversion rate of CFC (1A). If the hydrogen chloride concentration is above the lower limit, excessive substitution of chlorine atoms in CFC (1A) with hydrogen atoms can be prevented, allowing the desired HFC (2A) to be obtained with high purity.

(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 a catalyst. Hereinafter, 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.

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 the reaction time can be shortened and the production of by-products can be suppressed. The gas phase reaction can include 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).

A specific procedure for the gas phase reaction is to supply raw materials, namely, CFC (1A) heated to a gaseous state, hydrogen, and hydrogen chloride, into a reactor, and then bring the gaseous CFC (1A) and hydrogen into contact with a catalyst packed in the reactor, thereby obtaining 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, suppressing catalyst deactivation, etc. Specific examples of the dilution gas include nitrogen, carbon dioxide, helium, argon, etc. Two or more types of dilution gases may be used in combination.

The amount of dilution gas supplied to the reactor is preferably 0.1 moles or more, and more preferably 0.5 moles or more, per 1.0 mole of CFC (1A), from the viewpoints of maintaining a low maximum catalyst temperature, reducing by-product generation, suppressing catalyst degradation, and maintaining catalyst activity for an extended period of time. Furthermore, from the viewpoint of the recovery rate of the dilution gas, the amount of dilution 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).

The reaction temperature (temperature inside the reactor) in the first production method of the present invention 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.

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

The reaction pressure can be either atmospheric or elevated, but from the standpoint of ease of industrial implementation, it is preferable to carry out the reaction at atmospheric pressure.

The reactor is not particularly limited in shape or structure, as long as it can introduce CFC (1A) and hydrogen and react with them. Examples of such reactors include glass reactors, SUS reactors, glass-lined reactors, and resin-lined reactors. The reactor is typically equipped with a temperature control unit that adjusts the temperature inside the reactor. The temperature control unit can be any unit that can adjust the reaction temperature between CFC (1A) and hydrogen. Examples of such a unit include an oil bath. The temperature control unit may be integrally provided with the reactor.

A catalyst (preferably a catalyst carrier) is placed inside such a reactor, forming a catalyst layer as the reaction site. The catalyst carrier may be placed in either a fixed bed or fluidized bed. In addition, if the reactor is a fixed bed, it may be either a horizontal or vertical fixed bed. However, a vertical fixed bed is preferred, as it is easier to prevent concentration distribution of each component in a multi-component mixed gas from occurring depending on location due to differences in specific gravity.

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

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

The production method of the present invention may be carried out in a batch mode or a continuous mode. When carried out in a batch mode, 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 the hydrogen.

In a continuous reaction, CFC (1A) and hydrogen are continuously supplied to the reactor at a predetermined molar ratio and a predetermined supply rate, and the two components are allowed to contact each other for a predetermined period of time. One component may be supplied first, followed by the other, or both may be supplied simultaneously. When supplying either CFC (1A) or hydrogen first, the previously supplied component is retained in the reactor, and the other component is then supplied to the reactor, allowing the CFC (1A) and hydrogen to contact the catalyst for a predetermined period of time. When supplying CFC (1A) and hydrogen simultaneously to the reactor, the CFC (1A) and hydrogen may be supplied to the reactor through separate supply pipes, or they may be premixed and supplied through a single supply pipe. Because heat of adsorption between CFC (1A) and the catalyst is generated during the initial 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 reaction temperature control. When the production process 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.

The product gas discharged from the reactor outlet contains the target substance, CFC (1A), an HFC (hereinafter also referred to as HFC (2A)) 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.

Examples of CFC(1A) include 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.

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 manner, 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 distillative 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. Specific examples of components having a boiling point lower than that of the desired HFC (2A) include, when the HFC (2A) is 254cb, 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.

When removing the catalyst from the reactor after the reaction in the first production method of the present invention is completed, 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, and the catalyst is removed in a hydrated state.

In addition, in the second manufacturing method of the present invention, if two consecutive steps of a multi-stage process are both single steps (Y) and the previous single step (Y) is a process consisting of the first manufacturing method of the present invention, purification by alkaline washing of the generated gas or distillation of the outlet gas, etc., is not a necessary process.

When the first production method of the present invention is carried out in the 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, or pyridine. 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 the liquid phase, the reaction temperature is preferably room temperature (approximately 25°C) to approximately 150°C, and the reaction pressure is preferably atmospheric pressure to approximately 5 MPa. The reaction time is usually preferably approximately 1 to 72 hours. When the production method of the present invention is carried out in the liquid phase as a batch process, the reaction time is preferably 1 to 9 hours.

[Second production method of the present invention]
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) 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 of the single steps 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.

In each single step of the multi-stage process in the second production method of the present invention, the starting material of that single step is called a CFC, and the product of that single step is called an HFC. Thus, in two consecutive single steps, the product HFC of the earlier single step becomes the starting material CFC of the later single step. However, the CFC of the first single step is CFC(1B) as described above, and the HFC of 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 successive single steps (Y), and more preferably all the single steps in the multi-stage process consist of the single step (Y).

The single step (Y) is a step in the first production method of the present invention, in which the starting CFC of the single step (Y) corresponds to the CFC (1A) and the product HFC of the single step (Y) corresponds to the HFC (2A). However, if the single step (Y) is not the last single step, the product HFC containing by-products can be used as the starting CFC of 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 of the earlier single step (Y) is similar to that described above. However, it is usually preferable to carry out post-treatment after the reaction of 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).

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. The hydrogen chloride concentration not being 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 HFC (compound that will become CFC 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).

Therefore, as described above, in the second production method of the present invention, when the subsequent single step (Y) is one of two consecutive single steps, 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 step (Y) or a single step other than step (Y)), and prepare a reactive mixture containing CFC and hydrogen before the start of the reaction from the CFC (HFC) obtained in the previous single step, where the hydrogen chloride concentration relative to the CFC is 100 to 10,000 ppm by mass, and then carry out the subsequent single step (Y).

Examples of CFC(1B) include 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.

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

In the single step (Y), it is preferable that the HFC obtained is mainly composed of an HFC in which one chlorine atom of the raw CFC has been substituted with a hydrogen atom. Even in this case, an HFC in which two chlorine atoms of the CFC 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 the CFC have been substituted 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 starting CFC and the product HFC in the single step (Y) are mixtures of a plurality of 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 starting CFC and the average number of chlorine atoms per molecule of the product HFC, 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-stage 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.

Since the single step (Y) in the second manufacturing method of the present invention is the same as that in the first manufacturing method of the present invention, a detailed explanation of the single step (Y) will be omitted below.

[Experimental preparation]
(234cc, 244cc, 244ca production)
First, anhydrous aluminum chloride (25 g), CHCl ₃ (500 g), and 224 ca (100 g) were placed in a 500 mL stainless steel autoclave and degassed under reduced pressure while stirring. Then, tetrafluoroethylene (TFE) was fed into the autoclave until the pressure inside the autoclave reached 0.05 MPa, and the temperature inside the autoclave was raised to 80° C. Thereafter, TFE was further fed while maintaining the pressure inside the autoclave at 0.8 MPa. The total amount of TFE fed to the autoclave was 0.17 kg.
After stirring for another hour, the mixture was cooled to room temperature, and the reaction mixture was analyzed by gas chromatography. The conversion of CHCl ₃ was 33%, and the selectivity for 224ca was 84%. The reaction mixture was filtered, and 102 g of molecular sieves 5A was added to the crude liquid obtained. The mixture was stirred overnight and dehydrated. The crude product obtained after stirring was filtered, and distilled and purified to produce 224ca (230 g).

Using the 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) carrying palladium at a ratio of 2.0 mass%, and heated to 130 ° C. while flowing nitrogen (N ₂ ) gas (500 NmL / min). While maintaining the reactor at atmospheric pressure (1 atm), the catalyst was dried until the moisture content in the crude gas after passing through the reactor was 20 ppm or less. After completion of drying of the catalyst, 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, and then collected in a cold trap. Analysis of the collected crude product by gas chromatography revealed that the conversion of 224ca was 98%, with 234cc being obtained at a selectivity of 24%, 244cc being obtained at a selectivity of 70%, and 244ca being obtained at a selectivity of 5%. A total of 1,000g of 224ca was reacted in the above manner, yielding 596g of crude product.

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

(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) carrying palladium at a ratio of 2.0% by mass, and heated to 130 ° C. while flowing nitrogen (N ₂ ) gas (500 NmL / min). While maintaining the reactor at atmospheric pressure (1 atm), the catalyst was dried until the moisture content in 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 a selectivity of 70% for 235cc and a selectivity of 20% for 235ca. A total of 1,000 g of 225cb was reacted in the above manner to obtain 730 g of crude product.

The obtained crude product was distilled at atmospheric pressure in a 25-plate distillation column to obtain 235 cc (201 g) and 235 ca (80 g).

(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) carrying palladium at a ratio of 2.0 mass%, and heated to 130 ° C. while flowing nitrogen (N ₂ ) gas (500 NmL / min). While maintaining the reactor at atmospheric pressure (1 atm), the catalyst was dried until the moisture content in the crude gas after passing through the reactor was 20 ppm or less. After completion of drying of the catalyst, 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 revealed 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 in the above manner, yielding 751 g of crude product.

The obtained crude product was distilled at atmospheric pressure in a 25-plate distillation column to obtain 235cb (250g).

[Example 1]
A gas-phase reactor (Inconel (registered trademark) 600, 26 mm diameter, 60 cm long) consisting of a cylindrical reaction tube equipped with a salt bath furnace was filled with a palladium catalyst support in which palladium was supported at a ratio of 2.0 mass% to 100 mass% of activated carbon (crushed carbon), forming a catalyst layer 40 cm high. After heating the reactor to 200°C using a salt bath furnace, 234 cc of raw material compounds, hydrogen, and hydrogen chloride were supplied and contacted with the catalyst for 20 seconds so that the molar flow rate ratio per unit time of 234 cc to hydrogen (H ₂ ) (234 cc/H ₂ ) became 1/2 and the molar flow rate ratio per unit time of hydrogen chloride (HCl) to 234 cc (HCl/234 cc) became the ratio determined for each condition, thereby obtaining a product gas. The product gas was 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, except that the raw material compounds were changed to 244 cc and 244 ca.
The generated gas was analyzed using gas chromatography (GC). A DB-1301 column (length 60 m × inner diameter 250 μm × thickness 1 μm, manufactured by Agilent Technologies Inc.) was used. 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 (moles) of raw material compound supplied to the reactor - amount (moles) of raw material compound contained in the generated gas) / amount (moles) of raw material compound supplied to the reactor} × 100
Selectivity (%) of product compound = {amount (moles) of product compound contained in product gas / amount (moles) of raw material compound consumed in reaction} × 100
Production rate of product compound (%)=(conversion rate of raw material compound×selectivity of product compound)×100

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

The results in Table 1 show that the HFC production method 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 low.

[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 the produced compounds 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).

The results in Tables 2 and 3 show that the HFC production method 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 low.

[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 234 cc, 244 cc, and 244 ca as shown in Table 4. The compound compositions of the reaction products at each HCl concentration in the raw materials are shown in Table 4.

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 is excellent in the conversion 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.

[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 compositions of the reaction products for each HCl concentration in the raw materials are shown in Table 5.

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 is excellent in the conversion of CFC (1A) even when multiple compounds are used as raw materials. Furthermore, the "Other" product composition in the table shows that the amount of by-products produced is small.

[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.

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 is excellent in the conversion of CFC (1A) even when multiple compounds are used as raw materials. Furthermore, the "Other" product composition in the table shows that the amount of by-products produced is small.

[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 designated 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), and then the crude product was used as the raw material compound. The reaction temperature was set to 220°C, and a 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. In addition, 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.

The results in Table 7 show that the production method of the present invention has an excellent conversion rate of CFC (1B). It also shows that 254cb, an HFC (2B), is selectively obtained, with a low amount of by-products produced.

[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.

The results in Table 8 show that the production method of the present invention is excellent in the 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 the disclosure of the specification of the present invention.

Claims (14)

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, ^Xa each independently represents a hydrogen atom, a fluorine atom, or a chlorine atom, and 0 or 1 of the four ^Xa is a fluorine atom and at least one is a chlorine atom; and ^Rf is a fluoroalkylene group having 1 carbon atom.) The method according to claim 1 , wherein R ^f is a difluoromethylene group. The manufacturing method according to claim 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. The production method described in any one of claims 1 to 3, wherein the hydrofluorocarbon (2A) produced is primarily composed of a hydrofluorocarbon in which one chlorine atom of the chlorofluorocarbon (1A) has been substituted with a hydrogen atom. The method according to any one of claims 1 to 4 , wherein the chlorofluorocarbon (1A) and hydrogen are reacted in a gas phase. The method according to any one of claims 1 to 5 , wherein the reaction temperature is 150 to 350°C. 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 's are each independently a hydrogen atom, a fluorine atom, or a chlorine atom, and of the four X ^b's , 0 or 1 is a fluorine atom and 2 to 4 are chlorine atoms, and R ^f is a fluoroalkylene group having 1 carbon atom.) The method according to claim 7 , wherein R ^f is a difluoromethylene group. 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 . 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. 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. The method according to any one of claims 7 to 11 , wherein hydrogen is reacted in a gas phase in the single step (Y). 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. In two successive single steps:
At least the subsequent single step is the single step (Y),
The production 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 that is the hydrofluorocarbon obtained in the previous single step, the reactive mixture 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.