Method for producing reaction gas containing (E)-1,2-difluoroethylene

Abstract

This invention provides a method for producing a reaction gas containing R-1132(E) with a higher selectivity than existing methods. Specifically, this invention provides a method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)), (1) comprising a step of feeding a feed gas containing at least one fluoromethane selected from dichlorofluoromethane (R-22), difluoromethane (R-32), and fluoromethane (R-41) into a reaction including thermal decomposition to obtain the reaction gas, and (2) wherein the water vapor content in the feed gas is 1% by volume or less.

Description

Technical Field

[0001] The present invention relates to a method for producing a reaction gas containing (E)-1,2-difluoroethylene. Background Art

[0002] (E)-1,2-difluoroethylene (hereinafter also referred to as "R-1132(E)") has a low global warming potential (GWP) and is therefore attracting attention as a refrigerant to replace difluoromethane (R-32) and 1,1,1,2,2-pentafluoroethane (R-125), which are greenhouse gases.

[0003] Patent Document 1 discloses a method for producing 1,2-difluoroethylene, characterized in that 1,2-difluoroethylene is produced from a compound represented by the following formula (1): CH2FX(1) (where X is a halogen atom) by a synthesis reaction accompanied by thermal decomposition.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-241348 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] The object of the present invention is to provide a method for producing a reaction gas containing R-1132(E) with a higher selectivity than the conventional methods.

[0009] Technical solutions for solving technical problems

[0010] The present invention includes, for example, the inventions described in the following items.

[0011] Item 1. A method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)),

[0012] (1) a step of subjecting a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), difluoromethane (R-32) and fluoromethane (R-41) to a reaction including thermal decomposition to obtain the above-mentioned reaction gas,

[0013] (2) The water vapor content in the above-mentioned raw material gas is 1 volume % or less.

[0014] Item 2. A method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)),

[0015] (1) a step of subjecting a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), chlorofluoromethane (R-31), difluoromethane (R-32) and fluoromethane (R-41) to a reaction including thermal decomposition to obtain the above-mentioned reaction gas,

[0016] (2) The above reaction is carried out using a metal reaction vessel having an iron content of 10% by mass or less.

[0017] Item 3. A method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)),

[0018] (1) a step of subjecting a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), chlorofluoromethane (R-31), difluoromethane (R-32) and fluoromethane (R-41) to a reaction including thermal decomposition to obtain the above-mentioned reaction gas,

[0019] (2) The content of at least one inert gas selected from nitrogen, argon, hydrofluorocarbons and carbon dioxide in the raw material gas is 10 to 90% by volume.

[0020] Item 4. A method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)),

[0021] (1) a step of subjecting a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), chlorofluoromethane (R-31), difluoromethane (R-32) and fluoromethane (R-41) to a reaction including thermal decomposition to obtain the above-mentioned reaction gas,

[0022] (2) The content of the fluoromethane in the raw material gas is 90 to 100% by volume.

[0023] Item 5. The production method according to any one of Items 1 to 4, wherein the raw material gas contains R-32.

[0024] Item 6. The production method according to any one of Items 1 to 5, wherein the reaction is performed at 750 to 1050°C.

[0025] Item 7. The production method according to any one of Items 1 to 6, wherein the reaction is performed at 0 to 0.6 MPaG.

[0026] Item 8. A composition comprising:

[0027] (E)-1,2-difluoroethylene (R-1132(E)); and

[0028] At least one compound selected from the group consisting of 3,3,3-trifluoropropyne (TFP), propyne and 1,1,1,2-tetrafluoroethane (R-134a).

[0029] Item 9. The composition according to Item 8, wherein the content of TFP is 1 mass % or less based on the total amount of the composition.

[0030] Effects of the Invention

[0031] According to the method for producing a reaction gas containing R-1132(E) of the present invention, R-1132(E) can be produced with a higher selectivity (selectivity in the reaction gas) than that of the conventional method. DETAILED DESCRIPTION

[0032] In this specification, the "conversion rate" means the ratio (mol %) of the total molar amount of compounds other than fluoromethanes contained in the outflow gas (=reaction gas) from the reactor outlet to the molar amount of fluoromethanes supplied to the reactor.

[0033] In this specification, "selectivity" means the ratio (mol %) of the molar amount of the target compound (R-1132(E)) contained in the outflow gas (=reaction gas) from the reactor outlet to the total molar amount of compounds other than fluoromethanes contained in the outflow gas.

[0034] In the present specification, a numerical range expressed by "to" means a range including the numerical values ​​described before and after "to" as the lower limit and the upper limit.

[0035] The method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)) of the present invention is characterized in that it includes a step of supplying a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), chlorofluoromethane (R-31), difluoromethane (R-32) and fluoromethane (R-41) to a reaction including thermal decomposition (a synthesis reaction accompanied by thermal decomposition of the fluoromethane) to obtain a reaction gas containing R-1132(E). Specifically, it can be roughly divided into the following embodiments 1 to 4.

[0036] (Implementation Method 1)

[0037] A method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)).

[0038] (1) a step of subjecting a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), difluoromethane (R-32) and fluoromethane (R-41) to a reaction including thermal decomposition to obtain the reaction gas,

[0039] (2) The water vapor content in the raw material gas is 1 volume % or less.

[0040] (Implementation Method 2)

[0041] A method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)).

[0042] (1) a step of subjecting a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), chlorofluoromethane (R-31), difluoromethane (R-32) and fluoromethane (R-41) to a reaction including thermal decomposition to obtain the reaction gas,

[0043] (2) The reaction is carried out using a metal reaction vessel having an iron content of 10% by mass or less.

[0044] (Implementation method 3)

[0045] A method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)).

[0046] (1) a step of subjecting a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), chlorofluoromethane (R-31), difluoromethane (R-32) and fluoromethane (R-41) to a reaction including thermal decomposition to obtain the reaction gas,

[0047] (2) The content of at least one inert gas selected from nitrogen, argon, hydrofluorocarbons and carbon dioxide in the raw material gas is 10 to 90% by volume.

[0048] (Implementation 4)

[0049] A method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)).

[0050] (1) a step of subjecting a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), chlorofluoromethane (R-31), difluoromethane (R-32) and fluoromethane (R-41) to a reaction including thermal decomposition to obtain the above-mentioned reaction gas,

[0051] (2) The content of the fluoromethane in the raw material gas is 90 to 100% by volume.

[0052] According to the method for producing a reaction gas containing R-1132(E) of the present invention having the above-mentioned characteristics, a reaction gas containing R-1132(E) can be produced with a higher selectivity (selectivity in the reaction gas) than the conventional method.

[0053] 1.Method for producing reaction gas containing R-1132(E)

[0054] Hereinafter, the above-mentioned Embodiments 1 to 4 will be described respectively.

[0055] (Implementation Method 1)

[0056] Embodiment 1 is a method for producing a reaction gas containing R-1132(E), characterized in that:

[0057] (1) a step of subjecting a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), difluoromethane (R-32) and fluoromethane (R-41) to a reaction including thermal decomposition to obtain the reaction gas,

[0058] (2) The water vapor content in the raw material gas is 1 volume % or less.

[0059] The raw material gas is a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), difluoromethane (R-32) and fluoromethane (R-41), which can synthesize a reaction gas containing R-1132 (E) as the target compound by a reaction including thermal decomposition (hereinafter also referred to as "reaction"). Among these fluoromethanes, R-32 is preferred from the viewpoint of suppressing the generation of by-products.

[0060] Among them, in embodiment 1, as the raw material gas, a raw material gas with a water vapor content of 1% by volume or less is used. As a result, the selectivity of R-1132 (E) in the reaction gas is improved. The water vapor content in the raw material gas only needs to be 1% by volume or less, and in the best embodiment, it is preferably free of water vapor. That is to say, as the raw material gas, it can be substantially composed of the above-mentioned fluoromethanes (selected from at least one of R-22, R-32 and R-41). In addition, in embodiment 1, from the perspective of the generation of by-products, the water vapor content in the raw material gas is also preferably less, and the upper limit of the water vapor content in the raw material gas is preferably 1% by volume, more preferably 0.5% by volume, and particularly preferably 0.1% by volume. Further, in embodiment 1, the lower limit of the water vapor content in the raw material gas is preferably 0% by volume, more preferably 0.1% by volume, and particularly preferably 1% by volume. Among them, in embodiment 1, when the water vapor content in the raw material gas is 0% by volume, although the dehydration treatment is difficult and the process management is complicated, it is not a problem.

[0061] In Embodiment 1, the water vapor content of the raw material gas is 1% by volume or less, and the raw material conversion rate is reduced, but both the selectivity and yield of R-1132(E) in the reaction gas can be improved compared with the existing method. In particular, the selectivity of R-1132(E) in the reaction gas can be as high as 15 mol% or more, which is a great advantage over the existing technology.

[0062] In Embodiment 1, it is preferred that the raw material gas contains R-32, and the water vapor content in the raw material gas is 1 volume % or less. In Embodiment 1, it is more preferred that the raw material gas contains R-32, and the water vapor content in the raw material gas is 0 volume % or more and 0.5 volume % or less. In Embodiment 1, it is particularly preferred that the raw material gas contains R-32, and the water vapor content in the raw material gas is 0 volume % or more and 0.1 volume % or less.

[0063] In Embodiment 1, the raw material gas may be supplied directly to the reactor only with fluoromethane or diluted with an inert gas such as nitrogen, argon, carbon dioxide, etc., and then supplied to the reactor. In addition, the raw material gas may be preheated to any temperature before being supplied as required.

[0064] The temperature (reaction temperature) at which the raw material gas is supplied to the above-mentioned reaction is preferably 750 to 1050°C, more preferably 800 to 950°C, and further preferably 850 to 900°C. By setting the reaction temperature within such a range, both the conversion rate of fluoromethanes and the selectivity of R-1132(E) can be improved. In addition, in particular, by making the reaction temperature above 850°C, the reaction gas is likely to contain trifluoroethylene (R-1123) in addition to R-1132(E). In this case, there is an advantage that R-1132(E) and R-1123, which are promising refrigerants, can be produced simultaneously. When such simultaneous production is the purpose, the reaction temperature is preferably set to 850 to 1050°C, more preferably 850 to 950°C, and particularly preferably 850 to 900°C.

[0065] As a heating method for supplying the raw material gas to the above reaction, a known method can be used. Examples include: a method of heating the reactor (reaction container) in an electric furnace, a method of heating the reactor using an electric heater or a jacket through which a heat medium flows, a method of heating the reactor using microwaves, a method of heating the above inert gas as a diluent gas and then mixing it with fluoromethane, etc. Among them, the raw material gas can also be preheated to an arbitrary temperature before supplying, as required.

[0066] The pressure (reaction pressure) of the raw material gas supplied to the above reaction is preferably 0 to 0.6 MPaG, more preferably 0 to 0.3 MPaG. By setting the pressure within such a range, both the conversion rate of fluoromethanes and the selectivity of R-1132(E) can be improved. The lower limit of the pressure can be set to, for example, 0.01 MPaG, 0.1 MPaG, etc.

[0067] The time (residence time) for supplying the raw material gas to the above reaction varies depending on the type of fluoromethane, reaction temperature, reaction pressure, etc., and is preferably 0.2 to 3 seconds, and more preferably 0.5 to 1 second. When the residence time is made to be above the lower limit of the above range, the thermal decomposition of fluoromethanes can be promoted, and R-1132 (E) can be obtained efficiently. By becoming below the upper limit of the above range, side reactions can be suppressed, and the thermal decomposition of fluoromethanes can be promoted, and the productivity is good. In addition, for the purpose of simultaneously producing R-1132 (E) and R-1123, when the reaction temperature is set to 850°C to 1050°C, the residence time is preferably set to 0.1 to 0.5 seconds.

[0068] The form of the reactor for supplying the raw gas to the above reaction is not particularly limited, and a well-known reactor that can withstand the above reaction temperature and reaction pressure can be widely used. For example, a tubular flow-type reactor filled with a catalyst can be used. As a catalyst, for example, metal oxide catalysts such as Al2O3 and CoO2; metal catalysts such as Fe, Zn, and Co; oxides such as Pd / C, Pd / TiO2 or catalysts carrying metal particles in carbon carriers. In addition, when the reaction is carried out in the absence of a catalyst, an adiabatic reactor with an empty tower, an adiabatic reactor filled with porous or non-porous metals or media for improving the mixing state of the raw gas, etc. can also be used. In addition, a heat medium can be used to remove heat and / or a multi-tubular reactor can be used after the temperature distribution in the reactor is uniform.

[0069] When an empty tower reactor is used, in a method of improving heat transfer efficiency by using a reactor with a small inner diameter, for example, regarding the relationship between the flow rate of the raw material gas and the inner diameter of the reactor, a large linear velocity and a large heat transfer area are preferred.

[0070] As the reactor, specifically, it is preferable to use a reactor made of a material resistant to corrosion, such as HASTALLOY, INCONEL, MONEL, INCOLOY, stainless steel (SUS316, etc.), etc. The details are described in Embodiment 2. In the above-mentioned reactor, when a metal reaction container having an iron content of 10% by mass or less, such as HASTALLOY or INCONEL, is used, coking on the inner wall of the reactor can be suppressed more than in the conventional method.

[0071] The reaction gas containing R-1132(E) obtained in Embodiment 1 can be appropriately subjected to a purification step to improve the purity of R-1132(E) and then be taken out. As the purification method, a known purification method such as distillation can be used.

[0072] The reaction gas containing R-1132(E) obtained in Embodiment 1 more preferably further contains R-1123 and R-32. That is, in the present invention, the reaction gas obtained in Embodiment 1 more preferably contains R-1132(E), R-1123 and R-32.

[0073] (Implementation Method 2)

[0074] Embodiment 2 is a method for producing a reaction gas containing R-1132(E), characterized in that:

[0075] (1) a step of subjecting a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), chlorofluoromethane (R-31), difluoromethane (R-32) and fluoromethane (R-41) to a reaction including thermal decomposition to obtain the reaction gas,

[0076] (2) The reaction is carried out using a metal reaction vessel having an iron content of 10% by mass or less.

[0077] The raw material gas is a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), chlorofluoromethane (R-31), difluoromethane (R-32) and fluoromethane (R-41), which can synthesize a reaction gas containing R-1132 (E) as the target compound by a reaction including thermal decomposition. Among these fluoromethanes, R-32 is preferred from the viewpoint of suppressing the generation of by-products.

[0078] In Embodiment 2, as for the raw material gas, only fluoromethane can be directly supplied to the reactor, or it can be diluted with an inert gas such as nitrogen, argon, carbon dioxide, etc. before being supplied to the reactor. In addition, the raw material gas can be preheated to any temperature before being supplied as needed.

[0079] In embodiment 2, the above reaction is carried out using a metal reaction container having an iron content of 10% by mass or less. As such a metal reaction container, for example, HASTALLOY, INCOLLOY, INCONEL, MONEL, etc. can be cited. In embodiment 2, as a metal reaction container having an iron content of 10% by mass or less, INCONEL is particularly preferably used. In embodiment 2, by using a metal reaction container having an iron content of 10% by mass or less to carry out the above reaction, coking to the inner wall of the reactor can be more suppressed compared with the existing method. In addition, compared with the existing method, the generation of CO2 due to the reaction between the inner wall of the reactor and the raw gas can be more suppressed.

[0080] The generation of CO2 can be considered to be, for example, the following reaction mode: in a region where the reaction temperature is relatively high, fluoromethanes undergo thermal decomposition to generate fluorine free radicals, which replace oxygen atoms near iron atoms contained in the metal reaction container to generate oxygen free radicals, and the oxygen free radicals react on the coked inner wall of the reactor to generate CO2. However, by using a metal reaction container with an iron content of 10% by mass or less as in Embodiment 2, the generation of CO2 exemplified in the above manner can be suppressed.

[0081] As for the form of the reactor for supplying the raw gas to the above reaction, as long as the above-mentioned provisions of the iron content are met, there is no particular limitation, and a known reactor that can withstand the reaction temperature and reaction pressure described later can be widely used. For example, a tubular flow-type reactor filled with a catalyst can be used. As a catalyst, for example, metal oxide catalysts such as Al2O3 and CoO2; metal catalysts such as Fe, Zn, and Co; catalysts carrying metal particles in oxides such as Pd / C and Pd / TiO2 or carbon carriers. In addition, when the reaction is carried out in the absence of a catalyst, an adiabatic reactor of an empty tower, an adiabatic reactor filled with porous or non-porous metal or medium for improving the mixing state of the raw gas, etc. can also be used. In addition, a heat medium can be used to remove heat and / or a multi-tubular reactor can be used after the temperature distribution in the reactor is uniform.

[0082] When an empty tower reactor is used, in a method of improving heat transfer efficiency by using a reactor with a small inner diameter, for example, regarding the relationship between the flow rate of the raw material gas and the inner diameter of the reactor, a large linear velocity and a large heat transfer area are preferred.

[0083] The temperature (reaction temperature) at which the raw material gas is supplied to the above-mentioned reaction is preferably 750 to 1050°C, more preferably 800 to 950°C, and further preferably 850 to 900°C. By setting the reaction temperature within such a range, both the conversion rate of fluoromethanes and the selectivity of R-1132(E) can be improved. In addition, in particular, by making the reaction temperature above 850°C, the reaction gas is likely to contain trifluoroethylene (R-1123) in addition to R-1132(E). In this case, there is an advantage that R-1132(E) and R-1123, which are promising refrigerants, can be produced simultaneously. When such simultaneous production is the purpose, the reaction temperature is preferably set to 850 to 1050°C, more preferably 850 to 950°C, and particularly preferably 850 to 900°C.

[0084] As a heating method for supplying the raw material gas to the above reaction, a known method can be used. Examples include: a method of heating the reactor (reaction container) in an electric furnace, a method of heating the reactor using an electric heater or a jacket through which a heat medium flows, a method of heating the reactor using microwaves, a method of heating the above inert gas as a diluent gas and then mixing it with fluoromethane, etc. Among them, the raw material gas can also be preheated to an arbitrary temperature before supplying, as required.

[0085] The pressure (reaction pressure) of the raw material gas supplied to the above reaction is preferably 0 to 0.6 MPaG (gauge pressure), and more preferably 0 to 0.3 MPaG. By setting the pressure within such a range, both the conversion rate of fluoromethanes and the selectivity of R-1132(E) can be improved. The lower limit of the pressure can be set to, for example, 0.01 MPaG, 0.1 MPaG, etc.

[0086] The time (residence time) for supplying the raw material gas to the above reaction varies depending on the type of fluoromethane, reaction temperature, reaction pressure, etc., and is preferably 0.2 to 3 seconds, and more preferably 0.5 to 1 second. When the residence time is made to be above the lower limit of the above range, the thermal decomposition of fluoromethanes can be promoted, and R-1132 (E) can be obtained efficiently. By becoming below the upper limit of the above range, fluoromethanes and R-1132 (E) are not easy to coke, and the productivity is good. In addition, for the purpose of simultaneously producing R-1132 (E) and R-1123, when the reaction temperature is set to above 850°C, the residence time is preferably set to 0.1 to 0.5 seconds.

[0087] The reaction gas containing R-1132(E) obtained in Embodiment 2 can be appropriately subjected to a purification step to improve the purity of R-1132(E) and then be taken out. As the purification method, a known purification method such as distillation can be used.

[0088] (Implementation 3)

[0089] Embodiment 3 is a method for producing a reaction gas containing R-1132(E), characterized in that:

[0090] (1) a step of subjecting a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), chlorofluoromethane (R-31), difluoromethane (R-32) and fluoromethane (R-41) to a reaction including thermal decomposition to obtain the reaction gas,

[0091] (2) The content of at least one inert gas selected from nitrogen, argon, hydrofluorocarbons and carbon dioxide in the raw material gas is 10 to 90% by volume.

[0092] The raw material gas is a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), chlorofluoromethane (R-31), difluoromethane (R-32) and fluoromethane (R-41), which can synthesize a reaction gas containing R-1132 (E) as the target compound by a reaction including thermal decomposition. Among these fluoromethanes, R-32 is preferred from the viewpoints of easy separation of by-products, reduction of the number of steps such as distillation, and suppression of the generation of by-products.

[0093] Among them, in Embodiment 3, as a raw material gas, a raw material gas containing 10 to 90% by volume of at least one inert gas selected from nitrogen, argon, hydrofluorocarbons and carbon dioxide is used. That is, in Embodiment 3, by using the inert gas as a diluent gas, fluoromethane (selected from at least one of R-22, R-31, R-32 and R-41) is diluted and used. As the above-mentioned hydrofluorocarbon, for example, at least one selected from 1,1,2,2-tetrafluoroethane (R134), 1,1,1,2-tetrafluoroethane (R134a) and pentafluoroethane (R125) can be cited.

[0094] In Embodiment 3, by making the content of the above-mentioned inert gas in the raw material gas 10 to 90% by volume, both the conversion rate of fluoromethanes and the selectivity of R-1132(E) can be improved compared with the existing method. In particular, the selectivity of R-1132(E) in the reaction gas can be as high as 15 mol% or more, which is a great advantage over the existing technology.

[0095] In Embodiment 3, the content of the inert gas in the raw material gas is preferably 30 to 90% by volume, more preferably 50 to 89% by volume, and particularly preferably 70 to 88% by volume.

[0096] In Embodiment 3, the raw material gas may be preheated to an arbitrary temperature before being supplied, as necessary.

[0097] The temperature (reaction temperature) at which the raw material gas is supplied to the above-mentioned reaction is preferably 750 to 1050°C, more preferably 800 to 950°C, and further preferably 850 to 900°C. By setting the reaction temperature within such a range, both the conversion rate of fluoromethanes and the selectivity of R-1132(E) can be improved. In addition, in particular, by making the reaction temperature above 850°C, the reaction gas is likely to contain trifluoroethylene (R-1123) in addition to R-1132(E). In this case, there is an advantage that R-1132(E) and R-1123, which are promising refrigerants, can be produced simultaneously. When such simultaneous production is the purpose, the reaction temperature is preferably set to 850 to 1050°C, more preferably 850 to 950°C, and particularly preferably 850 to 900°C.

[0098] As a method for heating the raw material gas for the above reaction, a known method can be used, including: a method of heating the reactor (reaction container) in an electric furnace, a method of heating the reactor using an electric heater or a jacket through which a heat medium flows, a method of heating the reactor using microwaves, a method of heating the above inert gas as a diluent gas and then mixing it with fluoromethane, etc.

[0099] The pressure (reaction pressure) of the raw material gas supplied to the above reaction is preferably 0 to 0.6 MPaG, more preferably 0 to 0.3 MPaG. By setting the pressure within such a range, both the conversion rate of fluoromethanes and the selectivity of R-1132(E) can be improved. The lower limit of the pressure can be set to, for example, 0.01 MPaG, 0.1 MPaG, etc.

[0100] The time (residence time) for supplying the raw material gas to the above reaction varies depending on the type of fluoromethane, reaction temperature, reaction pressure, etc., and is preferably 0.2 to 3 seconds, and more preferably 0.5 to 1 second. When the residence time is made to be above the lower limit of the above range, the thermal decomposition of fluoromethanes can be promoted, and R-1132 (E) can be obtained efficiently. By becoming below the upper limit of the above range, side reactions can be suppressed, and the thermal decomposition of fluoromethanes can be promoted, and the productivity is good. In addition, for the purpose of simultaneously producing R-1132 (E) and R-1123, when the reaction temperature is set to 850°C to 1050°C, the residence time is preferably set to 0.1 to 0.5 seconds.

[0101] The form of the reactor for supplying the raw gas to the above reaction is not particularly limited, and a well-known reactor that can withstand the above reaction temperature and reaction pressure can be widely used. For example, a tubular flow-type reactor filled with a catalyst can be used. As a catalyst, for example, metal oxide catalysts such as Al2O3 and CoO2; metal catalysts such as Fe, Zn, and Co; oxides such as Pd / C, Pd / TiO2 or catalysts carrying metal particles in carbon carriers. In addition, when the reaction is carried out in the absence of a catalyst, an adiabatic reactor with an empty tower, an adiabatic reactor filled with porous or non-porous metals or media for improving the mixing state of the raw gas, etc. can also be used. In addition, a heat medium can be used to remove heat and / or a multi-tubular reactor can be used after the temperature distribution in the reactor is uniform.

[0102] When an empty tower reactor is used, in a method of improving heat transfer efficiency by using a reactor with a small inner diameter, for example, regarding the relationship between the flow rate of the raw material gas and the inner diameter of the reactor, a large linear velocity and a large heat transfer area are preferred.

[0103] As the reactor, specifically, it is preferable to use a reactor made of a material resistant to corrosion, such as HASTALLOY, INCONEL, MONEL, INCOLOY, stainless steel (SUS316, etc.), etc. As described above, when a metal reaction container such as HASTALLOY or INCONEL having an iron content of 10% by mass or less is used in the above-mentioned reactor, coking on the inner wall of the reactor can be suppressed more than in the conventional method.

[0104] The reaction gas containing R-1132(E) obtained in Embodiment 3 can be appropriately subjected to a purification step to improve the purity of R-1132(E) and then be taken out. As the purification method, a known purification method such as distillation can be used.

[0105] (Implementation 4)

[0106] Embodiment 4 is a method for producing a reaction gas containing R-1132(E), characterized in that:

[0107] (1) a step of subjecting a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), chlorofluoromethane (R-31), difluoromethane (R-32) and fluoromethane (R-41) to a reaction including thermal decomposition to obtain the above-mentioned reaction gas,

[0108] (2) The content of the fluoromethane in the raw material gas is 90 to 100% by volume.

[0109] The raw material gas is a raw material gas containing at least one fluoromethane selected from chlorodifluoromethane (R-22), chlorofluoromethane (R-31), difluoromethane (R-32) and fluoromethane (R-41), which can synthesize a reaction gas containing R-1132 (E) as the target compound by a reaction including thermal decomposition. Among these fluoromethanes, R-32 is particularly preferred from the viewpoints of easy separation of by-products, reduction of the number of steps such as distillation, and suppression of the generation of by-products.

[0110] In Embodiment 4, the content of fluoromethanes (at least one of these R-22, R-31, R-32 and R-41) in the raw material gas is 90 to 100% by volume. The content of the fluoromethanes in the raw material gas is preferably 95 to 100% by volume, more preferably 99 to 100% by volume, further preferably 99.5 to 100% by volume, and particularly preferably 99.9 to 100% by volume. When the content of the fluoromethanes in the raw material gas is within such a range, the conversion rate of the fluoromethanes and the selectivity of R-1132 (E) can be increased, and the selectivity of carbon in the reaction gas can be suppressed.

[0111] In Embodiment 4, the raw material gas preferably contains 100 volume % R-32. This can improve both the conversion rate of R-32 and the selectivity of R-1132(E) compared to conventional methods, and can suppress the selectivity of carbon in the reaction gas.

[0112] In Embodiment 4, as the raw material gas, it is preferred to use a raw material gas containing less than 10% by volume of at least one inert gas selected from nitrogen, argon, hydrofluorocarbons, and carbon dioxide. That is, in Embodiment 4, it is preferred to use the fluoromethane after dilution by using the inert gas as a diluent gas. As the above-mentioned hydrofluorocarbon, for example, at least one selected from 1,1,2,2-tetrafluoroethane (R134), 1,1,1,2-tetrafluoroethane (R134a), and pentafluoroethane (R125) can be cited.

[0113] In Embodiment 4, the content of the inert gas in the raw material gas is preferably less than 10% by volume. This can increase the conversion rate of fluoromethanes and the selectivity of R-1132(E), and can suppress the selectivity of carbon in the reaction gas.

[0114] In Embodiment 4, the content of the above-mentioned inert gas in the raw gas is more preferably less than 5 volume %, further preferably less than 1 volume %, further preferably less than 0.5 volume %, and particularly preferably less than 0.1 volume %. When the content of the above-mentioned inert gas in the raw gas is within such a range, the conversion rate of fluoromethanes and the selectivity of R-1132 (E) can be further improved, and the selectivity of carbon in the reaction gas can be further suppressed. In addition, when the content of the above-mentioned inert gas in the raw gas is within such a range, after the reaction including thermal decomposition, R-1132 (E) and the above-mentioned inert gas are easily separated, thereby reducing the manufacturing cost of the equipment. In Embodiment 4, the content of the above-mentioned inert gas in the raw gas is most preferably 0 volume %.

[0115] In the fourth embodiment, the raw material gas may be preheated to an arbitrary temperature before being supplied, as necessary.

[0116] The temperature (reaction temperature) at which the raw gas is supplied to the above reaction is preferably 750 to 1050°C, more preferably 800 to 900°C. By setting the reaction temperature within such a range, both the conversion rate of fluoromethanes and the selectivity of R-1132 (E) can be improved. In addition, in particular, by making the reaction temperature above 800°C, the reaction gas is likely to contain trifluoroethylene (R-1123) in addition to R-1132 (E). In this case, there is an advantage that R-1132 (E) and R-1123, which are promising refrigerants, can be produced simultaneously. When such simultaneous production is the purpose, the reaction temperature is preferably set to 800 to 900°C.

[0117] As a method for heating the raw material gas for the above reaction, a known method can be used, including: a method of heating the reactor (reaction container) in an electric furnace, a method of heating the reactor using an electric heater or a jacket through which a heat medium flows, a method of heating the reactor using microwaves, a method of heating the above inert gas as a diluent gas and then mixing it with fluoromethane, etc.

[0118] The pressure (reaction pressure) of the raw material gas supplied to the above reaction is preferably 0 to 0.6 MPaG, more preferably 0 to 0.3 MPaG. By setting the pressure within such a range, both the conversion rate of fluoromethanes and the selectivity of R-1132(E) can be improved. The lower limit of the pressure can be set to, for example, 0.01 MPaG, 0.1 MPaG, etc.

[0119] The time (residence time) for supplying the raw gas to the above reaction varies depending on the type of fluoromethane, reaction temperature, reaction pressure, etc., and is preferably 0.03 to 5 seconds, and more preferably 0.04 to 4 seconds. When the residence time is made to be above the lower limit of the above range, the thermal decomposition of fluoromethanes can be promoted, and R-1132 (E) can be obtained efficiently. By becoming below the upper limit of the above range, side reactions can be suppressed, and the thermal decomposition of fluoromethanes can be promoted, and the productivity is good. In addition, for the purpose of simultaneously producing R-1132 (E) and R-1123, when the reaction temperature is set to 750°C to 1050°C, the residence time is preferably set to 0.04 to 4 seconds.

[0120] The form of the reactor for supplying the raw gas to the above reaction is not particularly limited, and a well-known reactor that can withstand the above reaction temperature and reaction pressure can be widely used. For example, a tubular flow-type reactor filled with a catalyst can be used. As a catalyst, for example, metal oxide catalysts such as Al2O3 and CoO2; metal catalysts such as Fe, Zn, and Co; oxides such as Pd / C, Pd / TiO2 or catalysts carrying metal particles in carbon carriers. In addition, when the reaction is carried out in the absence of a catalyst, an adiabatic reactor with an empty tower, an adiabatic reactor filled with porous or non-porous metals or media for improving the mixing state of the raw gas, etc. can also be used. In addition, a heat medium can be used to remove heat and / or a multi-tubular reactor can be used after the temperature distribution in the reactor is uniform.

[0121] When an empty tower reactor is used, in a method of improving heat transfer efficiency by using a reactor with a small inner diameter, for example, regarding the relationship between the flow rate of the raw material gas and the inner diameter of the reactor, a large linear velocity and a large heat transfer area are preferred.

[0122] As the reactor, specifically, it is preferable to use a reactor made of a material resistant to corrosion, such as HASTALLOY, INCONEL, MONEL, INCOLLOY, stainless steel (SUS316, etc.). As described above, in the above reactor, when a metal reaction container having an iron content of 10% by mass or less such as HASTALLOY or INCONEL is used, coking on the inner wall of the reactor can be suppressed more than in the prior art. In Embodiment 4, INCONEL is particularly preferably used as a metal reaction container having an iron content of 10% by mass or less.

[0123] The reaction gas containing R-1132(E) obtained in Embodiment 4 can be appropriately subjected to a purification step to improve the purity of R-1132(E) and then be taken out. As the purification method, a known purification method such as distillation can be used.

[0124] 2. Composition

[0125] The composition of the present invention contains (E)-1,2-difluoroethylene (R-1132(E)) and at least one compound selected from 3,3,3-trifluoropropyne (TFP), propyne and 1,1,1,2-tetrafluoroethane (R-134a).

[0126] The composition of the present invention preferably contains R-1132(E) obtained by the production method described in Embodiments 1 to 4 above and at least one compound selected from TFP, propyne and R-134a.

[0127] The composition of the present invention more preferably contains R-1132(E) obtained by the production method described in Embodiments 1 to 4 above and at least one compound selected from TFP and R-134a.

[0128] The composition of the present invention particularly preferably contains R-1132(E), TFP, and R-134a obtained by the production method described in Embodiments 1 to 4 above.

[0129] In the composition of the present invention, the content of TFP is preferably 1% by mass or less based on the total amount of the composition.

[0130] In the composition of the present invention, the content of TFP is 0.3% by mass or less, and the content of R-134a is more preferably 0.2% by mass or less, based on the total amount of the composition.

[0131] As mentioned above, although embodiment of this invention was demonstrated, this invention is not limited to these examples at all, It is a matter of course that this invention can be implemented in various forms within the range which does not deviate from the summary of this invention.

[0132] Example

[0133] Hereinafter, Embodiments 1 to 4 of the production method of the present invention will be described in more detail based on Examples. However, the production method of the present invention is not limited to the scope of the Examples.

[0134] In the following Examples 1 to 9, the composition of each component was analyzed by gas chromatography (MS detector).

[0135] Examples 1 to 3 (Implementation 1: Effect of water vapor content on reaction performance)

[0136] Under the reaction conditions shown in Table 1, a raw material gas containing only R-32 as a fluoromethane was subjected to a reaction including thermal decomposition to obtain a reaction gas containing R-1132(E). The reaction performance of Example 2 showed that the yield of R-1132(E) was higher than that of Examples 1 and 3.

[0137] [Table 1]

[0138]

[0139] Examples 4 and 5 (Implementation 2: Effect of Reactor Material on Reaction Performance)

[0140] Under the reaction conditions shown in Table 2, a raw material gas containing only R-32 as a fluoromethane is subjected to a reaction including thermal decomposition, thereby obtaining a reaction gas containing R-1132 (E). According to the reaction performance of Example 4, the conversion rate of R-32 and the yield of R-1132 (E) are both high compared with the reaction performance of Example 5. In addition, according to the reaction performance of Example 4, the amount of carbon attached to the inner wall of the reactor is small (coking is suppressed) compared with the reaction performance of Example 5, and no CO2 is generated.

[0141] [Table 2]

[0142]

[0143] Examples 6 and 7 (Implementation 3: Differences between R-32 and R-31 with 90% by volume of inert gas and reaction performance Impact of

[0144] Under the reaction conditions shown in Table 3, a raw material gas containing fluoromethanes (R-32, R-31) is supplied to a reaction including thermal decomposition, thereby obtaining a reaction gas containing R-1132 (E). Under the same conditions in which the content of the inert gas (diluent gas) in the raw material gas is set to 90% by volume, it can be seen from the reaction performance of Example 6 using a raw material gas containing only R-32 as a fluoromethane that the yield of R-1132 (E) is higher than the reaction performance of Example 7 using a raw material gas containing only R-31 as a fluoromethane. It can be seen that as the fluoromethane contained in the raw material gas, R-32 is preferred over R-31.

[0145] [Table 3]

[0146]

[0147] Examples 6, 8 and 9 (Implementation 3: Effect of the difference in reaction temperature of 90% by volume of inert gas on reaction performance Influence)

[0148] Under the reaction conditions shown in Table 4, a raw material gas containing only R-32 as a fluoromethane is supplied to a reaction including thermal decomposition, thereby obtaining a reaction gas containing R-1132 (E). The reaction temperature of Example 6 is 850°C, and the reaction temperatures of Example 8 and Example 9 are 950°C and 1050°C, respectively. The comparison is made under the same conditions except that. It can be seen that as the reaction temperature increases, the conversion rate of R-32 and the yield of R-1132 (E) both increase. It can also be seen that as the reaction temperature increases, the ratio of trifluoroethylene (R-1123) generated together with R-1132 (E) increases. It can be seen that when the purpose is simultaneous production, it is advantageous to set the reaction temperature to a higher level.

[0149] [Table 4]

[0150]

[0151] In the following Examples 10 to 17, the composition of each component was analyzed by gas chromatography (FID detector).

[0152] Examples 10 to 17 (Implementation 4: Effect of the Content of Fluoromethanes in the Raw Gas on Reaction Performance)

[0153] Under the reaction conditions shown in Table 5, a raw material gas containing only R-32 as a fluoromethane is subjected to a reaction including thermal decomposition, thereby obtaining a reaction gas containing R-1132 (E). Among them, "others" in Table 5 can include fluorinated hydrocarbons having 3 to 6 carbon atoms, etc. As an example of a fluorinated hydrocarbon having 3 to 6 carbon atoms, for example, 1,1,2-trifluoro-1,3-butadiene and 1,3,5-trifluorobenzene can be listed.

[0154] According to the reaction performance of Examples 12 to 17, the yield of R-1132 (E) is higher than that of Example 11. In addition, according to the reaction performance of Examples 13 and 17 and the result of Example 10, the yield of R-1132 (E) in Example 10 is about the same as that in Examples 13 and 17, but in Examples 13 and 17, the selectivity of carbon (C) in the reaction gas is greatly reduced compared with that in Example 10. Therefore, it can be seen that in order to obtain the effect of reducing the selectivity of carbon in the reaction gas and the effect of increasing the yield of R-1132 (E), it is particularly advantageous not to dilute the raw material gas with nitrogen (nitrogen content in the raw material gas = 0 volume %). According to the above results, it can be confirmed that if the separation cost of the dilution gas in the subsequent process is taken into account, it is advantageous that the content of R-32 in the raw material gas is 90 to 100 volume %, and it is particularly advantageous that the content of R-32 in the raw material gas is 100 volume %.

[0155] [Table 5]

[0156]

[0157] Example 18 (Confirmation of Characteristics as a Refrigerant)

[0158] The global warming potential (GWP: Global Warming Potential) of the mixed refrigerants shown in Example 18 and Reference Example 1 (R410A) was evaluated based on the values ​​of the 4th report of IPCC (Intergovernmental Panel on Climate Change).

[0159] The coefficient of performance (COP) of these mixed refrigerants was determined by performing theoretical calculation of the refrigeration cycle of the mixed refrigerants under the following conditions using Refprop10.0 (manufactured by National Institute of Science and Technology (NIST)).

[0160] Evaporation temperature 10℃

[0161] Condensation temperature 45℃

[0162] Overheat temperature 5K

[0163] Supercooling temperature 5K

[0164] Compressor efficiency 70%

[0165] The coefficient of performance (COP) is calculated using the following formula.

[0166] COP = (cooling capacity or heating capacity) / power consumption

[0167] [Table 6]

[0168]

[0169] This confirms that the mixed refrigerant of Example 18 has a COP equivalent to that of R410A and has characteristics of sufficiently low GWP.

Claims

1. A method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)), the method comprising: (1) a step of subjecting a raw material gas containing fluoromethanes consisting only of difluoromethane (R-32) to a reaction including thermal decomposition to obtain the reaction gas; (2) the water vapor content in the raw gas is less than 1% by volume, (3) The reaction is carried out at a temperature of 750°C to 1050°C and a residence time of 0.2 to 3 seconds.

2. A method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)), the method comprising: (1) a step of subjecting a raw material gas containing fluoromethanes consisting only of difluoromethane (R-32) to a reaction including thermal decomposition to obtain the reaction gas; (2) the reaction is carried out using a metal reaction vessel having an iron content of 10% by mass or less, wherein the metal reaction vessel having an iron content of 10% by mass or less is an Inconel reaction vessel, (3) The reaction is carried out at a temperature of 750°C to 1050°C and a residence time of 0.2 to 3 seconds.

3. A method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)), the method comprising: (1) a step of subjecting a raw material gas containing fluoromethanes consisting only of difluoromethane (R-32) to a reaction including thermal decomposition to obtain the reaction gas; (2) the content of at least one inert gas selected from nitrogen, argon, hydrofluorocarbon and carbon dioxide in the raw material gas is 10 to 90% by volume, and the hydrofluorocarbon is at least one selected from 1,1,2,2-tetrafluoroethane (R134), 1,1,1,2-tetrafluoroethane (R134a) and pentafluoroethane (R125), (3) The reaction is carried out at a temperature of 800°C to 1050°C and a residence time of 0.2 to 3 seconds.

4. A method for producing a reaction gas containing (E)-1,2-difluoroethylene (R-1132(E)), the method comprising: (1) a step of subjecting a raw material gas containing fluoromethanes consisting only of difluoromethane (R-32) to a reaction including thermal decomposition to obtain the reaction gas; (2) The content of the fluoromethane in the raw material gas is 90 to 100% by volume. (3) The reaction is carried out at a temperature of 750°C to 1050°C.

5. The manufacturing method according to any one of claims 1 to 4, characterized in that: The reaction is carried out at 0-0.6 MPaG.

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