Method for producing difluoroethylene

Abstract

The present invention provides a method for efficiently obtaining HFO-1132(E) and / or HFO-1132(Z). The method for producing HFO-1132(E) and / or HFO-1132(Z) comprises the steps of supplying a composition containing HFO-1132(E) and / or HFO-1132(Z) to a reactor and performing an isomerization reaction between HFO-1132(E) and HFO-1132(Z).

Description

Technical Field

[0001] The present invention relates to a method for producing difluoroethylene. Background Art

[0002] Non-Patent Document 1 discloses a method of isomerizing HFO-1132(E) by contacting HFO-1132(Z) in a gas phase using iodine as a catalyst.

[0003] Prior art literature

[0004] Non-patent literature

[0005] Non-patent document 1: Journal of the American Chemical Society, 1961, vol. 83, 3047. Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] The technical problem to be solved by the present invention is to provide a method for effectively obtaining HFO-1132(E) and / or HFO-1132(Z).

[0008] Technical solutions for solving technical problems

[0009] The present invention includes, for example, the inventions described in the following items.

[0010] Item 1. A method for producing HFO-1132(E) and / or HFO-1132(Z), comprising: supplying a composition containing trans-1,2-difluoroethylene (HFO-1132(E)) and / or cis-1,2-difluoroethylene (HFO-1132(Z)) to a reactor, and performing an isomerization reaction between HFO-1132(E) and HFO-1132(Z) at a reaction temperature of 600° C. or higher.

[0011] Item 2. The production method according to Item 1 above, wherein the isomerization reaction is performed in the absence of a catalyst.

[0012] Item 3. A method for producing HFO-1132(E) and / or HFO-1132(Z), comprising: supplying a composition containing trans-1,2-difluoroethylene (HFO-1132(E)) and / or cis-1,2-difluoroethylene (HFO-1132(Z)) to a reactor, and performing an isomerization reaction between HFO-1132(E) and HFO-1132(Z) at a reaction temperature of 200° C. or higher in the absence of a catalyst.

[0013] Item 4. The production method according to any one of Items 1 to 3, wherein in the isomerization reaction, HFO-1132(Z) or a composition containing HFO-1132(E) and HFO-1132(Z) is supplied to a reactor to produce HFO-1132(E).

[0014] Item 5. The production method according to any one of Items 1 to 3, wherein in the isomerization reaction, HFO-1132(E) or a composition containing HFO-1132(E) and HFO-1132(Z) is supplied to a reactor to produce HFO-1132(Z).

[0015] Item 6. The production method according to any one of Items 1 to 5, comprising a step of separating HFO-1132(E) and HFO-1132(Z) by distillation after the isomerization reaction.

[0016] Item 7. The production method according to Item 6 above, comprising recycling HFO-1132(Z) to the isomerization reaction step after the separation step, and then supplying HFO-1132(Z) or a composition containing HFO-1132(E) and HFO-1132(Z) to the reactor to produce HFO-1132(E).

[0017] Item 8. The production method according to Item 6 above, comprising recycling HFO-1132(E) to the isomerization reaction step after the separation step, and then supplying HFO-1132(E) or a composition containing HFO-1132(E) and HFO-1132(Z) to the reactor to produce HFO-1132(Z).

[0018] Effects of the Invention

[0019] According to the present invention, HFO-1132(E) and / or HFO-1132(Z) can be obtained efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of a production facility for efficiently producing HFO-1132(E) from HFO-1132(Z) in the method for producing HFO-1132(E) and / or HFO-1132(Z) of the present invention.

[0021] Figure 2 This is a schematic diagram of a production facility for efficiently producing HFO-1132(Z) from HFO-1132(E) in the method for producing HFO-1132(E) and / or HFO-1132(Z) of the present invention.

[0022] Figure 3This is a graph showing the relationship between the reaction temperature and the equilibrium constant of HFO-1132(E) and HFO-1132(Z) in the method for producing HFO-1132(E) and / or HFO-1132(Z) of the present invention. DETAILED DESCRIPTION

[0023] Currently, in the production of HFO-1132(E) and / or HFO-1132(Z), the boiling point of HFO-1132(E) (boiling point: -52°C) is close to that of difluoromethane (HFC-32) (boiling point: -51.7°C), and the boiling point of HFO-1132(Z) (boiling point: -26°C) is close to that of 1,1,2,2-tetrafluoroethane (HFC-134) (boiling point: -20.0°C). In the method of separation by distillation utilizing the difference in boiling points, a large amount of energy is required.

[0024] Therefore, the technical problem to be solved by the present invention is to provide a technical solution to the above technical problem. Specifically, the technical problem to be solved by the present invention is to provide the following method: in the method for producing HFO-1132(E) and / or HFO-1132(Z), a thermal reaction is used to carry out an isomerization reaction between HFO-1132(E) and HFO-1132(Z), and a boiling point difference of 20°C or more between the two is used to combine distillation, thereby reducing the total energy consumption required for separation of the two, and more effectively obtaining HFO-1132(E) and / or HFO-1132(Z).

[0025] In order to solve the above technical problems, the inventors of the present invention have conducted intensive research and found that when a composition containing HFO-1132(E) and / or HFO-1132(Z) is supplied to a reactor and an isomerization reaction between HFO-1132(E) and HFO-1132(Z) is carried out, isomerization can be carried out (a) at a reaction temperature of 600°C or more, or (b) at a reaction temperature of 200°C or more in the absence of a catalyst. It was also found that the above technical problems can be solved by combining the step of carrying out the isomerization reaction with the step of separating the desired isomers. The present invention is an invention completed by further research based on these insights, and includes the following aspects.

[0026] 1. Isomerization reaction

[0027] The production method of the present invention is a method for producing HFO-1132(E) and / or HFO-1132(Z) by supplying a composition containing HFO-1132(E) and / or HFO-1132(Z) to a reactor and performing an isomerization reaction between HFO-1132(E) and HFO-1132(Z), wherein the reaction temperature is 600° C. or higher. Figure 1 and2 ).

[0028] The production method of the present invention is also a method for producing HFO-1132(E) and / or HFO-1132(Z) by supplying a composition containing HFO-1132(E) and / or HFO-1132(Z) to a reactor and performing an isomerization reaction between HFO-1132(E) and HFO-1132(Z), in the absence of a catalyst, at a reaction temperature of 200° C. or higher. Figure 1 and 2 ).

[0029] In the production method of the present invention, HFO-1132(Z) or a composition containing HFO-1132(E) and HFO-1132(Z) is preferably supplied to a reactor in the isomerization reaction to produce HFO-1132(E).

[0030] In the production method of the present invention, HFO-1132(E) or a composition containing HFO-1132(E) and HFO-1132(Z) is preferably supplied to a reactor in the isomerization reaction to produce HFO-1132(Z).

[0031] In the production method of the present invention, an isomerization reaction between HFO-1132(E) and HFO-1132(Z) is carried out. The isomerization reaction follows the following reaction formula. The E-isomer is less stable than the Z-isomer in terms of thermodynamics, so the equilibrium tends to the Z-isomer side.

[0032]

[0033] In the production method of the present invention, by subjecting the isomerization reaction to a change in the content ratio of HFO-1132(E) or HFO-1132(Z), a composition can be obtained. In the production method of the present invention, by utilizing the equilibrium relationship of the isomerization reaction between HFO-1132(E) and HFO-1132(Z), a composition can be obtained in which the content ratio of any compound is further increased.

[0034] Composition containing HFO-1132(E) and / or HFO-1132(Z)

[0035] In the production method of the present invention, the composition containing HFO-1132(E) and / or HFO-1132(Z) used as a raw material for isomerization may contain other components. The other components are not particularly limited as long as they do not significantly inhibit the isomerization reaction, and can be selected from a wide range.

[0036] Examples of other components include impurities mixed in during the process of obtaining the composition containing HFO-1132(E) and / or HFO-1132(Z), by-products generated, etc. The mixed impurities include impurities contained in the raw materials, etc.

[0037] Examples of methods for obtaining a composition containing HFO-1132(E) and / or HFO-1132(Z) used as a raw material include a method of subjecting ethane halide to a dehydrohalogenation reaction or a dehalogenation reaction.

[0038] The ethane halides used in the above-mentioned reaction are not particularly limited and can be selected from a wide range. As specific examples, the following ethane halides can be cited. These ethane halides are widely used as refrigerants, solvents, foaming agents, propellants, etc., and can be obtained in a usual manner.

[0039] 1,1,2-Trifluoroethane (CHF2CH2F: HFC-143)

[0040] 1-Bromo-1,2-difluoroethane (CHFBrCH2F)

[0041] 1-Chloro-1,2-difluoroethane (CHClFCH2F)

[0042] 1,2-Dichloro-1,2-difluoroethane (CHClFCHClF)

[0043] 1,1,2,2-Tetrafluoroethane (CHF2CHF2)

[0044] 1-Chloro-1,2,2-trifluoroethane (CHClFCHF2)

[0045] In the production method of the present invention, particularly when the production method of HFO-1132(E) is carried out, by using HFO-1132(Z) as a raw material, the isomerization reaction from HFO-1132(Z) to HFO-1132(E) can be efficiently promoted.

[0046] In the production method of the present invention, particularly when the production method of HFO-1132(Z) is carried out, by using HFO-1132(E) as a raw material, the isomerization reaction from HFO-1132(E) to HFO-1132(Z) can be efficiently promoted.

[0047] In the present invention, a gas (gas composition) containing HFO-1132(E) can be obtained by subjecting a gas containing fluoromethanes to a reaction including thermal decomposition (a synthesis reaction involving thermal decomposition of the above-mentioned fluoromethanes).

[0048] The gas containing the fluoromethanes is preferably at least one fluoromethane selected from chlorodifluoromethane (CHClF2: HCFC-22), chlorofluoromethane (CH2ClF: HCFC-31), difluoromethane (CH2F2: HFC-32) and fluoromethane (CH3F: HFC-41).

[0049] In the production method of the present invention, as a raw material for isomerization, a gas (gas composition) obtained by subjecting a gas containing at least one fluoromethane selected from HCFC-22, HCFC-31, HFC-32 and HFC-41 to a reaction including thermal decomposition (a synthesis reaction accompanied by thermal decomposition of the above-mentioned fluoromethanes) may be used. In other words, the production method of the present invention includes a method of purifying the obtained gas (gas composition) containing HFO-1132 (E) after subjecting the gas containing the above-mentioned fluoromethanes to a reaction including thermal decomposition.

[0050] Among them, the gas containing fluoromethanes is preferably HFC-32 from the viewpoint of reducing the number of steps such as separation and fractionation of by-products and suppressing the generation of hydrocarbon-based by-products.

[0051] The gas containing the above-mentioned fluoromethanes preferably has a water vapor content of 1% by volume or less. The gas containing the above-mentioned fluoromethanes uses a gas having a water vapor content of 1% by volume or less, thereby improving the selectivity of R1132(E) in the obtained gas containing HFO-1132(E). The gas containing the above-mentioned fluoromethanes preferably does not contain water vapor, and more preferably consists essentially only of the above-mentioned fluoromethanes.

[0052] In the present specification, when the target compound is HFO-1132(E), the "conversion rate" refers to the ratio (mol %) of the total molar amount of compounds other than fluoromethanes contained in the gas flowing out from the reactor outlet (= gas after the synthesis reaction accompanied by the above-mentioned thermal decomposition) to the molar amount of fluoromethanes supplied to the reactor.

[0053] In addition, when the target compound is HFO-1132(E), the above-mentioned "selectivity" refers to the ratio (mol %) of the molar amount of the target compound (HFO-1132(E)) contained in the gas (= gas after the synthesis reaction accompanied by the above-mentioned thermal decomposition) flowing out from the reactor outlet to the total molar amount of compounds other than fluoromethanes contained in the outflowing gas.

[0054] The gas containing the fluoromethanes may be diluted with an inert gas as a diluent gas. The gas containing the fluoromethanes may contain at least one inert gas selected from nitrogen, argon, hydrofluorocarbons and carbon dioxide in an amount of 10% to 90% by volume in order to further improve the conversion rate of the fluoromethanes and the selectivity of HFO-1132(E).

[0055] Examples of the hydrofluorocarbon include at least one selected from 1,1,2,2-tetrafluoroethane (R134), 1,1,1,2-tetrafluoroethane (R134a), and pentafluoroethane (R125).

[0056] The heating method for the reaction including thermal decomposition can be a known method. From the perspective of improving both the conversion rate of fluoromethanes and the selectivity of HFO-1132(E), the reaction temperature for the reaction including thermal decomposition is preferably about 750°C to 1,050°C, more preferably about 800°C to 900°C.

[0057] From the perspective of improving both the conversion rate of fluoromethanes and the selectivity of HFO-1132(E), the reaction pressure of the above-mentioned reaction including thermal decomposition is preferably about 0 MPaG to 0.6 MPaG (gauge pressure), and more preferably about 0 MPaG to 0.3 MPaG (gauge pressure). The lower limit of the above-mentioned reaction pressure can be set to, for example, 0.01 MPaG, 0.1 MPaG, etc.

[0058] The reaction time of the above reaction including thermal decomposition can be appropriately set according to the type of fluoromethane, reaction temperature, reaction pressure, etc. From the perspective of promoting thermal decomposition of fluoromethane and efficiently obtaining HFO-1132(E), and from the perspective of suppressing side reactions and promoting thermal decomposition of fluoromethane and achieving good productivity, the above reaction time is preferably about 0.2 to 3 seconds, and more preferably 0.5 to 1 second.

[0059] The above-mentioned reaction including thermal decomposition is preferably carried out using a metal reaction vessel having an iron content of 10% by mass or less. For example, the above-mentioned reactor is preferably made of a material resistant to corrosion, such as HASTALLOY, INCONEL, MONEL, and INCOLLOY. Among the above-mentioned reactors, from the perspective of suppressing the occurrence of coking on the inner wall of the reactor, it is more preferable to use a metal reaction vessel having an iron content of 10% by mass or less, such as HASTALLOY and INCONEL.

[0060] Reaction conditions

[0061] In the production method of the present invention, when the isomerization reaction between HFO-1132(E) and HFO-1132(Z) is carried out in the reactor, that is, in the isomerization reaction from HFO-1132(E) to HFO-1132(Z) or in the isomerization reaction from HFO-1132(Z) to HFO-1132(E), the reaction is carried out at a reaction temperature of 600° C. or higher from the viewpoint of suppressing the formation of by-products.

[0062] By setting the reaction temperature to 600° C. or higher, the isomerization reaction can be rapidly performed, and the equilibrium conversion rate of the isomerization can be achieved with a short residence time.

[0063] When the isomerization reaction is performed at a reaction temperature of 600° C. or higher, it is preferably performed in the absence of a catalyst.

[0064] In the production method of the present invention, when the isomerization reaction between HFO-1132(E) and HFO-1132(Z) is carried out in the reactor, the reaction is carried out at a reaction temperature of 200° C. or higher in the absence of a catalyst from the viewpoint of suppressing the formation of by-products.

[0065] In the production method of the present invention, when the isomerization reaction is carried out at a reaction temperature of 600° C. or above, or when the isomerization reaction is carried out at a reaction temperature of 200° C. or above in the absence of a catalyst, the upper limit of the reaction temperature of the isomerization reaction is preferably about 900° C. from the perspective of increasing the yield of HFO-1132(E) or HFO-1132(Z) and suppressing the decomposition of HFO-1132(E) and HFO-1132(Z) and preventing conversion into other compounds.

[0066] In the production method of the present invention, the reaction time (residence time) of the isomerization reaction is not particularly limited and can be appropriately set. The above-mentioned isomerization reaction can be carried out in a wide residence time, preferably in the range of about 0.1 second to about 600 seconds, more preferably in the range of about 0.2 second to about 60 seconds, and more preferably in the range of about 0.4 second to about 10 seconds.

[0067] In the manufacturing method of the present invention, the pressure of the reactor of the isomerization reaction is not particularly limited and can be set appropriately. When the reaction pressure is high, the generation of polymers such as tar is promoted, so an appropriate pressure can be set. It is usually in the range of about normal pressure to about 0.2MPaG, preferably in the range of about normal pressure to about 0.1MPaG. In the manufacturing method of the present invention, the pressure is more preferably in the range of about 0.005MPaG to about 0.05MPaG. In the manufacturing method of the present invention, regarding pressure, when there is no mark, it is a gauge pressure (gauge pressure p: MPaG).

[0068] Gas phase continuous flow

[0069] In the production method of the present invention, the isomerization reaction is preferably carried out in the gas phase. As a reactor for carrying out the isomerization reaction, it is preferably carried out in a gas phase continuous flow type using a tubular reactor. When the gas phase continuous flow type is carried out, the device, operation, etc. can be simplified, so it is economically advantageous. When the reaction is carried out in a flow type, for example, it is preferred to supply a composition containing HFO-1132(E) and / or HFO-1132(Z) used as a raw material for isomerization to the reactor, set the reaction temperature to a suitable temperature using a heater or a cooler, and carry out the reaction for a certain period of time.

[0070] In the production method of the present invention, the isomerization reaction step is carried out in a flow-through reaction vessel, thereby efficiently obtaining HFO-1132(E) and / or HFO-1132(Z). The isomerization reaction can also be carried out by a flow-through method in which the raw materials are continuously added to the reactor and the target compound is continuously extracted from the reactor.

[0071] In the production method of the present invention, when an isomerization reaction is carried out between HFO-1132(E) and HFO-1132(Z), it is necessary to separate the E-form and the Z-form after the isomerization reaction. Therefore, by using a continuous reaction apparatus, the separation process can also be continuous, and the efficiency of the production equipment can be achieved. For example, by using a distillation tower in the separation process, it is possible to use Figure 1 or Figure 2 The continuous reaction apparatus shown carries out reaction and separation continuously.

[0072] In the production method of the present invention, the isomerization reaction is preferably carried out in the presence of a diluent gas. As the diluent gas, oxygen, N2 gas, helium, HF gas, argon gas, etc. can be used, and N2 gas is particularly preferred from the perspective of cost.

[0073] In order to carry out the isomerization reaction in the presence of a diluent gas, a diluent gas may be supplied to the reactor. The supply amount may be appropriately set. The diluent gas may be supplied in a molar ratio of preferably 0.01 to 3.0, more preferably 0.1 to 2.0, and even more preferably 0.2 to 1.0 relative to the total amount of HFO-1132(E) and HFO-1132(Z).

[0074] The reactor outlet gas may contain HFO-1132a as a by-product in addition to the target HFO-1132(E) and HFO-1132(Z). The reactor outlet gas may also contain unreacted HFC-143 and / or HFC-143a generated by the conversion reaction of the raw materials.

[0075] In the absence of a catalyst

[0076] In the production method of the present invention, when the isomerization reaction between HFO-1132(E) and HFO-1132(Z) is carried out in the reactor, it is preferably carried out in the absence of a catalyst (without using a catalyst). By carrying out the isomerization reaction in the absence of a catalyst, the generation of by-products can be suppressed. The production method of the present invention is economically advantageous, i.e., a method for producing HFO-1132(E) and / or HFO-1132(Z) that can reduce economic costs, because a catalyst is not required.

[0077] 2. Separation process

[0078] The production method of the present invention preferably includes a step of separating HFO-1132(E) and HFO-1132(Z) by distillation after the isomerization reaction.

[0079] The boiling point of HFO-1132(E) (trans isomer) is -52°C, and the boiling point of HFO-1132(Z) (cis isomer) is -26°C. In the production method of the present invention, when HFO-1132(E) is produced from HFO-1132(Z), the boiling point difference between HFO-1132(E) (boiling point: -52°C) and HFO-1132(Z) (boiling point: -26°C), and HFC-134 (boiling point: -20.0°C) as a by-product can be utilized to effectively separate by distillation. By this operation, HFO-1132(E) can be produced continuously and efficiently.

[0080] In the production method of the present invention, in particular, when HFO-1132(Z) is produced from HFO-1132(E), the boiling point difference between HFO-1132(Z) (boiling point: -26°C), HFO-1132(E) (boiling point: -52°C), and HFC-32 (boiling point: -51.7°C) as a by-product can be utilized to effectively separate by distillation. By this operation, HFO-1132(Z) can be produced continuously and efficiently.

[0081] 3. Recycling process

[0082] In the production method of the present invention, in order to recover a composition having a further increased content ratio of either HFO-1132(E) or HFO-1132(Z), the gas stream containing HFO-1132(E) as the main component or the gas stream containing HFO-1132(Z) as the main component obtained in the above-mentioned separation step can be recycled to the above-mentioned isomerization reaction.

[0083] The production method of the present invention preferably includes a step of recycling HFO-1132(Z) to the isomerization reaction after the separation step, and then supplying HFO-1132(Z) or a composition containing HFO-1132(E) and HFO-1132(Z) to the reactor to produce HFO-1132(E).

[0084] By recycling and using HFO-1132(Z) in this manner, a composition having a further increased content of HFO-1132(E) can be obtained in the isomerization reaction after recycling.

[0085] In the production method of the present invention, it is preferred that the step of recycling HFO-1132(E) to the isomerization reaction after the separation step is included, and HFO-1132(E) or a composition containing HFO-1132(E) and HFO-1132(Z) is further supplied to the reactor to produce HFO-1132(Z).

[0086] By recycling and using HFO-1132(E) in this manner, a composition having a further increased content of HFO-1132(Z) can be obtained in the isomerization reaction after recycling.

[0087] 4. Step of performing isomerization reaction and separation by distillation simultaneously

[0088] In the production method of the present invention, the above-mentioned isomerization reaction and separation of HFO-1132(E) and HFO-1132(Z) by distillation (reactive distillation) can also be carried out simultaneously. In the production method of the present invention, when the isomerization reaction of HFO-1132(Z) and HFO-1132(E) is carried out, by using a gas phase continuous reaction apparatus, the isomerization reaction can be carried out in a distillation tower, and HFO-1132(E) or HFO-1132(Z) can be continuously obtained by efficient distillation, and the equipment is also economical.

[0089] 5. Preferred manufacturing method

[0090] Preferred method for producing HFO-1132(E) ( Figure 1 )

[0091] In the production method of the present invention, when HFO-1132(E) is produced from HFO-1132(Z), HFO-1132(E) (boiling point: -52°C) and HFO-1132(Z) (boiling point: -26°C) as a by-product can be effectively separated by distillation. By this operation, HFO-1132(E) can be produced continuously and efficiently.

[0092] Figure 1The following is an overview of a production facility for producing HFO-1132(E) by efficiently and continuously advancing the isomerization reaction from HFO-1132(Z) to HFO-1132(E) using HFO-1132(Z) as a raw material in the production method of the present invention, particularly when carrying out the production method of HFO-1132(E).

[0093] Using HFO-1132(Z) as a raw material, an isomerization reaction from HFO-1132(Z) to HFO-1132(E) is carried out ( Figure 1 1, 2 and 3). The above raw materials may contain HFC-134 in addition to HFO-1132(Z). Then, HFO-1132(Z) and HFO-1132(E) are separated and heat is recovered ( Figure 1 4). Next, the reactor outlet gas after heat recovery is cooled and liquefied, and then separated by distillation into a gas stream containing HFO-1132 (E) as a main component and a gas stream containing HFO-1132 (Z) as a main component ( Figure 1 5, 6 and 7). By performing these operations, HFO-1132 (E) ( Figure 1 6).

[0094] Next, the process includes a step of recycling HFO-1132(Z) to the above isomerization reaction and then supplying it to the isomerization reaction to produce HFO-1132(E)( Figure 1 8 and 9). By recycling in this way, a composition having a further increased content of HFO-1132(E) can be obtained in the isomerization reaction after recycling. By performing these operations, HFO-1132(E) can be produced continuously.

[0095] When HFC-134 is contained in a gas stream containing HFO-1132(Z) as a main component, HFC-134 is separated by another distillation or the like. Figure 1 10).

[0096] Preferred method for producing HFO-1132(Z) ( Figure 2 )

[0097] In the production method of the present invention, in particular, when HFO-1132(Z) is produced from HFO-1132(E), HFO-1132(Z) (boiling point: -26°C) and HFO-1132(E) (boiling point: -52°C) as a by-product can be effectively separated by distillation. By this operation, HFO-1132(Z) can be continuously and efficiently produced.

[0098] Figure 2The following is an overview of a production facility for producing HFO-1132(Z) by efficiently and continuously advancing the isomerization reaction from HFO-1132(E) to HFO-1132(Z) using HFO-1132(E) as a raw material in the production method of the present invention, particularly when carrying out the production method of HFO-1132(Z).

[0099] Using HFO-1132(E) as a raw material, an isomerization reaction from HFO-1132(E) to HFO-1132(Z) is carried out ( Figure 2 1, 2 and 3). The above raw materials may contain HFC-32 in addition to HFO-1132(E). Then, HFO-1132(E) and HFO-1132(Z) are separated and heat recovered ( Figure 2 4). Next, the reactor outlet gas after heat recovery is cooled and liquefied, and then separated by distillation into a gas stream containing HFO-1132(Z) as a main component and a gas stream containing HFO-1132(E) as a main component ( Figure 2 5, 6 and 7). By performing these operations, HFO-1132(Z) ( Figure 2 6).

[0100] Next, the process includes a step of recycling HFO-1132(E) to the isomerization reaction and then supplying it to the isomerization reaction to produce HFO-1132(Z)( Figure 2 8 and 9). By recycling in this way, a composition having a further increased content of HFO-1132(Z) can be obtained in the isomerization reaction after recycling. By performing these operations, HFO-1132(Z) can be produced continuously.

[0101] When HFC-32 is contained in the gas stream containing HFO-1132(E) as the main component, HFC-32 is separated by another distillation or the like. Figure 2 10).

[0102] Example

[0103] Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited to these Examples and the like.

[0104] Example 1

[0105] Method for producing HFO-1132(E) Figure 1 )

[0106] like Figure 1As shown, HFO-1132(E) is efficiently produced from HFO-1132(Z). In the production method of Example 1, when HFO-1132(E) is produced from HFO-1132(Z) by an isomerization reaction at a reaction temperature of 750°C without using a catalyst, HFO-1132(E) (boiling point: -52°C) and HFO-1132(Z) (boiling point: -26°C) and HFC-134 (boiling point: -20.0°C) as a by-product are effectively separated by conventional distillation, and HFO-1132(E) is continuously and efficiently produced.

[0107] Below, use Figure 1 Provide detailed explanation.

[0108] As a raw material, a composition containing HFC-134 in addition to HFO-1132(Z) is used. Using the composition containing HFO-1132(Z) as a raw material, an isomerization reaction from HFO-1132(Z) to HFO-1132(E) is carried out ( Figure 1 1, 2 and 3). Then, HFO-1132(Z) and HFO-1132(E) are separated and heat recovered ( Figure 1 4). Next, the reactor outlet gas after heat recovery is cooled and liquefied, and then separated by distillation into a gas stream containing HFO-1132 (E) as a main component and a gas stream containing HFO-1132 (Z) as a main component ( Figure 1 5, 6 and 7). By performing these operations, HFO-1132 (E) ( Figure 1 6).

[0109] Next, HFO-1132(Z) is recycled to the above isomerization reaction and then supplied to the isomerization reaction to produce HFO-1132(E)( Figure 1 8 and 9). By carrying out the recycling treatment in this way, a composition having a further increased content ratio of HFO-1132(E) is obtained in the isomerization reaction after recycling. By carrying out these operations, HFO-1132(E) is continuously produced.

[0110] In addition, since the gas stream containing HFO-1132(Z) as the main component contains HFC-134, HFC-134 is separated by another distillation ( Figure 1 10).

[0111] Table 1 shows Figure 1 The composition ratios of HFO-1132(E) (target compound), HFO-1132(Z) and HFC-134 in each of the pathways 1 to 10.

[0112] [Table 1]

[0113]

[0114] Among the production methods of the present invention, when the production method of HFO-1132(E) is carried out, HFO-1132(Z) is used as a raw material, so that HFO-1132(E) can be efficiently and continuously produced from HFO-1132(Z).

[0115] Example 2

[0116] Method for producing HFO-1132(Z) Figure 2 )

[0117] like Figure 2 As shown, HFO-1132(Z) is efficiently produced from HFO-1132(E). In the production method of Example 1, when HFO-1132(Z) is produced from HFO-1132(E) by an isomerization reaction without using a catalyst and at a reaction temperature of 800°C, HFO-1132(Z) (boiling point: -26°C) and HFO-1132(E) (boiling point: -52°C) and HFC-32 (boiling point: -51.7°C) as a by-product are effectively separated by conventional distillation, and HFO-1132(Z) is continuously and efficiently produced.

[0118] Below, use Figure 2 Provide detailed explanation.

[0119] As a raw material, a composition containing HFC-32 in addition to HFO-1132(E) is used. Using the composition containing HFO-1132(E) as a raw material, an isomerization reaction from HFO-1132(E) to HFO-1132(Z) is carried out ( Figure 2 1, 2 and 3). Then, HFO-1132(E) and HFO-1132(Z) are separated and heat recovered ( Figure 2 4). Next, the reactor outlet gas after heat recovery is cooled and liquefied, and then separated by distillation into a gas stream containing HFO-1132(Z) as a main component and a gas stream containing HFO-1132(E) (including HFC-32) as a main component ( Figure 2 5, 6 and 7). By performing these operations, HFO-1132(Z) ( Figure 2 6).

[0120] Next, HFO-1132(E) is recycled to the above isomerization reaction and then supplied to the isomerization reaction to produce HFO-1132(Z)( Figure 28 and 9). By carrying out the recycling treatment in this way, a composition having a further increased content ratio of HFO-1132(Z) is obtained in the isomerization reaction after recycling. By carrying out these operations, HFO-1132(Z) is continuously produced.

[0121] When HFC-32 is contained in the gas stream containing HFO-1132(E) as the main component, HFC-32 is separated by another distillation. Figure 2 10).

[0122] Table 2 shows Figure 2 The composition ratios of HFO-1132(E), HFO-1132(Z) (target compound) and HFC-32 in each of the pathways 1 to 10.

[0123] [Table 2]

[0124]

[0125] Among the production methods of the present invention, when the production method of HFO-1132(Z) is carried out, HFO-1132(E) can be efficiently and continuously produced from HFO-1132(E) by using HFO-1132(E) as a raw material.

[0126] Table 3 shows the relationship between the equilibrium constants of HFO-1132(E) and HFO-1132(Z) and the reaction temperature. The values ​​in Table 3 are shown in Figure 3 Graph of the curve.

[0127] [Table 3]

[0128] Table 3 Reaction temperature Equilibrium constant ℃ - 0 0.233839 100 0.345175 200 0.432190 300 0.500311 400 0.554523 600 0.634711 700 0.665064 800 0.690827 900 0.712954

[0129] Example 3

[0130] Method for producing HFO-1132(Z)

[0131] Table 4 shows the relationship between the reaction temperature and the equilibrium ratio of HFO-1132(E) and HFO-1132(Z). In the isomerization reaction, HFO-1132(E) is supplied to the reactor to carry out the isomerization reaction. When HFO-1132(Z) is produced without using a catalyst, the existence ratio of HFO-1132(Z) becomes large, especially at a reaction temperature of about 600°C to 900°C, and the isomerization reaction can be well promoted.

[0132] [Table 4]

[0133]

[0134] Example 4

[0135] Method for producing HFO-1132(E)

[0136] Table 5 shows the relationship between the reaction temperature and the equilibrium ratio of HFO-1132(E) and HFO-1132(Z). In the isomerization reaction, HFO-1132(Z) is supplied to the reactor to carry out the isomerization reaction to produce HFO-1132(E), especially when no catalyst is used, at a reaction temperature of about 600°C to 900°C, the abundance ratio of HFO-1132(E) increases, and the isomerization reaction can be well promoted.

[0137] [Table 5]

[0138]

Claims

1. A method for producing HFO-1132(E) and / or HFO-1132(Z), characterized in that: include: A step of supplying a composition containing trans-1,2-difluoroethylene (HFO-1132(E)) and / or cis-1,2-difluoroethylene (HFO-1132(Z)) to a reactor and performing an isomerization reaction between HFO-1132(E) and HFO-1132(Z) at a reaction temperature of 200° C. to 900° C. in the absence of a catalyst.

2. The manufacturing method according to claim 1, characterized in that: In the step of performing the isomerization reaction, the reaction temperature is 600° C. to 900° C. inclusive.

3. The manufacturing method according to claim 1 or 2, characterized in that: In the isomerization reaction, HFO-1132(Z) or a composition containing HFO-1132(E) and HFO-1132(Z) is supplied to a reactor to produce HFO-1132(E).

4. The manufacturing method according to claim 1 or 2, characterized in that: In the isomerization reaction, HFO-1132(E) or a composition containing HFO-1132(E) and HFO-1132(Z) is supplied to a reactor to produce HFO-1132(Z).

5. The manufacturing method according to claim 1 or 2, characterized in that: The method comprises the step of separating HFO-1132(E) and HFO-1132(Z) by distillation after the isomerization reaction.

6. The manufacturing method according to claim 5, characterized in that: The method comprises recycling HFO-1132(Z) to the isomerization reaction step after the separation step, and then supplying HFO-1132(Z) or a composition containing HFO-1132(E) and HFO-1132(Z) to a reactor to produce HFO-1132(E).

7. The manufacturing method according to claim 5, characterized in that: The method comprises recycling HFO-1132(E) to the isomerization reaction step after the separation step, and then supplying HFO-1132(E) or a composition containing HFO-1132(E) and HFO-1132(Z) to a reactor to produce HFO-1132(Z).

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