Method for producing difluoroethylene

Abstract

The present invention provides a method for efficiently producing HFO-1132(E) and / or HFO-1132(Z). The method comprises 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) by irradiation with light.

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(Z) to 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 efficiently obtaining HFO-1132(E) and / or HFO-1132(Z).

[0008] Technical solutions to technical problems

[0009] Item 1. A method for producing HFO-1132(E) and / or HFO-1132(Z), comprising the steps of supplying a composition containing trans-1,2-difluoroethylene (HFO-1132(E)) and / or cis-1,2-difluoroethylene (HFO-1132(Z)) into a reactor, irradiating the composition with light having a wavelength of not less than 10 nm and not more than 400 nm, and thereby performing an isomerization reaction between HFO-1132(E) and HFO-1132(Z).

[0010] Item 2. A method for producing HFO-1132(E), comprising the steps of supplying HFO-1132(Z) or a composition containing HFO-1132(E) and HFO-1132(Z) into a reactor, irradiating the reactor with light having a wavelength of not less than 10 nm and not more than 400 nm, and thereby performing an isomerization reaction between HFO-1132(E) and HFO-1132(Z).

[0011] Item 3. The production method according to Item 1 or 2 above, wherein the isomerization reaction is carried out in a gas phase.

[0012] Item 4. The production method according to any one of Items 1 to 3, further comprising a separation step of separating HFO-1132(E) and HFO-1132(Z) by distillation after the isomerization reaction.

[0013] Item 5. The production method according to Item 4, further comprising the step of subjecting HFO-1132(Z) to the isomerization reaction again after the separation step, and further subjecting the HFO-1132(Z) to the isomerization reaction.

[0014] Effects of the Invention

[0015] According to the present invention, HFO-1132(E) and / or HFO-1132(Z) can be obtained efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a diagram schematically showing the method for producing HFO-1132(E) and / or HFO-1132(Z) according to the present invention.

[0017] Figure 2 This is a diagram schematically showing a method for efficiently obtaining HFO-1132(E) in the method for producing HFO-1132(E) and / or HFO-1132(Z) of the present invention. DETAILED DESCRIPTION

[0018] The inventors discovered that conventional methods for producing HFO-1132 by dehydrofluorinating trihaloethanes such as 1,1,2-trifluoroethane (HFC-143) in the presence of a catalyst simultaneously produce both HFO-1132(E) and HFO-1132(Z) as isomers. Therefore, if only one isomer is desired, the other is unnecessary, resulting in cost inefficiency. The inventors also discovered that conventional isomerization reactions use iodine, which is highly corrosive and has a low sublimation point, making it difficult to implement in a commercial facility.

[0019] Therefore, the technical problem to be solved by the present invention is to provide a solution to this technical problem. Specifically, the technical problem to be solved by the present invention is to provide a method for more efficiently producing HFO-1132(E) and / or HFO-1132(Z) when HFO-1132(E) and HFO-1132(Z) are simultaneously produced, such as by a method for producing HFO-1132 by dehydrohalogenation of a trihaloethane.

[0020] To solve the above-mentioned technical problems, the inventors of the present invention conducted intensive research and discovered that a reaction composition containing HFO-1132, obtained by dehydrohalogenation of trihaloethanes, can be isomerized by irradiation with light. They also discovered that combining an isomerization step with a step for separating the desired isomers can solve the above-mentioned technical problems. The present invention, which was completed through further research based on this finding, includes the following aspects.

[0021] 1. Isomerization reaction process

[0022] The production method of the present invention is a production method of HFO-1132(E) and / or HFO-1132(Z), comprising the steps of supplying a composition containing HFO-1132(E) and / or HFO-1132(Z) into a reactor, irradiating the composition with light having a wavelength of 10 nm to 400 nm (by light irradiation), and performing an isomerization reaction between HFO-1132(E) and HFO-1132(Z). Figure 1 ).

[0023] The production method of the present invention is a method for producing HFO-1132(E), comprising the steps of supplying HFO-1132(Z) or a composition containing HFO-1132(E) and HFO-1132(Z) into a reactor, irradiating the reactor with light having a wavelength of 10 nm to 400 nm (by light irradiation), and performing an isomerization reaction between HFO-1132(E) and HFO-1132(Z).

[0024] In the present invention, an isomerization reaction between HFO-1132(E) and HFO-1132(Z) proceeds. This isomerization reaction follows the following reaction formula. Since the E-isomer is thermodynamically less stable than the Z-isomer, the equilibrium is biased toward the Z-isomer.

[0025]

[0026] In the present invention, by subjecting a composition containing HFO-1132(E) and / or HFO-1132(Z) to an isomerization reaction, a composition having a further increased HFO-1132(E) content can be obtained. Regarding this content, as the isomerization reaction proceeds during light irradiation, HFO-1132(Z) decreases and HFO-1132(E) increases.

[0027] In the present invention, the isomerization reaction is preferably carried out in a gas phase.

[0028] In the present invention, the photoirradiation for the isomerization reaction is performed by irradiating light having a wavelength of 10 nm to 400 nm.

[0029] In the present invention, by utilizing the equilibrium relationship of the isomerization reaction between HFO-1132(E) and HFO-1132(Z), a composition having a further increased content ratio of either compound can be obtained.

[0030] 1-1. Compositions containing HFO-1132(E) and / or HFO-1132(Z)

[0031] The composition containing HFO-1132(E) and / or HFO-1132(Z) used as a raw material for isomerization may contain other components. Such other components are not particularly limited and can be selected from a wide range as long as they do not significantly inhibit the isomerization reaction.

[0032] Examples of other components include impurities and by-products that are mixed in during the process of obtaining the composition containing HFO-1132(E) and / or HFO-1132(Z). The mixed impurities include impurities contained in the raw materials.

[0033] Examples of methods for obtaining a composition containing HFO-1132(E) and / or HFO-1132(Z) as a raw material include methods such as subjecting an ethane halide to a dehydrohalogenation reaction or a dehalogenation reaction. The ethane halide used in such a reaction is not particularly limited and can be selected from a wide range of sources. Specific examples include the following ethane halide. These ethane halide are widely used in applications such as refrigerants, solvents, foaming agents, and propellants and can be obtained by conventional methods.

[0034] 1,1,2-Trifluoroethane (CHF2CH2F, HFC-143)

[0035] 1-Bromo-1,2-difluoroethane (CHFBrCH2F)

[0036] 1-Chloro-1,2-difluoroethane (CHClFCH2F)

[0037] 1,2-Dichloro-1,2-difluoroethane (CHClFCHClF)

[0038] 1,1,2,2-tetrafluoroethane (CHF2CHF2)

[0039] 1-Chloro-1,2,2-trifluoroethane (CHClFCHF2)

[0040] In the present invention, particularly in the method for producing HFO-1132(E), by using HFO-1132(Z) as a raw material, the isomerization reaction from HFO-1132(Z) to HFO-1132(E) can be efficiently carried out.

[0041] 1-2. Reaction Conditions

[0042] Reaction temperature, time and pressure

[0043] In the isomerization reaction of the present invention, the reaction temperature is not particularly limited and can be appropriately set. The reaction temperature can be in the range of approximately -20°C to 200°C, preferably in the range of approximately 0°C to 100°C.

[0044] In the isomerization reaction of the present invention, the reaction time is not particularly limited and can be appropriately set. When the contact time is extended, the conversion rate can be improved, but a longer light irradiation time is inefficient, so an appropriate residence time can be set. It can generally be in the range of about 0.1 seconds to 100 seconds, preferably in the range of about 1 second to 50 seconds.

[0045] In the isomerization reaction of the present invention, the reactor pressure is not particularly limited and can be set appropriately. High pressure promotes the formation of polymers such as tar. Therefore, the isomerization reaction of the present invention can be performed under an appropriate pressure, typically within a range of atmospheric pressure to 0.2 MPa, preferably within a range of atmospheric pressure to 0.1 MPa. In the present invention, pressure, unless otherwise specified, refers to gauge pressure.

[0046] Gas phase reaction

[0047] In the present invention, the isomerization reaction is preferably carried out in the gas phase. 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. In particular, N2 gas is preferred from the perspective of cost.

[0048] To carry out the isomerization reaction in the presence of a diluent gas, it is sufficient to supply the diluent gas to the reactor. The supply amount can be appropriately set. In particular, it is preferably supplied at a molar ratio of 0.01 to 3.0 relative to the total amount of HFO-1132(E) and HFO-1132(Z), more preferably at a molar ratio of 0.1 to 2.0, and even more preferably at a molar ratio of 0.2 to 1.0.

[0049] Light exposure

[0050] In the present invention, the isomerization reaction is carried out by irradiating light having a wavelength of 10 nm to 400 nm. The light source for the irradiation is not particularly limited, but preferably, an excimer lamp, a low-pressure mercury lamp, a deuterium lamp, or the like can be used.

[0051] In the present invention, as a light irradiation device, for example, a batch excimer irradiation device (Model: MECL01U-1) can be used. For example, the number of lamps can be set to 1 lamp, and the light irradiation area can be set to an effective length of about 140 mm × 10 to 30 mm, and light irradiation can be performed. In the present invention, a wavelength of 172 nm and an intensity of 80 mW / cm 2 As the reaction tube used for the light irradiation reaction, it is preferable to use a tube with a diameter of 172 nm because the light irradiation is preferably carried out at a wavelength of 172 nm. A synthetic quartz tube (F310 manufactured by Shin-Etsu Quartz Co., Ltd.) of 3 mm x 150 mm in length.

[0052] The production method of the present invention is characterized by irradiating HFO-1132(E) and / or HFO-1132(Z) molecules themselves with light having a wavelength of 10 nm to 400 nm, and then directly irradiating the molecules to induce an isomerization reaction. This production method of the present invention does not require a photosensitizer, catalyst, or the like, and is an economically advantageous method for producing HFO-1132(E) and / or HFO-1132(Z).

[0053] Batch reaction

[0054] In the present invention, it is preferred to carry out the isomerization reaction in the gas phase. As a reactor for carrying out the isomerization reaction, a batch-type reaction vessel is preferably used to carry out the isomerization reaction. In a batch-type reaction, a reaction vessel of a closed reaction system can be used. When the reaction is carried out in a batch-type manner, for example, a composition containing HFO-1132(E) and / or HFO-1132(Z) as a raw material for isomerization is preferably added to the reactor, and a suitable reaction temperature is set using a heater, etc., and light irradiation is implemented to carry out the reaction for a certain period of time. As a reaction atmosphere, the reaction is preferably carried out in an atmosphere of an inert gas such as nitrogen, helium, or carbon dioxide gas.

[0055] In the present invention, when the isomerization reaction is carried out in a batch manner (eg, a closed reaction system), the reaction temperature is preferably in the range of approximately -20°C to 200°C, more preferably in the range of approximately 0°C to 100°C, from the viewpoint of more efficient isomerization.

[0056] In the isomerization reaction step of the present invention, HFO-1132(E) and / or HFO-1132(Z) can be efficiently obtained by performing the reaction in a batch-type reaction vessel (such as a sealed reaction vessel).

[0057] Flow-through reaction

[0058] In the present invention, it is preferred to carry out the isomerization reaction in the gas phase. As a reactor for carrying out the isomerization reaction, it is preferred to use a gas phase continuous flow type using a fixed bed reactor. When the gas phase continuous flow type is used, the device, operation, etc. can be simplified, and it is economically advantageous. When the reaction is carried out using a flow type, for example, it is preferred to add a composition containing HFO-1132(E) and / or HFO-1132(Z) used as a raw material for isomerization to the reactor, set the temperature to a suitable reaction temperature using a heater, implement light irradiation, and react for a certain period of time. As a reaction atmosphere, it is preferred to carry out the reaction in an atmosphere of an inert gas such as nitrogen, helium, or carbon dioxide gas.

[0059] In the present invention, when the isomerization reaction is carried out by a flow method (eg, a gas phase continuous flow method), the reaction temperature is preferably in the range of about -20°C to 200°C, more preferably in the range of about 0°C to 100°C, from the viewpoint of more efficient isomerization reaction.

[0060] In the isomerization reaction step of the present invention, HFO-1132(E) and / or HFO-1132(Z) can be efficiently obtained by performing the reaction in a flow-through reaction vessel (such as a gas-phase continuous flow reactor).

[0061] The isomerization reaction can be carried out using either a flow-through method, in which the raw materials are continuously added to the reactor and the target compound is continuously removed from the reactor, or a batch method. The flow-through method is preferred because the target compound does not remain in the reactor and the isomerization reaction can proceed continuously.

[0062] 2. Separation process

[0063] The present invention includes a step of separating HFO-1132(E) and HFO-1132(Z) by distillation after the above-mentioned isomerization reaction, and producing HFO-1132(E) and / or HFO-1132(Z) ( Figure 2 ).

[0064] The boiling point of HFO-1132(E) is -53°C, and the boiling point of HFO-1132(Z) is -26°C. Therefore, by utilizing the difference in boiling points between the two, HFO-1132(E) and HFO-1132(Z) can be separated by distillation.

[0065] For example, the reaction product obtained by the isomerization reaction is separated into a first gas stream containing HFO-1132(E) as the main component and a second gas stream containing HFO-1132(Z) as the main component. Specifically, the reactor outlet gas generated by the isomerization reaction is cooled and liquefied, and then distilled to separate the first gas stream containing HFO-1132(E) as the main component and the second gas stream containing HFO-1132(Z) as the main component.

[0066] 3. Recycling process

[0067] The present invention includes a step of transferring HFO-1132(Z) to the above-mentioned reactor for reuse after the above-mentioned separation step and then subjecting it to an isomerization reaction to produce HFO-1132(E) and / or HFO-1132(Z) ( Figure 2 ).

[0068] In the present invention, in order to recover a composition having a further increased content of either HFO-1132(E) or HFO-1132(Z), the first gas stream containing HFO-1132(E) as a main component or the second gas stream containing HFO-1132(Z) as a main component obtained in the above separation step can be fed again to the above isomerization reaction.

[0069] After the separation step, for example, by reusing the second gas stream containing HFO-1132(Z) as its main component, a composition having a further increased HFO-1132(E) content can be obtained in the isomerization reaction after the reuse. Alternatively, by reusing the first gas stream containing HFO-1132(E) as its main component in the reuse step, a composition having a further increased HFO-1132(Z) content can be obtained in the isomerization reaction after the reuse.

[0070] The production method of the present invention efficiently converts undesirable isomers, which are inevitably produced as byproducts during the production of HFO-1132(E) and / or HFO-1132(Z), into desired isomers, significantly improving the economic efficiency of the method for producing the desired isomers. HFO-1132(E) and / or HFO-1132(Z) produced by the production method of the present invention are highly suitable for various applications, such as raw materials for resin products, intermediates in organic synthesis, and heat transfer media.

[0071] Example

[0072] Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited to these Examples and the like.

[0073] (1) Isomerization reaction

[0074] A composition containing HFO-1132(E) and / or HFO-1132(Z) (raw material composition) is supplied to a reactor, and an isomerization reaction between HFO-1132(E) and HFO-1132(Z) proceeds by light irradiation, thereby obtaining a reaction composition having an increased isomer concentration of HFO-1132(E) compared to the supplied raw material composition.

[0075] Isomerization reaction conditions

[0076] Light irradiation device: Batch excimer irradiation device

[0077] Model:MECL01U-1

[0078] Light irradiation area: Effective length 140mm×10~30mm (172nm)

[0079] Number of lights: 1 light

[0080] Wavelength and illumination: 172nm type, 80mW / cm 2 above

[0081] Reaction tube: Shin-Etsu Quartz F310 (synthetic quartz tube) diameter 3×150mm in length

[0082] Dwell time: 60 seconds

[0083] Reaction temperature: 30°C

[0084] (2) Results of isomerization reaction

[0085] The reaction results are shown in Table 1.

[0086] [Table 1]

[0087] Table 1 Light exposure HFO-1132(E) HFO-1132(Z) Before irradiation 0.11％ 99.89％ After irradiation 5.0％ 95.0％

[0088] The production method of the present invention can be constructed to efficiently produce the target HFO-1132(E) and / or HFO-1132(Z), and it can be evaluated that HFO-1132(E) can be obtained efficiently.

Claims

1. A method for producing HFO-1132(E), characterized in that: The process includes the following steps: A step of supplying HFO-1132(Z) or a composition containing HFO-1132(E) and HFO-1132(Z) to a reactor, irradiating the mixture with light having a wavelength of 10 nm to 172 nm, and performing an isomerization reaction between HFO-1132(E) and HFO-1132(Z) at a reaction temperature range of -20°C to 200°C.

2. The manufacturing method according to claim 1, wherein: The residence time of the isomerization reaction is 0.1 seconds to 100 seconds.

3. The manufacturing method according to claim 1 or 2, wherein: The isomerization reaction is carried out in the gas phase.

4. The manufacturing method according to claim 1 or 2, wherein: The method includes a separation step of separating HFO-1132(E) and HFO-1132(Z) by distillation after the isomerization reaction.

5. The manufacturing method according to claim 4, wherein: The method includes the step of returning HFO-1132(Z) to the isomerization reaction after the separation step and supplying the HFO-1132(Z) to the isomerization reaction again.

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