Method for producing fluoroolefin

Abstract

The present disclosure mainly addresses the problem of providing a novel method for producing a fluoroolefin.　Provided as a solution is a method for producing a fluoroolefin represented by general formula (1): CX1X2=CX3X4 (where X1, X2, X3, and X4 are identical or different and each represent a hydrogen atom, a fluorine atom, or a chlorine atom, and at least one of X1, X2, X3, and X4 is a fluorine atom), said method comprising a dehydrohalogenation step for bringing a fluorocarbon represented by general formula (2): CX1X2HCX3X4Y (where X1, X2, X3, and X4 are the same as above, and Y is a fluorine atom or a chlorine atom) into contact with a noble metal catalyst to perform dehydrohalogenation.

Description

Method for producing fluoroolefin

[0001] The present disclosure relates to a method for producing fluoroolefin.

[0002] In recent years, 1,1-difluoroethylene (HFO-1132a) represented by CF =CH ２ and 1,2-difluoroethylene (HFO-1132) represented by CFH=CFH are regarded as promising refrigerant compounds with a low global warming potential (GWP).

[0003] Patent Document 1 describes a method for producing fluoroolefin by performing a dehydrofluorination reaction using an α-alumina catalyst in a temperature range of 300°C to 800°C.

[0004] Non-Patent Document 1 describes a method for producing fluoroolefin by performing a dehydrofluorination reaction using a θ-alumina catalyst in a temperature range of 400°C to 500°C.

[0005] International Publication No. 2024 / 057657

[0006] Jia W et al., Catal Letters., 2015, 145 : 654-661

[0007] As described above, the production of fluoroolefin using an alumina catalyst requires high temperature conditions, which poses a problem of production cost.

[0008] The present disclosure has been made in view of solving the above problems, and an object thereof is to provide a new method for producing fluoroolefin.

[0009] The present disclosure is, for example, as follows. Item 1. General formula (1): CX １ X ２ =CX ３ X ４ (wherein X １ , X ２ , X<​​​​​​​​​​A method for producing a fluoroolefin represented by the general formula (2): CX １ X ２ HCX ３ X ４ Y (wherein, X １ , X ２ , X ３ and X ４ A manufacturing method comprising a dehalogenation step in which a fluorocarbon represented by ( is the same as above, and Y is a fluorine atom or a chlorine atom) is contacted with a noble metal catalyst to dehalogenate it. Item 2. The above X １ , X ２ , X ３ and X ４ The same or different, representing a hydrogen atom or a fluorine atom, and the X １ , X ２ , X ３ and X ４ The method for producing a product according to claim 1, wherein at least one of is a fluorine atom, and Y is a fluorine atom. Claim 3. The method for producing a product according to claim 1 or 2, wherein the fluoroolefin represented by general formula (1) is 1,2-difluoroethylene (HFO-1132) or trifluoroethylene (HFO-1123). Claim 4. The method for producing a product according to any one of claims 1 to 3, wherein the noble metal catalyst is a palladium catalyst. Claim 5. The method for producing a product according to any one of claims 1 to 4, wherein the dehalogenation step is carried out at a temperature of 200°C to 400°C. Claim 6. The method for producing a product according to any one of claims 1 to 4, wherein the noble metal catalyst is carbon or alumina (Al ２ O ３ A manufacturing method according to any one of claims 1 to 5, wherein the noble metal catalyst is supported on a carrier containing ) . Claim 7. A manufacturing method according to any one of claims 1 to 6, wherein the noble metal catalyst is supported in an amount of less than 10% by mass relative to the total of the noble metal catalyst and the carrier.

[0010] This disclosure provides a novel method for producing fluoroolefins.

[0011] This figure shows the relationship between the amount of HFO-1132 produced and the reactor temperature when using a Pd-alumina catalyst. This figure shows the relationship between the amount of HFO-1132 produced and the reactor temperature when using a Pd-carbon catalyst. This figure shows the relationship between the amount of HFO-1132 produced and the reactor temperature when using a Pd-carbon catalyst. This figure compares the HFO-1132 production start temperatures when using each catalyst. This is a schematic diagram showing an example of a catalytic reactor used in the manufacturing method of this disclosure.

[0012] As a result of diligent research, the inventors have discovered that fluoroolefins represented by the above general formula (1) can be produced under low temperature conditions by reacting a raw material compound with a noble metal catalyst.

[0013] This disclosure is the result of further research based on the aforementioned findings. This disclosure includes the following embodiments.

[0014] The general formula (1) CX of this disclosure １ X ２ = CX ３ X ４ (In the formula, X １ , X ２ , X ３ and X ４ X represents a hydrogen atom, a fluorine atom, or a chlorine atom, and is either the same or different. １ , X ２ , X ３ and X ４ A method for producing a fluoroolefin represented by the general formula (2):CX １ X ２ HCX ３ X ４ Y (wherein, X １ , X ２ , X ３ and X ４ The present invention comprises a dehalogenation step in which a fluorocarbon (also referred to in this disclosure as a raw material compound) represented by the same as described above, where Y is a fluorine atom or a chlorine atom, is brought into contact with a noble metal catalyst to remove hydrogen halide.

[0015] The manufacturing method of the present disclosure includes a dehalogenation step in which a fluorocarbon represented by the above general formula (2) is contacted with a noble metal catalyst to remove hydrogen halogenation. This step makes it possible to produce a fluoroolefin represented by the above general formula (1), and in particular, it is possible to produce it under lower temperature conditions than conventional methods.

[0016] In this disclosure, when a numerical range is indicated as "A to B", it means A or greater and B or less.

[0017] In this disclosure, "conversion rate" means the ratio (mol%) of the total molar amount of compounds other than the raw material compound contained in the effluent gas from the reactor outlet to the molar amount of the raw material compound supplied to the reactor. "Selectivity" means the ratio (mol%) of the total molar amount of the target compound contained in the effluent gas from the reactor outlet to the total molar amount of compounds other than the raw material compound in said effluent gas.

[0018] 1. Raw Material Compound In this disclosure, the raw material compound is defined as having the general formula (2): CX １ X ２ HCX ３ X ４ Y (wherein, X １ , X ２ , X ３ and X ４ The same as above, and Y is a fluorine atom or a chlorine atom. ) This is a fluorocarbon represented by .

[0019] The fluorocarbons represented by the above general formula (2) are fluoroethane (HFC-161), 1,1-difluoroethane (HFC-152a), 1,2-difluoroethane (HFC-152), 1,1,1-trifluoroethane (HFC-143a), 1,1,2-trifluoroethane (HFC-143), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,2-tetrafluoroethane (HFC-134a), pentafluoroethane (HFC-125), 1-chloro-1-fluoroethane (HCFC-151a), 1-chloro-2-fluoroethane (HCFC-151), and 1,2-dichloro-1-fluoroethane. Preferably, it is at least one selected from the group consisting of oleethane (HCFC-141), 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123), 1-chloro-2,2-difluoroethane (HCFC-142), 1-chloro-1,2-difluoroethane (HCFC-142a), 1-chloro-1,1-difluoroethane (HCFC-142b), 1,1,2-trichloro-1,2,2-trifluoroethane (HCFC-113), 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124), and 1-chloro-1,1,2,2-tetrafluoroethane (HCFC-124a). Of these, 1,1,2-trifluoroethane (HFC-143), 1,1,2,2-tetrafluoroethane (HFC-134), or 1,1,1,2-tetrafluoroethane (HFC-134a) are more preferred.

[0020] HFC-143 can be produced by reducing chlorotrifluoroethylene (CTFE) with hydrogen in the presence of a palladium or platinum catalyst. Alternatively, HFC-143 can be produced by reducing HFO-1123 or CFC-113 (1,1,2-trichloro-1,2,2-trifluoroethane) with hydrogen in the presence of palladium. Furthermore, HFC-143 can be produced by fluorinating 1,1,2-trichloroethane with mercury oxide in the presence of hydrogen fluoride.

[0021] 2. Dehalogenation Process In the dehalogenation process described herein, the raw material compound is brought into contact with a noble metal catalyst to perform dehalogenation.

[0022] For example, when HFC-134 is used as the starting compound, the dehalogenation (defluorination) reaction follows the following reaction equation: CF ２ HCF ２ H → CF ２ =CHF + HF (HFC-134) 　　 (HFO-1123)

[0023] The precious metal catalyst used in this process is preferably a palladium catalyst, platinum catalyst, rhodium catalyst, ruthenium catalyst, silver catalyst, gold catalyst, iridium catalyst, or osmium catalyst. Of these, a palladium catalyst is more preferred because it is used in a variety of applications and is readily available.

[0024] In this process, when bringing the raw material compound into contact with the noble metal catalyst, it is preferable to bring the noble metal catalyst into contact with the raw material compound in a solid state (solid phase).

[0025] The above-mentioned precious metal catalyst is preferably supported on a carrier. Examples of carriers include carbon and alumina (Al ２ O ３ ), Zirconia (ZrO ２ ), silica (SiO ２ ), Titania (TiO ２ Examples include ) etc. As carbon, activated carbon, amorphous carbon, graphite, diamond, etc. can be used. Because the support is corroded by hydrofluoric acid produced during the reaction, the noble metal catalyst may be carbon or alumina (Al ２ O ３ It is more preferable that the material be supported on a carrier containing ).

[0026] When a precious metal catalyst is supported on a carrier, it is preferable that the amount of the precious metal catalyst supported is less than 10% by mass, and more preferably 5% by mass or less, relative to the total amount of the precious metal catalyst and the carrier. Furthermore, the lower limit of the amount of precious metal catalyst supported is not particularly limited and may be 0%, 0.1%, or 0.5% by mass.

[0027] Palladium catalysts can be obtained by known methods.

[0028] Japanese Patent Publication No. 6673413 describes a method for producing fluoroolefins using chromium oxide. In this reaction, oxygen must be circulated to maintain the activity of the catalyst. However, the circulation of oxygen necessitates separation in subsequent steps, which worsens the recovery rate. On the other hand, the method of this disclosure is preferable because it eliminates the need to maintain the activity of the catalyst with oxygen and improves the recovery rate. Therefore, the dehalogenation reaction of this disclosure is preferably carried out in the absence of oxygen.

[0029] The lower limit of the reaction temperature in the dehalogenation reaction is preferably 160°C, more preferably 180°C, and particularly preferably 200°C, from the viewpoint of more efficiently carrying out the dehalogenation reaction and suppressing a decrease in the conversion rate.

[0030] From the viewpoint of more efficiently carrying out the dehalogenation reaction and suppressing the decrease in selectivity due to the decomposition or polymerization of the reaction product, the upper limit of the reaction temperature in the dehalogenation reaction is preferably 400°C, and more preferably 350°C. To reduce manufacturing costs, 300°C is particularly preferred.

[0031] For example, when using a palladium catalyst as a precious metal catalyst, from the viewpoint of manufacturing cost, the reaction temperature in the dehalogenation reaction is preferably 200°C to 400°C, more preferably 200°C to 350°C, and particularly preferably 200°C to 300°C. Even when the reaction is carried out at 200°C to 300°C, from the viewpoint of catalytic activity, it is preferable to raise the temperature to 300°C or higher at one point, and more preferably to raise the temperature above 300°C at one point. Once the temperature is within the above range, the reaction may be carried out by lowering the temperature from the highest temperature thereafter, or the reaction may be carried out while maintaining the temperature.

[0032] The contact time of the raw material compound with the noble metal catalyst refers to the time during which the raw material compound and the noble metal catalyst are in contact.

[0033] The reaction pressure for the dehalogenation reaction is preferably 0 MPa to 2 MPa, more preferably 0 MPa to 0.9 MPa, and even more preferably 0 to 0.5 MPa, from the viewpoint of more efficiently carrying out the dehalogenation reaction. In this disclosure, unless otherwise specified, pressure refers to gauge pressure.

[0034] In the dehalogenation reaction, the reactor used to contact the raw material compound with the noble metal catalyst is not particularly limited in shape and structure, as long as it can withstand the above-mentioned temperature and pressure. Examples of reactors include vertical reactors, horizontal reactors, and multi-tube reactors. Examples of reactor materials include glass, stainless steel, iron, nickel, and iron-nickel alloys.

[0035] The dehalogenation reaction can be carried out by either a continuous flow system or a batch system, in which the starting compound is continuously charged into the reactor and the target compound is continuously withdrawn from the reactor. Since the dehalogenation reaction can continue if the target compound remains in the reactor, it is preferable to carry out the reaction by the continuous flow system.

[0036] The atmosphere during the dehalogenation reaction may be in the presence of an inert gas to avoid side reactions. This inert gas may be nitrogen, helium, argon, carbon dioxide, or a mixture thereof.

[0037] 3. Target Compound The target compound in this disclosure is the general formula (1): CX １ X ２ = CX ３ X ４ (In the formula, X １ , X ２ , X ３ and X ４ It is a fluoroolefin represented by the same as above.

[0038] The fluoroolefin represented by the above general formula (1) preferably does not contain chlorine atoms in order to reduce the ozone depletion potential (ODP). That is, in the formula (1), X １ , X ２ , X ３ and X ４X represents either the same or different hydrogen atom or fluorine atom. １ , X ２ , X ３ and X ４ It is preferable that at least one of the atoms is a fluorine atom. In this case, it is preferable that Y in the general formula (2) of the starting compound is a fluorine atom.

[0039] The fluoroolefin represented by the above general formula (1) is preferably at least one selected from the group consisting of fluoroethylene (HFO-1141), 1,1-difluoroethylene (HFO-1132a), 1,2-difluoroethylene (HFO-1132), or trifluoroethylene (HFO-1123). Of these, HFO-1132 or HFO-1123 is more preferred, and HFO-1132 is particularly preferred. Here, HFO-1132 includes trans-1,2-difluoroethylene ((E)-HFO-1132) and cis-1,2-difluoroethylene ((Z)-HFO-1132).

[0040] In this disclosure, the combinations of the above raw material compound and the above target compound are as follows:

[0041] When HFC-143 is used as the raw material compound, HFO-1132 can be obtained as the target compound after a dehydrofluoride reaction.

[0042] When HFC-143a is used as the raw material compound, HFO-1132a can be obtained as the target compound after a dehydrofluoride reaction.

[0043] When HFC-134 is used as the raw material compound, HFO-1123 can be obtained as the target compound after a dehydrofluoride reaction.

[0044] When HFC-134a is used as the raw material compound, HFO-1123 can be obtained as the target compound after a dehydrofluoride reaction.

[0045] If the target compound is either (E)-HFO-1132) or (Z)-HFO-1132, an isomerization reaction may be carried out. The isomerization reaction may be carried out using the noble metal catalyst of this disclosure. Therefore, the isomerization reaction may be carried out simultaneously with the dehalogenation reaction of this disclosure. Alternatively, the isomerization reaction may be carried out after the dehalogenation reaction.

[0046] The present disclosure will be specifically explained below with reference to examples, comparative examples, and reference examples, but the present disclosure is not limited in any way by these examples.

[0047] Example 1 A 100cc portable reactor from Pressure-Resistant Glass Industry, equipped with a pressure gauge, contained 0.5g of 2% Pd alumina spheres (NE Chemcat Co., Ltd.) and 3g of soda lime (Fujifilm Wako Pure Chemical Industries, Ltd.). The reactor was then closed and degassed using a vacuum pump. HFC-143 gas was filled into the reactor at a pressure of 0.1 MPa. A belt heater was wrapped around the reactor container, and the temperature was set using a digital temperature controller TC-1 (AS ONE Corporation). The experiment started at room temperature, and the temperature was gradually increased up to 350°C. After that, the temperature was lowered to 200°C and maintained thereafter. The products were analyzed at each temperature.

[0048] Gas was collected from the reactor's sampling port using a 2 ml glass syringe, and the product was analyzed using Shimadzu Corporation's NEXIS GC-2030 and GCMS-QP2020NX. An Agilent Technologies PoraPLOT Q column (length: 50 m, inner diameter: 0.32 mm, film thickness: 10 μm) was used with the GC-2030.

[0049] Mass spectrometry results confirmed the formation of (E)-HFO-1132, (Z)-HFO-1132, HFO-1132a, and HFO-1141.

[0050] The combined yield (selectivity) of (E)-HFO-1132, (Z)-HFO-1132, HFO-1132a, and HFO-1141 was 85.1 mol% at 250°C. The selectivity for (E)-HFO-1132 and (Z)-HFO-1132 was 0.04 mol% and 2.7 mol%, respectively. The results are shown in Figures 1 and 4.

[0051] Example 2 The dehydrofluoride reaction and mass spectrometry were carried out in the same manner as in Example 1, except that a palladium catalyst supported on coconut shell charcoal (Pd-carbon catalyst, NE Chemcat Co., Ltd.) was used as the precious metal catalyst, and the upper limit of the reaction temperature was changed from 350°C to 400°C. The palladium content was 2% by mass relative to the total Pd-carbon catalyst.

[0052] The combined yield (selectivity) of (E)-HFO-1132, (Z)-HFO-1132, HFO-1132a, and HFO-1141 was 100 mol% at 250°C. The selectivity for (E)-HFO-1132 and (Z)-HFO-1132 was 20.2 mol% and 79.8 mol%, respectively. The results are shown in Figures 2 and 4.

[0053] Example 3 The automated catalyst reactor used in this experiment is shown in Figure 5. An F-201CL (Bronkost Corporation) flow meter, a PGI-50M-MG5.0 (Swagelok Corporation) pressure gauge, an ARF3-400-9.52KC (Asahi Rika Seisakusho Co., Ltd.) electric furnace, and 1 / 4-inch outer diameter stainless steel piping were used. HFC-143 was used as the raw material. For the reactor (reaction tube), the material was Hastelloy C276, the inner diameter was 7.53 mm, and the catalyst placed inside the reaction tube was heated by covering the outside with an electric furnace.

[0054] The gas after the dehydrofluoric acid reaction was passed through a deoxidation tower filled with soda lime (medium granular; Fujifilm Wako Pure Chemical Industries, Ltd.) and a dehydration tower filled with calcium chloride (Fujifilm Wako Pure Chemical Industries, Ltd.) to remove hydrofluoric acid and water.

[0055] 0.17 g of a 0.02% Ru / θ alumina catalyst was used as the catalyst. The catalyst in the reaction tube was pretreated by supplying a gas of HFC-143, the raw material, diluted 50% with nitrogen, to the reactor at a flow rate of 20 ml / min and heating the reaction tube at a temperature of 400°C for more than 3 hours. After that, heating was stopped and the temperature in the reaction tube was lowered to room temperature (approximately 20°C). The temperature in the reaction tube was heated again to 50°C and HFC-143 was flowed through for 1 hour, after which the reaction gas was collected from the exhaust port using a 2 ml glass syringe. The same procedure was performed in 50°C increments from 50°C to 350°C, and the changes in the reaction products were investigated.

[0056] The reaction gas contained the fluorinated organic compounds (E)-HFO-1132, (Z)-HFO-1132, HFC-152a, HFO-1141, and R-1132a. The selectivity of (E)-HFO-1132 and (Z)-HFO-1132 in the reaction gas increased in the catalyst temperature range up to 350°C (Table 1).

[0057]

[0058] Comparative Example 1: The dehydrofluoride reaction and mass spectrometry were carried out in the same manner as in Example 2, except that a γ-alumina catalyst was used as a comparative example.

[0059] The combined yield (selectivity) of (E)-HFO-1132, (Z)-HFO-1132, HFO-1132a, and HFO-1141 was 47.6 mol% at 250°C. The selectivity for (E)-HFO-1132 and (Z)-HFO-1132 was 0.00 mol% and 16.6 mol%, respectively. The results are shown in Figures 3 and 4.

[0060] It can be seen that the dehydrofluoride reaction proceeds in a temperature-dependent manner in each catalyst. Furthermore, it can be seen that the formation of the target compound, HFO-1132, begins at lower temperatures when using a noble metal catalyst compared to when using a γ-alumina catalyst.

Claims

1. General formula (1): CX １ X ２ =CX ３ X ４ (wherein, X １ , X ２ , X ３ and X ４ are the same or different and each represents a hydrogen atom, a fluorine atom or a chlorine atom, and at least one of X １ , X ２ , X ３ and X ４ is a fluorine atom.). A method for producing a fluoroolefin represented by the following general formula (2): CX １ X ２ HCX ３ X ４ Y (wherein, X １ [[ID=3,4]]X ２ , X ３ and X ４ are the same as defined above, and Y is a fluorine atom or a chlorine atom.). The production method includes a dehydrohalogenation step of contacting the fluorocarbon represented by the formula with a noble metal catalyst for dehydrohalogenation.

2. The aforementioned X １ , X ２ , X ３ and X ４ The same or different, representing a hydrogen atom or a fluorine atom, and the X １ , X ２ , X ３ and X ４ The manufacturing method according to claim 1, wherein at least one of is a fluorine atom, and Y is a fluorine atom.

3. The manufacturing method according to claim 1, wherein the fluoroolefin represented by the general formula (1) is 1,2-difluoroethylene (HFO-1132) or trifluoroethylene (HFO-1123).

4. The manufacturing method according to any one of claims 1 to 3, wherein the noble metal catalyst is a palladium catalyst.

5. The manufacturing method according to claim 4, wherein the hydrogenation dehalogenation step is carried out at a temperature of 200°C to 400°C.

6. The noble metal catalyst is carbon or alumina (Al ２ O ３ A manufacturing method according to any one of claims 1 to 3, wherein the carrier is supported on a carrier comprising ) 7. The manufacturing method according to claim 6, wherein the noble metal catalyst is supported in an amount of less than 10% by mass relative to the total of the noble metal catalyst and the carrier.

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