Method for producing fluoroethane

Abstract

Provided is a method for producing fluoroethane represented by general formula (1), namely, CH2X1CHX2X3 (in formula 1, X1, X2, and X3 each independently represent a hydrogen atom or a fluorine atom, and at least one of X1, X2, and X3 represents a fluorine atom), wherein the method includes a step A in which the fluoroethane is obtained in the presence of a catalyst from chlorofluoroethane represented by general formula (2), namely, CX4CIFCX5X6X7 (in formula (2), X4, X5, X6, and X7 each independently represent a hydrogen atom, a fluorine atom, or a chlorine atom, and at least one of X4, X5, X6, and X7 represents a hydrogen atom).

Description

Fluoroethane production method

[0001] The present invention relates to a process for producing fluoroethane.

[0002] Fluoroethanes, typified by 1,1,2-trifluoroethane (hereinafter also referred to simply as "HFC-143" in this specification), are known as raw materials for producing various refrigerants. Various methods have been proposed for producing fluoroethanes such as HFC-143.

[0003] For example, Patent Document 1 proposes a technique for producing chlorotrifluoroethylene or trifluoroethylene by hydrogenation of 1,1,2-trichloro-1,2,2-trifluoroethylene (hereinafter also simply referred to as "CFC-113" in this specification) or the like in the presence of a hydrogenation catalyst.

[0004] However, when producing fluoroethanes such as HFC-143 by the method disclosed in Patent Document 1, there is a problem in that the selectivity to the target product is low. Moreover, Patent Document 1 does not disclose a method for obtaining hydrofluoroethane from hydrochlorofluorocarbons (hereinafter also simply referred to as "HCFCs" in this specification).

[0005] Japanese Patent Publication No. 4-117333

[0006] In view of the above circumstances, an object of the present disclosure is to provide a method for obtaining hydrofluoroethane with high selectivity using hydrochlorofluoroethane as a raw material.

[0007] As a result of intensive research aimed at solving the above problems, the present inventors have found that fluoroethane can be obtained in high yield by using a catalyst. Based on this finding, the present inventors have conducted further research and have completed the present disclosure.

[0008] That is, the present disclosure provides the following method for producing fluoroethane: Item 1. A method for producing fluoroethane represented by the following general formula (1): CH ２ X １ CHX ２ X ３ (1) [In formula (1), X １ , X ２ , and X３ each independently represents a hydrogen atom or a fluorine atom; X １ , X ２ , and X ３ wherein at least one of the formulas represents a fluorine atom, and ４ ClFCX ５ X ６ X ７ (2) [In formula (2), X ４ , X ５ , X ６ and X ７ each independently represents a hydrogen atom, a fluorine atom, or a chlorine atom; X ４ , X ５ , X ６ and X ７ wherein at least one of the formulae represents a hydrogen atom. Item 2. A method for producing fluoroethane, comprising step A of obtaining the fluoroethane from a chlorofluoroethane represented by the formula:

[0023] Item 2. The method according to item 1, wherein the catalyst is at least one selected from the group consisting of Ni, Pd, Pt, Rh, and Ru. Item 3. The method according to item 1 or 2, wherein the catalyst is supported on a carrier, and the carrier is a carbon-based carrier. Item 4. The method according to any one of items 1 to 3, wherein the fluoroethane is 1,1,2-trifluoroethane (HFC-143), 1,1-difluoroethane (HFC-152a), 1,2-difluoroethane (HFC-152), or fluoroethane (HFC-161). Item 5. Item 6. The method according to any one of Items 1 to 4, wherein the chlorotrifluoroethane is 2-chloro-1,1,2-trifluoroethane (HCFC-133) or 1-chloro-1,1,2-trifluoroethane (HCFC-133b). Item 7. The method according to Item 6, wherein a hydrogenation reaction is carried out in Step A. Item 8. The method according to Item 6, wherein the hydrogenation reaction is carried out at a temperature of 150° C. or higher and 350° C. or lower. Item 9. The hydrogenation reaction is carried out by reacting hydrogen with the chlorotrifluoroethane, ２Item 6. The method of Item 6 or 7, wherein the hydrogenation reaction is carried out by adding fluoroethane / chlorotrifluoroethane in a molar ratio of 1 to 20. Item 9. The method of any of Items 6 to 8, wherein the hydrogenation reaction is carried out in a gas phase. Item 10. A method for producing a fluoroolefin, further comprising a step B of subjecting the fluoroethane obtained by the production method of any of Items 1 to 9 to a dehydrofluorination reaction to obtain a fluoroolefin.

[0009] According to the method for producing fluoroethane according to the present disclosure, fluoroethane can be obtained in high yield.

[0010] In this specification, the term "containing" is a concept that encompasses all of "comprise," "consist essentially of," and "consist only of."

[0011] (1. Method for Producing Fluoroethane) The method for producing fluoroethane of the present disclosure comprises reacting a compound represented by the following general formula (1): CH ２ X １ CHX ２ X ３ (1) [In formula (1), X １ , X ２ , and X ３ each independently represents a hydrogen atom or a fluorine atom; X １ , X ２ , and X ３ wherein at least one of the formulae represents a fluorine atom.

[0012] The method for producing fluoroethane according to the present disclosure comprises reacting a compound represented by the following general formula (2): CX ４ ClFCX ５ X ６ X ７ (2) [In formula (2), X ４ , X ５ , X ６ and X ７ each independently represents a hydrogen atom, a fluorine atom, or a chlorine atom; X ４ , X ５ , X ６ and X ７wherein at least one of the fluoroethanes represents a hydrogen atom.

[0013] The above step A is carried out as a hydrogenation reaction, preferably in a reactor in the presence of a catalyst. A common raw material is used as the hydrogenation agent. In addition to hydrogen gas, hydrogenation agents such as hydrazine can also be used, but hydrogen gas is preferably used.

[0014] As the catalyst, it is preferable to use a metal catalyst, more preferably Ni, Pd, Pt, Rh or Ru, and particularly preferably Pd.

[0015] Furthermore, it is more preferable that the catalyst is used by being supported on a carrier. A wide variety of known carriers can be used as such a carrier, and there are no particular limitations. Examples of constituent materials of the single substance include carbon-based materials such as activated carbon, amorphous carbon, graphite, and diamond, porous aluminosilicates such as zeolites, aluminophosphates, aluminum oxide, silicon oxide, titanium oxide, zirconia oxide, zinc oxide, and aluminum fluoride. These may be used alone or in combination. Among these, it is preferable to use the above-mentioned carbon-based materials to form a carbon-based carrier.

[0016] The amount of metal supported on the catalyst is preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more, where the total mass of the support and the metal is taken as 100% by mass. Also, the mass of the catalyst is preferably 5% by mass or less, more preferably 4% by mass or less, where the total mass of the support and the catalyst is taken as 100% by mass.

[0017] The catalyst preparation method is not particularly limited, and a wide variety of known preparation methods can be used. For example, a catalyst in which a precious metal is supported on a carrier can be obtained by immersing the carrier in a solution containing the precious metal to impregnate the carrier with the solution, and then, as necessary, neutralizing, drying, calcining, etc. In this case, the amount of precious metal supported on the carrier can be controlled by adjusting the concentration of the solution, the impregnation time, etc.

[0018] The fluoroethane represented by the above formula (1) is preferably 1,1,2-trifluoroethane (HFC-143), 1,1-difluoroethane (HFC-152a), 1,2-difluoroethane (HFC-152), or fluoroethane (HFC-161). The production method of the present disclosure can produce only one of these fluoroethanes, or multiple fluoroethanes can be produced simultaneously. When multiple fluoroethanes are produced simultaneously, it is also preferable to separate them into individual fluoroethane components using a fractionator or the like.

[0019] Furthermore, the chlorofluoroethane represented by the above formula (2) is not particularly limited, and examples thereof include 1-chloro-1,1,2-trifluoroethane (HCFC-133b), 1-chloro-1,2,2-trifluoroethane (HCFC-133), and 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113). These may be used alone or in combination as a mixture of two or more. For example, it is also a suitable embodiment to use only HCFC-133b alone or to use a mixture of HCFC-133 and HCFC-133b in combination.

[0020] The reaction carried out in step A is not particularly limited as long as it is a reaction that can replace a fluorine atom or chlorine atom bonded to a carbon atom in fluoroethane with a hydrogen atom. Specifically, it is preferable to carry out a hydrogenation reaction.

[0021] When the hydrogenation reaction is carried out in step A, the amount of hydrogen added to the chlorofluoroethane represented by formula (2) is H ２The molar ratio of H to chlorofluoroethane is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and particularly preferably 5 or more. The molar ratio is preferably 20 or less, more preferably 18 or less, even more preferably 15 or less, and particularly preferably 13 or less. ２ By setting the ratio of chlorofluoroethane to the lower limit or more, it is possible to suppress the decrease in catalytic activity and improve the yield, while by setting the ratio to the upper limit or less, it is possible to suppress the generation of excess hydrogen and improve the reaction efficiency and yield.

[0022] In this case, the temperature condition for progressing the hydrogenation reaction is preferably 150°C or higher, more preferably 180°C or higher. The temperature condition is preferably 350°C or lower, more preferably 320°C or lower. By setting the temperature at or above the lower limit, a suitable raw material conversion rate and target product selectivity can be obtained. On the other hand, by setting the temperature at or below the upper limit, the progression of side reactions can be suppressed, catalyst deterioration can be suppressed, and the yield can be improved.

[0023] When carrying out a hydrogenation reaction, the catalyst loading (mass) in the reaction system is W (g), and the total flow rate of chlorofluoroethane and hydrogen gas expressed by formula (2) flowing into the reaction system is F (cc / sec). The contact time expressed as W / F0 is preferably 0.1 (g sec / cc) or more, more preferably 0.5 or more (g sec / cc), and even more preferably 1.0 or more (g sec / cc). Furthermore, the contact time is preferably 20 or less (g sec / cc), more preferably 15 or less (g sec / cc), and even more preferably 10 or less (g sec / cc). By setting the contact time within this numerical range, high conversion and selectivity can be obtained, resulting in an efficient process.

[0024] In the reaction of step A, the reaction system may contain compounds other than the chlorofluoroethane represented by formula (2), such as chlorotrifluoroethylene (CTFE) and / or 1,1,2-trifluoroethylene (HFO-1123).

[0025] The reaction in the above step A proceeds, for example, according to the following reaction formula 1.

[0026]

[0027] In the above reaction scheme, both HCFC-133 and HCFC-133b can be converted to HFC-143, and it is shown that the production of any useful product that can be converted to these target products can contribute to improving the selectivity.

[0028] (2. Method for Producing Fluoroolefin) The method for producing a fluoroolefin according to the present disclosure includes a step of obtaining a fluoroolefin by a dehydrofluorination reaction of fluoroethane obtained by the above-described method for producing fluoroethane. Hereinafter, this step is defined as step B in this specification.

[0029] In the method for producing a fluoroolefin of the present disclosure, a fluoroolefin represented by the following general formula (1): CH ２ X １ CHX ２ X ３ (1) [In formula (1), X １ , X ２ , and X ３ each independently represents a hydrogen atom or a fluorine atom; X １ , X ２ , and X ３ wherein at least one of the fluoroethanes represents a fluorine atom. ８ X ９ =CX １０ X １１ (3) [In formula (3), X ８ , X ９ , X １０ and X １１ are the same or different and represent a hydrogen atom, a fluorine atom or a chlorine atom; X ８ , X９ , X １０ and X １１ At least one of X represents a hydrogen atom; ８ , X ９ , X １０ and X １１ at least one of which represents a fluorine atom] can be obtained.

[0030] In step B, the method for the dehydrofluorination reaction is not particularly limited, and for example, the dehydrofluorination reaction can be carried out under the same conditions as those for known dehydrofluorination reactions. For example, the dehydrofluorination reaction can be carried out in the gas phase in the presence of a dehydrofluorination catalyst.

[0031] In the fluoroolefin production method of the present disclosure, when 1,1,2-trifluoroethane (HFC-143) is used as the fluoroethane, the dehydrofluorination reaction follows the following reaction formula: CF ２ HCFH ２ → CHF=CHF + HF

[0032] The dehydrofluorination catalyst is not particularly limited, and a wide variety of known catalysts can be used, including, for example, chromium oxide, chromium oxide fluoride, aluminum oxide, and aluminum oxide fluoride.

[0033] The dehydrofluorination catalyst is preferably supported on a carrier. Examples of the carrier include carbon and alumina (Al ２ O ３ ), zirconia (ZrO ２ ), silica (SiO ２ ), titania (TiO ２ Examples of carbon that can be used include activated carbon, amorphous carbon, graphite, and diamond.

[0034] The dehydrofluorination reaction in step B can also be carried out in the presence of an oxidizing agent. Examples of the oxidizing agent include oxygen, chlorine, bromine, and iodine, with oxygen being particularly preferred. The concentration of the oxidizing agent is not particularly limited and can be the same as that used in known dehydrofluorination reactions.

[0035] The reaction temperature of the dehydrofluorination reaction is not particularly limited and can be the same as that of known dehydrofluorination reactions, and can be, for example, 300° C. or higher, preferably 320° C. or higher, more preferably 340° C. or higher, and particularly preferably 350° C. or higher. The reaction temperature of the dehydrofluorination reaction can be 600° C. or lower, preferably 550° C. or lower, more preferably 500° C. or lower, and particularly preferably 450° C. or lower.

[0036] The reaction time and pressure during the dehydrofluorination reaction are not particularly limited, and a wide variety of known conditions can be used. The dehydrofluorination reaction can be carried out in the presence of either an inert gas or air. Examples of inert gases that can be used include helium, nitrogen, and argon, as well as fluorocarbons and hydrofluorocarbons such as HFC-23, FC-14, and FC-116, which are fluorine compounds that do not participate in the reaction. The dehydrofluorination reaction can be carried out either continuously or batchwise.

[0037] The method for producing a fluoroolefin according to the present disclosure may include other steps as necessary in addition to step B. In the method for producing a fluoroolefin according to the present disclosure, raw materials can also be separated from the crude product obtained by the production method and recycled.

[0038] The target fluoroolefin, for example, a compound represented by general formula (4), can be obtained by carrying out step B. The fluoroolefin obtained by the dehydrofluorination step may be one or more types.

[0039] The resulting fluoroolefin may depend on the fluoroethane used in the dehydrofluorination step. Examples of fluoroolefins include 1,2-difluoroethylene (HFO-1132), 1,1-difluoroethylene (HFO-1132a), and trifluoroethylene (HFO-1123).

[0040] In the fluoroolefin production method of the present disclosure, when HFC-143 is used as the fluoroethane, the resulting fluoroolefin is HFO-1132. In Production Method 2 of the present disclosure, when HFC-143a is used as the fluoroethane, the resulting fluoroolefin is HFO-1132a. In the fluoroolefin production method of the present disclosure, when HFC-134 is used as the fluoroethane, the resulting fluoroolefin is HFO-1123. HFO-1132 may include trans-1,2-difluoroethylene [(E)-HFO-1132] and cis-1,2-difluoroethylene [(Z)-HFO-1132].

[0041] When a fluoroolefin is obtained by the above-described method for producing a fluoroolefin according to the present disclosure, the above-described method for producing a fluoroethane according to the present disclosure and the method for producing a fluoroolefin according to the present disclosure may be carried out continuously or independently.

[0042] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to these examples and can, of course, be embodied in various forms without departing from the spirit of the present disclosure.

[0043] Hereinafter, the embodiments of the present disclosure will be described more specifically based on examples, but the present disclosure is not limited to these examples.

[0044] Example 1: 0.2 kg of activated carbon catalyst supporting 2% by mass of Pd was packed into a Hastelloy C reactor tube with an inner diameter of 50 mm and dried at 250°C for 3 hours with nitrogen purging. The reactor temperature was then set to 200°C, and a reduction reaction was carried out by supplying HCFC-133b at 2.1 g / min and hydrogen at 3600 Nml / min. The W / F0 ratio was 3, and the H2 / HCFC-133b molar ratio was 9. The outlet gas was washed with water, dried over calcium chloride, and analyzed by GC (Shimadzu GC-2030). HFC-143 was obtained in high yield (HCFC-133b conversion: 11.5%, HFC-143 selectivity: 96%).

[0045] Example 2: 0.2 kg of activated carbon catalyst supporting 2% by mass of Pd was packed into a Hastelloy C reactor tube with an inner diameter of 50 mm and dried at 250°C for 3 hours with nitrogen purging. The reactor temperature was then set to 300°C, and a reduction reaction was carried out by supplying HCFC-133b at 2.1 / min and hydrogen at 3600 Nml / min. The W / F0 ratio was 3, and the H2 / HCFC-133b molar ratio was 9. The outlet gas was washed with water, dried over calcium chloride, and analyzed by GC (Shimadzu GC-2030). HFC-143 was obtained in high yield (HCFC-133b conversion: 57.2%, HFC-143 selectivity: 97%).

[0046] Example 3: 0.2 kg of activated carbon catalyst supporting 2% by mass of Pd was packed into a Hastelloy C reactor tube with an inner diameter of 50 mm and dried at 200°C for 3 hours with nitrogen purging. The reactor temperature was then set to 300°C, and a reduction reaction was carried out by supplying HCFC-133b at 3.0 g / min and hydrogen at 3430 Nml / min. The W / F0 ratio was 3, and the H2 / HCFC-133b molar ratio was 6. The outlet gas was washed with water, dried over calcium chloride, and analyzed by GC (Shimadzu GC-2030). HFC-143 was obtained in high yield (HCFC-133b conversion: 50.0%, HFC-143 selectivity: 97%).

[0047] Example 4: 0.2 kg of activated carbon catalyst supporting 2% by mass of Pd was packed into a Hastelloy C reactor tube with an inner diameter of 50 mm and dried at 200°C for 3 hours with nitrogen purging. The reactor temperature was then set to 300°C, and a reduction reaction was carried out by supplying HCFC-133b at 1.6 g / min and hydrogen at 3690 Nml / min. The W / F0 ratio was 3, and the H2 / HCFC-133b molar ratio was 12. The outlet gas was washed with water, dried over calcium chloride, and analyzed by GC (Shimadzu GC-2030). HFC-143 was obtained in high yield (CFC-133b conversion: 66.6%, HFC-143 selectivity: 98%).

[0048] Example 5: 0.2 kg of activated carbon catalyst supporting 2% by mass of Pd was packed into a Hastelloy C reactor tube with an inner diameter of 50 mm and dried at 200°C for 3 hours with nitrogen purging. The reactor temperature was then set to 300°C, and a reduction reaction was carried out by supplying HCFC-133b at 4.2 g / min and hydrogen at 7200 Nml / min. The W / F0 ratio was 1.5, and the H2 / HCFC-133b molar ratio was 9. The outlet gas was washed with water, dried over calcium chloride, and analyzed by GC (Shimadzu GC-2030). HFC-143 was obtained in high yield (CFC-113 conversion: 42.9%, HFC-143 selectivity: 97%).

[0049] Example 6: 0.2 kg of activated carbon catalyst supporting 2% by mass of Pd was packed into a Hastelloy C reactor tube with an inner diameter of 50 mm and dried at 200°C for 3 hours with nitrogen purging. The reactor temperature was then set to 300°C, and a reduction reaction was carried out by supplying HCFC-133b at 1.1 g / min and hydrogen at 1800 Nml / min. The W / F0 ratio was 6, and the H2 / HCFC-133b molar ratio was 9. The outlet gas was washed with water, dried over calcium chloride, and analyzed by GC (Shimadzu GC-2030). HFC-143 was obtained in high yield (CFC-113 conversion: 70.8%, HFC-143 selectivity: 96%).

[0050] Example 7: 0.2 kg of activated carbon catalyst supporting 2% by mass of Pt was packed into a Hastelloy C reactor tube with an inner diameter of 50 mm and dried at 250°C for 3 hours with nitrogen purging. The reactor temperature was then set to 300°C, and a reduction reaction was carried out by supplying HCFC-133b at 2.1 g / min and hydrogen at 3600 Nml / min. The W / F0 ratio was 3, and the H2 / HCFC-133b molar ratio was 9. The outlet gas was washed with water, dried over calcium chloride, and analyzed by GC (Shimadzu GC-2030). HFC-143 was obtained in high yield (HCFC-133b conversion: 55.0%, HFC-143 selectivity: 66%).

[0051] Example 8: 0.2 kg of activated carbon catalyst supporting 2% by mass of Rh was packed into a Hastelloy C reactor tube with an inner diameter of 50 mm and dried at 250°C for 3 hours with nitrogen purging. The reactor temperature was then set to 300°C, and a reduction reaction was carried out by supplying HCFC-133b at 2.1 g / min and hydrogen at 3600 Nml / min. The W / F0 ratio was 3, and the H2 / HCFC-133b molar ratio was 9. The outlet gas was washed with water, dried over calcium chloride, and analyzed by GC (Shimadzu GC-2030). HFC-143 was obtained in high yield (HCFC-133b conversion: 85.7%, HFC-143 selectivity: 85%).

[0052] The above results are summarized in Table 1 below.

[0053]

Claims

1. A compound represented by the following general formula (1): CH ２ X １ CHX ２ X ３ (1) [In formula (1), X １ , X ２ , and X ３ each independently represents a hydrogen atom or a fluorine atom; X １ , X ２ , and X ３ wherein at least one of the formulas represents a fluorine atom, and ４ ClFCX ５ X ６ X ７ (2) [In formula (2), X ４ , X ５ , X ６ and X ７ each independently represents a hydrogen atom, a fluorine atom, or a chlorine atom; X ４ , X ５ , X ６ and X ７ wherein at least one of the fluoroethane groups represents a hydrogen atom.

2. The method according to claim 1, wherein the catalyst is at least one selected from the group consisting of Ni, Pd, Pt, Rh and Ru.

3. The method of claim 1, wherein the catalyst is supported on a support, the support being a carbon-based support.

4. The method of claim 1 or 2, wherein the fluoroethane is 1,1,2-trifluoroethane (HFC-143), 1,1-difluoroethane (HFC-152a), 1,2-difluoroethane (HFC-152) or fluoroethane (HFC-161).

5. The method of claim 1 or 2, wherein the chlorotrifluoroethane is 2-chloro-1,1,2-trifluoroethane (HCFC-133) or 1-chloro-1,1,2-trifluoroethane (HCFC-133b).

6. The method according to claim 1 or 2, wherein in step A, a hydrogenation reaction is carried out.

7. The method according to claim 6, wherein the hydrogenation reaction is carried out at a temperature of 150 to 350°C.

8. The hydrogenation reaction is carried out by adding hydrogen to the chlorotrifluoroethane. ２ The method according to claim 6, wherein the method is carried out by adding chlorotrifluoroethane in a molar ratio of 1 to 20.

9. The method of claim 6, wherein the hydrogenation reaction is carried out in the gas phase.

10. A method for producing a fluoroolefin, further comprising step B of subjecting the fluoroethane obtained by the method according to claim 1 or 2 to a dehydrofluorination reaction to obtain a fluoroolefin.

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