Method for producing fluoroethane

Abstract

To provide a method for producing hydrofluoroethane in high selectivity by using hydrochlorofluoroethane as a raw material.SOLUTION: A method for producing a fluoroethane represented by the following general formula (1): CH2X1CHX2X3 (1), (Wherein 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.) and comprising a step A of obtaining the fluoroethane from a chlorofluoroethane represented by the following general formula (2): CX4ClFCX5X6X7 (2), (Wherein X4, X5, X6 and X7 each independently represent a hydrogen atom, a fluorine atom or a chlorine atom, and at least one of X5, X6 and X7 represents a hydrogen atom) in the presence of a catalyst.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a process for producing fluoroethane. [Background technology]

[0002] Fluoroethanes, such as 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 technology 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) 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, there is no disclosure of a method for obtaining hydrofluoroethane from hydrochlorofluorocarbons (hereinafter also simply referred to as "HCFCs" in this specification). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 4-117333 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[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. Section 1. The following general formula (1) CH2X 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 At least one of the groups represents a fluorine atom. A method for producing fluoroethane represented by the formula: In the presence of a catalyst, 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 5 , X 6 and X 7 wherein at least one of the fluoroethane groups represents a hydrogen atom. Section 2. Item 1. 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. Section 3. Item 3. The method according to Item 1 or 2, wherein the catalyst is supported on a support, and the support is a carbon-based support. Section 4. 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). Section 5. 5. The method according to any one of items 1 to 4, wherein the chlorofluoroethane is 1,2-dichloro-1,1,2-trifluoroethane (HCFC-123a) or 1,1-dichloro-1,2,2-trifluoroethane (HCFC-123b). Section 6. 6. The method according to any one of items 1 to 5, wherein in step A, a hydrogenation reaction is carried out. Section 7. Item 7. 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. Section 8. Item 8. The method according to Item 6 or 7, wherein the hydrogenation reaction is carried out by adding hydrogen to the chlorofluoroethane in a molar ratio of H2 / chlorofluoroethane of 1 to 20. Section 9. Item 9. The method according to any one of Items 6 to 8, wherein the hydrogenation reaction is carried out in a gas phase. Section 10. Item 10. A method for producing a fluoroolefin, further comprising a step B of subjecting the fluoroethane obtained by the production method according to any one of items 1 to 9 to a dehydrofluorination reaction to obtain a fluoroolefin. [Effects of the Invention]

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

[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 according to the present disclosure comprises reacting fluoroethane represented by the following general formula (1): CH2X 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 At least one of the groups represents a fluorine atom. This is a method for producing fluoroethane represented by the formula:

[0012] The method for producing fluoroethane according to the present disclosure comprises reacting a compound represented by the following general formula (2) in the presence of a catalyst: 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 5 , X 6 and X 7 wherein at least one of the groups 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 in 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 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 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 simultaneously. When multiple fluoroethanes are produced simultaneously, it is also preferable to separate the fluoroethanes into individual 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 1,2-dichloro-1,1,2-trifluoroethane (HCFC-123a), 1,1-dichloro-1,2,2-trifluoroethane (HCFC-123b), and 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113). These may be used alone or in combination. For example, it is a preferred embodiment to use only one of HCFC-123a or HCFC-123b alone, or to use a mixture of HCFC-123a and HCFC-123b.

[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 carrying out the hydrogenation reaction in step A, the amount of hydrogen added to the chlorofluoroethane represented by formula (2) is preferably an H2 / chlorofluoroethane molar ratio of 1 or more, more preferably 2 or more, even more preferably 3 or more, and particularly preferably 5 or more. Furthermore, 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. By setting the H2 / chlorofluoroethane ratio at or above the lower limit, it is possible to suppress a decrease in catalyst activity and improve the selectivity for the target product. On the other hand, by setting the ratio at or below the upper limit, 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 also preferably 350°C or lower, more preferably 320°C or lower. By setting the temperature at or above the lower limit, it is possible to obtain a suitable raw material conversion rate and target product selectivity. On the other hand, by setting the temperature at or below the upper limit, it is possible to suppress the progression of side reactions and to suppress catalyst deterioration, thereby improving the yield.

[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 flowing into the reaction system, expressed by Equation (2), is F (cc / sec). The contact time, expressed as W / F, is preferably 0.1 (g sec / cc) or more, more preferably 0.5 (g sec / cc) or more, and even more preferably 1.0 (g sec / cc) or more. Furthermore, the contact time is preferably 20 (g sec / cc) or less, more preferably 15 (g sec / cc) or less, and even more preferably 10 (g sec / cc) or less. By setting the contact time within this 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] [ka]

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

[0028] (2. Method for producing fluoroolefins) The method for producing a fluoroolefin according to the present disclosure includes a step of obtaining a fluoroolefin by dehydrofluorination 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 according to the present disclosure, a fluoroolefin represented by the following general formula (1) is used. CH2X 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 At least one of the groups represents a fluorine atom. By subjecting fluoroethane represented by the following general formula (3) to dehydrofluorination reaction, CX 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 , X 9 , X 10 and X 11 At least one of the X represents a hydrogen atom, 8 , X 9 , X 10 and X 11 At least one of the groups represents a fluorine atom. A fluoroolefin represented by the formula:

[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. CF2HCFH2 → 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, alumina (Al2O3), zirconia (ZrO2), silica (SiO2), and titania (TiO2). 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, for example, 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 range of known conditions can be used. The dehydrofluorination reaction can be carried out in the presence of either an inert gas or air. Inert gases that can be used include helium, nitrogen, argon, and the like, as well as fluorocarbons and hydrofluorocarbons such as HFC-23, FC-14, FC-116, HFC-152a, and HFC-161, 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 can 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. [Example]

[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 A 0.2 kg amount 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 by nitrogen purging. The reactor temperature was then set to 200°C, and a reduction reaction was carried out by supplying HCFC-123a at 2.7 g / min and hydrogen at 3600 Nml / min. The W / F0 ratio was 3, and the H2 / HCFC-123a molar ratio was 9. The outlet gas was washed with water, dried over calcium chloride, and analyzed by GC (Shimadzu GC-2030). A high yield of HFC-143 was obtained (HCFC-123a conversion: 28.8%, selectivity for HFC-143 and useful products convertible to HFC-143: 95.6%).

[0045] Example 2 A 0.2 kg amount 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 by nitrogen purging. The reactor temperature was then set to 250°C, and a reduction reaction was carried out by supplying HCFC-123a at 2.7 g / min and hydrogen at 3600 Nml / min. The W / F0 ratio was 3, and the H2 / HCFC-123a molar ratio was 9. The outlet gas was washed with water, dried over calcium chloride, and analyzed by GC (Shimadzu GC-2030). A high yield of HFC-143 was obtained (HCFC-123a conversion: 70.4%, selectivity to HFC-143 and useful products convertible to HFC-143: 97.6%).

[0046] Example 3 A 0.2 kg amount 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 by nitrogen purging. The reactor temperature was then set to 300°C, and a reduction reaction was carried out by supplying HCFC-123a at 2.7 g / min and hydrogen at 3600 Nml / min. The W / F0 ratio was 3, and the H2 / HCFC-123a molar ratio was 9. The outlet gas was washed with water, dried over calcium chloride, and analyzed by GC (Shimadzu GC-2030). A high yield of HFC-143 was obtained (HCFC-123a conversion: 98.7%, selectivity for HFC-143 and useful products convertible to HFC-143: 98.3%).

[0047] The results of Examples 1 to 3 above are summarized in Table 1 below.

[0048] [Table 1]

Claims

1. 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 At least one of the groups represents a fluorine atom. A method for producing fluoroethane represented by the formula: In the presence of a catalyst, 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 ５ , X ６ and X ７ wherein at least one of the fluoroethane groups represents a hydrogen atom.

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

3. The method according to claim 1 or 2, wherein the catalyst is supported on a support, the support being a carbon-based support.

4. 3. The method according to 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. 3. The method according to claim 1, wherein the chlorofluoroethane is 1,2-dichloro-1,1,2-trifluoroethane (HCFC-123a) or 1,1-dichloro-1,2,2-trifluoroethane (HCFC-123b).

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°C or higher and 350°C or lower.

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

9. 7. 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 a 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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