Method and apparatus for producing hexafluoropropylene oxide

Abstract

To provide a production method and a production device for hexafluoropropylene oxide that satisfy following conditions: (1) capability to continuous synthesize HFPO, (2) utilization of oxygen as an oxidative agent, (3) simplicity of the process, (4) assurance of safety, and (5) exclusive use of raw materials with minimal environmental impact.SOLUTION: A production method for hexafluoropropylene oxide causes a reaction to occur between hexafluoropropene with oxygen in a solvent containing a perfluoropolyether compound represented by the formula (1) within a tubular reactor at temperatures ranging from 100°C to 200°C, thereby continuously synthesizing hexafluoropropylene oxide.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for producing hexafluoropropylene oxide.

Background Art

[0002] Hexafluoropropylene oxide (hereinafter sometimes referred to as "HFPO") is a very important intermediate in the synthesis of fluorine-containing organic compounds. Specifically, it is used as a raw material for the synthesis of fluorine-containing polymers and perfluorovinyl ethers. Furthermore, oligomers of HFPO are widely used industrially as lubricating oils and heat transfer media. As a prior art relating to HFPO synthesis, Patent Document 1 (International Publication No. WO 2008 / 05760) reports a method of oxidizing hexafluoropropene (hereinafter sometimes referred to as "HFP") with hypochlorous acid in the presence of a phase transfer catalyst. Although this method can achieve a high yield of HFPO, it is difficult to regenerate the phase transfer catalyst, resulting in high production cost of HFPO.

[0003] As another method for producing HFPO, Patent Document 2 (Japanese Patent No. 5454567) reports that HFPO can be obtained in high yield by allowing a water-soluble aprotic organic solvent and an oxidant aqueous solution to flow into a micro space and bring them into contact with each other. In the method of Patent Document 2, hypohalite or hydrogen peroxide, which is more expensive than molecular oxygen, is used as an oxidant, and it is necessary to add an alkali to the aqueous oxidant solution in order to allow these substances to exist stably. As described above, in the method of Patent Document 2, since it is necessary to add an alkali to the aqueous oxidant solution, the production cost of HFPO is increased. In addition, the method of Patent Document 2 involves many steps and is a complicated process when industrialized.

[0004] Patent document 3 (Japanese Patent Publication No. 45-11683) reports a method for synthesizing HFPO using molecular oxygen, which is cheaper as an oxidizing agent, by epoxidizing HFP using Freon R-113 as a solvent. However, Freon R-113 is a "specified Freon" and can destroy the ozone layer, so it cannot be used at present.

[0005] Furthermore, Patent Document 4 (Japanese Patent Publication No. 2514384) reports a method for producing HFPO using a perfluoropolyether compound as a reaction solvent. Specifically, the method in Patent Document 4 involves charging a perfluoropolyether compound into an autoclave, raising the temperature using an electric furnace or heating bath, and then adding oxygen. While this method can achieve a high yield of HFPO using molecular oxygen, the reaction time is long; for example, in the example, the total reaction time for a 3L scale was 3.3 hours. In addition, the autoclave (batch reactor) used in the method in Patent Document 4 has a small heat transfer area per unit volume, resulting in a slow heat transfer rate. In the method in Patent Document 4, the heat transfer area per unit volume generally decreases as the scale (reactor size) increases. Therefore, it takes time to remove the heat generated by the reaction, resulting in a longer reaction time. Moreover, because it is a batch method, it cannot be said to be an industrially advantageous method. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2008 / 05760 [Patent Document 2] Patent No. 5454567 [Patent Document 3] Special Publication No. 45-11683 [Patent Document 4] Patent No. 2514384 [Overview of the project] [Problems that the invention aims to solve]

[0007] As described above, the present invention has been completed in view of the prior art, and aims to establish a method for manufacturing HFPO and a manufacturing apparatus that satisfies the following five conditions. (1) The ability to synthesize HFPO in succession. (2) Using oxygen as an oxidizing agent, (3) The process is simple. (4) It must be safe, (5) Use only raw materials that have minimal impact on the global environment. [Means for solving the problem]

[0008] In the method for producing hexafluoropropylene oxide according to this embodiment, hexafluoropropene and oxygen are reacted at a temperature of 100°C to 200°C in a solvent containing a perfluoropolyether compound represented by the following formula (1) in a tubular reaction vessel, to continuously synthesize hexafluoropropylene oxide. [ka] The apparatus for producing hexafluoropropylene oxide according to this embodiment is: A first tank filled with a solvent containing a perfluoropolyether compound represented by the following formula (1) in which hexafluoropropene is dissolved, A second tank filled with oxygen, A tubular reaction vessel made of stainless steel is used to react a solvent containing the perfluoropolyether compound in which hexafluoropropene, which is continuously supplied from the first tank, is dissolved, with oxygen, which is continuously supplied from the second tank, at a temperature of 100°C to 200°C. It is equipped with. [ka] [Effects of the Invention]

[0009] It is possible to provide a method and an apparatus for producing hexafluoropropylene oxide that satisfy the following conditions: (1) HFPO can be continuously synthesized; (2) oxygen is used as an oxidant; (3) the process is simple; (4) it is safe; and (5) only raw materials that have little impact on the global environment are used. [BRIEF DESCRIPTION OF THE DRAWINGS]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing one embodiment of the apparatus for producing hexafluoropropylene oxide according to the present invention. [Figure 2] FIG. 2 is a diagram showing the relationship between the reaction temperature of hexafluoropropene and oxygen and the selectivity for hexafluoropropylene oxide. [MODE FOR CARRYING OUT THE INVENTION]

[0011] <Production of hexafluoropropylene oxide> In the method for producing hexafluoropropylene oxide of the present invention, hexafluoropropene and oxygen are reacted at a temperature of 100°C or higher and 200°C or lower in a solvent containing a perfluoropolyether compound represented by the following formula (1) in a tubular reaction vessel, to continuously synthesize hexafluoropropylene oxide. [Chemical Formula]

[0012] Further, the reaction for obtaining hexafluoropropylene oxide (HFPO) by reacting hexafluoropropene (HFP) with oxygen is represented by the following formula (2). [Chemical Formula]

[0013] The present invention provides a method for producing hexafluoropropylene oxide that satisfies the following conditions: (1) continuous synthesis of HFPO, (2) use of oxygen as an oxidizing agent, (3) a simple process, (4) safety, and (5) use of only raw materials with minimal impact on the global environment. More specifically, since hexafluoropropylene oxide is obtained by the oxidation of hexafluoropropene with oxygen, HFPO can be synthesized continuously through a simple process. Furthermore, the solvent (perfluoropolyether compound) and raw materials (hexafluoropropene, oxygen) used are safe and have minimal impact on the global environment. The synthesis reaction of HFPO is a highly exothermic reaction, but the tubular reaction vessel has a large heat transfer surface area, allowing heat to be quickly dissipated, making it possible to carry out the synthesis reaction more safely. In addition, the carbonyl fluoride and trifluoroacetyl fluoride produced as by-products during the production of HFPO can both be used as raw materials for various fluorine compounds, thereby reducing production costs.

[0014] Figure 1 shows an example of an HFPO production apparatus 10 according to this embodiment. As shown in Figure 1, the HFPO production apparatus 10 comprises a first tank 1 filled with a solvent (perfluoropolyether compound) in which the raw material HFP is dissolved, and a second tank (cylinder) 2 filled with oxygen. The flow rates of the solvent and oxygen are adjusted by a plunger pump 7 and a mass flow controller 3 located downstream, respectively. The tubular reaction vessel 8 is immersed in an oil bath 4, and the reaction temperature of HFP and oxygen is adjusted in the oil bath 4, while the reaction pressure is adjusted by a back pressure valve 5. The solvent in which HFP is dissolved and oxygen are continuously supplied to the tubular reaction vessel 8 from the first tank 1 and the second tank 2, respectively, and the supplied raw materials react in the heating section of the tubular reaction vessel 8 at a temperature of 100°C to 200°C, synthesizing HFPO as the reaction product 6. Furthermore, in addition to the target substance HFPO, reaction product 6 may also contain by-products such as carbonyl fluoride, carbon dioxide, unreacted HFP, and oxygen.

[0015] In one embodiment, the synthesis reaction of HFPO is carried out, for example, by preparing a perfluoropolyether compound (solvent) in which HFP is dissolved beforehand, and oxidizing the HFP while continuously flowing the perfluoropolyether compound and oxygen through a tubular reaction vessel. By using a tubular reaction vessel, the heat transfer area per unit volume can be increased compared to a batch reactor (e.g., an autoclave). The synthesis reaction of HFPO is a reaction that generates a very large amount of heat, but because the heat transfer area of ​​the tubular reaction vessel is large, heat can be quickly dissipated, making it possible to carry out the synthesis reaction more safely. Furthermore, by arranging tubular reaction vessels in parallel, it becomes possible to mass-produce HFPO, and it is possible to increase the production volume of HFPO without performing scale-up, which is technically difficult. In the synthesis of HFPO, the perfluoropolyether compound represented by the aforementioned formula (1) (n=8~12) is used as the solvent. Compounds with a larger n number than this are widely used industrially as lubricants and heat transfer fluids, but currently there are not many applications for compounds with n numbers of 8~12. When producing perfluoropolyether compounds with a large n number, a certain amount of compounds with an n number of approximately 8 to 12 are produced as by-products. By using these as a solvent, HFPO can be produced at low cost. The solvent only needs to contain at least the perfluoropolyether compounds represented by formula (1) (n=8 to 12) as described above, and the solvent may further contain perfluoropolyether compounds in formula (1) where n=5 to 7 and 13 to 15. Furthermore, the perfluoropolyether compounds represented by formula (1) may be perfluoropolyether compounds represented by formula (1) having one n among n=8, 9, 10, 11, or 12, or they may be perfluoropolyether compounds represented by formula (1) having multiple ns within the range of n=8 to 12.

[0016] The synthesis of HFPO can generate highly corrosive gases and liquids. Therefore, it is preferable to use a tubular reaction vessel made of SUS (stainless steel), which has higher corrosion resistance. By using a tubular reaction vessel made of SUS, the HFPO synthesis reaction can be carried out stably for a long period of time without being affected by corrosion from these highly corrosive gases and liquids. The inner diameter of the tubular reaction vessel should preferably be 10 mm or less, as a smaller inner diameter allows for a larger heat transfer area per unit volume, and more preferably 5 mm or less, as this enables the safe production of HFPO. In one example of the present invention, a SUS316 pipe with an inner diameter of 2.17 mm and a length of 10 m is used as the tubular reaction vessel. The raw material flow rate in the tubular reaction vessel and the length of the reaction tube in the tubular reaction vessel can be set as appropriate.

[0017] HFPO can be continuously obtained by continuously supplying a perfluoropolyether compound (solvent) in which HFP has been pre-dissolved and oxygen to a tubular reaction vessel, and reacting HFP with oxygen under conditions such as a temperature of 100°C to 200°C and a predetermined pressure. Specifically, the reaction temperature during the synthesis of HFPO is 100°C to 200°C, but from the viewpoint of safety and yield, the reaction temperature is preferably 115°C to 180°C, and more preferably 130°C to 160°C. The reaction pressure during the synthesis of HFPO is preferably 1.0 MPa to 4.0 MPa, and from the viewpoint of safety, more preferably 1.8 MPa to 2.5 MPa. The reaction time during the synthesis of HFPO (residence time of raw materials in the heated section of the tubular reaction vessel) is preferably 5 minutes to 60 minutes, and from the viewpoint of yield, more preferably 10 minutes to 30 minutes. The amount of molecular oxygen supplied to HFP is preferably between 0.1 and 5.0 molar equivalents, more preferably between 0.5 and 3.0 molar equivalents from an economic and safety standpoint, and even more preferably between 0.8 and 2.0 molar equivalents. The amount of HFP supplied can be arbitrarily set so that the reaction time falls within a preferred range for the volume (reaction tube length, reaction tube diameter) of the tubular reaction vessel used.

[0018] Based on the embodiments described above, the present invention relates to the following [1] to [4]. [1] A method for producing hexafluoropropylene oxide, characterized by reacting hexafluoropropene and oxygen in a solvent containing a perfluoropolyether compound represented by the following formula (1) in a tubular reaction vessel at a temperature of 100°C to 200°C to continuously synthesize hexafluoropropylene oxide. [ka] [2] The method for producing hexafluoropropylene oxide according to [1] above, wherein the tubular reaction vessel is a tubular reaction vessel made of SUS. [3] The method for producing hexafluoropropylene oxide according to [1] or [2] above, wherein the inner diameter of the tubular reaction vessel is 10 mm or less. [4] A method for producing hexafluoropropylene oxide according to any one of [1] to [3] above, wherein hexafluoropropene and oxygen are reacted at a temperature of 115°C to 180°C. [5] A first tank filled with a solvent containing a perfluoropolyether compound represented by the following formula (1) in which hexafluoropropene is dissolved, A second tank filled with oxygen, A tubular reaction vessel made of stainless steel is used to react a solvent containing the perfluoropolyether compound in which hexafluoropropene, which is continuously supplied from the first tank, is dissolved, with oxygen, which is continuously supplied from the second tank, at a temperature of 100°C to 200°C. A apparatus for producing hexafluoropropylene oxide, equipped with [a specific feature / equipment]. [ka]

[0019] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and includes all aspects included in the concept and claims of the present invention, and can be modified in various ways within the scope of the present invention. [Examples]

[0020] Next, examples will be described to further clarify the effects of the present invention, but the present invention is not limited to these examples.

[0021] (Example 1) A SUS316 pipe with an inner diameter of 2.17 mm and a length of 10 m was used as a tubular reaction vessel. As shown in Figure 1, the HFP was first dissolved in a perfluoropolyether compound represented by the following formula (2) to prepare a solvent in which the HFP was dissolved. [ka] The solubility of HFP in the perfluoropolyether compound was 116 g / L. The solvent containing dissolved HFP and oxygen were continuously supplied from the inlet end of the tubular reaction vessel 8. The supply amount of the solvent containing dissolved HFP was controlled by a plunger pump 7, and the flow rate of oxygen was controlled by a mass flow controller 3. The tubular reaction vessel 8 was immersed in an oil bath 4 heated to 140°C, and the pressure inside the tubular reaction vessel 8 was controlled to 2.06 MPaG by a back pressure valve 5 installed at the outlet end of the tubular reaction vessel 8. At this time, the residence time of the raw materials in the heated section of the tubular reaction vessel 8 was 12.6 minutes. The outlet gas (reaction product) 6 from the tubular reaction vessel 8 was sampled, and the composition of the outlet gas was confirmed by gas chromatography. As a result, the HFP conversion rate was 58.2%, the HFPO selectivity was 24.0%, the carbonyl fluoride selectivity was 24.9%, and the trifluoroacetyl fluoride selectivity was 50.8%. The synthesis conditions for HFPO in Example 1 are shown in Table 1, and the results are shown in Table 2. Note that the "Yield" shown in Table 2 represents the value for HFPO obtained by multiplying the "Conversion Rate" and the "HFPO Selectivity". (Examples 2-21) The HFPO synthesis reaction was carried out in the same manner as in Example 1, except that the reaction temperature, reaction pressure, reaction time, HFP content, oxygen supply, etc., during the HFPO synthesis reaction were changed as shown in Table 1. The HFPO synthesis conditions for Examples 2 to 21 are shown in Table 1, and the results are shown in Table 2.

[0022] [Table 1] [Table 2]

[0023] As shown in Table 2, in Examples 1 to 21, it was confirmed that HFPO can be synthesized stably and continuously by the reaction of HFP with oxygen. Figure 2 shows the relationship between the reaction temperature of hexafluoropropene and oxygen and the selectivity of hexafluoropropylene oxide in Examples 1 to 11. As shown in Figure 2, it can be seen that a high HFPO selectivity can be achieved even when the reaction temperature of hexafluoropropene and oxygen is varied from 115°C to 180°C. Furthermore, from Figure 2, it can be seen that the HFPO selectivity is highest at 150°C, and that a reaction temperature of 130°C to 160°C is preferable. [Explanation of Symbols]

[0024] 1. First tank 2. Second tank 3 Mass Flow Controller 4. Oil Bath 5. Back pressure valve 6. Reaction Products 7. Plunger pump 8. Tubular reaction vessel 10. Hexafluoropropylene oxide production apparatus

Claims

1. A method for producing hexafluoropropylene oxide, characterized by reacting hexafluoropropene and oxygen in a solvent containing a perfluoropolyether compound represented by the following formula (1) in a tubular reaction vessel at a temperature of 130°C to 180°C to continuously synthesize hexafluoropropylene oxide. 【Chemistry 1】

2. The method for producing hexafluoropropylene oxide according to claim 1, wherein the tubular reaction vessel is a tubular reaction vessel made of SUS.

3. The method for producing hexafluoropropylene oxide according to claim 1 or 2, wherein the inner diameter of the tubular reaction vessel is 10 mm or less.

4. A first tank filled with a solvent containing a perfluoropolyether compound represented by the following formula (1) in which hexafluoropropene is dissolved, A second tank filled with oxygen, An apparatus for producing hexafluoropropylene oxide, comprising a stainless steel tubular reaction vessel for reacting a solvent containing the perfluoropolyether compound obtained by dissolving hexafluoropropene, which is continuously supplied from the first tank, with oxygen, which is continuously supplied from the second tank, at a temperature of 130°C to 180°C. 【Chemistry 2】

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