Method for producing hexafluoropropene and composition

Abstract

To provide a method for producing hexafluoropropene in which the formation of octafluorocyclobutane, a by-product, is suppressed, and a composition obtained by the said production method. [Solution] A method for producing hexafluoropropene, comprising preheating trifluoromethane at a first preheating temperature of 350 to 700°C, then contacting it with tetrafluoroethylene to obtain a product containing hexafluoropropene.

Description

[Technical Field]

[0001] This disclosure relates to methods and compositions for producing hexafluoropropene. [Background technology]

[0002] Hexafluoropropene is a compound used as a raw material for fluororesins and the like, and can be obtained, for example, by the thermal decomposition reaction of trifluoromethane and tetrafluoroethylene. Hereinafter, hexafluoropropene will also be referred to as "HFP," trifluoromethane as "R23," and tetrafluoroethylene as "TFE." For example, Patent Document 1 discloses a method for producing HFP by mixing R23 and TFE in an R23 / TFE molar ratio of 0.25 to 10 and thermally decomposing it at a temperature range of 750 to 950°C and a residence time of 0.1 to 5 seconds. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] U.S. Patent No. 06403848 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] When attempting to obtain HFP through the reaction of R23 and TFE, octafluorocyclobutane may also be produced as a by-product. Hereafter, octafluorocyclobutane will also be referred to as "C318". Since C318 has a high global warming potential (GWP), it is desirable to minimize the amount of C318 produced in HFP manufacturing.

[0005] One aspect of this disclosure aims to provide a method for producing hexafluoropropene in which the formation of octafluorocyclobutane, a by-product, is suppressed, and a composition obtained by said production method. [Means for solving the problem]

[0006] This disclosure includes the following aspects: <1> A method for producing hexafluoropropene, comprising preheating trifluoromethane at a first preheating temperature of 350-700°C, then contacting it with tetrafluoroethylene to obtain a product containing hexafluoropropene. <2> The trifluoromethane preheated at the first preheating temperature is mixed with a second preheating heat transfer medium heated at a second preheating heat transfer medium heating temperature higher than the first preheating temperature, and this mixture is brought into contact with the tetrafluoroethylene. <1> A method for producing hexafluoropropene as described in [reference]. <3> The heating temperature of the second preheating heat transfer medium is 1100°C or lower. <2> A method for producing hexafluoropropene as described in [reference]. <4> The amount of the second preheating heat transfer medium added is 50 mol% or less of the total amount of the tetrafluoroethylene, the trifluoromethane preheated at the first preheating temperature, and the second preheating heat transfer medium. <2> or <3> A method for producing hexafluoropropene as described in [reference]. <5> The contact is carried out by mixing trifluoromethane preheated at the first preheating temperature, a reaction heat medium heated at a reaction heat medium heating temperature higher than the first preheating temperature, and the tetrafluoroethylene. <1> A method for producing hexafluoropropene as described in [reference]. <6> The heating temperature of the reaction medium is 1100°C or lower. <5> A method for producing hexafluoropropene as described in [reference]. <7> The amount of the reaction heat transfer medium added is 50 mol% or less of the total amount of the tetrafluoroethylene, the trifluoromethane preheated at the first preheating temperature, and the reaction heat transfer medium. <5> or <6> A method for producing hexafluoropropene as described in [reference]. <8> The method further includes heating a mixture obtained by contacting trifluoromethane preheated at the first preheating temperature with tetrafluoroethylene in a reactor at a reaction temperature of 800 to 1000°C. <1> ~ <7> A method for producing hexafluoropropene as described in any one of the above. <9> The heating time at the aforementioned reaction temperature is 5 seconds or less. <8> A method for producing hexafluoropropene as described in [reference]. <10> The gauge pressure inside the reactor is 0 kPaG or more and less than 200 kPaG. <8> or <9> A method for producing hexafluoropropene as described in [reference]. <11> The product further comprises octafluorocyclobutane, The ratio of the molar amount of hexafluoropropene contained in the product to the molar amount of octafluorocyclobutane contained in the product is 5 or more. <1> ~ <10> A method for producing hexafluoropropene as described in any one of the above. <12> The product further comprises perfluoroisobutene, The ratio of the molar amount of hexafluoropropene contained in the product to the molar amount of perfluoroisobutene contained in the product is 0.9 or greater. <1> ~ <11> A method for producing hexafluoropropene as described in any one of the above. <13> A composition comprising trifluoromethane, tetrafluoroethylene, hexafluoropropene, and octafluorocyclobutane, The total content of trifluoromethane, tetrafluoroethylene, hexafluoropropene, and octafluorocyclobutane is 98.7 mol% or more of the total composition. A composition in which the ratio of the molar amount of hexafluoropropene to the molar amount of octafluorocyclobutane is 5.0 or greater. <14> Furthermore, it contains perfluoroisobutene, The ratio of the molar amount of hexafluoropropene to the molar amount of perfluoroisobutene is 0.9 or greater. <13> The composition described above. <15> Furthermore, it includes at least one selected from the group consisting of pentafluoroethane and hexafluoroethane. <13> or <14> The composition described above. [Effects of the Invention]

[0007] According to one aspect of the present disclosure, there are provided a method for producing hexafluoropropene with suppressed production of octafluorocyclobutane as a by-product and a composition obtained by the production method.

Brief Description of the Drawings

[0008] [Figure 1] It is a schematic diagram showing an example of a production apparatus used in the production method of the present disclosure. [Figure 2] It is a schematic diagram showing another example of a production apparatus used in the production method of the present disclosure. [Figure 3] It is a schematic diagram showing another example of a production apparatus used in the production method of the present disclosure. [Figure 4] It is a schematic diagram showing another example of a production apparatus used in the production method of the present disclosure. [Figure 5] It is a schematic diagram showing another example of a production apparatus used in the production method of the present disclosure.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, which do not limit the present disclosure.

[0010] In the present disclosure, the term "step" includes, in addition to steps independent of other steps, also those steps that, even if not clearly distinguishable from other steps, are included as long as the purpose of the step is achieved. In the numerical range indicated by "~" in the present disclosure, the numerical values described before and after "~" are included as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other stepwise descriptions. Also, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In this disclosure, each component may contain multiple types of the corresponding substance. If multiple types of the substance corresponding to each component are present in the composition, the proportion of each component means the total proportion of the multiple types of substances present in the composition unless otherwise specified. When embodiments are described in this disclosure with reference to the drawings, the configuration of such embodiments is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each drawing are conceptual, and the relative relationships between the components are not limited thereto. In addition, components having substantially the same function are given the same reference numerals throughout all drawings, and redundant descriptions may be omitted.

[0011] In this disclosure, "preheating" refers to heating R23 before it comes into contact with TFE. The preheating of R23 is performed in a location separate from the reactor. During the preheating of R23, a small amount of R23 may undergo a thermal decomposition reaction on its own. In this disclosure, “reactor” means a region heated to a reaction temperature of 800°C or higher, where the reaction between R23 and TFE mainly proceeds. In this disclosure, "preheating temperature," "reaction temperature," and "heating temperature" are set temperatures for heating, and at least a portion of the object being heated may be at a temperature different from the set temperature. In this disclosure, “by-product” refers to products other than the target product, HFP.

[0012] [Method for producing hexafluoropropene (HFP)] A method for producing hexafluoropropene (HFP) in one embodiment of the present disclosure includes preheating trifluoromethane (R23) at a first preheating temperature of 350 to 700°C, and then contacting it with tetrafluoroethylene (TFE) to obtain a product containing HFP. The manufacturing method of this embodiment includes a first preheating step of preheating R23 to a first preheating temperature of 350 to 700°C, and a reaction step of contacting the R23 preheated at the first preheating temperature with TFE to obtain a product containing HFP. In this embodiment, the manufacturing method primarily yields a product containing HFP through the reaction of R23 and TFE in the reaction step. Alternatively, in the first preheating step, a portion of R23 may undergo a thermal decomposition reaction on its own, and a small amount of HFP may be generated by the thermal decomposition reaction of the R23 alone.

[0013] The manufacturing method of this embodiment may include other steps besides the first preheating step and the reaction step. Other steps include, for example, a supply step of supplying R23 and TFE, which have been preheated at a first preheating temperature, into the reactor; a second preheating step of obtaining a mixture by mixing R23 that has undergone the first preheating step with a second preheating heat medium heated at a second preheating heat medium heating temperature higher than the first preheating temperature; a TFE heating step of heating the TFE before contact between R23 and TFE; a discharge step of discharging the post-reaction composition containing the products obtained in the reaction step from the reactor; and a washing step of washing the post-reaction composition discharged in the discharge step. Hereinafter, "second preheating heat medium" refers to the heat medium used in the second preheating step, and "second preheating heat medium heating temperature" refers to the heating temperature of the second preheating heat medium.Hereafter, the mixture obtained in the second preheating step will also be called the "mixture after second preheating".

[0014] The manufacturing method of this embodiment preferably further includes the second preheating step described above. That is, in the manufacturing method of this embodiment, it is preferable to bring the R23 preheated at the first preheating temperature into contact with the TFE as a second post-preheating mixture obtained by mixing it with a second preheating heat medium heated at the second preheating heat medium heating temperature. In this embodiment, the manufacturing method may involve bringing R23, which has been preheated to a first preheating temperature, into contact with a heat transfer medium heated to a heating temperature higher than the first preheating temperature, and TFE during the reaction step. Hereinafter, the heat transfer medium used in the reaction step will also be referred to as the "reaction heat transfer medium."

[0015] Furthermore, the mixture obtained by contact between R23 and TFE is also called the "post-contact mixture." The post-contact mixture contains at least R23 and TFE. If the manufacturing method of this embodiment further includes a second preheating step, the post-contact mixture contains R23, a heat transfer medium for the second preheating step, and TFE. On the other hand, if the manufacturing method of this embodiment uses a reaction heat transfer medium in the reaction step, the post-contact mixture contains R23, TFE, and a reaction heat transfer medium. Furthermore, the mixture after contact may be formed from a portion of R23 undergoing thermal decomposition on its own before contact with TFE, or from a portion of R23 reacting with a portion of TFE after contact with TFE.

[0016] The manufacturing method of this embodiment further includes the above supply step, and in the reaction step, it is preferable to heat the R23 and TFE in the reactor at a reaction temperature of 800 to 1000°C. In other words, in the manufacturing method of this embodiment, it is preferable to supply the R23 and TFE, which have been preheated at the first preheating temperature, into the reactor, and to heat the R23 and TFE in the reactor at a reaction temperature of 800 to 1000°C.

[0017] According to the manufacturing method of this embodiment, the amount of octafluorocyclobutane (C318) produced is suppressed. The reason for this is not clear, but it is presumed to be as follows. In this embodiment, in the first preheating step, R23 that has been preheated to a first preheating temperature of 350 to 700°C is brought into contact with TFE. Therefore, compared to cases where there is no preheating step or the preheating temperature is less than 350°C, the R23 comes into contact with TFE at a higher temperature, and if heating is performed in the reaction step, the heating temperature is reached in a shorter time. Here, it is thought that the selectivity for the reaction in which C318 is produced in the mixture of R23 and TFE is higher at lower temperatures, and that the selectivity for the above reaction is particularly pronounced at temperatures around 300°C. In this embodiment, it is presumed that the production of C318 is suppressed because the time in which the mixture of R23 and TFE reaches the temperature at which the selectivity for the above reaction is high is short.

[0018] Furthermore, the manufacturing method of this embodiment also suppresses the generation of hydrogen fluoride adducts such as pentafluoroethane (hereinafter also referred to as "R125"). Hydrogen fluoride adducts are formed when hydrogen fluoride produced by the reaction of R23 and TFE adds to the reaction intermediate or reaction product. In this embodiment, the preheating temperature is high and the residence time until the desired conversion rate is reached can be shortened, so the contact time between the reaction intermediate and reaction product and hydrogen fluoride is also shortened, which is thought to suppress the generation of hydrogen fluoride adducts.

[0019] The following describes each step of the manufacturing method of this embodiment.

[0020] <Preheating process> (First preheating process) In the first preheating step, R23 is preheated to a first preheating temperature of 350-700°C. In the first preheating step, R23 may be preheated by supplying R23 to a preheater heated to a first preheating temperature, or by supplying R23 to the preheater and then heating the preheater to the first preheating temperature. Alternatively, the preheating of R23 in the first preheating step may be performed by mixing it with a heat transfer medium, as will be described later. As will be described later, R23 and the diluent may be mixed in advance before the first preheating step, and the mixture of R23 and the diluent (hereinafter also referred to as the "diluted mixture") may be preheated at the first preheating temperature. In other words, the first preheating step may be a step of preheating the R23 contained in the diluted mixture at the first preheating temperature.

[0021] The first preheating temperature is 350 to 700°C. From the viewpoint of suppressing the formation of C318, the first preheating temperature is preferably 450°C or higher, more preferably 500°C or higher, and even more preferably 600°C or higher. In the first preheating process, when R23 is preheated by heating a preheater, the first preheating temperature is the set temperature for heating, that is, the heating temperature of the preheater. The preheater is not particularly limited, and one with the same specifications as the reactor described later may be used. Furthermore, the preheater and reactor used in the manufacturing method of this embodiment may have the same specifications or different specifications.

[0022] (Second preheating process) As described above, the manufacturing method of this embodiment preferably further includes a second preheating step. In the second preheating step, a second post-preheated mixture is obtained by mixing R23 that has undergone the first preheating step with a second preheating heat transfer medium that has been heated at a heating temperature higher than the first preheating temperature. In this disclosure, "thermal fluid" means a fluid that does not substantially decompose on its own at the reaction temperature, and more preferably a fluid that does not substantially decompose on its own at temperatures of 1100°C or below. Examples of heat transfer fluids for the second preheating process include inert gases such as nitrogen gas, helium gas, and argon gas, with nitrogen gas being preferred from the viewpoint of economic efficiency and supply stability.

[0023] The heating temperature of the second preheating heat medium is higher than the first preheating temperature, for example, between 350°C and 1100°C. The heating temperature of the second preheating heat medium is above 350°C, and from the viewpoint of suppressing the formation of C318, it is preferably above 450°C, more preferably above 480°C, even more preferably above 500°C, particularly preferably above 850°C, extremely preferably above 900°C, and most preferably above 1000°C. Also, from the viewpoint of suppressing the formation of C318, the heating temperature of the second preheating heat medium is preferably 1100°C or lower, more preferably below 1050°C, and even more preferably below 1000°C. In another embodiment, from the viewpoint of suppressing the formation of C318 and from the viewpoint of operability, the heating temperature of the second preheating heat medium is preferably between 450 and 1100°C, more preferably between 600 and 1100°C, and even more preferably between 800 and 1000°C. The heating temperature of the second preheating heat transfer medium is preferably 10°C or more higher than the first preheating temperature, more preferably 50°C or more higher, even more preferably 200°C or more higher, and particularly preferably 500°C or more higher. The second preheating heat transfer medium is heated, for example, by supplying it to a heat transfer medium heater and heating it at the second preheating heat transfer medium heating temperature. The mixing of R23 and the second preheating heat transfer medium may be carried out using a mixer, or by merging the flow path for R23 with the flow path for the second preheating heat transfer medium.

[0024] The amount of the second preheating heat transfer medium added is, for example, 0 to 50 mol% of the total amount of R23, TFE, and the second preheating heat transfer medium preheated at the first preheating temperature. The amount of the second preheating heat transfer medium added to the total amount of R23, TFE, and the second preheating heat transfer medium is preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 30 mol% or less, and particularly preferably 20 mol% or less. By keeping the amount of the second preheating heat transfer medium added below the above upper limit, a large amount of HFP is produced in the reaction process, and the separation operation after the reaction becomes easier. Furthermore, the amount of the second preheating heat transfer medium added relative to the total amount of R23, TFE, and the second preheating heat transfer medium may be 0 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more. By having the amount of the second preheating heat transfer medium added be greater than or equal to the lower limit, the temperature of the mixture rises quickly after contact, and the formation of C318 is suppressed.

[0025] For example, the content of the second preheating heat transfer medium relative to the total amount of R23 and the second preheating heat transfer medium in the mixture after the second preheating before contact with the TFE can be 0 to 55.5 mol%. The content of the second preheating heat transfer medium relative to the total amount of R23 and the second preheating heat transfer medium is preferably 55.5 mol% or less, more preferably 44.4 mol% or less, and even more preferably 33.3 mol% or less. By keeping the content of the second preheating heat transfer medium below the upper limit, a large amount of HFP is generated in the reaction process, and the separation operation after the reaction becomes easier. Furthermore, the content of the second preheating heat transfer medium relative to the total amount of R23 and the second preheating heat transfer medium may be 0 mol% or more, preferably 5.5 mol% or more, and more preferably 11.1 mol% or more. By having a content of the second preheating heat transfer medium above the lower limit, the time it takes for the mixture to reach the reaction temperature after contact is shortened, and the formation of C318 is suppressed.

[0026] (First preheating process using a heat transfer medium) As stated above, the preheating of R23 in the first preheating step may be performed by mixing R23 with a heat transfer medium. Hereinafter, the heat transfer medium used in the first preheating step will also be referred to as the "first preheating heat transfer medium". In the first preheating step using a heat transfer medium, for example, the first preheating heat transfer medium, which has been heated at the first preheating heat transfer medium heating temperature in a heat transfer medium heater, is mixed with R23 to obtain a first post-preheated mixture, thereby preheating the R23 contained in the first post-preheated mixture to the first preheating temperature. The first preheating temperature in the first preheating step using a heat transfer medium, i.e., the set temperature for heating, is the temperature of the mixture after the first preheating, T3(K), which can be theoretically estimated using the following formula, based on the temperature of R23 before mixing T1(K), the heating temperature of the first preheating heat transfer medium T2(K), the flow rate of R23 to be mixed M1(kg / h), the flow rate of the first preheating heat transfer medium M2(kg / h), the average specific heat of R23 C1(kcal / kg·K), and the specific heat of the first preheating heat transfer medium C2(kcal / kg·K). Formula: (T3-T1)×M1×C1=(T2-T3)×M2×C2

[0027] The type of heat transfer medium for the first preheating is the same as that for the second preheating heat transfer medium. When both the first and second preheating heat transfer mediums are used in the preheating process, they may be the same type of medium or different types of medium, but it is preferable that they be the same type of medium from the viewpoint of facilitating separation operations after the reaction. The heating temperature of the first preheating heat medium should be any temperature that can raise the temperature T3 of the mixture after the first preheating to 350-700°C, for example, between 350°C and 1100°C. The heating temperature of the first preheating heat medium is above 350°C, and from the viewpoint of suppressing the formation of C318, it is preferably above 450°C, more preferably above 480°C, even more preferably above 500°C, particularly preferably above 850°C, extremely preferably above 900°C, and most preferably above 1000°C. Furthermore, from the viewpoint of suppressing the formation of C318, the heating temperature of the first preheating heat medium is preferably below 1100°C, more preferably below 1050°C, and even more preferably below 1000°C. Furthermore, from the viewpoint of suppressing the formation of C318, the heating temperature of the first preheating heat medium is preferably below 1100°C, more preferably below 1050°C, and even more preferably below 1000°C. In another embodiment, the heating temperature of the second preheating heat medium is preferably 450 to 1100°C, more preferably 600 to 1100°C, and even more preferably 800 to 1000°C, from the viewpoint of suppressing the formation of C318 and from the viewpoint of operability.

[0028] The mixing of R23 and the first preheating heat transfer medium may be carried out using a mixer, or by merging the flow path for R23 with the flow path for the first preheating heat transfer medium. The content of the first preheating heat transfer medium in the first preheated mixture before contact with TFE is not particularly limited as long as the amount is such that the temperature T3 of the first preheated mixture is 350 to 700°C. The content of the first preheating heat transfer medium in the first preheated mixture can be, for example, 55.5 mol% or less relative to the total of R23 and the first preheating heat transfer medium. The content of the first preheating heat transfer medium relative to the total of R23 and the first preheating heat transfer medium is preferably 55.5 mol% or less, more preferably 44.4 mol% or less, and even more preferably 33.3 mol% or less. Furthermore, the content of the first preheating heat transfer medium relative to the total of R23 and the first preheating heat transfer medium may be 0 mol% or more, preferably 5.5 mol% or more, and more preferably 11.1 mol% or more. If the content of the first preheating heat transfer medium relative to the total of R23 and the first preheating heat transfer medium is below the above upper limit, a large amount of HFP is produced in the reaction process, and the separation operation after the reaction is made easier. On the other hand, if the content of the first preheating heat transfer medium relative to the total of R23 and the first preheating heat transfer medium is above the above lower limit, the time it takes for R23 to reach the first preheating temperature is shortened.

[0029] Furthermore, if a heat transfer medium is used in the first preheating step, in the second preheating step, a second preheating mixture containing R23, the first preheating heat transfer medium, and the second preheating heat transfer medium is obtained by mixing the first preheating mixture, which is a mixture of R23 and the first preheating heat transfer medium, with the second preheating heat transfer medium.

[0030] (Mixing R23 with diluent) As mentioned above, R23 and the diluent may be mixed in advance before the first preheating step. In this disclosure, "dilution medium" means a medium that does not substantially decompose on its own at the temperature at which it is mixed with R23. It is desirable that the dilution medium, like the heat medium, does not substantially decompose on its own at the reaction temperature, and specifically, it is desirable that it does not substantially decompose on its own at temperatures of 1100°C or below. Examples of dilution media include those similar to those used for the second preheating heat medium. When at least one of the first preheating heat medium and the second preheating heat medium is used in the preheating step, the dilution media and at least one of the first preheating heat medium and the second preheating heat medium may be the same type of medium or different types of medium, but it is preferable that they be the same type of medium from the viewpoint of facilitating separation operations after the reaction. The temperature of the diluent when mixing with R23 is not particularly limited, but for example, it may be less than 450°C.

[0031] The mixing of R23 and the diluent may be performed using a mixer, or by merging the channel through which R23 passes with the channel through which the diluent passes. The content of the diluent medium relative to the total of R23 and the diluent medium is not particularly limited. Examples of the content of the diluent medium include 55.5 mol% or less relative to the total of R23 and the diluent medium. The content of the diluent medium relative to the total of R23 and the diluent medium is preferably 55.5 mol% or less, more preferably 44.4 mol% or less, and even more preferably 33.3 mol% or less. Also, the content of the diluent medium relative to the total of R23 and the diluent medium may be 0 mol% or more, preferably 5.5 mol% or more, and more preferably 11.1 mol% or more. When the content of the diluent medium relative to the total of R23 and the diluent medium is below the above upper limit, the production amount of HFP in the reaction step is large, and the separation operation after the reaction becomes easy. On the other hand, when the content of the diluent medium relative to the total of R23 and the diluent medium is above the above lower limit, the HFP concentration and the TFE concentration inside the reactor become low, so there is an advantage that the generation of sequential reaction by-products such as perfluoroisobutene (hereinafter also referred to as "PFIB") can be suppressed.

[0032] Before passing through the first preheating step, R23 and the diluent medium are mixed in advance, and when passing through the second preheating step, the mixture after the second preheating contains R23, the diluent medium, and the heat medium for the second preheating.

[0033] <TFE Heating Step> As described above, the production method of the present embodiment may further include a TFE heating step of heating TFE before the contact of R23 and TFE. Examples of the heating temperature in the TFE heating step include 50 to 250°C. From the viewpoint of TFE stability, 50 to 200°C is preferable, and 100 to 150°C is more preferable. The heating of TFE is performed, for example, by supplying TFE to a TFE heater for heating TFE and heating at the above heating temperature. As the TFE heater, the same one as the reactor described later is used.

[0034] <Supply Step> In the supply step, R23 and TFE, which have been preheated to the first preheating temperature in the first preheating step, are supplied to the reactor. In the manufacturing method of this embodiment, R23 and TFE may be supplied to the reactor separately and then brought into contact within the reactor to obtain a post-contact mixture, or the post-contact mixture obtained by bringing R23 and TFE into contact may be supplied to the reactor. In other words, in the manufacturing method of this embodiment, the reaction step may start after the supply step, or the supply step may be performed after the reaction step has started. Furthermore, in the manufacturing method of this embodiment, the post-contact mixture may be obtained either inside or outside the reactor.

[0035] The reactor only needs to be able to withstand the temperature and pressure described later, and its shape and structure are not particularly limited. Examples of reactors include tubular reactors. Examples of reactor materials include acid-resistant metal materials such as copper, stainless steel, Hastelloy, and Inconel. The reactor may be equipped with heating means such as an electric heater to heat the inside of the reactor. The reactor may be preheated to the reaction temperature before supplying R23 and TFE, or it may be heated to the reaction temperature after supplying R23 and TFE. R23 and TFE may be supplied into the reactor through a supply channel. The supply channel is a flow path through which R23, TFE, and any heat transfer fluid used as needed can pass, and its shape and size are not particularly limited. The material of the supply channel may be the same as that of the reactor. The term "medium" above is a general term for the first preheating heat transfer fluid, the dilution medium, the second preheating heat transfer fluid, and the reaction heat transfer fluid described later, and the same applies hereinafter. Furthermore, from the viewpoint of suppressing the generation of by-products, it is desirable to use a reactor with a mixing mechanism. Examples of reactors with a mixing mechanism include ejector-type reactors and reactors with mixers. By using a reactor with a mixing mechanism, when a mixture containing R23, TFE, and at least one of the medium is supplied to the reactor, it instantly becomes nearly homogeneous, thereby suppressing the generation of by-products.

[0036] <Reaction Process> (Contact between R23 and TFE) In the reaction step, R23, preheated at a first preheating temperature, is brought into contact with TFE to obtain a product containing HFP. In the reaction step, a post-contact mixture is obtained by the contact of R23 and TFE, and HFP is produced by the reaction of at least a portion of the R23 and at least a portion of the TFE contained in the post-contact mixture. In the reaction step, R23 that has undergone the first preheating step may be brought into contact with TFE as is, or R23 that has undergone both the first and second preheating steps may be brought into contact with TFE. In other words, the R23 brought into contact with TFE may be R23 that has been preheated in the first preheating step, or it may be R23 that has undergone another step (for example, a second preheating step) after being preheated in the first preheating step. When R23 that has undergone the first and second preheating steps is brought into contact with TFE, the aforementioned second preheated mixture is brought into contact with TFE. Also, when preheating of R23 in the first preheating step is performed by mixing R23 with the first preheating heat transfer medium, and the R23 that has undergone the first preheating step is brought into contact with TFE as is, the aforementioned first preheated mixture is brought into contact with TFE as is. Furthermore, if R23 is mixed with a diluent before the first preheating step, and the resulting diluted mixture is preheated to the first preheating temperature using a preheater, and the second preheating step is not performed, the diluted mixture that has undergone the first preheating step is brought into contact with TFE as is.

[0037] The ratio of R23 to TFE to be in contact is not particularly limited. For example, the ratio of TFE to the total amount of R23 and TFE in contact can be between 0 mol% and 50 mol%, preferably between 0 mol% and 30 mol%, and more preferably between 5 and 20 mol%. A TFE ratio above the lower limit increases the reaction selectivity of HFP, i.e., the proportion of HFP in the product. On the other hand, above Having the proportion of TFE below the above upper limit has the advantage of suppressing the formation of PFIBs, which are by-products other than C318.

[0038] (Form using a heat transfer medium for reaction) In the reaction step, as described above, R23 preheated at the first preheating temperature, a reaction heat transfer medium heated at a heating temperature higher than the first preheating temperature, and TFE may be brought into contact. Examples of reaction heat transfer fluids include those similar to those used for the second preheating heat transfer fluid. When at least one fluid selected from the group consisting of the first preheating heat transfer fluid, diluent, and second preheating heat transfer fluid is used before the reaction step, the reaction heat transfer fluid may be the same type of fluid as the at least one fluid selected from the group consisting of the first preheating heat transfer fluid, diluent, and second preheating heat transfer fluid, or a different type of fluid may be used. From the viewpoint of facilitating separation operations after the reaction, it is preferable to use the same type of fluid.

[0039] The heating temperature of the reaction heat medium is higher than the first preheating temperature, for example, between 350°C and 1100°C. The heating temperature of the reaction heat medium is above 350°C, and from the viewpoint of suppressing the formation of C318, it is preferably above 450°C, more preferably above 480°C, even more preferably above 500°C, particularly preferably above 850°C, extremely preferably above 900°C, and most preferably above 1000°C. Also, from the viewpoint of suppressing the formation of C318, the heating temperature of the reaction heat medium is preferably 1100°C or lower, more preferably below 1050°C, and even more preferably below 1000°C. In another embodiment, from the viewpoint of suppressing the formation of C318 and from the viewpoint of operability, the heating temperature of the reaction heat medium is preferably between 450 and 1100°C, more preferably between 600 and 1100°C, and even more preferably between 800 and 1000°C. The reaction heat transfer medium is preferably 10°C or more higher than the first preheating temperature, more preferably 50°C or more higher, even more preferably 200°C or more higher, and particularly preferably 500°C or more higher. The reaction heat transfer medium is heated, for example, by supplying it to a heat transfer medium heater and heating it to the heating temperature of the reaction heat transfer medium. Contact between R23, the reaction heat transfer medium, and TFE may be carried out using a mixer, or by merging the channel for passing R23, the channel for passing the reaction heat transfer medium, and the channel for passing TFE at a single point.

[0040] The amount of reaction heat transfer medium added is, for example, 0 to 50 mol% of the total amount of R23, TFE, and reaction heat transfer medium preheated at the first preheating temperature. The amount of reaction heat transfer medium added relative to the total amount of R23, TFE, and reaction heat transfer medium is preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 30 mol% or less, and particularly preferably 20 mol% or less. By keeping the amount of reaction heat transfer medium added below the above upper limit, a large amount of HFP is produced in the reaction process, and the separation operation after the reaction becomes easier. Furthermore, the amount of reaction heat transfer medium added relative to the total amount of R23, TFE, and reaction heat transfer medium may be 0 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more. By having the above amount of reaction heat transfer medium added be greater than or equal to the above lower limit, the temperature of the mixture rises quickly after contact, and the formation of C318 is suppressed.

[0041] Furthermore, the total media content relative to the total amount of R23, TFE, and any media included as needed in the mixture after contact is not particularly limited. Hereinafter, the total media content relative to the total amount of R23, TFE, and media will also be referred to as the "total media content." The total media content can range from 0 to 50 mol%, for example. The total media content is preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 30 mol% or less, and particularly preferably 20 mol% or less. By keeping the total media content below the above upper limit, a large amount of HFP is produced in the reaction process, and the separation operation after the reaction becomes easier. Furthermore, the total media content may be 0 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more. Having the total media content above the lower limit has the advantage of suppressing the generation of sequential reaction by-products such as PFIBs, as it reduces the HFP and TFE concentrations inside the reactor.

[0042] (Heating at reaction temperature) In the reaction step, as described above, it is preferable to heat the R23 and TFE supplied into the reactor in the supply step at a reaction temperature of 800 to 1000°C. In other words, in the reaction step, it is preferable to heat the post-contact mixture in the reactor at a reaction temperature of 800 to 1000°C.

[0043] The reaction temperature is preferably 800°C or higher, more preferably 800 to 1000°C. The reaction temperature is preferably 830°C or higher, more preferably 850°C or higher. Furthermore, the reaction temperature is preferably 1000°C or lower, more preferably 950°C or lower, even more preferably 900°C or lower, particularly preferably 870°C or lower, and extremely preferably 850°C or lower. By keeping the reaction temperature above the lower limit, the formation of C318 is suppressed. Furthermore, by keeping the reaction temperature below the upper limit, the formation of PFIB, a by-product other than C318, is suppressed. "Reaction temperature" refers to the set temperature during heating, i.e., the heating temperature of the reactor. In this embodiment, this also includes cases where at least a portion of the R23 and TFE in the reactor has not reached the reaction temperature. It is presumed that the generation of by-products in the reaction process is more likely to occur near the inner surface of the reactor, which is susceptible to the effects of heating. Therefore, the amount of by-products generated is thought to have a stronger correlation with the heating temperature of the reactor than with the temperature of R23 in the center of the reactor.

[0044] In the reaction process, the time for heating R23 and TFE in the reactor to the reaction temperature is preferably 5 seconds or less. In other words, in the reaction process, the time for heating the post-contact mixture in the reactor to the reaction temperature is preferably 5 seconds or less. Hereinafter, the time for heating the post-contact mixture in the reactor to the reaction temperature will also be referred to as the "reaction time". If the reaction method in the reaction process is continuous and the reactor is continuously heated to the reaction temperature, the above reaction time is the residence time from when R23 and TFE are supplied to the reactor until the product is discharged. The residence time is calculated, for example, from the reactor volume, supply flow rate, outlet flow rate, average reactor temperature, and reactor pressure. The above reaction time can be, for example, 0.01 to 5 seconds. Preferably, the reaction time is 0.1 seconds or more, more preferably 0.2 seconds or more, even more preferably 0.3 seconds or more, and particularly preferably 0.34 seconds or more. Also, preferably the reaction time is 5 seconds or less, more preferably 3 seconds or less, even more preferably 2 seconds or less, particularly preferably 1 second or less, and extremely preferably 0.5 seconds or less. By keeping the reaction time below the above upper limit, the formation of PFIB, a by-product other than C318, is suppressed. Furthermore, by keeping the reaction time above the above lower limit, energy efficiency is increased, the conversion rate of the raw materials is increased, and the amount of HFP produced is increased.

[0045] In the reaction process, the gauge pressure inside the reactor can be, for example, 0 kPaG or more and less than 200 kPaG. The gauge pressure inside the reactor is preferably 1 kPaG or more, more preferably 3 kPaG or more, and even more preferably 5 kPaG or more. Furthermore, the gauge pressure inside the reactor is preferably 190 kPaG or less, more preferably 150 kPaG or less, even more preferably 100 kPaG or less, particularly preferably 50 kPaG or less, and extremely preferably 10 kPaG or less. In another embodiment, the gauge pressure inside the reactor is preferably 1 to 190 kPaG, more preferably 3 to 150 kPaG, even more preferably 5 to 100 kPaG, and particularly preferably 50 to 100 kPaG. By keeping the gauge pressure inside the reactor below the above upper limits, the formation of PFIB, a by-product other than C318, is suppressed, and pressure adjustment inside the reactor becomes easier. Furthermore, when the gauge pressure inside the reactor is above the lower limit mentioned above, the reaction efficiency per unit volume is high, resulting in a larger amount of HFP being produced.

[0046] The post-reaction composition, after the reaction step, contains at least the product obtained by the reaction of R23 and TFE, and may further contain unreacted raw materials, R23 and TFE. Furthermore, if a medium is used in a step prior to the reaction step, the post-reaction composition may further contain the said medium. Hereinafter, a post-reaction composition obtained without using a medium, or a composition obtained by removing the medium from a post-reaction composition obtained with a medium, will also be referred to as a "specific composition."

[0047] In the reaction process, the product obtained by the reaction of R23 and TFE contains at least HFP, and may also contain compounds other than HFP. Examples of compounds other than HFP included in the product include by-products such as C318, PFIB, R125, and hexafluoroethane (hereinafter also referred to as "C2F6"). In other words, the specific composition may contain at least HFP, and may also contain HFP and unreacted raw materials R23 and TFE, and may further contain the by-product C318. The specific composition may further contain other by-products such as PFIB, and may further contain at least one selected from the group consisting of R125 and C2F6.

[0048] When a specific composition contains R23, TFE, HFP, and C318, the total content of R23, TFE, HFP, and C318 is preferably 98.7 mol% or more, more preferably 99.0 mol% or more, and even more preferably 99.2 mol% or more, relative to the entire specific composition. The HFP content relative to the entire specific composition is preferably 0.1 mol% or more, more preferably 1.0 mol% or more, even more preferably 1.8 mol% or more, particularly preferably 5.0 mol% or more, and extremely preferably 13.5 mol% or more.

[0049] If the product contains C318, the molar amount M of C318 contained in the above product is C318 Molar amount M of HFP relative to HFP The ratio (M HFP / M C318 A value of 5.0 or higher is preferred in terms of the amount of HFP produced in the by-products, more preferably 21.5 or higher, even more preferably 80.0 or higher, and particularly preferably 248.0 or higher. If the product contains PFIB, the molar amount M of PFIB contained in the above product is... PFIB Molar amount M of HFP relative to HFP The ratio (M HFP / M PFIB) is preferably 0.9 or higher, more preferably 4.8 or higher, even more preferably 10.8 or higher, particularly preferably 13.7 or higher, and extremely preferably 19.4 or higher, in terms of the large amount of HFP produced in the by-products.

[0050] <Other processes> In the discharge step, the post-reaction composition, including the product obtained in the reaction step, is discharged from the reactor. As described above, the post-reaction composition may also contain unreacted raw materials, R23 and TFE. Furthermore, the medium contained in the post-contact mixture is also contained in the post-reaction composition. In the washing process, the post-reaction composition discharged in the discharge process is washed. Specifically, for example, water is passed through the post-reaction composition to remove the acid generated by the reaction.

[0051] <Manufacturing equipment> Next, an example of a manufacturing apparatus used in the manufacturing method of this embodiment will be described with reference to Figures 1 to 5. The manufacturing apparatus shown in Figure 1 is used in the aforementioned manufacturing method, in which, in the first preheating step, R23 is preheated by heating a preheater, and in the second preheating step, the second preheated mixture obtained by mixing R23 with a second preheating heat transfer medium and TFE are supplied separately into the reactor. Furthermore, the manufacturing apparatus shown in Figure 1 may be used in a manufacturing method in which R23, preheated by heating in a preheater in the first preheating step, is supplied directly to the reaction apparatus without going through the second preheating step.

[0052] The manufacturing apparatus 100 shown in Figure 1 comprises an R23 container 1 for containing R23 before preheating, an R23 preheater 4 for preheating R23 in the first preheating step, a heat transfer medium container 5 for containing a second preheating heat transfer medium before heating, a heat transfer medium heater 8 for heating the second preheating heat transfer medium, a TFE container 9 for containing TFE before heating, a TFE heater 12 for heating TFE, and a reactor 13 for heating R23 and TFE at the reaction temperature in the reaction step. Between the R23 container 1 and the R23 preheater 4, there is an R23 supply passage 2 for supplying R23 from the R23 container 1 to the R23 preheater 4. Similarly, between the heat transfer medium container 5 and the heat transfer medium heater 8, there is a heat transfer medium supply passage 6 for supplying a second preheating heat transfer medium from the heat transfer medium container 5 to the heat transfer medium heater 8. Similarly, between the TFE container 9 and the TFE heater 12, there is a TFE supply passage 10 for supplying TFE from the TFE container 9 to the TFE heater 12. The R23 supply passage 2, the heat transfer medium supply passage 6, and the TFE supply passage 10 are each provided with an R23 flow rate control device 3 for controlling the flow rate of R23, a heat transfer medium flow rate control device 7 for controlling the flow rate of the second preheating heat transfer medium, and a TFE flow rate control device 11 for controlling the flow rate of TFE, respectively.

[0053] On the other hand, R23 supply passages 18 and 23 are provided between the R23 preheater 4 and the reactor 13 to supply R23 from the R23 preheater 4 to the reactor 13. The R23 supply passages 18 and 23 merge with a heat transfer medium supply passage 19 that supplies a second preheating heat transfer medium from the heat transfer medium heater 8 to the confluence point 20, which is located between the R23 preheater 4 and the reactor 13. Between the TFE heater 12 and the reactor 13, a TFE supply passage 21 is provided to supply TFE from the TFE heater 12 to a supply port in the reactor 13 that is different from the supply port for R23. Furthermore, in the manufacturing apparatus 100 shown in Figure 1, on the opposite side of the R23 supply passage 23 in the reactor 13, a washing tower 15 for washing the post-reaction composition, a recovery unit 16 for recovering the washed post-reaction composition, and an analytical device 17 for analyzing the components of the post-reaction composition are provided via a discharge passage 14.

[0054] Next, an example of the manufacturing method of this embodiment using the manufacturing apparatus 100 shown in Figure 1 will be described. R23 contained in R23 container 1 is supplied via R23 supply path 2 to R23 preheater 4, which is heated to a first preheating temperature. Here, the flow rate of R23 is controlled by R23 flow rate control device 3. Meanwhile, the second preheating heat transfer medium contained in heat transfer medium container 5 is supplied via heat transfer medium supply path 6 to heat transfer medium heater 8, which is heated to the second preheating heat transfer medium heating temperature. The flow rate of the second preheating heat transfer medium is controlled by heat transfer medium flow rate control device 7, similar to R23. Similarly, TFE contained in TFE container 9 is supplied via TFE supply path 10 to TFE heater 12, which is heated to the TFE heating temperature. The flow rate of TFE is controlled by TFE flow rate control device 11, similar to R23 and the second preheating heat transfer medium.

[0055] Next, the R23 preheated at the first preheating temperature in the R23 preheater 4 and the second preheating heat medium heated at the second preheating heat medium heating temperature in the heat medium heater 8 are mixed at the confluence point 20 via the R23 supply channel 18 and the heat medium supply channel 19, respectively, to form the second preheated mixture. The second preheated mixture obtained at the confluence point 20 is then supplied to the reactor 13, which has been heated to the reaction temperature, via the R23 supply channel 23. Meanwhile, the TFE heated to the heating temperature in the TFE heater 12 is supplied to the reactor 13, which has been heated to the reaction temperature, via the TFE supply passage 21, from a separate supply port from the second preheated mixture. In this way, the second preheated mixture and the TFE are supplied to the reactor 13, and the contact mixture is obtained by mixing them in the reactor 13.

[0056] The content of the second preheating heat transfer medium in the mixture after contact is controlled by adjusting the flow rates of R23, the second preheating heat transfer medium, and TFE, respectively, using the R23 flow rate control device 3, the heat transfer medium flow rate control device 7, and the TFE flow rate control device 11. The second preheated mixture supplied to reactor 13 mixes with TFE within reactor 13 to form a post-contact mixture. At least a portion of the R23 in the post-contact mixture reacts with at least a portion of the TFE to form a product containing HFP. The post-contact mixture is then heated at the reaction temperature within reactor 13, causing the reaction between R23 and TFE to proceed further. In other words, the post-contact mixture reacts with R23 and TFE within reactor 13, and the reaction proceeds further with heating, resulting in a post-reaction composition containing at least the above product and the second preheating heat transfer medium.

[0057] The post-reaction composition is supplied to the washing tower 15 via the discharge channel 14 and washed with water as necessary. Washing in the washing tower 15 removes the acid (e.g., hydrogen fluoride) generated by the reaction between R23 and TFE from the post-reaction composition. The post-reaction composition, after being washed as necessary, is recovered in the recovery unit 16 via the discharge channel 14. At least a portion of the post-reaction composition recovered in the recovery unit 16 is analyzed by an analyzer 17 as necessary.

[0058] In another example of the manufacturing method of this embodiment using the manufacturing apparatus 100 shown in Figure 1, HFP is manufactured without using a second preheating heat transfer medium. Specifically, for example, the HFP is manufactured in the same manner as the HFP manufacturing method using the second preheating heat transfer medium, except that the flow rate of the second preheating heat transfer medium is set to 0 ml / min by the heat transfer medium flow rate control device 7. In this case, the R23 preheated at the first preheating temperature in the R23 preheater 4 passes directly through the confluence point 20 and is supplied to the reactor 13.

[0059] (Other manufacturing equipment 1) The manufacturing apparatus shown in Figure 2 is used in the aforementioned manufacturing method, in which, in the first preheating step, R23 is preheated by heating in a preheater, and in the second preheating step, the second preheated mixture obtained by mixing R23 with the second preheating heat transfer medium is mixed with TFE beforehand and then supplied to the reactor. Furthermore, the manufacturing apparatus shown in Figure 2 may also be used in a manufacturing method in which R23, preheated by heating in a preheater in the first preheating step, is mixed directly with TFE without going through the second preheating step.

[0060] The manufacturing apparatus 101 shown in Figure 2 differs from the manufacturing apparatus 100 shown in Figure 1 in that, after the R23 supply path 18 merges with the heat transfer medium supply path 19 at the confluence point 20, the R23 supply path 23 further merges with the TFE supply path 21 that supplies TFE from the TFE heater 12 to the confluence point 22 at the confluence point 22, becoming the R23 supply path 29. Other components of the manufacturing apparatus 101 shown in Figure 2, namely the R23 container 1, R23 supply passage 2, R23 flow rate control device 3, R23 preheater 4, heat transfer medium container 5, heat transfer medium supply passage 6, heat transfer medium flow rate control device 7, heat transfer medium heater 8, TFE container 9, TFE supply passage 10, TFE flow rate control device 11, TFE heater 12, reactor 13, discharge passage 14, washing tower 15, recovery unit 16, and analysis device 17, are the same as those of the manufacturing apparatus 100 shown in Figure 1, so their explanation is omitted.

[0061] In an example of the manufacturing method of this embodiment using the manufacturing apparatus 101 shown in Figure 2, first, as in the manufacturing method described above, R23 and the second preheating heat transfer medium are mixed at the confluence point 20 to form the second preheated mixture. Next, the second preheated mixture obtained at the confluence point 20 and the TFE heated at the TFE heating temperature in the TFE heater 12 are mixed at the confluence point 22 via the R23 supply channel 23 and the TFE supply channel 21, respectively, to form a post-contact mixture. The post-contact mixture obtained at the confluence point 22 is then supplied to the reactor 13, which has been heated to the reaction temperature, via the R23 supply channel 29.

[0062] At the confluence point 22, the second preheated mixture mixes with TFE to form a post-contact mixture. At least a portion of the R23 in the post-contact mixture reacts with at least a portion of the TFE to form a product containing HFP. The post-contact mixture is then supplied to reactor 13 and heated at the reaction temperature, causing the reaction between R23 and TFE to proceed further. In other words, the post-contact mixture reacts with R23 and TFE at the confluence point 22, and the reaction proceeds further due to heating in reactor 13, resulting in a post-reaction composition containing at least the above product and the second preheating heat transfer medium.

[0063] In another example of the manufacturing method of this embodiment using the manufacturing apparatus 101 shown in Figure 2, HFP is manufactured without using a second preheating heat transfer medium. Specifically, for example, the HFP is manufactured in the same manner as the HFP manufacturing method using the second preheating heat transfer medium, except that the flow rate of the second preheating heat transfer medium is set to 0 ml / min by the heat transfer medium flow rate control device 7. In this case, the R23 preheated at the first preheating temperature in the R23 preheater 4 passes directly through the confluence point 20 and is supplied to the reactor 13 as a post-contact mixture mixed with TFE at the confluence point 22.

[0064] (Other manufacturing equipment 2) The manufacturing apparatus shown in Figure 3 is used in the aforementioned manufacturing method, in which, in the first preheating step, R23 preheated by heating a preheater, a reaction heat transfer medium, and TFE are mixed in advance and a post-contact mixture is supplied into the reactor. Furthermore, the manufacturing apparatus shown in Figure 3 may be used in a manufacturing method in which, without using a reaction heat transfer medium, a post-contact mixture obtained by mixing R23 and TFE, which have been preheated by heating a preheater in the first preheating step, is supplied into the reactor.

[0065] The manufacturing apparatus 102 shown in Figure 3 differs from the manufacturing apparatus 100 shown in Figure 1 and the manufacturing apparatus 101 shown in Figure 2 in that the R23 supply path 18 merges with both the heat transfer medium supply path 19 and the TFE supply path 21 at the confluence point 20 to become the R23 supply path 23. The heat transfer medium contained in the heat transfer medium container 5 is the heat transfer medium used when R23 and TFE come into contact, i.e., in the reaction process, and therefore differs from the manufacturing apparatus 100 shown in Figure 1 and the manufacturing apparatus 101 shown in Figure 2 in that it is the reaction heat transfer medium rather than the second preheating heat transfer medium. Other components of the manufacturing apparatus 102 shown in Figure 3, namely the R23 container 1, R23 supply passage 2, R23 flow rate control device 3, R23 preheater 4, heat transfer medium container 5, heat transfer medium supply passage 6, heat transfer medium flow rate control device 7, heat transfer medium heater 8, TFE container 9, TFE supply passage 10, TFE flow rate control device 11, TFE heater 12, reactor 13, discharge passage 14, washing tower 15, recovery unit 16, and analysis device 17, are the same as those of the manufacturing apparatus 100 shown in Figure 1, so their explanation is omitted.

[0066] In an example of the manufacturing method of this embodiment using the manufacturing apparatus 102 shown in Figure 3, first, as in the manufacturing method described above, R23 is preheated at a first preheating temperature in the R23 preheater 4, the reaction heat medium is heated at the reaction heat medium heating temperature in the heat medium heater 8, and the TFE is heated at the TFE heating temperature in the TFE heater 12. Then, R23, the reaction heat transfer medium, and TFE are mixed at the confluence point 20 via the R23 supply channel 18, the heat transfer medium supply channel 19, and the TFE supply channel 21, respectively, to form a post-contact mixture. The post-contact mixture obtained at the confluence point 20 is further supplied via the R23 supply channel 23 to the reactor 13, which has been heated to the reaction temperature.

[0067] At the confluence point 20, R23, the reaction heat transfer medium, and TFE are mixed to form a post-contact mixture. At least a portion of the R23 and at least a portion of the TFE in the post-contact mixture react to form a product containing HFP. The post-contact mixture is then supplied to the reactor 13 and heated at the reaction temperature, causing the reaction between R23 and TFE to proceed further. In other words, the post-contact mixture reacts with R23 and TFE at the confluence point 20, and the reaction proceeds further due to heating in the reactor 13, resulting in a post-reaction composition containing at least the above product and the reaction heat transfer medium.

[0068] In another example of the manufacturing method of this embodiment using the manufacturing apparatus 102 shown in Figure 3, HFP is manufactured without using a reaction heat transfer medium. Specifically, the HFP is manufactured in the same manner as the HFP manufacturing method using the reaction heat transfer medium, except that the flow rate of the reaction heat transfer medium is set to 0 ml / min by the heat transfer medium flow rate control device 7. In this case, the post-contact mixture, in which R23 preheated at the first preheating temperature in the R23 preheater 4 and TFE are mixed at the confluence point 20, is supplied to the reactor 13.

[0069] (Other manufacturing equipment 3) The manufacturing apparatus shown in Figure 4 is used in the aforementioned manufacturing method, in which R23 and the diluent are mixed in advance before the first preheating step, the resulting diluted mixture is preheated to the first preheating temperature by heating a preheater, mixed with TFE, and supplied to the reactor. Furthermore, the manufacturing apparatus shown in Figure 4 may also be used in a manufacturing method in which R23 is preheated directly to the first preheating temperature using a preheater without mixing R23 with a diluent.

[0070] The manufacturing apparatus 103 shown in Figure 4 includes an R23 container 1 for containing R23 before preheating, a dilution medium container 24 for containing a dilution medium, an R23 preheater 4 for preheating R23 in the first preheating step, a TFE container 9 for containing TFE before heating, a TFE heater 12 for heating TFE, and a reactor 13 for heating R23 and TFE at the reaction temperature in the reaction step. Between the R23 container 1 and the R23 preheater 4, R23 supply paths 2 and 27 are provided to supply R23 from the R23 container 1 to the R23 preheater 4. At a confluence point 28 located between the R23 container 1 and the R23 preheater 4, R23 supply paths 2 and 27 merge with a diluent supply path 25 that supplies diluent from a diluent container 24 to the confluence point 28. In addition, between the TFE container 9 and the TFE heater 12, a TFE supply path 10 is provided to supply TFE from the TFE container 9 to the TFE heater 12. The R23 supply path 2, diluent supply path 25, and TFE supply path 10 are each provided with an R23 flow rate control device 3 to control the flow rate of R23, a diluent flow rate control device 26 to control the flow rate of the diluent, and a TFE flow rate control device 11 to control the flow path of TFE, respectively.

[0071] On the other hand, on the opposite side of the R23 supply channel 27 in the R23 preheater 4, the reactor 13 is provided via R23 supply channels 23 and 29. At the confluence point 22 located between the R23 preheater 4 and the reactor 13, the R23 supply channel 23 merges with the TFE supply channel 21, which supplies TFE from the TFE heater 12 to the confluence point 22, and becomes the R23 supply channel 29. On the opposite side of the R23 supply passage 29 in the reactor 13, a washing tower 15, a recovery unit 16, and an analysis device 17 are provided via a discharge passage 14.

[0072] In an example of the manufacturing method of this embodiment using the manufacturing apparatus 103 shown in Figure 4, R23 contained in the R23 container 1 and the diluent medium contained in the diluent medium container 24 are mixed at the confluence point 28 via the R23 supply path 2 and the diluent medium supply path 25, respectively, to form a diluted mixture. The content of the diluent medium in the diluted mixture is controlled by adjusting the flow rate of R23 and the flow rate of the diluent medium, respectively, using the R23 flow rate control device 3 and the diluent medium flow rate control device 26. The diluted mixture obtained at the confluence point 28 is supplied via the R23 supply channel 27 to the R23 preheater 4, which is heated to the first preheating temperature. The diluted mixture heated at the first preheating temperature in the R23 preheater 4 and the TFE heated at the TFE heating temperature in the TFE heater 12 are mixed at the confluence point 22 via the R23 supply channel 23 and the TFE supply channel 21, respectively, to form a post-contact mixture. The post-contact mixture obtained at the confluence point 22 is supplied further via the R23 supply channel 29 to the reactor 13, which is heated to the reaction temperature.

[0073] The diluted mixture, heated at the first preheating temperature, mixes with TFE at the confluence point 22 to form a post-contact mixture. At least a portion of the R23 in the post-contact mixture reacts with at least a portion of the TFE to form a product containing HFP. The post-contact mixture is then supplied to the reactor 13 and heated at the reaction temperature, causing the reaction between R23 and TFE to proceed further. In other words, the post-contact mixture reacts with R23 and TFE at the confluence point 22, and the reaction proceeds further due to heating in the reactor 13, resulting in a post-reaction composition containing at least the above product and the diluent.

[0074] In another example of the manufacturing method of this embodiment using the manufacturing apparatus 103 shown in Figure 4, HFP is manufactured without using a diluent. Specifically, the HFP is manufactured in the same manner as the HFP manufacturing method using a diluent, except that the flow rate of the diluent is set to 0 ml / min by the diluent flow rate control device 26. In this case, the R23 contained in the R23 container 1 passes directly through the confluence point 28 and is supplied to the R23 preheater 4.

[0075] (Other manufacturing equipment 4) The manufacturing apparatus shown in Figure 5 is used in the aforementioned manufacturing method in which R23 and a diluent are mixed in advance before the first preheating step, and the resulting diluted mixture is preheated to the first preheating temperature by heating a preheater, and then TFE is supplied separately to the reactor. Furthermore, the manufacturing apparatus shown in Figure 5 may also be used in a manufacturing method in which R23 is preheated directly to the first preheating temperature using a preheater without mixing R23 with a diluent.

[0076] The manufacturing apparatus 104 shown in Figure 5 differs from the manufacturing apparatus 103 shown in Figure 4 in that the R23 supply path 23 and the TFE supply path 21 do not merge, but are connected to separate supply ports in the reactor 13. Other components of the manufacturing apparatus 104 shown in Figure 5, namely the R23 container 1, R23 supply path 2, R23 flow rate control device 3, R23 preheater 4, dilution medium container 24, dilution medium supply path 25, dilution medium flow rate control device 26, TFE container 9, TFE supply path 10, TFE flow rate control device 11, TFE heater 12, reactor 13, discharge path 14, washing tower 15, recovery unit 16, and analysis device 17, are the same as those of the manufacturing apparatus 103 shown in Figure 4, so their explanation will be omitted.

[0077] In an example of the manufacturing method of this embodiment using the manufacturing apparatus 104 shown in Figure 5, similar to the manufacturing method described above, R23 and the diluent are mixed at the confluence point 28 to form a diluted mixture. The diluted mixture is heated at the first preheating temperature in the R23 preheater 4, which is heated to the first preheating temperature, and then supplied to the reactor 13, which is heated to the reaction temperature, via the R23 supply path 23. Meanwhile, the TFE heated to the TFE heating temperature in the TFE heater 12 is supplied to the reactor 13, which is heated to the reaction temperature, via the TFE supply passage 21, from a separate supply port from the diluted mixture. In this way, the diluted mixture and the TFE are supplied to the reactor 13, and the contact mixture is obtained by mixing them in the reactor 13.

[0078] In another example of the manufacturing method of this embodiment using the manufacturing apparatus 104 shown in Figure 5, HFP is manufactured without using a diluent. Specifically, the HFP is manufactured in the same manner as the HFP manufacturing method using a diluent, except that the flow rate of the diluent is set to 0 ml / min by the diluent flow rate control device 26. The R23 contained in the R23 container 1 passes directly through the confluence point 28 and is supplied to the R23 preheater 4. [Examples]

[0079] The embodiments of this disclosure will be described in detail below with reference to examples, but the embodiments of this disclosure are not limited to these.

[0080] [Examples 2-6] Using the manufacturing apparatus 100 shown in Figure 1, a product containing hexafluoropropene (HFP) was obtained using trifluoromethane (R23), tetrafluoroethylene (TFE), and nitrogen gas as a second preheating heat transfer medium by the method described below.

[0081] Trifluoromethane (R23) was supplied from R23 container 1 to R23 preheater 4, which was set to the first preheating temperature shown in Table 1, via R23 supply path 2. Meanwhile, nitrogen gas was supplied from the heat transfer medium container 5 to the heat transfer medium heater 8, which was set to the heat transfer medium heating temperature shown in Table 1, via the heat transfer medium supply passage 6. Furthermore, tetrafluoroethylene (TFE) was supplied from the TFE container 9 to the TFE heater 12, which was set to 150°C, via the TFE supply path 10.

[0082] The R23 preheated in the R23 preheater 4 and the nitrogen gas heated in the heat transfer medium heater 8 were mixed at the confluence point 20 of the R23 supply path 18 and the heat transfer medium supply path 19 to obtain a second preheated mixture. The resulting second preheated mixture and the TFE heated in the TFE heater 12 were supplied to the reactor 13, controlled to the reaction temperature and gauge pressure values ​​shown in Tables 1 and 2, via the R23 supply channel 18 and the TFE supply channel 21, respectively. The reaction time, i.e., the residence time in the reactor 13, is shown in Table 1.

[0083] The flow rates of R23, nitrogen gas, and TFE were adjusted using the R23 flow rate control device 3, the heat transfer medium flow rate control device 7, and the TFE flow rate control device 11, respectively. By adjusting the flow rates of R23, nitrogen gas, and TFE as described above, the content of R23, nitrogen gas, and TFE in the total mixture after contact was controlled to the values ​​shown in Table 1.

[0084] In the outlet gas (post-reaction composition) discharged from the reactor 13, in addition to the product generated by the reaction, unreacted raw materials R23 and TFE were also included. The post-reaction composition was supplied to the scrubbing tower 15 via the discharge path 14. In the scrubbing tower 15, the post-reaction composition was washed with distilled water to remove the acid components from the post-reaction composition. The post-reaction composition from which the acid components were removed was recovered by the recovery device 16, and the recovered post-reaction composition was analyzed by the analyzer 17. As the analyzer 17, gas chromatography (product name "GC-2014", manufactured by Shimadzu Corporation) and a capillary column (product name "PoraPLOT Q", manufactured by Agilent Technologies) were used.

[0085] From the results of analyzing the composition of the post-reaction composition by the analyzer 17, the contents of R23 and TFE as raw materials, HFP as the target product, and by-products C318, PFIB, C2F6, R125, and other products with respect to the entire components excluding nitrogen gas as the heat medium in the post-reaction composition were calculated. Specifically, based on the relative sensitivity of gas chromatography of each component, it was calculated so that the total of the components described in Table 1 became 100 mol%. The results are shown in Table 1. Also, the molar amount M of C318 contained in the post-reaction composition C318 with respect to the molar amount M of HFP HFP The ratio (M HFP / M C318 ) is also shown in Table 1.

[0086] [Examples 7 to 17] A post-reaction composition was obtained in the same manner as in Example 2, except that nitrogen gas as the heat medium for the second preheating was not used, and the contents of R23 and TFE with respect to the entire post-contact mixture, the first preheating temperature, the reaction temperature, the gauge pressure in the reactor, and the reaction time were set to the values shown in Tables 1 to 3. The composition of the obtained post-reaction composition was analyzed in the same manner as in Example 2, and the contents of R23, TFE, HFP, C318, PFIB, C2F6, R125, and other products with respect to the entire post-reaction composition were calculated. The results are shown in Tables 1 to 3. Also, the molar amount M of C318 contained in the post-reaction composition C318 with respect to the molar amount M of HFP HFPThe ratio (M HFP / M C318 The results are shown in Tables 1-3.

[0087] [Example 18] The reaction was carried out in the same manner as in Example 2, except that instead of R23, a mixed gas of 90 moles of R23 and 1.0 mole of R125 was used as the raw material gas contained in the R23 container 1, nitrogen gas was not used, and the first preheating temperature, reaction temperature, gauge pressure in the reactor, reaction time, and TFE content relative to the total post-contact mixture were set to the values ​​shown in Table 4. The composition of the resulting post-reaction composition was analyzed in the same manner as in Example 2, and the content of R23, TFE, HFP, C318, PFIB, C2F6, R125, and other products relative to the total post-reaction composition was calculated. The results are shown in Table 4. In addition, the molar amount M of C318 contained in the post-reaction composition was calculated. C318 Molar amount M of HFP relative to HFP The ratio (M HFP / M C318 ) are also shown in Table 4.

[0088] [Example 1] Using the manufacturing apparatus 102 shown in Figure 3, a product containing hexafluoropropene (HFP) was obtained using trifluoromethane (R23), tetrafluoroethylene (TFE), and nitrogen gas as a reaction heat transfer medium by the method described below.

[0089] Trifluoromethane (R23) was supplied from R23 container 1 to R23 preheater 4, which was set to the first preheating temperature shown in Table 1, via R23 supply path 2. Meanwhile, nitrogen gas was supplied from the heat transfer medium container 5 to the heat transfer medium heater 8, which was set to the heat transfer medium heating temperature shown in Table 1, via the heat transfer medium supply passage 6. Furthermore, tetrafluoroethylene (TFE) was supplied from the TFE container 9 to the TFE heater 12, which was set to 150°C, via the TFE supply path 10.

[0090] R23 preheated in the R23 preheater 4, nitrogen gas heated in the heat transfer medium heater 8, and TFE heated in the TFE heater 12 were mixed at the confluence point 20 of the R23 supply path 18, the heat transfer medium supply path 19, and the TFE supply path 21, and a mixture was obtained after contact. The resulting post-contact mixture was supplied via the R23 supply channel 23 to reactor 13, which was controlled to the reaction temperature and gauge pressure values ​​shown in Table 1. The reaction time, i.e., the residence time in reactor 13, is shown in Table 1. The flow rates of R23, nitrogen gas, and TFE were adjusted using the R23 flow rate control device 3, the heat transfer medium flow rate control device 7, and the TFE flow rate control device 11, respectively. By adjusting the flow rates of R23, nitrogen gas, and TFE as described above, the content of R23, nitrogen gas, and TFE in the total mixture after contact was controlled to the values ​​shown in Table 1.

[0091] The outlet gas (post-reaction composition) discharged from reactor 13 contained not only the products generated by the reaction, but also unreacted raw materials, R23 and TFE. The composition of the resulting post-reaction composition was analyzed in the same manner as in Example 2, and the content of R23, TFE, HFP, C318, PFIB, C2F6, R125, and other products was calculated relative to the total components of the post-reaction composition excluding the nitrogen gas, which was the heat transfer medium. The results are shown in Table 1. In addition, the molar amount M of C318 contained in the post-reaction composition was calculated. C318 Molar amount M of HFP relative to HFP The ratio (M HFP / M C318 ) are also shown in Table 1.

[0092] [Table 1]

[0093] [Table 2]

[0094] [Table 3]

[0095] [Table 4]

[0096] In the above examples, Examples 1-16 and 18 are examples, and Example 17 is a comparative example. As shown in Tables 1-4, the molar amount M of C318 in Examples 1-16 and 18 is different from that in Example 17. C318 Molar amount M of HFP relative to HFP The ratio (M HFP / M C318 The high level of C318 indicates that its formation is suppressed. [Explanation of Symbols]

[0097] 1 R23 enclosure 2 R23 supply line 3 R23 Flow Control Device 4 R23 Preheater 5. Heat transfer medium container 6 Heat medium supply path 7. Heat transfer fluid flow control device 8 Heat medium heater 9 TFE enclosure 10 TFE supply line 11 TFE Flow Control Device 12 TFE heater 13 Reactor 14 Exhaust channel 15 Washing Tower 16 Recovery unit 17 Analyzer 18, 23, 27, 29 R23 supply route 19 Heat medium supply path 20, 22, 28 confluence 21 TFE supply line 24 Dilution medium container 25 Dilution medium supply channel 26 Dilution medium flow control device 100, 101, 102, 103, 104 Manufacturing equipment

Claims

1. A method for producing hexafluoropropene, comprising preheating trifluoromethane at a first preheating temperature of 350 to 700°C, then contacting it with tetrafluoroethylene to obtain a product containing hexafluoropropene.

2. A method for producing hexafluoropropene according to claim 1, comprising contacting tetrafluoroethylene with a mixture obtained by mixing trifluoromethane preheated at the first preheating temperature with a second preheating heat transfer medium heated at a second preheating heat transfer medium heating temperature higher than the first preheating temperature.

3. The method for producing hexafluoropropene according to claim 2, wherein the heating temperature of the second preheating heat transfer medium is 1100°C or lower.

4. The method for producing hexafluoropropene according to claim 2, wherein the amount of the second preheating heat transfer medium added is 50 mol% or less of the total amount of the tetrafluoroethylene, the trifluoromethane preheated at the first preheating temperature, and the second preheating heat transfer medium.

5. The method for producing hexafluoropropene according to claim 1, wherein the contact is carried out by mixing trifluoromethane preheated at the first preheating temperature, a reaction heat medium heated at a reaction heat medium heating temperature higher than the first preheating temperature, and the tetrafluoroethylene.

6. The method for producing hexafluoropropene according to claim 5, wherein the heating temperature of the reaction heat medium is 1100°C or lower.

7. The method for producing hexafluoropropene according to claim 5, wherein the amount of the reaction heat medium added is 50 mol% or less of the total amount of the tetrafluoroethylene, the trifluoromethane preheated at the first preheating temperature, and the reaction heat medium.

8. A method for producing hexafluoropropene according to any one of claims 1 to 7, further comprising heating a mixture obtained by contacting trifluoromethane preheated at the first preheating temperature with tetrafluoroethylene in a reactor at a reaction temperature of 800 to 1000°C.

9. The method for producing hexafluoropropene according to claim 8, wherein the heating time at the reaction temperature is 5 seconds or less.

10. The method for producing hexafluoropropene according to claim 8, wherein the gauge pressure in the reactor is 0 kPaG or more and less than 200 kPaG.

11. The product further comprises octafluorocyclobutane, A method for producing hexafluoropropene according to any one of claims 1 to 7, wherein the ratio of the molar amount of hexafluoropropene contained in the product to the molar amount of octafluorocyclobutane contained in the product is 5.0 or more.

12. The aforementioned product further comprises perfluoroisobutene, A method for producing hexafluoropropene according to any one of claims 1 to 7, wherein the ratio of the molar amount of hexafluoropropene contained in the product to the molar amount of perfluoroisobutene contained in the product is 0.9 or more.

13. A composition comprising trifluoromethane, tetrafluoroethylene, hexafluoropropene, and octafluorocyclobutane, The total content of trifluoromethane, tetrafluoroethylene, hexafluoropropene, and octafluorocyclobutane is 98.7 mol% or more of the total composition. A composition in which the ratio of the molar amount of hexafluoropropene to the molar amount of octafluorocyclobutane is 5.0 or greater.

14. Furthermore, it contains perfluoroisobutene, The composition according to claim 13, wherein the ratio of the molar amount of hexafluoropropene to the molar amount of perfluoroisobutene is 0.9 or more.

15. The composition according to claim 13 or 14, further comprising at least one selected from the group consisting of pentafluoroethane and hexafluoroethane.

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