WO2024176771A1

WO2024176771A1 - Vinylidene fluoride production method and vinylidene fluoride production device

Info

Publication number: WO2024176771A1
Application number: PCT/JP2024/003330
Authority: WO
Inventors: 英史塩田; 哲央大塚; 覚人三竹; 達也鎌塚; 明日香山川
Original assignee: Ａｇｃ株式会社
Priority date: 2023-02-20
Filing date: 2024-02-01
Publication date: 2024-08-29

Abstract

A vinylidene fluoride production method for producing vinylidene fluoride, in the presence of a heat medium, from a source material composition that includes chlorodifluoromethane and chloromethane by using a synethesis method that accompanies thermal decomposition, said method including a step in which the source material composition and a heat medium are brought into contact in a reaction vessel for a contact time of 0.2 seconds or less.

Description

Manufacturing method and apparatus for producing vinylidene fluoride

This disclosure relates to a method for producing vinylidene fluoride and an apparatus for producing vinylidene fluoride.

Vinylidene fluoride is useful as a monomer for fluororesins.

For example, Patent Document 1 describes a method for producing 2,3,3,3-tetrafluoropropene (HFO-1234yf) from a raw material composition containing chlorodifluoromethane (R22) and chloromethane (R40) in the presence of a heat transfer medium through a synthesis reaction involving thermal decomposition, the method comprising the steps of (a) premixing 0.01 to 3 moles of R40 per mole of R22 or separately supplying the mixture to a reactor and allowing the mixture to remain in the reactor for a predetermined period of time, and (b) supplying a heat transfer medium to the reactor and bringing the raw material composition into contact with the heat transfer medium in the reactor.

JP 2014-114214 A

However, in Patent Document 1, the objective is to produce HFO-1234yf, and vinylidene fluoride (VdF) is considered a by-product, so there was a demand for a production method aimed at producing VdF. In addition, there was a demand for reducing the by-product acetylene in the production of VdF.

The objective of one embodiment of the present invention is to provide a method and apparatus for producing VdF that can reduce the amount of by-product acetylene.

The present disclosure includes the following aspects.
＜1＞
A method for producing VdF by a synthesis method involving thermal decomposition from a raw material composition containing chlorodifluoromethane and chloromethane in the presence of a heat transfer medium, comprising the steps of:
A method for producing VdF, comprising a step of contacting a raw material composition with a heat transfer medium in a reactor for a contact time of 0.2 seconds or less.
＜2＞
The method for producing VdF according to <1>, wherein the acetylene content relative to the VdF content in the outlet gas discharged from the reactor is 20 mol % or less.
＜3＞
The method for producing VdF according to <1> or <2>, wherein the temperature in the reactor is 800° C. or higher.
＜4＞
The method for producing VdF according to any one of <1> to <3>, wherein the contact time is 0.1 seconds or less.
＜5＞
The method for producing VdF according to any one of <1> to <4>, wherein the contact time is 0.01 seconds or more.
＜6＞
When the temperature in the reactor is x°C and the contact time is y seconds,
The method for producing VdF according to any one of <1> to <5>, which satisfies the following formulas 1 and 2:
y≦-0.001x+1.05...Formula 1
850≦x≦950…Formula 2
＜７＞
The method for producing VdF according to any one of <1> to <6>, wherein the ratio of the molar amount of chloromethane to the molar amount of chlorodifluoromethane is 1 or more.
＜8＞
a reactor for contacting a raw material composition containing chlorodifluoromethane and chloromethane with a heat transfer medium;
a chlorodifluoromethane supply section that contains chlorodifluoromethane and supplies the chlorodifluoromethane to the reactor;
a chloromethane supply section that contains chloromethane and supplies the chloromethane to the reactor;
a heat transfer medium supplying section that accommodates a heat transfer medium and supplies the heat transfer medium to the reactor;
A control unit that controls the contact time between the raw material composition and the heat transfer medium in the reactor to 0.2 seconds or less.

According to one embodiment of the present invention, a method and apparatus for producing VdF are provided that can reduce the amount of by-product acetylene.

FIG. 1 is a diagram showing an example of a VdF manufacturing apparatus according to the present disclosure.

In the present disclosure, a numerical range indicated using "to" means a range that includes the numerical values before and after "to" as the minimum and maximum values, respectively.
In the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in the present disclosure. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.
In the present disclosure, a combination of two or more preferred aspects is a more preferred aspect.
In the present disclosure, when there are multiple substances corresponding to each component, the amount of each component means the total amount of multiple substances, unless otherwise specified.

[Method of manufacturing VdF]
The method for producing VdF disclosed herein is a method for producing VdF from a raw material composition containing R22 and R40 in the presence of a heat transfer medium by a synthesis method involving thermal decomposition, and includes a step of contacting the raw material composition with the heat transfer medium in a reactor for a contact time of 0.2 seconds or less.

According to the method for producing VdF disclosed herein, the content of acetylene produced as a by-product can be reduced by contacting the raw material composition with the heat transfer medium in the reactor for a contact time of 0.2 seconds or less.

The boiling point of VdF is −83° C., and the boiling point of acetylene is −84° C. Since the boiling points of VdF and acetylene are close to each other, it is difficult to separate and purify VdF and acetylene, and therefore, in the method for producing VdF, it is desirable to have a low content of acetylene as a by-product.
On the other hand, the production method described in Patent Document 1 aims to produce HFO-1234yf, and does not focus on acetylene because the boiling points of HFO-1234yf and acetylene are significantly different. Furthermore, Patent Document 1 does not mention the content of acetylene produced as a by-product in the production of VdF.

<Raw Material Composition>
The feed composition includes R22 and R40.
A raw material composition containing R22 and R40 undergoes thermal decomposition and dehydrochlorination reactions in a reactor to produce a reaction mixture containing difluorocarbene (F ₂ C:) and R40, and it is believed that this reaction mixture undergoes a direct addition reaction or is converted to VdF via one or more intermediates.

In the raw material composition, the ratio of the molar amount of R40 to the molar amount of R22 (R40/R22) is not particularly limited, but from the viewpoint of further reducing the content of by-produced acetylene, it is preferably 1 or more, more preferably 2 or more, and even more preferably 3.5 or more.

The upper limit of R40/R22 is not particularly limited, but from the viewpoint of ensuring a certain level of VdF content in the outlet gas, it is preferably 8 or less, and more preferably 6 or less.

The raw material composition may contain components other than R22 and R40.
As the components other than R22 and R40, fluorine-containing compounds capable of generating difluorocarbene by thermal decomposition in a reactor are preferred, and examples thereof include HFO-1234yf, tetrafluoroethylene (TFE), hexafluoropropene (HFP), octafluorocyclobutane (RC318), chlorotrifluoroethylene (CTFE), trifluoroethylene, and hexafluoropropylene oxide (HFPO). When the above-mentioned fluorine-containing compounds are used in the raw material composition, a newly prepared fluorine-containing compound may be used, but from the viewpoint of recycling, it is preferred to use at least one fluorine-containing compound by-produced in the production method of the present disclosure, for example, selected from the group consisting of HFO-1234yf, TFE, HFP, RC318, CTFE, and trifluoroethylene.

In the disclosed method for producing VdF, the outlet gas of the reactor contains unreacted raw materials, reaction products, and a heat transfer medium. By separating the heat transfer medium and the target product VdF from the outlet gas, and further removing by-products other than fluorine-containing compounds that can be thermally decomposed in the reactor to produce difluorocarbene, a composition is obtained that is mainly composed of the unreacted raw materials R22 and R40, HFO-1234yf, TFE, HFP, RC318, CTFE, and trifluoroethylene. Supplying this composition to the reactor makes it possible to recycle, which is economically advantageous.

The raw material composition may be introduced into the reactor at room temperature, but in order to improve the reactivity in the reactor, the temperature when introduced into the reactor may be adjusted by heating or the like. However, since the fluorine-containing compound capable of generating difluorocarbene containing R22 and R40 have different temperature ranges suitable for improving the reactivity, it is preferable to adjust the temperatures separately.

The temperature of R22 supplied to the reactor, or the temperature of the fluorine-containing compound capable of producing difluorocarbene containing R22 supplied to the reactor, is preferably 0 to 600° C. from the viewpoint of a temperature at which the reactivity is somewhat high but carbonization is difficult.
From the viewpoint of enhancing reactivity, R22 or a fluorine-containing compound capable of producing a difluorocarbene containing R22 is preferably heated to 50° C. or higher, more preferably 100 to 500° C., before being introduced into a reactor.

From the viewpoint of reactivity, the temperature of R40 supplied to the reactor is preferably 0 to 1200° C. From the viewpoint of increasing the reactivity, it is preferable to heat R40 to 50 to 1200° C., and more preferably to heat R40 to 100 to 800° C. before introducing it into the reactor.
However, the temperature of each of the raw material components supplied to the reactor is set to be equal to or lower than the temperature inside the reactor, which will be described later.

The raw materials R22, R40, and the fluorine-containing compound capable of producing difluorocarbene, which is used as necessary, may be supplied to the reactor separately, or after mixing the components. When the components are mixed and then supplied, the raw material composition may be divided into groups, for example, fluorine-containing compounds capable of producing difluorocarbene and others, and the components in each group may be mixed and supplied separately to the reactor, or all the components may be mixed and then supplied. Considering the difference in temperature conditions described above, it is preferable to supply the fluorine-containing compound capable of producing difluorocarbene, including R22, and R40 to the reactor after adjusting them to their preferred temperature conditions.

In addition, when the raw materials such as R22, R40, and optionally a fluorine-containing compound capable of producing difluorocarbene are mixed in advance and then fed to the reactor, the temperature at which they are introduced into the reactor is preferably less than 600°C, and more preferably less than 500°C, in order to prevent the reaction or decomposition from proceeding before the reactor.

<Heat medium>
The heat medium is a medium that does not undergo thermal decomposition at the temperature in the reactor, and specifically, is preferably a medium that does not undergo thermal decomposition at a temperature of 100 to 1200° C. The heat medium may be at least one gas selected from the group consisting of water vapor, nitrogen, hydrogen fluoride, and carbon dioxide. From the viewpoint of removing hydrogen chloride produced in the thermal decomposition reaction as hydrochloric acid, the heat medium is preferably water vapor. The proportion of water vapor in the heat medium is preferably 50% by volume or more, and the heat medium is more preferably composed of only water vapor.

The ratio of the number of moles of water vapor to the total number of moles of the raw material composition is preferably 0.5 or more, more preferably 0.6 or more, and even more preferably 0.7 or more, from the viewpoint of preventing clogging of the reactor by carbon generated in the reaction. The upper limit of the above ratio is, for example, 0.99.

In the VdF production method of the present disclosure, the contact time between the raw material composition and the heat transfer medium in the reactor is 0.2 seconds or less. From the viewpoint of further reducing the content of by-produced acetylene, the contact time is preferably 0.1 seconds or less, more preferably 0.08 seconds or less. From the viewpoint of ensuring a certain level of VdF content in the outlet gas, the contact time is preferably 0.01 seconds or more. The contact time between the raw material composition and the heat transfer medium corresponds to the residence time of the raw material composition in the reactor, and can be controlled by adjusting the flow rate of the raw material composition.
The contact time (seconds) is calculated using the following formula:
Contact time (seconds) = [volume of raw material composition at reaction temperature per second supplied to reactor] / [volume of reactor]

<Reactor>
The reactor is not particularly limited in shape as long as it can withstand the temperature and pressure in the reactor described below, and may be, for example, a cylindrical vertical reactor. The reactor may be made of glass, iron, nickel, or an alloy mainly composed of iron or nickel.

From the viewpoint of improving the conversion rate of the raw material composition to VdF, the temperature inside the reactor is preferably 800°C or higher, and more preferably 850°C or higher. On the other hand, from the viewpoint of reducing capital investment for increasing the temperature inside the reactor, the temperature inside the reactor is preferably 1000°C or lower. From these viewpoints, the temperature inside the reactor is preferably 850 to 950°C.

In particular, when the temperature inside the reactor is x° C. and the contact time is y seconds, it is preferable that the following formulas 1 and 2 are satisfied.
y≦-0.001x+1.05...Formula 1
850≦x≦950…Formula 2

From the viewpoint of further reducing the content of by-produced acetylene, it is more preferable that the following formula 1A and the above formula 2 are satisfied, and it is even more preferable that the following formula 1B and the above formula 2 are satisfied.
y≦-0.001x+1.00...Formula 1A
y≦-0.001x+0.95...Formula 1B

From the viewpoint of reducing capital investment required to improve the pressure resistance of the reactor, etc., the pressure inside the reactor is preferably 0 to 2.0 MPa, more preferably 0 to 0.5 MPa, even more preferably 0 to 0.3 MPa, and particularly preferably 0 to 0.2 MPa, in terms of gauge pressure.

<Outlet gas>
In the method for producing VdF disclosed herein, VdF can be obtained as an outlet gas discharged from a reactor. Examples of components other than VdF contained in the outlet gas include acetylene, methane, ethylene, HFO-1234yf, TFE, HFP, CTFE, trifluoroethylene, RC318, 1,3,3,3-tetrafluoropropene (HFO-1234ze), and 1,2-difluoroethylene.

In the outlet gas discharged from the reactor, the acetylene content relative to the VdF content is preferably 20 mol% or less, and more preferably 15 mol% or less.

The above components other than VdF contained in the outlet gas can be removed to the desired extent by known means such as distillation. The separated TFE, HFP, CTFE, trifluoroethylene, and RC318 are fluorine-containing compounds capable of producing difluorocarbene, and can be recycled as part of the raw material composition.

[VdF manufacturing equipment]
The VdF production apparatus of the present disclosure includes a reactor that brings a raw material composition containing R22 and R40 into contact with a heat transfer medium, an R22 supplying section that contains R22 and supplies R22 to the reactor, an R40 supplying section that contains R40 and supplies R40 to the reactor, a heat transfer medium supplying section that contains a heat transfer medium and supplies the heat transfer medium to the reactor, and a control section that controls the contact time between the raw material composition and the heat transfer medium in the reactor to 0.2 seconds or less.

The VdF manufacturing apparatus disclosed herein may be of a continuous type or a batch type.

In a continuous system, the supply of each raw material to the reactor and the supply of the heat transfer medium to the reactor are both carried out continuously. In a batch system, the supply of each raw material to the reactor and the supply of the heat transfer medium to the reactor may be either one first or simultaneously.

From the standpoint of production efficiency, the continuous method is preferred.

FIG. 1 shows an example of a VdF manufacturing apparatus according to the present disclosure.

The manufacturing apparatus 100 has an R40 supply section 51 in which R40 is stored, an R22 supply section 52 in which R22 is stored, a steam supply section 53 in which steam is stored as a heat medium, a reactor 1 equipped with a heating means such as an electric heater, and a control section 12. An R40 supply line 2, an R22 supply line 3, and a steam supply line 4 are connected to the reactor 1. Note that the installation of a heating means in the reactor 1 is not essential.

The R40 supply line 2 and the R22 supply line 3 are provided with preheaters 2a and 3a equipped with electric heaters or the like, respectively, so that the raw materials supplied from the R40 supply unit 51 and the R22 supply unit 52 are preheated to a predetermined temperature and then supplied to the reactor 1. In addition, the steam supply line 4 is provided with a superheated steam generator 4a, and the steam supplied from the steam supply unit 53 is mixed with the superheated steam, thereby adjusting the temperature and pressure of the supplied steam.
The water vapor contained in the water vapor supply unit 53 may be supplied to the reactor as it is, or may be heated and then supplied to the reactor in a heated state. As a method for heating the water vapor contained in the water vapor supply unit 53, in addition to the method of mixing the water vapor with superheated steam as described above, a method of heating the water vapor using a heater may be mentioned.
Furthermore, the water vapor contained in the water vapor supply unit 53 may be subjected to a phase change (for example, water, water vapor, or both water and water vapor) and then supplied to the reactor.

An R40 supply unit 51 is connected to the R40 supply line 2. R40 is accommodated in the R40 supply unit 51. The R40 supply unit 51 has a function of supplying R40 to the reactor 1. The R40 supply unit 51 and the reactor 1 may be directly connected to each other, or may be connected to each other via a preheater 2a and an R40 supply line 2 as shown in FIG. 1.
An R22 supply unit 52 is connected to the R22 supply line 3. R22 is accommodated in the R22 supply unit 52. The R22 supply unit 52 has a function of supplying R22 to the reactor 1. The R22 supply unit 52 and the reactor 2 may be directly connected to each other, or may be connected to each other via a preheater 3a and an R22 supply line 3 as shown in FIG.
A water vapor supply unit 53 is connected to the water vapor supply line 4. Water vapor is accommodated in the water vapor supply unit 53. The water vapor supply unit 53 has a function of supplying water vapor to the reactor 1. The water vapor supply unit 53 and the reactor 1 may be directly connected to each other, or may be connected to each other via a superheated steam generator 4a and a water vapor supply line 4 as shown in FIG. 1 .

The supply lines 2, 3, and 4 may each be connected separately to the reactor 1, but as shown in FIG. 1, the supply lines 2, 3, and 4 may be connected after passing through the preheaters 2a and 3a and the superheated steam generator 4a, so that all the components are mixed and then supplied to the reactor 1 via the raw material/steam mixture supply line 5.

The outlet of the reactor 1 is connected to an outlet line 7 equipped with a cooling means 6 such as a water cooler. The outlet line 7 is further equipped with a steam and acid liquid recovery tank 8, an alkaline washing device 9, and a dehydration tower 10, in that order. After being dehydrated by the dehydration tower 10, each component of the outlet gas is analyzed and quantified by an analysis device 11 such as a gas chromatography (GC).

The control unit 12 controls the contact time between the raw material composition and the heat medium to 0.2 seconds or less. Specifically, it controls the flow rate (supply rate) of each raw material and the flow rate (supply rate) of the heat medium so that the contact time between the raw material composition and the heat medium is 0.2 seconds or less.

Below, the present disclosure will be specifically explained using examples, but the present disclosure is not limited to these examples. Examples 1 to 11 are examples, and Examples 12 to 14 are comparative examples.

[Example 1]
Using the production apparatus shown in FIG. 1, VdF was obtained from a raw material composition (hereinafter also referred to as raw material gas) consisting of R22 and R40 by the method described below.

R40 was continuously introduced into a stainless steel tube in an electric furnace with an internal temperature set to 500°C, and the R40 was heated to 500°C. R22 was continuously introduced into a stainless steel tube in an electric furnace with an internal temperature set to 500°C, and the R22 was heated to 500°C.

The raw material gas, which had been preheated and adjusted to the above temperature, and steam (water vapor) heated by an electric furnace set to an internal temperature of 800°C were supplied to the reactor so that the ratio of the molar amount of R40 to the molar amount of R22 (R40/R22) was 4, and the ratio of the molar amount of water vapor to the total number of moles of R22 and R40 (water vapor/(R22+R40)) was 6. The temperature inside the reactor was 800°C, and the pressure was 0.014 MPa in gauge pressure.

The flow rate of the raw material gas was controlled so that the contact time between the raw material gas and the water vapor in the reactor was 0.2 seconds. The outlet gas discharged from the reactor contained unreacted raw material gas in addition to the gases produced or by-produced by the reaction.

The outlet gas was cooled to below 100°C, and after the steam and acidic liquid were collected and the gas was washed with alkali, it was dehydrated and then analyzed by gas chromatography to calculate the molar composition of the components contained in the outlet gas. The calculation results are shown in Tables 1 and 2, along with the reaction conditions.

In addition, the acetylene content relative to the VdF content (acetylene/VdF) was calculated based on the molar composition of the outlet gas obtained by gas chromatography analysis.

[Examples 2 to 14]
In Examples 2 to 14, the reaction was carried out in the same manner as in Example 1, except that the reaction temperature, contact time, reaction pressure, steam/(R22+R40), and R40/R22 were changed to the values shown in Tables 1 and 2.

As shown in Tables 1 and 2, in Examples 1 to 11, VdF is produced by a synthesis method involving thermal decomposition from a raw material composition containing R22 and R40 in the presence of a heat transfer medium, and it was found that the content of by-product acetylene can be reduced by contacting the raw material composition with the heat transfer medium in the reactor for a contact time of 0.2 seconds or less.

In Examples 12 to 14, the contact time between the raw material composition and the heat transfer medium was more than 0.2 seconds, and it was found that the content of by-produced acetylene was high.
The examples in Patent Document 1 disclose examples in which the contact times of the raw material compositions containing R22 and R40 with the heat transfer medium are both longer than 0.2 seconds, and a composition with a high acetylene content is obtained.

The disclosure of Japanese Patent Application No. 2023-024581, filed on February 20, 2023, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

A method for producing vinylidene fluoride from a raw material composition containing chlorodifluoromethane and chloromethane by a synthesis method involving thermal decomposition in the presence of a heat transfer medium, comprising the steps of:
A method for producing vinylidene fluoride, comprising the step of contacting the raw material composition with the heat transfer medium in a reactor for a contact time of 0.2 seconds or less.
The method for producing vinylidene fluoride according to claim 1, wherein the acetylene content relative to the vinylidene fluoride content in the outlet gas discharged from the reactor is 20 mol% or less.
The method for producing vinylidene fluoride according to claim 1 or 2, wherein the temperature inside the reactor is 800°C or higher.
The method for producing vinylidene fluoride according to claim 1 or 2, wherein the contact time is 0.1 seconds or less.
The method for producing vinylidene fluoride according to claim 1 or 2, wherein the contact time is 0.01 seconds or more.
When the temperature in the reactor is x° C. and the contact time is y seconds,
The method for producing vinylidene fluoride according to claim 1 or 2, which satisfies the following formulae 1 and 2:
y≦-0.001x+1.05...Formula 1
850≦x≦950…Formula 2
The method for producing vinylidene fluoride according to claim 1 or 2, wherein the ratio of the molar amount of chloromethane to the molar amount of chlorodifluoromethane is 1 or more.
a reactor for contacting a raw material composition containing chlorodifluoromethane and chloromethane with a heat transfer medium;
a chlorodifluoromethane supply section containing the chlorodifluoromethane and supplying the chlorodifluoromethane to the reactor;
a chloromethane supply section that contains the chloromethane and supplies the chloromethane to the reactor;
a heat medium supplying section that accommodates the heat medium and supplies the heat medium to the reactor;
a control unit that controls a contact time between the raw material composition and the heat transfer medium in the reactor to 0.2 seconds or less.