Method and device for continuously synthesizing and purifying hexafluoropropylene oxide

Abstract

The invention discloses a continuous synthesis and purification method of hexafluoropropylene oxide, which comprises the following steps: introducing hexafluoropropylene, oxygen and a fluorine-containing solvent into a supergravity reactor to carry out oxidation reaction at the reaction temperature of 100-200 DEG C under the reaction pressure of 1.0-2.5 Mpa for 10-120 seconds, and after the reaction is finished, overflowing and leading out reaction liquid to obtain the hexafluoropropylene oxide. And purifying to obtain the hexafluoropropylene oxide. According to the method, the problems of mass transfer and heat transfer can be effectively solved by using the supergravity reactor, the reaction selectivity is remarkably improved, meanwhile, the productivity is effectively improved, and the supergravity reactor is combined with extractive distillation treatment, so that the conversion rate of the hexafluoropropylene reaches 79% or above, the selectivity of the hexafluoropropylene oxide is 85% or above, and the purity of the hexafluoropropylene oxide after extractive distillation reaches 99%. The invention further discloses a device used in the continuous synthesis and purification method, and cyclic utilization of hexafluoropropylene and the fluorine-containing solvent can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of fluorine-containing fine chemicals, and specifically relates to a continuous synthesis and purification method and device for hexafluoropropylene oxide. Background Art

[0002] Hexafluoropropylene oxide (C 3 F 6 O, HFPO), also known as perfluoropropylene oxide or hexafluoropropylene oxide, due to its unique cyclic structure has high chemical activity, can undergo selective ring opening to generate different intermediates, and is one of the important intermediates for producing organic fluorine materials. It can be used to synthesize important fluorine-containing compounds such as perfluorinated ion exchange resins, fluoroplastics, fluororubbers, fluorosurfactants, fluorinated lubricants, and high-grade cleaning agents, and is widely used in the fields of aerospace, electronics, medicine, etc.

[0003] In the prior art, basically hexafluoropropylene (HFP) is used as a raw material to react with different oxidants to prepare hexafluoropropylene oxide. When using oxygen as an oxidant, the selection of the reactor is very important.

[0004] Asahi Glass Company in Japan selected perfluorocarboxylic acid fluoride as a solvent and prepared HFPO in a Hastelloy autoclave at 140 - 170°C and 2 - 4 MPa. The conversion rate of HFP was 46% - 73%, and the selectivity of HFPO was 65% - 68%. DuPont mentioned using perfluorocycloalkanes (such as perfluorodimethylcyclobutane) as solvents, with the conversion rate of HFP being 47 - 72.5% and the selectivity of HFPO being 58.5 - 59%.

[0005] Chinese patent document with the publication number CN104672177A discloses a process for continuously producing hexafluoropropylene oxide using a microchannel reactor, using a suitable fluorocarbon solvent as a supercritical fluid to oxidize HFP, with a short induction period, fast reaction rate, and stable reaction. When using HFC-236fa as a supercritical fluid, at a reaction temperature of 130°C and a reaction time of 12 h, the conversion rate of HFP was 97.1%, and the selectivity of HFPO was 64%.

[0006] Chinese patent document with the publication number CN1966498A discloses a preparation method for hexafluoropropylene oxide, using fluorocarbon cyclic ethers (such as perfluorobutylcyclopentane, perfluoropropylperfluorocyclohexane, etc.) as reaction solvents, reacting for 2 - 3.5 h, and when the conversion rate of HFP was 96%, the selectivity of HFPO was 70%.

[0007] Most of the existing processes for preparing hexafluoropropylene oxide by liquid-phase oxidation with oxygen use a batch reactor. First, a solvent and hexafluoropropylene are added to the reactor, and then oxygen is added in batches multiple times until the conversion rate of hexafluoropropylene reaches 85% - 95%. This method has a long reaction time, is difficult to produce continuously, and has poor reaction selectivity, only 65% - 68%. Due to the existence of the gas phase space and the limitation of the stirring efficiency in the traditional batch reaction, the heat generated by the reaction cannot be effectively transferred, and hot spot phenomena are extremely likely to occur in the reaction system, resulting in the high-temperature decomposition of the reaction products and a decrease in selectivity. At the same time, the existence of the gas phase space will cause a violent reaction between oxygen and gaseous hexafluoropropylene, resulting in an oxygen explosion phenomenon, bringing greater safety risks to production. Although the tubular reaction solves some problems of the batch reaction, with improved safety and selectivity, the raw material conversion rate is not high, and the production capacity is greatly limited.

[0008] Therefore, there is an urgent need to find a method that can improve the conversion rate of hexafluoropropylene and the selectivity of hexafluoropropylene oxide, while also avoiding the risks of runaway temperature and oxygen explosion. Summary of the Invention

[0009] To solve the above technical problems, the present invention provides a continuous synthesis and purification method for hexafluoropropylene oxide. This method uses a high-gravity reactor as the reaction device, which can effectively solve the problems of mass transfer and heat transfer, significantly improve the selectivity of the reaction, and effectively increase the production capacity at the same time. Combined with extractive distillation treatment, the conversion rate of hexafluoropropylene reaches more than 79%, the selectivity of hexafluoropropylene oxide is above 85%, and the purity of hexafluoropropylene oxide after extractive distillation is as high as 99%.

[0010] A continuous synthesis and purification method for hexafluoropropylene oxide includes the following steps:

[0011] Hexafluoropropylene, oxygen, and a fluorinated solvent are introduced into a high-gravity reactor for an oxidation reaction. Among them, the reaction temperature is 100 - 200 °C, the reaction pressure is 1.0 - 2.5 Mpa, the reaction residence time is 10 - 120 s. After the reaction, the reaction solution is overflowed and led out, and after purification treatment, hexafluoropropylene oxide is obtained.

[0012] In the present invention, a high-gravity reactor is used as the reaction device. Hexafluoropropylene, oxygen, and a fluorinated solvent are introduced into the high-gravity reactor for an oxidation reaction, and high-purity hexafluoropropylene oxide is prepared after purification treatment. The use of a high-gravity reactor in the present invention can effectively solve the problems of mass transfer and heat transfer, significantly improve the selectivity of the reaction, and effectively increase the production capacity at the same time. Combined with extractive distillation treatment, the conversion rate of hexafluoropropylene reaches more than 79%, the selectivity of hexafluoropropylene oxide is above 85%, and the purity of hexafluoropropylene oxide after extractive distillation is as high as 99%.

[0013] Preferably, the high-gravity reactor is a gas-liquid type high-gravity reactor.

[0014] The gas-liquid type high gravity reactor used in the present invention can be purchased or customized on the market. If customized, measures such as optimization and strengthening, compression of the gas phase space, and addition of cooling coils can be taken to enhance heat transfer and further improve the reaction effect.

[0015] Further preferably, the material of the high gravity reactor is stainless steel, Hastelloy or Monel alloy.

[0016] Preferably, the fluorinated solvent is hexafluoropropylene dimer, hexafluoropropylene trimer, hexafluoropropyl difluorovinyl ether (CF 3 CFHCF 2 OCH=CF 2 )、CHF 2 CF=CHOCF 2 CF 2 H、CF 2 =CFCH 2 OCF 2 CF 2 H、CF 2 =CHOCF 2 CF 2 H, or one of them.

[0017] In the present invention, the synthesis method of CHF 2 CF=CHOCF 2 CF 2 H、CF 2 =CFCH 2 OCF 2 CF 2 H、CF 2 =CHOCF 2 CF 2 H refers to the Chinese patent document with the publication number CN108101754A.

[0018] Preferably, the mass ratio of the hexafluoropropylene, oxygen and fluorinated solvent is 1: 0.1-0.2: 5-20.

[0019] Preferably, the purification treatment is to remove the light components from the reaction solution after the reaction, collect the light removal liquid, extract the light removal liquid with an extractant, and then separate out hexafluoropropylene oxide.

[0020] Further preferably, the light components include carbonyl fluoride, trifluoroacetyl fluoride and oxygen.

[0021] In the present invention, the product is hexafluoropropylene oxide. Relative to the product, carbonyl fluoride, trifluoroacetyl fluoride and oxygen are low-boiling components and can be removed by distillation to remove the light components.

[0022] Further preferably, the extractant is hexafluoropropylene dimer, hexafluoropropylene trimer, hexafluoropropyl difluorovinyl ether (CF 3 CFHCF 2 OCH=CF 2 )、CHF 2 CF=CHOCF 2 CF 2 H、CF 2 =CFCH 2 OCF 2 CF 2 H、CF 2 =CHOCF 2 CF 2 H, or one of the following

[0023] More preferably, the extractant is the same as the fluorinated solvent.

[0024] In the present invention, the oxidation reaction step and the subsequent purification step are coupled, and the extractant and the fluorinated solvent used are the same, so that the entire reaction step can be carried out continuously.

[0025] Further preferably, the mass ratio of the light component removal liquid to the extractant is 1:20 to 50.

[0026] Preferably, a desorption treatment step is added after the purification treatment to separate hexafluoropropylene and the fluorinated solvent.

[0027] Preferably, the conversion rate of hexafluoropropylene ≥ 79%, the selectivity of hexafluoropropylene oxide ≥ 85%, and the purity of hexafluoropropylene oxide after purification treatment > 99%.

[0028] The present invention also provides a device for continuous synthesis and purification reaction of hexafluoropropylene oxide, including a hexafluoropropylene tank, a fluorinated solvent tank, an oxygen tank, a rotating packed bed reactor, a light component removal tower, an extractive distillation tower and a desorption tower. The outputs of the hexafluoropropylene tank and the fluorinated solvent tank are collected and then input into the rotating packed bed reactor. The output pipeline of the oxygen tank is connected to the rotating packed bed reactor. The output pipeline of the rotating packed bed reactor is connected to the light component removal tower. A light component collection device is provided at the top of the light component removal tower. The output pipeline at the bottom of the light component removal tower is connected to the extractive distillation tower. A hexafluoropropylene oxide collection device is provided at the top of the extractive distillation tower. The output pipeline at the bottom of the extractive distillation tower is connected to the desorption tower. The hexafluoropropylene recovered at the top of the desorption tower is transported to the hexafluoropropylene tank, and the fluorinated solvent recovered at the bottom of the desorption tower is respectively input to the top of the extractive distillation tower and the fluorinated solvent tank.

[0029] The present invention realizes the continuous synthesis and purification of hexafluoropropylene oxide by using the above-mentioned device. Hexafluoropropylene oxide is synthesized in a high-gravity reactor, and high-purity hexafluoropropylene oxide is collected through a desorption column and an extractive distillation column. The hexafluoropropylene and fluorinated solvent in the extract are separated by the desorption column. The hexafluoropropylene can enter the hexafluoropropylene tank, and the fluorinated solvent can be used as an extractant or returned to the fluorinated solvent tank to realize the recycling of hexafluoropropylene and fluorinated solvent.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] (1) In the present invention, a high-gravity reactor is used as the reaction device. Hexafluoropropylene, oxygen and fluorinated solvent are introduced into the high-gravity reactor for oxidation reaction, and high-purity hexafluoropropylene oxide is obtained after purification. The use of the high-gravity reactor in this process can effectively solve the problems of mass transfer and heat transfer, significantly improve the selectivity of the reaction, effectively improve the production capacity at the same time, and combined with extractive distillation treatment, the conversion rate of hexafluoropropylene reaches more than 79%, the selectivity of hexafluoropropylene oxide is more than 85%, and the purity of hexafluoropropylene oxide after extractive distillation is as high as 99%.

[0032] (2) The device provided by the present invention synthesizes hexafluoropropylene oxide through a high-gravity reactor, collects high-purity hexafluoropropylene oxide through a desorption column and an extractive distillation column, and separates the hexafluoropropylene and fluorinated solvent in the extract by the desorption column. The hexafluoropropylene can enter the hexafluoropropylene tank, and the fluorinated solvent can be used as an extractant or returned to the fluorinated solvent tank to realize the recycling of hexafluoropropylene and fluorinated solvent. The reaction equipment has a small volume, easy-to-control reaction conditions and strong safety, and can effectively avoid the risks of runaway temperature and oxygen explosion. Description of the Drawings

[0033] Figure 1 is the process flow diagram of the continuous synthesis and purification device of hexafluoropropylene oxide of the present invention, wherein,

[0034] 1 is a hexafluoropropylene tank, 2 is a fluorinated solvent tank, 3 is an oxygen tank, 4 is a high-gravity reactor, 5 is a de-light tower, 6 is an extractive distillation column, 7 is a desorption column, 8 is a light component collection device, 9 is a hexafluoropropylene oxide collection device, 10 is a reaction liquid, 11 is a fluorinated solvent recovery pipeline, and 12 is a hexafluoropropylene recovery pipeline. Detailed Embodiments

[0035] The following combines examples to further illustrate the present invention in detail, but the embodiments of the present invention are not limited to the following examples.

[0036] The raw materials used in the present invention are all commercially available.

[0037] Such as Figure 1As shown in the figure, the device used in the continuous production process of hexafluoropropylene oxide according to the embodiment of the present invention includes a hexafluoropropylene tank 1, a fluorinated solvent tank 2, an oxygen tank 3, a rotating packed bed reactor 4, a de-light tower 5, an extractive distillation tower 6, and a desorption tower 7. The outputs of the hexafluoropropylene tank 1 and the fluorinated solvent tank 2 are collected and then input into the rotating packed bed reactor 4. The output pipeline of the oxygen tank 3 is connected to the rotating packed bed reactor 4. The output pipeline of the rotating packed bed reactor 4 is connected to the de-light tower 5. A light component collection device 8 is provided at the top of the de-light tower 5. The output pipeline at the bottom of the de-light tower 5 is connected to the extractive distillation tower 6. A hexafluoropropylene oxide collection device 9 is provided at the top of the extractive distillation tower 6. The output pipeline at the bottom of the extractive distillation tower 6 is connected to the desorption tower 7. The hexafluoropropylene recovered at the top of the desorption tower 7 is transported to the hexafluoropropylene tank 1, and the fluorinated solvent recovered at the bottom of the desorption tower 7 is respectively input to the top of the extractive distillation tower 6 and the fluorinated solvent tank 2.

[0038] Example 1

[0039] (1) The hexafluoropropylene and the fluorinated solvent in the hexafluoropropylene tank 1 and the fluorinated solvent tank 2 are mixed through pipelines and then enter the rotating packed bed reactor 4. Oxygen is introduced into the rotating packed bed reactor 4 through a pipeline from the oxygen tank 3. Among them, the mass ratio of hexafluoropropylene, hexafluoropropylene dimer, and oxygen is 1:0.15:13. The reaction temperature is set at 130 °C, the reaction pressure is 1.6 MPa, and the reaction residence time is 60 s. The reaction liquid 10 after the reaction is continuously overflowed and led out.

[0040] (2) The reaction liquid 10 enters the de-light tower 5. Carbonyl fluoride, trifluoroacetyl fluoride, oxygen and other acyl fluoride light components are discharged from the top of the tower and collected by the light component collection device 8 for other uses. The light component removal liquid at the bottom of the de-light tower 5 enters the lower feed port of the extractive distillation tower 6 and performs extractive distillation in the extractive distillation tower 6 with the hexafluoropropylene dimer fed from the top of the tower at a mass ratio of 1:25. After condensation at the top of the tower, high-purity hexafluoropropylene oxide is collected through the hexafluoropropylene oxide collection device. The extraction liquid at the bottom of the extractive distillation tower 6 enters the desorption tower 7 for desorption treatment. Hexafluoropropylene is taken out from the top of the tower and returned to the hexafluoropropylene tank 1 through the hexafluoropropylene recovery pipeline 12. Part of the desorbed extractant at the bottom of the tower is used as a circulating extractant and enters the extractive distillation tower 6, and part is returned to the fluorinated solvent tank 2 through the fluorinated solvent recovery pipeline 11.

[0041] Examples 2 to 6

[0042] The continuous synthesis and purification method is the same as that in Example 1, and the differences are shown in the following table.

[0043] Table 1: Differences in the continuous synthesis and purification methods of Examples 1 to 6

[0044]

[0045] Sample analysis

[0046] The HFP conversion rate, HFPO selectivity, and the purity of HFPP after extractive distillation were analyzed for Examples 1 to 6, and the results are shown in the following table.

[0047] Table 2: HFP conversion rate, HFPO selectivity, and the purity of HFPP after extractive distillation for Examples 1 to 6

[0048]

[0049] As shown in Table 2, the HFP conversion rates of Examples 1 to 6 are all greater than 79%, and the HFPO selectivities are all greater than 85%, which are significantly better than the prior art. At the same time, the purity of HFPO after extractive distillation can reach more than 99%.

[0050] The foregoing are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for continuous synthesis and purification of hexafluoropropylene oxide, characterized in that: The following steps are involved: Hexafluoropropylene, oxygen and fluorine-containing solvent are introduced into a supergravity reactor for oxidation reaction, wherein the reaction temperature is 100-200°C, the reaction pressure is 1.0-2.5Mpa, the reaction residence time is 10-120s, and after the reaction is completed, the reaction liquid overflows and is purified to obtain hexafluoropropylene oxide.

2. The method for continuous synthesis and purification of hexafluoropropylene oxide according to claim 1, characterized in that: The supergravity reactor is a gas-liquid supergravity reactor.

3. The method for continuous synthesis and purification of hexafluoropropylene oxide according to claim 1, characterized in that: The fluorine-containing solvent is one of hexafluoropropylene dimer, hexafluoropropylene trimer, hexafluoropropyl difluorovinyl ether, CHF2CF=CHOCF2CF2H, CF2=CFCH2OCF2CF2H, and CF2=CHOCF2CF2H.

4. The method for continuous synthesis and purification of hexafluoropropylene oxide according to claim 1, characterized in that: The mass ratio of hexafluoropropylene, oxygen and fluorine-containing solvent is 1:0.1-0.2:5-20.

5. The method for continuous synthesis and purification of hexafluoropropylene oxide according to claim 1, characterized in that: The purification treatment is to remove light components from the reaction liquid after the reaction, collect the light-removed liquid, extract the light-removed liquid with an extractant, and separate the hexafluoropropylene oxide.

6. The method for continuous synthesis and purification of hexafluoropropylene oxide according to claim 5, characterized in that: The extractant is one of hexafluoropropylene dimer, hexafluoropropylene trimer, hexafluoropropyl difluorovinyl ether (CF3CFHCF2OCH=CF2), CHF2CF=CHOCF2CF2H, CF2=CFCH2OCF2CF2H, and CF2=CHOCF2CF2H.

7. The method for continuous synthesis and purification of hexafluoropropylene oxide according to claim 5, characterized in that: The extractant is the same as the fluorine-containing solvent.

8. The method for continuous synthesis and purification of hexafluoropropylene oxide according to claim 5, characterized in that: The mass ratio of the light-removing liquid to the extractant is 1:20-50.

9. The method for continuous synthesis and purification of hexafluoropropylene oxide according to any one of claims 1 to 8, characterized in that: The conversion rate of hexafluoropropylene is ≥79%, the selectivity of hexafluoropropylene oxide is ≥85%, and the purity of hexafluoropropylene oxide after purification is >99%.

10. A device for continuous synthesis and purification of hexafluoropropylene oxide, characterized in that: The invention comprises a hexafluoropropylene tank (1), a fluorine-containing solvent tank (2), an oxygen tank (3), a supergravity reactor (4), a lightness removal tower (5), an extraction distillation tower (6) and a desorption tower (7). The outputs of the hexafluoropropylene tank (1) and the fluorine-containing solvent tank (2) are collected and then input into the supergravity reactor (4). The output pipeline of the oxygen tank (3) is connected to the supergravity reactor (4). The output pipeline of the supergravity reactor (4) is connected to the lightness removal tower (5). The top of the lightness removal tower (5) is provided with A light component collecting device (8) is provided, the output pipeline at the bottom of the light component removal tower (5) is connected to the extractive distillation tower (6), the top of the extractive distillation tower (6) is provided with a hexafluoropropylene oxide collecting device (9), the output pipeline at the bottom of the extractive distillation tower (6) is connected to the stripping tower (7), the hexafluoropropylene recovered at the top of the stripping tower (7) is transported to the hexafluoropropylene tank (1), and the fluorine-containing solvent recovered at the bottom of the stripping tower (7) is respectively input to the top of the extractive distillation tower (6) and the fluorine-containing solvent tank (2).

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