Process for recovering high-purity fluorobenzene in production of 1, 4-bis (4-fluorobenzoyl) benzene

Abstract

The invention discloses a high-purity fluorobenzene recovery process in 1, 4-bis (4-fluorobenzoyl) benzene production, and belongs to the technical field of organic waste liquid recovery, the process comprises the following steps: 1, enabling fluorobenzene waste liquid to pass through a tubular reactor filled with anhydrous aluminum chloride particles to react to obtain dewatered fluorobenzene waste liquid, the reaction temperature is 5-40 DEG C, the retention time is 60-200min, and the flow velocity of the fluorobenzene waste liquid is 0.1-0.4 m / min; 2, the water-removed fluorobenzene waste liquid is filtered through a micron filter and then enters a fluorobenzene rectifying tower to be rectified, organic steam on the tower top is compressed through a compressor, subjected to heat exchange through an MVR heat exchanger and condensed and then enters a reflux tank to be refluxed, high-purity fluorobenzene is extracted from the fluorobenzene rectifying tower, the purity of the fluorobenzene is larger than 99.99 wt%, and the mass content of water is smaller than 10 ppm. The fluorobenzene waste liquid in the production process of 1, 4-bis (4-fluorobenzoyl) benzene is used as a raw material, continuous batch production of high-purity fluorobenzene is achieved through reaction dehydration, crystalline aluminum chloride filtration and rectification, the process is simple, and energy consumption is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic waste liquid recovery, and particularly relates to a high-purity fluorobenzene recovery process in 1,4-bis(4-fluorobenzoyl)benzene production. BACKGROUND

[0002] Polyaryletherketone is a kind of semi-crystalline, high-temperature-resistant, high-performance thermoplastic engineering plastic, which has a wide application in the fields of aerospace, microelectronics, 3D printing, humanoid robots and the like.

[0003] 1,4-bis(4-fluorobenzoyl)benzene is a key monomer mainly used in polyaryletherketone series high-performance engineering plastics, and at present, 1,4-bis(4-fluorobenzoyl)benzene is synthesized by an industrial production method that fluorobenzene is reacted with terephthalyl chloride under the catalysis of aluminum chloride. Since the molar ratio of terephthalyl chloride to fluorobenzene is usually between 1:10-1:20, the excessive fluorobenzene in the reaction process needs to be recovered in the later stage. Usually, after the reaction is completed, the reaction mixture is quenched by water, and the organic layer is composed of fluorobenzene, a small amount of water and a small amount of crystalline aluminum chloride. The organic layer is subjected to rectification to recover fluorobenzene, but the theoretical tray number of the rectification tower is usually about 100, the reflux ratio is greater than 15, the energy consumption is high, and the water content of the obtained fluorobenzene is about 30 ppm, which does not meet the fluorobenzene recycling requirements.

[0004] In the prior art, Chinese patent CN117263765A uses a normal pressure pervaporation method to purify fluorobenzene from a synthesis workshop, and the water content in the obtained fluorobenzene is less than 20 ppm; patent CN118724672A uses a pressurized pervaporation method to remove water from fluorobenzene, and after multiple purifications, the water content in the fluorobenzene can be less than 10 ppm. Since the fluorobenzene waste liquid generated in the production of 1,4-bis(4-fluorobenzoyl)benzene also contains less than 0.5% of crystalline aluminum chloride, if the above method is used to purify the fluorobenzene waste liquid, the impurity crystalline aluminum chloride will contaminate the membrane material in the pervaporation process, affecting the purification process.

[0005] In view of the problems existing in the prior art, the present application combines years of design and use experience in the relevant field to design a high-purity fluorobenzene recovery process in 1,4-bis(4-fluorobenzoyl)benzene production to overcome the above-mentioned defects and obtain high-purity fluorobenzene. SUMMARY

[0006] In view of the problems existing in the prior art, the present application provides a high-purity fluorobenzene recovery process in 1,4-bis(4-fluorobenzoyl)benzene production, which reduces the water content and crystalline aluminum chloride in the fluorobenzene waste liquid, and obtains fluorobenzene with a purity greater than 99.99% and a water content less than 10 ppm.

[0007] In order to achieve the above object, the technical scheme adopted by the present application is as follows: a high-purity fluorobenzene recovery process in 1,4-bis(4-fluorobenzoyl)benzene production, comprising the following steps: Step 1: the fluorobenzene waste liquid passes through a tubular reactor filled with anhydrous aluminum chloride particles to obtain anhydrous fluorobenzene waste liquid, the reaction temperature is 5-40℃, the residence time is 60-200min, and the fluorobenzene waste liquid flow rate is 0.1-0.4m / min; Step 2: the anhydrous fluorobenzene waste liquid is filtered through a micrometer filter and then enters a fluorobenzene rectification tower for rectification, the organic vapor at the top of the tower is compressed by a compressor, heat exchanged by an MVR heat exchanger, and then condensed into a reflux tank for reflux, high-purity fluorobenzene is collected from the fluorobenzene rectification tower, the purity of the fluorobenzene is greater than 99.99wt%, and the water content in the fluorobenzene is less than 10ppm.

[0008] Preferably, the particle size of the anhydrous aluminum chloride particles is 4-16 mesh.

[0009] Preferably, the filtering accuracy of the micrometer filter is 10-20um, and the material is any one of silicon carbide, graphite and ceramic.

[0010] Preferably, the top pressure of the fluorobenzene rectification tower is 1bar, the top temperature is 84-86℃, and the bottom temperature is 85-87℃.

[0011] Preferably, the number of plates of the fluorobenzene rectification tower is 20-30, and the reflux ratio is 0.3-1.

[0012] Preferably, the compressor is a reciprocating compressor or a screw compressor.

[0013] Preferably, the compression ratio of the compressor is (1:1.8)-(1:3), and the gas outlet temperature of the compressor is 115-140℃.

[0014] Preferably, a distributor is arranged in the tubular reactor. The fluorobenzene waste liquid in step 1 enters the tubular reactor through the distributor.

[0015] The present application has the following advantages: 1. The present application uses fluorobenzene waste liquid generated in 1,4-bis(4-fluorobenzoyl)benzene production as raw material, significantly reduces the water content in the fluorobenzene waste liquid by chemical dehydration with anhydrous aluminum chloride, and does not introduce new impurities; after dehydration, the crystalline aluminum chloride precipitated in the fluorobenzene waste liquid is filtered by a micrometer filter, avoiding affecting the purification of fluorobenzene; the product after water absorption is crystalline aluminum chloride, which can be sold as a byproduct, and compared with physical absorption methods such as activated carbon, no solid waste is generated, and the process is green and environmentally friendly.

[0016] 2. The tubular reactor, micron filter, and MVR distillation device in the present invention are connected in sequence to achieve continuous batch production of high-purity fluorobenzene, which has good economic benefits. Fluorobenzene has high purity and can be directly used for the synthesis of 1,4-bis(4-fluorobenzoyl)benzene.

[0017] 3. In the present invention, fluorobenzene waste liquid is purified by combining distillation and MVR technology, and the energy consumption is 40% or less of the traditional distillation method, which significantly reduces the processing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a flow chart of a high-purity fluorobenzene recovery process in the production of 1,4-di(4-fluorobenzoyl)benzene.

[0019] In the figure: 1- tubular reactor, 2- micron filter, 3- start-up reboiler, 4- fluorobenzene distillation column, 5- reflux tank, 6- compressor, 7- MVR heat exchanger. DETAILED DESCRIPTION

[0020] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to specific embodiments.

[0021] like Figure 1 As shown, a process for recovering high-purity fluorobenzene in the production of 1,4-bis(4-fluorobenzoyl)benzene comprises the following steps: Step 1: passing the fluorobenzene waste liquid through a tubular reactor filled with anhydrous aluminum chloride particles to react and obtain dehydrated fluorobenzene waste liquid, the reaction temperature is 5-40°C, the residence time is 60-200min, and the flow rate of the fluorobenzene waste liquid is 0.1-0.4m / min; Step 2: Filter the dehydrated fluorobenzene waste liquid through a micron filter and then enter the fluorobenzene distillation tower for distillation. The organic vapor at the top of the tower is compressed by the compressor and then enters the MVR heat exchanger for heat exchange to heat the bottom material. After the heat exchange, the organic vapor is condensed and enters the reflux tank for reflux. Finally, high-purity fluorobenzene is extracted from the fluorobenzene distillation tower. The purity of fluorobenzene is greater than 99.99wt% and the water content is less than 10ppm.

[0022] Wherein, the dehydrating agent anhydrous aluminum chloride is filled in a tubular reactor to form a dehydrating agent layer, the thickness of the dehydrating agent layer is 100-150 mm, and a filter is used to fix the dehydrating agent layer to prevent the anhydrous aluminum chloride from flowing out with fluorobenzene. The filter material is preferably enamel, silicon carbide or tetrafluoroethylene, the filter pore size is 0.112-0.6 mm, and the tubular reactor contains a hollow part of the same volume as the dehydrating agent layer. The particle size of the anhydrous aluminum chloride particles in the filter is 4-16 mesh, and the filtration accuracy of the micron filter is 10-20 μm, which can fully filter out the crystalline aluminum chloride. The material of the micron filter is any one of silicon carbide, graphite, and ceramic.

[0023] The fluorobenzene waste liquid in the application is an organic phase after layering after water quenching in the production process of 1,4-bis(4-fluorobenzoyl)benzene. The fluorobenzene waste liquid contains fluorobenzene, a small amount of water, crystalline aluminum chloride and 1,4-bis(4-fluorobenzoyl)benzene and other heavy component impurities. When calcium chloride or activated carbon is used to remove water from the fluorobenzene waste liquid, because the water removal mechanism is physical adsorption, there is more residual water in the organic phase after treatment, which far exceeds the water content requirement of electronic grade fluorobenzene, affects the use of fluorobenzene in electronic grade, medical grade products and other working conditions, and also produces solid waste. The application uses anhydrous aluminum chloride as a water removal agent to remove trace amounts of water in the waste liquid, so that the water content is less than 10 ppm. At the same time, after the water content in the waste liquid is reduced, the crystalline aluminum chloride in the system will also be precipitated. The crystalline aluminum chloride entrained in the organic phase is filtered and removed by a micron filter, sold as a byproduct, and the process is green and environmentally friendly without generating solid waste. The filtered fluorobenzene waste liquid is rectified to remove heavy component footnotes, so that high-purity fluorobenzene is obtained at the top of the column, which can be directly reused, and the waste liquid containing 1,4-bis(4-fluorobenzoyl)benzene and other heavy components at the bottom of the column is treated as hazardous waste. The treatment process has the advantages of low energy consumption, continuous process and simple device.

[0024] The application preferably uses the MVR method for rectification. The pressure at the top of the fluorobenzene rectification column is 1 bar, the number of plates of the fluorobenzene rectification column is 20-30, the reflux ratio is 0.3-1, and the temperature of the fluorobenzene rectification column is strictly controlled, the top temperature is 84-86℃, and the bottom temperature is 85-87℃, so that the fluorobenzene leaves the top of the column and is separated from the 1,4-bis(4-fluorobenzoyl)benzene and other impurities at the bottom. The organic vapor is treated by using a compressor to increase the pressure and temperature, which is used as the heat source of the MVR heat exchanger. The compressor is a reciprocating compressor or a screw compressor, the compression ratio of the compressor is (1:1.8)-(1:3), and the gas outlet temperature of the compressor is 115-140℃.

[0025] The application controls the temperature of the tubular reactor and the flow rate of the fluorobenzene waste liquid, avoids the violent reaction of anhydrous aluminum chloride, limits the adiabatic temperature rise of the system, and makes the fluorobenzene waste liquid fully contact with the anhydrous aluminum chloride particles by controlling the flow rate of the fluorobenzene waste liquid. When the flow rate is greater than 0.4 m / min, the flow rate is too fast, the fluorobenzene waste liquid is not fully dehydrated, and the purified fluorobenzene obtained cannot be directly used. When the flow rate is less than 0.1 m / min, the fluorobenzene waste liquid stays in the tubular reactor for too long, increasing the processing time. The tubular reactor is provided with a distributor, and the fluorobenzene waste liquid enters the tubular reactor through the distributor to ensure that the distribution of the fluorobenzene waste liquid in the tubular reactor is more uniform. The distributor is a conventional device in the field and will not be described here. In the application, the tubular reactor, the micron filter and the MVR rectification device are connected in sequence, and the fluorobenzene waste liquid generated in the production process of 1,4-bis (4-fluorobenzoyl) benzene can continuously enter the tubular reactor for treatment, thereby realizing the continuous batch production of high-purity fluorobenzene and having good economic benefits. The treated fluorobenzene has high purity and can be directly used for the synthesis of 1,4-bis (4-fluorobenzoyl) benzene. Specific embodiments Example 1

[0026] The present embodiment provides a high-purity fluorobenzene recovery process in the production of 1,4-bis (4-fluorobenzoyl) benzene, which refers to Figure 1 The tubular reactor 1 has a specification of DN25mm*20m, the micron filter 2 has a filtering accuracy of 10um and is made of silicon carbide, and the compressor 6 is a reciprocating compressor; Step 1, fill 4mm anhydrous aluminum chloride into the tubular reactor 1, the thickness of the dehydrating agent layer is 100mm, and the fluorobenzene waste liquid from the 1,4-bis (4-fluorobenzoyl) benzene synthesis process enters the tubular reactor 1 under normal pressure to obtain dehydrated fluorobenzene waste liquid. The temperature of the tubular reactor 1 is 5℃, the liquid flow rate is 0.2m / min, and the residence time is 100min; Step 2, after the reaction is completed, the dehydrated fluorobenzene waste liquid enters the micron filter 2, filters the crystalline aluminum chloride, and then enters the fluorobenzene rectification column 4 for rectification. The fluorobenzene rectification column 4 has 20 theoretical trays, a reflux ratio of 1, a tower top pressure of 1bar, a tower top temperature of 85℃, and a tower bottom temperature of 87℃. The gaseous fluorobenzene at the tower top enters the compressor 6, the temperature is raised to 115℃ by compression, the compression ratio of the compressor 6 is 1:2, and then the heat exchange is performed through the MVR heat exchanger 7. After heat exchange, the liquid is condensed into the reflux tank 5 for reflux, and finally the fluorobenzene product is obtained in the rectification section of the fluorobenzene rectification column 4. The fluorobenzene product is detected, the fluorobenzene content is greater than 99.992wt%, and the water content is 8ppm. Example 2

[0027] The present embodiment provides a high-purity fluorobenzene recovery process in the production of 1,4-bis (4-fluorobenzoyl) benzene, which refers to Figure 1Wherein the pipe reactor 1 is DN25mm*20m, the micron filter 2 has a filtering accuracy of 20um and is made of graphite, and the compressor 6 is a reciprocating compressor; Step 1: 10 liters of anhydrous aluminum chloride is loaded into the pipe reactor 1, the thickness of the dehydrating agent layer is 150mm, and the fluorobenzene waste liquid from the 1,4-bis(4-fluorobenzoyl)benzene synthesis process enters the pipe reactor 1 through the distributor under normal pressure to obtain dehydrated fluorobenzene waste liquid, the temperature of the pipe reactor 1 is 40℃, the liquid flow rate is 0.1m / min, and the residence time is 200min; Step 2: After the reaction is completed, the dehydrated fluorobenzene waste liquid enters the micron filter 2 to filter the crystalline aluminum chloride, and then enters the fluorobenzene rectification tower 4 for rectification, the fluorobenzene rectification tower 4 has 25 theoretical trays, the reflux ratio is 0.3, the tower top pressure is 1bar, the tower top temperature is 86℃, the tower bottom temperature is 87℃, the gaseous fluorobenzene at the tower top enters the compressor 6, the temperature is increased to 140℃ by compression of the compressor 6, the compression ratio of the compressor 6 is 1:3, and then the MVR heat exchanger 7 is used for heat exchange, and the liquid is condensed into a liquid after heat exchange and enters the reflux tank 5 for reflux, and finally fluorobenzene products are obtained from the fluorobenzene rectification tower 4, the fluorobenzene products are detected, the fluorobenzene content is greater than 99.996wt%, and the water content is 4ppm. Example 3

[0028] The embodiment provides a high-purity fluorobenzene recovery process in 1,4-bis(4-fluorobenzoyl)benzene production, which refers to Figure 1 Wherein the pipe reactor 1 is DN25mm*24m, the micron filter 2 has a filtering accuracy of 15um and is made of ceramic, and the compressor 6 is a screw compressor; Step 1: 16 liters of anhydrous aluminum chloride is loaded into the pipe reactor 1, the thickness of the dehydrating agent layer is 125mm, and the fluorobenzene waste liquid from the 1,4-bis(4-fluorobenzoyl)benzene synthesis process enters the pipe reactor 1 through the distributor under normal pressure to obtain dehydrated fluorobenzene waste liquid, the temperature is 30℃, the liquid flow rate is 0.4m / min, and the residence time is 60min; Step 2: After the reaction is completed, the dehydrated fluorobenzene waste liquid enters the micron filter 2 to filter the crystalline aluminum chloride, and then enters the fluorobenzene rectification tower 4 for rectification, the fluorobenzene rectification tower 4 has 30 theoretical trays, the reflux ratio is 0.3, the tower top pressure is 1bar, the tower top temperature is 85℃, the tower bottom temperature is 86℃, the gaseous fluorobenzene at the tower top enters the compressor 6, the temperature is increased to 125℃ by compression of the compressor 6, the compression ratio of the compressor 6 is 1:2.3, and then the MVR heat exchanger 7 is used for heat exchange, and the liquid is condensed into a liquid after heat exchange and enters the reflux tank 5 for reflux, and finally fluorobenzene products are obtained from the fluorobenzene rectification tower 4, the fluorobenzene products are detected, the fluorobenzene content is greater than 99.990wt%, and the water content is 10ppm.

[0029] It should be understood that the use of the term "example" anywhere in this description is not intended to limit the application's scope. Rather, the term "example" is used to illustrate certain examples and aspects of the application. It is not intended to indicate that the application is limited in scope to the examples given. Furthermore, it is intended that every means within the scope of the example be considered to be within the scope of the application. Moreover, it is intended that every combination of means within the scope of the example be considered to be within the scope of the application.

Claims

1. A process for recovering high-purity fluorobenzene in the production of 1,4-bis(4-fluorobenzoyl)benzene, characterized in that: The following steps are involved: Step 1: passing the fluorobenzene waste liquid through a tubular reactor filled with anhydrous aluminum chloride particles to obtain dehydrated fluorobenzene waste liquid, the reaction temperature is 5-40° C., the residence time is 60-200 min, and the flow rate of the fluorobenzene waste liquid is 0.1-0.4 m / min; Step 2: Filter the dehydrated fluorobenzene waste liquid through a micron filter and then enter the fluorobenzene distillation tower for distillation. The organic vapor at the top of the tower is compressed by a compressor, heat-exchanged by an MVR heat exchanger, condensed, and refluxed into a reflux tank. High-purity fluorobenzene is obtained from the fluorobenzene distillation tower. The purity of fluorobenzene is greater than 99.99wt%, and the water content in fluorobenzene is less than 10ppm.

2. The high-purity fluorobenzene recovery process in the production of 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The particle size of the anhydrous aluminum chloride particles is 4-16 meshes.

3. The high-purity fluorobenzene recovery process in the production of 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The micron filter has a filtration accuracy of 10-20 μm and is made of any one of silicon carbide, graphite, and ceramic.

4. The process for recovering high-purity fluorobenzene in the production of 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The top pressure of the fluorobenzene distillation tower is 1 bar, the top temperature is 84-86°C, and the bottom temperature is 85-87°C.

5. The process for recovering high-purity fluorobenzene in the production of 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The fluorobenzene distillation tower has 20-30 plates and a reflux ratio of 0.3-1.

6. The process for recovering high-purity fluorobenzene in the production of 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The compressor is a reciprocating compressor or a screw compressor.

7. The process for recovering high-purity fluorobenzene in the production of 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The compression ratio of the compressor is (1:1.8)-(1:3), and the gas outlet temperature of the compressor is 115-140°C.

8. The process for recovering high-purity fluorobenzene in the production of 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that: A distributor is provided in the tubular reactor; In step 1, the fluorobenzene waste liquid enters the tubular reactor through a distributor.

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