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

Abstract

This invention discloses a high-purity fluorobenzene recovery process in the production of 1,4-bis(4-fluorobenzoyl)benzene, belonging to the field of organic waste liquid recovery technology. Step 1 involves reacting the fluorobenzene waste liquid through a tubular reactor containing anhydrous aluminum chloride particles to obtain dehydrated fluorobenzene waste liquid. The reaction temperature is 5-40℃, 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 involves filtering the dehydrated fluorobenzene waste liquid through a micron filter, then distilling it in a fluorobenzene distillation column. The organic vapor at the top of the column is compressed by a compressor, heat-exchanged by an MVR heat exchanger, condensed, and then refluxed in a reflux tank. High-purity fluorobenzene is obtained from the fluorobenzene distillation column, wherein the fluorobenzene purity is greater than 99.99 wt% and the water content is less than 10 ppm. This invention uses fluorobenzene waste liquid from the production process of 1,4-bis(4-fluorobenzoyl)benzene as raw material. Through reaction dehydration, crystalline aluminum chloride filtration and distillation, it achieves continuous batch production of high-purity fluorobenzene. The process is simple and has low energy consumption.

Description

Technical Field

[0001] This invention relates to the field of organic waste liquid recycling technology, specifically to a process for recovering high-purity fluorobenzene in the production of 1,4-bis(4-fluorobenzoyl)benzene. Background Technology

[0002] Polyaryletherketones (PAGEs) are a class of semi-crystalline, high-temperature resistant, high-performance thermoplastic engineering plastics with wide applications in aerospace, microelectronics, 3D printing, humanoid robots, and other fields.

[0003] 1,4-Di(4-fluorobenzoyl)benzene is a key monomer mainly used in polyaryletherketone series of high-performance engineering plastics. Currently, it is mainly synthesized by industrial production methods involving the reaction of fluorobenzene and terephthaloyl chloride under the catalysis of aluminum trichloride. Since the molar ratio of terephthaloyl chloride to fluorobenzene is usually between 1:10 and 1:20, it is necessary to recover the excess fluorobenzene in the later stages of the reaction. The usual method is to quench the reaction mixture with water after the reaction is completed, and separate the layers. The organic layer consists of fluorobenzene, a small amount of water, and a small amount of crystalline aluminum chloride. The organic layer is then distilled to recover the fluorobenzene. However, this method often requires a theoretical plate number of around 100 in the distillation column, and the reflux ratio is greater than 15, resulting in high energy consumption. Furthermore, the water content of the obtained fluorobenzene is around 30 ppm, which does not meet the requirements for fluorobenzene recycling.

[0004] In existing technologies, Chinese patent CN117263765A uses atmospheric pressure pervaporation to purify fluorobenzene from the synthesis workshop, resulting in a water content of less than 20 ppm. Patent CN118724672A uses pressurized pervaporation to remove water from fluorobenzene, achieving a water content of less than 10 ppm after multiple purification processes. However, since the fluorobenzene wastewater produced from 1,4-bis(4-fluorobenzoyl)benzene production also contains less than 0.5% crystalline aluminum chloride, if the above methods are used to purify the wastewater, the impurity crystalline aluminum chloride will contaminate the membrane material during pervaporation, affecting the purification process.

[0005] In view of the problems existing in the prior art, the present invention, combined with years of design and use experience in related fields, designs a high-purity fluorobenzene recovery process in the production of 1,4-bis(4-fluorobenzoyl)benzene to overcome the above defects and obtain high-purity fluorobenzene. Summary of the Invention

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

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a high-purity fluorobenzene recovery process in the production of 1,4-bis(4-fluorobenzoyl)benzene, comprising the following steps:

[0008] Step 1: The fluorobenzene waste liquid is reacted in a tubular reactor containing anhydrous aluminum chloride particles to obtain dehydrated fluorobenzene waste liquid. The reaction temperature is 5-40℃, the residence time is 60-200min, and the flow rate of the fluorobenzene waste liquid is 0.1-0.4m / min.

[0009] Step 2: The dehydrated fluorobenzene waste liquid is filtered through a micron filter and then enters the fluorobenzene distillation column for distillation. The organic vapor at the top of the column is compressed by a compressor, heat-exchanged by an MVR heat exchanger, condensed, and then refluxed into a reflux tank. High-purity fluorobenzene is collected from the fluorobenzene distillation column with a purity greater than 99.99 wt% and a water content of less than 10 ppm.

[0010] Preferably, the anhydrous aluminum chloride particles have a particle size of 4-16 mesh.

[0011] Preferably, the micron filter has a filtration accuracy of 10-20µm and is made of any one of silicon carbide, graphite, or ceramic.

[0012] Preferably, the pressure at the top of the fluorobenzene distillation column is 1 bar, the temperature at the top of the column is 84-86°C, and the temperature at the bottom of the column is 85-87°C.

[0013] Preferably, the fluorobenzene distillation column has 20-30 trays and a reflux ratio of 0.3-1.

[0014] Preferably, the compressor is a reciprocating compressor or a screw compressor.

[0015] Preferably, the compression ratio of the compressor is (1:1.8)-(1:3), and the gas outlet temperature of the compressor is 115-140℃.

[0016] Preferably, the tubular reactor is equipped with a distributor;

[0017] The fluorobenzene waste liquid from step 1 enters the tubular reactor through a distributor.

[0018] The advantages of this invention are:

[0019] 1. This invention uses fluorobenzene waste liquid generated during the production of 1,4-bis(4-fluorobenzoyl)benzene as raw material. Anhydrous aluminum chloride is used for chemical dehydration, significantly reducing the water content in the fluorobenzene waste liquid without introducing new impurities. After dehydration, a micron filter is used to filter the crystalline aluminum chloride precipitated in the fluorobenzene waste liquid, avoiding any impact on the purification of fluorobenzene. The product after the adsorbent absorbs water is crystalline aluminum chloride, which can be sold as a byproduct. Compared with physical absorption methods such as activated carbon, this process does not generate solid waste and is green and environmentally friendly.

[0020] 2. In this invention, the tubular reactor, micron filter, and MVR distillation device are connected in sequence to achieve continuous batch production of high-purity fluorobenzene, which has good economic benefits. The fluorobenzene has high purity and can be directly used for the synthesis of 1,4-bis(4-fluorobenzoyl)benzene.

[0021] 3. In this invention, fluorobenzene waste liquid is purified by a combination of distillation and MVR technology, which consumes 40% or less of the energy of traditional distillation, thus significantly reducing the energy consumption of the treatment. Attached Figure Description

[0022] Figure 1 This is a flowchart of a high-purity fluorobenzene recovery process in the production of 1,4-bis(4-fluorobenzoyl)benzene.

[0023] In the diagram: 1-Tube reactor, 2-Micron filter, 3-Start-up reboiler, 4-Fluorobenzene distillation column, 5-Reflux tank, 6-Compressor, 7-MVR heat exchanger. Detailed Implementation

[0024] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to specific embodiments.

[0025] like Figure 1 As shown, a process for recovering high-purity fluorobenzene in the production of 1,4-bis(4-fluorobenzoyl)benzene includes the following steps:

[0026] Step 1: Pass the fluorobenzene waste liquid through a tubular reactor containing anhydrous aluminum chloride particles to obtain dehydrated fluorobenzene waste liquid. The reaction temperature is 5-40℃, the residence time is 60-200min, and the flow rate of the fluorobenzene waste liquid is 0.1-0.4m / min.

[0027] Step 2: The dehydrated fluorobenzene waste liquid is filtered through a micron filter and then enters the fluorobenzene distillation column for distillation. The organic vapor at the top of the column is compressed by a compressor and then enters an MVR heat exchanger to heat the material in the bottom of the column. After heat exchange, the organic vapor is condensed and enters a reflux tank for recirculation. Finally, high-purity fluorobenzene is collected from the fluorobenzene distillation column. The purity of fluorobenzene is greater than 99.99 wt%, and the water content is less than 10 ppm.

[0028] Anhydrous aluminum chloride, a dehydrating agent, is filled in a tubular reactor to form a dehydrating agent layer with a thickness of 100-150 mm. A filter screen is used to fix the dehydrating agent layer and prevent the anhydrous aluminum chloride from flowing out with fluorobenzene. The filter screen is preferably made of enamel, silicon carbide, or tetrafluoroethylene, with a pore size of 0.112-0.6 mm. The tubular reactor contains a hollow section with a volume equal to that of the dehydrating agent layer. The anhydrous aluminum chloride particles in the filter screen have a particle size of 4-16 mesh, and the micron filter has a filtration accuracy of 10-20 μm, which can effectively filter out crystalline aluminum chloride. The micron filter can be made of any one of silicon carbide, graphite, or ceramic.

[0029] In this invention, the fluorobenzene waste liquid is the organic phase after water quenching and stratification during the production of 1,4-bis(4-fluorobenzoyl)benzene. The fluorobenzene waste liquid contains fluorobenzene, a small amount of water, crystalline aluminum chloride, and heavy component impurities such as 1,4-bis(4-fluorobenzoyl)benzene. When using calcium chloride or activated carbon to remove water from the fluorobenzene waste liquid, because the dehydration mechanism is physical adsorption, the residual water in the organic phase after treatment is much higher than the water content requirements for electronic-grade fluorobenzene, affecting the use of fluorobenzene in electronic and medical-grade products and generating solid waste. This invention uses anhydrous aluminum chloride as a dehydrating agent, employing chemical absorption to remove trace amounts of water from the waste liquid, reducing the water content to less than 10 ppm. Simultaneously, as the water content in the waste liquid decreases, crystalline aluminum chloride in the system also precipitates. This crystalline aluminum chloride, carried by the organic phase, is then filtered out using a micron filter and sold as a byproduct. The process is green and environmentally friendly, generating no solid waste. The filtered fluorobenzene waste liquid is distilled to remove heavy component byproducts, thereby obtaining high-purity fluorobenzene at the top of the column, which can be directly recycled. The waste liquid containing heavy components such as 1,4-bis(4-fluorobenzoyl)benzene in the bottom of the column is treated as hazardous waste. The process of this invention has the advantages of low energy consumption, continuous process, and simple equipment.

[0030] This invention preferably uses the MVR method for distillation. During the distillation process, the pressure at the top of the fluorobenzene distillation column is 1 bar, the number of trays in the fluorobenzene distillation column is 20-30, the reflux ratio is 0.3-1, and the temperature of the fluorobenzene distillation column is strictly controlled, with a top temperature of 84-86℃ and a bottom temperature of 85-87℃, so that fluorobenzene leaves from the top of the column and separates from impurities such as 1,4-bis(4-fluorobenzoyl)benzene at the bottom of the column. The organic vapor is pressurized and heated using a compressor and used as a heat source for the MVR heat exchanger. The compressor is a reciprocating compressor or a screw compressor with a compression ratio of (1:1.8)-(1:3) and a compressor gas outlet temperature of 115-140℃.

[0031] This invention controls the temperature of the tubular reactor and the flow rate of the fluorobenzene waste liquid to avoid violent reactions of anhydrous aluminum chloride and limit the adiabatic temperature rise of the system. By controlling the flow rate of the fluorobenzene waste liquid, it ensures sufficient contact with the anhydrous aluminum chloride particles. When the flow rate is greater than 0.4 m / min, the flow rate is too fast, and the dehydration of the fluorobenzene waste liquid is insufficient, so the purified fluorobenzene cannot be used directly. When the flow rate is less than 0.1 m / min, the residence time of the fluorobenzene waste liquid in the tubular reactor is too long, increasing the processing time. The tubular reactor is equipped with a distributor, through which the fluorobenzene waste liquid enters the tubular reactor, ensuring a more uniform distribution of the fluorobenzene waste liquid inside the tubular reactor. The distributor is a conventional device in the art and will not be described in detail here. In this invention, a tubular reactor, a micron filter, and an MVR distillation device are connected in sequence. The fluorobenzene waste liquid generated during the production 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 with good economic benefits. The treated fluorobenzene has high purity and can be directly used in the synthesis of 1,4-bis(4-fluorobenzoyl)benzene.

[0032] Specific embodiments are as follows: Example 1

[0033] This embodiment provides a high-purity fluorobenzene recovery process in the production of 1,4-bis(4-fluorobenzoyl)benzene, referencing... Figure 1 The tubular reactor 1 has a specification of DN25mm*20m, the micron filter 2 has a filtration accuracy of 10um and is made of silicon carbide, and the compressor 6 is a reciprocating compressor.

[0034] Step 1: 4-mesh anhydrous aluminum chloride is packed into tubular reactor 1. The thickness of the dehydrating agent layer is 100 mm. Fluorobenzene waste liquid from the synthesis process of 1,4-bis(4-fluorobenzoyl)benzene is introduced into tubular reactor 1 under normal pressure to react and obtain dehydrated fluorobenzene waste liquid. The temperature of tubular reactor 1 is 5℃, the liquid flow rate is 0.2 m / min, and the residence time is 100 min.

[0035] Step 2: After the reaction is complete, the dehydrated fluorobenzene waste liquid enters the micron filter 2 to filter out crystalline aluminum chloride, and then enters the fluorobenzene distillation column 4 for distillation. The fluorobenzene distillation column 4 has 20 theoretical plates, a reflux ratio of 1, a top pressure of 1 bar, a top temperature of 85°C, and a bottom temperature of 87°C. The vaporous fluorobenzene at the top of the column enters the compressor 6, which compresses it to raise the temperature to 115°C. The compression ratio of the compressor 6 is 1:2. After heat exchange in the MVR heat exchanger 7, the fluorobenzene condenses into liquid and enters the reflux tank 5 for reflux. Finally, the fluorobenzene product is obtained in the distillation section of the fluorobenzene distillation column 4. The fluorobenzene product is tested and found to have a fluorobenzene content greater than 99.992 wt% and a water content of 8 ppm. Example 2

[0036] This embodiment provides a high-purity fluorobenzene recovery process in the production of 1,4-bis(4-fluorobenzoyl)benzene, referencing... Figure 1 The tubular reactor 1 has a specification of DN25mm*20m, the micron filter 2 has a filtration accuracy of 20um and is made of graphite, and the compressor 6 is a reciprocating compressor.

[0037] Step 1: 10-mesh anhydrous aluminum chloride is packed into tubular reactor 1. The dehydrating agent layer thickness is 150 mm. Fluorobenzene waste liquid from the 1,4-bis(4-fluorobenzoyl)benzene synthesis process is introduced into tubular reactor 1 through a distributor under normal pressure to react and obtain dehydrated fluorobenzene waste liquid. The temperature of tubular reactor 1 is 40℃, the liquid flow rate is 0.1 m / min, and the residence time is 200 min.

[0038] Step 2: After the reaction is complete, the dehydrated fluorobenzene waste liquid enters the micron filter 2 to filter out crystalline aluminum chloride, and then enters the fluorobenzene distillation column 4 for distillation. The fluorobenzene distillation column 4 has 25 theoretical plates, a reflux ratio of 0.3, a top pressure of 1 bar, a top temperature of 86°C, and a bottom temperature of 87°C. The vaporous fluorobenzene at the top of the column enters the compressor 6, which compresses it to raise the temperature to 140°C. The compression ratio of the compressor 6 is 1:3. After passing through the MVR heat exchanger 7, the heat exchanged and condensed into liquid enters the reflux tank 5 for reflux. Finally, the fluorobenzene product is obtained from the fluorobenzene distillation column 4. The fluorobenzene product is tested and found to have a fluorobenzene content greater than 99.996 wt% and a water content of 4 ppm. Example 3

[0039] This embodiment provides a high-purity fluorobenzene recovery process in the production of 1,4-bis(4-fluorobenzoyl)benzene, referencing... Figure 1 The tubular reactor 1 has a specification of DN25mm*24m, the micron filter 2 has a filtration accuracy of 15um and is made of ceramic, and the compressor 6 is a screw compressor.

[0040] Step 1: 16-mesh anhydrous aluminum chloride is packed into tubular reactor 1. The thickness of the dehydrating agent layer is 125 mm. Fluorobenzene waste liquid from the synthesis process of 1,4-bis(4-fluorobenzoyl)benzene is introduced into tubular reactor 1 through a distributor under normal pressure to react and obtain dehydrated fluorobenzene waste liquid. The temperature is 30℃, the liquid flow rate is 0.4 m / min, and the residence time is 60 min.

[0041] Step 2: After the reaction is complete, the dehydrated fluorobenzene waste liquid enters the micron filter 2 to filter out crystalline aluminum chloride, and then enters the fluorobenzene distillation column 4 for distillation. The fluorobenzene distillation column 4 has 30 theoretical plates, a reflux ratio of 0.3, a top pressure of 1 bar, a top temperature of 85°C, and a bottom temperature of 86°C. The vaporous fluorobenzene at the top of the column enters the compressor 6, which compresses it to raise the temperature to 125°C. The compression ratio of the compressor 6 is 1:2.3. After passing through the MVR heat exchanger 7, the heat exchanged and condensed into liquid enters the reflux tank 5 for reflux. Finally, the fluorobenzene product is obtained from the fluorobenzene distillation column 4. The fluorobenzene product is tested and found to have a fluorobenzene content greater than 99.990 wt% and a water content of 10 ppm.

[0042] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention. Furthermore, it should be understood that after reading the technical description of this invention, those skilled in the art can make various alterations, modifications, and / or variations to the invention, and all such equivalent forms also fall within the scope of protection defined by the appended claims.

Claims

1. A process for recovering high-purity fluorobenzene in the production of 1,4-bis(4-fluorobenzoyl)benzene, characterized in that, Includes the following steps: Step 1: The fluorobenzene waste liquid is reacted in a tubular reactor containing anhydrous aluminum chloride particles to obtain dehydrated fluorobenzene waste liquid. The reaction temperature is 5-40℃, the residence time is 60-200min, and the flow rate of the fluorobenzene waste liquid is 0.1-0.4m / min. Step 2: The dehydrated fluorobenzene waste liquid is filtered through a micron filter and then enters the fluorobenzene distillation column for distillation. The organic vapor at the top of the column is compressed by a compressor, heat exchanged by an MVR heat exchanger, condensed, and then refluxed into a reflux tank. High-purity fluorobenzene is obtained from the fluorobenzene distillation column. The purity of fluorobenzene is greater than 99.99 wt%, and the water content in fluorobenzene is less than 10 ppm. The fluorobenzene distillation column has 20-30 trays, a reflux ratio of 0.3-1, a top pressure of 1 bar, a top temperature of 84-86℃, and a bottom temperature of 85-87℃. The compressor has a compression ratio of (1:1.8) to (1:3) and a gas outlet temperature of 115-140℃.

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 anhydrous aluminum chloride particles have a particle size of 4-16 mesh.

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 10-20µm and is made of any one of silicon carbide, graphite, or ceramic.

4. The high-purity fluorobenzene recovery process 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.

5. The high-purity fluorobenzene recovery process in the production of 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that, The tubular reactor is equipped with a distributor; In step 1, the fluorobenzene waste liquid enters the tubular reactor through a distributor.

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