Preparation method of electronic-grade fluorobenzene

Abstract

The invention discloses a preparation method of electronic-grade fluorobenzene, which comprises the following operation steps: S1, feeding a fluorobenzene raw material into a light component removal tower for rectification treatment, extracting light components from the tower top of the light component removal tower, and extracting liquid-phase light-removed fluorobenzene from the tower bottom of the light component removal tower; s2, feeding the liquid-phase light-fluorine-removed benzene into a heavy component removal tower for rectification treatment, extracting gas-phase electronic-grade fluorobenzene from the tower top of the heavy component removal tower, and extracting liquid-phase heavy components from the tower bottom of the heavy component removal tower; a first thermal coupling heat exchanger is arranged on a fluorobenzene raw material conveying pipeline connected with the light component removal tower; a second thermal coupling heat exchanger connecting loop and a light component removal tower reboiler connecting loop which are arranged in parallel are respectively arranged between the tower bottom and the tower kettle of the light component removal tower; a hot stream outlet of the first thermal coupling heat exchanger is used as an extraction port of an electronic-grade fluorobenzene product; according to the method, on the basis of ensuring that an electronic-grade fluorobenzene product is obtained at a high yield, the energy consumption is greatly reduced; the device is simple in structure, easy to operate and suitable for industrial continuous production and application.

Description

Technical Field

[0001] The invention belongs to the field of fluorobenzene preparation, and particularly relates to a method for preparing electronic-grade fluorobenzene. Background Art

[0002] Fluorobenzene (chemical formula: C6H5F) is an important organic fluoride, which is widely used in the fields of medicine, pesticides, electronic chemicals, etc. In the existing fluorobenzene preparation process: after the pyrolysis reaction is completed, the static separation method is mostly used to first separate the upper organic phase, and then the organic phase is washed and neutralized; then directly perform steam intermittent distillation, and then perform rectification, collect the 85-120°C fraction to obtain fluorobenzene. This intermittent distillation method not only has high energy consumption, but also has relatively low fluorobenzene yield and purity.

[0003] With the rapid development of the electronics industry (including semiconductor manufacturing, liquid crystal display materials, and high-performance polymers for the electronics industry), the purity requirements for fluorobenzene are getting higher and higher. Therefore, the existing fluorobenzene preparation process cannot meet the purity requirements for fluorobenzene. A domestic prior patent application with publication number CN118791354A discloses a continuous separation method for electronic-grade fluorobenzene. The method uses fluorobenzene pyrolysis reaction liquid as a raw material and performs a continuous operation of centrifugal separation, neutralization, filtration, phase separation, and distillation. Although the continuous refining production of electronic-grade fluorobenzene is achieved, there are also problems of high energy consumption and relatively expensive equipment costs.

[0004] Therefore, the applicant hopes to seek technical solutions to solve the above technical problems. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a method for preparing electronic-grade fluorobenzene, which greatly reduces energy consumption and improves energy utilization efficiency while ensuring high yield of electronic-grade fluorobenzene products; and the device structures adopted in this application are all conventional devices with simple structures and easy operation, which are suitable for industrial continuous production applications.

[0006] The technical solution adopted by the present invention is as follows: Before proposing the present application, it should be specially pointed out that the present applicant has paid special attention to the fact that the current processes used for the refining and purification of fluorobenzene are all steam intermittent distillation and rectification. This is because people believe that steam intermittent distillation has high efficiency and low energy consumption, and can achieve the preliminary purification of crude fluorobenzene. Direct distillation will increase the cost of process implementation. In particular, although the light removal and heavy removal combined distillation process has been applied to the separation and purification of some components, for those skilled in the art, if the conventional light removal and heavy removal combined distillation process is used for the separation and purification of fluorobenzene, the energy consumption is unbearable, and the key is that it is impossible to directly obtain fluorobenzene products of electronic grade purity.

[0007] A method for preparing electronic grade fluorobenzene, comprising at least the following steps: S1: feeding the fluorobenzene raw material into a light-removing tower for distillation treatment, extracting the light components from the top of the light-removing tower, and extracting the liquid light-removing fluorobenzene from the bottom of the light-removing tower after the light components are removed; the light-removing tower has 30-60 theoretical plates, the 15th-40th feed position, the operating pressure of 0-0.08MPaG, the operating temperature of 60-110°C, and the reflux ratio of the light-removing tower is 100-800; S2: sending the liquid phase light-defluorobenzene produced in the above step S1 into a de-weighting tower for distillation treatment, producing gas-phase electronic-grade fluorobenzene from the top of the de-weighting tower, and producing liquid-phase heavy components from the bottom of the de-weighting tower; the de-weighting tower has a theoretical plate number of 30-80, a feed position of the 15th-60th plate, an operating pressure of 0.08-0.12MPaG, an operating temperature of 110-149°C, and a reflux ratio of 1-10; Wherein, a first thermal coupling heat exchanger is provided on the fluorobenzene raw material conveying pipeline connected to the lightness removal tower; A second heat-coupled heat exchanger connection loop and a lightness removal tower reboiler connection loop are respectively provided in parallel between the bottom of the lightness removal tower and the bottom of the lightness removal tower; the gas-phase electronic-grade fluorobenzene is sent to the second heat-coupled heat exchanger as a hot stream of the second heat-coupled heat exchanger to provide heat for heating the bottom material of the lightness removal tower, thereby reducing the heat load of the lightness removal tower reboiler; The hot stream outlet of the second thermally coupled heat exchanger is connected to the inlet of the deweighting tower condenser, and the liquid electronic-grade fluorobenzene treated by the deweighting tower condenser is refluxed to the top material reflux inlet of the deweighting tower in one way, and is sent to the first thermally coupled heat exchanger in the other way as the hot stream of the first thermally coupled heat exchanger; The hot stream outlet of the first thermally coupled heat exchanger serves as a production outlet for electronic-grade fluorobenzene products, the purity of which is not less than 99.99%, and the yield of which is not less than 98%.

[0008] Preferably, a raw material delivery pump is provided on the fluorobenzene raw material delivery pipeline, wherein the outlet of the raw material delivery pump is connected to the cold stream inlet of the first thermally coupled heat exchanger, and the cold stream outlet of the first thermally coupled heat exchanger is connected to the feed inlet of the lightness removal tower.

[0009] Preferably, the top outlet of the de-weighting tower is connected to the hot stream inlet of the second thermally coupled heat exchanger, the cold stream inlet of the second thermally coupled heat exchanger is connected to the first bottom material outlet of the de-weighting tower, and the cold stream outlet of the second thermally coupled heat exchanger is connected to the first bottom material reflux inlet of the de-weighting tower; the liquid phase inlet of the reboiler of the de-weighting tower is connected to the second bottom material outlet of the de-weighting tower, and the liquid phase outlet of the reboiler of the de-weighting tower is connected to the second bottom material reflux inlet of the de-weighting tower.

[0010] Preferably, the liquid phase outlet of the deweighting tower condenser is connected to the inlet of the deweighting tower reflux tank, and the outlet of the deweighting tower reflux tank is connected to the inlet of the deweighting tower reflux pump; wherein, one outlet of the deweighting tower reflux pump is connected to the top material reflux inlet of the deweighting tower, and the other outlet is connected to the hot flow inlet of the first thermally coupled heat exchanger.

[0011] Preferably, the top outlet of the light-removal tower is connected to the inlet of the light-removal tower condenser, the liquid phase outlet of the light-removal tower condenser is connected to the inlet of the light-removal tower reflux tank, and the outlet of the light-removal tower reflux tank is connected to the inlet of the light-removal tower reflux pump; one outlet of the light-removal tower reflux pump is used as the extraction outlet of the light component, and the other outlet is connected to the top material reflux inlet of the light-removal tower.

[0012] Preferably, the bottom extraction port of the light removal tower is connected to the feed port of the heavy removal tower, and a light removal tower bottom extraction pump is provided on the connecting pipeline between the two to realize the extraction of liquid-phase light-removed fluorobenzene; a heavy removal tower reboiler connecting loop is provided between the bottom of the heavy removal tower and its kettle; the bottom extraction port of the heavy removal tower is connected to the heavy removal tower bottom extraction pump to realize the extraction of liquid-phase heavy components.

[0013] It should be particularly noted that the fluorobenzene raw material involved in the entire application is a crude fluorobenzene obtained by a known fluorobenzene synthesis process, usually a fluorobenzene pyrolysis reaction liquid obtained through salt formation, diazotization and pyrolysis steps, and its fluorobenzene content after treatment will not exceed 99.5%; preferably, the fluorobenzene raw material is a crude fluorobenzene obtained by neutralization of the fluorobenzene pyrolysis reaction liquid; the fluorobenzene content in the fluorobenzene raw material is 96-99%; the light component includes at least one of benzene and toluene.

[0014] Preferably, the operating temperature of the light-removal tower is 60-100°C, and the reflux ratio of the light-removal tower is 150-400; the light-removal tower adopts such process operating conditions to better achieve the separation of light components, while ensuring that the temperature gradient in the light-removal tower is reasonable.

[0015] Preferably, the operating temperature of the deweighting tower is 120-140°C, and the reflux ratio of the deweighting tower is 2-3; the deweighting tower adopts such process operating conditions to not only ensure the purity of the obtained electronic grade fluorobenzene product, but also provide a sufficient temperature difference to ensure the thermal coupling effect of the first thermal coupling heat exchanger and the second thermal coupling heat exchanger.

[0016] Preferably, the light-removal tower is filled with structured packing, more preferably CY wire mesh structured packing; the bottom layer of the heavy-removal tower is filled with random packing, more preferably MELLPAK Sulzer random packing, and the remaining layers are filled with structured packing, more preferably CY wire mesh structured packing; the scheme of using this packing combination can improve the mass transfer efficiency, while ensuring that the bottom of the light-removal tower and the bottom of the heavy-removal tower both have good liquid distribution.

[0017] Preferably, the reboiler of the light-removal tower adopts a thermal syphon reboiler, and the reboiler of the weight-removal tower also adopts a thermal syphon reboiler. The use of a thermal syphon reboiler can improve heat transfer efficiency and reduce energy loss; the condenser of the weight-removal tower is a heat exchanger that uses circulating water as a cold stream, and the condenser of the light-removal tower is also a heat exchanger that uses circulating water as a cold stream. Using circulating water as a cold stream can make full use of the existing cooling water system and reduce operating costs.

[0018] It should be particularly noted that the "feed position" referred to in the entire application refers to the number of tower plates from the top of the light-removal tower or the heavy-removal tower to the corresponding feed port; the "MPaG" referred to in the entire application refers to the gauge pressure, which can also be expressed in MPa(G); the "reflux ratio" referred to in the entire application refers to the ratio of the reflux flow rate from the top of the light-removal tower or the top of the heavy-removal tower returning to its corresponding tower to the extraction flow rate from its corresponding top.

[0019] The applicant has found that by combining the application of specific process parameters (especially the specific reflux ratio setting of the lightness removal tower) and the use of a specific thermal coupling process, a surprising refining effect can be obtained, and at the same time, the advantages of high purity, high yield, low energy consumption and continuous production implementation can be obtained; specifically, the present invention adopts a lightness removal tower and a heavyness removal tower as the main devices for preparing electronic-grade fluorobenzene, set under specific process parameter conditions, and sequentially perform lightness removal distillation and heavyness removal distillation on the fluorobenzene raw material. At the same time, the present application particularly proposes to set a first thermal coupling heat exchanger on the fluorobenzene raw material conveying pipeline connected to the lightness removal tower, and set a second thermal coupling heat exchanger connecting loop between the bottom of the lightness removal tower and the kettle of the lightness removal tower. By utilizing the thermal coupling effect of the first thermal coupling heat exchanger and the second thermal coupling heat exchanger, on the basis of ensuring a high yield of electronic-grade fluorobenzene products, energy consumption is greatly reduced and energy utilization efficiency is improved; and the device structures adopted in the present application are all conventional devices, which are simple in structure and easy to operate, and are suitable for industrial continuous production applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the connection structure of the device used to prepare electronic grade fluorobenzene in Example 1 of the present invention; Figure numerals: lightness removal tower 1, heaviness removal tower 2, lightness removal tower condenser 3, lightness removal tower reboiler 4, heaviness removal tower condenser 5, heaviness removal tower reboiler 6, first thermally coupled heat exchanger 7, second thermally coupled heat exchanger 8, lightness removal tower reflux tank 9, heaviness removal tower reflux tank 10, raw material delivery pump 11, lightness removal tower reflux pump 12, lightness removal tower bottom extraction pump 13, heaviness removal tower reflux pump 14, heaviness removal tower bottom extraction pump 15. DETAILED DESCRIPTION

[0021] This embodiment provides a method for preparing electronic grade fluorobenzene, comprising the following steps: S1: The fluorobenzene raw material is fed into a light-removing tower for distillation treatment, and the light components are extracted from the top of the light-removing tower, and the liquid phase light-removed fluorobenzene after the light components are removed is extracted from the bottom of the light-removing tower; the number of theoretical plates of the light-removing tower is 30-60, the feed position is the 15th-40th, the operating pressure is 0-0.08MPaG, the operating temperature is 60-110°C, and the reflux ratio of the light-removing tower is 100-800; preferably, in this embodiment, the fluorobenzene raw material is the crude fluorobenzene obtained by neutralization of the fluorobenzene pyrolysis reaction liquid; the fluorobenzene content in the fluorobenzene raw material is 96-99%; the light components include at least one of benzene and toluene; S2: The liquid phase light-defluorobenzene produced in the above step S1 is sent to a de-weighting tower for distillation treatment, gas-phase electronic-grade fluorobenzene is produced from the top of the de-weighting tower, and liquid-phase heavy components are produced from the bottom of the de-weighting tower; the theoretical plate number of the de-weighting tower is 30-80, the feed position is the 15th-60th plate, the operating pressure is 0.08-0.12MPaG, the operating temperature is 110-149°C, and the reflux ratio of the de-weighting tower is 1-10; Among them, a first thermally coupled heat exchanger is provided on the fluorobenzene raw material conveying pipeline connected to the lightness removal tower; a second thermally coupled heat exchanger connecting loop and a lightness removal tower reboiler connecting loop are respectively provided in parallel between the bottom of the lightness removal tower and the bottom of the lightness removal tower; gaseous electronic-grade fluorobenzene is sent to the second thermally coupled heat exchanger as the hot flow stream of the second thermally coupled heat exchanger to provide heat for heating the bottom material of the lightness removal tower and reduce the heat load of the lightness removal tower reboiler; the hot flow stream outlet of the second thermally coupled heat exchanger is connected to the inlet of the de-weight removal tower condenser, and the liquid-phase electronic-grade fluorobenzene treated by the de-weight removal tower condenser is refluxed to the top material reflux inlet of the de-weight removal tower in one way, and is sent to the first thermally coupled heat exchanger in the other way as the hot flow stream of the first thermally coupled heat exchanger; the hot flow stream outlet of the first thermally coupled heat exchanger serves as the production outlet of the electronic-grade fluorobenzene product, and the purity of the electronic-grade fluorobenzene product is not less than 99.99%, and the yield thereof is not less than 98%.

[0022] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0023] Example 1: Please see Figure 1 As shown, the device for preparing electronic grade fluorobenzene in this embodiment 1 includes the following: Lightness removal tower 1, heaviness removal tower 2, lightness removal tower condenser 3, lightness removal tower reboiler 4, heaviness removal tower condenser 5, heaviness removal tower reboiler 6, first thermal coupling heat exchanger 7, second thermal coupling heat exchanger 8, lightness removal tower reflux tank 9, heaviness removal tower reflux tank 10, raw material delivery pump 11, lightness removal tower reflux pump 12, lightness removal tower bottom extraction pump 13, heaviness removal tower reflux pump 14, heaviness removal tower bottom extraction pump 15; wherein, A first thermally coupled heat exchanger 7 is provided on the fluorobenzene raw material delivery pipeline connected to the lightness removal tower 1; a raw material delivery pump 11 is provided on the fluorobenzene raw material delivery pipeline, the outlet of the raw material delivery pump 11 is connected to the cold stream inlet of the first thermally coupled heat exchanger 7, and the cold stream outlet of the first thermally coupled heat exchanger 7 is connected to the feed inlet of the lightness removal tower 1; The top outlet of the light-removal tower 1 is connected to the inlet of the light-removal tower condenser 3, the liquid phase outlet of the light-removal tower condenser 3 is connected to the inlet of the light-removal tower reflux tank 9, and the outlet of the light-removal tower reflux tank 9 is connected to the inlet of the light-removal tower reflux pump 12; one outlet of the light-removal tower reflux pump 12 is used as a light component extraction outlet, and the other outlet is connected to the top material reflux inlet of the light-removal tower 1; The bottom extraction port of the light removal tower 1 is connected to the feed port of the heavy removal tower 2, and a light removal tower bottom extraction pump 13 is provided on the connecting pipeline between the two to realize the extraction of liquid-phase light-removed fluorobenzene, and the extracted liquid-phase light-removed fluorobenzene is sent to the heavy removal tower 2 for distillation treatment; a heavy removal tower reboiler 6 connecting loop is provided between the bottom of the heavy removal tower 2 and its kettle; the bottom extraction port of the heavy removal tower 2 is connected to the heavy removal tower bottom extraction pump 15 to realize the extraction of liquid-phase heavy components; The gaseous electronic-grade fluorobenzene is extracted from the top of the de-weighting tower 2; a second thermally coupled heat exchanger 8 connecting loop and a lightness-removing tower reboiler 4 connecting loop are respectively arranged in parallel between the bottom of the lightness-removing tower 1 and the bottom of the lightness-removing tower; the gaseous electronic-grade fluorobenzene is fed into the second thermally coupled heat exchanger 8 as the heat stream of the second thermally coupled heat exchanger 8 to provide heat for heating the bottom material of the lightness-removing tower 1 and reduce the heat load of the lightness-removing tower reboiler 4; the heat stream outlet of the second thermally coupled heat exchanger 8 is connected to the inlet of the de-weighting tower condenser 5, and the liquid-phase electronic-grade fluorobenzene treated by the de-weighting tower condenser 5 is refluxed to the top material reflux inlet of the weight-removing tower 2 in one way, and fed into the first thermally coupled heat exchanger 7 in the other way as the heat stream of the first thermally coupled heat exchanger 7; The top outlet of the de-weighting tower 2 is connected to the hot stream inlet of the second thermally coupled heat exchanger 8, the cold stream inlet of the second thermally coupled heat exchanger 8 is connected to the first bottom material outlet of the de-weighting tower 1, and the cold stream outlet of the second thermally coupled heat exchanger 8 is connected to the first bottom material reflux inlet of the de-weighting tower 1; the liquid phase inlet of the de-weighting tower reboiler 4 is connected to the second bottom material outlet of the de-weighting tower 1, and the liquid phase outlet of the de-weighting tower reboiler 4 is connected to the second bottom material reflux inlet of the de-weighting tower 1; The liquid phase outlet of the de-weighting tower condenser 5 is connected to the inlet of the de-weighting tower reflux tank 10, and the outlet of the de-weighting tower reflux tank 10 is connected to the inlet of the de-weighting tower reflux pump 14; one outlet of the de-weighting tower reflux pump 14 is connected to the reflux inlet of the top material of the de-weighting tower 2, and the other outlet is connected to the hot stream inlet of the first thermally coupled heat exchanger 7; the hot stream outlet of the first thermally coupled heat exchanger 7 is used as an electronic grade fluorobenzene product (i.e. Figure 1 The outlet for the “product” shown).

[0024] In this embodiment 1, the light-removal tower 1 is filled with CY wire mesh structured packing; the bottom layer of the de-weighting tower 2 is filled with random MELLPAK Sulzer packing, and the remaining layers are filled with CY wire mesh structured packing; the light-removal tower reboiler 4 and the de-weighting tower reboiler 6 are both thermosyphon reboilers; the light-removal tower condenser 3 and the de-weighting tower condenser 5 are both heat exchangers using circulating water as the cold stream.

[0025] In this embodiment 1, the fluorobenzene raw material is a crude fluorobenzene obtained by neutralizing the fluorobenzene pyrolysis reaction liquid from the upstream fluorobenzene synthesis section; wherein the feed temperature of the fluorobenzene raw material is 6° C., the feed pressure is 0.5 MPaG, the fluorobenzene content of the fluorobenzene raw material is 96%, and the fluorobenzene raw material also contains benzene, phenol, aniline, o-toluidine, m-toluidine, p-toluidine, phenylenediamine, nitrobenzene, toluene, chlorobenzene, water, 2,2'-difluorobiphenyl, 4,4'-difluorobiphenyl and other components; the method for preparing electronic grade fluorobenzene comprises the following operation process: The fluorobenzene raw material is transported to the first thermally coupled heat exchanger 7 at a flow rate of 1670 kg / h by the raw material delivery pump 11, and after being preheated and heated by the first thermally coupled heat exchanger 7 (i.e., heat exchanged with the electronic-grade fluorobenzene product), it enters the light-removal tower 1 for distillation treatment; the light components at the top of the light-removal tower 1 are partially refluxed after being condensed by the light-removal tower condenser 3, and partially extracted as light components; a part of the bottom material of the light-removal tower 1 is heated by the second thermally coupled heat exchanger 8 connecting loop and the light-removal tower reboiler 4 connecting loop, and then returned to the kettle of the light-removal tower 1, and the other part is extracted through the bottom extraction outlet to remove the light-removal fluorobenzene in the liquid phase; Wherein, in the present embodiment 1, the process operation parameters of the light removal tower 1 are set as follows: the number of theoretical plates is 50, the feed position is the 25th, the operating pressure is 0-0.04MPaG, the operating temperature is 60-90°C, and the reflux ratio of the light removal tower 1 is 245; when the top temperature of the light removal tower 1 is lower than 60°C, the light components (including benzene and toluene) are intermittently produced from the top of the light removal tower 1, and the total average flow rate is 8kg / h, and the light component production is stopped when the top temperature reaches 70°C or the liquid level of the light removal tower 1 is lower than 20%; the light removal tower reboiler 4 uses steam with a pressure of 0.6MPaG as a heat source, and provides 30kW of heat through the light removal tower reboiler 4 after the light component production is stable; the bottom of the light removal tower 1 produces a liquid phase light fluorobenzene with a flow rate of 945kg / h; The liquid phase light-depleted fluorobenzene extracted from the light-depleting tower 1 is sent to the middle section of the de-weighting tower 2 through the light-depleting tower bottom extraction pump 13 for pressurized distillation treatment; the product vapor (i.e., gas-phase electronic-grade fluorobenzene) extracted from the top of the de-weighting tower 2 enters the de-weighting tower condenser 5 after passing through the second thermally coupled heat exchanger 8 for condensation, and a part of it refluxes back to the top of the de-weighting tower 2, and the other part is used as the hot flow stream of the first thermally coupled heat exchanger 7, and the electronic-grade fluorobenzene product is extracted from the hot flow stream outlet of the first thermally coupled heat exchanger 7; wherein, the process operation parameters of the de-weighting tower 2 are set as follows: The number of theoretical plates is 35, the feed position is the 20th plate, the operating pressure is 0.1 MPaG, the operating temperature is 120-140°C, and the reflux ratio of the de-weighting tower 2 is 3.35; the feed enters the middle section of the de-weighting tower 2 through the extraction pump at the bottom of the de-weighting tower; 3473 kg / h, 0.1 MPaG, 110°C gas-phase electronic-grade fluorobenzene is extracted from the top of the de-weighting tower 2; 1588 kg / h, 40°C electronic-grade fluorobenzene product is extracted from the hot flow outlet of the first thermally coupled heat exchanger 7; 74 kg of liquid-phase heavy components are extracted from the bottom of the de-weighting tower.

[0026] Detected by gas chromatograph Agilent 7890A, the purity of the electronic grade fluorobenzene product obtained in Example 1 was 99.996%, and the yield was about 99.2%; Compared with the prior art method of preparing fluorobenzene by intermittent distillation of steam, the energy consumption of the preparation method of electronic-grade fluorobenzene provided in Example 1 is reduced by about 35%; compared with the combination of centrifugal separation, neutralization, filtration, phase separation, and distillation adopted in CN118791354A, the energy consumption of the preparation method of electronic-grade fluorobenzene provided in Example 1 is reduced by about 40%.

[0027] Example 2: The remaining technical scheme of this Example 2 is the same as that of Example 1, except that, in this Example 2, the process operation parameters of the light-removal tower 1 are set to: the number of theoretical plates is 60, the feed position is the 35th, the operating pressure is 0.04-0.08MPaG, the operating temperature is 60-100°C, and the reflux ratio of the light-removal tower 1 is 320; detected by gas chromatograph Agilent 7890A, the purity of the electronic-grade fluorobenzene product obtained in this Example 2 is 99.998%, and the yield is about 99.4%.

[0028] Embodiment 3: The remaining technical scheme of this embodiment 3 is the same as that of embodiment 1, except that, in this embodiment 3, the process operation parameters of the light-removal tower 1 are set as follows: the number of theoretical plates is 40, the feed position is the 20th, the operating pressure is 0-0.04MPaG, the operating temperature is 60-90°C, and the reflux ratio of the light-removal tower 1 is 200; detected by gas chromatograph Agilent 7890A, the purity of the electronic-grade fluorobenzene product obtained in this embodiment 3 is 99.992%, and the yield is about 98.7%.

[0029] Embodiment 4: The rest of the technical scheme of this embodiment 4 is the same as that of embodiment 1, except that, in this embodiment 4, the process operation parameters of the deweighting tower 2 are set as follows: the number of theoretical plates of the deweighting tower 2 is 60, the feed position is the 45th plate, the operating pressure is 0.12 MPaG, the operating temperature is 110-149°C, and the reflux ratio of the deweighting tower 2 is 2.5; detected by gas chromatograph Agilent 7890A, the purity of the electronic grade fluorobenzene product obtained in this embodiment 4 is 99.997%, and the yield is about 98.9%.

[0030] Example 5: The remaining technical scheme of this Example 5 is the same as that of Example 1, except that, in this Example 5, the process operation parameters of the deweighting tower 2 are set as follows: the number of theoretical plates of the deweighting tower 2 is 80, the feed position is the 45th plate, the operating pressure is 0.08 MPaG, the operating temperature is 120-140°C, and the reflux ratio of the deweighting tower 2 is 2.5; detected by gas chromatograph Agilent 7890A, the purity of the electronic grade fluorobenzene product obtained in this Example 5 is 99.997%, and the yield is about 99.5%.

[0031] Comparative Example 1: The remaining technical solutions of this comparative example 1 are the same as those of Example 1, except that, in this comparative example 1, the second thermally coupled heat exchanger 8 and its related connecting pipelines are eliminated; the top outlet of the deweighting tower 2 is connected to the inlet of the deweighting tower condenser 5; Detected by gas chromatograph Agilent 7890A, the purity of the fluorobenzene product obtained in Comparative Example 1 was 99.987%, and the yield was about 98.5%; and the energy consumption of Comparative Example 1 increased by about 32% compared with Example 1.

[0032] Comparative Example 2: The rest of the technical scheme of this comparative example 2 is the same as that of Example 1, except that, in this comparative example 2, the first thermally coupled heat exchanger 7 and its related connecting pipelines are cancelled; the outlet of the raw material delivery pump 11 is connected to the feed port of the de-light tower 1, and another outlet of the de-weight tower reflux pump 14 is used as the production port of the fluorobenzene product; after detection by gas chromatograph Agilent 7890A, the purity of the fluorobenzene product obtained in this comparative example 2 is 99.993%, and the yield is about 99.2%; and the energy consumption of this comparative example 2 is increased by about 18% relative to that of Example 1.

[0033] Comparative Example 3: The remaining technical solutions of this comparative example 3 are the same as those of Example 1, except that, in this comparative example 3, the deheaving tower 2 and its related connection structures are eliminated; the bottom outlet of the deheaving tower 1 is directly used as the outlet of the fluorobenzene product; and the purity of the fluorobenzene product obtained in this comparative example 3 is about 98.9% as detected by gas chromatograph Agilent 7890A.

[0034] Comparative Example 4: The remaining technical solutions of this comparative example 4 are the same as those of Example 1, except that, in this comparative example 4, the light removal tower 1 and its related connection structures are eliminated; the outlet of the raw material delivery pump 11 is connected to the feed port of the heavy removal tower 2; and the purity of the fluorobenzene product obtained in this comparative example 4 is about 99.1% as detected by gas chromatograph Agilent 7890A.

[0035] Comparative Example 5: The remaining technical solutions of this comparative example 5 are the same as those of Example 1, except that, in this comparative example 5, the reflux ratio of the light removal tower 1 is 50; and the purity of the fluorobenzene product obtained in this comparative example 5 is about 99.72% as detected by gas chromatograph Agilent 7890A.

[0036] Comparative Example 6: The remaining technical solutions of this comparative example 6 are the same as those of Example 1, except that, in this comparative example 6, the reflux ratio of the light removal tower 1 is 20; and the purity of the fluorobenzene product obtained in this comparative example 6 is about 99.58% as detected by gas chromatograph Agilent 7890A.

[0037] Comparative Example 7: The remaining technical solutions of this comparative example 7 are the same as those of Example 1, except that, in this comparative example 7, the reflux ratio of the light removal tower 1 is 10; and the purity of the fluorobenzene product obtained in this comparative example 7 is about 99.4% as detected by gas chromatograph Agilent 7890A.

[0038] Comparative Example 8: The remaining technical solutions of this comparative example 8 are the same as those of Example 1, except that, in this comparative example 8, the reflux ratio of the light removal tower 1 is 100; and the purity of the fluorobenzene product obtained in this comparative example 8 is about 99.92% as detected by gas chromatograph Agilent 7890A.

[0039] Comparative Example 9: The remaining technical solutions of this comparative example 9 are the same as those of Example 1, except that, in this comparative example 9, the reflux ratio of the light removal tower 1 is 120; and the purity of the fluorobenzene product obtained in this comparative example 9 is about 99.98% as detected by gas chromatograph Agilent 7890A.

[0040] Comparative Example 10: The remaining technical solutions of this comparative example 10 are the same as those of Example 1, except that, in this comparative example 10, the reflux ratio of the deweighting tower 2 is 15; detected by gas chromatograph Agilent 7890A, the purity of the fluorobenzene product obtained in this comparative example 10 is about 99.991%; however, the energy consumption is significantly increased relative to that of Example 1, and the operating conditions of the deweighting tower 2 have safety hazards.

[0041] The fluorobenzene products with a purity of less than 99.99% obtained in the above comparative examples need to be further distilled, which not only increases the difficulty of separation but also significantly increases the energy consumption. Compared with the related methods recorded in the background technology, they have no advantages and even perform worse.

[0042] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0043] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing electronic grade fluorobenzene, characterized in that: At least the following steps are included: S1: feeding the fluorobenzene raw material into a light-removing tower for distillation treatment, extracting the light components from the top of the light-removing tower, and extracting the liquid light-removing fluorobenzene from the bottom of the light-removing tower after the light components are removed; the light-removing tower has 30-60 theoretical plates, the 15th-40th feed position, the operating pressure of 0-0.08MPaG, the operating temperature of 60-110°C, and the reflux ratio of the light-removing tower is 100-800; S2: sending the liquid phase light-defluorobenzene produced in the above step S1 into a de-weighting tower for distillation treatment, producing gas-phase electronic-grade fluorobenzene from the top of the de-weighting tower, and producing liquid-phase heavy components from the bottom of the de-weighting tower; the de-weighting tower has a theoretical plate number of 30-80, a feed position of the 15th-60th plate, an operating pressure of 0.08-0.12MPaG, an operating temperature of 110-149°C, and a reflux ratio of 1-10; Wherein, a first thermal coupling heat exchanger is provided on the fluorobenzene raw material conveying pipeline connected to the lightness removal tower; A second heat-coupled heat exchanger connection loop and a lightness-removal tower reboiler connection loop are respectively provided in parallel between the bottom of the lightness-removal tower and the bottom of the lightness-removal tower; the gas-phase electronic-grade fluorobenzene is fed into the second heat-coupled heat exchanger as a heat stream of the second heat-coupled heat exchanger; The hot stream outlet of the second thermally coupled heat exchanger is connected to the inlet of the de-weighting tower condenser, and the liquid electronic-grade fluorobenzene treated by the de-weighting tower condenser is refluxed to the top material reflux inlet of the de-weighting tower in one way, and is sent to the first thermally coupled heat exchanger in the other way as the hot stream of the first thermally coupled heat exchanger; The hot stream outlet of the first thermally coupled heat exchanger serves as a production outlet for electronic-grade fluorobenzene products.

2. The method for preparing electronic grade fluorobenzene according to claim 1, characterized in that: A raw material delivery pump is provided on the fluorobenzene raw material delivery pipeline, wherein the outlet of the raw material delivery pump is connected to the cold stream inlet of the first thermally coupled heat exchanger, and the cold stream outlet of the first thermally coupled heat exchanger is connected to the feed inlet of the lightness removal tower.

3. The method for preparing electronic grade fluorobenzene according to claim 1 or 2, characterized in that: The top outlet of the de-weighting tower is connected to the hot stream inlet of the second thermally coupled heat exchanger, the cold stream inlet of the second thermally coupled heat exchanger is connected to the first bottom material outlet of the de-weighting tower, and the cold stream outlet of the second thermally coupled heat exchanger is connected to the first bottom material reflux inlet of the de-weighting tower; the liquid phase inlet of the reboiler of the de-weighting tower is connected to the second bottom material outlet of the de-weighting tower, and the liquid phase outlet of the reboiler of the de-weighting tower is connected to the second bottom material reflux inlet of the de-weighting tower.

4. The method for preparing electronic grade fluorobenzene according to claim 1, characterized in that: The liquid phase outlet of the deweighting tower condenser is connected to the inlet of the deweighting tower reflux tank, and the outlet of the deweighting tower reflux tank is connected to the inlet of the deweighting tower reflux pump; wherein, one outlet of the deweighting tower reflux pump is connected to the top material reflux inlet of the deweighting tower, and the other outlet is connected to the hot flow inlet of the first thermal coupling heat exchanger.

5. The method for preparing electronic grade fluorobenzene according to claim 1, characterized in that: The top outlet of the light-removal tower is connected to the inlet of the light-removal tower condenser, the liquid phase outlet of the light-removal tower condenser is connected to the inlet of the light-removal tower reflux tank, and the outlet of the light-removal tower reflux tank is connected to the inlet of the light-removal tower reflux pump; one outlet of the light-removal tower reflux pump is used as a light component extraction outlet, and the other outlet is connected to the top material reflux inlet of the light-removal tower.

6. The method for preparing electronic grade fluorobenzene according to claim 1, characterized in that: The bottom extraction port of the light removal tower is connected to the feed port of the heavy removal tower, and a light removal tower bottom extraction pump is provided on the connecting pipeline between the two to realize the extraction of liquid-phase light removal fluorobenzene; a heavy removal tower reboiler connecting loop is provided between the bottom of the heavy removal tower and its kettle; the bottom extraction port of the heavy removal tower is connected to the heavy removal tower bottom extraction pump to realize the extraction of liquid-phase heavy components.

7. The method for preparing electronic grade fluorobenzene according to claim 1, characterized in that: The fluorobenzene raw material is crude fluorobenzene obtained by neutralizing the fluorobenzene pyrolysis reaction liquid; the fluorobenzene content in the fluorobenzene raw material is 96-99%; and the light component includes at least one of benzene and toluene.

8. The method for preparing electronic grade fluorobenzene according to claim 1, characterized in that: The operating temperature of the light-removing tower is 60-100° C., and the reflux ratio of the light-removing tower is 150-400; the operating temperature of the heavy-removing tower is 120-140° C., and the reflux ratio of the heavy-removing tower is 2-3.

9. The method for preparing electronic grade fluorobenzene according to claim 1 or 8, characterized in that: The light-removing tower is filled with structured packing; the bottom layer of the heavy-removing tower is filled with random packing, and the remaining layers are filled with structured packing.

10. The method for preparing electronic grade fluorobenzene according to claim 1, characterized in that: The reboiler of the light removal tower is a thermosyphon reboiler; the condenser of the heavy removal tower is a heat exchanger using circulating water as a cold stream.

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