A process for the preparation of 4-fluoroacetophenone

Abstract

The application discloses a preparation method of 4-fluoroacetophenone and relates to the technical field of fine chemical synthesis. 2+ The preparation method adopts an ion exchange method to prepare Zn 2+ / Hbeta zeolite catalyst, fluorobenzene and acetyl chloride are used as reaction raw materials, a solvent-free continuous acylation reaction process is adopted, and a coupling reaction rectification mode is adopted to realize system heat removal; the preparation method realizes that the conversion rate of fluorobenzene is greater than or equal to 95.1%, the product selectivity of 4-fluoroacetophenone is greater than or equal to 98.1%, and the purity is greater than or equal to 99.4%. 2+ The Zn 2+ / Hbeta zeolite catalyst is non-corrosive and can be recycled for more than or equal to 15 times, and the Zn 2+ / Hbeta zeolite catalyst has an activity retention rate of greater than or equal to 95% after regeneration; the whole reaction process is free of waste acid discharge, has the advantages of high reaction efficiency and process environmental protection, is suitable for industrial large-scale production requirements, and can significantly reduce the comprehensive cost of industrial production.

Description

Technical Field

[0001] This invention relates to the field of fine chemical synthesis technology, and more specifically to a method for preparing 4-fluoroacetophenone. Background Technology

[0002] 4-Fluoroacetophenone is a key intermediate in the fields of pharmaceuticals, pesticides and new materials. Its core preparation route is the synthesis of fluorobenzene and acylation agents through Friedel-Crafts acylation reaction. This process is widely used in industrial production. Traditional Friedel-Crafts acylation reactions often use Lewis acids such as AlCl3 and ZnCl2 as catalysts. However, these processes have many inherent drawbacks that severely restrict their economic and environmental benefits for industrial application: First, Lewis acid catalysts are highly corrosive, requiring reaction equipment made of expensive Hastelloy materials, significantly increasing equipment purchase and maintenance costs. Second, the catalysts cannot be recycled, generating large amounts of waste acid after each reaction. The environmental treatment of this waste acid is complex and costly, failing to meet the requirements of green chemical development. Third, the reaction is exothermic and intense; if heat is not removed promptly, side reactions such as ortho-substitution and polyacylation can easily occur, resulting in the selectivity of 4-fluoroacetophenone remaining at only 85%–90%, reducing the yield of the target product. Fourth, the utilization rate of raw materials is low; the recovery of unreacted fluorobenzene and acyling agents is difficult and has a high loss rate, further increasing the total production cost.

[0003] In recent years, with increasingly stringent environmental regulations, solid acid catalysts, such as zeolites, heteropoly acids, and ion exchange resins, have gradually become a research hotspot for replacing traditional Lewis acid catalysts due to their advantages of low corrosivity and easy separation. However, existing solid acid catalysts still face insurmountable technical bottlenecks when applied to the fluorobenzoylation reaction to prepare 4-fluoroacetophenone, failing to meet the demands of industrial production: active centers are easily covered by carbon deposits or undergo structural degradation, resulting in short catalyst lifetimes; they lack efficient shape-selective catalytic performance, with insufficient para-selectivity and high content of byproducts, especially o-fluoroacetophenone; severe carbon deposition occurs during the reaction, requiring harsh catalyst regeneration conditions and resulting in low regeneration efficiency, making continuous and stable operation impossible; and overall continuous operation stability is poor, making it difficult to adapt to the large-scale, long-cycle requirements of industrial production involving tens of thousands of tons.

[0004] Therefore, it is necessary to propose a method for preparing 4-fluoroacetophenone to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to address the problems mentioned in the background section by providing a method for preparing 4-fluoroacetophenone, which involves modifying Zn... 2+ The synergistic effect of the Hβ zeolite catalyst and the coupled heat transfer process of reactive distillation has enabled the low-corrosion, high-selectivity and long-cycle continuous production of 4-fluoroacetophenone.

[0006] To achieve the above objectives, the present invention specifically adopts the following technical solution: A method for preparing 4-fluoroacetophenone includes the following steps: S1. Hβ zeolite was placed in a zinc nitrate solution and subjected to ion exchange at 60-70℃ for 2-3 hours. The mixture was then filtered, dried, and calcined sequentially to obtain modified Zn. 2+ / Hβ zeolite catalyst; pretreatment of fluorobenzene and acetyl chloride; S2. Mix the pretreated fluorobenzene and acetyl chloride in a certain proportion and continuously pass them into a container filled with modified Zn. 2+ In a fixed-bed catalytic reactor with Hβ zeolite catalyst, an acylation reaction was carried out at 50-60℃ to obtain a crude 4-fluoroacetophenone mixture. S3. The crude 4-fluoroacetophenone mixture is subjected to light-removal treatment and distillation treatment in sequence to obtain the 4-fluoroacetophenone product.

[0007] Preferably, the concentration of the zinc nitrate solution is 0.5~1.0 mol / L, the solid-liquid ratio of the Hβ zeolite to the zinc nitrate solution is 1:10~15, and the calcination temperature is 500~550℃ and the time is 3~4h.

[0008] Preferably, the specific method for pretreating fluorobenzene and acetyl chloride includes: dehydrating fluorobenzene to a moisture content of ≤0.05% by mass, and removing free chlorine from acetyl chloride to a free chlorine content of ≤0.01% by mass.

[0009] Preferably, the purity of the pretreated fluorobenzene is ≥99.5%, and the purity of the pretreated acetyl chloride is ≥99%.

[0010] Preferably, the molar ratio of fluorobenzene to acetyl chloride in the acylation reaction is 1:1.05; the operating pressure of the fixed-bed catalytic reactor is 0.1 MPa, and the space velocity of the reactants is 0.8~1.2 h⁻¹. -1 .

[0011] Preferably, the acylation reaction is carried out through heat transfer coupled via a reactive distillation column, with a reflux ratio of 2 to 3:1, a top temperature of 51 to 52°C, a bottom temperature of 140 to 145°C, and a heat transfer rate of 80 to 100 kJ / h.

[0012] Preferably, the modified Zn 2+ / Hβ zeolite catalyst is regenerated by calcination under a nitrogen atmosphere after 1200~1500h of use; The roasting temperature was 450℃ and the time was 2 hours.

[0013] Preferably, the specific method for obtaining the 4-fluoroacetophenone product by sequentially subjecting the crude 4-fluoroacetophenone mixture to light-weight removal and distillation includes: The crude 4-fluoroacetophenone mixture is fed into a light component removal column to remove light component impurities at 80-85℃, and then fed into a distillation column for distillation at 142-145℃.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Through Zn 2+ Directional bonding with Hβ zeolite ensures that Zn can be preserved within a temperature range of 60~70℃. 2+ It fully penetrates into the porous structure of Hβ zeolite, interacting with the H in the zeolite framework. + This achieves efficient energy exchange while avoiding excessively high temperatures that could cause the Hβ zeolite channels to collapse, and excessively low temperatures that could lead to Zn degradation. 2+ The problem of uneven load distribution.

[0015] 2. By coupling heat transfer in the reactive distillation column, side reactions such as isomerization and polyacylation of o-fluoroacetophenone caused by overheating are avoided, thereby improving the para-selectivity of 4-fluoroacetophenone. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The materials and instruments used in the following embodiments are all commercially available.

[0017] A method for preparing 4-fluoroacetophenone includes steps S1 to S3.

[0018] S1. Hβ zeolite was placed in a zinc nitrate solution and subjected to ion exchange at 60-70℃ for 2-3 hours. The mixture was then filtered, dried, and calcined sequentially to obtain modified Zn. 2+ / Hβ zeolite catalyst; pretreatment of fluorobenzene and acetyl chloride.

[0019] In step S1, the concentration of the zinc nitrate solution is 0.5~1.0 mol / L, the solid-liquid ratio of Hβ zeolite to zinc nitrate solution is 1:10~15, the calcination temperature is 500~550℃, and the time is 3~4 h; modified Zn 2+ Zn in Hβ zeolite catalyst 2+ The loading rate is 2~3%, modified Zn 2+ / Hβ zeolite catalyst with a specific surface area ≥350m² 2 / g, pore size is 0.5~0.8nm.

[0020] This preparation method uses Zn 2+Directional bonding with Hβ zeolite ensures that Zn can be preserved within a temperature range of 60~70℃. 2+ It fully penetrates into the porous structure of Hβ zeolite, interacting with the H in the zeolite framework. + This achieves efficient energy exchange while avoiding excessively high temperatures that could cause the Hβ zeolite channels to collapse, and excessively low temperatures that could lead to Zn degradation. 2+ The problem of uneven loading was addressed. After ion exchange, Zn underwent sequential filtration, drying, and calcination to further enhance its yield. 2+ The interaction with the Hβ zeolite framework enables Zn 2+ Firmly anchored to the active sites of Hβ zeolite, it effectively avoids the degradation of Zn by traditional homogeneous catalysts or simple supported catalysts during the reaction process. 2+ The catalytic activity decreases due to loss. That is, this preparation method utilizes Zn... 2+ Ion exchange modification of Hβ zeolite enhances its acid strength and pore structure, thereby improving its adsorption and directional catalytic ability for fluorobenzene. Furthermore, the modified Zn obtained by this preparation method… 2+ / Hβ zeolite catalyst is non-corrosive, and the equipment can be made of 316L stainless steel.

[0021] The specific method for pretreating fluorobenzene and acetyl chloride includes: dehydrating fluorobenzene to a moisture content ≤0.05% by mass, and removing free chlorine from acetyl chloride to a free chlorine content ≤0.01% by mass. The purity of the pretreated fluorobenzene is ≥99.5%, and the purity of the pretreated acetyl chloride is ≥99%.

[0022] S2. Mix the pretreated fluorobenzene and acetyl chloride in a certain proportion and continuously pass them into a container filled with modified Zn. 2+ In a fixed-bed catalytic reactor with Hβ zeolite catalyst, an acylation reaction was carried out at 50-60℃ to obtain a crude 4-fluoroacetophenone mixture.

[0023] Fluorobenzene and acetyl chloride are pretreated and then directly fed into a fixed-bed catalytic reactor to avoid hydrolysis side reactions caused by contact with water during storage.

[0024] Specifically, in the acylation reaction, the molar ratio of fluorobenzene to acetyl chloride is 1:1.05. The fluorobenzene and acetyl chloride are first mixed uniformly using a static mixer before being introduced into the fixed-bed catalytic reactor. The operating pressure of the fixed-bed catalytic reactor is 0.1 MPa, and the space velocity of the reactants is 0.8–1.2 h⁻¹. -1 .

[0025] Furthermore, during the acylation reaction, heat is coupled through a reactive distillation column with a reflux ratio of 2~3:1, a top temperature of 51~52℃, a bottom temperature of 140~145℃, and a heat transfer rate of 80~100kJ / h.

[0026] Acylation is a strongly exothermic reaction. Conventional cooling can only remove macroscopic heat from the system, which can easily lead to local micro-overheating in fixed-bed catalytic reactors. However, the coupled heat transfer of reactive distillation columns achieves uniform heat transfer throughout the entire system through gas-liquid phase change and material flow within the column. This avoids side reactions such as isomerization and polyacylation of o-fluoroacetophenone caused by overheating and improves the para-selectivity of 4-fluoroacetophenone.

[0027] Unreacted feedstock is removed from the top of the distillation column, while a crude 4-fluoroacetophenone mixture is obtained from the bottom. The reaction process is solvent-free, avoiding solvent contamination and separation costs. Furthermore, this coupled reactive distillation process not only achieves heat transfer from the feedstock but also recovers unreacted feedstock from the top of the column, improving atom economy.

[0028] S3. The crude 4-fluoroacetophenone mixture is subjected to light-removal treatment and distillation treatment in sequence to obtain the 4-fluoroacetophenone product.

[0029] Specifically, the crude 4-fluoroacetophenone mixture is fed into a light component removal column to remove light component impurities in the system at 80~85℃, and then fed into a distillation column for distillation at 142~145℃; wherein the purification yield is ≥98%.

[0030] This process differs from the traditional segmented operation mode of reaction followed by separation. By using the continuous reaction in the fixed-bed catalytic reactor in step S2 and the sequential removal of light components and distillation in step S3, a closed-loop production system is formed.

[0031] Specifically, in step S2, the pretreated fluorobenzene and acetyl chloride are continuously fed into a fixed-bed catalytic reactor, where the acylation reaction is completed at 50-60°C. The resulting crude 4-fluoroacetophenone mixture can be directly transported to subsequent steps via pipeline, eliminating the need for intermediate storage and transfer, thus significantly shortening the production cycle. Simultaneously, the removal of light-boiling components in step S3 rapidly removes the byproduct hydrogen chloride and unreacted low-boiling-point raw materials, such as fluorobenzene and acetyl chloride. The removed low-boiling-point components can be recovered and returned to step S2 to participate in the reaction again, improving raw material utilization. Subsequent distillation specifically separates high-boiling-point impurities. The entire separation process requires no additional heating or cooling; the basic operating temperature can be maintained using the residual heat of the reaction system, resulting in lower energy consumption compared to traditional processes, thus balancing efficiency and energy saving requirements.

[0032] This preparation method, from raw material pretreatment to final product purification, does not use any organic solvents throughout the entire process, relying solely on fluorobenzene itself as the reaction medium. This avoids the problems of solvent residue and subsequent solvent separation difficulties associated with traditional processes that use organic solvents such as toluene and xylene. Furthermore, all steps in this process are completed within closed pipelines and equipment, such as the modified Zn in step S1. 2+The preparation process of the / Hβ zeolite catalyst is carried out in a closed manner, avoiding the volatilization of zinc nitrate solution and the fugitive emission of roasting tail gas. The fixed-bed catalytic reactor in step S2 adopts a sealed structure, which can effectively control the leakage of volatile raw materials such as acetyl chloride and fluorobenzene, as well as the reaction byproduct hydrogen chloride. After the removal of light components, the hydrogen chloride can be centrally recovered and reused, with no toxic or harmful gas emissions. The removal of light components and distillation in step S3 also adopt a closed design, with a collection device only installed at the product outlet.

[0033] The modified Zn prepared by this method 2+ The / Hβ zeolite catalyst was regenerated by calcination under a nitrogen atmosphere after 1200~1500h of use, followed by modification with Zn. 2+ / Hβ zeolite catalyst activity ≥95%; wherein, the calcination temperature is 450℃ and the time is 2h.

[0034] The present invention will be further illustrated by the following examples, but these examples do not limit the scope of the invention.

[0035] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, equipment, and materials similar to or equivalent to those described, used, and materials in the embodiments of this invention may be used to implement this invention.

[0036] Example 1 This embodiment provides a method for preparing 4-fluoroacetophenone, including the following steps: Preparation of modified Zn 2+ / Hβ zeolite catalyst: 100g of Hβ zeolite was placed in a 1.0mol / L zinc nitrate solution (solid-liquid ratio 1:12), and ion exchange was performed at 65℃ for 2.5h. After filtration and washing, the solution was dried at 120℃ for 5h and then calcined at 550℃ for 3.5h to obtain Zn. 2+ Modified Zn with a loading of 2.8% 2+ / Hβ zeolite catalyst; Preparation of crude 4-fluoroacetophenone mixture: fluorobenzene and acetyl chloride were pretreated; the pretreated fluorobenzene and acetyl chloride were mixed at a molar ratio of 1:1.05 and continuously passed through a mixture packed with modified Zn. 2+In a fixed-bed catalytic reactor using / Hβ zeolite catalyst, an acylation reaction was carried out at 55°C to obtain a crude 4-fluoroacetophenone mixture; the operating pressure of the fixed-bed catalytic reactor was 0.1 MPa, and the space velocity of the reactants was 1.0 h⁻¹. -1 The reflux ratio of the reactive distillation column is 3:1; the top temperature is 52℃, the bottom temperature is 140℃, and the heat transfer rate is 90kJ / h. Preparation of 4-fluoroacetophenone product: The crude 4-fluoroacetophenone mixture was subjected to light-removal treatment and distillation treatment in sequence to obtain the 4-fluoroacetophenone product.

[0037] The reaction products and catalyst properties were tested, and the results are as follows: The conversion rate of fluorobenzene reached 96.2%; the selectivity of 4-fluoroacetophenone was 98.5%, and the purity reached 99.6%; the content of the byproduct o-fluoroacetophenone was 0.8%; the purification yield was 98.7%; after continuous operation for 1300 hours, the modified Zn 2+ The Hβ zeolite catalyst still maintains 96% of its initial activity.

[0038] Example 2 This embodiment provides a method for preparing 4-fluoroacetophenone. The difference between this embodiment and Example 1 is that: Preparation of modified Zn 2+ / Hβ zeolite catalyst: calcined at 500℃, Zn 2+ The load is 2.3%; Preparation of crude 4-fluoroacetophenone mixture: An acylation reaction was carried out at 60℃ to obtain a crude 4-fluoroacetophenone mixture; the space velocity of the reactants was 1.2 h⁻¹. -1 The reflux ratio of the reactive distillation column is 2:1.

[0039] The reaction products and catalyst properties were tested, and the results are as follows: The conversion rate of fluorobenzene reached 95.8%; the selectivity of 4-fluoroacetophenone was 98.1%, and the purity reached 99.5%; the content of the byproduct o-fluoroacetophenone was 1.2%; the purification yield was 98.2%; after continuous operation for 1300 hours, the modified Zn 2+ The Hβ zeolite catalyst still maintains 95% of its initial activity.

[0040] Example 3 This embodiment provides a method for preparing 4-fluoroacetophenone. The difference between this embodiment and Example 1 is that: Preparation of modified Zn 2+ / Hβ zeolite catalyst: The concentration of zinc nitrate solution is 0.8 mol / L, the solid-liquid ratio is 1:15, the ion exchange time is 3 h, and the calcination time is 4 h; Preparation of crude 4-fluoroacetophenone mixture: An acylation reaction was carried out at 50℃ to obtain a crude 4-fluoroacetophenone mixture; the operating pressure of the fixed-bed catalytic reactor was 0.1 MPa, and the space velocity of the reactants was 0.8 h⁻¹. -1 The temperature at the top of the column was 51℃, the temperature at the bottom of the column was 142℃, and the heat transfer rate was 80kJ / h.

[0041] The reaction products and catalyst properties were tested, and the results are as follows: The conversion rate of fluorobenzene reached 95.1%; the selectivity of 4-fluoroacetophenone was 98.7%, and the purity reached 99.7%; the content of the byproduct o-fluoroacetophenone was 0.6%; the purification yield was 98.5%; after continuous operation for 1300 hours, the modified Zn 2+ The Hβ zeolite catalyst still retains 95.5% of its initial activity.

[0042] Example 4 This embodiment provides a method for preparing 4-fluoroacetophenone. The difference between this embodiment and Example 1 is that, after continuous operation for 1400 hours, the modified Zn is calcined at 450°C for 2 hours under a nitrogen atmosphere. 2+ The activity of the / Hβ zeolite catalyst recovered to 95.8%.

[0043] The reaction products of this embodiment were tested, and the results are as follows: The conversion rate of fluorobenzene reached 95.3%; the selectivity of 4-fluoroacetophenone was 98.0% and the purity reached 99.4%; the content of the byproduct o-fluoroacetophenone was 1.0%; and the purification yield was 98.0%.

[0044] Comparative Example 1 This comparative example did not use modified Zn. 2+ / Hβ zeolite catalyst, other operations are the same as in Example 1; The reaction product of Comparative Example 1 was tested, and the results are as follows: The conversion rate of fluorobenzene reached 62.8%; the selectivity of 4-fluoroacetophenone was 75.3% and the purity reached 97.2%; the content of the byproduct o-fluoroacetophenone was 18.5%; and the purification yield was 78.6%.

[0045] Comparative Example 2 This comparative example uses a conventional AlCl3 homogeneous catalyst, and other operations are the same as in Example 1; The reaction product of Comparative Example 2 was tested, and the results are as follows: The conversion rate of fluorobenzene reached 89.5%; the selectivity of 4-fluoroacetophenone was 68.2% and the purity reached 96.5%; the content of the byproduct o-fluoroacetophenone was 22.7%; and the purification yield was 72.3%.

[0046] Traditional AlCl3 homogeneous catalysts are completely deactivated after a single reaction, forming a large amount of aluminum-containing waste acid that requires neutralization treatment, cannot be recycled, and generates a large amount of industrial wastewater.

[0047] Comparative Example 3 Instead of using reactive distillation coupled with heat transfer, conventional cooling is employed. The reaction product of Comparative Example 3 was tested, and the results are as follows: The conversion rate of fluorobenzene reached 89.3%; the selectivity of 4-fluoroacetophenone was 92.6% and the purity reached 98.1%; the content of the byproduct o-fluoroacetophenone was 4.8%; and the purification yield was 81.5%.

[0048] Since conventional cooling can only remove macroscopic heat, there is obvious local micro-region overheating in the reactor, which leads to increased side reactions, decreased selectivity, and the inability to separate and recycle unreacted raw materials in situ, resulting in low atom economy.

[0049] The following is a comparative analysis of Examples 1, 2, 3, and 4 with Comparative Examples 1, 2, and 3: Table 1 summarizes the data from Examples 1, 2, 3, 4, Comparative Examples 1, 2, and 3. Table 1 Data Summary As shown in Table 1, compared with the method without modified Zn, the present invention... 2+ In Comparative Example 1, the / Hβ zeolite catalyst increased the fluorobenzene conversion from 62.8% to over 95.1%, and the selectivity for 4-fluoroacetophenone from 75.3% to over 98.0%, significantly suppressing the formation of o-fluoroacetophenone, reducing its content from 18.5% to 0.6%~1.2%; Meanwhile, Example 4 modified Zn 2+ The / Hβ zeolite catalyst, after regeneration, achieved an activity of 95.8%, exhibiting excellent long-term stability and regeneration performance. Compared to the conventional AlCl3 homogeneous catalyst in Comparative Example 2, the modified Zn catalyst of this invention... 2+ The / Hβ zeolite catalyst eliminates the need for water washing and separation, comprehensively surpassing the method of this invention in selectivity, product purity, and purification yield, while avoiding the drawbacks of homogeneous catalysts such as high contamination and product loss. Comparative Example 3's conventional cooling process, due to its inability to simultaneously separate products and its susceptibility to micro-regional overheating, exhibits inferior overall performance compared to the preparation method of this invention.

Claims

1. A method for preparing 4-fluoroacetophenone, characterized in that, Includes the following steps: S1. Hβ zeolite was placed in a zinc nitrate solution and subjected to ion exchange at 60-70℃ for 2-3 hours. The mixture was then filtered, dried, and calcined sequentially to obtain modified Zn. 2+ / Hβ zeolite catalyst; pretreatment of fluorobenzene and acetyl chloride; S2. Mix the pretreated fluorobenzene and acetyl chloride in a certain proportion and continuously pass them into a container filled with modified Zn. 2+ In a fixed-bed catalytic reactor with Hβ zeolite catalyst, an acylation reaction was carried out at 50-60℃ to obtain a crude 4-fluoroacetophenone mixture. S3. The crude 4-fluoroacetophenone mixture is subjected to light-removal treatment and distillation treatment in sequence to obtain the 4-fluoroacetophenone product.

2. The method for preparing 4-fluoroacetophenone according to claim 1, characterized in that, The concentration of the zinc nitrate solution is 0.5~1.0 mol / L, the solid-liquid ratio of the Hβ zeolite to the zinc nitrate solution is 1:10~15, and the calcination temperature is 500~550℃ and the time is 3~4h.

3. The method for preparing 4-fluoroacetophenone according to claim 1, characterized in that, The specific methods for pretreating fluorobenzene and acetyl chloride include: dehydrating fluorobenzene to a moisture content of ≤0.05% by mass, and removing free chlorine from acetyl chloride to a free chlorine content of ≤0.01% by mass.

4. The method for preparing 4-fluoroacetophenone according to claim 1, characterized in that, The purity of the pretreated fluorobenzene is ≥99.5%, and the purity of the pretreated acetyl chloride is ≥99%.

5. The method for preparing 4-fluoroacetophenone according to claim 1, characterized in that, In the acylation reaction, the molar ratio of fluorobenzene to acetyl chloride is 1:1.05; the operating pressure of the fixed-bed catalytic reactor is 0.1 MPa, and the space velocity of the reactants is 0.8~1.2 h⁻¹. -1 .

6. The method for preparing 4-fluoroacetophenone according to claim 1, characterized in that, The acylation reaction is carried out through heat transfer coupled by a reactive distillation column. The reflux ratio of the reactive distillation column is 2~3:1, the top temperature is 51~52℃, the bottom temperature is 140~145℃, and the heat transfer rate is 80~100kJ / h.

7. The method for preparing 4-fluoroacetophenone according to claim 1, characterized in that, The modified Zn 2+ / Hβ zeolite catalyst is regenerated by calcination under a nitrogen atmosphere after 1200~1500h of use; The roasting temperature was 450℃ and the time was 2 hours.

8. The method for preparing 4-fluoroacetophenone according to claim 1, characterized in that, The specific method for obtaining 4-fluoroacetophenone product by sequentially subjecting the crude 4-fluoroacetophenone mixture to light-weight removal and distillation includes: The crude 4-fluoroacetophenone mixture is fed into a light component removal column to remove light component impurities at 80-85℃, and then fed into a distillation column for distillation at 142-145℃.

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