Preparation equipment and preparation process of m-chlorobenzoyl chloride

Abstract

The invention discloses preparation equipment and a preparation process of m-chlorobenzoyl chloride, and the preparation equipment comprises a chlorination reaction unit, a primary rectification unit, a cooling crystallization unit and a secondary rectification unit. Crystallization separation is carried out by utilizing solubility difference of meta-isomers and para-isomers at low temperature, and trace ortho-isomers are further removed through secondary rectification, so that the separation problem caused by approximate boiling points of m-chlorobenzoyl chloride and para-benzoyl chloride is effectively solved, the product purity is remarkably improved, and the production cost is reduced. The method meets high-standard requirements in the fields of medicines, electronic chemicals and the like, is suitable for fine separation of isomers with boiling points close to those of the isomers, and realizes industrial production of high-purity m-chlorobenzoyl chloride.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of pharmaceutical and pesticide intermediate chemical products among chemical raw materials and chemical products, and in particular to a preparation device and a preparation process thereof for m-chlorobenzoyl chloride. Background Art

[0002] Meta-chlorobenzoyl chloride is an important organic intermediate widely used in fields such as medicine, pesticides, dyes, and polymer materials. Currently, the traditional preparation process for meta-chlorobenzoyl chloride primarily uses benzoyl chloride as a raw material and is produced through a chlorine chlorination reaction. This process has the advantages of simple operation and low cost, but it suffers from the problem of difficulty in separation during actual production. During the distillation separation stage, the boiling points of o-benzoyl chloride, p-benzoyl chloride, and the target product, meta-chlorobenzoyl chloride, are extremely close (particularly, the boiling points of p-benzoyl chloride and m-chlorobenzoyl chloride are almost identical), resulting in low separation efficiency. Conventional distillation methods can only produce meta-chlorobenzoyl chloride products with a purity of 96-97%, a purity level that is difficult to meet the stringent requirements for high-purity raw materials in pharmaceutical synthesis and other fine chemical industries. This not only limits the product's scope of application but also increases the cost of subsequent purification treatments. Therefore, developing new separation technologies and improving existing processes to increase the product purity of meta-chlorobenzoyl chloride have become key technical issues that urgently need to be addressed in this field. Summary of the Invention

[0003] In response to the above problems, the present invention discloses a preparation device and a preparation process of m-chlorobenzoyl chloride. A combined separation process is adopted, through the combination of crystallization and distillation, to effectively solve the separation problem caused by the close boiling points of m-chlorobenzoyl chloride and p-benzoyl chloride, thereby significantly improving the product purity.

[0004] The specific technical solutions are as follows:

[0005] A preparation device for m-chlorobenzoyl chloride comprises a chlorination reaction unit, a primary distillation unit, a cooling crystallization unit, and a secondary distillation unit. The outlet of the chlorination reaction unit is connected to the liquid inlet of the primary distillation unit via a pumping pipeline. The top outlet of the primary distillation unit is connected to a first condenser, which is connected to a circulation tank and recovers unreacted benzoyl chloride. The bottom outlet of the primary distillation unit is connected to an intermediate tank, which is connected to the cooling crystallization unit via a pumping pipeline. The outlet of the cooling crystallization unit is connected to a centrifuge for separating crystals from mother liquor. The liquid inlet of the secondary distillation unit is connected to a dissolving tank via a pumping pipeline, which is used to dissolve crystals separated by the centrifuge. The top outlet of the secondary distillation unit is connected to a second condenser, which is connected to a vacuum pump for vacuuming the secondary distillation unit. The outlet of the second condenser is connected to a product tank.

[0006] Among them, the first-level distillation unit is a packed distillation tower, and the second-level distillation unit is a rotating cone distillation tower. The rotating cone distillation tower includes a tower body, a movable cone assembly, a rotating cone assembly, a transmission mechanism, a segmented heating assembly, a driving mechanism and a reboiler. A steam outlet is provided at the top of the tower body, and a liquid inlet pipe connected to the outlet of the dissolving tank is provided on one side of the steam outlet. The bottom of the tower body is connected to a three-way valve through a pipeline, and one end of the three-way valve is connected to the reboiler through a pipeline. The outlet of the reboiler is connected to the bottom of the tower body through a return air pipe; the movable cone assembly includes a rotating drum and a plurality of movable cones arranged longitudinally on the inner wall of the rotating drum. The outer wall of the rotating drum is rotatably arranged on the inner wall of the tower body through a bearing, and a sandwich is formed between the outer wall of the rotating drum and the inner wall of the tower body, the segmented heating component is arranged in the sandwich, and the temperature inside the tower body is controlled from top to bottom by a gradient; the rotating cone assembly includes a rotating shaft and a plurality of rotating cone disks arranged on the rotating shaft and axially spaced from the movable cone disk, the rotating shaft is longitudinally arranged at the center of the tower body, the lower end of the rotating shaft is driven by a driving mechanism outside the tower body to rotate in the forward direction at a high speed, and the upper end of the rotating shaft drives the movable cone assembly to rotate in the reverse direction at a low speed through a transmission mechanism inside the tower body, so that the liquid on the movable cone disk is more evenly distributed.

[0007] Preferably, the transmission mechanism includes a transmission box, a rotating sleeve, and a planetary gear assembly. The transmission box is arranged at the top of the tower body cavity, and the transmission box is fixedly connected to the top of the tower body through a hanger. The lower end of the transmission box is opened and embedded with the rotating sleeve. The side wall of the lower end of the rotating sleeve is circumferentially distributed with several fixing rods. The rotating sleeve is fixedly connected to the inner wall of the rotating drum through several fixing rods, and the middle side wall of the rotating sleeve is rotatably connected to the lower end opening of the transmission box through a bearing. The upper end of the rotating sleeve is provided with a ring part of an annular structure, and the planetary gear assembly is arranged in the ring part; the upper end of the rotating shaft extends upward into the rotating sleeve and is rotatably connected to the inner wall of the rotating sleeve through a bearing. The upper end of the rotating shaft extends into the ring part and is transmission-connected to the rotating sleeve through the planetary gear assembly.

[0008] Preferably, the planetary gear assembly includes a planetary carrier, a ring gear, a sun gear and a plurality of planetary gears, the ring gear is fixedly arranged on the step on the inner wall of the collar portion; the sun gear is arranged at the upper end of the rotating shaft and corresponds to the position of the ring gear; a fixed shaft is provided at the center of the planetary carrier, and the upper end of the fixed shaft is fixedly arranged in the transmission box through a mounting seat to keep the planetary carrier fixed, and a plurality of planetary gears are installed at the lower end of the planetary carrier, and each planetary gear is located between the ring gear and the sun gear, so that when the rotating shaft rotates, the rotating sleeve and the movable cone assembly are driven to rotate through the planetary gear assembly.

[0009] Preferably, the rotating cone disk and the movable cone disk are both conical disks with a lower middle and higher edges, and the bottom of the rotating cone disk is provided with a wing; one end of the outer edge of the movable cone disk is fixedly connected to the inner wall of the rotating drum, and a plurality of support plates are provided on the inner wall of the rotating drum to support the bottom of the movable cone disk on all sides.

[0010] Preferably, the central opening of the movable cone disk is continuously bent to form a material receiving groove with a U-shaped cross-section, a plurality of flow openings are opened at the bottom end of the material receiving groove, and a circle of filler layer is provided in each material receiving groove; the material receiving groove is annular in structure and the inner end of the material receiving groove on each movable cone disk is arranged close to the rotating shaft, and a gap is left between the inner side of the material receiving groove and the rotating shaft.

[0011] Preferably, a convex ring is provided at the upper and lower ends of the outer wall of the rotating drum, and an annular support is provided on the inner wall of the tower body at the position of the convex ring. A thrust bearing is provided on the annular support, and the convex ring is supported by the thrust bearing on the annular support to realize the rotational connection between the rotating drum and the tower body, and the upper and lower ends of the outer wall of the rotating drum are sealed between the inner wall of the tower body through sealing rings.

[0012] Preferably, the segmented heating assembly includes a plurality of electromagnetic coils fixedly mounted on the inner wall of the tower body and distributed in sequence from top to bottom, each electromagnetic coil is respectively connected to an external control system, the electromagnetic coils are spirally arranged around the outer ring of the rotating drum, and an annular partition is provided on the inner wall of the tower body between two adjacent electromagnetic coils, and the interlayer is divided from top to bottom into multiple areas, each area is respectively provided with a temperature sensor connected to the control system, which is used to monitor the temperature of each section of the tower body in real time and feed back to the control system.

[0013] A preparation process for m-chlorobenzoyl chloride specifically comprises the following steps:

[0014] S1, chlorination reaction: adding benzoyl chloride to a reactor, adding 0.5% by mass of ferric chloride catalyst dropwise, and slowly introducing chlorine gas into the reactor to obtain a mixed solution with a content of 50-55% of benzoyl chloride and a content of 45-50% of chlorobenzoyl chloride;

[0015] S2, preliminary distillation: the mixed solution is put into a packed distillation tower for preliminary separation, and the top fraction is unreacted benzoyl chloride, which is condensed and temporarily stored in a circulation tank and reused for the next batch of chlorination reaction; the bottom fraction is a chlorobenzoyl chloride mixture and is pumped into an intermediate tank;

[0016] S3, crystallization separation: using a crystallizer, the bottom fraction is mixed with toluene solvent in a mass ratio of 1:1.5, the temperature is raised until completely dissolved, and then the temperature is stepped down to allow m-chlorobenzoyl chloride to crystallize preferentially, and then the crystals and the mother liquor are separated by centrifuge, wherein the crystals are a crude product with a content of ≥98% m-chlorobenzoyl chloride;

[0017] S4, secondary distillation: the above crystals are placed in a dissolution tank and dissolved in toluene at a mass ratio of 1:1. After preheating, they are pumped into a rotating cone distillation tower for secondary distillation. The final overhead fraction is high-purity m-chlorobenzoyl chloride with a content of ≥99.5%, which is condensed and enters the product tank; the bottom of the tower is a residual liquid containing toluene and high-boiling substances, which is pumped into a solvent recovery tower;

[0018] S5. Product collection: The top fraction is passed through a falling film evaporator to remove residual toluene, and then passed through a molecular sieve adsorption column to remove trace moisture to obtain the finished product of m-chlorobenzoyl chloride.

[0019] Preferably, in S1, chlorine gas is introduced at a rate of 10-15 L / min, and the reaction temperature is maintained at 60-80°C.

[0020] Preferably, in S1, the benzoyl chloride content is tracked by online gas chromatography, and the chlorine feeding is stopped when the benzoyl chloride content drops to 50-55%.

[0021] Preferably, 0.2-0.5% by mass of an additive is further added to S1. The additive may be a Lewis acid ligand or an ionic liquid, which inhibits ortho-substitution through steric hindrance or coordination and increases the proportion of meta-products.

[0022] Preferably, in the step S3, the bottom fraction is mixed with toluene and preheated to 60°C and stirred until completely dissolved. During the step cooling, the first stage is cooled to 40°C at a cooling rate of 1°C / min and kept warm for 1 hour to induce crystal nucleation; the second stage is cooled to 20°C at a cooling rate of 0.5°C / min and kept warm for 2 hours to allow crystal growth; the third stage is cooled to 5°C at a cooling rate of 0.2°C / min.

[0023] / min, keep warm for 3 hours to maximize crystallization.

[0024] The beneficial effects of the present invention are embodied in:

[0025] (1) The present invention adopts a combined separation process, through the synergistic effect of the crystallization-distillation process, utilizing the solubility difference between the meta- and para-isomers at low temperature to perform crystallization separation, and then further removing the trace ortho-isomer through secondary distillation, ultimately increasing the product purity to ≥99.5%, meeting the high standards required in the fields of medicine, electronic chemicals, etc., solving the separation bottleneck of traditional processes, and having the advantages of high purity, low energy consumption, high yield, and low pollution. It is effectively suitable for the fine separation of isomers with similar boiling points, and realizes the industrial production of high-purity m-chlorobenzoyl chloride.

[0026] (2) The present invention adopts a high-efficiency rotating cone distillation tower, which significantly improves the separation efficiency. The movable cone is used instead of the traditional fixed cone, so that a reverse shear force is formed between the counter-rotating movable cone and the high-speed rotating rotating cone, further breaking up the liquid film and increasing the gas-liquid contact area. At the same time, during the rotation of the movable cone, the liquid on its surface can flow spirally toward the center, which not only prolongs the flow path of the liquid in the tower, increases the gas-liquid contact time, and improves the separation effect, but also avoids the local liquid film from being too thick or drying up, promotes component diffusion and mass transfer efficiency, and is effectively applicable to high-difficulty separation scenarios.

[0027] (3) The present invention sets an annular material receiving trough at the center of the movable cone disk and adds a packing layer, which can further increase the gas-liquid contact surface and contact time. The liquid film dispersed by the rotating cone disk is superimposed on the liquid film on the surface of the packing to form a dual mass transfer path, effectively improving the mass transfer efficiency, optimizing the flow field distribution, and thus improving the separation efficiency.

[0028] (4) A segmented heating component is used to heat the inner wall of the drum. By precisely controlling the temperature distribution, the relative volatility difference of components with similar boiling points is amplified, the separation accuracy is improved, the separation efficiency is optimized, and a stable thermodynamic driving force is formed, thereby reducing gas-liquid backmixing and avoiding azeotropic phenomena. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the present invention.

[0030] Figure 2 It is a schematic structural diagram of the rotating cone distillation tower in the present invention.

[0031] Figure 3 It is a schematic diagram of the structure between the movable cone assembly and the rotating cone assembly in the present invention.

[0032] Figure 4 Schematic diagram of liquid flow on the movable cone in the present invention.

[0033] Figure 5 It is a cross-sectional view of the transmission mechanism in the present invention.

[0034] Figure 6 Schematic diagram of the structure of the planetary gear assembly in the present invention.

[0035] Explanation of reference numerals: chlorination reaction unit 1, primary distillation unit 2, first condenser 21, circulation tank 22, intermediate tank 23, cooling crystallization unit 3, centrifuge 4, dissolution tank 41, secondary distillation unit 5, second condenser 51, vacuum pump 52, product tank 53;

[0036] Tower body 6, interlayer 601, annular partition 602, annular support 603, thrust bearing 604, steam outlet 61, liquid inlet pipe 62, three-way valve 63;

[0037] Movable cone assembly 7, rotating drum 71, convex ring 711, sealing ring 712, supporting plate 713, movable cone disc 72, receiving trough 73, packing layer 74;

[0038] Rotating cone assembly 8, rotating shaft 81, rotating cone disk 82, wing plate 83;

[0039] Transmission mechanism 9, transmission box 91, suspension rod 911, rotating sleeve 92, fixed rod 921, collar portion 922, planet carrier 93, fixed shaft 931, ring gear 94, sun gear 95, planet gears 96, mounting seat 97;

[0040] Segmented heating assembly 10 , driving mechanism 11 , reboiler 12 , and return air pipe 121 . DETAILED DESCRIPTION

[0041] To make the technical solution of the present invention more clear and specific, the present invention is further described below with reference to the accompanying drawings. Any equivalent replacement of the technical features of the technical solution of the present invention and any solution derived from conventional reasoning shall fall within the scope of protection of the present invention. The fixed connection and fixed setting mentioned in the present invention are all common connection methods in the mechanical field, including welding, bolt and nut connection, and screw connection.

[0042] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0043] Please see the attached Figure 1The present embodiment provides a preparation device for m-chlorobenzoyl chloride, comprising a chlorination reaction unit 1, a primary distillation unit 2, a cooling crystallization unit 3, and a secondary distillation unit 5. The outlet end of the chlorination reaction unit 1 is connected to the liquid inlet end of the primary distillation unit 2 through a pumping pipeline. The top outlet end of the primary distillation unit 2 is connected to a first condenser 21, and the outlet end of the first condenser 21 is connected to a circulation tank 22, and unreacted benzoyl chloride is recovered. The bottom outlet end of the primary distillation unit 2 is connected to an intermediate tank 23, and the intermediate tank 23 is connected to the intermediate tank 23 through a pumping pipeline. The pumping pipeline is connected to the cooling crystallization unit 3, and the outlet end of the cooling crystallization unit 3 is connected to the centrifuge 4, which is used to separate the crystals from the mother liquor. The liquid inlet end of the secondary distillation unit 5 is connected to the dissolution tank 41 through the pumping pipeline, and the dissolution tank 41 is used to dissolve the crystals separated by the centrifuge 4. The top outlet end of the secondary distillation unit 5 is connected to the second condenser 51, and the second condenser 51 is connected to a vacuum pump 52, which vacuums the secondary distillation unit 5. The outlet end of the second condenser 51 is connected to the product tank 53.

[0044] In this embodiment, the first-stage distillation unit is a packed distillation tower, and the second-stage distillation unit 5 is a rotating cone distillation tower. Figure 2-6 As shown, the rotating cone distillation tower includes a tower body 6, a movable cone assembly 7, a rotating cone assembly 8, a transmission mechanism 9, a segmented heating assembly 10, a driving mechanism 11 and a reboiler 12. A steam outlet 61 is provided at the top of the tower body 6, and the steam outlet 61 is connected to the second condenser 51 through a pipeline. At the same time, a vacuum pump 52 on the second condenser 51 continuously evacuates the interior of the tower body 6, and also increases the flow rate of the gas from bottom to top; a liquid inlet pipe 62 connected to the outlet of the dissolving tank 41 is provided on one side of the steam outlet 61, and a three-way valve 63 is connected to the bottom of the tower body 6 through a pipeline. One end of 63 is connected to the reboiler 12 through a pipeline, and the outlet end of the reboiler 12 is connected to the bottom end of the tower body 6 through the return air pipe 121; the movable cone assembly 7 includes a rotating drum 71 and a plurality of movable cone disks 72 arranged longitudinally on the inner wall of the rotating drum 71. The outer wall of the rotating drum 71 is rotatably set on the inner wall of the tower body 6 through a bearing, and an interlayer 601 is formed between the outer wall of the rotating drum 71 and the inner wall of the tower body 6. The segmented heating assembly 10 is set in the interlayer 601 and performs gradient temperature control on the interior of the tower body 6 from top to bottom. The heated inner wall of the tower directly transfers heat to the liquid film, accelerating the evaporation of low-boiling-point components in the liquid and shortening the vaporization time.

[0045] The rotating cone assembly 8 includes a rotating shaft 81 and a plurality of rotating cone disks 82 arranged on the rotating shaft 81 and axially spaced from the movable cone disk 72. The rotating shaft 81 is longitudinally arranged at the center of the tower body 6. The lower end of the rotating shaft 81 is driven by a driving mechanism 11 outside the tower body 6 to rotate in the forward direction at high speed. The upper end of the rotating shaft 81 drives the movable cone assembly 7 to rotate in the reverse direction at low speed through a transmission mechanism 9 inside the tower body 6, so that the liquid on the movable cone disk 72 is more evenly distributed, avoiding the local liquid film from being too thick or drying up, and at the same time extending the flow path of the liquid in the tower, increasing the gas-liquid contact time, and improving the separation effect.

[0046] In this embodiment, the transmission mechanism 9 includes a transmission box 91, a rotating sleeve 92, and a planetary gear assembly. The transmission box 91 is arranged at the top of the inner cavity of the tower body 6, and the transmission box 91 is fixedly connected to the top of the tower body 6 through a suspension rod 911. The lower end of the transmission box 91 is opened and embedded with a rotating sleeve 92. The side wall of the lower end of the rotating sleeve 92 is circumferentially distributed with several fixing rods 921. The rotating sleeve is fixedly connected to the inner wall of the rotating drum 71 through several fixing rods 921, and the middle side wall of the rotating sleeve 92 is rotatably connected to the lower end opening of the transmission box 91 through a bearing. The upper end of the rotating sleeve 92 is provided with a ring portion 922 of an annular structure, and a planetary gear assembly is arranged in the ring portion 922; the upper end of the rotating shaft 81 extends upward into the rotating sleeve 92 and is rotatably connected to the inner wall of the rotating sleeve 92 through a bearing. The upper end of the rotating shaft 81 extends into the ring portion 922 and is transmission-connected to the rotating sleeve 92 through the planetary gear assembly.

[0047] The planetary gear assembly includes a planet carrier 93, a ring gear 94, a sun gear 95, and multiple planetary gears 96. The ring gear 94 is fixedly mounted on a step on the inner wall of the collar portion 922. The sun gear 95 is mounted on the upper end of the rotating shaft 81 and corresponds to the position of the ring gear 94. A fixed shaft 931 is provided at the center of the planet carrier 93. The upper end of the fixed shaft 931 is fixedly mounted in the transmission case 91 via a mounting seat 97, which keeps the planet carrier 93 stationary. Multiple planetary gears 96 are mounted on the lower end of the planet carrier 93. Each planetary gear 96 is located between the ring gear 94 and the sun gear 95. When the rotating shaft 81 rotates, the planetary gear assembly drives the rotating sleeve 92 and the movable cone assembly 7 to rotate. By utilizing the transmission of the planetary gears, the rotating sleeve 92 with the ring gear rotates at a low speed, preventing the movable cone 72 from rotating too fast and affecting the normal downward flow of liquid.

[0048] In this embodiment, both the rotating cone 82 and the movable cone 72 are conical disks with a lower center and higher edges. The bottom of the rotating cone 82 is equipped with fins 83, which increase the gas flow rate during rotation. One end of the outer edge of the movable cone 72 is fixedly connected to the inner wall of the rotating drum 71. Several support plates 713 are provided on the inner wall of the rotating drum 71 to support the bottom of the movable cone 72.

[0049] In another embodiment, the central opening of the movable cone 72 is continuously curved to form a U-shaped cross-section receiving trough 73. Several flow openings are provided at the bottom of the trough 73, and each trough 73 is provided with a ring of packing 74. The packing 74 is preferably a structured packing with low pressure drop. The trough 73 is annular in shape, and the inner end of each trough 73 on the movable cone 72 is positioned close to the rotating shaft 81. A gap is left between the inner side of the trough 73 and the rotating shaft 81 to prevent friction caused by contact and increased power consumption.

[0050] In this embodiment, a convex ring 711 is provided at the upper and lower ends of the outer wall of the rotating drum 71, and an annular support 603 is provided on the inner wall of the tower body 6 at the position of the convex ring 711. A thrust bearing 604 is provided on the annular support 603. The convex ring 711 is supported by the thrust bearing 604 on the annular support 603, and the rotating connection between the rotating drum 71 and the tower body 6 is realized. The upper and lower ends of the outer wall of the rotating drum 71 are sealed with the inner wall of the tower body 6 by sealing rings 712 respectively.

[0051] In this embodiment, the segmented heating assembly 10 comprises three electromagnetic coils fixedly mounted on the inner wall of the tower body 6 and arranged sequentially from top to bottom. Each electromagnetic coil segment is connected to an external control system. The electromagnetic coils are spirally arranged around the outer ring of the rotating drum 71. An annular partition 602 is provided on the inner wall of the tower body 6 between adjacent electromagnetic coil segments, dividing the interlayer 601 into three zones from top to bottom. Each zone is equipped with a temperature sensor connected to the control system for real-time temperature monitoring of each section of the tower body 6 and providing feedback to the control system. The upper section maintains a relatively low temperature, set close to the dew point of the light component, i.e., m-chlorobenzoyl chloride, to promote condensation and reflux, reduce the risk of material decomposition, and is suitable for heat-sensitive components such as m-chlorobenzoyl chloride. The middle section maintains an optimal separation temperature (55-65°C) to maximize the relative volatility difference. The lower section is slightly above the bubble point of the heavy component, i.e., the para-isomer, to ensure full evaporation of the heavy component.

[0052] This embodiment also provides a preparation process of m-chlorobenzoyl chloride, which specifically comprises the following steps:

[0053] S1, chlorination reaction: benzoyl chloride is added to the reactor, 0.5% mass ratio of ferric chloride catalyst is added dropwise, chlorine is slowly introduced into the reactor, chlorine is introduced at a rate of 10-15L / min, the reaction temperature is maintained at 60-80°C, the benzoyl chloride content is tracked by online gas chromatography, and when its content drops to 50-55%, the chlorine is stopped, then the temperature is raised to 80°C and stirred for 1 hour, residual chlorine is decomposed, the reaction solution is allowed to stand and stratify, and the ferric chloride catalyst is discharged through the bottom valve for recycling and regeneration. A mixed solution of benzoyl chloride with a content of 50-55% and chlorobenzoyl chloride with a content of 45-50% is finally obtained. Under the catalysis of ferric chloride, chlorine and benzoyl chloride undergo electrophilic substitution reaction to generate an ortho-, meta- and para-chlorobenzoyl chloride mixture, which consists of: meta-45-50%, ortho-20-25%, and para-25-30%;

[0054] S2, preliminary distillation: the mixed solution is put into a packed distillation tower for preliminary separation, wherein the tower top temperature is 195-198 ° C, which is used to control the distillation of benzoyl chloride, and the tower bottom temperature is 220-230 ° C, which is used to prevent thermal decomposition. The final top fraction is unreacted benzoyl chloride, which is temporarily stored in a circulation tank 22 after condensation and reused in the next batch of chlorination reaction; the bottom fraction is a chlorobenzoyl chloride mixture and is pumped into the intermediate tank 23;

[0055] S3, crystallization separation: using a crystallizer, the bottom fraction is mixed with toluene solvent in a mass ratio of 1:1.5. Toluene and chlorobenzoyl chloride have good compatibility. The mixture is heated to 60° C. and stirred until completely dissolved. The temperature is then stepped down to allow m-chlorobenzoyl chloride to crystallize first. The crystals and the mother liquor are then separated by centrifuge 4 or a centrifuge. The crystals are crude m-chlorobenzoyl chloride with a content of ≥98% and a yield of 70-75%. The mother liquor contains the para isomer (about 60%) and the residual meta isomer, which can be concentrated and then subjected to secondary crystallization or isomerization treatment.

[0056] S4, secondary distillation: The crystals are placed in a dissolving tank 41 and dissolved in toluene at a mass ratio of 1:1. After preheating, they are pumped into a rotating cone distillation tower for secondary distillation. The top fraction is high-purity m-chlorobenzoyl chloride with a content of ≥99.5%, which is condensed and enters a product tank 53. The bottom fraction contains toluene and high-boiling substances and is pumped into a solvent recovery tower.

[0057] S5. Product collection: The top fraction is passed through a falling film evaporator to remove residual toluene (temperature 80° C., vacuum degree 10 kPa), and then passed through a molecular sieve adsorption column to remove trace moisture to obtain the finished product of m-chlorobenzoyl chloride.

[0058] 0.2-0.5% by mass of an additive is also added to S1. The additive may be a Lewis acid ligand or an ionic liquid, which inhibits ortho-position substitution through steric hindrance or coordination and increases the proportion of meta-position products.

[0059] In S3, the bottom fraction was mixed with toluene and preheated to 60°C and stirred until completely dissolved. During the step cooling, the first stage was cooled to 40°C at a cooling rate of 1°C / min and kept warm for 1 hour to induce nucleation; the second stage was cooled to 20°C at a cooling rate of 0.5°C / min and kept warm for 2 hours to allow crystal growth; the third stage was cooled to 5°C at a cooling rate of 0.2°C / min and kept warm for 3 hours to maximize crystallization.

[0060] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A preparation device for m-chlorobenzoyl chloride, characterized in that, The invention comprises a chlorination reaction unit (1), a primary distillation unit (2), a cooling crystallization unit (3), and a secondary distillation unit (5); the outlet end of the chlorination reaction unit (1) is connected to the liquid inlet end of the primary distillation unit (2) through a pumping pipeline; the top outlet end of the primary distillation unit (2) is connected to a first condenser (21); the outlet end of the first condenser (21) is connected to a circulation tank (22) for recovering unreacted benzoyl chloride; the bottom outlet end of the primary distillation unit (2) is connected to an intermediate tank (23); the intermediate tank (23) is connected to the cooling crystallization unit through a pumping pipeline. (3), the outlet end of the cooling crystallization unit (3) is connected to a centrifuge (4), the centrifuge (4) is used to separate crystals from mother liquor, the liquid inlet end of the secondary distillation unit (5) is connected to a dissolving tank (41) through a pumping pipeline, the dissolving tank (41) is used to dissolve the crystals separated by the centrifuge (4), the top outlet end of the secondary distillation unit (5) is connected to a second condenser (51), the second condenser (51) is connected to a vacuum pump (52), the vacuum pump (52) performs vacuum treatment on the secondary distillation unit (5), and the outlet end of the second condenser (51) is connected to a product tank (53); The first-stage distillation unit is a packed distillation tower, and the second-stage distillation unit (5) is a rotating cone distillation tower. The rotating cone distillation tower comprises a tower body (6), a movable cone assembly (7), a rotating cone assembly (8), a transmission mechanism (9), a segmented heating assembly (10), a driving mechanism (11) and a reboiler (12). The top of the tower body (6) is provided with a steam outlet (61), and one side of the steam outlet (61) is provided with a liquid inlet pipe (62) connected to the outlet of the dissolving tank (41). The bottom of the tower body (6) is connected to a three-way valve (63) through a pipeline. One end of the three-way valve (63) is connected to the reboiler (12) through a pipeline. The outlet of the reboiler (12) is connected to the bottom of the tower body (6) through a return gas pipe (121). The movable cone assembly (7) comprises a rotating drum (71) and a plurality of movable cone disks ( 72), the outer wall of the rotating drum (71) is rotatably arranged on the inner wall of the tower body (6) through a bearing, and an interlayer (601) is formed between the outer wall of the rotating drum (71) and the inner wall of the tower body (6), the segmented heating component (10) is arranged in the interlayer (601) and performs gradient temperature control on the inside of the tower body (6) from top to bottom; the rotating cone assembly (8) includes a rotating shaft (81) and a plurality of rotating cone disks (82) arranged on the rotating shaft (81) and axially spaced from the movable cone disk (72), the rotating shaft (81) is longitudinally arranged at the center of the tower body (6), the lower end of the rotating shaft (81) is driven by a driving mechanism (11) outside the tower body (6) to rotate in a forward high-speed direction, and the upper end of the rotating shaft (81) drives the movable cone assembly (7) to rotate in a reverse low-speed direction through a transmission mechanism (9) inside the tower body (6), so that the liquid on the movable cone disk (72) is more evenly distributed.

2. A preparation equipment for m-chlorobenzoyl chloride according to claim 1, characterized in that, The transmission mechanism (9) comprises a transmission box (91), a rotating sleeve (92), and a planetary gear assembly. The transmission box (91) is arranged at the top of the inner cavity of the tower body (6), and the transmission box (91) is fixedly connected to the top of the tower body (6) through a suspension rod (911). The lower end of the transmission box (91) is opened and embedded with the rotating sleeve (92). The side wall of the lower end of the rotating sleeve (92) is provided with a plurality of fixed rods (921) distributed along the circumferential direction. The rotating sleeve is connected to the inner wall of the rotating drum (71) through the plurality of fixed rods (921). The rotating sleeve (92) is fixedly connected, and the side wall of the middle part of the rotating sleeve (92) is rotatably connected to the lower end opening of the transmission box (91) through a bearing. The upper end of the rotating sleeve (92) is provided with a ring portion (922) of an annular structure, and the planetary gear assembly is arranged in the ring portion (922); the upper end of the rotating shaft (81) extends upward into the rotating sleeve (92) and is rotatably connected to the inner wall of the rotating sleeve (92) through a bearing. The upper end of the rotating shaft (81) extends into the ring portion (922) and is transmission-connected to the rotating sleeve (92) through the planetary gear assembly.

3. A preparation equipment for m-chlorobenzoyl chloride according to claim 2, characterized in that, The planetary gear assembly comprises a planet carrier (93), a ring gear (94), a sun gear (95) and a plurality of planetary gears (96), wherein the ring gear (94) is fixedly arranged on a step on the inner wall of the collar portion (922); the sun gear (95) is arranged at the upper end of the rotating shaft (81) and corresponds to the position of the ring gear (94); a fixed shaft (931) is provided at the center of the planet carrier (93), and the upper end of the fixed shaft (931) is fixedly arranged in the transmission box (91) through a mounting seat (97) so that the planet carrier (93) remains fixed; a plurality of planetary gears (96) are installed at the lower end of the planet carrier (93), and each planetary gear (96) is located between the ring gear (94) and the sun gear (95), so that when the rotating shaft (81) rotates, the rotating sleeve (92) and the movable cone assembly (7) are driven to rotate through the planetary gear assembly.

4. A preparation equipment for m-chlorobenzoyl chloride according to claim 1, characterized in that, The rotating cone disk (82) and the movable cone disk (72) are both conical disks with a lower middle and a higher edge. The bottom of the rotating cone disk (82) is provided with a wing (83). One end of the outer edge of the movable cone disk (72) is fixedly connected to the inner wall of the rotating drum (71), and a plurality of support plates (713) are provided on the inner wall of the rotating drum (71) to support the bottom of the movable cone disk (72) on all sides.

5. A preparation equipment for m-chlorobenzoyl chloride according to claim 4, characterized in that, The central opening of the movable cone disk (72) is continuously bent to form a receiving groove (73) with a U-shaped cross-section. A plurality of flow openings are provided at the bottom end of the receiving groove (73), and a ring of filler layer (74) is provided in each receiving groove (73). The receiving groove (73) is an annular structure, and one end of the inner side of the receiving groove (73) on each movable cone disk (72) is arranged close to the rotating shaft (81), and a gap is left between the inner side of the receiving groove (73) and the rotating shaft (81).

6. A preparation equipment for m-chlorobenzoyl chloride according to claim 1, characterized in that, A convex ring (711) is provided at the upper and lower ends of the outer wall of the rotating drum (71), and an annular support (603) is provided on the inner wall of the tower body (6) at the position of the convex ring (711). A thrust bearing (604) is provided on the annular support (603). The convex ring (711) is supported by the annular support (603) through the thrust bearing (604), and the rotating connection between the rotating drum (71) and the tower body (6) is realized; the upper and lower ends of the outer wall of the rotating drum (71) are sealed with the inner wall of the tower body (6) through sealing rings (712).

7. A preparation equipment for m-chlorobenzoyl chloride according to claim 6, characterized in that, The segmented heating assembly (10) comprises a plurality of electromagnetic coils fixedly mounted on the inner wall of the tower body (6) and sequentially distributed from top to bottom, each electromagnetic coil being connected to an external control system. The electromagnetic coils are spirally arranged around the outer ring of the rotating drum (71), and an annular partition (602) is provided on the inner wall of the tower body (6) between two adjacent electromagnetic coils to separate the interlayer (601) from top to bottom into a plurality of areas. Each area is provided with a temperature sensor connected to the control system for real-time monitoring of the temperature of each section of the tower body (6) and feeding back to the control system.

8. A process for preparing a m-chlorobenzoyl chloride preparation device according to any one of claims 1 to 7, characterized in that: The specific steps include: S1, chlorination reaction: adding benzoyl chloride to a reactor, adding 0.5% by mass of ferric chloride catalyst dropwise, and slowly introducing chlorine gas into the reactor to obtain a mixed solution with a content of 50-55% of benzoyl chloride and a content of 45-50% of chlorobenzoyl chloride; S2, preliminary distillation: the mixed solution is put into a packed distillation tower for preliminary separation, and the top fraction is unreacted benzoyl chloride, which is temporarily stored in a circulation tank (22) after condensation and reused for the next batch of chlorination reaction; the bottom fraction is a chlorobenzoyl chloride mixture and is pumped into an intermediate tank (23); S3, crystallization separation: using a crystallizer, the bottom fraction is mixed with toluene solvent in a mass ratio of 1:1.5, the temperature is raised until it is completely dissolved, and then the temperature is lowered in steps to allow m-chlorobenzoyl chloride to crystallize out first, and then the crystals and the mother liquor are separated by a centrifuge (4), wherein the crystals are a crude product of m-chlorobenzoyl chloride with a content of ≥98%; S4, secondary distillation: the above crystals are put into a dissolving tank (41), dissolved in toluene at a mass ratio of 1:1, preheated and pumped into a rotating cone distillation tower for secondary distillation, and the final top fraction is high-purity m-chlorobenzoyl chloride with a content of ≥99.5%, which is condensed and enters the product tank (53); the bottom of the tower is a residual liquid containing toluene and high-boiling substances and is pumped into a solvent recovery tower; S5. Product collection: The top fraction is passed through a falling film evaporator to remove residual toluene, and then passed through a molecular sieve adsorption column to remove trace moisture to obtain the finished product of m-chlorobenzoyl chloride.

9. A process for preparing a m-chlorobenzoyl chloride preparation device as claimed in claim 8, characterized in that: 0.2-0.5% by mass of an additive is further added to the S1. The additive may be a Lewis acid ligand or an ionic liquid, which inhibits ortho-substitution through steric hindrance or coordination and increases the proportion of meta-products.

10. The process for preparing a m-chlorobenzoyl chloride preparation device according to claim 8, wherein: In the S3, the bottom fraction is mixed with toluene and preheated to 60°C and stirred until completely dissolved. During the step cooling, the first stage is cooled to 40°C at a cooling rate of 1°C / min and kept warm for 1 hour to induce crystal nucleation; the second stage is cooled to 20°C at a cooling rate of 0.5°C / min and kept warm for 2 hours to allow crystal growth; the third stage is cooled to 5°C at a cooling rate of 0.2°C / min and kept warm for 3 hours to maximize crystallization.

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