A reaction system and method for the precipitation polymerization of alpha olefins with maleic anhydride

Abstract

The application belongs to the field of polymerization reaction, and discloses a reaction system and method for the precipitation polymerization of alpha olefin and maleic anhydride. The system comprises a reaction circulation subsystem and an external circulation heat removal subsystem; the reaction circulation subsystem comprises a reaction kettle, a reactor, a reaction circulation pump and a mixing connecting device; the reaction kettle comprises a kettle body, a jacket, a stirring device and a first non-condensed gas outlet; the reactor comprises a reaction liquid cavity, an external circulation liquid cavity and a second non-condensed gas outlet, the external circulation liquid cavity is annularly arranged outside the reaction liquid cavity and is not communicated with the reaction liquid cavity; the second non-condensed gas outlet is arranged at the top of the reaction liquid cavity; the external circulation heat removal subsystem comprises an external circulation buffer tank, an external circulation pump, an external circulation heater and an external circulation cooler. The application separates the heating and heat removal functions of the reaction kettle by using a sectional reaction system, so as to meet the heating and heat removal requirements of the precipitation polymerization of alpha olefin and maleic anhydride in different reaction stages of different solvent systems.

Description

Technical Field

[0001] This invention belongs to the field of polymerization reactions, and more specifically, relates to a reaction system and method for the precipitation polymerization of α-olefins with maleic anhydride. Background Technology

[0002] After α-olefins and maleic anhydride are dissolved in a solvent, they undergo polymerization under the action of an initiator to obtain an emulsion-like polymer suspension. Based on the reasonable interaction between the polymer and the solvent, no external surfactants or stabilizers are needed, and the resulting polymer can be stably suspended in the solvent. To obtain a stable suspension, the liquid needs to be kept still after the reaction begins, but this makes it difficult to deheat the reaction and maintain the temperature.

[0003] CN110624487A employs a method of cooling the reactor system by circulating the reaction liquid to an external cooler and introducing low-temperature water into the reactor jacket and inner coils. Since this precipitation polymerization reaction cannot involve flow, this method disrupts the reaction environment through pumping, failing to achieve a satisfactory suspension. Furthermore, due to the presence of a stirrer and high reactant concentration in the reactor, the heat exchange area of ​​the inner coils and jacket cannot meet the heat removal requirements, making temperature control impossible. Using a low-temperature heat exchange medium to increase the heat exchange temperature difference to meet heat removal requirements results in excessively low surface temperatures on the coils and jacket, causing localized reaction cessation, uneven product distribution, and low conversion rates. Moreover, the reaction residue adheres to the reactor walls, making cleaning the coils difficult. Prolonged accumulation leads to scale buildup on the coils, significantly reducing heat exchange capacity, resulting in delayed heat removal, overheating, and product deactivation. These three factors compromise the reaction safety of this approach, making product quality unreliable.

[0004] CN111085154A employs a baffle design, which controls the flow rate of reactants to allow the reaction liquid to pass through the reactor at a low flow rate, while external cooling medium removes heat. The disadvantages of this method are that the flow rate of the reaction liquid is extremely low, and it takes a long time for different materials to mix evenly before the reaction can proceed. To meet the required reaction residence time, a large reactor volume is needed. In addition, the baffle is prone to wall adhesion, making it difficult to clean. Furthermore, there is a problem of excessively high local flow rates at the baffle, leading to uneven reaction precipitation.

[0005] Therefore, there is an urgent need to propose a new reaction system and method for the precipitation polymerization of α-olefins and maleic anhydride. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a reaction system and method for the precipitation polymerization of α-olefins with maleic anhydride. This invention utilizes a segmented reaction system, separating the heating and cooling functions of the reaction vessel to meet the heating and cooling requirements at different stages of the precipitation polymerization reaction of α-olefins with maleic anhydride in different solvent systems.

[0007] To achieve the above objectives, the first aspect of the present invention provides a reaction system for the precipitation polymerization of α-olefins with maleic anhydride, the system comprising a reaction cycle subsystem and an external circulation cooling subsystem;

[0008] The reaction cycle subsystem includes a reaction vessel, a reactor, a reaction cycle pump, and a mixing connection device; the reaction vessel includes a vessel body, a jacket, a stirring device, and a first non-condensable gas outlet; the reactor includes a reaction liquid chamber, an external circulation liquid chamber, and a second non-condensable gas outlet, the external circulation liquid chamber being arranged around the outside of the reaction liquid chamber and not communicating with the reaction liquid chamber; the second non-condensable gas outlet is located at the top of the reaction liquid chamber;

[0009] The outlet of the vessel, the mixing connection device, the reaction liquid chamber, and the reaction circulation pump are connected in sequence; the reaction circulation pump is connected to the inlet of the mixing connection device, the downstream system, and the inlet of the vessel, respectively.

[0010] The external circulation heat removal subsystem includes an external circulation buffer tank, an external circulation pump, an external circulation heater, and an external circulation cooler; the cooling medium outlet of the external circulation liquid cavity, the external circulation buffer tank, the external circulation pump, the external circulation heater, the external circulation cooler, and the cooling medium inlet of the external circulation liquid cavity are connected in sequence;

[0011] The heating medium outlet of the jacket is connected to an external drain pipe, and the heating medium inlet of the jacket is connected to an external heating medium feed pipe.

[0012] According to the present invention, preferably, the reaction cycle subsystem further includes a first temperature control device, a second temperature control device, and a pressure control device.

[0013] According to the present invention, preferably, the first temperature control device is used to measure the temperature of the vessel body and control the flow rate of the heating medium entering the jacket according to the temperature.

[0014] According to the present invention, preferably, the second temperature control device is used to measure the temperature of the reaction liquid chamber and select or control the external circulation heater and the external circulation cooler according to the temperature.

[0015] According to the present invention, preferably, the connecting pipeline of the first non-condensable gas outlet merges with the connecting pipeline of the second non-condensable gas outlet, and the pressure control device is disposed on the merged pipeline for measuring the pressure of the system and controlling the discharge of non-condensable gas according to the pressure.

[0016] According to the present invention, preferably, the stirring device includes one or more stirring blades, the multiple stirring blades being arranged axially.

[0017] According to the present invention, preferably, the jacket includes one or more cavities, which may be interconnected or not interconnected.

[0018] According to the present invention, preferably, the external circulating fluid cavity includes one or more cavities, which are interconnected or not interconnected.

[0019] According to the present invention, preferably, the reaction liquid chamber includes one or more chambers, and the multiple chambers are interconnected.

[0020] According to the present invention, preferably, there are 1-2 external circulation coolers.

[0021] A second aspect of the present invention provides a method for the precipitation polymerization of α-olefins with maleic anhydride, the method employing the aforementioned system and comprising the following steps:

[0022] S1: Add solvent, α-olefin, maleic anhydride and crosslinking agent to the reactor body, stir, heat to the first preset temperature using a heating medium, add initiator to the reactor body, stir evenly, and send the material in the reactor body into the reaction liquid chamber through a mixing and connecting device;

[0023] S2: In the reaction liquid chamber, the mixture is cooled to a second preset temperature using a cooling medium, and the pressure of the system is maintained constant by the pressure control device until the reaction is completed, thus obtaining a reaction liquid.

[0024] S3: Reduce the system pressure through the pressure control device, send the reaction liquid back to the reactor body through the reaction circulation pump, stir, and heat to a third preset temperature using a heating medium to remove unreacted olefins, and then send the final reaction liquid back into the reaction liquid chamber.

[0025] S4: In the reaction liquid chamber, the final reaction liquid is cooled to a fourth preset temperature by using a cooling medium and circulating between the outlet and inlet of the reaction liquid chamber by the reaction circulation pump, and then sent to the downstream system.

[0026] According to the present invention, preferably, in step S1:

[0027] The solvent is an alcohol, ester, ketone, alkane or ether with a boiling point greater than 60°C at one standard atmosphere, or at least one of an alcohol, ester, ketone, alkane and ether with a bubble point or azeotropic point greater than 60°C.

[0028] The crosslinking agent is divinylbenzene and / or styrene;

[0029] The α-olefin is a C4-C9 α-olefin, or a hydrocarbon mixture in which the mass content of C4-C9 α-olefin is greater than 20% based on the total weight of the hydrocarbon mixture;

[0030] The initiator is azobisisobutyronitrile and / or benzoyl peroxide;

[0031] The first preset temperature is no more than 130°C.

[0032] According to the present invention, preferably, in step S2:

[0033] The reaction time is 2-12 hours;

[0034] The second preset temperature is no more than 130℃;

[0035] Maintain the system pressure at 0.5-2.0 MPaG;

[0036] There is no forced flow of the reaction solution during the reaction.

[0037] According to the present invention, preferably, in step S3:

[0038] Reduce the system pressure to 0.05-0.10 MPaG;

[0039] The third preset temperature is 100-200℃.

[0040] According to the present invention, preferably, in step S4:

[0041] The fourth preset temperature is 20-40℃;

[0042] The circulation time is 1-2 hours.

[0043] According to the present invention, preferably, there are two external circulation coolers, including a first external circulation cooler and a second external circulation cooler;

[0044] The temperature of the heating medium in the external circulation heater is 80-250℃;

[0045] The temperature of the cooling medium in the first external circulation cooler is 30-70℃;

[0046] The temperature of the cooling medium in the second external circulation cooler is -30 to 20°C;

[0047] The temperature of the heating medium in the external heating medium feed pipe is 60-280℃.

[0048] The beneficial effects of the technical solution of the present invention are as follows:

[0049] 1) This invention separates the heating and cooling functions of the reaction vessel through a segmented reaction system. The upper stirred reaction vessel is used for initial mixing, heating, and removal of excess monomers after the reaction is completed. The lower reactor is used for cooling and heat preservation during static liquid reaction, as well as cooling after the reaction is completed. This achieves stable temperature control at different stages of the reaction system and ensures the quality of the reaction product.

[0050] 2) The system of the present invention has strong applicability and is applicable to the reaction of olefin self-stabilizing precipitation polymerization to produce copolymer microspheres in a variety of solvent systems.

[0051] 3) This invention simplifies the internal structure of the reactor and solves the problem of reduced reaction heat removal efficiency caused by the adhesion of the reaction system to the reactor wall.

[0052] 4) The present invention simplifies the reactor jacket and external circulation heat removal system, avoiding operational safety and stress problems caused by switching jackets of different types of utilities during the same reaction.

[0053] 5) This invention reduces the need for a downstream cooling system after material discharge by using reactor circulation cooling, thereby reducing equipment investment and shortening the process flow.

[0054] 6) The reaction circulation system of the present invention can realize the cyclic cleaning of each piece of equipment in the reaction system, which is convenient to operate and reduces the number of offline maintenance.

[0055] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0056] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0057] Figure 1 A schematic diagram of a reaction system for the precipitation polymerization of α-olefins and maleic anhydride provided by an embodiment of the present invention is shown.

[0058] The annotations in the attached figures are explained as follows:

[0059] 1-Reactor body; 2-Reaction liquid chamber; 3-Reaction circulation pump; 4-Mixing connection device; 5-Jacket; 6-External circulation liquid chamber; 7-External circulation pump; 8-External circulation heater; 9-First external circulation cooler; 10-Second external circulation cooler; 11-External circulation buffer tank; 12-Stirring device; 13-First temperature control device; 14-Second temperature control device; 15-Inlet of reactor body; 16-Outlet of reactor body; 17-Reaction liquid inlet pipeline into reaction liquid chamber; 18-Reaction liquid inlet pipeline into reactor body; 19-Final reaction liquid inlet pipeline into downstream system; 20-Cooling medium inlet pipeline into external circulation liquid chamber; 22-Heating medium in external circulation heater; 23-Cooling medium in first external circulation cooler; 24-Cooling medium in second external circulation cooler; 25-External heating medium feed pipe; 26-First non-condensable gas outlet; 27-External drain pipe; 28-Pressure control device; 29-Second non-condensable gas outlet. Detailed Implementation

[0060] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0061] Example

[0062] This embodiment provides a reaction system for the precipitation polymerization of α-olefins and maleic anhydride, such as... Figure 1 As shown, the system includes a reaction cycle subsystem and an external circulation heat removal subsystem;

[0063] The reaction circulation subsystem includes a reaction vessel, a reactor, a reaction circulation pump 3, and a mixing connection device 4; the reaction vessel includes a vessel body 1, a jacket 5, a stirring device 12, and a first non-condensable gas outlet 26; the reactor includes a reaction liquid chamber 2, an external circulation liquid chamber 6, and a second non-condensable gas outlet 29, the external circulation liquid chamber 6 being arranged around the outside of the reaction liquid chamber 2 and not communicating with the reaction liquid chamber 2; the second non-condensable gas outlet 29 is located at the top of the reaction liquid chamber 2;

[0064] The outlet 16 of the vessel body, the mixing connection device 4, the reaction liquid chamber 2 and the reaction circulation pump 3 are connected in sequence.

[0065] The stirring device 12 includes two layers of stirring blades arranged axially; the jacket 5 includes a cavity; the external circulating liquid cavity 6 includes a cavity; and the reaction liquid cavity 2 includes a cavity.

[0066] The reaction cycle subsystem also includes a first temperature control device 13, a second temperature control device 14, and a pressure control device 28;

[0067] The first temperature control device 13 is used to measure the temperature of the vessel body 1 and control the flow rate of the heating medium entering the jacket 5 according to the temperature;

[0068] The second temperature control device 14 is used to measure the temperature of the reaction liquid chamber 2 and select or control the external circulation heater 8 and the external circulation cooler according to the temperature.

[0069] The connecting pipeline of the first non-condensable gas outlet 26 merges with the connecting pipeline of the second non-condensable gas outlet 29. The pressure control device 28 is installed on the merged pipeline to measure the pressure of the system and control the discharge of non-condensable gas according to the pressure.

[0070] The external circulation heat removal subsystem includes an external circulation buffer tank 11, an external circulation pump 7, an external circulation heater 8, and two external circulation coolers; the cooling medium outlet of the external circulation liquid chamber 6, the external circulation buffer tank 11, the external circulation pump 7, the external circulation heater 8, the first external circulation cooler 9, the second external circulation cooler 10, and the cooling medium inlet of the external circulation liquid chamber 6 are connected in sequence.

[0071] The reaction circulation pump 3 is connected to the inlet of the mixing connection device 4, the downstream system and the inlet 15 of the vessel, respectively.

[0072] The heating medium outlet of the jacket 5 is connected to the external drain pipe 27, and the heating medium inlet of the jacket 5 is connected to the external heating medium feed pipe 25.

[0073] The method for carrying out the precipitation polymerization reaction of α-olefins with maleic anhydride using the system described in this embodiment includes the following steps:

[0074] S1: Isoamyl acetate, isobutylene, maleic anhydride and divinylbenzene are added to the reactor 1 through the inlet 15 of the reactor body, stirred, and heated to the first preset temperature of 75°C using the heating medium from the external heating medium feed pipe 25. Then, azobisisobutyronitrile is added to the reactor 1 through the inlet 15 of the reactor body, stirred for 10 minutes, and the material in the reactor body 1 is sent into the reaction liquid chamber 2 through the mixing connection device 4.

[0075] S2: The material in the vessel 1 is left to stand in the reaction liquid chamber 2 for 3 hours. During this period, it is cooled to the second preset temperature of 70°C by the cooling medium from the first external circulation cooler 9 and the second external circulation cooler 10 (at this time, the external circulation heater 8 is not working). The pressure of the system is maintained at a constant 0.8 MPaG by the pressure control device 28 until the reaction is completed, and the reaction liquid is obtained. There is no forced flow of the reaction liquid during the reaction.

[0076] S3: The system pressure is reduced to 0.08 MPaG by the pressure control device 28, and the reaction liquid is sent back to the reactor 1 by the reaction circulation pump 3. The mixture is stirred and heated to a third preset temperature of 110°C by the heating medium from the external heating medium feed pipe 25 to remove unreacted olefins. The final reaction liquid is then sent back to the reaction liquid chamber 2.

[0077] S4: In the reaction liquid chamber 2, the final reaction liquid is cooled by the cooling medium from the first external circulation cooler 9 and the second external circulation cooler 10, and then circulated between the outlet and inlet of the reaction liquid chamber 2 by the reaction circulation pump 3 to a fourth preset temperature of 25°C (circulation for 1.5 hours) before being sent to the downstream system.

[0078] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A reaction method for the precipitation polymerization of α-olefins with maleic anhydride, characterized in that, The system used in this method includes a reaction cycle subsystem and an external circulation heat removal subsystem; The reaction cycle subsystem includes a reaction vessel, a reactor, a reaction cycle pump, and a mixing connection device; the reaction vessel includes a vessel body, a jacket, a stirring device, and a first non-condensable gas outlet; the reactor includes a reaction liquid chamber, an external circulation liquid chamber, and a second non-condensable gas outlet, the external circulation liquid chamber being arranged around the outside of the reaction liquid chamber and not communicating with the reaction liquid chamber; the second non-condensable gas outlet is located at the top of the reaction liquid chamber; The outlet of the vessel, the mixing connection device, the reaction liquid chamber, and the reaction circulation pump are connected in sequence; the reaction circulation pump is connected to the inlet of the mixing connection device, the downstream system, and the inlet of the vessel, respectively. The external circulation heat removal subsystem includes an external circulation buffer tank, an external circulation pump, an external circulation heater, and an external circulation cooler; the cooling medium outlet of the external circulation liquid cavity, the external circulation buffer tank, the external circulation pump, the external circulation heater, the external circulation cooler, and the cooling medium inlet of the external circulation liquid cavity are connected in sequence; The heating medium outlet of the jacket is connected to an external drain pipe, and the heating medium inlet of the jacket is connected to an external heating medium feed pipe. The reaction cycle subsystem also includes a pressure control device; the connecting pipeline of the first non-condensable gas outlet merges with the connecting pipeline of the second non-condensable gas outlet, and the pressure control device is installed on the merged pipeline to measure the pressure of the system and control the discharge of non-condensable gas according to the pressure. The method includes the following steps: S1: Add solvent, α-olefin, maleic anhydride and crosslinking agent to the reactor body, stir, heat to the first preset temperature using a heating medium, add initiator to the reactor body, stir evenly, and send the material in the reactor body into the reaction liquid chamber through a mixing and connecting device; S2: In the reaction liquid chamber, the mixture is cooled to a second preset temperature using a cooling medium, and the pressure of the system is maintained constant by the pressure control device until the reaction is completed, thus obtaining a reaction liquid. S3: Reduce the system pressure through the pressure control device, send the reaction liquid back to the reactor body through the reaction circulation pump, stir, and heat to a third preset temperature using a heating medium to remove unreacted olefins, and then send the final reaction liquid back into the reaction liquid chamber. S4: In the reaction liquid chamber, the final reaction liquid is cooled to a fourth preset temperature by using a cooling medium and circulating between the outlet and inlet of the reaction liquid chamber by the reaction circulation pump, and then sent to the downstream system.

2. The reaction method for precipitation polymerization of α-olefins with maleic anhydride according to claim 1, wherein, The reaction cycle subsystem also includes a first temperature control device and a second temperature control device; The first temperature control device is used to measure the temperature of the vessel body and control the flow rate of the heating medium entering the jacket according to the temperature; The second temperature control device is used to measure the temperature of the reaction liquid chamber and select or control the external circulation heater and external circulation cooler according to the temperature.

3. The reaction method for precipitation polymerization of α-olefins with maleic anhydride according to claim 1, wherein, The stirring device includes one or more stirring blades, which are arranged axially.

4. The reaction method for precipitation polymerization of α-olefins with maleic anhydride according to claim 1, wherein, The jacket includes one or more cavities, which may be interconnected or not interconnected. The external circulating fluid chamber includes one or more chambers, which may be interconnected or not interconnected. The reaction liquid chamber includes one or more chambers, and the multiple chambers are interconnected; There are 1-2 external circulation coolers.

5. The reaction method for precipitation polymerization of α-olefins with maleic anhydride according to claim 1, wherein, In step S1: The solvent is an alcohol, ester, ketone, alkane or ether with a boiling point greater than 60°C at one standard atmosphere, or at least one of an alcohol, ester, ketone, alkane and ether with a bubble point or azeotropic point greater than 60°C. The crosslinking agent is divinylbenzene and / or styrene; The α-olefin is a C4-C9 α-olefin, or a hydrocarbon mixture in which the mass content of C4-C9 α-olefin is greater than 20% based on the total weight of the hydrocarbon mixture; The initiator is azobisisobutyronitrile and / or benzoyl peroxide; The first preset temperature is no more than 130°C.

6. The reaction method for precipitation polymerization of α-olefins with maleic anhydride according to claim 1, wherein, In step S2: The reaction time is 2-12 hours; The second preset temperature is no more than 130℃; Maintain the system pressure at 0.5-2.0 MPaG; There is no forced flow of the reaction solution during the reaction.

7. The reaction method for precipitation polymerization of α-olefins with maleic anhydride according to claim 1, wherein, In step S3: Reduce the system pressure to 0.05-0.10 MPaG; The third preset temperature is 100-200℃.

8. The reaction method for precipitation polymerization of α-olefins with maleic anhydride according to claim 1, wherein, In step S4: The fourth preset temperature is 20-40℃; The circulation time is 1-2 hours.

9. The reaction method for precipitation polymerization of α-olefins with maleic anhydride according to claim 1, wherein, There are two external circulation coolers, including a first external circulation cooler and a second external circulation cooler; The temperature of the heating medium in the external circulation heater is 80-250℃; The temperature of the cooling medium in the first external circulation cooler is 30-70℃; The temperature of the cooling medium in the second external circulation cooler is -30 to 20°C; The temperature of the heating medium in the external heating medium feed pipe is 60-280℃.

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