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

Abstract

This invention belongs to the field of polymerization reactions and discloses a reaction system and method for the precipitation polymerization of α-olefins with maleic anhydride. The system includes a reaction circulation subsystem and an external circulation temperature control subsystem. The reaction circulation subsystem includes a reaction vessel, a reactor, a reaction circulation 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 is arranged around the outside of the reaction liquid chamber and is not connected to it. The external circulation temperature control subsystem includes an external circulation buffer tank, an external circulation pump, an external circulation heater, and an external circulation cooler. This invention, through a segmented reaction system, separates the heating and cooling functions of the reaction vessel, meeting the heating and cooling requirements of the precipitation polymerization of α-olefins with maleic anhydride in different solvent systems at different reaction stages.

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 and maleic anhydride, the system comprising a reaction cycle subsystem and an external circulation temperature control 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 body, 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 and the downstream system respectively.

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

[0011] The temperature regulating medium outlet, external circulation buffer tank, external circulation pump, external circulation heater, external circulation cooler, and temperature regulating medium inlet of the jacket are connected in sequence.

[0012] According to the present invention, preferably, the reaction cycle subsystem further includes a first temperature control device, a second temperature control device, a third 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 temperature regulating 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 third temperature control device is used to measure the temperature of the temperature-regulating medium entering the jacket and control the external circulation heater according to the temperature.

[0016] 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.

[0017] According to the present invention, preferably, the stirring device includes one or more stirring blades, the multiple stirring blades being arranged axially.

[0018] According to the present invention, preferably, the jacket includes one or more cavities, which may be interconnected or not interconnected.

[0019] According to the present invention, preferably, the external circulating fluid cavity includes one or more cavities, which are interconnected or not interconnected.

[0020] According to the present invention, preferably, the reaction liquid chamber includes one or more chambers, and the multiple chambers are interconnected.

[0021] According to the present invention, preferably, there are 1-2 external circulation coolers.

[0022] 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:

[0023] S1: The solvent, mixed α-olefin and maleic anhydride are added to the reactor body and stirred. After heating to the first preset temperature using a temperature-regulating medium, the initiator is added to the reactor body and stirred evenly. The material in the reactor body is then sent into the reaction liquid chamber through a mixing and connecting device.

[0024] S2: In the reaction liquid chamber, the reaction medium is not forced to flow. The temperature is controlled at a second preset temperature by a temperature regulating medium. The pressure of the system is maintained constant by the pressure control device until the reaction ends, and the final reaction liquid is obtained.

[0025] S3: Reduce the system pressure using a pressure control device, cool the final reaction liquid by means of a temperature regulating medium and circulate it between the outlet and inlet of the reaction liquid chamber using the reaction circulation pump to cool it to a third preset temperature, and then send it 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 55°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 55°C.

[0028] The mixed α-olefins are hydrocarbon mixtures in which the mass content of C4-C9 α-olefins is greater than 10% based on the total weight of the hydrocarbon mixture;

[0029] The initiator is azobisisoheptanenitrile;

[0030] The first preset temperature is no more than 70°C.

[0031] According to the present invention, preferably, in step S2:

[0032] The reaction time is 4-10 hours;

[0033] The second preset temperature is no more than 70°C;

[0034] The system pressure is maintained at 0.4-1.5 MPaG.

[0035] According to the present invention, preferably, in step S3:

[0036] Reduce the system pressure to 0.05-0.08 MPaG;

[0037] The third preset temperature is 30-50℃;

[0038] The circulation time is 0.5-1.5 hours;

[0039] According to the present invention, preferably, there are two external circulation coolers, including a first external circulation cooler and a second external circulation cooler;

[0040] The temperature of the heating medium in the external circulation heater is 80-250℃;

[0041] The temperature of the cooling medium in the first external circulation cooler is 30-70℃;

[0042] The temperature of the cooling medium in the second external circulation cooler is -30 to -20℃;

[0043] The beneficial effects of the technical solution of the present invention are as follows:

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 4) The reaction vessel jacket and external circulation temperature control subsystem of this invention adopt a unified temperature control medium, which avoids the operational safety and stress problems caused by switching the jacket of different utilities with different temperatures and phases during the same reaction.

[0048] 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.

[0049] 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.

[0050] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0051] 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.

[0052] Figure 1 A schematic diagram of a reaction system for the precipitation polymerization of α-olefins and maleic anhydride provided by the present invention is shown.

[0053] Figure 2 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.

[0054] The annotations in the attached figures are explained as follows:

[0055] 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-Inlet pipeline of reaction liquid into reaction liquid chamber; 19-Pipeline of final reaction liquid into downstream system; 20-Pipeline of temperature regulating medium into external circulation liquid chamber; 21-Pipeline of temperature regulating medium into jacket; 22-Heating medium of external circulation heater; 23-Cooling medium of first external circulation cooler; 24-Cooling medium of second external circulation cooler; 26-First non-condensable gas outlet; 27-Third temperature control device; 28-Pressure control device; 29-Second non-condensable gas outlet. Detailed Implementation

[0056] 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.

[0057] Example

[0058] This embodiment provides a reaction system for the precipitation polymerization of α-olefins and maleic anhydride, such as... Figure 2 As shown, the system includes a reaction cycle subsystem and an external circulation temperature control subsystem;

[0059] 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;

[0060] 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.

[0061] 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.

[0062] The reaction cycle subsystem also includes a first temperature control device 13, a second temperature control device 14, a third temperature control device 27, and a pressure control device 28;

[0063] The first temperature control device 13 is used to measure the temperature of the vessel body 1 and control the flow rate of the temperature regulating medium entering the jacket 5 according to the temperature.

[0064] 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.

[0065] The third temperature control device 27 is used to measure the temperature of the temperature regulating medium entering the jacket 5 and control the external circulation heater 8 according to the temperature.

[0066] 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.

[0067] The external circulation temperature control subsystem includes an external circulation buffer tank 11, an external circulation pump 7, an external circulation heater 8, and an external circulation cooler; the temperature control 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 second external circulation cooler 10, and the temperature control medium inlet of the external circulation liquid chamber 6 are connected in sequence.

[0068] The reaction circulation pump 3 is connected to the inlet of the mixing connection device 4 and the downstream system, respectively.

[0069] The temperature regulating medium outlet of the jacket 5, the external circulation buffer tank 11, the external circulation pump 7, the external circulation heater 8, the first external circulation cooler 10, and the temperature regulating medium inlet of the jacket 5 are connected in sequence.

[0070] 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:

[0071] S1: Add the acetone / hexane mixture, the isobutylene-containing mixed C4 and maleic anhydride into the reactor 1 through the inlet 15 of the reactor body, stir, and heat to the first preset temperature of 55°C using the temperature-regulating medium (the temperature-regulating medium is set to 80°C) from the external circulation heater 8 (at this time, the second external circulation cooler 10 is not working). Then add azobisisobutyronitrile into the reactor 1 through the inlet 15 of the reactor body, stir for 10 minutes, and send the material in the reactor body 1 into the reaction liquid chamber 2 through the mixing connection device 4.

[0072] S2: The material in the vessel 1 is left to stand in the reaction liquid chamber 2 for 6 hours. During this period, it is cooled to the second preset temperature of 55°C by the temperature regulating medium from 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 0.6 MPaG by the pressure control device 28 until the reaction ends, and the final reaction liquid is obtained. There is no forced flow of the reaction liquid during the reaction.

[0073] S3: The system pressure is reduced by 0.06 MPaG by the pressure control device 28, and the final reaction liquid is cooled by the temperature regulating medium from the second external circulation cooler 10 (at this time, the external circulation heater 8 is not working) and circulated between the outlet and inlet of the reaction liquid chamber 2 by the reaction circulation pump 3 to a third preset temperature of 35°C (circulation for 1 hour) before being sent to the downstream system.

[0074] 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 temperature control 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 body, 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 and the downstream system respectively. The external circulation temperature control subsystem includes an external circulation buffer tank, an external circulation pump, an external circulation heater, and an external circulation cooler; the temperature control 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 temperature control medium inlet of the external circulation liquid cavity are connected in sequence; The temperature regulating medium outlet, external circulation buffer tank, external circulation pump, external circulation heater, external circulation cooler, and temperature regulating medium inlet of the jacket are connected in sequence. 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: The solvent, mixed α-olefin and maleic anhydride are added to the reactor body and stirred. After heating to the first preset temperature using a temperature-regulating medium, the initiator is added to the reactor body and stirred evenly. The material in the reactor body is then sent into the reaction liquid chamber through a mixing and connecting device. S2: In the reaction liquid chamber, the reaction medium is not forced to flow. The temperature is controlled at a second preset temperature by a temperature regulating medium. The pressure of the system is maintained constant by the pressure control device until the reaction ends, and the final reaction liquid is obtained. S3: Reduce the system pressure using a pressure control device, cool the final reaction liquid by means of a temperature regulating medium and circulate it between the outlet and inlet of the reaction liquid chamber using the reaction circulation pump to cool it to a third preset temperature, and then send it 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, a second temperature control device, and a third 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 temperature regulating 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. The third temperature control device is used to measure the temperature of the temperature-regulating medium entering the jacket and control the external circulation heater 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, which are interconnected.

5. The reaction method for precipitation polymerization of α-olefins with maleic anhydride according to claim 1, wherein, There are 1-2 external circulation coolers.

6. 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 55°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 55°C. The mixed α-olefins are hydrocarbon mixtures in which the mass content of C4-C9 α-olefins is greater than 10% based on the total weight of the hydrocarbon mixture; The initiator is azobisisoheptanenitrile; The first preset temperature is no more than 70°C.

7. The reaction method for precipitation polymerization of α-olefins with maleic anhydride according to claim 1, wherein, In step S2: The reaction time is 4-10 hours; The second preset temperature is no more than 70°C; The system pressure is maintained at 0.4-1.5 MPaG.

8. 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 0.05-0.08 MPaG; The third preset temperature is 30-50℃; The circulation time is 0.5-1.5 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.

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