Loop reactor system and process for liquid phase peroxidation of ethylbenzene

Abstract

The present application relates to a loop reactor system and method for liquid phase peroxidation of ethylbenzene. The loop reactor comprises an ejector, a reaction kettle, a circulating pump and a heat exchanger; the ejector comprises a nozzle cavity provided with a nozzle, a suction section, a mixing section and a diffusion section; the circulating liquid is jetted at high speed through the ejector, a low pressure area is formed at the nozzle of the ejector, gas is sucked into the low pressure area, and the gas is broken into tiny bubbles; the bottom end of the ejector extends into the liquid surface of the reaction kettle; the gas-liquid two-phase mixture flows into the reaction kettle after mixing through the ejector; the gas-liquid mixture collides with the material in the reaction kettle, promoting the mixing and dispersion of the gas-liquid mixture; the material flows through the heat exchanger through the bottom outlet of the reaction kettle. The multi-stage loop reactor is connected in series, the reaction products between stages are sent to the next stage reactor through a separation system, air is fed separately to each reactor, and ethylbenzene raw materials and other materials are supplemented from the first stage. The present application has the advantages of high efficiency, small footprint, simple structure, stable control, etc.

Description

Technical Field

[0001] This invention belongs to the field of chemical production technology, specifically relating to a loop reactor system and method for liquid-phase peroxidation of ethylbenzene. Background Technology

[0002] Ethylbenzene hydrogen peroxide is an important organic chemical raw material that can participate in various organic synthesis reactions as an oxidant. It can oxidize compounds containing unsaturated bonds (such as carbon-carbon double bonds and carbon-nitrogen double bonds), for example, in the propylene oxide / styrene co-production (PO / SM) process, it reacts with propylene to produce propylene oxide and styrene. In the field of polymer chemistry, ethylbenzene hydrogen peroxide is an important free radical polymerization initiator. For example, in the production of plastics such as polystyrene, it can initiate the polymerization reaction of styrene monomers, which is the basis for manufacturing various plastic products. Polystyrene, due to its excellent insulation, transparency, and processability, is widely used in packaging materials, electronic and electrical appliance housings, and other products.

[0003] Currently, the industrial production of ethylbenzene hydrogen peroxide uses a horizontal multi-stage bubbling reactor, with heat exchange tubes and baffles in each stage. US patents US4066706 and US4262143 disclose a horizontal reactor that uses baffles to divide the reactor into 5-10 zones. The ethylbenzene reaction liquid enters the reactor from one side, passes through each zone sequentially, and exits from the other side. Air is blown into the corresponding zones from the bottom, reacts with the ethylbenzene, and exits from the top. Shell's patent CN101022885A differs from the above reactor; Shell's reactor uses axial baffles, and air distributors are arranged in the separated reaction zones. A tube-and-shell heat exchanger is also installed below the liquid surface of the reactor to remove heat. However, for the multiphase process of ethylbenzene peroxide, uniform gas distribution is crucial. In practical applications, the above reactors still suffer from insufficient gas-liquid mixing, limited mass transfer, and low reaction efficiency.

[0004] To address the problems of existing reactors, patent reports describe various methods to improve gas-liquid mass transfer. Wanhua Chemical Group Co., Ltd. disclosed a multi-stage horizontal stirred airlift reactor in patent CN107930555B. The reactor retains a horizontal cylindrical structure with multiple longitudinally spaced baffles within the reactor. A guide tube and stirring device are added in the middle to improve the mixing effect of the reaction raw materials and circulating mother liquor. Zhejiang Zhiying Petrochemical Technology Co., Ltd. disclosed a horizontal reactor in patent CN113680302B, which increases the contact time between air and materials by setting internal distribution pipes and radial baffles, thereby increasing the yield of ethylbenzene hydrogen peroxide. Changzhou Ruihua Chemical Engineering Technology Co., Ltd. disclosed a vertical bubble column reaction system in patent CN111606835A, which achieves ethylbenzene hydrogen peroxide concentration control through multi-stage series connection. China Petrochemical Engineering Construction Co., Ltd. disclosed a multi-stage vertical bubble column system in a patent, with an internal guide tube and gas distribution pipe to control the temperature distribution within the reactor. The stirred and bubble tower reactors mentioned in the above patent reports still have problems such as uneven gas distribution, insufficient mixing effect, difficulty in scale-up, and complex structure during the design process.

[0005] A loop reactor is a multiphase reactor suitable for continuous production. It achieves uniform bubble breakage and dispersion through injection, enhancing gas-liquid mass transfer. It is currently used in reactions such as hydrogenation and carbonylation. However, there are no reports on its application in the production of ethylbenzene through peroxidation.

[0006] The loop reactor mainly consists of four parts: an ejector, a reaction vessel, a circulating pump, and an external heat exchanger. Liquid is pressurized and injected into the ejector via the circulating pump. The high-speed flowing liquid phase creates a low-pressure zone within the ejector, entraining and shearing the gas into tiny bubbles. The design of the ejector and the reaction vessel is crucial. For the ethylbenzene peroxidation reaction, the reactants themselves are unstable, easily decompose at high temperatures (>160℃), and exhibit deep oxidation characteristics, generating other byproducts (such as acetophenone and phenylethanol), which adversely affect subsequent synthesis and separation. Existing design methods cannot provide guidance on how to achieve sufficient gas-liquid contact and effective control of the reaction depth. Conventional design methods rely on small-scale experiments and empirical correlations, limiting the applicability of the system. They cannot predict the relationship between key structures such as the ejector and reaction vessel and bubble size and mass transfer coefficient, offering limited guidance and inevitably leading to scale-up effects. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing reactors for ethylbenzene peroxidation, such as large surface area, poor reaction effect, and unstable control, and to develop a novel, efficient, stable, and reliable loop reactor system and method.

[0008] To achieve the above objectives, this invention provides a reaction system and method for preparing ethylbenzene hydrogen peroxide through ethylbenzene peroxidation. This method uses ethylbenzene and air as raw materials to synthesize ethylbenzene hydrogen peroxide through a peroxidation reaction. A novel loop reactor is employed to enhance gas-liquid mass transfer, specifically in the design of the ejector structure and reactor structure, thereby solving problems such as poor gas distribution, complex equipment structure, large footprint, and high investment associated with existing reactors. Specifically, this invention uses a loop reactor to prepare ethylbenzene hydrogen peroxide: before the reaction begins, the raw materials, initiator, catalyst, etc., are placed in the reactor vessel of the loop reactor. Air is introduced into the loop reactor, and the reaction temperature is controlled at 130–160°C by controlling the circulation rate and the shell-side heat transfer system. The reactor pressure is controlled at 0.1–0.3 MPa through the tail gas system.

[0009] This invention uses a loop reactor as the reactor for the liquid-phase peroxidation of ethylbenzene. The gas is broken into tiny bubbles by liquid injection. Through optimized design, the contact area between the gas and liquid reactants (ethylbenzene and oxygen) is greatly increased, the mass transfer rate is improved, and the over-oxidation of ethylbenzene to generate other by-products is avoided, thereby improving the overall reaction efficiency.

[0010] The technical solution of the present invention is as follows:

[0011] A loop reactor system for liquid-phase peroxidation of ethylbenzene; the loop reactor includes an ejector, a reaction vessel, a circulating pump, and a heat exchanger; the ejector, from top to bottom, includes a nozzle cavity with nozzles installed, an intake section, a mixing section, and a diffusion section; wherein: the key structural parameters of the ejector include nozzle diameter Dn, nozzle angle α, intake section length Lt (distance from nozzle to throat), mixing section diameter Dt, mixing section length Lm, diffusion section length Ld, and diffusion section outlet diameter Dd; wherein: the ratio of mixing section diameter to nozzle diameter Dt / Dn is 2 to 4; the nozzle contraction angle α is 20 to 40°; the ratio of intake section diameter to mixing section diameter Dc / Dt is greater than 2; the ratio of intake section length to mixing section diameter Lt / Dt should be greater than 4; the recommended ratio of the length of the mixing section to the diameter of the mixing section Lm / Dt is (1 to 3):1.

[0012] The length-to-diameter ratio of the reactor vessel in the loop reactor is preferably 2 to 6.

[0013] The number of injectors is preferably 1 to 6.

[0014] The fluid linear velocity at the ejector nozzle of the loop reactor is preferably controlled between 60 and 120 m / s.

[0015] The distance r from the center of the injector to the center of the reactor is given, and the radius of the reactor is R. The value of r / R is preferably 0.4 to 0.6.

[0016] The ethylbenzene liquid-phase peroxidation reaction is carried out using a multi-stage loop reactor, preferably with 2 to 6 stages.

[0017] The heat exchanger used can be a tubular, plate, or other type of heat exchanger.

[0018] The method for liquid-phase peroxidation of ethylbenzene using a loop reactor system involves placing the raw materials, initiator, and catalyst into the reactor vessel before the reaction begins, and introducing air into the reactor. A circulating pump is then started to power the circulating liquid in the loop. The circulating liquid is sprayed at high speed by an ejector, creating a low-pressure zone at the ejector nozzle, which entrains the gas. Simultaneously, the gas is broken into tiny bubbles, significantly increasing the gas-liquid contact area and promoting the gas-liquid mass transfer rate. The bottom of the ejector extends below the liquid surface in the reactor vessel, and the gas and liquid phases are thoroughly mixed before flowing into the reactor vessel. The gas-liquid mixture impacts the materials in the reactor vessel, promoting gas-liquid mixing and dispersion. The material flows through a heat exchanger at the bottom outlet of the reactor vessel to remove heat promptly. The reaction temperature is controlled at 130–160°C by controlling the circulation rate and the shell cooling water temperature, and the reactor pressure is controlled at 0.1–0.3 MPa.

[0019] To control the reaction process, a multi-stage loop reactor is connected in series. The reaction products between stages are sent to the next stage reactor via a separation system. Air is fed into each reactor separately, while ethylbenzene and other materials are added from the first stage.

[0020] For an ethylbenzene peroxide loop reactor system, the key factors are the ejector structural dimensions design, process parameter settings, the number of ejectors, and their arrangement within the reactor. The nozzle diameter and angle directly affect the internal flow field, and a suitable flow velocity is a prerequisite for effective gas-liquid mixing. The distance from the nozzle to the throat, the throat diameter, and the mixing length directly affect the bubble size distribution; controlling these proportions is crucial. The diffuser section provides the space for thorough gas-liquid mixing.

[0021] Preferably, the ejector of the loop reactor uses a throat with a mixing length. The purpose of the mixing section is to achieve uniform mixing of bubbles as much as possible. The recommended ratio of the length of the mixing section to the diameter of the mixing section, Lm / Dt, is (1~3):1.

[0022] Preferably, during the ethylbenzene peroxidation reaction, the fluid linear velocity at the injector nozzle of the loop reactor is controlled at 60–120 m / s.

[0023] The preferred arrangement of the ejector and reactor in a loop reactor is as follows: define the distance r from the center of the ejector to the center of the reactor, the radius of the reactor as R, and the value of r / R should be controlled between 0.4 and 0.6.

[0024] This invention uses a loop reactor as the reactor for the liquid-phase peroxidation of ethylbenzene. The reaction temperature is controlled by an external circulating cooler. The heat transfer medium of the cooler can be either low-pressure steam produced as a byproduct or directly exchanged with other materials, depending on the process requirements.

[0025] This invention employs a multi-stage loop reactor to achieve high conversion rates in the ethylbenzene peroxidation process. By controlling the size and reaction temperature of each stage reactor, the reaction process is effectively controlled, and side reactions are suppressed. A preferred number of stages in the loop reactor is 2 to 6.

[0026] The present invention has the following advantages over the prior art:

[0027] 1. This invention optimizes the design of the ejector and reaction vessel structure of the loop reactor, effectively improving the flow and mass transfer performance within the ethylbenzene peroxidation reactor and thus enhancing the overall reaction efficiency.

[0028] 2. This invention achieves efficient bubble breakage and increases the specific surface area of ​​the gas-liquid interface by using the optimal length of the injector mixing section.

[0029] 3. The loop reactor uses a circulating pump instead of an electric agitator to provide power, resulting in higher energy transfer efficiency and less mechanical loss.

[0030] 4. The loop reactor uses an external heat exchanger, which has no limit on the heat exchange area. It can provide sufficient heat exchange area according to the required heat exchange, and can remove the generated heat of reaction in a timely manner to avoid excessive temperature affecting the fluid flow state and the generation of hot spots in the reactor.

[0031] 5. The loop reactor has no other moving parts inside the reactor vessel, ensuring good sealing and unrestricted length-to-diameter ratio. Furthermore, the ejector, reactor vessel, and heat exchanger are all independent components, making scale-up easier to achieve.

[0032] 6. Gas intake no longer relies on compressor delivery, but on the entrainment effect of the liquid phase, achieving sufficient gas-liquid mixing with lower energy consumption and effectively saving costs.

[0033] 7. This invention specifies the length-to-diameter ratio, number and position of injectors of the reactor, thereby achieving more thorough mixing of gas and liquid in the reactor, enhancing the gas-liquid mass transfer process, and increasing the reaction rate.

[0034] 8. The production of ethylbenzene hydrogen peroxide using a loop reactor has advantages such as high efficiency, small footprint, simple structure, and stable control. Attached Figure Description

[0035] Figure 1 Schematic diagram of a single-stage loop reactor for ethylbenzene peroxidation

[0036] Figure 2Schematic diagram of a two-stage loop reactor for ethylbenzene peroxidation

[0037] Figure 3 for Figure 1 Detailed structural diagram of the injector in the diagram

[0038] Figure 4 for Figure 1 Schematic diagram of the relative positions of the three injectors inside the reactor.

[0039] Explanation of serial numbers: 101-First-stage ejector, 102-First-stage reactor, 103-First-stage circulating pump, 104-First-stage heat exchanger, 105-First-stage separation system, 106-First-stage ethylbenzene inlet, 107-First-stage gas intake chamber, 108-First-stage circulating liquid inlet, 109-First-stage nozzle, 110-First-stage mixing section, 111-First-stage diffusion section, 112-First-stage nozzle outlet, 201-Second-stage ejector, 202-Second-stage reactor, 203-Second-stage circulating pump, 204-Second-stage heat exchanger, 205-Second-stage separation system;

[0040] Symbol explanation: Di - circulating liquid inlet diameter, Dn - nozzle diameter, Dc - suction section diameter, α - nozzle angle, Lt - suction section length, Dt - mixing section diameter, Lm - mixing section length, Ld - diffusion section length, Dd - diffusion section outlet diameter. Detailed Implementation

[0041] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0042] like Figure 1 The diagram shows a single-stage loop reactor, which is used in this invention for the ethylbenzene peroxidation process. The loop reactor mainly includes a primary ejector (101), a primary reactor (102), a primary circulating pump (103), and a primary heat exchanger (104). The ejector is shown in the schematic diagram; for its specific structure, see [link to schematic diagram]. Figure 3 .

[0043] Before the reaction begins, the raw materials ethylbenzene, initiator, catalyst, etc. are placed in the reactor of the loop reactor, and air is introduced into the loop reactor; the primary heat exchanger (104) used in this patent can be a tubular, plate, or other type of heat exchanger.

[0044] For the liquid-phase peroxidation reaction of ethylbenzene, the structure of the primary ejector (101) and the primary reactor (102) directly affects the degree of gas-liquid mixing, mass transfer, and reaction rate. A schematic diagram of the preferred ejector and reactor structure is shown below. Figure 3 , Figure 4 As shown. Figure 3The diagram shows a specific first-stage injector structure. High-speed liquid is ejected from the center of the first-stage nozzle (109) and interacts with the first-stage gas intake chamber (107) to form a suction effect. The mixed gas and liquid enter the first-stage mixing section (110) and the first-stage diffusion chamber (111). The inlet of the mixing section is the throat. In the mixing section, the gas and liquid are fully mixed and evenly distributed. Figure 4 A schematic diagram of the relative arrangement of multiple injectors in the primary reactor (102) is given, with multiple nozzles evenly arranged.

[0045] Example 1

[0046] by Figure 2 This will be illustrated using a two-stage loop reactor system as an example:

[0047] The number of primary ejectors (101) is 1, and the specific structural parameters are as follows: the diameter Di of the circulating liquid inlet (108) of the primary ejector (101) is 500 mm, the diameter Dn of the primary nozzle (109) is 80 mm, the ratio of the mixing section diameter to the nozzle diameter is Dt / Dn = 2, the nozzle angle α is 30°, the ratio of the suction section diameter to the mixing section diameter is Dc / Dt = 2, the ratio of the suction section length to the mixing section diameter is Lt / Dt = 10:1, the ratio of the length of the ejector mixing section to the mixing section diameter is Lm / Dt = 2:1, the outlet diameter Dd of the primary diffuser section (111) is 450 mm, the fluid linear velocity at the primary nozzle (109) of the loop reactor is controlled at 100 m / s, the ejector is arranged in the center of the reactor, and the total volume of the reactor is 350 m³. 3 The length-to-diameter ratio is 4:1, and the configuration of the secondary injector (201) is the same;

[0048] The feed flow rate of ethylbenzene raw material is 1500 t / h, added from the primary reaction system. Ethylbenzene hydrogen peroxide (organic peroxide) initiator is added simultaneously; catalyst is optional. The air feed flow rates of the primary reactor (102) and the secondary reactor (202) are 24 t / h and 32 t / h, respectively. When the loop reactor is working, the primary circulating pump (103) is started to provide power for the circulating liquid in the loop. The circulating liquid is sprayed at high speed by the primary ejector (101), forming a low-pressure area at the primary nozzle (109), which entrains the gas. The bottom end of the ejector extends below the liquid surface in the primary reactor (102), and the gas and liquid phases are fully mixed by the ejector before flowing into the primary reactor (102). The material flows through the primary heat exchanger (104) through the bottom outlet of the reactor to remove heat in time, controlling the reaction temperature to be stable at 150℃. The pressure of the primary reactor (102) is controlled at 0.2 MPa. To control the reaction process, a two-stage loop reactor is connected in series, and the reaction products between stages are sent to the next stage reactor via a separation system.

[0049] The bubble size at the throat center of the first-stage injector (101) is approximately 0.4 mm, and the bubble size at the outlet of the first-stage diffuser section (111) is approximately 0.8 mm. The specific surface area of ​​the gas-liquid interface at the throat center of the first-stage mixing section (110) is approximately 1400 m². -1 The volumetric mass transfer coefficient is approximately 15s. -1 Under these conditions, the content of ethylbenzene hydroperoxide in the liquid phase product of the secondary reactor (202) is approximately 3.8 wt%.

[0050] Compared to traditional stirring or bubbling methods, by controlling process conditions, the overall reaction efficiency is comparable, the amount of air added is reduced by more than 15%, and the area occupied is reduced by more than 40%.

[0051] Example 2

[0052] by Figure 2 Taking this as an example, the number of primary ejectors (101) is 3, and the specific structural parameters are as follows: the diameter Di of the circulating liquid inlet (108) of the primary ejector (101) is 300mm, the diameter Dn of the nozzle (109) is 60mm, the ratio of the diameter of the mixing section to the diameter of the nozzle is Dt / Dn=3, the nozzle angle α is 30°, the ratio of the diameter of the suction section to the diameter of the mixing section is Dc / Dt=4, the ratio of the length of the suction section to the diameter of the mixing section is Lt / Dt 8:1, the ratio of the length of the mixing section to the diameter of the mixing section is Lm / Dt 3:1, the outlet Dd of the diffuser section (111) is 300mm, the fluid linear velocity at the ejector nozzle (109) of the loop reactor is controlled at 120m / s, and the nozzle arrangement is as follows Figure 4 As shown, the r / R value is 0.5. The total volume of the reactor is 300 m³. 3 The length-to-diameter ratio is 2:1, and the configuration of the secondary injector (201) is the same.

[0053] The feed flow rate of ethylbenzene is 1500 t / h, added from the primary reaction system, along with the initiator ethylbenzene hydrogen peroxide (organic peroxide). The catalyst can be a supported cobalt oxide catalyst. The air feed flow rates of the primary reactor (102) and the secondary reactor (202) are 24 t / h and 32 t / h, respectively. When the loop reactor is working, the primary circulating pump (103) is started to provide power for the circulating liquid in the loop. The circulating liquid is sprayed at high speed by the primary ejector (101), forming a low-pressure area at the primary nozzle (109), which entrains the gas. The bottom end of the ejector extends below the liquid surface of the primary reactor (102), and the gas and liquid phases are fully mixed by the ejector before flowing into the primary reactor (102). The material flows through the primary heat exchanger (104) through the bottom outlet of the reactor to remove heat in time, control the reaction temperature to be stable at 130℃, and control the pressure of the reactor (102) to be 0.2 MPa. To control the reaction process, a two-stage loop reactor is connected in series, and the reaction products between stages are sent to the next stage reactor via a separation system.

[0054] The bubble size at the throat center of the first-stage injector (101) is approximately 0.3 mm, and the bubble size at the outlet of the first-stage diffuser section (111) is approximately 0.6 mm. The specific surface area of ​​the gas-liquid interface at the throat center of the first-stage mixing section (110) is approximately 1600 m². -1 The volumetric mass transfer coefficient is approximately 20s. -1 Under these conditions, the content of ethylbenzene hydroperoxide in the liquid phase product of the secondary reactor (202) is approximately 4.2 wt%.

[0055] Compared to traditional stirring or bubbling methods, by controlling process conditions, the overall reaction efficiency is comparable, the amount of air added is reduced by more than 20%, and the area occupied is reduced by more than 50%.

[0056] Example 3

[0057] by Figure 2 Taking this as an example, the number of primary ejectors (101) is 6, and the specific structural parameters are as follows: the diameter Di of the ejector circulating liquid inlet (108) is 200mm, the diameter Dn of the nozzle (109) is 30mm, the ratio of the mixing section diameter to the nozzle diameter is Dt / Dn=4, the nozzle angle α is 20°, the ratio of the suction section diameter to the mixing diameter is Dc / Dt=6, the ratio of the suction section length to the mixing section diameter is Lt / Dt is 4:1, the ratio of the length of the ejector mixing section to the mixing section diameter is Lm / Dt is 3:1, the outlet Dd of the diffuser section (111) is 400mm, and the fluid linear velocity at the primary nozzle (109) of the loop reactor is controlled at 60m / s. The ejectors are arranged according to... Figure 4 The reactor is arranged in a regular and uniform manner, with an r / R value of 0.6. The total volume of the reactor is 400 m³. 3 The length-to-diameter ratio is 2:1, and the configuration of the secondary injector (201) is the same.

[0058] The feed flow rate of ethylbenzene is 1500 t / h, added from the primary reaction system, along with the initiator ethylbenzene hydrogen peroxide (organic peroxide). The catalyst can be a supported cobalt oxide catalyst. The air feed flow rates of the primary reactor (102) and the secondary reactor (202) are 24 t / h and 32 t / h, respectively. When the loop reactor is working, the primary circulating pump (103) is started to provide power for the circulating liquid in the loop. The circulating liquid is sprayed at high speed by the primary ejector (101), forming a low-pressure area at the primary nozzle (109), which entrains the gas. The bottom end of the ejector extends below the liquid surface of the primary reactor (102), and the gas and liquid phases are fully mixed by the ejector before flowing into the primary reactor (102). The material flows through the primary heat exchanger (104) through the bottom outlet of the reactor to remove heat in time, control the reaction temperature to be stable at 140℃, and control the pressure of the primary reactor (102) to be 0.1 MPa. To control the reaction process, a two-stage loop reactor is connected in series, and the reaction products between stages are sent to the next stage reactor via a separation system.

[0059] The bubble size at the throat center of the first-stage injector (101) is approximately 0.4 mm, and the bubble size at the outlet of the first-stage diffuser section (111) is approximately 0.8 mm. The specific surface area of ​​the gas-liquid interface at the throat center of the first-stage mixing section (110) is approximately 1200 m². -1 The volumetric mass transfer coefficient is approximately 10s. -1 Under these conditions, the content of ethylbenzene hydroperoxide in the liquid phase product (202) of the secondary reactor is approximately 3.7 wt%.

[0060] Compared to traditional stirring or bubbling methods, by controlling process conditions, the overall reaction efficiency is comparable, the amount of air added is reduced by more than 10%, and the area occupied is reduced by more than 35%.

[0061] Example 4

[0062] by Figure 2 For example, the number of first-stage ejectors (101) is 3, and the specific parameters are as follows: the diameter Di of the liquid phase inlet (108) of the first-stage ejector is 350 mm, the diameter Dn of the first-stage nozzle (109) is 50 mm, the ratio of the diameter of the mixing section to the diameter of the nozzle is Dt / Dn = 4, the nozzle angle α is 40°, the ratio of the diameter of the suction section to the diameter of the mixing section is Dc / Dt = 3, the ratio of the length of the suction section to the diameter of the mixing section is Lt / Dt = 6:1, the ratio of the length of the mixing section to the diameter of the mixing section is Lm / Dt = 4:1, the outlet diameter Dd of the first-stage diffuser is 400 mm, and the fluid linear velocity at the first-stage nozzle (109) of the first-stage loop reactor is controlled at 120 m / s. The size of the central bubble at the throat of the first-stage ejector (102) is approximately 0.35 mm, and the ejectors of the first-stage diffuser section (111) are arranged according to... Figure 4 As shown, the r / R value is 0.4, and the total volume of the reactor is 300 m³. 3The length-to-diameter ratio is 6:1, and the secondary injector (201) has the same configuration.

[0063] The feed flow rate of ethylbenzene is 1800 t / h, added from the primary reaction system, along with the initiator ethylbenzene hydrogen peroxide (organic peroxide). The catalyst can be a supported cobalt oxide catalyst. The air feed flow rates of the primary reactor (102) and the secondary reactor (202) are 32 t / h and 40 t / h, respectively. When the loop reactor is working, the primary circulating pump (103) is started to provide power for the circulating liquid in the loop. The circulating liquid is sprayed at high speed by the primary ejector (101), forming a low-pressure area at the nozzle (109) of the primary ejector, which entrains the gas. The bottom end of the ejector extends below the liquid surface of the primary reactor (102), and the gas and liquid phases are fully mixed by the ejector before flowing into the primary reactor (102). The material flows through the primary heat exchanger (104) through the bottom outlet of the reactor to remove heat in time, control the reaction temperature to be stable at 160℃, and control the pressure of the primary reactor (102) to be 0.3 MPa. To control the reaction process, a two-stage loop reactor is connected in series, and the reaction products between stages are sent to the next stage reactor via a separation system.

[0064] The bubble size at the throat center of the first-stage injector (102) is approximately 0.25 mm, and the bubble size at the outlet of the first-stage diffuser section (111) is approximately 0.5 mm. The specific surface area of ​​the gas-liquid interface at the throat center of the first-stage mixing section (110) is approximately 1800 m². -1 The volumetric mass transfer coefficient is approximately 25s. -1 .

[0065] Under these conditions, the content of ethylbenzene hydroperoxide in the liquid phase product (202) of the secondary reactor is approximately 4.5 wt%.

[0066] Compared to traditional stirring or bubbling methods, by controlling process conditions, the overall reaction efficiency is comparable, the amount of air added is reduced by more than 25%, and the area occupied is reduced by more than 50%.

[0067] The technical solutions disclosed and proposed in this invention can be implemented by those skilled in the art by appropriately modifying the conditions and routes, etc. Although the methods and preparation techniques of this invention have been described through preferred embodiments, those skilled in the art can obviously modify or recombine the methods and technical routes described herein without departing from the content, spirit, and scope of this invention to achieve the final preparation technique. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the spirit, scope, and content of this invention. Matters not covered in this invention are common knowledge.

Claims

1. A loop reactor system for liquid-phase peroxidation of ethylbenzene; characterized in that, The loop reactor includes an ejector, a reaction vessel, a circulating pump, and a heat exchanger. The ejector, from top to bottom, includes a nozzle cavity with nozzles installed, an intake section, a mixing section, and a diffusion section. Key structural parameters of the ejector include nozzle diameter Dn, nozzle angle α, intake section length Lt (distance from nozzle to throat), mixing section diameter Dt, mixing section length Lm, diffusion section length Ld, and diffusion section outlet diameter Dd. Specifically, the ratio of the mixing section diameter to the nozzle diameter, Dt / Dn, is 2~4; the nozzle contraction angle α is 20~40°; the ratio of the intake section diameter to the mixing section diameter, Dc / Dt, is greater than 2; the ratio of the intake section length to the mixing section diameter, Lt / Dt, should be greater than 4; and the ratio of the ejector mixing section length to the mixing section diameter, Lm / Dt, is (1~3):

1.

2. The loop reactor system for liquid-phase peroxidation of ethylbenzene as described in claim 1; characterized in that, The length-to-diameter ratio of the reactor vessel in a loop reactor is 2 to 6.

3. The loop reactor system for liquid-phase peroxidation of ethylbenzene as described in claim 1; characterized in that, The number of injectors is 1 to 6.

4. The loop reactor system for liquid-phase peroxidation of ethylbenzene as described in claim 1; characterized in that, The fluid linear velocity at the ejector nozzle of the loop reactor is controlled at 60~120 m / s.

5. The loop reactor system for liquid-phase peroxidation of ethylbenzene as described in claim 1; characterized in that, The distance r from the center of the injector to the center of the reactor is given by the reactor's radius R, and the value of r / R is 0.4~0.

6.

6. The loop reactor system for liquid-phase peroxidation of ethylbenzene as described in claim 1; characterized in that, The liquid-phase peroxidation reaction of ethylbenzene is carried out using a multi-stage loop reactor with 2 to 6 stages.

7. The loop reactor system for liquid-phase peroxidation of ethylbenzene as described in claim 1; characterized in that, The heat exchangers used are tubular, plate, or other types of heat exchangers.

8. A method for liquid-phase peroxidation of ethylbenzene using the loop reactor system of claim 1, characterized in that, Before the reaction begins, the raw materials, initiator, and catalyst are placed in the reactor vessel of the loop reactor, and air is introduced into the loop reactor. The circulation pump is started, and the circulating liquid is sprayed at high speed through the ejector, forming a low-pressure area at the ejector nozzle, which entrains the gas and breaks it into tiny bubbles. The bottom of the ejector extends below the liquid surface in the reactor vessel, and the gas and liquid phases are mixed by the ejector and flow into the reactor vessel. The gas-liquid mixture impacts the materials in the reactor vessel, promoting gas-liquid mixing and dispersion. The materials flow through the bottom outlet of the reactor vessel to the heat exchanger to remove heat. The reaction temperature is controlled at 130~160℃ by controlling the circulation rate and the shell-side heat transfer system, and the reactor pressure is controlled at 0.1~0.3MPa by the tail gas system.

9. A method for liquid-phase peroxidation of ethylbenzene using a loop reactor system as described in claim 8, characterized in that, A multi-stage loop reactor is connected in series. The reaction products between stages are sent to the next stage reactor via a separation system. Air is fed into each reactor separately, while ethylbenzene and other materials are added from the first stage.

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