A microchannel oxidation reactor and oxidation method for a vulcanization accelerator

Abstract

This invention discloses a microchannel oxidation reactor and oxidation method for vulcanization accelerators. The reactor includes a shell with a cold fluid inlet and a cold fluid outlet. Inside the shell, from top to bottom, are arranged a first reaction chamber, a second reaction chamber, and a third reaction chamber. The first reaction chamber has a thin plate structure, the second reaction chamber has a tubular structure, and the third reaction chamber has a disc structure. A feed pipe is provided on the shell. The solution inside the third reaction chamber undergoes swirling motion. The third reaction chamber has a light phase outlet and a heavy phase outlet. Gaps are provided between the first, second, and third reaction chambers and the inner wall of the shell. This invention not only provides excellent temperature control, making it suitable for the oxidation production of vulcanization accelerators, but also simultaneously achieves product separation, reducing subsequent filtration and separation costs.

Description

Technical Field

[0001] This invention relates to the field of microchannel reactor technology, and in particular to a microchannel oxidation reactor and oxidation method for a sulfidation accelerator. Background Technology

[0002] DM, or dibenzothiazole disulfide, is an excellent vulcanization accelerator. It appears as light yellow needle-like crystals, slightly soluble in benzene, dichloromethane, carbon tetrachloride, acetone, ethanol, and ether at room temperature, but insoluble in water, ethyl acetate, gasoline, and alkalis. Production processes include the sodium nitrite method, oxygen oxidation method, and hydrogen peroxide method. The hydrogen peroxide method is the most environmentally friendly, but because the synthesis process involves oxidation, the reaction is rapid and exothermic, easily leading to localized overheating and increased byproducts. To facilitate temperature control, oxidants are typically added dropwise in conjunction with a stirring device, resulting in a lengthy production process. Microchannel reactors, however, offer precise temperature control and are ideal for the synthesis of temperature-sensitive materials, as illustrated in patent 201910319750. Patent 202311761449.5 discloses a microchannel reactor that achieves precise temperature control by concentrating materials in a reaction tube for mixing and reaction. However, this type of reactor is not suitable for the hydrogen peroxide method of producing accelerator DM. This is because the synthesized DM has a high density and is insoluble in water, which will cause it to accumulate in the micro-reaction channels. In addition, solid catalysts are usually added during the hydrogen peroxide synthesis process to accelerate the reaction, such as the high-purity rubber vulcanization accelerator DM and its preparation method disclosed in patent 202311761449.5. The combined effect of the solid catalyst and the product DM will cause the microchannel reactor to become clogged and fail. How to improve the existing microchannel reactor to be suitable for the production of rubber vulcanization accelerator DM is a key challenge that needs to be overcome in the development of this industry. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a microchannel oxidation reactor and oxidation method for sulfurization accelerators that are suitable for the hydrogen peroxide method to synthesize DM, have good temperature control, and avoid clogging of reaction channels.

[0004] One objective of this invention is to provide a microchannel oxidation reactor for a vulcanization accelerator, comprising a shell, wherein a first reaction chamber, a second reaction chamber, and a third reaction chamber are arranged sequentially from top to bottom within the shell. The first reaction chamber is a thin plate structure, the second reaction chamber is a tubular structure, and the third reaction chamber is a disc structure. A feed pipe is provided on the shell, passing through the shell and connecting to the first reaction chamber. One end of the second reaction chamber is connected to the first reaction chamber. The bottom end of the second reaction chamber guides the internal solution to flow into the third reaction chamber at a certain angle. The solution inside the third reaction chamber undergoes swirling motion. The third reaction chamber is provided with a light phase outlet and a heavy phase outlet. The light phase outlet is connected to the bottom center of the third reaction chamber, and the heavy phase outlet is connected to the periphery of the third reaction chamber. Gaps are provided between the first, second, and third reaction chambers and the inner wall of the shell. A cold fluid inlet and a cold fluid outlet are provided on the shell to achieve heat exchange.

[0005] Preferably, there are multiple second reaction chambers, and each second reaction chamber is provided with an internal heat exchange tube. The internal heat exchange tube runs through the second reaction chamber from top to bottom, and its two ends pass through the second reaction chamber and the shell respectively and are connected to the external heat exchange fluid.

[0006] Preferably, the second reaction chamber is provided with a plurality of outer baffle rings and a plurality of inner baffle plates. The outer baffle rings are connected inside the shell, and the inner baffle plates are fixedly connected to the second reaction chamber. The plurality of outer baffle rings and the plurality of inner baffle plates are arranged alternately and staggered at intervals. The plurality of outer baffle rings and the plurality of inner baffle plates form a moving fluid that exchanges heat with the second reaction chamber from the outside to the inside and then from the inside to the outside, from top to bottom.

[0007] Preferably, there are multiple third reaction chambers stacked vertically, and a first guide pipe is provided between adjacent third reaction chambers. The upper end of the first guide pipe is connected to the light phase region in the middle of the third reaction chamber, and the lower end of the first guide pipe guides the internal solution to flow into the separation region of the third reaction chamber at a certain angle.

[0008] Preferably, a crescent ring is provided on the third reaction chamber, the inner ring surface of the crescent ring is sealed to the third reaction chamber, and the outer ring surface of the crescent ring is connected to the inner wall of the shell. The crescent rings are alternately arranged on the left and right sides of the stacked third reaction chambers to guide the heat exchange fluid to perform baffled flow.

[0009] Preferably, the third reaction chamber has an M-shaped structure, comprising a horizontal section, an inclined section, and a sedimentation section. The horizontal section is a light phase reaction liquid collection area, the inclined section is a centrifugal separation reaction area, and the sedimentation section is a gravity separation area.

[0010] Preferably, the settling section is provided with a separation pipe, a control pipe, and a spiral auger. The upper end of the separation pipe is connected to the middle of the settling section, the heavy phase outlet is connected to the bottom of the separation pipe, the spiral auger is located inside the control pipe, the feed end of the control pipe is connected to the bottom of the settling section, and the discharge end of the control pipe is connected to the inclined section of the next layer of the third reaction chamber.

[0011] Preferably, a second guide pipe is provided at the bottom end of the second reaction chamber, and the diameter of the second guide pipe is smaller than the diameter of the third reaction chamber.

[0012] Preferably, the feed pipe has a four-way pipe structure, with one inlet end connected to a crude M sodium salt solution, one inlet end connected to hydrogen peroxide, and one inlet end connected to a catalyst.

[0013] The second objective of this invention is to provide a microchannel oxidation method for a vulcanization accelerator, comprising the following steps:

[0014] S1. The crude M sodium salt solution, hydrogen peroxide, and catalyst are mixed through the feed pipe;

[0015] S2. The mixed reaction solution is discharged into the first reaction chamber, the temperature of the first reaction chamber is controlled to carry out the reaction, and the reaction solution is evenly distributed into the second reaction chamber;

[0016] S3. The reaction takes place in the second reaction chamber, and the reaction liquid is introduced into the third reaction chamber in a swirling manner;

[0017] S4. The reaction takes place in the third reaction chamber, and the product DM is separated into the sedimentation section by centrifugation, while the remaining light phase is separated into the horizontal section;

[0018] S5. The DM solution in the settling section is discharged through the heavy phase outlet, and the light phase solution is discharged through the light phase outlet.

[0019] This invention has the following advantages: It proposes a microchannel oxidation reactor and oxidation method suitable for the reaction synthesis of DM, a sulfidation accelerator. This microchannel reactor not only has good temperature control, but also effectively separates the organic product DM from crude DM, avoiding the problem of DM clogging the microchannel and reducing the cost of subsequent filtration and separation. At the same time, the equipment is also suitable for the use of solid catalysts, ensuring the uniform distribution of solid catalysts in the microchannel reactor, ensuring the stability of the reaction, and further improving production efficiency. Meanwhile, the solid catalyst will not clog the microchannel, and external circulation or replacement is very convenient. Overall, it realizes the microchannel reaction and separation function of aqueous phase, organic phase and solid phase. Attached Figure Description

[0020] Figure 1This is a schematic cross-sectional view of the overall structure of the present invention;

[0021] Figure 2 The present invention Figure 1 Top view of the structure at point AA;

[0022] Figure 3 This is a schematic cross-sectional view of the third reaction chamber of the present invention.

[0023] In the diagram, 1. Shell; 2. First reaction chamber; 3. Second reaction chamber; 4. Third reaction chamber; 5. First guide pipe; 6. Light phase outlet; 7. Heavy phase outlet; 8. Feed pipe; 9. Cold fluid inlet; 10. Cold fluid outlet; 11. Internal heat exchanger tube; 12. Separation pipe; 13. Feed control pipe; 14. Spiral auger; 15. Motor; 16. Discharge pipe; 17. Crescent ring; 18. Outer baffle ring; 19. Inner baffle plate; 20. Second guide pipe; 21. Horizontal section; 22. Inclined section; 23. Settling section. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] like Figure 1-3 As shown, a microchannel oxidation reactor for a vulcanization accelerator includes a shell 1 with a tank structure. Inside the shell 1, from top to bottom, are arranged a first reaction chamber 2, a second reaction chamber 3, and a third reaction chamber 4. The first reaction chamber 2 is a circular thin-plate structure with an internal cavity of 2-3 mm in height. The single-layer thin-plate structure facilitates heat exchange between the upper and lower surfaces. The second reaction chamber 3 is a tubular structure, and there are multiple second reaction chambers 3. Each second reaction chamber 3 is equipped with an internal heat exchange tube 11, which runs from top to bottom through the second reaction chamber 3. Both ends of the internal heat exchange tube 11 pass through the second reaction chamber 3 and the shell 1, respectively, and are connected to an external heat exchange fluid. Because each second reaction chamber 3 is equipped with an internal heat exchange tube 11, the temperature within each individual reaction chamber can be controlled separately, resulting in more precise temperature control.

[0026] Multiple outer baffle rings 18 and multiple inner baffle plates 19 are installed on the second reaction chamber 3. The outer baffle rings 18 are connected inside the shell 1, and the inner baffle plates 19 are fixedly connected to the second reaction chamber 3. The multiple outer baffle rings 18 and multiple inner baffle plates 19 are arranged alternately and staggered at intervals. The multiple outer baffle rings 18 and multiple inner baffle plates 19 form a moving fluid that exchanges heat with the second reaction chamber 3 from the outside to the inside and then from the inside to the outside. Since there are multiple second reaction chambers 3 and they are densely distributed, they together form a cylindrical structure, resulting in a temperature higher at the center of the cylinder than at the periphery. The outer baffle rings 18 and the inner baffle plates 19 can form a baffle motion that moves from the periphery to the center and from the center to the periphery, avoiding the formation of a temperature gradient where the temperature in the center is higher than that in the periphery. Compared with the baffle plates in traditional heat exchangers, they can form a mixed and rotating motion. The rotation is formed by the Coriolis force, resulting in better heat exchange effect.

[0027] The third reaction chamber 4 has a disc-shaped structure with an M-shaped cavity cross-section. It includes a horizontal section 21, an inclined section 22, and a settling section 23. The horizontal section 21 is the light phase reaction liquid collection area, the inclined section 22 is the centrifugal separation reaction area, and the settling section 23 is the gravity separation area. Multiple third reaction chambers 4 are stacked vertically. A first guide pipe 5 is installed between adjacent third reaction chambers 4. The upper end of the first guide pipe 5 connects to the middle light phase area of ​​the third reaction chamber 4. The top of the second reaction chamber 3 connects to the first reaction chamber 2. A second guide pipe 20 is installed at the bottom of the second reaction chamber 3. The diameter of the second guide pipe 20 is smaller than the diameter of the third reaction chamber 4, which increases the flow rate of the reaction liquid. The bottom end of the second guide pipe 20 connects to the third reaction chamber 4. The lower ends of both the first guide pipe 5 and the second guide pipe 20 are connected at a 30-degree angle relative to the surface of the inclined section 22 to drive the internal reaction liquid to rotate. In some embodiments, the lower ends of the first guide tube 5 and the second guide tube 20 can be directly inserted into the inclined section 22, causing the internal reaction liquid to be sprayed out tangentially along the inclined section 22. The resulting product DM has a higher density and tends to precipitate downwards compared to the crude M sodium salt solution. The rotating reaction liquid in the third reaction chamber 4 can move DM to the surroundings under the action of centrifugal force and fall into the settling section 23. The disc-shaped structure formed by the inclined section 22 can serve to gather the light phase. The planar rotation causes the light phase to run to the surroundings under the action of centrifugal force, resulting in a lack or absence of light phase aggregation in the horizontal section. The disc-shaped structure can not only separate the heavy phase by centrifugal force, but also gather the light phase, ensuring that the light phase continues to flow to the lower layer. The settling section 23 is vertically set below the disc-shaped structure, which can reduce the influence of the inclined section 22 on the rotation and centrifugal force of the settling section 23, making the solution in the settling section 23 appear slow or still, which is conducive to the separation of the heavy phase and the light phase.

[0028] A feed pipe 8 is installed at the top of the shell 1. The feed pipe 8 passes through the shell 1 and connects to the first reaction chamber 2. A heavy phase outlet 7 is installed at the bottom of the settling section 23 of the third reaction chamber 4. A light phase outlet 6 is installed at the center of the horizontal section 21 of the bottommost third reaction chamber 4. There are gaps between the first reaction chamber 2, the second reaction chamber 3, and the third reaction chamber 4 and the inner wall of the shell 1. A cold fluid inlet 9 is installed at the top of the shell 1, and a cold fluid outlet 10 is installed at the bottom of the shell 1. That is, all three reaction chambers are enclosed in heat exchange fluid.

[0029] In some embodiments, the space between the stacked third reaction chambers 4 is narrow, making it difficult for the heat exchange fluid to move quickly, which seriously affects the heat exchange effect. A crescent ring 17 is installed on the third reaction chamber 4. The inner ring surface of the crescent ring 17 is sealed to the third reaction chamber 4, and the outer ring surface of the crescent ring 17 is connected to the inner wall of the shell 1. The crescent rings 17 are alternately arranged on the left and right sides of the stacked third reaction chambers 4, that is, a baffle structure similar to a heat exchanger is formed between the crescent rings 17 and the third reaction chambers 4. The crescent rings 17 can guide the heat exchange fluid to make baffle motion to accelerate the heat exchange between the third reaction chambers 4.

[0030] In some embodiments, if a solid catalyst is added during the DM production process, the impact of the solid catalyst on the microchannel reactor needs to be considered. First, the feed pipe 8 is set as a four-way pipe structure. One inlet end of the feed pipe 8 is connected to the crude M sodium salt solution, one inlet end of the feed pipe 8 is connected to hydrogen peroxide, and one inlet end of the feed pipe 8 is connected to the catalyst. The feed pipe 8 plays the role of mixing the reaction raw materials, avoiding the problem of uneven reaction between the second reaction chambers 3 caused by each raw material pipeline being directly connected to the first reaction chamber 2 and thus causing each raw material to be discharged into the second reaction chamber 3 separately.

[0031] A separation pipe 12, a control pipe 13, and a spiral auger 14 are installed on the settling section 23. A motor 15 is installed outside the shell 1. The motor 15 is a servo motor that can precisely control the speed. The upper end of the separation pipe 12 is connected to the middle of the settling section 23. A filter screen is installed at the connection between the separation pipe 12 and the settling section 23 to prevent solid catalyst from entering the separation pipe 12. The heavy phase outlet 7 is connected to the bottom of the separation pipe 12. The spiral auger 14 is located inside the control pipe 13. The motor 15 drives the spiral auger 14 to rotate slowly. The feed end of the control pipe 13 is connected to the bottom of the settling section 23. A discharge pipe 16 is installed at the discharge end of the control pipe 13. The discharge end of the discharge pipe 16 is connected to the inclined section 22 of the third reaction chamber 4 of the next layer. The discharge pipe 16 is installed at the bottom and directly passes through the shell 1 for external discharge. The density of the bulk catalyst is greater than that of DM, which is greater than that of coarse M. In a static state, the solid catalyst is located at the bottom, followed by DM, and the coarse M is at the top. The separation pipe 12 can separate and discharge DM in the middle of the settling section 23. The solid catalyst at the bottom is controlled by the feed control pipe 13. Installing only the feed control pipe 13 can also discharge the upper solid catalyst into the lower layer, but the discharge speed cannot be controlled. The screw conveyor 14 can form a spiral channel. When the inside is filled with solid catalyst, it can provide a large pressure drop and block the feed control pipe 13 to prevent the upper DM or coarse M from flowing into the lower layer. At this time, the screw conveyor 14 acts like a valve to block the flow. At the same time, controlling the motor 15 to rotate slowly can also discharge the solid catalyst to the lower layer, ensuring the stable operation of the equipment.

[0032] A microchannel oxidation method for a vulcanization accelerator includes the following steps:

[0033] S1. The crude sodium salt solution, hydrogen peroxide, and solid catalyst are mixed through the feed pipe 8;

[0034] S2. The mixed reaction solution is discharged into the first reaction chamber 2, the first reaction chamber 2 is temperature controlled to carry out the reaction, and the reaction solution is evenly distributed into the second reaction chamber 3;

[0035] S3. The reaction takes place in the second reaction chamber 3 and the reaction liquid is introduced into the third reaction chamber 4 in a swirling manner;

[0036] S4. The reaction takes place in the third reaction chamber 4 and the product DM is separated into the sedimentation section 23 under centrifugation, while the remaining light phase is separated into the horizontal section 21.

[0037] S5. After the DM in the settling section 23 is discharged into the separation pipe 12, it undergoes secondary settling and is discharged through the heavy phase outlet 7. The light phase solution is discharged through the light phase outlet 6, and the solid catalyst is discharged through the feed control pipe 13.

[0038] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A microchannel oxidation reactor for a sulfidation accelerator, characterized in that: The device includes a shell (1), within which a first reaction chamber (2), a second reaction chamber (3), and a third reaction chamber (4) are arranged sequentially from top to bottom. The first reaction chamber (2) is a thin plate structure, the second reaction chamber (3) is a tubular structure, and the third reaction chamber (4) is a disc structure. A feed pipe (8) is provided on the shell (1), which passes through the shell (1) and connects to the first reaction chamber (2). One end of the second reaction chamber (3) is connected to the first reaction chamber (2), and the bottom end of the second reaction chamber (3) guides the internal solution to flow into the third reaction chamber (4) at a certain angle. The solution inside the third reaction chamber (4) undergoes swirling motion. A light... The light phase outlet (6) and heavy phase outlet (7) are connected to the bottom center of the third reaction chamber (4). The heavy phase outlet (7) is connected to the periphery of the third reaction chamber (4). The first reaction chamber (2), the second reaction chamber (3), and the third reaction chamber (4) are all provided with gaps between themselves and the inner wall of the shell (1). The shell (1) is provided with a cold fluid inlet (9) and a cold fluid outlet (10) to achieve heat exchange. The third reaction chamber (4) has an M-shaped structure. The third reaction chamber (4) includes a horizontal section (21), an inclined section (22), and a settling section (23). The horizontal section (21) is the light phase reaction liquid collection area. The inclined section (22) is the centrifugal separation reaction area. The settling section (23) is the gravity separation area.

2. The microchannel oxidation reactor for a sulfidation accelerator according to claim 1, characterized in that: There are multiple second reaction chambers (3), and each second reaction chamber (3) is provided with an inner heat exchange tube (11). The inner heat exchange tube (11) runs through the second reaction chamber (3) from top to bottom. The two ends of the inner heat exchange tube (11) pass through the second reaction chamber (3) and the shell (1) respectively and are connected to the external heat exchange fluid.

3. The microchannel oxidation reactor for a sulfurization accelerator according to claim 2, characterized in that: The second reaction chamber (3) is provided with multiple outer baffle rings (18) and multiple inner baffle plates (19). The outer baffle rings (18) are connected inside the shell (1), and the inner baffle plates (19) are fixedly connected to the second reaction chamber (3). The multiple outer baffle rings (18) and multiple inner baffle plates (19) are arranged alternately and staggered at intervals. The multiple outer baffle rings (18) and multiple inner baffle plates (19) form a moving fluid that exchanges heat with the second reaction chamber (3) from the outside to the inside and then from the inside to the outside from top to bottom.

4. A microchannel oxidation reactor for a vulcanization accelerator according to any one of claims 1 to 3, characterized in that: The third reaction chambers (4) are multiple and stacked one on top of the other. A first guide pipe (5) is provided between adjacent third reaction chambers (4). The upper end of the first guide pipe (5) is connected to the light phase region in the middle of the third reaction chamber (4), and the lower end of the first guide pipe (5) guides the internal solution to flow into the separation region of the third reaction chamber (4) at a certain angle.

5. The microchannel oxidation reactor for a vulcanization accelerator according to claim 4, characterized in that: A crescent ring (17) is provided on the third reaction chamber (4). The inner ring surface of the crescent ring (17) is sealed to the third reaction chamber (4). The outer ring surface of the crescent ring (17) is connected to the inner wall of the shell (1). The crescent ring (17) is alternately arranged on the left and right sides of the stacked third reaction chamber (4) to guide the heat exchange fluid to make a baffle motion.

6. The microchannel oxidation reactor for a vulcanization accelerator according to claim 5, characterized in that: The settling section (23) is provided with a separation pipe (12), a control pipe (13), and a spiral auger (14). The upper end of the separation pipe (12) is connected to the middle of the settling section (23), the heavy phase outlet (7) is connected to the bottom of the separation pipe (12), the spiral auger (14) is located inside the control pipe (13), the feed end of the control pipe (13) is connected to the bottom of the settling section (23), and the discharge end of the control pipe (13) is connected to the inclined section (22) of the third reaction chamber (4) in the next layer.

7. A microchannel oxidation reactor for a vulcanization accelerator according to claim 6, characterized in that: The bottom end of the second reaction chamber (3) is provided with a second guide pipe (20), the diameter of which is smaller than the diameter of the third reaction chamber (4).

8. The microchannel oxidation reactor for a vulcanization accelerator according to claim 7, characterized in that: The feed pipe (8) has a four-way pipe structure. One inlet end of the feed pipe (8) is connected to a crude M sodium salt solution, one inlet end of the feed pipe (8) is connected to hydrogen peroxide, and one inlet end of the feed pipe (8) is connected to a catalyst.

9. The oxidation method of a microchannel oxidation reactor for a sulfurization accelerator according to claim 8, characterized in that, Includes the following steps, S1. The crude sodium M salt solution, hydrogen peroxide, and catalyst are mixed through the feed pipe (8); S2. The mixed reaction solution is discharged into the first reaction chamber (2), the temperature of the first reaction chamber (2) is controlled to carry out the reaction, and the reaction solution is evenly distributed into the second reaction chamber (3); S3. The second reaction chamber (3) is used for the reaction and the reaction liquid is introduced into the third reaction chamber (4) in a swirling manner. S4. The reaction takes place in the third reaction chamber (4) and the product DM is separated into the sedimentation section (23) under centrifugation, while the remaining light phase is separated into the horizontal section (21); S5. The DM in the settling section (23) is discharged through the heavy phase outlet (7), and the light phase solution is discharged through the light phase outlet (6).

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