Multi-stage fixed bed reactor and its application
By combining a multi-stage fixed-bed reactor with a static mixer, the problems of excessively high local concentration of isobutylene and inaccurate temperature control in a single-stage reactor were solved, achieving efficient, stable and continuous production of 2,4-di-tert-butylphenol and improving product selectivity and catalyst life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- EAST CHINA UNIV OF SCI & TECH
- Filing Date
- 2026-04-27
- Publication Date
- 2026-07-21
AI Technical Summary
In the prior art, when producing 2,4-di-tert-butylphenol, the local concentration of isobutylene is too high in the early stage of the reaction, which easily leads to the generation of multiple alkylation byproducts. In the later stage, the reaction rate decreases, and the exothermic alkylation reaction is difficult to control the temperature precisely, which affects the product selectivity and catalyst life.
A multi-stage fixed-bed reactor is adopted, and segmented precise feeding and mixing are achieved by setting up static mixers with insulated shell sides between adjacent sections. Combined with segmented temperature control of the tubular reactor, the raw materials are ensured to be uniformly mixed and the temperature is stable.
This method enables efficient, stable, and continuous production of 2,4-di-tert-butylphenol, improving raw material conversion rate and target product selectivity while reducing side reactions.
Smart Images
Figure CN122076328B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of chemical process production equipment, and more specifically, to a multi-stage fixed-bed reactor and its application in the continuous production of 2,4-di-tert-butylphenol. Background Technology
[0002] 2,4-Di-tert-butylphenol is an important chemical raw material and intermediate, playing a crucial role in multiple industrial sectors. It can be used as an antioxidant additive in aviation gasoline and as a stabilizer for natural and synthetic rubber. Simultaneously, this compound effectively improves the thermal stability of polyolefins and polystyrene and is widely used in the production of coatings, adhesives, and pesticides. In the field of polymer additives, 2,4-di-tert-butylphenol is a key intermediate raw material for the synthesis of antioxidant 168 and ultraviolet absorbers UV-326 and UV-327. With continuous technological advancements, the demand for 2,4-di-tert-butylphenol in domestic and international markets is steadily increasing.
[0003] Currently, the production of 2,4-di-tert-butylphenol both domestically and internationally mainly employs the batch process. However, this method has many drawbacks, such as long production cycles, high material exposure risks, and significant safety hazards. Moreover, it involves high labor intensity for workers, complex material transfer operations, and even with energy-saving and emission-reduction measures, the improvement effects are not entirely satisfactory, posing challenges to safe production, quality control, and comprehensive resource utilization.
[0004] Compared to batch processes, continuous processes can achieve a continuous supply of reactants and a continuous output of products, ensuring the stability and consistency of process operation. CN116496145A provides a method for producing 2,4-di-tert-butylphenol, which involves passing a feedstock containing phenol and tert-butanol or isobutylene through a reactor containing a solid acid catalyst bed to produce 2,4-di-tert-butylphenol. However, this method uses a single-stage fixed-bed reactor, with all feedstocks entering at once. This can easily lead to excessively high local concentrations of isobutylene in the early stages of the reaction, resulting in the formation of multiple alkylation byproducts, and a decrease in the reaction rate in the later stages. Simultaneously, the exothermic alkylation reaction is difficult to precisely control the temperature, and local overheating of the bed can easily occur, affecting product selectivity and catalyst lifetime. Therefore, it is necessary to provide an improved reactor for the continuous production of 2,4-di-tert-butylphenol to solve the above problems. Summary of the Invention
[0005] To address the aforementioned problems in existing technologies, this invention proposes a multi-stage fixed-bed reactor and its application. This reactor employs multiple reaction units connected in series, with static mixers featuring insulated shell sides between stages for feeding and mixing, and uses a tubular reactor as the reaction unit. This invention achieves precise segmented feeding and forced mixing between stages, while also enabling precise segmented temperature control, effectively suppressing side reactions and improving feed conversion rate and target product selectivity.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] In a first aspect, the present invention provides a multi-stage fixed-bed reactor, the fixed-bed reactor comprising a plurality of reaction units arranged in series in a vertical direction, and a static mixer disposed between adjacent reaction units;
[0008] The reaction unit includes a reactor and a redistributor located above the reactor;
[0009] The static mixer has a mixing component inside, and an insulating shell is provided outside the mixing component; each static mixer has a corresponding raw material supply pipe; the inlet of the static mixer is connected to the outlet of the reactor of the previous reaction unit and the raw material supply pipe, and the outlet of the static mixer is connected to the redistributor of the next reaction unit.
[0010] Furthermore, the mixing components within the static mixer include a first spherical material distributor, a conical funnel, a mixing tube section, and a second spherical material distributor connected sequentially from top to bottom; it also includes a baffle disposed at the lower part of the mixing tube section;
[0011] The inlet of the first spherical material distributor is connected to the outlet of the reactor and the raw material supply pipe of the previous reaction unit;
[0012] The outlet of the second spherical material distributor is connected to the redistributor of the next stage reaction unit;
[0013] The outer conical funnel and mixing pipe section of the static mixer form an insulating shell between itself and the upper part of the baffle, and the insulating shell is used to introduce the insulating medium.
[0014] Furthermore, the reactor is a tubular reactor, with the catalyst built into the tube side and the heat exchange medium introduced into the shell side; the height-to-diameter ratio of the reactor is 0.5:1 to 5:1, and the tube diameter is 6 mm to 100 mm.
[0015] Furthermore, the bottom of the redistributor is provided with several small holes, the diameter of which is 2mm to 50mm; the height-to-diameter ratio of the redistributor is 0.2:1 to 2:1.
[0016] Furthermore, the upper and lower ends of the mixing pipe section are respectively connected to a conical funnel and a second spherical material distributor, and the mixing pipe section has built-in spiral blades.
[0017] Furthermore, both the first and second spherical material distributors are provided with a plurality of openings, the size of which is 2mm to 50mm; the shape of which is circular, square or irregular.
[0018] Furthermore, a primary mixer is provided at the top of the fixed-bed reactor for pre-mixing the initial raw materials; and a discharge port is provided at the bottom of the fixed-bed reactor for discharging the reaction products.
[0019] Secondly, the present invention provides an application of the above-mentioned multi-stage fixed-bed reactor for the continuous production of 2,4-di-tert-butylphenol using phenol and isobutylene as raw materials, comprising the following steps: initially, phenol and isobutylene are mixed and then enter a redistributor above the first stage reactor, and after uniform distribution, they enter the reactor for alkylation reaction; the reactor discharge enters a static mixer below, and is mixed with supplemented isobutylene and kept at a constant temperature, and then enters the next stage reactor to continue the reaction; the process of supplementing feed and reaction is repeated, and after multiple stages of reaction, the reaction product is drawn out from the final stage reactor.
[0020] Furthermore, the insulation temperature of the static mixer is 50℃~135℃.
[0021] Furthermore, the reaction temperature of each reactor section is independently controlled between 50℃ and 150℃; the working pressure of each reactor section is independently controlled between 0.1MPa and 2MPa.
[0022] Compared with the prior art, the present invention has the following beneficial effects:
[0023] This invention provides a simple, efficient, and continuous multi-stage fixed-bed reactor for the production of 2,4-di-tert-butylphenol. By installing a static mixer with an insulated shell between adjacent stages, the feedstock is forcibly and uniformly mixed with the output from the previous stage reactor, and the insulated shell maintains the mixing temperature to ensure stable output. Simultaneously, a tubular reactor is used for independent temperature control in each stage. After each stage reactor discharges, feed is automatically replenished, mixed, and kept warm before being redistributed to the next stage reactor, ensuring thorough mixing and uniform distribution of the feedstock. The equipment is simple to operate and enables efficient and stable continuous production of 2,4-di-tert-butylphenol. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the structure of the multi-stage fixed-bed reactor of the present invention.
[0025] Figure 2 yes Figure 1 A magnified view of a portion of the image.
[0026] In the picture:
[0027] 10-Reactor; 11-Reactor shell-side inlet; 12-Reactor shell-side outlet; 20-Redistributor; 30-Static mixer; 31-First spherical material distributor; 32-Conical funnel; 33-Mixing section; 34-Second spherical material distributor; 35-Baffle; 36-Raw material replenishment pipe; 37-Static mixer shell-side inlet; 38-Static mixer shell-side outlet; 40-Primary mixer. Detailed Implementation
[0028] 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 a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in this application without creative effort are within the scope of protection of this application.
[0029] like Figure 1 and Figure 2 As shown, the present invention provides a multi-stage fixed-bed reactor, the fixed-bed reactor comprising several reaction units arranged in series in a vertical direction, and a static mixer 30 disposed between adjacent reaction units;
[0030] The reaction unit includes a reactor 10 and a redistributor 20 located above the reactor 10; the reaction unit has two or more sections, which are selected according to actual production needs.
[0031] The reactor 10 is a tubular reactor with a catalyst embedded in the tubes. The shell side of the reactor has a shell-side inlet 11 and a shell-side outlet 12 for introducing a heat exchange medium. This tubular structure effectively increases the contact area between the material and the catalyst, allowing for sufficient heat exchange and ensuring stable reaction temperature.
[0032] The static mixer 30 is used for inter-stage feeding, which can realize the precise addition and heat preservation of raw materials in stages, effectively avoid local over- or under-production of raw materials and unstable output, and improve reaction selectivity and stability.
[0033] The static mixer 30 has a mixing component inside, and an insulating shell is provided outside the mixing component. The mixing component includes a first spherical material distributor 31, a conical funnel 32, a mixing pipe section 33, and a second spherical material distributor 34 connected sequentially from top to bottom; it also includes a baffle 35 disposed at the lower part of the mixing pipe section; each static mixer 30 is provided with a corresponding raw material replenishment pipe 36;
[0034] The inlet of the first spherical material distributor 31 is connected to the outlet of the reactor 10 of the previous reaction unit and the raw material supply pipe 36; the outlet of the second spherical material distributor 34 is connected to the redistributor 20 of the next reaction unit.
[0035] The first spherical material distributor 31 is used to rapidly mix the raw materials added in stages with the output of the previous reactor 10. The conical funnel 32 mixes the materials before they enter the mixing tube section 33, reducing uneven mixing caused by material dispersion and improving the mixing effect. The mixing tube section 33 has built-in spiral blades to ensure uniform material composition.
[0036] The conical funnel 32 of the static mixer 30, the outer part of the mixing tube section 33, and the upper part of the baffle 35 form an insulated shell side to maintain stable discharge. The insulated shell side is provided with a static mixer shell side inlet 37 and a static mixer shell side outlet 38 for introducing the insulated medium. The insulated medium introduced into the reactor 10 and the static mixer 30 can be water, steam, heat transfer oil, molten salt, or an organic carrier.
[0037] The first spherical material distributor 31 and the second spherical material distributor 34 are each provided with a plurality of openings, the size of which is 2mm to 50mm; the shape of which is circular, square or irregular.
[0038] Furthermore, the height-to-diameter ratio of the reactor 10 is between 0.5:1 and 5:1. In the reactor 10, the diameter and length of the tubes can be flexibly varied according to actual production volume and process requirements; preferably, the tube diameter is 6mm to 100mm. The tube diameter or length of each section of the reactor 10 can be the same or different, allowing for differentiated design based on requirements.
[0039] The catalyst loaded in the tubes of each reactor section 10 is a commonly used catalyst in the field. Molecular sieve catalysts, resin catalysts or solid acid catalysts can be selected, and the specific selection can be flexibly made according to the reaction selectivity requirements, catalyst life and production cost.
[0040] The bottom of the redistributor 20 is provided with several small holes for uniformly distributing the material from the previous unit into the reactor 10 below. The diameter of the small holes is 2mm to 50mm, which can be flexibly adjusted according to the material flow rate and viscosity. The height-to-diameter ratio of the redistributor 20 is 0.2 / 1 to 2 / 1, which can ensure uniform distribution of the liquid and avoid material retention and accumulation, thereby reducing the occurrence of side reactions.
[0041] Furthermore, a primary mixer 40 is provided at the top of the fixed-bed reactor for pre-mixing the initial raw materials; and a discharge port is provided at the bottom of the fixed-bed reactor for discharging the reaction products.
[0042] The following describes in detail the process of continuously producing 2,4-di-tert-butylphenol from phenol and isobutylene using this reactor, taking a three-stage reaction unit as an example. The specific steps are as follows:
[0043] (1) The initial raw materials (phenol and isobutylene) are mixed evenly by the top primary mixer 40, which effectively avoids local reaction abnormalities caused by uneven initial feed components. The mixed raw materials directly enter the redistributor 20 of the first stage. After being evenly distributed by the redistributor 20, they enter the tubes of the reactor 10 of the first stage, fully contact the catalyst in the tubes and undergo alkylation reaction.
[0044] (2) The material discharged from the reactor 10 of the first stage enters the static mixer 30 below it, and at the same time, isobutylene is added to the static mixer 30 through the raw material replenishment pipe 36 of this stage; the insulation medium is introduced into the insulation shell of the static mixer 30 to keep the material warm and maintain the material temperature stable; the added isobutylene and the material discharged from the first stage are fully mixed in the static mixer 30 to ensure that the isobutylene is evenly dispersed in the material and to avoid local excess of isobutylene; the material after being evenly mixed enters the redistributor 20 of the second stage, and after being evenly distributed, it enters the reactor 10 of the second stage to participate in the reaction.
[0045] (3) The discharge from the second stage reactor 10 enters the static mixer 30 below it. Isobutylene is added to the static mixer 30 through the raw material replenishment pipe 36 of this stage. At the same time, the insulation shell side is continuously kept warm to stabilize the material temperature. After the isobutylene is fully mixed with the discharge from the second stage, it reaches the redistributor 20 of the third stage reactor. After being evenly distributed, it enters the third stage reactor 10 to continue the reaction, so that the raw material is fully converted and the product purity is ensured. After the reaction is completed, the product is drawn out from the bottom discharge port of the reactor 10 and enters the subsequent separation process.
[0046] Furthermore, the temperature of each reactor 10 can be flexibly adjusted according to the reaction requirements of each stage, with the reaction temperature controlled between 50 and 150°C; the working pressure of each reactor 10 is typically controlled between 0.1 and 2 MPa. The insulation temperature of the static mixer 30 is 50°C to 135°C.
[0047] Example 1:
[0048] This embodiment uses the aforementioned multi-stage fixed-bed reactor (eight-stage reactor) to produce 2,4-di-tert-butylphenol. The phenol feed flow rate is 40.9 kg / h, the isobutylene feed rate for each stage is 6.09 kg / h, the phenol to isobutylene feed molar ratio is 4, and the reactor tube diameter is 32 mm. The operating temperature of each stage reactor is 80°C, the operating pressure is 1 MPa, and a cationic resin catalyst is used. The static mixer is kept at 80°C.
[0049] The catalyst loading in the first reactor is 2.3 kg, in the second reactor it is 3.1 kg, in the third reactor it is 4.6 kg, in the fourth reactor it is 6.8 kg, in the fifth reactor it is 11 kg, in the sixth reactor it is 19.8 kg, in the seventh reactor it is 45.3 kg, and in the eighth reactor it is 174 kg.
[0050] After passing through an 8-stage reactor, the isobutylene conversion rate reached 99%, and the molar fraction of 2,4-di-tert-butylphenol in the product composition reached 97.03%.
[0051] Example 2:
[0052] This embodiment uses the aforementioned multi-stage fixed-bed reactor (six-stage reactor) to produce 2,4-di-tert-butylphenol. The phenol feed flow rate is 55.4 kg / h, the isobutylene feed rate for each stage is 11 kg / h, the phenol to isobutylene feed molar ratio is 3, and the reactor tube diameter is 25 mm. The operating temperature of each stage reactor is 85°C, the operating pressure is 1.05 MPa, and a cationic resin catalyst is used. The static mixer is kept at 85°C.
[0053] The catalyst loading in the first reactor is 3.35 kg, in the second reactor it is 4.79 kg, in the third reactor it is 8.13 kg, in the fourth reactor it is 15.3 kg, in the fifth reactor it is 36.8 kg, and in the sixth reactor it is 159.5 kg.
[0054] After passing through a six-stage reactor, the isobutylene conversion rate reached 98.98%, and the molar fraction of 2,4-di-tert-butylphenol in the product composition reached 96.26%.
[0055] Example 3:
[0056] This embodiment uses the aforementioned multi-stage fixed-bed reactor (seven-stage reactor) to produce 2,4-di-tert-butylphenol. The phenol feed flow rate is 54 kg / h, the isobutylene feed rate for each stage is 8.05 kg / h, the phenol to isobutylene feed molar ratio is 4, and the reactor tube diameter is 25 mm. The operating temperature of each stage reactor is 90°C, the operating pressure is 1.1 MPa, and a cationic resin catalyst is used. The static mixer is kept at 90°C.
[0057] The catalyst loading in the first reactor is 2.6 kg, in the second reactor it is 3.35 kg, in the third reactor it is 4.8 kg, in the fourth reactor it is 7.65 kg, in the fifth reactor it is 13.9 kg, in the sixth reactor it is 33.5 kg, and in the seventh reactor it is 114.8 kg.
[0058] After passing through a seven-stage reactor, the isobutylene conversion rate reached 98.95%, and the molar fraction of 2,4-di-tert-butylphenol in the product composition reached 95.38%.
[0059] Example 4:
[0060] This embodiment uses the aforementioned multi-stage fixed-bed reactor (four-stage reactor) to produce 2,4-di-tert-butylphenol. The phenol feed flow rate is 10.8 T / h, the isobutylene feed rate for each stage is 1.6 T / h, the phenol to isobutylene feed molar ratio is 4, and the reactor tube diameter is 32 mm. The operating temperature of each stage reactor is 80℃, the operating pressure is 1.2 MPa, and a cationic resin catalyst is used. The static mixer is kept at 80℃.
[0061] The catalyst loading in the first reactor is 520 kg, in the second reactor it is 67 kg, in the third reactor it is 960 kg, and in the fourth reactor it is 1530 kg.
[0062] After passing through four reactors, the isobutylene conversion rate reached 99%, and the molar fraction of 2,4-di-tert-butylphenol in the product composition reached 72%.
[0063] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A multi-stage fixed-bed reactor, characterized in that, The fixed-bed reactor includes several reaction units arranged in series in a vertical direction, and a static mixer disposed between adjacent reaction units; The reaction unit includes a reactor and a redistributor located above the reactor; The static mixer has a mixing component inside, and an insulation shell is provided outside the mixing component; each static mixer has a corresponding raw material supply pipe; the inlet of the static mixer is connected to the outlet of the reactor of the previous reaction unit and the raw material supply pipe, and the outlet of the static mixer is connected to the redistributor of the next reaction unit. The mixing components within the static mixer include, from top to bottom, a first spherical material distributor, a conical funnel, a mixing tube section, and a second spherical material distributor; it also includes a baffle plate disposed at the lower part of the mixing tube section; The inlet of the first spherical material distributor is connected to the outlet of the reactor and the raw material supply pipe of the previous reaction unit; The outlet of the second spherical material distributor is connected to the redistributor of the next stage reaction unit; The outer conical funnel and mixing pipe section of the static mixer form an insulating shell between itself and the upper part of the baffle, and the insulating shell is used to introduce the insulating medium.
2. The multi-stage fixed-bed reactor according to claim 1, characterized in that, The reactor is a tubular reactor, with a catalyst built into the tube side and a heat exchange medium introduced into the shell side; the height-to-diameter ratio of the reactor is 0.5:1 to 5:1, and the tube diameter is 6 mm to 100 mm.
3. The multi-stage fixed-bed reactor according to claim 1, characterized in that, The bottom of the redistributor is provided with several small holes, the diameter of which is 2mm to 50mm; the height-to-diameter ratio of the redistributor is 0.2:1 to 2:
1.
4. The multi-stage fixed-bed reactor according to claim 1, characterized in that, The upper and lower ends of the mixing pipe section are respectively connected to a conical funnel and a second spherical material distributor, and the mixing pipe section has built-in spiral blades.
5. The multi-stage fixed-bed reactor according to claim 1, characterized in that, Both the first and second spherical material distributors are provided with a number of openings, the size of which is 2mm to 50mm; the shape of the openings is circular, square or irregular.
6. The multi-stage fixed-bed reactor according to claim 1, characterized in that, The fixed-bed reactor is equipped with a primary mixer at the top to pre-mix the initial raw materials thoroughly; and a discharge port at the bottom of the fixed-bed reactor to discharge the reaction products.
7. An application of the multi-stage fixed-bed reactor according to any one of claims 1 to 6, characterized in that, The method for continuously producing 2,4-di-tert-butylphenol from phenol and isobutylene includes the following steps: initial phenol and isobutylene are mixed and then enter a redistributor above the first stage reactor. After uniform distribution, the mixture enters the reactor for alkylation reaction. The reactor discharge enters a static mixer below and is mixed with supplemented isobutylene and kept at a constant temperature. Then, it enters the next stage reactor to continue the reaction. The process of supplementing feed and reaction is repeated. After multiple stages of reaction, the reaction product is drawn out from the final stage reactor.
8. The application according to claim 7, characterized in that, The insulation temperature of the static mixer is 50℃~135℃.
9. The application according to claim 7, characterized in that, The reaction temperature of each reactor section is independently controlled between 50℃ and 150℃; the working pressure of each reactor section is independently controlled between 0.1MPa and 2MPa.