Continuous production method and device of styrene oxide

Abstract

The invention discloses a continuous production method and device of styrene oxide based on series connection of a microchannel and a tank reactor. Styrene and peroxide are used as reaction raw materials, a catalyst and a polymerization inhibitor are added, and continuous production is realized through a'one-stage microchannel reactor + n-stage tank reactor 'series device. The micro-channel reactor rapidly completes a main reaction by utilizing efficient mass and heat transfer characteristics and inhibits generation of by-products; the tank reactor thoroughly decomposes the residual oxidizing agent through supplementing the polymerization inhibitor and heating operation, and is especially suitable for a system taking tert-butyl hydroperoxide as an oxidizing agent. The problem of high oxidant residue in a single-stage microreactor is solved; and multi-stage microreactors are connected in series, so that the cost is high and blockage is easy. Compared with a traditional tank reactor production process, the method has the advantages that the reaction time can be shortened to 2 hours, and the conversion rate gt of tert-butyl hydroperoxide is realized; the selectivity of styrene oxide is gt; and the method has no self-polymerization risk and is suitable for industrial high-efficiency production.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology, specifically relating to a method for efficiently preparing styrene oxide using a microchannel reactor and a batch reactor connected in series, which is particularly suitable for the oxidation reaction system of styrene and tert-butyl hydrogen peroxide. Background Technology

[0002] Styrene oxide (1,2-epoxyethylbenzene), as a high-value-added fine chemical intermediate, possesses both reactive epoxy groups and benzene rings in its molecular structure, exhibiting rich chemical reactivity and serving as a core platform compound for the synthesis of various high-value chemicals. With the continuous expansion and deepening of downstream applications, its global market demand is showing steady growth, placing higher demands on the efficiency, safety, and economy of production processes. However, the current mainstream batch reactor production process faces many insurmountable technical bottlenecks, while emerging microreactor technology also encounters significant obstacles in addressing the specific challenges of this system. Therefore, developing an efficient, safe, low-cost, and scalable continuous production process has become an urgent priority to meet the rapidly developing needs of downstream industries.

[0003] The epoxy groups in styrene oxide molecules can participate in the curing reaction of resins, becoming part of the cross-linking network. This allows it to effectively reduce the initial viscosity of high-viscosity epoxy resin systems and significantly improve processing flowability (such as potting, impregnation, and spraying), making it a highly efficient reactive diluent. Compared to inactive diluents (such as plasticizers), styrene oxide improves processability while minimizing negative impacts on the final mechanical properties (strength, modulus, heat resistance), chemical resistance, and electrical insulation of the cured resin, and can even optimize toughness. It is now widely used in wind turbine blade composites, electronic encapsulation adhesives, high-performance coatings, and adhesives, and is crucial for achieving complex structure manufacturing and performance improvement. Secondly, styrene oxide is also a key precursor for the synthesis of β-phenylethanol. Under mild conditions (acidic catalysts, such as water or alcohol), it can undergo a selective ring-opening reaction to produce β-phenylethanol (2-phenylethanol, PEA) in high yield. PEA is one of the most in-demand synthetic fragrance monomers globally, widely used in perfumes, cosmetics, toiletries, and soap fragrances. In the field of new energy materials, styrene oxide undergoes a cycloaddition reaction with carbon dioxide under the action of a catalyst to efficiently synthesize styrene carbonate. Styrene carbonate is one of the key additives in the electrolytes of next-generation high-performance lithium-ion batteries (especially power batteries and energy storage batteries). Its main mechanism of action is to preferentially decompose on the surface of the negative electrode (mainly graphite) before solvent molecules, forming a stable, dense solid electrolyte interphase (SEI) film with high ionic conductivity. Benefiting from the explosive growth of the global new energy vehicle industry and the rapid expansion of the electrochemical energy storage market, the demand in the lithium battery industry chain has surged. The strong demand from these three major application areas, especially the sharp increase in demand for styrene carbonate in the new energy sector, has placed higher demands on the production scale, supply stability, cost control, and product quality consistency of styrene oxide. Traditional batch processes can no longer meet this continuously growing and demanding market requirement.

[0004] Currently, large-scale global SO production primarily relies on the traditional batch / semi-batch stirred tank reactor (BSTR) process. This process typically involves the epoxidation of styrene with organic peroxides (most commonly tert-butyl hydroperoxide, TBHP) in the presence of a catalyst (such as a complex of molybdenum, titanium, or tungsten). Although this process is relatively mature, its inherent drawbacks are becoming increasingly apparent under the demands of large-scale production and modern industry. First, the reaction time for a single batch is typically as long as 3 to 5 hours, including a slow feeding phase, a lengthy reaction sustaining phase, and a necessary heat preservation phase. This long reaction time directly leads to low equipment utilization and low space-time yield, limiting the rapid increase in overall capacity. Second, the epoxidation reaction is a strongly exothermic reaction. The limited surface area of ​​large reactors makes heat removal difficult. Uneven material mixing easily leads to the formation of localized high-temperature "hot spots" at the feeding point or in highly active areas. Meanwhile, high-temperature "hot spots" can induce styrene free radical polymerization, generating tar-like polystyrene byproducts. This not only consumes expensive raw material styrene and reduces the selectivity of the main reaction, but also severely pollutes the reaction system, adhering to the reactor walls and agitators, reducing heat transfer efficiency, increasing reactor cleaning frequency, and increasing waste disposal costs. Furthermore, high temperatures and excessively high local peroxide concentrations can cause the generated styrene oxide to undergo ring-opening or further oxidation, generating benzaldehyde and small amounts of impurities such as benzoic acid and phenylacetaldehyde. These impurities increase the difficulty and cost of subsequent separation and purification. Limited by these side reactions, even with optimized operation, the selectivity of industrial batch processes for styrene oxide is typically only 90-93%. This means that 7-10% of the raw material is converted into low-value or payable byproducts. In terms of production operations, batch operations involve frequent feeding, discharging, and cleaning steps, increasing the risk of human error and leakage. Single batch capacity is usually limited to less than 1 ton to control exothermic risks. Expanding the scale of a single reactor faces geometric scaling challenges, with significant scaling-up effects and dramatically increased risks.

[0005] Microreactor technology, as a revolutionary process intensification device, is based on the use of a network of precise channels at the micrometer to millimeter scale to confine the reaction fluid and achieve continuous flow operation. Its specific surface area is typically higher than 10,000 m². 2 / m 3The flow rate is 2-3 orders of magnitude higher than that of traditional reactors. The fluid within the microchannels is predominantly laminar, with extremely short diffusion distances and highly efficient intermolecular contact, enabling instantaneous, molecular-scale homogeneous mixing of reactants. This is particularly beneficial for fast reactions and mass-transfer-controlled reactions. The enormous specific surface area and extremely thin microchannel walls allow heat to be removed instantaneously, efficiently, and uniformly by the heat exchange medium. Macroscopic temperature gradients are virtually eliminated, achieving a near-isothermal reaction environment. Furthermore, the extremely small liquid holdup (microliters to milliliters) means that even in the event of violent reactions or runaway reactions, the energy contained within the system is extremely limited, significantly reducing safety risks. The continuous flow mode facilitates automated, precise control, which is beneficial for obtaining products with high selectivity and reproducibility.

[0006] However, applying microreactor technology to styrene epoxidation systems also presents some challenges. In single-stage microreactors, even with optimized reaction conditions (temperature, pressure, catalyst concentration, residence time), the conversion rate of tert-butyl hydroperoxide typically struggles to exceed the 85% upper limit during styrene epoxidation. Unconverted oxidant flows out of the microreactor with the reaction liquid, entering downstream collection tanks, intermediate storage tanks, or being directly separated and purified. Tert-butyl hydroperoxide is a thermally unstable and highly oxidizing organic peroxide. During subsequent heating (e.g., distillation), concentration, and storage, the residual oxidant readily decomposes, generating large amounts of oxygen and releasing heat. This poses a significant risk of thermal decomposition, pressure buildup, and even explosion. From an intrinsic safety perspective, residual highly reactive oxidant is an unacceptable major hazard in continuous processes. The most direct technical solution to improve the overall conversion rate of tert-butyl hydroperoxide is to connect multiple microreactor units in series, extending the total residence time to bring the reaction closer to complete. It is important to note that although temperature control within the microreactor is excellent, the self-polymerization of styrene is an intrinsic side reaction that is difficult to completely eliminate. The resulting polystyrene may have a low molecular weight and may exist as a viscous oil or oligomer, making it highly susceptible to adhesion, deposition, and accumulation on the channel walls and in subsequent pipes and heat exchangers, causing channel blockage. Cleaning complex microreactor modules is difficult and time-consuming, specialized cleaning agents are expensive, maintenance is extensive, and frequent cleaning and physical unblocking may damage the delicate microchannel structure.

[0007] Therefore, a novel continuous process for the production of styrene oxide needs to be developed and industrialized. The technical solution must simultaneously meet the following core requirements: 1. Intrinsically safe: eliminating or strictly controlling the risk of residual organic peroxides to ensure safe operation throughout the entire process from reaction to separation; 2. Highly efficient and stable: achieving near 100% oxidant conversion rate and high selectivity (>95%), significantly inhibiting styrene self-polymerization and deep oxidation of styrene oxide, and ensuring long-term continuous and stable operation; 3. Economically feasible: equipment investment and operation and maintenance costs must be controlled at a competitive level, and the overall production cost should be significantly lower than or at least comparable to the optimized batch process; 4. Easy to scale up: the technical solution must have good engineering scale-up potential, enabling large-scale production of tens of thousands of tons or more; 5. Green and environmentally friendly: reducing by-product waste (especially tar), lowering separation and purification difficulty and energy consumption, and improving atom economy. Summary of the Invention

[0008] This invention aims to resolve three contradictions existing in the production of styrene oxide:

[0009] (1) The contradiction between the high efficiency of microreactors and the risk of clogging;

[0010] (2) The contradiction between complete conversion of the oxidant and reaction selectivity;

[0011] (3) The contradiction between continuous production and equipment costs.

[0012] The purpose of this invention is to provide a high-efficiency, low-consumption, and safe continuous styrene oxidation production method. By connecting a microchannel reactor and a batch reactor in series and controlling the parameters in stages, the core objectives of complete oxidant consumption, inhibition of self-polymerization, and improved selectivity are achieved by combining the technical advantages of both.

[0013] To achieve the objectives of this invention, the technical solution is as follows:

[0014] A continuous production method for styrene oxide uses styrene and an oxidant as reactants, preferably peroxides, and adds a catalyst and a polymerization inhibitor. The reaction is carried out continuously through a microchannel reactor and a batch reactor connected in series. The series device includes a first-stage microchannel reactor and 1-3 stages of batch reactors.

[0015] In this invention, the microchannel reactor is used to rapidly initiate the main reaction, enhance mass and heat transfer, and suppress self-polymerization side reactions. The batch reactor receives the discharge from the microchannel reactor, completing the deep conversion and reducing oxidant residue. The microchannel reactor is responsible for completing more than 85% of the main reaction within the first 10 minutes, while the batch reactor provides sufficient residence time to decompose residual TBHP to <1%.

[0016] Preferably, there are two batch reactors.

[0017] As a preferred embodiment, the microchannel reactor has a reaction volume of 40-60 mL, a coil inner diameter of 0.5-2 mm, and is made of silicon carbide or polytetrafluoroethylene. The batch reactor has a volume of 0.5-2 L and is made of borosilicate glass.

[0018] More preferably, the microchannel reactor has a volume of 60 mL, the inner diameter of the coil is 1 mm, and the material is silicon carbide; the batch reactor has a volume of 1 L and is made of borosilicate glass.

[0019] As a preferred embodiment, a microchannel-stage reactor synergistic reaction system is employed, and the method includes the following steps:

[0020] a. The raw materials are mixed in a mass ratio of styrene: oxidant: catalyst: polymerization inhibitor = 1000:(250-550):(0.03-0.08):(2-8), and fed into a microchannel reactor and reacted at 55-75℃ for 5-30 minutes.

[0021] b. Input the material from the microchannel reactor into the batch reactor, add the polymerization inhibitor, and react for 20-120 minutes at 80-90℃, preferably 200-500 rpm with stirring.

[0022] In this invention, the mass ratio of styrene, oxidant, catalyst, and polymerization inhibitor in step a is based on chemical substances. The oxidant, catalyst, and polymerization inhibitor are all added in solution form. Preferably, the concentration of the oxidant solution ranges from 45-60 wt%, and the solvent is one or more of tert-butanol, n-decane, and isododecane. The concentration of the catalyst solution ranges from 1-10 wt%, and the solvent is one or more of acetonitrile, benzene, toluene, and tert-butanol. The concentration of the polymerization inhibitor solution ranges from 10-25 wt%, and the solvent is one or both of styrene and tert-butanol.

[0023] More preferably, the oxidant in step a is tert-butyl hydroperoxide (TBHP). More preferably, the mass ratio of styrene to TBHP includes, but is not limited to, 1000:300, 1000:320, 1000:350, 1000:370, 1000:400, 1000:420, 1000:450, 1000:470, 1000:500, 1000:520, 1000:540, or any combination thereof.

[0024] As a preferred embodiment, the catalyst is MoO3 or an ammonium molybdate-acetylacetone complex. The mass ratio of styrene to the catalyst is within the range of 1000:0.04, 1000:0.05, 1000:0.06, 1000:0.07, or any combination thereof.

[0025] More preferably, the catalyst is MoO3, and the mass ratio of styrene to MoO3 is 1000:0.03.

[0026] As a preferred embodiment, the polymerization inhibitor comprises one or more of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, methylhydroquinone, p-benzoquinone, 4,6-dinitro-o-sec-butylphenol, p-tert-butylcatechol, hydroquinone, and p-hydroxyanisole. In step a, the mass ratio of styrene to the polymerization inhibitor is 1000:3, 1000:3.5, 1000:4, 1000:4.5, 1000:5, 1000:5.5, 1000:6, 1000:6.5, 1000:7, 1000:7.5, or any combination thereof. More preferably, the polymerization inhibitor is bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and the mass ratio of styrene to bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate is 1000:4.8.

[0027] As a preferred approach, a gradient control strategy for the polymerization inhibitor is adopted. In step b, the amount of polymerization inhibitor added is based on the amount of styrene added as raw material, and is 0.1-0.5% of the mass of styrene, including but not limited to 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or any combination thereof, and more preferably 0.2%.

[0028] As a preferred embodiment, the microchannel reactor is equipped with a multi-segment temperature control module and employs a temperature gradient control strategy. The inlet zone temperature is 55-65℃, including but not limited to 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, or any combination thereof; the reaction zone temperature is 65-75℃, including but not limited to 66℃, 67℃, 68℃, 69℃, 70℃, 71℃, 72℃, 73℃, 74℃, or any combination thereof.

[0029] As a preferred option, the cascaded batch reactors are of the continuous overflow type, with online concentration monitors installed between stages to adjust the residence time in real time.

[0030] As a preferred option, step b includes an oxidant residue warning system that automatically extends the residence time by 10-20 minutes when the concentration of oxidant in the reaction solution exceeds 2.0%.

[0031] The reaction apparatus of this invention includes a microchannel reactor with multiple temperature control modules connected in series, and a series of 1-3 stage batch reactors, preferably batch reactors with mechanical stirring and jacketed temperature control. After initial mixing, the raw materials are fed into the microchannel reactor to complete the initial, rapid, or exothermic steps of the reaction. The material flowing out of the microchannel reactor enters the multi-stage batch reactor to decompose residual TBHP to <1%.

[0032] Compared with the prior art, the method and apparatus of the present invention have the following advantages:

[0033] 1. The present invention adopts a synergistic reaction design, in which the microreactor quickly completes the main reaction and the batch reactor ensures the reaction endpoint, avoiding the high cost and clogging risk of multi-stage microreactors, and improving conversion rate and selectivity;

[0034] 2. Compared with the traditional batch reactor production process, the present invention can shorten the reaction time to 2 hours, achieve a tert-butyl hydrogen peroxide conversion rate of >94% and a styrene oxide selectivity of >98%, and has no risk of self-polymerization, making it suitable for efficient industrial production;

[0035] 3. The preferred scheme adopts a dynamic control strategy, combining segmented temperature control with gradient feeding to further improve conversion rate and selectivity. Attached Figure Description

[0036] Figure 1 These are schematic diagrams of the reaction apparatus structures of Embodiments 1, 2, 3, 4, and 5 of this application.

[0037] Figure 2 This is a schematic diagram of the reaction apparatus of Comparative Example 1 of this application. Detailed Implementation

[0038] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Locational terms such as top and bottom, mentioned or possibly used in this specification, are defined relative to the constructions shown in the accompanying drawings; they are relative concepts and may therefore vary depending on their location and usage.

[0040] Sample analysis was performed using an Agilent-7890B gas chromatograph with a DB-5 30×0.32×0.25 column, an FID detector, N2 as the carrier gas, a flow rate of 1.5 mL / min, a vaporization chamber temperature of 260℃, and a detector temperature of 300℃. A temperature program was used, starting at 50℃ and holding for 2 min, then increasing to 80℃ at 5℃ / min, and finally increasing to 280℃ at 15℃ / min and holding for 10 min. Qualitative analysis of the components was performed using retention values, and quantitative analysis was performed using the peak area method with mesitylene as an internal standard. The TBHP content in the samples was determined by iodometric titration (GB / T601-2016).

[0041] Example 1

[0042] The microchannel reactor is made of reactive silicon carbide (SiC, purity >99.5%), employing a serpentine flow channel design (total length 15.3m), with an inner diameter of 2.0±0.05mm and an effective volume of 45mL. The entire microchannel reactor consists of five plates: the first plate is the inlet zone, with a temperature set at 65℃±1℃; plates 2-5 form the reaction zone, with a temperature set at 75℃±1℃. Two 1L borosilicate glass reactors are equipped with stirring systems using 80mm diameter inclined blade turbine impellers at a speed of 300rpm; a heat transfer oil jacket circulation system is used, with temperature control at 90±1℃; and the residence time is controlled by the overflow pipe height difference.

[0043] like Figure 1 As shown, the raw materials were prepared into a mixed solution with a mass ratio of styrene:TBHP:MoO3:bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate = 1000:420:0.03:4.8. TBHP was a 55 wt% tert-butanol solution, MoO3 was a 10 wt% acetonitrile solution, and bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate was a 20 wt% tert-butanol solution. The mixture was then fed into reactor R1 at a static mixer at a rate of 0.8 mL / min, with a total residence time of 20 minutes. The effluent from R1 was fed into the first batch reactor R2-1, with a polymerization inhibitor dosage of 0.2% of the styrene feed amount. The reaction was carried out at 90°C for 50 minutes. The overflow was then fed into the second batch reactor R2-2, where the reaction was carried out at 90°C for 50 minutes. The final reaction solution showed a TBHP outlet concentration of 0.98%, a conversion rate of 96.4%, and a styrene oxidation selectivity of 99.3%. After 100 hours of continuous operation, the microchannel pressure drop increased by only 2.1% (initial value 0.15 MPa), and no polymer coking occurred in the batch reactor (verified by visual inspection and weighing).

[0044] Example 2

[0045] The apparatus of Example 1 was maintained. The raw materials were prepared into a solution with a mass ratio of styrene:TBHP:MoO3:polymer inhibitor = 1000:250:0.04:2. The copolymer inhibitor was a mixture of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate and hydroquinone in a 1:1 ratio. Specifically, TBHP was a 55 wt% tert-butanol solution, MoO3 was a 10 wt% acetonitrile solution, and the copolymer inhibitor was a 10 wt% styrene solution. The microchannel reactor temperature was adjusted to 55°C in the inlet zone and 70°C in the reaction zone; the temperature inside the batch reactor was reduced to 80°C; the amount of copolymer inhibitor added when R1 exited into the first batch reactor was 0.5% of the styrene feed amount. Other parameters not mentioned remained unchanged. The final result showed a TBHP conversion rate of 94.6% and a styrene oxide selectivity of 98.8% in the reaction solution.

[0046] Example 3

[0047] Maintaining the apparatus of Example 1, the raw materials were prepared into a mixed solution in R1 at a mass ratio of styrene:TBHP:MoO3:bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate = 1000:550:0.08:8, and the total residence time was 30 minutes. Similarly, TBHP was prepared using a 55 wt% tert-butanol solution, MoO3 using a 10 wt% acetonitrile solution, and bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate using a 20 wt% tert-butanol solution. When the material from R1 was discharged into R2-1, the polymerization inhibitor dosage was increased to 0.15% of the styrene feed amount, and the reaction was carried out at 90°C for 50 minutes; overflow was then discharged into R2-2, and the reaction was carried out at 90°C for 40 minutes. The rotation speed was set to 500 rpm, and all other parameters not mentioned were left unchanged. The sample analysis method was the same as in Example 1. The final reaction solution showed a TBHP conversion rate of 95.2% and a styrene oxide selectivity of 99.1%.

[0048] Example 4

[0049] The apparatus of Example 1 was maintained. A mixed solution of styrene, TBHP, MoO3, and bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate was prepared at a mass ratio of 1000:550:0.08:8 and fed into R1. The total residence time was 30 minutes. TBHP was a 55 wt% tert-butanol solution, MoO3 was a 10 wt% acetonitrile solution, and bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate was a 20 wt% tert-butanol solution. When the material from R1 was discharged into R2-1, the polymerization inhibitor dosage was 0.15% of the styrene feed amount. The reaction was carried out at 90°C for 50 minutes; the overflow was then transferred to the second batch reactor and reacted at 90°C for 40 minutes. The rotation speed was set to 500 rpm, and the temperature of all five plates in the microchannel reactor was set to 75°C. No segmented temperature control was used. All other parameters not mentioned were not changed. The sample analysis method was the same as in Example 1. The final reaction solution showed a TBHP conversion rate of 94.2% and a styrene oxide selectivity of 98.2%.

[0050] Example 5

[0051] The apparatus of Example 1 was maintained. A mixed solution of styrene, TBHP, MoO3, and bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate was prepared at a mass ratio of 1000:420:0.03:4.8 and fed into R1. The total residence time was 20 minutes. TBHP was prepared using a 55 wt% tert-butanol solution, MoO3 using a 10 wt% acetonitrile solution, and bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate using a 20 wt% tert-butanol solution. The product from R1 was fed into R2-1 and reacted at 90°C for 50 minutes without additional polymerization inhibitor. Overflow was then fed into R2-2 and reacted at 90°C for 50 minutes. All other parameters not mentioned were unchanged, and the sample analysis method was the same as in Example 1. The final reaction solution showed a TBHP conversion rate of 95.6% and a styrene oxide selectivity of 98.6%.

[0052] Comparative Example 1

[0053] like Figure 2As shown, only two batch reactors were used, with the same reactor configuration as in Example 1. The reaction temperature was 90°C, the rotation speed was set to 300 rpm, and the residence time was 90 minutes. A mixed solution was prepared according to the mass ratio of styrene:TBHP:MoO3:bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate = 1000:420:0.03:4.8, where TBHP was a 55 wt% tert-butanol solution, MoO3 was a 10 wt% acetonitrile solution, and bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate was a 20 wt% tert-butanol solution. The TBHP outlet concentration was 3.18%, which is higher than the safety threshold, posing a safety risk, and at this point, the selectivity for styrene oxidation was only 88.4%.

[0054] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A continuous production method for styrene oxide, characterized in that: Styrene and an oxidant are used as reactants, preferably peroxides, and a catalyst and a polymerization inhibitor are added. The reaction is carried out continuously through a microchannel reactor and a batch reactor connected in series. The series device includes a first-stage microchannel reactor and 1-3 stages of batch reactors.

2. The method according to claim 1, characterized in that: The microchannel reactor has a reaction volume of 40-60 mL, a coil inner diameter of 0.5-2 mm, and is made of silicon carbide or polytetrafluoroethylene; and / or, the batch reactor has a volume of 0.5-2 L and is made of borosilicate glass.

3. The method according to claim 1 or 2, comprising the following steps: a. The raw materials are mixed in a mass ratio of styrene: oxidant: catalyst: polymerization inhibitor = 1000:(250-550):(0.03-0.08):(2-8), and fed into a microchannel reactor for reaction, preferably at 55-75°C for 5-30 minutes; b. Input the material from the microchannel reactor into the batch reactor, add polymerization inhibitor, preferably based on the amount of styrene added, which is 0.1-0.5% of the styrene mass; react for 20-120 minutes at 80-90℃, preferably with stirring at 200-500 rpm.

4. The method according to any one of claims 1-3, characterized in that: The oxidant is tert-butyl hydroperoxide (TBHP), and the mass ratio of styrene to TBHP is 1000:400-450.

5. The method according to any one of claims 1-4, characterized in that: The catalyst is MoO3 or an ammonium molybdate-acetylacetone complex; preferably, the catalyst is MoO3, and the mass ratio of styrene to MoO3 is 1000:0.03-0.

05.

6. The method according to any one of claims 1-5, characterized in that: The polymerization inhibitor comprises one or more of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, methyl hydroquinone, p-benzoquinone, 4,6-dinitro-o-sec-butylphenol, p-tert-butylcatechol, hydroquinone, and p-hydroxyanisole; preferably, the polymerization inhibitor is bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and the mass ratio of styrene to bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate is 1000:3-5.

7. The method according to any one of claims 1-6, characterized in that: The microchannel reactor is equipped with a multi-segment temperature control module, with the inlet zone temperature at 55-65℃ and the reaction zone temperature at 65-75℃.

8. The method according to any one of claims 1-7, characterized in that: The cascaded batch reactors are continuous overflow reactors, with online concentration monitors installed between stages to adjust the residence time in real time.

9. The method according to any one of claims 1-8, characterized in that: In step b, an oxidant residue early warning system is set up. When the concentration of oxidant in the reaction solution is higher than 2.0%, the residence time is automatically extended by 10-20 minutes.

10. An apparatus for implementing the method according to any one of claims 1-9, characterized in that: It includes a microchannel reactor with multiple temperature control modules connected in sequence and a series of 1-3 stage batch reactors with mechanical stirring and jacket temperature control.

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