Production system and production method of 3-methoxy-N, N-bis (2-ethoxyl) aniline

Abstract

The invention provides a production system and a production method of 3-methoxy-N, N-bis (2-ethoxyl) aniline. According to the production method, functionalized ionic liquid ([HEMIM] HSO4, [HEMIM] H2PO4, [APMIM] HSO4 and [APMIM] H2PO4) and triethylamine are adopted to construct an efficient synergistic catalysis system. Amino (-NH2) or hydroxyl (-OH) of a cation side chain of the ionic liquid is combined with nitrogen atoms of triethylamine through hydrogen bonds, meanwhile, acidic anions (HSO4 <-> / H2PO4 <->) of the ionic liquid and protonated triethylamine ([H-TEA] < + >) generated in the reaction can form strong ion pairs, and the overall stability of a catalytic system is remarkably enhanced through the multiple non-covalent interaction. Compared with traditional acid catalysis or single ionic liquid catalysis, the synergistic catalysis system is high in catalytic activity, excellent in selectivity and high in stability, and the yield and purity of the target product 3-methoxy-N, N-bis (2-ethoxyl) aniline can be remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical synthesis, in particular to a production system and method of 3-methoxy-N,N-di(2-hydroxyethyl)aniline. BACKGROUND

[0002] 3-methoxy-N,N-di(2-hydroxyethyl)aniline (chemical formula C 11 H 17 NO3, molecular weight 211.25) as a derivative of N,N-di(2-hydroxyethyl)aniline, is widely used in the fields of dyes, medicines, organic synthesis, etc., and is an important organic synthesis intermediate.

[0003] At present, the preparation methods of 3-methoxy-N,N-di(2-hydroxyethyl)aniline mainly include the following: (1) 3-methoxyaniline reacts with 2-chloroethanol: 3-methoxyaniline, 2-chloroethanol, calcium carbonate and potassium iodide are added to water and refluxed for 8 h, then cooled and filtered, the filtrate is extracted with ethyl acetate, and the organic phase is dried, concentrated and separated by column chromatography to obtain the product. This method produces a large amount of waste salt water and has a low product yield.

[0004] (2) 3-methoxy nitrobenzene reacts with 2-haloethanol: under a nitrogen atmosphere, a catalyst Co(II), zinc powder, an organic solvent, 3-methoxy nitrobenzene and 2-haloethanol are added to a reaction vessel, and the reaction is carried out at 60-90℃ for 6 h. After the reaction is completed, the mixture is extracted with a mixture of ethyl acetate and distilled water, and the combined organic phase is dried with anhydrous sodium sulfate and separated by column chromatography to obtain the product. This method uses metal catalysts, which causes metal pollution, and the post-treatment operation is complicated and the amount of organic solvent used is large.

[0005] (3) 3-methoxyaniline reacts with ethylene oxide: the amine and ethylene oxide are stirred vigorously in an aqueous acetic acid solution at 20℃ for 24 h, the obtained solution is poured into brine and extracted with ethyl acetate, the organic phase is washed with saturated sodium bicarbonate, dried, distilled, and the obtained oily substance is purified by column chromatography (eluted with ethyl acetate) and crystallized with chloroform / petroleum ether to obtain the product. This method has a long reaction time, complicated operation and low product yield.

[0006] The reaction of 3-methoxyaniline with ethylene oxide is a typical ethoxylation reaction, which is a strong exothermic reaction, and the raw material ethylene oxide is flammable and explosive.

[0007] The common ethoxylation reactors at present include kettle type stirring reactor, Press spray type reactor, Buss reactor, tubular reactor and microchannel reactor.

[0008] Among them, the kettle type stirring reactor is a traditional ethoxylation reactor. Such reactor has low reaction rate, long reaction time, easy explosion and static deflagration, more by-products and small chain growth of product. The Press spray type reactor is strict in requirements for material viscosity and spray uniformity, and is not suitable for ethoxylation reaction of solid with high melting point as starting agent and ethylene oxide. Compared with the Buss reactor ethoxylation process, the reaction rate thereof is relatively slow. The circulating pump of the Buss reactor has high energy consumption and large equipment investment, and is not as widely applied as the Press reactor.

[0009] The tubular reactor is mainly used for continuous production of polyether, and has narrow molecular weight distribution of ethoxylate, good color and low by-product content due to close to ideal plug flow, short residence time and regular material contact time. In addition, the tubular reactor will not produce local overheating of the reactor due to good heat dissipation of the long and thin reaction tube. The built-in static mixer of the tubular reactor can improve the uniformity of residence time distribution, so that the flow in the reactor is closer to plug flow than the empty tube, and the heat transfer efficiency is also greatly increased. Although the tubular reactor is close to ideal plug flow and has narrow residence time distribution, it is difficult to ensure uniform distribution of materials in each pipeline during scale-up production, and the heat transfer capacity per unit volume decreases significantly with the increase of scale.

[0010] Although the micro-channel reactor has extremely high heat and mass transfer efficiency, high viscosity materials or solid impurities can easily block the micro-channel, and the "number increase" strategy needs to be adopted for industrial scale-up, which leads to a significant increase in equipment complexity and cost. The high specific surface area of the micro-channel also leads to a large fluid pressure drop. SUMMARY

[0011] In view of the technical problems in the background art, the present application provides a production system and a production method of 3-methoxy-N,N-di(2-hydroxyethyl)aniline. The production method of the present application adopts a high-efficiency synergistic catalytic system constructed by functional ionic liquid ([HEMIM]HSO4, [HEMIM]H2PO4, [APMIM]HSO4, [APMIM]H2PO4) and triethylamine.

[0012] Specifically, the amino group (-NH2) or hydroxyl group (-OH) on the side chain of the cation of the ionic liquid is combined with the nitrogen atom of triethylamine through hydrogen bond, and the acidic anion (HSO4 - / H2PO4 - ) of the ionic liquid can be combined with the protonated triethylamine ([H-TEA] +The formation of strong ion pairs significantly enhances the overall stability of the catalytic system through multiple non-covalent interactions. In the reaction, the acidic anion activates the oxygen atom of ethylene oxide through proton transfer or hydrogen bonding, significantly lowering the ring-opening energy barrier of the three-membered ring. Triethylamine, as a basic component, establishes a dynamic equilibrium with the amino group of 3-methoxyaniline, generating its highly active activated state in minute quantities, greatly enhancing the nucleophilicity of the nitrogen atom and promoting nucleophilic attack on ethylene oxide. The cationic functional groups (-NH2 / -OH) stabilize reaction intermediates (such as the alkoxy anions generated after ring opening) through hydrogen bonding, optimizing the reaction pathway and lowering the transition state energy. Compared to traditional acid catalysis or single ionic liquid catalysis, this synergistic catalytic system exhibits high catalytic activity, excellent selectivity, and strong stability, significantly improving the yield and purity of the target product, 3-methoxy-N,N-di(2-hydroxyethyl)aniline.

[0013] Furthermore, the catalytic system and the reaction products have a significant density difference, which can be efficiently separated and recovered by simple static stratification (recovery rate ≥96%). The trace catalyst components remaining in the organic phase can be efficiently removed by water washing due to their strong hydrophilicity, which greatly reduces the difficulty of subsequent purification.

[0014] The production system of this application uses an SMR heat exchanger with near-plug flow characteristics, ultra-high heat transfer efficiency, and a design without rotating parts as the core reactor. Its special tube bundle structure enables rapid and uniform mixing of materials and timely and efficient removal of reaction heat, significantly improving the safety and control precision of the strongly exothermic reaction and reducing side reactions caused by local overheating or backmixing.

[0015] In a first aspect, embodiments of this application provide a production system for 3-methoxy-N,N-di(2-hydroxyethyl)aniline, comprising a catalyst premixing vessel, an ethylene oxide storage tank, a primary reactor, a secondary reactor, a reaction liquid cooler, a reaction liquid stratification tank, a soft water tank, a water washing vessel, a water washing liquid stratification tank, a wastewater tank, a dehydration tower, a first suspension crystallization device, and a second suspension crystallization device; the first suspension crystallization device comprises a first scraped crystallizer, a first aging vessel, a first crystal washing tower, a first mother liquor tank, and a first finished product tank; the second suspension crystallization device comprises a second scraped crystallizer, a second aging vessel, a second crystal washing tower, a second mother liquor tank, and a second finished product tank; The outlet of the catalyst premixing vessel is connected to the inlet of the first-stage reactor; The outlet of the ethylene oxide storage tank is connected to the inlet of the first-stage reactor and the second-stage reactor, respectively. The first-stage reactor, the second-stage reactor, the reaction liquid cooler, and the reaction liquid stratification tank are connected sequentially along the material flow direction. The upper layer outlet of the reaction liquid layering tank is communicated with the feed inlet of the water washing kettle, and the lower layer outlet of the reaction liquid layering tank is communicated with the recovered catalyst feed inlet of the catalyst premix kettle; The soft water tank, the water washing kettle and the water washing liquid layering tank are sequentially communicated along the material flow direction. The upper layer outlet of the water washing liquid layering tank is communicated with the feed inlet of the wastewater tank, and the lower layer outlet of the water washing liquid layering tank is communicated with the feed inlet of the dehydration tower. The tower kettle outlet of the dehydration tower is communicated with the feed inlet of the first aging kettle. The first and second crystal washing towers use pure product molten liquid to wash the crystals, the high-purity product obtained by the first suspension crystallization device is discharged out of the system as the final product, part of the obtained mother liquor is used as raw material to enter the second suspension crystallization device to further recover the product, and part of the obtained mother liquor is returned to the system for circulation; the low-purity product obtained by the second suspension crystallization device is used as raw material to enter the first suspension crystallization device for secondary purification, part of the obtained mother liquor is discharged out of the system as the final residual liquid, and part of the obtained mother liquor is returned to the system for circulation.

[0016] Further, the ethylene oxide storage tank is provided with an ethylene oxide feed inlet and a nitrogen feed inlet.

[0017] Further, the first reactor and the second reactor both use SMR heat exchangers as reactors; the SMR heat exchanger includes a plurality of pipe bundles arranged vertically, and the flow characteristics of the SMR heat exchanger are close to ideal plug flow.

[0018] Further, the catalyst premix kettle is provided with a 3-methoxy aniline feed inlet, a triethylamine feed inlet, an ionic liquid feed inlet, a recovered catalyst feed inlet and a nitrogen feed inlet, and the catalyst premix kettle is provided with a stirring member inside.

[0019] Further, the dehydration tower is provided with a condenser and a discharge tank at the top, and the tower kettle of the dehydration tower is provided with a heating device and a material circulating pump for providing the required heat for dehydration.

[0020] Further, the water washing kettle is provided with a reaction crude product feed inlet and a soft water feed inlet, and the water washing kettle is provided with a stirring member inside.

[0021] In a second aspect, the embodiments of the present application provide a production method of 3-methoxy-N,N-di(2-hydroxyethyl)aniline, which uses the aforementioned production system and includes the following steps: S1, continuously adding triethylamine, ionic liquid, 3-methoxy aniline into the catalyst premixing kettle under nitrogen atmosphere, and stirring at room temperature to obtain a mixture; wherein the ionic liquid is at least one selected from 1-hydroxyethyl-3-methylimidazole hydrogen sulfate, 1-hydroxyethyl-3-methylimidazole dihydrogen phosphate, 1-aminopropyl-3-methylimidazole hydrogen sulfate and 1-aminopropyl-3-methylimidazole dihydrogen phosphate; the molar ratio of triethylamine to ionic liquid is (0.6-0.9):1; and the molar ratio of ionic liquid to 3-methoxy aniline is (0.02-0.05):1; S2, continuously adding ethylene oxide into the ethylene oxide storage tank under nitrogen atmosphere, and then continuously inputting the ethylene oxide and the mixture obtained in step S1 into a first reactor to react; when the first reactor effluent is input into a second reactor, ethylene oxide is continuously supplemented into the second reactor to continue the reaction; wherein the reaction temperature of the first reactor is controlled at 50-70°C, and the residence time is controlled at 30-50 min; the reaction temperature of the second reactor is controlled at 80-100°C, and the residence time is controlled at 50-70 min; wherein the molar ratio of total ethylene oxide amount to 3-methoxy aniline is (2-2.1):1; and the molar ratio of ethylene oxide input into the first reactor to ethylene oxide input into the second reactor is (1-1.5):1; S3, the second reactor effluent is cooled to 60-65°C by a reaction liquid cooler, and then is input into a reaction liquid layering tank to stand and layer, the residence time of the material in the reaction liquid layering tank is 30-60 min, the lower layer of catalyst phase is transported to the catalyst premixing kettle for recycling, and the upper layer of oil phase is transported to a water washing kettle; S4, the oil phase obtained in step S3 and soft water from a soft water tank are input into the water washing kettle at a mass ratio of 1:(1-1.5) to stir and wash, and the residence time is 30-60 min at 60-65°C; after washing, the material is input into a water washing liquid layering tank to stand and layer, the residence time of the material in the water washing liquid layering tank is 30-60 min, the lower layer of oil phase is transported to a dehydration tower, and the upper layer of water phase is transported to a wastewater tank; S5, the pressure of the dehydration tower is controlled at -85 to -90 kpa, and the kettle temperature is controlled at 70-80°C, so that the water in the oil phase obtained in step S4 is evaporated from the top of the tower, and the crude product after dehydration is input into a first aging kettle; the water content of the crude product is ≤0.1%; S6, the crude product obtained in step S5 is mixed with the low-purity product returned from the second suspension crystallization device and then enters the first aging kettle for crystallization, the crystal slurry in the first aging kettle is divided into A and B parts and flows out; the crystal slurry A enters the first crystal washing tower for washing and solid-liquid separation, to obtain high-purity product with purity ≥ 99.9% entering the first product tank and first mother liquor entering the first mother liquor tank; the crystal slurry B is cooled to 35-40 DEG C by the first scraped crystalizer and then returns to the first aging kettle; the residence time of the material in the first aging kettle is 6-8h; the first mother liquor in the first mother liquor tank is divided into A and B parts and flows out, the mother liquor A is discharged as raw material to the second aging kettle, and the mother liquor B returns to the outlet pipeline of the first aging kettle, mixes with the crystal slurry B and then enters the first scraped crystalizer to circulate, forming a crystal slurry circulation loop inside the first suspension crystallization device; S7, the mother liquor A discharged from the first suspension crystallization device enters the second aging kettle of the second suspension crystallization device for crystallization, the crystal slurry in the second aging kettle is divided into C and D parts and flows out, the crystal slurry C enters the second crystal washing tower for washing and solid-liquid separation, to obtain low-purity product and second mother liquor entering the second mother liquor tank; the low-purity product enters the second product tank and is then transported as raw material to the first aging kettle; the crystal slurry D is cooled to 20-25 DEG C by the second scraped crystalizer and then returns to the second aging kettle; the residence time of the material in the second aging kettle is 10-12h; the second mother liquor is divided into C and D parts and flows out, the mother liquor C is discharged as final residual liquid to the outside, and the mother liquor D returns to the outlet pipeline of the second aging kettle, mixes with the crystal slurry D and then enters the second scraped crystalizer to circulate, forming a crystal slurry circulation loop inside the second suspension crystallization device.

[0022] Further, in step S3, the recovery rate of the catalyst phase recovered by the layering is ≥ 96%, and the catalyst phase can be directly recycled and used.

[0023] Further, in step S6, the mass ratio of the mother liquor A to the total feed of the first aging kettle is (0.1-0.6):1; the mass ratio of the mother liquor B to the mother liquor A is (0.5-20):1.

[0024] Further, in step S7, the mass ratio of the mother liquor C to the mother liquor A is (0.3-0.6):1; the mass ratio of the mother liquor D to the mother liquor C is (0.2-4.5):1.

[0025] The beneficial effects of the present application are: In the technical scheme of the embodiment of the application, the functional ionic liquid ([HEMIM]HSO4, [HEMIM]H2PO4, [APMIM]HSO4, [APMIM]H2PO4) and triethylamine are used to construct a high-efficiency synergistic catalytic system. The amino group (-NH2) or the hydroxyl group (-OH) of the cation side chain of the ionic liquid is combined with the nitrogen atom of the triethylamine through hydrogen bonding, and meanwhile, the acidic anion (HSO4 - / H2PO4 - ) of the ionic liquid can form a strong ion pair with the protonated triethylamine ([H-TEA]+) generated in the reaction, and the above multiple non-covalent interactions significantly enhance the overall stability of the catalytic system. In the reaction, the acidic anion activates the oxygen atom of the oxirane through proton transfer or hydrogen bonding, significantly reducing the ring-opening energy barrier of the three-membered ring; the triethylamine, as the basic component, establishes a dynamic equilibrium with the amino group of 3-methoxyaniline, and a trace amount but continuous generation of the highly active activated state thereof greatly enhances the nucleophilicity of the nitrogen atom and promotes the nucleophilic attack on the oxirane; the cation functional group (-NH2 / -OH) stabilizes the intermediate (such as the alkoxy anion generated after ring opening) in the reaction through hydrogen bonding, optimizes the reaction path and reduces the transition state energy.

[0026] Compared with the traditional acid catalysis or single ionic liquid catalysis, the synergistic catalytic system has high catalytic activity, excellent selectivity and strong stability, and can significantly improve the yield and purity of the target product 3-methoxy-N,N-di(2-hydroxyethyl)aniline. In addition, there is a significant density difference between the catalytic system and the reaction product, and high-efficiency separation and recovery (recovery rate ≥ 96%) can be realized by simple static layering; due to its strong hydrophilicity, a trace amount of catalyst component remaining in the organic phase can be efficiently removed by water washing, greatly reducing the difficulty of subsequent purification.

[0027] The SMR heat exchanger with the characteristics of close plug flow, ultra-high heat transfer efficiency and no rotating part design is used as the core reactor in the application. The special tube bundle structure realizes rapid and uniform mixing of the material and timely and efficient removal of the reaction heat, significantly improves the safety and control accuracy of the strong exothermic reaction, and reduces the side reactions caused by local overheating or back mixing. It is particularly suitable for the reaction system and potential viscosity changes.

[0028] The suspension crystallization process is used for the final purification of the product in the application. The crystal washing tower uses high-purity product melt liquid for washing, and no organic solvent needs to be introduced, so that high-purity product with a purity of ≥99.9% can be obtained. Compared with the traditional extraction, rectification and solvent recrystallization methods, the process is simplified, the energy consumption is significantly reduced, there is no organic solvent pollution, and the green chemistry concept is met.

[0029] The application innovatively integrates the synergistic catalytic system, the efficient SMR reactor and the green suspension crystallization purification process to form a continuous, efficient, intrinsically safe and environmentally friendly production system. The total yield of the preferred scheme is greater than or equal to 90%, which is suitable for large-scale industrial production and has significant economic and social benefits.

[0030] The above description is only a summary of the technical solutions of the application. In order to enable the technical means of the application to be implemented more clearly according to the content of the specification, and in order to enable the above and other purposes, characteristics and advantages of the application to be more obvious and easy to understand, the following specific embodiments of the application are described. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the application, the drawings used in the application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0032] Fig. 1 The structure schematic diagram of the production system of 3-methoxy-N,N-di(2-hydroxyethyl) aniline provided in the embodiments of the application.

[0033] Fig. 2 The structure schematic diagram of the SMR heat exchanger.

[0034] Legend: 101, catalyst premixing kettle; 102, ethylene oxide storage tank; 103, first stage reactor; 104, second stage reactor; 105, reaction liquid cooler; 106, reaction liquid layering tank; 107, soft water tank; 108, water washing kettle; 109, water washing liquid layering tank; 110, waste water tank; 111, dehydration tower; 112, first aging kettle; 113, first scraped surface crystallizer; 114, first crystal washing tower; 115, first product tank; 116, first mother liquor tank; 117, second aging kettle; 118, second scraped surface crystallizer; 119, second crystal washing tower; 120, second product tank; 121, second mother liquor tank. DETAILED DESCRIPTION

[0035] The embodiments of the technical solutions of the application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the application, and therefore only serve as examples, but cannot limit the protection scope of the application.

[0036] 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 application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the use of the terms "including," "comprising," or "having" and variations thereof herein is intended to be broad and encompass the terms "consisting of" and "consisting essentially of" and variations thereof. Unless otherwise required by context, singular terms shall include pluralities and vice versa. Unless otherwise required by context, the use herein of the singular is also to be construed as a use of the plural and vice versa.

[0037] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified.

[0038] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification is not necessarily all referring to the same embodiment, or to a particular embodiment, or to a particular set of embodiments. It will be explicitly understood by those of ordinary skill in the art that the embodiments described herein can be combined with other embodiments.

[0039] In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two). In the description of the embodiments of the present application, the technical terms "top", "bottom", "upper", "lower", "inner", "horizontal", "transverse", etc. indicate the orientation or positional relationship shown in the drawings, which is only for the purpose of facilitating the description of the embodiments of the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0040] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connecting", "connecting", "fixing", etc. should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0041] Please refer to Figs. 1-2As shown, the application provides a production system of 3-methoxy-N,N-di(2-hydroxyethyl) aniline, which comprises a catalyst premixing kettle 101, an ethylene oxide storage tank 102, a first reactor 103, a second reactor 104, a reaction liquid cooler 105, a reaction liquid layering tank 106, a soft water tank 107, a water washing kettle 108, a water washing liquid layering tank 109, a waste water tank 110, a dehydration tower 111, and a first suspension crystallization device and a second suspension crystallization device.

[0042] The first suspension crystallization device and the second suspension crystallization device each comprise a scraper crystallizer, an aging kettle, a crystal washing tower, a mother liquor tank, and a product tank.

[0043] The scraper crystallizer is composed of multiple tube heat exchangers with built-in scrapers, and can be operated in parallel or in series.

[0044] The aging kettle is operated adiabically, has a built-in stirring element, is provided with a feed inlet and a crystal slurry inlet and outlet, and a part of the crystal slurry in the aging kettle is returned to the scraper crystallizer after being cooled and crystallized, and another part of the crystal slurry is sent to the crystal washing tower for washing and solid-liquid separation.

[0045] The crystal washing tower uses pure product molten liquid to wash the crystals to improve the purity of the crystal product, and the mother liquor outlet is communicated with the mother liquor tank, and the product outlet is communicated with the product tank. Part of the mother liquor in the mother liquor tank is mixed with part of the crystal slurry flowing out of the aging kettle and then returned to the scraper crystallizer for circulation.

[0046] Specifically, the first suspension crystallization device comprises a first scraper crystallizer 113, a first aging kettle 112, a first crystal washing tower 114, a first mother liquor tank 116, and a first product tank 115.

[0047] The second suspension crystallization device comprises a second scraper crystallizer 118, a second aging kettle 117, a second crystal washing tower 119, a second mother liquor tank 121, and a second product tank 120.

[0048] In the application, the high-purity product obtained by the first suspension crystallization device is discharged as the final product, part of the obtained mother liquor is used as raw material to enter the second suspension crystallization device for further recovery of the product, and part of the obtained mother liquor is returned to the system for circulation; the low-purity product obtained by the second suspension crystallization device is used as raw material to enter the first suspension crystallization device for secondary purification, part of the obtained mother liquor is discharged as the final residual liquid, and part of the obtained mother liquor is returned to the system for circulation.

[0049] The catalyst premixing kettle 101 is provided with a 3-methoxyphenylamine feed inlet, a triethylamine feed inlet, an ionic liquid feed inlet, a recovered catalyst feed inlet, and a nitrogen gas feed inlet, and is provided with a stirring element inside and a jacket outside.

[0050] The discharge outlet of the catalyst premixing kettle 101 is communicated with the feed inlet of the first reactor 103.

[0051] The ethylene oxide storage tank 102 is provided with an ethylene oxide feed inlet and a nitrogen feed inlet.

[0052] The outlet of the ethylene oxide storage tank 102 is communicated with the feed inlet of the first-stage reactor 103 and the second-stage reactor 104 respectively.

[0053] The outlet of the first-stage reactor 103 is communicated with the feed inlet of the second-stage reactor 104, and the outlet of the second-stage reactor 104 is communicated with the feed inlet of the reaction liquid cooler 105; the outlet of the reaction liquid cooler 105 is communicated with the feed inlet of the reaction liquid layering tank 106.

[0054] The reaction liquid cooler 105 is a tube heat exchanger or a plate heat exchanger.

[0055] The reaction liquid layering tank 106 and the water washing liquid layering tank 109 are both provided with built-in coalescing separators to realize rapid layering of materials.

[0056] The water washing kettle 108 is provided with a reaction feed inlet (crude product feed inlet) and a soft water feed inlet, and is provided with an agitating member inside and a jacket outside.

[0057] The upper layer outlet of the reaction liquid layering tank 106 is communicated with the feed inlet of the water washing kettle 108, and the lower layer outlet of the reaction liquid layering tank 106 is communicated with the recycled catalyst feed inlet of the catalyst premix kettle 101.

[0058] The soft water tank 107 is provided with corresponding raw material feed inlets and nitrogen feed inlets.

[0059] The outlet of the soft water tank 107 is communicated with the feed inlet of the water washing kettle 108; the outlet of the water washing kettle 108 is communicated with the feed inlet of the water washing liquid layering tank 109; the upper layer outlet of the water washing liquid layering tank 109 is communicated with the feed inlet of the wastewater tank 110, and the lower layer outlet of the water washing liquid layering tank 109 is communicated with the feed inlet of the dehydration tower 111.

[0060] The dehydration tower 111 is provided with a condenser and a discharge tank at the top, the discharge tank is used to store the water evaporated from the top, and the discharge tank is communicated with the wastewater tank 110. The column still of the dehydration tower 111 is provided with a heating device (falling film evaporator) and a material circulating pump to provide the heat required for dehydration.

[0061] The column still outlet of the dehydration tower 111 is communicated with the feed inlet of the first aging kettle 112.

[0062] In the present application, the first-stage reactor 103 and the second-stage reactor 104 both adopt SMR heat exchangers as reactors. The SMR heat exchanger includes a plurality of pipe bundles arranged vertically, such as Fig. 2The SMR heat exchanger has highly filled heat exchange area, which can strengthen the interface radial mixing and heat transfer efficiency; the flow characteristics of the SMR heat exchanger is close to ideal flat flow, and the residence time distribution is extremely narrow. The structure design makes the unit volume heat transfer efficiency much higher than that of the ordinary tubular reactor, can effectively solve the problem of heat removal of strong exothermic reaction, and has small amplification effect. At the same time, the non-rotating part design reduces the risk of failure and static electricity, has high safety, and is suitable for high viscosity materials and systems with potential risk of containing solids.

[0063] Of course, the production system also includes auxiliary equipment for realizing material transfer and parameter control, such as multiple power pumps, regulating valves and control components. The auxiliary equipment is prior art, which will not be described here.

[0064] The application also provides a production method for producing 3-methoxy-N,N-di(2-hydroxyethyl) aniline by using the foregoing production system, comprising the following steps: S1, continuously adding triethylamine, ionic liquid and 3-methoxy aniline into the catalyst premixing kettle 101 under a nitrogen atmosphere, and stirring at room temperature to obtain a mixed solution; wherein the ionic liquid is at least one selected from 1-hydroxyethyl-3-methyl imidazole bisulfate ([HEMIM]HSO4), 1-hydroxyethyl-3-methyl imidazole dihydrogen phosphate ([HEMIM]H2PO4), 1-aminopropyl-3-methyl imidazole bisulfate ([APMIM]HSO4) and 1-aminopropyl-3-methyl imidazole dihydrogen phosphate ([APMIM]H2PO4); the molar ratio of triethylamine to ionic liquid is (0.6-0.9):1; and the molar ratio of ionic liquid to 3-methoxy aniline is (0.02-0.05):1; S2, continuously adding ethylene oxide into the ethylene oxide storage tank 102 under a nitrogen atmosphere, and then continuously inputting the ethylene oxide and the mixed solution obtained in step S1 into a first reactor 103 for reaction; when the first reactor 103 is discharged into a second reactor 104, ethylene oxide is continuously supplemented into the second reactor 104 for continuous reaction; wherein the reaction temperature of the first reactor 103 is controlled at 50-70°C, and the residence time is controlled at 30-50 min; the reaction temperature of the second reactor 104 is controlled at 80-100°C, and the residence time is controlled at 50-70 min; wherein the molar ratio of the total amount of ethylene oxide to 3-methoxy aniline is (2-2.1):1; and the molar ratio of ethylene oxide entering the first reactor to ethylene oxide entering the second reactor is (1-1.5):1.

[0065] S3, the second reactor 104 is cooled to 60-65°C by a reaction liquid cooler, and then the cooled second reactor 104 is discharged into a reaction liquid separation tank 106 for static separation, and the material stays in the reaction liquid separation tank 106 for 30-60 min; the lower layer of catalyst phase is transported to the catalyst premixing kettle 101 for recycling, and the upper layer of oil phase is transported to a water washing kettle 108. The recovery rate of the catalyst phase recovered by layering is greater than or equal to 96%, and the recovered catalyst phase can be directly recycled and used.

[0066] S4, the oil phase obtained in step S3 and soft water from the soft water tank 107 are mixed at a mass ratio of 1:(1-1.5) and then enter the water washing kettle 108 for stirring and water washing, and the material stays in the water washing kettle 108 at 60-65°C for 30-60 min; after the water washing, the material enters the water washing liquid layering tank 109 for layering, and the material stays in the water washing liquid layering tank 109 for 30-60 min, the lower oil phase is transported to the dehydration tower 111, and the upper water phase is transported to the wastewater tank 110; S5, the pressure of the dehydration tower 111 is controlled to be -85 to -90 kPa, and the kettle temperature is 70-80°C, so that the water in the oil phase obtained in step S4 is evaporated from the top of the tower, and the crude product (water content ≤0.1%) after dehydration enters the first aging kettle 112; S6, the crude product obtained in step S5 is mixed with the low-purity product returned from the second suspension crystallization device, and then enters the first aging kettle 112 for crystallization; the crystal slurry in the first aging kettle 112 is divided into two parts A and B; the crystal slurry A enters the first crystal washing tower 114 for washing and solid-liquid separation, to obtain a high-purity product (entering the first product tank 115) with a purity of ≥99.9% and a first mother liquor (entering the first mother liquor tank 116); the crystal slurry B is cooled to 35-40°C by the first scraped surface crystallizer 113 and then returns to the first aging kettle 112; the material stays in the first aging kettle 112 for 6-8 h; the first mother liquor in the first mother liquor tank 116 is divided into two parts A and B, the mother liquor A is discharged as raw material to the second aging kettle 117, and the mother liquor B returns to the outlet pipeline of the first aging kettle 112, mixes with the crystal slurry B, and then enters the first scraped surface crystallizer 113 to form a crystal slurry circulation loop inside the first suspension crystallization device.

[0067] The mass ratio of the mother liquor A to the total feed of the first aging kettle is (0.1-0.6):1, and the mass ratio of the mother liquor B to the mother liquor A is (0.5-20):1.

[0068] S7, the mother liquor A discharged from the first suspension crystallization device enters the second aging kettle 117 of the second suspension crystallization device for crystallization; the crystal slurry in the second aging kettle 117 is divided into two parts C and D, the crystal slurry C enters the second crystal washing tower 119 for washing and solid-liquid separation, to obtain a low-purity product and a second mother liquor entering the second mother liquor tank 121; the low-purity product enters the second product tank 120 and is then transported as raw material to the first aging kettle 112. The crystal slurry D is returned to the second aging kettle 117 after being cooled to 20-25℃ by the second scraped blade crystallizer 118; the residence time of the material in the second aging kettle 117 is 10-12h; the secondary mother liquor is divided into two parts C and D, the mother liquor C is discharged to the outside as the final residual liquid, and the mother liquor D is returned to the outlet pipeline of the second aging kettle 117, mixed with the crystal slurry D, and then enters the second scraped blade crystallizer 118 to form a crystal slurry circulation loop inside the second suspended crystallization device.

[0069] The mass ratio of the mother liquor C to the mother liquor A is (0.3-0.6):1, and the mass ratio of the mother liquor D to the mother liquor C is (0.2-4.5):1.

[0070] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application and cannot be understood as a limitation of the present application.

[0071] Example 1 The present example provides a method for producing 3-methoxy-N,N-di(2-hydroxyethyl)aniline by reacting 3-methoxyaniline with ethylene oxide, which comprises the following steps: S1, under a nitrogen atmosphere, continuously adding triethylamine (15 kg / h, 0.148 kmol / h), 1-hydroxyethyl-3-methylimidazole dihydrogen phosphate ([HEMIM]H2PO4) (40 kg / h, 0.178 kmol / h), and 3-methoxyaniline (500 kg / h, 4.06 kmol / h) into the catalyst premix kettle 101, and stirring at room temperature to obtain a mixed solution.

[0072] The molar ratio of triethylamine to [HEMIM]H2PO4 is 0.829:1, and the molar ratio of [HEMIM]H2PO4 to 3-methoxyaniline is 0.044:1.

[0073] S2, under a nitrogen atmosphere, continuously adding ethylene oxide (365 kg / h, 8.29 kmol / h) into the ethylene oxide storage tank 102. Then, the ethylene oxide and the mixed solution in the catalyst premix kettle 101 are continuously input into the first-stage reactor 103 (SMR heat exchanger) at flow rates of 205 kg / h and 555 kg / h, respectively, for reaction. When the first-stage reactor 103 is discharged into the second-stage reactor 104 (SMR heat exchanger), ethylene oxide is continuously supplemented into the second-stage reactor 104 at a flow rate of 160 kg / h for continuous reaction. The temperature of the first-stage reactor 103 is controlled at 60℃, and the residence time is 50 min. The temperature of the second-stage reactor 104 is controlled at 80℃, and the residence time is 70 min.

[0074] The molar ratio of total ethylene oxide to 3-methoxyaniline is 2.04:1, and the molar ratio of ethylene oxide entering the first reactor 103 to the second reactor 104 is 1.28:1.

[0075] S3, the discharge of the second reactor 104 is cooled to 60°C by the reaction liquid cooler 105 and then enters the reaction liquid layering tank 106 for static layering, and the residence time of the material in the reaction liquid layering tank 106 is 30 min. The lower layer of catalyst phase (about 55 kg / h, containing [HEMIM]H2PO438.4 kg / h, triethylamine 14.4 kg / h, and 2.2 kg / h of entrained crude product, and the recovery rate of effective catalyst components is 96%) is transported to the catalyst premix kettle 101 for reuse.

[0076] At the same time, the triethylamine feed quantity in the catalyst premix kettle 101 is changed to 0.6 kg / h, and the [HEMIM]H2PO4 feed quantity is changed to 1.6 kg / h, which is used to compensate for the 4% loss of total catalyst caused by layering. The upper layer of oil phase is transported to the water washing kettle 108.

[0077] S4, the upper layer of oil phase (about 865 kg / h) and soft water (1000 kg / h) in the soft water tank 107 enter the water washing kettle 108 for stirring and water washing, and the residence time is 30 min at 60°C. After water washing, the material enters the water washing liquid layering tank 109 for static layering, and the residence time of the material in the water washing liquid layering tank 109 is 30 min. The lower layer of oil phase (about 870 kg / h) is transported to the dehydration tower 111, and the upper layer of water phase (about 995 kg / h, containing a small amount of catalyst and target product) is transported to the wastewater tank 110.

[0078] S5, the pressure of the dehydration tower 111 is controlled to be -90 kPa, and the kettle temperature is 80°C, so that the water in the oil phase after water washing is distilled from the top of the tower. The crude product after dehydration (850 kg / h, containing 97.6 wt%, and the moisture content is 0.05 wt%) enters the first aging kettle 112 in the first suspension crystallization device. The molar yield of the crude product calculated based on 3-methoxyaniline is 96.7%.

[0079] S6, the dehydration crude product (850 kg / h, containing 97.6 wt%) is mixed (total amount 930 kg / h) with the low-purity finished product (80 kg / h, containing 97.7 wt%) returned from the second suspension crystallization device to enter the first aging kettle 112 for crystallization. This mixture is the only external feed entering the first suspension crystallization device system.

[0080] The crystal slurry in the first aging kettle 112 is divided into two parts A and B, the crystal slurry A enters the first crystal washing tower 114, and high-purity products (790 kg / h, content 99.92 wt%) and first mother liquor (1190 kg / h, content 84.7 wt%) are separated, the high-purity products enter the first product tank 115, and the first mother liquor enters the first mother liquor tank 116. The crystal slurry B is cooled to 40 DEG C through the first scraped crystalizer 113 and then returns to the first aging kettle 112, and the material stays in the first aging kettle 112 for 7 h.

[0081] The first mother liquor in the first mother liquor tank 116 is divided into two parts A and B, the mother liquor A (140 kg / h, content 84.7 wt%) is discharged as raw material into the second aging kettle 117 in the second suspension crystallization device, and the mother liquor B (1050 kg / h, content 84.7 wt%) returns to the outlet pipeline of the first aging kettle 112, mixes with the crystal slurry B and then enters the first scraped crystalizer 113 for circulation. The mass ratio of the mother liquor B to the mother liquor A is 7.5:1.

[0082] The total molar yield of the high-purity products is 92% based on 3-methoxyaniline. The total molar recovery of the products of the two sets of crystallization devices is 95.1%.

[0083] S7, the mother liquor A from the first suspension crystallization device enters the second aging kettle 117 for crystallization, and the mother liquor A is the only external feed into the second suspension crystallization device system.

[0084] The crystal slurry in the second aging kettle 117 is divided into two parts C and D, the crystal slurry C enters the second crystal washing tower 119, and low-purity products (80 kg / h, content 97.7 wt%) and second mother liquor (186 kg / h, content 67.4 wt%) are separated, the low-purity products enter the second product tank 120, and then are returned as raw material to the first aging kettle 112 in the first suspension crystallization device for secondary purification, and the second mother liquor enters the second mother liquor tank 121.

[0085] The crystal slurry D is cooled to 25 DEG C through the second scraped crystalizer 118 and then returns to the second aging kettle 117. The material stays in the second aging kettle 117 for 10 h. The second mother liquor in the second mother liquor tank 121 is divided into two parts C and D, the mother liquor C (60 kg / h, content 67.4 wt%) is discharged as final residual liquid to the outside, and the mother liquor D (126 kg / h, content 67.4 wt%) returns to the outlet pipeline of the second aging kettle 117, mixes with the crystal slurry D and then enters the second scraped crystalizer 118 for circulation. The mass ratio of the mother liquor D to the mother liquor C is 2.1:1.

[0086] It can be known from the experiment that the catalyst continuously runs for 200 hours, the activity is stable, and the product yield and purity do not decrease.

[0087] The embodiment integrates the "co-catalysis, segmented SMR reaction, double suspension crystallization" process: the co-catalysis system has high activity and can be recycled, the segmented SMR reaction controls the temperature safely, and the double suspension crystallization guarantees high-purity products; the process is continuous and controllable, has no organic solvent, meets the needs of industrialization and green chemical industry, and solves the pain points of traditional processes.

[0088] Comparative Example 1 The present comparative example provides a production method of 3-methoxy-N,N-di(2-hydroxyethyl)aniline, and the main difference compared with Example 1 is that a single [HEMIM]H2PO4 is used as the catalyst, i.e., triethylamine is not used; the specific process is as follows: S1, the amount of [HEMIM]H2PO4 is 40 kg / h (0.178 kmol / h), and the other conditions are the same as those in Example 1.

[0089] S2-S4, the same as S2-S4 in Example 1; S5, the same as S5 in Example 1, and 830 kg / h of dehydrated crude product is obtained, with a content of 89.4wt%, a molar yield of 86.5% based on 3-methoxyaniline.

[0090] S6, the dehydrated crude product (830 kg / h, content 89.4wt%) and the low-purity finished product (351 kg / h, content 97.7wt%) returned from the second suspension crystallization device enter the first aging kettle 112 for crystallization, and the remaining operations are the same as S6 in Example 1.

[0091] After separation by the first crystal washing tower 114, a higher-purity finished product (567 kg / h, content 99.60wt%) and a primary mother liquor (1323 kg / h, content 84.7wt%) are obtained, wherein the mother liquor A is 614 kg / h, and the mother liquor B is 709 kg / h.

[0092] S7, the second suspension crystallization device processes the mother liquor A (614 kg / h, content 84.7wt%), and after separation, a low-purity finished product (351 kg / h, content 97.7wt%) and a secondary mother liquor (819 kg / h, content 67.4wt%) are obtained, wherein the mother liquor C is 263 kg / h, and the mother liquor D is 556 kg / h.

[0093] It can be seen that when only a single [HEMIM]H2PO4 is used as the catalyst, the number of side reactions increases and the selectivity decreases due to the lack of triethylamine to regulate the nucleophilicity of the amino group, thereby reducing the yield and purity of the product. This result indirectly verifies the necessity of the synergistic effect of "triethylamine + ionic liquid".

[0094] Comparative Example 2 This comparative example provides a method for producing 3-methoxy-N,N-bis(2-hydroxyethyl)aniline, which uses a conventional stirred tank reactor and acetic acid as a catalyst; the specific process is as follows: S1, after purging the ethylene oxide storage tank with nitrogen, 88 kg (2 kmol) of ethylene oxide is added; the stirring of the conventional stirred reactor is turned on, and 100 kg (0.812 kmol) of 3-methoxyaniline, 10 kg (0.167 kmol) of acetic acid and 40 kg of soft water are added, and the reactor is purged with nitrogen.

[0095] S2, cool the reactor to 0°C with chilled brine, add ethylene oxide dropwise to the reactor (control the reactor temperature to 0~20°C, add dropwise for 12h); after the addition is complete, age at 20~25°C for 12h to ensure complete reaction; after aging, replace the residual ethylene oxide in the reactor with nitrogen.

[0096] S3, the reaction solution was sent to a distillation vessel (-95 kPa, 100 °C) to remove low-boiling points, yielding 150 kg of crude product (content 96.5 wt%). The molar yield of the crude product, based on 3-methoxyaniline, was 84.4%.

[0097] In step S4, 150 kg of the low-boiling point crude product obtained in step S3, 47 kg of 95% ethanol, and 103 kg of soft water were added to the dissolving vessel and heated to 70°C to dissolve. After cooling to room temperature, the mixture was transferred to a crystallization vessel and cooled to 0°C for 24 hours. The crystals were filtered, centrifuged, pulverized, and dried to obtain 100 kg of high-purity finished product (content 99.63 wt%). The total molar yield of the high-purity finished product, based on 3-methoxyaniline, was 58%. Approximately 200 kg of wastewater containing the target product, impurities, and ethanol was generated.

[0098] It is evident that, compared to the integrated process of "synergistic catalysis + segmented SMR reaction + dual suspension crystallization" in Example 1, the traditional scheme of "conventional stirred tank + acetic acid catalysis + solvent crystallization" in Comparative Example 2 is difficult to meet the requirements of industrialization in terms of reaction efficiency, product yield, environmental friendliness, and economy.

[0099] Comparative Example 3 This comparative example provides a method for producing 3-methoxy-N,N-bis(2-hydroxyethyl)aniline, which uses an SMR heat exchanger as a reactor and acetic acid as a catalyst; the specific process is as follows: S1. Under a nitrogen atmosphere, 3-methoxyaniline (500 kg / h, 4.06 kmol / h), acetic acid (50 kg / h, 0.835 kmol / h), and soft water (200 kg / h) are continuously added to a stirred tank, and the mixture is stirred at room temperature to obtain a mixture.

[0100] S2, same as Example 1S2 (mixture feed rate 750kg / h).

[0101] S3, the effluent from the second-stage reactor is directly fed to a distillation kettle (-95 kPa, 100 °C) to remove low-boiling-point substances, yielding a crude product of 760 kg / h with a content of 96.8 wt%. The molar yield of this crude product, based on 3-methoxyaniline, is 85.8%.

[0102] It is evident that acetic acid, as a single protic acid, can only be produced by donating H+. + Activating ethylene oxide, unlike the synergistic system, fails to regulate the nucleophilicity of the 3-methoxyaniline amino group and stabilize the reaction intermediate, leading to increased side reactions and decreased yield. Therefore, even using the same SMR heat exchanger as Example 1 as the reactor, Comparative Example 3 still exhibits significantly inferior process performance compared to Example 1.

[0103] Comparative Example 4 This comparative example provides a method for producing 3-methoxy-N,N-bis(2-hydroxyethyl)aniline, which, compared with Example 1, changes the molar ratio of the raw materials in step S1; the specific process is as follows: S1, triethylamine (5.1 kg / h, 0.05 kmol / h), [HEMIM]H2PO4 (13.6 kg / h, 0.061 kmol / h), 3-methoxyaniline (500 kg / h, 4.06 kmol / h), the molar ratio of triethylamine to [HEMIM]H2PO4 is 0.829:1; the molar ratio of [HEMIM]H2PO4 to 3-methoxyaniline is 0.015:1, other conditions are the same as in Example 1; S2~S4 are the same as S2~S4 in Example 1.

[0104] S5, the same as S5 in Example 1, yields 840 kg / h of dehydrated crude product with a content of 93.1 wt% and a molar yield of 91.2% based on 3-methoxyaniline.

[0105] S6, the dehydrated crude product (840 kg / h, content 93.1 wt%) and the low-purity finished product (229 kg / h, content 97.7 wt%) returned from the second suspension crystallization unit are fed into the first aging kettle for crystallization. The remaining operations are the same as S6 in Example 1.

[0106] After separation in the first crystal washing tower, a high-purity finished product (668 kg / h, content 99.71 wt%) and a primary mother liquor (1420 kg / h, content 84.7 wt%) were obtained, of which mother liquor A was 401 kg / h and mother liquor B was 1019 kg / h.

[0107] S7, the second suspension crystallization device processes the mother liquor A (401 kg / h, content 84.7 wt%), and low-purity products (229 kg / h, content 97.7 wt%) and secondary mother liquor (487 kg / h, content 67.4 wt%) are obtained through separation, wherein the mother liquor C is 172 kg / h, and the mother liquor D is 315 kg / h.

[0108] Examples 2-3 and Comparative Examples 4-5 Examples 2-3 and Comparative Examples 4-5 provide a production method of 3-methoxy-N,N-di(2-hydroxyethyl)aniline, the main difference being that the molar ratio of the raw materials in step S1 is changed, as shown in Table 1, and the other steps are basically the same as in Example 1, which will not be repeated here.

[0109] Table 1 From the above table, it can be seen that in the production process of 3-methoxy-N,N-di(2-hydroxyethyl)aniline, the molar ratio of triethylamine to [HEMIM]H2PO4 and the molar ratio of [HEMIM]H2PO4 to 3-methoxyaniline need to be controlled within a suitable range to ensure the efficiency of the process.

[0110] In Examples 1-3, the molar ratio of triethylamine to [HEMIM]H2PO4 is in the interval (0.6-0.9):1, and the molar ratio of [HEMIM]H2PO4 to 3-methoxyaniline is in the interval (0.02-0.05):1, the content of the dehydrated crude product is above 95.8%, the molar yield of the dehydrated crude product is above 94.5%, and the content of the high-purity product is not less than 99.90%, which shows that the “triethylamine + [HEMIM]H2PO4” synergistic catalytic system can efficiently promote the reaction and ensure the yield and purity of the product within this ratio interval.

[0111] In Comparative Examples 4-7, the molar ratio of the raw materials exceeds the above-mentioned suitable interval, and the content of the dehydrated crude product, the molar yield of the dehydrated crude product, and the content of the high-purity product are all lower than those of the examples to varying degrees.

[0112] In Comparative Example 4, the molar ratio of [HEMIM]H2PO4 to 3-methoxyaniline is too low, in Comparative Example 5, the ratio is too high, in Comparative Example 6, the molar ratio of triethylamine to [HEMIM]H2PO4 is too low, and in Comparative Example 7, the ratio is too high, all of which result in an imbalance of the synergistic catalytic system, an increase in side reactions, and a decrease in reaction efficiency and product purity.

[0113] It should be noted that experiments show that the ionic liquid can be one or more of 1-hydroxyethyl-3-methylimidazolium hydrogen sulfate ([HEMIM]HSO4), 1-hydroxyethyl-3-methylimidazolium dihydrogen phosphate ([HEMIM]H2PO4), 1-aminopropyl-3-methylimidazolium hydrogen sulfate ([APMIM]HSO4), and 1-aminopropyl-3-methylimidazolium dihydrogen phosphate ([APMIM]H2PO4).

[0114] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration as the technical idea and exerting the same effects within the scope of the technical solution of the present application are all included in the technical scope of the present application. Furthermore, within the scope of the gist of the present application, various modifications that can be thought of by those skilled in the art, other modes constructed by combining part of the configuration elements of the embodiments are also included in the scope of the present application.

Claims

1. A production system for 3-methoxy-N,N-bis(2-hydroxyethyl)aniline, characterized in that, The production system comprises a catalyst premixing kettle, an ethylene oxide storage tank, a first reactor, a second reactor, a reaction liquid cooler, a reaction liquid layering tank, a soft water tank, a water washing kettle, a water washing liquid layering tank, a waste water tank, a dehydration tower, and a first and a second suspension crystallization device. The outlet of the catalyst premixing kettle is connected with the inlet of the first reactor. The outlets of the ethylene oxide storage tank are respectively connected with the inlets of the first and second reactors. The first reactor, the second reactor, the reaction liquid cooler, and the reaction liquid layering tank are sequentially connected in the material flow direction. The upper outlet of the reaction liquid layering tank is connected with the inlet of the water washing kettle, and the lower outlet of the reaction liquid layering tank is connected with the recycled catalyst inlet of the catalyst premixing kettle. The soft water tank, the water washing kettle, and the water washing liquid layering tank are sequentially connected in the material flow direction. The upper outlet of the water washing liquid layering tank is connected with the inlet of the waste water tank, and the lower outlet of the water washing liquid layering tank is connected with the inlet of the dehydration tower. The outlet of the dehydration tower is connected with the inlet of the first aging kettle. The first and second crystal washing towers use pure product melt to wash the crystals. The high-purity product obtained by the first suspension crystallization device is discharged as the final product, and part of the mother liquor is returned to the system for recycling. The low-purity product obtained by the second suspension crystallization device is used as raw material to enter the first suspension crystallization device for secondary purification, and part of the mother liquor is discharged as the final residue.

2. The system for producing 3-methoxy-N,N-di(2-hydroxyethyl)aniline according to claim 1, characterized by The ethylene oxide storage tank is provided with an ethylene oxide inlet and a nitrogen inlet.

3. The system for producing 3-methoxy-N,N-di(2-hydroxyethyl)aniline according to claim 1, characterized by The first and second reactors both use SMR heat exchangers as reactors. The SMR heat exchanger comprises a plurality of pipe bundles arranged vertically, and the flow characteristics of the SMR heat exchanger are close to ideal plug flow.

4. The system for producing 3-methoxy-N,N-di(2-hydroxyethyl)aniline according to claim 1, characterized by The catalyst premixing kettle is provided with a 3-methoxy aniline inlet, a triethylamine inlet, an ionic liquid inlet, a recycled catalyst inlet, and a nitrogen inlet, and the inside of the catalyst premixing kettle is provided with a stirring part.

5. The system for producing 3-methoxy-N,N-di(2-hydroxyethyl)aniline according to claim 1, characterized by The dehydration tower is provided with a condenser and an outlet tank at the top, and a heating device and a material circulating pump at the tower bottom, for providing the heat required for dehydration.

6. The system for producing 3-methoxy-N,N-di(2-hydroxyethyl)aniline according to claim 1, characterized by The water washing kettle is provided with a reaction crude product inlet and a soft water inlet, and the inside of the water washing kettle is provided with a stirring part.

7. A method for producing 3-methoxy-N,N-di(2-hydroxyethyl)aniline, characterized by: The production system of any one of claims 1-6 comprises the following steps: S1, under a nitrogen atmosphere, continuously adding triethylamine, ionic liquid, 3-methoxy aniline into the catalyst premixing kettle, stirring at room temperature to obtain a mixture; wherein the ionic liquid is selected from at least one of 1-hydroxyethyl-3-methylimidazolium hydrogen sulfate, 1-hydroxyethyl-3-methylimidazolium dihydrogen phosphate, 1-aminopropyl-3-methylimidazolium hydrogen sulfate, 1-aminopropyl-3-methylimidazolium dihydrogen phosphate; the molar ratio of triethylamine to ionic liquid is (0.6-0.9):1; the molar ratio of ionic liquid to 3-methoxy aniline is (0.02-0.05):1; S2, under a nitrogen atmosphere, continuously adding ethylene oxide into the ethylene oxide storage tank, and then continuously inputting the ethylene oxide and the mixture obtained in step S1 into a first reactor to react; when the first reactor effluent is input into a second reactor, ethylene oxide is continuously supplemented into the second reactor to continue the reaction; wherein the reaction temperature of the first reactor is controlled at 50-70℃, and the residence time is controlled at 30-50min; the reaction temperature of the second reactor is controlled at 80-100℃, and the residence time is controlled at 50-70min; wherein the molar ratio of total ethylene oxide amount to 3-methoxy aniline is (2-2.1):1; the molar ratio of ethylene oxide entering the first reactor to ethylene oxide entering the second reactor is (1-1.5):1; S3, the second reactor effluent is cooled to 60-65℃ by a reaction liquid cooler, and then is input into a reaction liquid layering tank to stand and layer, the residence time of the material in the reaction liquid layering tank is 30-60min, the lower layer of catalyst phase is transported to the catalyst premixing kettle for recycling, and the upper layer of oil phase is transported to a water washing kettle; S4, the oil phase obtained in step S3 and soft water from a soft water tank are input into the water washing kettle at a mass ratio of 1:(1-1.5) to stir and wash, and the residence time is 30-60min at 60-65℃; after washing, the material is input into a water washing liquid layering tank to stand and layer, the residence time of the material in the water washing liquid layering tank is 30-60min, the lower layer of oil phase is transported to a dehydration tower, and the upper layer of water phase is transported to a wastewater tank; S5, the pressure of the dehydration tower is controlled at -85--90kpa, and the kettle temperature is controlled at 70-80℃, so that the water in the oil phase obtained in step S4 is evaporated from the top of the tower, and the crude product after dehydration is input into a first aging kettle; the water content of the crude product is ≤0.1%. S6, the crude product obtained in step S5 is mixed with the low-purity product returned from the second suspension crystallization device and then enters the first aging kettle for crystallization, and the crystal slurry in the first aging kettle is divided into two parts A and B; the crystal slurry A enters the first crystal washing tower for washing and solid-liquid separation, to obtain high-purity product with purity ≥ 99.9% entering the first product tank and first mother liquor entering the first mother liquor tank; the crystal slurry B is cooled to 35-40℃ by the first scraped crystalizer and then returns to the first aging kettle; the residence time of the material in the first aging kettle is 6-8h; the first mother liquor in the first mother liquor tank is divided into two parts A and B, the mother liquor A is discharged as raw material to the second aging kettle, and the mother liquor B returns to the outlet pipeline of the first aging kettle, mixes with the crystal slurry B and then enters the first scraped crystalizer to form a crystal slurry circulation loop inside the first suspension crystallization device; S7, the mother liquor A discharged from the first suspension crystallization device enters the second aging kettle of the second suspension crystallization device for crystallization, and the crystal slurry in the second aging kettle is divided into two parts C and D, the crystal slurry C enters the second crystal washing tower for washing and solid-liquid separation, to obtain low-purity product and second mother liquor entering the second mother liquor tank; the low-purity product enters the second product tank and is then transported as raw material to the first aging kettle; the crystal slurry D is cooled to 20-25℃ by the second scraped crystalizer and then returns to the second aging kettle; the residence time of the material in the second aging kettle is 10-12h; the second mother liquor is divided into two parts C and D, the mother liquor C is discharged as final residual liquid to the outside, and the mother liquor D returns to the outlet pipeline of the second aging kettle, mixes with the crystal slurry D and then enters the second scraped crystalizer to form a crystal slurry circulation loop inside the second suspension crystallization device.

8. The method for producing 3-methoxy-N,N-di(2-hydroxyethyl)aniline according to claim 7, characterized by, In step S3, the recovery rate of the catalyst phase recovered by layering is ≥ 96%, and it can be directly recycled and used.

9. The method of producing 3-methoxy-N,N-di(2-hydroxyethyl)aniline according to claim 7, characterized by, In step S6, the mass ratio of the mother liquor A to the total feed of the first aging kettle is (0.1-0.6):1; the mass ratio of the mother liquor B to the mother liquor A is (0.5-20):

1.

10. The method for producing 3-methoxy-N,N-di(2-hydroxyethyl)aniline according to claim 7, characterized by, In step S7, the mass ratio of the mother liquor C to the mother liquor A is (0.3-0.6):1; the mass ratio of the mother liquor D to the mother liquor C is (0.2-4.5):1.

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