An energy-saving and environmentally friendly method and system for producing 2-ethylanthraquinone

Abstract

This application provides an energy-saving and environmentally friendly method and system for producing 2-ethylanthraquinone. This method achieves zero sodium sulfate wastewater generation, waste acid recycling rate of over 80%, chlorobenzene recovery rate of over 98%, stable BE acid yield of over 90%, 2-ethylanthraquinone yield of over 80%, and product purity of ≥99.5%. Compared with traditional processes, production efficiency is increased by 35%, total energy consumption is reduced by 30%, and raw material costs are reduced by 25%, demonstrating significant environmental, energy-saving, and economic value.

Description

Technical Field

[0001] This invention belongs to the field of anthraquinone production technology, and relates to an energy-saving and environmentally friendly method and system for producing 2-ethylanthraquinone. Background Technology

[0002] Anthraquinones are compounds whose basic core is anthraquinone. They belong to the category of fused-ring organic compounds and are important intermediates in fine chemicals. 2-Ethylanthraquinone is a core catalyst for the production of hydrogen peroxide, and there is huge market demand for it.

[0003] In traditional anthraquinone production processes, after the acylation reaction, sodium hydroxide extraction is required to obtain the intermediate benzoic acid, which is then purified by sulfuric acid precipitation. This process generates large amounts of sodium sulfate wastewater and high-concentration industrial waste acid, making wastewater treatment difficult and costly, and easily causing water and soil pollution. Simultaneously, the cyclization process uses constant-temperature heating, resulting in poor reaction selectivity, low anthraquinone yield, and high consumption of fuming sulfuric acid, leading to high waste acid emissions and significant resource waste. Furthermore, in traditional processes, the intermediate 2-(4'-ethylbenzoyl)benzoic acid (BE acid) needs to be crystallized before proceeding to the next step, a cumbersome process with low production efficiency, and prone to intermediate loss, reducing product yield.

[0004] While existing technologies have made some attempts to improve anthraquinone production processes, these efforts mostly focus on optimizing single steps and lack a holistic environmental and energy-saving design. Furthermore, there is no precise solution for controlling the temperature rise during the cyclization process, making it impossible to simultaneously increase yield and reduce waste acid. The core environmental and efficiency issues of traditional processes remain unresolved. Therefore, developing an anthraquinone production process that controls pollution at the source, achieves full-process resource utilization, high yield, and low energy consumption has become a pressing technical challenge for the industry. Summary of the Invention

[0005] The purpose of this invention is to provide an energy-saving and environmentally friendly method and system for producing 2-ethylanthraquinone, in order to solve the problem of serious pollution caused by existing production methods.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, this application provides an energy-saving and environmentally friendly method for producing 2-ethylanthraquinone, the method comprising: After mixing ethylbenzene, anhydrous aluminum trichloride and chlorobenzene, phthalic anhydride was slowly added dropwise, and the reaction was kept at 45-50℃ for 4-5 hours to obtain an acylated solution. The acylation solution was slowly added dropwise to dilute hydrochloric acid at 5-10℃, and the hydrolysis reaction was carried out at 30-35℃ for 2-3 hours to obtain the hydrolysis reaction solution. The hydrolysis reaction solution was allowed to stand and separate, washed until the pH of the aqueous phase was 6-7, dried until the water content was ≤0.1%, and filtered to obtain a dry BE acid mother liquor. The BE acid mother liquor was distilled under reduced pressure to obtain a BE acid intermediate slurry. Add fuming acid at 10-15℃ to the BE acid intermediate slurry, and carry out a cyclization reaction under staged heating and stirring rate of 200-300r / min to obtain a cyclized liquid; The cyclized liquid was slowly dripped into cold water at 5-10°C. After crystallization, washing, and filtration, crude 2-ethylanthraquinone was obtained. The crude 2-ethylanthraquinone was vacuum distilled at a vacuum of -0.095 to -0.098 MPa and a temperature of 220-230 °C, and then condensed to obtain 2-ethylanthraquinone.

[0007] Secondly, this application provides an energy-saving and environmentally friendly 2-ethylanthraquinone production system, the system comprising an acylation vessel, a hydrolysis vessel, a separating tank, a chlorobenzene tank, a drying vessel, a cyclization vessel, a crystallization vessel, and a distillation vessel connected in series; the separating tank is connected in series to a waste liquid tank and an extraction tower, and the extraction tower is connected to the chlorobenzene tank.

[0008] The present invention has the following beneficial effects: (1) Significant environmental benefits: ① The sodium hydroxide extraction and sulfuric acid precipitation steps in the acylation process are eliminated, fundamentally avoiding the generation of large amounts of sodium sulfate wastewater and solving the core water pollution problem of traditional processes; ② The water phase is used to prepare flocculants, the inorganic phase is used to recover aluminum trichloride, and the distillation residue is used as fuel, realizing the resource utilization and energy utilization of solid waste and wastewater, with no ineffective discharge; ③ Waste sulfuric acid is recycled and reused in the cyclization process after extraction and concentration, reducing waste acid discharge by more than 80% and solving the waste acid pollution problem of traditional processes; ④ Solvents chlorobenzene, extractants, and desiccants are all recycled and reused, greatly improving resource utilization and reducing waste discharge of chemical raw materials.

[0009] (2) Significant energy saving and consumption reduction: ① The use of vacuum distillation to remove chlorobenzene reduces the distillation temperature and saves about 30% of heating energy consumption; ② The condensate and heating heat transfer oil are all in circulation system, and the heat recovery heat exchanger is matched to realize the recovery and utilization of process waste heat, reducing the total energy consumption by more than 25%; ③ There is no additional organic solvent recrystallization step in the whole process, which reduces the energy consumption of solvent heating and condensation.

[0010] (3) Significantly improved product yield and production efficiency: ① The reaction conditions are precisely controlled during the acylation process, and a staged gradient heating strategy is designed for the cyclization process, so that the yield of intermediate BE acid reaches more than 90% and the yield of 2-ethylanthraquinone is stable at more than 80%, which is 15-20% higher than the traditional process; ② The intermediate BE acid does not need to be crystallized and separated, and directly enters the subsequent process, simplifying the process steps, increasing the production efficiency by more than 30%, while reducing intermediate loss and further improving product yield; ③ The raw materials, solvents and additives of each process are recycled, reducing the amount of raw material replenishment and reducing the production raw material cost.

[0011] (4) The process is simple to operate and suitable for industrial production. All process parameters are precisely controllable. The cyclization kettle is equipped with a special precision temperature control system. There are no complicated operation steps. The equipment is a conventional industrial equipment, which is easy to modify and scale up. The product is purified by high vacuum distillation and has a purity of ≥99.5%, which meets the requirements for industrial-grade 2-ethylanthraquinone and has strong market applicability. Attached Figure Description

[0012] Figure 1 A schematic diagram of an energy-saving and environmentally friendly 2-ethylanthraquinone production system provided in the embodiments of this application; Symbolic representation: 1-Acylation vessel, 2-Hydrolysis vessel, 3-Separating tank, 4-Chlorobenzene tank, 5-Drying vessel, 6-Cycloning vessel, 7-Crystallization vessel, 8-Distillation vessel, 9-Waste liquid tank, 10-Extraction tower. Detailed Implementation

[0013] This application provides an energy-saving and environmentally friendly method for producing 2-ethylanthraquinone, the method comprising: S01: After mixing ethylbenzene, anhydrous aluminum trichloride and chlorobenzene, phthalic anhydride is slowly added dropwise, and the mixture is kept at 45-50℃ for 4-5 hours to obtain an acylated solution.

[0014] Ethylbenzene, anhydrous aluminum trichloride, and chlorobenzene were added to an acylation reactor at a mass ratio of (5-8):(15-21):(1-4). The mixture was stirred at a stirring rate of 300-400 r / min for 15-20 min to form a mixture. Phthalic anhydride was added dropwise to the mixture at a rate of 5-8 kg / h, with the system temperature maintained at 25-30℃ during the addition process to avoid localized overheating and side reactions. After the addition was complete, the mixture was kept at 45-50℃ for 4-5 h, and the reaction progress of ethylbenzene and anhydrous aluminum trichloride was monitored by liquid chromatography. After the reaction of ethylbenzene and anhydrous aluminum trichloride was complete, heating was stopped, and the jacket cooling system was turned on to lower the system temperature to 20-25℃, yielding the acylated solution.

[0015] In this application, anhydrous aluminum trichloride is used in extreme excess as a catalyst to facilitate the formation of a highly efficient catalytically active complex, thereby driving the efficient generation of BE acid and accelerating the reaction kinetics. Chlorobenzene serves as an inert reaction medium; too little chlorobenzene will result in an overly vigorous reaction and an increase in side reactions, while too much chlorobenzene will dilute ethylbenzene and phthalic anhydride, reducing the reaction rate and production capacity. Therefore, the mass ratio of ethylbenzene to chlorobenzene in this application is (5-8):(1-4).

[0016] In this application, the molar ratio of phthalic anhydride to ethylbenzene is 1:(0.5-1.2), with a slight excess of ethylbenzene, so as to achieve the complete conversion of the more expensive phthalic anhydride using the relatively inexpensive ethylbenzene, while suppressing the occurrence of side reactions.

[0017] In this application, the acylation process of ethylbenzene does not involve sodium hydroxide extraction or sulfuric acid precipitation, thus avoiding the generation of sodium sulfate wastewater from the source. At the same time, this application precisely controls the dropping rate and reaction temperature of phthalic anhydride to reduce side reactions and improve the yield of BE acid.

[0018] S02: The acylation solution is slowly added dropwise to dilute hydrochloric acid at 5-10℃, and the hydrolysis reaction is carried out at 30-35℃ for 2-3 hours to obtain the hydrolysis reaction solution.

[0019] A 10-15% (w / w) solution of dilute hydrochloric acid is prepared in a hydrolysis reactor and cooled to 5-10°C. The acylation solution is added dropwise to the dilute hydrochloric acid at a rate of 10-12 kg / h, maintaining the system temperature at 10-15°C during the addition process to prevent excessive temperature from causing hydrolysis of the organic phase. After the addition is complete, the hydrolysis reaction is carried out at 30-35°C for 2-3 hours to ensure complete hydrolysis of the acylation solution, yielding a hydrolyzed reaction solution. After the hydrolysis reaction is complete, heating is stopped, and the jacket cooling system is activated to lower the system temperature to 20-25°C. In this application, the mass ratio of the acylation solution to the dilute hydrochloric acid is 22:0.15.

[0020] S03: The hydrolysis reaction solution is allowed to stand and separate, washed until the pH of the aqueous phase is 6-7, dried until the water content is ≤0.1%, and filtered to obtain a dry BE acid mother liquor.

[0021] The hydrolysis reaction solution is transferred to a separatory tank and allowed to stand for 1-2 hours to separate the organic and inorganic phases. Pure water is added to the organic phase, and the mixture is washed for 10-15 minutes with a stirring rate of 200-250 rpm. The mixture is then allowed to stand and separate. This washing process is repeated until the pH of the aqueous phase after washing is 6-7. In each washing cycle, the amount of pure water added is 30-40% of the organic phase mass. The inorganic phase and the washed aqueous phase are then transferred to a waste liquid tank and purged with a polymerization initiator to prepare polyaluminum chloride flocculant. This process achieves resource utilization of the aqueous phase, eliminates wastewater discharge, and reduces environmental treatment costs.

[0022] The washed organic phase is transferred to a drying reactor, and anhydrous magnesium sulfate (8-10% of the organic phase mass) is added. The mixture is dried at a stirring speed of 150-200 rpm for 4-5 hours until the water content of the organic phase is ≤0.1%. After drying, the solution is filtered through a rotary drum vacuum filter to obtain dried BE acid mother liquor. The filtered anhydrous magnesium sulfate is regenerated in a magnesium sulfate dryer and recycled, reducing solid waste generation and raw material consumption.

[0023] S04: The BE acid mother liquor is distilled under reduced pressure to obtain BE acid intermediate slurry.

[0024] The BE acid mother liquor was transferred to a cyclization reactor and distilled under reduced pressure at a vacuum of -0.08 to -0.09 MPa and a temperature of 60-70°C to remove chlorobenzene solvent from the system. Distillation was stopped when no solvent was distilled off, yielding a BE acid intermediate slurry. This slurry was cooled to room temperature and stored for later use. The removed chlorobenzene was condensed in a chlorobenzene condensation recovery tank and then recycled to a chlorobenzene tank, with a chlorobenzene recovery rate ≥98%.

[0025] In this application, the BE acid mother liquor is directly introduced into the concentration process without crystallization separation, simplifying the process steps, reducing intermediate losses, and increasing production efficiency by more than 30%. Simultaneously, vacuum distillation can lower the heating temperature, and with the addition of condensation recovery, solvent recycling is achieved, saving energy and reducing resource waste.

[0026] S05: Add fuming acid at 10-15℃ to the BE acid intermediate slurry, and carry out a cyclization reaction under segmented heating and stirring rate of 200-300r / min to obtain a cyclized liquid.

[0027] Add fuming acid pre-cooled to 10-15℃ to the BE acid intermediate slurry, with the amount of fuming acid being 1.2-1.5 times the mass of the BE acid intermediate slurry. Under a stirring rate of 200-300 r / min, first maintain the reaction at 15-20℃ for 1-2 hours to ensure thorough mixing of the fuming acid and BE acid, initiating the cyclization reaction and avoiding localized carbonization due to direct high temperature. Then, increase the temperature to 35-40℃ at a rate of 1-2℃ / min and maintain the reaction for 2-3 hours. This reaction stage is the main stage of the cyclization reaction; precise temperature control ensures reaction selectivity and reduces side reactions. Finally, increase the temperature to 55-60℃ at a rate of 0.5-1℃ / min and maintain the reaction for 3-4 hours to ensure complete cyclization of the remaining BE acid and improve the reaction conversion rate. During the cyclization reaction, the reaction progress of the BE acid is monitored by liquid chromatography. Once the BE acid reaction is complete, the jacket cooling is activated to cool the system to below 20°C, yielding a cyclized liquid.

[0028] In this application, segmented temperature control can precisely match the kinetic characteristics of the cyclization reaction, improve reaction selectivity and conversion rate, and achieve a 2-ethylanthraquinone yield of over 80%, significantly reducing the amount of fuming acid used and reducing waste acid emissions from the source.

[0029] S06: The cyclized liquid is slowly dripped into cold water at 5-10℃, and after crystallization, washing, and filtration, crude 2-ethylanthraquinone is obtained.

[0030] Add cold water to the crystallization vessel and cool it to 5-10℃. Slowly add the cyclized liquid dropwise into the cold water at a rate of 8-10 kg / h, maintaining the system temperature at 10-15℃ during the addition process to allow for slow crystallization and the acquisition of 2-ethylanthraquinone crystals. After the addition is complete, continue stirring for 30-40 minutes to allow the 2-ethylanthraquinone crystals to grow sufficiently. Filter the crystallized material through a centrifuge, and wash the filter cake 2-3 times with pure water until the pH of the washing water reaches 5-6. Dry the washed filter cake to obtain crude 2-ethylanthraquinone.

[0031] The filtrate after centrifugation is waste sulfuric acid with a mass fraction of approximately 50%. This waste sulfuric acid is then extracted and concentrated by benzene and higher alcohols and used as fuming acid, thus realizing the recycling of sulfuric acid, reducing the amount of sulfuric acid used, and reducing waste acid emissions by more than 80%.

[0032] S07: The crude 2-ethylanthraquinone is vacuum distilled at a vacuum degree of -0.095 to -0.098 MPa and a temperature of 220-230℃, and then condensed to obtain 2-ethylanthraquinone.

[0033] The crude 2-ethylanthraquinone was transferred to a distillation vessel, and a high vacuum system was activated. Vacuum distillation was performed at a vacuum level of -0.095 to -0.098 MPa and a temperature of 220-230℃. The resulting 2-ethylanthraquinone vapor was condensed to obtain 2-ethylanthraquinone with a purity ≥99.5%. The 2-ethylanthraquinone was then sliced ​​using a slicer and packaged for storage.

[0034] In this application, no organic solvents are used for recrystallization, reducing solvent usage and waste liquid generation. Furthermore, the residue in the distillation vessel can be treated and used as fuel, achieving the energy utilization of solid waste.

[0035] In addition, this application also provides an energy-saving and environmentally friendly 2-ethylanthraquinone production system, which is used to implement the above-described 2-ethylanthraquinone production method. (See attached...) Figure 1 As shown, the energy-saving and environmentally friendly 2-ethylanthraquinone production system provided in this application includes an acylation kettle 1, a hydrolysis kettle 2, a separating tank 3, a chlorobenzene tank 4, a drying kettle 5, a cyclization kettle 6, a crystallization kettle 7, and a distillation kettle 8 connected in series. The separating tank 3 is connected in series with a waste liquid tank 9 and an extraction tower 10, and the extraction tower 10 is connected to the chlorobenzene tank 4.

[0036] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0037] Example 1 This application provides an energy-saving and environmentally friendly method for producing 2-ethylanthraquinone, the method comprising: S101: Add 60 kg of ethylbenzene, 190 kg of anhydrous aluminum trichloride, and 20 kg of chlorobenzene to an acylation reactor and stir at 350 r / min for 15 min to form a mixture. Add 80 kg of phthalic anhydride dropwise to the mixture at a rate of 5 kg / h, maintaining the system temperature at 25°C during the addition. After the addition is complete, maintain the reaction at 45°C for 4 h, and monitor the reaction progress of ethylbenzene and anhydrous aluminum trichloride using liquid chromatography. After the reaction of ethylbenzene and anhydrous aluminum trichloride is complete, stop heating and open the jacket cooling system to lower the system temperature to 20°C, obtaining the acylated solution.

[0038] S102: Prepare a 10% (w / w) solution of dilute hydrochloric acid in a hydrolysis reactor and cool it to 8°C. Add the acylated solution dropwise into the hydrochloric acid at a rate of 10 kg / h, maintaining the system temperature at 12°C throughout the addition. After the addition is complete, hydrolyze the solution at 32°C for 2.5 h to obtain the hydrolyzed reaction solution. Once the hydrolysis reaction is complete, stop heating and turn on the jacket cooling system to lower the system temperature to 20°C.

[0039] S103: Transfer the hydrolysis reaction solution to a separatory tank and allow it to stand for 1.5 hours to separate the organic and inorganic phases. Add pure water to the organic phase and wash for 13 minutes at a stirring rate of 220 r / min. Allow it to stand and separate the phases. Repeat the washing process until the pH of the aqueous phase after washing is 6-7. In each washing process, the amount of pure water added is 35% of the mass of the organic phase. Transfer the washed organic phase to a drying vessel and add anhydrous magnesium sulfate at 9% of the mass of the organic phase. Dry the organic phase at a stirring speed of 180 r / min for 4.5 hours to ensure that the water content of the organic phase is ≤0.1%. After drying, filter the solution using a rotary drum vacuum filter to obtain the dried BE acid mother liquor.

[0040] S104: The BE acid mother liquor is transferred to a cyclization reactor and distilled under reduced pressure at a vacuum of -0.085 MPa and a temperature of 65°C to remove chlorobenzene solvent from the system. Distillation is stopped when no solvent is distilled off, yielding a BE acid intermediate slurry. This slurry is cooled to room temperature and used for later use. The removed chlorobenzene is condensed in a chlorobenzene condensation recovery tank and then recycled to a chlorobenzene tank, with a chlorobenzene recovery rate ≥98%.

[0041] S105: Add fuming acid pre-cooled to 12°C to the BE acid intermediate slurry, with the amount of fuming acid being 1.3 times the mass of the BE acid intermediate slurry. Under a stirring rate of 250 r / min, first maintain the reaction at 18°C ​​for 1.5 h; then, increase the temperature to 38°C at a rate of 1.2°C / min and maintain the reaction for 2.5 h; finally, increase the temperature to 58°C at a rate of 0.8°C / min and maintain the reaction for 3.5 h. During the cyclization reaction, the reaction progress of the BE acid is monitored by liquid chromatography. When the complete reaction of the BE acid is detected, the jacket cooling is activated to cool the system to below 20°C, yielding the cyclized liquid.

[0042] S106: Add cold water to the crystallization vessel and cool the water to 8°C. Add the cyclized liquid slowly to the cold water at a dropping rate of 9 kg / h, maintaining the system temperature at 12°C during the addition process to allow for slow crystallization and the acquisition of 2-ethylanthraquinone crystals. After the addition is complete, continue stirring for 35 minutes to allow the 2-ethylanthraquinone crystals to grow sufficiently. Filter the crystallized material through a centrifuge, and wash the filter cake twice with pure water until the pH of the washing water reaches 5-6. Dry the washed filter cake to obtain crude 2-ethylanthraquinone.

[0043] S107: Transfer the crude 2-ethylanthraquinone to a distillation vessel, turn on the high vacuum system, and perform vacuum distillation at a vacuum degree of -0.096 MPa and a temperature of 225 °C. The 2-ethylanthraquinone vapor obtained by distillation is condensed by a condenser to obtain 2-ethylanthraquinone.

[0044] The results showed that the yield of BE acid was 91%, the purity of 2-ethylanthraquinone was 99.6%, and the yield of 2-ethylanthraquinone was 81%.

[0045] Example 2 This application provides an energy-saving and environmentally friendly method for producing 2-ethylanthraquinone, the method comprising: S201: Add 50 kg of ethylbenzene, 150 kg of anhydrous aluminum trichloride, and 10 kg of chlorobenzene to an acylation reactor and stir at 300 r / min for 15 min to form a mixture. Add 37.5 kg of phthalic anhydride dropwise to the mixture at a rate of 8 kg / h, maintaining the system temperature at 30°C during the addition. After the addition is complete, maintain the reaction at 50°C for 5 h, and monitor the reaction progress of ethylbenzene and anhydrous aluminum trichloride using liquid chromatography. After the reaction of ethylbenzene and anhydrous aluminum trichloride is complete, stop heating and turn on the jacket cooling system to lower the system temperature to 25°C, obtaining the acylated solution.

[0046] S202: Prepare a 15% (w / w) solution of dilute hydrochloric acid in a hydrolysis reactor and cool it to 5°C. Add the acylated solution dropwise into the hydrochloric acid at a rate of 12 kg / h, maintaining the system temperature at 15°C throughout the addition. After the addition is complete, hydrolyze the solution at 35°C for 3 hours to obtain the hydrolyzed reaction solution. Once the hydrolysis reaction is complete, stop heating and turn on the jacket cooling system to lower the system temperature to 25°C.

[0047] S203: Transfer the hydrolysis reaction solution to a separatory tank and allow it to stand for 1 hour to separate the organic and inorganic phases. Add pure water to the organic phase and wash for 15 minutes at a stirring rate of 200 rpm. Allow it to stand and separate the phases. Repeat the washing process until the pH of the aqueous phase after washing is 6-7. In each washing process, the amount of pure water added is 40% of the mass of the organic phase. Transfer the washed organic phase to a drying vessel and add anhydrous magnesium sulfate at 10% of the mass of the organic phase. Dry the organic phase at a stirring speed of 150 rpm for 5 hours to ensure that the water content of the organic phase is ≤0.1%. After drying, filter the solution using a rotary drum vacuum filter to obtain the dried BE acid mother liquor.

[0048] S204: The BE acid mother liquor is transferred to a cyclization reactor and distilled under reduced pressure at a vacuum of -0.09 MPa and a temperature of 70°C to remove chlorobenzene solvent from the system. Distillation is stopped when no solvent is distilled off, yielding a BE acid intermediate slurry. This slurry is cooled to room temperature and used for later use. The removed chlorobenzene is condensed in a chlorobenzene condensation recovery tank and then recycled to a chlorobenzene tank, with a chlorobenzene recovery rate ≥98%.

[0049] S205: Add fuming acid pre-cooled to 10°C to the BE acid intermediate slurry, with the amount of fuming acid being 1.5 times the mass of the BE acid intermediate slurry. Under a stirring rate of 300 r / min, first maintain the reaction at 20°C for 2 h; then, increase the temperature to 40°C at a rate of 2°C / min and maintain the reaction for 3 h; finally, increase the temperature to 60°C at a rate of 1°C / min and maintain the reaction for 4 h. During the cyclization reaction, the reaction progress of the BE acid is monitored by liquid chromatography. When the complete reaction of the BE acid is detected, the jacket cooling is activated to cool the system to below 20°C, yielding the cyclized liquid.

[0050] S206: Add cold water to the crystallization vessel and cool the water to 5°C. Add the cyclized liquid slowly to the cold water at a dropping rate of 10 kg / h, maintaining the system temperature at 15°C during the addition process to allow for slow crystallization and the acquisition of 2-ethylanthraquinone crystals. After the addition is complete, continue stirring for 30 minutes to allow the 2-ethylanthraquinone crystals to grow sufficiently. Filter the crystallized material through a centrifuge, and wash the filter cake twice with pure water until the pH of the washing water reaches 5-6. Dry the washed filter cake to obtain crude 2-ethylanthraquinone.

[0051] S207: Transfer the crude 2-ethylanthraquinone to a distillation vessel, turn on the high vacuum system, and perform vacuum distillation at a vacuum degree of -0.098 MPa and a temperature of 230℃. The 2-ethylanthraquinone vapor obtained by distillation is condensed by a condenser to obtain 2-ethylanthraquinone.

[0052] The results showed that the yield of BE acid was 92%, the purity of 2-ethylanthraquinone was 99.7%, and the yield of 2-ethylanthraquinone was 83%.

[0053] Example 3 This application provides an energy-saving and environmentally friendly method for producing 2-ethylanthraquinone, the method comprising: S301: Add 60 kg of ethylbenzene, 190 kg of anhydrous aluminum trichloride, and 20 kg of chlorobenzene to an acylation reactor and stir at 400 r / min for 15 min to form a mixture. Add 80 kg of phthalic anhydride dropwise to the mixture at a rate of 7 kg / h, maintaining the system temperature at 25°C during the addition. After the addition is complete, maintain the reaction at 45°C for 4 h, and monitor the reaction progress of ethylbenzene and anhydrous aluminum trichloride using liquid chromatography. After the reaction of ethylbenzene and anhydrous aluminum trichloride is complete, stop heating and open the jacket cooling system to lower the system temperature to 25°C, obtaining the acylated solution.

[0054] S302: Prepare a 15% (w / w) solution of dilute hydrochloric acid in a hydrolysis reactor and cool it to 10°C. Add the acylated solution dropwise into the dilute hydrochloric acid at a rate of 10 kg / h, maintaining the system temperature at 10°C throughout the addition. After the addition is complete, hydrolyze the solution at 35°C for 2 hours to obtain the hydrolyzed reaction solution. Once the hydrolysis reaction is complete, stop heating and turn on the jacket cooling system to lower the system temperature to 20°C.

[0055] S303: Transfer the hydrolysis reaction solution to a separatory tank and allow it to stand for 2 hours to separate the organic and inorganic phases. Add pure water to the organic phase and wash for 15 minutes at a stirring rate of 250 r / min. Allow it to stand and separate the phases. Repeat the washing process until the pH of the aqueous phase after washing is 6-7. In each washing process, the amount of pure water added is 40% of the mass of the organic phase. Transfer the washed organic phase to a drying vessel and add anhydrous magnesium sulfate at 10% of the mass of the organic phase. Dry the organic phase at a stirring speed of 150 r / min for 5 hours to ensure that the water content of the organic phase is ≤0.1%. After drying, filter the solution using a rotary drum vacuum filter to obtain the dried BE acid mother liquor.

[0056] S304: The BE acid mother liquor is transferred to a cyclization reactor and distilled under reduced pressure at a vacuum of -0.09 MPa and a temperature of 70°C to remove chlorobenzene solvent from the system. Distillation is stopped when no solvent is distilled off, yielding a BE acid intermediate slurry. This slurry is cooled to room temperature and used for later use. The removed chlorobenzene is condensed in a chlorobenzene condensation recovery tank and then recycled to a chlorobenzene tank, with a chlorobenzene recovery rate ≥98%.

[0057] S305: Add fuming acid pre-cooled to 10°C to the BE acid intermediate slurry, with the amount of fuming acid being 1.2 times the mass of the BE acid intermediate slurry. Under a stirring rate of 280 r / min, first maintain the reaction at 18°C ​​for 1.5 h; then, increase the temperature to 38°C at a rate of 1.2°C / min and maintain the reaction for 2.5 h; finally, increase the temperature to 58°C at a rate of 0.6°C / min and maintain the reaction for 3.5 h. During the cyclization reaction, the reaction progress of the BE acid is monitored by liquid chromatography. When the complete reaction of the BE acid is detected, the jacket cooling is activated to cool the system to below 20°C, yielding the cyclized liquid.

[0058] S306: Add cold water to the crystallization vessel and cool the water to 8°C. Add the cyclized liquid slowly to the cold water at a dropping rate of 9 kg / h, maintaining the system temperature at 12°C during the addition process to allow for slow crystallization and the acquisition of 2-ethylanthraquinone crystals. After the addition is complete, continue stirring for 35 minutes to allow the 2-ethylanthraquinone crystals to grow sufficiently. Filter the crystallized material through a centrifuge, and wash the filter cake three times with pure water until the pH of the washing water reaches 5-6. Dry the washed filter cake to obtain crude 2-ethylanthraquinone.

[0059] S307: Transfer the crude 2-ethylanthraquinone to a distillation vessel, turn on the high vacuum system, and perform vacuum distillation at a vacuum degree of -0.098MPa and a temperature of 230℃. The 2-ethylanthraquinone vapor obtained by distillation is condensed by a condenser to obtain 2-ethylanthraquinone with a purity of ≥99.5%.

[0060] The test results showed that the yield of BE acid was 91.3%, the purity of 2-ethylanthraquinone was 99.5%, and the yield of 2-ethylanthraquinone was 81.5%.

[0061] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for producing 2-ethylanthraquinone that is energy-saving and environmentally friendly, characterized in that, include: After mixing ethylbenzene, anhydrous aluminum trichloride and chlorobenzene, phthalic anhydride was slowly added dropwise, and the reaction was kept at 45-50℃ for 4-5 hours to obtain an acylated solution. The acylation solution was slowly added dropwise to dilute hydrochloric acid at 5-10℃, and the hydrolysis reaction was carried out at 30-35℃ for 2-3 hours to obtain the hydrolysis reaction solution. The hydrolysis reaction solution was allowed to stand and separate, washed until the pH of the aqueous phase was 6-7, dried until the water content was ≤0.1%, and filtered to obtain a dry BE acid mother liquor. The BE acid mother liquor was distilled under reduced pressure to obtain a BE acid intermediate slurry. Add fuming acid at 10-15℃ to the BE acid intermediate slurry, and carry out a cyclization reaction under staged heating and stirring rate of 200-300r / min to obtain a cyclized liquid; The cyclized liquid was slowly dripped into cold water at 5-10°C. After crystallization, washing, and filtration, crude 2-ethylanthraquinone was obtained. The crude 2-ethylanthraquinone was vacuum distilled at a vacuum of -0.095 to -0.098 MPa and a temperature of 220-230 °C, and then condensed to obtain 2-ethylanthraquinone.

2. The energy-saving and environmentally friendly method for producing 2-ethylanthraquinone according to claim 1, characterized in that, The mass ratio of the ethylbenzene, the anhydrous aluminum trichloride, and the chlorobenzene is (5-8):(15-21):(1-4); the molar ratio of the phthalic anhydride and the ethylbenzene is 1:(0.5-1.2).

3. The energy-saving and environmentally friendly method for producing 2-ethylanthraquinone according to claim 1, characterized in that, The phthalic anhydride was added at a rate of 5-8 kg / h, and the system temperature during the addition process was 25-30℃.

4. The energy-saving and environmentally friendly method for producing 2-ethylanthraquinone according to claim 1, characterized in that, The mass ratio of the acylation solution to the dilute hydrochloric acid is 22:0.15; the dropping rate of the acylation solution is 10-12 kg / h, and the system temperature during the dropping process is 10-15℃; the dropping rate of the cyclization solution is 8-10 kg / h, and the system temperature during the dropping process is 10-15℃.

5. The energy-saving and environmentally friendly method for producing 2-ethylanthraquinone according to claim 1, characterized in that, The organic phase of the hydrolysis reaction solution after standing and separation is washed with pure water at a stirring rate of 200-250 r / min, and the amount of pure water used is 30-40% of the mass of the organic phase.

6. The energy-saving and environmentally friendly method for producing 2-ethylanthraquinone according to claim 5, characterized in that, Anhydrous magnesium sulfate is added to the washed organic phase, and the mixture is dried for 4-5 hours at a stirring speed of 150-200 r / min, with the amount of anhydrous magnesium sulfate being 8-10% of the mass of the organic phase.

7. The energy-saving and environmentally friendly method for producing 2-ethylanthraquinone according to claim 1, characterized in that, The vacuum distillation conditions are: vacuum degree of -0.08 to -0.09 MPa and temperature of 60-70℃.

8. The energy-saving and environmentally friendly method for producing 2-ethylanthraquinone according to claim 1, characterized in that, The amount of nicotinic acid used is 1.2-1.5 times the mass of the BE acid intermediate slurry.

9. The energy-saving and environmentally friendly method for producing 2-ethylanthraquinone according to claim 1, characterized in that, The segmented heating includes: holding the reaction at 15-20℃ for 1-2 hours; heating to 35-40℃ at a rate of 1-2℃ / min and holding the reaction for 2-3 hours; and heating to 55-60℃ at a rate of 0.5-1℃ / min and holding the reaction for 3-4 hours.

10. An energy-saving and environmentally friendly 2-ethylanthraquinone production system, characterized in that, The system implements the energy-saving and environmentally friendly 2-ethylanthraquinone production method according to any one of claims 1-9; the system includes an acylation kettle (1), a hydrolysis kettle (2), a separating tank (3), a chlorobenzene tank (4), a drying kettle (5), a cyclization kettle (6), a crystallization kettle (7), and a distillation kettle (8) connected in series; the separating tank (3) is connected in series to a waste liquid tank (9) and an extraction tower (10), and the extraction tower (10) is connected to the chlorobenzene tank (4).

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