Electronic-grade ethyl acetate continuous preparation process based on reactive distillation

Abstract

The invention discloses an electronic-grade ethyl acetate continuous preparation process based on reactive distillation, relates to the field of ethyl acetate preparation, and adopts a reactive distillation technology to integrate ester exchange reaction and rectification separation of methyl acetate and ethanol into the same tower. According to the process, transesterification and rectification separation are integrated through a reaction distillation technology, mass transfer is enhanced by means of three-section type catalyst bed layer distribution and ultrasonic vibration, chemical equilibrium limitation is broken through, and the high-level ethanol conversion rate is maintained; heat pump rectification and an APC system are adopted to dynamically optimize the reflux ratio, energy is saved by 40% compared with a traditional process, the raw material utilization rate is increased through a recovery system, low-energy-consumption and high-efficiency production is achieved, an intelligent control system is built through a fiber optic spectrometer, a digital twinborn model and the like, real-time parameter monitoring and closed-loop adjustment are achieved, the process stability and continuity are ensured, and the production efficiency is improved. And high reliability, environmental protection and economical efficiency are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of ethyl acetate preparation, in particular to a continuous preparation process of electronic-grade ethyl acetate based on reactive distillation. Background Art

[0002] Electronic-grade ethyl acetate, a high-end organic solvent, is widely used in fields such as semiconductor wafer manufacturing. With the development of industries like 5G, market demand is rapidly growing, creating an urgent need for high-purity products. Traditional preparation methods, such as esterification, suffer from corrosion and contamination, equilibrium limitations, and difficulty in separation. While transesterification avoids strong acid corrosion, its step-by-step operation is inefficient, catalyst stability is poor, and impurity control is insufficient, making it difficult to meet semiconductor-grade purity requirements. Reactive distillation technology, by coupling reaction with distillation, improves ethanol conversion, saves energy, and reduces equipment investment.

[0003] However, the existing reactive distillation process still faces technical bottlenecks in the preparation of electronic-grade products: Compatibility of catalyst and equipment: The catalyst loading method affects the mass transfer efficiency. Traditional dry loading is prone to channeling, leading to local overheating or insufficient reaction. The catalyst particle size is not well matched with the packing structure, and excessive pressure drop can easily cause flooding, limiting production load. Lack of deep impurity removal technology: Water forms an azeotrope with ethyl acetate (azeotropic point 71.8℃, water content 2.9%), and traditional distillation is difficult to further dehydrate; metal ions (such as Na dissolved in equipment materials) + There is a lack of efficient interception methods for ) and nano-sized particles (catalyst powder, pipeline corrosion products). Insufficient process control precision: Temperature fluctuations in the reaction section lead to an increase in side reactions (such as the formation of ethyl acetate dimer); offline detection (such as a 30-minute gas chromatography analysis cycle) cannot respond to purity fluctuations in a timely manner, resulting in a high rate of defective products. Summary of the Invention

[0004] The object of the present invention is to provide a continuous preparation process of electronic-grade ethyl acetate based on reactive distillation to solve the problems raised by the above background technology.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solution: a continuous production process for electronic-grade ethyl acetate based on reactive distillation, which integrates the transesterification reaction and distillation separation of methyl acetate and ethanol in the same tower using reactive distillation technology; the process comprises the following steps: carrying out the transesterification reaction and preliminary separation from the raw material tank area to the reactive distillation tower, separating the light component methanol and unreacted methyl acetate in a light removal tower, deeply purifying them in a heavy removal tower, and finally collecting them in a finished product tank; the overhead by-products of the light removal tower are processed by a recovery system and then returned to the raw material tank area for recycling; and an online monitoring and control system monitors temperature, pressure, and purity parameters in real time and adjusts them in a coordinated manner to form a closed-loop control system. The specific steps are: S1. Preparation before driving; S2, feeding and reaction control; S3, multi-stage separation and purification; S4, online monitoring and intelligent control; S5, catalyst regeneration; S6. Waste heat recovery and exhaust gas treatment.

[0006] Preferably, pre-driving preparations include: S11. Catalyst loading and pretreatment: calcine H-ZSM-5 zeolite molecular sieve at 550°C for 6 hours, pass through a 20-40 mesh sieve after cooling, and inject into the reaction zone using a "wet loading" method with a loading density of 650-700 kg / m³. 304 stainless steel wire mesh and ceramic inert filler are laid on the top and bottom of the bed; S12. Equipment air tightness test: Helium mass spectrometry leak detection leakage rate ≤5×10 -9 mbar·L / s, the water pressure test pressure is 1.5 times the operating pressure, and the pressure drop is ≤0.5%; S13, raw material pretreatment: remove metal ions through chelating resin column, and control the ethanol water content ≤100ppm and methyl acetate water content ≤50ppm through molecular sieve adsorber.

[0007] Preferably, the feed and reaction control includes: S21, ethanol feed is controlled by a Coriolis mass flowmeter and an electro-hydraulic servo valve in cascade, and the feed rate is automatically adjusted when the temperature fluctuates by ±0.5°C; methyl acetate gasification controls the gas phase superheat at 10-15°C and the superficial gas velocity at 0.8-1.2m / s; S22. The catalyst bed in the reaction section adopts a "three-stage distribution": the upper layer is filled with θ-ring packing, the middle section is filled with catalyst and packing alternately, and the lower distillation section uses structured packing and is equipped with an ultrasonic vibrator.

[0008] Preferably, the multi-stage separation and purification steps include: S31, the light removal tower uses 50 layers of high-efficiency float valve trays and adopts heat pump distillation technology. The ethanol-water azeotrope produced by the side line is treated by the molecular sieve membrane dehydration unit and then returned to the reactive distillation tower; The S32 deweighting tower uses stainless steel wire mesh corrugated packing, and the reflux ratio is dynamically optimized through an open source cache acceleration tool. The terminal filtration uses a 1μm sintered metal filter element and a 0.2μm polytetrafluoroethylene pleated filter element. S33, by-product recovery system adopts the three-stage process of "cryogenic condensation - fractional distillation purification - adsorption drying".

[0009] Preferably, online monitoring and intelligent control include: S41. A fiber optic spectrometer is installed in the middle of the reaction section to predict the conversion rate using a partial least squares regression model. An online TOC analyzer and a dielectric constant sensor are installed at the outlet of the finished product tank to automatically trigger reflux when the threshold is deviated. S42. Build a digital twin model based on process simulation software, synchronize real-time data every 5 minutes, and optimize reaction temperature and feed ratio through model predictive control.

[0010] Preferably, the catalyst regeneration comprises: S51, pulse pickling: first rinse with deionized water for 2 hours, then use a mixture of 5% nitric acid and 0.1% hydrofluoric acid combined with ultrasonic assistance to remove carbon deposits; S52. Microwave activation: microwave at a frequency of 2.45 GHz, a power of 10 kW, a heating rate of 10°C / min to 500°C, and constant temperature heating for 3 hours.

[0011] Preferably, waste heat recovery and waste gas treatment include: S61, the overhead steam of the reactive distillation tower preheats the raw material ethanol, and the bottom liquid of the heavy removal tower heats the feed of the light removal tower; S62, the waste gas is treated by "deep-cold condensation, activated carbon fiber adsorption and catalytic combustion".

[0012] Preferably, targeted treatment measures are taken for abnormal phenomena, including: When the reaction section is flooded, reduce the methyl acetate feed rate by 30%, open the top vent valve to release the pressure to 0.3 MPa, and purge with nitrogen (flow rate 5 m³ / h, lasting 10 minutes); When the catalyst deactivation warning is issued, the system switches to the spare catalyst bed and triggers the rapid regeneration program (regeneration time ≤ 6 hours); When the metal ion content of the finished product exceeds the standard, the ion exchange resin column (three columns in parallel) is automatically switched and the unqualified products are reprocessed.

[0013] Preferably, key parameter control includes: Reaction section temperature 55-100℃ (control accuracy ±0.1℃), temperature gradient ≤2℃ / m; Finished product moisture ≤50ppm (Karl Fischer online monitoring, automatic reflux if exceeded for three consecutive times); Particle pollution control: ≥0.5μm particles ≤100 particles / mL (real-time monitoring by laser particle counter, alarm value ≥150 particles / mL).

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. This process integrates transesterification reaction and distillation separation through reactive distillation technology. Leveraging a "three-stage" catalyst bed distribution and ultrasonic vibration to enhance mass transfer, it overcomes chemical equilibrium limitations and achieves an ethanol conversion rate of ≥99.8%. Using heat pump distillation and an APC system to dynamically optimize the reflux ratio, it saves 40% energy compared to traditional processes. Furthermore, a recycling system improves raw material utilization, achieving low-energy consumption and high-efficiency production. 2. The process uses multi-stage precision purification (molecular sieve membrane dehydration and two-stage terminal filtration) to ensure the purity of the finished product is ≥99.99%, meeting the needs of high-end fields; relying on fiber optic spectrometers, digital twin models, etc. to build an intelligent control system to achieve real-time parameter monitoring and closed-loop adjustment, combined with pulse pickling + microwave activation high-efficiency catalyst regeneration technology (regeneration time is shortened by 50%, acid recovery rate ≥95%), to ensure process stability and continuity, and combine high reliability with environmental protection and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention is a flow chart of a continuous process for preparing electronic-grade ethyl acetate based on reactive distillation. DETAILED DESCRIPTION

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the implementation regulations described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0017] Example 1: Reference Figure 1 As shown: A continuous production process for electronic-grade ethyl acetate based on reactive distillation utilizes reactive distillation (RD) technology to integrate the transesterification reaction between methyl acetate and ethanol with distillation separation in the same column. Through catalyst engineering optimization, multi-stage precision purification, and intelligent process control, continuous production of electronic-grade ethyl acetate (purity ≥ 99.99%) is achieved. The process integrates the synergistic effect of reaction and separation, breaking through the limitations of chemical equilibrium, significantly improving conversion rates (ethanol conversion rate ≥ 99.8%) and reducing energy consumption (40% energy saving compared to traditional processes), meeting the stringent requirements for ultra-pure solvents in high-end fields such as semiconductors and photoresists. The process mainly includes: Main process: raw material tank area → reaction distillation tower (ester exchange reaction + preliminary separation) → light removal tower (separation of light component methanol / unreacted methyl acetate) → heavy removal tower (deep purification) → finished product tank (electronic grade product).

[0018] Circulation system: The by-products from the top of the light removal tower are processed by the recovery system and returned to the raw material tank area for recycling, thereby improving the utilization rate of raw materials.

[0019] Control system: The online monitoring and control system monitors parameters such as temperature, pressure, purity, etc. in real time, and adjusts process conditions in a coordinated manner to form a closed-loop control.

[0020] The key steps are as follows: Step 1: Prepare before driving.

[0021] Catalyst treatment: H-ZSM-5 zeolite molecular sieve is calcined and wet-packed (mixed with ethanol at a ratio of 1:3). The packing density is 650-700 kg / m³. The bed is fixed with stainless steel wire mesh and ceramic filler.

[0022] Equipment detection: Helium mass spectrometry leak detection (leak rate ≤ 5×10 -9 mbar·L / s) and water pressure test (pressure is 1.5 times of the operating pressure, pressure drop ≤0.5%).

[0023] Raw material pretreatment: metal ions (Na + , K + 、Fe 3+ ≤0.1ppb), molecular sieve adsorber controls moisture (ethanol ≤100ppm, methyl acetate ≤50ppm).

[0024] Step 2: Feed and reaction control.

[0025] The ethanol feed is controlled by a mass flow meter and an electro-hydraulic servo valve in cascade, and the methyl acetate gasification is controlled at a superheat of 10-15°C and an superficial gas velocity of 0.8-1.2 m / s.

[0026] The catalyst bed adopts a "three-stage distribution" and is equipped with an ultrasonic vibrator (frequency 20kHz) to increase the mass transfer coefficient by 20%-30%.

[0027] Step 3: multi-stage separation and purification.

[0028] Light-removal tower: 50-layer floating valve tray, adopts heat pump distillation (energy saving 35%), and the azeotropic product taken out from the side line is dehydrated by molecular sieve membrane and then returned to the reaction tower.

[0029] De-weighting tower: Stainless steel wire mesh corrugated packing (specific surface area 700m² / m³), reflux ratio dynamically optimized by APC (Advanced Process Control) system, terminal filtration uses 1μm and 0.2μm filter elements.

[0030] Step 4: Online monitoring and intelligent control.

[0031] The fiber optic spectrometer monitors the reactant concentration in real time, while the TOC analyzer and dielectric constant sensor control the quality of the finished product (TOC ≥ 5ppb or dielectric constant deviation triggers reflux).

[0032] The digital twin model synchronizes data every 5 minutes to optimize the reaction temperature and feed ratio, ensuring that the conversion rate remains stable at above 99.8%.

[0033] Step 5: Catalyst regeneration.

[0034] Pulse pickling (nitric acid + hydrofluoric acid mixture) combined with ultrasound-assisted carbon removal and microwave activation (2.45GHz, 10kW) shortened the regeneration time to 3 hours, with an acid recovery rate of ≥95%.

[0035] Step 6: Waste heat recovery and exhaust gas treatment.

[0036] The waste heat from the tower top steam and tower bottom liquid is used to preheat the raw materials, saving 20% of steam annually.

[0037] The exhaust gas is treated by "condensation + activated carbon adsorption + catalytic combustion", and the VOCs emission is ≤10mg / m³.

[0038] Example 2: A continuous process for preparing electronic-grade ethyl acetate based on reactive distillation, comprising the following steps: Step 1: Preparation before start-up, mainly including catalyst loading and pretreatment, equipment air tightness testing and raw material pretreatment.

[0039] (I) Catalyst Loading and Pretreatment. First, the new catalyst (H-ZSM-5 zeolite molecular sieve, silicon-aluminum ratio of 30-50) is heated to 550°C in a muffle furnace at a rate of 5°C / min and calcined at this temperature for 6 hours to remove adsorbed water and organic impurities. After cooling, it is passed through a 20-40 mesh sieve (particle size 0.425-0.85mm). Next, using a "wet loading" technique, the catalyst and ethanol are mixed in a 1:3 volume ratio to form a slurry. This slurry is uniformly injected into the reaction zone through an elevated tank at a flow rate of 0.5m³ / h to prevent catalyst breakage and bed drift. The loading density is controlled at 650-700kg / m³. Finally, 304 stainless steel wire mesh (pore size 0.25mm) and ceramic inert filler (height 100mm) are laid on the top and bottom of the bed to prevent catalyst powder loss and liquid channeling.

[0040] (2) Equipment air tightness testing, including helium mass spectrometry leak detection and water pressure testing.

[0041] Helium mass spectrometer leak detection: Evacuate the reaction distillation tower, pipeline and valve system to ≤10Pa, fill with 99.999% high-purity helium to 0.6MPa, and use a helium mass spectrometer leak detector (accuracy 1×10 -9 mbar·L / s) to detect each welding point and flange interface, and the leakage rate must be ≤5×10 -9 mbar·L / s.

[0042] Water pressure test: The light-removal tower and heavy-removal tower are subjected to water pressure test (the test pressure is 1.5 times the operating pressure, and the pressure is maintained for 30 minutes). A pressure drop of ≤0.5% is considered qualified.

[0043] (3) Raw material pretreatment includes metal ion removal and moisture control.

[0044] Metal ion removal: Ethanol and methyl acetate raw materials first pass through a chelating resin column (filled with D401 resin, particle size 0.315-1.25mm) at a flow rate of 2BV / h (bed volume multiple) to ensure that Na + , K + 、Fe 3+ Concentration ≤0.1ppb.

[0045] Moisture control: A molecular sieve adsorber (4Å type, regeneration cycle 24 hours) was installed on the top of the raw material tank to reduce the moisture content of ethanol to ≤100ppm and the moisture content of methyl acetate to ≤50ppm (online monitoring by Karl Fischer titration).

[0046] Step 2: Feed and reaction control, specifically: (I) Construction of a precise feeding system: Ethanol feed uses a Coriolis mass flowmeter (accuracy ±0.1%) + electro-hydraulic servo valve (response time ≤0.5s), which forms a cascade control with the reaction section temperature: when the temperature fluctuation exceeds ±0.5°C, the feed amount is automatically adjusted (adjustment range ±5%); methyl acetate gasification uses a plate heat exchanger (heat exchange area 50m2, pressure drop ≤0.02MPa), and the gas phase superheat is controlled at 10-15°C. The gas flow rate is monitored by a vortex flowmeter (accuracy ±0.5%) to ensure that the superficial gas velocity is 0.8-1.2m / s to avoid flooding.

[0047] (II) Enhanced mass transfer in the reaction section: The catalyst bed adopts a "three-stage distribution": the upper layer (below the distillation section) is filled with θ-ring packing (made of 316L stainless steel, with a specific surface area of 500m² / m³), the middle reaction section is filled with catalyst and packing alternately (catalyst bed height 500mm + packing layer 300mm), and the lower distillation section uses structured packing (Mellapak250Y, pressure drop ≤0.5kPa / m). The gas-liquid distribution is optimized through CFD simulation; an ultrasonic vibrator (frequency 20kHz, power 1kW / ㎡) is installed on the outer wall of the reaction section and automatically starts for 5 minutes every 30 minutes to break the liquid film on the catalyst surface and improve the mass transfer coefficient by 20%-30%.

[0048] Step 3: Multi-stage separation and purification, specifically: (I) Azeotropic distillation in the light-removal column. The column utilizes 50 high-efficiency float valve trays (3mm diameter, 10% porosity), with 40 theoretical plates, and the feed is located on the 20th plate. Using heat pump distillation technology, overhead steam (72°C, 0.15MPa) is boosted to 0.3MPa by a compressor and used as the heat source for the bottom reboiler, achieving a 35% energy saving. The condensate subcooling is controlled at 5-8°C. An ethanol-water azeotrope is drawn from the side stream and fed into a molecular sieve membrane dehydration unit (membrane area 10 m2, operating temperature 50°C, vacuum 5 kPa). The permeate (water content ≤ 10 ppm) is returned to the reactive distillation column.

[0049] (II) Precision distillation in the deweighting tower. The packing is stainless steel wire mesh corrugated packing (specific surface area 700m² / m³, plate height ≤0.15m), the total number of theoretical plates in the tower is 80, and the reflux ratio is Dynamic optimization through APC (Advanced Process Control) system: ; in, =2.0, =0.5, =0.1, with real-time adjustments to ensure top-of-tower purity fluctuations ≤0.001%. Terminal filtration: A two-stage filtration system is set up, first passing the particles through a 1μm sintered metal filter element (automatically backflushed when the pressure differential is ≥0.1MPa), then through a 0.2μm pleated polytetrafluoroethylene filter element (sterilizing grade, particle capture efficiency ≥99.99%). Laser particle counters (detection accuracy 0.3μm, counting frequency 1 time / minute) are installed at the filter inlet and outlet. A two-stage filtration system is set up, first passing the particles through a 1μm sintered metal filter element (automatically backflushed when the pressure differential is ≥0.1MPa), then through a 0.2μm pleated polytetrafluoroethylene filter element (sterilizing grade, particle capture efficiency ≥99.99%). Laser particle counters (detection accuracy 0.3μm, counting frequency 1 time / minute) are installed at the filter inlet and outlet for terminal filtration.

[0050] (3) The by-product recovery system, whose core is to process the methanol-methyl acetate mixed gas (containing a small amount of ethanol and water) discharged from the top of the lightness removal tower. Through the three-stage recovery process of "deep cold condensation-fractionation purification-adsorption drying", the raw material recycling (recovery rate ≥ 98%) is achieved, which significantly reduces material consumption and emissions.

[0051] 1. Cryogenic condensation technology, which uses a spiral tube cryogenic condenser (made of 316L stainless steel, with a heat exchange area of 200 m2) and liquid nitrogen as the refrigerant (temperature -70°C, pressure 1.2 MPa), with a condensation efficiency of ≥98%.

[0052] Control: The temperature of the condensed liquid is monitored (controlled at -65~-60℃) by a temperature sensor (accuracy ±0.5℃) to ensure that methanol (freezing point -97.8℃) and methyl acetate (freezing point -98.1℃) are completely liquefied, and only a small amount of non-condensable gas (nitrogen and trace low-boiling point components) enters subsequent processing.

[0053] 2. The fractionation and purification unit uses a packed tower (filled with Intalox metal packing, specific surface area 380m² / m³), 30 theoretical plates, and the feed position is the 15th plate.

[0054] Operating conditions: tower top temperature 70°C (methanol boiling point 64.7°C, controlled subcooling 5°C), tower bottom temperature 57°C (methyl acetate boiling point 57.1°C), pressure 0.1 MPa (normal pressure), reflux ratio 1:1.

[0055] 3. Adsorption drying and impurity removal: A molecular sieve adsorption bed filled with 3Å molecular sieve (particle size 1.6-2.5mm, dynamic water adsorption capacity ≥20%wt) is used, with two towers connected in parallel (one in use, one in standby, with an 8-hour regeneration cycle). Regeneration is performed by low-pressure heating regeneration (150°C, nitrogen purge, flow rate 20m³ / h, for 2 hours) to ensure that the recovered liquid moisture content is ≤50ppm (meeting the raw material feed requirements).

[0056] The methanol / methyl acetate after fractionation flowed through a chelating resin column (D401 resin, filling volume 2m³) at a controlled flow rate of 1BV / h. + , K + 、Fe 3+ Concentration ≤ 0.1ppb (ICP-MS detection), metal ion fine treatment is carried out.

[0057] Step 4: Online monitoring and intelligent control: Detection and control are carried out by building a multi-dimensional detection system and digital twin model.

[0058] (1) Multi-dimensional detection system: A fiber optic spectrometer (wavelength range 200-1100nm) is installed in the middle of the reaction section to monitor the changes in reactant concentration in real time. The conversion rate is predicted (prediction accuracy ±1%) using the PLS (partial least squares regression) model for process analysis. An online TOC analyzer (detection limit 1ppb) and a dielectric constant sensor (resolution 0.01Dk) are installed at the outlet of the finished product tank. When TOC ≥ 5ppb or the dielectric constant deviates from the standard value (2.55±0.02), the reflux valve is automatically triggered (response time ≤10s) for quality control.

[0059] (2) Digital Twin Model: A full-process model was established based on process simulation software (AspenPlus), and real-time data (temperature, pressure, and flow) were synchronized every 5 minutes. The reaction temperature and feed ratio were optimized through model predictive control (MPC), so that the ethanol conversion rate was stabilized at above 99.8% (standard deviation ≤ 0.1%).

[0060] Step 5: Regeneration of the catalyst is achieved through pulse acid washing and microwave activation.

[0061] (1) Pulse pickling, using "segmented pickling + ultrasonic assistance": first rinse with deionized water (60℃, conductivity ≤1μS / cm) at a flow rate of 2BV / h for 2 hours, then use a mixed solution of 5% nitric acid + 0.1% hydrofluoric acid (temperature 70℃) for pulse injection (pulse frequency 1Hz, cycle 30 minutes), and increase the ultrasonic power to 2kW / ㎡ to dissolve the carbon deposits in the catalyst pores (the amount of carbon deposits detected by the burning method is ≤0.5wt%).

[0062] (2) Microwave activation: Microwave heating (frequency 2.45 GHz, power 10 kW) is used in the thermal regeneration stage, with a heating rate of 10°C / min to 500°C and a constant temperature of 3 hours (the traditional heating method takes 6 hours). The bed temperature uniformity is monitored by an infrared thermal imager (temperature difference ≤ 5°C). The acid recovery rate of the catalyst after regeneration is ≥ 95% (NH3-TPD detection).

[0063] Step 6: Waste heat recovery and exhaust gas deep treatment, specifically including: (1) Waste heat is recovered as the top steam (65℃) of the reactive distillation tower is used to preheat the raw ethanol (from 25℃ to 50℃), with a heat exchange efficiency of ≥90%; the bottom liquid (80℃) of the deheaving tower is heated to the feed of the light deheaving tower through a plate heat exchanger, saving 20% of steam consumption annually.

[0064] (II) Exhaust gas deep treatment, using the "condensation + activated carbon fiber adsorption + catalytic combustion" combined process: first through the cryogenic unit (-70 ℃) to recover more than 95% of the organic matter, the remaining exhaust gas through the activated carbon fiber bed (space velocity 2000h -1 ) after adsorption, it enters the RCO (regenerative catalytic oxidation) device (catalytic temperature 250℃, removal rate ≥99%), and the final VOCs concentration at the emission port is ≤10mg / m³.

[0065] In addition, there are targeted technical diagnostic methods and treatment measures for abnormal phenomena, as shown in Table 1.

[0066]

[0067] In different process links, different indicators are tested to ensure that they are within the allowable range of key parameters, as shown in Table 2 below.

[0068]

[0069] In summary, through wet filling and ultrasonic vibration, the mass transfer efficiency is improved and the bed pressure drop is reduced; through heat pump distillation and APC dynamic optimization, energy consumption is reduced compared with traditional processes, and the separation efficiency is improved; through digital twins and MPC, closed-loop precise control of conversion rate and purity is achieved.

[0070] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A continuous process for preparing electronic-grade ethyl acetate based on reactive distillation, characterized in that: Reactive distillation technology is used to integrate the transesterification reaction and distillation separation of methyl acetate and ethanol into the same column. The process involves carrying out the transesterification reaction and preliminary separation from the raw material tank area to the reactive distillation tower, separating the light component methanol and unreacted methyl acetate in the light removal tower, deeply purifying them in the heavy removal tower, and finally collecting them in the finished product tank. The overhead by-products of the light removal tower are processed by a recovery system and then returned to the raw material tank area for recycling. The temperature, pressure, and purity parameters are monitored in real time and adjusted in a coordinated manner through an online monitoring and control system to form a closed-loop control system. The specific steps are: S1. Preparation before driving; S2, feeding and reaction control; S3, multi-stage separation and purification; S4, online monitoring and intelligent control; S5, catalyst regeneration; S6. Waste heat recovery and exhaust gas treatment.

2. The process for continuously preparing electronic-grade ethyl acetate based on reactive distillation according to claim 1, wherein Preparations before driving include: S11. Catalyst loading and pretreatment: calcine H-ZSM-5 zeolite molecular sieve at 550°C for 6 hours, pass through a 20-40 mesh sieve after cooling, and inject into the reaction zone using a "wet loading" method with a loading density of 650-700 kg / m³. 304 stainless steel wire mesh and ceramic inert fillers are laid on the top and bottom of the bed. S12. Equipment air tightness test: Helium mass spectrometry leak detection leakage rate ≤5×10 -9 mbar·L / s, the hydraulic test pressure is 1.5 times the operating pressure, and the pressure drop is ≤0.5%; S13, raw material pretreatment: remove metal ions through chelating resin column, and control the ethanol water content ≤100ppm and methyl acetate water content ≤50ppm through molecular sieve adsorber.

3. The continuous preparation process for electronic-grade ethyl acetate based on reactive distillation according to claim 1, wherein Feed and reaction control includes: S21, ethanol feed is controlled by a Coriolis mass flowmeter and an electro-hydraulic servo valve in cascade, and the feed rate is automatically adjusted when the temperature fluctuates by ±0.5°C; methyl acetate gasification controls the gas phase superheat at 10-15°C and the superficial gas velocity at 0.8-1.2m / s; S22. The catalyst bed in the reaction section adopts a "three-stage distribution": the upper layer is filled with θ-ring packing, the middle section is filled with catalyst and packing alternately, and the lower distillation section uses structured packing and is equipped with an ultrasonic vibrator.

4. The process for continuously preparing electronic-grade ethyl acetate based on reactive distillation according to claim 1, wherein The multi-stage separation and purification steps include: S31, the light removal tower uses 50 layers of high-efficiency float valve trays and adopts heat pump distillation technology. The ethanol-water azeotrope produced by the side line is treated by the molecular sieve membrane dehydration unit and then returned to the reactive distillation tower; The S32 deweighting tower uses stainless steel wire mesh corrugated packing, and the reflux ratio is dynamically optimized through an open source cache acceleration tool. The terminal filtration uses a 1μm sintered metal filter element and a 0.2μm polytetrafluoroethylene pleated filter element. S33, by-product recovery system adopts the three-stage process of "cryogenic condensation - fractional distillation purification - adsorption drying".

5. The continuous preparation process of electronic-grade ethyl acetate based on reactive distillation according to claim 1, wherein Online monitoring and intelligent control include: S41. A fiber optic spectrometer is installed in the middle of the reaction section to predict the conversion rate using a partial least squares regression model. An online TOC analyzer and a dielectric constant sensor are installed at the outlet of the finished product tank to automatically trigger reflux when the threshold is deviated. S42. Build a digital twin model based on process simulation software, synchronize real-time data every 5 minutes, and optimize reaction temperature and feed ratio through model predictive control.

6. The process for continuously preparing electronic-grade ethyl acetate based on reactive distillation according to claim 1, wherein Catalyst regeneration includes: S51, pulse pickling: first rinse with deionized water for 2 hours, then use a mixture of 5% nitric acid and 0.1% hydrofluoric acid combined with ultrasonic assistance to remove carbon deposits; S52. Microwave activation: microwave at a frequency of 2.45 GHz, a power of 10 kW, a heating rate of 10°C / min to 500°C, and constant temperature heating for 3 hours.

7. The process for continuously preparing electronic-grade ethyl acetate based on reactive distillation according to claim 1, wherein Waste heat recovery and exhaust gas treatment include: S61, the overhead steam of the reactive distillation tower preheats the raw material ethanol, and the bottom liquid of the heavy removal tower heats the feed of the light removal tower; S62, the waste gas is treated by "cryogenic condensation, activated carbon fiber adsorption and catalytic combustion".

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