Preparation process of vinyl ethyl ether

Abstract

The invention relates to the field of material science and engineering, and particularly discloses a preparation process of vinyl ethyl ether. The process comprises the following steps: conveying acetylene and an ethanol catalyst solution into a micro-packed bed reactor for continuous gas-liquid reaction, carrying out gas-liquid separation on a reaction solution, feeding the reaction solution into an extractive distillation tower, carrying out separation and purification under the action of an extraction agent, strengthening gas-liquid mass transfer by using a micropore structure of a micro-packed bed, and realizing efficient conversion under mild pressure, the acetylene explosion risk is obviously reduced; the residence time is accurately controlled, so that acetalation and self-polymerization side reactions are effectively inhibited, and the problem of scaling of the reactor is solved; besides, the relative volatility of components is changed by utilizing an extractive distillation technology, an azeotropic system of vinyl ethyl ether and ethanol is broken, and a product with higher purity can be directly obtained without water washing; according to the process, the problems of poor mass transfer, low safety and difficulty in azeotropic separation of a traditional kettle method are solved, and intrinsically safe and stable production is realized.

Description

Technical Field

[0001] This application relates to the field of materials science and engineering, and more specifically, to a process for preparing vinyl ethyl ether. Background Technology

[0002] Vinyl ethyl ether is an important organic chemical intermediate and fine chemical raw material. Due to the presence of reactive vinyl and ethoxy groups in its molecular structure, it exhibits unique chemical properties in polymerization reactions and organic synthesis. Industrially, vinyl ethyl ether is widely used in the production of glutaraldehyde, fragrances, lubricant additives, and specialty coatings; it is also a key raw material for the synthesis of pharmaceuticals and pesticides. Currently, the mainstream industrial process for preparing vinyl ethyl ether is based on the Rapa process, which uses acetylene and anhydrous ethanol as raw materials, and synthesizes vinyl ethyl ether through a nucleophilic addition reaction in the liquid phase in the presence of a strong base catalyst. This reaction is a gas-liquid heterogeneous exothermic reaction.

[0003] Existing industrial production technologies for vinyl ethyl ether typically employ a traditional stirred tank reactor combined with a conventional distillation column. The specific process usually involves: dissolving potassium hydroxide in excess anhydrous ethanol to prepare a catalyst solution, which is then loaded into a reactor equipped with a mechanical stirrer and a heating jacket; subsequently, acetylene gas is bubbled into the bottom of the reactor through a distributor. Under pressurized and heated conditions, the acetylene bubbles react with the ethanol in the liquid phase as they rise. The resulting crude product then enters a distillation unit, where the boiling point difference between vinyl ethyl ether and ethanol is utilized to separate them using a conventional plate or packed column. The product is collected at the top of the column, while the unreacted ethanol at the bottom is recycled.

[0004] In existing technologies, the large bubbles generated by stirring in traditional batch reactors result in a small gas-liquid contact area and low conversion rates due to limitations in mass transfer control. To maintain production capacity, high-temperature and high-pressure processes are forced, which not only increases energy consumption but also significantly raises the safety hazard of acetylene decomposition explosions. Furthermore, vinyl ether exhibits an azeotropic phenomenon with the raw material ethanol, which cannot be separated by conventional distillation due to thermodynamic limitations, leading to lengthy processes and large amounts of wastewater. Secondly, the prolonged residence time of products in the batch reactor under high-temperature and strong alkaline conditions makes them highly susceptible to secondary addition or self-polymerization reactions. This not only reduces selectivity and yield but also causes scaling in the reactor, shortening the equipment's operating cycle. Summary of the Invention

[0005] To address the problems of large bubbles, small gas-liquid contact area, and low conversion rate caused by mass transfer control limitations in traditional batch reactors, this application provides a process for preparing vinyl ethyl ether.

[0006] The first aspect of this invention provides a method for the continuous preparation and separation of vinyl ethyl ether, the method comprising the following steps:

[0007] Raw material pretreatment: The alkaline catalyst is dissolved in ethanol to prepare a reaction liquid phase;

[0008] Continuous synthesis reaction: Acetylene gas and the reaction liquid phase are fed into a micro packed bed reactor through a feeding device, and the gas-liquid two-phase continuous contact reaction is carried out under the action of a catalyst to obtain a crude reaction mixture containing vinyl ethyl ether, unreacted ethanol and acetylene.

[0009] Gas-liquid separation: The crude reaction mixture is subjected to gas-liquid separation. The separated gas phase is recycled or recovered, while the liquid phase enters the subsequent separation stage.

[0010] Extractive distillation separation: The liquid phase after gas-liquid separation is passed into an extractive distillation column. The extractant is used to change the relative volatility of vinyl ether and ethanol, breaking the azeotropic system. High-purity vinyl ether product is collected from the top of the column, and a mixture containing ethanol and extractant is collected from the bottom of the column.

[0011] The micro-packed bed reactor is filled with packing material with micron- to millimeter-sized pore structures, cutting the macroscopic gas-liquid two-phase flow into micron-sized microfluids. This structure significantly increases the specific surface area of ​​the gas and liquid phases, enhancing the interphase mass transfer process. Since the reaction of acetylene in ethanol is mass-transfer controlled, the significant improvement in mass transfer efficiency allows the reaction to proceed efficiently under relatively mild temperature and pressure conditions, thus avoiding the explosion risk associated with high-pressure acetylene. Simultaneously, the micro-packed bed reactor possesses excellent heat exchange performance, effectively removing reaction heat and preventing localized overheating, fundamentally improving process safety.

[0012] Furthermore, through precise control of the continuous flow process, the residence time distribution of reactants in the micro-packed bed reactor is extremely narrow, and the residence time can be precisely controlled on the order of seconds or minutes. This mode of immediate reaction and separation or short residence time effectively suppresses the secondary addition and self-polymerization reactions of vinyl ethyl ether in alkaline alcohol solutions caused by prolonged heating, significantly improving the selectivity and yield of the target product, while solving the reactor scaling problem and extending the equipment operating cycle.

[0013] For the azeotropic system formed by vinyl ethyl ether and ethanol, this invention introduces a specific extractant. This extractant exhibits a strong interaction with ethanol molecules, significantly reducing the volatility of ethanol in the mixture and thus increasing the relative volatility between vinyl ethyl ether and ethanol. This allows vinyl ethyl ether to be distilled off the top of the column in high purity, overcoming the limitations of thermodynamic gas-liquid equilibrium. Higher purity products can be obtained without cumbersome water washing steps, significantly shortening the process and reducing wastewater discharge.

[0014] Preferably, the packing material in the micro-filled bed reactor is one or more combinations of foamed metal, wire mesh corrugated packing, or static mixing elements.

[0015] Preferably, the extractant is selected from one or a combination of glycols, amides, or ionic liquids.

[0016] A second aspect of the present invention provides a continuous production system for vinyl ethyl ether for implementing the above-described method, mainly comprising:

[0017] Feeding unit: used for precise metering and delivery of acetylene gas and ethanol catalyst solution;

[0018] Micro-packed bed reaction unit: includes at least one micro-packed bed reactor, used to provide gas-liquid enhanced mass transfer and reaction site;

[0019] Gas-liquid separation unit: connected to the outlet of the reaction unit, used to separate unreacted gases;

[0020] Extractive distillation unit: includes an extractive distillation column and a solvent recovery column, used to achieve high-purity separation of products and recycling of extractants.

[0021] In summary, this application has the following beneficial effects:

[0022] 1. This invention employs micro-filled bed continuous reaction technology, utilizing the microporous structure of the packing material to cut and disperse the macroscopic gas-liquid fluid, significantly increasing the specific surface area of ​​acetylene and the reaction liquid phase, and enhancing the mass transfer-controlled gas-liquid reaction process. This enhanced mass transfer effect enables the reaction to proceed efficiently under relatively mild temperature and pressure conditions, avoiding the decomposition and explosion risks brought about by maintaining a high-pressure acetylene environment in pursuit of conversion rate in traditional batch processes, thus achieving inherent safety in the production process and reducing system energy consumption.

[0023] 2. This invention employs an extractive distillation process, which significantly alters the activity coefficient of ethanol in the mixed system by adding a specific extractant, thereby increasing the relative volatility of vinyl ether and ethanol. This effectively breaks the thermodynamic azeotropic limitation. This method eliminates the need for traditional, cumbersome water washing or complex chemical treatment steps, allowing for the direct acquisition of a higher purity product from the top of the column. It not only shortens the process flow but also reduces wastewater generation at the source, resulting in significant environmental benefits.

[0024] 3. This invention achieves precise control and an extremely narrow residence time distribution of reactants within the reactor through a continuous flow reaction mode. This immediate reaction and separation mode effectively avoids the prolonged residence of the generated vinyl ether in a high-temperature alkaline environment, thereby significantly suppressing side reactions such as acetalization secondary addition and self-polymerization to form resinous polymers. This not only greatly improves the selectivity and yield of the target product but also solves the problem of scaling and clogging on the reactor wall, extending the continuous operation cycle of the equipment. Attached Figure Description

[0025] Figure 1 This is a flowchart of a preparation process for vinyl ethyl ether provided in this application. Detailed Implementation

[0026] The following is in conjunction with the appendix Figure 1 The present application will be further described in detail with reference to the embodiments.

[0027] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0028] Anhydrous ethanol: analytical grade, purity ≥99.7%; Uses: reaction raw material and solvent.

[0029] Acetylene: High-purity gas, 99.9% purity, used as a reaction feedstock.

[0030] Potassium hydroxide; industrial grade caustic soda flakes, purity ≥90.0%; Uses: preparation of potassium ethoxide catalyst.

[0031] Diethylene glycol: analytical grade, purity ≥99.0%; Uses: extractant and distillation solvent.

[0032] N-Methylpyrrolidone: Analytical grade, purity ≥99.5%; Uses: Extractive distillation solvent.

[0033] Ethylene glycol: analytical grade, purity ≥99.5%; Uses: extractant and distillation solvent.

[0034] n-Butanol: Chromatographic grade; Uses: Internal standard for gas chromatography analysis.

[0035] Acetone: analytical grade; uses: cleaning scale and solvent collection.

[0036] Example 1: This example provides a continuous preparation and separation method for vinyl ethyl ether. See [link to example]. Figure 1 The specific steps are as follows:

[0037] Raw material pretreatment: Dissolve potassium hydroxide in anhydrous ethanol to prepare a 20% (w / w) ethanol-potassium hydroxide catalyst solution as a liquid phase raw material.

[0038] Continuous synthesis reaction: Acetylene gas is simultaneously delivered to a micro-packed bed reactor via a mass flow controller and catalyst solution via a high-pressure metering pump. The reactor is filled with nickel foam packing material with a porosity of 90%. The reaction conditions are controlled as follows: system pressure 1.8 MPa, reaction temperature 150 °C, acetylene to ethanol molar ratio 1.2:1, and liquid phase residence time in the reactor 5 minutes.

[0039] Gas-liquid separation: The reaction effluent enters the gas-liquid separator. The separated unreacted acetylene gas is compressed and purified before being recycled back to the reaction inlet, while the liquid products enter the intermediate storage tank.

[0040] Extractive distillation separation: The liquid phase after gas-liquid separation is passed into the middle of the extractive distillation column, while the extractant diethylene glycol is introduced from the top of the column. The mass ratio of extractant to crude product is controlled at 3:1, the reflux ratio at 2:1, and the operating pressure at the top of the column is atmospheric pressure. A colorless, transparent liquid product is collected from the top of the column by condensation.

[0041] Example 2: This example provides a continuous preparation and separation method for vinyl ethyl ether, the specific steps of which are as follows:

[0042] Raw material pretreatment: Dissolve potassium hydroxide in anhydrous ethanol to prepare a 20% (w / w) ethanol-potassium hydroxide catalyst solution as a liquid phase raw material.

[0043] Continuous synthesis reaction: Acetylene gas is simultaneously delivered to a micro-packed bed reactor via a mass flow controller and catalyst solution via a high-pressure metering pump. The reactor is filled with nickel foam packing material with a porosity of 90%. The reaction conditions are controlled as follows: system pressure 1.6 MPa, reaction temperature 145℃, acetylene to ethanol molar ratio 1.2:1, and liquid phase residence time in the reactor 8 minutes.

[0044] Gas-liquid separation: The reaction effluent enters the gas-liquid separator. The separated unreacted acetylene gas is compressed and purified before being recycled back to the reaction inlet, while the liquid products enter the intermediate storage tank.

[0045] Extractive distillation separation: The liquid phase after gas-liquid separation is passed into the middle of the extractive distillation column, while the extractant *N-methylpyrrolidone is introduced from the top of the column. The mass ratio of extractant to crude product is controlled at 3:1, the reflux ratio at 2:1, and the operating pressure at the top of the column is atmospheric pressure. A colorless, transparent liquid product is collected from the top of the column by condensation.

[0046] Example 3: This example provides a continuous preparation and separation method for vinyl ethyl ether, the specific steps of which are as follows:

[0047] Raw material pretreatment: Dissolve potassium hydroxide in anhydrous ethanol to prepare a 15% (w / w) ethanol-potassium hydroxide catalyst solution as a liquid phase raw material.

[0048] Continuous synthesis reaction: Acetylene gas is simultaneously delivered to a micro-packed bed reactor via a mass flow controller and catalyst solution via a high-pressure metering pump. The reactor is filled with nickel foam packing material with a porosity of 90%. The reaction conditions are controlled as follows: system pressure 2.0 MPa, reaction temperature 150℃, acetylene to ethanol molar ratio 1.2:1, and liquid phase residence time in the reactor 3 minutes.

[0049] Gas-liquid separation: The reaction effluent enters the gas-liquid separator. The separated unreacted acetylene gas is compressed and purified before being recycled back to the reaction inlet, while the liquid products enter the intermediate storage tank.

[0050] Extractive distillation separation: The liquid phase after gas-liquid separation is passed into the middle of the extractive distillation column, while the extractant ethylene glycol is simultaneously introduced from the top of the column. The mass ratio of extractant to crude product is controlled at 3:1, the reflux ratio at 2:1, and the operating pressure at the top of the column is atmospheric pressure. A colorless, transparent liquid product is collected by condensation from the top of the column.

[0051] Comparative Example 1: Compared with Example 1, the difference is that the micro-filled bed continuous reaction system was replaced with a traditional high-pressure autoclave reactor, the reaction mode was changed from continuous flow to batch operation, the reaction pressure was set to 3.0 MPa, and the reaction time was extended to 4 hours. The other raw material ratios and post-processing methods are the same.

[0052] Comparative Example 2: Compared with Example 1, the difference is that diethylene glycol was not added as an extractant in the extractive distillation section, and the reaction solution was directly sent to the distillation column for ordinary distillation separation. All other aspects are the same.

[0053] Comparative Example 3: Compared with Example 1, the difference is that no microstructured packing material was filled inside the reactor, while the other process parameters and steps are the same.

[0054] Experiment 1: Reaction Performance and Safety Tests. This experiment aims to verify the effects of different reactor configurations and process conditions on the efficiency, product distribution, and system operating pressure of the heterogeneous gas-liquid reaction between acetylene and ethanol. The specific experimental steps are as follows:

[0055] Start the reaction apparatus of Examples 1, 3, Comparative Example 1, and Comparative Example 3. Feed materials are introduced according to the set temperature, pressure, and flow rate conditions, and the system is run continuously. Once the temperature and pressure sensor readings of the continuous flow system fluctuate within ±1%, it is considered to have reached a steady state, and timing and sampling begin.

[0056] Precision pressure sensors installed at the reactor inlet and outlet continuously record system operating pressure data during the reaction process, and the average pressure value during stable operation is taken as the recorded data.

[0057] For continuous flow systems, in Examples 1, 3 and Comparative Example 3, the reaction mixture was collected at the reactor outlet sampling valve using a sealed sampling bottle.

[0058] For batch reactor systems, samples are taken after the reaction has finished and the system has been cooled to room temperature.

[0059] Internal standards were added immediately after sampling, and quantitative analysis was performed using a gas chromatograph equipped with a flame ionization detector and a capillary column.

[0060] Based on the chromatographic peak area and correction factor, calculate the ethanol conversion rate and the selectivity of vinyl ether.

[0061] The test results are shown in Table 1 below:

[0062] Experimental group reactor configuration Operating pressure (MPa) Dwell / Reaction Time Ethanol conversion rate (%) Vinyl ethyl ether selectivity (%) Example 1 Microfilled bed 1.82 5min 96.43 98.17 Example 3 Microfilled bed 2.03 3min 95.91 98.64 Comparative Example 1 Kettle Mixer 3.05 4h 94.12 86.48 Comparative Example 3 Empty pipe continuous 1.81 5min 35.24 97.05

[0063] Analysis of the data in Table 1 shows that Examples 1 and 3, using micro-packed bed reactors, achieved high ethanol conversion rates at lower operating pressures, significantly outperforming Comparative Example 3 under the same pressure and residence time. This result confirms that the microstructured packing material inside the micro-packed bed has a significant cutting and dispersing effect on the gas-liquid two-phase fluid. Since the reaction process of acetylene in ethanol is controlled by gas-liquid mass transfer, the presence of the packing material breaks down macroscopic bubbles into microbubbles, greatly increasing the specific surface area of ​​gas-liquid contact, thereby enhancing the interphase mass transfer rate. In contrast, Comparative Example 3 lacks the disturbance of the packing material, resulting in laminar or slug-like gas-liquid flow with limited contact area, leading to a very low conversion rate that cannot meet the needs of industrial production.

[0064] Regarding product selectivity, Examples 1 and 3 both maintained above 98%, while Comparative Example 1, although achieving a similar conversion rate by increasing pressure and extending reaction time, only achieved a selectivity of 86.48%. This is because vinyl ether is chemically reactive and readily undergoes secondary addition to form acetaldehyde diethyl acetal or self-polymerization under high-temperature alkaline conditions and prolonged residence. The continuous flow process employed in this invention has precise residence time control capabilities, enabling immediate reaction and separation of reactants. It reduces the heating time of the product in the high-temperature zone from hours in Comparative Example 1 to minutes, effectively blocking side reaction pathways and significantly improving the yield of the target product.

[0065] Furthermore, a comparison of safety data shows that Example 1 achieves excellent reaction performance at a pressure of 1.82 MPa, while Comparative Example 1 requires increasing the operating pressure to 3.05 MPa to overcome the low mass transfer efficiency of the batch reactor. In acetylene chemical production, higher operating pressures mean an exponential increase in the risk of acetylene decomposition explosion. This invention, by enhancing the mass transfer mechanism, enables the reaction to proceed efficiently under relatively mild pressure conditions, thereby reducing the system's energy level and safety hazards from a process principle perspective, and achieving inherently safe production.

[0066] Experiment 2: Product Purity and Separation Efficiency Test. This experiment aims to verify the separation efficiency of the extractive distillation unit in breaking the azeotropic system of vinyl ether and ethanol and improving product purity; the specific experimental steps are as follows:

[0067] Once the distillation systems of Examples 1, 2, and 2 reach thermal equilibrium (i.e., the fluctuations in the top temperature, bottom temperature, and reflux tank level are all less than ±0.5%), liquid samples are collected from the top reflux line of the distillation column of each experimental setup using a micro-injection needle.

[0068] Start the gas chromatograph equipped with a flame ionization detector and a polar capillary column. Set the injection port temperature to 200℃, the detector temperature to 250℃, and the column oven temperature program to: initial temperature 40℃, hold for 3 minutes, then increase to 150℃ at a rate of 10℃ / min.

[0069] The collected samples were injected into the gas chromatograph at a volume of 0.2 μL and a split ratio of 50:1. The chromatographic elution curves were recorded, and the main peak of vinyl ether and impurity peaks such as ethanol, acetaldehyde, and diethyl acetal were identified.

[0070] The mass percentage of each component in the product was calculated using the area normalization method, and the average value was taken as the final determination result after three repeated injections.

[0071] The test results are shown in Table 2 below:

[0072] test group Separation process type Types of extractants Vinyl ethyl ether purity (wt%) Ethanol residue (wt%) Other impurities content (wt%) Example 1 Extractive distillation diethylene glycol 99.82 0.09 0.09 Example 2 Extractive distillation NMP 99.64 0.14 0.22 Comparative Example 2 Ordinary distillation none 95.31 4.43 0.26

[0073] As shown in Table 2, in Comparative Example 2, without the addition of an extractant, despite using the same number of trays and reflux ratio as the Example, the purity of vinyl ethyl ether in the product collected from the top of the column remained consistently around 95.31%, with 4.43% ethanol remaining. This data is highly consistent with the azeotropic composition of the vinyl ethyl ether-ethanol binary system under normal pressure, confirming that under conventional distillation mode, the compositional difference between the gas and liquid phases is limited by thermodynamic gas-liquid equilibrium. When the ethanol concentration decreases to near the azeotropic point, the relative volatility of the two components approaches 1, making deep separation of the two impossible in ordinary distillation.

[0074] In contrast, Examples 1 and 2 successfully broke the original gas-liquid equilibrium limitations by continuously introducing diethylene glycol or N-methylpyrrolidone as extractants at the top of the distillation column. The mechanism lies in the fact that the selected extractant molecules have strong polarity, enabling them to form strong intermolecular interactions with ethanol molecules. This significantly reduces the activity coefficient of ethanol in the mixed liquid phase while increasing the relative volatility between vinyl ether and ethanol. This change in relative volatility makes vinyl ether the only light component in the system, allowing it to be easily distilled off at high purity from the top of the column, while ethanol is carried by the extractant and remains in the liquid phase flowing to the bottom of the column.

[0075] Test results show that using this extractive distillation process, vinyl ether products with a purity exceeding 99.5% can be directly obtained without the need for additional water washing, alcohol removal, or chemical treatment units, while the residual ethanol content is controlled below 0.15%. This physical separation method, which changes the relative volatility between components, not only solves the technical bottleneck of traditional processes where product purity is difficult to exceed 97%, but also avoids the wastewater treatment load caused by introducing a water washing process, achieving high efficiency and cleanliness in the separation process.

[0076] Experiment 3: Long-Term Operation Stability and Scaling Test. This experiment aims to examine the system stability of this continuous production process under long-term operating conditions and to verify the technical effectiveness of the micro-packed bed reactor in suppressing the deposition of by-reaction products and preventing equipment scaling. The specific experimental steps are as follows:

[0077] The micro-packed bed reaction system described in Example 1 was started, with the reaction temperature set at 150°C and the system back pressure at 1.8 MPa. After reaching steady state, continuous feeding was maintained for 200 hours. During this period, the pressure drop of the reactor bed was recorded every 12 hours using high-precision differential pressure transmitters connected to the reactor inlet and outlet.

[0078] Start the high-pressure reactor system described in Comparative Example 1, and set the same reaction temperature and catalyst concentration. Repeat batch reactions, with each batch having a reaction time of 4 hours, for a total of 50 batches, for a total effective reaction time of 200 hours.

[0079] After the experiment was completed, the residual liquid in each reactor was drained and purged with nitrogen to dry. The micro-packed bed reactor of Example 1 and the reaction vessel of Comparative Example 1 were disassembled, and the solid deposits on the inner wall of the reactor, the stirring blades, and the surface of the packing were visually inspected.

[0080] Solid residues adhering to the inside of each device were collected using a scraper, washed with acetone, vacuum dried, weighed, and the scale mass was recorded.

[0081] The test results are shown in Table 3 below:

[0082] Runtime (h) / batch Example 1 - Reactor Pressure Drop (ΔP, kPa) Example 1 - Description of the appearance of the inner wall and packing Comparative Example 1 - Description of the internal appearance of the vessel Start (0h) 15.2 Metallic luster, clean Metallic luster, clean 50h / Batch 12 15.3 -- Pale yellow spots appeared on the pot wall 100h / Batch 25 15.4 -- The agitator is covered with viscous substances 150h / Batch 37 15.2 -- Obvious resinous solid deposits 200h / 50th batch 15.6 -- Brown, hard scale buildup at the bottom Final scale dry weight (g) 0.12 No obvious coverage on the metal surface 18.45

[0083] According to the monitoring data in Table 3, the bed pressure drop of the micro-packed bed reactor used in Example 1 remained within a narrow fluctuation range of 15.2 kPa to 15.6 kPa during the continuous operation for 200 hours, without any significant pressure rise trend. Final disassembly and inspection showed that the surface of the microstructured packing remained clean, with only a trace amount of residue (0.12 g). This indicates that under these process conditions, the fluid flowed smoothly inside the reactor, without channel blockage or reduced flow area due to polymer deposition, demonstrating the excellent long-term operational stability of this continuous flow process.

[0084] In contrast, the batch reactor in Comparative Example 1, after accumulating the same operating time, produced 18.45g of brown solid scale inside, and a large amount of resinous material adhered to the reactor wall and agitator. Analysis of the reaction mechanism reveals that vinyl ether is highly reactive in strongly alkaline ethanol solutions. If exposed to high temperatures for extended periods, it readily undergoes intermolecular self-polymerization or acetalization with ethanol, generating high-boiling-point viscous polymers. Traditional batch reactor processes, due to severe backmixing of reactants and residence times lasting several hours, objectively provide a time window for these successive side reactions, leading to the continuous nucleation, growth, and deposition of polymers on the reactor wall surface, ultimately forming a hard scale that is difficult to remove.

[0085] This invention utilizes micro-filled bed reaction technology, leveraging the fluid-splitting effect of its internal packing material to achieve a near-plug flow pattern, significantly narrowing the material residence time distribution. By precisely controlling the heating time of the reaction liquid in the high-temperature zone to the minute level, the reaction system is removed from the reactor and enters the subsequent separation stage before side reactions occur. This short residence time and no backmixing kinetic characteristic fundamentally cuts off the reaction path of vinyl ether to resinous polymer, effectively solving the equipment scaling and pipeline blockage problems commonly found in traditional processes, and significantly reducing the frequency of equipment maintenance and downtime cleaning costs.

[0086] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A process for preparing vinyl ethyl ether, characterized in that, The process includes the following steps: S1. Dissolve potassium hydroxide in ethanol solvent to prepare a catalyst solution; S2. The catalyst solution and acetylene gas are simultaneously introduced into the external circulation injection loop reaction system. The acetylene gas is sheared and dispersed in the liquid phase using an injector to form a gas-liquid mixture, and the vinylization reaction is carried out in a tubular reactor. S3. The gas-liquid mixture after the reaction is sent to a gas-liquid separator for flash evaporation separation. The crude gas phase containing vinyl ether and ethanol is collected from the top of the device, and the liquid phase is discharged from the bottom of the device and recycled back to step S2. S4. The crude gaseous product is fed into an extractive distillation column, and an extractant is sprayed into the column for continuous extractive distillation. The vinyl ether product is collected from the top of the column.

2. The preparation process of vinyl ethyl ether according to claim 1, characterized in that, In step S1, a phase transfer catalyst is also added to the catalyst solution. The phase transfer catalyst is selected from one or a combination of several of polyethylene glycol dimethyl ether, 18-crown-6, and 15-crown-5.

3. The preparation process of vinyl ethyl ether according to claim 2, characterized in that, The phase transfer catalyst has a mass fraction of 0.5% to 2.0% in the catalyst solution.

4. The preparation process of vinyl ethyl ether according to claim 1, characterized in that, In step S2, the external circulation injection loop reaction system includes a circulation pump, a Venturi injector, and a tubular reactor connected in sequence; the catalyst solution is pressurized by the circulation pump and ejected through the nozzle of the Venturi injector, forming a negative pressure at the throat of the Venturi injector and drawing in acetylene gas.

5. The preparation process of vinyl ethyl ether according to claim 4, characterized in that, In step S2, the temperature of the vinylation reaction is controlled within the range of 130°C to 160°C, and the reaction pressure is controlled within the range of 1.0 MPa to 2.0 MPa.

6. The preparation process of vinyl ethyl ether according to claim 1, characterized in that, In step S3, the gas-liquid separation device is a flash tank, and the operating temperature of the flash separation is controlled within the range of 140°C to 160°C, and the operating pressure is atmospheric pressure or a slight positive pressure of 0.01MPa to 0.05MPa.

7. The preparation process of vinyl ethyl ether according to claim 1, characterized in that, In step S4, the extractant is selected from one or a combination of several of ethylene glycol, diethylene glycol, dimethyl sulfoxide, and N-methylpyrrolidone.

8. The preparation process of vinyl ethyl ether according to claim 7, characterized in that, In step S4, the extractant enters from the top of the extractive distillation column, and the crude gaseous product enters from the middle and lower part of the extractive distillation column. The mass feed ratio of the extractant to the crude gaseous product is 1:1 to 3:

1.

9. The preparation process of vinyl ethyl ether according to claim 1, characterized in that, In step S4, before or after extraction, a polymerization inhibitor is continuously injected into the vinyl ethyl ether product. The polymerization inhibitor is triethylamine or potassium hydroxide solid particles.

10. The preparation process of vinyl ethyl ether according to claim 1, characterized in that, The process also includes step S5: the mixture discharged from the bottom of the extractive distillation column in step S4 is sent to the solvent recovery column for distillation and separation, ethanol is recovered from the top of the solvent recovery column and returned to step S1 or step S2 for recycling, and the extractant is recovered from the bottom of the solvent recovery column and returned to step S4 for recycling.

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