Ethyl acetate esterification synthesis method based on microwave enhancement

Abstract

The invention belongs to the technical field of ethyl acetate preparation, and provides an ethyl acetate esterification synthesis method based on microwave strengthening, which comprises the following steps: step 1, acidifying modified montmorillonite, carrying out suction filtration, drying, calcining in a closed muffle furnace, and cooling to obtain a catalyst; 2, ethanol and glacial acetic acid are mixed, the catalyst prepared in the step 1 is added, the mixture is placed in a microwave reactor for a reaction, and a reaction solution is obtained; step 3, after the reaction is finished, cooling to room temperature, adding a reaction solution into a saturated sodium carbonate solution, adjusting the pH value, fully shaking up the solution, standing for layering, and removing a lower water layer; step 4, washing an upper ester layer with a saturated saline solution and a saturated calcium chloride solution, and then drying with anhydrous magnesium sulfate to remove moisture in ethyl acetate; and step 5, distilling the ethyl acetate solution, and collecting fractions at 73-78 DEG C to obtain ethyl acetate.

Description

Technical Field

[0001] This invention belongs to the field of ethyl acetate preparation technology, specifically relating to a microwave-enhanced ethyl acetate esterification synthesis method. Background Technology

[0002] Ethyl acetate is a widely used industrial compound. It possesses excellent solubility and is a fast-drying industrial solvent, widely used in the production of coatings, cellulose acetate, ethyl cellulose, artificial leather, roofing felt colorants, chlorinated rubber, ethylene resins, cellulose acetate resins, and synthetic rubber. It can also be used in the production of liquid nitrocellulose inks for copiers. In the textile industry, it is used as a cleaning agent; in the food industry, it is a crucial flavoring additive, serving as a component of fragrances; ethyl acetate is also used as a binder in printing inks and the production of artificial pearls; it is used as a thinner for paints and as a raw material in the manufacture of pharmaceuticals and dyes. With the rapid development of downstream industries, global demand for ethyl acetate continues to grow; therefore, the research on the synthesis methods of ethyl acetate and its catalysts has been a focus of attention.

[0003] Currently, the mainstream industrial method for producing ethyl acetate is still the traditional acid-catalyzed esterification method using concentrated sulfuric acid as a catalyst. This process involves reacting acetic acid and ethanol under the catalysis of concentrated sulfuric acid at atmospheric pressure and reflux temperature (approximately 70–80°C). The water produced in the reaction forms a low-boiling-point azeotrope with ethanol and ethyl acetate, which is continuously removed from the system by distillation, thereby disrupting the reaction equilibrium and promoting the esterification reaction towards the formation of ethyl acetate, thus increasing the feed conversion rate. To obtain a higher ester yield, methods such as increasing the amount of acid or alcohol and continuously removing ester or water from the product are typically employed. Reflux devices and the use of excess ethanol are generally used to increase the ester yield. Although this traditional process technology is mature, it suffers from several inherent and difficult-to-overcome serious drawbacks: such as excessively high concentrated sulfuric acid concentration causing carbonization of some reactants or products; increasing the amount of reactants to obtain more product, resulting in waste of some reactants; and long reaction times, typically requiring several hours to achieve a high conversion rate, thus hindering production efficiency.

[0004] Therefore, developing a microwave-enhanced ethyl acetate esterification synthesis method is of great significance for reducing energy and material consumption, minimizing environmental pollution, and achieving green and environmentally friendly practices. Summary of the Invention

[0005] To address one of the technical problems mentioned in the background art, this invention provides a microwave-enhanced ethyl acetate esterification synthesis method, which shortens the reaction time, increases the yield and purity, and thus reduces the production cost of ethyl acetate.

[0006] The objective of this invention can be achieved through the following technical solutions: A microwave-enhanced ethyl acetate esterification synthesis method includes the following steps: Step 1: The modified montmorillonite is acidified, then filtered, dried, and calcined in a closed muffle furnace. After cooling, the catalyst is obtained. Acidification of montmorillonite alters its physicochemical properties, effectively enhancing its activity. The K, Na, Ca, Mg, and other cations between the montmorillonite layers are converted into acid-soluble salts and dissolved, thereby weakening the original interlayer bonding force, causing the interlayer lattice to crack and the interlayer spacing to increase. The specific surface area and adsorption capacity of the modified montmorillonite are significantly improved, providing an ideal platform for the loading and dispersion of acidic active sites, providing more active sites, and thus improving the selectivity of the reaction and the purity of the product. Step 2: Mix ethanol and glacial acetic acid, add the catalyst prepared in step 1, and place the mixture in a microwave reactor to react and obtain a reaction solution. Step 3: After the reaction is complete, cool to room temperature, add the reaction solution to a saturated sodium carbonate solution, adjust the pH value, shake the solution thoroughly and let it stand to separate into layers, remove and discard the lower water layer; Step 4: The upper ester layer is washed with saturated brine and saturated calcium chloride solution, and then dried with anhydrous magnesium sulfate to remove water from the ethyl acetate. Step 5: Distill the ethyl acetate solution and collect the fraction at 73-78℃ to obtain ethyl acetate.

[0007] In some embodiments of the present invention, the sulfuric acid solvent used in step 1 for acidification has a concentration of 1 to 1.25 mol / L.

[0008] In some embodiments of the present invention, the calcination temperature in step 1 is 300-600°C and the calcination time is 10-16 hours.

[0009] In some embodiments of the present invention, the preparation steps of the modified montmorillonite in step 1 are as follows: S1. Add montmorillonite to deionized water and ultrasonically disperse for 0.5-1 h. Add FeCl3·6H2O and FeSO4·7H2O and stir for 5-6 h. Adjust the pH value to 11.5-12 with NaOH solution to obtain magnetic montmorillonite solution. S2. Add tetrabutyl titanate to anhydrous ethanol and stir until homogeneous. Add concentrated nitric acid for hydrolysis to obtain TiO2 precursor sol. Then add it dropwise to montmorillonite solution, heat to 70-75℃ and stir for 3-5 hours. Filter, wash until neutral, and dry to constant weight to obtain modified montmorillonite.

[0010] In the above technical solution, magnetic Fe3O4 is first deposited in the interlayer and surface of montmorillonite. The catalyst can be quickly separated from the liquid phase system under the action of an external magnetic field, which helps the catalyst to be separated and recovered. Furthermore, the introduction of Fe3O4 effectively enhances the activity of the catalyst. Then, the TiO2 precursor sol is uniformly dispersed on the surface and interlayer of montmorillonite using the sol method. After acidification and calcination, TiO2 nanoparticles are formed, which can be uniformly dispersed in montmorillonite, thereby further increasing the active centers of the catalyst and promoting the catalyst to have high catalytic activity.

[0011] In some embodiments of the present invention, the ratio of montmorillonite, deionized water, FeCl3·6H2O and FeSO4·7H2O in S1 is 5-5.2g:100mL:3.30-3.35g:1.65-1.68g.

[0012] In some embodiments of the present invention, the ratio of tetrabutyl titanate, anhydrous ethanol, concentrated nitric acid and montmorillonite solution in S2 is 8-10g:10mL:1mL:100mL.

[0013] In some embodiments of the present invention, the molar ratio of ethanol to glacial acetic acid in step 2 is 1:1.2 to 1.5.

[0014] In some embodiments of the present invention, the amount of catalyst used in step 2 is 5% to 10% of the total weight of the raw materials.

[0015] In some embodiments of the present invention, the radiation power in the microwave reactor in step 2 is 350–500 W, the radiation time is 5–8 min, and the radiation temperature is 110–120 °C. Compared with the traditional preparation process that takes 1–2 h for heating and reflux, the core advantage of the present invention lies in the use of microwave heating. By rapidly raising the reactants to a preset high temperature and maintaining precise control, efficient esterification is completed within 5–8 min. This "high temperature, short time" method effectively avoids the reactants and products from remaining in locally overheated areas such as the container wall for extended periods, significantly suppressing decomposition and side reactions, thereby ensuring product purity and yield.

[0016] In some embodiments of the present invention, the pH value is adjusted to 7-8 in step 3.

[0017] The beneficial effects of this invention are: (1) This invention provides a microwave-enhanced ethyl acetate esterification synthesis method. This process utilizes the unique bulk heating and non-thermal effects of microwaves, in conjunction with a montmorillonite catalyst. The montmorillonite catalyst plays a role in increasing the reaction rate and reducing local overheating, thus achieving high efficiency, energy saving, and controllability of the reaction process. Compared with traditional methods, this process has significant advantages such as fast reaction rate, low energy consumption, and high yield, providing a new path for reducing the production cost of ethyl acetate.

[0018] (2) This invention employs precipitation and sol-gel methods to load Fe3O4 and TiO2 precursors onto montmorillonite, followed by acidification and calcination to prepare a magnetic montmorillonite catalyst. The prepared montmorillonite catalyst exhibits high catalytic activity, strong magnetic properties, and excellent stability. The introduction of Fe3O4 increases the catalyst's activity, and the catalyst is also easier to recover under an external magnetic field. The TiO2 nanoparticles are highly dispersed on the montmorillonite surface, increasing the number of catalytic active centers and thus giving the catalyst high catalytic activity. When used to catalyze the synthesis of ethyl acetate, it can effectively improve the reactivity, esterification rate, yield, and purity of ethyl acetate. Furthermore, the catalyst provided by this invention has excellent properties such as strong acidity, good stability, easy product separation, and reusability, effectively promoting the esterification reaction of ethanol and glacial acetic acid to prepare ethyl acetate with high yield and high purity.

[0019] (3) This invention provides a microwave-enhanced ethyl acetate esterification synthesis method. Compared with the traditional heating synthesis method, the microwave radiation method can achieve a higher yield and shorten the reaction time of ethyl acetate. Moreover, the operation is simple and the reaction speed is fast, which shows the advantages of saving time and energy, and has certain social and economic benefits. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Preparation Example Preparation Example 1 This preparation example provides a modified montmorillonite, and the preparation steps are as follows: S1. Add 5g of montmorillonite to 100mL of deionized water and sonicate for 1h. Add 3.4g of FeCl3·6H2O and 1.7g of FeSO4·7H2O and stir for 6h. Adjust the pH to 12 with NaOH solution (1mol / L) to obtain magnetic montmorillonite solution. S2. Add 8g of tetrabutyl titanate to 10mL of anhydrous ethanol and stir until homogeneous. Add 1mL of concentrated nitric acid for hydrolysis to obtain TiO2 precursor sol. Then add it dropwise to 100mL of montmorillonite solution, heat to 75℃ and stir for 5h. Filter, wash with deionized water until neutral, and finally dry in an 80℃ oven to constant weight to obtain modified montmorillonite.

[0022] Preparation Example 2 This preparation example provides a modified montmorillonite, and the preparation steps are as follows: S1. Add 5.4g of montmorillonite to 100mL of deionized water and sonicate for 1h. Add 3.45g of FeCl3·6H2O and 1.75g ​​of FeSO4·7H2O and stir for 6h. Adjust the pH to 12 with NaOH solution (1mol / L) to obtain magnetic montmorillonite solution. S2. Add 9g of tetrabutyl titanate to 10mL of anhydrous ethanol and stir until homogeneous. Add 1mL of concentrated nitric acid for hydrolysis to obtain TiO2 precursor sol. Then add it dropwise to 100mL of montmorillonite solution, heat to 75℃ and stir for 5h. Filter, wash with deionized water until neutral, and finally dry in an 80℃ oven to constant weight to obtain modified montmorillonite.

[0023] Preparation Example 3 This preparation example provides a modified montmorillonite, and the preparation steps are as follows: S1. Add 5.8g of montmorillonite to 100mL of deionized water and sonicate for 1h. Add 3.5g of FeCl3·6H2O and 1.8g of FeSO4·7H2O and stir for 6h. Adjust the pH to 12 with NaOH solution (1mol / L) to obtain magnetic montmorillonite solution. S2. Add 8-10g of tetrabutyl titanate to 10mL of anhydrous ethanol and stir until homogeneous. Add 1mL of concentrated nitric acid for hydrolysis to obtain TiO2 precursor sol. Then add it dropwise to 100mL of montmorillonite solution, heat to 75℃ and stir for 5h. Filter, wash with deionized water until neutral, and finally dry in an 80℃ oven to constant weight to obtain modified montmorillonite.

[0024] Example Example 1 This embodiment provides a microwave-enhanced ethyl acetate esterification synthesis method, including the following steps: Step 1: The modified montmorillonite in Preparation Example 1 was acidified with sulfuric acid (concentration of 1 mol / L), then filtered, dried, and calcined in a closed muffle furnace at 300°C for 16 h. After cooling, the catalyst was obtained. Step 2: Mix ethanol and glacial acetic acid in a molar ratio of 1:1.2, add the catalyst prepared in step 1, the amount of catalyst is 5% of the total weight of raw materials, place in a microwave reactor for reaction, the radiation power in the microwave reactor is 350W, the radiation time is 8min, the radiation temperature is 110℃, and a reaction solution is obtained. Step 3: After the reaction is complete, cool to room temperature, add the reaction solution to a saturated sodium carbonate solution, adjust the pH to 7, shake the solution thoroughly and let it stand to separate into layers, remove and discard the lower water layer. Step 4: The upper ester layer is washed with saturated brine and saturated calcium chloride solution, and then dried with anhydrous magnesium sulfate to remove water from the ethyl acetate. Step 5: Distill the ethyl acetate solution and collect the fraction at 73-78℃ to obtain ethyl acetate.

[0025] Example 2 The only difference from Example 1 is the concentration of sulfuric acid in step 1: Step 1: The modified montmorillonite in Preparation Example 1 was acidified with sulfuric acid (concentration 1.25 mol / L), then filtered, dried, and calcined in a closed muffle furnace at 300°C for 16 h. After cooling, the catalyst was obtained.

[0026] Example 3 The only difference from Example 1 is that: The modified montmorillonite in Preparation Example 1 was replaced with the modified montmorillonite in Preparation Example 2.

[0027] Example 4 The only difference from Example 1 is that: The modified montmorillonite in Preparation Example 1 was replaced with the modified montmorillonite in Preparation Example 3.

[0028] Example 5 The only difference from Example 1 is that the calcination temperature and time are different in step 1: Step 1: The modified montmorillonite in Preparation Example 1 was acidified with sulfuric acid (concentration of 1 mol / L), then filtered, dried, and calcined in a closed muffle furnace at 600°C for 11 h. After cooling, the catalyst was obtained.

[0029] Example 6 The only difference from Example 1 is the molar ratio of ethanol and glacial acetic acid used in step 2: Step 2: Mix ethanol and glacial acetic acid in a molar ratio of 1:1.5, add the catalyst prepared in step 1, the amount of catalyst is 5% of the total weight of raw materials, place in a microwave reactor for reaction, the radiation power in the microwave reactor is 350W, the radiation time is 8min, the radiation temperature is 110℃, and a reaction solution is obtained.

[0030] Example 7 The only difference from Example 1 is the amount of catalyst used in step 2: Step 2: Mix ethanol and glacial acetic acid in a molar ratio of 1:1.2, add the catalyst prepared in Step 1, the amount of catalyst is 8% of the total weight of raw materials, place in a microwave reactor for reaction, the radiation power in the microwave reactor is 350W, the radiation time is 8min, the radiation temperature is 110℃, and the reaction solution is obtained.

[0031] Example 8 The only difference from Example 1 is that the process parameters in the microwave reactor in step 2 are different: Step 2: Mix ethanol and glacial acetic acid in a molar ratio of 1:1.2, add the catalyst prepared in Step 1, the amount of catalyst is 5% of the total weight of raw materials, place in a microwave reactor for reaction, the radiation power in the microwave reactor is 400W, the radiation time is 6min, the radiation temperature is 115℃, and a reaction solution is obtained.

[0032] Example 9 The only difference from Example 1 is that the process parameters in the microwave reactor in step 2 are different: Step 2: Mix ethanol and glacial acetic acid in a molar ratio of 1:1.2, add the catalyst prepared in step 1, the amount of catalyst is 5% of the total weight of raw materials, place in a microwave reactor for reaction, the radiation power in the microwave reactor is 500W, the radiation time is 5min, the radiation temperature is 120℃, and a reaction solution is obtained.

[0033] Example 10 The only difference from Example 1 is the pH value in step 3: Step 3: After the reaction is complete, cool to room temperature, add the reaction solution to a saturated sodium carbonate solution, adjust the pH to 8, shake the solution thoroughly and let it stand to separate into layers, remove and discard the lower water layer.

[0034] Comparative Example Comparative Example 1 This comparative example provides a method for synthesizing ethyl acetate, including the following steps: Step 1: The modified montmorillonite in Preparation Example 1 was acidified with sulfuric acid (concentration of 1 mol / L), then filtered, dried, and calcined in a closed muffle furnace at 300°C for 16 h. After cooling, the catalyst was obtained. Step 2: Mix ethanol and glacial acetic acid in a molar ratio of 1:1.2, add the catalyst prepared in step 1, the amount of catalyst is 5% of the total weight of raw materials, and heat to 50℃ and react for 3 hours. Step 3: After the reaction is complete, cool to room temperature, add the reaction solution to a saturated sodium carbonate solution, adjust the pH to 7, shake the solution thoroughly and let it stand to separate into layers, remove and discard the lower water layer. Step 4: The upper ester layer is washed with saturated brine and saturated calcium chloride solution, and then dried with anhydrous magnesium sulfate to remove water from the ethyl acetate. Step 5: Distill the ethyl acetate solution and collect the fraction at 73-78℃ to obtain ethyl acetate.

[0035] Comparative Example 2 This comparative example provides a microwave-enhanced ethyl acetate esterification synthesis method, including the following steps: Step 1: Acidify montmorillonite with sulfuric acid (concentration of 1 mol / L), then filter, dry, and calcine in a closed muffle furnace at 300°C for 16 hours. After cooling, the catalyst is obtained. Step 2: Mix ethanol and glacial acetic acid in a molar ratio of 1:1.2, add the catalyst prepared in step 1, the amount of catalyst is 5% of the total weight of raw materials, place in a microwave reactor for reaction, the radiation power in the microwave reactor is 350W, the radiation time is 8min, the radiation temperature is 110℃, and a reaction solution is obtained. Step 3: After the reaction is complete, cool to room temperature, add the reaction solution to a saturated sodium carbonate solution, adjust the pH to 7, shake the solution thoroughly and let it stand to separate into layers, remove and discard the lower water layer. Step 4: The upper ester layer is washed with saturated brine and saturated calcium chloride solution, and then dried with anhydrous magnesium sulfate to remove water from the ethyl acetate. Step 5: Distill the ethyl acetate solution and collect the fraction at 73-78℃ to obtain ethyl acetate.

[0036] Comparative Example 3 The only difference from Example 1 is the concentration of sulfuric acid in step 1: Step 1: The modified montmorillonite in Preparation Example 1 was acidified with sulfuric acid (concentration of 0.8 mol / L), then filtered, dried, and calcined in a closed muffle furnace at 300°C for 16 h. After cooling, the catalyst was obtained.

[0037] Comparative Example 4 The only difference from Example 1 is that: Step 1: The modified montmorillonite in Preparation Example 1 was acidified with sulfuric acid (concentration of 1.5 mol / L), then filtered, dried, and calcined in a closed muffle furnace at 300°C for 16 h. After cooling, the catalyst was obtained.

[0038] Comparative Example 5 The only difference from Example 1 is the calcination temperature in step 1: Step 1: The modified montmorillonite in Preparation Example 1 was acidified with sulfuric acid (concentration of 1 mol / L), then filtered, dried, and calcined in a closed muffle furnace at 250°C for 16 h. After cooling, the catalyst was obtained.

[0039] Comparative Example 6 The only difference from Example 1 is that the calcination temperature in step 1 is different. Step 1: The modified montmorillonite in Preparation Example 1 was acidified with sulfuric acid (concentration of 1 mol / L), then filtered, dried, and calcined in a closed muffle furnace at 650°C for 16 h. After cooling, the catalyst was obtained.

[0040] Comparative Example 7 The only difference from Example 1 is the molar ratio of ethanol and glacial acetic acid used in step 2: Step 2: Mix ethanol and glacial acetic acid in a molar ratio of 1:1, add the catalyst prepared in step 1, the amount of catalyst is 5% of the total weight of raw materials, place in a microwave reactor for reaction, the radiation power in the microwave reactor is 350W, the radiation time is 8min, the radiation temperature is 110℃, and a reaction solution is obtained.

[0041] Comparative Example 8 The only difference from Example 1 is the amount of catalyst used in step 2: Step 2: Mix ethanol and glacial acetic acid in a molar ratio of 1:1.2, add the catalyst prepared in Step 1, the amount of catalyst is 3% of the total weight of raw materials, place in a microwave reactor for reaction, the radiation power in the microwave reactor is 350W, the radiation time is 8min, the radiation temperature is 110℃, and a reaction solution is obtained.

[0042] Comparative Example 9 The only difference from Example 1 is the amount of catalyst used in step 2: Step 2: Mix ethanol and glacial acetic acid in a molar ratio of 1:1.2, add the catalyst prepared in Step 1, the amount of catalyst is 13% of the total weight of raw materials, place in a microwave reactor for reaction, the radiation power in the microwave reactor is 350W, the radiation time is 8min, the radiation temperature is 110℃, and a reaction solution is obtained.

[0043] Comparative Example 10 The only difference from Example 1 is that the process parameters in the microwave reactor in step 2 are different: Step 2: Mix ethanol and glacial acetic acid in a molar ratio of 1:1.2, add the catalyst prepared in step 1, the amount of catalyst is 5% of the total weight of raw materials, place in a microwave reactor for reaction, the radiation power in the microwave reactor is 300W, the radiation time is 8min, the radiation temperature is 110℃, and a reaction solution is obtained.

[0044] Comparative Example 11 The only difference from Example 1 is that the process parameters in the microwave reactor in step 2 are different: Step 2: Mix ethanol and glacial acetic acid in a molar ratio of 1:1.2, add the catalyst prepared in step 1, the amount of catalyst is 5% of the total weight of raw materials, place in a microwave reactor for reaction, the radiation power in the microwave reactor is 300W, the radiation time is 3min, the radiation temperature is 110℃, and a reaction solution is obtained.

[0045] Comparative Example 12 The only difference from Example 1 is that the process parameters in the microwave reactor in step 2 are different: Step 2: Mix ethanol and glacial acetic acid in a molar ratio of 1:1.2, add the catalyst prepared in step 1, the amount of catalyst is 5% of the total weight of raw materials, place in a microwave reactor for reaction, the radiation power in the microwave reactor is 550W, the radiation time is 8min, the radiation temperature is 130℃, and a reaction solution is obtained.

[0046] Performance testing The yields and purity of ethyl acetate obtained in Examples 1-10 and Comparative Examples 1-12 were tested, and the results are shown in Table 1. Table 1 As shown in Table 1, the yield and purity of ethyl acetate obtained in Examples 1-10 are higher than those in Examples 1-12. Furthermore, considering Comparative Example 1 and Examples 1-10, it is evident that this invention significantly shortens the reaction time for preparing ethyl acetate. Therefore, the microwave-enhanced ethyl acetate esterification synthesis method provided in this invention achieves high yields, is simple to operate, and has a fast reaction rate, demonstrating advantages such as time and energy saving, and possessing certain social and economic benefits.

[0047] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0048] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A microwave-enhanced ethyl acetate esterification synthesis method, characterized in that, Includes the following steps: Step 1: Acidify the modified montmorillonite, then filter it, dry it, and calcine it in a closed muffle furnace. After cooling, the catalyst is obtained. Step 2: Mix ethanol and glacial acetic acid, add the catalyst prepared in step 1, and place the mixture in a microwave reactor to react and obtain a reaction solution. Step 3: After the reaction is complete, cool to room temperature, add the reaction solution to a saturated sodium carbonate solution, adjust the pH value, shake the solution thoroughly and let it stand to separate into layers, remove and discard the lower water layer; Step 4: The upper ester layer is washed with saturated brine and saturated calcium chloride solution, and then dried with anhydrous magnesium sulfate to remove water from the ethyl acetate. Step 5: Distill the ethyl acetate solution and collect the fraction at 73-78℃ to obtain ethyl acetate.

2. The microwave-enhanced ethyl acetate esterification synthesis method according to claim 1, characterized in that, The acidification solvent used in step 1 is sulfuric acid with a concentration of 1–1.25 mol / L.

3. The microwave-enhanced ethyl acetate esterification synthesis method according to claim 1, characterized in that, In step 1, the calcination temperature is 300–600℃ and the calcination time is 10–16 h.

4. The microwave-enhanced ethyl acetate esterification synthesis method according to claim 1, characterized in that, The preparation steps of modified montmorillonite in step 1 are as follows: S1. Add montmorillonite to deionized water and ultrasonically disperse for 0.5-1 h. Add FeCl3·6H2O and FeSO4·7H2O and stir for 5-6 h. Adjust the pH value to 11.5-12 with NaOH solution to obtain magnetic montmorillonite solution. S2. Add tetrabutyl titanate to anhydrous ethanol and stir until homogeneous. Add concentrated nitric acid for hydrolysis to obtain TiO2 precursor sol. Then add it dropwise to montmorillonite solution, heat to 70-75℃ and stir for 3-5 hours. Filter, wash until neutral, and dry to constant weight to obtain modified montmorillonite.

5. The microwave-enhanced ethyl acetate esterification synthesis method according to claim 4, characterized in that, The ratio of montmorillonite, deionized water, FeCl3·6H2O and FeSO4·7H2O used in S1 is 5-5.2g:100mL:3.30-3.35g:1.65-1.68g.

6. The microwave-enhanced ethyl acetate esterification synthesis method according to claim 4, characterized in that, The ratio of tetrabutyl titanate, anhydrous ethanol, concentrated nitric acid, and montmorillonite solution in S2 is 8-10g:10mL:1mL:100mL.

7. The microwave-enhanced ethyl acetate esterification synthesis method according to claim 1, characterized in that, In step 2, the molar ratio of ethanol to glacial acetic acid is 1:1.2 to 1.

5.

8. The microwave-enhanced ethyl acetate esterification synthesis method according to claim 1, characterized in that, In step 2, the amount of catalyst used is 5% to 10% of the total weight of the raw materials.

9. The microwave-enhanced ethyl acetate esterification synthesis method according to claim 1, characterized in that, Step 2: The radiation power in the microwave reactor is 350–500W, the radiation time is 5–8 minutes, and the radiation temperature is 110–120℃.

10. The microwave-enhanced ethyl acetate esterification synthesis method according to claim 1, characterized in that, In step 3, adjust the pH value to 7-8.

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