Production process method of electronic grade diethyl carbonate

Abstract

The invention relates to the technical field of fine chemical engineering, and particularly discloses a production process method of electronic-grade diethyl carbonate. The method comprises the following steps: carrying out ester exchange reaction on ethylene carbonate and absolute ethyl alcohol in a microwave reaction kettle under the catalysis of a composite catalyst; after the reaction liquid is subjected to phase separation treatment, an intermediate is obtained by adopting a normal-pressure and reduced-pressure rectification coupled continuous separation process; metal impurities and moisture are removed through molecular sieve adsorption, ultra-clean purification is achieved by combining precise filtration of a polytetrafluoroethylene membrane, and the composite catalyst can remarkably improve the transesterification reaction efficiency and product selectivity. According to the process, water, metal impurities and nanoscale particles in a reaction system are efficiently removed through the synergistic effect of reaction process strengthening and a multi-stage purification technology, and the purity of the prepared electronic-grade diethyl carbonate meets the strict requirements in the field of high-end electronic chemicals such as lithium battery electrolyte; the method has the technical advantages of short reaction period, thorough impurity removal, high product purity and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of fine chemicals, and more particularly to a production process for electronic-grade diethyl carbonate. Background Art

[0002] As an important lipid compound, diethyl carbonate, due to its excellent chemical stability and solubility, is a key component of high-end electronic chemicals such as lithium-ion battery electrolytes and semiconductor photoresists. Electronic-grade diethyl carbonate requires extremely high purity, with strict control of moisture, metal ions, and nanoparticle impurities. Its preparation technology relies on efficient transesterification reaction control and precision purification process design.

[0003] At present, the industrial preparation of diethyl carbonate mainly adopts the transesterification method, which uses ethylene carbonate or propylene carbonate and ethanol as raw materials and is generated by transesterification reaction under the action of a catalyst. However, these traditional processes have many shortcomings: on the one hand, the dimethyl carbonate generated by the reaction will form an azeotrope with methanol or ethanol, which makes it difficult to separate the product from the raw materials, affecting the yield and purity of diethyl carbonate. On the other hand, traditional catalysts usually use homogeneous or solid catalysts, which have problems such as difficulty in catalyst separation, low selectivity, and easy occurrence of side reactions, resulting in limited improvement in target product yield and purity, and the reaction conditions are relatively harsh, usually requiring high temperature and high pressure, high energy consumption, and low production efficiency. Therefore, the present invention provides a production process method for electronic-grade diethyl carbonate to solve the above-mentioned technical problems. Summary of the Invention

[0004] The present invention aims to provide a production process for electronic-grade diethyl carbonate. The process achieves efficient removal of water, metal impurities, and nanoparticles in the reaction system through the synergistic effect of reaction process intensification and multi-stage purification technology. The purity of the electronic-grade diethyl carbonate produced meets the stringent requirements of high-end electronic chemicals such as lithium battery electrolytes. The process has technical advantages such as a short reaction cycle, thorough impurity removal, and high product purity.

[0005] A production process for electronic-grade diethyl carbonate comprises the following steps:

[0006] S1. Add ethylene carbonate and anhydrous ethanol to a microwave reactor, add a composite catalyst, introduce an inert gas to replace the air, start microwave heating, control the microwave heating conditions, reaction temperature, and pressure, and stir the reaction to obtain a crude reaction solution containing diethyl carbonate, ethanol, and ethylene glycol;

[0007] S2. Cool the crude reaction solution to 20-30° C., add sodium carbonate for phase separation and separate the upper organic phase, and pump the organic phase into an atmospheric distillation tower and a vacuum distillation tower in sequence for continuous separation to obtain a diethyl carbonate intermediate;

[0008] S3. The diethyl carbonate intermediate is subjected to adsorption treatment by passing it through a fixed bed reactor filled with molecular sieves to remove moisture and metal impurities; and then filtered through a polytetrafluoroethylene membrane to retain particles with a particle size greater than 0.05-0.2 μm to obtain electronic grade diethyl carbonate.

[0009] Preferably, in step S1, the components include 10-15 parts by weight of ethylene carbonate, 8-12 parts by weight of anhydrous ethanol, and 0.4-0.8 parts by weight of the composite catalyst.

[0010] Preferably, in step S1, the microwave frequency is 2000-2500 MHz, the power is 200-400 W, the reaction temperature is 60-70° C., the pressure is 0.04-0.06 MPa, and the stirring reaction time is 25-35 min.

[0011] Preferably, the production process for electronic-grade diethyl carbonate according to claim 1 in step S2 is characterized in that the top temperature of the atmospheric distillation tower in step S2 is 75-80°C, the bottom temperature is 115-125°C, the vacuum degree of the vacuum distillation tower is -0.08 to -0.1 MPa, the top temperature is 80-90°C, and the bottom temperature is 105-115°C.

[0012] Preferably, in step S3, the adsorption temperature is 45-55°C, and the flow rate is 0.3-0.7 BV / h.

[0013] Preferably, in step S3, the molecular sieve is composed of 3A and 13X molecular sieves in a mass ratio of 1-3:1, and the filling height of the mixed molecular sieve is 4-6 times the bed diameter.

[0014] Preferably, the preparation steps of the composite catalyst in step S1 are:

[0015] A1. Dispersing hexagonal boron nitride in N-methylpyrrolidone, adding sodium dodecylbenzenesulfonate, ultrasonically exfoliating for 3-5 hours, and centrifuging to obtain boron nitride nanosheets; dispersing the boron nitride nanosheets and aluminum oxide nanoparticles in anhydrous ethanol, ultrasonically dispersing for 30-40 minutes, and then stirring and blending at 70-80°C for 2-4 hours, and centrifuging to obtain a composite carrier;

[0016] A2. Dispersing the composite support in toluene, adding 3-aminopropyltrimethoxysilane, reacting at 80-100° C. for 4-6 hours under nitrogen protection, washing, and drying to obtain an intermediate; dispersing the intermediate in toluene, adding 3-glycidoxypropyltrimethoxysilane, reacting at 90-110° C. for 5-7 hours under nitrogen protection, washing, and drying to obtain a modified composite support;

[0017] A3. Disperse the modified composite support and 1-butyl-3-methylimidazolium hydroxyacetate in deionized water, adjust the pH to 10-12, and react at 50-70° C. for 6-8 hours; then add 1-propylsulfonic acid-3-methylimidazolium hydrogen sulfate, continue to react at 60-80° C. for 7-9 hours, and wash and dry to obtain a composite catalyst.

[0018] Preferably, in step A1, the ingredients are, by weight, 10-15 parts of hexagonal boron nitride, 80-90 parts of N-methylpyrrolidone, 1-3 parts of sodium dodecylbenzenesulfonate; and 10-15 parts of boron nitride nanosheets, 5-8 parts of aluminum oxide nanoparticles, and 70-80 parts of anhydrous ethanol.

[0019] Preferably, in step A2, the components by weight include 10-15 parts of the composite carrier, 60-70 parts of toluene and 2-5 parts of 3-aminopropyltrimethoxysilane; and 10-15 parts of the intermediate, 60-70 parts of toluene and 3-6 parts of 3-glycidoxypropyltrimethoxysilane.

[0020] Preferably, in step A3, the modified composite carrier, 3-6 parts by weight, 0.3-0.8 parts by weight of 1-butyl-3-methylimidazolium hydroxyacetate, 30-40 parts by weight of deionized water, and 0.5-1 parts by weight of 1-propylsulfonic acid-3-methylimidazolium hydrogen sulfate are included.

[0021] In summary, the present invention has the following beneficial effects:

[0022] 1. The present invention constructs a composite catalyst system with high activity and selectivity by performing dual-functional modification on a boron nitride and aluminum oxide composite carrier. Based on the layered structure of boron nitride nanosheets and the mesoporous properties of aluminum oxide nanoparticles, the composite carrier can provide abundant loading sites and mass transfer channels, significantly enhancing the dispersibility of the active components. Furthermore, through the step-by-step grafting modification of amino groups and epoxysilanes, a gradient functionalized surface is formed, enabling hydroxyacetic acid esters and sulfonic acid imidazole salts to be directionally anchored and form acid-base synergistic active centers, thereby precisely regulating the proton transfer path of the transesterification reaction and inhibiting the formation of by-products. The non-thermal effect of the microwave field further enhances the adsorption-dissociation behavior of the reactant molecules on the catalyst surface, breaking through the kinetic limitations of traditional heat conduction and achieving efficient conversion under mild conditions.

[0023] 2. The present invention adopts a multi-stage purification strategy combining molecular sieve composite adsorption with polytetrafluoroethylene membrane filtration to achieve deep impurity removal through structural complementarity. The microporous characteristics of the 3A molecular sieve preferentially adsorb water and small molecular polar impurities, while the 13X molecular sieve selectively captures metal ions through ion exchange; the surface hydrophobicity and pore size distribution design of the polytetrafluoroethylene membrane can effectively intercept nano-scale particles and reduce the risk of membrane contamination. This purification system breaks through the limitations of single purification technology for trace impurity removal through the synergistic effect of the chemical adsorption of molecular sieves and the physical interception of membranes, ensuring that the product purity meets electronic grade standards. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0025] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used are purchased from conventional biochemical reagent stores unless otherwise specified. The quantitative experiments in the following examples were all repeated three times, and the data are the average or mean ± standard deviation of the three repeated experiments.

[0026] Hexagonal boron nitride was purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number S40088;

[0027] Type 3A molecular sieve, purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number S14149;

[0028] 13X molecular sieve was purchased from Xi'an Qiyue Biotechnology Co., Ltd., brand Qiyue Bio.

[0029] Example 1

[0030] A production process for electronic-grade diethyl carbonate comprises the following steps:

[0031] S1. Add 10 parts of ethylene carbonate and 8 parts of anhydrous ethanol to a microwave reactor, add 0.4 parts of a composite catalyst, introduce nitrogen to replace the air, turn on microwave heating, control the microwave frequency to 2000 MHz, the power to 200 W, the reaction temperature to 60°C, the pressure to 0.04 MPa, and react at a stirring speed of 200 r / min for 35 min to obtain a crude reaction solution containing diethyl carbonate, ethanol and ethylene glycol;

[0032] S2. Cool the crude reaction solution to 20°C, add sodium carbonate for phase separation, let it stand for 30 minutes, separate the upper organic phase, and pump the organic phase into the atmospheric distillation tower and the vacuum distillation tower for continuous separation. The top temperature of the atmospheric distillation tower is 75°C and the bottom temperature is 115°C; the vacuum degree of the vacuum distillation tower is -0.08MPa, the top temperature is 80°C, and the bottom temperature is 105°C, and finally obtain the diethyl carbonate intermediate;

[0033] S3. The diethyl carbonate intermediate is passed through a fixed-bed reactor packed with molecular sieves. The molecular sieves are composed of 3A and 13X molecular sieves in a 1:1 mass ratio, and the mixed molecular sieves are packed to a height of four times the bed diameter. The adsorption temperature is 45°C, the flow rate is 0.3 BV / h, and the treatment is carried out for 2 hours to remove moisture and metal impurities. The intermediate is then filtered through a polytetrafluoroethylene membrane to retain particles with a particle size greater than 0.05 μm, thereby obtaining electronic-grade diethyl carbonate.

[0034] The preparation steps of the composite catalyst are as follows:

[0035] A1. Dispersing 10 parts of hexagonal boron nitride in 80 parts of N-methylpyrrolidone, adding 1 part of sodium dodecylbenzenesulfonate, and ultrasonically exfoliating for 5 hours at an ultrasonic power of 200 W and an ultrasonic temperature of 25° C., and centrifuging to obtain boron nitride nanosheets; dispersing 10 parts of boron nitride nanosheets and 5 parts of aluminum oxide nanoparticles in 70 parts of anhydrous ethanol, and ultrasonically dispersing for 40 minutes at an ultrasonic power of 150 W and a temperature of 30° C., and then stirring and blending at 70° C. for 4 hours at a stirring speed of 300 r / min, and centrifuging to obtain a composite carrier;

[0036] A2. Dispersing 10 parts of the composite support in 60 parts of toluene, adding 2 parts of 3-aminopropyltrimethoxysilane, reacting at 80° C. for 6 hours under nitrogen protection, stirring at 200 r / min, washing and drying to obtain an intermediate; dispersing 10 parts of the intermediate in 60 parts of toluene, adding 3 parts of 3-glycidoxypropyltrimethoxysilane, reacting at 90° C. for 7 hours under nitrogen protection, stirring at 200 r / min, washing and drying to obtain a modified composite support;

[0037] A3. Disperse 3 parts of the modified composite support and 0.3 parts of 1-butyl-3-methylimidazolium hydroxyacetate in 30 parts of deionized water, adjust the pH to 10, and react at 50°C for 8 hours with a stirring speed of 150 r / min; then add 0.5 parts of 1-propylsulfonic acid-3-methylimidazolium hydrogen sulfate, continue to react at 60°C for 9 hours with a stirring speed of 150 r / min, and wash and dry to obtain a composite catalyst.

[0038] Example 2

[0039] A production process for electronic-grade diethyl carbonate comprises the following steps:

[0040] S1. Add 12 parts of ethylene carbonate and 10 parts of anhydrous ethanol to a microwave reactor, add 0.5 parts of a composite catalyst, introduce nitrogen to replace the air, turn on microwave heating, control the microwave frequency to 2250 MHz, the power to 300 W, the reaction temperature to 65 ° C, the pressure to 0.05 MPa, and stir the reaction at a speed of 250 r / min for 30 min to obtain a crude reaction solution containing diethyl carbonate, ethanol and ethylene glycol;

[0041] S2. Cool the crude reaction solution to 25°C, add sodium carbonate for phase separation, let it stand for 25 minutes, separate the upper organic phase, and pump the organic phase into the atmospheric distillation tower and the vacuum distillation tower in sequence for continuous separation. The top temperature of the atmospheric distillation tower is 78°C and the bottom temperature is 120°C; the vacuum degree of the vacuum distillation tower is -0.09MPa, the top temperature is 85°C, and the bottom temperature is 110°C, and finally obtain the diethyl carbonate intermediate;

[0042] S3. The diethyl carbonate intermediate is passed through a fixed-bed reactor packed with molecular sieves. The molecular sieves are composed of 3A and 13X molecular sieves in a mass ratio of 2:1, and the mixed molecular sieves are packed to a height of 5 times the bed diameter. The adsorption temperature is 50°C, the flow rate is 0.5 BV / h, and the treatment time is 1.5 hours to remove moisture and metal impurities. The intermediate is then filtered through a polytetrafluoroethylene membrane to retain particles with a size greater than 0.1 μm to obtain electronic-grade diethyl carbonate.

[0043] The preparation steps of the composite catalyst are as follows:

[0044] A1. Dispersing 12 parts of hexagonal boron nitride in 85 parts of N-methylpyrrolidone, adding 2 parts of sodium dodecylbenzenesulfonate, and ultrasonically exfoliating for 4 hours at an ultrasonic power of 250 W and an ultrasonic temperature of 30° C., and centrifuging to obtain boron nitride nanosheets; dispersing 12 parts of boron nitride nanosheets and 6 parts of aluminum oxide nanoparticles in 75 parts of anhydrous ethanol, and ultrasonically dispersing for 35 minutes at an ultrasonic power of 200 W and a temperature of 35° C., and then stirring and blending at 75° C. for 3 hours at a stirring speed of 350 r / min, and centrifuging to obtain a composite carrier;

[0045] A2. Dispersing 12 parts of the composite support in 65 parts of toluene, adding 3 parts of 3-aminopropyltrimethoxysilane, reacting at 90° C. for 5 hours under nitrogen protection, stirring at 220 r / min, washing and drying to obtain an intermediate; dispersing 12 parts of the intermediate in 65 parts of toluene, adding 4 parts of 3-glycidoxypropyltrimethoxysilane, reacting at 100° C. for 6 hours under nitrogen protection, stirring at 220 r / min, washing and drying to obtain a modified composite support;

[0046] A3. Disperse 4 parts of the modified composite support and 0.5 parts of 1-butyl-3-methylimidazolium hydroxyacetate in 35 parts of deionized water, adjust the pH to 11, react at 60°C for 7 hours, and stir at 160 r / min; then add 0.7 parts of 1-propylsulfonic acid-3-methylimidazolium hydrogen sulfate, continue to react at 70°C for 8 hours, stir at 160 r / min, and wash and dry to obtain a composite catalyst.

[0047] Example 3

[0048] A production process for electronic-grade diethyl carbonate comprises the following steps:

[0049] S1. Add 15 parts of ethylene carbonate and 12 parts of anhydrous ethanol to a microwave reactor, add 0.8 parts of a composite catalyst, introduce nitrogen to replace the air, turn on microwave heating, control the microwave frequency to 2500 MHz, the power to 400 W, the reaction temperature to 70°C, and the pressure to 0.06 MPa, and stir the reaction at a speed of 300 r / min for 25 min to obtain a crude reaction solution containing diethyl carbonate, ethanol, and ethylene glycol;

[0050] S2. Cool the crude reaction solution to 30°C, add sodium carbonate for phase separation, let it stand for 20 minutes, separate the upper organic phase, and pump the organic phase into the atmospheric distillation tower and the vacuum distillation tower in sequence for continuous separation. The top temperature of the atmospheric distillation tower is 80°C and the bottom temperature is 125°C; the vacuum degree of the vacuum distillation tower is -0.1MPa, the top temperature is 90°C, and the bottom temperature is 115°C, and finally obtain the diethyl carbonate intermediate;

[0051] S3. The diethyl carbonate intermediate is passed through a fixed-bed reactor packed with molecular sieves. The molecular sieves are composed of 3A and 13X molecular sieves in a mass ratio of 3:1, and the mixed molecular sieves are packed to a height of 6 times the bed diameter. The adsorption temperature is 55°C, the flow rate is 0.7 BV / h, and after 1 hour of treatment, moisture and metal impurities are removed. The intermediate is then filtered through a polytetrafluoroethylene membrane to retain particles with a particle size greater than 0.2 μm, thereby obtaining electronic-grade diethyl carbonate.

[0052] The preparation steps of the composite catalyst are as follows:

[0053] A1. Dispersing 15 parts of hexagonal boron nitride in 90 parts of N-methylpyrrolidone, adding 3 parts of sodium dodecylbenzenesulfonate, and ultrasonically exfoliating for 3 hours at an ultrasonic power of 300 W and an ultrasonic temperature of 35° C., and centrifuging to obtain boron nitride nanosheets; dispersing 15 parts of boron nitride nanosheets and 8 parts of aluminum oxide nanoparticles in 80 parts of anhydrous ethanol, and ultrasonically dispersing for 30 minutes at an ultrasonic power of 250 W and a temperature of 40° C., and then stirring and blending at 80° C. for 2 hours at a stirring speed of 400 r / min, and centrifuging to obtain a composite carrier;

[0054] A2. Disperse 15 parts of the composite support in 70 parts of toluene, add 5 parts of 3-aminopropyltrimethoxysilane, react at 100° C. for 4 hours under nitrogen protection, stir at 250 r / min, wash and dry to obtain an intermediate; disperse 15 parts of the intermediate in 70 parts of toluene, add 6 parts of 3-glycidoxypropyltrimethoxysilane, react at 110° C. for 5 hours under nitrogen protection, stir at 250 r / min, wash and dry to obtain a modified composite support;

[0055] A3. Disperse 6 parts of the modified composite support and 0.8 parts of 1-butyl-3-methylimidazolium hydroxyacetate in 40 parts of deionized water, adjust the pH to 12, and react at 70°C for 6 hours with a stirring speed of 180 r / min; then add 1 part of 1-propylsulfonic acid-3-methylimidazolium hydrogen sulfate, continue to react at 80°C for 7 hours with a stirring speed of 180 r / min, and wash and dry to obtain a composite catalyst.

[0056] Example 4

[0057] A production process for electronic-grade diethyl carbonate comprises the following steps:

[0058] S1. Add 13 parts of ethylene carbonate and 11 parts of anhydrous ethanol to a microwave reactor, add 0.6 parts of a composite catalyst, introduce nitrogen to replace the air, turn on microwave heating, control the microwave frequency to 2350 MHz, the power to 350 W, the reaction temperature to 68 ° C, the pressure to 0.055 MPa, and stir the reaction at a speed of 280 r / min for 28 min to obtain a crude reaction solution containing diethyl carbonate, ethanol and ethylene glycol;

[0059] S2. Cool the crude reaction solution to 23°C, add sodium carbonate for phase separation, let it stand for 22 minutes, separate the upper organic phase, and pump the organic phase into the atmospheric distillation tower and the vacuum distillation tower for continuous separation. The top temperature of the atmospheric distillation tower is 77°C and the bottom temperature is 122°C; the vacuum degree of the vacuum distillation tower is -0.085MPa, the top temperature is 85°C, and the bottom temperature is 110°C, to finally obtain diethyl carbonate intermediate;

[0060] S3. The diethyl carbonate intermediate is passed through a fixed-bed reactor packed with molecular sieves. The molecular sieves are composed of 3A and 13X molecular sieves in a mass ratio of 2.5:1, and the mixed molecular sieves are packed to a height of 5.5 times the bed diameter. The adsorption temperature is 52°C, the flow rate is 0.6 BV / h, and the treatment time is 1.2 hours to remove moisture and metallic impurities. The intermediate is then filtered through a polytetrafluoroethylene membrane to retain particles with a size greater than 0.15 μm to obtain electronic-grade diethyl carbonate.

[0061] The preparation steps of the composite catalyst are as follows:

[0062] A1. Disperse 13 parts of hexagonal boron nitride in 88 parts of N-methylpyrrolidone, add 2.5 parts of sodium dodecylbenzenesulfonate, and ultrasonically exfoliate for 4.5 hours at an ultrasonic power of 280 W and a temperature of 32° C., and centrifuge to obtain boron nitride nanosheets. Disperse 13 parts of boron nitride nanosheets and 7 parts of aluminum oxide nanoparticles in 78 parts of anhydrous ethanol, ultrasonically disperse for 38 minutes at an ultrasonic power of 230 W and a temperature of 38° C., then stir and blend at 78° C. for 3.5 hours at a stirring speed of 380 r / min, and centrifuge to obtain a composite carrier.

[0063] A2. Dispersing 13 parts of the composite support in 68 parts of toluene, adding 4 parts of 3-aminopropyltrimethoxysilane, reacting at 95° C. for 5.5 hours under nitrogen protection, stirring at 230 r / min, washing and drying to obtain an intermediate; dispersing 13 parts of the intermediate in 68 parts of toluene, adding 5 parts of 3-glycidoxypropyltrimethoxysilane, reacting at 105° C. for 6.5 hours under nitrogen protection, stirring at 230 r / min, washing and drying to obtain a modified composite support;

[0064] A3. Disperse 5 parts of the modified composite support and 0.6 parts of 1-butyl-3-methylimidazole hydroxyacetate in 38 parts of deionized water, adjust the pH to 11.5, react at 65°C for 7.5 hours, and stir at 170 r / min; then add 0.8 parts of 1-propylsulfonic acid-3-methylimidazole hydrogen sulfate, continue to react at 75°C for 8.5 hours, stir at 170 r / min, and wash and dry to obtain a composite catalyst.

[0065] Comparative Example 1

[0066] A process for producing electronic-grade diethyl carbonate is disclosed. The process differs from Example 4 in that, in step S1, the composite catalyst of the present invention is not used but the conventional homogeneous catalyst triethylamine is used. The remaining reaction conditions, namely, microwave frequency, power, temperature, pressure, etc., are the same as those in Example 4.

[0067] Comparative Example 2

[0068] A process for producing electronic-grade diethyl carbonate is disclosed. The process differs from Example 4 in that the aminosilane grafting modification in step A2 of the composite catalyst preparation process is omitted. That is, the composite support prepared in step A1 is directly used for loading the ionic liquid in step A3. Surface functionalization treatment with 3-aminopropyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane is not performed. The remaining catalyst preparation and reaction conditions, namely, microwave frequency, power, temperature, and pressure, are the same as those in Example 4.

[0069] Comparative Example 3

[0070] A process for producing electronic-grade diethyl carbonate is disclosed. The process differs from Example 4 in that the surface modification of steps A2 and A3 is omitted in the composite catalyst preparation step. That is, the boron nitride and aluminum oxide composite support prepared in step A1 is directly used as the catalyst. The remaining catalyst preparation and reaction conditions, namely, microwave frequency, power, temperature, pressure, etc., are the same as those in Example 4.

[0071] Comparative Example 4

[0072] A process for producing electronic-grade diethyl carbonate is disclosed. The process differs from Example 4 in that, in the composite catalyst preparation step, 1-propylsulfonyl-3-methylimidazole hydrogen sulfate is not introduced in step A3, and only 1-butyl-3-methylimidazole hydroxyacetate is retained. The remaining catalyst preparation and reaction conditions, namely, microwave frequency, power, temperature, and pressure, are the same as those in Example 4.

[0073] Comparative Example 5

[0074] A process for producing electronic-grade diethyl carbonate is disclosed, which differs from Example 4 in that a composite system of 3A and 13X molecular sieves is not used in step S3. Instead, 3A molecular sieve is used alone, and the filling height is 5 times the bed diameter. The remaining purification conditions, namely, adsorption temperature, flow rate, membrane filtration parameters, etc., are the same as those in Example 4.

[0075] Comparative Example 6

[0076] A process for producing electronic-grade diethyl carbonate is disclosed, which differs from Example 4 in that step S1 does not use microwave heating but instead uses conventional oil bath heating. Meanwhile, the heating power is equivalently matched, the reaction temperature is maintained at 68° C., the stirring speed and reaction time are the same as those in Example 4, and the other reaction conditions remain unchanged.

[0077] Performance Testing

[0078] The production process of electronic-grade diethyl carbonate of Examples 1-4 and Comparative Examples 1-6 was subjected to performance tests. The test results are shown in Table 1 below.

[0079] Table 1

[0080] Test items Yield / % Selectivity / % Moisture / ppm Catalyst cycle times Example 1 92.3 98.3 4.2 8 Example 2 93.8 98.5 3.5 9 Example 3 92.0 98.4 4.0 8 Example 4 94.2 98.9 2.8 10 Comparative Example 1 78.6 92.0 18.5 / Comparative Example 2 85.1 92.5 10.2 5 Comparative Example 3 81.5 93.2 15.3 4 Comparative Example 4 88.2 96.0 8.7 6 Comparative Example 5 89.4 98.0 5.5 7 Comparative Example 6 87.1 97.2 4.8 6

[0081] 1. Examples 1-4 of the present invention achieved yields of ≥92.3% through microwave-enhanced transesterification and synergistic effects with a composite catalyst, significantly higher than those of Comparative Examples 1-6. Example 4, relying on a gradient functionalized modified support, namely, an acid-base synergistic active center constructed by step-by-step grafting of 3-aminopropyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane, achieved a high yield of 94.2% and a high selectivity of 98.9%, effectively suppressing the formation of byproducts such as ethylene glycol. The conventional homogeneous catalyst in Comparative Example 1 had a yield of only 78.6% due to poor dispersion of the active center, demonstrating the necessity of composite catalyst design.

[0082] 2. This example utilizes a composite adsorption system of 3A and 13X molecular sieves, combined with polytetrafluoroethylene membrane precision filtration, achieving a moisture content of ≤4.2 ppm, significantly lower than that of Comparative Examples 1-6. The 3A molecular sieve's microporous structure preferentially adsorbs small water molecules, while the 13X molecular sieve captures polar metal ions through ion exchange. These two synergistically achieve deep dehydration and removal of metal impurities, meeting the stringent trace moisture requirements of electronic-grade diethyl carbonate.

[0083] 3. The composite catalyst of Example 4 achieved 10 cycles, significantly exceeding those of Comparative Examples 1-6. This is attributed to the high mechanical strength of the boron nitride nanosheet and alumina nanoparticle composite support and the directional loading of 1-butyl-3-methylimidazolium glycolate and 1-propylsulfonate-3-methylimidazolium hydrogen sulfate, which reduced loss of active components. In Comparative Example 2, where support surface modification was omitted, the composite catalyst achieved only 5 cycles, demonstrating the critical role of gradient functionalization in the catalyst's structural stability.

[0084] In summary, the present invention, through microwave field coupling of composite catalysts and multi-stage purification technology, significantly outperforms single-variable control examples in four core indicators: yield, selectivity, moisture control, and catalyst cycle stability. Among them, Example 4 achieved the best overall performance, verifying the synergistic innovation advantages of dual-functional modification of composite supports, microwave non-thermal effect-enhanced mass transfer, and molecular sieve-membrane filtration gradient purification, providing an industrially feasible solution for the green and efficient production of electronic-grade diethyl carbonate.

[0085] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A production process for electronic grade diethyl carbonate, characterized in that, The following steps are involved: S1. Add ethylene carbonate and anhydrous ethanol to a microwave reactor, add a composite catalyst, introduce an inert gas to replace the air, start microwave heating, control the microwave heating conditions, reaction temperature, and pressure, and stir the reaction to obtain a crude reaction solution containing diethyl carbonate, ethanol, and ethylene glycol; S2, cooling the crude reaction solution, adding sodium carbonate to separate the phases and separating the upper organic phase, and pumping the organic phase into an atmospheric distillation tower and a vacuum distillation tower in sequence for continuous separation to obtain a diethyl carbonate intermediate; S3. The diethyl carbonate intermediate is subjected to adsorption treatment by passing it through a fixed bed reactor filled with molecular sieves to remove moisture and metal impurities; and then filtered through a polytetrafluoroethylene membrane to retain particles with a particle size greater than 0.05-0.2 μm to obtain electronic grade diethyl carbonate.

2. a production process for electronic-grade diethyl carbonate according to claim 1, characterized in that, In step S1, the components include 10-15 parts of ethylene carbonate, 8-12 parts of anhydrous ethanol and 0.4-0.8 parts of a composite catalyst in parts by weight.

3. A process for producing electronic-grade diethyl carbonate according to claim 1, characterized in that: In step S1, the microwave frequency is 2000-2500 MHz, the power is 200-400 W, the reaction temperature is 60-70° C., the pressure is 0.04-0.06 MPa, and the stirring reaction time is 25-35 min.

4. a production process for electronic-grade diethyl carbonate according to claim 1, characterized in that, In step S2, the top temperature of the atmospheric distillation tower is 75-80°C, the bottom temperature is 115-125°C, the vacuum degree of the vacuum distillation tower is -0.08 to -0.1 MPa, the top temperature is 80-90°C, and the bottom temperature is 105-115°C.

5. A process for producing electronic-grade diethyl carbonate according to claim 1, wherein In step S3, the adsorption temperature is 45-55°C, and the flow rate is 0.3-0.7 BV / h.

6. A process for producing electronic-grade diethyl carbonate according to claim 1, characterized in that: In step S3, the molecular sieve is composed of 3A and 13X molecular sieves in a mass ratio of 1-3:1, and the filling height of the mixed molecular sieve is 4-6 times the bed diameter.

7. A production process for electronic-grade diethyl carbonate according to claim 1, characterized in that, The preparation steps of the composite catalyst in step S1 are: A1. Dispersing hexagonal boron nitride in N-methylpyrrolidone, adding sodium dodecylbenzenesulfonate, ultrasonically exfoliating for 3-5 hours, and centrifuging to obtain boron nitride nanosheets; dispersing the boron nitride nanosheets and aluminum oxide nanoparticles in anhydrous ethanol, ultrasonically dispersing for 30-40 minutes, and then stirring and blending at 70-80°C for 2-4 hours, and centrifuging to obtain a composite carrier; A2. Dispersing the composite support in toluene, adding 3-aminopropyltrimethoxysilane, reacting at 80-100° C. for 4-6 hours under nitrogen protection, washing, and drying to obtain an intermediate; dispersing the intermediate in toluene, adding 3-glycidoxypropyltrimethoxysilane, reacting at 90-110° C. for 5-7 hours under nitrogen protection, washing, and drying to obtain a modified composite support; A3. Disperse the modified composite support and 1-butyl-3-methylimidazolium hydroxyacetate in deionized water, adjust the pH to 10-12, and react at 50-70° C. for 6-8 hours; then add 1-propylsulfonic acid-3-methylimidazolium hydrogen sulfate, continue to react at 60-80° C. for 7-9 hours, and wash and dry to obtain a composite catalyst.

8. A process for producing electronic-grade diethyl carbonate according to claim 7, characterized in that: In step A1, the components by weight include 10-15 parts of hexagonal boron nitride, 80-90 parts of N-methylpyrrolidone, 1-3 parts of sodium dodecylbenzenesulfonate; and 10-15 parts of boron nitride nanosheets, 5-8 parts of aluminum oxide nanoparticles, and 70-80 parts of anhydrous ethanol.

9. A process for producing electronic-grade diethyl carbonate according to claim 7, characterized in that: In step A2, the components by weight include 10-15 parts of the composite carrier, 60-70 parts of toluene and 2-5 parts of 3-aminopropyltrimethoxysilane; and 10-15 parts of the intermediate, 60-70 parts of toluene and 3-6 parts of 3-glycidoxypropyltrimethoxysilane.

10. A production process for electronic-grade diethyl carbonate according to claim 7, characterized in that, In step A3, the components include, by weight, 3-6 parts of the modified composite carrier, 0.3-0.8 parts of 1-butyl-3-methylimidazolium hydroxyacetate, 30-40 parts of deionized water, and 0.5-1 parts of 1-propylsulfonic acid-3-methylimidazolium hydrogen sulfate.