A method for transesterification of dimethyl carbonate with a polyethylene glycol-assisted supported base catalyst and application thereof

Abstract

The application discloses a method for catalyzing dimethyl carbonate by transesterification of a polyethylene glycol-assisted supported base catalyst and application thereof, and belongs to the technical field of new chemical materials. The method comprises the following steps: preparing magnesium hydroxide nanotubes by a hydrothermal method, uniformly loading a basic active component into the inner wall of the magnesium hydroxide nanotubes by a vacuum impregnation method to obtain a supported base catalyst, and catalyzing dimethyl carbonate by transesterification of the polyethylene glycol-assisted supported base catalyst to obtain methyl ethyl carbonate and diethyl carbonate. The conversion rate of the dimethyl carbonate is not less than 69%, the selectivity of the methyl ethyl carbonate is not less than 75%, and the selectivity of the diethyl carbonate is not less than 19%. Through the synergistic effect of the carrier magnesium hydroxide and the basic active component, the method can effectively improve the shortcomings of the existing dimethyl carbonate transesterification heterogeneous catalyst, such as low selectivity of target products, weak stability, easy plugging of a separator, and difficult recovery, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of new chemical materials technology, and more specifically, relates to a method and application of polyethylene glycol-assisted supported alkaline catalyst for transesterification catalysis of dimethyl carbonate. Background Technology

[0002] Electrolyte is one of the four key materials in lithium-ion batteries (positive electrode, negative electrode, separator, and electrolyte). It plays a crucial role in conducting electrons between the positive and negative electrodes, ensuring the high voltage and high specific energy of lithium-ion batteries. Electrolytes are generally formulated from high-purity organic solvents, lithium salt electrolytes, and necessary additives in specific proportions. The choice of electrolyte has a significant impact on the performance of lithium-ion batteries. It must possess good chemical stability, especially at high potentials and temperatures, and be resistant to decomposition. It must also have high ionic conductivity (>10⁻³ S / cm) and not corrode the anode and cathode materials. Because lithium-ion batteries have high charge and discharge potentials and the anode material contains chemically active lithium, the electrolyte must be an organic compound and cannot contain water. Currently, lithium-ion batteries mainly use liquid electrolytes, with anhydrous organic solvents such as ethyl carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate, which exhibit high ionic conductivity and good electrochemical stability.

[0003] Catalysts for the transesterification synthesis of methyl ethyl carbonate are broadly classified into homogeneous and heterogeneous categories. Homogeneous catalysts include soluble strong organic bases (sodium methoxide, sodium ethoxide, sodium tert-butoxide, etc.), soluble strong inorganic bases (potassium hydroxide, sodium hydroxide, etc.), other inorganic bases (potassium carbonate, sodium carbonate, potassium fluoride, etc.), and ionic liquids. Heterogeneous catalysts include ion exchange resins, metal oxides (magnesium oxide, calcium oxide, magnesium oxide-alumina, etc.), basic molecular sieves (Al-Zn-MCM-41), and MOF materials (ZIF-8 or ZIF-67). In homogeneous strong-base catalysts, the transesterification alcoholysis reaction follows a nucleophilic addition-elimination mechanism; the higher the base strength of the catalyst, the stronger its nucleophilicity and the higher the catalytic efficiency. Homogeneous catalysts offer high activity and mild reaction conditions. While this method is relatively mature, trace amounts of water in the feedstock react with the alkaline catalyst to produce hydroxides, leading to irreversible catalyst deactivation and reduced catalytic efficiency. Furthermore, the catalyst can clog the distillation tray channels after being distilled with the feedstock. Currently, the separation and recovery of this type of catalyst is mainly achieved through distillation in the later stages of the reaction. However, this later stage generates low-activity carbonates that deposit on the reactor wall, causing the methyl ethyl carbonate purity to fall short of requirements during distillation, necessitating timely removal.

[0004] Currently used heterogeneous transesterification catalysts suffer from problems such as low activity, high cost, and difficulty in separation, and have not yet been widely used in industrial applications. Future research on this type of catalyst should focus on how to achieve high catalyst activity, high selectivity for target products, and recyclability.

[0005] In recent years, there have been increasing reports on the use of solid catalysts for transesterification reactions, such as basic ion exchange resins, metal oxides, type A molecular sieves, TS-molecular sieves, and supported catalysts. However, resins have poor thermal stability, metal oxides are prone to chemical changes, molecular sieves have low transesterification activity, TS-molecular sieves have high preparation costs, and supported catalysts generally have low catalytic selectivity and poor reusability. Therefore, the preparation and application technology of heterogeneous transesterification catalysts is still under development.

[0006] Non-carbon compound nanotubes are important members of the nanomaterial family. Due to their high volume percentage specific surface area, they exhibit high chemical activity and outstanding physical properties. Through physical and chemical modification methods, nanotubes can be endowed with new functional properties, showing significant application prospects in fields such as information components, biosensors, catalytic materials, ion channels, smart drugs, microtools, and advanced aerospace materials. However, existing heterogeneous catalysts for dimethyl carbonate transesterification reactions suffer from problems such as low activity, low selectivity for ethyl methyl carbonate, and decreased recyclability. Summary of the Invention

[0007] To address the aforementioned problems in the existing technology, the technical problem to be solved by the present invention is to provide a method for transesterification catalysis of dimethyl carbonate using a polyethylene glycol-assisted supported base catalyst. This method selectively loads the active component into magnesium hydroxide nanotubes via a vacuum impregnation loading method, avoiding the loss of active component due to stirring and mass transfer during the reaction. While maintaining high catalytic efficiency, it also possesses good recyclability. By adding a polyethylene glycol auxiliary agent of a specific molecular weight, the amount of heterogeneous catalyst used can be reduced, thereby increasing the reaction rate. Another technical problem to be solved by the present invention is to provide the application of the above-mentioned polyethylene glycol-assisted supported base catalyst in the transesterification synthesis of ethyl methyl carbonate and diethyl carbonate from dimethyl carbonate and ethanol.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0009] A method for transesterification catalysis of dimethyl carbonate using a polyethylene glycol-assisted supported base catalyst involves using a polyethylene glycol-assisted supported base catalyst to catalyze the transesterification reaction of dimethyl carbonate to obtain methyl ethyl carbonate and diethyl carbonate; wherein the conversion rate of dimethyl carbonate is not less than 69%, the selectivity of methyl ethyl carbonate is not less than 75%, and the selectivity of diethyl carbonate is not less than 19%.

[0010] Preferably, the supported alkaline catalyst is composed of an alkaline active component and a magnesium hydroxide nanotube support; wherein the alkaline active component is selected from any one of C1 to C4 organic alkoxides of lithium, potassium, and sodium, the alkaline active component accounts for 5 to 20% of the catalyst weight, and the magnesium hydroxide nanotube accounts for 80 to 95% of the catalyst weight.

[0011] Preferably, the polyethylene glycol has a molecular weight of 600-1000, and the amount of polyethylene glycol added is 0.5%-2% of the mass of dimethyl carbonate.

[0012] Preferably, the polyethylene glycol has a molecular weight of 800, and the amount of polyethylene glycol added is 1% of the mass of dimethyl carbonate.

[0013] Preferably, the preparation process of the supported alkaline catalyst is as follows: magnesium hydroxide nanotubes are prepared by hydrothermal method, and alkaline active components are uniformly loaded onto the inner wall of the magnesium hydroxide nanotubes by vacuum impregnation method to obtain the supported alkaline catalyst; preferably, the prepared magnesium hydroxide nanotubes are open at both ends, and no end opening treatment is required before loading the alkaline active components. The inner diameter of the magnesium hydroxide nanotubes is between 4 and 10 nm, the outer diameter is between 20 and 50 nm, and the tube length is between 200 nm and 5 μm.

[0014] The method for transesterification catalysis of dimethyl carbonate using a polyethylene glycol-assisted supported base catalyst includes the following steps:

[0015] 1) Dissolve sodium hydroxide, potassium hydroxide and magnesium carbonate in deionized water, stir thoroughly and transfer to a high-pressure reactor. Stir at low speed at 160-200℃ for 12-24 hours and then cool to room temperature. After filtering, washing and drying the mixture in the reactor, magnesium hydroxide nanotubes are obtained.

[0016] 2) After the alkaline active component and ethanol are stirred and dissolved, the magnesium hydroxide nanotubes from step 1) are added. After stirring, the mixture is subjected to multiple vacuum pretreatments under ultrasonic action. Then, the ethanol is slowly evaporated at 20-30°C to obtain a white solid. After drying, the supported alkaline catalyst is obtained.

[0017] 3) Place ethanol, dimethyl carbonate, supported alkaline catalyst and polyethylene glycol into a reaction vessel. The transesterification reaction temperature is 80℃~120℃ and the pressure is atmospheric pressure. After reacting for 1~6 hours under reflux and stirring conditions, methyl ethyl carbonate and diethyl carbonate are obtained by centrifugation. After the transesterification reaction is completed, the reaction products are removed online and can be used directly without any treatment.

[0018] Preferably, in step 3), the molar ratio of dimethyl carbonate to ethanol is 1:1 to 1:3, the amount of supported alkaline catalyst is 0.2% to 1% of the mass of raw material dimethyl carbonate, and the amount of polyethylene glycol added is 0.5% to 2% of the mass of dimethyl carbonate.

[0019] Preferably, in step 3), the molar ratio of dimethyl carbonate to ethanol is 1:2, the amount of supported alkaline catalyst is 0.8% of the mass of raw material dimethyl carbonate, the molecular weight of polyethylene glycol is 800, and the amount of polyethylene glycol added is 1% of the mass of dimethyl carbonate.

[0020] Preferably, in step 3), the transesterification reaction temperature is 95°C and the reaction time is 4 hours.

[0021] The application of the polyethylene glycol-assisted supported base catalyst in the transesterification synthesis of ethyl methyl carbonate and diethyl carbonate from dimethyl carbonate and ethanol.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1) This invention uses magnesium hydroxide nanotubes as a carrier and selectively loads the active component alkaline compound onto the inner wall of the magnesium hydroxide nanotubes through a vacuum impregnation loading method. This fully utilizes the special confinement effect and surface effect of magnesium hydroxide nanotubes to increase the reactant density and catalytic efficiency within the tubes, thereby effectively initiating catalytic sites.

[0024] 2) In this invention, the active component is immobilized on the inner wall of magnesium hydroxide nanotubes to avoid loss of active component due to stirring and mass transfer during the reaction. The active component is connected to the carrier in a bonded manner, which can effectively prevent loss of active component and maintain high catalytic efficiency while also having good recyclability.

[0025] 3) The catalyst prepared by this invention has good catalytic activity and reaction performance through the synergistic effect of the support magnesium hydroxide and the basic active component. It can effectively improve the problems of low target product selectivity, weak stability, easy clogging of separator and difficult recovery of existing heterogeneous catalysts for dimethyl carbonate transesterification reaction, and has good prospects for industrial application.

[0026] 4) Compared with the prior art, the supported catalyst prepared by the present invention can reduce the amount of ethanol used in the raw materials and improve production efficiency. By adding polyethylene glycol additives with a specific molecular weight, the amount of heterogeneous catalyst used can be reduced and the reaction rate can be increased.

[0027] 5) The supported base catalyst prepared by this method can be used directly after the reaction products are removed online after the transesterification reaction is completed, without any treatment. The catalyst still maintains good catalytic activity during recycling. Due to its high boiling point, the auxiliary agent polyethylene glycol remains in the substrate after distillation and can be recycled without the need to add new auxiliary agent. Attached Figure Description

[0028] Figure 1 TEM image of the active component prepared in this invention loaded on the inner wall of magnesium hydroxide nanotubes. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is further described below with reference to specific embodiments. Unless otherwise specified, the technical means used in the following embodiments are all conventional means well known to those skilled in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0030] Example 1

[0031] 8.0 g of sodium hydroxide, 6 g of potassium hydroxide, and 15 g of magnesium carbonate were weighed and dissolved in 100 mL of deionized water. The solution was then transferred to a 250 mL autoclave and sealed. The autoclave was stirred at low speed at 200 °C for 12 h. After the reaction was complete, the autoclave was allowed to cool naturally to room temperature. The reaction solution was then filtered, and the filter cake was washed three times with deionized water and ethanol, respectively. The final product was dried at 120 °C for 6 h, yielding a white powder, which was magnesium hydroxide nanotubes, with a yield of 92.8%. Transmission electron microscopy (TEM) measurements showed that... Figure 1 As shown, the inner diameter of the magnesium hydroxide nanotubes is between 4 and 10 nm, the outer diameter is between 20 and 50 nm, and the tube length is between 200 nm and 5 μm.

[0032] Example 2

[0033] The dimethyl carbonate transesterification reaction was carried out using 1.8 g of a supported catalyst. The catalyst contained 20% (wt%) sodium methoxide as the active component and 80% (wt%) magnesium hydroxide nanotubes as the magnesium hydroxide nanotubes. The catalyst was prepared according to the following steps:

[0034] (1) Weigh 0.36g sodium methoxide and 5.0g ethanol into a flask, stir to dissolve, and then add 1.44g magnesium hydroxide nanotubes prepared according to the method in Example 1, and stir to impregnate;

[0035] (2) The flask was connected to a vacuum pump for evacuation. After repeated evacuation and evacuation at room temperature, and ultrasonic treatment for 0.5 h, the flask was placed in a 30°C water bath to slowly evaporate the liquid and obtain a white solid.

[0036] (3) The prepared solid was placed in an oven and dried at 100°C for 4 hours to prepare a supported transesterification catalyst.

[0037] Using a 500ml three-necked flask, add 90g of dimethyl carbonate and 46g of ethanol, then add 1.8g of the prepared catalyst and 0.45g of polyethylene glycol (molecular weight 600). Connect a reflux-condenser receiver to the top of the flask to recover the byproduct methanol. The reaction temperature is 80℃ and the reaction time is 6h.

[0038] The reaction results were analyzed by gas chromatography. The conversion rate and product selectivity of dimethyl carbonate were calculated using the external standard method, as follows:

[0039] Dimethyl carbonate conversion rate % = (molar amount of raw material dimethyl carbonate - molar amount of remaining dimethyl carbonate) × 100% / molar amount of raw material dimethyl carbonate;

[0040] ethyl methyl carbonate selectivity % = (molar amount of ethyl methyl carbonate) × 100% / (molar amount of raw material dimethyl carbonate - molar amount of remaining dimethyl carbonate)

[0041] Diethyl carbonate selectivity % = (Molar amount of diethyl carbonate) × 100% / (Molar amount of raw material dimethyl carbonate - Molar amount of remaining dimethyl carbonate)

[0042] The analytical results of Example 2 showed that the dimethyl carbonate conversion rate was 78.4%, the methyl ethyl carbonate selectivity was 75.2%, and the diethyl carbonate selectivity was 24.8%.

[0043] Example 3

[0044] In this embodiment, 0.18 g of supported catalyst was prepared using the same method as in Examples 1 and 2, but the active component was sodium tert-butoxide. The catalyst contained 15% (wt%) sodium tert-butoxide and 85% (wt%) magnesium hydroxide nanotubes, with 0.03 g of sodium tert-butoxide and 0.15 g of magnesium hydroxide nanotubes used. The same reaction apparatus as in Example 2 was used, with 90 g of dimethyl carbonate, 138 g of ethanol, and 0.18 g of the prepared catalyst and 1.8 g of polyethylene glycol (molecular weight 1000) added. The reaction temperature was 120°C, and the reaction time was 6 h. Using the same analytical method as in Example 2, the dimethyl carbonate conversion was 69.1%, the methyl ethyl carbonate selectivity was 78.3%, and the diethyl carbonate selectivity was 21.7%.

[0045] Example 4

[0046] In this embodiment, 0.72 g of supported catalyst was prepared using the same method as in Examples 1 and 2, but the active component was potassium ethoxide. The potassium ethoxide content in the catalyst was 20% (wt%), and the magnesium hydroxide nanotube content was 80% (wt%). The same reaction apparatus as in Example 2 was used, with 90 g of dimethyl carbonate and 138 g of ethanol added, along with 0.72 g of the prepared catalyst and 0.9 g of polyethylene glycol (molecular weight 800). The reaction temperature was 100°C, and the reaction time was 4 h. Using the same analytical method as in Example 2, the dimethyl carbonate conversion rate was 91.7%, the methyl ethyl carbonate selectivity was 80.1%, and the diethyl carbonate selectivity was 19.9%.

[0047] Example 5

[0048] In this embodiment, 0.90 g of supported catalyst was prepared using the same method as in Examples 1 and 2. The active component was sodium isopropoxide, and the catalyst contained 15% (wt%) potassium carbonate and 85% (wt%) magnesium hydroxide nanotubes. The same reaction apparatus as in Example 2 was used, with 90 g of dimethyl carbonate, 138 g of ethanol, and 0.90 g of the prepared catalyst and 0.6 g of polyethylene glycol (molecular weight 1000) added. The reaction temperature was 90°C, and the reaction time was 4 h. Using the same analytical method as in Example 2, the dimethyl carbonate conversion rate was 83.4%, the methyl ethyl carbonate selectivity was 76.7%, and the diethyl carbonate selectivity was 23.3%.

[0049] Example 6

[0050] In this embodiment, 0.72 g of supported catalyst was prepared using the same method as in Examples 1 and 2. The active component was sodium ethoxide, and the catalyst contained 15% (wt%) sodium ethoxide and 85% (wt%) magnesium hydroxide nanotubes. The same reaction apparatus as in Example 2 was used, with 90 g of dimethyl carbonate, 92 g of ethanol, and 0.72 g of the prepared catalyst and 0.9 g of polyethylene glycol (molecular weight 1000) added. The reaction temperature was 95°C, and the reaction time was 4 h. Using the same analytical method as in Example 2, the dimethyl carbonate conversion rate was 93.1%, the methyl ethyl carbonate selectivity was 82.3%, and the diethyl carbonate selectivity was 17.7%.

[0051] Example 7

[0052] This embodiment uses the same supported catalyst as in Example 6 and the same reaction apparatus as in Example 2. 90g of dimethyl carbonate and 92g of ethanol were used, along with 0.72g of the prepared catalyst and 0.9g of polyethylene glycol (molecular weight 800). The reaction temperature was 95℃, and the reaction time was 4 hours. After the reaction, all unreacted raw materials and products were distilled off under reduced pressure, leaving only the transesterification catalyst in the flask. Then, 90g of dimethyl carbonate and 92g of ethanol were added to initiate a catalyst recycling reaction. The reaction was repeated 10 times, and the experimental results are shown in Table 1.

[0053] Table 1. Reaction performance of transesterification catalysts after recycling

[0054]

[0055] As shown in Table 1, the transesterification catalyst prepared in this invention maintains good activity and catalytic performance even after 10 cycles. The conversion rate of dimethyl carbonate remains above 90%, and the selectivity of the target product, ethyl methyl carbonate, remains stable within a certain range. The catalyst exhibits good stability and can be recycled multiple times.

[0056] Comparative Example 1

[0057] The same catalyst as in Example 4 was used, along with the same reaction apparatus and experimental methods as in Example 2. 90g of dimethyl carbonate and 138g of ethanol were used, and 0.72g of the prepared catalyst was added. The reaction temperature was 100℃, and the reaction time was 4h. The experimental results are shown in Table 2.

[0058] Comparative Example 2

[0059] The same catalyst as in Example 4 was used, along with the same reaction apparatus and experimental methods as in Example 2. 90g of dimethyl carbonate and 138g of ethanol were used, along with 0.72g of the prepared catalyst and 0.9g of polyethylene glycol (molecular weight 400). The reaction temperature was 100℃, and the reaction time was 4h. The experimental results are shown in Table 2.

[0060] Comparative Example 3

[0061] The same catalyst as in Example 4 was used, along with the same reaction apparatus and experimental methods as in Example 2. 90g of dimethyl carbonate and 138g of ethanol were used, along with 0.72g of the prepared catalyst and 0.9g of polyethylene glycol (molecular weight 2000). The reaction temperature was 100℃, and the reaction time was 4h. The experimental results are shown in Table 2.

[0062] Comparative Example 4

[0063] Using 0.72g of commercially available industrial sodium methoxide transesterification catalyst, and following the same reaction apparatus and experimental method as in Example 4, 90g of dimethyl carbonate and 138g of ethanol were added, followed by 0.72g of sodium methoxide catalyst and 0.9g of polyethylene glycol (molecular weight 800). The reaction temperature was 100℃ and the reaction time was 4h. The experimental results are shown in Table 2.

[0064] Comparative Example 5

[0065] Commercially available magnesium hydroxide powder was used as a carrier to prepare a 0.72 g supported catalyst for the dimethyl carbonate transesterification reaction. The catalyst contained 20% (wt%) potassium ethoxide and 80% (wt%) magnesium hydroxide as the active component. The loading method of the active component was the same as in Example 2. Following the same reaction apparatus and experimental method as in Example 4, 90 g of dimethyl carbonate and 138 g of ethanol were added, followed by 0.72 g of sodium methoxide catalyst and 0.9 g of polyethylene glycol (molecular weight 800). The reaction temperature was 100 °C, and the reaction time was 4 h. The experimental results are shown in Table 2.

[0066] Table 2. Results of experimental reactions in Comparative Examples 1-5

[0067]

[0068]

[0069] As shown in Table 2, compared with Example 4, the addition of polyethylene glycol (PEG) significantly improved the conversion rate of dimethyl carbonate in Comparative Example 1. As shown in Comparative Examples 2 and 3, the conversion rate of dimethyl carbonate was only slightly improved when the molecular weight of PEG was small or large. Based on the reaction results of the examples, it can be seen that when the molecular weight of PEG is between 600 and 1000, the conversion rate of dimethyl carbonate can be effectively improved.

[0070] Compared with currently used sodium methoxide catalysts in industrial applications, the supported catalyst prepared in this invention achieves a similar conversion rate of dimethyl carbonate. However, the supported transesterification catalyst exhibits better selectivity for the target product, ethyl methyl carbonate, because the active component is supported on the inner wall of magnesium hydroxide nanotubes. Utilizing the unique internal structure and confinement effect of magnesium hydroxide nanotubes, along with the synergistic effect of the magnesium hydroxide support and the basic active component, the catalyst's reactivity is enhanced. In contrast, Comparative Example 5, using magnesium hydroxide powder as a support, produced a catalyst with significantly lower reactivity, demonstrating that the transesterification catalyst using magnesium hydroxide nanotubes as a support possesses excellent reactivity. The comparative experimental results prove that the catalyst prepared in this invention exhibits good reactivity and selectivity for the target product.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for the transesterification of dimethyl carbonate catalyzed by polyethylene glycol assisted supported base catalyst characterized in that, The catalytic transesterification reaction of dimethyl carbonate is carried out by using a polyethylene glycol assisted supported base catalyst to obtain methyl ethyl carbonate and diethyl carbonate; wherein the conversion rate of the dimethyl carbonate is not less than 69%, the selectivity of the methyl ethyl carbonate is not less than 75%, and the selectivity of the diethyl carbonate is not less than 19%; the supported base catalyst is composed of a basic active component and a carrier magnesium hydroxide nanotube; wherein the basic active component is selected from any one of C1-C4 organic alkali of lithium, potassium and sodium elements, the basic active component accounts for 5-20% of the weight of the catalyst, and the magnesium hydroxide nanotube accounts for 80-95% of the weight of the catalyst; the molecular weight of the polyethylene glycol is 600-1000, and the addition amount of the polyethylene glycol is 0.5-2% of the mass of the dimethyl carbonate.

2. The process of claim 1, wherein the polyethylene glycol-assisted supported base catalyst transesterification of dimethyl carbonate is characterized by, The molecular weight of the polyethylene glycol is 800, and the addition amount of the polyethylene glycol is 1% of the mass of the dimethyl carbonate.

3. The process of claim 1, wherein the polyethylene glycol-assisted supported base catalyst transesterification of dimethyl carbonate is characterized by, The preparation process of the supported base catalyst is as follows: magnesium hydroxide nanotubes are prepared by a hydrothermal method, and the basic active component is uniformly loaded on the inner wall of the magnesium hydroxide nanotubes by vacuum impregnation to obtain the supported base catalyst.

4. The process of claim 1, wherein the polyethylene glycol-assisted supported base catalyst transesterification of dimethyl carbonate is characterized by, The method comprises the following steps: 1) Dissolve sodium hydroxide, potassium hydroxide and magnesium carbonate in deionized water, and after sufficient stirring, transfer to a high-pressure reaction kettle, cool to room temperature after low-speed stirring at 160-200℃ for 12-24h, and then filter, wash and dry the mixture in the kettle to obtain magnesium hydroxide nanotubes; 2) Dissolve the basic active component and ethanol by stirring, then add the magnesium hydroxide nanotubes of step 1), and then perform multiple vacuum pretreatments under the action of ultrasonic waves, and then slowly evaporate ethanol at 20-30℃ to obtain a white solid, and then dry to obtain the supported base catalyst; 3) Put ethanol, dimethyl carbonate, the supported base catalyst and polyethylene glycol into a reaction container, the transesterification reaction temperature is 80-120℃, the pressure is normal pressure, and after reaction under reflux stirring for 1-6h, centrifugal separation is performed to obtain methyl ethyl carbonate and diethyl carbonate, and after the transesterification reaction is completed, the reaction products are evaporated in line, and no treatment is required, and the products can be directly used.

5. The process of claim 4, wherein the polyethylene glycol-assisted supported base catalyst transesterification of dimethyl carbonate is characterized by, In step 3), the molar ratio of dimethyl carbonate to ethanol is 1:1-1:3, the amount of the supported base catalyst is 0.2-1% of the mass of the raw dimethyl carbonate, and the addition amount of the polyethylene glycol is 0.5-2% of the mass of the dimethyl carbonate.

6. The process of claim 5, wherein the polyethylene glycol-assisted supported base catalyst transesterification of dimethyl carbonate is characterized by, In step 3), the molar ratio of dimethyl carbonate to ethanol is 1:2, the amount of the supported base catalyst is 0.8% of the mass of the raw dimethyl carbonate, the molecular weight of the polyethylene glycol is 800, and the addition amount of the polyethylene glycol is 1% of the mass of the dimethyl carbonate.

7. The process of claim 4, wherein the polyethylene glycol-assisted supported base catalyst transesterification of dimethyl carbonate is characterized by, In step 3), the transesterification reaction temperature is 95℃, and the reaction time is 4h.

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