Synthesis method of trimethylene carbonate

Abstract

The invention discloses a synthesis method of trimethylene carbonate, which comprises the following steps: sequentially adding a MO-Ce-CMNDI catalyst, 2-cyano furan, potassium carbonate and 1, 3-propylene glycol into a reaction kettle in a water-free and oxygen-free environment, introducing CO2 for reaction, and obtaining a target product after the reaction is finished. When the MO-Ce-CMNDI catalyst is used for the trimethylene carbonate synthesis reaction, the catalytic activity is high, the reusability is good, and the yield of the product is improved.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis, specifically relating to a method for synthesizing trimethylene carbonate. Background Technology

[0002] Trimethylene carbonate, as a key polymer monomer, is mainly used in the production of biodegradable medical materials such as polytrimethylene carbonate (PTMC). PTMC materials are widely used in biomedical fields such as ligation devices and implant materials due to their non-toxicity and excellent mechanical properties. Compared with other carbonates, trimethylene carbonate produces no byproducts during ring-opening polymerization, can rapidly reach high molecular weights, and does not generate CO2, making it an ideal polycarbonate monomer. It can also be copolymerized with glycolide, lactide, etc., to prepare medical polymer materials with different functions. However, the large-scale synthesis technology of trimethylene carbonate in China is still immature, while abroad it is mainly synthesized through transesterification and phosgene methods. The phosgene method is being phased out due to its toxicity and environmental harm, while the transesterification method has limitations due to low yield and poor selectivity.

[0003] In contrast, the direct cyclization of CO2 and 1,3-propanediol to synthesize trimethylene carbonate is a promising synthetic route. However, most catalysts used in current studies for the synthesis of this substance have low activity and are limited in yield and selectivity due to phase equilibrium limitations. Therefore, finding highly active catalysts and overcoming phase equilibrium constraints are of great significance for the synthesis of trimethylene carbonate. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for synthesizing trimethylene carbonate. The MO@Ce-CMNDI catalyst used in this invention exhibits high catalytic activity and good reusability in the trimethylene carbonate synthesis reaction, thereby improving the product yield.

[0005] The method for synthesizing trimethylene carbonate of the present invention includes the following steps: under an anhydrous and oxygen-free environment, MO@Ce-CMNDI catalyst, 2-cyanofuran, 1,3-propanediol and potassium carbonate are added sequentially to a reaction vessel, and CO2 is introduced to carry out the reaction. After the reaction is completed, the target product is obtained. The MO@Ce-CMNDI catalyst is wherein MO represents one of the metal oxides such as MgO, Ag2O, ZnO, CuO, Fe2O3, CeO2, SiO2, Al2O3, TiO2, etc., preferably Ag2O; Ce-CMNDI represents the metal coordination network material [Ce(CMNDI)(CH3COO)(H2O)2]·H2O synthesized from Ce(NO3)3·6H2O and N,N'-di(carboxymethyl)-1,4,5,8-naphthalenedimide.

[0006] The reaction conditions are as follows: the pressure inside the reactor is 2-5 MPa; the reaction temperature is 100-160℃, preferably 120-140℃; the reaction time is 0.5-8 h, preferably 3-5 h; wherein the molar ratio of MO@Ce-CMNDI catalyst, 2-cyanofuran, 1,3-propanediol and potassium carbonate is 1-3:10:10:10.

[0007] The reaction route is as follows:

[0008]

[0009] The preparation method of the MO@Ce-CMNDI catalyst of the present invention includes the following steps:

[0010] (1) Dissolve 1,4,5,8-naphthalenetetracarboxylic dianhydride and glycine in an appropriate amount of organic solvent and reflux the reaction mixture. Filter, wash and dry the reaction mixture to obtain a solid product;

[0011] (2) Dissolve the solid powder from step 1 and Ce(NO3)3·6H2O in a mixed solvent, add HNO3 solution and react for a period of time to obtain Ce-CMNDI;

[0012] (3) The Ce-CMNDI and metal oxide prepared in step (2) are mechanically ground, transferred to a solvent, stirred evenly, and subjected to hydrothermal reaction. After the reaction is completed, the solid product is filtered and washed, and then calcined in a muffle furnace to obtain the catalyst MO@Ce-CMNDI.

[0013] The solvent mentioned in step (1) is one or more of the following: ethanol, methanol, isopropanol, ethylene glycol, acetonitrile, acetic acid, propionic acid, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, benzene, toluene, chlorobenzene, dichloromethane, pyridine, and tetrahydrofuran.

[0014] The molar ratio of 1,4,5,8-naphthalenetetracarboxylic dianhydride and glycine in step (1) is 1:2 to 1:4, and the ratio of organic solvent to solute is 10 mL: 2 mmol to 10 mL: 1 mmol.

[0015] The reflux reaction conditions described in step (1) are: temperature 80-120℃ and time 8-12 hours.

[0016] The reaction mixture obtained from the reflux reaction in step (1) is filtered to obtain a solid product, which is then washed with deionized water and anhydrous ethanol. Drying is preferably carried out under vacuum conditions, with a drying temperature of 50-80°C and a drying time of 12-24 hours.

[0017] The addition ratio of the solid powder, Ce(NO3)3·6H2O, mixed solvent and HNO3 solution in step (2) is 0.01mmol:0.04mmol:4mL:100μL to 0.01mmol:0.06mmol:5mL:300μL.

[0018] The mixed solvent in step (2) is a combination of two or more strongly polar solvents such as N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF), ethanol, methanol, acetonitrile, ethylene glycol, isopropanol or water, preferably DMA and water, with a solvent ratio of 3:1 to 6:1.

[0019] The reaction conditions described in step (2) are: reacting at 80-110℃ for 2-4 days.

[0020] The metal oxide mentioned in step (3) is a metal oxide such as MgO, ZnO, CuO, Fe2O3, CeO2, SiO2, Al2O3, TiO2, etc., preferably Ag2O. The solvent is ethanol, methanol, isopropanol, ethylene glycol, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, benzene, toluene, chlorobenzene, dichloromethane, pyridine, and tetrahydrofuran, preferably ethanol.

[0021] The roasting temperature in step (3) is 300-500℃ and the roasting time is 5-10 hours.

[0022] In step (3), the ratio of Ce-CMNDI to metal oxide is 1:1 to 1:4.

[0023] The mixing and dispersion in step (3) needs to achieve the goal of no obvious lumpy solids in the solution, which can be achieved by stirring, sonication, or other methods.

[0024] The hydrothermal reaction described in step (3) is generally carried out in a hydrothermal reactor. The hydrothermal reaction conditions are: temperature of 120-180℃ and time of 5-24h. After the reaction is completed, the reactor is cooled to room temperature, filtered, and the solid product is washed with deionized water and anhydrous ethanol. It is then dried at 50-80℃ and calcined to obtain the catalyst MO@Ce-CMNDI.

[0025] This invention synthesizes trimethylene carbonate using greenhouse gases as a carbon source, enabling the synthesis of high-value-added chemicals from CO2. The synthesis method is simple and does not require harsh conditions such as high temperature and high pressure. The required alkali is inexpensive, and the catalyst is simple to prepare and can be reused after simple treatment. The catalyst contains metal oxides with high catalytic activity, numerous Ce-CMNDI active groups, a large specific surface area, and high porosity. It contains hydrogen bond acceptors for coordination molecules, and there are π-π interactions between NDI molecules, which can adsorb MO. In addition, cerium ions and NDI nuclei have redox activity, which can promote the interaction between the Lewis acid sites of MO and 1,3-propanediol, thus exhibiting good catalytic activity. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the single-crystal structure of the catalyst in Example 1.

[0027] Figure 2 This is a photograph of the synthesized product from Example 12. Detailed Implementation

[0028] The present invention will be further described in detail below through embodiments, but these embodiments are not intended to limit the invention. The yield calculation formula is: Actual yield / Theoretical yield × 100%

[0029] Example 1: Preparation of Ce-CMNDI

[0030] 10 mmol (2.682 g) of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 25 mmol (1.875 g) of glycine were dissolved in 200 mL of propionic acid. The reaction mixture was transferred to a round-bottom flask and refluxed at 110 °C for 15 h. The reaction mixture was filtered to obtain a solid product, which was then washed with deionized water and anhydrous ethanol. The resulting product was transferred to a vacuum drying oven and dried at 70 °C for 12 h, with a yield of 75%. 0.02 mmol (10 mg) of the product (N,N'-di(carboxymethyl)-1,4,5,8-naphthalenedimide) and 0.02 mmol (9 mg) of Ce(NO3)3·6H2O were dissolved in a mixture of 2 mL of DMA and 0.5 mL of water. Then, 300 μL of 8 M HNO3 solution was added to the solution. The solution mixture was sonicated at room temperature for 2 h. The mixture was transferred to a Pyrex heat-resistant glass bottle. After heating at 100°C for 3 days, the catalyst Ce-CMNDI was obtained by cooling to room temperature and filtering. Figure 1 It has a single-crystal structure.

[0031] Example 2: Preparation of catalyst MgO@Ce-CMNDI

[0032] 0.2 mmol (0.1 g) of the prepared Ce-CMNDI and 0.6 mmol (0.02 g) of MgO were ground in an agate mortar for 30 min, transferred to 50 mL of N,N-dimethylacetamide, and stirred until no obvious lumpy solids were found. The mixture was then transferred to a hydrothermal reactor and reacted at 160 °C for 24 h. After the reactor cooled to room temperature, the mixture was filtered, and the solid product was washed with deionized water and anhydrous ethanol and dried at 80 °C. The product was then calcined in a muffle furnace at 300 °C for 6 h to obtain the catalyst MgO@Ce-CMNDI.

[0033] Example 3: Preparation of catalyst Ag2O@Ce-CMNDI

[0034] 0.2 mmol (0.1 g) of the prepared Ce-CMNDI and 0.4 mmol (0.09 g) of Ag₂O were ground in an agate mortar for 60 min, transferred to 60 mL of ethanol, and stirred until no obvious lumpy solids were found. The mixture was then transferred to a hydrothermal reactor and reacted at 120 °C for 12 h. After the reactor cooled to room temperature, the mixture was filtered, and the solid product was washed with deionized water and anhydrous ethanol and dried at 80 °C. The product was then calcined in a muffle furnace at 350 °C for 5 h to obtain the catalyst Ag₂O@Ce-CMNDI.

[0035] Example 4: Preparation of catalyst ZnO@Ce-CMNDI

[0036] 0.2 mmol (0.1 g) of the prepared Ce-CMNDI and 0.4 mmol (0.04 g) of ZnO were ground in an agate mortar for 30 min, transferred to 50 mL of acetonitrile, and stirred until no obvious lumpy solids were found. The mixture was then transferred to a hydrothermal reactor and reacted at 120 °C for 12 h. After the reactor cooled to room temperature, the mixture was filtered, and the solid product was washed with deionized water and anhydrous ethanol and dried at 80 °C. The product was then calcined in a muffle furnace at 300 °C for 6 h to obtain the catalyst ZnO@Ce-CMNDI.

[0037] Example 5: Preparation of the catalyst CuO@Ce-CMNDI

[0038] 0.2 mmol (0.1 g) of the prepared Ce-CMNDI and 0.6 mmol (0.05 g) of CuO were ground in an agate mortar for 40 min, transferred to 70 mL of ethanol, and stirred until no obvious lumpy solids were found. The mixture was then transferred to a hydrothermal reactor and reacted at 140 °C for 10 h. After the reactor cooled to room temperature, the mixture was filtered, and the solid product was washed with deionized water and anhydrous ethanol and dried at 80 °C. The product was then calcined in a muffle furnace at 300 °C for 8 h to obtain the catalyst CuO@Ce-CMNDI.

[0039] Example 6: Preparation of catalyst Fe2O3@Ce-CMNDI

[0040] 0.2 mmol (0.1 g) of the prepared Ce-CMNDI and 0.6 mmol (0.09 g) of Fe2O3 were ground in an agate mortar for 40 min, transferred to 50 mL of N,N-dimethylformamide, and stirred until no obvious lumpy solids were found. The mixture was then transferred to a hydrothermal reactor and reacted at 200 °C for 10 h. After the reactor cooled to room temperature, the mixture was filtered, and the solid product was washed with deionized water and anhydrous ethanol and dried at 80 °C. The product was then calcined in a muffle furnace at 400 °C for 8 h to obtain the catalyst Fe2O3@Ce-CMNDI.

[0041] Example 7 Preparation of the catalyst CeO2@Ce-CMNDI

[0042] 0.2 mmol (0.1 g) of the prepared Ce-CMNDI and 0.4 mmol (0.06 g) of CeO2 were ground in an agate mortar for 30 min, transferred to 80 mL of ethanol, and stirred until no obvious lumpy solids were found. The mixture was then transferred to a hydrothermal reactor and reacted at 130 °C for 12 h. After the reactor cooled to room temperature, the mixture was filtered, and the solid product was washed with deionized water and anhydrous ethanol and dried at 80 °C. The product was then calcined in a muffle furnace at 350 °C for 8 h to obtain the catalyst CeO2@Ce-CMNDI.

[0043] Example 8: Preparation of SiO2@Ce-CMNDI catalyst

[0044] 0.2 mmol (0.1 g) of the prepared Ce-CMNDI and 0.6 mmol (0.04 g) of SiO2 were ground in an agate mortar for 30 min, transferred to 70 mL of acetonitrile, and stirred until no obvious lumpy solids were found. The mixture was then transferred to a hydrothermal reactor and reacted at 120 °C for 16 h. After the reactor cooled to room temperature, the mixture was filtered, and the solid product was washed with deionized water and anhydrous ethanol and dried at 80 °C. The product was then calcined in a muffle furnace at 450 °C for 8 h to obtain the catalyst SiO2@Ce-CMNDI.

[0045] Example 9: Preparation of catalyst Al2O3@Ce-CMNDI

[0046] 0.2 mmol (0.1 g) of the prepared Ce-CMNDI and 0.6 mmol (0.06 g) of Al2O3 were ground in an agate mortar for 30 min, transferred to 50 mL of N,N-dimethylacetamide, and stirred until no obvious lumpy solids were found. The mixture was then transferred to a hydrothermal reactor and reacted at 200 °C for 16 h. After the reactor cooled to room temperature, the mixture was filtered, and the solid product was washed with deionized water and anhydrous ethanol and dried at 80 °C. The product was then calcined in a muffle furnace at 300 °C for 8 h to obtain the catalyst Al2O3@Ce-CMNDI.

[0047] Example 10 Preparation of the catalyst TiO2@Ce-CMNDI

[0048] 0.2 mmol (0.1 g) of the prepared Ce-CMNDI and 0.6 mmol (0.05 g) of TiO2 were ground in an agate mortar for 30 min, transferred to 70 mL of ethylene glycol, and stirred until no obvious lumpy solids were found. The mixture was then transferred to a hydrothermal reactor and reacted at 120 °C for 12 h. After the reactor cooled to room temperature, the mixture was filtered, and the solid product was washed with deionized water and anhydrous ethanol and dried at 80 °C. The product was then calcined in a muffle furnace at 300 °C for 9 h to obtain the catalyst TiO2@Ce-CMNDI.

[0049] Example 11: Synthesis of Trimethylene Carbonate Catalyzed by MgO@Ce-CMNDI

[0050] The structural formula of trimethylene carbonate is as follows:

[0051]

[0052] Under anhydrous and oxygen-free conditions, 6 mmol (0.4 g) MgO@Ce-CMNDI, 20 mmol (1.9 g) 2-cyanofuran, 20 mmol (1.5 g) 1,3-propanediol, and 20 mmol (2.7 g) K₂CO₃ were added sequentially to a 100 mL high-pressure stainless steel reactor. The reactor was sealed, and the air inside was replaced three times with CO₂. CO₂ was then introduced at a certain pressure at room temperature, and the temperature was raised to 120 °C for 5 h. During the heating process, the pressure was monitored to ensure that the pressure inside the reactor was 4 MPa when the reaction temperature was reached. After the reaction was complete, the reactor was allowed to cool to room temperature and excess gas was released. The reactor was opened only after all gas had been released, the catalyst was removed by filtration, and the solvent was removed by vacuum to obtain the target product in 45% yield.

[0053] The NMR data are as follows: 1 H NMR (400MHz, CDCl3) δ (ppm): 4.24 (t, J = 6.0Hz, 4H), 2.08-2.02 (m, 2H).

[0054] Example 12: Synthesis of Trimethylene Carbonate Catalyzed by Ag2O@Ce-CMNDI

[0055] Under anhydrous and oxygen-free conditions, 6 mmol (0.5 g) Ag₂O@Ce-CMNDI, 20 mmol (1.5 g) 1,3-propanediol, 20 mmol (2.7 g) K₂CO₃, and 20 mmol (1.9 g) 2-cyanofuran were added sequentially to a 100 mL high-pressure stainless steel reactor. The reactor was sealed, and the air inside was replaced three times with CO₂. CO₂ was then introduced at a certain pressure at room temperature, and the temperature was raised to 120 °C for 5 h. During the heating process, the pressure was monitored to ensure that the pressure inside the reactor was 4 MPa when the reaction temperature was reached. After the reaction was complete, the reactor was allowed to cool to room temperature and excess gas was released. The reactor was opened only after all gas had been released, the catalyst was removed by filtration, and the solvent was removed by vacuum to obtain the target product with a yield of 95%.

[0056] Example 13: CuO@Ce-CMNDI-catalyzed synthesis of trimethylene carbonate

[0057] Under anhydrous and oxygen-free conditions, 6 mmol (0.4 g) CuO@Ce-CMNDI, 20 mmol (1.5 g) 1,3-propanediol, 20 mmol (2.7 g) K₂CO₃, and 20 mmol (1.9 g) 2-cyanofuran were added sequentially to a 100 mL high-pressure stainless steel reactor. The reactor was sealed, and the air inside was replaced three times with CO₂. CO₂ was then introduced at a certain pressure at room temperature, and the temperature was raised to 130 °C for 4 h. During the heating process, the pressure was monitored to ensure that the pressure inside the reactor was 4 MPa when the reaction temperature was reached. After the reaction was complete, the reactor was allowed to cool to room temperature and excess gas was released. The reactor was opened only after all gas had been released, the catalyst was removed by filtration, and the solvent was removed by vacuum to obtain the target product in 83% yield.

[0058] Example 14: Synthesis of Trimethylene Carbonate Catalyzed by Fe2O3@Ce-CMNDI

[0059] Under anhydrous and oxygen-free conditions, 6 mmol (0.4 g) Fe₂O₃@Ce-CMNDI, 20 mmol (1.5 g) 1,3-propanediol, 20 mmol (2.7 g) K₂CO₃, and 20 mmol (1.9 g) 2-cyanofuran were added sequentially to a 100 mL high-pressure stainless steel reactor. The reactor was sealed, and the air inside was replaced three times with CO₂. CO₂ was then introduced at a certain pressure at room temperature, and the temperature was raised to 140 °C for 5 h. During the heating process, the pressure was monitored to ensure that the pressure inside the reactor was 4 MPa when the reaction temperature was reached. After the reaction was complete, the reactor was allowed to cool to room temperature and excess gas was released. The reactor was opened only after all gas had been released, the catalyst was removed by filtration, and the solvent was removed by vacuum to obtain the target product in 50% yield.

[0060] Example 15: Synthesis of trimethylene carbonate catalyzed by CeO2@Ce-CMNDI

[0061] Under anhydrous and oxygen-free conditions, 6 mmol (0.4 g) CeO2@Ce-CMNDI, 20 mmol (1.5 g) 1,3-propanediol, 20 mmol (2.7 g) K2CO3, and 20 mmol (1.9 g) 2-cyanofuran were added sequentially to a 100 mL high-pressure stainless steel reactor. The reactor was sealed, and the air inside was replaced three times with CO2. CO2 was then introduced at a certain pressure at room temperature, and the temperature was raised to 120 °C for 6 h. During the heating process, the pressure was monitored to ensure that the pressure inside the reactor was 4 MPa when the reaction temperature was reached. After the reaction was complete, the reactor was allowed to cool to room temperature and excess gas was released. The reactor was opened only after all gas had been released, the catalyst was removed by filtration, and the solvent was removed by vacuum to obtain the target product with a yield of 88%.

[0062] Example 16: Synthesis of Trimethylene Carbonate Catalyzed by SiO2@Ce-CMNDI

[0063] Under anhydrous and oxygen-free conditions, 6 mmol (0.3 g) SiO2@Ce-CMNDI, 20 mmol (1.5 g) 1,3-propanediol, 20 mmol (2.7 g) K2CO3, and 20 mmol (1.9 g) 2-cyanofuran were added sequentially to a 100 mL high-pressure stainless steel reactor. The reactor was sealed, and the air inside was replaced three times with CO2. CO2 was then introduced at a certain pressure at room temperature, and the temperature was raised to 180 °C for 6 h. During the heating process, the pressure was monitored to ensure that the pressure inside the reactor reached 5 MPa when the reaction temperature was reached. After the reaction was complete, the reactor was allowed to cool to room temperature and excess gas was released. The reactor was opened only after all gas had been released, the catalyst was removed by filtration, and the solvent was removed by vacuum to obtain the target product with a yield of 61%.

[0064] Example 17: Synthesis of Trimethylene Carbonate Catalyzed by Al2O3@Ce-CMNDI

[0065] Under anhydrous and oxygen-free conditions, 6 mmol (0.4 g) of Al₂O₃@Ce-CMNDI, 20 mmol (1.5 g) of 1,3-propanediol, 20 mmol (2.7 g) of K₂CO₃, and 20 mmol (1.9 g) of 2-cyanofuran were added sequentially to a 100 mL high-pressure stainless steel reactor. The reactor was sealed, and the air inside was replaced three times with CO₂. CO₂ was then introduced at a certain pressure at room temperature, and the temperature was raised to 120 °C for 3 hours. During the heating process, the pressure was monitored to ensure that the pressure inside the reactor was 4 MPa when the reaction temperature was reached. After the reaction was complete, the reactor was allowed to cool to room temperature and excess gas was released. The reactor was opened only after all gas had been released, the catalyst was removed by filtration, and the solvent was removed by vacuum to obtain the target product in 55% yield.

[0066] Example 18: Synthesis of Trimethylene Carbonate Catalyzed by TiO2@Ce-CMNDI

[0067] Under anhydrous and oxygen-free conditions, 6 mmol (0.3 g) TiO2@Ce-CMNDI, 20 mmol (1.5 g) 1,3-propanediol, 20 mmol (2.7 g) K2CO3, and 20 mmol (1.9 g) 2-cyanofuran were added sequentially to a 100 mL high-pressure stainless steel reactor. The reactor was sealed, and the air inside was replaced three times with CO2. CO2 was then introduced at a certain pressure at room temperature, and the temperature was raised to 150 °C for 4 h. During the heating process, the pressure was monitored to ensure that the pressure inside the reactor was 4 MPa when the reaction temperature was reached. After the reaction was complete, the reactor was allowed to cool to room temperature and excess gas was released. The reactor was opened only after all gas had been released, the catalyst was removed by filtration, and the solvent was removed by vacuum to obtain the target product with a yield of 69%.

[0068] Examples 19-24: Reusability of Ag2O@Ce-CMNDI

[0069] The heterogeneous catalyst separated in Example 12 can be reused after washing and drying with diethyl ether. The catalytic yields for the five catalytic reactions were 95%, 92%, 93%, 90%, and 91%, respectively.

[0070] Comparative Example 1: Catalyst-free synthesis of trimethylene carbonate

[0071] Under anhydrous and oxygen-free conditions, 20 mmol (1.5 g) of 1,3-propanediol, 20 mmol (2.7 g) of K₂CO₃, and 20 mmol (1.9 g) of 2-cyanofuran were added sequentially to a 100 mL high-pressure stainless steel reactor. The reactor was sealed, and the air inside was replaced three times with CO₂. CO₂ was then introduced at a certain pressure at room temperature, and the temperature was raised to 120 °C for 5 h. During the heating process, the pressure was monitored to ensure that the pressure inside the reactor was 4 MPa when the reaction temperature was reached. After the reaction was complete, the reactor was allowed to cool to room temperature and excess gas was released. The reactor was opened only after all gas had been released, the catalyst was removed by filtration, and the solvent was removed by vacuum to obtain the target product in 20% yield.

[0072] Comparative Example 2: Ce-CMNDI-catalyzed synthesis of trimethylene carbonate

[0073] Under anhydrous and oxygen-free conditions, 6 mmol (0.4 g) Ce-CMNDI, 20 mmol (1.5 g) 1,3-propanediol, 20 mmol (2.7 g) K₂CO₃, and 20 mmol (1.9 g) 2-cyanofuran were added sequentially to a 100 mL high-pressure stainless steel reactor. The reactor was sealed, and the air inside was replaced three times with CO₂. CO₂ was then introduced at a certain pressure at room temperature, and the temperature was raised to 120 °C for 5 h. During the heating process, the pressure was monitored to ensure that the pressure inside the reactor was 4 MPa when the reaction temperature was reached. After the reaction was complete, the reactor was allowed to cool to room temperature and excess gas was released. The reactor was opened only after all gas had been released, the catalyst was removed by filtration, and the solvent was removed by vacuum to obtain the target product in 39% yield.

[0074] Comparative Example 3: Ag₂O-catalyzed synthesis of trimethylene carbonate

[0075] Under anhydrous and oxygen-free conditions, 6 mmol (0.1 g) Ag₂O, 20 mmol (1.5 g) 1,3-propanediol, 20 mmol (2.7 g) K₂CO₃, and 20 mmol (1.9 g) 2-cyanofuran were added sequentially to a 100 mL high-pressure stainless steel reactor. The reactor was sealed, and the air inside was replaced three times with CO₂. CO₂ was then introduced at a certain pressure at room temperature, and the temperature was raised to 120 °C for 5 h. During the heating process, the pressure was monitored to ensure that the pressure inside the reactor was 4 MPa when the reaction temperature was reached. After the reaction was complete, the reactor was allowed to cool to room temperature and excess gas was released. The reactor was opened only after all gas had been released, the catalyst was removed by filtration, and the solvent was removed by vacuum to obtain the target product in 44% yield.

Claims

1. A method of synthesizing triethylene carbonate, characterized by The application relates to a preparation method of a MO@Ce-CMNDI catalyst, and a preparation method of a 2-cyano furan-1, 3-propanediol product.

2. The method of claim 1, wherein: The reaction conditions are as follows: the pressure in the reaction kettle is 2-5 MPa; the reaction temperature is 100-160 DEG C, preferably 120-140 DEG C; and the reaction time is 0.5-8 hours, preferably 3-5 hours.

3. The method of claim 1, wherein: The molar ratio of the MO@Ce-CMNDI catalyst, 2-cyano furan, 1, 3-propanediol and potassium carbonate is 1-3:10:10:

10.

4. The method of claim 1, wherein: The preparation method of the MO@Ce-CMNDI catalyst comprises the following steps: (1) 1, 4, 5, 8-naphthalene tetracarboxylic dianhydride and glycine are dissolved in an appropriate amount of organic solvent to perform a reflux reaction; the reaction mixture is filtered, washed and dried to obtain a solid product; (2) the solid powder in step 1 and Ce(NO3)3.6H2O are dissolved in a mixed solvent, an HNO3 solution is added and reacted for a period of time to obtain Ce-CMNDI; (3) the Ce-CMNDI prepared in step (2) and metal oxide are mechanically ground, transferred into a solvent, uniformly stirred, and subjected to a hydrothermal reaction; after the reaction is completed, the solid product is filtered and washed, and is calcined in a muffle furnace to obtain the catalyst MO@Ce-CMNDI.

5. The method of claim 4, wherein: The solvent in step (1) is one or more of ethanol, methanol, isopropanol, ethylene glycol, acetonitrile, acetic acid, propionic acid, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, benzene, toluene, chlorobenzene, dichloromethane, pyridine and tetrahydrofuran.

6. The method of claim 4, wherein: The molar ratio of 1, 4, 5, 8-naphthalene tetracarboxylic dianhydride and glycine in step (1) is 1:2-1:4, and the ratio of the amount of the organic solvent to the solute is 10 mL:2 mmol-10 mL:1 mmol.

7. The method of claim 4, wherein: The reflux reaction conditions in step (1) are as follows: the temperature is 80-120 DEG C, and the time is 8-12 hours.

8. The method of claim 4, wherein: The addition ratio of the solid powder, Ce(NO3)3.6H2O, the mixed solvent and the HNO3 solution in step (2) is 0.01 mmol:0.04-0.06 mmol:4-5 mL:100-300 muL.

9. The method of claim 4, wherein: The mixed solvent in step (2) is a combination of two or more of N, N-dimethylacetamide (DMA), N, N-dimethylformamide (DMF), ethanol, methanol, acetonitrile, ethylene glycol, isopropanol and water.

10. The method of claim 4, wherein: The reaction condition in step (2) is that the reaction is carried out at 80-110°C for 2-4 days.

11. The method of claim 4, wherein: The metal oxide in step (3) is MgO, ZnO, CuO, Fe2O3, CeO2, SiO2, Al2O3, TiO2, etc., and Ag2O is preferred. The solvent is one or more of ethanol, methanol, isopropanol, ethylene glycol, acetonitrile, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, benzene, toluene, chlorobenzene, dichloromethane, pyridine and tetrahydrofuran.

12. The method of claim 4, wherein: The ratio of Ce-CMNDI to metal oxide in step (3) is 1:1-1:

4.

13. The method of claim 4, wherein: The hydrothermal reaction condition in step (3) is that the temperature is 120-180°C and the time is 5-24 h.

14. The method of claim 4, wherein: The calcination temperature in step (3) is 300-500°C, and the calcination time is 5-10 hours.

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