Synthesis method of cyclic carbonate

Abstract

The present invention provides a cyclic carbonate synthesis method, and belongs to the technical field of organic ester compound synthesis, and the cyclic carbonate synthesis method comprises the following steps: S1, 1, 3-propylene glycol, a dehydrating agent and a catalyst are added into a high pressure reaction kettle, and CO2 is introduced into the high pressure reaction kettle for a reaction; s2, after the reaction is finished, after the high-pressure reaction kettle is cooled to the room temperature, redundant gas in the high-pressure reaction kettle is discharged, after the gas in the high-pressure reaction kettle is completely discharged, the high-pressure reaction kettle is opened, the catalyst is filtered out, and the solution is subjected to vacuum-pumping separation to obtain a target product; the catalyst is a heterogeneous catalyst M < 1 > < x > M < 2 > < y > O < z > (at) Bi-TDPAT. According to the invention, carbon dioxide conversion is carried out in a chemical utilization manner, a chemical product trimethylene carbonate can be produced, the synthesis route is easy to operate, and after the M1xM2yOz-Bi-TDPAT catalyst is added, the yield is high, the added value is high, and the green chemistry concept is met.

Description

Technical Field

[0001] The invention relates to the technical field of synthesis of organic ester compounds, in particular to a method for synthesizing cyclic carbonate. Background Art

[0002] Carbon capture, utilization and storage (CCUS) is one of the key technologies to address global climate change and has received great attention worldwide. Countries around the world have stepped up their research and development efforts to achieve large-scale industrial emission reductions. In recent years, scientists have reported many research results on the conversion of CO2 into various chemicals; however, so far, the scale of eliminating CO2 by chemical utilization is still very small. As a low-toxic, non-flammable, abundant and cheap carbon resource, the development of new CO2-synthesized organic chemical products has become increasingly necessary and urgent, and is also the development direction of CO2 chemical utilization to address greenhouse gas emission reduction.

[0003] Cyclic carbonates are an important class of compounds, which are widely used as starting materials for polycarbonate resins, electrolytes for lithium batteries, inert solvents, alkyl and carbonyl reagents, etc. Among cyclic carbonates, trimethylene carbonate is an important one. Trimethylene carbonate is the monomer of polytrimethylene carbonate, which is a class of non-toxic, biocompatible, biodegradable biomedical materials. At the same time, because it has certain elasticity and good mechanical processing properties at human body temperature, it has been widely used in biomedical fields such as degradable ligature devices, drug controlled release, and in vivo implant materials.

[0004] The synthesis of TMC (Trimethylcarbonate) mainly includes phosgene method, ester exchange method, propylene glycol-urea method and carbon dioxide-epoxide method. From the perspective of green chemistry, the synthesis route with simple operation, mild reaction conditions and high selectivity is better. The synthesis of trimethylene carbonate using CO2 as raw material is a synthesis route that is more in line with the concept of green chemistry. However, due to the low reaction activity of CO2, large-scale synthetic application cannot be achieved. For this reason, the present invention provides a method for synthesizing cyclic carbonate. Summary of the invention

[0005] In order to solve the problem that in the synthesis route of trimethylene carbonate using CO2 as a raw material, large-scale synthesis and application cannot be achieved due to the low reaction activity of CO2, the present invention provides a method for synthesizing cyclic carbonate.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for synthesizing a cyclic carbonate comprises the following steps:

[0008] S1, adding 1,3-propylene glycol, a dehydrating agent and a catalyst into a high-pressure reactor, and introducing CO2 into the high-pressure reactor for reaction;

[0009] S2. After the reaction is completed, wait for the autoclave to cool to room temperature and discharge the excess gas in the autoclave. After all the gas in the autoclave is discharged, open the autoclave, filter to remove the catalyst, and vacuum separate the solution to obtain the target product.

[0010] The catalyst is a heterogeneous catalyst M 1x M 2y O z @Bi-TDPAT, where M1 and M2 represent two metal elements, and x, y, and z are all stoichiometric numbers.

[0011] As a further description of the above technical solution:

[0012] M 1x M 2y O z @Bi-M1xM in TDPAT 2y O z It represents a composite oxide of any two metal oxides of CoO, ZrO2, NiO, Fe2O3, ZnO, MnO2, CdO, and Cr2O3;

[0013] M 1x M 2y O z @Bi-TDPAT in Bi-TDPAT stands for the metallic crystalline material H3O·[Bi(TDPAT) synthesized from Bi(NO3)3·5H2O and 2,4,6-tris(3,5-dicarboxyanilino)-1,3,5-triazine 2 / 3 ]·3H2O·4DMA.

[0014] As a further description of the above technical solution:

[0015] The dehydrating agent is one of 2-cyanopyridine, 3-cyanopyridine, 2-cyanofuran, 2-cyanothiophene, 2-cyanopyrimidine, isopropanol, n-butanol, tert-butanol, ethylene glycol, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

[0016] As a further description of the above technical solution:

[0017] In the step S1, the pressure in the autoclave is controlled to be 1-5 MPa and the temperature is controlled to be 40-100° C., and the reaction is carried out under stirring for 2-8 hours.

[0018] As a further description of the above technical solution:

[0019] The M1x M 2y O z The preparation of @Bi-TDPAT includes the following steps:

[0020] Step 1: Prepare M1xM 2y O z Composite oxides;

[0021] Step 2: Prepare the M1xM 2y O z The composite oxide and Bi-TDPAT were fully ground in a mortar for 30 min to obtain catalyst M1xM 2y O z @Bi-TDPAT.

[0022] As a further description of the above technical solution:

[0023] The M1xM 2y O z The composite oxide is CoZrO3 composite oxide, and the preparation method of CoZrO3 composite oxide includes:

[0024] Co(NO3)2·6H2O and ZrO(NO3)2 were dispersed in water at a molar ratio of 1:1, stirred at room temperature for 30 minutes, and NaOH solution was added thereto and stirred until no more precipitate was generated. Stirring was continued for 30 minutes, and the precipitate was separated by centrifugation and dried at 100°C. After drying, it was transferred to a tubular furnace and heated to 400°C at a heating rate of 5°C / min, then kept at a constant temperature for 8 hours, taken out and cooled to room temperature to obtain CoZrO3 composite oxide.

[0025] As a further description of the above technical solution:

[0026] The preparation method of Bi-TDPAT comprises:

[0027] Dissolve 7 mg Bi(NO3)3·5H2O and 2 mg H6TDPAT in a mixed solution of 2 mL DMA and 0.5 mL H2O, adjust the pH, stir for 30 min until the solution is clear, transfer the mixed solution to a heat-resistant glass bottle, heat at 90°C for 6-9 h, cool to room temperature, wash with DMA and dry to obtain colorless crystalline Bi-TDPAT.

[0028] Beneficial effects of the present invention:

[0029] 1. The present invention converts carbon dioxide in a chemical utilization manner to produce a chemical product, trimethylene carbonate. The synthetic route is easy to operate. 1x M 2y O z@Bi-TDPAT catalyst has high yield, high added value, and is in line with the concept of green chemistry.

[0030] 2. M provided by the present invention 1x M 2y O z @Bi-TDPAT catalyst is used in the synthesis reaction of cyclic carbonates. It has good catalytic reusability and can be reused more than 5 times. It has high catalytic activity and high reaction conversion rate.

[0031] 3. The present invention, catalyst M 1x M 2y O z The metal oxides in Bi-TDPAT have good dispersion, large specific surface area, and many catalytic sites. They are tightly connected to Bi-TDPAT through intermolecular interactions, and the electron transfer between the metal sites and the metal oxides improves its catalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate a method for synthesizing a cyclic carbonate, the following drawings are shown;

[0033] Figure 1 Schematic diagram of the crystal structure of Bi-TDPAT in the present invention. DETAILED DESCRIPTION

[0034] Example 1

[0035] The present invention also provides a method for synthesizing trimethylene carbonate:

[0036] The synthesis method of trimethylene carbonate mainly comprises the following steps: adding M 1x M 2y O z @Bi-TDPAT catalyst, 1,3-propylene glycol and dehydrating agent, then CO2 is introduced into the high-pressure stainless steel reactor, the pressure in the high-pressure stainless steel reactor is 1-5 MPa, the reaction temperature is 40-100°C, and the preferred reaction temperature is 60-80°C. The reaction time is 2-8h, preferably 4-5h.

[0037] After the reaction is completed, wait for the high-pressure reactor to cool to room temperature and discharge excess gas in the high-pressure reactor. After all the gas in the high-pressure reactor is discharged, open the high-pressure reactor, filter to remove the catalyst, and vacuum separate the solution to obtain the target product.

[0038] The reaction route is as follows:

[0039]

[0040] Example 2

[0041] The method for preparing Bi-TDPAT specifically comprises:

[0042] Dissolve 7 mg Bi(NO3)3·5H2O and ligand 2 mg H6TDPAT in a mixed solution of 2 mL DMA and 0.5 mL H2O, adjust the pH, stir for 30 min until the solution is clear, transfer the mixed solution to a heat-resistant glass bottle, heat at 90°C for 6-9 h, cool to room temperature, wash with DMA and dry to obtain colorless crystal Bi-TDPAT; the yield of colorless crystal Bi-TDPAT is 58%, and its crystal structure is as follows Figure 1 as shown in .

[0043] Example 3

[0044] The catalyst CoZrO3@Bi-TDPAT was prepared based on the colorless crystalline Bi-TDPAT in Example 2.

[0045] Specifically, 0.2mmol Co(NO3)2·6H2O and 0.2mmol ZrO(NO3)2 were dispersed in water, stirred at room temperature for 30min, 8mol / LNaOH solution was added and stirred until no more precipitation was generated, stirring was continued for 30min, the precipitate was separated by centrifugation, and dried at 100℃, and after drying, it was transferred to a tube furnace and heated to 400℃ at a heating rate of 5℃ / min, and kept at a constant temperature for 8h, and then taken out and cooled to room temperature to obtain the composite oxide CoZrO3. The composite oxide CoZrO3 and 0.4mmol Bi-TDPAT were fully ground in a mortar for 30min to obtain the catalyst CoZrO3@Bi-TDPAT.

[0046] Example 4

[0047] The catalyst NiZrO3@Bi-TDPAT was prepared based on the colorless crystalline Bi-TDPAT in Example 2.

[0048] Specifically, 0.2mmol Ni(NO3)2·6H2O and 0.2mmol ZrO(NO3)2 were dispersed in water, stirred at room temperature for 30min, 8mol / LNaOH solution was added and stirred until no precipitation was generated, stirring was continued for 30min, the precipitate was separated by centrifugation, and dried at 100℃, and then transferred to a tube furnace and heated to 500℃ at a heating rate of 5℃ / min, and kept at a constant temperature for 10h, and then taken out and cooled to room temperature to obtain the composite oxide NiZrO3. The obtained composite oxide CoZrO3 and 0.4mmol Bi-TDPAT were fully ground in a mortar for 30min to obtain the catalyst NiZrO3@Bi-TDPAT.

[0049] Example 5

[0050] The catalyst ZrFe2O5@Bi-TDPAT was prepared based on the colorless crystalline Bi-TDPAT in Example 2.

[0051] Specifically: 0.2mmol Fe(NO3)3·9H2O and 0.2mmol ZrO(NO3)2 were dispersed in water, stirred at room temperature for 30min, ammonia solution was added thereto and stirred until no more precipitate was generated, stirring was continued for 30min, the precipitate was separated by centrifugation and dried at 100°C, after drying, it was transferred to a tubular furnace and heated to 500°C at a heating rate of 5°C / min and kept at a constant temperature for 10h, then taken out and cooled to room temperature to obtain the composite oxide ZrFe2O5, the obtained composite oxide ZrFe2O5 and 0.4mmol Bi-TDPAT were fully ground in a mortar for 30min to obtain the catalyst ZrFe2O5@Bi-TDPAT.

[0052] Example 6

[0053] The catalyst ZnZrO3@Bi-TDPAT was prepared based on the colorless crystalline Bi-TDPAT in Example 2.

[0054] Specifically, 0.2mmol Zn(NO3)2·6H2O and 0.2mmol ZrO(NO3)2 were dispersed in water, stirred at room temperature for 60min, 8mol / LNaOH solution was added thereto and stirred until no more precipitation was generated, stirring was continued for 30min, the precipitate was separated by centrifugation, and dried at 120℃, after drying, it was transferred to a tube furnace and heated to 400℃ at a heating rate of 5℃ / min, and kept at a constant temperature for 12h, and then taken out and cooled to room temperature to obtain the composite oxide ZnZrO3. The composite oxide ZnZrO3 and 0.4mmol Bi-TDPAT were fully ground in a mortar for 60min to obtain the catalyst ZnZrO3@Bi-TDPAT.

[0055] Example 7

[0056] The catalyst MnZrO4@Bi-TDPAT was prepared based on the colorless crystalline Bi-TDPAT in Example 2.

[0057] Specifically, 0.2mmol Mn(NO3)2·4H2O and 0.2mmol ZrO(NO3)2 were dispersed in water, stirred at room temperature for 90min, 8mol / L KOH solution was added and stirred until no more precipitation was generated, stirring was continued for 30min, the precipitate was separated by centrifugation, and dried at 120℃, and then transferred to a tube furnace and heated to 450℃ at a heating rate of 5℃ / min, and kept at a constant temperature for 8h, and then taken out and cooled to room temperature to obtain the composite oxide MnZrO4. The obtained composite oxide MnZrO4 and 0.4mmol Bi-TDPAT were fully ground in a mortar for 60min to obtain the catalyst MnZrO4@Bi-TDPAT.

[0058] Example 8

[0059] The catalyst CdZrO3@Bi-TDPAT was prepared based on the colorless crystalline Bi-TDPAT in Example 2.

[0060] Specifically, 0.2mmol Cd(NO3)2·4H2O and 0.2mmol ZrO(NO3)2 were dispersed in water, stirred at room temperature for 90min, Ca(OH)2 solution was added and stirred until no more precipitation was generated, stirring was continued for 30min, the precipitate was separated by centrifugation, and dried at 110℃, and after drying, it was transferred to a tube furnace and heated to 450℃ at a heating rate of 5℃ / min, and kept at a constant temperature for 10h, and then taken out and cooled to room temperature to obtain the composite oxide CdZrO3. The obtained composite oxide CdZrO3 and 0.4mmol Bi-TDPAT were fully ground in a mortar for 30min to obtain the catalyst CdZrO3@Bi-TDPAT.

[0061] Example 9

[0062] The catalyst ZrCr2O5@Bi-TDPAT was prepared based on the colorless crystalline Bi-TDPAT in Example 2.

[0063] Specifically, 0.2mmol Cr(NO3)3·9H2O and 0.2mmol ZrO(NO3)2 were dispersed in water, stirred at room temperature for 90min, 8mol / LKOH solution was added thereto and stirred until no more precipitation was generated, stirring was continued for 30min, the precipitate was separated by centrifugation, and dried at 120℃, after drying, it was transferred to a tube furnace and heated to 450℃ at a heating rate of 5℃ / min, and kept at a constant temperature for 8h, and then taken out and cooled to room temperature to obtain the composite oxide ZrCr2O5. The composite oxide ZrCr2O5 and 0.4mmol Bi-TDPAT were fully ground in a mortar for 60min to obtain the catalyst ZrCr2O5@Bi-TDPAT.

[0064] Examples 10-24

[0065] A synthesis method of trimethylene carbonate comprises the following steps: adding 0.04 mmol of a catalyst, 10 mmol (0.76 g) of 1,3-propylene glycol and 30 mL of a dehydrating agent to a 100 mL high-pressure stainless steel reactor in sequence, then sealing the reactor, replacing the air in the reactor with CO2 for three times, charging the reactor with a certain pressure of CO2 at room temperature, and reacting at a certain temperature for a certain time; after the reaction is completed, waiting for the reactor to cool to room temperature and exhausting the excess gas in the reactor, opening the reactor only after all the gas in the reactor is exhausted, filtering to remove the catalyst, and vacuumizing the solution to remove the dehydrating agent to obtain the target product.

[0066] According to a synthesis method of trimethylene carbonate, ZrFe2O5@Bi-TDPAT is used as a catalyst, and the dehydrating agent, reaction temperature, reaction time, and reaction pressure are adjusted to obtain the trimethylene carbonate yield Table 1 as follows:

[0067]

[0068]

[0069] Table 1

[0070] Among them, the NMR data of trimethylene carbonate are as follows: 1 H NMR (400MHz, CDCl3) δ (ppm): 4.24 (t, J = 6.0Hz, 4H), 2.08-2.02 (m, 2H).

[0071] It can be seen from Table 1 that when ZrFe2O5@Bi-TDPAT is used as a catalyst, 2-cyanopyridine is used as a dehydrating agent, the reaction temperature is 60°C, the reaction time is 4h, and the reaction pressure is 5MPa, the yield is the highest. Under the above conditions, the reaction pressure of 1-5MPa has little effect on the yield, and the reaction pressure can be selected to be 1MPa. The reaction temperature has the greatest impact and should be controlled at about 60°C.

[0072] Embodiment 25

[0073] Synthesis of trimethylene carbonate catalyzed by CoZrO3@Bi-TDPAT

[0074] 0.04g CoZrO3@Bi-TDPAT, 10mmol (0.76g) 1,3-propylene glycol and 30mL 2-cyanopyridine were added to a 100mL high-pressure stainless steel reactor. After the reactor was sealed, the air in the reactor was replaced with CO2 three times, and a certain pressure of CO2 was filled at room temperature. The temperature was raised to 60℃ for 4h. The pressure was monitored during the heating process to ensure that the pressure in the reactor was 1MPa during the reaction. After the reaction was completed, the reactor was cooled to room temperature and the excess gas in the reactor was discharged. The reactor could be opened after all the gas in the reactor was discharged, the catalyst was filtered out, and the solution was vacuumed to remove the dehydrating agent to obtain the target product with a yield of 77%.

[0075] Embodiment 26

[0076] Synthesis of trimethylene carbonate catalyzed by NiZrO3@Bi-TDPAT

[0077] 0.04g NiZrO3@Bi-TDPAT, 10mmol (0.76g) 1,3-propylene glycol and 30mL 2-cyanopyridine were added to a 100mL high-pressure stainless steel reactor. After the reactor was sealed, the air in the reactor was replaced with CO2 three times, and a certain pressure of CO2 was filled at room temperature. The temperature was raised to 60℃ for 4h. The pressure was monitored during the heating process to ensure that the pressure in the reactor was 1MPa during the reaction. After the reaction was completed, the reactor was cooled to room temperature and the excess gas in the reactor was discharged. The reactor was opened after all the gas in the reactor was discharged, the catalyst was filtered out, and the solution was vacuumed to remove the dehydrating agent to obtain the target product with a yield of 74%.

[0078] Embodiment 27

[0079] Synthesis of trimethylene carbonate catalyzed by ZrCr2O5@Bi-TDPAT

[0080] 0.04g ZrCr2O5@Bi-TDPAT, 10mmol (0.76g) 1,3-propylene glycol and 30mL 2-cyanopyridine were added to a 100mL high-pressure stainless steel reactor. After the reactor was sealed, the air in the reactor was replaced with CO2 three times, and a certain pressure of CO2 was filled at room temperature. The temperature was raised to 60℃ for 4h. The pressure was monitored during the heating process to ensure that the pressure in the reactor was 1MPa during the reaction. After the reaction was completed, the reactor was cooled to room temperature and the excess gas in the reactor was discharged. The reactor could be opened after all the gas in the reactor was discharged, the catalyst was filtered out, and the solution was vacuumed to remove the dehydrating agent to obtain the target product with a yield of 82%.

[0081] Embodiment 28

[0082] Synthesis of trimethylene carbonate catalyzed by ZnZrO3@Bi-TDPAT

[0083] 0.04g ZnZrO3@Bi-TDPAT, 10mmol (0.76g) 1,3-propylene glycol and 30mL 2-cyanopyridine were added to a 100mL high-pressure stainless steel reactor. After the reactor was sealed, the air in the reactor was replaced with CO2 three times, and a certain pressure of CO2 was filled at room temperature. The temperature was raised to 60℃ for 4h. The pressure was monitored during the heating process to ensure that the pressure in the reactor was 1MPa during the reaction. After the reaction was completed, the reactor was cooled to room temperature and the excess gas in the reactor was discharged. The reactor could be opened after all the gas in the reactor was discharged, the catalyst was filtered out, and the solution was vacuumed to remove the dehydrating agent to obtain the target product with a yield of 83%.

[0084] Embodiment 29

[0085] Synthesis of trimethylene carbonate catalyzed by MnZrO4@Bi-TDPAT

[0086] 0.04g MnZrO4@Bi-TDPAT, 10mmol (0.76g) 1,3-propylene glycol and 30mL 2-cyanopyridine were added to a 100mL high-pressure stainless steel reactor. After the reactor was sealed, the air in the reactor was replaced with CO2 three times, and a certain pressure of CO2 was filled at room temperature. The temperature was raised to 60℃ for 4h. The pressure was monitored during the heating process to ensure that the pressure in the reactor was 1MPa during the reaction. After the reaction was completed, the reactor was cooled to room temperature and the excess gas in the reactor was discharged. The reactor could be opened after all the gas in the reactor was discharged, the catalyst was filtered out, and the solution was vacuumed to remove the dehydrating agent to obtain the target product with a yield of 86%.

[0087] Embodiment 30

[0088] Synthesis of trimethylene carbonate catalyzed by CdZrO3@Bi-TDPAT

[0089] 0.04g CdZrO3@Bi-TDPAT, 10mmol (0.76g) 1,3-propylene glycol and 30mL 2-cyanopyridine were added to a 100mL high-pressure stainless steel reactor. After the reactor was sealed, the air in the reactor was replaced with CO2 three times, and a certain pressure of CO2 was filled at room temperature. The temperature was raised to 60℃ for 4h. The pressure was monitored during the heating process to ensure that the pressure in the reactor was 1MPa during the reaction. After the reaction was completed, the reactor was cooled to room temperature and the excess gas in the reactor was discharged. The reactor could be opened only after all the gas in the reactor was discharged, the catalyst was filtered out, and the solution was vacuumed to remove the dehydrating agent to obtain the target product with a yield of 85%.

[0090] Examples 31 to 35

[0091] Verification of the reusability of ZrFe2O5@Bi-TDPAT catalyst

[0092] The multiphase catalyst separated in Example 16 can be reused after washing with ether and drying. The catalytic yields of the five times are 90%, 89%, 89%, 90% and 88% respectively.

[0093] Comparative Example 1

[0094] Synthesis of trimethylene carbonate without catalyst

[0095] Add 10 mmol (0.76 g) of 1,3-propylene glycol and 30 mL of 2-cyanopyridine to a 100 mL high-pressure stainless steel reactor. After sealing the reactor, replace the air in the reactor with CO2 three times, fill it with a certain pressure of CO2 at room temperature, heat it to 40 ° C for 4 hours, monitor the pressure during the heating process, and ensure that the pressure in the reactor is 1 MPa during the reaction. After the reaction is completed, wait for the reactor to cool to room temperature and exhaust the excess gas in the reactor. The reactor can be opened only after all the gas in the reactor is exhausted, and the catalyst is filtered out. The solution is vacuumed to remove the dehydrating agent to obtain the target product with a yield of 15%.

[0096] Comparative Example 2

[0097] Synthesis of trimethylene carbonate using Bi-TDPAT catalyst

[0098] 0.04 (3.12 g) Bi-TDPAT, 10 mmol (0.76 g) 1,3-propylene glycol and 30 mL 2-cyanopyridine were added to a 100 mL high-pressure stainless steel reactor. After the reactor was sealed, the air in the reactor was replaced with CO2 three times, and a certain pressure of CO2 was filled at room temperature. The temperature was raised to 60 ° C for 4 hours. The pressure was monitored during the heating process to ensure that the pressure in the reactor was 1 MPa during the reaction. After the reaction was completed, the reactor was cooled to room temperature and the excess gas in the reactor was discharged. The reactor was opened after all the gas in the reactor was discharged, the catalyst was filtered out, and the solution was vacuumed to remove the dehydrating agent to obtain the target product with a yield of 53%.

[0099] The composite material M of the present invention is used 1x M 2y O z @Bi-TDPAT is a catalyst for preparing high value-added polymerization monomer trimethylene carbonate. The catalyst has high catalytic activity, is easy to recover and reuse, has a high product yield, and the reaction process is simple and easy to operate.

[0100] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the disclosure of the invention herein. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

[0101] It should be understood that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for synthesizing a cyclic carbonate, characterized in that: The following steps are involved: S1, adding 1,3-propylene glycol, a dehydrating agent and a catalyst into a high-pressure reactor, and introducing CO2 into the high-pressure reactor for reaction; S2. After the reaction is completed, wait for the autoclave to cool to room temperature and discharge the excess gas in the autoclave. After all the gas in the autoclave is discharged, open the autoclave, filter to remove the catalyst, and vacuum separate the solution to obtain the target product. The catalyst is a heterogeneous catalyst M 1x M 2y O z @Bi-TDPAT, where M1 and M2 represent two metal elements, and x, y, and z are all stoichiometric numbers.

2. The method for synthesizing a cyclic carbonate according to claim 1, characterized in that: M 1x M 2y O z @Bi-M1xM in TDPAT 2y O z It represents a composite oxide of any two metal oxides of CoO, ZrO2, NiO, Fe2O3, ZnO, MnO2, CdO, and Cr2O3; M 1x M 2y O z @Bi-TDPAT in Bi-TDPAT stands for the metallic crystalline material H3O·[Bi(TDPAT) synthesized from Bi(NO3)3·5H2O and 2,4,6-tris(3,5-dicarboxyanilino)-1,3,5-triazine 2 / 3 ]·3H2O·4DMA.

3. The method for synthesizing a cyclic carbonate according to claim 1, characterized in that: The dehydrating agent is one of 2-cyanopyridine, 3-cyanopyridine, 2-cyanofuran, 2-cyanothiophene, 2-cyanopyrimidine, isopropanol, n-butanol, tert-butanol, ethylene glycol, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

4. The method for synthesizing a cyclic carbonate according to claim 1, characterized in that: In the step S1, the pressure in the autoclave is controlled to be 1-5 MPa and the temperature is controlled to be 40-100° C., and the reaction is carried out under stirring for 2-8 hours.

5. The method for synthesizing a cyclic carbonate according to claim 2, characterized in that: M 1x M 2y O z The preparation of @Bi-TDPAT includes the following steps: Step 1: Prepare M1xM 2y O z Composite oxides; Step 2: Prepare the M1xM 2y O z The composite oxide and Bi-TDPAT were fully ground in a mortar for 30 min to obtain catalyst M1xM 2y O z @Bi-TDPAT.

6. The method for synthesizing a cyclic carbonate according to claim 5, characterized in that: The M1xM 2y O z The composite oxide is CoZrO3 composite oxide, and the preparation method of CoZrO3 composite oxide includes: Co(NO3)2·6H2O and ZrO(NO3)2 were dispersed in water at a molar ratio of 1:1, stirred at room temperature for 30 minutes, and NaOH solution was added thereto and stirred until no more precipitate was generated. Stirring was continued for 30 minutes, and the precipitate was separated by centrifugation and dried at 100°C. After drying, it was transferred to a tubular furnace and heated to 400°C at a heating rate of 5°C / min, then kept at a constant temperature for 8 hours, taken out and cooled to room temperature to obtain CoZrO3 composite oxide.

7. The method for synthesizing a cyclic carbonate according to claim 5, characterized in that: The preparation method of the Bi-TDPAT comprises: Dissolve 7 mg Bi(NO3)3·5H2O and 2 mg H6TDPAT in a mixed solution of 2 mL DMA and 0.5 mL H2O, adjust the pH, stir for 30 min until the solution is clear, transfer the mixed solution to a heat-resistant glass bottle, heat at 90°C for 6-9 h, cool to room temperature, wash with DMA and dry to obtain colorless crystalline Bi-TDPAT.

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