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 < x > O < y >-Mn-MOF. Carbon dioxide conversion is carried out in a chemical utilization mode, a chemical product trimethylene carbonate can be produced, the synthesis route is easy to operate, and after the MxOy-Mn-MOF catalyst is added, the yield is high, the high additional value is achieved, 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] The development and consumption of fossil fuels leads to large amounts of carbon dioxide (CO 2 ) is released into the air, CO in the atmosphere 2 The sharp increase in CO content has led to the greenhouse effect and global climate change, which in turn threatens human survival and development. As various countries have implemented carbon reduction plans, CO 2 The application and research of CO have ushered in huge opportunities and challenges. 2 It is a renewable carbon resource with very abundant reserves, and can be used as a very important chemical raw material or liquid fuel for the production of esters, alcohols, ethers, acids, etc.

[0003] Cyclic carbonates are cyclic compounds containing O=C=O structure in their molecular structure. They have the advantages of high boiling point, low toxicity, stable structure and biodegradability, and are widely used. Trimethylene carbonate (TMC) is an important cyclic carbonate and a monomer of polytrimethylene carbonate. Polytrimethylene carbonate is a non-toxic, biocompatible and biodegradable biomedical material. 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] In traditional processes, the main methods for synthesizing cyclic carbonates include phosgene method, transesterification method and alcoholysis method. Phosgene method was first used in industrial production, but toxic and hazardous substances such as pyridine and phosgene were used in the reaction process, which has long been eliminated by the times. The transesterification reaction is a reversible reaction, which leads to a decrease in the conversion rate of the target product, thereby limiting its industrial application. The alcoholysis method uses a catalyst containing metal ions, and there are also problems of complex separation and difficult recovery. For this reason, the present invention provides a method for synthesizing cyclic carbonates. Summary of the invention

[0005] In order to solve the problem of 2 In the synthesis route of trimethylene carbonate using CO as raw material, 2 The reaction activity is low and large-scale synthesis application cannot be achieved. 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, 1,3-propylene glycol, a dehydrating agent and a catalyst are added to a high-pressure reactor, and CO is introduced into the high-pressure reactor. 2 to react;

[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 x O y -Mn-MOF.

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

[0012] The M x O y -M in Mn-MOF x O y MgO, CuO, NiO, CoO, Nb 2 O 5 、V 2 O 5 、CeO 2 、SiO 2 , one of PdO;

[0013] The M x O y -Mn-MOF in Mn-MOF means MnCl 2 ·4H 2 Metal-organic framework [Mn(HTTPCA)]H synthesized from O and 1,1',1"-(1,3,5-triazine-2,4,6-triyl)tripiperidine-4-carboxylic acid 2 O.

[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 60-120° C., and the reaction is carried out for 2-8 hours under stirring conditions.

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

[0019] M x O y The preparation of Mn-MOF includes the following steps:

[0020] Mn-MOF and metal acetate are dispersed in a low boiling point solvent and stirred at room temperature for 30 to 90 minutes. Oxalic acid is added thereto until no more precipitation occurs. The obtained precipitate is centrifuged and dried at 60 to 80°C. The precipitate is transferred to a tube furnace and heated to 300 to 400°C at a heating rate of 5°C / min and kept at this temperature for 4 to 12 hours. The catalyst M is then taken out and cooled to room temperature to obtain the catalyst M. x O y -Mn-MOF.

[0021] As a further description of the above technical solution:

[0022] The metal acetate is MgAc 2 ,CuAc 2 、NiAc 2 、CoAc 2 ,NbAc 5 、VO(Ac) 2 、CeAc 3 、SiAc 4 、PdAc 2 Any of .

[0023] As a further description of the above technical solution:

[0024] The low boiling point solvent is any one of ethanol, methanol, isopropanol, ethylene glycol, acetonitrile, benzene, toluene, chlorobenzene, dichloromethane, pyridine and tetrahydrofuran.

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

[0026] The preparation method of Mn-MOF comprises the following steps:

[0027] The ligand H 3 TTPCA and MnCl 2 ·4H 2 O was dissolved in a mixed solvent, the pH was adjusted to 5-7, ultrasonic mixing was performed for 30 min, heating was performed at 100-120 °C for 12-48 h, the mixture was allowed to stand at room temperature for 10-12 h, the solid product was filtered and washed with anhydrous ethanol, and dried at 60-80 °C to obtain Mn-MOF.

[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 synthesis route is easy to operate, and the yield is high after adding the MxOy-Mn-MOF catalyst. It has high added value and is in line with the concept of green chemistry.

[0030] 2. The MxOy-Mn-MOF catalyst provided by the present invention has good catalytic reusability when used for cyclic carbonate synthesis reaction, can be reused more than 5 times, has high catalytic activity and high reaction conversion rate.

[0031] 3. In the present invention, the metal oxide in the catalyst MxOy-Mn-MOF has high catalytic activity and good dispersibility; Mn-MOF has many active groups, rich redox sites, and a large contact area with the raw materials, which promotes the reaction of 1,3-propylene glycol with CO 2 contact and action, showing good 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 Mn-MOF in the present invention. DETAILED DESCRIPTION

[0034] Example 1

[0035] The present application provides an embodiment of the present invention also provides a method for synthesizing trimethylene cyclic carbonate:

[0036] The synthesis method of trimethylene cyclic carbonate mainly comprises the following steps: adding M x O y -Mn-MOF catalyst, 1,3-propylene glycol and a dehydrating agent, wherein 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, preferably 2-cyanopyridine, and CO is introduced into the reaction mixture. 2 The pressure in the reactor is 1-5 MPa, preferably 1-2 MPa. The reaction temperature is 60-120°C, preferably 80-100°C. The reaction time is 2-8 hours, preferably 4-6 hours.

[0037] The reaction route is as follows:

[0038]

[0039] Example 2

[0040] This embodiment provides a method for preparing Mn-MOF, which specifically includes:

[0041] 0.075 mmol (0.015 g) MnCl 2 ·4H 2 O and 0.04 mmol (0.02 g) H 3 TTPCA was dissolved in 2 mL DMA and 1 mL water, and appropriate amount of nitric acid / sodium bicarbonate was added dropwise to adjust the pH to 5-7. Ultrasonic mixing was performed for 30 min, and the mixture was transferred to a small Pyrex heat-resistant glass bottle and heated to 100 °C for 48 h. The mixture was allowed to stand at room temperature for 12 h, filtered, and the solid product was washed with anhydrous ethanol and dried at 80 °C to obtain Mn-MOF with a yield of 69%. Its crystal structure is shown in Figure 1 as shown in .

[0042] Example 3

[0043] The catalyst MgO-Mn-MOF was prepared based on the crystalline Mn-MOF in Example 2.

[0044] Specifically, 0.2 mmol (0.1 g) of prepared Mn-MOF and 0.2 mmol (0.03 g) of MgAc 2 Disperse in 20 mL of methanol and stir at room temperature for 30 min. Add oxalic acid until no more precipitate is precipitated. Centrifuge the precipitate, dry at 60 °C, transfer to a tubular furnace and heat to 300 °C at a heating rate of 5 °C / min and keep the temperature constant for 8 h. Take out and cool to room temperature to obtain the catalyst MgO-Mn-MOF.

[0045] Example 4

[0046] The catalyst CuO-Mn-MOF was prepared based on the crystalline Mn-MOF in Example 2.

[0047] Specifically, 0.2 mmol (0.1 g) of prepared Mn-MOF and 0.2 mmol (0.04 g) of CuAc were taken. 2 Disperse in 20 mL of ethanol and stir at room temperature for 60 min. Add oxalic acid until no more precipitate is precipitated. Centrifuge the precipitate, dry at 60 °C, transfer to a tubular furnace and heat to 300 °C at a heating rate of 5 °C / min and keep the temperature constant for 4 h. Take out and cool to room temperature to obtain the catalyst CuO-Mn-MOF.

[0048] Example 5

[0049] The catalyst NiO-Mn-MOF was prepared based on the crystalline Mn-MOF in Example 2.

[0050] Specifically, 0.2 mmol (0.1 g) of prepared Mn-MOF and 0.2 mmol (0.04 g) of NiAc were taken. 2 Disperse in 20 mL of acetonitrile and stir at room temperature for 60 min. Add oxalic acid until no more precipitate is precipitated. Centrifuge the precipitate, dry at 60 °C, transfer to a tubular furnace and heat to 350 °C at a heating rate of 5 °C / min and keep the temperature constant for 8 h. Take out and cool to room temperature to obtain the catalyst NiO-Mn-MOF.

[0051] Example 6

[0052] The catalyst CoO-Mn-MOF was prepared based on the crystalline Mn-MOF in Example 2.

[0053] Specifically, 0.2 mmol (0.1 g) of prepared Mn-MOF and 0.2 mmol (0.04 g) of CoAc were taken. 2 Disperse in 20 mL of acetonitrile and stir at room temperature for 60 min. Add oxalic acid until no more precipitate is precipitated. Centrifuge the precipitate, dry at 60 °C, transfer to a tubular furnace and heat to 350 °C at a heating rate of 5 °C / min and keep the temperature constant for 8 h. Take out and cool to room temperature to obtain the catalyst CoO-Mn-MOF.

[0054] Example 7

[0055] Preparation of catalyst Nb based on the crystalline Mn-MOF in Example 2 2 O 5 -Mn-MOF.

[0056] Specifically, 0.2 mmol (0.1 g) of prepared Mn-MOF and 0.2 mmol (0.08 g) of NbAc were taken. 5 Disperse in 20 mL of isopropanol, stir at room temperature for 90 min, add oxalic acid until no more precipitate is precipitated, centrifuge and dry at 70 °C, transfer to a tube furnace and heat to 400 °C at a heating rate of 5 °C / min, keep the temperature constant for 10 h, take out and cool to room temperature to obtain catalyst Nb 2 O 5 -Mn-MOF.

[0057] Example 8

[0058] Preparation of Catalyst V Based on Crystalline Mn-MOF in Example 2 2 O 5 -Mn-MOF.

[0059] Specifically: Take 0.2mmol (0.1g) of prepared Mn-MOF and 0.2mmol (0.04g) VO(Ac) 2Disperse in 20 mL of tetrahydrofuran, stir at room temperature for 60 min, add oxalic acid until no more precipitate is precipitated, centrifuge the precipitate, dry at 80 °C, transfer to a tube furnace and heat to 400 °C at a heating rate of 5 °C / min, keep the temperature constant for 12 h, take out and cool to room temperature to obtain catalyst V 2 O 5 -Mn-MOF.

[0060] Example 9

[0061] Preparation of CeO catalyst based on crystalline Mn-MOF in Example 2 2 -Mn-MOF.

[0062] Specifically: Take 0.2mmol (0.1g) of prepared Mn-MOF and 0.2mmol (0.06g) of Ce(Ac) 3 Disperse in 20 mL of ethanol, stir at room temperature for 60 min, add oxalic acid until no more precipitate is precipitated, centrifuge and dry at 80 °C, transfer to a tube furnace and heat to 300 °C at a heating rate of 5 °C / min, keep the temperature constant for 12 h, take out and cool to room temperature to obtain the catalyst CeO 2 -Mn-MOF.

[0063] Example 10

[0064] Preparation of catalyst SiO based on the crystalline Mn-MOF in Example 2 2 -Mn-MOF.

[0065] Specifically: Take 0.2mmol (0.1g) of prepared Mn-MOF and 0.2mmol (0.05g) of Si(Ac) 4 Disperse in 20 mL of ethylene glycol, stir at room temperature for 90 min, add oxalic acid until no more precipitate is precipitated, centrifuge the precipitate, dry at 80 °C, transfer to a tube furnace and heat to 350 °C at a heating rate of 5 °C / min, keep the temperature constant for 8 h, take out and cool to room temperature to obtain the catalyst SiO 2 -Mn-MOF.

[0066] Embodiment 11

[0067] The catalyst PdO-Mn-MOF was prepared based on the crystalline Mn-MOF in Example 2.

[0068] Specifically: Take 0.2mmol (0.1g) of prepared Mn-MOF and 0.2mmol (0.04g) of Pd (Ac) 2Disperse in 20 mL of acetonitrile and stir at room temperature for 30 min. Add oxalic acid until no more precipitate is precipitated. Centrifuge the precipitate, dry at 80 °C, transfer to a tubular furnace and heat to 400 °C at a heating rate of 5 °C / min and keep the temperature constant for 12 h. Take out and cool to room temperature to obtain the catalyst PdO-Mn-MOF.

[0069] Example 12

[0070] A method for synthesizing trimethylene cyclic carbonate: 0.04 g CeO 2 -Mn-MOF, 10 mmol (0.76 g) 1,3-propylene glycol and 30 mL dehydrating agent. The reactor was sealed and then heated with CO 2 Replace the air in the reactor three times and fill it with a certain pressure of CO at room temperature. 2 , react at a certain temperature for a certain time. 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 can be filtered out and the solution can be vacuum separated to obtain the target product.

[0071] According to the above method, the dehydrating agent, reaction temperature, reaction time and reaction pressure were adjusted to obtain the trimethylene carbonate yield Table 1 as follows:

[0072]

[0073]

[0074] Table 1

[0075] The NMR data of trimethylene carbonate are as follows: 1HNMR (400 MHz, CDCl3) δ (ppm): 4.24 (t, J = 6.0 Hz, 4H), 2.08-2.02 (m, 2H).

[0076] As shown in Table 1, CeO 2 -Mn-MOF is used as the catalyst, 2-cyanopyridine is used as the dehydrating agent, the reaction temperature is 80°C, the reaction time is 5h, and the reaction pressure is 5MPa. The yield is the highest. Under the above conditions, the reaction pressure at 1-5MPa has little effect on the yield. The reaction pressure can be selected as 1MPa, and the reaction time can be appropriately extended.

[0077] Embodiment 27

[0078] Synthesis of trimethylene carbonate using MgO-Mn-MOF as catalyst

[0079] 0.04 g MgO-Mn-MOF, 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. 2 Replace the air in the reactor three times and fill it with a certain pressure of CO at room temperature. 2 , heat to 80℃ and react for 4h. Monitor the pressure during the heating process to ensure that the pressure in the reactor is 1MPa. 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 vacuum-separated to obtain the target product with a yield of 80%.

[0080] Embodiment 28

[0081] Synthesis of trimethylene carbonate using CuO-Mn-MOF as catalyst

[0082] 0.04 g CuO-Mn-MOF, 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. 2 Replace the air in the reactor three times and fill it with a certain pressure of CO at room temperature. 2 , heat to 80℃ and react for 4h. Monitor the pressure during the heating process to ensure that the pressure in the reactor is 1MPa. 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. The catalyst is filtered out and the solution is vacuum-separated to obtain the target product with a yield of 75%.

[0083] Embodiment 29

[0084] Synthesis of trimethylene carbonate using NiO-Mn-MOF as catalyst

[0085] 0.04 g NiO-Mn-MOF, 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. 2 Replace the air in the reactor three times and fill it with a certain pressure of CO at room temperature. 2 , heat to 80℃ and react for 4h. Monitor the pressure during the heating process to ensure that the pressure in the reactor is 1MPa. 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. The catalyst is filtered out and the solution is vacuum-separated to obtain the target product with a yield of 70%.

[0086] Embodiment 30

[0087] Synthesis of trimethylene carbonate using CoO-Mn-MOF as catalyst

[0088] 0.04 g CoO-Mn-MOF, 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. 2 Replace the air in the reactor three times and fill it with a certain pressure of CO at room temperature. 2 , heat to 80℃ and react for 4h. Monitor the pressure during the heating process to ensure that the pressure in the reactor is 1MPa. 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 vacuum-separated to obtain the target product with a yield of 80%.

[0089] Embodiment 31

[0090] Nb 2 O 5 -Mn-MOF catalytic synthesis of trimethylene carbonate

[0091] 0.04 g Nb 2 O 5 -Mn-MOF, 10 mmol (0.76 g) 1,3-propylene glycol and 30 mL 2-cyanopyridine. The reactor was sealed and heated with CO 2 Replace the air in the reactor three times and fill it with a certain pressure of CO at room temperature. 2 , heat to 80℃ and react for 4h. Monitor the pressure during the heating process to ensure that the pressure in the reactor is 1MPa. 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. The catalyst is filtered out and the solution is vacuum-separated to obtain the target product with a yield of 73%.

[0092] Embodiment 32

[0093] V 2 O 5 -Mn-MOF catalytic synthesis of trimethylene carbonate

[0094] 0.04 g V 2 O 5 -Mn-MOF, 10 mmol (0.76 g) 1,3-propylene glycol and 30 mL 2-cyanopyridine. The reactor was sealed and heated with CO 2 Replace the air in the reactor three times and fill it with a certain pressure of CO at room temperature. 2, heat to 80℃ and react for 4h, monitor the pressure during the heating process to ensure that the pressure in the reactor is 1MPa. 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, filter to remove the catalyst, and vacuum separate the solution to obtain the target product with a yield of 55%.

[0095] Embodiment 33

[0096] SiO 2 -Mn-MOF catalytic synthesis of trimethylene carbonate

[0097] 0.04 g SiO 2 -Mn-MOF, 10 mmol (0.76 g) 1,3-propylene glycol and 30 mL 2-cyanopyridine. The reactor was sealed and heated with CO 2 Replace the air in the reactor three times and fill it with a certain pressure of CO at room temperature. 2 , heat to 80℃ and react for 4h. Monitor the pressure during the heating process to ensure that the pressure in the reactor is 1MPa. 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. The catalyst is filtered out and the solution is vacuum-separated to obtain the target product with a yield of 76%.

[0098] Embodiment 34

[0099] Synthesis of trimethylene carbonate using PdO-Mn-MOF as catalyst

[0100] 0.04 g PdO-Mn-MOF, 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. 2 Replace the air in the reactor three times and fill it with a certain pressure of CO at room temperature. 2 , heat to 80℃ and react for 4h. Monitor the pressure during the heating process to ensure that the pressure in the reactor is 1MPa. 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. The catalyst is filtered out and the solution is vacuum-separated to obtain the target product with a yield of 75%.

[0101] Embodiments 35 to 39

[0102] Inspection of CeO 2 -Mn-MOF, catalyst reusability

[0103] The multiphase catalyst separated in Example 17 can be reused after washing with ether and drying. The catalytic yields of the five times are 86%, 86%, 85%, 84% and 84% respectively.

[0104] Comparative Example 1

[0105] Synthesis of trimethylene carbonate without catalyst

[0106] 10 mmol (0.76 g) of 1,3-propylene glycol and 30 mL of 2-cyanopyridine were added to a 100 mL high-pressure stainless steel reactor. 2 Replace the air in the reactor three times and fill it with a certain pressure of CO at room temperature. 2 , heat to 80℃ and react for 4h. Monitor the pressure during the heating process to ensure that the pressure in the reactor is 1MPa. 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 vacuum-separated to obtain the target product with a yield of 15%.

[0107] Comparative Example 2

[0108] Synthesis of trimethylene carbonate using Mn-MOF catalyst

[0109] 0.04 g Mn-MOF, 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. 2 Replace the air in the reactor three times and fill it with a certain pressure of CO at room temperature. 2 , heat to 80℃ and react for 4h, monitor the pressure during the heating process to ensure that the pressure in the reactor is 1MPa. 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, filter to remove the catalyst, and vacuum separate the solution to obtain the target product with a yield of 42%.

[0110] The above examples show that the composite coordination network material M of the present invention is x O y -Mn-MOF is used as a catalyst to prepare trimethylene carbonate. This multiphase catalyst is easy to recycle and reuse, has high catalytic activity, a simple synthesis reaction process, and a high product yield, providing an important reference for the chemical utilization of carbon dioxide.

[0111] 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.

[0112] 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 x O y -Mn-MOF.

2. The method for synthesizing a cyclic carbonate according to claim 1, characterized in that: The M x O y -M in Mn-MOF x O y One of MgO, CuO, NiO, CoO, Nb2O5, V2O5, CeO2, SiO2, and PdO; The M x O y -Mn-MOF in Mn-MOF represents the metal organic framework material [Mn(HTTPCA)]H2O synthesized from MnCl2·4H2O and 1,1',1"-(1,3,5-triazine-2,4,6-triyl)tripiperidine-4-carboxylic acid.

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 60-120° C., and the reaction is carried out for 2-8 hours under stirring conditions.

5. The method for synthesizing a cyclic carbonate according to claim 1, characterized in that: M x O y The preparation of Mn-MOF includes the following steps: Mn-MOF and metal acetate are dispersed in a low boiling point solvent and stirred at room temperature for 30 to 90 minutes. Oxalic acid is added thereto until no more precipitation occurs. The obtained precipitate is centrifuged and dried at 60 to 80°C. The precipitate is transferred to a tube furnace and heated to 300 to 400°C at a heating rate of 5°C / min and kept at this temperature for 4 to 12 hours. The catalyst M is then taken out and cooled to room temperature to obtain the catalyst M. x O y -Mn-MOF.

6. The method for synthesizing a cyclic carbonate according to claim 5, characterized in that: The metal acetate is any one of MgAc2, CuAc2, NiAc2, CoAc2, NbAc5, VO(Ac)2, CeAc3, SiAc4, and PdAc2.

7. The method for synthesizing a cyclic carbonate according to claim 5, characterized in that: The low boiling point solvent is any one of ethanol, methanol, isopropanol, ethylene glycol, acetonitrile, benzene, toluene, chlorobenzene, dichloromethane, pyridine and tetrahydrofuran.

8. The method for synthesizing a cyclic carbonate according to claim 5, characterized in that: The preparation method of Mn-MOF comprises the following steps: The ligand H3TTPCA and MnCl2·4H2O were dissolved in a mixed solvent, the pH was adjusted to 5-7, ultrasonically mixed for 30 min, heated at 100-120°C for 12-48 h, the mixture was allowed to stand at room temperature for 10-12 h, filtered and the solid product was washed with anhydrous ethanol, and dried at 60-80°C to obtain Mn-MOF.

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