Catalyst for synthesizing ethylene carbonate as well as preparation method and application of catalyst
By introducing thioether groups into Schiff alkali metal complex catalysts and using ethylene carbonate as a solvent, combined with microwave ultrasonication to prepare the catalyst, the problems of environmental pollution and insufficient activity of traditional catalysts are solved, and the efficient and green synthesis of ethylene carbonate is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI CONCH MATERIAL TECHNOLOGY CO LTD
- Filing Date
- 2025-12-15
- Publication Date
- 2026-04-21
AI Technical Summary
Existing Schiff base metal complex catalysts require volatile organic solvents, leading to environmental pollution and operational complexity, and their catalytic activity and selectivity need to be improved.
A Schiff base metal complex catalyst with thioether groups introduced using ethylene carbonate as a solvent was prepared by microwave sonication, which improved catalytic activity and selectivity and avoided the use of volatile organic solvents.
This method efficiently catalyzes the synthesis of ethylene carbonate from carbon dioxide and epoxides under mild conditions, simplifying the process, improving catalyst solubility and activity, and reducing environmental impact.
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Figure CN121895342A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of ethylene carbonate synthesis, specifically relating to a catalyst for synthesizing ethylene carbonate, its preparation method, and its application. Background Technology
[0002] Carbon dioxide (CO2), as the most significant greenhouse gas, is a key driver of global climate change due to its continuously rising atmospheric concentration, posing a severe challenge to the ecological environment and human societal development. Effective capture and resource utilization of CO2, converting it into valuable chemicals, has become a crucial strategic direction for achieving "dual carbon" goals, developing a circular economy, and alleviating environmental pressure. Among these, the efficient conversion of CO2 with ethylene oxide into ethylene carbonate via a cycloaddition reaction is a highly attractive technological route. This reaction not only boasts high atom economy and directly consumes CO2, but the product, ethylene carbonate, also possesses broad application prospects due to its unique chemical properties (such as high polarity, high boiling point, low toxicity, and biodegradability), making it an extremely important chemical platform molecule and intermediate.
[0003] With the continuous expansion of downstream applications of ethylene carbonate, especially the explosive growth of the new energy industry, market demand continues to rise, making the need for efficient and green synthesis technologies increasingly urgent. Currently, the cycloaddition reaction of CO2 with ethylene oxide is the main method for industrial synthesis of ethylene carbonate, and the successful implementation of this reaction highly depends on the development of efficient catalysts. Among numerous catalyst systems, Schiff base metal complexes have been extensively studied due to their tunable structure and certain catalytic activity, and are currently one of the relatively mature and widely used homogeneous catalysts.
[0004] The catalytic mechanism of Schiff base metal complexes mainly involves the central metal acting as a Lewis acidic site to activate epoxides, polarizing CO bonds, and the diimino group (-N=) providing a Lewis basic site for the adsorption and activation of CO2 molecules. This leads to CO2 insertion and cyclization through nucleophilic ring-opening. While traditional Schiff base metal complex catalysts exhibit good catalytic activity, they generally require the addition of halogen quaternary ammonium salts as co-catalysts to achieve better synergistic catalytic effects. Furthermore, the synthesis of traditional catalysts typically uses volatile organic solvents (such as methanol, ethanol, acetonitrile, toluene, etc.). These solvents are not only harmful to the environment and operator health, but also require additional removal and recovery steps in subsequent treatment, increasing process complexity and energy consumption, thus contradicting the original intention of utilizing CO2 as a green chemical process. Therefore, developing a highly active, highly selective, and environmentally friendly catalyst system is of great significance. Summary of the Invention
[0005] The present invention aims to provide a catalyst for the synthesis of ethylene carbonate, its preparation method, and its application. The catalyst for the synthesis of ethylene carbonate uses ethylene carbonate as a green solvent and can efficiently catalyze the synthesis of ethylene carbonate from carbon dioxide and epoxides under mild conditions. At the same time, the catalyst introduces thioether groups into the Schiff base ligand structure, thereby improving catalytic activity and selectivity through multiple mechanisms. Furthermore, the polarity and flexible molecular conformation of the thioether groups can enhance the solubility of Schiff base metal complexes and their synthetic raw materials in ethylene carbonate.
[0006] Another objective of this invention is to provide the application of the catalyst for synthesizing ethylene carbonate in the synthesis of ethylene carbonate.
[0007] This invention provides a catalyst for synthesizing ethylene carbonate, the structural formula of which is shown below:
[0008] ;
[0009] In the formula, M represents Al. 3+ Zn 2+ Fe 3+ Co 3+ Mn 3+ Ni 3+ Mg 2+ or Ca 2+ One of them;
[0010] R1 is , , , , , or One of them;
[0011] R2 is one or more of H, CH3, C(CH3)3, F, Cl, Br, I or NO2;
[0012] Z is F - Cl - ,Br - I - NO3 - or CH3COO - One of them.
[0013] This invention provides a method for preparing the catalyst for synthesizing ethylene carbonate, the method comprising the following steps:
[0014] 1) Under inert gas protection, organic acids, aminophenyl sulfides and salicylaldehydes are dispersed in ethylene carbonate and condensed under microwave conditions to obtain a Schiff base ligand solution.
[0015] 2) Under inert gas protection, organic acid and metal source M are dispersed in Schiff base ligand solution, and coordination reaction is carried out under microwave conditions to obtain catalyst for the synthesis of ethylene carbonate.
[0016] In step 1) of the above preparation method, the structural formula of the aminophenyl sulfide compound is as follows: , or One of them, where R is one of CH3, Ph, PhNH2, PhNO2 or PhCl.
[0017] In step 1) of the above preparation method, the structural formula of the salicylaldehyde compound is as follows: In the formula, R is one or more of H, CH3, C(CH3)3, F, Cl, Br, I or NO2.
[0018] In the above preparation method, the organic acid is one of formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, succinic acid, tartaric acid, or benzoic acid.
[0019] In step 1) of the above preparation method, the molar ratio of the aminophenyl sulfide compound, salicylaldehyde compound, organic acid and ethylene carbonate is 1:1:0.0001~0.01:50~1000.
[0020] In step 2) of the above preparation method, the metal source M is one of zinc acetate, zinc bromide, calcium chloride, aluminum chloride, magnesium chloride, ferric chloride, manganese iodide, cobalt chloride, or cobalt acetate.
[0021] In step 2) of the above preparation method, the molar ratio of the metal source M, Schiff base ligand and organic acid is 0.5:1:0.0001~0.01.
[0022] In the above preparation method, the microwave power of the condensation reaction and the coordination reaction is 100~800 W, and the reaction time is 2~15 min.
[0023] In the above preparation method, the inert gas is either nitrogen or argon.
[0024] In the above preparation method, preferably, the dispersion is performed by ultrasound, the power of which is 100~400W and the ultrasound time is 10~30 min.
[0025] The present invention also provides the application of the catalyst for synthesizing ethylene carbonate in the synthesis of ethylene carbonate.
[0026] A method for synthesizing ethylene carbonate, the method utilizing a catalyst for synthesizing ethylene carbonate as a catalyst to synthesize ethylene carbonate, the method comprising the following steps:
[0027] A solution of ethylene carbonate, containing a catalyst for the synthesis of ethylene carbonate, is added to a reaction vessel. The reaction vessel is then purged with carbon dioxide. After purging, ethylene oxide is added to the reaction vessel. Once this is complete, carbon dioxide is introduced to maintain the pressure in the reaction system at 0.1–5.0 MPa. The mixture is stirred and heated to 20–180 °C. After reacting for 1–72 h, stirring is stopped, the mixture is cooled to room temperature, and the unreacted carbon dioxide is released. The product, ethylene carbonate, is then separated.
[0028] In the above method, the molar ratio of the catalyst used to synthesize ethylene carbonate to ethylene oxide is 1:500~500000.
[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0030] 1. The thioether group in the benzene ring linked to the imino group in the catalyst for synthesizing ethylene carbonate provided by this invention can enhance the Lewis acidity of the metal center through a weak electron-donating effect, thereby strengthening its electrophilic activation ability for epoxide substrates. The sulfur atom in the thioether group (RS-R') has a lone pair of electrons, which can act as a nucleophile to directly attack the sterically less hindered carbon atom in the epoxide, initiating ring opening. At the same time, the weak Lewis basicity of the thioether can promote the activation and adsorption of CO2, stabilize the high-energy anionic intermediate, prevent its decomposition, and accelerate subsequent cyclization. The introduction of the thioether group into the ligand structure can replace the role of co-catalysts such as quaternary ammonium halides (e.g., TBAB), producing a synergistic catalytic effect.
[0031] 2. The polarity and flexible molecular conformation of the thioether group in the catalyst for synthesizing ethylene carbonate provided by this invention can improve the solubility of Schiff base metal complexes and their synthetic raw materials in ethylene carbonate. Therefore, using ethylene carbonate to replace toxic and volatile organic solvents such as methanol and toluene in the preparation of the catalyst is not only green and environmentally friendly, but the synthesized catalyst solution can also be directly used as the reaction substrate for synthesizing ethylene carbonate to exert a highly efficient catalytic effect, which greatly simplifies the synthesis process of the catalyst and ethylene carbonate.
[0032] 3. The catalyst for synthesizing ethylene carbonate provided by this invention is prepared using an ultrasonic and microwave reaction method, which enhances mass transfer efficiency and significantly improves the reaction rate of catalyst synthesis;
[0033] 4. The catalyst for synthesizing ethylene carbonate provided by this invention has high activity and good selectivity, and can efficiently catalyze the synthesis of ethylene carbonate under mild conditions; Attached Figure Description
[0034] Figure 1This is a diagram illustrating the preparation process of the catalyst used in the synthesis of ethylene carbonate. Detailed Implementation
[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0036] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.
[0037] Example 1
[0038] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0039] 1) Dissolve 0.1 mol of 2-aminoaniline sulfide and 0.1 mol of 3-tert-butylsalicylaldehyde in 1000 g of ethylene carbonate at 50 °C, add 0.001 mol of acetic acid as a catalyst, protect the reaction system with nitrogen purging, sonicate at 400 W for 10 min, and condense under microwave at 400 W for 4 min to obtain a ethylene carbonate solution of Schiff base ligand;
[0040] 2) Add 0.05 mol of zinc acetate and 0.001 mol of acetic acid as a catalyst to the ethylene carbonate solution of the Schiff base ligand obtained in step 1). Protect the reaction system by purging with nitrogen, sonicate at 400 W for 10 min, and then perform a coordination reaction under microwave at 400 W for 4 min to obtain a ethylene carbonate solution containing the catalyst for synthesizing ethylene carbonate. The structural formula of the catalyst for synthesizing ethylene carbonate is shown below:
[0041] .
[0042] Example 2
[0043] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0044] 1) Dissolve 0.1 mol of 2-aminodiphenyl sulfide and 0.1 mol of salicylaldehyde in 1000 g of ethylene carbonate at 80 °C, add 0.0005 mol of formic acid as a catalyst, protect the reaction system with nitrogen, sonicate at 200 W for 20 min, and condense under microwave at 200 W for 8 min to obtain a ethylene carbonate solution of Schiff base ligand.
[0045] 2) Add 0.05 mol of zinc bromide and 0.0005 mol of formic acid as a catalyst to the ethylene carbonate solution of the Schiff base ligand obtained in step 1). Protect the reaction system by purging with nitrogen, sonicate at 200 W for 20 min, and then perform a coordination reaction under microwave at 200 W for 8 min to obtain a ethylene carbonate solution containing the catalyst for synthesizing ethylene carbonate. The structural formula of the catalyst for synthesizing ethylene carbonate is shown below:
[0046] .
[0047] Example 3
[0048] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0049] 1) 0.1 mol of 2-amino-4'-chlorodiphenyl sulfide and 0.1 mol of 5-bromosalicylic acid were dissolved in 1000 g of ethylene carbonate at 60 °C. 0.0001 mol of oxalic acid was added as a catalyst. The reaction system was protected by nitrogen purging. The mixture was sonicated at 400 W for 10 min and then condensed under microwave at 150 W for 12 min to obtain a ethylene carbonate solution containing Schiff base ligands.
[0050] 2) Add 0.05 mol of manganese iodide and 0.0001 mol of oxalic acid as a catalyst to the ethylene carbonate solution of the Schiff base ligand obtained in step 1). Protect the reaction system by purging with nitrogen, sonicate at 400 W for 10 min, and then perform a coordination reaction under microwave at 150 W for 12 min to obtain a ethylene carbonate solution containing the catalyst for synthesizing ethylene carbonate. The structural formula of the catalyst for synthesizing ethylene carbonate is shown below:
[0051] .
[0052] Example 4
[0053] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0054] 1) Dissolve 0.1 mol of 3-aminoanisidine sulfide and 0.1 mol of 3,5-di-tert-butylsalicylaldehyde in 1000 g of ethylene carbonate at 100 °C, add 0.001 mol of propionic acid as a catalyst, protect the reaction system with nitrogen purging, sonicate at 300 W for 15 min, and condense under microwave at 300 W for 6 min to obtain a ethylene carbonate solution of Schiff base ligand.
[0055] 2) Add 0.05 mol of calcium chloride and 0.001 mol of propionic acid as a catalyst to the ethylene carbonate solution of the Schiff base ligand obtained in step 1). Protect the reaction system with nitrogen purging, sonicate at 300 W for 15 min, and then perform a coordination reaction under microwave at 300 W for 6 min to obtain a ethylene carbonate solution containing the catalyst for synthesizing ethylene carbonate. The structural formula of the catalyst for synthesizing ethylene carbonate is shown below:
[0056] .
[0057] Example 5
[0058] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0059] 1) Dissolve 0.1 mol of 4-aminoanisidine sulfide and 0.1 mol of 3,5-dibromosalicylic acid in 1000 g of ethylene carbonate at 45 °C, add 0.0005 mol of butyric acid as a catalyst, protect the reaction system with nitrogen purging, sonicate at 200 W for 20 min, and condense under microwave at 200 W for 10 min to obtain a ethylene carbonate solution of Schiff base ligand.
[0060] 2) Add 0.05 mol of aluminum chloride and 0.0005 mol of butyric acid as a catalyst to the ethylene carbonate solution of the Schiff base ligand obtained in step 1). Protect the reaction system with nitrogen purging, sonicate at 200 W for 20 min, and then perform a coordination reaction under microwave at 200 W for 10 min to obtain a ethylene carbonate solution containing the catalyst for synthesizing ethylene carbonate. The structural formula of the catalyst for synthesizing ethylene carbonate is shown below:
[0061] .
[0062] Example 6
[0063] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0064] 1) Dissolve 0.1 mol of 2-amino-2'-nitrodiphenyl sulfide and 0.1 mol of 5-fluorosalicylaldehyde in 1000 g of ethylene carbonate at 50 °C. Protect the reaction system with nitrogen purging. Add 0.01 mmol of benzoic acid as a catalyst. Sonicate at 400 W for 10 min and microwave at 400 W for 4 min to obtain a ethylene carbonate solution of Schiff base ligand.
[0065] 2) Add 0.05 mol of magnesium chloride and 0.01 mmol of benzoic acid as a catalyst to the ethylene carbonate solution of the Schiff base ligand obtained in step 1). Protect the reaction system by purging with nitrogen, sonicate at 400 W for 10 min, and then perform a coordination reaction under microwave at 400 W for 4 min to obtain a ethylene carbonate solution containing the catalyst for synthesizing ethylene carbonate. The structural formula of the catalyst for synthesizing ethylene carbonate is shown below:
[0066] .
[0067] Example 7
[0068] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0069] 1) 0.1 mol of 2,2'-diaminodiphenyl sulfide and 0.1 mol of 5-methylsalicylaldehyde were dissolved in 1000 g of ethylene carbonate at 60 °C. 0.2 mmol of succinic acid was added as a catalyst. The reaction system was protected by nitrogen purging. The mixture was sonicated at 400 W for 10 min and then condensed under microwave at 800 W for 2 min to obtain a ethylene carbonate solution containing Schiff base ligands.
[0070] 2) Add 0.05 mol of cobalt acetate to the ethylene carbonate solution of the Schiff base ligand obtained in step 1), and add 0.2 mmol of succinic acid as a catalyst. Protect the reaction system by purging with nitrogen, sonicate at 400 W for 10 min, and then perform a coordination reaction under microwave at 800 W for 2 min to obtain a ethylene carbonate solution containing the catalyst for synthesizing ethylene carbonate. The structural formula of the catalyst for synthesizing ethylene carbonate is shown below:
[0071] .
[0072] Example 8
[0073] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0074] 1) Dissolve 0.1 mol of 2-aminodiphenyl sulfide and 0.1 mol of 3,5-dichlorosalicylaldehyde in 1000 g of ethylene carbonate at 90 °C, add 0.001 mol of formic acid as a catalyst, protect the reaction system with nitrogen purging, sonicate at 200 W for 20 min, and condense under microwave at 200 W for 10 min to obtain a ethylene carbonate solution of Schiff base ligand.
[0075] 2) Add 0.05 mol of cobalt chloride and 0.001 mol of formic acid as a catalyst to the ethylene carbonate solution of the Schiff base ligand obtained in step 1). Protect the reaction system by purging with nitrogen, sonicate at 200 W for 10 min, and then perform a coordination reaction under microwave at 200 W for 10 min to obtain a ethylene carbonate solution containing the catalyst for synthesizing ethylene carbonate. The structural formula of the catalyst for synthesizing ethylene carbonate is shown below:
[0076] .
[0077] Example 9
[0078] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0079] 1) Dissolve 0.1 mol of 2-aminoaniline sulfide and 0.1 mol of 3,5-di-tert-butylsalicylaldehyde in 1000 g of ethylene carbonate at 60 °C, add 0.0003 mol of acetic acid as a catalyst, protect the reaction system with nitrogen purging, sonicate at 300 W for 10 min, and condense under microwave at 100 W for 15 min to obtain a ethylene carbonate solution of Schiff base ligand.
[0080] 2) Add 0.05 mol of zinc bromide and 0.0003 mol of acetic acid as a catalyst to the ethylene carbonate solution of the Schiff base ligand obtained in step 1). Protect the reaction system with nitrogen purging, sonicate at 300 W for 15 min, and then perform a coordination reaction under 100 W microwave for 15 min to obtain a ethylene carbonate solution containing the catalyst for synthesizing ethylene carbonate. The catalyst for synthesizing ethylene carbonate has the following structural formula:
[0081] .
[0082] Example 10
[0083] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0084] 1) 0.1 mol of 4-chloro-4′-aminodiphenyl sulfide and 0.1 mol of 5-iodosalicylic acid were dissolved in 1000 g of ethylene carbonate at 80 °C. 0.0005 mol of succinic acid was added as a catalyst. The reaction system was protected by nitrogen purging. The system was sonicated at 400 W for 10 min and then condensed under microwave at 400 W for 4 min to obtain a ethylene carbonate solution of Schiff base ligand.
[0085] 2) Add 0.05 mol of zinc acetate and 0.0005 mol of succinic acid as a catalyst to the ethylene carbonate solution of the Schiff base ligand obtained in step 1). Protect the reaction system with nitrogen purging, sonicate at 400 W for 10 min, and then perform a coordination reaction under microwave at 400 W for 4 min to obtain a ethylene carbonate solution containing the catalyst for synthesizing ethylene carbonate. The structural formula of the catalyst for synthesizing ethylene carbonate is shown below:
[0086] .
[0087] Example 11
[0088] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0089] 1) Dissolve 0.1 mol of 3-aminoanisidine sulfide and 0.1 mol of 5-nitrosalicylic acid in 1000 g of ethylene carbonate at 50 °C, add 0.001 mol of acetic acid as a catalyst, protect the reaction system with nitrogen purging, sonicate at 300 W for 15 min, and condense under microwave at 300 W for 6 min to obtain a ethylene carbonate solution of Schiff base ligand.
[0090] 2) Add 0.05 mol of zinc bromide and 0.001 mol of acetic acid as a catalyst to the ethylene carbonate solution of the Schiff base ligand obtained in step 1). Protect the reaction system with nitrogen purging, sonicate at 300 W for 15 min, and then perform a coordination reaction under microwave at 300 W for 6 min to obtain a ethylene carbonate solution containing the catalyst for synthesizing ethylene carbonate. The structural formula of the catalyst for synthesizing ethylene carbonate is shown below:
[0091] .
[0092] Example 12
[0093] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0094] 1) Dissolve 0.1 mol of 4-amino-4'-nitrodiphenyl sulfide and 0.1 mol of 5-chlorosalicylaldehyde in 1000 g of ethylene carbonate at 50 °C, add 0.01 mmol of tartaric acid as a catalyst, protect the reaction system with nitrogen purging, sonicate at 400 W for 10 min, and condense under microwave at 400 W for 4 min to obtain a ethylene carbonate solution of Schiff base ligand.
[0095] 2) Add 0.05 mol of ferric chloride and 0.01 mmol of tartaric acid as a catalyst to the ethylene carbonate solution of the Schiff base ligand obtained in step 1). Protect the reaction system with nitrogen purging, sonicate at 400 W for 10 min, and then perform a coordination reaction under microwave at 400 W for 4 min to obtain a ethylene carbonate solution containing the catalyst for synthesizing ethylene carbonate. The structural formula of the catalyst for synthesizing ethylene carbonate is shown below:
[0096] .
[0097] Comparative Example 1
[0098] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0099] 1) Dissolve 0.1 mol of 2-aminobenzyl sulfide and 0.1 mol of 3-tert-butylsalicylaldehyde in 300 mL of methanol, add 0.05 mol of zinc acetate, and then add 0.001 mol of acetic acid as a catalyst. Heat and reflux at 70 °C for 4 h with stirring.
[0100] 2) After the reaction is completed and cooled to room temperature, methanol is removed by vacuum distillation, dried, dissolved in acetonitrile at 60°C, and then crystallized in an ice-water bath to obtain a catalyst for the synthesis of ethylene carbonate. The structural formula of the catalyst for the synthesis of ethylene carbonate is shown below:
[0101] .
[0102] Comparative Example 2
[0103] A method for preparing a catalyst for the synthesis of ethylene carbonate, the method comprising the following steps:
[0104] 1) Dissolve 0.1 mol of aminobenzene and 0.1 mol of 3-tert-butylsalicylaldehyde in 1000 g of ethylene carbonate at 45 °C, add 0.001 mol of acetic acid as a catalyst, protect the reaction system with nitrogen purging, sonicate at 400 W for 10 min, and microwave at 400 W for 4 min to obtain a ethylene carbonate solution of Schiff base ligand.
[0105] 2) Add 0.05 mol of zinc acetate to the ethylene carbonate solution of the Schiff base ligand obtained in step 1) to carry out a coordination reaction. Add 0.001 mol of acetic acid as a catalyst. Protect the reaction system with nitrogen purging, sonicate at 400 W for 10 min, and then microwave at 400 W for 4 min to obtain a ethylene carbonate solution containing the catalyst for synthesizing ethylene carbonate. The structural formula of the catalyst for synthesizing ethylene carbonate is shown below:
[0106] .
[0107] Application Example 1
[0108] A method for synthesizing ethylene carbonate using the catalysts prepared in the various embodiments and comparative examples, the method comprising the following steps:
[0109] 200 g of ethylene carbonate solution containing 0.01 mol of the catalyst prepared in each example and comparative example for the synthesis of ethylene carbonate was added to a 1 L high-pressure reactor equipped with a mechanical stirrer and a temperature-controlled heating device. The air in the reactor was replaced with carbon dioxide. After adding 400 g of ethylene oxide, carbon dioxide was continuously introduced to maintain the pressure in the reaction system to 1.0 MPa. The mixture was stirred and heated to 130 °C. After reacting for 3 h, stirring was stopped, and the mixture was cooled to room temperature. The unreacted carbon dioxide was released, and the reactor liquid was separated by vacuum distillation to obtain the product ethylene carbonate reaction solution.
[0110] Test Example 1
[0111] Conversion rate, selectivity, and yield testing:
[0112] The ethylene carbonate reaction solution prepared in Application Example 1 was directly sampled for qualitative and quantitative analysis by GC and GC-MS. Qualitative analysis was performed using an Agilent HP6890 / 5973 GC-MS system; quantitative analysis was performed using a Shanghai Analytical Instrument Factory GC-112A gas chromatograph. The conversion, selectivity, and yield results are shown in Table 1 below.
[0113] Table 1 Catalytic performance of ethylene carbonate synthesis in each example and comparative example
[0114] sample Conversion rate (%) Selectivity (%) Yield (%) Comparative Example 1 90 98.9 85.7 Comparative Example 2 81.2 97.9 82.6 Example 1 91.2 99.5 92.5 Example 2 94.8 99.4 94.7 Example 3 95.1 99.7 93.6 Example 4 93.6 99.6 91.8 Example 5 96.8 99.5 94.1 Example 6 95.7 99.6 93.4 Example 7 92.3 99.7 95.1 Example 8 97.4 99.5 91.7 Example 9 96.5 99.3 92.0 Example 10 94.9 99.4 91.6 Example 11 91.8 99.3 90.7 Example 12 93.4 99.5 93.8
[0115] The samples in Example 1 and Comparative Example 1 used the same raw materials but different synthesis methods. The ultrasonic-microwave method significantly improved the preparation rate of the Schiff base metal catalyst. Furthermore, ethylene carbonate was used as the reaction solvent, avoiding the use of volatile organic solvents and reducing cumbersome processes such as vacuum distillation and recrystallization. The resulting catalyst samples showed similar results in conversion rate, selectivity, and yield when used for the synthesis of ethylene carbonate. Comparative Example 2 was a Schiff base metal catalyst without thioether groups. When used alone, it exhibited lower catalytic activity and selectivity. The catalyst samples containing thioether groups in Examples 1 to 12 achieved ethylene oxide conversion rates above 90%, ethylene carbonate selectivity above 99.3%, and yields above 90% when used for the synthesis of ethylene carbonate. The introduction of thioether groups improved catalyst activity and selectivity for ethylene carbonate through multiple mechanisms, including electronic effects.
[0116] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0117] The above description of the embodiments is intended to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.
Claims
1. A catalyst for synthesizing ethylene carbonate, characterized in that, The structural formula of the catalyst used for synthesizing ethylene carbonate is shown below: ； In the formula, M represents Al. 3+ Zn 2+ Fe 3+ Co 3+ Mn 3+ Ni 3+ Mg 2+ or Ca 2+ One of them; R1 is , , , , , or One of the following; R2 is one or more of H, CH3, C(CH3)3, F, Cl, Br, I, or NO2; Z is F - Cl - ,Br - I - NO3 - or CH3COO - One of them.
2. A method for preparing a catalyst for synthesizing ethylene carbonate as described in claim 1, characterized in that, The preparation method includes the following steps: 1) Under inert gas protection, organic acids, aminophenyl sulfides and salicylaldehydes are dispersed in ethylene carbonate and condensed under microwave conditions to obtain a Schiff base ligand solution. 2) Under inert gas protection, organic acid and metal source M are dispersed in Schiff base ligand solution, and coordination reaction is carried out under microwave conditions to obtain catalyst for the synthesis of ethylene carbonate.
3. The method for preparing the catalyst for synthesizing ethylene carbonate according to claim 2, characterized in that, In step 1) of the preparation method, the structural formula of the aminophenyl sulfide compound is as follows: , or One of them, where R is one of CH3, Ph, PhNH2, PhNO2 or PhCl.
4. The method for preparing the catalyst for synthesizing ethylene carbonate according to claim 2, characterized in that, In step 1) of the preparation method, the structural formula of the salicylaldehyde compound is shown below: ； In the formula, R is one or more of H, CH3, C(CH3)3, F, Cl, Br, I or NO2.
5. The method for preparing the catalyst for synthesizing ethylene carbonate according to claim 2, characterized in that, The organic acid is one of formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, succinic acid, tartaric acid, or benzoic acid.
6. The method for preparing the catalyst for synthesizing ethylene carbonate according to any one of claims 2-5, characterized in that, In step 1) of the preparation method, the molar ratio of the aminophenyl sulfide compound, salicylaldehyde compound, organic acid and ethylene carbonate is 1:1:0.0001~0.01:50~1000.
7. The method for preparing the catalyst for synthesizing ethylene carbonate according to claim 2, characterized in that, In step 2) of the preparation method, the metal source M is one of zinc acetate, zinc bromide, calcium chloride, aluminum chloride, magnesium chloride, ferric chloride, manganese iodide, cobalt chloride, or cobalt acetate.
8. The method for preparing the catalyst for synthesizing ethylene carbonate according to any one of claims 2, 5, or 7, characterized in that, In step 2) of the preparation method, the molar ratio of the metal source M, the Schiff base ligand, and the organic acid is 0.5:1:0.0001~0.
01.
9. The method for preparing the catalyst for synthesizing ethylene carbonate according to claim 2, characterized in that, The microwave power for the condensation reaction and the coordination reaction is 100~800 W, and the reaction time is 2~15 min.
10. The application of the catalyst for synthesizing ethylene carbonate as described in claim 1 in the synthesis of ethylene carbonate.