Composite resin catalyst for synthesizing cyclic carbonate as well as preparation method and application of composite resin catalyst

Abstract

The invention belongs to the technical field of cyclic carbonate synthesis, and particularly relates to a composite resin catalyst for cyclic carbonate synthesis and a preparation method and application thereof. The preparation method of the composite resin catalyst for synthesizing cyclic carbonate comprises the steps of preparing the carrier and preparing the composite resin catalyst. The composite resin catalyst prepared by the invention has the advantages of high activity, strong stability and the like when being used for synthesizing cyclic carbonate from carbon dioxide and alkylene oxide.

Description

Technical Field

[0001] This invention belongs to the field of cyclic carbonate synthesis technology, specifically relating to composite resin catalysts for cyclic carbonate synthesis, their preparation methods, and applications. Background Technology

[0002] Cyclic carbonates such as ethylene carbonate and propylene carbonate are high-performance organic solvents and intermediates, and are important components of lithium-ion battery electrolytes. Meanwhile, carbon dioxide is a greenhouse gas, and its capture, fixation, and utilization have become one of the most pressing issues of this century. The synthesis of ethylene carbonate and propylene carbonate from ethylene oxide, propylene oxide, and carbon dioxide is a highly efficient method for utilizing carbon dioxide resources. With the development of electrification in my country, the fixation of carbon dioxide through cyclic carbonates has significant economic value and environmental protection implications.

[0003] Most catalysts used in the synthesis of cyclic carbonates are homogeneous catalysts, including one or more mixtures of alkali (earth) metal halides, transition metal salts, metal complexes, organic amines, organophosphorus compounds, quaternary ammonium salts, quaternary phosphonium salts, imidazole salts, etc. These homogeneous catalytic systems suffer from problems such as high catalyst consumption and high energy consumption in separating the catalyst from the product.

[0004] To overcome this challenge, the industry has developed supported cyclic carbonate catalysts.

[0005] Supported cyclic carbonate catalysts include metal oxide catalysts, molecular sieve catalysts, supported organic amines, organophosphorus catalysts, and supported ionic liquid catalysts. Currently, supported organic amines, organophosphorus catalysts, and supported ionic liquid catalysts exhibit good catalytic activity, but the loss of active components during the reaction leads to poor catalyst stability. For example, Chinese patent CN105503811B discloses that after five cycles of use in a reactor (120℃, 2.0MPa, 3h) with a conventional composite imidazole resin catalyst, the ethylene oxide conversion rate was only 75.8%. However, a composite imidazole resin catalyst modified by incorporating multi-walled carbon nanotubes and then supporting imidazole active components showed an improved ethylene oxide conversion rate of 93.6% after five cycles under the same reaction conditions. However, this preparation process requires the addition of extra carbon nanotubes, increasing the cost and difficulty of catalyst preparation.

[0006] Controlling the cost of cyclic carbonate supported catalysts, developing convenient preparation methods, and further improving the stability of supported catalyst activity and ensuring long-term operation of catalysts are of great significance to the industry. Summary of the Invention

[0007] This invention provides a composite resin catalyst for the synthesis of cyclic carbonates, which is applied to the reaction of cyclic carbonates synthesized from epoxides and carbon dioxide, and improves the problem of activity decay of supported catalysts in the prior art.

[0008] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a composite resin catalyst for the synthesis of cyclic carbonates, comprising the following steps: S1: Preparation of the support The monomer, comonomer, and initiator are mixed in a container to obtain an oily mixed solution. An aqueous solution of the additives is added to the oily mixed solution, and the container is placed in an oil bath. The reaction is carried out by gradually increasing the temperature: at 60-70°C for 0.5-4 hours, the temperature is further increased to 70-90°C for 2-8 hours, and then the temperature is increased to 90-95°C for 8-16 hours, at which point the reaction is terminated. The resulting solid is extracted, washed, filtered, dried, and sieved to obtain a chloromethylated polystyrene crosslinked resin carrier, which is the carrier itself.

[0009] S2: Preparation of composite resin catalyst S2-1: Place the carrier in a container, then place the container in an oil bath, evacuate the bath, and replace the evacuation gas with an inert gas. Under inert gas protection, add the swelling solvent and heat and stir to induce swelling.

[0010] S2-2: Organic amines, organophosphines, and alkylimidazolium are added to the reaction system after swelling in S2-1 under inert gas protection, and then grafted onto the chloromethyl group on the support.

[0011] S2-3: Remove the liquid from the S2-2 reaction system, wash with washing solvent until the mass of the washing liquid remains unchanged, then wash with deionized water to remove the organic solvent, and finally dry to obtain the composite resin catalyst.

[0012] In a preferred embodiment, in S1, the total weight percentage of monomers, comonomers, initiators and auxiliaries is 85% to 95%; the weight percentage of comonomers is 5% to 10%; the weight percentage of initiators is 0.1% to 10%; and the weight percentage of auxiliaries is 1% to 20%.

[0013] In a preferred embodiment, the monomer in S1 is selected from at least one of 4-vinylbenzyl chloride, methyl methacrylate, styrene, and 4-butylstyrene.

[0014] In a preferred embodiment, the comonomer in S1 is selected from at least one of diallylbenzene, methylenebisacrylamide, and divinylbenzene.

[0015] In a preferred embodiment, the initiator in S1 is selected from at least one of benzoyl peroxide, azobisisobutyronitrile, lauroyl peroxide, and cumene hydroperoxide.

[0016] In a preferred embodiment, the additive in S1 is selected from at least one of polyvinyl alcohol, starch, gelatin, sodium polyphosphate, methylcellulose, and 2-hydroxyethylcellulose.

[0017] As a preferred embodiment, the chlorine content of the chloromethylated polystyrene crosslinked resin carrier is 15%~20%, and the degree of crosslinking (specifically, the DVB value) is 7%~10%.

[0018] In a preferred embodiment, the swelling solvent in S2 is selected from any one or more of N,N-dimethylformamide, toluene, mesitylene, ethanol, and acetonitrile.

[0019] In a preferred embodiment, the mass ratio of swelling solvent to carrier in S2-1 is 8~20:1, preferably 10~15:1.

[0020] In a preferred embodiment, the swelling temperature in S2-1 is 20~100℃, preferably 40~80℃; the swelling time is 2~24 hours, preferably 3~16 hours.

[0021] In a preferred embodiment, the organic amine, organophosphine, and alkylimidazole in S2-2 are selected from any one or more of tertiary amines, tertiary phosphines, N-alkylimidazoles, aminopyridines, aminopiperazines, and aminotriazoles, including but not limited to triethylamine, tri-n-propylamine, tri-n-pentylamine, chloropropyl dibutylamine, triphenylphosphine, tri-p-tolylphosphine or N-butylimidazole, 2-aminopyridine, aminoethylpiperazine, 3-amino-1,2,4-triazoles, etc.

[0022] In a preferred embodiment, the mass ratio of organic amine, organic phosphine, alkyl imidazole to carrier in S2-2 is 0.5~3:1, preferably 0.7~2:1.

[0023] In a preferred embodiment, the grafting reaction temperature in S2-2 is 50~120℃, preferably 70~100℃; the reaction time is 6~48 hours, preferably 8~24 hours.

[0024] In a preferred embodiment, the washing solvent in S2-3 is selected from any one of methanol, tetrahydrofuran, ethanol, acetone, acetonitrile, ethyl acetate, dichloromethane, and dichloroethane.

[0025] In a preferred embodiment, the mass ratio of the washing solvent used in a single wash to the carrier in S2-3 is 5~50:1, preferably 10~25:1; the number of washes is 2~8, preferably 3~5.

[0026] In a preferred embodiment, the drying temperature in S2-3 is 60~110℃, preferably 75~100℃; the drying time is 6~48 hours, preferably 10~36 hours.

[0027] In a preferred embodiment, S2 may further include step S2-4: subjecting the composite resin catalyst obtained in S2-3 to an ion exchange reaction by adding the composite resin catalyst to a metal halide solution prepared with a halogen exchange solvent, performing one or more halogen ion exchanges, and then washing and drying to obtain the ion exchange composite resin catalyst.

[0028] In a preferred embodiment, the halogen exchange solvent in S2-4 is water or at least one of ethanol, propanol, and isopropanol.

[0029] In a preferred embodiment, the weight of the halogen exchange solvent in S2-4 is 10 to 40 times, preferably 15 to 30 times, the weight of the composite resin catalyst.

[0030] In a preferred embodiment, the metal halide in S2-4 includes at least one of NaBr, KBr, NaI, KI, MgBr2, MgI2, CaBr2, CaI2, BaBr2, or BaI2.

[0031] In a preferred embodiment, the weight of the metal halide in S2-4 is 1 to 10 times, preferably 2 to 6 times, the weight of the composite resin catalyst.

[0032] In a preferred embodiment, the ion exchange reaction temperature in S2-4 is 20~80℃, preferably 20~60℃; the reaction time is 3~24 hours, preferably 6~18 hours. The ion exchange reaction is repeated 1~8 times, preferably 2~5 times.

[0033] Preparation process of composite resin catalyst: ;

[0034] Where X represents organic amine, organophosphine, or alkylimidazolium; R3N represents organic amine; R3P represents organophosphine; RIm represents alkylimidazolium; Y represents halogen exchange solvent solution of metal halide; and m, n, and z are positive integers.

[0035] A second aspect of the present invention provides a composite resin catalyst for the synthesis of cyclic carbonates, obtained by the preparation method described above.

[0036] A third aspect of the present invention provides the application of a composite resin catalyst for the synthesis of cyclic carbonates, specifically for the synthesis of cyclic carbonates.

[0037] A fourth aspect of the present invention provides a method for synthesizing cyclic carbonates, the method comprising: using a composite resin catalyst prepared in the present invention to catalyze the synthesis of cyclic carbonates from carbon dioxide and epoxides.

[0038] This invention does not impose any other limitations on the specific synthesis method of the above-mentioned cyclic carbonates. Based on the use of composite resin catalysts, conventional synthesis methods in the art can be adopted, including but not limited to: high-pressure reactor batch method and fixed-bed continuous method.

[0039] The synthetic reaction process of cyclic carbonates: ; R1 and R2 are H or alkyl groups, and Cat is the composite resin catalyst prepared in this invention.

[0040] In a preferred embodiment, the cyclic carbonate includes, but is not limited to, ethylene carbonate and propylene carbonate.

[0041] This invention increases the initial loading of the active component by increasing the chlorine content of the chloromethylated polystyrene crosslinked resin support. Optionally, the preparation method of the composite resin catalyst may further include a step of bromide ion exchange on the obtained composite resin catalyst.

[0042] In the preparation of the composite resin catalyst, a suitable solvent is used to swell the chloromethylated polystyrene crosslinked resin support, thereby expanding the pores of the support. Large molecular active centers such as organic amines, organophosphorus compounds, and alkylimidazolium can then enter the interior of the support through these pores. The composite resin catalyst particles obtained after loading or ion exchange all show some expansion. In the process of catalyzing the synthesis of cyclic carbonates from carbon dioxide and epoxides using the catalyst of this invention, it was unexpectedly discovered that the composite resin catalyst prepared from a high-chlorine, high-crosslinking degree chloromethylated polystyrene crosslinked resin support exhibited particle size shrinkage after the reaction. However, no particle size shrinkage was observed after the reaction in the composite resin catalyst prepared from a commercially available low-chlorine, low-crosslinking degree chloromethylated polystyrene crosslinked resin support. No particle size shrinkage was also observed after the reaction in the composite resin catalyst prepared from a carbon nanotube-modified chloromethylated polystyrene crosslinked resin support. Experimental data are shown in Table 2. Particle shrinkage is beneficial for reducing the enlarged pores during the preparation process, thus reducing the loss of active centers such as organic amines, organophosphorus compounds, and alkylimidazolium compounds.

[0043] Compared with the prior art, the present invention achieves at least the following technical effects: Compared with the prior art, the catalyst prepared by the present invention has high activity and good stability. Attached Figure Description

[0044] Figure 1 The figure shows the results of the fixed-bed continuous flow stability test of the catalyst. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below. However, it should be understood that the description herein is merely illustrative and not intended to limit the scope of the invention.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. All reagents and instruments used herein are commercially available, and the characterization methods involved are described in relevant prior art and will not be repeated herein.

[0047] Example 1-1 This embodiment provides a composite resin catalyst for the synthesis of ethylene carbonate, and the preparation method includes the following steps: S1: Preparation of the support In a 500 mL three-necked flask, 7.0 g of styrene, 50.0 g of 4-vinylbenzyl chloride, 5.0 g of divinylbenzene (corresponding to a crosslinking degree DVB of 8.1%), and 0.3 g of azobisisobutyronitrile initiator were added and stirred at room temperature for 15 minutes. Then, 130 mL of deionized water containing 0.4 g of 2-hydroxyethyl cellulose, 0.3 g of sodium polyphosphate, and 5.0 g of gelatin was added. The stirring speed was adjusted, and the mixture was stirred at 60 °C for 2 hours. The temperature was then gradually increased to 80 °C and reacted for 4 hours. Finally, the temperature was increased to 90 °C and reacted for 12 hours. After the reaction was completed, the supernatant was decanted, and the resulting solid was washed three times with hot water at 85 °C and ethanol. The solid was then filtered, dried in an oven at 90 °C, sieved, and the chloromethylated polystyrene crosslinked resin carrier R1 in the range of 20–40 mesh was collected.

[0048] S2: Preparation of composite resin catalyst A 250 mL three-necked flask was evacuated and purged with nitrogen. 10 g of chloromethylated polystyrene crosslinked resin carrier R1 and 120 mL of N,N-dimethylformamide were added. The mixture was stirred and swollen at 60 °C for 8 hours. After swelling, 7.3 g of triethylamine was added under a nitrogen atmosphere, and the mixture was heated to 90 °C and reacted for 16 hours. The solution was filtered off, washed three times with 75 mL each of tetrahydrofuran, methanol, and deionized water, and dried at 90 °C for 12 hours to obtain the composite resin catalyst A1.

[0049] Examples 1-2 This embodiment provides a composite resin catalyst for the synthesis of ethylene carbonate. The specific implementation method is the same as that in Example 1-1, except that the composite resin catalyst A1 is subjected to ion exchange treatment. The specific operation is as follows: Add 10 g of composite resin catalyst A1, 20.6 g of sodium bromide, 150 mL of deionized water and 50 mL of ethanol to a 300 mL beaker. Stir at 45 °C for 12 hours to carry out ion exchange. Filter the solution and repeat the ion exchange 3 times. After the ion exchange is completed, filter and wash, and dry at 90 °C for 12 hours to obtain composite resin catalyst A2.

[0050] Example 2-1 This embodiment provides a composite resin catalyst for the synthesis of ethylene carbonate. The specific implementation method is the same as that in Example 1-1, except that 7.3 g of triethylamine in S2 is replaced with 10.2 g of tri-n-propylamine to obtain composite resin catalyst B1.

[0051] Example 2-2 This embodiment provides a composite resin catalyst for the synthesis of ethylene carbonate. The specific implementation method is the same as that in Example 2-1, except that the composite resin catalyst B1 is subjected to ion exchange treatment. The specific operation is as follows: Add 10 g of composite resin catalyst B1, 20.6 g of sodium bromide, 150 mL of deionized water and 50 mL of ethanol to a 300 mL beaker. Stir at 45 °C for 12 hours to carry out ion exchange. Filter the solution and repeat the ion exchange 3 times. After the ion exchange is completed, filter and wash the solution and dry it at 90 °C for 12 hours to obtain composite resin catalyst B2.

[0052] Example 3-1 This embodiment provides a composite resin catalyst for the synthesis of ethylene carbonate. The specific implementation method is the same as that in Example 1-1, except that 7.3 g of triethylamine in S2 is replaced with 16.2 g of tri-n-pentylamine to obtain composite resin catalyst C1.

[0053] Example 3-2 This embodiment provides a composite resin catalyst for the synthesis of ethylene carbonate. The specific implementation method is the same as that in Example 3-1, except that the composite resin catalyst C1 is subjected to ion exchange treatment. The specific operation is as follows: Add 10 g of composite resin catalyst C1, 20.6 g of sodium bromide, 150 mL of deionized water and 50 mL of ethanol to a 300 mL beaker. Stir at 45 °C for 12 hours to carry out ion exchange. Filter the solution and repeat the ion exchange 3 times. After the ion exchange is completed, filter and wash the solution and dry it at 90 °C for 12 hours to obtain composite resin catalyst C2.

[0054] Example 4

[0055] This embodiment provides a composite resin catalyst for the synthesis of ethylene carbonate. The specific implementation method is the same as that in Example 1-1, except that 7.3 g of triethylamine in S2 is replaced with 15.0 g of triphenylphosphine to obtain composite resin catalyst D.

[0056] Example 5

[0057] This embodiment provides a composite resin catalyst for the synthesis of ethylene carbonate. The specific implementation method is the same as that in Example 1-1, except that 7.3 g of triethylamine in S2 is replaced with 7.1 g of butylimidazole to obtain composite resin catalyst E.

[0058] Comparative Example 1-1 This comparative example provides a composite resin catalyst for the synthesis of ethylene carbonate, and the preparation method includes: S1: The carrier is a commercially available product. The chloromethylated polystyrene resin carrier was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with the following information: Cl content 1.0~1.24 mmol / g, 50-100 mesh, 1% DVB, CAS: 55844-94-5. This carrier is named R2 in this invention. The batch used in this invention has a Cl content of 1.23 mmol / g, calculated to be 4.4 wt%, and a crosslinking degree of 1% DVB, summarized in Table 1. Fifty particles were randomly sampled, and the average particle size of the carrier was measured and statistically analyzed to be 0.72 mm, as shown in Table 2.

[0059] S2: Preparation of composite resin catalyst, the specific implementation method is the same as S2 in Example 1-1, except that R2 is used to replace R1 to obtain composite resin catalyst F1.

[0060] Comparative Examples 1-2 The specific implementation method of this comparative example is the same as that of Comparative Example 1-1, except that the composite resin catalyst F1 is subjected to ion exchange treatment. The specific operation is as follows: Add 10 g of composite resin catalyst F1, 20.6 g of sodium bromide, 150 mL of deionized water and 50 mL of ethanol to a 300 mL beaker. Stir at 45 °C for 12 hours to carry out ion exchange. Filter the solution and repeat the ion exchange 3 times. After the ion exchange is completed, filter and wash, and dry at 90 °C for 12 hours to obtain composite resin catalyst F2.

[0061] Comparative Example 2-1 This comparative example provides a composite resin catalyst for the synthesis of ethylene carbonate, and the preparation method includes: S1: Use commercially available R2; S2: The specific implementation method is the same as S2 in Comparative Example 1-1, except that 7.3 g of triethylamine in S2 is replaced with 10.2 g of tri-n-propylamine to obtain composite resin catalyst G1.

[0062] Comparative Example 2-2 The specific implementation method of this comparative example is the same as that of comparative example 2-1, except that the composite resin catalyst G1 is subjected to ion exchange treatment. The specific operation is as follows: Add 10 g of composite resin catalyst G1, 20.6 g of sodium bromide, 150 mL of deionized water and 50 mL of ethanol to a 300 mL beaker. Stir at 45 °C for 12 hours to carry out ion exchange. Filter the solution and repeat the ion exchange 3 times. After the ion exchange is completed, filter and wash, and dry at 90 °C for 12 hours to obtain composite resin catalyst G2.

[0063] Comparative Example 3 This comparative example provides a composite resin catalyst for the synthesis of ethylene carbonate, and the preparation method includes: S1: Preparation of chloromethylated polystyrene crosslinked resin carrier containing carbon nanotubes: In a 500 mL three-necked flask, add 25.4 g styrene, 30.3 g 4-vinylbenzyl chloride, 3.7 g divinylbenzene (crosslinking degree DVB 6.2%), 13.0 g toluene, and 0.3 g azobisisobutyronitrile initiator. Stir at room temperature for 15 minutes, then add 0.3 g carbon nanotubes (Shandong Dazhan Nanomaterials Co., Ltd., model GT-300, particle size D50 < 15 μm), and continue stirring for 15 minutes. Add 130 mL of deionized water containing 0.4 g 2-hydroxyethyl cellulose, 0.3 g sodium polyphosphate, 5.0 g gelatin, and 18.9 g glycerol. Adjust the stirring speed and stir at 60 °C for 2 hours; then gradually increase the temperature to 80 °C and react for 4 hours; finally, increase the temperature to 90 °C and react for 12 hours. After the reaction was completed, the supernatant was poured off, washed three times with 85°C hot water and ethanol, then filtered, dried in an oven at 85°C, sieved, and the chloromethylated polystyrene crosslinked resin carrier R3 in the range of 10~18 mesh was collected.

[0064] S2: Preparation of composite resin catalyst: A 250 mL three-necked flask was evacuated and purged with nitrogen. 10 g of chloromethylated polystyrene crosslinked resin carrier R3 and 120 mL of N,N-dimethylformamide were added. The mixture was stirred and swollen at 60 °C for 8 hours. After swelling, 15.0 g of triphenylphosphine was added under a nitrogen atmosphere, and the mixture was heated to 90 °C and reacted for 16 hours. The solution was filtered off, washed three times with 75 mL each of tetrahydrofuran, methanol, and deionized water, and dried at 90 °C for 12 hours to obtain the composite resin catalyst H.

[0065] Comparative Example 4 The specific implementation method of this comparative example is the same as that of comparative example 3, except that 11.8 g of (3-chloropropyl)-dibutylamine is used to replace 15.0 g of triphenylphosphine to obtain composite resin catalyst I.

[0066] Comparative Example 5 The specific implementation method of this comparative example is the same as that of comparative example 3, except that 17.4 g of tri-p-tolylphosphine is used to replace 15.0 g of triphenylphosphine to obtain composite resin catalyst J.

[0067] Performance testing The supports and catalysts obtained in the above examples and comparative examples were subjected to the following tests, and the results are shown in Tables 1-3.

[0068] 1. The chlorine, bromine, phosphorus, and nitrogen contents were obtained through XRF testing. The loading of active sites on the catalyst can be determined by measuring these elements, and the results are summarized in Table 1. Table 1 shows that the initial chlorine content of the support in this invention is high, resulting in an increased loading of active sites on the catalyst. The initial particle size of the support, the particle size of the prepared catalyst, and the particle size of the catalyst after use were measured. These changes allow for the assessment of the swelling performance of the support and catalyst, and the results are summarized in Table 2. The data in Table 2 unexpectedly revealed that the catalyst particle size of this invention shrinks after the reaction, while no particle size shrinkage was observed in the comparative example.

[0069] 2. The results of the high-pressure reactor method for synthesizing ethylene carbonate and propylene carbonate are summarized in Table 3: (1) After adding 2.0 g of catalyst to the high-pressure reactor and sealing it, and after passing the airtightness test, the gas inside the reactor was replaced 5 times with 1.0 MPa carbon dioxide. The reactor body was cooled to below 5°C. 20.0 g of ethylene oxide (EO) was added to the reactor using a pre-cooled stainless steel syringe. 1.0 MPa carbon dioxide was introduced by opening the gas inlet valve. The reactor was stirred, the reaction temperature was set and raised to 120°C, and carbon dioxide was introduced to maintain the pressure at 4.0 MPa. After reacting for 2 hours, the reactor body was cooled to below 50°C. The gas in the reactor was released to atmospheric pressure, and the residual ethylene oxide vapor inside the reactor was purged 3 times with 1.0 MPa carbon dioxide. The reactor was opened, the product liquid was filtered and collected using a sintered glass funnel, and the mass was weighed. The catalyst, reactor and stirrer were washed with anhydrous ethanol. The washing liquid was quantitatively measured in a 100 mL volumetric flask. The concentration of the product and by-product was analyzed by gas chromatography, and the conversion rate of ethylene oxide and the selectivity of ethylene carbonate were calculated.

[0070] (2) Catalyst A2 was used to catalyze the reaction of propylene oxide (PO) and carbon dioxide to synthesize propylene carbonate. The reaction conditions and test conditions in the high-pressure reactor were the same as in (1), and this was recorded as Experiment 1.

[0071] (3) Catalyst E was used to catalyze the reaction of propylene oxide and carbon dioxide to synthesize propylene carbonate. The reaction conditions and test conditions of the high-pressure reactor were the same as those in (1), and this was recorded as Experiment 2.

[0072] 3. Fixed-bed continuous flow synthesis of ethylene carbonate: Quartz wool, 2.0 g of catalyst, and quartz wool are sequentially loaded into a fixed-bed reactor, with the catalyst fixed in the middle of the reactor. The reaction tube is then tightened and secured in the heating furnace. After confirming good airtightness, the air in the reactor pipeline is purged. The flow rates of carbon dioxide, ethylene carbonate pump, and ethylene oxide pump are set. The ethylene oxide storage tank is kept cold at -5℃ and sealed with 0.5 MPa nitrogen, while the ethylene carbonate storage tank is kept at 80℃. The pressure is controlled at 4.0 MPa by the back pressure valve downstream of the reactor. The reactor temperature is raised to 140℃ at an EO space velocity of 0.76 h⁻¹. -1 The reaction was carried out under conditions where the CO2 / EO feed mass ratio was 1.2; EC was used as a diluent in the reaction, and the EC / EO feed mass ratio was 2:1. Timing began after the EO feed pump pressure reached the reactor pressure. After 4-6 hours of reaction stabilization, samples of tail gas and liquid products were taken at different time points, and the concentrations of products and byproducts were analyzed by gas chromatography to calculate the ethylene oxide conversion rate and ethylene carbonate selectivity. The continuous reaction time was 24-350 hours. When catalyst E was used, the EO space velocity decreased to 0.5 h⁻¹ after 200 hours. -1 With all other conditions remaining unchanged, the conversion rate of ethylene oxide catalyzed by different catalysts over time is shown in the figure. Figure 1 As shown.

[0073] Table 1. Crosslinking degree and elemental analysis results of the support and catalyst (elemental content is by mass fraction).

[0074] Table 2 Changes in support particle size and catalyst particle size before and after reaction

[0075] Table 3. Results of Cyclic Carbonate Synthesis (High-Pressure Reactor)

[0076] As shown in Table 3, the catalyst of the present invention has excellent performance, good conversion rate of epoxides and high selectivity of cyclic carbonates. Figure 1 It can be seen that the stability of the catalyst of the present invention is better than that of the comparative example.

[0077] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0078] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A method for preparing a composite resin catalyst for the synthesis of cyclic carbonates, characterized in that, Includes the following steps: S1. Preparation of the carrier: The monomer, comonomer and initiator are mixed in a container to obtain an oily mixed solution; the aqueous solution of the auxiliary agent is added to the oily mixed solution, and the reaction is carried out by gradient heating. The solid obtained from the reaction is washed and dried to obtain the carrier. S2. Preparation of composite resin catalyst: After the support is mixed with the swelling solvent and swollen, the active component is added to carry out the immobilized reaction. The solid after the reaction is washed and dried to obtain the composite resin catalyst. The monomer is selected from at least one of 4-vinylbenzyl chloride, methyl methacrylate, styrene, and 4-butylstyrene; The comonomer is selected from at least one of diallylbenzene, methylenebisacrylamide, and divinylbenzene; The additives are selected from at least one of polyvinyl alcohol, starch, gelatin, sodium polyphosphate, methylcellulose, and 2-hydroxyethylcellulose; The swelling solvent is selected from at least one of N,N-dimethylformamide, toluene, mesitylene, ethanol, and acetonitrile; The active ingredient is selected from at least one of organic amines, organophosphorus compounds, and alkylimidazolium compounds.

2. The preparation method according to claim 1, characterized in that, The specific steps of the gradient heating reaction in S1 are as follows: react at 60~70℃ for 0.5~4 hours, heat to 70~90℃ for 2~8 hours, and heat to 90~95℃ for 8~16 hours.

3. The preparation method according to claim 1, characterized in that, In the total weight of monomers, comonomers, initiators, and auxiliaries in S1, the weight percentage of monomers is 85% to 95%; the weight percentage of comonomers is 5% to 10%; the weight percentage of initiators is 0.1% to 10%; and the weight percentage of auxiliaries is 1% to 20%.

4. The preparation method according to claim 1, characterized in that, The chlorine content of the carrier is 15%~20%, and the degree of crosslinking is 7%~10%.

5. The preparation method according to claim 1, characterized in that, The organic amine, organophosphine, and alkylimidazolium are selected from any one or more of tertiary amines, tertiary phosphines, N-alkylimidazolium, aminopyridine, aminopiperazine, and aminotriazole.

6. The preparation method according to claim 1, characterized in that, The composite resin catalyst obtained in S2 can also undergo halide ion exchange.

7. The preparation method according to claim 6, characterized in that, The metal halide used for halide ion exchange includes at least one of NaBr, KBr, NaI, KI, MgBr2, MgI2, CaBr2, CaI2, BaBr2, or BaI2.

8. A composite resin catalyst for the synthesis of cyclic carbonates, obtained by the preparation method according to any one of claims 1-7.

9. An application of the composite resin catalyst according to claim 8, characterized in that, Used in the synthesis of cyclic carbonates.

10. A method for synthesizing a cyclic carbonate, characterized in that, The synthesis method includes: using the composite resin catalyst of claim 8 to catalyze the synthesis of cyclic carbonates from carbon dioxide and epoxides.

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