Quaternary ammonium salt coordination bimetallic catalysts, their preparation methods and applications

Abstract

This invention relates to the field of catalyst technology, disclosing a quaternary ammonium salt coordination bimetallic catalyst, its preparation method, and its applications. The preparation method of the quaternary ammonium salt coordination bimetallic catalyst includes reacting a solution containing a potassium polycyanometalate and a terminal hydroxyl-terminated quaternary ammonium salt ligand with a metal salt solution to obtain the quaternary ammonium salt coordination bimetallic catalyst. This invention uses a terminal hydroxyl-terminated quaternary ammonium salt as the ligand, directly preparing the quaternary ammonium salt coordination bimetallic catalyst while synthesizing the bimetallic catalyst. The preparation process of this invention is simple, and the obtained quaternary ammonium salt coordination bimetallic catalyst can be directly recycled after filtration. The quaternary ammonium salt coordination bimetallic catalyst obtained by this invention can be used to synthesize carbon dioxide-based cyclic carbonates, exhibiting high catalytic efficiency, high selectivity, and a certain degree of water tolerance. The conversion rate of epoxides can reach over 99%, and the selectivity can reach over 99%.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to quaternary ammonium salt coordination bimetallic catalysts, their preparation methods, and applications. Background Technology

[0002] Cyclic carbonates are widely used in pesticides, pharmaceuticals, resins, dyes, coatings, electronic chemicals, food additives, and solvents. They are important fine chemical intermediates and high-performance organic solvents. The catalytic reaction of carbon dioxide with epoxides to synthesize cyclic carbonates is a low-pollution, environmentally friendly, and highly atom-utilizing technical route.

[0003] Currently, catalysts for the cycloaddition reaction of epoxides with CO2 are mainly classified into homogeneous and heterogeneous catalysts. Homogeneous catalysts mainly include quaternary ammonium salts, phosphine salts, alkali metal halides, ionic liquids, salon complexes, and metalloporphyrins. Heterogeneous catalysts mainly include metal oxides, zeolites, and polymer-supported ammonium salts. Although these catalysts can effectively catalyze the cycloaddition reaction of CO2 with epoxides, they suffer from drawbacks such as low catalytic activity, sensitivity of the catalytic system to water, complex preparation processes, and difficulty in separating the catalyst from the product.

[0004] CN102580780A discloses a method for catalyzing the cycloaddition reaction of epoxides and CO2 by physically mixing a bimetallic cyanide complex with a quaternary ammonium salt as a two-component bimetallic catalyst. This method exhibits high catalytic efficiency and selectivity, and the reaction system is compatible with small amounts of water. However, the quaternary ammonium salt component is easily lost and cannot be recycled. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of easy loss and inability to recycle existing quaternary ammonium salt components, and to provide a quaternary ammonium salt coordination bimetallic catalyst, its preparation method and application. The preparation process of this catalyst is simple, and a quaternary ammonium salt-containing bimetallic catalyst can be directly synthesized during the preparation of bimetallic catalysts. It can efficiently catalyze the cycloaddition reaction of CO2 and epoxides in a short time with a selectivity of >99%, and is not sensitive to water. At the same time, the bicomponent catalyst can be directly recycled and reused after filtration.

[0006] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a quaternary ammonium salt coordination bimetallic catalyst, the method comprising: reacting a solution containing a potassium polycyanometalate and a terminal hydroxyl quaternary ammonium salt ligand with a metal salt solution to obtain a quaternary ammonium salt coordination bimetallic catalyst.

[0007] A second aspect of the present invention provides a quaternary ammonium salt coordination bimetallic catalyst, wherein the catalyst is prepared by the preparation method described in the first aspect.

[0008] The third aspect of this invention provides the application of the quaternary ammonium salt coordination bimetallic catalyst described in the second aspect in the synthesis of cyclic carbonates from carbon dioxide.

[0009] The fourth aspect of the present invention provides a method for synthesizing cyclic carbonates from carbon dioxide, the method comprising: reacting an epoxide with CO2 in the presence of the quaternary ammonium salt coordination bimetallic catalyst described in the second aspect to obtain the product cyclic carbonate;

[0010] Preferably, the molar ratio of the quaternary ammonium salt coordination bimetallic catalyst to the epoxide is 1:100-1:3000.

[0011] The technical effects achieved by the present invention through the above technical solution are as follows:

[0012] (1) This invention uses terminal hydroxyl quaternary ammonium salts as ligands to directly prepare quaternary ammonium salt coordination bimetallic catalysts while synthesizing bimetallic catalysts. The preparation process of this invention is simple, and the obtained quaternary ammonium salt coordination bimetallic catalysts can be directly recycled after filtration. It has been verified that after being recycled and reused 5 times, the catalytic activity is almost unaffected.

[0013] (2) The quaternary ammonium salt coordination bimetallic catalyst obtained in this invention can be used to synthesize carbon dioxide-based cyclic carbonates. It can efficiently catalyze the cycloaddition reaction of CO2 and epoxides in a short time. It has high catalytic efficiency, high selectivity, and certain tolerance to water. The conversion rate of epoxides can reach more than 99%, and the selectivity can reach more than 99%. Attached Figure Description

[0014] Figure 1 The infrared spectrum of the catalyst obtained in Example 1 is shown below.

[0015] Figure 2 The hydrogen NMR spectrum of the product obtained in Application Example 1;

[0016] Figure 3 The image shows the hydrogen NMR spectrum of the product obtained in Application Example 3. Detailed Implementation

[0017] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0018] The first aspect of the present invention provides a method for preparing a quaternary ammonium salt coordination bimetallic catalyst, the method comprising: reacting a solution containing a potassium polycyanometalate and a terminal hydroxyl quaternary ammonium salt ligand with a metal salt solution to obtain a quaternary ammonium salt coordination bimetallic catalyst.

[0019] This invention uses a hydroxyl-terminated quaternary ammonium salt as a ligand, coordinating the quaternary ammonium salt within a metal catalyst. The terminal hydroxyl group can replace water-soluble polymers as ligands and also promotes the reaction between CO2 and epoxides. Furthermore, the quaternary ammonium salt does not dissolve in the reaction solution during the catalytic process; after filtration, it can be recovered and reused along with the metal catalyst. Verification has shown that after five cycles of recovery and reuse, there is almost no loss of catalytic activity. This results in reagent savings, accelerated reaction, and catalyst recycling.

[0020] This invention coordinates quaternary ammonium salts in a metal catalyst to further enhance its catalytic effect; the metal catalyst is preferably a bimetallic catalyst, which can efficiently catalyze the cycloaddition reaction between CO2 and epoxide.

[0021] The preparation process of this invention is simple. Using terminal hydroxyl quaternary ammonium salts as ligands, quaternary ammonium salt coordination bimetallic catalysts are directly prepared simultaneously with the synthesis of bimetallic catalysts. The synthesis of terminal hydroxyl quaternary ammonium salts is simple, the synthesized catalysts have high activity, and they can be recycled and reused repeatedly without changing their activity.

[0022] In some embodiments, the general formula of the terminal hydroxyl quaternary ammonium salt ligand is Formula I:

[0023]

[0024] In Formula I, X is selected from halogens, and n = 1-10;

[0025] Preferably, X is selected from chlorine, bromine or iodine, and n = 1-8.

[0026] In some preferred embodiments, the terminal hydroxyl quaternary ammonium salt ligand is selected from the terminal hydroxyl quaternary ammonium salts represented by Formula 1, Formula 2, or Formula 3:

[0027]

[0028] In some preferred embodiments, the molar ratio of the polycyanometallic potassium salt and the terminal hydroxyl quaternary ammonium salt ligand is 1:1-10, preferably 1:1-5.

[0029] In some preferred embodiments, the molar ratio of the polycyanometallic potassium salt to the metal salt solution is 1:3-20.

[0030] In some preferred embodiments, the solution containing potassium polycyanate and terminal hydroxyl quaternary ammonium salt ligands has a mass concentration of 1-50% for the potassium polycyanate.

[0031] In some preferred embodiments, the solution containing a potassium polycyanometalate and a terminal hydroxyl quaternary ammonium salt ligand has a mass concentration of 1-50%.

[0032] Furthermore, the polycyanometallic potassium salt is selected from potassium hexacyanocobaltate, potassium hexacyanoferrate, potassium tetracyanonitrile, potassium tetracyancadmium cadmium cyanate, potassium monobromopentanocyanocobaltate, potassium mononitropentanocyanocobalt complex, or potassium monoazidopentanocyanocobaltate.

[0033] Furthermore, the metal salt is selected from metal halides, nitrates, phosphates, or sulfates.

[0034] Furthermore, the metal is selected from zinc, cobalt, or cadmium.

[0035] Furthermore, the mass concentration of the metal salt solution is 1-60%.

[0036] It should be noted that the catalyst of the present invention is a bimetallic catalyst. Therefore, the metal in the potassium polycyanometalate salt is different from the metal in the metal salt. For example, when the potassium polycyanometalate salt is selected from potassium hexacyanocobaltate, the metal in the metal salt is selected from zinc or cadmium, but cannot be selected from cobalt; when the potassium polycyanometalate salt is selected from potassium hexacyanoferrate, the metal in the metal salt can be selected from zinc, cobalt or cadmium.

[0037] In some embodiments, the reaction temperature is 0-100°C, preferably 25-80°C; and the time is 0.5-72h, preferably 3-24h.

[0038] A second aspect of the present invention provides a quaternary ammonium salt coordination bimetallic catalyst, wherein the catalyst is prepared by the preparation method described above.

[0039] A third aspect of the present invention provides the application of the aforementioned quaternary ammonium salt coordination bimetallic catalyst in the synthesis of cyclic carbonates from carbon dioxide.

[0040] A fourth aspect of the present invention provides a method for synthesizing cyclic carbonates from carbon dioxide, the method comprising: reacting an epoxide with CO2 in the presence of the aforementioned quaternary ammonium salt coordination bimetallic catalyst to obtain the product cyclic carbonate.

[0041] In some embodiments, the molar ratio of the quaternary ammonium salt coordination bimetallic catalyst to the epoxide is 1:100-1:3000, for example 1:200, 1:300, 1:500, 1:800, 1:1000, 1:1500, 1:2000, 1:2500, and any value within the range of any two values.

[0042] In some embodiments, the synthesis reaction is carried out at a temperature of 50-120°C, a pressure of 0.1-6 MPa, and a time of 0.5-24 h.

[0043] The catalyst of this invention is water-resistant; therefore, water can be included in the synthesis reaction system, meaning that the catalyst still exhibits high catalytic activity in the presence of a certain amount of water. In some embodiments, the mass percentage of water during the synthesis reaction is less than 20%; for example, 0.1%, 0.5%, 1%, 3%, 4%, 5%, 9%, 10%, 15%, 16%, 18%, and any value within the range of any two of these values, preferably 1-5%.

[0044] In some embodiments, the epoxide is selected from at least one of ethylene oxide, propylene oxide, epichlorohydrin, allyl glycidyl ether, cyclohexene oxide, 4-vinylcyclohexene oxide, styrene oxide, and alkyl-substituted styrene oxide.

[0045] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the following description.

[0046] Unless otherwise specified, the following examples and comparative examples were conducted under standard conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are commercially available products.

[0047] In the following examples and comparative examples, the structures of terminal hydroxyl quaternary ammonium salt 1, terminal hydroxyl quaternary ammonium salt 2, and terminal hydroxyl quaternary ammonium salt 3 are shown below:

[0048] Terminal quaternary ammonium salt:

[0049]

[0050] The preparation method of hydroxyl-terminated quaternary ammonium salt 1 includes the following steps: 0.1 mol of triethylamine is weighed into a flask, and 10 ml of 2 mol / L hydrochloric acid is slowly added dropwise; after the addition is completed, 0.2 mol of ethylene oxide is slowly added dropwise, and then the temperature is raised to 80℃ and the reaction is carried out for 20 min; after the reaction is completed, the product is dried at 100℃ for 24 h to obtain hydroxyl-terminated quaternary ammonium salt 1.

[0051] The preparation method of hydroxyl-terminated quaternary ammonium salt 2 includes the following steps: 0.1 mol of tributylamine is weighed into a flask, and 10 ml of 2 mol / L hydrobromic acid is slowly added dropwise; after the addition is completed, 0.2 mol of ethylene oxide is slowly added dropwise, and then the temperature is raised to 80℃ and the reaction is carried out for 20 min; after the reaction is completed, the product is dried at 100℃ for 24 h to obtain hydroxyl-terminated quaternary ammonium salt 2.

[0052] The preparation method of hydroxyl-terminated quaternary ammonium salt 3 includes the following steps: 0.1 mol of trioctylamine is weighed into a flask, and 10 ml of 2 mol / L hydroiodic acid is slowly added dropwise; after the addition is completed, 0.2 mol of ethylene oxide is slowly added dropwise, and then the temperature is raised to 80℃ and the reaction is carried out for 20 min; after the reaction is completed, the product is dried at 100℃ for 24 h to obtain hydroxyl-terminated quaternary ammonium salt 3.

[0053] Example 1

[0054] Dissolve 1.0 g potassium hexacyanocobalaminate in 50 ml of deionized water, add 2.0 g of terminal hydroxyl quaternary ammonium salt 1, stir until completely dissolved, and then add dropwise to 10 mL of aqueous solution containing 5.0 g zinc chloride. Stir at 25 °C for 2 h, and then obtain the catalyst after filtration and vacuum drying.

[0055] The catalyst was subjected to elemental analysis using an Agilent 720ES inductively coupled plasma atomic emission spectrometer (ICP). The results were: Co: 1.50, Zn: 3.45.

[0056] The obtained catalyst was analyzed using a Bruker TENSOR 27 infrared spectrometer, and the results were as follows: Figure 1 The infrared spectrum shown is for wavelengths of 2200 cm⁻¹. -1 The peaks shown represent characteristic peaks of the cyano group in the bimetallic cyanide moiety of the catalyst. Additionally, the wavelengths shown in the figure are 2900 and 1120 cm⁻¹. -1 The two peaks at the specified position represent the characteristic peaks of the CH and CN bonds in the terminal hydroxyl quaternary ammonium salt group of the catalyst, respectively. This proves the successful synthesis of the catalyst.

[0057] Example 2

[0058] Dissolve 5.0 g potassium tetracyanide nickelate in 50 mL of deionized water, add 10.0 g of terminal hydroxyl quaternary ammonium salt 1, stir until completely dissolved, and then add dropwise to 40 mL of aqueous solution containing 15.0 g zinc chloride. Stir at 50 °C for 48 h, and then obtain the catalyst after filtration and vacuum drying.

[0059] The catalyst was subjected to elemental analysis using an Agilent 720ES inductively coupled plasma atomic emission spectrometer (ICP). The elemental analysis results were: Ni: 2.31, Zn: 4.25.

[0060] Example 3

[0061] Dissolve 7.0 g of potassium bromopentacyanocobaltate in 40 mL of deionized water, add 15.0 g of terminal hydroxyl quaternary ammonium salt 1, stir until completely dissolved, and then add dropwise to 40 mL of aqueous solution containing 18.0 g of zinc chloride. Stir at 80 °C for 72 h, and then obtain the catalyst after filtration and vacuum drying.

[0062] The catalyst was subjected to elemental analysis using an Agilent 720ES inductively coupled plasma atomic emission spectrometer (ICP). The results were: Co: 2.11, Zn: 3.16.

[0063] Example 4

[0064] Dissolve 1.0 g potassium hexacyanocobalaminate in 50 ml of deionized water, add 2.0 g of terminal hydroxyl quaternary ammonium salt 2, stir until completely dissolved, and then add dropwise to 10 ml of aqueous solution containing 5.0 g zinc chloride. Stir at 25 °C for 2 h, and then obtain the catalyst after filtration and vacuum drying.

[0065] The catalyst was subjected to elemental analysis using an Agilent 720ES inductively coupled plasma atomic emission spectrometer (ICP). The results were: Co: 1.61, Zn: 3.23.

[0066] Example 5

[0067] Dissolve 1.0 g potassium hexacyanocobalaminate in 50 ml of deionized water, add 2.0 g of terminal hydroxyl quaternary ammonium salt 3, stir until completely dissolved, and then add dropwise to 10 ml of aqueous solution containing 5.0 g zinc chloride. Stir at 25 °C for 2 h, and then obtain the catalyst after filtration and vacuum drying.

[0068] The catalyst was subjected to elemental analysis using an Agilent 720ES inductively coupled plasma atomic emission spectrometer (ICP). The results were: Co: 1.87, Zn: 3.15.

[0069] Example 6

[0070] Dissolve 1.0 g potassium hexacyanocobalaminate in 50 ml of deionized water, add 2.0 g of terminal hydroxyl quaternary ammonium salt 1, stir until completely dissolved, and then add dropwise to 10 ml of aqueous solution containing 5.0 g zinc nitrate. Stir at 25 °C for 2 h, and then obtain the catalyst after filtration and vacuum drying.

[0071] The catalyst was subjected to elemental analysis using an Agilent 720ES inductively coupled plasma atomic emission spectrometer (ICP). The elemental analysis results were: Co: 1.32, Zn: 3.56.

[0072] Example 7

[0073] Dissolve 1.0 g potassium hexacyanocobalaminate in 50 ml of deionized water, add 2.0 g of terminal hydroxyl quaternary ammonium salt 1, stir until completely dissolved, and then add dropwise to 10 ml of aqueous solution containing 5.0 g zinc sulfate. Stir at 25 °C for 2 h, and then obtain the catalyst after filtration and vacuum drying.

[0074] The catalyst was subjected to elemental analysis using an Agilent 720ES inductively coupled plasma atomic emission spectrometer (ICP). The elemental analysis results were: Co: 1.76, Zn: 3.47.

[0075] Comparative Example 1

[0076] Dissolve 1.0 g potassium hexacyanocobalaminate in 50 ml of deionized water, then add 2.0 g tert-butanol and stir until completely dissolved. Then add it dropwise to 10 mL of aqueous solution containing 5.0 g zinc chloride. Stir at 25 °C for 2 h. After filtration, multiple washings, and vacuum drying, mix with terminal hydroxyl quaternary ammonium salt 1 in a 1:1 ratio to obtain the catalyst.

[0077] The catalyst was subjected to elemental analysis using an Agilent 720ES inductively coupled plasma atomic emission spectrometer (ICP). The elemental analysis results were: Co: 1.38, Zn: 3.39.

[0078] Application Example 1

[0079] (1) Heat a 100ml high-pressure polymerization reactor to 120℃ and vacuum dry for 1h to remove residual moisture from the reactor;

[0080] (2) Add 0.1g of the catalyst from Example 1 to the high-pressure polymerization reactor in step (1), continue vacuum drying, and cool down to room temperature. Then add 30mL of purified epichlorohydrin and maintain a certain pressure of CO2. Heat to 120°C, turn on the stirrer, adjust the pressure to 5.0MPa, react for 12h, cool down quickly, release the remaining CO2, and filter to remove the catalyst.

[0081] (3) The reaction solution obtained in step (2) was subjected to nuclear magnetic resonance and gas chromatography-mass spectrometry to determine the yield and selectivity of the reaction. The test results are shown in Table 1. The remaining reaction solution was rotary evaporated to remove unreacted monomers. The final product obtained was chloromethyldioxacyclophenone.

[0082] The collected products were tested using a Bruker Avance 400 instrument to obtain... Figure 2 The 1H NMR spectrum shown is as follows: 1¹H NMR (400MHz, Chloroform-d) δ 4.97 (dtd, J = 8.2, 5.6, 3.8 Hz, 1H), 4.58 (t, J = 8.6 Hz, 1H), 4.40 (dd, J = 8.9, 5.7 Hz, 1H), 3.75 (qd, J = 12.1, 4.7 Hz, 2H); the product was confirmed to be chloromethyldioxacyclophenone.

[0083] Application Example 2

[0084] (1) Heat a 100ml high-pressure polymerization reactor to 80℃ and vacuum dry for 1h to remove residual moisture in the reactor;

[0085] (2) Add 0.1g of the catalyst from Example 1 to the high-pressure polymerization reactor in step (1), continue vacuum drying, and cool down to room temperature. Then add 30ml of purified epichlorohydrin and maintain a certain pressure of CO2. Heat up to 120°C, turn on the stirrer, adjust the pressure to 3.0MPa, react for 24h, cool down rapidly, release the remaining CO2, and filter to remove the catalyst.

[0086] (3) The reaction solution obtained in step (2) was subjected to nuclear magnetic resonance and gas chromatography-mass spectrometry to determine the yield and selectivity of the reaction. The test results are shown in Table 1. The remaining reaction solution was rotary evaporated to remove unreacted monomers. The final product obtained was chloromethyldioxacyclophenone.

[0087] Application Example 3

[0088] (1) Heat a 100ml high-pressure polymerization reactor to 50℃ and vacuum dry for 1h to remove residual moisture in the reactor;

[0089] (2) Add 0.1g of the catalyst from Example 1 to the high-pressure reactor of polymerization in step (1), continue vacuum drying, and cool down to room temperature. Then add 30ml of purified styrene oxide and maintain a certain pressure of CO2. Heat up to 120°C, turn on the stirrer, adjust the pressure to 1.0MPa, react for 4 hours, cool down quickly, release the remaining CO2, and filter to remove the catalyst.

[0090] (3) The reaction solution obtained in step (2) was subjected to nuclear magnetic resonance and gas chromatography-mass spectrometry to determine the reaction yield and selectivity. The test results are shown in Table 1. The remaining reaction solution was rotary evaporated to remove unreacted monomers, and the final product obtained was styrene carbonate.

[0091] The collected products were tested using a Bruker Avance 400 instrument to obtain... Figure 3 The 1H NMR spectrum shown is as follows: 1¹H NMR (400MHz, Chloroform-d) δ 7.50–7.31 (m, 5H), 5.68 (t, J = 8.0 Hz, 1H), 4.80 (t, J = 8.4 Hz, 1H), 4.34 (t, J = 8.3 Hz, 1H); the product was confirmed to be styrene carbonate.

[0092] Application Example 4

[0093] (1) Heat a 100ml high-pressure polymerization reactor to 120℃ and vacuum dry for 1h to remove residual moisture from the reactor;

[0094] (2) Add 0.1g of the catalyst from Example 2 to the high-pressure polymerization reactor in step (1), continue vacuum drying, and cool down to room temperature. Then add 30ml of purified epichlorohydrin and maintain a certain pressure of CO2. Heat to 120°C, turn on the stirrer, adjust the pressure to 5.0MPa, react for 12 hours, cool down quickly, release the remaining CO2, and filter to remove the catalyst.

[0095] (3) The reaction solution obtained in step (2) was subjected to nuclear magnetic resonance and gas chromatography-mass spectrometry to determine the yield and selectivity of the reaction. The test results are shown in Table 1. The remaining reaction solution was rotary evaporated to remove unreacted monomers, and the final product obtained was chloromethyldioxacyclophenone.

[0096] Application Example 5

[0097] (1) Heat a 100ml high-pressure polymerization reactor to 120℃ and vacuum dry for 1h to remove residual moisture from the reactor;

[0098] (2) Add 0.1g of the catalyst from Example 3 to the high-pressure polymerization reactor in step (1), continue vacuum drying, and cool down to room temperature. Then add 30ml of purified epichlorohydrin and maintain a certain pressure of CO2. Heat to 120°C, turn on the stirrer, adjust the pressure to 5.0MPa, react for 12 hours, cool down quickly, release the remaining CO2, and filter to remove the catalyst.

[0099] (3) The reaction solution obtained in step (2) was subjected to nuclear magnetic resonance and gas chromatography-mass spectrometry to determine the yield and selectivity of the reaction. The test results are shown in Table 1. The remaining reaction solution was rotary evaporated to remove unreacted monomers, and the final product obtained was chloromethyldioxacyclophenone.

[0100] Application Example 6

[0101] (1) Heat a 100ml high-pressure polymerization reactor to 120℃ and vacuum dry for 1h to remove residual moisture from the reactor;

[0102] (2) Add 0.1g of the catalyst from Example 1 to the high-pressure polymerization reactor in step (1), continue vacuum drying, and cool down to room temperature. Then add 30ml of purified epichlorohydrin and 0.1ml of deionized water, maintain a certain pressure of CO2, raise the temperature to 120°C, turn on the stirrer, adjust the pressure to 5.0MPa, react for 12h, cool down rapidly, release the remaining CO2, and filter to remove the catalyst.

[0103] (3) The reaction solution obtained in step (2) was subjected to nuclear magnetic resonance and gas chromatography-mass spectrometry to determine the yield and selectivity of the reaction. The test results are shown in Table 1. The remaining reaction solution was rotary evaporated to remove unreacted monomers, and the final product obtained was chloromethyldioxacyclophenone.

[0104] Application Example 7

[0105] The catalyst recovered by filtration in Example 8 was subjected to a recycling experiment. The catalyst obtained after filtration was washed three times with ethyl acetate, dried overnight under vacuum at 30°C, weighed after complete drying, and the experimental conditions of Example 8 were repeated for a total of 5 times. The test results are shown in Table 2.

[0106] Comparative Application Example 1

[0107] (1) Heat a 100ml high-pressure polymerization reactor to 120℃ and vacuum dry for 1h to remove residual moisture from the reactor;

[0108] (2) Add 0.1 g of catalyst and terminal hydroxyl group from Comparative Example 1 to the high-pressure polymerization reactor in step (1), continue vacuum drying, and cool down to room temperature. Then add 30 mL of purified epichlorohydrin and maintain a certain pressure of CO2. Heat to 120°C, turn on the stirrer, adjust the pressure to 5.0 MPa, react for 12 h, cool down quickly to release the remaining CO2, and filter to remove the catalyst.

[0109] (3) The reaction solution obtained in step (2) was subjected to nuclear magnetic resonance and gas chromatography-mass spectrometry to determine the yield and selectivity of the reaction. The test results are shown in Table 1. The remaining reaction solution was rotary evaporated to remove unreacted monomers. The final product obtained was chloromethyldioxacyclophenone.

[0110] Table 1

[0111] Example number Yield / % Selectivity / % Epoxide conversion rate / % Application Example 1 99 99 99 Application Example 2 95 99 99 Application Example 3 91 99 99 Application Example 4 94 99 99 Application Example 5 96 99 99 Application Example 6 98 99 99 Comparative Application Example 1 92 98 99

[0112] As can be seen from the results in Table 1, the quaternary ammonium salt coordination bimetallic catalyst obtained by the method of the present invention can be used to synthesize carbon dioxide-based cyclic carbonates. The yield of carbon dioxide-based cyclic carbonates can reach more than 91%, the conversion rate of epoxides can reach more than 99%, and the selectivity can reach more than 99%.

[0113] Table 2

[0114] Loop count Weight after recovery / mg Yield / % Selectivity / % 1 98 99 99 2 97 98 99 3 97 97 99 4 95 97 99 5 95 97 99

[0115] As shown in Table 2, the quaternary ammonium salt coordination bimetallic catalyst obtained by the method of this invention can be directly recycled after filtration. Verification showed that after five recycling cycles, the catalytic activity was almost completely unaffected.

[0116] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A process for the preparation of a quaternary ammonium salt ligating bimetallic catalyst, characterized in that, The preparation method comprises: reacting a solution containing a potassium polycyanometallate and a terminal hydroxyl quaternary ammonium salt ligand with a metal salt solution to obtain a quaternary ammonium salt coordination bimetallic catalyst; the potassium polycyanometallate is selected from potassium hexacyanocobaltate, potassium hexacyanoferrate, potassium tetracyanonickelate, potassium tetracyanonickelate, potassium monobromopentacyanocobaltate, potassium mononitropentacyanocobaltate or potassium monoazidopentacyanocobaltate; the metal salt is selected from a halide, nitrate, phosphate or sulfate of a metal; the metal is selected from zinc, cobalt or cadmium; the reaction temperature is 0-100℃, and the reaction time is 0.5-72h; The terminal hydroxyl quaternary ammonium salt ligand has a general formula I: Formula I In formula I, X is selected from halogen, and n is 1-10.

2. The production method according to claim 1, wherein, X is selected from chlorine, bromine or iodine, and n=1-8.

3. The production method according to claim 1 or 2, wherein The terminal hydroxyl quaternary ammonium salt ligand is selected from a terminal hydroxyl quaternary ammonium salt represented by formula 1, a terminal hydroxyl quaternary ammonium salt represented by formula 2 or a terminal hydroxyl quaternary ammonium salt represented by formula 3: 。 4. The production method according to claim 1 or 2, wherein The molar ratio of the potassium polycyanometallate and the terminal hydroxyl quaternary ammonium salt ligand is 1:(1-10); And / or, the molar ratio of the potassium polycyanometallate and the metal salt is 1:(3-20); And / or, in the solution containing the potassium polycyanometallate and the terminal hydroxyl quaternary ammonium salt ligand, the mass concentration of the potassium polycyanometallate is 1-50%; And / or, in the solution containing the potassium polycyanometallate and the terminal hydroxyl quaternary ammonium salt ligand, the mass concentration of the terminal hydroxyl quaternary ammonium salt ligand is 1-50%.

5. The production method according to claim 1, wherein The mass concentration of the metal salt solution is 1-60%.

6. The production method according to claim 1, wherein The reaction temperature is 25-50℃, and the reaction time is 3-12h.

7. A quaternary ammonium salt ligating bimetallic catalyst characterized in that, The catalyst is prepared by the preparation method in any one of claims 1-6.

8. Application of the quaternary ammonium salt coordination bimetallic catalyst in claim 7 in the synthesis of cyclic carbonates from carbon dioxide.

9. A method for synthesizing a cyclic carbonate from carbon dioxide, characterized by, The method comprises: synthesizing an epoxide and CO2 in the presence of the quaternary ammonium salt coordination bimetallic catalyst in claim 7 to obtain a product cyclic carbonate.

10. The method of claim 9, wherein, The molar ratio of the quaternary ammonium salt coordination bimetallic catalyst and the epoxide is 1:100-1:3000.

11. The method of claim 9 or 10, wherein, The synthesis reaction temperature is 50-120℃, the synthesis reaction pressure is 0.1-6MPa, and the synthesis reaction time is 0.5-24h. And / or, the mass percentage of water in the synthesis reaction is less than 20%; And / or, the epoxide is at least one selected from oxirane, oxetane, epichlorohydrin, allyl glycidyl ether, cyclohexene oxide, 4-vinyl cyclohexene oxide, styrene oxide and alkyl-substituted styrene oxide.

12. The method of claim 11, wherein, The mass percentage of water in the synthesis reaction is 1-5%.

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