Ionic liquid catalyst and method for its preparation

Abstract

The application provides an ionic liquid catalyst and a preparation method thereof. The ionic liquid catalyst comprises a quaternary ammonium salt compound and an auxiliary ring-opening agent, wherein the quaternary ammonium salt compound has the following formula (I). The catalyst can effectively catalyze the synthesis reaction of CO2 and PO / EO, the PO conversion rate is high, the PC selectivity is high, and the energy consumption can be effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon dioxide utilization, in particular to an ionic liquid catalyst and a preparation method thereof. BACKGROUND

[0002] With the development of fossil energy, the concentration of carbon dioxide in the environment is getting higher and higher, and the greenhouse effect is getting more and more serious. At the same time, carbon dioxide itself is a cheap C1 source, and effective utilization of carbon dioxide can not only alleviate the greenhouse effect, but also alleviate the energy crisis.

[0003] Since carbon dioxide itself is a kinetically inert gas, it is difficult to activate directly, which makes it difficult to convert and utilize carbon dioxide under mild conditions. The ionic liquid catalyzes the formation of carbonates from carbon dioxide and epoxides, which is an effective way to utilize carbon dioxide, has high atom economy, and is green and efficient. At present, various ionic liquid catalysts for preparing carbonates from carbon dioxide have been industrialized, and their products have been widely used in electrolyte fields, providing a good way for carbon dioxide utilization.

[0004] Patent CN102336735B provides an ionic liquid catalyst for catalytic preparation of carbonates. Its feature is to use 1,2,4-triazole ionic liquid as catalyst, and the reaction temperature is high, up to 150℃, and the advantage is that the amine group can play a synergistic catalytic role.

[0005] Patent CN108129392B provides a protonated carboxy imidazole ionic liquid catalyst, and the reaction condition is between 90-130℃, without adding a cocatalyst. The invention uses hydrogen ions carried by the ionic liquid to promote PO ring opening, and does not add a cocatalyst, which has the problem of slow PO ring opening efficiency.

[0006] Industrialized ionic liquid catalysts have high catalytic efficiency, and the PO conversion rate can reach more than 95%, but the problem is that the reaction needs to be operated at high temperature, the EC industrialization temperature is between 130-145℃, and the PC industrialization temperature is between 110-125℃, which is not energy-friendly and also has some safety hazards.

[0007] In summary, there is an urgent need in the art to provide an ionic liquid catalyst that reduces safety hazards and reduces energy consumption. SUMMARY

[0008] In order to better play the role of carbon dioxide as a C1 source and reduce the consumption of fossil energy, one of the purposes of the present application is to provide an efficient ionic liquid catalyst, which can reduce safety hazards, effectively reduce the energy consumption of carbonate synthesis, and improve resource utilization.

[0009] To achieve the above object, the technical scheme of the present application is as follows:

[0010] An ionic liquid catalyst for preparing ethylene carbonate or propylene carbonate, comprising the following components:

[0011] Quaternary ammonium salt compound 35-55 wt%, preferably 38-45 wt%;

[0012] Auxiliary ring-opening agent 45-65 wt%, preferably 55-62 wt%;

[0013] Based on the total mass of the catalyst;

[0014] Wherein, the quaternary ammonium salt compound has the following formula (I):

[0015]

[0016] Wherein, R 1 , R 2 are each independently selected from one of C2-C4 alkyl groups; X is a halogen element, preferably Br and / or I, n is an integer of 1-6, preferably an integer of 1-3.

[0017] The ionic liquid catalyst provided by the present application has a reaction mechanism in which the alkylene oxide and the empty electron orbital of the metal element are combined, the halide anion attacks the weakened alkylene oxide as a nucleophile, forms an oxy anion, introduces a double hydroxyl functional group, effectively stabilizes the oxy anion of the transition intermediate through double hydrogen bonds, and better realizes the insertion reaction of carbon dioxide. Because a unique structure with double hydroxyl groups in both branches is prepared, the compound has stronger acidity than single hydroxyl compounds, and the metal element can effectively promote the ring-opening of PO / EO.

[0018] In an embodiment of the present application, the auxiliary ring-opening agent is a metal salt with an empty electron orbital, preferably one or more of aluminum chloride, zinc chloride, aluminum bromide, zinc bromide, aluminum methane sulfonate, and zinc methane sulfonate, more preferably aluminum bromide, zinc bromide, aluminum methane sulfonate, and zinc methane sulfonate.

[0019] Another object of the present application is to provide a method for preparing an ionic liquid catalyst.

[0020] A method for preparing the above-mentioned ionic liquid catalyst, comprising the following steps:

[0021] S1: adding an amine compound and a halogenated alkylene oxide into a reactor, adding a solvent, and refluxing to obtain an intermediate product;

[0022] S2: adding water to the intermediate product, and refluxing to obtain the target quaternary ammonium salt compound.

[0023] In one embodiment of the present application, the amine compound of S1 has the following structure:

[0024]

[0025] wherein R 1 , R 2 are each independently selected from one of C2-C4 alkyl groups.

[0026] In one embodiment of the present application, the halogenated epoxy of S1 has the following structure:

[0027]

[0028] wherein n is an integer from 1 to 6, preferably from 1 to 3; X is a halogen, preferably Br and / or I.

[0029] In one embodiment of the present application, the mass ratio of the amine compound to the halogenated epoxy alkane is preferably 1:3.0-5.5.

[0030] In one embodiment of the present application, the solvent of S1 is aprotic solvent, preferably one or more of ester solvents.

[0031] In one embodiment of the present application, the reaction temperature of S1 is 75-90°C.

[0032] In one embodiment of the present application, the reaction time of S1 is 20-26h.

[0033] In one embodiment of the present application, S2 is carried out under acidic conditions; preferably, the acidic conditions use aqueous hydrochloric acid; preferably, the pH value of the acidic conditions is 1-3.

[0034] In one embodiment of the present application, the reaction temperature of S2 is between 68-75°C.

[0035] In one embodiment of the present application, S2 is carried out under nitrogen atmosphere, to avoid possible oxidation under acidic conditions, the reaction can be carried out by nitrogen replacement to form an inert environment.

[0036] In one embodiment of the present application, S2 is first gradually removed by heating part of the water and hydrochloric acid, then n-hexane is added to reflux and evaporate to remove water to obtain the target compound. The above is a general pretreatment step in the art.

[0037] Another object of the present application is to provide a use of an ionic liquid catalyst.

[0038] Use of an ionic liquid catalyst, which is the ionic liquid catalyst as described above, or the ionic liquid catalyst prepared by the method as described above, for preparing ethylene carbonate or propylene carbonate.

[0039] In a specific embodiment of the present application, the method for preparing ethylene carbonate or propylene carbonate by the catalyst is as follows: the synthesized ionic liquid catalyst is weighed and dissolved in PC solvent, then aluminum bromide is added into the solution, the ionic liquid catalyst is stirred and obtained, and then the ionic liquid catalyst is placed in a high-pressure reactor, PO is slowly added into the high-pressure reactor, then CO2 gas is introduced into the high-pressure reactor, and the reaction is carried out. After the reaction is completed, the reactor is cooled to room temperature, the pressure of the reactor is slowly released, and the target product is obtained.

[0040] Compared with the prior art, the effective effect of the present application is that:

[0041] By using the new ionic liquid catalyst synthesized, the safety can be effectively improved, the energy consumption of the device can be reduced, the yield of PC and EC can be improved, and the cost competitiveness of the entire device can be effectively improved. DETAILED DESCRIPTION

[0042] The specific embodiments of the present application are further illustrated by examples, but the examples are only used for understanding the present application, and the protection scope of the present application is not limited by the following examples.

[0043] Raw material information:

[0044]

[0045] Test instrument information:

[0046] Instrument name Model Manufacturer NMR spectrometer AVANCE NEO 400M Bruker Gas chromatograph 7890B Agilent

[0047] The above gas chromatography adopts the following analysis method: the temperature of the sample inlet is 240 DEG C, the split ratio is 50:1; the column oven temperature program is 60 DEG C for 5 min, 10 DEG C / min to 150 DEG C, 20 DEG C / min to 220 DEG C, and the detector is FID; the detection temperature is 240 DEG C.

[0048] Example 1

[0049] (1) The round bottom flask was replaced with nitrogen, 50 g of diethylamine was added into the flask, followed by 100 mL of ethyl acetate, and the mixture was shaken to dissolve completely. After dissolution, 260 g of bromo-oxirane was added dropwise, and the reaction was carried out at 75°C for 20 h under reflux. The ethyl acetate and excess bromo-oxirane were removed by rotary evaporation, followed by washing with dichloromethane and drying in a drying oven, and the yield was 75%. A small amount of the product was purified by adding 100 mL of n-hexane to the reaction solution, and refluxing was carried out. The crystallized precipitate was analyzed by nuclear magnetic resonance to determine that N,N-diethyl-N,N-di(2,3-dihydroxypropyl) ammonium bromide was obtained. The nuclear magnetic resonance hydrogen spectrum (400 MHz, DMF-D6) showed peaks at 2.77 (m, 2H); 2.62-2.63 (m, 4H); 2.37-2.40 (m, 8H); 1.02 (t, 6H); and the nuclear magnetic resonance carbon spectrum showed peaks at 66.2; 55.8; 49.3; 45.9; and 11.1.

[0050] (2) 95 mL of hydrochloric acid aqueous solution (10 wt%) was added into the flask, and the pH value was 2.3. The product obtained in the first step was transferred into a glass flask, and was continuously stirred and dissolved. The solution was heated under reflux at 68°C for 10 h, and the reflux device was removed. 400 mL of toluene was added, and water-toluene azeotrope was distilled off at 100°C. The product was dried in a drying oven at 110°C. The structure of the product was confirmed by nuclear magnetic resonance, and the target product was obtained. The detailed peak positions were as follows: 3.93 (m, 2H); 3.81 (m, 2H); 3.65 (s, 2H); 3.52-3.58 (m, 6H); 3.28 (m, 6H); 1.25 (t, 6H); and the nuclear magnetic resonance carbon spectrum showed peaks at 69.8; 68.8; 63.1; 56.2; and 8.3.

[0051] Example 2

[0052] (1) A round bottom flask was replaced with nitrogen, 50 g of dibutylamine was added into the flask, then 100 mL of ethyl acetate was added, and the mixture was shaken to dissolve completely. After dissolution, 158 g of bromoepoxypropane was added dropwise, and the mixture was refluxed at 88°C for 22 h. The ethyl acetate was removed by rotary evaporation, then washed with dichloromethane, and dried in a drying oven. The yield was 68%. A small amount of the product was purified by adding 100 mL of n-hexane to the reaction solution, and refluxing. The crystalline precipitate was analyzed by nuclear magnetic resonance to determine that brominated N,N-dibutyl-N,N-di(2,3-dihydroxypropyl) ammonium was obtained.

[0053] (2) 103 mL of hydrochloric acid aqueous solution (10 wt%) was added into the flask, and the pH value was 1.6. The product obtained in the first step was transferred into a glass flask, and was stirred to dissolve. The mixture was heated and refluxed at 72°C for 12 h. After removing the reflux device, 400 mL of toluene was added, and water-toluene azeotrope was distilled at 100°C. The mixture was dried in a drying oven at 110°C. The structure of the product was confirmed by nuclear magnetic resonance, and the target product was obtained. The detailed peak positions were as follows: 3.93 (m, 2H); 3.81 (m, 2H); 3.65 (s, 2H); 3.52-3.58 (m, 6H); 3.24-3.27 (m, 6H); 1.77 (m, 4H); 0.90 (t, 6H); the nuclear magnetic resonance carbon spectrum peak position was 69.8; 68.8; 63.7; 61.4; 15.7; 11.1.

[0054] Example 3

[0055] (1) A round bottom flask was replaced with nitrogen, 50 g of dibutylamine was added into the flask, then 100 mL of ethyl acetate was added, and the mixture was shaken to dissolve completely. After dissolution, 158 g of bromoepoxypropane was added dropwise, and the mixture was refluxed at 88°C for 22 h. The ethyl acetate was removed by rotary evaporation, then washed with dichloromethane, and dried in a drying oven. The yield was 68%. A small amount of the product was purified by adding 100 mL of n-hexane to the reaction solution, and refluxing. The crystalline precipitate was analyzed by nuclear magnetic resonance to determine that brominated N,N-dibutyl-N,N-di(2,3-dihydroxypropyl) ammonium was obtained.

[0056] (2) Add 105 mL of hydrochloric acid aqueous solution (10 wt%) to the flask, and the pH value is 1.8. Transfer the product obtained in the first step to a glass flask, and continuously stir and dissolve it. Heat it to reflux at 75°C for 13 h. Remove the reflux device, and add 400 mL of toluene to it. Distill off the water-toluene azeotrope at 100°C. Dry it in a drying oven at 110°C. Confirm the structure of the product by nuclear magnetic resonance to obtain the target product.

[0057] Example 4

[0058] (1) Replace the round-bottom flask with nitrogen, and add 50 g of diethylamine to the round-bottom flask, followed by 100 mL of ethyl acetate. Shake to dissolve it thoroughly. After dissolving, add 256 g of bromoepoxybutane dropwise. Reflux at 85°C for 26 h. Spin dry the ethyl acetate by rotary evaporation, followed by dichloromethane washing, and dry it in a drying oven. The yield is 68%. Take a small amount for purification. The purification method is to add 100 mL of n-hexane to the removed reaction liquid, and continuously reflux. Take the crystalline precipitate for analysis. Determine by nuclear magnetic resonance that brominated N,N-diethyl-N,N-di(2,3-dihydroxypropyl) ammonium is obtained.

[0059] (2) Add 98 mL of hydrochloric acid aqueous solution (10 wt%) to the flask, and the pH value is 2.4. Transfer the product obtained in the first step to a glass flask, and continuously stir and dissolve it. Heat it to reflux at 72°C for 14 h. Remove the reflux device, and add 400 mL of toluene to it. Distill off the water-toluene azeotrope at 100°C. Dry it in a drying oven at 110°C. Confirm the structure of the product by nuclear magnetic resonance to obtain the target product.

[0060] Example 5

[0061] (1) Replace the round-bottom flask with nitrogen, and add 50 g of diethylamine to the round-bottom flask, followed by 100 mL of ethyl acetate. Shake to dissolve it thoroughly. After dissolving, add 280 g of iodoepoxypropane dropwise. Reflux at 85 ℃ °C for 27 h. Spin dry the ethyl acetate by rotary evaporation, followed by dichloromethane washing, and dry it in a drying oven. The yield is 68%. Take a small amount for purification. The purification method is to add 100 mL of n-hexane to the removed reaction liquid, and continuously reflux. Take the crystalline precipitate for analysis. Determine by nuclear magnetic resonance that brominated N,N-diethyl-N,N-di(2,3-dihydroxypropyl) ammonium is obtained.

[0062] (2) Add 101 mL of hydrochloric acid aqueous solution (10 wt%) into the flask, and the pH value is 2.2. Transfer the product obtained in the first step into a glass flask, and continuously stir and dissolve it. Heat it to reflux at 72°C for 14 h. Remove the reflux device, and add 400 mL of toluene into it. Distill water-toluene azeotrope at 100°C. Dry it in a drying oven at 110°C. Confirm the structure of the product by using nuclear magnetic resonance, and obtain the target product.

[0063] Example 6

[0064] (1) Replace a round-bottom flask with nitrogen, and add 50 g of diethylamine into the round-bottom flask. Then add 100 mL of ethyl acetate, and shake to dissolve it completely. After dissolving, add 258 g of chloroepoxyhexane dropwise, and reflux it at 85°C for 27 h. Dry it by using a rotary evaporator, and then wash it with dichloromethane. Dry it in a drying oven, and the yield is 68%. Take a small amount for purification. Add 100 mL of n-hexane into the removed reaction liquid, and continuously reflux it. Take the crystallized precipitate for analysis, and determine the obtained N,N-dihexyl-N,N-bis(2,3-dihydroxypropyl) ammonium bromide by using nuclear magnetic resonance.

[0065] (2) Add 100 mL of hydrochloric acid aqueous solution (10 wt%) into the flask, and the pH value is 2.5. Transfer the product obtained in the first step into a glass flask, and continuously stir and dissolve it. Heat it to reflux at 72°C for 14 h. Remove the reflux device, and add 400 mL of toluene into it. Distill water-toluene azeotrope at 100°C. Dry it in a drying oven at 110°C. Confirm the structure of the product by using nuclear magnetic resonance, and obtain the target product.

[0066] Example 7

[0067] Weigh 0.25 g of the ionic liquid catalyst obtained in Example 1, and dissolve it in 0.6 g of PC solvent. Then add 0.35 g of aluminum bromide into it, and stir to obtain the ionic liquid catalyst. Place it in a high-pressure reaction kettle, and slowly add 55 g of PO into the high-pressure reaction kettle. Then introduce 45 g of CO2 gas into it, and react it at 80°C. End the reaction after 1 h of reaction, cool it to room temperature, slowly release the pressure of the reaction kettle, take a sample, and analyze it by using gas chromatography. The calculated PO conversion rate is 99%, and the PC selectivity is 98.5%.

[0068] Example 8

[0069] The ionic liquid catalyst obtained from Example 2 was weighed 0.28 g and dissolved in 0.6 g PC reaction liquid, then 0.35 g aluminum bromide was added into it and stirred to obtain the ionic liquid catalyst, which was placed in a high-pressure reactor, 55 g PO was slowly added into the high-pressure reactor, then 45 g CO2 gas was introduced into it, and the reaction was carried out at 83°C. The reaction was completed after 1 h, cooled to room temperature, slowly unloaded the reactor pressure, sampling, gas chromatography analysis, by calculating the PO conversion rate was 99%, PC selectivity was 97.3%.

[0070] Example 9

[0071] The ionic liquid catalyst obtained from Example 3 was weighed 0.31 g and dissolved in 0.6 g PC reaction liquid, then 0.40 g aluminum bromide was added into it and stirred to obtain the ionic liquid catalyst, which was placed in a high-pressure reactor, 55 g PO was slowly added into the high-pressure reactor, then 45 g CO2 gas was introduced into it, and the reaction was carried out at 81°C. The reaction was completed after 1 h, cooled to room temperature, slowly unloaded the reactor pressure, sampling, gas chromatography analysis, by calculating the PO conversion rate was 98%, PC selectivity was 93.5%.

[0072] Example 10

[0073] The ionic liquid catalyst obtained from Example 4 was weighed 0.28 g and dissolved in 0.6 g PC reaction liquid, then 0.42 g aluminum bromide was added into it and stirred to obtain the ionic liquid catalyst, which was placed in a high-pressure reactor, 55 g PO was slowly added into the high-pressure reactor, then 45 g CO2 gas was introduced into it, and the reaction was carried out at 83°C. The reaction was completed after 1 h, cooled to room temperature, slowly unloaded the reactor pressure, sampling, gas chromatography analysis, by calculating the PO conversion rate was 99%, PC selectivity was 98.6%.

[0074] Example 11

[0075] The ionic liquid catalyst obtained from Example 4 was weighed 0.28 g and dissolved in 0.6 g PC reaction liquid, then 0.50 g aluminum chloride was added into it and stirred to obtain the ionic liquid catalyst, which was placed in a high-pressure reactor, 55 g PO was slowly added into the high-pressure reactor, then 45 g CO2 gas was introduced into it, and the reaction was carried out at 82°C. The reaction was completed after 1 h, cooled to room temperature, slowly unloaded the reactor pressure, sampling, gas chromatography analysis, by calculating the PO conversion rate was 92%, PC selectivity was 95.8%.

[0076] Example 12

[0077] The ionic liquid catalyst obtained from Example 5 was weighed 0.38 g and dissolved in 0.6 g PC reaction liquid, then 0.35 g aluminum chloride was added into it and stirred to obtain the ionic liquid catalyst, which was placed in a high-pressure reactor, 55 g PO was slowly added into the high-pressure reactor, then 45 g CO2 gas was introduced into it, and the reaction was carried out at 81°C. The reaction was completed after 1 h, cooled to room temperature, slowly unloaded the reactor pressure, sampling, gas chromatography analysis, by calculating the PO conversion rate was 93%, PC selectivity was 92.8%.

[0078] Example 13

[0079] The ionic liquid catalyst obtained from Example 6 was weighed 0.38 g and dissolved in 0.6 g PC reaction liquid, then 0.45 g zinc methanesulfonate was added into it and stirred to obtain the ionic liquid catalyst, which was placed in a high-pressure reactor, 55 g PO was slowly added into the high-pressure reactor, then 45 g CO2 gas was introduced into it, and the reaction was carried out at 82°C. The reaction was completed after 1 h, cooled to room temperature, slowly unloaded the reactor pressure, sampling, gas chromatography analysis, by calculating the PO conversion rate was 93%, PC selectivity was 95.5%.

[0080] Comparative Example 1

[0081] The industrial ionic liquid catalyst (0.25 g 1-butyl-3-methyl imidazole bromide + 0.35 g aluminum bromide, dissolved in 0.6 g PC) was synthesized according to the same method as Example 7, and gas chromatography analysis calculation showed that the PO conversion rate was 89% and the PC selectivity was 91%.

[0082] Comparative Example 2

[0083] The industrial ionic liquid catalyst (0.25 g 1-butyl-3-methyl imidazole bromide + 0.35 g aluminum bromide, dissolved in 0.6 g PC) was synthesized according to the same method as Example 7, except that the reaction temperature was 120°C, and sampling, gas chromatography analysis calculation showed that the PO conversion rate was 97% and the PC selectivity was 93%.

[0084] The experimental data of each example / comparative example were quantitatively analyzed by gas chromatography, and the conversion rate and selectivity were as follows:

[0085]

[0086] As can be seen from the data of Examples 5-8 and Comparative Examples 1-2, under the same temperature conditions, the ionic liquid catalyst prepared in the application can more efficiently improve the PO conversion rate, and achieve high selectivity to generate PC, and most importantly, can reduce the reaction temperature by 40℃, greatly improving the safety and reducing the energy consumption. Moreover, it is found that the catalyst of the application is also superior to the catalyst of the prior art in the effect at high temperature of 120℃.

[0087] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An ionic liquid catalyst for the production of ethylene carbonate or propylene carbonate, characterized in that, The ionic liquid catalyst comprises the following components: a quaternary ammonium salt compound 35-55 wt.%; an auxiliary ring-opening agent 45-65 wt.%; based on the total mass of the catalyst; wherein the quaternary ammonium salt compound has the following structure of formula (I): wherein R 1 , R 2 are each independently selected from one of C2-C4alkane groups; X is a halogen element; n is an integer from 1 to 6; The catalyst is prepared by a method comprising the following steps: S1: adding an amine compound and a halogenated alkylene oxide into a reactor, adding a solvent, and refluxing to obtain an intermediate product; S2: adding water to the intermediate product, and refluxing to obtain a target quaternary ammonium salt compound.

2. The ionic liquid catalyst of claim 1, wherein, The ionic liquid catalyst comprises the following components: a quaternary ammonium salt compound 38-45 wt.%; an auxiliary ring-opening agent 55-62 wt.%; based on the total mass of the catalyst; in the structure of formula (I), X is Br and / or I; n is an integer of 1-3.

3. The ionic liquid catalyst according to claim 1 or 2, characterized in that, The auxiliary ring-opening agent is a metal salt with a vacant electron orbital.

4. The ionic liquid catalyst of claim 3, wherein, The auxiliary ring-opening agent is one or more of aluminum chloride, zinc chloride, aluminum bromide, zinc bromide, aluminum methane sulfonate, and zinc methane sulfonate.

5. The ionic liquid catalyst of claim 4, wherein, The auxiliary ring-opening agent is one or more of aluminum bromide, zinc bromide, aluminum methane sulfonate, and zinc methane sulfonate.

6. A process for the preparation of the ionic liquid catalyst of any one of claims 1 to 5, characterized in that, The method comprises the following steps: S1: adding an amine compound and a halogenated alkylene oxide into a reactor, adding a solvent, and refluxing to obtain an intermediate product; S2: adding water to the intermediate product, and refluxing to obtain a target quaternary ammonium salt compound.

7. The method of claim 6, wherein, The structure of the amine compound in S1 is as follows: wherein R 1 , R 2 are each independently selected from one of C2-C4alkyl groups; and / or, the structure of the halogenated epoxy in S1 is as follows: wherein n is an integer of 1-6; X is a halogen element; and / or, the solvent in S1 is an aprotic solvent; and / or, the reaction temperature in S1 is 75-90°C.

8. The method of claim 7, wherein, in the structure of the halogenated epoxy in S1, n is an integer of 1-3; X is Br and / or I; the mass ratio of the amine compound to the halogenated alkylene oxide in S1 is 1:3.0-5.5; and / or, the solvent in S1 is an ester solvent.

9. The method of claim 6, wherein, The S2 is carried out under acidic conditions.

10. The method of claim 9, wherein, The acidic conditions of S2 use an aqueous hydrochloric acid solution.

11. Use of an ionic liquid catalyst, the catalyst being the ionic liquid catalyst of any one of claims 1-5, or the ionic liquid catalyst prepared by the method of any one of claims 6-10, for preparing ethylene carbonate or propylene carbonate.

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