[TMGH] Br dication-based supported polymeric ionic liquid as well as preparation method and application thereof

Abstract

The invention discloses a supported polymeric ionic liquid based on [TMGH] Br dication and a preparation method and application thereof. According to the method, five starting raw materials which are easy to obtain are used, the supported polymeric ionic liquid based on [TMGH] Br dication is prepared through a one-pot method, and cyclic carbonate can be efficiently synthesized under the conditions of the temperature of 60 DEG C, normal pressure, no solvent and no cocatalyst. The polymeric ionic liquid is simple and efficient in synthesis method, has multiple active centers and high ion density, shows excellent catalytic activity and has good cycle performance.

Description

Technical Field

[0001] The invention relates to the technical field of synthesis of cyclic carbonates, and in particular to a supported polymeric ionic liquid based on [TMGH]Br dication, and a preparation method and application thereof. Technical Background

[0002] To date, the global energy supply mainly relies on the combustion of fossil fuels (about 83%), which has led to a continuous increase in the concentration of CO2 in the atmosphere, and a corresponding increase in global temperature of 2°C compared to pre-industrial levels. Extreme weather, melting glaciers, ocean acidification and food production reduction are considered to be closely related to global climate change. Therefore, reducing CO2 emissions has become a top priority for many countries. At the same time, as a non-toxic and abundant renewable carbon resource, CO2 can be converted into a variety of high-value-added chemicals, including urea, cyclic carbonates, ethylene carbonate, dimethyl ether, methane, methanol, acetic acid, carbon monoxide and ethylene. Among these transformation reactions, the cycloaddition reaction of CO2 with epoxides to form cyclic carbonates has attracted great interest among researchers. However, the thermodynamic barriers and inherent kinetic inertness of CO2 require efficient catalysts to promote the reaction.

[0003] At present, there are many reports on the catalytic system for converting CO2 and epoxide into cyclic carbonate. CN115025817A discloses a catalyst for catalyzing CO2 to synthesize cyclic carbonate, characterized in that the catalyst can convert CO2 and epoxide into cyclic carbonate under mild conditions of 50-100°C without organic solvent and co-catalyst, and the catalyst is easy to recover. However, the catalyst requires the coordination of metal complexes, and the introduction of Cr metal complexes not only causes secondary pollution to the environment, but also increases the reaction cost.

[0004] In addition, CN115888824A discloses an amide functionalized polyionic liquid catalyst for catalyzing CO2 to synthesize cyclic carbonates, characterized in that the catalyst has the advantages of being easy to separate and recyclable. The catalyst is prepared by free radical polymerization and contains ionic liquids and amide monomers with different active centers. However, the catalyst requires the synthesis of ionic liquid monomers first, and then free radical polymerization to synthesize polymers, and the experimental steps are relatively cumbersome.

[0005] CN114433228A discloses a core-shell polyionic liquid catalyst for catalyzing CO2 to synthesize cyclic carbonate. The catalyst has many advantages such as high catalytic efficiency, strong stability, not easy to decompose, simple preparation process, etc., but the research only examines the catalytic effect of pure CO2 on cycloaddition reaction, and does not examine the catalytic effect on simulated flue gas. Summary of the invention

[0006] The present invention aims to provide a supported polymeric ionic liquid based on [TMGH]Br dication and its preparation method and application in view of the deficiencies in the prior art. The preparation adopts five raw materials of 3-bromopropionic acid, 4-dimethylaminopyridine, 1-vinylimidazole, tetramethylguanidine and divinylbenzene through a one-pot reaction. The supported polymeric ionic liquid based on [TMGH]Br dication prepared by the present invention can be used to catalyze the synthesis of cyclic carbonates from epoxy compounds and CO2. Under the conditions of 60°C, normal pressure, solvent-free and catalyst-free, the reaction lasts for 20 hours, and cyclic carbonates can be obtained with excellent yield and high selectivity. In addition, using simulated flue gas (15vol%CO2+85vol%N2) as the CO2 source, at a pressure of 1.5MPa and at the same temperature, the conversion rate of epoxides after 24 hours of reaction is as high as 93%. The synthetic raw materials of this catalyst are cheap and easily available, the synthesis method is simple and efficient, it has multi-center active sites and high ion density, and it has excellent catalytic performance in catalyzing the reaction of CO2 and epoxides to synthesize cyclic carbonates. It can be easily recycled, meets the requirements of green chemistry and sustainable development, and shows good industrial application potential.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] First, the present invention provides a supported polymeric ionic liquid based on [TMGH]Br dication, wherein the polymeric ionic liquid based on [TMGH]Br dication has the following structural formula:

[0009] n, m≥1 and are integers.

[0010] The structural formula of the supported substance of the [TMGH]Br dicationic polymeric ionic liquid is:

[0011]

[0012] The structural formula of the supported polymerized ionic liquid is:

[0013]

[0014] Secondly, the present invention provides a method for preparing the above-mentioned [TMGH]Br dication-based supported polymeric ionic liquid, comprising the following steps:

[0015] Under a nitrogen atmosphere, 3-bromopropionic acid, 4-dimethylaminopyridine and acetonitrile are mixed and stirred evenly, and 1-vinylimidazole and tetramethylguanidine are added; after heating to 60°C to 70°C, azobisisobutyronitrile and divinylbenzene are dissolved in an appropriate amount of acetonitrile, added to the reaction system, heated to 80°C and stirred for reaction for 24 hours, filtered, washed and dried to obtain a supported polymeric ionic liquid based on [TMGH]Br double cation.

[0016] Furthermore, the molar ratio of the 3-bromopropionic acid, 4-dimethylaminopyridine, 1-vinylimidazole, tetramethylguanidine and divinylbenzene is 2:1:1:2:0.5-4.

[0017] Thirdly, the present invention provides an application of the above-mentioned supported polymeric ionic liquid based on [TMGH]Br dication, which is used for catalyzing the reaction of synthesizing cyclic carbonates from carbon dioxide and epoxides.

[0018] Furthermore, epoxide and pure CO2 were reacted at a reaction pressure of 1 bar, a reaction temperature of 60°C, using a supported polymeric ionic liquid based on [TMGH]Br dication as a catalyst, and a reaction time of 20 hours to catalyze the synthesis of cyclic carbonate.

[0019] Furthermore, epoxide was reacted with 15 vol% CO2 and 85 vol% N2 at a reaction pressure of 1.5 MPa, a reaction temperature of 60°C, and a reaction time of 24 hours, using a supported polymeric ionic liquid based on [TMGH]Br dication as a catalyst to catalyze the synthesis of cyclic carbonate.

[0020] Furthermore, the epoxide is one of epichlorohydrin, epibromohydrin, ethylene oxide methanol, n-butyl glycidyl ether, allyl glycidyl ether, glycidyl phenyl ether, and styrene oxide.

[0021] Furthermore, 6 mg of the supported polymeric ionic liquid based on [TMGH]Br dications is required to be added to 1 mmol of the epoxide as a catalyst.

[0022] The beneficial effects of the present invention include:

[0023] (1) The present invention uses a one-pot method to simply and efficiently synthesize a supported polymeric ionic liquid based on [TMGH]Br dication.

[0024] (2) The present invention is based on the [TMGH]Br double cation supported polymeric ionic liquid, which is a multi-site ionic liquid heterogeneous catalyst for catalyzing the cycloaddition reaction of CO2 and epoxide. It has high catalytic efficiency and can obtain cyclic carbonate compounds in high yield and high selectivity.

[0025] (3) The supported polymeric ionic liquid based on [TMGH]Br dication of the present invention has a wide range of applicability to epoxy compound substrates.

[0026] (4) The supported polymeric ionic liquid based on the [TMGH]Br dication of the present invention has stable recycling performance, still maintains high active sites after multiple cycles, and can be scaled up for synthesis. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FT-IR spectrum of DM[TMGH]Br@P-DVB / Im[TMGH]Br prepared in Example 1 of the present invention;

[0028] Figure 2 This is the TG thermogravimetric diagram of DM[TMGH]Br@P-DVB / Im[TMGH]Br prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] For a deeper understanding of the present invention, the preferred embodiments will be described in detail below in conjunction with examples. However, it should be noted that these descriptions are only used to further illustrate the features and advantages of the present invention and do not constitute a limitation to the claims of the present invention.

[0030] The reagents and instruments used in the present invention are not marked with the manufacturer, and are all commercially available conventional products.

[0031] Example 1

[0032] 1. Preparation of supported polymeric ionic liquids based on [TMGH]Br dications

[0033] Under nitrogen atmosphere, 1683 mg (10 mmol) of 3-bromopropionic acid and 611 mg (5 mmol) of 4-dimethylaminopyridine were placed in a reaction bottle, 10 mL of acetonitrile was added, and the mixture was dissolved under stirring. 0.41 mL (5 mmol) of 1-vinylimidazole and 1.5 mL (10 mmol) of tetramethylguanidine were added with a syringe under sealed stirring.

[0034] After heating to 60°C to 70°C, 30 mg of azobisisobutyronitrile was dissolved in 0.71 mL (5 mmol) of divinylbenzene and added to the reaction system. The mixture was stirred at 80°C for 24 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed with ethyl acetate three times, and vacuum dried at 80°C for 24 hours to obtain a loaded polymeric ionic liquid based on [TMGH]Br dication, recorded as DM[TMGH]Br@P-DVB / Im[TMGH]Br.

[0035] 2. Catalytic CO2 cycloaddition reaction to synthesize cyclic carbonates

[0036] Weigh 30 mg of DM[TMGH]Br@P-DVB / Im[TMGH]Br and place it in a Schlenk tube. Then add 5 mmol of epichlorohydrin and seal the Schlenk tube with a rubber stopper. After evacuation, replace the gas in the bottle with 1 bar of CO2. Repeat this step 3 times until the Schlenk tube is filled with CO2. Then place it in a magnetic stirrer and heat it in an oil bath, and react at 60°C for 20 hours.

[0037] The chemical reaction equation is as follows:

[0038]

[0039] After the reaction was completed, the solid catalyst was filtered and washed three times with ethyl acetate, and dried in a vacuum drying oven at 80° C. to recover the catalyst.

[0040] The reaction product (filtrate) after filtration was diluted with ethyl acetate and quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS). The selectivity of the target product was 98% and the yield was 99%.

[0041] Example 2

[0042] The difference from Example 1 is that a mixed gas of 15 vol% CO2 + 85 vol% N2 is used as the CO2 source, 30 mg of DM[TMGH]Br@P-DVB / Im[TMGH]Br is weighed and placed in a 25 mL Schlenk tube, and then 5 mmol of epichlorohydrin is added, and the reaction is carried out under reaction conditions of 60°C and 1.5 MPa for 24 hours. The reaction liquid is quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS), and the selectivity for preparing the target product reaches 97%, and the yield is 93%.

[0043] Example 3

[0044] The difference from Example 1 is that the epoxy compound used to prepare the cyclic carbonate is epibromopropane. Through quantitative analysis by GC-MS, the selectivity of the target product is 99% and the yield is 97.6%.

[0045] The chemical equation for this reaction is as follows:

[0046]

[0047] Example 4

[0048] The difference from Example 1 is that the epoxy compound used to prepare the cyclic carbonate is ethylene oxide methanol. Through quantitative analysis by GC-MS, the selectivity of the target product is 99% and the yield is 95.2%.

[0049] The chemical equation for this reaction is as follows:

[0050]

[0051] Example 5

[0052] The difference from Example 1 is that the epoxy compound used to prepare the cyclic carbonate is n-butyl glycidyl ether. Through quantitative analysis by GC-MS, the selectivity of the target product is 99% and the yield is 94.6%.

[0053] The chemical equation for this reaction is as follows:

[0054]

[0055] Example 6

[0056] The difference from Example 1 is that the epoxy compound used to prepare the cyclic carbonate is allyl glycidyl ether. Quantitative analysis by GC-MS shows that the selectivity of the target product is 97.6% and the yield is 96.3%.

[0057] The chemical equation for this reaction is as follows:

[0058]

[0059] Example 7

[0060] The difference from Example 1 is that the epoxy compound used to prepare the cyclic carbonate is glycidyl phenyl ether. Quantitative analysis by GC-MS shows that the selectivity of the target product is 99% and the yield is 90.4%.

[0061] The chemical equation for this reaction is as follows:

[0062]

[0063] Example 8

[0064] The difference from Example 1 is that the epoxy compound used to prepare the cyclic carbonate is styrene oxide. Quantitative analysis by GC-MS shows that the selectivity of the target product is 99% and the yield is 57%.

[0065] The chemical equation for this reaction is as follows:

[0066]

[0067] Example 9

[0068] The difference from Example 1 is that the catalyst used is prepared from 3-bromopropionic acid, 4-dimethylaminopyridine, 1-vinylimidazole, tetramethylguanidine and divinylbenzene in a molar ratio of 2:1:1:2:0.5. Quantitative analysis by GC-MS shows that the selectivity of the target product is 98% and the yield is 93%.

[0069] Example 10

[0070] The difference from Example 1 is that the catalyst used is prepared from 3-bromopropionic acid, 4-dimethylaminopyridine, 1-vinylimidazole, tetramethylguanidine and divinylbenzene in a molar ratio of 2:1:1:2:2. Quantitative analysis by GC-MS shows that the selectivity of the target product is 98% and the yield is 87%.

[0071] Embodiment 11

[0072] The difference from Example 1 is that the catalyst used is prepared from 3-bromopropionic acid, 4-dimethylaminopyridine, 1-vinylimidazole, tetramethylguanidine and divinylbenzene in a molar ratio of 2:1:1:2:4. Quantitative analysis by GC-MS shows that the selectivity of the target product is 98% and the yield is 81%.

[0073] The catalyst DM[TMGH]Br@P-DVB / Im[TMGH]Br recovered after the reaction in Example 1 was used for cyclic catalysis. The number of cycles and the selectivity and yield of the prepared target product are shown in Table 1.

[0074] Table 1. Recycling effect of catalyst DM[TMGH]Br@P-DVB / Im[TMGH]Br

[0075]

[0076] like Figure 1 This is the Fourier transform infrared (FT-IR) spectrum of DM[TMGH]Br@P-DVB / Im[TMGH]Br. 1603cm -1 、1550cm -1 and 1448cm -1 The absorption peak at 3095cm -1 The adsorption peak at 2974 cm is due to the CH stretching vibration of the aromatic CH, confirming that DVB was successfully incorporated into the polymer framework. -1 and 2900cm -1 The peak at 1640 cm -1 The significant absorption at 1160cm-1 CN appears everywhere + The stretching vibration absorption peak of the bond indicates the presence of a quaternary ammonium salt structure in the material. In summary, FT-IR characterization shows that the supported polymeric ionic liquid DM[TMGH]Br@P-DVB / Im[TMGH]Br based on [TMGH]Br dication was successfully synthesized.

[0077] Figure 2 This is the thermogravimetric (TG) graph of DM[TMGH]Br@P-DVB / Im[TMGH]Br prepared in Example 1 of the present invention. Figure 2 As shown, the DM[TMGH]Br@P-DVB / Im[TMGH]Br prepared in Example 1 began to degrade after about 200°C, indicating that the DM[TMGH]Br@P-DVB / Im[TMGH]Br catalyst prepared in Example 1 has good thermal stability at the studied temperature (60°C).

[0078] According to the contents disclosed in the above description, those skilled in the art to which the present invention belongs may also make appropriate changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A supported polymeric ionic liquid based on [TMGH]Br dication, characterized in that: The supported polymeric ionic liquid based on [TMGH]Br dication has the following structural formula: n, m≥1 and are integers.

2. A method for preparing a supported polymeric ionic liquid based on [TMGH]Br dication according to claim 1, characterized in that: The steps include: Under a nitrogen atmosphere, 3-bromopropionic acid, 4-dimethylaminopyridine and acetonitrile are mixed and stirred evenly, and 1-vinylimidazole and tetramethylguanidine are added; after heating to 60°C to 70°C, azobisisobutyronitrile and divinylbenzene are dissolved in an appropriate amount of acetonitrile, added to the reaction system, heated to 80°C and stirred for reaction for 24 hours, filtered, washed and dried to obtain a supported polymeric ionic liquid based on [TMGH]Br double cation.

3. The method for preparing a supported polymeric ionic liquid based on [TMGH]Br dication according to claim 2, characterized in that: The molar ratio of the 3-bromopropionic acid, 4-dimethylaminopyridine, 1-vinylimidazole, tetramethylguanidine and divinylbenzene is 2:1:1:2:0.5-4.

4. Use of the [TMGH]Br dication-based supported polymeric ionic liquid according to claim 1 for catalyzing the reaction of carbon dioxide and epoxy compounds to synthesize cyclic carbonates.

5. The use according to claim 4, characterized in that: Cyclic carbonates were synthesized by reacting epoxide and CO2 at a reaction pressure of 1 bar and a reaction temperature of 60°C using a supported polymeric ionic liquid based on [TMGH]Br dication as a catalyst for a reaction time of 20 hours.

6. The use according to claim 4, characterized in that: Cyclic carbonate was synthesized by reacting epoxide with 15 vol% CO2 and 85 vol% N2 at a reaction pressure of 1.5 MPa, a reaction temperature of 60°C, and a reaction time of 24 hours using a supported polymeric ionic liquid based on [TMGH]Br dication as a catalyst.

7. The use according to claim 4, characterized in that: The epoxide is one of epichlorohydrin, epibromohydrin, ethylene oxide methanol, n-butyl glycidyl ether, allyl glycidyl ether, glycidyl phenyl ether and styrene oxide.

8. The use according to any one of claims 4 to 7, characterized in that: The 1 mmol epoxide needs to add 6 mg of the supported polymeric ionic liquid based on [TMGH]Br dications as a catalyst.

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