Phenylboronic acid functionalized polyionic liquid catalyst as well as preparation method and application thereof

Abstract

The invention discloses a phenylboronic acid functionalized polyionic liquid catalyst which is synthesized in one step through hydrothermal free radical copolymerization by taking phenylboronic acid imidazolium salt ionic liquid (PBIL) as a monomer and divinyl benzene (DVB) as a cross-linking agent. The catalyst efficiently catalyzes the cycloaddition reaction of CO and epoxide under the conditions of no solvent, normal pressure and 90-100 DEG C through the synergistic effect of multiple active sites of hydroxyl, imidazolyl and Br, and the conversion rate of 1, 2-epoxyhexane reaches 99%. The catalyst can be recycled and is stable in structure, the problem that high pressure / co-catalyst is needed in the prior art is solved, and the catalyst has industrial application potential.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of heterogeneous catalytic materials and carbon dioxide capture and conversion technology, and particularly relates to a phenylboronic acid functionalized polyionic liquid catalyst, a preparation method thereof, and application of the catalyst in catalyzing a carbon dioxide and epoxide cycloaddition reaction to prepare a cyclic carbonate. BACKGROUND

[0002] As one of the main greenhouse gases, the rapid increase of carbon dioxide (CO2) concentration in the atmosphere significantly aggravates the greenhouse effect, has a profound impact on the global climate pattern, and poses a serious threat to environmental stability and ecological system integrity. Under the background of increasingly tight global resources and energy supply, chemical capture, activation and subsequent conversion of CO2 into high-value energy carriers, materials or chemical products are of great importance. This not only can alleviate the rise of CO2 concentration in the atmosphere, but also helps to transition to a low-carbon economic system.

[0003] Among various CO2 conversion methods, the cycloaddition reaction of CO2 and epoxide is a key reaction, which has 100% atom economy and meets the principles of "green chemistry". The obtained product cyclic carbonate is an important organic synthesis intermediate and fine chemical product, which is widely used in the fields of solvents, battery electrolytes, medicines and polymer synthesis, etc.

[0004] However, due to the high thermodynamic stability and kinetic inertness of CO2 molecules, as well as the energy barrier of epoxide ring-opening, the cycloaddition reaction puts high requirements on the performance of catalysts. Traditional catalysts such as metal complexes and quaternary ammonium salts often have problems such as low catalytic activity, need for co-catalysts, harsh reaction conditions (such as high temperature and high pressure), difficulty in catalyst recovery or metal residue, etc.

[0005] Ionic liquids (ILs) have shown great potential in the field of CO2 capture and conversion due to their adjustable structure, excellent chemical and thermal stability, and unique ionic environment. Imidazolium-based ionic liquids can activate CO2 due to the strong van der Waals force and electrostatic interaction between the imidazole ring and CO2. Integrating hydrogen bond donors (such as hydroxyl, carboxyl, amino, boronic acid groups, etc.) into imidazolium-based ionic liquids or polyionic liquids (PILs) catalysts can form hydrogen bond interactions with the oxygen atoms in epoxide compounds, which is beneficial to the polarization of C-O bond in epoxide compounds and promotes the nucleophilic attack of nucleophiles on the β-carbon atom in epoxide compounds, thereby improving the catalytic efficiency. As a new type of functional material, polyionic liquids combine the advantages of ionic liquids and polymers, such as structural designability, high specific surface area, good chemical and thermal stability, and easy recovery and reuse, etc., and have received widespread attention as heterogeneous catalysts in CO2 cycloaddition reactions.

[0006] Therefore, developing a benzene boronic acid functionalized polyionic liquid catalyst with high catalytic activity, good stability, no need for co-catalyst, mild reaction conditions and environmental friendliness has important theoretical significance and application value for efficient conversion of CO2 to prepare cyclic carbonates.

[0007] Based on the above considerations, the present application designs a series of imidazole / benzene boronic acid functionalized PILs, taking benzene boronic acid imidazole ionic liquid (PBIL) as a monomer and divinylbenzene (DVB) as a crosslinking agent, to prepare imidazole / benzene boronic acid functionalized crosslinked PILs by one-step hydrothermal polymerization. Since the catalyst has hydroxyl, imidazole, Br − active sites, it can efficiently catalyze the cycloaddition reaction of CO2 and epoxide under the conditions of no solvent and no co-catalyst at 100 °C and normal pressure. SUMMARY

[0008] In view of the problems of insufficient catalytic activity, need for co-catalyst, harsh reaction conditions or difficulty in catalyst recovery in the existing CO2 and epoxide cycloaddition reaction catalysts, the present application aims to provide a benzene boronic acid functionalized polyionic liquid catalyst and a preparation method thereof. The catalyst has multiple active sites for synergistic effect and can efficiently catalyze the cycloaddition reaction of CO2 and epoxide under mild conditions. The preparation method is simple and environmentally friendly. The present application also provides the application of the catalyst in the cycloaddition reaction of CO2 and epoxide.

[0009] To achieve the above-mentioned purposes, the present application adopts the following technical solutions: A preparation method of a benzene boronic acid functionalized polyionic liquid catalyst, comprising the following steps: (1) Synthesis of benzene boronic acid imidazole ionic liquid monomer (PBIL): 1-vinylimidazole (VIm) and 4-(bromomethyl)benzene boronic acid are dissolved in an organic solvent, heated under nitrogen protection, and after the reaction is completed, the PBIL monomer is obtained by precipitation, washing and drying.

[0010] The organic solvent is acetonitrile; the molar ratio of 1-vinylimidazole to 4-(bromomethyl)benzene boronic acid is (3-5):1, preferably 4:1; the heating reaction temperature is 70-90℃, preferably 80℃; the reaction time is 20-30 hours, preferably 24 hours; the precipitant solvent is diethyl ether, and the white solid is precipitated by settling in a large amount of diethyl ether, and the product PBIL is obtained by vacuum drying after suction filtration.

[0011] (2) Synthesis of phenylboronic acid functionalized polyionic liquid catalyst (PILs): the PBIL monomer obtained in step (1) and a crosslinking agent divinylbenzene (DVB) are dissolved in an organic solvent according to a certain molar ratio, a free radical initiator is added, and a hydrothermal polymerization reaction is carried out in a sealed reaction container. After the reaction is completed, the phenylboronic acid functionalized polyionic liquid catalyst is obtained by washing and drying.

[0012] The molar ratio of the PBIL monomer to DVB is 1:(1-4), preferably 1:2; the free radical initiator is azobisisobutyronitrile (AIBN); the temperature of the hydrothermal polymerization reaction is 90-110°C, preferably 100°C; the reaction time is 20-30 hours, preferably 24 hours; the organic solvent is N,N-dimethylformamide (DMF); the solvent used for washing is anhydrous methanol to remove unreacted raw materials and part of the solvent, and then vacuum filtration and vacuum drying are carried out.

[0013] The application also provides a phenylboronic acid functionalized polyionic liquid catalyst prepared by the above preparation method, and the structural formula is: n=50-200, and m=20-100.

[0014] The catalyst contains imidazole cations, bromide anions (Br⁻) and phenylboronic acid groups (-B(OH)2). The imidazole cations can activate CO2, the Br⁻ can act as a nucleophile to attack the epoxide to make it ring-opening, and the hydroxyl group in the phenylboronic acid group can act as a hydrogen bond donor to further activate the epoxide and promote the ring-opening of the epoxide, thereby realizing the synergistic and efficient catalysis of multiple active sites.

[0015] The application further provides an application of the above phenylboronic acid functionalized polyionic liquid catalyst in the preparation of cyclic carbonates by catalyzing the ring-opening reaction of carbon dioxide and epoxide.

[0016] The conditions of the ring-opening reaction are as follows: the phenylboronic acid functionalized polyionic liquid catalyst is used as a catalyst, the reaction is carried out under a solvent-free condition, the CO2 pressure is normal pressure (1 bar), the reaction temperature is 80-110°C, preferably 90-100°C, and the reaction time is 24-72 hours, and the specific time can be adjusted according to the reactivity of the epoxide.

[0017] The epoxide is at least one selected from 1,2-epoxyhexane, allyl glycidyl ether, n-butyl glycidyl ether, glycidyl methacrylate, phenyl glycidyl ether and styrene oxide.

[0018] Structure characterization of the catalyst The chemical structures of the monomer and the PIL are characterized by FT-IR spectroscopy, as shown in Figure 1The imidazole moiety has C=N and C−N. + The tensile vibration peak appears at 1654 cm. −1 and 1152 cm −1 This confirms the successful incorporation of the imidazole moiety into the polymer structure. (3390cm) −1 The broad and strong peak nearby is the tensile vibration peak of −OH. Additionally, at 962 cm⁻¹... −1 The disappearance of the C−H vibration peak indicates complete polymerization of the unsaturated vinyl groups. These characteristic peaks confirm the successful preparation of PBIL1-DVB2.

[0019] Next, solid-state... 13 The chemical structure of PBIL1-DVB2 was further investigated using C SSNMR spectroscopy. Figure 2 As shown, multiple peaks exist between 12 and 155 ppm in the chemical shift range. The signal near 110 ppm, attributed to unsaturated vinyl groups, disappears, and new peaks appear in the 15–60 ppm range, attributed to alkyl carbons in the macromolecular backbone. Furthermore, aliphatic carbons connecting the imidazole ring resonate in this region. The signal in the 110–150 ppm range originates from aromatic carbon atoms in the imidazole and benzene ring components. Therefore, the results confirm the successful copolymerization of the imidazole phenylboronic acid IL monomer with DVB.

[0020] The thermal stability of phenylboronic acid-functionalized crosslinked PILs materials was evaluated by TGA analysis. Figure 3 As shown, the slight weight loss observed at around 290 °C is attributed to the release of absorbed solvent and water molecules. The weight loss of PILs can be divided into two steps: the first stage occurs at approximately 406 °C, possibly due to the thermal decomposition of the imidazole moiety; the second weight loss occurs after 458 °C, when the polymer backbone completely decomposes. These results indicate that the PIL catalysts possess excellent thermal stability.

[0021] Using SEM ( Figure 4 The microstructure and structure of the PBIL1-DVB2 catalyst were characterized by SEM and EDS spectroscopy. SEM revealed that the P2ImBE catalyst consisted of irregularly shaped nanospheres. The elemental distribution in the PBIL1-DVB2 catalyst was investigated using EDS elemental mapping. Figure 4 (d–g), it can be observed that C, N, O and Br elements are uniformly distributed on the catalyst surface.

[0022] Then, the chemical composition of PBIL1-DVB2 was analyzed by XPS. Figure 5 The full spectrum of a confirms the presence of C, N, B, O, and Br elements in the catalyst. First, the C 1s energy spectrum is deconvolved ( Figure 5(b) Three distinct peaks appear at 283.80, 284.53, and 285.89 eV, corresponding to C−B, C−C / C=C, and C−N / C=N bonds, respectively. Furthermore, the N1s spectrum unconvolutes to two peaks at 399.38 eV and 401.42 eV (b). Figure 5 c), indicating that C=N and C−N + The presence of bonds. B 1s energy spectrum ( Figure 5 d) Two distinct peaks appear at 190.98 eV and 187.62 eV, corresponding to the B−OH and B−C bonds, respectively. These findings confirm the successful synthesis of PBIL1-DVB2, consistent with the expected structure. The Br 3d signal in PBIL1-DVB2 appears at 67.18 eV (3d... 5 / 2 ) and 68.08 eV (3d 3 / 2 () Figure 5 e), indicating the presence of free bromide anions. These results further demonstrate that the phenylboronic acid and imidazole moieties were successfully incorporated into the polymer structure.

[0023] Catalytic performance test of CO2 cycloaddition reaction with epoxide 1. Performance testing of the catalyst in the cycloaddition reaction of CO2 with 1,2-epoxyhexane The catalytic performance of phenylboronic acid-functionalized polymeric liquids (PILs) heterogeneous catalysts for the cycloaddition of 1,2-epoxyhexane with CO2 to form cyclic carbonates was evaluated in detail. The experimental conditions were 1 bar CO2, 60 mg catalyst, 10 mmol 1,2-epoxyhexane, and reaction at 90 °C for 48 hours. The results showed that without the phenylboronic acid-functionalized monomer, the conversion rate of the catalyst PBnIL1-DVB2 obtained by copolymerization of PBnIL and crosslinking agent DVB was 82%. After introducing phenylboronic acid groups into the PILs, the catalytic conversion rate of the catalyst PBIL1-DVB2 obtained by copolymerization of PBIL and crosslinking agent DVB was 99%. This indicates that phenylboronic acid can act as a hydrogen bond donor, activating the epoxy substrate and promoting the catalytic reaction. However, the catalytic conversion rate decreased with increasing crosslinking agent ratio. This is because although increasing the DVB ratio is beneficial for increasing the specific surface area, excessive DVB during polymerization increases the crosslinking degree of the PILs, leading to a reduction in available ionic liquid active sites and thus decreasing the catalytic activity. When ionic liquid and crosslinking agent are copolymerized at a molar ratio of 1:2, catalyst PBnIL1-DVB2 is obtained, which has a CO2 conversion rate of 99%.

[0024] a Reaction conditions: catalyst dosage: 60 mg, epoxide dosage: 10 mmol, temperature: 90°C, time: 48 h, CO2 balloon.b By 1 The conversion and selectivity of the product were detected by H NMR (CDC13, 400MHz).

[0025] 2. Study on the applicability of catalysts to other epoxides Under the optimized conditions, the substrate applicability of PBIL1-DVB2 catalytic system for the chemical fixation of CO2 and epoxides to generate cyclic carbonates was further studied. The catalytic conversion effect of the catalyst on the cycloaddition reaction of different substituent epoxides was tested under an initial CO2 pressure of 1 bar, as shown in Table 4. After prolonging the reaction time, PBIL1-DVB2 had good catalytic activity for the conversion of different substituent epoxides into the corresponding cyclic carbonates (Table 2, items 1-5). Allyl glycidyl ether, butyl glycidyl ether, glycidyl methacrylate and other epoxides were efficiently converted into the corresponding cyclic carbonates after reacting with CO2 at 100 °C for 36 h. The yield of the conversion of the reaction of the sterically hindered styrene oxide and CO2 into the corresponding cyclic carbonate could reach 85% at 100 °C after 72 h.

[0026] The present application has the following beneficial effects: 1. Novel catalyst structure, multiple active sites synergistic effect: The phenylboronic acid functionalized polyionic liquid catalyst prepared by the present application introduces the phenylboronic acid group into the polyionic liquid skeleton, so that the catalyst has imidazole cation, bromide anion (Br⁻) and phenylboronic acid group (-B(OH)2) at the same time. The imidazole cation and Br⁻ can synergistically activate CO2 and epoxide, and the hydroxyl group in the phenylboronic acid group can form a hydrogen bond with the oxygen atom in the epoxide, further polarize the C-O bond, promote the ring-opening of the epoxide, and realize the synergistic catalysis of multiple active sites, which significantly improves the catalytic activity.

[0027] 2. High catalytic activity and selectivity: Under the conditions of no solvent and no co-catalyst, only using the phenylboronic acid functionalized polyionic liquid catalyst of the present application, the cycloaddition reaction of CO2 and various epoxides can be efficiently catalyzed under mild conditions (such as normal pressure CO2, 90 °C), with a conversion rate of 99% and a selectivity of 99%. Compared with the polyionic liquid without phenylboronic acid group, the catalytic activity is significantly improved.

[0028] 3. Simple and easy-to-operate preparation method: The imidazole / phenylboronic acid functionalized PILs catalyst with multiple active sites is synthesized by one-step solvothermal polymerization method using phenylboronic acid imidazole ionic liquid (PBIL) as monomer, divinylbenzene (DVB) as crosslinking agent and AIBN as initiator, which has mild reaction conditions, simple operation and is easy to scale up.

[0029] 4. Mild reaction conditions and good stability: This catalyst can catalyze reactions under ambient pressure CO2 and moderate temperatures without the need for organic solvents or co-catalysts, meeting the requirements of green chemistry and sustainable development. The resulting polyionic liquid catalyst exhibits good thermal and chemical stability, which is beneficial for recovery and reuse. Attached Figure Description

[0030] Figure 1 FT-IR spectra of PBIL and PBIL1-DVB2; Figure 2 13C SSNMR spectrum of PIL1-DVB2; Figure 3 TGA curves of PILs; Figure 4 SEM plot (ac) and element mapping plot (dg) of PBIL1-DVB2; Figure 5 (a) XPS full spectrum of PIL1-DVB2; (b) C1s spectrum; (c) N1s spectrum; (d) B1s spectrum; (e) Br3d spectrum. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0032] Example 1: Preparation of phenylboronic acid functionalized polyionic liquid catalyst (PIL1-DVB2) 1. Synthesis of phenylboronic acid imidazole ionic liquid monomer (PBIL) 1-Vinylimidazole (VIm, 1.88 g, 20 mmol) and 4-(bromomethyl)phenylboronic acid (1.07 g, 5 mmol) were dissolved in 50 mL of acetonitrile (MeCN) in a two-necked flask. After three evacuations and nitrogen purging, the mixture was magnetically stirred in an oil bath at 80 °C for 24 h under nitrogen protection. The reaction was stopped, cooled to room temperature, and the reaction solution was precipitated with diethyl ether, resulting in a white solid. The solid was filtered and then dried in a vacuum oven at 50 °C for 24 h to give product PBIL (0.96 g), with a yield of approximately 62%.

[0033] 2. Synthesis of PILs catalysts functionalized with phenylboronic acid A catalyst with a PBIL to DVB molar ratio of 1:2 (denoted as PIL1-DVB2) was prepared as follows: PBIL monomer (0.62 g, 2 mmol) and divinylbenzene (DVB, 0.52 g, 4 mmol) were weighed and dissolved in 15 mL of N,N-dimethylformamide (DMF). Azobisisobutyronitrile (AIBN, 0.11 g, 0.67 mmol) was added as a free radical initiator, and the mixture was stirred until homogeneous. The mixture was transferred to a 20 mL hydrothermal reactor, sealed, and placed in a 100 °C oven for 24 h. After the reaction, the mixture was cooled to room temperature to obtain a yellow paste-like solid. The solid was washed several times with anhydrous methanol to remove unreacted raw materials and residual solvent. After vacuum filtration, the obtained solid was dried in a 70 °C vacuum drying oven for 24 h to obtain the yellow solid catalyst PIL1-DVB2 (1.03 g), with a yield of approximately 91%. The structure of PBIL1-DVB2 is characterized as follows. Figures 1-5 .

[0034] Example 2: Synthesis of phenylboronic acid functionalized polyionic liquid catalyst (PIL1-DVB4) Following the method of Example 1, the molar ratio of PBIL monomer to DVB was changed to 1:4 (PBIL 0.62 g, 2 mmol; DVB 1.04 g, 8 mmol), while other conditions remained unchanged, to prepare catalyst PIL1-DVB4.

[0035] Comparative Example 1: Synthesis of a polyionic liquid catalyst (PBnIL1-DVB2) without phenylboronic acid groups Following the method of Example 1, the PBIL monomer was replaced with PBnIL monomer (1-vinyl-3-benzylimidazole bromide), and the molar ratio of PBnIL monomer to DVB was 1:2. Other conditions remained unchanged, resulting in the preparation of a polyionic liquid catalyst PBnIL1-DVB2 without phenylboronic acid groups. The synthesis method of PBnIL monomer was as follows: benzyl bromide (10 g, 58 mmol) was dissolved in 10 mL of diethyl ether, and 1-vinylimidazole (4.6 g, 49 mmol) was added dropwise under stirring in an ice-water bath. After reacting the mixture at room temperature for 24 h, the precipitate was obtained by centrifugation, washed with diethyl ether, and vacuum dried for 6 h to obtain a white powdery PBnIL monomer. Yield: 11.43 g, 88%.

[0036] Synthetic route of PBnIL monomer: Example 3: Performance test of catalyst in the cycloaddition reaction of CO2 with 1,2-epoxyhexane In a 25 mL Schlenk tube, 60 mg of the catalyst PIL1-DVB2 prepared in Example 1 and 10 mmol of 1,2-epoxyhexane were added sequentially. The Schlenk tube was connected to a CO2 balloon (providing 1 bar CO2 pressure), and after purging the air from the tube three times, it was placed in a 90°C oil bath and magnetically stirred for 48 h. After the reaction was complete, the mixture was cooled to room temperature, and the reaction solution was removed. The conversion and selectivity of the products were detected by ¹H NMR (CDCl3 as solvent, 400 MHz). The results showed that the conversion of 1,2-epoxyhexane was 99%, and the selectivity for cyclic carbonates was 99%.

[0037] Example 4: Effect of different catalysts on the performance of the cycloaddition reaction of CO2 with 1,2-epoxyhexane The catalytic performance of the catalysts prepared in Example 1 (PIL1-DVB1), Example 2 (PIL1-DVB4), and Comparative Example 1 (PBnIL1-DVB2) was investigated under the reaction conditions of Example 3. The results are shown in the table below: As shown in the table above, the catalytic activity of the catalyst was significantly improved after the introduction of phenylboronic acid groups (PIL1-DVB2 vs PBnIL1-DVB2), indicating that the introduction of phenylboronic acid groups promotes the catalytic reaction. Meanwhile, the ratio of the crosslinking agent DVB also affects the catalytic activity. When the molar ratio of PBIL to DVB was 1:2, the catalyst PIL1-DVB2 exhibited the best catalytic activity. Further increasing the DVB ratio (e.g., 1:4) resulted in a decrease in catalytic activity because excessive crosslinking led to the encapsulation or reduction of active sites.

[0038] Example 5: Applicability study of catalyst PIL1-DVB2 to different epoxides Following the reaction conditions of Example 3 (catalyst PIL1-DVB2 60 mg, epoxide 10 mmol, CO2 balloon, reaction temperature adjusted to 100°C according to the substrate, reaction time adjusted according to the substrate), the catalytic effect of catalyst PIL1-DVB2 on different epoxides (such as allyl glycidyl ether, n-butyl glycidyl ether, glycidyl methacrylate, styrene oxide, or phenyl glycidyl ether) was investigated. The results showed that this catalyst exhibited good catalytic activity for various substituted epoxides, with conversions generally exceeding 85% and selectivity maintained at 99%. For example, for sterically hindered styrene oxide, after reacting at 100°C for 72 h, the conversion reached 85% and the selectivity 99%.

[0039] In summary, using phenylboronic acid imidazole ionic liquid (PBIL) as the monomer, divinylbenzene (DVB) as the crosslinking agent, and AIBN as the initiator, a multi-site imidazole / phenylboronic acid functionalized PIL catalyst was synthesized in one step via solvothermal polymerization. This metal-free heterogeneous catalyst exhibits excellent catalytic performance in the absence of a co-catalyst. The effect of the monomer-to-initiator ratio on CO2 adsorption performance and cycloaddition reaction was investigated. The results showed that the introduction of phenylboronic acid significantly improved CO2 adsorption performance and cycloaddition catalytic activity. Furthermore, the catalyst PBIL1-DVB2, obtained with a PBIL:DVB molar ratio of 1:2, achieved a 99% conversion rate in the reaction of 1,2-epoxyhexane at 1 bar CO2 and 90 °C for 48 h.

Claims

1. A method for preparing a phenylboronic acid-functionalized polyionic liquid catalyst, characterized in that, Includes the following steps: (1) Synthesis of phenylboronic acid imidazole salt ionic liquid monomer: 1-vinylimidazolium and 4-(bromomethyl)phenylboronic acid were dissolved in an organic solvent and heated under nitrogen protection. After the reaction was completed, the monomer was obtained by precipitation, washing and drying. (2) Synthesis of phenylboronic acid functionalized polyionic liquid catalyst: The PBIL monomer obtained in step (1) and the crosslinking agent divinylbenzene are dissolved in an organic solvent, a free radical initiator is added, and a hydrothermal polymerization reaction is carried out. After the reaction is completed, the catalyst is washed and dried to obtain the phenylboronic acid functionalized polyionic liquid catalyst.

2. The preparation method according to claim 1, characterized in that, In step (1), the organic solvent is acetonitrile; the molar ratio of 1-vinylimidazolium to 4-(bromomethyl)phenylboronic acid is (3-5):1; the heating reaction temperature is 70-90℃ and the reaction time is 20-30 hours; the solvent used for precipitation is diethyl ether.

3. The preparation method according to claim 1 or 2, characterized in that, In step (2), the molar ratio of PBIL monomer to divinylbenzene is 1:(1-4); the free radical initiator is azobisisobutyronitrile; the temperature of the hydrothermal polymerization reaction is 90-110℃, and the reaction time is 20-30 hours; the organic solvent is N,N-dimethylformamide.

4. The preparation method according to claim 3, characterized in that, In step (2), the molar ratio of PBIL monomer to divinylbenzene is 1:

2.

5. A phenylboronic acid-functionalized polyionic liquid catalyst prepared by the preparation method according to any one of claims 1-4, characterized in that, The catalyst contains hydroxyl, imidazole, and Br⁻ synergistic catalytic active sites; the structural formula of the phenylboronic acid-functionalized polyionic liquid catalyst is: ,n=50~200,m=20~100。 6. The application of the phenylboronic acid functionalized polyionic liquid catalyst of claim 5 in the catalytic cycloaddition reaction of carbon dioxide with epoxide to prepare cyclic carbonates.

7. The application according to claim 6, characterized in that, The conditions for the cycloaddition reaction are as follows: using the phenylboronic acid functionalized polyionic liquid catalyst as the catalyst, under solvent-free conditions, with CO2 pressure at atmospheric pressure, reaction temperature at 80-110℃, and reaction time at 24-72 hours.

8. The application according to claim 6 or 7, characterized in that, The epoxide is selected from at least one of 1,2-epoxyhexane, allyl glycidyl ether, n-butyl glycidyl ether, glycidyl methacrylate, styrene oxide, or phenyl glycidyl ether.

Images