A magnetic composite material supported functionalized ionic liquid catalyst and its application

Abstract

The application provides a magnetic composite material loaded functionalized ionic liquid catalyst. The catalyst comprises a magnetic composite material carrier and a functionalized ionic liquid; wherein the functionalized ionic liquid is a sugar-based functionalized imidazole ionic liquid, and the imidazole structure of the ionic liquid is N-alkyl imidazole. The catalyst has the advantages of high catalytic activity, strong stability, difficulty in loss of active components and recyclability.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical engineering, specifically relating to a magnetic composite material supported on a functionalized ionic liquid catalyst and its application. Background Technology

[0002] Cyclic carbonates are high-performance organic solvents and intermediates, commonly used in many fields such as gas separation, plastics, and electrochemistry. Glyceryl carbonate, ethylene carbonate, propylene carbonate, and 1,2-butenyl carbonate are some of the most representative products. Ethylene carbonate (EC) and propylene carbonate (PC) are two fundamental materials in the electronic chemicals family, primarily used as chemical solvents in new energy vehicle batteries, and are currently known as the most environmentally friendly chemical solvents.

[0003] The preparation of cyclic carbonates via cycloaddition reactions using epoxides and carbon dioxide as raw materials is an environmentally friendly and atom-economical process. Simultaneously, the use of carbon dioxide as a raw material addresses carbon emission issues. From a resource utilization perspective, carbon dioxide, as the world's most abundant and inexpensive carbon resource, plays a crucial role in developing green carbon dioxide utilization technologies, creating a green and high-tech fine chemical industry chain, and increasing product added value, which has significant economic and environmental implications. Currently, catalysts used for cycloaddition reactions mainly include organic catalysts, ionic liquids, metal-organic frameworks, porous organic polymers, and transition metal complexes. Among these, homogeneous catalysts exhibit high catalytic activity. However, a major problem with homogeneous catalysts, such as ionic liquids, is the presence of residual halogen atoms in the cyclic carbonates, which reduces product quality and limits their application as high-quality raw materials. Furthermore, the separation process using homogeneous catalysts requires additional separation equipment, increasing investment costs. Separation using distillation columns or thin-film evaporators involves high temperatures in the distillation column bottom and inside the thin-film evaporator. Under high temperatures and in the presence of ionic liquids, carbonates are prone to decomposition and polymerization, generating impurities. Carbonates containing certain impurities, when combined with additives, exhibit discoloration, with the color deepening over time, affecting the quality of the electrolyte product.

[0004] To address the aforementioned issues, heterogeneous catalysts have attracted significant attention. Currently, commonly used heterogeneous catalysts include supported ionic liquid catalysts, polymeric catalysts, metal oxide catalysts, molecular sieves, and clay-based catalysts. Patent CN 101265253 B discloses a heterogeneous catalytic synthesis method for preparing cyclic carbonates via the cycloaddition reaction of carbon dioxide with epoxides. This method uses a metal composite oxide obtained by calcining Zn-M-Al hydrotalcite as a catalyst, where M is an alkaline earth metal. An organic tertiary amine is used as both a solvent and a co-catalyst. Under initial carbon dioxide pressures of 0.1-6 MPa and reaction temperatures of 100-180 °C, cyclic carbonates can be prepared with high selectivity exceeding 97%. This catalyst is simple to prepare, halogen-free, and reusable, but its catalytic performance is relatively poor. Patent CN 108097309 B discloses a method for synthesizing propylene carbonate using activated carbon as a support and a nitrogen-containing polymer as the active center as a catalyst. Under reaction conditions of 120℃ and 2MPa, the conversion rate can reach 97% and the selectivity 99%. However, this method suffers from nitrogen loss during the reaction, making subsequent separation difficult. Patent CN 101474576A discloses a reaction system for synthesizing cyclic carbonates, using the metal-organic coordination polymer MOF-5 as a co-catalyst. This system operates at temperatures of 30-80℃ and pressures of 2-12MPa. Compared to traditional methods, this catalytic system offers milder reaction conditions, higher yield and selectivity, and the ability to be reused through simple filtration. It effectively catalyzes cycloaddition reactions, but its preparation cost and stability need further improvement. Patent CN 106831595 B discloses a method for synthesizing cyclic carbonates using benzylimidazolium salt ionic liquid catalysis. The reaction pressure is 1-5 MPa and the reaction temperature is 100-150℃. In this reaction process, the cationic active groups and anions work synergistically to achieve a high-efficiency and high-selectivity catalytic reaction with a product yield of 94.91%. However, this ionic liquid catalyst has few active sites, and the active sites on the supported catalyst are very easy to fall off during use.

[0005] Based on the current application status of heterogeneous catalysts, problems such as low catalytic activity, poor stability, and easy loss of active components still exist in the synthesis of cyclic carbonates. Therefore, the preparation of highly efficient heterogeneous ionic liquid catalysts with high catalytic activity, good stability, and recyclability has become an urgent problem to be solved in the research on the synthesis of cyclic carbonates. Summary of the Invention

[0006] To address the shortcomings of existing technologies, one objective of this invention is to provide a magnetic composite material-supported functionalized ionic liquid catalyst. This catalyst possesses advantages such as high catalytic activity, strong stability, minimal loss of active components, and recyclability.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] A magnetic composite material supported functionalized ionic liquid catalyst, the catalyst comprising a magnetic composite material support and a functionalized ionic liquid; wherein the functionalized ionic liquid is a glycosyl-functionalized imidazole ionic liquid, its imidazole structure being N-alkylimidazole, and it has the following structure:

[0009]

[0010] Among them, anion X - It is one or more of halogen elements, halogen-containing groups, oxygen-sulfur groups, and carboxyl groups, preferably X. - For I - Cl - ,Br - One or more of the following; R1 and R2 are each independently selected from one of the C1-C10 alkyl groups.

[0011] In the catalyst prepared by this invention, the glycosyl-functionalized ionic liquid imidazole is linked to glycosyl compounds such as glucose, containing multiple hydroxyl groups. On the one hand, this disperses the active sites of the ionic liquid, improving its utilization rate; on the other hand, the multiple hydroxyl groups can form hydrogen bonds with epoxides, thereby activating the epoxides. The H atoms in the catalyst form intermolecular hydrogen bonds with the negatively charged O atoms in the raw material PO, polarizing and stretching the CO bonds. The anions nucleophilically attack the less sterically hindered C atoms in PO, causing PO to open its ring and form an intermediate. Carbon dioxide inserts into the intermediate, generating the product carbonate through intramolecular nucleophilic attack.

[0012] In one embodiment of the present invention, the magnetic composite material is a yolk-shell type magnetic composite carbon sphere with a mesoporous structure. Preferably, the magnetic core of the carbon sphere is a magnetic nanoparticle, and the shell is a carbonized product of phenolic resin. Preferably, the magnetic nanoparticle is one or more of magnetic metal oxides, magnetic elemental metals, and magnetic metal alloys, preferably iron oxide and / or Fe3O4. Preferably, the phenolic resin is a condensation of phenolic compounds and aldehyde compounds. Preferably, the phenolic compounds include one or more of resorcinol, cresol, phenylphenol, and bisphenol A, and the aldehyde compounds include one or more of acetaldehyde, paraformaldehyde, and furfural. It is known in the art that the magnetic nanoparticles can be prepared by a hydrothermal method, with the addition of dispersant PSSMA during the preparation process to improve the dispersion and uniformity of the particles.

[0013] In one specific embodiment of the present invention, the magnetic composite material has an average particle size of 2-80 μm, a shell thickness of 0.6-20 μm, and a specific surface area of ​​400-1000 m². 2 / g, with an average pore size of 2-50nm. In this field, the specific specifications of the support can be adjusted according to the specific equipment used for the catalyst application.

[0014] Another object of the present invention is to provide a method for preparing a catalyst.

[0015] A method for preparing the above-mentioned catalyst, the method comprising the following steps:

[0016] S1: Prepare an amino-containing chloroalkylimidazolium via alkylimidazolium, which is then reacted with a lactone of a glycosyl compound via an epoxy ring-opening reaction to obtain a glycosyl-functionalized imidazolium ionic liquid.

[0017] S2: Using phenolic resin as a carbon source, in-situ polymerization was carried on the surface of magnetic nanoparticles, and after carbonization, an egg yolk-eggshell type magnetic composite material was prepared.

[0018] S3: The target catalyst is obtained by loading glycosylated imidazole ionic liquid onto the surface of a magnetic composite material via esterification reaction.

[0019] In one embodiment of the present invention, the S1 alkylimidazolium is reacted with an amine salt to prepare a chloroalkylimidazolium containing an amino group; preferably, the amine salt is a halogen-substituted aliphatic amine, more preferably 3-chloropropylamine.

[0020] In one embodiment of the present invention, the glycosyl compound of S1 is a monosaccharide and / or a disaccharide, preferably one or more of glucose, fructose, sucrose, and maltose.

[0021] For example, in step S1, alkylimidazolium and 3-chloropropylamine hydrochloride are dissolved in acetonitrile, reacted, washed, and filtered to obtain chloroalkylimidazolium containing an amino group; the obtained chloroalkylimidazolium is dissolved in ethanol with gluconolactone, and after an epoxy ring-opening reaction, imidazole gluconamide is obtained, thereby achieving the combination of glucose and imidazole ionic liquid.

[0022] In one embodiment of the present invention, the S2 is carbonized and then etched to remove silicon.

[0023] In one embodiment of the present invention, the shell of the magnetic composite material obtained in S2 has a mesoporous structure.

[0024] For example, in step S2, phenolic resin is used as the carbon source, tetraethyl orthosilicate is added as the silicon precursor, and cetyltrimethylammonium bromide surfactant is added as an auxiliary reagent. The mixture is loaded onto the surface of magnetic nanoparticles via in-situ polymerization. After carbonization, the silicon is removed by etching with sodium hydroxide solution, resulting in a yolk-shell type magnetic composite carbon sphere with a mesoporous shell structure. The mesoporous pores and the cavity between the core and shell of the magnetic composite material increase the contact area with the functionalized ionic liquid, while the protective effect of the core-shell structure reduces the loss of active components in the ionic liquid catalyst.

[0025] In one embodiment of the present invention, the S3 magnetic composite material is first subjected to acidification treatment.

[0026] In one embodiment of the invention, S3 is dehydrated and esterified in concentrated acid.

[0027] In one embodiment of the present invention, the catalyst particle size obtained by S3 is 10-100 μm.

[0028] For example, in step S3, the magnetic composite material is acidified in concentrated nitric acid, washed until neutral, and then carboxyl groups are attached to the surface of the magnetic composite carbon spheres. The above-mentioned glycosylated imidazole ionic liquid and the magnetic composite carbon spheres are dissolved in concentrated sulfuric acid, and after esterification reaction, the ionic liquid is loaded onto the surface of the magnetic composite material to obtain a magnetic composite material supported on a functionalized ionic liquid catalyst.

[0029] Another object of the present invention is to provide a method for preparing cyclic carbonates.

[0030] A method for preparing a cyclic carbonate, wherein the preparation method uses the above-mentioned catalyst, or a catalyst prepared by the above method, wherein the mass ratio of catalyst to epoxide is 0.1-15%; the reaction temperature is 50-150℃, the reaction pressure is 0.1-3 MPaG, and the reaction time is 1-24 h; optionally, after the reaction is completed, the organic phase and the catalyst phase are separated into liquid / solid phases under the action of an external magnetic field for recovery and recycling of the catalyst.

[0031] Another object of the present invention is to provide the use of a magnetic composite material supported on a functionalized ionic liquid catalyst.

[0032] The use of a magnetic composite material supported functionalized ionic liquid catalyst, wherein the catalyst is the catalyst described above, or a catalyst prepared by the method described above, and the catalyst is used for the catalytic synthesis of cyclic carbonates, preferably for the synthesis of ethylene carbonate, propylene carbonate, and glycerol carbonate.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The supported glycosyl functionalized ionic liquid catalyst provided by the present invention has both polyhydroxy and polycarboxyl groups, and has a good synergistic effect with halide anions, thereby improving the catalytic activity of cycloaddition reactions.

[0035] (2) This invention utilizes the hydrogen bonding between hydroxyl and carboxyl groups to form a network confinement space. At the same time, the mesoporous pores and yolk-shell structure of the magnetic composite carbon spheres on the support expand the range of the confinement space, which can effectively reduce the loss of active components of the catalyst and improve the stability of the catalyst.

[0036] (3) The magnetic composite material supported functionalized ionic liquid catalyst provided by the present invention can achieve rapid separation and recycling of the catalyst by applying an external magnetic field, which is convenient to operate; compared with the separation of traditional homogeneous catalysts, it can avoid impurities generated by high temperature and improve product quality. Detailed Implementation

[0037] The following examples are intended to illustrate the present invention and not to further limit the invention.

[0038] Raw material information: Ammonia, 25wt%, AR; Resorcinol, AR; Formaldehyde solution, AR; Ferric chloride hexahydrate, AR; Sodium poly(4-styrenesulfonic acid-copoly-maleic acid) (PSSMA), AR; Anhydrous sodium acetate, AR; Tetraethyl silicate, AR; Sodium hydroxide, 98%; Ethylene glycol, 98%; Cetyltrimethylammonium bromide, AR; Concentrated sulfuric acid, 98%; 1-Methylimidazole, 99%; 3-Chloropropylamine hydrochloride, 98%; Gluconolactone, 99%; Concentrated nitric acid, 98%; Acetonitrile, 99.5%; Propylene oxide, 99%; Beijing Innochem Technology Co., Ltd.

[0039] Equipment Information: Electric heating drying oven, DHG-9036A; Hydrothermal reactor, KH-100; Temperature-controlled digital display constant temperature water bath, HH-4; Vacuum tube furnace, QSH-VTF-1200T; High-speed benchtop centrifuge, TGL-10B.

[0040] Analytical instrument information: Nuclear magnetic resonance spectrometer, model AVANCE NEO 400M, manufacturer Bruker; Gas chromatograph, model 7890B, manufacturer Agilent.

[0041] Gas chromatography analysis method: injection port temperature 240℃, split ratio 50:1; column oven temperature program: 60℃ for 10 min, increase to 160℃ at 10℃ / min, increase to 220℃ at 20℃ / min; detector is FID, detection temperature is 240℃.

[0042] Example 1

[0043] (1) Preparation of magnetic nuclei: 2.04 g of ferric chloride hexahydrate was dissolved in 60 mL of ethylene glycol, then 3.6 g of anhydrous sodium acetate was added, and the mixture was stirred vigorously for 30 min. Then, 0.9 g of dispersant PSSMA was added, and the mixture was stirred vigorously for another 30 min to ensure homogeneity. The homogeneous brownish-yellow solution was transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene (PTFE), and the reaction was carried out hydrothermally at 200 °C for 10 h. After the reaction was complete, the black precipitate was separated from the reaction solution using a neodymium magnet. The generated Fe3O4 nanoparticles were washed three times sequentially with deionized water and ethanol, and then dried.

[0044] (2) Preparation of magnetic composite carbon spheres: The prepared Fe3O4 magnetic nanoparticles were dispersed in 84 mL of a mixed solvent of ethanol and water (volume ratio 3:4). 0.6 mL of ammonia water was added as an alkaline catalyst, followed by the addition of 0.6 g of resorcinol, 0.6 g of surfactant CTAB, 0.84 mL of formaldehyde solution, and 4 mL of silicon source TEOS. After thorough mixing, the mixture was stirred and reacted in a 40 °C water bath for 24 h. The resulting solution was then transferred to a polytetrafluoroethylene-lined hydrothermal reactor and placed in a 100 °C oven for hydrothermal reaction for 24 h. After the reaction was completed, impurities were removed by washing with deionized water and anhydrous ethanol. The product was then dried at 120°C and carbonized at 600°C for 4 hours under a nitrogen atmosphere. The surfactant CTAB was removed during carbonization, and RF was carbonized. Then, the hard template silica in the material was etched away by stirring in 50 ml of 1 mol / L sodium hydroxide solution in a 50°C water bath for 60 minutes, yielding magnetic composite carbon spheres with an average particle size of 55 μm, a shell thickness of 7.2 μm, and a specific surface area of ​​821 m². 2 / g, with an average pore size of 37nm.

[0045] (3) Preparation of glycosylated imidazole ionic liquid: 10 g of 1-methylimidazolium and 15 g of 3-chloropropylamine hydrochloride were dissolved in 50 ml of acetonitrile. The mixture was stirred and refluxed at 80 °C under a nitrogen atmosphere for 24 h. After cooling to room temperature, the lower solid was washed with diethyl ether and filtered to obtain 1-aminopropyl-3-methylimidazolium chloride. 20 g of 1-aminopropyl-3-methylimidazolium chloride and 30 g gluconolactone were dissolved in 100 ml of ethanol and heated and refluxed at 80 °C for 24 h. After an epoxy ring-opening reaction, 3-methylimidazolium chloride propylglucamide was obtained, i.e., glycosylated imidazole ionic liquid. The peak position was determined to be 1.6 (m, 2) by 1H NMR spectroscopy (400 MHz, DMF-D6). 2.8 (s, 1H); 3.2 (t, 2H); 3.37-3.38 (m, 2H); 3.56-3.72 (m, 10H); 4.24 (d, 1H); 4.7 (t, 2H); 7.75 (s, 1H); 7.76 (s, 1H); 8.03 (s, 1H); 8.92 (s, 1H); The peak positions of the carbon NMR spectrum are: 173.2; 137; 123; 122.8; 72.8; 71.9; 71.4; 69.8; 64.4; 45.6; 38.6; 37.1; 28.6.

[0046] (4) Preparation of functionalized ionic liquid catalyst supported on magnetic composite material: 10g of magnetic composite material was placed in 50ml of 98% concentrated nitric acid for 12h for acidification treatment. After washing with pure water until neutral, carboxyl groups were connected to the surface of the magnetic composite carbon spheres. 20ml of the above-mentioned glycosylated imidazole ionic liquid and 10g of acidified magnetic composite material were placed in 50ml of 98% concentrated sulfuric acid and esterified at 80℃ for 6h to obtain the ionic liquid catalyst supported on the magnetic composite material with a particle size of 78μm.

[0047] (5) Catalyst for the synthesis of cyclic carbonates: Propylene carbonate was prepared by the addition reaction of carbon dioxide and propylene oxide in a batch reactor. The reactor volume was 500 mL, and the catalyst loading amount was 2% of the mass of propylene oxide. The specific reaction conditions were: reaction temperature 100℃, reaction pressure 1.0 MPa(G), stirring speed 300 r / min, and reaction time 2 h. After that, the mass flow meter reading of carbon dioxide was observed to be unchanged, and the reaction was completed. The catalyst and product were separated by an external magnet. The purity of the product propylene carbonate was measured to be 99.0%, the yield of propylene carbonate was calculated to be 99.5%, and the selectivity was 99.5%. After the catalyst was recycled 5 times, the yield of propylene carbonate was still above 98%.

[0048] Example 2

[0049] (1) Preparation of magnetic cores: 14.5 g Fe(NO3)3·9H2O and 8.8 g Fe2(SO4)3 were dissolved in 400 mL of distilled water and stirred until completely dissolved. After heating to 40 °C, 24 mL of concentrated ammonia was slowly added dropwise to obtain a black precipitate. The precipitate was stirred at 60 °C for 30 min, filtered and washed until neutral, and the black precipitate was separated from the reaction solution using a neodymium magnet. Then, the precipitate was placed in an oven and pyrolyzed at 85 °C for 12 h to obtain γ-Fe2O3 nanoparticles.

[0050] (2) Preparation of magnetic composite carbon spheres: The prepared γ-Fe2O3 magnetic nanoparticles were dispersed in 84 mL of ethanol-water mixed solvent (volume ratio 3:4), and 0.6 mL of ammonia water was added as an alkaline catalyst. Then, 1.0 g of bisphenol A, 0.6 g of surfactant CTAB, 0.7 mL of furfural solution and 4 mL of silicon source TEOS were added sequentially. After mixing evenly, the mixture was stirred and reacted in a 40 °C water bath for 24 h. The mixed solution was then transferred to a polytetrafluoroethylene-lined hydrothermal reactor and placed in a 100 °C oven for hydrothermal reaction for 24 h. After the reaction, impurities were removed by washing with deionized water and anhydrous ethanol. The product was then dried at 120°C and carbonized at 600°C for 4 hours under a nitrogen atmosphere. The surfactant CTAB was removed during carbonization, and the phenolic resin was carbonized. Then, the hard template silica in the material was etched away by stirring in 50 ml of 1 mol / L sodium hydroxide solution in a 50°C water bath for 60 minutes, yielding magnetic composite carbon spheres with an average particle size of 71 μm, a shell thickness of 15.3 μm, and a specific surface area of ​​625 m². 2 / g, with an average pore size of 22nm.

[0051] (3) Preparation of glycosylated imidazole ionic liquid: 9 g of 1-octylimidazole and 12 g of 3-chloropropylamine sulfate were dissolved in 50 ml of acetonitrile and stirred and refluxed at 150 °C under a nitrogen atmosphere for 24 h. After cooling to room temperature, the lower solid was washed with diethyl ether and filtered to obtain sulfated-1-aminopropyl-3-octylimidazole; 20 g of sulfated-1-aminopropyl-3-octylimidazole and 15 g of sucrose were dissolved in 100 ml of ethanol / water solution (ethanol concentration 50%) and heated and refluxed at 70 °C for 24 h. The glycosylated imidazole ionic liquid was obtained by epoxy ring-opening reaction.

[0052] (4) Preparation of functionalized ionic liquid catalyst supported on magnetic composite material: 10g of magnetic composite material was placed in 50ml of 98% concentrated nitric acid for 12h for acidification treatment. After washing with pure water until neutral, carboxyl groups were connected to the surface of the magnetic composite carbon spheres. 20ml of the above-mentioned glycosylated imidazole ionic liquid and 10g of acidified magnetic composite material were placed in 50ml of 98% concentrated sulfuric acid and esterified at 80℃ for 12h to obtain the ionic liquid catalyst supported on the magnetic composite material with a particle size of 95μm.

[0053] (5) Catalyst for the synthesis of cyclic carbonates: Propylene carbonate was prepared by the addition reaction of carbon dioxide and propylene oxide in a batch reactor. The reactor volume was 500 mL, and the catalyst loading amount accounted for 12% of the mass of propylene oxide. The specific reaction conditions were: reaction temperature 80℃, reaction pressure 2.0 MPa (G), stirring speed 300 r / min, and reaction time 4 h. After that, the mass flow meter reading of carbon dioxide was observed to be unchanged, and the reaction was completed. The catalyst and product were separated by an external magnet.

[0054] Example 3

[0055] (1) The preparation of the magnetic core is the same as in Example 1.

[0056] (2) The preparation of magnetic composite carbon spheres is the same as in Example 1.

[0057] (3) Preparation of glycosylated imidazole ionic liquid: 10 g of 1-methylimidazolium, 10 g of 1-aminocyclopropanecarboxylic acid and 10 mL of acetic acid were dissolved in 50 mL of acetonitrile. The mixture was stirred and refluxed at 100 °C under a nitrogen atmosphere for 24 h. After cooling to room temperature, the lower solid was washed with diethyl ether and filtered to obtain acetate-1-cycloaminopropyl-3-methylimidazolium. 20 g of acetate-methylimidazolium and 30 g of gluconolactone were dissolved in 100 mL of ethanol and heated and refluxed at 80 °C for 24 h. The glycosylated imidazole ionic liquid was obtained by epoxy ring-opening reaction.

[0058] (4) Preparation of functionalized ionic liquid catalyst supported on magnetic composite material: 10g of magnetic composite material was placed in 50ml of 98% concentrated nitric acid for 12h for acidification treatment. After washing with pure water until neutral, carboxyl groups were connected to the surface of the magnetic composite carbon spheres. 20ml of the above-mentioned glycosylated imidazole ionic liquid and 10g of acidified magnetic composite material were placed in 50ml of 98% concentrated sulfuric acid and esterified at 80℃ for 3h to obtain the ionic liquid catalyst supported on the magnetic composite material. The average particle size of the catalyst was 67μm.

[0059] (5) Catalyst for the synthesis of cyclic carbonates: Propylene carbonate was prepared by the addition reaction of carbon dioxide and propylene oxide in a batch reactor. The reactor volume was 500 mL, and the catalyst loading amount accounted for 5% of the mass of propylene oxide. The specific reaction conditions were: reaction temperature 60℃, reaction pressure 3.0 MPa(G), stirring speed 300 r / min, and reaction time 6 h. After that, the mass flow meter reading of carbon dioxide was observed to be unchanged, and the reaction was completed. The catalyst and product were separated by an external magnet.

[0060] Example 4

[0061] (1) The preparation of the magnetic core is the same as in Example 1.

[0062] (2) The preparation of magnetic composite carbon spheres is the same as in Example 1.

[0063] (3) Preparation of glycosylated imidazole ionic liquid: 10 g of 1-methylimidazolium and 7 g of 7-bromoheptane-1-amine hydrobromide were dissolved in 50 ml of acetonitrile and stirred under nitrogen atmosphere at 100 °C for 24 h. After cooling to room temperature, the lower solid was washed with diethyl ether and filtered to obtain brominated 1-amino-3-methylimidazolium. 20 g of brominated 1-amino-3-methylimidazolium and 8 g of β-cyclodextrin were dissolved in 100 ml of ethanol / water solution (ethanol concentration 50%) and heated under reflux at 100 °C for 24 h. Glycosylated imidazole ionic liquid was obtained by epoxy ring-opening reaction.

[0064] (4) Preparation of functionalized ionic liquid catalyst supported on magnetic composite material: 10g of magnetic composite material was placed in 50ml of 98% concentrated nitric acid for 12h for acidification treatment. After washing with pure water until neutral, carboxyl groups were connected to the surface of the magnetic composite carbon spheres. 20ml of the above-mentioned glycosylated imidazole ionic liquid and 10g of acidified magnetic composite material were placed in 50ml of 98% concentrated sulfuric acid and esterified at 80℃ for 12h to obtain the ionic liquid catalyst supported on the magnetic composite material. The average particle size of the catalyst was 92μm.

[0065] (5) Catalyst for the synthesis of cyclic carbonates: Propylene carbonate was prepared by the addition reaction of carbon dioxide and propylene oxide in a batch reactor. The reactor volume was 500 mL, and the catalyst loading amount accounted for 10% of the mass of propylene oxide. The specific reaction conditions were: reaction temperature 80℃, reaction pressure 1.0 MPa (G), stirring speed 300 r / min, and reaction time 4 h. After that, the mass flow meter reading of carbon dioxide was observed to be unchanged, and the reaction was completed. The catalyst and product were separated by an external magnet.

[0066] Example 5

[0067] (1) The preparation of the magnetic core is the same as in Example 1.

[0068] (2) The preparation of magnetic composite carbon spheres is the same as in Example 1.

[0069] (3) Preparation of glycosylated imidazole ionic liquid: 10 g of 1-methylimidazolium and 8 g of 7-chloroheptane hydrochloride were dissolved in 50 ml of acetonitrile and stirred under reflux at 100 °C for 24 h under a nitrogen atmosphere. After cooling to room temperature, the lower solid was washed with diethyl ether and filtered to obtain 1-amino-3-methylimidazolium chloride. 20 g of 1-amino-3-methylimidazolium chloride and 30 g of gluconolactone were dissolved in 100 ml of ethanol and heated under reflux at 100 °C for 24 h. The glycosylated imidazole ionic liquid was obtained by epoxy ring-opening reaction.

[0070] (4) Preparation of functionalized ionic liquid catalyst supported on magnetic composite material: 10g of magnetic composite material was placed in 50ml of 98% concentrated nitric acid for 12h for acidification treatment. After washing with pure water until neutral, carboxyl groups were connected to the surface of the magnetic composite carbon spheres. 20ml of the above-mentioned glycosylated imidazole ionic liquid and 10g of acidified magnetic composite material were placed in 50ml of 98% concentrated sulfuric acid and esterified at 80℃ for 24h to obtain the ionic liquid catalyst supported on the magnetic composite material. The average particle size of the catalyst was 110μm.

[0071] (5) Catalyst for the synthesis of cyclic carbonates: Propylene carbonate was prepared by the addition reaction of carbon dioxide and propylene oxide in a batch reactor. The reactor volume was 500 mL, and the catalyst loading amount was 0.2% of the mass of propylene oxide. The specific reaction conditions were: reaction temperature 140℃, reaction pressure 2.0 MPa(G), stirring speed 300 r / min, and reaction time 24 h. After that, the mass flow meter reading of carbon dioxide was observed to be unchanged, and the reaction was completed. The catalyst and product were separated by an external magnet.

[0072] Example 6

[0073] (1) Preparation of magnetic cores: 3 mmol of manganese acetate was added to 45 mL of xylene, followed by 3 mmol of oleic acid and 3 mmol of oleylamine as surfactants. The mixture was stirred rapidly and heated to 90 °C. 5 mL of deionized water was added, and the mixture was kept at a constant temperature for 3 h. Finally, Mn3O4 magnetic nanoparticles with good monodispersity were obtained by precipitation and centrifugation.

[0074] (2) Preparation of magnetic composite carbon spheres: The prepared Mn3O4 magnetic nanoparticles were dispersed in 84 mL of ethanol-water mixed solvent (volume ratio 3:4), and 0.6 mL of ammonia water was added as an alkaline catalyst. Then, 1.0 g of phenol, 0.6 g of surfactant CTAB, 1.0 mL of acetaldehyde solution and 4 mL of silicon source TEOS were added sequentially. After mixing evenly, the mixture was stirred and reacted in a water bath at 40 °C for 24 h. The mixed solution was then transferred to a hydrothermal reactor with a polytetrafluoroethylene liner and placed in an oven at 100 °C for hydrothermal reaction for 24 h. After the reaction, impurities were removed by washing with deionized water and anhydrous ethanol. The product was then dried at 120°C and carbonized at 600°C for 4 hours under a nitrogen atmosphere. The surfactant CTAB was removed during carbonization, and the phenolic resin was carbonized. Then, the hard template silica in the material was etched away by stirring in 50 ml of 1 mol / L sodium hydroxide solution in a 50°C water bath for 60 minutes, yielding magnetic composite carbon spheres with an average particle size of 12 μm, a shell thickness of 0.9 μm, and a specific surface area of ​​478 m². 2 / g, with an average pore size of 10nm.

[0075] (3) Preparation of glycosylated imidazole ionic liquid: 10 g of 1-pentylimidazolium and 15 g of 2-chloroethylamine hydrochloride were dissolved in 50 ml of acetonitrile and stirred under nitrogen atmosphere at 120 °C for 24 h. After cooling to room temperature, the lower solid was washed with diethyl ether and filtered to obtain 1-amino-3-methylimidazolium chloride. 20 g of 1-amino-3-methylimidazolium chloride and 5 g of maltose were dissolved in 100 ml of ethanol / water solution (ethanol concentration 50%) and heated under reflux at 100 °C for 24 h. Glycosylated imidazole ionic liquid was obtained by epoxy ring-opening reaction.

[0076] (4) Preparation of functionalized ionic liquid catalyst supported on magnetic composite material: 10g of magnetic composite material was placed in 50ml of 98% concentrated nitric acid for 12h for acidification treatment. After washing with pure water until neutral, carboxyl groups were connected to the surface of the magnetic composite carbon spheres. 20ml of the above-mentioned glycosylated imidazole ionic liquid and 10g of acidified magnetic composite material were placed in 50ml of 98% concentrated sulfuric acid and esterified at 80℃ for 12h to obtain the ionic liquid catalyst supported on the magnetic composite material. The average particle size of the catalyst was 25μm.

[0077] (5) Catalyst for the synthesis of cyclic carbonates: Propylene carbonate was prepared by the addition reaction of carbon dioxide and propylene oxide in a batch reactor. The reactor volume was 500 mL, and the catalyst loading amount was 0.2% of the mass of propylene oxide. The specific reaction conditions were: reaction temperature 140℃, reaction pressure 2.0 MPa(G), stirring speed 300 r / min, and reaction time 24 h. After that, the mass flow meter reading of carbon dioxide was observed to be unchanged, and the reaction was completed. The catalyst and product were separated by an external magnet.

[0078] Comparative Example 1

[0079] Compared with Example 1, the difference lies in the use of a non-glycosylated imidazole ionic liquid.

[0080] (1) The preparation of the magnetic core is the same as in Example 1.

[0081] (2) The preparation of magnetic composite carbon spheres is the same as in Example 1.

[0082] (3) Preparation of hydroxyl-functionalized imidazole ionic liquid: 10 g of 1-methylimidazolium and 15 mL of 3-chloropropanol were dissolved in 50 mL of acetonitrile. The mixture was stirred and refluxed at 80 °C under a nitrogen atmosphere for 24 h. After cooling to room temperature, the lower solid was washed with diethyl ether and filtered to obtain chlorinated 1-(3-hydroxypropyl)methylimidazolium, which is a functionalized imidazole ionic liquid containing a single hydroxyl group.

[0083] (4) The preparation of the magnetic composite material supported functionalized ionic liquid catalyst is the same as in Example 1.

[0084] (5) The catalyst was used to synthesize cyclic carbonates. The amount of catalyst, reaction temperature, reaction pressure and other parameters were the same as in Example 1.

[0085] Comparative Example 2

[0086] Compared with Example 1, the difference lies in the use of a glycosyl-functionalized non-imidazolium ionic liquid.

[0087] (1) The preparation of the magnetic core is the same as in Example 1.

[0088] (2) The preparation of magnetic composite carbon spheres is the same as in Example 1.

[0089] (3) Preparation of glycosylated pyridine ionic liquid: 10 g of 2-methylpyridine and 15 g of 3-chloropropylamine hydrochloride were dissolved in 50 ml of acetonitrile and stirred under reflux at 80 °C for 24 h under a nitrogen atmosphere. After cooling to room temperature, the lower solid was washed with diethyl ether and filtered to obtain 1-aminopropyl-2-methylpyridine chloride. 1-aminopropyl-2-methylpyridine chloride and 30 g of gluconolactone were dissolved in 100 ml of ethanol and heated under reflux at 80 °C for 24 h. After epoxy ring-opening reaction, 2-methylpyridine-propylglucamide chloride was obtained, which is a glycosylated pyridine ionic liquid.

[0090] (4) The preparation of the magnetic composite material supported functionalized ionic liquid catalyst is the same as in Example 1.

[0091] (5) The catalyst was used to synthesize cyclic carbonates. The amount of catalyst, reaction temperature, reaction pressure and other parameters were the same as in Example 1.

[0092] Comparative Example 3

[0093] Compared with Example 1, the difference lies in the use of a non-glycosylated non-imidazolium ionic liquid.

[0094] (1) The preparation of the magnetic core is the same as in Example 1.

[0095] (2) The preparation of magnetic composite carbon spheres is the same as in Example 1.

[0096] (3) Preparation of functionalized ionic liquid: 10g of hydroxyl-terminated polyepoxychloropropane and 8g of pyrrole were added to 50mL of acetonitrile and stirred at 80℃ for 1h. After adding 1g of sodium carbonate solid, the reaction continued for 7h. The product was washed three times with deionized water to obtain hydroxyl-terminated polyether pyrrole ionic liquid catalyst.

[0097] (4) The preparation of the magnetic composite material supported functionalized ionic liquid catalyst is the same as in Example 1.

[0098] (5) The catalyst was used to synthesize cyclic carbonates. The amount of catalyst, reaction temperature, reaction pressure and other parameters were the same as in Example 1.

[0099] Comparative Example 4

[0100] Compared with Example 1, the difference lies in the use of a non-magnetic composite material carrier.

[0101] (1) Preparation of molecular sieve support: 30 mL of toluene and 1 g of calcined support SBA-15 were added to a 50 mL four-necked flask. 4.7 mmol of 3-chloropropyltrimethoxysilane was added dropwise. The mixture was stirred and refluxed at 110 °C for 24 h in a magnetically heated stirrer under a nitrogen atmosphere. After the reaction was completed, the mixture was extracted with dichloromethane for 12 h and dried under vacuum at 80 °C for 8 h to obtain a molecular sieve containing silane linker.

[0102] (2) The preparation of the glycosylated imidazole ionic liquid is the same as in Example 1.

[0103] (3) Preparation of supported functionalized ionic liquid catalyst: 30 mmol of molecular sieve containing silane linker was dispersed in 30 mL of anhydrous ethanol, and 3 mmol of the above-mentioned glycosylated imidazole ionic liquid was added. The mixture was stirred and refluxed at 90 °C for 12 h, extracted with dichloromethane by Soxhlet extraction for 12 h, and the resulting solid was vacuum dried at 80 °C for 10 h to obtain the supported functionalized ionic liquid catalyst.

[0104] (4) The catalyst was used to synthesize cyclic carbonates. The amount of catalyst, reaction temperature, reaction pressure and other parameters were the same as in Example 1.

[0105] The experimental data for the catalytic synthesis of cyclic carbonates in each example / comparative example were quantitatively analyzed by gas chromatography. The product purity, yield, selectivity, and yield after five catalyst cycles are detailed below:

[0106] purity(%) Yield (%) Selectivity (%) Yield (%) after 5 cycles Example 1 99 99.5 99.5 >98 Example 2 99.5 99.6 99.8 >98 Example 3 98.3 98.9 99 >97 Example 4 99.1 99.4 99.3 >98 Example 5 97.5 98.6 97.1 >97 Example 6 98.7 99.1 98.5 >98 Comparative Example 1 97 97.5 97.2 93 Comparative Example 2 97.3 98.4 98 94 Comparative Example 3 95 96.5 97.6 92 Comparative Example 4 96.5 98 96 90

[0107] The above data show that the catalyst prepared in this application has the characteristics of high catalytic activity, strong stability, minimal loss of active components, and recyclability.

Claims

1. A magnetic composite material supported functionalized ionic liquid catalyst, characterized in that, The catalyst comprises a magnetic composite carrier and a functionalized ionic liquid; The functionalized ionic liquid is a glycosyl-functionalized imidazole ionic liquid, the imidazole structure is N-alkyl imidazole, and has the following structure: wherein the anion X - is one or more of a halogen element, a halogen element-containing group, an oxygen-sulfur-containing group, a carboxylate group; R1 and R2 are each independently selected from one of C1-C10 alkyl; The magnetic composite is a yolk-eggshell type magnetic composite carbon sphere with a mesoporous structure. The magnetic core of the carbon sphere of the magnetic composite is a magnetic nanoparticle, and the shell layer is a carbonized product of a phenolic resin.

2. The catalyst according to claim 1, characterized in that, In its imidazole structure, the anion X - is I - , Cl - , Br - or one or more of these.

3. The catalyst of claim 1, wherein The magnetic nanoparticle is one or more of a magnetic metal oxide, a magnetic metal element, and a magnetic metal alloy. The phenolic resin is a condensate of a phenolic compound and an aldehyde compound.

4. The catalyst of claim 3, wherein The magnetic nanoparticle is iron oxide and / or Fe3O4. The phenolic compound in the phenolic resin includes one or more of resorcinol, cresol, phenyl phenol, and bisphenol A, and the aldehyde compound includes one or more of acetaldehyde, paraformaldehyde, and furfural.

5. A process for the preparation of the catalyst of claim 1 or 2, characterized in that, The method comprises the following steps: S1: preparing a chloroalkyl imidazole containing an amino group by using an alkyl imidazole, and then performing an epoxy ring-opening reaction with a lactone of a glycosyl compound to obtain a glycosyl-functionalized imidazole ionic liquid; S2: using a phenolic resin as a carbon source, in-situ polymerization on the surface of a magnetic nanoparticle, and carbonization to prepare a yolk-eggshell type magnetic composite material; S3: loading the glycosyl-functionalized imidazole ionic liquid on the surface of the magnetic composite material through esterification to obtain the target catalyst.

6. The method of claim 5, wherein, The alkyl imidazole in S1 is prepared into a chloroalkyl imidazole containing an amino group by using an amine salt; And / or, the glycosyl compound in S1 is a monosaccharide and / or a disaccharide.

7. The method of claim 6, wherein, The amine salt in S1 is a halogen-substituted aliphatic amine; And / or, the glycosyl compound in S1 is one or more of glucose, fructose, sucrose, and maltose.

8. The method of claim 7, wherein, The amine salt in S1 is 3-chloropropylamine.

9. The method of claim 5, wherein, The silicon is etched away after carbonization in S2; And / or, the shell layer of the magnetic composite material obtained in S2 has a mesoporous structure.

10. The method of claim 5, wherein, The magnetic composite material in S3 is first subjected to acid treatment; And / or, the S3 is subjected to dehydration esterification in a concentrated acid; And / or, the particle size of the catalyst obtained in S3 is 10-100 μm.

11. A process for the preparation of cyclic carbonates using the catalyst according to any one of claims 1 to 4, or the catalyst prepared according to the process of any one of claims 5 to 10, characterized in that, In the preparation method, the mass ratio of the catalyst to the epoxide compound is 0.1-15%, the reaction temperature is 50-150°C, the reaction pressure is 0.1-3 MPaG, and the reaction time is 1-24 h; Optionally, after the reaction is completed, the organic phase and the catalyst phase are separated under the action of an external magnetic field, and the catalyst is recovered and recycled.

12. Use of a magnetic composite material loaded with a functionalized ionic liquid catalyst, said catalyst being the catalyst of any one of claims 1 to 4, or a catalyst prepared using the method of any one of claims 5 to 10, characterized in that, The catalyst is used for catalyzing the synthesis of cyclic carbonates.

13. Use according to claim 12, characterized in that, The catalyst is used for catalyzing the synthesis of ethylene carbonate, propylene carbonate, and glycerol carbonate.

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