Fiber type polyion liquid catalyst as well as preparation method and application thereof

Abstract

The invention provides a fiber type polyionic liquid catalyst and a preparation method and application thereof, the fiber type polyionic liquid catalyst is prepared by spinning a precursor solution, and the precursor solution is prepared by dissolving an ionic liquid monomer, an initiator, a cross-linking agent and a polymer raw material in a solvent and mixing. A specific precursor solution is spun to obtain a polyion liquid catalyst with a fiber structure and high porosity, and the polyion liquid catalyst has a microporous network, can enhance gas and mass transport, enables catalytic active sites to be effectively exposed, and can catalyze CO2 cycloaddition to generate cyclic carbonate under the mild conditions of no metal, no catalyst promoter and no solvent; and the catalyst has high catalytic activity and good cycle performance. The fiber type polyion liquid catalyst has processability, can still keep high catalytic activity after continuously catalyzing CO2 cycloaddition reaction for 1000 hours in micro continuous flow reactors (such as fixed beds) and the like, and has a wide industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, designs a polyionic liquid catalyst, and specifically relates to a fiber-type polyionic liquid catalyst and a preparation method and application thereof. Background Art

[0002] CO2 is one of the most common greenhouse gases on Earth, but it is also an abundant, cheap and renewable C1 raw material. Converting CO2 into fine chemical products with high added value can not only effectively alleviate greenhouse gas emissions, but also create social and economic value and environmental benefits. Among the many ways to utilize CO2, the cycloaddition reaction of CO2 with epoxides to generate five-membered cyclic carbonates has 100% atom economy and is considered to be one of the most promising ways to convert and utilize resources.

[0003] Currently, many homogeneous and heterogeneous catalyst systems have been studied and used to catalyze cycloaddition reactions. However, these catalysts also have many limitations. For example, when metal catalysts are used, the reaction conditions are usually harsh and co-catalysts and solvent conditions are required to promote the reaction. In addition, ionic liquids have made remarkable research progress in the field of CO2 cycloaddition as catalysts (ionic liquids are molten salts composed entirely of ions. Ionic liquids with different properties can be obtained through the combination of anions and cations). For example, the Chinese invention patent with application number 202010188049.X discloses a method for synthesizing cyclic carbonates from carbon dioxide using fluoroalcohol-functionalized ionic liquids. The method prepares fluoroalcohol-functionalized bifunctional ionic liquids by animazole cyclization reaction of amino compounds and formaldehyde, glyoxal, and hydrohalic acid, and quaternization reaction of amino compounds with halogenated alkanes. Carbon dioxide and different epoxy compounds are used as raw materials. The reaction pressure is 0.1-5MPa, the reaction temperature is 25-150°C, the amount of catalyst is 0.1-10mol% of the epoxy compound, and the reaction time is 1-10h. The corresponding cyclic carbonates are prepared by cycloaddition reaction under solvent-free conditions. However, there are still many difficulties in the separation and recovery of homogeneous catalysts of ionic liquids.

[0004] With the deepening of the study of ionic liquids, supported or polymerized ionic liquids can achieve heterogeneity of ionic liquids and show good catalyst recycling performance. For example, the Chinese invention patent with application number 202311529247.8 discloses a method for preparing a cyclic carbonate catalyst by a carbon dioxide cycloaddition reaction, which relates to a method for preparing a cyclic carbonate catalyst, wherein the method is to prepare a MOF carrier NH2-MIL-101 by a hydrothermal method, and to introduce 1-n-butyl-3-methylimidazolium bromide ionic liquid active components in two steps by "post-synthesis modification", and to prepare a MOF-supported ionic liquid heterogeneous catalyst IL(Br-)-NH2-MIL-101 in three steps; to prepare a MOF-supported ionic liquid bifunctional heterogeneous catalyst with carbon dioxide adsorption and activation ability by grafting 1-n-butyl-3-methylimidazolium bromide with NH2-MIL-101; the catalyst has good catalytic activity and reusability; the catalyst has good carbon dioxide adsorption and activation ability, and the catalytic reaction can also be carried out efficiently at a lower pressure. However, the immobilization of such ionic liquids tends to wrap the active sites and prevent them from being fully exposed, which results in the inability to maximize their catalytic activity. Very harsh conditions are often required to catalyze the cycloaddition reaction of CO2 and epoxides. Therefore, it is still difficult to develop a multiphase polyionic liquid catalyst that can efficiently catalyze the cycloaddition reaction of CO2 under mild conditions.

[0005] The Chinese invention patent with application number 202411091419.2 discloses an imidazolyl polyionic liquid catalyst and its preparation method and application, which belongs to the technical field of five-membered cyclic carbonate synthesis. The application polymerizes imidazolyl ionic liquid and divinylbenzene to obtain an imidazolyl polyionic liquid catalyst, and uses it to catalyze the one-step preparation of styrene cyclic carbonate from carbon dioxide and styrene. The imidazolyl polyionic liquid catalyst can efficiently convert styrene into styrene cyclic carbonate; among them, PIL exhibits the best catalytic activity, and the yield and selectivity of styrene cyclic carbonate obtained under the conditions of no catalyst, 90°C, 1MPa CO2, and 24h are 71%. However, the yield and selectivity of styrene cyclic carbonate in this application will decrease significantly when the temperature decreases. Summary of the invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to provide a fiber-type polyionic liquid catalyst that can promote the efficient conversion of CO2 under low temperature and low pressure, solvent-free and catalyst-free conditions.

[0007] In order to achieve the above technical purpose, the present invention provides a fiber-type polyionic liquid catalyst, which is obtained by spinning a precursor solution, wherein the precursor solution is prepared by dissolving an ionic liquid monomer, an initiator, a crosslinking agent and a polymer raw material in a solvent.

[0008] Optimally, its porosity is 20-80%.

[0009] Optimally, the precursor solution comprises the following components in parts by weight:

[0010] 8 to 15 parts of ionic liquid monomer;

[0011] 8-15 parts of polymer raw material;

[0012] 88-92 parts of solvent;

[0013] Cross-linking agent 0.1-2 parts;

[0014] Initiator 0.1 to 2 parts.

[0015] Furthermore, the cation of the ionic liquid monomer is one or more selected from imidazolium ions, pyridinium ions, guanidine ions, piperidine ions and pyrrole ions, and the anion of the ionic liquid monomer is one or more selected from Cl - Br - ,I - 、BF4 - PF6 - NTf2 - and TFSI - One or more of .

[0016] Furthermore, the cation of the ionic liquid monomer is one or more selected from the following chemical formulas:

[0017]

[0018] In the formula, R is R' is an alkyl group having 1 to 6 carbon atoms or a vinyl group.

[0019] Specifically, the cation of the ionic liquid monomer is

[0020] Further, the polymer raw material is one or more selected from polyethylene oxide, polyvinylidene fluoride, polyacrylonitrile, polypropylene and cotton. The solvent is one or more selected from acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide and water. The crosslinking agent is one or two selected from N,N-methylenebisacrylamide and divinylbenzene. The initiator is one or more selected from 2-hydroxy-methylphenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone and 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone.

[0021] Another object of the present invention is to provide a method for preparing the above-mentioned fiber-type polyionic liquid catalyst, comprising the following steps:

[0022] (a) dissolving the ionic liquid monomer, initiator, crosslinking agent and polymer raw material in a solvent to obtain a precursor solution;

[0023] (b) spinning the precursor solution to obtain an ionic liquid composite fiber membrane;

[0024] (c) subjecting the ionic liquid composite fiber membrane to free radical polymerization to obtain the fiber-type polyionic liquid catalyst.

[0025] Optimally, the spinning is electrospinning, wet spinning, air-blow spinning or melt spinning,

[0026] The process parameters of the electrospinning are: positive voltage 18-21KV, negative voltage 3-4KV, receiver speed 300-500rmp, syringe back and forth speed 200-500mm / min, injection speed 0.1-0.8mL / min, distance from syringe to receiver 13-15cm, temperature 25-45°C, humidity 30-45%;

[0027] The process parameters of the air-jet spinning are: gas pressure 0.5-0.7MPa, receiver speed 400-500rmp, injector reciprocating speed 500-800mm / min, injection speed 50-80μL / min, distance from injector to receiver 30-50cm, temperature 25-35℃, humidity 30-45%.

[0028] Another object of the present invention is to provide an application of the above-mentioned fiber-type polyionic liquid catalyst, which is used as a catalyst for catalyzing the carbon dioxide cycloaddition reaction to prepare cyclic carbonates.

[0029] The fiber-type polyionic liquid catalyst of the present invention is obtained by spinning a specific precursor solution to obtain a fiber structure and a polyionic liquid catalyst with high porosity. The fiber-type polyionic liquid catalyst has a microporous network, can enhance gas-gas transport, and can effectively expose the catalytic active sites, so that the fiber-type polyionic liquid catalyst can catalyze CO2 cycloaddition to generate cyclic carbonates under the conditions of no metal, no promoter, no solvent, and low temperature (can be as low as 30°C, such as 30-70°C) and low pressure (can be as low as 0.1MPa, such as 0.1-1MPa); and has high catalytic activity and good cycle performance. The fiber-type polyionic liquid catalyst has processability, and can still maintain high catalytic activity after continuously catalyzing CO2 cycloaddition reaction in a micro-continuous flow reactor (such as a fixed bed, etc.) for 1000 hours, and has broad industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a comparison diagram of Fourier transform infrared spectra of each component in Example 5;

[0031] Figure 2is a scanning electron microscope image of the fiber-type polyionic liquid catalyst in Example 5;

[0032] Figure 3 The results are shown in Example 5, in which the fiber-type polyionic liquid catalyst catalyzes the cycloaddition reaction of CO2 with a series of terminal epoxides containing different substituents. DETAILED DESCRIPTION

[0033] The fiber-type polyionic liquid catalyst of the present invention is prepared by spinning a precursor solution, wherein the precursor solution is prepared by dissolving ionic liquid monomer, initiator, crosslinking agent and polymer raw material in a solvent and mixing them. The porosity of the fiber-type polyionic liquid catalyst is preferably 20-80%.

[0034] The above-mentioned precursor solution preferably includes the following components in parts by weight: 8-15 parts of ionic liquid monomer, 8-15 parts of polymer raw material, 88-92 parts of solvent, 0.1-2 parts of crosslinking agent, and 0.1-2 parts of initiator. Among them, the cation of the ionic liquid monomer is one or more selected from imidazolium ions, pyridinium ions, guanidine ions, piperidine ions and pyrrole ions, and the anion is one or more selected from Cl - Br - ,I - 、BF4 - (tetrafluoroborate anion), PF6 - (hexafluorophosphate anion), NTf2 - (bis(trifluoromethanesulfonyl imide) ion) and TFSI - (bis(trifluoromethylsulfonyl)imide ion). The above ionic liquid monomer is prepared by affinity substitution reaction in an organic solvent, the organic solvent is one or more selected from acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide and dichloromethane, the reaction temperature is 25-70°C, and the reaction time is 12-48h.

[0035] The cation of the ionic liquid monomer is preferably selected from one or more of the following chemical formulas:

[0036]

[0037] In the formula, R is R' is an alkyl group or vinyl group having 1 to 6 carbon atoms. The cation of the ionic liquid monomer is preferably Guanidine-based ionic liquids have better effects, among which tetramethylguanidine-4-vinylbenzyl chloride ionic liquid is the best. This is because guanidine-based ionic liquids have better catalytic activity in cycloaddition reactions than other ionic liquids, and tetramethylguanidine-4-vinylbenzyl chloride ionic liquids are faster and more complete in free radical polymerization than other guanidine salts.

[0038] The polymer raw material is preferably selected from one or more of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polypropylene (PP) and cotton. The solvent is preferably selected from one or more of acetonitrile, N,N-dimethylformamide (DMF), dimethyl sulfoxide and water, the cross-linking agent is preferably selected from one or both of N,N-methylenebisacrylamide and divinylbenzene (DVB), and the initiator is preferably selected from one or more of 2-hydroxy-methylphenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone (HCPK) and 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone.

[0039] The preparation method of the above-mentioned fiber-type polyionic liquid catalyst comprises the following steps: (a) dissolving the ionic liquid monomer, initiator, crosslinking agent and polymer raw material in a solvent to obtain a precursor solution; (b) spinning the precursor solution to obtain an ionic liquid composite fiber membrane; (c) subjecting the ionic liquid composite fiber membrane to free radical polymerization to obtain the fiber-type polyionic liquid catalyst.

[0040] The spinning is electrostatic spinning, wet spinning, air-jet spinning or melt spinning. The process parameters of the electrostatic spinning are preferably: positive voltage 18-21KV, negative voltage 3-4KV, receiver (such as receiving roller, etc., the same below) speed 300-500rmp, syringe reciprocating speed 200-500mm / min, injection speed 0.1-0.8mL / min, distance from syringe to receiver 13-15cm, temperature 25-45°C, humidity 30-45%; the process parameters of the air-jet spinning are preferably: gas pressure 0.5-0.7MPa, receiver speed 400-500rmp, syringe reciprocating speed 500-800mm / min, injection speed 50-80μL / min, distance from syringe to receiver 30-50cm, temperature 25-35°C, humidity 30-45%.

[0041] The fiber-type polyionic liquid catalyst is used to catalyze the cycloaddition reaction of CO2 and epoxy compounds, that is, to be used as a catalyst for catalyzing the cycloaddition reaction of carbon dioxide to prepare cyclic carbonates. For example, it can catalyze the reaction of carbon dioxide and epoxy compounds to prepare cyclic carbonates in an intermittent reactor (reaction conditions are 30-70°C, CO2 pressure is 0.1-1MPa, and time is 18-24h), and it can also catalyze the cycloaddition reaction of CO2 and epoxy compounds in a fixed bed (reaction conditions are 30-70°C, CO2 flow rate is 5-50mL / min, epoxy compound flow rate is 0.05-5mL / min, CO2 pressure is 0.1-1MPa, and reaction time is 0.1-1000h).

[0042] The fiber-type polyionic liquid catalyst of the present invention has a wide range of raw material selection, low cost, flexible and controllable structure, and adjustable loading amount of active components; it can be processed into various shapes and is suitable for filling different reactors. In addition, the fiber-type polyionic liquid catalyst has a microporous network, which can enhance gas-gas transfer and has a large specific surface area. These characteristics enable the catalytic active sites to be effectively exposed and promote continuous cycloaddition reactions. The polyionic liquid part in the catalyst can efficiently adsorb and activate carbon dioxide and epoxy substrates, so that the cycloaddition reaction can be efficiently catalyzed in the absence of solvents, catalyst promoters, and low temperature (can be as low as 30°C, such as 30-70°C) and low pressure (can be as low as 0.1MPa, such as 0.1-1MPa) conditions.

[0043] The fiber-type polyionic liquid catalyst of the present invention has high catalytic performance and stability. When the fiber-type polyionic liquid catalyst continuously catalyzes carbon dioxide and an epoxy substrate for 700 hours, the yield of the product can be stabilized at 99%. In addition, even in a continuous reaction of 1000 hours, the yield can still reach 93.5%, which has great industrial application prospects.

[0044] The preferred embodiments of the present invention will be described in detail below.

[0045] Example 1

[0046] This embodiment provides a fiber-type polyionic liquid catalyst and a preparation method and application thereof, as follows:

[0047] (a0) 1-vinylimidazole (40 mmol) was dissolved in a round-bottom flask containing 15 mL of acetonitrile, bromopropane (40 mmol) was added dropwise, and the mixture was stirred at 70° C. for 24 h; the obtained product was washed with ethyl acetate and ether three times each, and the residual solvent was removed by a rotary evaporator, and finally dried under vacuum at 25° C. overnight to obtain an imidazolyl ionic liquid (i.e., 1-vinyl-3-propyl-imidazolium bromide);

[0048] (a) Take 1.2 g of imidazole ionic liquid and 1.2 g of PAN (M w =149000-151000), DVB 0.024g, HCPK 0.024g and DMF 8.8g, stirred at room temperature overnight to obtain a precursor solution;

[0049] (b) The precursor solution was injected into a 10 mL syringe, and a 25G needle was taken to prepare the ionic liquid composite fiber membrane using the electrospinning process technology: the electrospinning conditions were positive voltage 18 KV, negative voltage 3 KV, receiving drum speed 300 rpm, syringe back and forth movement speed 300 mm / min, injection speed 0.1 mL / min, distance from syringe to receiver 13 cm, temperature 30 ° C, and humidity 35%;

[0050] (c) The obtained ionic liquid composite fiber membrane was polymerized under ultraviolet light atmosphere for 1 hour to obtain a fiber-type polyionic liquid catalyst (defined as cat.1-1).

[0051] This embodiment also performs the following steps simultaneously:

[0052] (b') injecting the above precursor solution into a 10 mL syringe, and preparing the ionic liquid composite fiber membrane by air-jet spinning process technology: the spinning conditions are gas pressure 0.7 MPa, receiving drum speed 400 rpm, syringe back and forth moving speed 600 mm / min, injection speed 80 μL / min, distance from syringe to receiver 50 cm, temperature 25 ° C, humidity 40%;

[0053] (c') The obtained ionic liquid composite fiber membrane was polymerized under ultraviolet light atmosphere for 1 h to obtain a fiber-type polyionic liquid catalyst (defined as cat.1-2).

[0054] This embodiment also provides the application of the fiber-type polyionic liquid catalyst, which is as follows:

[0055] 65mmol of epichlorohydrin and 3.5mol% of cat.1-1 (the molar content here is the percentage of the molar amount of imidazole-based ionic liquid to the molar amount of epichlorohydrin, the same below) were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The calculated yield of the product was 89.5% and the conversion rate was 89.5%.

[0056] 65mmol epichlorohydrin and 3.5mol% cat.1-2 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The calculated yield of the product was 89.2% and the conversion rate was 89.2%.

[0057] Example 2

[0058] This embodiment provides a fibrous polyionic liquid catalyst and its preparation method and application, which are basically the same as those in Example 1, except that in step (a0), bromopentane (40 mmol) is added dropwise, so that step (c) finally obtains a fibrous polyionic liquid catalyst (defined as cat.2).

[0059] 65mmol epichlorohydrin and 3.5mol% cat.2 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The calculated yield of the product was 94.3% and the conversion rate was 95.5%.

[0060] Example 3

[0061] This embodiment provides a fiber-type polyionic liquid catalyst and its preparation method and application, which are basically the same as those in Example 1, except that: in step (a0), 4-ethylbenzyl chloride (40 mmol) is added dropwise, so that step (c) finally obtains a fiber-type polyionic liquid catalyst (defined as cat.3).

[0062] 65mmol epichlorohydrin and 3.5mol% cat.4 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The calculated yield of the product was 89.7% and the conversion rate was 90.1%.

[0063] Example 4

[0064] This embodiment provides a fiber-type polyionic liquid catalyst and its preparation method and application, which are basically the same as those in Example 2, except that: in step (a), 1.0 g of imidazole ionic liquid, 1.0 g of PAN, 0.02 g of DVB, 0.02 g of HCPK and 9 g of DMF are taken and stirred at room temperature overnight to obtain a precursor solution; in this way, step (c) finally obtains a fiber-type polyionic liquid catalyst (defined as cat. 4).

[0065] 65mmol epichlorohydrin and 3.5mol% cat.3 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The calculated yield of the product was 90.2% and the conversion rate was 91.3%.

[0066] Example 5

[0067] This embodiment provides a fiber-type polyionic liquid catalyst and its preparation method and application, which are basically the same as those in Example 1, except that: in step (a0), 1,1,3,3-tetramethylguanidine (40 mmol) is dissolved in a round-bottom flask containing 15 mL of acetonitrile, 4-vinylbenzyl chloride (40 mmol) is added dropwise, and stirred at 25°C for 48 hours. The obtained product is washed three times with ethyl acetate and ether respectively, and the residual solvent is removed by a rotary evaporator, and finally vacuum dried at 25°C overnight to obtain an imidazolyl ionic liquid (abbreviated as [TMGVB]Cl); thus, step (c) finally obtains a fiber-type polyionic liquid catalyst (defined as cat.5, abbreviated as PIL@PAN).

[0068] 65mmol epichlorohydrin and 3.5mol% cat.5 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The yield of the product was calculated to be 99% and the conversion rate was 99%.

[0069] 65mmol of styrene oxide and 3.5mol% cat.5 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The yield of the product was calculated to be 87% and the conversion rate was 99%. Under the same conditions, when the temperature was raised to 90°C, the yield of the product was calculated to be 99% and the conversion rate was 99%.

[0070] 3.5 mol% cat.1-1 was also placed in a fixed bed reactor (a carbon dioxide valve was used to maintain the carbon dioxide pressure in the pipeline at 0.1 MPa, and the carbon dioxide flow rate was controlled to 15 mL / min by a carbon dioxide mass flowmeter; the ECH (epichlorohydrin) flow rate was 0.1 mL / min; the fiber membrane catalyst cat.5 was cut into circles with a diameter of 15 mm and filled into a quartz tube with an inner diameter of 15 mm, with a filling length of 10 cm (4.0 g)). The temperature of the heating sleeve was set to 70°C to allow the reaction to continue. The product collected in the product collection tank was dissolved in deuterated chloroform, and analyzed by nuclear magnetic resonance to determine the product yield and conversion rate. Experiments have shown that it can continuously and stably catalyze the cycloaddition reaction of CO2 and epoxy substrates. In the first 700 hours, the product yield remained at 99%; and when the reaction was carried out to 1000 hours, the product yield could still reach 93.5% (such as Figures 1 to 3 shown).

[0071] The experimental results show that the fiber-type catalyst exhibits excellent yield and selectivity for terminal epoxides with small-sized substituents (such as epichlorohydrin, epibromohydrin, ethylene oxide, etc.) under mild conditions (70°C, 0.1MPa). However, for allyl glycidyl ether (AGE) and styrene oxide (SO), the catalytic effect of the fiber-type catalyst is reduced, which may be due to the steric hindrance between molecules. Both AGE with a longer alkyl chain and SO with a larger substituent have large steric hindrance, which may hinder the contact between the substrate and the active site of the catalyst, thereby reducing the catalytic activity. When the temperature is increased to 90°C, AGE and SO also show a yield and selectivity of 99%, further indicating that the fiber-type catalyst has excellent catalytic performance for cycloaddition reactions.

[0072] Example 6

[0073] This embodiment provides a fibrous polyionic liquid catalyst and its preparation method and application, which are basically the same as those in Example 5, except that: in step (a0), allyl bromide (40 mmol) is added dropwise; thus, step (c) finally obtains a fibrous polyionic liquid catalyst (defined as cat.6).

[0074] 65mmol epichlorohydrin and 3.5mol% cat.6 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The product yield was calculated to be 99% and the conversion rate was 99%.

[0075] Example 7

[0076] This embodiment provides a fibrous polyionic liquid catalyst and its preparation method and application, which are basically the same as those in Example 5, except that: in step (a0), bromopentene (40 mmol) is added dropwise; thus, step (c) finally obtains a fibrous polyionic liquid catalyst (defined as cat.7).

[0077] 65mmol epichlorohydrin and 3.5mol% cat.7 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The product yield was calculated to be 99% and the conversion rate was 99%.

[0078] Example 8

[0079] This embodiment provides a fiber-type polyionic liquid catalyst and its preparation method and application, which are basically the same as those in Example 1, except that: in step (a0), 2-methylpyridine (40 mmol) is dissolved in a round-bottom flask containing 15 mL of acetonitrile, propylene bromide (40 mmol) is added dropwise, and stirred at 50° C. for 24 h. The obtained product is washed three times with ethyl acetate and ether respectively, and the residual solvent is removed by a rotary evaporator, and finally vacuum dried at 25° C. overnight; thus, step (c) finally obtains a fiber-type polyionic liquid catalyst (defined as cat. 8).

[0080] 65mmol epichlorohydrin and 3.5mol% cat.8 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The calculated yield of the product was 67.8% and the conversion rate was 68.3%.

[0081] Example 9

[0082] This embodiment provides a fibrous polyionic liquid catalyst and its preparation method and application, which are basically the same as those in Example 8, except that: in step (a0), bromopentene (40 mmol) is added dropwise; thus, step (c) finally obtains a fibrous polyionic liquid catalyst (defined as cat.9).

[0083] 65mmol epichlorohydrin and 3.5mol% cat.9 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The yield of the product was calculated to be 70.2% and the conversion rate was 70.6%.

[0084] Example 10

[0085] This embodiment provides a fiber-type polyionic liquid catalyst and its preparation method and application, which are basically the same as those in Example 8, except that: in step (a0), 4-vinylbenzyl chloride (40 mmol) is added dropwise; thus, step (c) finally obtains a fiber-type polyionic liquid catalyst (defined as cat.10).

[0086] 65mmol epichlorohydrin and 3.5mol% cat.10 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The calculated yield of the product was 83.4% and the conversion rate was 84.5%.

[0087] Embodiment 11

[0088] This embodiment provides a fiber-type polyionic liquid catalyst and its preparation method and application, which are basically the same as those in Example 1, except that: in step (a0), 1-methylpiperidine (40 mmol) is dissolved in a round-bottom flask containing 15 mL of acetonitrile, propylene bromide (40 mmol) is added dropwise, and stirred at 50° C. for 24 h. The obtained product is washed three times with ethyl acetate and ether respectively, and the residual solvent is removed by a rotary evaporator, and finally vacuum dried at 25° C. overnight; thus, step (c) finally obtains a fiber-type polyionic liquid catalyst (defined as cat.11).

[0089] 65mmol epichlorohydrin and 3.5mol% cat.11 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The calculated yield of the product was 96.7% and the conversion rate was 96.8%.

[0090] Example 12

[0091] This embodiment provides a fibrous polyionic liquid catalyst and its preparation method and application, which are basically the same as those in Example 11, with the only difference being that in step (a0), bromopentene (40 mmol) is added dropwise; thus, step (c) finally obtains a fibrous polyionic liquid catalyst (defined as cat. 12).

[0092] 65mmol epichlorohydrin and 3.5mol% cat.12 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The calculated yield of the product was 97.2% and the conversion rate was 97.5%.

[0093] Example 13

[0094] This embodiment provides a fibrous polyionic liquid catalyst and its preparation method and application, which are basically the same as those in Example 11, except that: in step (a0), 4-vinylbenzyl chloride (40 mmol) is added dropwise; thus, step (c) finally obtains a fibrous polyionic liquid catalyst (defined as cat.13).

[0095] 65mmol epichlorohydrin and 3.5mol% cat.13 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. The yield of the product was calculated to be 99% and the conversion rate was 99%.

[0096] Comparative Example 1

[0097] This example provides a catalyst and a preparation method and application thereof, which are basically the same as those in Example 1, except that: 0.024 g of DVB (defined as cat. 14) is not added.

[0098] 65mmol epichlorohydrin and 3.5mol% cat.14 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. It was found that the nuclear magnetic peak of imidazole-based ionic liquid appeared in the nuclear magnetic resonance spectrum. This is because some imidazole salts failed to free radical polymerization, resulting in small molecules dissolved in the reaction system.

[0099] Comparative Example 2

[0100] This example provides a catalyst and its preparation method and application, which are basically the same as those in Example 1, except that no ionic liquid monomer is added. It is finally found that epichlorohydrin does not react.

[0101] Comparative Example 3

[0102] This example provides a catalyst and its preparation method and application, which are basically the same as those in Example 1, except that the precursor solution is directly reacted at 70°C for 24 hours, cooled to room temperature, centrifuged, washed three times with ethanol / water (V:V=3:1) solvent, and vacuum dried at 60°C (without using electrospinning process). In this way, step (c) finally obtains a fiber-type polyionic liquid catalyst (defined as cat.17).

[0103] 65mmol epichlorohydrin and 3.5mol% cat.17 were placed in a 100mL stainless steel reactor, sealed, and filled with 0.1MPa CO2 three times to replace the air in the reactor; then the reactor was heated to 70°C and kept for 24h. After the reaction was completed, it was cooled with an ice water bath, and then the CO2 in the reactor was released. The product after the reaction was dissolved in deuterated chloroform and analyzed by nuclear magnetic resonance. It was found that compared with the catalytic result of the fiber-type polyionic liquid catalyst cat.1 in Example 1, the product yield catalyzed by cat.17 decreased, and its yield was only 15.7%. This is because cat.17 has no porous structure, its specific surface area is smaller than that of the fiber-type polyionic liquid catalyst cat.1, and the active sites are not fully exposed.

[0104] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A fiber-type polyionic liquid catalyst, which is prepared by spinning a precursor solution, characterized in that: The precursor solution is prepared by dissolving an ionic liquid monomer, an initiator, a cross-linking agent and a polymer raw material in a solvent and mixing them.

2. The fiber-type polyionic liquid catalyst according to claim 1, characterized in that: Its porosity is 20-80%.

3. The fiber-type polyionic liquid catalyst according to claim 1, characterized in that: The precursor solution includes the following components in parts by weight: 8 to 15 parts of ionic liquid monomer; 8-15 parts of polymer raw material; 88-92 parts of solvent; Cross-linking agent 0.1-2 parts; Initiator 0.1 to 2 parts.

4. The fiber-type polyionic liquid catalyst according to claim 3, characterized in that: The cation of the ionic liquid monomer is one or more selected from imidazolium ions, pyridinium ions, guanidine ions, piperidine ions and pyrrole ions, and the anion of the ionic liquid monomer is one or more selected from Cl - Br - ,I - 、BF4 - PF6 - NTf2 - and TFSI - One or more of .

5. The fiber-type polyionic liquid catalyst according to claim 4, characterized in that: The cation of the ionic liquid monomer is one or more selected from the following chemical formulas: In the formula, R is R' is an alkyl group having 1 to 6 carbon atoms or a vinyl group.

6. The fiber-type polyionic liquid catalyst according to claim 5, characterized in that: The cation of the ionic liquid monomer is 7. The fiber-type polyionic liquid catalyst according to claim 3, characterized in that: The polymer raw material is one or more selected from polyethylene oxide, polyvinylidene fluoride, polyacrylonitrile, polypropylene and cotton, the solvent is one or more selected from acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide and water, the crosslinking agent is one or two selected from N,N-methylenebisacrylamide and divinylbenzene, and the initiator is one or more selected from 2-hydroxy-methylphenylpropane-1-one, 1-hydroxycyclohexyl phenyl ketone and 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone.

8. The method for preparing the fiber-type polyionic liquid catalyst according to any one of claims 1 to 7, characterized in that: The following steps are involved: (a) dissolving the ionic liquid monomer, initiator, crosslinking agent and polymer raw material in a solvent to obtain a precursor solution; (b) spinning the precursor solution to obtain an ionic liquid composite fiber membrane; (c) subjecting the ionic liquid composite fiber membrane to free radical polymerization to obtain the fiber-type polyionic liquid catalyst.

9. The method for preparing the fiber-type polyionic liquid catalyst according to claim 8, characterized in that: The spinning is electrostatic spinning, wet spinning, air-blow spinning or melt spinning, The process parameters of the electrospinning are: positive voltage 18-21KV, negative voltage 3-4KV, receiver speed 300-500rmp, syringe back and forth speed 200-500mm / min, injection speed 0.1-0.8mL / min, distance from syringe to receiver 13-15cm, temperature 25-45°C, humidity 30-45%; The process parameters of the air-jet spinning are: gas pressure 0.5-0.7MPa, receiver speed 400-500rmp, injector reciprocating speed 500-800mm / min, injection speed 50-80μL / min, distance from injector to receiver 30-50cm, temperature 25-35℃, humidity 30-45%.

10. The use of the fiber-type polyionic liquid catalyst according to any one of claims 1 to 7, characterized in that: It is used as a catalyst for the preparation of cyclic carbonates by catalytic carbon dioxide cycloaddition reaction.

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