Polyionic liquid catalyst as well as preparation method and application thereof

Abstract

The invention provides a polyion liquid catalyst as well as a preparation method and application thereof, belongs to the technical field of biomass catalytic conversion, and aims to solve the technical problem of low yield of 5-HMF (5-hydroxymethylfurfural) synthesized from glucose. According to the preparation method disclosed by the invention, the P (VEIM)-PH-Al polyion liquid catalyst is prepared by reacting polybrominated 1-vinyl-3-ethylimidazole with acid fuchsin and metal aluminum salt. The catalyst is used for catalyzing glucose to prepare 5-hydroxymethylfurfural, and 5-hydroxymethylfurfural is synthesized through selective catalysis of glucose in a two-phase solvent system. The prepared catalyst contains a large amount of sulfonic acid Bronsted acid sites and aluminum-based coordination metal ion Lewis acid sites, and directional conversion of preparing 5-hydroxymethylfurfural from glucose is achieved in a two-phase solvent system. The synthesis method of the catalyst is simple, the process is short, few reaction byproducts are produced, and the yield of 5-hydroxymethylfurfural is up to 73.26%.

Description

Technical Field

[0001] This invention belongs to the technical field of biomass catalytic conversion, and particularly relates to a polyionic liquid catalyst. Background Technology

[0002] With the increasing consumption of fossil fuels and the growing severity of environmental pollution, the application of renewable and clean energy as alternatives to fossil fuels has received increasing attention in recent years. Lignocellulosic biomass is a promising renewable energy source and can serve as a precursor for many compounds. 5-Hydroxymethylfurfural (5-HMF) has been designated by the U.S. Department of Energy as one of the top ten priority biomass-based compounds for production. It is formed by the dehydration of hexose sugars and, due to the presence of functional groups such as C=O, CO, and furan rings, it becomes an important multifunctional molecule that can be converted into a series of industrially important fine chemicals, such as biofuels, platform chemicals, solvents, bulk chemicals, and various monomers for polymer production.

[0003] In recent years, rapid progress has been made in efficient catalytic methods for the production of 5-HMF. Fructose can be efficiently converted to 5-hydroxymethylfurfural using dehydration catalysts such as strong acid cation exchange resins, zeolites, or inorganic acids. However, the large-scale application of fructose in the production of 5-HMF is limited by its high cost. Glucose, as the cheapest and most abundant monosaccharide, is considered the preferred raw material for the production of 5-HMF. The conversion of glucose to 5-HMF consists of two distinct steps, both promoted by acid catalysts: first, Lewis acid isomerizes the aldose (glucose) to the ketose (fructose), and then fructose undergoes dehydration in the presence of Brønsted acid to 5-HMF. Generally, the glucose-to-fructose isomerization step is considered the rate-limiting step in the glucose-to-5-HMF conversion because, in addition to the glucose-to-fructose isomerization, a competitive isomerization reaction of glucose to mannose also occurs on the acid catalyst. These interconversions between sugar molecules slow down the overall conversion process and increase reaction byproducts.

[0004] To facilitate the isomerization of glucose to fructose, the pioneering Cr / ionic liquid system [Metal Chlorides in Ionic Liquid Solvents Convert Sugars to 5-Hydroxymethylfurfural] by Zhao et al., and other pathways based on this catalytic system, have been extensively studied. While these catalytic processes exhibit high activity in the synthesis of 5-hydroxymethylfurfural from glucose, these reactions are carried out in toxic heavy metal catalytic systems, making large-scale industrial production difficult. To overcome these challenges, numerous attempts have been made to develop chromium-free methods as less hazardous alternatives.

[0005] The reaction solvent also has a significant impact on the preparation of 5-HMF. High product yields can be obtained in high-boiling-point single solvents such as DMSO, DMAc, and DMF, but problems such as difficult product purification, high solvent cost, and difficulty in reuse are encountered. Water is a green solvent for chemical reactions. Using water and low-boiling-point solvents as reaction solvents to form a two-phase system can achieve high yields. Furthermore, the low-boiling-point solvent can also be used as an extractant to extract 5-HMF from the aqueous phase to achieve purification and separation. Moreover, the low-boiling-point solvent can separate the product and recover the solvent under mild conditions, making it suitable for industrial production and economically viable.

[0006] The current challenge in producing 5-HMF is improving the economics and reaction yield of industrial-scale production. The yield of HMF from expensive ketoses (fructose) can reach approximately 94%, while the yield from inexpensive and abundant aldoses (glucose), even under strong Brønsted acid catalysis at 150-200°C, is only around 60%. Therefore, the development and preparation of highly efficient and economical novel acid catalysts are crucial. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention proposes a polyionic liquid catalyst, its preparation method, and its application. The prepared catalyst exhibits excellent catalytic performance in the synthesis of 5-HMF from glucose in a two-phase solvent system.

[0008] To achieve the above objectives, the technical solution of the present invention is implemented as follows: A polyionic liquid catalyst, denoted as P(VEIM)-PH-Al, has the following structural formula: , n≥2.

[0009] A method for preparing a polyionic liquid catalyst includes the following steps: (1) Poly(1-vinyl-3-ethylimidazolium) (P(VEIM)) and acid fuchsin (PH) were added to solvent I and mixed evenly. Then the reaction was carried out. After the reaction was completed, the solvent was removed from the reaction solution by vacuum distillation and dried in an oven at a certain temperature for a certain time to obtain intermediate P(VEIM)-PH. (2) P(VEIM)-PH and aluminum salt were added to solvent II and mixed evenly. Then the reaction was carried out. After the reaction was completed, the solvent was removed by vacuum distillation and the solution was dried in an oven at a certain temperature for a certain time to obtain P(VEIM)-PH-Al.

[0010] The preparation method of P(VEIM) is as follows: 1-vinyl-3-ethylimidazole bromide is mixed with an initiator at a certain mass ratio, and anhydrous ethanol is used as a solvent to pass through the initiator. P(VEIM) solution is obtained by self-polymerization at a certain temperature and time. The anhydrous ethanol solvent is removed from the reaction solution by vacuum distillation, and P(VEIM) is dried in an oven at a certain temperature for a certain time.

[0011] The mass ratio of the initiator to the monomer 1-vinyl-3-ethylimidazole bromide is 0.01~0.03:1, the self-polymerization time is 6~15h, and the self-polymerization temperature is 40~70℃. The initiator is one of benzoyl peroxide and azobisisobutyronitrile.

[0012] In step (1), the mass ratio of acid fuchsin to poly(1-vinyl-3-ethylimidazole) is 0.2-0.6:1, the reaction temperature is 30-60℃, and the reaction time is 6-12h.

[0013] Solvent I is one or more of deionized water, methanol, ethanol, N,N-dimethylformamide, and dimethyl sulfoxide; the concentration of poly(1-vinyl-3-ethylimidazolium) in solvent I is 0.1-1 g / mL.

[0014] In step (2), the aluminum salt is one or more of aluminum chloride, aluminum nitrate, aluminum sulfate, and aluminum isopropoxide; the mass ratio of the aluminum salt to P(VEIM)-PH is 0.1-0.3:1, the reaction temperature is 25-50℃, and the reaction time is 4-10h.

[0015] Solvent II is one or more of deionized water, methanol, ethanol, N,N-dimethylformamide, and dimethyl sulfoxide; the concentration of P(VEIM)-PH in solvent II is 0.1-1 g / mL.

[0016] A method for preparing 5-hydroxymethylfurfural from glucose includes the following steps: adding glucose and the polyionic liquid catalyst of claim 1 into a solvent to obtain a reaction solution, then carrying out the reaction under a nitrogen atmosphere, and finally separating to obtain 5-hydroxymethylfurfural after the reaction is completed.

[0017] The concentration of glucose in the reaction solution is 0.1-0.4 g / mL; the mass ratio of polyionic liquid catalyst to glucose is 0.04-0.08:1; the reaction temperature is 90-120℃ and the reaction time is 4-8 h.

[0018] The solvent is a two-phase solvent composed of brine and a polar organic solvent in a mass ratio of 0.2-0.4:1.

[0019] The polar organic solvent is one of acetone, tetrahydrofuran, or methyl isobutyl ketone; the brine is an aqueous solution of sodium chloride with a salt concentration of 0.3-0.6 g / ml.

[0020] The beneficial effects of this invention are: 1. The novel polyionic liquid catalyst P(VEIM)-PH-Al prepared in this invention is used to catalyze the conversion of glucose to 5-hydroxymethylfurfural. Aluminum-based metal ions are used to coordinate modify the polyionic liquid, wherein aluminum ions (Al...) 3+ The small size and high charge density of P(VEIM) give it strong Lewis acidity, enabling it to effectively adsorb and activate molecules with lone pairs of electrons. Furthermore, it is less toxic and cheaper than other metal ions such as chromium. In addition, the acidic fuchsin structure in the catalyst contains abundant Brønsted sulfonic acid groups, providing a stable source of Brønsted acid for the dehydration of fructose to 5-HMF during the reaction. In summary, P(VEIM)-PH-Al possesses sufficient Brønsted and Lewis acid sites, enabling it to stably catalyze the conversion of glucose to 5-HMF. Tests have shown that this catalyst achieves a high yield for the conversion of glucose to 5-HMF, reaching a maximum of 73.26%.

[0021] 2. The catalyst prepared by this invention can be synthesized on a large scale at low temperatures and in a short time. The preparation method is simple and the process cycle is short. Compared with the preparation methods of traditional catalysts, this method does not require the participation of a large amount of volatile strong acid, and the preparation process is green and environmentally friendly, avoiding the large-scale emission of waste acid and waste alkali. In addition, compared with traditional homogeneous catalysts such as inorganic and organic acids, this catalyst has lower corrosiveness to equipment and relatively lower equipment requirements, and has the potential to achieve large-scale industrial preparation.

[0022] 3. The solvent system used in this invention is a two-phase solvent system of brine / low-boiling-point organic solvent. After the reaction is completed, the product 5-HMF is concentrated in the low-boiling-point organic solvent, so that glucose can be converted into 5-HMF with high purity by simple phase separation and vacuum distillation. The purification method is simple. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The image shows the high-performance liquid chromatogram of 5-HMF.

[0025] Figure 2 This is a standard curve plot using the 5-HMF external standard method.

[0026] Figure 3 The image shown is the P(VEIM) plot prepared in Example 1.

[0027] Figure 4 The image shows the P(VEIM)-PH diagram prepared in Example 1.

[0028] Figure 5 The image shows the P(VEIM)-PH-Al prepared in Example 1.

[0029] Figure 6 The 5-HMF prepared in Example 9 of this invention 1 H NMR spectrum.

[0030] Figure 7 The 5-HMF prepared in Example 9 of this invention 13 C NMR spectrum.

[0031] Figure 8 This is a schematic diagram of the catalyst synthesis process. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In all examples, the glucose isomerization dehydration products were diluted with water or ethanol and filtered through a 0.22 μm nylon filter. They were then qualitatively and quantitatively analyzed by Waters Arc HPLC with an XBridge® C18 5 μm (4.6*250 mm) column. Peak times were as follows: Figure 1 As shown; the concentrations of substances quantitatively analyzed by high performance liquid chromatography were calculated using an external standard method fitting function. The standard curve for 5-HMF detected by a variable ultraviolet detector is shown below. Figure 2 As shown in Table 1, the specific operating conditions for high-performance liquid chromatography (HPLC) are as follows.

[0034] Table 1 Operating conditions for high performance liquid chromatography The yield of 5-HMF is calculated using the following formula.

[0035] Example 1 A method for preparing a polyionic liquid catalyst, the method comprising the following steps: (1) Preparation of P(VEIM)-A: Weigh 15g of monomer 1-vinyl-3-ethylimidazole bromide into a 100ml three-necked flask equipped with a reflux condenser and a constant pressure dropping funnel, dissolve it in 45g of anhydrous ethanol, add 0.15g of initiator azobisisobutyronitrile (i.e., initiator to monomer mass ratio 0.01:1) into the constant pressure dropping funnel, dissolve it in 15g of ethanol, heat to 60℃, add the initiator dropwise at a rate of 3-5s / drop, and simultaneously stir magnetically at 600rpm. After the addition is complete, keep at 60℃ for 12h to carry out the reaction. After the reaction is complete, P(VEIM)-A solution is obtained. Remove the ethanol solvent from the reaction solution by vacuum distillation, and dry it in an oven at 100℃ for 4.5h to obtain P(VEIM)-A, with the morphology as shown in the figure. Figure 3 As shown.

[0036] (2) Preparation of P(VEIM)-PH-A: 12g of P(VEIM)-A and 6g of acid fuchsin (pH) (i.e., pH to P(VEIM) mass ratio 0.5:1) were added to a 100ml single-necked flask, followed by 30ml of anhydrous ethanol. The mixture was magnetically stirred at 35℃ for 10h. After the reaction was complete, a P(VEIM)-PH-A solution was obtained. The ethanol solvent was removed from the reaction solution by vacuum distillation, and the solution was dried in an oven at 100℃ for 4.5h to obtain P(VEIM)-PH-A, with the following morphology. Figure 4 As shown.

[0037] (3) Preparation of P(VEIM)-PH-Al-A: 10g of P(VEIM)-PH-A and 2g of aluminum chloride hexahydrate (AlCl3·6H2O) (i.e., the mass ratio of AlCl3·6H2O to P(VEIM)-PH-A is 0.2:1) were added to a 50ml single-necked flask. 20ml of anhydrous ethanol was added, and the mixture was magnetically stirred at 30℃ for 9h. After the reaction was completed, a P(VEIM)-PH-Al-A solution was obtained. The ethanol solvent was removed from the reaction solution by vacuum distillation, and the solution was dried in an oven at 100℃ for 4.5h to obtain the catalyst P(VEIM)-PH-Al-A, with the morphology as shown in the figure. Figure 5 As shown.

[0038] Example 2 A method for preparing a polyionic liquid catalyst, the method comprising the following steps: (1) Preparation of P(VEIM)-B: Weigh 15g of monomer 1-vinyl-3-ethylimidazole bromide into a 100ml three-necked flask equipped with a reflux condenser and a constant pressure dropping funnel, dissolve it with 45g of anhydrous ethanol, add 0.3g of initiator azobisisobutyronitrile (i.e., initiator to monomer mass ratio 0.02:1) into the constant pressure dropping funnel, dissolve it with 15g of ethanol, heat to 70℃, add the initiator dropwise at a rate of 3-5s / drop, and simultaneously stir magnetically at a speed of 600rpm. After the dropwise addition is complete, keep it at 70℃ for 7h to carry out the reaction. After the reaction is completed, P(VEIM)-B solution is obtained. Remove the ethanol solvent from the reaction solution by vacuum distillation and dry it in an oven at 120℃ for 3h to obtain P(VEIM)-B.

[0039] (2) Preparation of P(VEIM)-PH-B: Add 12g of P(VEIM)-B and 4.2g of acid fuchsin (PH) (i.e., the mass ratio of PH to P(VEIM) is 0.35:1) to a 100ml single-necked flask, add 30ml of anhydrous ethanol, and stir magnetically at 45℃ for 8h. After the reaction is completed, P(VEIM)-PH-B solution is obtained. Remove the ethanol solvent from the reaction solution by vacuum distillation and dry it in an oven at 120℃ for 3h to obtain P(VEIM)-PH-B.

[0040] (3) Preparation of P(VEIM)-PH-Al-B: Add 10g of P(VEIM)-PH-B and 3g of aluminum chloride hexahydrate (AlCl3·6H2O) to a 50ml single-necked flask (i.e., the mass ratio of AlCl3·6H2O to P(VEIM)-PH-B is 0.3:1), add 20ml of anhydrous ethanol, and stir magnetically at 45℃ for 6h. After the reaction is completed, P(VEIM)-PH-Al-B solution is obtained. Remove the ethanol solvent from the reaction solution by vacuum distillation and dry it in an oven at 120℃ for 3h to obtain the catalyst P(VEIM)-PH-Al-B.

[0041] Example 3 A method for preparing a polyionic liquid catalyst, the method comprising the following steps: (1) Preparation of P(VEIM)-C: Weigh 15g of monomer 1-vinyl-3-ethylimidazole bromide into a 100ml three-necked flask equipped with a reflux condenser and a constant pressure dropping funnel, dissolve it with 45g of anhydrous ethanol, add 0.45g of initiator benzoyl peroxide (i.e., initiator to monomer mass ratio 0.03:1) into the constant pressure dropping funnel, dissolve it with 15g of ethanol, heat to 45℃, add the initiator dropwise at a rate of 3-5s / drop, and simultaneously stir magnetically at a speed of 600rpm. After the dropwise addition is complete, keep the temperature at 45℃ for 14h to carry out the reaction. After the reaction is completed, P(VEIM)-C solution is obtained. Remove the ethanol solvent from the reaction solution by vacuum distillation and dry it in an oven at 125℃ for 2h to obtain P(VEIM)-C.

[0042] (2) Preparation of P(VEIM)-PH-C: Add 12g of P(VEIM)-C and 3g of acid fuchsin (PH) (i.e., the mass ratio of PH to P(VEIM) is 0.25:1) to a 100ml single-necked flask, add 30ml of anhydrous ethanol, and stir magnetically at 60℃ for 6h. After the reaction is completed, P(VEIM)-PH-C solution is obtained. Remove the ethanol solvent from the reaction solution by vacuum distillation and dry it in an oven at 125℃ for 2h to obtain P(VEIM)-PH-C.

[0043] (3) Preparation of P(VEIM)-PH-Al-C: Add 10g of P(VEIM)-PH-C and 1g of aluminum chloride hexahydrate (AlCl3·6H2O) to a 50ml single-necked flask (i.e., the mass ratio of AlCl3·6H2O to P(VEIM)-PH-C is 0.1:1), add 20ml of anhydrous ethanol, and stir magnetically at 50℃ for 4h. After the reaction is completed, P(VEIM)-PH-Al-C solution is obtained. Remove the ethanol solvent from the reaction solution by vacuum distillation and dry it in an oven at 125℃ for 2h to obtain the catalyst P(VEIM)-PH-Al-C.

[0044] Example 4 A method for preparing a polyionic liquid catalyst, the method comprising the following steps: (1) Preparation of P(VEIM): Weigh 15g of monomer 1-vinyl-3-ethylimidazole bromide into a 100ml three-necked flask equipped with a reflux condenser and a constant pressure dropping funnel, dissolve it with 45g of anhydrous ethanol, add 0.45g of initiator benzoyl peroxide (i.e., initiator to monomer mass ratio 0.03:1) into the constant pressure dropping funnel, dissolve it with 15g of ethanol, heat to 45℃, add the initiator dropwise at a rate of 3-5s / drop, and stir magnetically at a speed of 600rpm at the same time. After the dropwise addition is completed, keep it at 45℃ for 14h to carry out the reaction. After the reaction is completed, P(VEIM) solution is obtained. Remove the ethanol solvent from the reaction solution by vacuum distillation and dry it in an oven at 125℃ for 2h to obtain P(VEIM).

[0045] (2) Preparation of P(VEIM)-PH: Add 10g of P(VEIM) and 6g of acid fuchsin (PH) (i.e., the mass ratio of PH to P(VEIM) is 0.6:1) to a 200ml single-necked flask, add 100ml of anhydrous ethanol, and stir magnetically at 30℃ for 12h. After the reaction is completed, P(VEIM)-PH solution is obtained. Remove the ethanol solvent from the reaction solution by vacuum distillation and dry it in an oven at 125℃ for 2h to obtain P(VEIM)-PH.

[0046] (3) Preparation of P(VEIM)-PH-Al: Add 10g of P(VEIM)-PH and 2g of aluminum nitrate to a 200ml single-necked flask, add 100ml of anhydrous ethanol, and stir magnetically at 25℃ for 10h. After the reaction is completed, P(VEIM)-PH-Al solution is obtained. Remove the ethanol solvent from the reaction solution by vacuum distillation and dry it in an oven at 125℃ for 2h to obtain the catalyst P(VEIM)-PH-Al.

[0047] Example 5 A method for preparing a polyionic liquid catalyst, the method comprising the following steps: (1) Preparation of P(VEIM): Weigh 15g of monomer 1-vinyl-3-ethylimidazole bromide into a 100ml three-necked flask equipped with a reflux condenser and a constant pressure dropping funnel, dissolve it with 45g of anhydrous ethanol, add 0.45g of initiator benzoyl peroxide (i.e., initiator to monomer mass ratio 0.03:1) into the constant pressure dropping funnel, dissolve it with 15g of ethanol, heat to 45℃, add the initiator dropwise at a rate of 3-5s / drop, and stir magnetically at a speed of 600rpm at the same time. After the dropwise addition is completed, keep it at 45℃ for 14h to carry out the reaction. After the reaction is completed, P(VEIM) solution is obtained. Remove the ethanol solvent from the reaction solution by vacuum distillation and dry it in an oven at 125℃ for 2h to obtain P(VEIM).

[0048] (2) Preparation of P(VEIM)-PH: Add 10g of P(VEIM) and 2g of acid fuchsin (PH) (i.e., the mass ratio of PH to P(VEIM) is 0.2:1) to a 50ml single-necked flask, add 10ml of anhydrous ethanol, and stir magnetically at 50℃ for 8h. After the reaction is completed, P(VEIM)-PH solution is obtained. Remove the ethanol solvent from the reaction solution by vacuum distillation and dry it in an oven at 125℃ for 2h to obtain P(VEIM)-PH.

[0049] (3) Preparation of P(VEIM)-PH-Al: Add 10g of P(VEIM)-PH and 3g of aluminum isopropoxide to a 50ml single-necked flask, add 10ml of anhydrous ethanol, and stir magnetically at 40℃ for 6h. After the reaction is completed, P(VEIM)-PH-Al solution is obtained. Remove the ethanol solvent from the reaction solution by vacuum distillation and dry it in an oven at 125℃ for 2h to obtain the catalyst P(VEIM)-PH-Al.

[0050] Performance testing of polyionic liquid catalysts for the conversion of glucose to 5-HMF: Application Example 1 The synthesis of 5-HMF using P(VEIM)-PH-Al-A synthesized in Example 1 as a catalyst includes the following steps: 3g of glucose raw material was added to a 75ml pressure-resistant glass flask, along with 4g of water, 10g of tetrahydrofuran (a low-boiling-point polar organic solvent with a glucose concentration of 0.21g / ml and a water-to-solvent mass ratio of 0.4:1), 1.4g of sodium chloride (i.e., a salt concentration of 0.35g / ml in water), and 0.15g of catalyst P(VEIM)-PH-Al-A (i.e., a catalyst-to-glucose mass ratio of 0.05:1). The reaction was carried out at 100℃ for 6 hours under a nitrogen atmosphere to catalyze the conversion of glucose to 5-hydroxymethylfurfural. After the reaction, the mixture was cooled to room temperature in an ice-water bath. The organic and aqueous phases were separated, and the organic phase was collected. A small amount of the organic phase solution was diluted and quantitatively analyzed by high-performance liquid chromatography (HPLC). The 5-HMF content was determined by external standard method, and the results are shown in Table 2. The low-boiling-point organic solvent was removed by vacuum distillation, and the product was dried in an oven to obtain pure 5-HMF.

[0051] 5-HMF 1H NMR spectrum as shown Figure 6 As shown, 5-HMF(CDCl3) has the following δ values: 2.87 (1H, aH); 4.70 (2H, bH); 6.50 (1H, cH); 7.20 (1H, dH); 9.55 (1H, eH). The carbon NMR spectrum of 5-HMF is shown below. Figure 7As shown, the characteristic shift peaks in the 5-HMF NMR spectrum are consistent with the expected structure, indicating that 5-HMF was successfully synthesized. δ: 56.54 (C-1); 109.00 (C-3); 122.02 (C-4); 151.30 (C-5); 159.77 (C-2); 176.74 (C-6).

[0052] Application Example 2 The synthesis of 5-HMF using P(VEIM)-PH-Al-A synthesized in Example 1 as a catalyst includes the following steps: 3g of glucose raw material was added to a 75ml pressure-resistant glass flask, along with 2g of water, 6.6g of low-boiling-point polar organic solvent methyl isobutyl ketone (glucose concentration 0.35g / ml, water to low-boiling-point solvent mass ratio 0.3:1), 0.9g of sodium chloride (i.e., salt concentration in water 0.45g / ml), and 0.21g of catalyst P(VEIM)-PH-Al-A (i.e., catalyst to glucose mass ratio 0.07:1). The reaction was carried out at 90℃ for 8 hours under a nitrogen atmosphere to catalyze the conversion of glucose to 5-hydroxymethylfurfural. After the reaction, the mixture was cooled to room temperature in an ice-water bath, the organic and aqueous phases were separated, and the organic phase was collected. A small amount of the organic phase solution was diluted and quantitatively analyzed by high-performance liquid chromatography (HPLC). The 5-HMF content was determined by external standard method, and the results are shown in Table 2.

[0053] Application Example 3 The synthesis of 5-HMF using P(VEIM)-PH-Al-A synthesized in Example 1 as a catalyst includes the following steps: 3g of glucose raw material was added to a 75ml pressure-resistant glass flask, along with 2g of water, 18g of low-boiling-point polar organic solvent acetone (glucose concentration 0.15g / ml, water to low-boiling-point solvent mass ratio 0.2:1), 2.2g of sodium chloride (i.e., salt concentration in water 0.55g / ml), and 0.12g of catalyst P(VEIM)-PH-Al-A (i.e., catalyst to glucose mass ratio 0.04:1). The reaction was carried out at 120℃ for 4h under a nitrogen atmosphere to catalyze the conversion of glucose to 5-hydroxymethylfurfural. After the reaction, the mixture was cooled to room temperature in an ice-water bath, the organic and aqueous phases were separated, and the organic phase was collected. A small amount of the organic phase solution was diluted and quantitatively analyzed by high-performance liquid chromatography (HPLC). The 5-HMF content was determined by external standard method, and the results are shown in Table 2.

[0054] Application Example 4 The synthesis of 5-HMF using P(VEIM)-PH-Al-B synthesized in Example 2 as a catalyst includes the following steps: 3g of glucose raw material was added to a 75ml pressure-resistant glass flask, along with 2g of water, 6.6g of low-boiling-point polar organic solvent methyl isobutyl ketone (glucose concentration 0.35g / ml, water to low-boiling-point solvent mass ratio 0.3:1), 0.9g of sodium chloride (i.e., salt concentration in water 0.45g / ml), and 0.18g of catalyst P(VEIM)-PH-Al-B (i.e., catalyst to glucose mass ratio 0.06:1). The reaction was carried out at 90℃ for 8 hours under a nitrogen atmosphere to catalyze the conversion of glucose to 5-hydroxymethylfurfural. After the reaction, the mixture was cooled to room temperature in an ice-water bath, the organic and aqueous phases were separated, and the organic phase was collected. A small amount of the organic phase solution was diluted and quantitatively analyzed by high-performance liquid chromatography (HPLC). The 5-HMF content was determined by external standard method, and the results are shown in Table 2.

[0055] Application Example 5 The synthesis of 5-HMF using P(VEIM)-PH-Al-B synthesized in Example 2 as a catalyst includes the following steps: 3g of glucose raw material was added to a 75ml pressure-resistant glass flask, along with 4g of water, 10g of tetrahydrofuran (a low-boiling-point polar organic solvent with a glucose concentration of 0.21g / ml and a water-to-solvent mass ratio of 0.4:1), 1.4g of sodium chloride (i.e., a salt concentration of 0.35g / ml in water), and 0.24g of catalyst P(VEIM)-PH-Al-B (i.e., a catalyst-to-glucose mass ratio of 0.08:1). The reaction was carried out at 100℃ for 6 hours under a nitrogen atmosphere to catalyze the conversion of glucose to 5-hydroxymethylfurfural. After the reaction, the mixture was cooled to room temperature in an ice-water bath. The organic and aqueous phases were separated, and the organic phase was collected. A small amount of the organic phase solution was diluted and quantitatively analyzed by high-performance liquid chromatography (HPLC). The 5-HMF content was determined by the external standard method, and the results are shown in Table 2.

[0056] Application Example 6 The synthesis of 5-HMF using P(VEIM)-PH-Al-B synthesized in Example 2 as a catalyst includes the following steps: 3g of glucose raw material was added to a 75ml pressure-resistant glass flask, along with 2g of water, 18g of low-boiling-point polar organic solvent acetone (glucose concentration 0.15g / ml, water to low-boiling-point solvent mass ratio 0.2:1), 2.2g of sodium chloride (i.e., salt concentration in water 0.55g / ml), and 0.09g of catalyst P(VEIM)-PH-Al-B (i.e., catalyst to glucose mass ratio 0.03:1). The reaction was carried out at 120℃ for 4h under a nitrogen atmosphere to catalyze the conversion of glucose to 5-hydroxymethylfurfural. After the reaction, the mixture was cooled to room temperature in an ice-water bath, the organic and aqueous phases were separated, and the organic phase was collected. A small amount of the organic phase solution was diluted and quantitatively analyzed by high-performance liquid chromatography (HPLC). The 5-HMF content was determined by external standard method, and the results are shown in Table 2.

[0057] Application Example 7 The synthesis of 5-HMF using P(VEIM)-PH-Al-C synthesized in Example 3 as a catalyst includes the following steps: 3g of glucose raw material was added to a 75ml pressure-resistant glass flask, along with 4g of water, 10g of low-boiling-point polar organic solvent acetone (glucose concentration 0.21g / ml, water to low-boiling-point solvent mass ratio 0.4:1), 1.4g of sodium chloride (i.e., salt concentration in water 0.35g / ml), and 0.15g of catalyst P(VEIM)-PH-Al-C (i.e., catalyst to glucose mass ratio 0.05:1). The reaction was carried out at 120℃ for 4h under a nitrogen atmosphere to catalyze the conversion of glucose to 5-hydroxymethylfurfural. After the reaction, the mixture was cooled to room temperature in an ice-water bath, the organic and aqueous phases were separated, and the organic phase was collected. A small amount of the organic phase solution was diluted and quantitatively analyzed by high-performance liquid chromatography (HPLC). The 5-HMF content was determined by external standard method, and the results are shown in Table 2.

[0058] Application Example 8 The synthesis of 5-HMF using P(VEIM)-PH-Al-C synthesized in Example 3 as a catalyst includes the following steps: 3g of glucose raw material was added to a 75ml pressure-resistant glass flask, along with 4.5g of water, 11.3g of low-boiling-point polar organic solvent acetone (glucose concentration 0.19g / ml, water to low-boiling-point solvent mass ratio 0.4:1), 2.7g of sodium chloride (i.e., salt concentration in water 0.6g / ml), and 0.18g of catalyst P(VEIM)-PH-Al-C (i.e., catalyst to glucose mass ratio 0.06:1). The reaction was carried out at 110℃ for 6 hours under a nitrogen atmosphere to catalyze the conversion of glucose to 5-hydroxymethylfurfural. After the reaction, the mixture was cooled to room temperature in an ice-water bath, the organic and aqueous phases were separated, and the organic phase was collected. A small amount of the organic phase solution was diluted and quantitatively analyzed by high-performance liquid chromatography (HPLC). The 5-HMF content was determined by external standard method, and the results are shown in Table 2.

[0059] Application Example 9 The synthesis of 5-HMF using P(VEIM)-PH-Al-C synthesized in Example 3 as a catalyst includes the following steps: 3g of glucose raw material was added to a 75ml pressure-resistant glass flask, along with 2g of water, 6.6g of low-boiling-point polar organic solvent methyl isobutyl ketone (glucose concentration 0.35g / ml, water to low-boiling-point solvent mass ratio 0.3:1), 0.9g of sodium chloride (i.e., salt concentration in water 0.45g / ml), and 0.24g of catalyst P(VEIM)-PH-Al-C (i.e., catalyst to glucose mass ratio 0.08:1). The reaction was carried out at 100℃ for 8 hours under a nitrogen atmosphere to catalyze the conversion of glucose to 5-hydroxymethylfurfural. After the reaction, the mixture was cooled to room temperature in an ice-water bath, the organic and aqueous phases were separated, and the organic phase was collected. A small amount of the organic phase solution was diluted and quantitatively analyzed by high-performance liquid chromatography (HPLC). The 5-HMF content was determined by external standard method, and the results are shown in Table 2.

[0060] Comparative Example 1 The synthesis of 5-HMF using P(VEIM)-A synthesized in Example 1 as a catalyst includes the following steps: The reaction conditions were the same as in Application Example 1, except that the catalyst P(VEIM)-PH-Al-A was replaced with P(VEIM)-A. 3g of glucose raw material was added to a 75ml pressure-resistant glass flask, along with 4g of water, 10g of the low-boiling-point polar organic solvent tetrahydrofuran (glucose concentration 0.21g / ml, water to low-boiling-point solvent mass ratio 0.4:1), 1.4g of sodium chloride (i.e., salt concentration in water 0.35g / ml), and 0.15g of P(VEIM) (i.e., catalyst to glucose mass ratio 0.05:1). The reaction was carried out at 100℃ for 6 hours under a nitrogen atmosphere to catalyze the conversion of glucose to 5-hydroxymethylfurfural. After the reaction, the mixture was cooled to room temperature in an ice-water bath, the organic and aqueous phases were separated, and the organic phase was collected. A small amount of the organic phase solution was diluted and quantitatively analyzed by high-performance liquid chromatography (HPLC). The 5-HMF content was determined by external standard method, and the results are shown in Table 2.

[0061] Comparative Example 2 The synthesis of 5-HMF using P(VEIM)-PH-A synthesized in Example 1 as a catalyst includes the following steps: The reaction conditions were the same as in Application Example 1, except that the catalyst P(VEIM)-PH-Al-A was replaced with P(VEIM)-PH-A. Specifically, 3g of glucose raw material was added to a 75ml pressure-resistant glass flask, along with 4g of water, 10g of the low-boiling-point polar organic solvent tetrahydrofuran (glucose concentration 0.21g / ml, water to low-boiling-point solvent mass ratio 0.4:1), 1.4g of sodium chloride (i.e., salt concentration in water 0.35g / ml), and 0.15g of P(VEIM)-A (i.e., catalyst to glucose mass ratio 0.05:1). The reaction was carried out at 100℃ for 6 hours under a nitrogen atmosphere to catalyze the conversion of glucose to 5-hydroxymethylfurfural. After the reaction, the mixture was cooled to room temperature in an ice-water bath, the organic and aqueous phases were separated, and the organic phase was collected. A small amount of the organic phase solution was diluted and quantitatively analyzed by high-performance liquid chromatography (HPLC). The 5-HMF content was determined by the external standard method, and the results are shown in Table 2.

[0062] Comparative Example 3 The synthesis of 5-HMF using P(VEIM)-PH-B synthesized in Example 2 as a catalyst includes the following steps: The reaction conditions were the same as in Application Example 4, except that the catalyst P(VEIM)-PH-Al-B was replaced with P(VEIM)-PH-B. Specifically, 3g of glucose raw material was added to a 75ml pressure-resistant glass flask, along with 4g of water, 10g of the low-boiling-point polar organic solvent tetrahydrofuran (glucose concentration 0.21g / ml, water to low-boiling-point solvent mass ratio 0.4:1), 1.4g of sodium chloride (i.e., salt concentration in water 0.35g / ml), and 0.24g of catalyst P(VEIM)-PH-B (i.e., catalyst to glucose mass ratio 0.08:1). The reaction was carried out at 100℃ for 6 hours under a nitrogen atmosphere to catalyze the conversion of glucose to 5-hydroxymethylfurfural. After the reaction, the mixture was cooled to room temperature in an ice-water bath, the organic and aqueous phases were separated, and the organic phase was collected. A small amount of the organic phase solution was diluted and quantitatively analyzed by high-performance liquid chromatography (HPLC). The 5-HMF content was determined by the external standard method, and the results are shown in Table 2.

[0063] Comparative Example 4 The synthesis of 5-HMF using P(VEIM)-PH-C synthesized in Example 3 as a catalyst includes the following steps: The reaction conditions were the same as in Application Example 7, except that the catalyst P(VEIM)-PH-Al-C was replaced with P(VEIM)-PH-C. Specifically, 3g of glucose raw material was added to a 75ml pressure-resistant glass flask, along with 4.5g of water, 11.3g of the low-boiling-point polar organic solvent acetone (glucose concentration 0.19g / ml, water to low-boiling-point solvent mass ratio 0.4:1), 2.7g of sodium chloride (i.e., salt concentration in water 0.6g / ml), and 0.18g of catalyst P(VEIM)-PH-Al-C (i.e., catalyst to glucose mass ratio 0.06:1). The reaction was carried out at 110℃ for 6 hours under a nitrogen atmosphere to catalyze the conversion of glucose to 5-hydroxymethylfurfural. After the reaction, the mixture was cooled to room temperature in an ice-water bath, the organic and aqueous phases were separated, and the organic phase was collected. A small amount of the organic phase solution was diluted and quantitatively analyzed by high-performance liquid chromatography (HPLC). The 5-HMF content was determined by the external standard method, and the results are shown in Table 2.

[0064] Table 2 As shown in Table 2, the prepared polyionic liquid catalyst has a high yield for the conversion of glucose to 5-HMF. Among them, the P(VEIM)-PH-Al-C catalyst has a yield of up to 73.26% for the conversion of glucose to 5-HMF. Compared with Comparative Example 1, which only contains the ionic liquid self-polymer P(VEIM), it can be seen that the P(VEIM) catalyst has almost no catalytic activity, indicating that P(VEIM) itself does not have acidic sites available for catalysis and cannot play the role of acid catalysis.

[0065] Comparing Application Example 1 with Comparative Example 2, Application Example 4 with Comparative Example 3, and Application Example 7 with Comparative Example 4, it can be seen that when acidic fuchsin containing a large number of Brønsted acid sites is introduced into the polyionic liquid, according to the reaction mechanism, P(VEIM)-PH still has a relatively low yield due to the lack of aluminum-based metal ions to provide Lewis acid sites. This indirectly proves that the prepared aluminum ion complexed polyionic liquid-acidic fuchsin catalyst P(VEIM)-PH-Al has higher activity for the preparation of 5-HMF from glucose. Figure 8 As shown, the catalytic performance of P(VEIM)-PH-Al is attributed to the combined catalytic effect of the large number of Brønsted acid sulfonic acid sites contained in the acid fuchsin portion of the catalyst structure and the large number of Lewis acid sites provided by the complexed and coordinated aluminum-based metal ions. Moreover, the polybrominated 1-vinyl-3-ethylimidazolium P(VEIM) plays the role of a "bridge" to further assist the combination of the Brønsted acid sites and Lewis acid sites in series. The combined effect gives P(VEIM)-PH-Al excellent catalytic performance.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polyionic liquid catalyst, characterized in that, The polyionic liquid catalyst is designated P(VEIM)-PH-Al, and its structural formula is shown below: ，n≥2。 2. The method for preparing the polyionic liquid catalyst according to claim 1, characterized in that, Includes the following steps: (1) Poly(1-vinyl-3-ethylimidazolium) and acid fuchsin were added to solvent I and mixed evenly, and then the reaction was carried out to prepare intermediate P(VEIM)-PH; (2) P(VEIM)-PH and aluminum salt were added to solvent II and mixed evenly, and then the reaction was carried out to prepare P(VEIM)-PH-Al.

3. The method for preparing the polyionic liquid catalyst according to claim 2, characterized in that, In step (1), the mass ratio of acid fuchsin to poly(1-vinyl-3-ethylimidazole) is 0.2-0.6:1, the reaction temperature is 30-60℃, and the reaction time is 6-12h.

4. The method for preparing the polyionic liquid catalyst according to claim 3, characterized in that, Solvent I is one or more of deionized water, methanol, ethanol, N,N-dimethylformamide, and dimethyl sulfoxide; the concentration of poly(1-vinyl-3-ethylimidazolium) in solvent I is 0.1-1 g / mL.

5. The method for preparing the polyionic liquid catalyst according to claim 2, characterized in that, In step (2), the aluminum salt is one or more of aluminum chloride, aluminum nitrate, aluminum sulfate, and aluminum isopropoxide; the mass ratio of the aluminum salt to P(VEIM)-PH is 0.1-0.3:1, the reaction temperature is 25-50℃, and the reaction time is 4-10h.

6. The method for preparing the polyionic liquid catalyst according to claim 5, characterized in that, Solvent II is one or more of deionized water, methanol, ethanol, N,N-dimethylformamide, and dimethyl sulfoxide; the concentration of P(VEIM)-PH in solvent II is 0.1-1 g / mL.

7. A method for preparing 5-hydroxymethylfurfural from glucose, characterized in that, Includes the following steps: Glucose and the polyionic liquid catalyst of claim 1 were added to a solvent to obtain a reaction solution, which was then reacted under a nitrogen atmosphere. After the reaction was completed, 5-hydroxymethylfurfural was obtained by separation.

8. The method for preparing 5-hydroxymethylfurfural from glucose according to claim 7, characterized in that, The concentration of glucose in the reaction solution is 0.1-0.4 g / mL; the mass ratio of polyionic liquid catalyst to glucose is 0.04-0.08:1; the reaction temperature is 90-120℃ and the reaction time is 4-8 h.

9. The method for preparing 5-hydroxymethylfurfural from glucose according to claim 8, characterized in that, The solvent is a two-phase solvent composed of brine and a polar organic solvent in a mass ratio of 0.2-0.4:

1.

10. The method for preparing 5-hydroxymethylfurfural from glucose according to claim 9, characterized in that, The polar organic solvent is one of acetone, tetrahydrofuran, or methyl isobutyl ketone; the brine is an aqueous solution of sodium chloride with a salt concentration of 0.3-0.6 g / ml.

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