A multifunctional nanocarbon catalyst and a method for catalyzing carbohydrates to synthesize 2,5-furandicarboxylic acid

Abstract

The present invention discloses a multifunctional nanocarbon catalyst and a method for catalytically synthesizing 2,5-furandicarboxylic acid from carbohydrates. A multifunctional nanocarbon catalyst is prepared by the following steps: S1. Lignin is dispersed in ethanol, stirred and reacted, and after filtration, solid R1 and an ethanol solution are obtained. The ethanol in the ethanol solution is evaporated to obtain solid R2; S2. R1 and / or R2 are dissolved in tetrahydrofuran, and then the tetrahydrofuran solution is dropped into water to prepare a suspension containing lignin nanoparticles NR1 and / or NR2. A PdCl2 hydrochloric acid solution is added to the suspension and stirred for an in-situ reduction reaction to obtain a mixture of Pd / NR1 and / or Pd / NR2; S3. The mixture is added to an aqueous solution of a sulfonating agent and subjected to hydrothermal reaction to obtain a multifunctional nanocarbon catalyst. The present invention uses in-situ reduction and hydrothermal reaction to prepare a multifunctional nanocarbon catalyst, which catalytically synthesizes 2,5-furandicarboxylic acid from monosaccharides by a two-step method under mild conditions, and the target product has a high yield.

Description

Technical Field:

[0001] The present invention relates to the technical field of organic chemistry, and particularly relates to a multifunctional nano-carbon catalyst and a method for catalytically synthesizing 2,5-furandicarboxylic acid from carbohydrates. Background Art:

[0002] Biomass carbohydrates, as a renewable carbon source, are one of the raw materials for producing bio-based chemicals. Non-grain biomass is rich in reserves, has a short growth cycle, and is easy to depolymerize. It has a high content of carbohydrates and is easy to extract, making it a very promising biomass resource. 5-Hydroxymethylfurfural (5-HMF) is one of the key intermediates derived from the dehydration of carbohydrates, and its derivatives have the potential to replace a variety of monomers used in polymer synthesis. Among them, 2,5-furandicarboxylic acid (FDCA) is one of the most valuable ones because it is the main monomer for synthesizing poly(ethylene furandicarboxylate) (PEF), and PEF is widely regarded as a viable alternative to poly(ethylene terephthalate) (PET) in food and beverage packaging. Currently, in the process of synthesizing 5-HMF from biomass carbohydrates, carbon catalysts are widely used and have high efficiency. Compared with conventional carbon materials, nano-carbon materials not only have the characteristics of easy preparation, high conductivity, and wide source, but also have high stability and are more easily dispersed. Therefore, using nano-carbon-based solid acids to catalytically synthesize 5-HMF will be beneficial to improving the product performance. In addition, a palladium / carbon catalyst can be used to catalytically prepare FDCA from 5-HMF, but sodium borohydride or hydrogen needs to be used to reduce palladium metal during the catalyst preparation process. The reduction time of sodium borohydride is long and it is toxic; hydrogen reduction requires high temperature, and the safety of hydrogen use needs to be considered, thus reducing the catalyst preparation efficiency. These methods are prone to agglomeration of palladium nanoparticles during the reduction process, reducing the catalytic activity of the catalyst. Therefore, how to develop a new type of catalyst and solvent system to improve the efficiency of converting biomass carbohydrates into FDCA is of great significance for the industrial application of converting biomass into high-added-value energy chemicals, and it is also a difficult problem that the field has been eager to solve. Summary of the Invention:

[0003] Aiming at the problems existing in the prior art, the present invention provides a multifunctional nano-carbon catalyst and a method for catalytically synthesizing 2,5-furandicarboxylic acid from carbohydrates. The multifunctional nano-carbon catalyst proposed by the present invention can simply and efficiently catalyze the synthesis of 2,5-furandicarboxylic acid from carbohydrates, with a high yield of the target product and easy separation.

[0004] The purpose of the present invention is to provide a multifunctional nano-carbon catalyst, which is prepared by the following steps:

[0005] S1. Disperse lignin in ethanol, stir and react, filter to obtain residual solid R1 and an ethanol solution, and evaporate the ethanol from the ethanol solution to obtain solid R2;

[0006] S2. Dissolve R1 and / or R2 in tetrahydrofuran to obtain a tetrahydrofuran solution containing R1 and / or R2, then drop the tetrahydrofuran solution containing R1 and / or R2 into water to prepare a suspension containing lignin nanoparticles NR1 and / or NR2. Add a PdCl2 hydrochloric acid solution to the suspension for in-situ reduction, stir and react at 70 °C - 90 °C for 5 - 7 h, and obtain Pd / NR1 and / or Pd / NR2 after centrifugal separation and drying;

[0007] S3. Add Pd / NR1 and / or Pd / NR2 to a solution with a sulfonating agent concentration of 0.6 - 1.8 g / mL, carry out a hydrothermal reaction at 160 °C - 200 °C for 4 - 12 h, then wash, centrifuge and dry the product to obtain a multifunctional nanocarbon catalyst, and the multifunctional nanocarbon catalyst includes Pd / CNR1 and / or Pd / CNR2, that is, Pd / CNR1, Pd / CNR2, and a mixture of Pd / CNR1 and Pd / CNR2.

[0008] In step S1, the yield of solid R1 is 40% - 45%, the molecular mass is 3100 - 3400 g / mol, the yield of solid R2 is 55% - 60%, and the molecular mass is 1450 - 1800 g / mol.

[0009] Preferably, the solid-liquid ratio of lignin to ethanol in step S1 is 0.1 - 0.5 g / mL. Stir and react in step S1 for 1 - 3 h.

[0010] Preferably, the mass concentration of R1 and / or R2 in the tetrahydrofuran solution in step S2 is 0.5 - 5 g / L.

[0011] More preferably, dissolve R1 and R2 with a mass ratio of 1:3 - 3:1 in tetrahydrofuran to obtain a tetrahydrofuran solution containing R1 and R2. Even more preferably, the mass ratio of R1 to R2 is 1:1.

[0012] Preferably, the mass ratio of PdCl2 to lignin in step S2 is 1:5 - 1:25, and the concentration of PdCl2 in the PdCl2 hydrochloric acid solution is 0.5 - 2 g / L.

[0013] Preferably, the sulfonating agent in step S3 is selected from one of p-toluenesulfonic acid, p-hydroxybenzenesulfonic acid, and concentrated sulfuric acid; the mass ratio of the sulfonating agent to lignin is 80:1 - 20:1.

[0014] The present invention also protects a method for catalyzing the synthesis of 2,5-furandicarboxylic acid from carbohydrates, including the following steps:

[0015] (1) Catalyze the synthesis of 5-hydroxymethylfurfural from carbohydrates in diphenyl sulfoxide using the multifunctional nanocarbon catalyst, and extract and separate the product to obtain an aqueous solution of 5-hydroxymethylfurfural with a concentration of 3-9 g / L.

[0016] (2) Then, use the multifunctional nanocarbon catalyst to catalyze the preparation of 2,5-furandicarboxylic acid from the aqueous solution of 5-hydroxymethylfurfural in an air atmosphere.

[0017] Preferably, the carbohydrate in step (1) is a biomass carbohydrate, and the biomass carbohydrate includes monosaccharides and / or disaccharides.

[0018] Preferably, the mass ratio of the carbohydrate to the multifunctional nanocarbon catalyst in step (1) is 1:1 to 10:1; and / or, the mass ratio of the carbohydrate to diphenyl sulfoxide is 1:10 to 1:50; and / or, the reaction temperature for synthesizing 5-hydroxymethylfurfural is 120°C to 170°C; and / or, the reaction time for synthesizing 5-hydroxymethylfurfural is 1 to 8 h.

[0019] More preferably, the reaction temperature for synthesizing 5-hydroxymethylfurfural is 140°C to 160°C, and the reaction time is 180 - 300 min.

[0020] Preferably, the mass-to-volume ratio of the multifunctional nanocarbon catalyst to the aqueous solution of 5-hydroxymethylfurfural in step (2) is 1:1 to 10:1 g / L; and / or, the reaction temperature for preparing 2,5-furandicarboxylic acid is 60°C to 100°C; and / or, the reaction time for preparing 2,5-furandicarboxylic acid is 10 to 360 min; and / or, the air flow rate is 10 to 100 mL / min.

[0021] More preferably, the reaction temperature for preparing 2,5-furandicarboxylic acid is 80°C to 90°C, the reaction time is 120 to 240 min, and the air flow rate is 60 to 80 mL / min.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The multifunctional nanocarbon catalyst provided by the present invention has a simple composition. Palladium chloride can be in-situ reduced to palladium metal by lignin, reducing the use of reducing agents and hydrogen, which is green and environmentally friendly.

[0024] (2) The synthesis method of 2,5-furandicarboxylic acid provided by the present invention uses the multifunctional nanocarbon catalyst, which can simply and efficiently catalyze the synthesis of 2,5-furandicarboxylic acid from carbohydrates under mild conditions. The target product has a high yield and is easy to separate, having good industrial application prospects. Description of the Drawings:

[0025] Figure 1 They are the SEM morphology diagram of the multifunctional nanocarbon catalyst obtained in Example 1 and the TEM diagram of palladium metal particles;

[0026] Figure 2 It is the process flow diagram of the synthesis method of 2,5-furandicarboxylic acid of the present invention. Specific implementation manners:

[0027] The following examples are further illustrations of the present invention rather than limitations thereof.

[0028] In order to make the objectives, technical solutions and advantages of the present invention clearer, the embodiments and implementation manners of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary instance is actually only illustrative and in no way restricts the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0029] A multifunctional nanocarbon catalyst includes the following steps:

[0030] S1. Disperse lignin in ethanol (0.1 - 0.5 g / mL), stir magnetically for 1 - 3 h, filter to obtain residual solid R1 and an ethanol solution, and rotary evaporate the ethanol solution to remove ethanol to obtain solid R2;

[0031] S2. Dissolve R1 and / or R2 in tetrahydrofuran, then use a peristaltic pump to drop the mixture into water to prepare a suspension containing lignin nanoparticles NR1 and / or NR2. Add a PdCl2 hydrochloric acid solution to the suspension of NR1 and / or NR2 respectively, stir and react, and after centrifugal separation and drying, obtain Pd / NR1 and / or Pd / NR2;

[0032] S3. Add Pd / NR1 and / or Pd / NR2 to an aqueous solution of a sulfonating agent, and synthesize a nanocarbon catalyst through a hydrothermal reaction at 160°C - 200°C for 4 - 12 h. After washing, centrifugal separation and drying, obtain a multifunctional nanocarbon catalyst, and the multifunctional nanocarbon catalyst is Pd / CNR1, Pd / CNR2, and a combination of Pd / CNR1 and Pd / CNR2.

[0033] In the following examples, the mass-volume ratio (mass concentration) of R1 and / or R2 to tetrahydrofuran is 0.5 to 5.0 g / L, and can be, for example, any value among 0.5 g / L, 1 g / L, 1.5 g / L, 2 g / L, 3 g / L, 4 g / L, and 5 g / L. If the tetrahydrofuran solution is a mixture of R1 and R2, the mass ratio of R1 to R2 is 1:3 to 3:1, and can be, for example, any value among 1:3, 1:2, 1:1, 2:1, and 3:1.

[0034] In the following examples, the mass ratio of PdCl2 to lignin is 1:5 to 1:25, and can be, for example, any value among 1:5, 1:10, 1:15, 1:20, and 1:25. The concentration of PdCl2 in the PdCl2 hydrochloric acid solution is 0.5 to 2 g / L, and can be, for example, any value among 0.5 g / L, 1 g / L, 1.5 g / L, and 2 g / L.

[0035] In the following examples, the mass ratio of the sulfonating agent to lignin is 80:1 to 20:1, and can be, for example, any value among 80:1, 60:1, 40:1, and 20:1. The concentration of the sulfonating agent in the aqueous solution of the sulfonating agent is 0.6 to 1.8 g / mL, and can be, for example, any value among 0.6 g / mL, 1.2 g / mL, and 1.8 g / mL.

[0036] The following examples also provide the use of the multifunctional nanocarbon catalyst. The above multifunctional nanocarbon catalyst is used to catalyze the synthesis of 5-hydroxymethylfurfural from carbohydrates in diphenyl sulfoxide, and then the product is separated by water extraction to obtain an aqueous solution of 5-hydroxymethylfurfural. Then, the multifunctional nanocarbon catalyst is used to catalyze the preparation of 2,5-furandicarboxylic acid from the aqueous solution of 5-hydroxymethylfurfural in an air atmosphere.

[0037] In the following examples, the carbohydrates include monosaccharides or disaccharides, and can include, but are not limited to, fructose or sucrose, etc.

[0038] In the following examples, the mass ratio of fructose to the multifunctional nanocarbon catalyst is 1:1 to 10:1, and can be, for example, any value among 1:1, 2:1, 4:1, 6:1, 8:1, and 10:1.

[0039] In the following examples, the mass ratio of fructose to diphenyl sulfoxide is 1:10 to 1:50; for example, it can be any value among 1:10, 1:20, 1:30, 1:40, and 1:50.

[0040] In the following examples, the reaction temperature for the synthesis of 5-hydroxymethylfurfural is 120°C to 170°C, and the reaction time is 60 to 480 min; further, the reaction temperature can be preferably 140°C to 160°C, and the reaction time can be preferably 180 - 300 min.

[0041] In the following examples, the mass-volume ratio of the multifunctional nano-carbon catalyst to the 5-hydroxymethylfurfural aqueous solution is 1:1 to 10:1 g / L; for example, it can be any value among 1:1, 2:1, 4:1, 6:1, 8:1, and 10:1. The concentration of the 5-hydroxymethylfurfural aqueous solution is 3 to 9 g / L, for example, it can be any value among 3 g / L, 5 g / L, 7 g / L, and 9 g / L.

[0042] In the following examples, the reaction temperature for preparing 2,5-furandicarboxylic acid is 60°C to 100°C, the reaction time is 10 to 360 min, and the air flow rate is 10 to 100 mL / min. Further, the reaction temperature is preferably 80°C to 90°C, the reaction time is preferably 120 to 240 min, and the air flow rate is preferably 60 to 80 mL / min.

[0043] The following will further describe the present application in detail with specific examples, but the protection scope of the present application is not limited to these specific examples. Unless otherwise specified, the raw materials used in the following examples can be obtained from the market or prepared according to references, and the production equipment, testing equipment, testing methods, etc. used can also be common equipment or methods in the art.

[0044] Example 1

[0045] A multifunctional nano-carbon catalyst includes the following steps: Disperse lignin in ethanol (0.2 g / mL), stir magnetically for 2 h, filter to obtain residual solid R1 and an ethanol solution, and remove ethanol from the ethanol solution by rotary evaporation to obtain solid R2. Dissolve R1 and R2 in tetrahydrofuran, with the mass ratio of R1 to R2 being 1:1, to obtain a mixed solution with a concentration of 2 g / L of R1 and R2, and then use a peristaltic pump to drop the mixed solution into water to prepare a suspension containing lignin nanoparticles NR1 and NR2. Dissolve PdCl2 with a mass ratio of 1:15 to lignin in hydrochloric acid to obtain a PdCl2 hydrochloric acid solution with a concentration of 1 g / L of PdCl2, and add the PdCl2 hydrochloric acid solution to the suspension of NR1 and NR2, stir and react at 80°C for 6 h, centrifuge and dry to obtain Pd / NR1 and Pd / NR2. Then add Pd / NR1 and Pd / NR2 to an aqueous solution of p-toluenesulfonic acid with a concentration of 1.2 g / mL, with the mass ratio of p-toluenesulfonic acid to lignin being 60:1, and perform a hydrothermal reaction at 180°C for 6 h to synthesize a nano-carbon catalyst. After washing, centrifuging and drying, a multifunctional nano-carbon catalyst composed of Pd / CNR1 and Pd / CNR2 is obtained.

[0046] A method for synthesizing 2,5-furandicarboxylic acid. Add Pd / CNR1 multifunctional nanocarbon catalyst and fructose with a mass ratio of 2:1 into diphenyl sulfoxide and react at 150 °C for 360 min to synthesize 5-HMF. The mass ratio of fructose to diphenyl sulfoxide is 1:20, and the mass ratio of fructose to Pd / CNR1 multifunctional nanocarbon catalyst is 4:1. Then, use water extraction to separate the product to obtain a 5-HMF aqueous solution with a concentration of 5 g / L. Mix the multifunctional nanocarbon catalyst and 5-HMF aqueous solution agent with a mass-volume ratio of 4:1, and catalytically react the 5-HMF alkaline aqueous solution at 80 °C and an air flow rate of 80 mL / min for 180 min to obtain 2,5-furandicarboxylic acid. After the reaction, analyze the reaction product by high performance liquid chromatography. The yield of 5-HMF is 90.2%, and the yield of FDCA is 96.5%.

[0047] Comparative Example 1

[0048] A method for preparing 2,5-furandicarboxylic acid from sugar, comprising the following steps: Add 1 g of fructose, 0.1 g of FeCl3 catalyst, and 5 mL of tetramethylurea into a 25 mL autoclave, heat to 120 °C under magnetic stirring, with a stirring rate of 800 r / min, and stir and react at atmospheric pressure for 3 h. After the reaction is completed, cool to room temperature, heat and stir in an atmospheric oxygen atmosphere at 80 °C for 12 h, cool down, precipitate FDCA, filter by suction, and dry to obtain 0.8 g of FDCA, with a molar yield of 92%.

[0049] Comparative Example 2

[0050] A method for preparing 2,5-furandicarboxylic acid, comprising the following steps:

[0051] One-step method: Weigh 1 g of fructose, 30 g of water, 0.5 g of 30% hydrogen peroxide, and 1 g of copper catalyst into the inner liner of a 50 mL high-pressure reaction kettle, fill with a mixed gas of oxygen and nitrogen, close the high-pressure reaction kettle, and react at 180 °C for 30 min, with a pressure of 1 MPa. After the reaction, wait until it cools to room temperature, and detect and analyze the substances in the high-pressure reaction kettle. The yield of 2,5-furandicarboxylic acid is measured to be 18%.

[0052] Two-step method: Weigh 1 g of fructose, 30 g of water, and 0.8 g of 3% hydrogen peroxide into the inner liner of a 50 mL high-pressure reaction kettle, close the high-pressure reaction kettle, and react at 130 °C for 3 h. After the reaction, wait until it cools to room temperature, and take the liquid to test for the main intermediate product 5-hydroxymethylfurfural. Then, continue to add 0.3 g of sodium hydroxide, 2 g of copper-silica catalyst, and 2 g of 30% hydrogen peroxide to the reaction mixture, and stir and react at 25 °C for 2 h. After the reaction, take the liquid to detect and calculate the yield of 2,5-furandicarboxylic acid to be 28%.

[0053] Comparative Example 3

[0054] A preparation method of 2,5-furandicarboxylic acid, comprising the following steps: Add 0.2 g of fructose and 5 mL of an acidic buffer solution (pH = 5) with phosphate as the acidic buffer salt into a 35 mL pressure-resistant tube. Among them, the concentration of the acidic buffer solution is 1 mol / L. Place the pressure-resistant tube in an oil bath preheated to 120 °C and stir for reaction for 0.5 h. After the reaction is completed, quickly cool to room temperature and centrifuge to remove insoluble substances. Add 20 mg of a dicarboximide compound catalyst 1 and 50 mg of copper chloride into the solution, and react at 50 °C for 24 h under the condition of 0.1 MPa of oxygen. Cool down, dilute and make up the volume of the reaction solution with methanol for liquid phase detection. Determine the FDCA yield to be 78.3% by HPLC.

[0055] The catalytic system used in this Comparative Example 1 has a lower effect than the catalyst in Example 1. The FDCA synthesis process of this Comparative Example 2 is also much more complicated than that of Example 1, and the reaction temperature used is significantly higher than that of Example 1, with higher energy consumption and greater solvent consumption, which cannot meet the requirements of green environmental protection. At the same time, the catalyst used in Comparative Example 3 has a much lower effect than that in Example 1. The morphology of the multifunctional nanocarbon catalyst prepared by in-situ reduction in Example 1 is as Figure 1 shown. Pd metal particles can be evenly distributed on the surface of lignin nanocarbon, and the statistical particle size is 8.1 nm. The process of the multifunctional nanocarbon catalyst continuously catalyzing fructose to synthesize FDCA is as Figure 2 shown. This reaction system can achieve green and efficient catalysis of fructose to synthesize FDCA.

[0056] Example 2

[0057] A multifunctional nanocarbon catalyst, comprising the following steps: Disperse lignin in ethanol (0.2 g / mL), stir magnetically for 2 h, filter to obtain residual solid R1 and an ethanol solution, and remove ethanol by rotary evaporation of the ethanol solution to obtain solid R2. Dissolve R1 in tetrahydrofuran to obtain a tetrahydrofuran solution with a concentration of 2 g / L of R1, and then use a peristaltic pump to drop the mixed solution into water to prepare a suspension containing lignin nanoparticles NR1. Dissolve PdCl2 with a mass ratio of 1:15 to lignin in hydrochloric acid to obtain a PdCl2 hydrochloric acid solution with a concentration of 1 g / L of PdCl2, and add the PdCl2 hydrochloric acid solution to the suspension of NR1, stir and react at 80 °C for 6 h, centrifuge and dry to obtain Pd / NR1. Then add Pd / NR1 to an aqueous solution of p-toluenesulfonic acid with a concentration of 1.2 g / mL, the mass ratio of p-toluenesulfonic acid to lignin is 60:1, and hydrothermal react at 180 °C for 6 h to synthesize a nanocarbon catalyst. After washing, centrifuging and drying, a multifunctional nanocarbon catalyst (Pd / CNR1) is obtained.

[0058] The synthesis method of 2,5-furandicarboxylic acid is the same as that of Example 1. After the reaction, the reaction product was analyzed by high performance liquid chromatography. The yield of 5-HMF was 88.5%, and the yield of FDCA was 94.6%.

[0059] Example 3

[0060] A multifunctional nano-carbon catalyst, comprising the following steps: lignin was dispersed in ethanol (0.2 g / mL), magnetically stirred for 2 h, and after filtration, the residual solid R1 and ethanol solution were obtained. The ethanol solution was rotary evaporated to remove ethanol to obtain solid R2. R2 was dissolved in tetrahydrofuran to obtain a tetrahydrofuran solution with a concentration of 2 g / L of R2, and then the mixture was dropped into water using a peristaltic pump to prepare a suspension containing lignin nanoparticles NR2. PdCl2 with a mass ratio of 1:15 to lignin was dissolved in hydrochloric acid to prepare a PdCl2 hydrochloric acid solution with a concentration of 1 g / L of PdCl2, and the PdCl2 hydrochloric acid solution was added to the suspension of NR2, and stirred at 80 °C for 6 h. After centrifugation and drying, Pd / NR2 was obtained. Then Pd / NR2 was added to an aqueous solution of p-toluenesulfonic acid with a concentration of 1.2 g / mL, and the mass ratio of p-toluenesulfonic acid to lignin was 60:1. A nano-carbon catalyst was synthesized by hydrothermal reaction at 180 °C for 6 h. After washing, centrifugation and drying, a multifunctional nano-carbon catalyst (Pd / CNR2) was obtained.

[0061] The synthesis method of 2,5-furandicarboxylic acid is the same as that of Example 1. After the reaction, the reaction product was analyzed by high performance liquid chromatography. The yield of 5-HMF was 86.2%, and the yield of FDCA was 91.4%.

[0062] Example 4

[0063] The preparation steps and conditions of the multifunctional nano-carbon catalyst are the same as those of Example 1, and a multifunctional nano-carbon catalyst composed of Pd / CNR1 and Pd / CNR2 was obtained.

[0064] A synthesis method of 2,5-furandicarboxylic acid, a multifunctional nano-carbon catalyst and fructose with a mass ratio of 4:1 were added to diphenyl sulfoxide and reacted at 150 °C for 240 min to synthesize 5-HMF. The mass ratio of fructose to diphenyl sulfoxide was 1:10, and then the product was separated by water extraction to obtain a 5-HMF aqueous solution with a concentration of 5 g / L. A multifunctional nano-carbon catalyst and the 5-HMF aqueous solution with a mass-volume ratio of 4:1 were mixed, and the 5-HMF alkaline aqueous solution was catalytically reacted at 80 °C and an air flow rate of 80 mL / min for 180 min to obtain 2,5-furandicarboxylic acid. After the reaction, the reaction product was analyzed by high performance liquid chromatography. The yield of 5-HMF was 82.1%, and the yield of FDCA was 89.3%.

[0065] Example 5

[0066] The preparation steps and conditions of the multifunctional nanocarbon catalyst are the same as those in Example 1, and a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2 is obtained.

[0067] A method for synthesizing 2,5-furandicarboxylic acid. The multifunctional nanocarbon catalyst and fructose with a mass ratio of 1:4 are added to diphenyl sulfoxide and reacted at 150 °C for 240 min to synthesize 5-HMF. The mass ratio of fructose to diphenyl sulfoxide is 1:50. Then, the product is separated by water extraction to obtain a 5-HMF aqueous solution with a concentration of 5 g / L. The multifunctional nanocarbon catalyst and the 5-HMF aqueous solution with a mass-to-volume ratio of 4:1 are mixed, and the 5-HMF alkaline aqueous solution is catalytically reacted at 80 °C and an air flow rate of 80 mL / min for 180 min to obtain 2,5-furandicarboxylic acid. After the reaction, the reaction product is analyzed by high-performance liquid chromatography. The yield of 5-HMF is 84.5%, and the yield of FDCA is 92.6%.

[0068] Example 6

[0069] The preparation steps and conditions of the multifunctional nanocarbon catalyst are the same as those in Example 1, and a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2 is obtained.

[0070] A method for synthesizing 2,5-furandicarboxylic acid. The multifunctional nanocarbon catalyst and fructose with a mass ratio of 2:1 are added to diphenyl sulfoxide and reacted at 100 °C for 480 min to synthesize 5-HMF. The mass ratio of fructose to diphenyl sulfoxide is 1:20. Then, the product is separated by water extraction to obtain a 5-HMF aqueous solution with a concentration of 3 g / L. The multifunctional nanocarbon catalyst and the 5-HMF aqueous solution with a mass-to-volume ratio of 4:1 are mixed, and the 5-HMF alkaline aqueous solution is catalytically reacted at 80 °C and an air flow rate of 80 mL / min for 180 min to obtain 2,5-furandicarboxylic acid. After the reaction, the reaction product is analyzed by high-performance liquid chromatography. The yield of 5-HMF is 55.6%, and the yield of FDCA is 64.1%.

[0071] Example 7

[0072] The preparation steps and conditions of the multifunctional nanocarbon catalyst are the same as those in Example 1, and a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2 is obtained.

[0073] A method for synthesizing 2,5-furandicarboxylic acid. Multifunctional nanocarbon catalyst and fructose with a mass ratio of 2:1 are added to diphenyl sulfoxide and reacted at 170 °C for 60 min to synthesize 5-HMF. The mass ratio of fructose to diphenyl sulfoxide is 1:20. Then, the product is separated by water extraction to obtain a 5-HMF aqueous solution with a concentration of 9 g / L. The multifunctional nanocarbon catalyst and the 5-HMF aqueous solution with a mass-volume ratio of 4:1 are mixed, and the alkaline aqueous solution of 5-HMF is catalytically reacted at 80 °C and an air flow rate of 80 mL / min for 180 min to obtain 2,5-furandicarboxylic acid. After the reaction, the reaction product is analyzed by high performance liquid chromatography. The yield of 5-HMF is 78.2%, and the yield of FDCA is 82.3%.

[0074] Example 8

[0075] The preparation steps and conditions of the multifunctional nanocarbon catalyst are the same as those in Example 1, and a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2 is obtained.

[0076] A method for synthesizing 2,5-furandicarboxylic acid. Multifunctional nanocarbon catalyst and fructose with a mass ratio of 2:1 are added to diphenyl sulfoxide and reacted at 140 °C for 300 min to synthesize 5-HMF. The mass ratio of fructose to diphenyl sulfoxide is 1:20. Then, the product is separated by water extraction to obtain a 5-HMF aqueous solution with a concentration of 5 g / L. The multifunctional nanocarbon catalyst and the 5-HMF aqueous solution with a mass-volume ratio of 4:1 are mixed, and the alkaline aqueous solution of 5-HMF is catalytically reacted at 80 °C and an air flow rate of 80 mL / min for 180 min to obtain 2,5-furandicarboxylic acid. After the reaction, the reaction product is analyzed by high performance liquid chromatography. The yield of 5-HMF is 72.5%, and the yield of FDCA is 78.9%.

[0077] Example 9

[0078] The preparation steps and conditions of the multifunctional nanocarbon catalyst are the same as those in Example 1, and a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2 is obtained.

[0079] A method for synthesizing 2,5-furandicarboxylic acid. Multifunctional nanocarbon catalyst and fructose with a mass ratio of 2:1 are added to diphenyl sulfoxide and reacted at 160 °C for 180 min to synthesize 5-HMF. The mass ratio of fructose to diphenyl sulfoxide is 1:20. Then, the product is separated by water extraction to obtain a 5-HMF aqueous solution with a concentration of 5 g / L. Multifunctional nanocarbon catalyst and 5-HMF aqueous solution with a mass-to-volume ratio of 4:1 are mixed and catalytically react with the 5-HMF alkaline aqueous solution at 80 °C and an air flow rate of 80 mL / min for 180 min to obtain 2,5-furandicarboxylic acid. After the reaction, the reaction product is analyzed by high performance liquid chromatography. The yield of 5-HMF is 84.6%, and the yield of FDCA is 89.2%.

[0080] Example 10

[0081] The preparation steps and conditions of the multifunctional nanocarbon catalyst are the same as those in Example 1, and a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2 is obtained.

[0082] A method for synthesizing 2,5-furandicarboxylic acid. Multifunctional nanocarbon catalyst and fructose with a mass ratio of 2:1 are added to diphenyl sulfoxide and reacted at 150 °C for 240 min to synthesize 5-HMF. The mass ratio of fructose to diphenyl sulfoxide is 1:20. Then, the product is separated by water extraction to obtain a 5-HMF aqueous solution with a concentration of 5 g / L. Multifunctional nanocarbon catalyst and 5-HMF aqueous solution with a mass-to-volume ratio of 1:1 are mixed and catalytically react with the 5-HMF alkaline aqueous solution at 80 °C and an air flow rate of 80 mL / min for 180 min to obtain 2,5-furandicarboxylic acid. After the reaction, the reaction product is analyzed by high performance liquid chromatography. The yield of 5-HMF is 86.3%, and the yield of FDCA is 80.6%.

[0083] Example 11

[0084] The preparation steps and conditions of the multifunctional nanocarbon catalyst are the same as those in Example 1, and a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2 is obtained.

[0085] A method for synthesizing 2,5-furandicarboxylic acid. Multifunctional nanocarbon catalyst and fructose with a mass ratio of 2:1 are added to diphenyl sulfoxide and reacted at 150 °C for 300 min to synthesize 5-HMF. The mass ratio of fructose to diphenyl sulfoxide is 1:20. Then, water extraction is used to separate the product to obtain a 5-HMF aqueous solution with a concentration of 5 g / L. The multifunctional nanocarbon catalyst and the 5-HMF aqueous solution with a mass-volume ratio of 10:1 are mixed, and the 5-HMF alkaline aqueous solution is catalytically reacted at 80 °C and an air flow rate of 80 mL / min for 180 min to obtain 2,5-furandicarboxylic acid. After the reaction, the reaction product is analyzed by high-performance liquid chromatography. The yield of 5-HMF is 89.4%, and the yield of FDCA is 80.6%.

[0086] Example 12

[0087] The preparation steps and conditions of the multifunctional nanocarbon catalyst are the same as those in Example 1, and a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2 is obtained.

[0088] A method for synthesizing 2,5-furandicarboxylic acid. Multifunctional nanocarbon catalyst and fructose with a mass ratio of 2:1 are added to diphenyl sulfoxide and reacted at 160 °C for 240 min to synthesize 5-HMF. The mass ratio of fructose to diphenyl sulfoxide is 1:20. Then, water extraction is used to separate the product to obtain a 5-HMF aqueous solution with a concentration of 5 g / L. The multifunctional nanocarbon catalyst and the 5-HMF aqueous solution with a mass-volume ratio of 4:1 are mixed, and the 5-HMF alkaline aqueous solution is catalytically reacted at 60 °C and an air flow rate of 10 mL / min for 360 min to obtain 2,5-furandicarboxylic acid. After the reaction, the reaction product is analyzed by high-performance liquid chromatography. The yield of 5-HMF is 86.7%, and the yield of FDCA is 75.5%.

[0089] Example 13

[0090] The preparation steps and conditions of the multifunctional nanocarbon catalyst are the same as those in Example 1, and a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2 is obtained.

[0091] A method for synthesizing 2,5-furandicarboxylic acid. Multifunctional nanocarbon catalyst and fructose with a mass ratio of 2:1 are added to diphenyl sulfoxide and reacted at 160 °C for 360 min to synthesize 5-HMF. The mass ratio of fructose to diphenyl sulfoxide is 1:20. Then, water extraction is used to separate the product to obtain a 5-HMF aqueous solution with a concentration of 5 g / L. The multifunctional nanocarbon catalyst and the 5-HMF aqueous solution with a mass-volume ratio of 4:1 are mixed, and the alkaline aqueous solution of 5-HMF is catalytically reacted at 100 °C and an air flow rate of 100 mL / min for 10 min to obtain 2,5-furandicarboxylic acid. After the reaction, the reaction product is analyzed by high performance liquid chromatography. The yield of 5-HMF is 84.2%, and the yield of FDCA is 85.9%.

[0092] Example 14

[0093] The preparation steps and conditions of the multifunctional nanocarbon catalyst are the same as those in Example 1, and a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2 is obtained.

[0094] A method for synthesizing 2,5-furandicarboxylic acid. Multifunctional nanocarbon catalyst and fructose with a mass ratio of 2:1 are added to diphenyl sulfoxide and reacted at 150 °C for 480 min to synthesize 5-HMF. The mass ratio of fructose to diphenyl sulfoxide is 1:20. Then, water extraction is used to separate the product to obtain a 5-HMF aqueous solution with a concentration of 5 g / L. The multifunctional nanocarbon catalyst and the 5-HMF aqueous solution with a mass-volume ratio of 4:1 are mixed, and the alkaline aqueous solution of 5-HMF is catalytically reacted at 80 °C and an air flow rate of 60 mL / min for 240 min to obtain 2,5-furandicarboxylic acid. After the reaction, the reaction product is analyzed by high performance liquid chromatography. The yield of 5-HMF is 87.8%, and the yield of FDCA is 90.4%.

[0095] Example 15

[0096] The preparation steps and conditions of the multifunctional nanocarbon catalyst are the same as those in Example 1, and a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2 is obtained.

[0097] A method for synthesizing 2,5-furandicarboxylic acid. Multifunctional nanocarbon catalyst and fructose with a mass ratio of 2:1 are added to diphenyl sulfoxide and reacted at 150 °C for 360 min to synthesize 5-HMF. The mass ratio of fructose to diphenyl sulfoxide is 1:20. Then, the product is separated by water extraction to obtain a 5-HMF aqueous solution with a concentration of 5 g / L. The multifunctional nanocarbon catalyst and the 5-HMF aqueous solution are mixed with a mass-volume ratio of 4:1, and the alkaline aqueous solution of 5-HMF is catalytically reacted at 90 °C and an air flow rate of 80 mL / min for 120 min to obtain 2,5-furandicarboxylic acid. After the reaction, the reaction product is analyzed by high performance liquid chromatography. The yield of 5-HMF is 90.2%, and the yield of FDCA is 85.1%.

[0098] Example 16

[0099] The preparation steps of the multifunctional nanocarbon catalyst are the same as those in Example 1, except that: the mass ratio of R1 to R2 is 1:3, the concentration of PdCl2 in the PdCl2 hydrochloric acid solution is 0.5 g / L, and the concentration of the sulfonating agent in the aqueous solution of the sulfonating agent is 0.6 g / mL, to obtain a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2.

[0100] The synthesis method of 2,5-furandicarboxylic acid is the same as that in Example 1. After the reaction, the reaction product is analyzed by high performance liquid chromatography. The yield of 5-HMF is 82.4%, and the yield of FDCA is 87.9%.

[0101] Example 17

[0102] The preparation steps of the multifunctional nanocarbon catalyst are the same as those in Example 1, except that: the mass ratio of R1 to R2 is 1:2, to obtain a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2.

[0103] The synthesis method of 2,5-furandicarboxylic acid is the same as that in Example 1. After the reaction, the reaction product is analyzed by high performance liquid chromatography. The yield of 5-HMF is 85.7%, and the yield of FDCA is 90.2%.

[0104] Example 18

[0105] The preparation steps of the multifunctional nanocarbon catalyst are the same as those in Example 1, except that: the mass ratio of R1 to R2 is 3:1, the concentration of PdCl2 in the PdCl2 hydrochloric acid solution is 2 g / L, and the concentration of the sulfonating agent in the aqueous solution of the sulfonating agent is 1.8 g / mL, to obtain a multifunctional nanocarbon catalyst composed of Pd / CNR1 and Pd / CNR2.

[0106] The synthesis method of 2,5-furandicarboxylic acid is the same as that of Example 1. After the reaction is completed, the reaction product is analyzed by high performance liquid chromatography, and the yield of 5-HMF is 86.8% and the yield of FDCA is 91.7%.

[0107] The description of the above embodiments is only used to help understand the technical solution and its core idea of the present invention. It should be noted that for those skilled in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A multifunctional nanocarbon catalyst, characterized in that, It is prepared by the following steps: S1. Disperse lignin in ethanol, stir and react, filter to obtain residual solid R1 and an ethanol solution, and evaporate the ethanol from the ethanol solution to obtain solid R2; S2. Dissolve R1 and / or R2 in tetrahydrofuran to obtain a tetrahydrofuran solution containing R1 and / or R2, then drop the tetrahydrofuran solution containing R1 and / or R2 into water to prepare a suspension containing lignin nanoparticles NR1 and / or NR2. Add a PdCl2 hydrochloric acid solution to the suspension for in-situ reduction, stir and react at 70 °C - 90 °C for 5 - 7 h, and obtain Pd / NR1 and / or Pd / NR2 after centrifugal separation and drying; S3. Add Pd / NR1 and / or Pd / NR2 to a solution with a sulfonating agent concentration of 0.6 - 1.8 g / mL, carry out a hydrothermal reaction at 160 °C - 200 °C for 4 - 12 h, wash the product, carry out centrifugal separation and drying, and obtain a multifunctional nanocarbon catalyst, where the multifunctional nanocarbon catalyst includes Pd / CNR1 and / or Pd / CNR2.

2. The multifunctional nanocarbon catalyst according to claim 1, characterized in that, The solid-liquid ratio of the lignin to ethanol in step S1 is 0.1 - 0.5 g / mL.

3. The multifunctional nanocarbon catalyst according to claim 1 or 2, characterized in that, The mass concentration of R1 and / or R2 in the tetrahydrofuran solution in step S2 is 0.5 - 5.0 g / L.

4. The multifunctional nanocarbon catalyst according to claim 3, characterized in that, Dissolve R1 and R2 with a mass ratio of 1:3 - 3:1 in tetrahydrofuran to obtain a tetrahydrofuran solution containing R1 and R2.

5. The multifunctional nanocarbon catalyst according to claim 1 or 2, characterized in that, The mass ratio of PdCl2 to lignin in step S2 is 1:5 - 1:25, and the concentration of PdCl2 in the PdCl2 hydrochloric acid solution is 0.5 - 2 g / L.

6. The multifunctional nanocarbon catalyst according to claim 1 or 2, characterized in that, The sulfonating agent in step S3 is selected from one of p-toluenesulfonic acid, p-hydroxybenzenesulfonic acid, and concentrated sulfuric acid; the mass ratio of the sulfonating agent to lignin is 80:1 - 20:

1.

7. A method for catalyzing the synthesis of 2,5-furandicarboxylic acid from carbohydrates, characterized in that, It includes the following steps: (1) Catalyze the synthesis of 5-hydroxymethylfurfural from carbohydrates by the multifunctional nanocarbon catalyst as claimed in claim 1 or 2 in diphenyl sulfoxide, extract and separate the product to obtain a 5-hydroxymethylfurfural aqueous solution with a concentration of 3 - 9 g / L; (2) Then use the multifunctional nanocarbon catalyst as claimed in claim 1 or 2 to catalyze the 5-hydroxymethylfurfural aqueous solution to prepare 2,5-furandicarboxylic acid under an air atmosphere.

8. The method according to claim 7, characterized in that, The carbohydrate in step (1) is a biomass carbohydrate, and the biomass carbohydrate includes monosaccharides and / or disaccharides.

9. The method according to claim 7 or 8, characterized in that, The mass ratio of the carbohydrate to the multifunctional nanocarbon catalyst in step (1) is 1:1 - 10:1; and / or, the mass ratio of the carbohydrate to diphenyl sulfoxide is 1:10 - 1:50; and / or, the reaction temperature for synthesizing 5-hydroxymethylfurfural is 120 °C - 170 °C; and / or, the reaction time for synthesizing 5-hydroxymethylfurfural is 1 - 8 h.

10. The method according to claim 7 or 8, characterized in that, The mass-volume ratio of the multifunctional nanocarbon catalyst to the 5-hydroxymethylfurfural aqueous solution in step (2) is 1:1 - 10:1 g / L; and / or, the reaction temperature for preparing 2,5-furandicarboxylic acid is 60 °C - 100 °C; and / or, the reaction time for preparing 2,5-furandicarboxylic acid is 10 - 360 min; and / or, the air flow rate is 10 - 100 mL / min.

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