A method for synthesizing furandicarboxylic acid

Abstract

The invention discloses a method for synthesizing furandicarboxylic acid, and relates to the technical field of furandicarboxylic acid synthesis. The method comprises the following steps: uniformly mixing HMF, an alkali and water to obtain an HMF mixed reaction liquid; pumping the HMF mixed reaction liquid into a fixed-bed reactor filled with an x%Ru-y%Co@CeO2 catalyst to carry out a catalytic oxidation reaction, collecting an aqueous solution containing furandicarboxylate, and filtering and collecting the solution after acidification to obtain FDCA; during the preparation process of the x%Ru-y%Co@CeO2 catalyst, a microemulsion confinement method combined with an ultrasonic dispersion technology is adopted to accurately control the particle size of the Ru-Co alloy core, and the CeO2 carrier in the catalyst can produce a synergistic effect with Ru and Co, optimize the electronic structure, and increase the active sites, which is beneficial to improving the selectivity of the oxidation reaction. The preparation method is simple, avoids the use of a noble metal catalyst, and has low preparation cost. The fixed-bed reactor can realize continuous reaction preparation, reduce backmixing of the reaction liquid, and greatly shorten the reaction time, thereby improving the reaction efficiency and effectively reducing the reaction cost.

Description

Technical Field

[0001] The present invention relates to the technical field of furandicarboxylic acid synthesis, and in particular to a method for synthesizing furandicarboxylic acid. Background Art

[0002] Furandicarboxylic acid (FDCA), a highly promising bio-based platform compound, has attracted significant attention in both research and industry. While sharing structural characteristics with terephthalic acid, it offers significant performance advantages, such as smaller bond angles, greater rigidity, and increased polarity, which contribute to its excellent biodegradability and low carbon emissions. Across numerous applications, FDCA can significantly enhance the thermal stability and mechanical properties of bio-based polymers when used in the synthesis of these materials. The resulting polymers are widely used in industries such as films, food packaging, and textiles.

[0003] Currently, FDCA synthesis routes are primarily categorized by raw material: the 5-hydroxymethylfurfural (HMF) route, the furoic acid route, the hexacarboxylic acid route, the diethylene glycol route, and the furan route. The HMF route, due to its early research and rich research results, is currently the most widely used and has the greatest potential for industrialization. However, this route still faces numerous challenges in the catalytic oxidation stage.

[0004] Existing catalytic methods include direct oxidation, transition metal-catalyzed oxidation, noble metal-catalyzed oxidation, electrochemical oxidation, and bio-enzymatic oxidation. In the area of ​​noble metal catalysis, for example, patent publication No. CN 109046349B utilizes single-atom Pd as a catalyst for HMF oxidation at 110°C for 5 hours, achieving a high FDCA yield of 94.2%. However, Pd is expensive and suffers from a reduced lifespan, significantly increasing production costs and limiting large-scale industrial application. In the field of non-noble metal catalysis, patent publication No. CN 116730956A utilizes nano-copper oxide as a catalyst, achieving a maximum FDCA yield of 84.5%. The platinum-cobalt-niobium heterogeneous catalyst disclosed in patent publication No. CN115569652B achieves product selectivity exceeding 99% and exhibits good catalytic activity, selectivity, and reusability. However, overall, non-noble metal catalyst systems still require further optimization to improve catalytic efficiency and stability.

[0005] As research continues to deepen, researchers have found that developing an efficient, stable and low-cost catalytic system is the key to promoting the industrial production of FDCA. Summary of the Invention

[0006] The object of the present invention is to provide a method for synthesizing furandicarboxylic acid to solve the following technical problems:

[0007] How to provide an efficient, stable and low-cost catalyst for the industrial production of FDCA.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A method for synthesizing furandicarboxylic acid comprises the following steps:

[0010] Step 1: HMF (5-hydroxymethylfurfural), alkali and water are uniformly mixed to obtain an HMF mixed reaction solution;

[0011] Step 2: Pump the HMF mixed reaction liquid into a fixed bed reactor filled with x%Ru-y%Co@CeO2 catalyst to carry out catalytic oxidation reaction, and obtain a reaction product liquid after the reaction is completed;

[0012] Step 3: Condensing the reaction solution, collecting the aqueous solution containing furandicarboxylate, acidifying and filtering to obtain FDCA;

[0013] In the x%Ru-y%Co@CeO2 catalyst of step 2, the x% is the molar ratio of Ru element to Ce element, and x=5-10; the y% is the molar ratio of Co element to Ce element, and y=5-10.

[0014] Furthermore, the x%Ru-y%Co@CeO2 catalyst is prepared by the following steps:

[0015] S1. Dissolve RuCl3·3H2O and Co(NO3)2·6H2O in a solvent system according to the molar ratio of Ru:Co=x:y, add NaBH4 solution dropwise until the pH of the solution system reaches 11, perform ultrasonic treatment and filter to obtain solid particles, wash and dry, grind and pulverize, and finally calcine to obtain an alloy core;

[0016] S2. The alloy cores were dispersed in an ethanol aqueous solution containing 0.1 mol / L Ce(NO3)3 and 0.1 mol / L glucose at a molar ratio of Ru:Ce=x%, and Co:Ce=y%. The pH was adjusted by alternating the addition of NH3·H2O to a pH of 9 and the addition of CO2 gas to a pH of 6. After alternating for 5 times, a reaction solution was obtained. The reaction solution was reacted at 80°C for 12 hours, and solid particles were obtained after filtration. The solid particles were washed, dried, and then calcined to obtain an x%Ru-y%Co@CeO2 catalyst.

[0017] Preferably, the particle size of the x%Ru-y%Co@CeO2 catalyst is 30-100 mesh;

[0018] More preferably, the particle size of the x%Ru-y%Co@CeO2 catalyst is 50-100 mesh.

[0019] Furthermore, in step S1, the ratio of the sum of the molar amounts of RuCl3·3H2O and Co(NO3)2·6H2O to the volume of the solvent system is 1 mmol:(25-50) mL.

[0020] Furthermore, in step S1, the solvent system is a mixed solution of cyclohexane, polyethylene glycol octylphenyl ether and n-hexanol in a volume ratio of 4:3:1.

[0021] Furthermore, in step S1, the calcination condition is: calcination at 300-500° C. for 2 h under nitrogen atmosphere.

[0022] Furthermore, in step S2, the ethanol aqueous solution is a mixed solution consisting of ethanol and water in a volume ratio of 3:1.

[0023] Furthermore, in step S2, the calcination condition is: calcination at 500° C. for 3 hours in an air atmosphere.

[0024] Furthermore, in step 1, the molar ratio of HMF to alkali is (2-4):1.

[0025] Furthermore, in step 1, the base is a composition composed of any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate in any proportion.

[0026] Furthermore, in step 1, the mass fraction of HMF in the HMF mixed reaction solution is 1-20%.

[0027] Furthermore, in step 2, the reaction temperature of the catalytic oxidation reaction is 130-180° C., and the reaction pressure is 0.1-3 MPa.

[0028] Furthermore, in step 2, the reaction gas for the catalytic oxidation reaction is air or oxygen.

[0029] Furthermore, in step 2, the HMF mixed reaction liquid is pumped into the fixed bed reactor at a flow rate of 2-20 mL / min, preferably 2-10 mL / min.

[0030] Furthermore, in step 2, the filling amount of the x%Ru-y%Co@CeO2 catalyst in the bed of the fixed bed reactor is 100%.

[0031] Furthermore, in step three, the acidification step is: adding an acidic reagent to the aqueous solution containing furandicarboxylate, acidifying to a pH <1 and then precipitating a solid;

[0032] Preferably, the acidic reagent is at least one of hydrochloric acid and sulfuric acid; more preferably, hydrochloric acid.

[0033] Furthermore, the fixed bed reactor includes a feeding system, a reaction system and a product processing system.

[0034] The feeding system includes a balance B01, a feeding tank V01, a metering pump P01, a preheater E01, and a preheating furnace F01; the feeding tank V01 is connected to the metering pump P01 and the preheater E01 in sequence. The feeding tank V01 is used to store the liquid reaction raw material HMF mixed reaction liquid. The flow rate of the HMF mixed reaction liquid is controlled by the metering pump P01 to achieve continuous feeding. The liquid flows through the preheater E01, and the preheating furnace F01 preheats and mixes the HMF mixed reaction liquid.

[0035] The reaction system includes a tubular reactor R01 and a reactor furnace F02; the tubular reactor R01 is used to be filled with catalyst and serves as a place for catalytic oxidation reaction, and the reactor furnace F02 provides a constant temperature heat exchange medium for the heat exchange jacket of the tubular reactor R01.

[0036] The product processing system includes a cooler E02, a gas-liquid separator V03, a first liquid storage tank V04A, and a second liquid storage tank V04B. After the HMF mixed reaction liquid reacts in the reaction system, it flows through the cooler E02 for cooling and condensation. The gas-liquid separator V03 separates the gas and liquid products according to the different boiling points of the materials. The first liquid storage tank V04A and the second liquid storage tank V04B are used to collect liquid reaction products.

[0037] The fixed bed reactor further includes various pipe and valve components, such as joints and pipelines, valves, one-way valves CV, back pressure valves, pressure reducing valves, solenoid valves, gas cylinders, etc.

[0038] Furthermore, the process flow of using the fixed bed reactor to synthesize furandicarboxylic acid is as follows: a prepared HMF mixed reaction liquid is added to a feed tank V01, preheated by a metering pump P01 at a certain flow rate through a preheater E01, and then transported to a tubular reactor R01, where a catalytic reaction is carried out at a certain temperature and a certain pressure. After the reaction is completed, the product obtained is cooled by a cooler E02, separated by a gas-liquid separator V03, and collected in a first liquid storage tank V04A or a second liquid storage tank V04B to obtain a reaction liquid, which is then discharged through a discharge valve to obtain an FDCA reaction liquid.

[0039] Beneficial effects of the present invention:

[0040] 1. The present invention provides a method for synthesizing furandicarboxylic acid. During the synthesis process, an x%Ru-y%Co@CeO2 catalyst is used for catalysis. During the preparation process of the x%Ru-y%Co@CeO2 catalyst, a microemulsion confinement method combined with ultrasonic dispersion technology is adopted to accurately control the particle size of the Ru-Co alloy core. The CeO2 carrier in the catalyst can produce a synergistic effect with Ru and Co, optimize the electronic structure, and increase the active sites, which is beneficial to improving the selectivity of the oxidation reaction.

[0041] 2. The preparation method of the x%Ru-y%Co@CeO2 catalyst in the present invention is simple, avoids the use of precious metal catalysts, and has low preparation cost. In addition, the use of a fixed-bed reactor can achieve continuous preparation of the reaction, reduce backmixing of the reaction solution, and greatly shorten the reaction time, thereby improving reaction efficiency and effectively reducing reaction costs, providing a new approach for the industrial production of FDCA. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The present invention will be further described below with reference to the accompanying drawings.

[0043] Figure 1 Schematic diagram of the working process of the fixed bed reactor in the method for synthesizing furandicarboxylic acid of the present invention;

[0044] Figure 2 Schematic diagram of the structure of a fixed bed reactor in the method for synthesizing furandicarboxylic acid of the present invention;

[0045] Figure 3 This is the BET spectrum of the 5%Ru-5%Co@CeO2 catalyst prepared in Preparation Example 1 of the present invention;

[0046] Figure 4 is the XRD spectrum of the 5%Ru-5%Co@CeO2 catalyst prepared in Preparation Example 1 of the present invention;

[0047] Figure 5 This is the XPS graph of the 5%Ru-5%Co@CeO2 catalyst prepared in Preparation Example 1 of the present invention;

[0048] Figure 6 This is the XPS graph of Ru3p in the 5%Ru-5%Co@CeO2 catalyst prepared in Example 1 of the present invention;

[0049] Figure 7 This is the XPS graph of Ce3d in the 5%Ru-5%Co@CeO2 catalyst prepared in Example 1 of the present invention;

[0050] Figure 8 This is the XPS graph of Co2p in the 5%Ru-5%Co@CeO2 catalyst of Preparation Example 1 of the present invention;

[0051] Figure 9This is a SEM image of the 5%Ru-5%Co@CeO2 catalyst prepared in Preparation Example 1 of the present invention at 2 μm;

[0052] Figure 10 is a SEM image of the 5%Ru-5%Co@CeO2 catalyst prepared in Preparation Example 1 of the present invention at 100nm;

[0053] Figure 11 is a liquid phase diagram of FDCA prepared in Example 1 of the present invention;

[0054] Figure 12 is the hydrogen spectrum of FDCA prepared in Example 1 of the present invention;

[0055] Figure 13 It is the carbon spectrum of FDCA prepared in Example 1 of the present invention.

[0056] Figure 2 1 , B01 , balance; V01 , feed tank; P01 , metering pump; E01 , preheater; F01 , preheating furnace; R01 , tubular reactor; F02 , reactor furnace; E02 , cooler; V03 , gas-liquid separator; V04A , first liquid storage tank; V04B , second liquid storage tank. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the preparation examples and embodiments of the present invention to clearly and completely describe the technical solutions in the preparation examples and embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0058] Unless otherwise specified, the experimental methods in the following preparations and examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples are all commercially available unless otherwise specified.

[0059] The present invention discloses a method for synthesizing furandicarboxylic acid, comprising the following steps:

[0060] Step 1: HMF, a base, and water are uniformly mixed to obtain an HMF mixed reaction liquid; wherein the molar ratio of HMF to the base is (2-4):1; the base is a combination of any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate in any proportion; and the mass fraction of HMF in the HMF mixed reaction liquid is 1-20%.

[0061] Step 2: The HMF mixed reaction liquid is pumped into a fixed bed reactor filled with a 30-100 mesh x% Ru-y% Co@CeO2 catalyst at a flow rate of 2-20 mL / min for a catalytic oxidation reaction. The reaction temperature is 130-180°C, the reaction pressure is 0.1-3 MPa, and the reaction gas is air or oxygen. The filling amount of the x% Ru-y% Co@CeO2 catalyst in the bed layer of the fixed bed reactor is 100%. After the reaction is completed, a reaction product liquid is obtained.

[0062] Step 3: Condensing the reaction solution, collecting an aqueous solution containing furandicarboxylate, adding an acidic reagent to the aqueous solution containing furandicarboxylate, wherein the acidic reagent is at least one of hydrochloric acid and sulfuric acid; acidifying to a pH <1 to precipitate a solid, collecting by filtration, and obtaining FDCA;

[0063] In the x%Ru-y%Co@CeO2 catalyst of step 2, the x% is the molar ratio of Ru element to Ce element, and x=5-10; the y% is the molar ratio of Co element to Ce element, and y=5-10.

[0064] The x%Ru-y%Co@CeO2 catalyst was prepared by the following steps:

[0065] S1. RuCl3·3H2O and Co(NO3)2·6H2O were dissolved in a solvent system according to the molar ratio of Ru:Co=x:y, and NaBH4 solution was added dropwise until the pH of the solution system reached 11. After ultrasonic treatment, the mixture was filtered to obtain solid particles, which were washed, dried, ground and pulverized. Finally, the solid particles were calcined at 300-500°C for 2h under a nitrogen atmosphere to obtain an alloy core.

[0066] The ratio of the sum of the molar amounts of RuCl3·3H2O and Co(NO3)2·6H2O to the volume of the solvent system is 1 mmol:(25-50) mL; the solvent system is a mixed solution of cyclohexane, polyethylene glycol octylphenyl ether, and n-hexanol in a volume ratio of 4:3:1;

[0067] S2. The alloy cores were dispersed in an ethanol aqueous solution containing 0.1 mol / L Ce(NO3)3 and 0.1 mol / L glucose according to the molar ratio of Ru:Ce=x and Co:Ce=y. NH3·H2O was alternately added to pH=9, and CO2 gas was passed through to pH=6. After alternating five times, a reaction solution was obtained. The reaction solution was reacted at 80°C for 12 hours, and solid particles were obtained after filtration. After washing and drying, solid particles were calcined at 500°C for 3 hours in an air atmosphere to obtain an x%Ru-y%Co@CeO2 catalyst.

[0068] See also Figure 1 The fixed bed reactor in step 2 includes a feeding system, a reaction system and a product processing system.

[0069] See also Figure 2 In the fixed-bed reactor, the feeding system includes a balance B01, a feeding tank V01, a metering pump P01, a preheater E01, and a preheating furnace F01; the feeding tank V01 is connected to the metering pump P01 and the preheater E01 in sequence. The feeding tank V01 is used to store the liquid reaction raw material HMF mixed reaction liquid. The flow rate of the HMF mixed reaction liquid is controlled by the metering pump P01 to achieve continuous feeding. The liquid flows through the preheater E01, and the preheating furnace F01 preheats and mixes the HMF mixed reaction liquid.

[0070] The reaction system includes a tubular reactor R01 and a reactor furnace F02; the tubular reactor R01 is used to load catalysts and serves as a place for catalytic oxidation reactions, and the reactor furnace F02 provides a constant temperature heat exchange medium for the heat exchange jacket of the tubular reactor R01.

[0071] The product processing system includes a cooler E02, a gas-liquid separator V03, a first liquid storage tank V04A, and a second liquid storage tank V04B. After the HMF mixed reaction liquid reacts in the reaction system, it flows through the cooler E02 for cooling and condensation. The gas-liquid separator V03 separates the gas and liquid products according to the different boiling points of the materials. The first liquid storage tank V04A and the second liquid storage tank V04B are used to collect liquid reaction products.

[0072] The fixed bed reactor also includes various pipe and valve parts, such as joints and pipes, valves, one-way valves CV, back pressure valves, pressure reducing valves, solenoid valves, gas cylinders, etc.

[0073] The process flow for synthesizing furandicarboxylic acid using a fixed-bed reactor is as follows: a prepared HMF mixed reaction liquid is added to a feed tank V01, preheated by a metering pump P01 at a certain flow rate through a preheater E01, and then transported to a tubular reactor R01. A catalytic reaction is carried out at a certain temperature and pressure. After the reaction is completed, the product is cooled by a cooler E02, separated by a gas-liquid separator V03, and collected in a first liquid storage tank V04A or a second liquid storage tank V04B to obtain a reaction liquid, which is then discharged through a discharge valve to obtain an FDCA reaction liquid.

[0074] Preparation Example 1

[0075] The 5%Ru-5%Co@CeO2 catalyst was prepared by following the steps below:

[0076] S1. Dissolve 0.2 mmol of RuCl3·3H2O and 0.2 mmol of Co(NO3)2·6H2O in 5 ml of a cyclohexane / polyethylene glycol octylphenyl ether / n-hexanol solvent system with a volume ratio of 4:3:1, add NaBH4 solution dropwise until the system pH is 11, and ultrasonicate for 20 min. Then filter to obtain solid particles, wash with ethanol, dry at 70°C for 12 h, grind, and calcine at 400°C under nitrogen for 2 h to obtain alloy cores.

[0077] S2, the alloy cores were dispersed in 40 mL of ethanol / water mixture containing 0.1 mol / L Ce(NO3)3 and 0.1 mol / L glucose (V 乙醇 :V 水 =3:1), and the pH was adjusted alternately by adding NH3·H2O to pH=9 and passing CO2 gas to pH=6. After 5 cycles, the reaction solution was aged at 80°C for 12 h, filtered to obtain solid particles, washed with ethanol, dried at 70°C for 12 h, and calcined in air at 500°C for 3 h to obtain a 5%Ru-5%Co@CeO2 catalyst.

[0078] Preparation Example 2

[0079] A 5%Ru-10%Co@CeO2 catalyst was prepared. The preparation steps were the same as those in Preparation Example 1, except that in step S1, the amount of Co(NO3)2·6H2O added was changed to 0.4 mmol. The other steps and conditions remained the same, and a 5%Ru-10%Co@CeO2 catalyst was finally prepared.

[0080] Preparation Example 3

[0081] A 10%Ru-5%Co@CeO2 catalyst was prepared. The preparation steps were the same as those in Preparation Example 1, except that in step S1, the amount of RuCl3·3H2O added was changed to 0.4 mmol. The other steps and conditions remained the same, and a 10%Ru-5%Co@CeO2 catalyst was finally prepared.

[0082] Preparation Example 4

[0083] A 5%Ru-5%Co@CeO2 catalyst was prepared. The preparation steps were the same as those in Preparation Example 1, except that in step S1, the calcination temperature was changed to 500°C, and the other steps and conditions remained the same, ultimately producing a 5%Ru-5%Co@CeO2 catalyst.

[0084] Preparation Example 5

[0085] A 5%Ru-5%Co@CeO2 catalyst was prepared. The preparation steps were the same as those in Preparation Example 1, except that in step S1, the calcination temperature was changed to 300°C, and the other steps and conditions remained the same, ultimately producing a 5%Ru-5%Co@CeO2 catalyst.

[0086] Next, the performance tests of the x%Ru-y%Co@CeO2 catalyst samples prepared in Preparation Examples 1-5 were carried out and the test results were analyzed. It can be seen that the test results of each group of preparation examples are comparable; taking Preparation Example 1 as an example, the following results are obtained: Figure 3-10 The representation diagram, according to Figure 1-4 Conduct specific analysis.

[0087] Figure 3 The BET spectrum of the 5%Ru-5%Co@CeO2 catalyst sample in Preparation Example 1 is as follows: Figure 3 The characterization results show that the specific surface area of ​​the 5%Ru-5%Co@CeO2 catalyst sample in Preparation Example 1 is 72.67 m² / g, and the adsorption cumulative pore volume is 0.143 cm 3 / g. The average pore diameters of the sample for BJH adsorption and desorption were 8.69 nm and 8.48 nm, respectively, which were within the range of mesopores. Meanwhile, the t-Plot micropore area was only 0.31 m 2 / g, accounting for a very small proportion, while the external surface area is large, which also indicates that the sample is mainly composed of a mesoporous structure; the large BET specific surface area and mesoporous structure make the 5%Ru-5%Co@CeO2 catalyst sample have a rich internal surface, which can provide more active sites for the oxidation reaction; the mesoporous structure can effectively disperse the active components and prevent them from agglomerating during the reaction, thereby improving the stability of the catalyst.

[0088] Figure 4 The XRD spectrum of the 5%Ru-5%Co@CeO2 catalyst sample in Preparation Example 1 is as follows: Figure 4 The characterization results show that the 5%Ru-5%Co@CeO2 catalyst sample in Preparation Example 1 has a clear crystalline structure and the presence of CeO2 crystal phase, but no obvious diffraction peaks of Ru and Co metals were observed in XRD, indicating that Ru and Co are highly dispersed. Figure 1 It can also be seen from the BET results in Figure 2 that these structural features have many positive effects on the oxidation reaction, not only improving the structural stability but also promoting the diffusion of reactants / products.

[0089] Figure 5-8 This is the XPS spectrum of the 5%Ru-5%Co@CeO2 catalyst sample in Preparation Example 1. Figure 5-8The characterization results show that: in the XPS spectrum of the 5%Ru-5%Co@CeO2 catalyst sample in Preparation Example 1, multiple obvious peaks can be seen, which indicates that there are multiple elements in the catalyst; Figure 5 Ce is marked 3d5 , O 1s 、Co 2p3 、Ru 3p The peaks are as follows, which indicates that Ce, O, Co, and Ru elements exist in the catalyst; the peak intensities of Ru and Co are relatively weak, which shows that their relative contents on the surface are small, indicating that they are wrapped by the CeO2 layer, which is beneficial to the substrate adsorption and the reaction of the active sites.

[0090] Figure 9-10 This is the SEM spectrum of the 5%Ru-5%Co@CeO2 catalyst sample in Preparation Example 1. Figure 9-10 From the characterization results, it can be seen that the 5%Ru-5%Co@CeO2 catalyst sample in Preparation Example 1 presents a relatively loose particle stacking structure with particles of varying sizes; it can be seen that the catalyst has a relatively complex microstructure with obvious protrusions and pore structures on the surface, which helps to increase the specific surface area of ​​the material and thus enhance its catalytic activity.

[0091] Example 1

[0092] This embodiment provides a method for synthesizing furandicarboxylic acid, which is carried out in the following steps:

[0093] Step 1: Add 63 g HMF (0.5 mol) and 60 g sodium hydroxide (1.5 mol) to 1137 g water (molar ratio HMF: alkali = 1:3), mix well to obtain an HMF mixed reaction solution with an HMF mass concentration of 5%;

[0094] Step 2: Grind the 5%Ru-5%Co@CeO2 catalyst of Preparation Example 1 to a size of 100 mesh, and then fill it into the catalyst bed (volume 40 mL) of the tubular reactor R01 in the fixed bed reactor, with a filling amount of 100%; start the fixed bed reactor, set the reaction temperature to 160°C, the reaction pressure to 2 MPa, preheat the preheater E01 to the reaction temperature, and introduce 75% enriched oxygen to allow the system to reach the reaction pressure. During this period, pure water is pumped into the system at a rate of 20 mL / min by the metering pump P01. After the reaction system reaches the set value and the program is stable, stop pumping water, and pump the HMF mixed reaction liquid into the tubular reactor R01 at a rate of 5 mL / min by the metering pump P01, and flow through the catalyst bed for catalytic reaction;

[0095] Step 3: After the reaction is completed, the product is condensed in a cooler E02 and separated in a gas separator V03. The aqueous solution containing furandicarboxylate is collected in a storage tank V04A or a liquid storage tank V04B and discharged through a discharge valve. Hydrochloric acid is added to the aqueous solution containing furandicarboxylate discharged from the discharge valve to adjust the pH to <1. The precipitated solid is collected by filtration and dried to obtain FDCA. Its liquid phase diagram, hydrogen spectrum and carbon spectrum are shown in the following order: Figure 11-13 shown.

[0096] Example 2

[0097] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that the amount of water in step 1 is replaced with 3027 g (so that the mass concentration of the prepared HMF mixed reaction solution is 2%). The other steps and conditions remain the same, and FDCA is finally produced.

[0098] Example 3

[0099] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that the amount of water in step 1 is replaced with 777 g (so that the mass concentration of the prepared HMF mixed reaction solution is 7%). The other steps and conditions remain the same, and FDCA is finally produced.

[0100] Example 4

[0101] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that the amount of water in step 1 is replaced with 507 g (so that the mass concentration of the prepared HMF mixed reaction solution is 10%). The other steps and conditions remain the same, and FDCA is finally produced.

[0102] Example 5

[0103] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that the amount of sodium hydroxide in step 1 is replaced by 40 g (1 mol), so that the molar ratio of HMF:base is 1:2; the other steps and conditions remain the same, and FDCA is finally produced.

[0104] Example 6

[0105] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the 5%Ru-5%Co@CeO2 catalyst of Preparation Example 1 is replaced with the 5%Ru-10%Co@CeO2 catalyst of Preparation Example 2; the other steps and conditions remain the same, and FDCA is finally produced.

[0106] Example 7

[0107] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the 5%Ru-5%Co@CeO2 catalyst of Preparation Example 1 is replaced with the 10%Ru-5%Co@CeO2 catalyst of Preparation Example 3; the other steps and conditions remain the same, and FDCA is finally produced.

[0108] Example 8

[0109] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the 5%Ru-5%Co@CeO2 catalyst of Preparation Example 1 is replaced with the 5%Ru-5%Co@CeO2 catalyst of Preparation Example 4; the other steps and conditions remain the same, and FDCA is finally produced.

[0110] Example 9

[0111] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the 5%Ru-5%Co@CeO2 catalyst of Preparation Example 1 is replaced with the 5%Ru-5%Co@CeO2 catalyst of Preparation Example 5; the other steps and conditions remain the same, and FDCA is finally produced.

[0112] Example 10

[0113] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the 5%Ru-5%Co@CeO2 catalyst of Preparation Example 1 is ground and crushed to a size of 100 mesh and replaced with 50 mesh; the other steps and conditions remain the same, and FDCA is finally produced.

[0114] Example 11

[0115] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the 5%Ru-5%Co@CeO2 catalyst of Preparation Example 1 is ground and crushed to a size of 100 mesh and replaced with 30 mesh; the other steps and conditions remain the same, and FDCA is finally produced.

[0116] Example 12

[0117] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the reaction temperature is replaced from 160° C. to 130° C.; the other steps and conditions remain the same, and FDCA is finally produced.

[0118] Example 13

[0119] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the reaction temperature is replaced from 160° C. to 180° C.; the other steps and conditions remain the same, and FDCA is finally produced.

[0120] Example 14

[0121] This embodiment provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the reaction gas O2 is replaced by air; the other steps and conditions remain the same, and FDCA is finally produced.

[0122] Example 15

[0123] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the reaction pressure is replaced from 2 MPa to 0.1 MPa; the other steps and conditions remain the same, and FDCA is finally produced.

[0124] Example 16

[0125] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the reaction pressure is replaced from 2 MPa to 3 MPa; the other steps and conditions remain the same, and FDCA is finally produced.

[0126] Example 17

[0127] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the reaction pressure is replaced from 2 MPa to 1 MPa; the other steps and conditions remain the same, and FDCA is finally produced.

[0128] Example 18

[0129] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the pumping rate of the HMF mixed reaction solution is replaced from 5 mL / min to 2 mL / min; the other steps and conditions remain the same, and FDCA is finally produced.

[0130] Example 19

[0131] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the pumping rate of the HMF mixed reaction solution is replaced from 5 mL / min to 10 mL / min; the other steps and conditions remain the same, and FDCA is finally produced.

[0132] Example 20

[0133] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 2, the pumping rate of the HMF mixed reaction solution is replaced from 5 mL / min to 20 mL / min; the other steps and conditions remain the same, and FDCA is finally produced.

[0134] Example 21

[0135] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 1, sodium hydroxide is replaced with an equimolar amount of sodium carbonate; the other steps and conditions remain the same, and FDCA is finally produced.

[0136] Example 22

[0137] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 1, sodium hydroxide is replaced with an equimolar amount of potassium carbonate; the other steps and conditions remain the same, and FDCA is finally produced.

[0138] Example 23

[0139] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 1, sodium hydroxide is replaced with an equimolar amount of potassium bicarbonate; the other steps and conditions remain the same, and FDCA is finally produced.

[0140] Example 24

[0141] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 1, sodium hydroxide is replaced with an equimolar amount of sodium bicarbonate; the other steps and conditions remain the same, and FDCA is finally produced.

[0142] Example 25

[0143] This example provides a method for synthesizing furandicarboxylic acid. Compared with Example 1, the only difference is that in step 1, sodium hydroxide is replaced with an equimolar amount of potassium hydroxide; the other steps and conditions remain the same, and FDCA is finally produced.

[0144] In step 3 of Example 1-25, the aqueous solution containing furandicarboxylate discharged through the sample discharge valve was sampled and tested to test the purity of FDCA. The testing method and conditions were as follows:

[0145] Detection method: High performance liquid chromatography

[0146] Detection conditions: Hitachi L2000 HPLC System, Alltech C18 column; mobile phase: methanol: 0.5 wt% trifluoroacetic acid aqueous solution = 20:80; flow rate: 1.0 mL / min; column temperature: 30°C; detector: DAD, detection wavelength: 264 nm.

[0147] In step 3 of Example 1-25, the yield of the finally obtained FDCA was detected by high performance liquid chromatography (HPLC).

[0148] The above test results are listed in Table 1, which is as follows:

[0149] Table 1

[0150]

[0151] Analysis of the data in Table 1 shows that the x%Ru-y%Co@CeO2 catalyst in the method for synthesizing furandicarboxylic acid of the present invention has high catalytic activity and selectivity for preparing FDCA from HMF; the yield of FDCA can be further improved by changing the reaction conditions, such as substrate concentration, reaction temperature, and reaction pressure.

[0152] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for synthesizing furandicarboxylic acid, characterized in that: The steps include: Step 1: HMF, alkali and water are mixed to obtain an HMF mixed reaction solution; Step 2: Pump the HMF mixed reaction liquid into a fixed bed reactor filled with x%Ru-y%Co@CeO2 catalyst to carry out catalytic oxidation reaction, and obtain a reaction product liquid after the reaction is completed; Step 3: Condensing the reaction solution, collecting the aqueous solution containing furandicarboxylate, acidifying and filtering to obtain FDCA; In the x%Ru-y%Co@CeO2 catalyst of step 2, the x% is the molar ratio of Ru element to Ce element, x=5-10; the y% is the molar ratio of Co element to Ce element, y=5-10; The x%Ru-y%Co@CeO2 catalyst is prepared by the following steps: S1. Dissolve RuCl3·3H2O and Co(NO3)2·6H2O in a solvent system according to the molar ratio of Ru:Co=x:y, add NaBH4 solution dropwise until the pH of the solution system reaches 11, perform ultrasonic treatment and filter to obtain solid particles, wash and dry, grind and pulverize, and finally calcine to obtain an alloy core; S2. The alloy cores are dispersed in an ethanol aqueous solution containing 0.1 mol / L Ce(NO3)3 and 0.1 mol / L glucose according to a molar ratio of Ru:Ce=x%, and Co:Ce=y%. The pH is adjusted by alternately adding NH3·H2O to a pH of 9 and passing CO2 gas to a pH of 6. After alternating for 5 times, a reaction solution is obtained. The reaction solution is reacted at 80°C for 12 hours, filtered to obtain solid particles, washed, dried, and then calcined to obtain an x%Ru-y%Co@CeO2 catalyst. In step S1, the calcination conditions are: calcination at 300-500° C. for 2 h under nitrogen atmosphere; In step S2, the calcination condition is: calcination at 500°C for 3 hours in an air atmosphere.

2. The method for synthesizing furandicarboxylic acid according to claim 1, wherein In step S1, the ratio of the sum of the molar amounts of RuCl3·3H2O and Co(NO3)2·6H2O to the volume of the solvent system is 1 mmol:(25-50) mL.

3. The method for synthesizing furandicarboxylic acid according to claim 1, wherein In step S1, the solvent system is a mixed solution consisting of cyclohexane, polyethylene glycol octylphenyl ether and n-hexanol in a volume ratio of 4:3:

1.

4. The method for synthesizing furandicarboxylic acid according to claim 1, wherein In step S2, the ethanol-water solution is a mixed solution consisting of ethanol and water in a volume ratio of 3:

1.

5. The method for synthesizing furandicarboxylic acid according to claim 1, wherein In step 1, the molar ratio of HMF to alkali is (2-4):

1.

6. The method for synthesizing furandicarboxylic acid according to claim 1, wherein In step 1, the base is a composition consisting of any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate in any proportion.

7. The method for synthesizing furandicarboxylic acid according to claim 1, wherein In step 1, the mass fraction of HMF in the HMF mixed reaction solution is 1%-20%.

8. The method for synthesizing furandicarboxylic acid according to claim 1, wherein In step 2, the reaction temperature of the catalytic oxidation reaction is 130-180° C., and the reaction pressure is 0.1-3 MPa.

9. The method for synthesizing furandicarboxylic acid according to claim 1, wherein In step 2, the HMF mixed reaction liquid is pumped into the fixed bed reactor at a flow rate of 2-20 mL / min.

10. The method for synthesizing furandicarboxylic acid according to claim 1, wherein In step 2, the filling amount of the x%Ru-y%Co@CeO2 catalyst in the bed of the fixed bed reactor is 100%.

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