A method for synthesizing 2,5-furandicarboxylic acid by carboxylation

Abstract

This invention discloses a method for synthesizing 2,5-furandicarboxylic acid (FDCA) by carboxylation, belonging to the field of organic chemical synthesis technology. The preparation method of this invention is as follows: In a rotary kiln, furoic acid and carbonate are mixed and then an X%Ru-Y%Cs / C catalyst is added. Carbon dioxide is introduced to carry out the carboxylation reaction. After the reaction, acidification is performed, and FDCA is separated and collected. In the X%Ru-Y%Cs / C catalyst, X is the molar percentage of Ru, 0.5≤X≤20, and Y is the molar percentage of Cs, 1≤Cs≤20. The prepared X%Ru-Y%Cs / C catalyst has a large specific surface area, and the preparation method is simple and the reaction conditions are mild. Using this catalyst to synthesize FDCA has the advantages of high reaction efficiency, high yield, and low cost.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, specifically relating to a method for synthesizing 2,5-furandicarboxylic acid by carboxylation. Background Technology

[0002] 2,5-Furandicarboxylic acid (FDCA) is a biomass-derived compound with significant application potential and is listed by the U.S. Department of Energy as one of the twelve key bio-based platform chemicals. Its structure is similar to terephthalic acid, and it is considered a potential substitute for terephthalic acid in the manufacture of polyester plastics, enabling the production of next-generation biodegradable plastics similar to polyethylene terephthalate (PET). Its pentacyclic bifunctional structure, compared to the six-membered ring structure of terephthalic acid, exhibits an asymmetric molecular arrangement, thus allowing for the synthesis of optical / gas-barrier polymers. FDCA also serves as an important intermediate in the production of other fine chemicals, pharmaceuticals, and pesticides. Therefore, the preparation of FDCA is considered a highly representative sustainable bioconversion process that replaces petroleum production, possessing significant application prospects and potential. Currently, the main synthetic method for FDCA uses expensive 5-hydroxymethylfurfural (HMF) as a raw material. This method suffers from low overall yield and high cost, making large-scale industrial application difficult. Furoic acid, as an inexpensive bio-based raw material, can be used to prepare FDCA by carboxylating the carbon at the 5-position of furoic acid with carbonate and CO2, providing a new approach for FDCA synthesis. However, this reaction condition is relatively harsh and the reaction efficiency is low, resulting in a low yield of FDCA. Therefore, there is an urgent need for a catalyst with a large number of catalytically active sites to improve the efficiency of the carboxylation reaction between furoic acid and carbon dioxide, thereby increasing the yield of FDCA. Summary of the Invention

[0003] The purpose of this invention is to provide a method for synthesizing 2,5-furandicarboxylic acid by carboxylation, in order to solve the problems of low efficiency and low FDCA yield in the carboxylation reaction of furoic acid and carbon dioxide in the prior art.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0006] S1. Preparation of X%Ru-Y%Cs / C catalyst: The Ru / C catalyst is added sequentially to an aqueous solution containing cesium carbonate, stirred at 600-800 rpm. After the addition is complete, the mixture is stirred at 200-400 rpm for 0.5-1.5 h until homogeneous, and then allowed to stand for aging for 3-6 h. The black solid obtained after concentrating the reaction solution is placed in an oven and dried at 100-150℃ for 12-24 h. The solid is then ground into powder and placed in a rotary furnace. Under a nitrogen atmosphere, the temperature is uniformly raised to 300-600℃ at a rate of 5℃ / min and calcined for 1-10 h. The powder is then naturally cooled to room temperature (25-30℃). The calcined solid powder is placed in a tube furnace and reduced at a hydrogen atmosphere at a rate of 2℃ / min to 150-300℃ for 1-10 h. After reduction, the powder is cooled to room temperature and aged for 2-4 h to obtain the X%Ru-Y%Cs / C catalyst.

[0007] Furthermore, in the X%Ru-Y%Cs / C catalyst, X represents the molar percentage of Ru, 0.5 ≤ X ≤ 20; Y represents the molar percentage of Cs, 1 ≤ Cs ≤ 20. Specifically, the X%Ru-Y%Cs / C catalyst is X%Ru / C supported on Y%Cs. There is no essential relationship between the X and Y values; the combined effect of the two metals promotes the immobilization of carbon dioxide to form furanyl dicarboxylate. The difference in their ratio only affects the catalyst activity and product selectivity.

[0008] S2. Synthesis of 2,5-furandicarboxylic acid: Furoic acid and carbonate are mixed evenly, and then X%Ru-Y%Cs / C catalyst is added. After mixing evenly, carbon dioxide is introduced at a flow rate of 100-1000 mL / min to make the pressure of the reaction system 0.1-2 MPa. Under the condition of 10-100 rpm, the temperature is uniformly increased to 190-280℃ at a heating rate of 1-20℃ / min for 2-24 h. After the reaction is completed, the solid is naturally cooled to room temperature, and the solid is taken out and suspended in water. An acid solution is added for acidification treatment, and the pH is adjusted to no more than 1. A large amount of solid precipitates out. The solid is filtered, dried and collected as FDCA.

[0009] Furthermore, the carbonate in S2 includes sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, or lithium carbonate.

[0010] Furthermore, the acid solution used in the acidification treatment in S2 includes one or any combination of hydrochloric acid, sulfuric acid, dilute nitric acid, trifluoroacetic acid, and trifluoromethanesulfonic acid.

[0011] Furthermore, the molar ratio of furoic acid to carbonate is 1:1-10, and the mass ratio of catalyst to furoic acid is 0.05-1:1.

[0012] Furthermore, the 2,5-furandicarboxylic acid is synthesized by carboxylation in a rotary kiln, with carbon dioxide supplied by a carbon dioxide generator, which includes a generator inlet and a generator outlet. The rotary kiln includes a heating furnace, a main unit, a cooling receiving tank, and a rotating motor. The heating temperature range of the heating furnace is 30-500℃, and the temperature of the cooling receiving tank is 5-30℃.

[0013] Furthermore, the heating furnace includes an insulated furnace chamber, a shaped tube baffle, an electric heating wire, and a shaped tube. The heater inside the main unit of the equipment is used to regulate the heating of the electric heating wire inside the heating furnace. The temperature can be directly read from the temperature control instrument. The shaped tube inside the heating furnace is heated to the set temperature at a certain heating rate and then kept warm for reaction.

[0014] Furthermore, the material of the shaped tube is quartz.

[0015] Furthermore, the two ends of the shaped tube are respectively connected to the air inlet and the air outlet of the shaped tube via furnace tube flanges, and the air outlet of the shaped tube is connected to the air inlet of the cooling receiving tank via a pipe.

[0016] Furthermore, the main unit of the equipment is located at the bottom of the heating furnace and includes control buttons, a motor speed driver and a temperature control instrument, and is electrically connected to the heater. The temperature and time of the reaction system are controlled by the main unit of the equipment.

[0017] Furthermore, the cooling receiving tank includes a cooling receiving tank inlet, a cooling receiving tank outlet, and a cooling receiving tank discharge port. Since the water generated in the reaction system affects the reaction conversion rate, the cooling device is used to cool the mixed water vapor into water, which is then discharged through the cooling receiving tank discharge port. The carbon dioxide generator outputs high-pressure carbon dioxide through its generator outlet to the shaped tube in the heating furnace for reaction. The generator inlet is connected to the cooling receiving tank outlet via a circulation pipe. The cooling receiving tank cools the water vapor mixed in the reacted carbon dioxide into water, which is then discharged through the cooling receiving tank discharge port. Simultaneously, the remaining carbon dioxide is returned to the carbon dioxide generator for recycling through the cooling receiving tank outlet via the circulation pipe.

[0018] Furthermore, the control button of the main unit of the equipment adjusts the transmission belt synchronization device, so that the rotary furnace equipment can operate smoothly at a certain speed under the drive of the motor speed driver. The motor speed driver drives the rotating motor, and the motor synchronous pulley connected to the rotating motor drives the synchronous belt to transmit to the main synchronous pulley. The furnace tube gear on the outer surface of the shaped tube is nested and engaged with the main synchronous pulley, thereby driving the shaped tube to rotate.

[0019] As a further aspect of the present invention, a method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0020] S1. Preparation of X%Ru-Y%Cs / C catalyst: The Ru / C catalyst is added sequentially to an aqueous solution containing cesium carbonate, stirred at 600-800 rpm. After the addition is complete, the mixture is stirred at 200-400 rpm for 0.5-1.5 h until homogeneous, and then allowed to stand for aging for 3-6 h. The black solid obtained after concentrating the reaction solution is placed in an oven and dried at 100-150℃ for 12-24 h. The solid is then ground into powder and placed in a rotary furnace. Under a nitrogen atmosphere, the temperature is uniformly raised to 300-600℃ at a rate of 5℃ / min and calcined for 1-10 h. The powder is then naturally cooled to room temperature (25-30℃). The calcined solid powder is placed in a tube furnace and reduced at a hydrogen atmosphere at a rate of 2℃ / min to 150-300℃ for 1-10 h. After reduction, the powder is cooled to room temperature and aged for 2-4 h to obtain the X%Ru-Y%Cs / C catalyst. In the X%Ru-Y%Cs / C catalyst, X is the molar percentage of Ru, 0.5≤X≤20; Y is the molar percentage of Cs, 1≤Cs≤20.

[0021] S2. After physically mixing 1 mol of furoic acid with 1-10 mol of carbonate, add X%Ru-Y%Cs / C catalyst (0.5≤X≤20, 1≤Cs≤20), where the mass ratio of X%Ru-Y%Cs / C catalyst to furoic acid is 0.05-1:1. Add the mixed solid to a quartz tube, which is then clamped into a rotary kiln. Carbon dioxide is introduced into the tube at a flow rate of 100-1000 mL / min via a carbon dioxide generator, maintaining a reaction pressure of 0.1-2 MPa. The rotary kiln speed is adjusted to 10-100 rpm, and the heating rate is 1-20℃ / min, raising the temperature to 190-280℃. The reaction is maintained at this temperature for 2-24 hours. After the reaction is complete, allow it to cool naturally to room temperature and remove the solid. Place the solid in water, add acid to adjust the pH to ≤1, and filter the precipitated cake to obtain the synthesized product FDCA.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention provides a method for synthesizing 2,5-furandicarboxylic acid by carboxylation. In this invention, the X%Ru-Y%Cs / C type catalyst has a large specific surface area, and the preparation method is simple and the reaction conditions are mild. Using this catalyst to synthesize FDCA has the advantages of high reaction efficiency, high yield and low cost.

[0024] 2. This invention uses a rotary kiln with a carbon dioxide generator as the reaction device to synthesize FDCA under suitable reaction conditions. The water vapor mixed in the carbon dioxide after the reaction is condensed in a cooling receiving tank, and the remaining carbon dioxide is sent back to the carbon dioxide generator for recycling through a circulation pipe. This not only removes the water vapor generated during the reaction in a timely manner, reducing its impact on the reaction yield, but also removes water vapor from the carbon dioxide and recycles the carbon dioxide. It has the advantages of simple process, mild reaction conditions, low energy consumption, high yield, and cost savings. Attached Figure Description

[0025] The invention will now be further described with reference to the accompanying drawings.

[0026] Figure 1 This is the Fourier transform infrared (FTIR) spectrum of the 5%Ru-10%Cs / C catalyst in Example 2 of this invention;

[0027] Figure 2 This is the Raman spectrum of the 5%Ru-10%Cs / C type catalyst in Example 2 of the present invention;

[0028] Figure 3 This is the XPS diagram of the 5% Ru-10% Cs / C type catalyst in Example 2 of the present invention;

[0029] Figure 4 This is the XRD pattern of the 5% Ru-10% Cs / C type catalyst in Example 2 of the present invention;

[0030] Figure 5 This is a front view of the rotary converter in Embodiment 3 of the present invention;

[0031] Figure 6 This is a top view of the rotary converter in Embodiment 3 of the present invention;

[0032] Figure 7 This is a cross-sectional view of the rotary kiln of the present invention along line AA;

[0033] In the diagram: 1. Carbon dioxide generator; 2. Carbon dioxide generator inlet; 3. Carbon dioxide generator outlet; 4. Shaped tube inlet; 5. Circulation pipe; 6. Heating furnace; 7. Shaped tube outlet; 8. Cooling receiving tank inlet; 9. Cooling receiving tank outlet; 10. Cooling receiving tank; 11. Cooling receiving tank discharge port; 12. Control button; 13. Motor speed driver; 14. Temperature controller; 15. Main unit; 16. Furnace tube flange; 17. Main synchronous belt pulley; 18. Furnace tube gear; 19. Insulated furnace chamber; 20. Shaped tube baffle; 21. Electric heating wire; 22. Shaped tube; 23. Heater; 24. Rotating motor; 25. Motor synchronous belt pulley; 26. Synchronous belt. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] The 5% Ru / C catalyst was prepared by impregnation, including the following steps:

[0037] 25g of activated carbon was dissolved in 250mL of water and stirred for 0.5h to ensure uniform dispersion. A 10mL aqueous solution containing 2.6g of RuCl3 was slowly added dropwise to the dispersed activated carbon solution at 600rpm. After the addition was complete, stirring was continued for 1h, followed by overnight aging at room temperature (12h). The solution was concentrated to dryness, vacuum dried at 80℃ for 6h, and then ground into powder. The powder was calcined at 400℃ under a nitrogen atmosphere for 3h and then cooled. Reduction was performed in a tube furnace under a hydrogen atmosphere at 150℃ for 3h, with a heating rate of 2℃ / min. After reduction, the solution was cooled to room temperature, the two ends were opened, and the solution was aged under air for 3h with rotation. The resulting product was 20.0g of 5% Ru / C catalyst.

[0038] A 2% Ru / C catalyst was prepared using the same method, wherein the amount of RuCl3 was 1.0 g;

[0039] A 6% Ru / C catalyst, wherein the amount of RuCl3 is 3.1 g;

[0040] A 10% Ru / C catalyst, wherein the amount of RuCl3 is 5.1 g.

[0041] Example 2

[0042] The preparation of a 5% Ru-10% Cs / C catalyst includes the following steps:

[0043] 18.8 g of 5% Ru / C catalyst was added in five portions to a 500 mL aqueous solution containing 2.3 g of cesium carbonate, stirred at 700 rpm. After the addition was complete, the mixture was stirred at 300 rpm for 1 h, then stopped and allowed to stand for 4 h of aging. The reaction solution was concentrated to obtain a black solid, which was dried overnight (12 h) at 120 °C in an oven, yielding 24.5 g of the dried catalyst. The dried catalyst was ground into powder, placed in a rotary furnace, and calcined at 400 °C for 3 h with a nitrogen flow rate of 5 °C / min. The powder was then allowed to cool naturally to room temperature. The calcined catalyst was placed in a tube furnace and reduced at 200 °C for 4 h with a hydrogen atmosphere and a heating rate of 2 °C / min. After reduction, the catalyst was cooled to room temperature, the two ends were opened, and the catalyst was aged for 3 h to obtain 20.5 g of 5% Ru-10% Cs / C catalyst.

[0044] The performance of the 5% Ru-10% Cs / C catalyst prepared in Example 2 was tested. The catalyst had a specific surface area of ​​1050.7278 m² / g and a micropore volume of 0.372611 cm³. 3 / g indicates that the catalyst has a large specific surface area, which can increase the contact between the active sites and the substrate, thus facilitating the reaction.

[0045] The Fourier transform infrared (FTIR) spectrum of the 5% Ru-10% Cs / C catalyst is shown below. Figure 1 ,from Figure 1 The type of surface functional groups can be determined; the carbon support has carboxyl groups (CO stretching vibration at 1178 cm⁻¹). -1 The C=O stretching vibration occurs at 1630 cm⁻¹. -1 ), alcohol functional group (OH) in-plane bending at 1384 cm -1 The stretching vibration of OH is at 3417 cm. -1 ) and alkyl groups (CH stretching vibrations at 2922-2852 cm⁻¹) -1 );

[0046] The Raman spectrum of the 5% Ru-10% Cs / C catalyst is shown below. Figure 2 ,from Figure 2 The structural information of the carbon material is known. The figure shows two characteristic peaks located at approximately 1340 and 1594 cm⁻¹ in the D and G bands, respectively. –1 Location. D-band (sp) 3 The presence of carbon (associated with graphene defects caused by pentagons or heptagons) indicates the degree of surface defects and disorder in the carbon support, while the G-band corresponds to sp 2 The in-plane stretching vibrations of carbon atoms indicate that the carbon support has a graphite structure in the order of C atoms.

[0047] XPS plot of 5% Ru-10% Cs / C catalyst is shown below Figure 3,from Figure 3 It can be seen that the catalyst contains Ru (490-450, 288-278 eV), Cs (746-718 eV), O (544-528 eV), and C (290-282 eV);

[0048] The XRD pattern of the 5% Ru-10% Cs / C catalyst is shown in the figure. Figure 4 , Figure 4 The main peaks in the sample were carbon diffraction peaks, and no obvious Ru and Cs diffraction peaks were observed, indicating that the active sites Ru and Cs in the catalyst are uniformly dispersed, which is more conducive to the oxidation reaction. From the above characterization results, it can be seen that the 5%Ru-10%Cs / C catalyst has a large specific surface area. The catalyst contains Ru, Cs, O, and C elements. The C in the catalyst is mainly graphene-structured carbon, which facilitates electron transfer, while the highly dispersed Ru and Cs further promote the oxidation reaction.

[0049] Example 3

[0050] An apparatus for synthesizing 2,5-furandicarboxylic acid. Figure 5 This is a front view of the rotary kiln equipment. Figure 6 This is a top view of the rotary kiln equipment. Figure 7 This is a cross-sectional view of the rotary kiln along line AA, as shown in the figure. During operation, 1 mol of furoic acid and 1-10 mol of carbonate are physically mixed evenly, and then X%Ru-Y%Cs / C catalyst (0.5≤X≤20, 1≤Cs≤20) is added. The mass ratio of X%Ru-Y%Cs / C catalyst to furoic acid is 0.05-1:1. The mixed solid is added into a quartz-material shaped tube 22, and the shaped tube 22 is clamped and installed into the rotary kiln equipment using a baffle 20. The carbon dioxide generator outlet 3 of the carbon dioxide generator 1 is connected to the inlet 4 of the shaped tube, with a flow rate of 100-10... Carbon dioxide is introduced into the shaped tube 22 at a flow rate of 00 mL / min, making the internal pressure of the shaped tube 22 0.1-2 MPa; the transmission belt synchronization device is adjusted by the control button 12 of the main unit 15, so that the rotary furnace equipment operates smoothly at a speed of 10-100 rpm under the drive of the motor speed driver 13. The motor speed driver 13 drives the rotary motor 24, and the motor synchronous pulley 25 connected to the rotary motor 24 drives the synchronous belt 26 to transmit to the main synchronous pulley 17. The furnace tube gear 18 on the outer surface of the shaped tube 22 is nested and engaged with the main synchronous pulley 17, thereby driving the shaped tube 22 to rotate.

[0051] Meanwhile, the heater 23 inside the main unit 15 is used to regulate the heating of the electric heating wire 21 inside the heating furnace 6. The temperature can be directly read from the temperature control instrument. The irregularly shaped tube 22 inside the heating furnace 6 is heated to 190-280℃ at a heating rate of 1-20℃ / min, and then kept at this temperature in the insulated furnace chamber 19 for 2-24 hours. After the reaction is complete, it is naturally cooled to room temperature, and the solid is removed. The solid is placed in water, and an acid solution is added to adjust the pH to ≤1. The precipitated filter cake is then filtered to obtain the synthesized product FDCA.

[0052] After the reaction, the water vapor and excess carbon dioxide produced enter the cooling receiving tank 10 through the air inlet 8 of the cooling receiving tank connected to the outlet 7 of the special-shaped pipe. The temperature of the cooling receiving tank 10 is controlled at 5-30℃. At this time, the water vapor is cooled into water through condensation and discharged from the outlet 11 of the cooling receiving tank, which effectively improves the reaction efficiency. The excess carbon dioxide flows out from the outlet 9 of the cooling receiving tank to the circulation pipe 5, and then returns to the carbon dioxide generator 1 from the inlet 2 of the carbon dioxide generator to realize the recycling of carbon dioxide.

[0053] Example 4

[0054] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0055] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0056] S2. 10g of furoic acid and 20g of potassium carbonate (molar ratio of furoic acid to potassium carbonate is 1:1.6) are physically mixed evenly. 1g of 5% Ru-10% Cs / C catalyst is added. The mixed solid is added into a quartz tube and clamped into a rotary kiln. Carbon dioxide is introduced into the tube at a flow rate of 1000mL / min through a carbon dioxide generator, and the reaction pressure is 0.1MPa. The rotary kiln speed is adjusted to 100rpm, the heating rate is 20℃ / min, the temperature is raised to 250℃, and the reaction is maintained at this temperature for 6h. After the reaction is complete, it is allowed to cool naturally to room temperature, and the solid is removed. The solid is suspended in 100mL of deionized water, and hydrochloric acid is added to adjust the pH to 0.8. The precipitated filter cake is filtered to obtain the synthesized product FDCA.

[0057] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0058] Sampling and analysis were performed under the following 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℃; detector: DAD; detection wavelength: 264 nm. The yield of FDCA was 78%, and the purity of FDCA was 99.3%.

[0059] Example 5

[0060] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0061] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0062] S2. Compared with Example 4, only the equimolar amount of potassium carbonate was replaced with sodium carbonate, wherein the mass of sodium carbonate was 15g, and the remaining components and steps were completely the same. After the reaction was completed, the yield of FDCA was measured to be 70% and the purity was 99.0%.

[0063] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0064] Example 6

[0065] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0066] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0067] S2. Compared with Example 4, only the equimolar amount of potassium carbonate was replaced with rubidium carbonate, wherein the mass of rubidium carbonate was 33.4 g. The remaining components and steps were completely the same. After the reaction was completed, the yield of FDCA was measured to be 68% and the purity was 98.8%.

[0068] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0069] Example 7

[0070] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0071] S1. Prepare a 5% Ru-5% Cs / C catalyst. The preparation process is the same as in Example 2, except that the amount of cesium carbonate used is 1.2g, while the other components and steps are completely the same.

[0072] S2. Same as Example 4, except that the 5% Ru-5% Cs / C catalyst prepared in S1 is used. The remaining components and steps are completely the same. After the reaction, the FDCA yield was measured to be 70% and the purity was 99.1%.

[0073] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0074] Example 8

[0075] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0076] S1. Prepare a 5% Ru-15% Cs / C catalyst. The preparation process is the same as in Example 2, except that the amount of cesium carbonate used is 3.5g, while the other components and steps are completely the same.

[0077] S2. Same as Example 4, except that the 5% Ru-15% Cs / C catalyst prepared in S1 is used. The remaining components and steps are completely the same. After the reaction, the FDCA yield was measured to be 72% and the purity was 99.4%.

[0078] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0079] Example 9

[0080] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0081] S1. Prepare a 5% Ru-20% Cs / C catalyst. The preparation process is the same as in Example 2, except that the amount of cesium carbonate used is 4.6 g, while the other components and steps are completely the same.

[0082] S2. Same as Example 4, except that the 5% Ru-20% Cs / C catalyst prepared in S1 is used. The remaining components and steps are completely the same. After the reaction, the FDCA yield was measured to be 69% and the purity was 98.9%.

[0083] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0084] Example 10

[0085] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0086] S1. Prepare a 2%Ru-10%Cs / C catalyst. The preparation process is the same as in Example 2, except that a 2%Ru / C catalyst is used. The other components and steps are completely the same.

[0087] S2. Same as Example 4, except that the 2% Ru-10% Cs / C catalyst prepared in S1 is used; the remaining components and steps are completely identical. After the reaction, the FDCA yield was measured to be 73%, and the purity was 98.7%.

[0088] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0089] Example 11

[0090] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0091] S1. Prepare a 6%Ru-10%Cs / C catalyst. The preparation process is the same as in Example 2, except that a 6%Ru / C catalyst is used. The other components and steps are completely the same.

[0092] S2. Same as Example 4, except that the 6% Ru-10% Cs / C catalyst prepared in S1 was used; the remaining components and steps were completely identical. After the reaction, the FDCA yield was measured to be 79%, and the purity was 99.1%.

[0093] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0094] Example 12

[0095] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0096] S1. Prepare a 10%Ru-10%Cs / C catalyst. The preparation process is the same as in Example 2, except that a 10%Ru / C catalyst is used. The other components and steps are completely the same.

[0097] S2. Same as Example 4, except that the 10% Ru-10% Cs / C catalyst prepared in S1 is used; the remaining components and steps are completely identical. After the reaction, the FDCA yield was measured to be 80%, and the purity was 99.1%.

[0098] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0099] Example 13

[0100] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0101] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0102] S2. Compared with Example 4, the difference is that the temperature is raised to 190°C and the reaction is maintained at that temperature. The other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 68% and the purity was 99.0%.

[0103] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0104] Example 14

[0105] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0106] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0107] S2. Compared with Example 4, the difference is that the temperature is raised to 230°C and the reaction is maintained at that temperature. The other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 75% and the purity was 98.9%.

[0108] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0109] Example 15

[0110] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0111] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0112] S2. Compared with Example 4, the difference is that the temperature is raised to 270°C and the reaction is maintained at that temperature. The other components and steps are completely the same. After the reaction is completed, the yield of FDCA is 73% and the purity is 99.1%.

[0113] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0114] Example 16

[0115] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0116] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0117] S2. Compared with Example 4, the difference is that the heat preservation reaction time is 8 hours, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 79% and the purity was 98.0%.

[0118] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0119] Example 17

[0120] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0121] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0122] S2. Compared with Example 4, the difference is that the heat preservation reaction time is 12h, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 80% and the purity was 98.7%.

[0123] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0124] Example 18

[0125] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0126] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0127] S2. Compared with Example 4, the difference is that the reaction pressure is 1 MPa, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 80% and the purity was 99.4%.

[0128] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0129] Example 19

[0130] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0131] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0132] S2. Compared with Example 4, the difference is that the reaction pressure is 2 MPa, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 82% and the purity was 99.0%.

[0133] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0134] Example 20

[0135] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0136] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0137] S2. Compared with Example 4, the difference is that the carbon dioxide flow rate is 400 mL / min, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 63% and the purity was 99.1%.

[0138] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0139] Example 21

[0140] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0141] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0142] S2. Compared with Example 4, the difference is that the carbon dioxide flow rate is 700 mL / min, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 71% and the purity was 98.7%.

[0143] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0144] Example 22

[0145] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0146] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0147] S2. Compared with Example 4, the difference is that the rotary furnace speed is 25 rpm, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 62% and the purity was 98.9%.

[0148] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0149] Example 23

[0150] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0151] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0152] S2. Compared with Example 4, the difference is that the rotary furnace speed is 50 rpm, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 68% and the purity was 99.1%.

[0153] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0154] Example 24

[0155] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0156] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0157] S2. Compared with Example 4, the difference is that the rotary furnace speed is 75 rpm, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 70% and the purity was 98.5%.

[0158] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0159] Example 25

[0160] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0161] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0162] S2. Compared with Example 4, the difference is that the heating rate is 10℃ / min, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 73% and the purity was 99.2%.

[0163] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0164] Example 26

[0165] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0166] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0167] S2. Compared with Example 4, the difference is that the heating rate is 15℃ / min, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 75% and the purity was 99.4%.

[0168] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0169] Example 27

[0170] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0171] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0172] S2. Compared with Example 4, the difference is that the amount of potassium carbonate used is 62.2g, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 70% and the purity was 99.0%.

[0173] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0174] Example 28

[0175] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0176] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0177] S2. Compared with Example 4, the difference is that the amount of potassium carbonate used is 124.0g, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 65% and the purity was 99.1%.

[0178] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0179] Example 29

[0180] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0181] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0182] S2. Compared with Example 4, the difference is that the amount of 5% Ru-10% Cs / C catalyst is 5g, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 65% and the purity was 98.8%.

[0183] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0184] Example 30

[0185] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0186] S1. Prepare a 5% Ru-10% Cs / C catalyst, the preparation process of which is the same as in Example 2;

[0187] S2. Compared with Example 4, the difference is that the amount of 5% Ru-10% Cs / C catalyst used is 9.5g, while the other components and steps are completely the same. After the reaction, the yield of FDCA was measured to be 63% and the purity was 99.0%.

[0188] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0189] Example 31

[0190] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0191] S1. Prepare a 5% Ru-10% Cs / C catalyst. The preparation process is the same as in Example 2, except that: the temperature is increased to 400°C at a rate of 5°C / min, calcined for 2 hours, and then naturally cooled to room temperature; the calcined catalyst is placed in a tube furnace and reduced to 200°C at a rate of 2°C / min in a hydrogen atmosphere for 3 hours; the remaining components and steps are completely the same.

[0192] S2. Compared with Example 4, the difference is that the 5% Ru-10% Cs / C catalyst prepared in S2 is used. The other components and steps are completely the same. After the reaction, the FDCA yield was measured to be 80% and the purity was 99.1%.

[0193] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0194] Example 32

[0195] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0196] S1. Prepare a 5% Ru-10% Cs / C catalyst. The preparation process is the same as in Example 2, except that: the temperature is increased to 400°C at a rate of 5°C / min, calcined for 5 hours, and then naturally cooled to room temperature; the calcined catalyst is placed in a tube furnace and reduced to 200°C at a rate of 2°C / min in a hydrogen atmosphere for 5 hours; the remaining components and steps are completely the same.

[0197] S2. Compared with Example 4, the difference is that the 5% Ru-10% Cs / C catalyst prepared in S2 is used. The other components and steps are completely the same. After the reaction, the FDCA yield was measured to be 79% and the purity was 99.0%.

[0198] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0199] Example 33

[0200] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0201] S1. Prepare a 5% Ru-10% Cs / C catalyst. The preparation process is the same as in Example 2, except that: the temperature is increased to 500°C at a rate of 5°C / min, calcined for 3 hours, and then naturally cooled to room temperature; the calcined catalyst is placed in a tube furnace and reduced to 250°C at a rate of 2°C / min in a hydrogen atmosphere for 4 hours; the remaining components and steps are completely the same.

[0202] S2. Compared with Example 4, the difference is that the 5% Ru-10% Cs / C catalyst prepared in S2 is used. The other components and steps are completely the same. After the reaction, the FDCA yield was measured to be 79% and the purity was 99.3%.

[0203] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0204] Example 34

[0205] A method for synthesizing 2,5-furandicarboxylic acid by carboxylation includes the following steps:

[0206] S1. Prepare a 5% Ru-10% Cs / C catalyst. The preparation process is the same as in Example 2, except that: the temperature is increased to 300°C at a rate of 5°C / min, calcined for 3 hours, and then naturally cooled to room temperature; the calcined catalyst is placed in a tube furnace and reduced to 150°C at a rate of 2°C / min in a hydrogen atmosphere for 4 hours; the remaining components and steps are completely the same.

[0207] S2. Compared with Example 4, the difference is that the 5% Ru-10% Cs / C catalyst prepared in S2 is used. The other components and steps are completely the same. After the reaction, the FDCA yield was measured to be 77% and the purity was 99.3%.

[0208] The apparatus used for synthesizing 2,5-furandicarboxylic acid in this embodiment is the same as in Embodiment 3.

[0209] Examples 4-6 show that, when using different bases (sodium carbonate, calcium carbonate) as reactants, the FDCA yield is best under potassium carbonate conditions, reaching 78%. Examples 4 and 7-12 show that adjusting the mass fraction of Cs or Ru in the catalyst can affect the FDCA yield. Examples 4 and 13-15 show that the FDCA yield increases with increasing temperature, but above 250°C, the yield decreases with increasing temperature, mainly due to the decomposition of FDCA at a certain temperature, which affects the reaction yield. Examples 4 and 16-17 show that the longer the holding time, the higher the reaction conversion rate; when the holding time is 12 hours, the FDCA yield can reach up to 80%. Examples 4 and 18-21 show that controlling the reaction pressure and carbon dioxide flow rate can further improve the product yield. Examples 4... Examples 22-24 show that the reaction yield is highest at 100 rpm under different rotary furnace speeds (25 rpm, 50 rpm, 75 rpm, 100 rpm). Examples 4 and 25-26 show that the heating rate of the furnace has little effect on the reaction, with the highest FDCA yield at a heating rate of 20 °C / min. Examples 4 and 27-28 show that changing the equivalent of potassium carbonate affects the product yield, with the optimal equivalent of potassium carbonate being 1.65, resulting in a product yield of 78%. Examples 4 and 29-30 show that the best product yield is achieved when the catalyst input is 10% of the furoic acid. Examples 4 and 31-34 show that the calcination and reduction time and temperature during catalyst preparation have little effect on the product yield, with shorter calcination and reduction times resulting in a lower product yield. The above examples show that the type and amount of carbonate used in the reaction, the amount of catalyst, the heating temperature and rate, the rotary kiln speed, the holding time, the carbon dioxide flow rate, and the reaction pressure are all factors that affect the yield of FDCA. Reasonable screening and optimization of experimental conditions and proper control of experimental variables can help improve the conversion rate of the reaction.

[0210] The X%Ru-Y%Cs / C catalyst prepared in this invention has a large specific surface area, and its use in the carboxylation synthesis of FDCA offers advantages such as high yield and low cost. Furthermore, the use of a rotary kiln equipped with a carbon dioxide generator can promptly remove water vapor generated during the reaction, reducing its impact on the reaction yield, and can also remove water vapor from the carbon dioxide, allowing for carbon dioxide recycling. This process offers advantages such as simple operation, mild reaction conditions, low energy consumption, high yield, and cost savings.

[0211] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0212] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for synthesizing 2,5-furandicarboxylic acid by carboxylation, characterized in that, Includes the following steps: In a rotary kiln, furoic acid and carbonate are mixed and then an X%Ru-Y%Cs / C catalyst is added. Carbon dioxide is introduced to carry out a carboxylation reaction. After the reaction, acidification is performed, and FDCA is separated and collected. In the X%Ru-Y%Cs / C catalyst, X is the molar percentage of Ru, 0.5≤X≤20, and Y is the molar percentage of Cs, 1≤Cs≤20. The X%Ru-Y%Cs / C catalyst is prepared by the following steps: The Ru / C catalyst was added to a cesium carbonate aqueous solution stirred at 600-800 rpm and stirred at 200-400 rpm for 0.5-1.5 h until homogeneous. The mixture was then allowed to stand for 3-6 h to age. The black solid obtained after concentrating the reaction solution was placed in an oven and dried at 100-150℃ for 12-24 h. After grinding into powder, the powder was calcined in a nitrogen atmosphere at a rate of 5℃ / min to 300-600℃ for 1-10 h, and then allowed to cool naturally to room temperature. The calcined solid powder was then reduced in a hydrogen atmosphere at a rate of 2℃ / min to 150-300℃ for 1-10 h. After reduction, the powder was cooled to room temperature and aged for 2-4 h to obtain the X%Ru-Y%Cs / C catalyst.

2. The method for synthesizing 2,5-furandicarboxylic acid by carboxylation according to claim 1, characterized in that, The molar ratio of furoic acid to carbonate is 1:1-10, and the molar ratio of furoic acid to X%Ru-Y%Cs / C catalyst is 1:0.05-1.

3. The method for synthesizing 2,5-furandicarboxylic acid by carboxylation according to claim 1, characterized in that, The carbonate is selected from sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, or lithium carbonate.

4. The method for synthesizing 2,5-furandicarboxylic acid by carboxylation according to claim 1, characterized in that, The carbon dioxide flow rate is 100-1000 mL / min.

5. The method for synthesizing 2,5-furandicarboxylic acid by carboxylation according to claim 1, characterized in that, The carboxylation reaction conditions are as follows: the reaction system pressure is 0.1-2 MPa, the rotation speed is 10-100 rpm, and the temperature is uniformly increased to 190-280℃ at a heating rate of 1-20℃ / min for 2-24 hours.

6. The method for synthesizing 2,5-furandicarboxylic acid by carboxylation according to claim 1, characterized in that, The acidification treatment specifically involves adjusting the pH of the reaction system to be no greater than 1 using an acid solution.

7. The method for synthesizing 2,5-furandicarboxylic acid by carboxylation according to claim 6, characterized in that, The acid solution is selected from one or any combination of hydrochloric acid, sulfuric acid, dilute nitric acid, trifluoroacetic acid, and trifluoromethanesulfonic acid.

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