A preparation method of dimethyl 2,5-furandicarboxylate

Abstract

The present invention relates to the field of organic synthesis, and more particularly to a method for preparing dimethyl 2,5-furandicarboxylate. The present invention adds 5-hydroxymethylfurfural, a solvent, and a catalyst into a reactor, introduces an oxygen source, performs an oxidation-esterification reaction under stirring and heating conditions, and cools and filters after the reaction to obtain dimethyl 2,5-furandicarboxylate. The preparation method does not add alkaline substances in the reaction system, has a relatively low reaction pressure, is simple to operate, has high efficiency, has low pollution, and is suitable for industrial large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of organic synthesis, and particularly relates to a method for preparing dimethyl 2,5-furandicarboxylate. Background Art

[0002] The substitution of bio-based materials for petroleum-based materials has important scientific significance and application prospects. 5-Hydroxymethylfurfural has received extensive attention as a biomass platform molecule. 5-Hydroxymethylfurfural can be prepared by hydrolyzing fructose or glucose, and there are a large number of polysaccharide substances such as starch and cellulose in nature, which are widely sourced and inexpensive. Therefore, it has also been listed as one of the most important bio-platform compounds in the 21st century by the US Department of Energy. Based on 5-hydroxymethylfurfural, 2,5-furandicarboxylic acid (FDCA) can be prepared by oxidation, and FDCA has been listed as one of the most important high-value-added bio-platform molecules by the US Department of Energy. Dimethyl 2,5-furandicarboxylate can be used to prepare the bio-based polyester material PEF through transesterification. PEF is considered an excellent substitute for the petrochemical product PET and has the advantage of being biodegradable. Therefore, the preparation process of dimethyl 2,5-furandicarboxylate has also become an important research field in the process of synthesizing bio-based materials.

[0003] At present, there have been many reports on the method for preparing dimethyl 2,5-furandicarboxylate from 5-hydroxymethylfurfural. For example, CN110799504 A discloses a preparation method using noble metal gold supported on hydroxyapatite as a catalyst, and CN 11253353 A discloses a preparation method using a transition metal as a catalyst and adding a nitrogen source as an additive. CN 108892652 B discloses a catalytic preparation method under alkaline conditions. However, most of the catalysts selected in the above preparation methods are noble metals such as gold or palladium, and it is difficult to promote them on a large scale due to the high production cost. In addition, most reactions are carried out in a reaction atmosphere of alkaline additives. Although the alkaline conditions can improve the conversion rate, they also increase the possibility of hydrolysis, which is not conducive to subsequent treatment. Moreover, the oxidation process involving molecular oxygen in the reaction process is relatively fast, so the oxidation reaction needs to be carried out under high pressure, but too high pressure will increase the equipment investment cost and operation safety risk.

[0004] In view of this, in response to the above technical problems, developing a green and environmentally friendly non-noble metal catalyst with low cost and high catalytic activity, which can prepare dimethyl 2,5-furandicarboxylate without alkaline conditions, is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] The object of the present invention is to provide a method for preparing dimethyl 2,5-furandicarboxylate, so as to solve the technical problems of high production cost and high equipment requirements in the preparation process of dimethyl 2,5-furandicarboxylate.

[0007] (2) Technical solution

[0008] In order to solve the above problems, the present invention provides a method for preparing dimethyl 2,5-furandicarboxylate, specifically as follows:

[0009] 5-Hydroxymethylfurfural, a solvent, and a catalyst are added to a reaction kettle, an oxygen source is introduced, and an oxidation-esterification reaction is carried out under stirring and heating conditions. After the reaction is completed, it is cooled and filtered to obtain dimethyl 2,5-furandicarboxylate.

[0010] Preferably, the catalyst is an Anderson-type molybdenum-containing heteropolyacid catalyst.

[0011] Preferably, the preparation method of the Anderson-type molybdenum-containing heteropolyacid catalyst is as follows: Sodium molybdate is dissolved in water, nitric acid is added dropwise to adjust the pH to weakly acidic, and then a metal salt solution is added dropwise to obtain a mixed solution. The mixture is refluxed at 120 °C for 1 h, filtered and separated. The filtrate is transferred to a petri dish and allowed to stand for crystallization. After the crystallization is completed, it is dried at 80 °C under vacuum for 2 h. The dried crystals are pyrolyzed at 300 °C to 800 °C for 3 h to obtain an Anderson-type molybdenum-containing heteropolyacid catalyst.

[0012] Preferably, the metal salt is at least one of cobalt salt, manganese salt, nickel salt, copper salt, cerium salt, and calcium salt.

[0013] It should be noted that the Anderson-type heteropolyacid, also known as Anderson-type polyoxometalate, is an important structure in polyoxometalate compounds and is a highly efficient oxidant. It can exhibit fast and reversible multi-electron redox ability under relatively mild conditions. The Anderson heteropolyacid used in the present invention has molybdenum as the central ion, and the pentavalent molybdenum plays a key role in the activation of oxygen.

[0014] Preferably, the content of the catalyst is 1% to 15% of the mass of 5-hydroxymethylfurfural.

[0015] Preferably, the solvent is methanol.

[0016] Preferably, the oxygen source is oxygen or air.

[0017] Preferably, the mass ratio of 5-hydroxymethylfurfural to methanol is 1:5 to 10.

[0018] Preferably, the reaction temperature of the oxidation-esterification reaction is 50 °C to 120 °C, the reaction pressure is 0.3 MPa to 2.5 MPa, and the reaction time is 3 h to 8 h.

[0019] More preferably, the reaction temperature of the oxidation-esterification reaction is 70°C to 100°C, and the reaction pressure is 1 MPa to 1.5 Mpa.

[0020] Preferably, the temperature of the cooling is below 50°C.

[0021] Preferably, the stirring speed of the oxidation-esterification reaction is 600 r / min.

[0022] (3) Beneficial effects

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] In the present invention, 5-hydroxymethylfurfural, a solvent, and a catalyst are added to a reaction kettle, an oxygen source is introduced, and an oxidation-esterification reaction is carried out under stirring and heating conditions. After the reaction is completed, it is cooled and filtered to obtain dimethyl 2,5-furandicarboxylate.

[0025] 1. The present invention uses Anderson-type molybdenum-containing heteropolyacid as a catalyst, which belongs to a non-precious metal catalyst and contains an important structure in polyoxometalate compounds. It is an efficient oxidant with high reaction activity and low production cost.

[0026] 2. The chemical reaction of the present invention can be carried out under a relatively low pressure, with low requirements for production equipment, simple operation, and is suitable for large-scale industrial production.

[0027] 3. No basic substances are added to the reaction system of the present invention, and the organic solvent is only methanol, both of which are low-toxic chemical reagents, easy to recover and have good environmental protection. Specific embodiments

[0028] In order to more clearly understand the above-mentioned objects, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0030] The following further describes the embodiments of the present invention in detail in conjunction with the examples. The detailed description of the following examples is used to exemplarily illustrate the principle of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0031] Unless otherwise specified in the following examples, the raw materials and solvents in the embodiments of the present application are all purchased through commercial channels.

[0032] Example 1

[0033] (1) Catalyst preparation

[0034] Weigh 5.43 g of sodium molybdate dihydrate and dissolve it in 10 mL of deionized water. Adjust the pH to 4.5 - 4.8 with concentrated nitric acid. Then weigh 0.531 g of cobalt acetate and dissolve it in 10 mL of deionized water. Add it dropwise to the above solution at 45°C. Reflux the solution at 120°C for 1 h, filter it while it is hot, transfer the filtrate to a petri dish, let it stand for crystallization, dry the crystals under vacuum at 80°C for 2 h, and then pyrolyze the dried solid under a protective gas at 300°C - 800°C for 2 h to obtain the required catalyst, which is denoted as CoCat.

[0035] (2) Synthesis of dimethyl 2,5 - furandicarboxylate

[0036] Add 50 mL of methanol to a 100 - mL reactor. Weigh 5 g of HMF crystals and 0.5 g of the catalyst prepared as described above, and add them to the reactor. Set the stirring speed of the reactor to 600 r / min, set the reaction temperature to 70°C, after heating to the set temperature, introduce oxygen to make the pressure 2.5 Mpa, and set the reaction time to 4 h. After the reaction is completed, cool it to 50°C for filtration, cool the filtrate to room temperature. If no crystals precipitate, directly dilute the filtrate and determine the content of dimethyl 2,5 - furandicarboxylate by liquid chromatography.

[0037] Example 2

[0038] (1) Catalyst preparation

[0039] Weigh 5.43 g of sodium molybdate dihydrate and dissolve it in 10 mL of deionized water. Adjust the pH to 4.5 - 4.8 with concentrated nitric acid. Then weigh 0.735 g of manganese acetate and dissolve it in 10 mL of deionized water. Add it dropwise to the above solution at 45°C. The remaining catalyst preparation steps and reaction conditions are the same as in Example 1, and the catalyst is denoted as MnCat.

[0040] (2) Synthesis of dimethyl 2,5 - furandicarboxylate

[0041] The synthesis steps and reaction conditions are the same as in Example 1.

[0042] Example 3

[0043] (1) Catalyst preparation

[0044] Weigh 5.43 g of sodium molybdate dihydrate and dissolve it in 10 mL of deionized water. Adjust the pH to 4.5 - 4.8 with concentrated nitric acid. Then weigh 0.548 g of nickel nitrate and dissolve it in 10 mL of deionized water. Add it dropwise to the above solution at 45°C. The remaining catalyst preparation steps and reaction conditions are the same as in Example 1, and the catalyst is denoted as NiCat.

[0045] (2) Synthesis of dimethyl 2,5 - furandicarboxylate

[0046] The synthesis steps and reaction conditions are the same as in Example 1.

[0047] Example 4

[0048] (1) Catalyst preparation

[0049] Weigh 5.43 g of sodium molybdate dihydrate and dissolve it in 10 mL of deionized water. Adjust the pH to 4.5 - 4.8 with concentrated nitric acid. Then weigh 0.563 g of copper nitrate and dissolve it in 10 mL of deionized water. Add it dropwise to the above solution at 45°C. The remaining catalyst preparation steps and reaction conditions are the same as in Example 1, and the catalyst is denoted as CuCat.

[0050] (2) Synthesis of dimethyl 2,5 - furandicarboxylate

[0051] The synthesis steps and reaction conditions are the same as in Example 1.

[0052] Example 5

[0053] (1) Catalyst preparation

[0054] Weigh 5.43 g of sodium molybdate dihydrate and dissolve it in 10 mL of deionized water. Adjust the pH to 4.5 - 4.8 with concentrated nitric acid. Then weigh 0.663 g of cerium nitrate and dissolve it in 10 mL of deionized water. Add it dropwise to the above solution at 45°C. The remaining catalyst preparation steps and reaction conditions are the same as in Example 1, and the catalyst is denoted as CeCat.

[0055] (2) Synthesis of dimethyl 2,5 - furandicarboxylate

[0056] The synthesis steps and reaction conditions are the same as in Example 1.

[0057] Example 6

[0058] (1) Catalyst preparation

[0059] Weigh 5.43 g of sodium molybdate dihydrate and dissolve it in 10 mL of deionized water. Adjust the pH to 4.5 - 4.8 with concentrated nitric acid. Then weigh 0.531 g of cobalt acetate and 0.735 g of manganese acetate, dissolve them in 10 mL of deionized water, and add them dropwise to the above solution at 45 °C. The remaining catalyst preparation steps and reaction conditions are the same as those in Example 1, and the catalyst is denoted as CoMnCat.

[0060] (2) Synthesis of dimethyl 2,5 - furandicarboxylate

[0061] The synthesis steps and reaction conditions are the same as those in Example 1.

[0062] Example 7

[0063] (1) Catalyst preparation

[0064] Weigh 5.43 g of sodium molybdate dihydrate and dissolve it in 10 mL of deionized water. Adjust the pH to 4.5 - 4.8 with concentrated nitric acid. Then weigh 0.531 g of cobalt acetate and 0.563 g of copper nitrate, dissolve them in 10 mL of deionized water, and add them dropwise to the above solution at 45 °C. The remaining catalyst preparation steps and reaction conditions are the same as those in Example 1, and the catalyst is denoted as CoCuCat.

[0065] (2) Synthesis of dimethyl 2,5 - furandicarboxylate

[0066] The synthesis steps and reaction conditions are the same as those in Example 1.

[0067] Example 8

[0068] (1) Catalyst preparation

[0069] Weigh 5.43 g of sodium molybdate dihydrate and dissolve it in 10 mL of deionized water. Adjust the pH to 4.5 - 4.8 with concentrated nitric acid. Then weigh 0.531 g of cobalt acetate and 0.663 g of cerium nitrate, dissolve them in 10 mL of deionized water, and add them dropwise to the above solution at 45 °C. The remaining catalyst preparation steps and reaction conditions are the same as those in Example 1, and the catalyst is denoted as CoCeCat.

[0070] (2) Synthesis of dimethyl 2,5 - furandicarboxylate

[0071] The synthesis steps and reaction conditions are the same as those in Example 1.

[0072] Example 9

[0073] (1) Catalyst preparation

[0074] Weigh 5.43 g of sodium molybdate dihydrate and dissolve it in 10 mL of deionized water. Adjust the pH to 4.5 - 4.8 with concentrated nitric acid. Then weigh 0.531 g of cobalt acetate, 0.735 g of manganese acetate, and 0.663 g of cerium nitrate, dissolve them in 10 mL of deionized water, and add them dropwise to the above solution at 45 °C. The remaining catalyst preparation steps and reaction conditions are the same as those in Example 1, and the catalyst is denoted as CoMnCeCat.

[0075] (2) Synthesis of dimethyl 2,5 - furandicarboxylate

[0076] The synthesis steps and reaction conditions are the same as those in Example 1.

[0077] Example 10

[0078] (1) Catalyst preparation

[0079] Weigh 5.43 g of sodium molybdate dihydrate and dissolve it in 10 mL of deionized water. Adjust the pH to 4.5 - 4.8 with concentrated nitric acid. Then weigh 0.333 g of calcium chloride, dissolve it in 10 mL of deionized water, and add it dropwise to the above solution at 45 °C. The remaining catalyst preparation steps and reaction conditions are the same as those in Example 1, and the catalyst is denoted as CaCat.

[0080] (2) Synthesis of dimethyl 2,5 - furandicarboxylate

[0081] The synthesis steps and reaction conditions are the same as those in Example 1.

[0082] Table 1 shows the conversion rate and selectivity results of dimethyl 2,5 - furandicarboxylate prepared in Examples 1 - 10 using different molybdenum heteropolyacid catalysts.

[0083] Table 1 Conversion rate and selectivity of dimethyl 2,5 - furandicarboxylate prepared in Examples 1 - 10

[0084] Example Name Catalyst Conversion Rate (%) Selectivity (%) Example 1 CoCat 100 94.2 Example 2 MnCat 100 96.8 Example 3 NiCat 95.2 82.1 Example 4 Cucat 98.5 86.3 Example 5 CeCat 100 94.5 Example 6 CoMnCat 100 97.2 Example 7 CoCuCat 100 95.3 Example 8 CoCeCat 100 97.5 Example 9 CoMnCeCat 100 98.3 Example 10 CaCat 92.1 84.6

[0085] It should be clear that the present invention is not limited to the specific steps and structures described above. And, for the sake of brevity, the detailed description of known method technologies is omitted here.

[0086] The above are only the embodiments of the present application and do not limit the present application. For those skilled in the art, the present application can have various changes and modifications without departing from the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A method for preparing dimethyl 2,5-furandicarboxylate, Features: 5-Hydroxymethylfurfural, a solvent and a catalyst are added to a reaction kettle, an oxygen source is introduced, and an oxidation-esterification reaction is carried out under stirring and heating conditions. After the reaction is completed, the reaction is cooled and filtered to obtain dimethyl 2,5-furandicarboxylate; The catalyst is an Anderson type molybdenum-containing heteropoly acid catalyst; the preparation method of the Anderson type molybdenum-containing heteropoly acid catalyst is: dissolving sodium molybdate in water, adding nitric acid dropwise to adjust the pH to weak acidity, and then adding a metal salt solution dropwise to obtain a mixed solution, refluxing the mixture at 120° C. for 1 hour, filtering and separating, transferring the filtrate to a culture dish, standing for crystallization, drying at 80° C. for 2 hours under vacuum after the crystallization is completed, and pyrolyzing the dried crystals at 300° C. to 800° C. for 3 hours to obtain the Anderson type molybdenum-containing heteropoly acid catalyst; The metal salt is at least one of cobalt salt, manganese salt, nickel salt, copper salt, cerium salt and calcium salt.

2. The method for preparing dimethyl 2,5-furandicarboxylate according to claim 1, Features: The content of the catalyst is 1% to 15% of the mass of 5-hydroxymethylfurfural.

3. The method for preparing dimethyl 2,5-furandicarboxylate according to claim 1, Features: The solvent is methanol.

4. The method for preparing dimethyl 2,5-furandicarboxylate according to claim 1, Features: The oxygen source is oxygen or air.

5. The method for preparing dimethyl 2,5-furandicarboxylate according to claim 3, Features: The mass ratio of the 5-hydroxymethylfurfural to methanol is 1:5-10.

6. The method for preparing dimethyl 2,5-furandicarboxylate according to claim 1, Features: The reaction temperature of the oxidation-esterification reaction is 50° C. to 120° C., the reaction pressure is 0.3 MPa to 2.5 MPa, and the reaction time is 3 h to 8 h.

7. The method for preparing dimethyl 2,5-furandicarboxylate according to claim 1, Features: The cooling temperature is 50° C. or lower.