CN108383814A - A kind of preparation method of 2,5- furandicarboxylic acids - Google Patents

Abstract

The invention provides a preparation method of 2,5-furandicarboxylic acid. Firstly, furan formate is obtained by neutralizing furan formic acid, basic compound and water; then, under the condition of carbon dioxide gas, the above steps After reacting the obtained furan formic acid salt, molten salt and catalyst, 2,5-furandicarboxylic acid salt is obtained; the melting point of the molten salt is less than or equal to 400°C; the catalyst includes a metal salt catalyst and/or an organic Alkaline catalyst; finally, the 2,5-furandicarboxylic acid salt obtained in the above steps is acidified to obtain 2,5-furandicarboxylic acid. In the present invention, furan formic acid is used as a starting material, furan formate is first prepared, and then conventional metal salts and/or organic bases are cheap and easy to obtain as catalysts, and monomers or mixtures of organic salts or inorganic salts with low melting points are used as catalysts. The molten salt has simple process, low reaction temperature, economy and environmental protection, and is suitable for large-scale industrial production.

Description

A kind of preparation method of 2,5-furandicarboxylic acid

technical field

The invention belongs to the technical field of 2,5-furandicarboxylic acid synthesis, and relates to a preparation method of 2,5-furandicarboxylic acid, in particular to a low-cost industrial preparation method of 2,5-furandicarboxylic acid.

Background technique

2,5-furandicarboxylic acid (FDCA), the chemical formula is C ₆ H ₄ O ₅ , and the structural formula is As an important derivative of furan, its bio-based polymer aromatic ring monomer with a "rigid" planar structure can be polymerized with monomers such as diols and diamines to prepare new bio-based polymer synthetic materials with excellent performance. It is an important chemical raw material and organic chemical intermediate.

At present, with the wide application of polyester products, the rapid development of the polyester raw material industry has been driven. Among them, the development of bio-based polyester monomers used to replace petroleum-based raw materials has become one of the current research hotspots in the field of polyester. Polyethylene terephthalate (PET), as an important thermoplastic polyester, has the advantages of excellent toughness, easy processing and high recovery rate, and is widely used in the field of packaging. At present, ethylene glycol, one of the raw materials for producing PET, can already be prepared from biomass raw materials. For example, the existing technology has successfully prepared a fully recyclable bio-based PET beverage bottle using bio-based ethylene glycol as a raw material. However, terephthalic acid, another raw material used to make PET, is produced from the catalytic oxidation of paraxylene, a petroleum-based industrial feedstock, resulting in PET plastic products that contain only 30 percent plant-based content. Although the bio-based polyester raw material monomer succinic acid, which has been vigorously studied in recent years, has the potential to partially replace petroleum-based diacids, but because it cannot provide the same rigid aromatic benzene ring structure as terephthalic acid, it is largely The performance of corresponding polyester products is limited. Therefore, how to obtain polyester raw material dibasic acid with rigid ring structure from biomass is an important development direction in the field of polyester raw material research and development.

Studies in recent years have found that 2,5-furandicarboxylic acid is an ideal polyester raw material for replacing terephthalic acid. First, 2,5-furandicarboxylic acid has a rigid aromatic ring similar to terephthalic acid. structure; secondly, the carbon number of 2,5-furandicarboxylic acid is the same as that of glucose, and its aromaticity is weaker than that of benzene ring, so it is easier to degrade; more importantly, 2,5-furandicarboxylic acid is a kind that can be prepared from biomass from bio-based monomers. Based on the above characteristics, furandicarboxylic acid has attracted more and more attention from researchers and R&D departments of enterprises.

At present, the method for synthesizing 2,5-furandicarboxylic acid is mainly to oxidize 5-hydroxymethylfurfural. This method has been reported in a large number of documents and patents, but there are many problems. First, the raw material 5-hydroxymethylfurfural has disadvantages such as low reserves, difficult preparation, difficult separation, and instability, resulting in very expensive costs; second, when oxidizing 5-hydroxymethylfurfural to synthesize 2,5-furandicarboxylic acid , often requires the use of expensive noble metal catalysts, and the conversion rate is low. Therefore, the 5-hydroxymethylfurfural oxidation method is not yet suitable for large-scale industrial production, which also greatly limits the application of 2,5-furandicarboxylic acid and its polyester products.

Although some literatures or patents have recently reported a method for preparing 2,5-furandicarboxylic acid using the cheap bio-based raw material furancarboxylic acid as a raw material. For example, ChemSusChem2013, 6, 47-50 reported a method of using zinc acetate as a catalyst to catalyze furanic acid and carbon dioxide to prepare 2,5-furandicarboxylic acid through disproportionation reaction, but the 2,5-furandicarboxylic acid prepared by this method The selectivity of formic acid is poor. During the reaction, part of 2,3-furandicarboxylic acid and 2,4-furandicarboxylic acid are formed, and the pure product of 2,5-furandicarboxylic acid cannot be obtained. ARKIVOC, 2013, 405-412 reported a method of preparing 2,5-furandicarboxylic acid by feeding carbon dioxide into a tetrahydrofuran solution under normal pressure using furancarboxylic acid as a raw material and lithium diisopropylamide as a catalyst. The implementation of this method requires the use of a large amount of organic solvents, which has a great environmental pollution problem. In addition, the lithium diisopropylamide used in the reaction is expensive and unstable, and is not suitable for industrial production. There is also a document reporting a method for preparing 2,5-furandicarboxylic acid using furancarboxylic acid as a starting material and cesium carbonate as a catalyst under normal or pressurized carbon dioxide gas conditions. However, because the catalyst used in this method is high-cost cesium carbonate, it is also difficult to apply this method to industrial production.

Therefore, how to develop an efficient and cheap route for the preparation of 2,5-furandioic acid will be an important means of synthesizing biomass-derived bulk chemicals and high value-added polymer materials, and has great application prospects and potential , has become one of the focuses of many forward-looking researchers in the field.

Contents of the invention

In view of this, the technical problem to be solved in the present invention is to provide a kind of preparation method of 2,5-furandicarboxylic acid, particularly a kind of low-cost suitable for industrialization 2,5-furandicarboxylic acid preparation method, the present invention provides The catalysts and raw materials used in the preparation method are all cheap chemical products, which greatly reduces the reaction cost, and the process is simple and the reaction conditions are mild, which is an economical and environment-friendly preparation method suitable for large-scale industrial production.

The invention provides a kind of preparation method of 2,5-furandicarboxylic acid, comprising the following steps:

A) After neutralizing furancarboxylic acid, basic compound and water, furan formic acid salt is obtained;

B) Under the condition of carbon dioxide gas, after reacting the furan formic acid salt obtained in the above steps, the molten salt and the catalyst, 2,5-furandicarboxylic acid salt is obtained;

The melting point of the molten salt is less than or equal to 400°C;

The catalyst includes a metal salt catalyst and/or an organic base catalyst;

C) Acidifying the 2,5-furandicarboxylic acid salt obtained in the above steps to obtain 2,5-furandicarboxylic acid.

Preferably, the molten salt includes a single salt or a mixed salt;

The molten salt is sodium salt, or a mixed salt of sodium salt and potassium salt.

Preferably, the molten salt includes mixed molten salt of sodium nitrate and potassium nitrate, mixed molten salt of sodium nitrate and potassium nitrite, mixed molten salt of sodium nitrate and sodium nitrite, mixed molten salt of sodium nitrite and potassium nitrate Salt, mixed molten salt of sodium nitrite and potassium nitrite, mixed molten salt of potassium acetate and sodium acetate, mixed molten salt of potassium acetate and potassium formate, mixed molten salt of potassium acetate and sodium formate, mixture of sodium acetate and potassium formate Molten salt, mixed molten salt of sodium acetate and sodium formate, mixed molten salt of potassium formate and sodium formate, mixed molten salt of sodium bicarbonate and potassium bicarbonate, mixed molten salt of sodium hydroxide and potassium hydroxide, molten sodium nitrite and one or more of molten sodium formate;

The mass ratio of the mixed salt is (5-95): (95-5).

Preferably, the molten salt also includes other meltable salts and/or non-meltable salts;

The cation of the metal salt catalyst includes one or more of potassium ions, sodium ions, lithium ions and alkaline earth metal ions;

The anions of the metal salt catalyst include one or more of carbonate ions, phosphate ions, hydroxide ions, bicarbonate ions;

The organic base catalyst includes 1,8-diazabicycloundec-7-ene, methylamine, urea, ethylamine, ethanolamine, ethylenediamine, dimethylamine, trimethylamine, triethylamine, propylamine, Isopropylamine, 1,3-propylenediamine, 1,2-propylenediamine, tripropylamine, triethanolamine, butylamine, isobutylamine, tert-butylamine, hexylamine, octylamine, cyclohexylamine, triethylenediamine, tetra One of methylethylenediamine, aniline and its derivatives, benzylamine and its derivatives, pyridine and its derivatives, pyrimidine, 4-dimethylaminopyridine, potassium tert-butoxide, sodium hydride, sodium ethoxide, and sodium methoxide one or more kinds;

The furanic acid salts include furanic acid potassium salt and/or furanic acid sodium salt.

Preferably, the molar ratio of the furanic acid salt to the catalyst is 1: (0.5-50);

The ratio of the total mass of the furan formic acid salt and the catalyst to the mass of the molten salt is 1: (0.5-100).

Preferably, the reaction time is 1 to 24 hours;

The reaction pressure is 0.1-25MPa;

The reaction temperature is 220-400°C.

Preferably, the basic compound includes one or more of potassium hydroxide, sodium hydroxide, potassium carbonate and sodium carbonate;

A dehydration step is also included after the neutralization reaction.

Preferably, after the reaction, a post-treatment step is also included.

The specific steps of the post-processing are:

Add water to the reacted reaction system to mix, remove insoluble matter in the reaction system, and then decolorize.

Preferably, the decolorization comprises adsorption decolorization;

The acid used for acidification includes one or more of hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid and dilute nitric acid;

The pH value of the acidification is less than or equal to 3.0.

Preferably, the after-treatment step is also included after the acidification;

The post-treatment again includes one or more of separation, drying and recrystallization.

The invention provides a preparation method of 2,5-furandicarboxylic acid, which comprises the following steps: firstly neutralizing furan formic acid, basic compound and water to obtain furan formate; and then under the condition of carbon dioxide gas , reacting the furan formic acid salt obtained in the above steps, the molten salt and the catalyst to obtain 2,5-furandicarboxylic acid salt; the melting point of the molten salt is less than or equal to 400°C; the catalyst includes a metal salt catalyst And/or an organic base catalyst; finally, the 2,5-furandicarboxylic acid salt obtained in the above steps is acidified to obtain 2,5-furandicarboxylic acid. Compared with the prior art, the present invention aims at the disadvantages that the existing method for oxidatively synthesizing 2,5-furandicarboxylic acid from 5-hydroxymethylfurfural has high raw material prices, uses noble metal catalysts, and has low conversion rate. In view of the existing furan formic acid as raw material preparation method of 2,5-furandicarboxylic acid, there are poor selectivity, low purity, large pollution, especially with high-cost cesium carbonate as catalyst, although potassium carbonate and cesium carbonate can be mixed , but the large proportion of cesium carbonate also makes this method difficult to be used in industrialized production defects.

The inventive method of the present invention uses furan formic acid as a starting material, firstly prepares furan formate, and then uses cheap and easy-to-obtain conventional metal salts and/or organic bases as catalysts, and especially utilizes a single organic salt or inorganic salt with a low melting point. body or mixture as a molten salt to prepare 2,5-furandicarboxylic acid. The catalyst and molten salt used in the present invention are all cheap chemical products, which greatly reduces the reaction cost, and the process is simple and the reaction temperature is low. An economical and environment-friendly preparation method suitable for large-scale industrial production promotes the industrialization process of 2,5-furandicarboxylic acid.

Experimental results show that the 2,5-furandicarboxylic acid prepared by the invention has high purity and yield, the purity is over 99%, and the yield can reach over 70%.

Description of drawings

Figure 1 is the H NMR spectrum of pure 2,5-furandicarboxylic acid prepared in Example 1 of the present invention.

Detailed ways

In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the invention.

All raw materials in the present invention have no particular limitation on their sources, they can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

The purity of all raw materials in the present invention is not particularly limited, and the present invention preferably adopts analytical purity or conventional purity in the field of 2,5-furandicarboxylic acid synthesis.

The invention provides a kind of preparation method of 2,5-furandicarboxylic acid, comprising the following steps:

A) After neutralizing furancarboxylic acid, basic compound and water, furan formic acid salt is obtained;

B) Under the condition of carbon dioxide gas, after reacting the furan formic acid salt obtained in the above steps, the molten salt and the catalyst, 2,5-furandicarboxylic acid salt is obtained;

The melting point of the molten salt is less than or equal to 400°C;

The catalyst includes a metal salt catalyst and/or an organic base catalyst;

C) Acidifying the 2,5-furandicarboxylic acid salt obtained in the above steps to obtain 2,5-furandicarboxylic acid.

In the present invention, furan formic acid salt is obtained by neutralizing furan formic acid, basic compound and water.

The present invention has no particular limitation on the furan formic acid, the furan formic acid well known to those skilled in the art can be used, and those skilled in the art can prepare it according to conventional methods or purchase it from the market. The furan formic acid described in the present invention is preferably bio-based monomeric furancarboxylic acid.

The present invention is not particularly limited to the basic compound, and the conventional basic compound well known to those skilled in the art can be used. Those skilled in the art can select and adjust according to actual production conditions, quality control and product requirements. The basic compound preferably includes one or more of potassium hydroxide, sodium hydroxide, potassium carbonate and sodium carbonate, more preferably potassium hydroxide, sodium hydroxide, potassium carbonate or sodium carbonate.

The present invention has no special limitation on the amount of the furancarboxylic acid and the basic compound, and the conventional ratio well known to those skilled in the art can be used. Those skilled in the art can select and adjust according to actual production conditions, quality control and product requirements. The molar ratio of the furancarboxylic acid and the basic compound in the invention is preferably 1:(0.5-5), more preferably 1:(1.5-4), more preferably 1:(2.5-3).

The conditions of the neutralization reaction are not particularly limited, the conditions of the conventional neutralization reaction well known to those skilled in the art can be selected and adjusted by those skilled in the art according to actual production conditions, quality control and product requirements, the present invention The time for the neutralization reaction is preferably 6-20 h, more preferably 8-18 h, more preferably 10-16 h.

In the present invention, 2,5-furandicarboxylate is obtained after reacting the furan formic acid salt, molten salt and catalyst obtained in the above steps under the condition of carbon dioxide gas.

The present invention is not particularly limited to the molten salt, and the organic salts and/or inorganic salts with a low melting point well known to those skilled in the art can be selected and selected according to actual production conditions, quality control and product requirements. Adjustment, the melting point of the molten salt is less than or equal to 400°C, more preferably less than or equal to 350°C, more preferably less than or equal to 300°C. The preparation method provided by the present invention can allow the reaction to be carried out at low temperature, and has high product quality. The melting point of the molten salt described in the present invention can be less than or equal to 290°C, or less than or equal to 270°C, or less than or equal to 250°C. , or less than or equal to 230°C.

The molten salt of the present invention can be a single salt or a mixed salt, specifically preferably a sodium salt, or a mixed salt of a sodium salt and a potassium salt, more specifically preferably a mixed molten salt comprising sodium nitrate and potassium nitrate, sodium nitrate Mixed molten salt of potassium nitrite, mixed molten salt of sodium nitrate and sodium nitrite, mixed molten salt of sodium nitrite and potassium nitrate, mixed molten salt of sodium nitrite and potassium nitrite, mixture of potassium acetate and sodium acetate Molten salt, mixed molten salt of potassium acetate and potassium formate, mixed molten salt of potassium acetate and sodium formate, mixed molten salt of sodium acetate and potassium formate, mixed molten salt of sodium acetate and sodium formate, mixed molten salt of potassium formate and sodium formate, One or more of the mixed molten salt of sodium bicarbonate and potassium bicarbonate, the mixed molten salt of sodium hydroxide and potassium hydroxide, molten sodium nitrite and molten sodium formate, more preferably sodium nitrate and potassium nitrate Mixed molten salt, mixed molten salt of sodium nitrate and potassium nitrite, mixed molten salt of sodium nitrate and sodium nitrite, mixed molten salt of sodium nitrite and potassium nitrite, mixed molten salt of sodium nitrite and potassium nitrite, acetic acid Mixed molten salt of potassium and sodium acetate, mixed molten salt of potassium acetate and potassium formate, mixed molten salt of potassium acetate and sodium formate, mixed molten salt of sodium acetate and potassium formate, mixed molten salt of sodium acetate and sodium formate, potassium formate and Mixed molten salt of sodium formate, mixed molten salt of sodium bicarbonate and potassium bicarbonate, mixed molten salt of sodium hydroxide and potassium hydroxide, molten sodium nitrite or molten sodium formate.

The ratio of the mixed molten salt in the present invention is not particularly limited, and the conventional ratio well known to those skilled in the art can be used. Those skilled in the art can select and adjust according to actual production conditions, quality control and product requirements. The mass ratio of the mixed molten salt is preferably (5-95):(95-5), more preferably (25-75):(75-25), more preferably (45-55):(55-45).

In the molten salt described in the present invention, also include other fusible salts and/or infusible salts, more preferably trace other fusible salts and/or infusible salts, the present invention does not specifically limit, these traces of fusible salts And/or non-meltable salt also can be added in the salt of above-mentioned fusion of the present invention, forms the mixture of multiple salts, and the essence of its technical scheme is identical with the present invention, also can form the mixture of low melting point, these molten salts that add and /or the technical solution of infusible salt is also in the protection of the present invention.

The present invention does not have special restriction to the consumption of the salt of described fusion, those skilled in the art can select and adjust according to actual production situation, quality control and product requirement, the gross mass of furan formic acid salt of the present invention and catalyzer and described The mass ratio of molten salt is preferably 1:(0.5-100), more preferably 1:(1-80), more preferably 1:(2-50), more preferably 1:(3-20), More preferably, it is 1:(4-10), and specifically, it may be 1:(0.5-10).

In the molten salt of the present invention, also comprise other fusible salt and/or infusible salt, the present invention does not specifically limit, these fusible salts and/or infusible salt also can be added in the above-mentioned molten salt of the present invention, The essence of the technical solution for forming a mixture of various salts is the same as that of the present invention, and the technical solutions of adding these meltable salts and/or non-meltable salts are also included in the protection of the present invention.

The present invention has no special restrictions on the metal salt catalyst, and the conventional metal salt catalyst well known to those skilled in the art can be used. Those skilled in the art can select and adjust according to actual production conditions, quality control and product requirements. The present invention guarantees The reaction can be carried out at low temperature to further improve the quality of the product. The cation of the metal salt catalyst preferably includes one or more of potassium ions, sodium ions, lithium ions and alkaline earth metal ions, more preferably potassium ions, sodium ions ions, lithium ions, or alkaline earth metal ions. The anions of the metal salt catalyst preferably include one or more of carbonate ions, phosphate ions, hydroxide ions and bicarbonate ions, more preferably carbonate ions, phosphate ions, hydroxide ions or Bicarbonate ion.

The present invention has no special limitation to the organic base catalyst, and the conventional organic base catalyst well known to those skilled in the art can be used. Those skilled in the art can select and adjust according to actual production conditions, quality control and product requirements. The present invention guarantees The reaction can be carried out at low temperature to further improve the quality of the product. The organic base catalyst preferably includes 1,8-diazabicycloundec-7-ene, methylamine, urea, ethylamine, ethanolamine, ethylenediamine , dimethylamine, trimethylamine, triethylamine, propylamine, isopropylamine, 1,3-propylenediamine, 1,2-propylenediamine, tripropylamine, triethanolamine, butylamine, isobutylamine, tert-butylamine, hexylamine , octylamine, cyclohexylamine, triethylenediamine, tetramethylethylenediamine, aniline and its derivatives, benzylamine and its derivatives, pyridine and its derivatives, pyrimidine, 4-dimethylaminopyridine, tert-butyl One or more of potassium alkoxide, sodium hydride, sodium ethoxide and sodium methoxide, more preferably 1,8-diazabicycloundec-7-ene, methylamine, urea, ethylamine, ethanolamine, ethylamine Diamine, dimethylamine, trimethylamine, triethylamine, propylamine, isopropylamine, 1,3-propylenediamine, 1,2-propylenediamine, tripropylamine, triethanolamine, butylamine, isobutylamine, tert-butylamine, Hexylamine, octylamine, cyclohexylamine, triethylenediamine, tetramethylethylenediamine, aniline and its derivatives, benzylamine and its derivatives, pyridine and its derivatives, pyrimidine, 4-dimethylaminopyridine, Potassium tert-butoxide, sodium hydride, sodium ethoxide, or sodium methoxide.

The present invention is not particularly limited to the consumption of described catalyzer, those skilled in the art can select and adjust according to actual production situation, quality control and product requirement, and the mol ratio of described furoformic acid salt of the present invention and described catalyzer is preferably 1 : (0.5-50), more preferably 1: (1-40), more preferably 1: (2-20), more preferably 1: (2-20), more preferably 1: (3-10) , specifically can be 1: (0.5-5).

The present invention does not have special limitation to the temperature of described reaction, can get final product with the temperature of conventional this type of reaction well known to those skilled in the art, those skilled in the art can select and adjust according to actual production situation, quality control and product requirement, the present invention The reaction temperature is preferably 220-400°C, more preferably 250-350°C, more preferably 270-330°C, more preferably 290-310°C. The present invention reduces the reaction temperature by adopting molten salt and specific metal salt and/or organic base catalyst, enables the reaction to be carried out at low temperature, and has higher product quality, reduces production risk and energy consumption cost, The reaction temperature may be 220-290°C, 230-280°C, 240-270°C, or 250-260°C.

The present invention does not have special limitation to the pressure of described reaction, can get final product with the pressure of conventional this type of reaction well-known to those skilled in the art, and those skilled in the art can select and adjust according to actual production situation, quality control and product requirement, the present invention The pressure of the reaction is preferably 0.1-25 MPa, more preferably 1-20 MPa, more preferably 5-15 MPa.

The present invention does not have special limitation to the time of described reaction, can get final product with the conventional time of this type of reaction well known to those skilled in the art, those skilled in the art can select and adjust according to actual production situation, quality control and product requirement, the present invention The reaction time is preferably 1-24 hours, more preferably 5-20 hours, more preferably 10-15 hours.

In order to ensure the purity and yield of the final product, the present invention improves and optimizes the preparation process, and preferably also includes a post-processing step after the reaction.

The present invention has no particular limitation on the specific steps of the post-treatment, the post-treatment steps of this type of reaction well known to those skilled in the art can be selected and adjusted according to actual production conditions, quality control and product requirements , the specific steps of post-processing described in the present invention are preferably:

Add water to the reacted reaction system to mix, remove insoluble matter in the reaction system, and then decolorize.

More specifically, it can be:

After the reaction, a certain amount of water is added to the reaction system, the insoluble matter in the system is removed by filtration, and activated carbon is added to the filtrate for decolorization.

The invention provides a kind of furanic acid and carbon dioxide with cheap price as raw materials, industrial raw materials such as potassium carbonate as catalysts, potassium acetate, sodium acetate, etc. , Technology and method for preparing 2,5-furandicarboxylic acid. Considering from the cost point of view, the raw material used in the present invention is easy to prepare, low-cost furancarboxylic acid in industry, rather than the expensive 5-hydroxymethylfurfural used in traditional methods; in addition, the catalyst used in the present invention is price Cheap industrial raw material potassium carbonate, instead of expensive cesium-based catalysts, effectively solves the problem of high production cost of 2,5-furandicarboxylic acid at present, and invented a method for preparing 2,5-furandicarboxylic acid at low cost The method is of great significance for promoting the industrialization of 2,5-furandicarboxylic acid. From the perspective of green environmental protection and sustainable development, the raw material furancarboxylic acid used in the present invention can be derived from biological materials such as corn cobs, straws, etc., effectively realizing the conversion and utilization of waste biomass; in addition, the used in the present invention Another raw material, carbon dioxide, can be obtained from industrial waste gas, which is of great significance for reducing carbon dioxide emissions and alleviating the environmental problems caused by the current greenhouse effect.

Finally, in the present invention, the 2,5-furandicarboxylic acid salt obtained in the above steps is acidified to obtain 2,5-furandicarboxylic acid.

The present invention has no special restrictions on the specific steps and parameters of the acidification, and the conventional acidification steps and parameters well known to those skilled in the art can be used, and those skilled in the art can select and adjust according to actual production conditions, quality control and product requirements The acid used for acidification in the present invention preferably includes one or more of hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid and dilute nitric acid, more preferably hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid or dilute nitric acid. The pH value of the acidification is preferably less than or equal to 3.0, more preferably less than or equal to 2.5, more preferably less than or equal to 2.0.

In order to ensure the purity and yield of the final product, the present invention perfects and optimizes the preparation process, and preferably further includes another post-treatment step after the acidification.

The present invention is not particularly limited to the specific steps of the re-post-treatment, and the conventional post-treatment steps of this type of reaction well known to those skilled in the art can be used, and those skilled in the art can select according to actual production conditions, quality control and product requirements and adjustment, the post-treatment again in the present invention preferably includes one or more of separation, drying and recrystallization, more preferably separation, drying and recrystallization in sequence, specifically suction filtration separation, drying and thermal Water recrystallizes.

In order to ensure the purity and yield of the final product, the present invention improves and optimizes the preparation process, and the above-mentioned overall preparation process can specifically be:

In the present invention, the bio-based monomer furan formic acid is used as a raw material, and first neutralized with an aqueous alkali solution, wherein the alkali includes all inorganic or organic bases that can be neutralized with furan formic acid, preferably KOH, NaOH, K ₂ CO ₃ , Na ₂ CO ₃ , to prepare an aqueous solution of furan formate. Subsequently, the water solvent was evaporated to dryness under reduced pressure to obtain a solid powder of furan formate.

Pour the solid powder prepared above evenly into a high-temperature and high-pressure reactor, and add a catalyst equivalent to 0.5 to 5 times the equivalent of furanic acid as the raw material, wherein the cation of the metal salt catalyst can be potassium ion, sodium ion, lithium ion and alkaline earth metals. The anion of the metal salt catalyst may be carbonate, phosphate, hydroxide, bicarbonate and the like. Finally, molten salt whose mass is equivalent to 0.5 to 10 times the total mass of the raw material and the catalyst is added into the kettle.

After adding and mixing evenly, replace the air in the reactor with carbon dioxide for at least 3 times to remove the air and moisture in the system; then, carry out the reaction under a certain pressure and temperature. amount of water, filtered to remove insoluble matter in the system, the filtrate was decolorized by adding activated carbon, and acidified with hydrochloric acid, the obtained white solid was suction filtered and dried to obtain the product 2,5-furandicarboxylic acid, which was recrystallized with hot water to obtain 2,5 - Pure furandicarboxylic acid.

The present invention provides a low-cost industrial preparation method of 2,5-furandicarboxylic acid, using furan formate as the starting material, and using cheap and easily available conventional metal salts and/or organic bases as catalysts, especially using The monomer or mixture of organic salt or inorganic salt with low melting point is used as molten salt to prepare 2,5-furandicarboxylic acid. The raw materials selected in the present invention are low-cost bio-based monomer furan formic acid and carbon dioxide, which are not present. There is the expensive 5-hydroxymethylfurfural commonly used in the technology, and the cheap inorganic base is used as the catalyst to replace the expensive metal catalyst, such as metal cesium catalyst, which greatly reduces the preparation cost of the product; simultaneously the present invention Using cheap and less polluting inorganic molten salts instead of organic solvents, a completely green process for preparing 2,5-furandicarboxylic acid is realized; in addition, the preparation method and post-treatment method used are simple, and it is easy to realize 2,5-furandicarboxylic acid The large-scale industrial production of dicarboxylic acid has promoted the industrialization process of 2,5-furandicarboxylic acid. The present invention has simple overall process and low reaction temperature, is an economical and environment-friendly preparation method suitable for large-scale industrial production.

Experimental results show that the 2,5-furandicarboxylic acid prepared by the invention has high purity and yield, the purity is over 99%, and the yield can reach over 70%.

In order to further understand the present invention, a kind of preparation method of 2,5-furandicarboxylic acid provided by the present invention is described below in conjunction with the examples, but it should be understood that these examples are carried out under the premise of the technical solution of the present invention, given The detailed implementation and specific operation process are only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention, and the protection scope of the present invention is not limited to the following examples.

Example 1

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high-temperature and high-pressure reactor, add respectively the mixed molten salt 5.0g of the above-mentioned prepared potassium furoate, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate (the quality of potassium acetate and sodium acetate The ratio is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 280° C. for 24 hours, and the conversion rate was 95%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

The pure 2,5-furandicarboxylic acid prepared in Example 1 of the present invention was characterized, and the obtained 2,5-furandicarboxylic acid was subjected to nuclear magnetic resonance analysis using deuterated DMSO as a solvent.

Referring to Fig. 1, Fig. 1 is the H NMR spectrum of pure 2,5-furandicarboxylic acid prepared in Example 1 of the present invention. It can be seen from Fig. 1 that the pure product of 2,5-furandicarboxylic acid prepared by the present invention has no obvious impurity peaks, and the purity calculated by NMR is ≥99%.

The yield of pure 2,5-furandicarboxylic acid prepared in Example 1 of the present invention was 80%.

Example 2

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain gas flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 280° C. for 6 hours, and the conversion rate was 87%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

The pure 2,5-furandicarboxylic acid prepared in Example 2 of the present invention was characterized, and the obtained 2,5-furandicarboxylic acid was subjected to nuclear magnetic resonance analysis using deuterated DMSO as a solvent.

The results show that the pure 2,5-furandicarboxylic acid prepared by the present invention has no obvious impurity peaks, and the purity calculated by NMR is ≥99%.

The yield of pure 2,5-furandicarboxylic acid prepared in Example 2 of the present invention was 70%.

Example 3

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 280° C. for 3 hours, and the conversion rate was 77%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 4

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 280° C. for 1 hour, and the conversion rate was 42%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 5

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the prepared potassium furoate, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 6 hours, and the conversion rate was 73%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 6

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high-temperature and high-pressure reactor, add respectively the mixed molten salt 4.0g (mass ratio of potassium acetate and sodium acetate) of the prepared potassium furoate, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 6 hours, and the conversion rate was 71%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 7

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 7.4g (mass ratio of potassium acetate and sodium acetate) of the prepared potassium furoate, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 6 hours, and the conversion rate was 58%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 8

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 9.9g (mass ratio of potassium acetate and sodium acetate) of the prepared potassium furoate, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 6 hours, and the conversion rate was 53%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 9

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 9.9g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 6 hours, and the conversion rate was 53%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 10

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In the high-temperature and high-pressure reaction still of 100ml, add respectively the mixed molten salt 12g of above-mentioned prepared potassium salt of furoformate, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate (the mass ratio of potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 6 hours, and the conversion rate was 35%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 11

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In the high temperature and high pressure reactor of 100ml, add the mixed molten salt 15g (mass ratio of potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 6 hours, and the conversion rate was 27%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 12

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In the high-temperature and high-pressure reaction kettle of 100ml, add respectively the mixed molten salt 5g (mass ratio of potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 6 hours, and the conversion rate was 42%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 13

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In the high-temperature and high-pressure reactor of 100ml, add respectively the mixed molten salt 5g of above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 1.38g (10mmol), potassium acetate and sodium acetate (the mass ratio of potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 6 hours, and the conversion rate was 53%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 14

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In the high-temperature and high-pressure reaction kettle of 100ml, add respectively the mixed molten salt 5g of above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 2.76g (20mmol), potassium acetate and sodium acetate (the mass ratio of potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 6 hours, and the conversion rate was 42%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 15

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In the high-temperature and high-pressure reaction still of 100ml, add respectively the mixed molten salt 5g of above-mentioned prepared potassium salt of furoformate, anhydrous potassium carbonate 4.14g (30mmol), potassium acetate and sodium acetate (the mass ratio of potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 6 hours, and the conversion rate was 77%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 16

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In the high-temperature and high-pressure reaction kettle of 100ml, add respectively the mixed molten salt 5g (mass ratio of potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 6 hours, and the conversion rate was 72%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 17

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 250° C. for 6 hours, and the conversion rate was 26%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 18

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 260° C. for 6 hours, and the conversion rate was 41%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, vacuum dry, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid

Example 19

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 265° C. for 6 hours, and the conversion rate was 64%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, vacuum dry, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid

Example 20

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 275° C. for 6 hours, and the conversion rate was 82%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 21

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 285° C. for 6 hours, and the conversion rate was 91%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 22

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.1 MPa, and the reaction was carried out at 280° C. for 6 hours, and the conversion rate was 70%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 23

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 10 MPa, and the reaction was carried out at 280° C. for 6 hours, and the conversion rate was 89%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 24

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.4 MPa, and the reaction was carried out at 280° C. for 6 hours, and the conversion rate was 80%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 25

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high temperature and high pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium carbonate 3.45g (25mmol), potassium acetate and sodium acetate was 55:45). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 280° C. for 24 hours, and the conversion rate was 95%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

The pure 2,5-furandicarboxylic acid prepared in Example 25 of the present invention was characterized, and the obtained 2,5-furandicarboxylic acid was subjected to nuclear magnetic resonance analysis using deuterated DMSO as a solvent.

The results show that the pure 2,5-furandicarboxylic acid prepared by the present invention has no obvious impurity peaks, and the purity calculated by NMR is ≥99%.

The yield of pure 2,5-furandicarboxylic acid prepared in Example 2 of the present invention was 80%.

Example 26

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high-temperature and high-pressure reactor, add respectively the mixed molten salt 5.0g (the quality of potassium nitrate and sodium nitrite) of the above-mentioned prepared potassium salt of furoformate, anhydrous potassium carbonate 1.38g (10mmol), potassium acetate and sodium acetate. The ratio is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 24 hours, and the conversion rate was 63%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 27

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In the 100ml high-temperature and high-pressure reactor, add respectively the mixed molten salt 5.0g (the quality of potassium nitrite and sodium nitrate) of above-mentioned prepared potassium salt of furoformate, anhydrous potassium carbonate 1.38g (10mmol), potassium acetate and sodium acetate The ratio is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 24 hours, and the conversion rate was 60%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 28

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high-temperature and high-pressure reaction kettle, respectively add the prepared above-mentioned potassium furoate, 1.38g (10mmol) of anhydrous potassium carbonate, and 5.0g of sodium nitrite mixed molten salt of potassium acetate and sodium acetate. After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 280° C. for 24 hours, and the conversion rate was 83%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 29

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high-temperature and high-pressure reactor, add the above-mentioned prepared potassium furoate, 1.38g (10mmol) of anhydrous potassium carbonate, and 5.0g of sodium formate, a mixed molten salt of potassium acetate and sodium acetate, respectively. After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 24 hours, and the conversion rate was 80%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 30

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In a 100ml high-temperature and high-pressure reactor, add respectively the mixed molten salt 5.0g (mass ratio of potassium acetate and sodium acetate) of the above-mentioned prepared potassium salt of furanic acid, anhydrous potassium phosphate 2.12g (10mmol), potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 24 hours, and the conversion rate was 36%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 31

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In the high-temperature and high-pressure reactor of 100ml, add the mixed molten salt 5.0g of above-mentioned prepared potassium furoate, potassium hydroxide 0.56g (10mmol), potassium acetate and sodium acetate respectively (the mass ratio of potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain gas flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 24 hours, and the conversion rate was 20%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 32

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.7 g (5 mmol) of potassium carbonate, and 10 ml of water were sequentially added. The obtained clear potassium furanic acid salt solution was evaporated to dryness under reduced pressure to obtain a white solid powder of potassium furanic acid salt. In the high-temperature and high-pressure reactor of 100ml, add respectively the mixed molten salt 5.0g of above-mentioned prepared potassium furoate, sodium hydroxide 0.4g (10mmol), potassium acetate and sodium acetate (the mass ratio of potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain gas flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 270° C. for 24 hours, and the conversion rate was 20%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Example 33

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.54 g (5 mmol) of sodium carbonate, and 10 ml of water were sequentially added. The obtained clarified aqueous solution of sodium furanic acid was evaporated to dryness under reduced pressure to obtain a white solid powder of sodium furanic acid. In the high-temperature and high-pressure reactor of 100ml, add respectively the mixed molten salt 4.8g (mass ratio of potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 280° C. for 24 hours, and the conversion rate was 95%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

The pure 2,5-furandicarboxylic acid prepared in Example 25 of the present invention was characterized, and the obtained 2,5-furandicarboxylic acid was subjected to nuclear magnetic resonance analysis using deuterated DMSO as a solvent.

The results show that the pure 2,5-furandicarboxylic acid prepared by the present invention has no obvious impurity peaks, and the purity calculated by NMR is ≥99%.

The yield of pure 2,5-furandicarboxylic acid prepared in Example 33 of the present invention was 80%.

Example 34

Into a 100 ml flask, 1.12 g (10 mmol) of furancarboxylic acid, 0.54 g (5 mmol) of sodium carbonate, and 10 ml of water were sequentially added. The obtained clarified aqueous solution of sodium furanic acid was evaporated to dryness under reduced pressure to obtain a white solid powder of sodium furanic acid. In the high-temperature and high-pressure reactor of 100ml, add respectively the mixed molten salt 4.8g (mass ratio of potassium acetate and sodium acetate is 1:1). After the addition is complete, replace the air in the reactor with carbon dioxide. Then, under the condition of maintaining a certain air flow, the pressure of carbon dioxide was kept at 0.8 MPa, and the reaction was carried out at 275° C. for 24 hours, and the conversion rate was 93%.

After the reaction is over, add 100ml of deionized water to the reaction system to obtain a brown transparent solution, add 0.2g of activated carbon to the mother liquor, stir for 30 minutes at 50°C, and filter while it is hot. The resulting colorless aqueous solution is washed with hydrochloric acid Acidify until the pH value is about 2, a large amount of white precipitates are formed, filter under reduced pressure, dry in vacuum, and recrystallize with water to obtain pure 2,5-furandicarboxylic acid.

Above, a kind of low-cost industrial preparation method of 2,5-furandicarboxylic acid provided by the present invention has been introduced in detail. In this paper, specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above examples It is only used to help understand the method and its core idea of the present invention, including the best mode, and also to enable anyone skilled in the art to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims (10)

1. a preparation method of 2,5-furandicarboxylic acid, is characterized in that, comprises the following steps: A) After neutralizing furancarboxylic acid, basic compound and water, furan formic acid salt is obtained; B) Under the condition of carbon dioxide gas, after reacting the furan formic acid salt obtained in the above steps, the molten salt and the catalyst, 2,5-furandicarboxylic acid salt is obtained; The melting point of the molten salt is less than or equal to 400°C; The catalyst includes a metal salt catalyst and/or an organic base catalyst; C) Acidifying the 2,5-furandicarboxylic acid salt obtained in the above steps to obtain 2,5-furandicarboxylic acid. 2. preparation method according to claim 1, is characterized in that, the salt of described fusion comprises single salt or mixed salt; The molten salt is sodium salt, or a mixed salt of sodium salt and potassium salt. 3. preparation method according to claim 1, is characterized in that, the salt of described fusion comprises the mixed molten salt of sodium nitrate and potassium nitrate, the mixed molten salt of sodium nitrate and potassium nitrite, sodium nitrate and sodium nitrite Mixed molten salt, mixed molten salt of sodium nitrite and potassium nitrate, mixed molten salt of sodium nitrite and potassium nitrite, mixed molten salt of potassium acetate and sodium acetate, mixed molten salt of potassium acetate and potassium formate, potassium acetate and Mixed molten salt of sodium formate, mixed molten salt of sodium acetate and potassium formate, mixed molten salt of sodium acetate and sodium formate, mixed molten salt of potassium formate and sodium formate, mixed molten salt of sodium bicarbonate and potassium bicarbonate, sodium hydroxide and One or more of mixed molten salt of potassium hydroxide, molten sodium nitrite and molten sodium formate; The mass ratio of the mixed salt is (5-95): (95-5). 4. preparation method according to claim 3, is characterized in that, the salt of described fusion also comprises other fusible salt and/or infusible salt; The cation of the metal salt catalyst includes one or more of potassium ions, sodium ions, lithium ions and alkaline earth metal ions; The anions of the metal salt catalyst include one or more of carbonate ions, phosphate ions, hydroxide ions, bicarbonate ions; The organic base catalyst includes 1,8-diazabicycloundec-7-ene, methylamine, urea, ethylamine, ethanolamine, ethylenediamine, dimethylamine, trimethylamine, triethylamine, propylamine, Isopropylamine, 1,3-propylenediamine, 1,2-propylenediamine, tripropylamine, triethanolamine, butylamine, isobutylamine, tert-butylamine, hexylamine, octylamine, cyclohexylamine, triethylenediamine, tetra One of methylethylenediamine, aniline and its derivatives, benzylamine and its derivatives, pyridine and its derivatives, pyrimidine, 4-dimethylaminopyridine, potassium tert-butoxide, sodium hydride, sodium ethoxide, and sodium methoxide one or more kinds; The furanic acid salts include furanic acid potassium salt and/or furanic acid sodium salt. 5. The preparation method according to claim 1, characterized in that, the molar ratio of the furanic acid salt to the catalyst is 1:(0.5～50); The ratio of the total mass of the furan formic acid salt and the catalyst to the mass of the molten salt is 1: (0.5-100). 6. The preparation method according to claim 1, characterized in that, the reaction time is 1 to 24 hours; The reaction pressure is 0.1-25MPa; The reaction temperature is 220-400°C. 7. preparation method according to claim 1, is characterized in that, described alkaline compound comprises one or more in potassium hydroxide, sodium hydroxide, potassium carbonate and sodium carbonate; A dehydration step is also included after the neutralization reaction. 8. The preparation method according to any one of claims 1 to 6, characterized in that, after the reaction, a post-treatment step is also included; The specific steps of the post-processing are: Add water to the reacted reaction system to mix, remove insoluble matter in the reaction system, and then decolorize. 9. The preparation method according to claim 8, wherein the decolorization comprises adsorption decolorization; The acid used for acidification includes one or more of hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid and dilute nitric acid; The pH value of the acidification is less than or equal to 3.0. 10. The preparation method according to claim 1, characterized in that, after the acidification, further post-treatment steps are included; The post-treatment again includes one or more of separation, drying and recrystallization.