Method for preparing 2,5-furandicarboxylic acid from 5-hydroxymethylfurfural by means of co-oxidation

Abstract

A method for preparing 2,5-furandicarboxylic acid from 5-hydroxymethylfurfural by means of co-oxidation. The method comprises the following step: subjecting a reaction system containing 5-hydroxymethylfurfural, a co-oxidant, an oxidation catalyst and a reaction solvent to an oxidation reaction in an oxidizing gas atmosphere, so as to generate 2,5-furandicarboxylic acid, wherein the co-oxidant is one or more of acetaldehyde, paracetaldehyde and methyl ethyl ketone, and the reaction solvent comprises an acetic acid. In the method, by introducing the specific co-oxidant into the reaction system, the reaction for preparing 2,5-furandicarboxylic acid from 5-hydroxymethylfurfural by means of oxidation can be promoted, and while a higher conversion rate, a high yield and a high purity are ensured, the utilization of hydrobromic acid is reduced, or even avoided, thereby reducing corrosion to equipment.

Description

A method for preparing 2,5-furandicarboxylic acid by co-oxidation of 5-hydroxymethylfurfural TECHNICAL FIELD

[0001] The present application relates to the technical field of synthesis of 2,5-furandicarboxylic acid, and in particular to a method for preparing 2,5-furandicarboxylic acid by co-oxidation of 5-hydroxymethylfurfural. BACKGROUND

[0002] The emergence of synthetic polymer materials has promoted social progress and improved people's quality of life, but most of the current synthetic polymer materials rely on fossil resources. With the depletion of fossil resources and the increasing environmental problems, biobased synthetic polymer materials have attracted widespread attention. Biobased poly(ethylene 2,5-furandicarboxylate) (PEF) is considered to be a good alternative to petroleum-based poly(ethylene terephthalate) (PET) material.

[0003] The key to popularizing PEF lies in the development of cheap monomer 2,5-furandicarboxylic acid (2,5-Furandicarboxylic acid, abbreviated as: FDCA, CAS No.: 3238-40-2). Among the routes for preparing FDCA from biomass, dehydration of fructose to 5-hydroxymethylfurfural (HMF) and further oxidation to prepare FDCA is considered to be the most promising route for industrialization. In the process of fructose conversion to FDCA, HMF oxidation to FDCA is a key step.

[0004] In recent years, researchers have found that the Co / Mn / Br catalytic system has great development potential in the preparation of FDCA from HMF. It has been successfully applied to this reaction (such as patent CN202210493097.9), but it has the following problems: Co / Mn / Br catalytic HMF oxidation in acetic acid system is a chain free radical reaction principle, which requires a large amount of hydrobromic acid to provide bromine free radicals to initiate the reaction, which causes greater corrosion to the equipment. When the amount of hydrobromic acid is reduced, although the corrosion to the equipment can be reduced, the conversion rate, product yield and purity are too low.

[0005] SUMMARY

[0006] In order to solve the above technical problems, that is, in the method for preparing 2,5-furandicarboxylic acid by Co / Mn / Br catalysis, a large amount of hydrobromic acid is required, which causes greater corrosion to the equipment, the present application provides a method for preparing 2,5-furandicarboxylic acid by co-oxidation of 5-hydroxymethylfurfural. This method can reduce or even avoid the use of hydrobromic acid while ensuring high conversion rate, high conversion rate and high purity, thereby reducing the corrosion to the equipment.

[0007] The specific technical scheme of the present application is as follows:

[0008] A method for preparing 2,5-furan dicarboxylic acid by co-oxidation of 5-hydroxymethylfurfural, comprising the following steps: using a reaction system comprising 5-hydroxymethylfurfural, a co-oxidant, an oxidation catalyst, and a reaction solvent, and performing an oxidation reaction in an oxidation gas atmosphere to generate 2,5-furan dicarboxylic acid; the co-oxidant is one or more of acetaldehyde, paraldehyde, and methyl ethyl ketone; and the reaction solvent comprises acetic acid.

[0009] The present application introduces a co-oxidant, acetaldehyde, paraldehyde, or methyl ethyl ketone, into the reaction system for preparing FDCA from HMF, and in the process of the oxidation reaction, HMF is oxidized into FDCA, and the co-oxidant is oxidized into acetic acid. The introduction of the co-oxidant can promote the oxidation reaction of HMF→FDCA, and high conversion rate can be achieved without even using hydrobromic acid, thereby avoiding the corrosion of hydrobromic acid to the equipment; and the product after the reaction of the co-oxidant in the present application is acetic acid, which is easy to separate from FDCA, and when acetic acid is used as the reaction solvent, there is no need to separate it from the reaction solvent.

[0010] In addition, the existing Co / Mn / Br catalytic system requires a long oxidation initiation induction time and a high reaction temperature to achieve high conversion rate, and HMF has poor stability at high temperature, and is easy to be ring-opened to generate by-products such as acetic acid, propionic acid, and formic acid under acid catalysis, or to be dehydrated and condensed to form humin, thereby affecting the yield and purity of FDCA. However, after the introduction of the co-oxidant in the present application, the reaction temperature of HMF→FDCA can be reduced to ensure high conversion rate and reduce side reactions, thereby helping to achieve high yield and high purity.

[0011] Preferably, the co-oxidant is paraldehyde.

[0012] Preferably, the oxidation catalyst comprises a main catalyst; the main catalyst comprises cobalt elements and manganese elements.

[0013] Preferably, the oxidation catalyst further comprises an auxiliary catalyst; the auxiliary catalyst comprises one or more of the following metal elements: iron, zirconium, zinc, copper, and nickel.

[0014] Further, the main catalyst and the auxiliary catalyst are metal salts that are soluble in the reaction solvent.

[0015] Further, the main catalyst comprises divalent cobalt salts and divalent manganese salts that are soluble in the reaction solvent.

[0016] Further, the auxiliary catalyst comprises one or more of trivalent iron salts, tetravalent zirconium salts, divalent copper salts, divalent zinc salts, and divalent nickel salts that are soluble in the reaction solvent.

[0017] Further, the metal salt is one or more of acetate, halide, carbonate, sulfate, nitrate and phosphate.

[0018] As preferred, the amount of the oxidation catalyst added in the reaction system is 1000-6000 ppm in terms of metal element; the molar ratio between cobalt element and manganese element in the main catalyst is 1:(0.015-0.15).

[0019] Further, the amount of the oxidation catalyst added in the reaction system is 1500-5000 ppm in terms of metal element.

[0020] As preferred, the molar ratio between the main catalyst and the cocatalyst is 1:(0.07-0.10) in terms of metal element.

[0021] As preferred, the mass ratio between the co-oxidant and 5-hydroxymethylfurfural is (0.1-1):1, further preferably (0.3-0.8):1, and more further preferably (0.5-0.7):1.

[0022] In the reaction of preparing FDCA from HMF, due to the influence of humin impurities in HMF, more co-oxidant needs to be added to achieve higher FDCA yield and purity, but when the amount of co-oxidant is too large, the oxidation reaction will occur excessively, generating by-products. Based on this, the mass ratio between the co-oxidant and HMF is controlled within the above range, which can improve the FDCA yield and purity to a greater extent.

[0023] As preferred, the temperature of the oxidation reaction is 100-160℃, and the time is 10 min-1h.

[0024] Further, the temperature of the oxidation reaction is 110-150℃.

[0025] As preferred, the purity of 5-hydroxymethylfurfural is 50-99%.

[0026] HMF often contains a certain amount of humin impurities, which will cause the reduction of FDCA yield and purity. However, the present application can reduce the adverse effects of low HMF purity on FDCA yield and purity by introducing a co-oxidant in the reaction of HMF→FDCA.

[0027] As preferred, the oxidation gas is air or a mixed gas of air and CO2; the gas pressure of the oxidation gas atmosphere is 0.4-5 MPa.

[0028] Further, the oxidation gas is a mixed gas of air and CO2 with a volume ratio of 1:(0.125-4), and the further preferred volume ratio is 1:(0.15-2).

[0029] Further, the gas pressure of the oxidizing gas atmosphere is 0.5-4 MPa.

[0030] As a preference, the method specifically comprises the following steps: dissolving 5-hydroxymethylfurfural and a co-oxidant into a reaction solvent to form a reactant mixture; adding the reaction solvent and an oxidation catalyst into a reaction device, after warming, adding an acetic acid solution of 5-hydroxymethylfurfural and a co-oxidant under an oxidizing gas atmosphere, and then separating 2,5-furan dicarboxylic acid.

[0031] As a preference, the mass fraction of 5-hydroxymethylfurfural in the acetic acid solution of 5-hydroxymethylfurfural and a co-oxidant is 5-50%, and further preferably 10-40%.

[0032] As a preference, the method for separating 2,5-furan dicarboxylic acid is crystallization separation.

[0033] Compared with the prior art, the present application has the following advantages:

[0034] (1) The present application can promote the reaction of preparing FDCA from HMF by introducing a co-oxidant acetaldehyde, paraldehyde or methyl ethyl ketone into the reaction system, reduce or even avoid the use of hydrobromic acid, and thus reduce the corrosion to the equipment.

[0035] (2) The process of preparing FDCA from HMF of the present application is simple, has low requirements on the purity of raw materials, and has a wide range of applications. DETAILED DESCRIPTION

[0036] The present application will be further described below in conjunction with examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application, and the changes and advantages that can be thought of by those skilled in the art without departing from the spirit and scope of the present application are included in the present application, and the appended claims and any equivalents thereof are the protection scope of the present application.

[0037] General Examples

[0038] A method for preparing 2,5-furan dicarboxylic acid by co-oxidation of 5-hydroxymethylfurfural, comprising the following steps: using a reaction system comprising 5-hydroxymethylfurfural, a co-oxidant, an oxidation catalyst and a reaction solvent to perform an oxidation reaction in an oxidizing gas atmosphere to generate 2,5-furan dicarboxylic acid; the co-oxidant is one or more of acetaldehyde, paraldehyde and methyl ethyl ketone; and the reaction solvent comprises acetic acid.

[0039] As a specific embodiment, the mass ratio between the co-oxidant and 5-hydroxymethylfurfural is (0.1-1):1.

[0040] As a specific embodiment, the oxidation catalyst comprises a main catalyst; the main catalyst comprises cobalt element and manganese element; the oxidation catalyst is added in the reaction system in an amount of 1000-6000 ppm in terms of metal elements; the molar ratio between cobalt element and manganese element in the main catalyst is 1:(0.015-0.15).

[0041] As another specific embodiment, the oxidation catalyst comprises a main catalyst and an auxiliary catalyst; the main catalyst comprises cobalt element and manganese element; the auxiliary catalyst comprises one or more of the following metal elements: iron, zirconium, zinc, copper, nickel; the oxidation catalyst is added in the reaction system in an amount of 1000-6000 ppm in terms of metal elements; the molar ratio between the main catalyst and the auxiliary catalyst is 1:(0.07-0.10) in terms of metal elements; the molar ratio between cobalt element and manganese element in the main catalyst is 1:(0.015-0.15).

[0042] As a specific embodiment, the temperature of the oxidation reaction is 100-160℃, and the time is 10 min-1h.

[0043] As a specific embodiment, the purity of 5-hydroxymethylfurfural is 50-99%.

[0044] As a specific embodiment, the oxidation gas is air, or a mixed gas of air and CO2 in a volume ratio of 1:(0.125-4); the gas pressure of the oxidation gas atmosphere is 0.4-5 MPa.

[0045] As a specific embodiment, the method specifically comprises the following steps: adding a reaction solvent and an oxidation catalyst into a reaction device, and after warming, adding 5-hydroxymethylfurfural and an acetic acid solution of a co-oxidant (wherein the mass fraction of 5-hydroxymethylfurfural is 5-50%) under an oxidation gas atmosphere to carry out an oxidation reaction, and then separating 2,5-furan dicarboxylic acid. The method for separating 2,5-furan dicarboxylic acid can adopt crystallization separation.

[0046] Specific embodiments

[0047] The present application is described below through specific embodiments.

[0048] In the following specific embodiments, the detection and analysis methods used are specifically as follows:

[0049] (1) The specific method of HPLC-UV analysis detection is as follows:

[0050] HMF: Agilent 1260, column: Eclipse XDB-C18, column temperature: 40°C, UV detector, mobile phase: methanol / water (9:1, by volume), flow rate: 1 mL / min, detection wavelength: 283 nm.

[0051] FDCA: Agilent 1260, column: Eclipse XDB-C18, column temperature: 35°C, UV detector, mobile phase: trifluoroacetic acid (0.1% by mass) / methanol (2:3, by volume), flow rate: 1 mL / min, detection wavelength: 260 nm.

[0052] (2) The calculation formulae of the HMF conversion rate and the FDCA yield (molar yield) are as follows:

[0053] HMF conversion rate = molar amount of converted HMF / molar amount of added HMF x 100%;

[0054] FDCA yield = molar amount of generated FDCA / molar amount of added HMF x 100%;

[0055] The "molar amount of converted HMF" and the "molar amount of generated FDCA" are analyzed by high-performance liquid chromatography.

[0056] Examples 1 to 5: Effect of different co-oxidants on HMF oxidation

[0057] 2,5-Furandicarboxylic acid (FDCA) is prepared from 5-hydroxymethylfurfural (HMF) by the following steps:

[0058] In a 5-L reaction vessel, 1500 g of acetic acid and an oxidation catalyst are previously added, and after being warmed to the reaction temperature, a reactant mixture (i.e., an acetic acid solution of HMF and a co-oxidant) 1500 g is added under an oxidation gas atmosphere, and the oxidation reaction is performed at a feeding rate of 20 g / min for 75 min. After the reaction is completed, 2,5-furandicarboxylic acid is isolated by crystallization.

[0059] In Examples 1 to 5, the specific parameter settings and raw material selections are shown in Table 1 (the reaction time in Table 1 is counted from the completion of the addition of the reactant mixture). After 2,5-furandicarboxylic acid is prepared, it is analyzed and detected by high-performance liquid chromatography (HPLC-UV), and the conversion rate and the molar yield are calculated. The results are shown in Table 2.

[0060] Table 1: Parameter settings and raw material selections in Examples 1 to 5

[0061] Table 2: Experimental results in Examples 1 to 5

[0062] From the experimental results of Examples 1 to 5, it can be seen that:

[0063] Among acetaldehyde, paraldehyde and methyl ethyl ketone, the highest yield and purity of FDCA were obtained when paraldehyde was used as the co-oxidant, because the co-oxidant was first oxidized to form a peroxide in the acetic acid solvent, and the peroxide then changed the valence state of the metal elements in the catalyst through oxidation, promoting the oxidation of HMF. The structures of acetaldehyde and methyl ethyl ketone are similar, and the mechanism of forming peroxide is different from that of paraldehyde. The higher activity of paraldehyde is probably because the oxidation activity of the peroxide formed by paraldehyde is higher than that of acetaldehyde and methyl ethyl ketone.

[0064] Comparative Examples 1 to 3: Effect of not adding a co-oxidant on the oxidation of HMF

[0065] 2,5-Furandicarboxylic acid (FDCA) was prepared from 5-hydroxymethylfurfural (HMF) by the following steps:

[0066] In a 5L reaction kettle, acetic acid 1500g and an oxidation catalyst were pre-added, and after being warmed to the reaction temperature, HMF acetic acid solution 1500g was added under an oxidation gas atmosphere, and the oxidation reaction was carried out at a feeding rate of 20g / min for 75min. After the reaction was completed, 2,5-furandicarboxylic acid was separated by crystallization.

[0067] In Comparative Examples 1 to 3, the specific experimental parameters and raw material selection are shown in Table 3 (the reaction time in Table 3 is counted from the completion of the addition of HMF acetic acid solution). After 2,5-furandicarboxylic acid was prepared, it was analyzed and detected by high performance liquid chromatography HPLC-UV, and the conversion rate and molar yield were calculated, and the results are shown in Table 3.

[0068] Table 3 Parameter settings, raw material selection and experimental results of Comparative Examples 1 to 3

[0069] From the experimental results of Examples 1 to 5 and Comparative Examples 1 to 3, it can be seen that:

[0070] (1) By introducing co-oxidants acetaldehyde, paraldehyde or methyl ethyl ketone into the reaction system for preparing FDCA from HMF, the use of hydrobromic acid can be avoided, the reaction temperature can be reduced, and high yield and high purity can be ensured, while ensuring the conversion rate of HMF.

[0071] (2) The experimental results of Example 3 and Comparative Example 3 show that by introducing a co-oxidant, the adverse effects of low HMF purity on the yield and purity of FDCA can be reduced.

[0072] Examples 6 to 15: Effect of co-oxidant addition amount on the oxidation of HMF

[0073] 2,5-furan dicarboxylic acid (FDCA) is prepared from 5-hydroxymethylfurfural (HMF) by the following steps:

[0074] In a 5L reactor, 1500g of acetic acid and an oxidation catalyst are added in advance, and after the temperature is raised to the reaction temperature, a reactant mixture (i.e., an acetic acid solution of HMF and a co-oxidant) 1500g is added under an oxidation gas atmosphere, and the oxidation reaction is performed at a feeding rate of 20g / min for 75min. After the reaction is completed, 2,5-furan dicarboxylic acid is separated by crystallization.

[0075] In Examples 6 to 15, the specific experimental parameters and raw material selection are shown in Table 4 (the reaction time in Table 4 is counted from the completion of the addition of the reactant mixture). After 2,5-furan dicarboxylic acid is prepared, it is analyzed and detected using high performance liquid chromatography HPLC-UV, and the conversion rate and molar yield are calculated, and the results are shown in Table 5.

[0076] Table 4: Parameter settings and raw material selection for Examples 6 to 15

[0077] Table 5: Experimental results for Examples 6 to 15

[0078] According to the experimental results of Examples 6 to 15, it can be seen that:

[0079] (1) Within a certain range, by increasing the amount of co-oxidant, the yield and purity of FDCA can be improved while ensuring the conversion rate of HMF.

[0080] (2) When the amount of co-oxidant is too large, it will have an adverse effect on the yield and purity of FDCA, which is due to the excessive oxidation reaction caused by the excessive amount of co-oxidant, generating by-products.

[0081] Examples 16 to 21: Effect of HMF purity on HMF oxidation

[0082] 2,5-furan dicarboxylic acid (FDCA) is prepared from 5-hydroxymethylfurfural (HMF) by the following steps:

[0083] In a 5L reactor, 1500g of acetic acid and an oxidation catalyst are added in advance, and after the temperature is raised to the reaction temperature, a reactant mixture (i.e., an acetic acid solution of HMF and a co-oxidant) 1500g is added under an oxidation gas atmosphere, and the oxidation reaction is performed at a feeding rate of 20g / min for 75min. After the reaction is completed, 2,5-furan dicarboxylic acid is separated by crystallization.

[0084] In Examples 16 to 21, the specific experimental parameters and raw material selection are shown in Table 6 (the reaction time in Table 6 is counted from the completion of the addition of the reactant mixture). After the production of 2,5-furan dicarboxylic acid, the conversion rate and molar yield were calculated by analyzing and detecting using high performance liquid chromatography HPLC-UV, and the results are shown in Table 7.

[0085] Table 6: Parameter settings and raw material selection in Examples 16 to 21

[0086] Table 7: Experimental results in Examples 16 to 21

[0087] Examples 22 to 27: Effect of HMF concentration on HMF oxidation

[0088] 2,5-furan dicarboxylic acid (FDCA) is produced from 5-hydroxymethylfurfural (HMF) by the following steps:

[0089] In a 5L reactor, 1500g of acetic acid and an oxidation catalyst are pre-added, and after the temperature is raised to the reaction temperature, 1500g of a reactant mixture (i.e., an acetic acid solution of HMF and a co-oxidant) is added under an oxidation gas atmosphere, and the oxidation reaction is performed at a feeding rate of 20g / min for 75min, and after the reaction is completed, 2,5-furan dicarboxylic acid is separated by crystallization.

[0090] In Examples 22 to 27, the specific experimental parameters and raw material selection are shown in Table 8 (the reaction time in Table 8 is counted from the completion of the addition of the reactant mixture). After the production of 2,5-furan dicarboxylic acid, the conversion rate and molar yield were calculated by analyzing and detecting using high performance liquid chromatography HPLC-UV, and the results are shown in Table 9.

[0091] Table 8: Parameter settings and raw material selection in Examples 22 to 27

[0092] Table 9: Experimental results in Examples 22 to 27

[0093] According to the experimental results of Examples 22 to 27, it can be seen that:

[0094] By reducing the HMF concentration, the reaction temperature can be reduced while ensuring the conversion rate, thereby improving the yield and purity of FDCA.

[0095] Examples 28 to 33: Effect of a promoter on HMF oxidation

[0096] 2,5-furan dicarboxylic acid (FDCA) is produced from 5-hydroxymethylfurfural (HMF) by the following steps:

[0097] In a 5L reactor, 1500g of acetic acid and oxidation catalyst were added in advance, and after the temperature was raised to the reaction temperature, 1500g of the reactant mixture (i.e., the acetic acid solution of HMF and co-oxidant) was added under the atmosphere of oxidation gas, and the oxidation reaction was carried out at a feeding rate of 20g / min for 75min. After the reaction, 2,5-furan dicarboxylic acid was separated by crystallization.

[0098] In Examples 28-33, the specific experimental parameters and raw material selection are shown in Table 10 (the reaction time in Table 10 is counted from the completion of the addition of the reactant mixture). After 2,5-furan dicarboxylic acid was prepared, it was analyzed and detected by HPLC-UV, and the conversion rate and molar yield were calculated, and the results are shown in Table 11.

[0099] Table 10 Parameter settings and raw material selection of Examples 28-32

[0100] Table 11 Experimental results of Examples 28-33

[0101] Unless otherwise defined, all technical and scientific terms used in the present disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The raw materials and equipment used in the present disclosure are conventional raw materials and equipment in the art, and can be obtained from conventional commercial channels, unless otherwise specified. The methods used in the present disclosure are conventional methods in the art, unless otherwise specified.

[0102] The above description is only the preferred embodiments of the present disclosure, and does not limit the present disclosure in any way. Any simple modification, change and equivalent transformation of the above embodiments based on the technical essence of the present disclosure are still within the protection scope of the technical solution of the present disclosure.

Claims

1. A method for the co-oxidation of 5-hydroxymethylfurfural to 2,5-furan dicarboxylic acid, characterized in that, The method comprises the following steps: The method comprises the following steps:

2. The method of claim 1, wherein, The method comprises the following steps:

3. The method of claim 2, wherein, The oxidation catalyst comprises a main catalyst, and the main catalyst comprises cobalt and manganese.

4. The method according to claim 2 or 3, characterized in that, The oxidation catalyst further comprises an auxiliary catalyst, and the auxiliary catalyst comprises one or more of the following metal elements: iron, zirconium, zinc, copper and nickel.

5. The method of claim 1, wherein, The oxidation catalyst is added in an amount of 1000-6000 ppm in terms of metal elements in the reaction system, and the molar ratio between cobalt and manganese in the main catalyst is 1:(0.015-0.15).

6. The method of claim 1, wherein, The mass ratio between the co-oxidant and 5-hydroxymethylfurfural is (0.1-1):

1.

7. The method of claim 1, wherein, The oxidation reaction is carried out at a temperature of 100-160 DEG C for 10 min to 1 h.

8. The method of claim 1, wherein, The purity of 5-hydroxymethylfurfural is 50-99%.

9. The method of claim 1, wherein, The oxidation gas is air or a mixture of air and CO2, and the gas pressure of the oxidation gas atmosphere is 0.4-5 MPa. The method comprises the following steps:

10. The method of claim 9, wherein, The method comprises the following steps: The method comprises the following steps: The mass fraction of 5-hydroxymethylfurfural in the acetic acid solution of 5-hydroxymethylfurfural and the co-oxidant is 5-50%.

Images