Catalysts for the oxidation of 5-hydroxymethylfurfural to FDCA, their preparation methods and applications

Abstract

This invention discloses a catalyst for the preparation of FDCA from 5-hydroxymethylfurfural, its preparation method, and its application. The catalyst preparation method includes: mixing and calcining an organic compound containing hydroxyl or carboxyl groups with a soluble metal salt, wherein the soluble metal salt contains at least two of Mn, Co, Ni, Cu, Fe, and Ce, and the calcination temperature is 300℃-400℃. The preparation method is simple, the resulting catalyst is inexpensive, and it exhibits excellent catalytic performance in the preparation of FDCA from 5-hydroxymethylfurfural, achieving a high FDCA yield.

Description

Technical Field

[0001] This invention belongs to the field of biomass chemical engineering, specifically relating to a catalyst for the preparation of FDCA from 5-hydroxymethylfurfural, its preparation method, and its application. Background Technology

[0002] With the increasing prominence of environmental, energy, and climate issues, carbon emission reduction has become a focal point of global concern. Bio-based chemicals, produced through biomass conversion, offer significant carbon reduction benefits over their life cycle. 2,5-Furandicarboxylic acid (FDCA) is one of the most promising bio-based chemicals, with broad application prospects.

[0003] Currently, the main methods for synthesizing 2,5-furandicarboxylic acid (FDCA) from 5-hydroxymethylfurfural (HMF) include four types: biosynthesis, photocatalytic oxidation, electrocatalytic oxidation, and chemical catalytic oxidation. Among them, chemical catalytic oxidation is the earliest developed and most mature method, which includes homogeneous catalytic systems and heterogeneous catalytic systems.

[0004] Heterogeneous catalytic systems mainly include two categories: noble metal catalysts and non-noble metal catalysts. Noble metal catalysts used for the catalytic oxidation of HMF to FDCA are mainly composed of four noble metals: gold, platinum, palladium, and ruthenium. All of them have very good catalytic performance (FDCA yield reaches 95%-99%), and the conditions are mild, even under alkaline conditions. However, the cost of using noble metal catalysts is too high, making it difficult to promote their use in industrial applications.

[0005] Non-precious metal catalysts are mainly transition metals, such as manganese, cobalt, and nickel. Although many non-precious metal catalysts reported so far have good catalytic effects, their preparation processes are complex, making large-scale industrial production difficult, and the yield of FDCA is low. Summary of the Invention

[0006] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one object of this invention is to provide a catalyst for the preparation of FDCA from 5-hydroxymethylfurfural, a method for its preparation, and its application. The catalyst is low in cost, has a simple preparation process, exhibits excellent catalytic effect, and achieves a high FDCA yield.

[0007] The first aspect of this invention provides a method for preparing a catalyst for the catalytic oxidation of 5-hydroxymethylfurfural to FDCA, comprising: mixing and calcining an organic compound containing hydroxyl or carboxyl groups with a soluble metal salt; wherein the soluble metal salt contains at least two of Mn, Co, Ni, Cu, Fe and Ce; and wherein the calcination temperature is 300℃-400℃.

[0008] The inventors discovered that by mixing and calcining a soluble metal salt (containing at least two of Mn, Co, Ni, Cu, Fe, and Ce) with an organic compound containing hydroxyl or carboxyl groups, the soluble metal salt reacts with the organic compound during the mixing process to obtain an insoluble metal salt. Further calcination at 300℃-400℃ yields a metal oxide with lattice defects and numerous oxygen vacancies. When the calcination temperature is below 300℃, a metal oxide crystal form favorable for the catalytic oxidation of HMF to FDCA cannot be obtained, and the resulting solid material does not truly begin to decompose at this temperature, thus hindering catalytic oxidation. When the temperature is above 400℃, the crystal form of the catalyst obtained after calcination changes; although it can still catalyze the oxidation of HMF, the effect is significantly reduced. Therefore, high-temperature calcination at 300℃-400℃ can yield a metal oxide with lattice defects and numerous oxygen vacancies. The metal oxide has a spinel-type crystal form, MnCo₂O₄.₅, which possesses numerous lattice defects and oxygen vacancies, enhancing the catalytic effect of oxygen oxidation of HMF to FDCA. Furthermore, using at least two soluble metal salts to prepare the catalyst results in a catalyst with a larger specific surface area and pore size, facilitating electron transfer, increasing oxygen mobility, and more readily generating lattice oxygen and oxygen vacancies. The d-orbital electronic structure of the transition metals endows them with excellent catalytic activity, providing effective electron transfer and promoting oxygen molecule activation, thereby achieving better molecular oxygen activation efficiency and catalytic HMF oxidation conversion. Thus, a low-cost, simple-to-prepare catalyst with excellent catalytic effect and high FDCA yield is obtained.

[0009] In addition, the catalyst preparation method for the preparation of FDCA from 5-hydroxymethylfurfural according to the present invention also has the following technical features:

[0010] In some embodiments of the present invention, the organic compound containing hydroxyl or carboxyl groups includes at least one of glucose, fructose, citric acid, lactic acid, tartaric acid, malonic acid, succinic acid, and oxalic acid. Adding organic compounds facilitates the formation of insoluble metal salts and regulates oxygen vacancies and lattice oxygen structure, thereby improving the performance of the catalyst.

[0011] In some embodiments of the present invention, the organic compound containing hydroxyl or carboxyl groups includes succinic acid or oxalic acid. This further improves the performance of the catalyst.

[0012] In some embodiments of the present invention, the soluble metal salt includes at least one selected from nitrates, acetates, and sulfates. This results in a catalyst with excellent catalytic performance and high FDCA yield.

[0013] In some embodiments of the present invention, the soluble metal salt contains Mn and Co. This results in a better catalytic effect, improving HMF conversion and FDCA yield.

[0014] In some embodiments of the present invention, the molar ratio of Mn to Co is 1-10:1-10. This further improves the catalytic effect and enhances the HMF conversion and FDCA yield.

[0015] In some embodiments of the present invention, the molar ratio of the organic compound containing hydroxyl or carboxyl groups to the soluble metal salt is 1-10:1-10. This facilitates the further formation of the insoluble metal salt and the regulation of oxygen vacancies and lattice oxygen structure, thereby further improving the performance of the catalyst.

[0016] In some embodiments of the present invention, the mixing conditions include: a mixing time of 6 h to 24 h; and / or a mixing temperature of 25 °C to 40 °C. This results in the formation of a uniform mixture and insoluble metal salts with consistent particle size.

[0017] In some embodiments of the present invention, the calcination time is 1-6 hours. This forms a catalytically active metal oxide, which in turn activates molecular oxygen to catalyze the oxidation of HMF to FDCA.

[0018] A second aspect of this invention provides a catalyst for the preparation of FDCA from 5-hydroxymethylfurfural, said catalyst comprising a catalyst prepared by any of the methods described above. Therefore, the catalyst is low in cost, simple in preparation process, exhibits excellent catalytic effect, and achieves a high FDCA yield.

[0019] A third aspect of this invention provides a method for preparing FDCA from 5-hydroxymethylfurfural, comprising: mixing 5-hydroxymethylfurfural with a catalyst to prepare FDCA, wherein the catalyst includes a catalyst prepared by any one of the methods described above or a catalyst as described above. Therefore, the method has a simple preparation process, high HMF conversion rate, and high FDCA yield.

[0020] In some embodiments of the present invention, the method includes: (1) mixing 5-hydroxymethylfurfural, an inorganic base, an oxidant, and a catalyst to react and obtain a reaction mixture; (2) separating the reaction mixture into solid and liquid components to obtain a solid substance and a filtrate; and (3) treating the filtrate to obtain an FDCA product. Therefore, the method for preparing FDCA from 5-hydroxymethylfurfural has a simple preparation process, high HMF conversion rate, and high FDCA yield.

[0021] In addition, the method for preparing FDCA from 5-hydroxymethylfurfural according to the present invention also has the following technical features:

[0022] In some embodiments of the present invention, in the method for preparing FDCA from 5-hydroxymethylfurfural, the concentration of 5-hydroxymethylfurfural in step (1) is 0.1 mol / L-2 mol / L. Therefore, the method for preparing FDCA from 5-hydroxymethylfurfural has a high HMF conversion rate and a high FDCA yield.

[0023] In some embodiments of the present invention, in a method for preparing FDCA from 5-hydroxymethylfurfural, the inorganic base in step (1) contains at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. Therefore, the method for preparing FDCA from 5-hydroxymethylfurfural has a high HMF conversion rate and a high FDCA yield.

[0024] In some embodiments of the present invention, in the method for preparing FDCA from 5-hydroxymethylfurfural, the concentration of the inorganic base in step (1) is 0.001 mol / L to 4 mol / L. This results in a higher FDCA yield.

[0025] In some embodiments of the present invention, in a method for preparing FDCA from 5-hydroxymethylfurfural, the oxidant in step (1) is air or oxygen, the reaction pressure is 0.1 MPa-5 MPa; and / or, the reaction temperature is 20℃-170℃; and / or, the reaction time is 1h-10h. This allows for a higher FDCA yield.

[0026] In some embodiments of the present invention, in the method for preparing FDCA from 5-hydroxymethylfurfural, the mass ratio of 5-hydroxymethylfurfural to catalyst in step (1) is 1-10:1-10. Therefore, the method exhibits excellent catalytic effect, high HMF conversion rate, and high FDCA yield.

[0027] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0029] Figure 1 This is a schematic flowchart illustrating a method for preparing a catalyst for the production of FDCA from 5-hydroxymethylfurfural according to one embodiment of the present invention.

[0030] Figure 2 This is a schematic flowchart of a method for preparing FDCA from 5-hydroxymethylfurfural according to one embodiment of the present invention.

[0031] Figure labels: 1-mixer; 2-calcining furnace; 3-oxidation reactor; 4-separation and purification unit. Detailed Implementation

[0032] The embodiments of the present invention are described in detail below, and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0033] The first aspect of this invention provides a method for preparing a catalyst for the preparation of FDCA from 5-hydroxymethylfurfural, comprising: mixing and calcining an organic compound containing a hydroxyl or carboxyl group with a soluble metal salt; wherein the soluble metal salt contains at least two of Mn, Co, Ni, Cu, Fe and Ce; and wherein the calcination temperature is 300℃-400℃.

[0034] The inventors discovered that by mixing and calcining a soluble metal salt (containing at least two of Mn, Co, Ni, Cu, Fe, and Ce) with an organic compound containing hydroxyl or carboxyl groups, the soluble metal salt reacts with the organic compound during the mixing process to obtain an insoluble metal salt. Further calcination at 300℃-400℃ yields a metal oxide with lattice defects and numerous oxygen vacancies. When the calcination temperature is below 300℃, a metal oxide crystal form favorable for the catalytic oxidation of HMF to FDCA cannot be obtained, and the resulting solid material does not truly begin to decompose at this temperature, thus hindering catalytic oxidation. When the temperature is above 400℃, the crystal form of the catalyst obtained after calcination changes; although it can still catalyze the oxidation of HMF, the effect is significantly reduced. Therefore, high-temperature calcination at 300℃-400℃ can yield a metal oxide with lattice defects and numerous oxygen vacancies. The metal oxide has a spinel-type crystal form, MnCo₂O₄.₅, which possesses numerous lattice defects and oxygen vacancies, enhancing the catalytic effect of oxygen oxidation of HMF to FDCA. Furthermore, using at least two soluble metal salts to prepare the catalyst results in a catalyst with a larger specific surface area and pore size, facilitating electron transfer, increasing oxygen mobility, and more readily generating lattice oxygen and oxygen vacancies. The d-orbital electronic structure of the transition metals endows them with excellent catalytic activity, providing effective electron transfer and promoting oxygen molecule activation, thereby achieving better molecular oxygen activation efficiency and catalytic HMF oxidation conversion. Thus, a low-cost, simple-to-prepare catalyst with excellent catalytic effect and high FDCA yield is obtained.

[0035] According to embodiments of the present invention, the mixing of the organic compound containing hydroxyl or carboxyl groups with the soluble metal salt is carried out under solvent-assisted conditions. The solvent includes at least one of water, methanol, and ethanol. By using a solvent, the organic compound containing hydroxyl or carboxyl groups and the soluble metal salt can be better dispersed, resulting in a more uniform mixture and a precipitate with a more uniform particle size, thereby improving the performance of the catalyst.

[0036] It should be noted that there is no particular limitation on the method of mixing organic compounds containing hydroxyl or carboxyl groups with soluble metal salts as described in this invention. As long as a uniform mixture and a precipitate with uniform particle size can be formed, it is acceptable. Those skilled in the art can choose according to actual needs.

[0037] For example, in some embodiments of the present invention, the mixing of the metal salt and the organic matter is carried out by dissolving the organic matter containing hydroxyl or carboxyl groups and the soluble metal salt in a solvent and then adding them dropwise.

[0038] For example, in some embodiments of the present invention, metal salts and organic substances dissolved in a solvent can be continuously mixed via a microchannel reactor to form a uniform mixture and a precipitate with uniform particle size.

[0039] In some embodiments of the present invention, the calcination is carried out after filtering and drying the solid material produced by mixing.

[0040] It should be noted that the method of filtering and drying the solid material before calcination described in this invention is a conventional technique in the field, and those skilled in the art can choose it according to actual needs.

[0041] In some embodiments of the present invention, the organic compound containing hydroxyl or carboxyl groups includes at least one of glucose, fructose, citric acid, lactic acid, tartaric acid, malonic acid, succinic acid, and oxalic acid. Adding organic compounds can improve the pore structure properties of the catalyst, such as specific surface area and total pore volume. It can also promote the reduction of some metal oxides during calcination, forming abundant low-valence metal ions, thereby promoting the formation of more oxygen vacancies, catalytic oxidation of HMF, and improving reactivity.

[0042] In some embodiments of the present invention, the organic compound containing hydroxyl or carboxyl groups includes succinic acid or oxalic acid. This further improves the performance of the catalyst.

[0043] In some embodiments of the present invention, the soluble metal salt includes at least one selected from nitrates, acetates, and sulfates. This results in a catalyst with excellent catalytic performance and high FDCA yield.

[0044] In some embodiments of the present invention, the soluble metal salt contains Mn and Co. On the one hand, both manganese and cobalt are transition metals, and their d-orbital electronic structures give them good catalytic activity, enabling efficient electron transfer and promoting the activation of oxygen molecules to achieve better molecular oxygen activation efficiency and catalytic HMF oxidation conversion. On the other hand, the synergistic effect of manganese and cobalt makes it easier to adsorb substrates and oxidants, while forming abundant oxygen vacancies and lattice oxygen, promoting the adsorption and activation process of HMF and oxidants, thereby enabling efficient catalytic oxidation of HMF. In some embodiments of the present invention, the molar ratio of Mn to Co is 1-10:1-10. For example, the molar ratio of Mn to Co can be 1:1, 1:5, 1:10, 10:1, 10:5, etc. Therefore, by controlling the molar ratio of Mn to Co within this range, the oxygen mobility of the corresponding catalyst can be affected, further improving the catalytic effect and further increasing the HMF conversion rate and FDCA yield.

[0045] In some embodiments of the present invention, the molar ratio of the organic compound containing hydroxyl or carboxyl groups to the soluble metal salt is 1-10:1-10, for example, it can be 1:1, 1:5, 1:10, 10:1, 10:5, etc. This facilitates further control of oxygen vacancies and lattice oxygen structure, thereby further improving the performance of the catalyst.

[0046] In some embodiments of the present invention, the mixing conditions include: a mixing time of 6h-24h; and / or a mixing temperature of 25℃-40℃. For example, the mixing time can be 6h, 10h, 14h, 18h, 24h, etc. For example, the mixing temperature can be 25℃, 30℃, 35℃, 40℃, etc. This results in the formation of a uniform mixture and insoluble metal salts with consistent particle size.

[0047] In some embodiments of the present invention, the calcination time is 1-6 hours. For example, the calcination time can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, etc. This forms a catalytically active metal oxide, which in turn activates molecular oxygen to catalyze the oxidation of HMF to FDCA.

[0048] A second aspect of this invention provides a catalyst for the preparation of FDCA from 5-hydroxymethylfurfural, said catalyst comprising a catalyst prepared by any of the methods described above. Therefore, the catalyst is low in cost, simple in preparation process, exhibits excellent catalytic effect, and achieves a high FDCA yield.

[0049] A third aspect of this invention provides a method for preparing FDCA from 5-hydroxymethylfurfural, comprising: mixing 5-hydroxymethylfurfural with a catalyst to prepare FDCA, wherein the catalyst includes the catalyst prepared by the method described in the first aspect above or the catalyst described in the second aspect above. Therefore, the method has a simple preparation process, high HMF conversion rate, and high FDCA yield.

[0050] In some embodiments of the present invention, the method for preparing FDCA from 5-hydroxymethylfurfural is described in the appendix. Figure 1 ,include:

[0051] S100: A mixture of 5-hydroxymethylfurfural, inorganic base, oxidant, and catalyst is reacted.

[0052] In this step, 5-hydroxymethylfurfural, an inorganic base, an oxidant, and a catalyst are mixed and reacted. Under the action of the catalyst, 5-hydroxymethylfurfural is oxidized by the oxidant, forming intermediate products 5-hydroxymethyl-2-furanic acid and 5-formyl-2-furanic acid, and finally forming the product 2,5-furandicarboxylic acid.

[0053] In some embodiments of the present invention, in S100, the concentration of 5-hydroxymethylfurfural is 0.1 mol / L to 2 mol / L. For example, the concentration of 5-hydroxymethylfurfural can be 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, etc. Therefore, the method for preparing FDCA from 5-hydroxymethylfurfural has a high HMF conversion rate and a high FDCA yield.

[0054] In some embodiments of the present invention, in S100, the inorganic base contains at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. Therefore, the method for preparing FDCA from 5-hydroxymethylfurfural has a high HMF conversion rate and a high FDCA yield.

[0055] In some embodiments of the present invention, in S100, the concentration of the inorganic base is 0.001 mol / L to 4 mol / L. For example, the concentration of the inorganic base can be 0.001 mol / L, 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, 2.0 mol / L, 3.0 mol / L, 4.0 mol / L, etc. This results in a higher FDCA yield.

[0056] In some embodiments of the present invention, in S100, the oxidant is air or oxygen, the reaction pressure is 0.1 MPa-5 MPa; and / or, the reaction temperature is 20°C-170°C; and / or, the reaction time is 1 h-10 h. Increasing the pressure of air or oxygen is beneficial to the oxidation reaction, thereby achieving a higher FDCA yield within the operating parameter range provided by the present invention.

[0057] In some embodiments of the present invention, in S100, the mass ratio of 5-hydroxymethylfurfural to the catalyst is 1-10:1-10. For example, the mass ratio of 5-hydroxymethylfurfural to the catalyst can be 1:1, 1:5, 1:10, 10:1, 10:5, etc. Therefore, the method exhibits excellent catalytic effect, high HMF conversion, and high FDCA yield.

[0058] S200: Separate the reaction mixture into solid and liquid phases.

[0059] In this step, the reaction mixture is subjected to solid-liquid separation to obtain solid substances and filtrate.

[0060] S300: Process the filtrate.

[0061] In this step, the filtrate is processed to obtain the FDCA product. Specifically, the filtrate is processed by decolorization, acidification, filtration, washing, and recrystallization. It should be noted that the methods of decolorization, acidification, filtration, washing, and recrystallization of the filtrate described in this invention are conventional techniques in the art, and those skilled in the art can choose according to actual needs.

[0062] Therefore, the method for preparing FDCA from 5-hydroxymethylfurfural is simple, has a high HMF conversion rate, and a high FDCA yield.

[0063] One embodiment of the present invention is as follows, with reference to the appendix. Figure 2 A soluble metal salt and an organic compound containing hydroxyl or carboxyl groups are added to mixer 1, and the resulting solid mixture is calcined in calcining furnace 2 to obtain a catalyst. In oxidation reactor 3, 5-hydroxymethylfurfural, an inorganic base, an oxidant, and the catalyst are mixed and reacted, and FDCA is obtained after separation and purification in separator 4.

[0064] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0065] Preparation Example

[0066] This invention illustrates the preparation method of the catalyst for the preparation of FDCA from 5-hydroxymethylfurfural.

[0067] Preparation Example 1

[0068] 2 mmol of manganese nitrate, 8 mmol of cobalt nitrate, and 7.5 mmol of oxalic acid were added to ethanol, and the mixture was left to stand for 24 h. The resulting solid mixture was then calcined at 300 °C for 3 h to obtain a catalyst denoted as Mn-Co. The molar ratio of manganese to cobalt was 0.25:1, and the molar ratio of oxalic acid to the metal salt was 0.75:1.

[0069] Preparation Example 2

[0070] Preparation Example 2 was carried out in the same manner as Preparation Example 1, except that 7.5 mmol of oxalic acid in Preparation Example 1 was replaced with 7.5 mmol of tartaric acid, 7.5 mmol of malonic acid, and 7.5 mmol of succinic acid, respectively. The resulting catalysts were denoted as Mn / Co-1, Mn / Co-2, and Mn / Co-3, respectively. The molar ratio of manganese to cobalt was 0.25:1, and the molar ratio of oxalic acid to metal salt was 0.75:1.

[0071] Preparation Example 3

[0072] Preparation Example 3 was carried out in the same manner as Preparation Example 1, except that the molar ratio of manganese to cobalt in Preparation Example 1 was changed to 3:7, 4:6, 5:5, and 6:4, respectively. The molar ratio of oxalic acid to the metal salt was 0.75:1, and the resulting catalysts were designated as Mn-Co-37, Mn-Co-46, Mn-Co-55, and Mn-Co-64, respectively.

[0073] Preparation Example 4

[0074] 4 mmol of manganese nitrate, 6 mmol of cobalt nitrate, and 7.5 mmol of oxalic acid were added to 20 ml of ethanol. After mixing and standing for 24 h, the resulting solid mixture was calcined at 300 °C for 2 h. The resulting catalyst was denoted as Mn-Co-300. The molar ratio of manganese to cobalt was 4:6, and the molar ratio of oxalic acid to the metal salt was 0.75:1.

[0075] 4 mmol of manganese nitrate, 6 mmol of cobalt nitrate, and 7.5 mmol of oxalic acid were added to 20 ml of ethanol. After mixing and standing for 24 h, the resulting solid mixture was calcined at 400 °C for 2 h. The resulting catalyst was denoted as Mn-Co-400. The molar ratio of manganese to cobalt was 4:6, and the molar ratio of oxalic acid to the metal salt was 0.75:1.

[0076] Preparation Example 5

[0077] 4 mmol of manganese nitrate, 6 mmol of cobalt nitrate, and 7.5 mmol of oxalic acid were added to 20 ml of ethanol. After mixing and standing for 24 h, the resulting solid mixture was calcined at 300 °C for 2 h. The resulting catalyst was denoted as Mn-Co-0.75. The molar ratio of manganese to cobalt was 4:6, and the molar ratio of oxalic acid to the metal salt was 0.75:1.

[0078] The preparation method based on catalyst Mn-Co-0.75 differs in that the 7.5 mmol oxalic acid in Mn-Co-0.75 is replaced with 3 mmol oxalic acid, 5 mmol oxalic acid, 10 mmol oxalic acid, and 20 mmol oxalic acid, respectively. The resulting catalysts are designated as Mn-Co-0.3, Mn-Co-0.5, Mn-Co-1.0, and Mn-Co-2.0, respectively. The molar ratio of manganese to cobalt is 4:6, and the molar ratios of oxalic acid to metal salt are 0.3:1, 0.5:1, 1.0:1, and 2.0:1, respectively.

[0079] Preparation Example 6

[0080] Preparation Example 6 was carried out in the same manner as Preparation Example 1, except that the manganese nitrate and cobalt nitrate in Preparation Example 1 were replaced with manganese nitrate and nickel nitrate, manganese nitrate and iron nitrate, manganese nitrate and cerium nitrate, copper nitrate and cobalt nitrate, and manganese nitrate and cobalt nitrate, respectively, resulting in catalysts denoted as Mn-Ni, Mn-Fe, Mn-Ce, Cu-Co, and Mn-Co. The molar ratio of Mn-Ni, Mn-Fe, Mn-Ce, Cu-Co, and Mn-Co was 0.25:1, and the molar ratio of oxalic acid to the metal salt was 0.75:1.

[0081] Example

[0082] This invention is used to illustrate a method for preparing FDCA from 5-hydroxymethylfurfural using the catalyst described in this invention.

[0083] In the following examples, the HMF conversion rate and FDCA yield were calculated using the following formulas:

[0084] HMF conversion rate (%) = (1 - molar amount of HMF in the product / initial molar amount of HMF) × 100%

[0085] FDCA yield (%) = (Molar amount of FDCA in the product / Initial molar amount of HMF) × 100%

[0086] Example 1

[0087] 1 mmol of 5-hydroxymethylfurfural, 2 mmol of sodium bicarbonate, and 20 ml of water were added to a 70 ml high-pressure reactor. 100 mg of Mn-Co catalyst was added, and the reactor was sealed. Oxygen was introduced at 1.6 MPa, and the mixture was heated to 140 °C with a stirring rate of 500 rpm and maintained for 8 hours. After the reaction was completed, the mixture was cooled to room temperature, and samples were taken for analysis. The results showed that the Mn-Co catalyst achieved a 100% HMF conversion and an 89.06% FDCA yield.

[0088] Example 2

[0089] Example 2 was conducted in the same manner as Example 1, except that the 100 mg Mn-Co catalyst in Example 1 was replaced with 100 mg Mn-Co-1, 100 mg Mn-Co-2, and 100 mg Mn-Co-3, respectively. After the reaction was completed, the mixture was cooled to room temperature and samples were taken for analysis. The results are listed in Table 1. It can be seen that the catalyst containing Mn-Co and oxalic acid has a 100% HMF conversion and an 84.73% FDCA yield.

[0090] Table 1. Detection results of catalysts with different organic compounds.

[0091] Mn-Co-1 100.00 53.05 Mn-Co-2 100.00 56.98 Mn-Co-3 100.00 84.73

[0092] Example 3

[0093] Example 3 was conducted in the same manner as Example 1, except that the Mn-Co catalyst in Example 1 was replaced with Mn-Co-37, Mn-Co-46, Mn-Co-55, and Mn-Co-64, respectively. The results are shown in Table 2. It can be seen that the catalyst containing Mn-Co and oxalic acid, with a molar ratio of Mn-Co of 4:6, has a 100% HMF conversion and a 92.78% FDCA yield.

[0094] Table 2 Effect of different manganese-cobalt molar ratios on catalyst performance

[0095]

[0096]

[0097] Example 4

[0098] 1 mmol of 5-hydroxymethylfurfural, 2 mmol of sodium bicarbonate and 20 ml of water were added to a 70 ml high-pressure reactor. 150 mg of Mn-Co-300 catalyst was added and the reactor was sealed. Oxygen was introduced at 1.6 MPa and heated to 140 °C at a stirring rate of 500 rpm for 4 h. After the reaction was completed, the reactor was cooled to room temperature and samples were taken for testing. The results are shown in Table 3.

[0099] 1 mmol of 5-hydroxymethylfurfural, 2 mmol of sodium bicarbonate and 20 ml of water were added to a 70 ml high-pressure reactor. 150 mg of Mn-Co-400 catalyst was added and the reactor was sealed. Oxygen was introduced at 1.6 MPa and heated to 140 °C at a stirring rate of 500 rpm for 4 h. After the reaction was completed, the reactor was cooled to room temperature and samples were taken for testing. The results are shown in Table 3.

[0100] It can be seen that the catalyst containing Mn-Co and oxalic acid, with a molar ratio of Mn-Co of 4:6, and a calcination temperature of 300℃, has a 100% HMF conversion and a 92.89% FDCA yield.

[0101] Table 3 Effect of different calcination temperatures on the catalytic performance of the catalyst

[0102] Mn-Co-300 100.00 92.89 Mn-Co-400 100.00 69.21

[0103] Example 5

[0104] Example 5 was conducted based on the Mn-Co-300 reaction method in Example 3, except that the Mn-Co-300 catalyst in Example 3 was replaced with Mn-Co-0.3, Mn-Co-0.5, Mn-Co-0.75, Mn-Co-1.0, and Mn-Co-2.0, respectively. The results are shown in Table 4. It can be seen that the catalyst containing Mn-Co and oxalic acid, with a molar ratio of Mn-Co of 4:6, a calcination temperature of 300℃, and a molar ratio of oxalic acid to Mn-Co metal salt of 0.75:1, exhibits 100% HMF conversion and 92.72% FDCA yield.

[0105] Table 4. Effect of different oxalic acid addition amounts on catalyst performance

[0106] Mn-Co-0.3 98.91 51.31 Mn-Co-0.5 100.00 59.11 Mn-Co-0.75 100.00 92.72 Mn-Co-1.0 100.00 92.26 Mn-Co-2.0 100.00 89.18

[0107] Example 6

[0108] Example 6 was carried out in the same manner as Example 1, except that the Mn-Co catalyst in Example 1 was replaced with Mn-Ni, Mn-Fe, Mn-Ce and Cu-Co respectively. After the reaction was completed, the mixture was cooled to room temperature and samples were taken for testing. The results are listed in Table 5.

[0109] Table 5 Comparison of the catalytic effects of different catalysts on the oxidation conversion of HMF

[0110] Mn-Ni 67.36 61.46 Mn-Fe 85.34 58.61 Mn-Ce 93.30 79.87 Cu-Co 85.02 56.77

[0111] Example 7

[0112] 1 mmol of 5-hydroxymethylfurfural and 20 ml of water were added to a 70 ml high-pressure reactor, followed by 1 mmol of potassium carbonate and 150 mg of Mn-Co-46 catalyst. The reactor was sealed, and oxygen was introduced at 1.6 MPa. The mixture was heated to 140 °C at a stirring rate of 500 rpm and maintained for 4 h. After the reaction was completed, the mixture was cooled to room temperature and samples were taken for testing. The results are listed in Table 6.

[0113] 1 mmol of 5-hydroxymethylfurfural and 20 ml of water were added to a 70 ml high-pressure reactor, followed by 1 mmol of sodium carbonate and 150 mg of Mn-Co-46 catalyst. The reactor was sealed, and oxygen was introduced at 1.6 MPa. The mixture was heated to 140 °C at a stirring rate of 500 rpm and maintained for 4 h. After the reaction was completed, the mixture was cooled to room temperature and samples were taken for testing. The results are listed in Table 6.

[0114] 1 mmol of 5-hydroxymethylfurfural and 20 ml of water were added to a 70 ml high-pressure reactor, followed by 2 mmol of potassium bicarbonate and 150 mg of Mn-Co-46 catalyst. The reactor was sealed, and oxygen was introduced at 1.6 MPa. The mixture was heated to 140 °C with a stirring rate of 500 rpm and maintained for 4 h. After the reaction was completed, the mixture was cooled to room temperature and samples were taken for testing. The results are listed in Table 6.

[0115] It is known that a catalyst containing Mn-Co and oxalic acid, with a molar ratio of Mn-Co of 4:6 and potassium bicarbonate as the inorganic base, has a 100% HMF conversion and a 93.42% FDCA yield.

[0116] Table 6. Effects of different inorganic bases on the oxidative synthesis of FDCA from HMF.

[0117] Mn-Co-46 Potassium carbonate 100.00 87.94 Mn-Co-46 Sodium carbonate 100.00 88.73 Mn-Co-46 Potassium bicarbonate 100.00 93.42 Mn-Co-46 Sodium bicarbonate 100.00 92.89

[0118] Example 8

[0119] 1 mmol of 5-hydroxymethylfurfural, 2 mmol of sodium bicarbonate and 20 ml of water were added to a 70 ml high-pressure reactor. 150 mg of Mn-Co-46 catalyst was added, the reactor was sealed, and oxygen was introduced at 1.6 MPa. The mixture was heated to 140 °C at a stirring rate of 500 rpm and maintained for 4 h. After the reaction was completed, the mixture was cooled to room temperature and samples were taken for testing. The results are shown in Table 7.

[0120] 1.5 mmol of 5-hydroxymethylfurfural, 3 mmol of sodium bicarbonate and 20 ml of water were added to a 70 ml high-pressure reactor. 150 mg of Mn-Co-46 catalyst was added, the reactor was sealed, and oxygen was introduced at 1.6 MPa. The reactor was heated to 140 °C at a stirring rate of 500 rpm and maintained for 4 h. After the reaction was completed, the reactor was cooled to room temperature and samples were taken for testing. The results are shown in Table 7.

[0121] 2 mmol of 5-hydroxymethylfurfural, 4 mmol of sodium bicarbonate and 20 ml of water were added to a 70 ml high-pressure reactor. 150 mg of Mn-Co-46 catalyst was added, the reactor was sealed, and oxygen was introduced at 1.6 MPa. The reactor was heated to 140 °C at a stirring rate of 500 rpm and maintained for 4 h. After the reaction was completed, the reactor was cooled to room temperature and samples were taken for testing. The results are shown in Table 7.

[0122] Table 7. Effect of HMF concentration on FDCA yield

[0123]

[0124] Example 9

[0125] The catalyst obtained by adding 2 mmol of manganese nitrate, 4 mmol of cerium nitrate, 4 mmol of cobalt nitrate and 7.5 mmol of oxalic acid to 20 ml of ethanol and mixing and letting stand for 24 h is denoted as Mn-Ce-Co after calcining the solid mixture at 300 °C for 3 h.

[0126] 1 mmol of 5-hydroxymethylfurfural, 2 mmol of sodium bicarbonate, and 20 ml of water were added to a 70 ml high-pressure reactor. 100 mg of Mn-Ce-Co catalyst was added, the reactor was sealed, and oxygen was introduced at 1.6 MPa. The mixture was heated to 140 °C at a stirring rate of 500 rpm and maintained for 8 h. After the reaction was completed, the mixture was cooled to room temperature and samples were taken for analysis. The obtained Mn-Ce-Co catalyst had a 100% HMF conversion rate and a 70.0% FDCA yield.

[0127] Comparative Example 1

[0128] 4 mmol of manganese nitrate, 6 mmol of cobalt nitrate, and 7.5 mmol of oxalic acid were added to 20 ml of ethanol. After mixing and standing for 24 h, the resulting solid mixture was calcined at 200 °C for 2 h to obtain the catalyst, which was denoted as Mn-Co-200. The molar ratio of manganese to cobalt was 4:6, and the molar ratio of oxalic acid to the metal salt was 0.75:1.

[0129] 1 mmol of 5-hydroxymethylfurfural, 2 mmol of sodium bicarbonate, and 20 ml of water were added to a 70 ml high-pressure reactor. 150 mg of Mn-Co-200 catalyst was added, the reactor was sealed, and oxygen was introduced at 1.6 MPa. The mixture was heated to 140 °C at a stirring rate of 500 rpm and maintained for 4 h. After the reaction was completed, the mixture was cooled to room temperature and samples were taken for analysis. The Mn / Co-200 catalyst showed only a 38.76% HMF conversion and a 1.45% FDCA yield.

[0130] Comparative Example 2

[0131] Comparative Example 2 was conducted in the same manner as Comparative Example 1, except that the solid mixture was calcined at 500℃ for 2 hours to obtain a catalyst, which was designated Mn-Co-500. After sampling and testing, although the Mn / Co-500 catalyst had a 100% HMF conversion rate, it only had a 1.45% FDCA yield.

[0132] Comparative Example 3

[0133] 4 mmol of manganese nitrate and 7.5 mmol of oxalic acid were added to 20 ml of ethanol. After mixing and standing for 24 h, the resulting solid mixture was calcined at 300 °C for 2 h. The resulting catalyst was denoted as Mn-300.

[0134] 1 mmol of 5-hydroxymethylfurfural, 2 mmol of sodium bicarbonate, and 20 ml of water were added to a 70 ml high-pressure reactor. 150 mg of Mn-300 catalyst was added, the reactor was sealed, and oxygen was introduced at 1.6 MPa. The mixture was heated to 140 °C at a stirring rate of 500 rpm and maintained for 4 h. After the reaction was completed, the mixture was cooled to room temperature and samples were taken for analysis. The HMF conversion rate of the Mn-300 catalyst was 95%, and the FDCA yield was 25%.

[0135] Comparative Example 4

[0136] 6 mmol of cobalt nitrate and 7.5 mmol of oxalic acid were added to 20 ml of ethanol, and the mixture was left to stand for 24 h. The resulting solid mixture was then calcined at 300 °C for 2 h to obtain the catalyst Co-300.

[0137] 1 mmol of 5-hydroxymethylfurfural, 2 mmol of sodium bicarbonate, and 20 ml of water were added to a 70 ml high-pressure reactor. 150 mg of Co-300 catalyst was added, the reactor was sealed, and oxygen was introduced at 1.6 MPa. The reactor was heated to 140 °C at a stirring rate of 500 rpm and maintained for 4 h. After the reaction was completed, the reactor was cooled to room temperature and samples were taken for analysis. The HMF conversion rate of the Co-300 catalyst was 97%, and the FDCA yield was 5%.

[0138] Comparative Example 5

[0139] 4 mmol of manganese nitrate, 6 mmol of cobalt nitrate, and 7.5 mmol of thiourea were added to 20 ml of ethanol, where the organic compound was thiourea. After mixing and standing for 24 h, the resulting solid mixture was calcined at 300 °C for 2 h to obtain the catalyst.

[0140] 1 mmol of 5-hydroxymethylfurfural, 2 mmol of sodium bicarbonate, and 20 ml of water were added to a 70 ml high-pressure reactor. 150 mg of the catalyst prepared above was added, the reactor was sealed, and oxygen was introduced at 1.6 MPa. The mixture was heated to 140 °C at a stirring rate of 500 rpm and maintained for 4 h. After the reaction was completed, the mixture was cooled to room temperature and samples were taken for testing. The final HMF conversion rate was 60%, and the FDCA yield was only 3%.

[0141] As can be seen from the data in the above examples and comparative examples, the catalyst described in this invention has excellent catalytic performance and high FDCA yield when used for the catalytic oxidation of 5-hydroxymethylfurfural. Furthermore, the preparation method of the catalyst described in this invention is simple and low in cost, and it has promising prospects for industrial application.

[0142] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0143] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A process for the production of 2,5-furandicarboxylic acid by oxidation of 5-hydroxymethylfurfural, characterized in that, 2,5-Furandicarboxylic acid is prepared by mixing 5-hydroxymethylfurfural with a catalyst, wherein the catalyst is a metal oxide catalyst, and the catalyst is prepared by the following method: An organic compound containing hydroxyl or carboxyl groups is mixed with a soluble metal salt and calcined, wherein the mixing is carried out under solvent-assisted conditions, the solvent including at least one of water, methanol and ethanol; The mixing conditions include: mixing time of 6h-24h; mixing temperature of 25℃-40℃; The molar ratio of the organic compound containing hydroxyl or carboxyl groups to the soluble metal salt is 0.75:1 or 1.0:1, the organic compound containing hydroxyl or carboxyl groups is oxalic acid, and the soluble metal salt contains Mn and Co. The calcination temperature is 300℃; The crystal form of the metal oxide is spinel-type MnCo2O 4.5 .

2. The method of claim 1, wherein, The soluble metal salt includes at least one of nitrate, acetate, and sulfate.

3. The method of claim 1, wherein, The calcination time is 1-6 hours.

4. The method according to any one of claims 1 to 3, characterized in that, The method includes: (1) 5-hydroxymethylfurfural, inorganic base, oxidant and catalyst are mixed and reacted to obtain a reaction mixture; (2) The reaction mixture is subjected to solid-liquid separation to obtain solid substances and filtrate; (3) The filtrate is processed to obtain 2,5-furandicarboxylic acid product.

5. The method of claim 4, wherein, In step (1), the concentration of 5-hydroxymethylfurfural is 0.1 mol / L to 2 mol / L.

6. The method of claim 5, wherein, In step (1), the inorganic base contains at least one of sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate.

7. The method of claim 5, wherein, In step (1), the concentration of the inorganic base is 0.001 mol / L to 4 mol / L.

8. The method of claim 5, wherein, In step (1), the oxidant is air or oxygen, the reaction pressure is 0.1 MPa-5 MPa; and / or, the reaction temperature is 20℃-170℃; and / or, the reaction time is 1h-10h.

9. The method of claim 5, wherein, In step (1), the mass ratio of 5-hydroxymethylfurfural to the catalyst is 1-10:1-10.

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