A method for preparing a catalyst and a method for preparing dff by oxidizing hmf
By combining manganese oxide catalyst with oxidizing gas, the problems of low reaction efficiency and poor selectivity in the oxidation of HMF to DFF were solved, achieving efficient and mild DFF preparation, which is suitable for industrial applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PUTIAN DAKAI NEW MATERIALS CO LTD
- Filing Date
- 2026-02-04
- Publication Date
- 2026-05-29
AI Technical Summary
Existing technologies for the oxidation of HMF to DFF suffer from low reaction efficiency and poor selectivity, and require harsh reaction conditions, lacking efficient and simple catalyst solutions.
Using a self-made manganese oxide catalyst, high HMF conversion and high DFF selectivity are achieved by combining it with an oxidizing gas under alkaline conditions. The catalyst is reusable, and the process is simple and does not require high-temperature and high-pressure equipment.
It achieves 100% conversion of HMF and ≥95% selectivity of DFF, with mild reaction conditions suitable for industrial production, and the catalyst can be reused more than 5 times.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic synthesis technology, and relates to a method for preparing a catalyst and a method for preparing DFF by oxidizing HMF. Background Technology
[0002] 5-Hydroxymethylfurfural (HMF) is an important biomass platform compound that can be oxidized to produce various high-value-added chemicals, such as 2,5-dicarboxyfuran (DFF). DFF has broad application prospects in the synthesis of bactericides, pharmaceuticals, and functional polymer materials. In the oxidation of HMF to DFF, catalysts are typically required to improve reaction efficiency and selectivity while reducing the severity of reaction conditions, thus achieving green and efficient DFF preparation. Chinese patent CN117696074A discloses a method for preparing DFF based on the oxidation of HMF with sulfides supported on Anderson-type polyoxometalates, but this method requires catalytic oxidation under light conditions. Chinese patent CN112375052A discloses a method for preparing 2,5-dicarboxyfuran via a three-step cascade reaction of glucose. Glucose is converted to fructose under the action of a heterogeneous Lewis acid catalyst, and fructose is converted to 2,5-dicarboxyfuran under the action of a graphene oxide catalyst. This method involves multiple reaction steps and requires specific catalysts.
[0003] Therefore, the method for preparing DFF from HMF needs further optimization. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a method for preparing a catalyst.
[0005] On the other hand, the present invention also provides a method for preparing DFF by HMF oxidation.
[0006] The technical solution of the present invention is as follows:
[0007] A method for preparing a catalyst, comprising the following steps: Prepare a manganese salt aqueous solution; Prepare a mixed solution consisting of an alkali and an oxidizing agent; The mixed solution and the manganese salt aqueous solution are mixed and reacted. After the reaction is completed, the mixture is filtered, the solid is collected, dried, and ground to obtain the catalyst. The weight ratio of the manganese salt aqueous solution to the mixed solution is 1:1-50.
[0008] Preferably, the concentration of the manganese salt aqueous solution is 0.5-10 wt%; The manganese salt used in the manganese salt aqueous solution is selected from one or a combination of two or more of manganese nitrate, manganese sulfate, manganese chloride, manganese acetate, and manganese bromide.
[0009] Preferably, the alkali is selected from one or a combination of two or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate.
[0010] Preferably, the oxidant is selected from one or a combination of two or more of hypochlorite solution, perchlorate solution, chlorite solution, chlorine dioxide solution and hydrogen peroxide; The weight ratio of the alkali to the oxidant is 1:1-100.
[0011] Preferably, the mixing and reaction of the mixed solution and the manganese salt aqueous solution is as follows: the mixed solution is added dropwise to the manganese salt aqueous solution, and the reaction is continued by stirring for 10-60 minutes after the addition is complete.
[0012] A method for preparing DFF by oxidation of HMF, wherein HMF, organic base, organic solvent and catalyst are added to a reaction vessel and sealed, oxidizing gas is introduced, and the reaction is carried out at 60-120℃ for 10-60 min to obtain DFF solution; The catalyst is prepared by the preparation method described in any of the above embodiments.
[0013] Preferably, the weight ratio of the HMF, the organic base, the organic solvent, and the catalyst is 1:1-10:1-200:0.1-10.
[0014] Preferably, the organic base is selected from one or a combination of two or more of imidazole and its derivatives, triethylamine, pyridine and its derivatives, piperidine and its derivatives, morpholine and its derivatives, N-methyldiethylamine, DBU, DBN, tetramethylguanidine and triethanolamine.
[0015] Preferably, the organic solvent is selected from one or a combination of two or more of alcohol solvents, ether solvents, ester solvents, ketone solvents and nitrile solvents.
[0016] Preferably, the oxygen volume content in the oxidizing gas is not less than 10%, and the pressure of the oxidizing gas is 0.1-10 MPa.
[0017] The beneficial effects of this invention are: (1) The present invention prepares manganese oxide by oxidation of water-soluble manganese salt through a simple process.
[0018] (2) This invention uses self-made manganese oxide as a catalyst to oxidize HMF under alkaline conditions, achieving a high conversion rate (100%) of HMF and a high selectivity (≥95%) of DFF. The conditions are mild and the preparation method is simple, requiring no harsh conditions or complex equipment, making it suitable for industrial production. The manganese oxide catalyst can be recycled and reused after simple treatment, and can be reused more than 5 times. Detailed Implementation
[0019] The technical solution of the present invention will be further explained and described below through specific embodiments.
[0020] On the one hand, this invention proposes a method for preparing a catalyst, the steps of which include: Prepare a manganese salt aqueous solution; Prepare a mixed solution consisting of an alkali and an oxidizing agent; The mixed solution and the manganese salt aqueous solution were mixed and reacted. After the reaction was completed, the mixture was filtered, the solid was collected, dried, and ground to obtain the catalyst. The weight ratio of the manganese salt aqueous solution to the mixed solution is 1:1-50.
[0021] This invention utilizes an oxidant to oxidize manganese salt under alkaline and aqueous conditions to obtain a manganese oxide catalyst. The process is simple, the conditions are mild, and no high-temperature, high-pressure equipment or other special equipment is required. In manganese oxides, Mn is in a high valence state and possesses certain oxidizing properties, making it suitable as a catalyst for oxidation reactions. Furthermore, it is rich in active sites and works well when combined with oxidizing gases (such as oxygen and ozone) for oxidation reactions.
[0022] The weight ratio of the manganese salt aqueous solution to the mixed solution can be any value or any value between 1:1, 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, and 1:50, without any particular limitation. Furthermore, the weight ratio of the manganese salt aqueous solution to the mixed solution can be between 1:1 and 1:5.
[0023] There are no particular restrictions on the particle size of manganese oxide catalysts; for example, the average particle size can be 1-100 μm.
[0024] In some embodiments, the concentration of the manganese salt aqueous solution is 0.5-10 wt%; The manganese salt (manganese in the +2 valence) used in the manganese salt aqueous solution is selected from one or a combination of two or more of manganese nitrate, manganese sulfate, manganese chloride, manganese acetate, and manganese bromide. For example, the concentration of the manganese salt aqueous solution can be any value or any value between 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, and 10wt%, without any particular limitation.
[0025] In some embodiments, the alkali is selected from one or a combination of two or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate.
[0026] In some embodiments, the oxidant is selected from one or a combination of two or more of hypochlorite solution, perchlorate solution, chlorite solution, chlorine dioxide solution, and hydrogen peroxide; The weight ratio of alkali to oxidant is 1:1-100. For example, the weight ratio can be any value or any value between 1:1, 1:5, 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, and 1:100, without particular limitation. Further, the weight ratio of alkali to oxidant can be 1:10-50.
[0027] Hypochlorite solution (aqueous solution) may be sodium hypochlorite and / or potassium hypochlorite, with a concentration of not less than 10 wt%; perchlorate solution (aqueous solution) may be sodium perchlorite and / or potassium perchlorate, with a concentration of not less than 10 wt%; chlorite solution (aqueous solution) may be sodium chlorite and / or potassium chlorite, with a concentration of not less than 10 wt%; chlorine dioxide solution (aqueous solution) with a concentration of not less than 10 wt%. Those skilled in the art will understand that the oxidizing power of an oxidant is greatly related to its concentration. Generally, the higher the concentration, the stronger the oxidizing power. If the concentration is too low, the oxidizing power will be low, the oxidation reaction will be incomplete, or the reaction rate will be low.
[0028] In some embodiments, the mixing and reaction of the mixed solution and the manganese salt aqueous solution is carried out by adding the mixed solution dropwise to the manganese salt aqueous solution, and then continuing to stir the reaction for 10-60 minutes after the addition is complete. By adding the solution dropwise, the reaction rate can be controlled within a suitable range, avoiding an excessively fast reaction rate or violent reactions.
[0029] On the other hand, the present invention also proposes a method for preparing DFF by HMF oxidation, wherein HMF, organic base, organic solvent and catalyst are added to a reaction vessel and sealed, oxidizing gas is introduced, and the reaction is carried out at 60-120℃ for 10-60 min to obtain DFF solution. The catalyst is prepared by the preparation method described in any of the above embodiments.
[0030] This invention uses the aforementioned manganese oxide catalyst as a catalyst. The manganese oxide catalyst can adsorb oxidizing gases (such as oxygen). The adsorbed oxidizing gases are converted into superoxide radicals, peroxy radicals, etc., under the action of active sites. Furthermore, the manganese oxide catalyst, which possesses a certain degree of oxidizing power, can synergistically enhance the oxidizing power of the oxidizing gases. With the assistance of an organic base, it catalyzes the efficient conversion of HMF to DFF. The reaction conditions are mild, the reaction time is short, and the conversion rate of HMF can reach 100%, while the selectivity of DFF can reach 95% or higher. This invention also found that the organic base has a promoting effect on the oxidation reaction of HMF.
[0031] In some embodiments, the weight ratio of HMF, organic base, organic solvent, and catalyst is 1:1-10:1-200:0.1-10. For example, the weight ratio of HMF, organic base, organic solvent, and catalyst can be any value or any value between 1:1:1:0.1, 1:3:10:0.5, 1:5:30:0.5, 1:5:50:0.5, 1:8:80:0.8, 1:8:80:1, 1:10:80:1, 1:8:100:1, 1:10:100:10, 1:10:120:10, 1:10:150:10, 1:10:170:10, 1:10:200:10, etc., without any particular limitation. Furthermore, the weight ratio of HMF, organic base, organic solvent and catalyst can be 1:1-10:1-200:0.5-10.
[0032] In some embodiments, the organic base is selected from one or a combination of two or more of imidazole and its derivatives, triethylamine, pyridine and its derivatives, piperidine and its derivatives, morpholine and its derivatives, N-methyldiethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene DBU, 1,5-diazabicyclo[4.3.0]non-5-ene DBN, tetramethylguanidine, and triethanolamine. Imidazole and its derivatives may be imidazole, 1-methylimidazole, 2-methylimidazole, etc.; pyridine and its derivatives may be pyridine, 2-methylpyridine, 3-methylpyridine, 4-dimethylaminopyridine (DMAP), etc.; morpholine and its derivatives may be morpholine, N-methylmorpholine, 2-methylmorpholine, etc.
[0033] In some embodiments, the organic solvent is selected from one or a combination of two or more of alcohol solvents, ether solvents, ester solvents, ketone solvents, and nitrile solvents. Alcohol solvents may be ethanol, isopropanol, etc.; ether solvents may be ethylene glycol dimethyl ether, diethyl ether, etc.; ester solvents may be ethyl acetate, butyl acetate, etc.; ketone solvents may be acetone, butanone, etc.; and nitrile solvents may be acetonitrile, etc.
[0034] In some embodiments, the oxygen volume content in the oxidizing gas is not less than 10%, and the pressure of the oxidizing gas is 0.1-10 MPa. For example, the oxygen volume content in the oxidizing gas can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, etc., and the oxidizing gas can be air or oxygen. The pressure of the oxidizing gas can be 0.1 MPa, 0.2 MPa, 0.5 MPa, 0.7 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, etc. Further, the pressure of the oxidizing gas can be not less than 0.5 MPa.
[0035] The technical solution of the present invention will be further described and illustrated below with reference to various embodiments. Unless otherwise specified, the parts mentioned in the following embodiments are parts by weight.
[0036] Examples 1-10: Preparation of Catalysts Example 1 Dissolve 2g of manganese chloride in 18g of deionized water to prepare a 10wt% manganese salt aqueous solution.
[0037] 1.2g of sodium hydroxide was mixed with 30g of a 10wt% sodium hypochlorite aqueous solution to prepare a mixed solution.
[0038] At room temperature, the above mixed solution was added dropwise to the above manganese salt aqueous solution. After the addition was complete, the mixture was stirred for 20 minutes, filtered, and the obtained solid was dried in an oven at 60°C overnight. Then it was ground to an average particle size of 8 μm to obtain the manganese oxide catalyst.
[0039] Example 2 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, manganese chloride is replaced with an equal weight of manganese acetate. The remaining steps remain unchanged.
[0040] Example 3 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, manganese chloride is replaced with an equal weight of manganese nitrate. The remaining steps remain unchanged.
[0041] Example 4 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, sodium hydroxide is replaced with an equal weight of sodium carbonate. The remaining steps remain unchanged.
[0042] Example 5 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the sodium hypochlorite aqueous solution is replaced with an equal weight of sodium perchlorate aqueous solution with a concentration of 10wt%. The remaining steps remain unchanged.
[0043] Example 6 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the sodium hypochlorite aqueous solution is replaced with an equal weight of a 10wt% sodium chlorite aqueous solution. The remaining steps remain unchanged.
[0044] Example 7 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the sodium hypochlorite aqueous solution is replaced with an equal weight of chlorine dioxide aqueous solution with a concentration of 10wt%. The remaining steps remain unchanged.
[0045] Example 8 0.2g of manganese sulfate was dissolved in 19.8g of deionized water to prepare a 1wt% manganese salt aqueous solution.
[0046] 1g of sodium hydroxide was mixed with 19g of a 10wt% sodium hypochlorite aqueous solution to prepare a mixed solution.
[0047] At room temperature, the above mixed solution was added dropwise to the above manganese salt aqueous solution. After the addition was complete, the mixture was stirred for 30 min, filtered, and the obtained solid was dried overnight in an oven at 60 °C. Then it was ground to an average particle size of 10 μm to obtain the manganese oxide catalyst.
[0048] Example 9 1g of manganese acetate was dissolved in 19g of deionized water to prepare a 5wt% manganese salt aqueous solution.
[0049] 9g of sodium hydroxide and 90g of a 10wt% sodium hypochlorite aqueous solution were mixed to prepare a mixed solution.
[0050] At room temperature, the above mixed solution was added dropwise to the above manganese salt aqueous solution. After the addition was complete, the mixture was stirred for 10 min, filtered, and the obtained solid was dried in an oven at 60°C overnight. Then it was ground to an average particle size of 10 μm to obtain the manganese oxide catalyst.
[0051] Example 10 Dissolve 2g of manganese sulfate in 18g of deionized water to prepare a 10wt% manganese salt aqueous solution.
[0052] 1g of sodium hydroxide is mixed with 50g of a 10wt% sodium hypochlorite aqueous solution to prepare a mixed solution.
[0053] At room temperature, the above mixed solution was added dropwise to the above manganese salt aqueous solution. After the addition was complete, the mixture was stirred for 45 min, filtered, and the obtained solid was dried in an oven at 60 °C overnight. Then it was ground to an average particle size of 15 μm to obtain the manganese oxide catalyst.
[0054] Examples 11-33: Preparation of DFF by HMF Oxidation Examples 11-20 0.5 g of catalyst was placed in a 50 ml microreactor, along with 0.2 g of HMF, 20 g of ethanol, and 0.2 g of 1-methylimidazole. After purging with oxygen to remove air, the reactor was sealed and pressurized to 1 MPa. The mixture was stirred and heated to 100 °C, then maintained at this temperature for 30 min. After the reaction was complete, the mixture was cooled to room temperature, and samples were taken, diluted, and brought to a final volume. The conversion rate of HMF and the selectivity of DFF were then determined by HPLC.
[0055] Comparative Example 1 The difference between this comparative example and Example 11 is that 1-methylimidazole was not added in Example 11. The remaining steps remained unchanged.
[0056] Comparative Example 2 The difference between this comparative example and Example 11 is that no catalyst was added in Example 11. The remaining steps remain unchanged.
[0057] The results are shown in Table 1 below.
[0058] Table 1
[0059] As can be seen from the results in Table 1 above, using the manganese oxide catalyst of the present invention as a catalyst can achieve a HMF conversion rate of 100% and a DFF selectivity of not less than 95%, while without the addition of organic base or catalyst, both the HMF conversion rate and the DFF selectivity are reduced.
[0060] Examples 21-27 Different weights of the catalyst prepared in Example 1 were placed in a 50 ml microreactor. 0.2 g HMF, 20 g ethanol, and different weights of 2-methylpyridine were added. After purging with oxygen to remove air, the reactor was sealed and then filled with oxygen at different pressures. The mixture was stirred and heated to 100°C, and then kept at that temperature for 30 min. After the reaction was complete, the mixture was cooled to room temperature, and samples were taken, diluted, and brought to a final volume. The conversion rate of HMF and the selectivity of DFF were then determined by HPLC.
[0061] The results are shown in Table 2 below.
[0062] Table 2
[0063] As can be seen from the data in Table 2 above, with the increase of oxygen pressure, the oxidizing power is enhanced, and both the conversion rate of HMF and the selectivity of DFF are improved. When the pressure of the oxidizing gas is low (e.g., 0.1 MPa in Example 21), the conversion rate of HMF and the selectivity of DFF can be improved by increasing the amount of catalyst or organic base.
[0064] Examples 28-33 Different weights of the catalyst prepared in Example 2 were placed in a 50 ml microreactor. 0.2 g HMF, 15 g ethyl acetate, and 0.5 g of different organic bases were added. After purging with oxygen to remove air, the reactor was sealed and then purged with air at 2 MPa. The mixture was stirred and heated to 90 °C, and then kept at that temperature for 50 min. After the reaction was completed, the mixture was cooled to room temperature, and samples were taken, diluted, and brought to a final volume. The conversion rate of HMF and the selectivity of DFF were then determined by HPLC.
[0065] The results are shown in Table 3 below.
[0066] Table 3
[0067] As can be seen from the results in Table 3 above, the manganese oxide of the present invention has high catalytic activity. When 0.2g of HMF is added, 0.05g of catalyst can achieve a high conversion rate of HMF. Moreover, the selectivity of DFF is improved with the increase of catalyst dosage.
[0068] Following the method of Example 30 above, the organic base was replaced with N-methyldiethylamine. After the reaction was completed, the catalyst was filtered out, washed twice alternately with deionized water and anhydrous ethanol, dried at 60°C, and then subjected to a trial. The results are shown in Table 4 below.
[0069] Table 4
[0070] Therefore, the results in Table 4 show that the catalyst of the present invention has good reusability when used for the oxidation of HMF to DFF, and can be reused more than 5 times.
[0071] As described above, the basic principles, main features, and advantages of the present invention have been shown and described. Those skilled in the art should understand that the present invention is not limited to the above embodiments, which are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent changes and modifications made in accordance with the scope of the patent and the description should still fall within the scope of the present invention. The scope of protection of this invention is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a catalyst, characterized in that the step... include: Prepare a manganese salt aqueous solution; Prepare a mixed solution consisting of an alkali and an oxidizing agent; The mixed solution and the manganese salt aqueous solution are mixed and reacted. After the reaction is completed, the mixture is filtered, the solid is collected, dried, and ground to obtain the catalyst. The weight ratio of the manganese salt aqueous solution to the mixed solution is 1:1-50.
2. The method for preparing the catalyst according to claim 1, characterized in that, The concentration of the manganese salt aqueous solution is 0.5-10 wt%; The manganese salt used in the manganese salt aqueous solution is selected from one or a combination of two or more of manganese nitrate, manganese sulfate, manganese chloride, manganese acetate, and manganese bromide.
3. The method for preparing the catalyst according to claim 1, characterized in that, The alkali is selected from one or a combination of two or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate.
4. The method for preparing the catalyst according to claim 1, characterized in that, The oxidant is selected from one or a combination of two or more of hypochlorite solution, perchlorate solution, chlorite solution, chlorine dioxide solution, and hydrogen peroxide; The weight ratio of the alkali to the oxidant is 1:1-100.
5. The method for preparing the catalyst according to claim 1, characterized in that, The mixing and reaction of the mixed solution and the manganese salt aqueous solution is as follows: the mixed solution is added dropwise to the manganese salt aqueous solution, and the reaction is continued by stirring for 10-60 minutes after the addition is complete.
6. A method for preparing DFF by oxidation of HMF, characterized in that, HMF, organic base, organic solvent and catalyst are added to the reaction vessel and sealed. Oxidizing gas is introduced and the reaction is carried out at 60-120℃ for 10-60 min to obtain DFF solution. The catalyst is prepared by the preparation method according to any one of claims 1-5.
7. The method according to claim 6, characterized in that, The weight ratio of the HMF, the organic base, the organic solvent, and the catalyst is 1:1-10:1-200:0.1-10.
8. The method according to claim 6, characterized in that, The organic base is selected from one or a combination of two or more of imidazole and its derivatives, triethylamine, pyridine and its derivatives, piperidine and its derivatives, morpholine and its derivatives, N-methyldiethylamine, DBU, DBN, tetramethylguanidine and triethanolamine.
9. The method according to claim 6, characterized in that, The organic solvent is selected from one or a combination of two or more of the following: alcohol solvents, ether solvents, ester solvents, ketone solvents, and nitrile solvents.
10. The method according to claim 6, characterized in that, The oxidizing gas contains oxygen at a volume content of not less than 10%, and the pressure of the oxidizing gas is 0.1-10 MPa.