A complex catalyst, its preparation method and application in oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

Abstract

This application discloses a complex catalyst, its preparation method, and its application in the oxidation of 5-hydroxymethylfurfural to 2,5-dicarboxyfuran. The method includes at least: contacting a material containing 5-hydroxymethylfurfural with a catalyst using oxygen or air as an oxidant to react and obtain 2,5-dicarboxyfuran; wherein the catalyst is a complex catalyst; the complex catalyst is prepared from a nitrogen-containing compound A, an aldehyde compound B, and a vanadium-containing compound C. This method exhibits high oxidation efficiency, high product yield, mild reaction conditions, easy separation of the catalyst from the product, and easy purification of the product. This method has broad application prospects.

Description

Technical Field

[0001] This application relates to a complex catalyst, its preparation method, and its application in the oxidation of 5-hydroxymethylfurfural to 2,5-dicarboxyfuran, belonging to the field of chemical synthesis technology. Background Technology

[0002] The catalytic conversion of renewable biomass resources into high-value-added chemicals and liquid fuels has attracted widespread attention as a supplement to traditional fossil resource synthesis routes. 5-Hydroxymethylfurfural, which can be obtained through the dehydration of carbohydrate compounds, is one of the important platform compounds in biorefining. Its molecule contains a furan ring, an aldehyde group, and a hydroxymethyl group, exhibiting high reactivity.

[0003] 2,5-Diformylfuran is one of the important oxidation products of 5-hydroxymethylfurfural, exhibiting typical aldehyde chemical properties. 2,5-Diformylfuran can serve not only as a starting material for pharmaceuticals, macrocyclic ligands, antifungals, nematicides, and organic ligands in fine chemicals, but also as a crosslinking agent for polyvinyl alcohol in battery separators, a component of foundry sand binders, organic phosphors and luminescent materials. Furthermore, it is an important monomer for furan-based polymers, such as the synthesis of Schiff bases with different diamines and the synthesis of novel biomass-based resins with urea, demonstrating high market value.

[0004] Because the aldehyde group in 5-hydroxymethylfurfural is easily oxidized to a carboxyl group, and the furan ring is prone to ring-opening hydrolysis and polymerization, the preparation of 2,5-dicarboxyfuran from 5-hydroxymethylfurfural with high selectivity and high conversion remains challenging. Under mild conditions, the selective oxidation of 5-hydroxymethylfurfural with VOSO4 / Cu(NO3)2 can selectively prepare 2,5-dicarboxyfuran (Appl. Catal. A, 2014, 482, 231-236). However, the nitrogen oxides in this method are corrosive and easily lost after the reaction, making catalyst recycling impossible. Therefore, developing a new technique for the oxidation of 5-hydroxymethylfurfural to 2,5-dicarboxyfuran with recyclable catalyst, mild reaction conditions, high yield, and easily separable products is of great significance. Summary of the Invention

[0005] According to one aspect of this application, a method for the catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-dicarboxyfuran is provided. This method is a novel oxidation technique with mild reaction conditions, high yield, easy product separation, and recyclable catalyst. Molecular oxygen or air is used as the oxidant to catalytically oxidize 5-hydroxymethylfurfural to prepare 2,5-dicarboxyfuran. This method has broad application prospects.

[0006] According to one aspect of this application, a complex catalyst is provided, the complex catalyst having the structure shown in Formula I:

[0007]

[0008] Formula I;

[0009] L1 is selected from at least one of amino acids, alkanolamines, ethylenediamine, and o-aminophenol;

[0010] L2 is selected from at least one of 2,2-dimethyl-3-hydroxypropanal, benzaldehyde containing a single substituent, and benzaldehyde containing multiple substituents;

[0011] X, Y, and Z are independently selected from N or O, and at least one of them is N.

[0012] Specifically, Equation I can have the following structure:

[0013]

[0014]

[0015] The amino acid is selected from at least one of 2-aminoacetic acid, 2-aminopropionic acid, 2-aminobutyric acid, 2-aminovaleric acid, 2-aminohexanoic acid, 2-amino-3-methylbutyric acid, 2-amino-3-methylvaleric acid, and 2-amino-4-methylvaleric acid.

[0016] The alkanolamine is selected from at least one of ethanolamine, 2-aminopropanol, 2-amino-1-butanol, 2-amino-1-pentanol, 2-amino-1-hexanol, 2-amino-3-methyl-1-butanol, 2-amino-3-methyl-1-pentanol, and 2-amino-4-methyl-1-pentanol.

[0017] The benzaldehyde containing a single substituent is selected from at least one of 2-hydroxybenzaldehyde and 2-aminobenzaldehyde;

[0018] The benzaldehyde containing multiple substituents is selected from at least one of 2-hydroxy-4-methoxybenzaldehyde, 2-hydroxy-4-nitrobenzaldehyde, 4-chloro-2-hydroxybenzaldehyde, 2-hydroxy-4-methylbenzaldehyde, 2,4-dihydroxybenzaldehyde, 2-hydroxy-4-dimethylaminobenzaldehyde, 2-hydroxy-5-methoxybenzaldehyde, 2-hydroxy-5-nitrobenzaldehyde, 5-chloro-2-hydroxybenzaldehyde, 2-hydroxy-5-methylbenzaldehyde, 2,5-dihydroxybenzaldehyde, and 3-formyl-4-hydroxybenzaldehyde.

[0019] According to another aspect of this application, a method for preparing the above-mentioned complex catalyst is provided, comprising the following steps:

[0020] An aqueous solution containing nitrogen-containing compound A and sodium acetate is mixed with a solvent solution containing aldehyde compound B and vanadium-containing compound C, and then dried to obtain the complex catalyst.

[0021] The nitrogen-containing compound A is selected from at least one of amino acids, alkanolamines, ethylenediamine, and o-aminophenol;

[0022] The amino acid is selected from at least one of 2-aminoacetic acid, 2-aminopropionic acid, 2-aminobutyric acid, 2-aminovaleric acid, 2-aminohexanoic acid, 2-amino-3-methylbutyric acid, 2-amino-3-methylvaleric acid, and 2-amino-4-methylvaleric acid.

[0023] The alkanolamine is selected from at least one of ethanolamine, 2-aminopropanol, 2-amino-1-butanol, 2-amino-1-pentanol, 2-amino-1-hexanol, 2-amino-3-methyl-1-butanol, 2-amino-3-methyl-1-pentanol, and 2-amino-4-methyl-1-pentanol.

[0024] The aldehyde compound B is selected from at least one of 2,2-dimethyl-3-hydroxypropanal, benzaldehyde containing a single substituent, and benzaldehyde containing multiple substituents.

[0025] The benzaldehyde containing a single substituent is selected from at least one of 2-hydroxybenzaldehyde and 2-aminobenzaldehyde;

[0026] The benzaldehyde containing multiple substituents is selected from at least one of 2-hydroxy-4-methoxybenzaldehyde, 2-hydroxy-4-nitrobenzaldehyde, 4-chloro-2-hydroxybenzaldehyde, 2-hydroxy-4-methylbenzaldehyde, 2,4-dihydroxybenzaldehyde, 2-hydroxy-4-dimethylaminobenzaldehyde, 2-hydroxy-5-methoxybenzaldehyde, 2-hydroxy-5-nitrobenzaldehyde, 5-chloro-2-hydroxybenzaldehyde, 2-hydroxy-5-methylbenzaldehyde, 2,5-dihydroxybenzaldehyde, and 3-formyl-4-hydroxybenzaldehyde;

[0027] The vanadium-containing compound C is selected from at least one of vanadium acetylacetonate, vanadium trichloride, vanadium phosphate, vanadium oxalate, vanadium sulfate, ammonium metavanadate, vanadium dioxide, and vanadium pentoxide.

[0028] The solvent is selected from at least one of water, ethanol, and tetrahydrofuran.

[0029] The molar amount of sodium acetate is 0-300% of the molar amount of nitrogen-containing compound A;

[0030] Optionally, the molar amount of sodium acetate is any value or a range between 0%, 50%, 100%, 150%, 200%, 250%, and 300% of the molar amount of the nitrogen-containing compound A.

[0031] The molar ratio of the nitrogen-containing compound A to the aldehyde compound B is 1:0.5~1.1;

[0032] Optionally, the molar ratio of the nitrogen-containing compound A to the aldehyde compound B is any value from 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1 or any range between the two.

[0033] The molar ratio of the nitrogen-containing compound A to the vanadium-containing compound C is 1:0.6~1.2.

[0034] Optionally, the molar ratio of the nitrogen-containing compound A to the vanadium-containing compound C is any value from 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2 or any range between the two.

[0035] Specifically:

[0036] (1) Add nitrogen-containing compound A and anhydrous sodium acetate to deionized water in the required proportion, and heat at 60°C. o Stirring in an oil bath for 10 minutes yields mixture a;

[0037] (2) Add an ethanol-tetrahydrofuran solution containing aldehyde compound B to mixture a in the required proportion, and heat at 90°C. o C. The mixture was refluxed under an oil bath for 12 h to obtain mixture b.

[0038] (3) Add an aqueous solution of vanadium compound C to the mixture b in the required proportion, and stir at room temperature for 2 h to obtain mixture c;

[0039] (4) After stirring, the solvent in mixture c is removed by rotary evaporation. After dissolving in dichloromethane, it is extracted with water-dichloromethane. The dichloromethane layer is then removed by rotary evaporation to remove the solvent. The solution is then heated to 40°C. o The complex catalyst was obtained by vacuum drying at C for 24 h.

[0040] According to another aspect of this application, a method for preparing 2,5-dicarboxyfuran by catalytic oxidation of 5-hydroxymethylfurfural is provided, comprising the following steps:

[0041] In an oxygen-containing atmosphere, a material containing 5-hydroxymethylfurfural is contacted with a catalyst and reacted to yield 2,5-dicarboxyfuran.

[0042] The process is shown in the following formula:

[0043]

[0044] The catalyst is selected from the complex catalysts described above or the complex catalysts prepared by the preparation method described above.

[0045] The molar amount of the catalyst is 0.1 to 40% of the molar amount of 5-hydroxymethylfurfural.

[0046] Optionally, the molar amount of the catalyst is any value from 0.1%, 0.5%, 1%, 5%, 10%, 20%, 30%, 40% of the molar amount of 5-hydroxymethylfurfural, or a range between any two.

[0047] The material also contains organic solvents;

[0048] The organic solvent is selected from at least one of dimethyl sulfoxide, acetonitrile, tetrahydrofuran, N,N-dimethylformamide, toluene, 1,4-dioxane, and dichloromethane.

[0049] The reaction temperature is 30~180℃;

[0050] Optionally, the reaction temperature is 45~150℃;

[0051] Optionally, the temperature of the reaction is any value of 45°C, 50°C, 100°C, 150°C, or a range between any two.

[0052] The reaction time is 0.5~24h;

[0053] Optionally, the reaction time is 1 to 12 hours.

[0054] Optionally, the reaction time is any value among 1h, 2h, 4h, 6h, 8h, 10h, and 12h, or a range between any two.

[0055] The oxygen-containing atmosphere is selected from oxygen or air;

[0056] The partial pressure of oxygen in the oxygen-containing atmosphere is 0.02~5.0 MPa;

[0057] Optionally, the partial pressure of oxygen in the oxygen-containing atmosphere is 0.05~3.0 MPa.

[0058] Optionally, the partial pressure of oxygen in the oxygen-containing atmosphere is any value among 0.05 MPa, 0.1 MPa, 0.5 MPa, 1 MPa, 2 MPa, and 3 MPa, or a range between any two.

[0059] If the pressure drops by half during the reaction, oxygen should be replenished promptly.

[0060] Optionally, after obtaining 2,5-diformylfuran, the method further includes separating the 2,5-diformylfuran. The step of separating the 2,5-diformylfuran includes: cooling to room temperature after the reaction, filtering to remove the catalyst, and rotary evaporating the mixture to remove the solvent; adding ethyl acetate and vacuum filtering, rotary evaporating the resulting filtrate to remove the solvent, and obtaining a solid; then adding an aqueous sodium bicarbonate solution to dissolve the solid, extracting with dichloromethane, collecting the lower layer liquid after extraction, rotary evaporating to remove the dichloromethane, and drying under vacuum to obtain 2,5-diformylfuran.

[0061] The reaction takes place in a reaction vessel.

[0062] The beneficial effects that this application can produce include:

[0063] 1) The catalytic system used in this application has a simple reaction operation, using air or oxygen as the oxidant. Under mild conditions, the catalytic reaction can be completed in a short time, with substrate conversion and product selectivity reaching over 99%. The 2,5-diformylfuran product obtained by this method has high purity and is environmentally friendly.

[0064] 2) The complex catalyst system used in this application has high activity, requires less catalyst, is inexpensive and readily available, has a simple and easy preparation process, and allows for easy separation of the product and catalyst. The catalyst can be recycled, making it environmentally friendly and economical.

[0065] 3) The separated and purified products are of high quality. The separated products are tested and analyzed by gas chromatography-mass spectrometry and nuclear magnetic resonance spectrometry, and the retention time is compared with that of standard samples. The purity reaches more than 99%. Detailed Implementation

[0066] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0067] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0068] In the embodiments of this application, the conversion rate, selectivity, and separation rate are calculated as follows:

[0069]

[0070]

[0071]

[0072] Example 1

[0073] Add 1 mmol of o-aminophenol and 2 mmol of anhydrous sodium acetate to deionized water, and heat at 60 °C. oAfter stirring in an oil bath for 10 min, an ethanol-tetrahydrofuran solution containing 1 mmol of 2,2-dimethyl-3-hydroxypropanal was added, and the mixture was stirred at 90 °C. o Refluxed in an oil bath for 12 h, cooled to room temperature, and then an aqueous solution containing 1 mmol of acetylacetonate vanadyl was added. The mixture was stirred at room temperature for 2 h. After stirring, the solvent was removed by rotary evaporation. The solution was first dissolved in dichloromethane and then extracted with water-dichloromethane. The dichloromethane layer was then subjected to rotary evaporation to remove the solvent. The solution was then heated to 40 °C. o The complex catalyst was obtained by vacuum drying at C for 24 h.

[0074] Add 2 mmol of 5-hydroxymethylfurfural, 0.05 mmol of the complex catalyst, and 5 mL of dimethyl sulfoxide to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with 1 MPa of oxygen and heat to 80°C. o At temperature C, the reaction was carried out for 3 hours. Oxygen was added promptly if the pressure dropped by half during the reaction. After the reaction, the mixture was cooled to room temperature and filtered to remove the catalyst. A certain amount of 1 mL of internal standard methylbenzene was added, and a sample was taken for gas chromatography analysis. The solvent was removed by rotary evaporation, ethyl acetate was added, and the mixture was filtered. The filtrate was then rotary evaporated to remove the ethyl acetate, yielding a solid. The solid was then dissolved in an aqueous sodium bicarbonate solution, extracted with dichloromethane, and the lower layer was collected and rotary evaporated to remove the dichloromethane. After vacuum drying, the gas chromatography (GC) purity reached over 99%.

[0075] The conversion rate of 5-hydroxymethylfurfural, the GC yield of 2,5-dicarboxyfuran, and the separation yield of 2,5-dicarboxyfuran were calculated. The conversion rate of 5-hydroxymethylfurfural was 97%, the GC yield of 2,5-dicarboxyfuran was 95%, and the separation yield of 2,5-dicarboxyfuran was 82%.

[0076] The catalyst obtained by filtration and separation was collected, washed with deionized water and ethanol, and then subjected to a reaction at 40°C. o After vacuum drying at C for 12 h, multiple cyclic experiments were conducted under the same reaction conditions. The conversion rates of 5-hydroxymethylfurfural and the GC yields of 2,5-dicarboxyfuran after multiple reactions are shown in the table below:

[0077]

[0078] In other embodiments, the used complex catalyst can be subjected to multiple cycles after filtration, washing, and drying, and the catalytic activity remains almost unchanged. Specific data of the cycle experiments (i.e., the conversion rate of 5-hydroxymethylfurfural and the GC yield of 2,5-dicarboxyfuran) will not be listed here.

[0079] Example 2

[0080] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with 2-amino-4-methyl-1-pentanol, the amount of anhydrous sodium acetate added is 1 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.78 mmol of 2-aminobenzaldehyde, and 1 mmol of vanadium acetylacetonate is replaced with 1.2 mmol of vanadium pentoxide.

[0081] Add 2 mmol of 5-hydroxymethylfurfural, 3.80 mmol of the complex catalyst, and 5 mL of acetonitrile to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with 0.05 MPa of oxygen and heat to 140°C. o At temperature C, the reaction was carried out for 0.5 h. Oxygen was added promptly when the pressure dropped by half during the reaction. After the reaction was completed, the mixture was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 95%, the GC yield of 2,5-dicarboxyfuran was 94%, and the separation yield was 93%.

[0082] Example 3

[0083] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with ethylenediamine, anhydrous sodium acetate is added at 1.5 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.78 mmol of 2-hydroxybenzaldehyde, and 1 mmol of acetylacetonate vanadyl is replaced with 0.50 mmol of vanadyl trichloride.

[0084] Add 2 mmol of 5-hydroxymethylfurfural, 0.02 mmol of the complex catalyst, and 5 mL of tetrahydrofuran to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with 0.5 MPa of oxygen and heat to 70°C. o At temperature C, the reaction was carried out for 5 hours. Oxygen was added promptly when the pressure dropped by half during the reaction. After the reaction was completed, the mixture was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 90%, the GC yield of 2,5-dicarboxyfuran was 89%, and the separation yield was 85%.

[0085] Example 4

[0086] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with 2-amino-3-methyl-1-butanol, the amount of anhydrous sodium acetate added is 3 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.52 mmol of 2-hydroxybenzaldehyde, and 1 mmol of acetylacetonate is replaced with 0.88 mmol of ammonium metavanadate.

[0087] Add 2 mmol of 5-hydroxymethylfurfural, 1.80 mmol of the complex catalyst, and 5 mL of N,N-dimethylformamide to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with 0.4 MPa of oxygen and heat to 55°C. o At temperature C, the reaction was carried out for 16 hours. Oxygen was added promptly when the pressure dropped by half during the reaction. After the reaction was completed, the mixture was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 95%, the GC yield of 2,5-dicarboxyfuran was 93%, and the separation yield was 92%.

[0088] Example 5

[0089] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with 2-aminopropionic acid, the amount of anhydrous sodium acetate added is 3 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.83 mmol of 2-hydroxy-4-methoxybenzaldehyde, and 1 mmol of acetylacetonate vanadyl is replaced with 0.86 mmol of oxalate vanadyl.

[0090] Add 2 mmol of 5-hydroxymethylfurfural, 0.08 mmol of the complex catalyst, and 5 mL of toluene to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with 0.7 MPa of oxygen and heat to 60°C. o At temperature C, the reaction was carried out for 15 hours. Oxygen was added promptly when the pressure dropped by half during the reaction. After the reaction was completed, the mixture was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 89%, the GC yield of 2,5-dicarboxyfuran was 85%, and the separation yield was 80%.

[0091] Example 6

[0092] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with -amino-1-pentanol, the amount of anhydrous sodium acetate added is 2.5 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.89 mmol of 2,5-dihydroxybenzaldehyde, and 1 mmol of acetylacetonate vanadium is replaced with 0.93 mmol of vanadium sulfate.

[0093] Add 2 mmol of 5-hydroxymethylfurfural, 3.50 mmol of the complex catalyst, and 5 mL of 1,4-dioxane to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with 0.2 MPa of oxygen and heat to 95°C. oAt temperature C, the reaction was carried out for 1 hour. If the pressure dropped by half during the reaction, oxygen was added promptly. After the reaction was completed, the mixture was cooled and samples were taken for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 90%, the GC yield of 2,5-dicarboxyfuran was 87%, and the separation yield was 82%.

[0094] Example 7

[0095] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with 2-aminovaleric acid, anhydrous sodium acetate is added at 1.75 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.67 mmol of 4-chloro-2-hydroxybenzaldehyde, and 1 mmol of acetylacetonate is replaced with 0.84 mmol of ammonium metavanadate.

[0096] Add 2 mmol of 5-hydroxymethylfurfural, 0.20 mmol of the complex catalyst, and 5 mL of dichloromethane to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with 0.3 MPa of oxygen and heat to 85°C. o At temperature C, the reaction was carried out for 2 hours. Oxygen was added promptly when the pressure dropped by half during the reaction. After the reaction was completed, the mixture was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 88%, the GC yield of 2,5-dicarboxyfuran was 83%, and the separation yield was 79%.

[0097] Example 8

[0098] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with 2-aminopropanol, anhydrous sodium acetate is added at 1.25 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.73 mmol of 5-chloro-2-hydroxybenzaldehyde, and 1 mmol of vanadium acetylacetonate is replaced with 0.68 mmol of vanadium phosphate.

[0099] Add 2 mmol of 5-hydroxymethylfurfural, 2.50 mmol of the complex catalyst, and 5 mL of dimethyl sulfoxide to a 50 mL reactor. Close the reactor, replace the air in the reactor with air five times, then purge with 0.4 MPa of oxygen and heat to 65°C. o At temperature C, the reaction was carried out for 12 hours. If the pressure dropped by half during the reaction, air was added promptly. After the reaction was completed, the mixture was cooled and samples were taken for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 92%, the GC yield of 2,5-dicarboxyfuran was 89%, and the separation yield was 85%.

[0100] Example 9

[0101] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with 2-amino-3-methylbutyric acid, the amount of anhydrous sodium acetate added is 2.25 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.88 mmol of 2,4-dihydroxybenzaldehyde, and 1 mmol of acetylacetonate vanadium is replaced with 1.15 mmol of vanadium dioxide.

[0102] Add 2 mmol of 5-hydroxymethylfurfural, 0.80 mmol of the complex catalyst, and 5 mL of tetrahydrofuran to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with 0.02 MPa of oxygen and heat to 120°C. o At temperature C, the reaction was carried out for 1.5 h. Oxygen was added promptly when the pressure dropped by half during the reaction. After the reaction was completed, the mixture was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 91%, the GC yield of 2,5-dicarboxyfuran was 88%, and the separation yield was 87%.

[0103] Example 10

[0104] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with ethanolamine, anhydrous sodium acetate is added at 0.75 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.95 mmol of 2-hydroxy-5-nitrobenzaldehyde, and 1 mmol of acetylacetonate vanadyl is replaced with 0.70 mmol of vanadyl trichloride.

[0105] Add 2 mmol of 5-hydroxymethylfurfural, 2.00 mmol of the complex catalyst, and 5 mL of acetonitrile to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with 0.8 MPa of oxygen and heat to 30°C. o At temperature C, the reaction was carried out for 24 hours. Oxygen was added promptly when the pressure dropped by half during the reaction. After the reaction was completed, the mixture was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 93%, the GC yield of 2,5-dicarboxyfuran was 91%, and the separation yield was 84%.

[0106] Example 11

[0107] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with 2-amino-3-methylpentanoic acid, anhydrous sodium acetate is added at 0.5 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.56 mmol of 2-hydroxy-4-dimethylaminobenzaldehyde, and 1 mmol of vanadium acetylacetonate is replaced with 1.08 mmol of vanadium pentoxide.

[0108] Add 2 mmol of 5-hydroxymethylfurfural, 1.00 mmol of the complex catalyst, and 5 mL of 1,4-dioxane to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with 0.6 MPa of oxygen and heat to 100°C. o At temperature C, the reaction was carried out for 2 hours. Oxygen was added promptly when the pressure dropped by half during the reaction. After the reaction was completed, the mixture was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 85%, the GC yield of 2,5-dicarboxyfuran was 83%, and the separation yield was 80%.

[0109] Example 12

[0110] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with 2-amino-4-methylvaleric acid, the amount of anhydrous sodium acetate added is 2.75 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.62 mmol of 2-hydroxy-5-methoxybenzaldehyde, and 1 mmol of acetylacetonate vanadyl is replaced with 0.76 mmol of vanadyl sulfate.

[0111] Add 2 mmol of 5-hydroxymethylfurfural, 1.50 mmol of the complex catalyst, and 5 mL of N,N-dimethylformamide to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with air at 2.2 MPa and heat to 110°C. o At temperature C, the reaction was carried out for 3 hours. If the pressure dropped by half during the reaction, oxygen was added promptly. After the reaction was completed, the mixture was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 94%, the GC yield of 2,5-dicarboxyfuran was 91%, and the separation yield was 85%.

[0112] Example 13

[0113] The difference from the catalyst preparation method in Example 1 is that: o-aminophenol is replaced with 2-aminohexanoic acid, the amount of anhydrous sodium acetate added is 2.8 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.79 mmol of 2-hydroxy-4-methylbenzaldehyde, and 1 mmol of acetylacetonate is replaced with 0.97 mmol of ammonium metavanadate.

[0114] Add 2 mmol of 5-hydroxymethylfurfural, 0.50 mmol of the complex catalyst, and 5 mL of dichloromethane to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with air at 3.1 MPa and heat to 90°C. oAt temperature C, the reaction was carried out for 6 hours. Oxygen was added promptly when the pressure dropped by half during the reaction. After the reaction was completed, the mixture was cooled and samples were taken for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 98%, the GC yield of 2,5-dicarboxyfuran was 97%, and the separation yield was 93%.

[0115] Example 14

[0116] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with 2-amino-1-butanol, anhydrous sodium acetate is added at 1 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.91 mmol of 2-hydroxy-5-methylbenzaldehyde, and 1 mmol of acetylacetonate is replaced with 0.62 mmol of acetylacetonate.

[0117] Add 2 mmol of 5-hydroxymethylfurfural, 3.00 mmol of the complex catalyst, and 5 mL of toluene to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with 0.9 MPa of oxygen and heat to 75°C. o At temperature C, the reaction was carried out for 9 hours. Oxygen was added promptly when the pressure dropped by half during the reaction. After the reaction was completed, the mixture was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 95%, the GC yield of 2,5-dicarboxyfuran was 93%, and the separation yield was 88%.

[0118] Example 15

[0119] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with 2-aminobutyric acid, anhydrous sodium acetate is added at 0.25 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 1.05 mmol of 2-hydroxy-4-nitrobenzaldehyde, and 1 mmol of vanadium acetylacetonate is replaced with 1.05 mmol of vanadium sulfate.

[0120] Add 2 mmol of 5-hydroxymethylfurfural, 0.10 mmol of the complex catalyst, and 5 mL of acetonitrile to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with air at 4 MPa and heat to 180°C. o At temperature C, the reaction was carried out for 0.5 hours. If the pressure dropped by half during the reaction, oxygen was added promptly. After the reaction was completed, the mixture was cooled and samples were taken for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 88%, the GC yield of 2,5-dicarboxyfuran was 84%, and the separation yield was 83%.

[0121] Example 16

[0122] The difference from the catalyst preparation method in Example 1 is that: o-aminophenol is replaced with 2-amino-1-hexanol, the amount of anhydrous sodium acetate added is 0 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.84 mmol of 3-formyl-4-hydroxybenzoic acid, and 1 mmol of acetylacetonate vanadyl is replaced with 0.92 mmol of oxalate vanadyl.

[0123] Add 2 mmol of 5-hydroxymethylfurfural, 4.00 mmol of the complex catalyst, and 5 mL of N,N-dimethylformamide to a 50 mL reactor. Close the reactor, replace the air in the reactor with oxygen five times, then purge with air at 1.5 MPa and heat to 105 °C. o At temperature C, the reaction was carried out for 2.5 h. Oxygen was added promptly when the pressure dropped by half during the reaction. After the reaction was completed, the mixture was cooled and sampled for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 95%, the GC yield of 2,5-dicarboxyfuran was 94%, and the separation yield was 92%.

[0124] Example 17

[0125] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with 2-aminoacetic acid, the amount of anhydrous sodium acetate added is 0 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 1.10 mmol of 2-aminobenzaldehyde, and 1 mmol of acetylacetonate vanadyl is replaced with 1.18 mmol of vanadyl phosphate.

[0126] Add 2 mmol of 5-hydroxymethylfurfural, 0.05 mmol of the complex catalyst, and 5 mL of tetrahydrofuran to a 50 mL reactor. Close the reactor, replace the air in the reactor with air five times, then purge with air at 5 MPa and heat to 50 °C. o At temperature C, the reaction was carried out for 18 hours. If the pressure dropped by half during the reaction, air was added promptly. After the reaction was completed, the mixture was cooled and samples were taken for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 85%, the GC yield of 2,5-dicarboxyfuran was 82%, and the separation yield was 80%.

[0127] Example 18

[0128] The difference from the catalyst preparation method in Example 1 is that o-aminophenol is replaced with 2-amino-3-methyl-1-pentanol, the amount of anhydrous sodium acetate added is 2 mmol, 1 mmol of 2,2-dimethyl-3-hydroxypropanal is replaced with 0.93 mmol of 2-hydroxy-4-methoxybenzaldehyde, and 1 mmol of acetylacetonate is replaced with 0.60 mmol of vanadium dioxide.

[0129] Add 2 mmol of 5-hydroxymethylfurfural, 2.70 mmol of the complex catalyst, and 5 mL of dichloromethane to a 50 mL reactor. Close the reactor, replace the air in the reactor with air five times, then purge with 0.9 MPa of oxygen and heat to 160°C. o At temperature C, the reaction was carried out for 1.5 h. If the pressure dropped by half during the reaction, air was added promptly. After the reaction was completed, the mixture was cooled and samples were taken for analysis according to the method described in Example 1. The conversion rate of 5-hydroxymethylfurfural was 95%, the GC yield of 2,5-dicarboxyfuran was 93%, and the separation yield was 89%.

[0130] The reaction conditions described in this application are mild, the catalyst dosage is small, and the catalyst is easily separated from the reaction system after the reaction. The obtained 2,5-diformylfuran product has a high purity, exceeding 99%, and has broad application prospects.

[0131] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A complex catalyst, characterized in that, The complex catalyst has the structure shown in Formula I: Formula I; L1 is selected from at least one of amino acids, alkanolamines, ethylenediamine, and o-aminophenol; L2 is selected from at least one of 2,2-dimethyl-3-hydroxypropanal, benzaldehyde containing a single substituent, and benzaldehyde containing multiple substituents; X, Y, and Z are independently selected from N or O, and at least one of them is N.

2. The complex catalyst according to claim 1, characterized in that, The amino acid is selected from at least one of 2-aminoacetic acid, 2-aminopropionic acid, 2-aminobutyric acid, 2-aminovaleric acid, 2-aminohexanoic acid, 2-amino-3-methylbutyric acid, 2-amino-3-methylvaleric acid, and 2-amino-4-methylvaleric acid. The alkanolamine is selected from at least one of ethanolamine, 2-aminopropanol, 2-amino-1-butanol, 2-amino-1-pentanol, 2-amino-1-hexanol, 2-amino-3-methyl-1-butanol, 2-amino-3-methyl-1-pentanol, and 2-amino-4-methyl-1-pentanol. The benzaldehyde containing a single substituent is selected from at least one of 2-hydroxybenzaldehyde and 2-aminobenzaldehyde; The benzaldehyde containing multiple substituents is selected from at least one of 2-hydroxy-4-methoxybenzaldehyde, 2-hydroxy-4-nitrobenzaldehyde, 4-chloro-2-hydroxybenzaldehyde, 2-hydroxy-4-methylbenzaldehyde, 2,4-dihydroxybenzaldehyde, 2-hydroxy-4-dimethylaminobenzaldehyde, 2-hydroxy-5-methoxybenzaldehyde, 2-hydroxy-5-nitrobenzaldehyde, 5-chloro-2-hydroxybenzaldehyde, 2-hydroxy-5-methylbenzaldehyde, 2,5-dihydroxybenzaldehyde, and 3-formyl-4-hydroxybenzaldehyde.

3. A method for preparing the complex catalyst according to any one of claims 1 or 2, characterized in that, Includes the following steps: An aqueous solution containing nitrogen-containing compound A and sodium acetate is mixed with a solvent solution containing aldehyde compound B and vanadium-containing compound C, and then dried to obtain the complex catalyst.

4. The preparation method according to claim 3, characterized in that, The nitrogen-containing compound A is selected from at least one of amino acids, alkanolamines, ethylenediamine, and o-aminophenol; The amino acid is selected from at least one of 2-aminoacetic acid, 2-aminopropionic acid, 2-aminobutyric acid, 2-aminovaleric acid, 2-aminohexanoic acid, 2-amino-3-methylbutyric acid, 2-amino-3-methylvaleric acid, and 2-amino-4-methylvaleric acid. The alkanolamine is selected from at least one of ethanolamine, 2-aminopropanol, 2-amino-1-butanol, 2-amino-1-pentanol, 2-amino-1-hexanol, 2-amino-3-methyl-1-butanol, 2-amino-3-methyl-1-pentanol, and 2-amino-4-methyl-1-pentanol. The aldehyde compound B is selected from at least one of 2,2-dimethyl-3-hydroxypropanal, benzaldehyde containing a single substituent, and benzaldehyde containing multiple substituents. The benzaldehyde containing a single substituent is selected from at least one of 2-hydroxybenzaldehyde and 2-aminobenzaldehyde; The benzaldehyde containing multiple substituents is selected from at least one of 2-hydroxy-4-methoxybenzaldehyde, 2-hydroxy-4-nitrobenzaldehyde, 4-chloro-2-hydroxybenzaldehyde, 2-hydroxy-4-methylbenzaldehyde, 2,4-dihydroxybenzaldehyde, 2-hydroxy-4-dimethylaminobenzaldehyde, 2-hydroxy-5-methoxybenzaldehyde, 2-hydroxy-5-nitrobenzaldehyde, 5-chloro-2-hydroxybenzaldehyde, 2-hydroxy-5-methylbenzaldehyde, 2,5-dihydroxybenzaldehyde, and 3-formyl-4-hydroxybenzaldehyde; The vanadium-containing compound C is selected from at least one of vanadium acetylacetonate, vanadium trichloride, vanadium oxyphosphate, vanadium oxalate, vanadium sulfate, ammonium metavanadate, vanadium dioxide, and vanadium pentoxide. The solvent is selected from at least one of water, ethanol, and tetrahydrofuran.

5. The preparation method according to claim 3, characterized in that, The molar amount of sodium acetate is 0-300% of the molar amount of nitrogen-containing compound A; The molar ratio of the nitrogen-containing compound A to the aldehyde compound B is 1:0.5~1.1; The molar ratio of the nitrogen-containing compound A to the vanadium-containing compound C is 1:0.6~1.

2.

6. A method for preparing 2,5-dicarboxyfuran by catalytic oxidation of 5-hydroxymethylfurfural, characterized in that, Includes the following steps: In an oxygen-containing atmosphere, a material containing 5-hydroxymethylfurfural is contacted with a catalyst and reacted to yield 2,5-dicarboxyfuran. The catalyst is selected from the complex catalyst according to any one of claims 1 or 2 or the complex catalyst prepared by the preparation method according to any one of claims 3 to 5.

7. The method according to claim 6, characterized in that, The molar amount of the catalyst is 0.1 to 40% of the molar amount of 5-hydroxymethylfurfural.

8. The method according to claim 6, characterized in that, The material also contains organic solvents; The organic solvent is selected from at least one of dimethyl sulfoxide, acetonitrile, tetrahydrofuran, N,N-dimethylformamide, toluene, 1,4-dioxane, and dichloromethane.

9. The method according to claim 6, characterized in that, The reaction temperature is 30~180℃; The reaction time is 0.5 to 24 hours.

10. The method according to claim 6, characterized in that, The reaction temperature is 45~150℃.

11. The method according to claim 6, characterized in that, The reaction time is 1 to 12 hours.

12. The method according to claim 6, characterized in that, The oxygen-containing atmosphere is selected from oxygen or air; The partial pressure of oxygen in the oxygen-containing atmosphere is 0.02~5.0 MPa.

13. The method according to claim 6, characterized in that, The partial pressure of oxygen in the oxygen-containing atmosphere is 0.05~3.0 MPa.

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