Carbon-based solid acid-base bifunctional catalyst as well as preparation method and application thereof

Abstract

The invention provides a carbon-based solid acid-base bifunctional catalyst and a preparation method and application thereof.The preparation method comprises the steps that activated carbon and a solution containing 3-mercaptopropyltrimethoxysilane are mixed for a first reaction, and after the reaction is finished, solid-liquid separation and drying are conducted; mixing the obtained sulfhydrylated activated carbon AC-SH with a solution containing 3-aminopropyltrimethoxysilane to carry out a second reaction, and after the reaction is finished, carrying out solid-liquid separation and drying; and mixing the obtained NH2-AC-SH with an oxidant solution to carry out a third reaction, and after the reaction is finished, carrying out solid-liquid separation and drying to obtain the carbon-based solid acid-base bifunctional catalyst of which the surface is simultaneously bonded with a sulfonic group and an amino group. According to the invention, a sulfonic group and an amino group are connected with an activated carbon carrier through a C-Si-O-C covalent bond, an acidic site is responsible for a dehydration reaction of saccharides, and an alkaline site promotes isomerization of aldehydes such as glucose to fructose, so that efficient conversion of various saccharides (especially glucose) into 5-hydroxymethyl-2-furaldehyde is realized.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and particularly relates to a carbon-based solid acid-base bifunctional catalyst, its preparation method, and its application. Background Technology

[0002] 5-Hydroxymethyl-2-furanaldehyde (HMF) is a core and bridge connecting biomass feedstocks and bio-based chemicals, playing a central role in the synthesis of various important chemicals, including furan-based polymers, fine chemicals, and biofuels. Currently, the preparation of HMF from sugars (such as fructose and glucose) through dehydration is a research hotspot. Existing technologies primarily utilize inorganic acids (such as hydrochloric acid and sulfuric acid), metal salts, and solid acid catalysts for this reaction. However, inorganic acid catalysts suffer from problems such as equipment corrosion, difficult post-processing, and environmental pollution; metal salt catalysts may face difficulties in metal leaching and recovery; and many solid acid catalysts (such as zeolites and acidic resins) are prone to deactivation during the reaction or are costly.

[0003] The reaction mechanism for the dehydration of fructose to produce HMF typically involves acid catalysis. However, when using glucose or sucrose as raw materials, the reaction pathway first requires the isomerization of glucose to fructose, a step that usually requires catalysis by basic or Lewis acid sites. Therefore, developing a bifunctional catalyst possessing both acidic and basic sites could efficiently achieve a one-step synthesis of HMF from glucose and other raw materials via a tandem isomerization-dehydration reaction, simplifying the process and improving reaction efficiency. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a carbon-based solid acid-base bifunctional catalyst, its preparation method and application. The method is simple, and the catalyst obtained exhibits high catalytic activity and selectivity in the preparation of HMF.

[0005] This invention provides a method for preparing a carbon-based solid acid-base bifunctional catalyst, comprising the following steps:

[0006] The activated carbon and a solution containing 3-mercaptopropyltrimethoxysilane were mixed to carry out the first reaction. After the reaction was completed, the solid-liquid separation and drying were performed to obtain thiolized activated carbon AC-SH.

[0007] The AC-SH was mixed with a solution containing 3-aminopropyltrimethoxysilane to carry out a second reaction. After the reaction was completed, solid-liquid separation and drying were performed to obtain amino and mercapto bifunctional activated carbon NH2-AC-SH.

[0008] The NH2-AC-SH was mixed with an oxidant solution to carry out a third reaction. After the reaction was completed, solid-liquid separation and drying were performed to obtain a carbon-based solid acid-base bifunctional catalyst NH2-AC-SO3H with sulfonic acid groups and amino groups bonded to its surface.

[0009] Preferably, both the first and second reactions are carried out under an inert atmosphere.

[0010] The temperature of both the first and second reactions is 30~120℃, and the reaction time is 6~24h.

[0011] Preferably, the temperature of the third reaction is 20~80℃, and the time is 2~12h;

[0012] The oxidant is a hydrogen peroxide solution with a mass fraction of 5-30%.

[0013] Preferably, the solvent in the solution containing 3-mercaptopropyltrimethoxysilane is selected from ethyl acetate, ethanol, or toluene;

[0014] The mass-to-volume ratio of the activated carbon to the solvent is 1g:(10~30)mL;

[0015] The mass-to-volume ratio of the activated carbon and 3-mercaptopropyltrimethoxysilane is 1 g: (5~15) mL.

[0016] Preferably, the solvent in the solution containing 3-aminopropyltrimethoxysilane is a 65%~85% aqueous ethanol solution;

[0017] The mass-to-volume ratio of the thiolized activated carbon AC-SH to the solvent is 1 g:(10~30) mL;

[0018] The mass-to-volume ratio of AC-SH to 3-aminopropyltrimethoxysilane is 1 g:(5~15) mL;

[0019] The mass-to-volume ratio of NH2-AC-SH to the oxidant solution is 1 g:(10~30) mL.

[0020] This invention provides a carbon-based solid acid-base bifunctional catalyst prepared by the preparation method described above, characterized in that the catalyst uses activated carbon as a support, and its surface is simultaneously modified with sulfonic acid groups and amino groups through chemical bonding.

[0021] This invention provides the application of a carbon-based solid acid-base bifunctional catalyst prepared by the preparation method described above in the catalytic preparation of 5-hydroxymethyl-2-furan carbaldehyde from carbohydrate compounds.

[0022] Preferably, the carbohydrate compound is selected from at least one of fructose, glucose, sucrose and cellulose.

[0023] Preferably, the preparation of 5-hydroxymethyl-2-furanaldehyde from catalytic carbohydrate compounds is carried out in a polar aprotic solvent;

[0024] The polar aprotic solvent is selected from one or more of dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone, γ-valerolactone, ethyl acetate, and ionic liquids.

[0025] Preferably, the temperature for preparing 5-hydroxymethyl-2-furan carboxaldehyde from carbohydrate compounds is 80~180℃, and the time is 0.5~8h.

[0026] This invention provides a method for preparing a carbon-based solid acid-base bifunctional catalyst, comprising the following steps: mixing activated carbon with a solution containing 3-mercaptopropyltrimethoxysilane for a first reaction, followed by solid-liquid separation and drying to obtain mercapto-modified activated carbon AC-SH; mixing AC-SH with a solution containing 3-aminopropyltrimethoxysilane for a second reaction, followed by solid-liquid separation and drying to obtain amino and mercapto-modified bifunctional activated carbon NH2-AC-SH; mixing NH2-AC-SH with an oxidant solution for a third reaction, followed by solid-liquid separation and drying to obtain a carbon-based solid acid-base bifunctional catalyst NH2-AC-SO3H with sulfonic acid groups and amino groups simultaneously bonded to its surface. This invention introduces sulfonic acid groups and amino groups simultaneously onto the surface of activated carbon. These two functional groups are connected to the activated carbon support through stable C-Si-OC covalent bonds, preventing the loss of active components and constructing a well-defined solid acid-base bifunctional catalyst. The acidic sites are responsible for the dehydration reaction of sugars, while the basic sites can promote the isomerization of aldoses such as glucose to fructose, thereby achieving efficient conversion of various sugars (especially glucose) into 5-hydroxymethyl-2-furanaldehyde. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the preparation process of the catalyst of the present invention;

[0028] Figure 2 The image shows a comparison of the Fourier transform infrared (FT-IR) spectra of the catalyst NH2-AC-SO3H prepared in Example 1 and the original activated carbon (AC).

[0029] Figure 3 The graph shows the catalyst reuse performance test under the conditions of Example 2. Detailed Implementation

[0030] This invention provides a method for preparing a carbon-based solid acid-base bifunctional catalyst, comprising the following steps:

[0031] The activated carbon and a solution containing 3-mercaptopropyltrimethoxysilane were mixed to carry out the first reaction. After the reaction was completed, the solid-liquid separation and drying were performed to obtain thiolized activated carbon AC-SH.

[0032] The AC-SH was mixed with a solution containing 3-aminopropyltrimethoxysilane to carry out a second reaction. After the reaction was completed, solid-liquid separation and drying were performed to obtain amino and mercapto bifunctional activated carbon NH2-AC-SH.

[0033] The NH2-AC-SH was mixed with an oxidant solution to carry out a third reaction. After the reaction was completed, solid-liquid separation and drying were performed to obtain a carbon-based solid acid-base bifunctional catalyst NH2-AC-SO3H with sulfonic acid groups and amino groups bonded to its surface.

[0034] This invention successfully introduces sulfonic acid groups and amino groups simultaneously onto the surface of activated carbon through a stepwise grafting and selective oxidation strategy, constructing a well-defined solid acid-base bifunctional catalyst. These two functional groups are linked to the activated carbon support via stable C-Si-OC covalent bonds, preventing the loss of active components. The acidic sites are responsible for the dehydration reaction of sugars, while the basic sites can promote the isomerization of aldoses such as glucose to fructose, thereby achieving efficient conversion of various sugars (especially glucose) into 5-hydroxymethyl-2-furanaldehyde.

[0035] In this invention, activated carbon and a solution containing 3-mercaptopropyltrimethoxysilane are mixed to carry out a first reaction. After the reaction is completed, solid-liquid separation and drying are performed to obtain thiolized activated carbon AC-SH.

[0036] In this invention, the first reaction is carried out under an inert atmosphere; the temperature of the first reaction is 30~120℃, specifically 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃ or 120℃; the time of the first reaction is 6~24h, specifically 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h or 24h.

[0037] In this invention, activated carbon is a porous carbon material that is inexpensive, readily available, has a large specific surface area, and stable physicochemical properties, making it an ideal catalyst support. This invention constructs a carbon-based acid-base bifunctional catalyst containing both sulfonic acid groups and amino groups by performing thiolation, ammoniation, and thiooxidation reactions on activated carbon, which can be used for the efficient catalysis of the preparation of HMF from various sugars.

[0038] The solvent used in the solution containing 3-mercaptopropyltrimethoxysilane described in this invention is selected from ethyl acetate, ethanol, or toluene; the mass-to-volume ratio of the activated carbon to the solvent is 1 g:(10~30) mL, specifically 1 g:10 mL, 2 g:10 mL, 3 g:10 mL, 4 g:10 mL, 5 g:10 mL, 6 g:10 mL, 7 g:10 mL, 8 g:10 mL, 9 g:10 mL, 10 g:10 mL, 11 g:10 mL, 12 g:10 mL, 13 g:10 mL, 14 g:10 mL, 15 g:10 mL, 16 g:10 mL, 17 g:10 mL, 18 g:10 mL, 19 g:10 mL, 20 g:10 mL, 21 g:10 mL, 22 g:10 mL, 23 g:10 mL, 24 g:10 mL, 25 g:10 mL, 26 g:10 mL, 26 g:10 mL, 27 g:10 mL, 28 g:10 mL, 29 g:10 mL, 20 g:10 mL, 21 g:10 mL, 22 g:10 mL, 23 g:10 mL, 24 g:10 mL, 25 ... The activated carbon is 10 mL, 27 g: 10 mL, 28 g: 10 mL, 29 g: 10 mL, or 30 g: 10 mL; the mass-to-volume ratio of the activated carbon to 3-mercaptopropyltrimethoxysilane is 1 g:(5~15) mL; specifically, it can be 1 g:5 mL, 1 g:6 mL, 1 g:7 mL, 1 g:8 mL, 1 g:9 mL, 1 g:10 mL, 1 g:11 mL, 1 g:12 mL, 1 g:13 mL, 1 g:14 mL, or 1 g:15 mL.

[0039] The present invention preferably separates solids and liquids by filtration or centrifugation and dries the solids.

[0040] After obtaining the thiolized activated carbon AC-SH, the present invention mixes the AC-SH with a solution containing 3-aminopropyltrimethoxysilane to carry out a second reaction. After the reaction is completed, the mixture is separated into solid and liquid phases and dried to obtain the amino and thiol bifunctionalized activated carbon NH2-AC-SH. In the present invention, the second reaction is carried out under an inert atmosphere; the temperature of the second reaction is 30~120℃, specifically 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃ or 120℃; the time of the second reaction is 6~24h, specifically 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h or 24h.

[0041] In this invention, the solvent used in the solution containing 3-aminopropyltrimethoxysilane is a 65-85% aqueous ethanol solution; the mass-to-volume ratio of the thiolized activated carbon AC-SH to the 65-85% aqueous ethanol solution is 1 g:(10-30) mL, specifically 1 g:10 mL, 1 g:11 mL, 1 g:12 mL, 1 g:13 mL, 1 g:14 mL, 1 g:15 mL, 1 g:16 mL, 1 g:17 mL, 1 g:18 mL, 1 g:19 mL, 1 g:20 mL, 1 g:21 mL, 1 g:22 mL, 1 g:23 mL, 1 g:24 mL, 1 g:25 mL, 1 g:26 mL, 1 g:27 mL, 1 g:28 mL, 1 g:29 mL, or 1 g:30 mL; the mass-to-volume ratio of AC-SH to 3-aminopropyltrimethoxysilane is 1 g:(5-15) mL.

[0042] After obtaining amino and thiol-functionalized activated carbon NH2-AC-SH, the present invention mixes the NH2-AC-SH with an oxidant solution to carry out a third reaction. After the reaction is completed, the carbon-based solid acid-base bifunctional catalyst NH2-AC-SO3H with sulfonic acid groups and amino groups bonded to its surface is obtained.

[0043] The oxidant solution described in this invention is a hydrogen peroxide aqueous solution with a mass concentration of 5% to 30%. In this invention, the mass-to-volume ratio of NH₂-AC-SH to the oxidant solution is 1 g:(10~30) mL, specifically 1 g:10 mL, 1 g:11 mL, 1 g:12 mL, 1 g:13 mL, 1 g:14 mL, 1 g:15 mL, 1 g:16 mL, 1 g:17 mL, 1 g:18 mL, 1 g:19 mL, 1 g:20 mL, 1 g:21 mL, 1 g:22 mL, 1 g:23 mL, 1 g:24 mL, 1 g:25 mL, 1 g:26 mL, 1 g:27 mL, 1 g:28 mL, 1 g:29 mL, or 1 g:30 mL.

[0044] In this invention, the temperature of the third reaction is 20~80℃, specifically 20℃, 30℃, 40℃, 50℃, 60℃, 70℃ or 80℃; the time of the third reaction is 2~12h, specifically 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h or 12h.

[0045] The method provided by this invention uses commercially available, inexpensive activated carbon as a carrier, and the silane reagent and hydrogen peroxide used are common chemicals, resulting in low cost. The preparation process involves conventional liquid-phase grafting and oxidation reactions, with simple steps, mild conditions, and easy scale-up for production. This invention avoids the use of corrosive liquid acids, reducing emissions and aligning with the development direction of green chemistry.

[0046] Figure 1 This is a schematic diagram of the process for preparing a carbon-based solid acid-base bifunctional catalyst in a specific embodiment of the present invention.

[0047] This invention provides a carbon-based solid acid-base bifunctional catalyst prepared by the preparation method described above. The catalyst uses activated carbon as a support, and its surface is simultaneously modified with sulfonic acid groups and amino groups through chemical bonding.

[0048] Specifically, the catalyst uses activated carbon as a support, and its surface is chemically bonded by a silane coupling agent to simultaneously and stably modify sulfonic acid groups (-SO3H) that provide acidic centers and amino groups (-NH2) that provide basic centers, thereby forming acid-base bifunctional active sites.

[0049] The present invention also provides the application of the carbon-based solid acid-base bifunctional catalyst prepared by the preparation method described above in the catalytic preparation of 5-hydroxymethyl-2-furan carbaldehyde from carbohydrate compounds.

[0050] In this invention, the carbohydrate compound is selected from at least one of fructose, glucose, sucrose, and cellulose. This catalyst exhibits high yields and selectivity of 5-hydroxymethyl-2-furanaldehyde for a variety of substrates, including fructose, glucose, and sucrose. Due to its heterogeneous characteristics, the catalyst is easily separated from the reaction system by simple filtration and can be reused multiple times without significant decrease in activity, demonstrating good stability.

[0051] In this invention, the preparation of 5-hydroxymethyl-2-furanaldehyde from catalytic carbohydrate compounds is carried out in a polar aprotic solvent; the polar aprotic solvent is selected from one or more of dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone, γ-valerolactone, ethyl acetate, and ionic liquids.

[0052] In this invention, the temperature for preparing 5-hydroxymethyl-2-furanaldehyde from carbohydrate compounds is 80~180℃, specifically 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃ or 180℃; the time is 0.5~8h, specifically 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h or 8h.

[0053] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, provides a carbon-based solid acid-base bifunctional catalyst, its preparation method, and its applications. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0054] Example 1: Preparation of Catalyst

[0055] Take 5.0 g of pretreated activated carbon (AC, 50 mesh) and disperse it in 100 mL of toluene. Disperse it by sonication for 30 min. Add 30 mL of 3-mercaptopropyltrimethoxysilane and reflux at 110 °C for 12 h under nitrogen protection. After the reaction is completed, cool to room temperature, filter, wash three times with toluene and ethanol respectively, and dry in a vacuum drying oven at 80 °C for 12 h to obtain thiolized activated carbon AC-SH.

[0056] Take 4.0 g of AC-SH and redisperse it in 80 mL of 75% ethanol. Add 20 mL of 3-aminopropyltrimethoxysilane and reflux at 80 °C for 12 h under nitrogen protection. After the reaction is complete, cool, filter, wash with ethanol, and vacuum dry at 80 °C for 12 h to obtain aminated-thiolized activated carbon NH2-AC-SH.

[0057] Take 3.0 g of NH2-AC-SH and disperse it in 30 mL of deionized water. Slowly add 30 mL of 30% hydrogen peroxide and stir the reaction at 60 °C for 6 h. After the reaction is complete, filter the solution and wash it with a large amount of deionized water and ethanol until the filtrate is neutral. Dry it under vacuum at 80 °C for 12 h to obtain the final product, the carbon-based solid acid-base bifunctional catalyst NH2-AC-SO3H.

[0058] Figure 2 This is a comparison of the Fourier Transmission Spectra (FT-IR) of the catalyst NH2-AC-SO3H prepared in Example 1 and the original activated carbon (AC); Figure 2 It can be seen that: compared to the original AC, NH2-AC-SO3H at 771 cm⁻¹ -1 and 1106 cm -1 Characteristic peaks of asymmetric stretching vibrations of Si-OC and Si-O-Si were observed nearby, confirming that 3-mercaptopropyltrimethoxysilane successfully grafted silicon-containing functional groups onto the support surface through a hydrolytic condensation reaction between its methoxy group and the hydroxyl group (-OH) on the AC surface. Subsequently, at 1038 cm⁻¹... -1 884 cm -1 and 1250 cm -1 The presence of stretching vibration peaks at 1163 cm⁻¹, attributed to the S=O, SO, and -SO₃H groups in the sulfonic acid group, indicates that the grafted thiol group was effectively sulfonated to -SO₃H via subsequent oxidation steps. Furthermore, at 1163 cm⁻¹... -1 A CN stretching vibration absorption peak appears at 1738 cm⁻¹, and at 1738 cm⁻ -1The observation of a characteristic peak of the NH stretching vibration of the amino group nearby indicates that 3-aminopropyltrimethoxysilane also reacts with the hydroxyl groups on the AC surface through a similar mechanism to introduce the amino group. These results demonstrate that the sulfonic acid group and the amino group have been successfully and stably linked to the activated carbon support via C-Si-OC covalent bonds, forming a bifunctional solid acid catalyst NH2-AC-SO3H.

[0059] Comparative Example 1: Catalyst containing only sulfonic acid groups (AC-SO3H)

[0060] Referring to Example 1, only steps (1) and (3) were performed, without the amination modification in step (2), to obtain a catalyst AC-SO3H containing only sulfonic acid groups.

[0061] Example 2: Catalytic dehydration of fructose to prepare HMF

[0062] In a 50 mL thick-walled, pressure-resistant reaction tube, 0.1 g of the catalyst NH₂-AC-SO₃H prepared in Example 1, 0.5 g of fructose, and 10 mL of dimethyl sulfoxide (DMSO) were added. The reaction tube was sealed and placed in an oil bath at 150 °C with stirring for 2 h. After the reaction was complete, the reaction tube was cooled in an ice-water bath, and the catalyst was separated by centrifugation. The supernatant was collected, and the product was analyzed by high-performance liquid chromatography (HPLC). The yield of HMF was calculated to be 92.5%.

[0063] Example 3: Catalytic dehydration of glucose to prepare HMF

[0064] The reaction conditions were the same as in Example 2, except that the substrate fructose was replaced with 0.5 g of glucose, and the reaction time was extended to 4 h. The calculated yield of HMF was 78.3%.

[0065] Example 4: Catalytic dehydration of sucrose to prepare HMF

[0066] The reaction conditions were the same as in Example 2, except that the substrate fructose was replaced with 0.5 g of sucrose, and the reaction time was 4 h. The calculated yield of HMF was 75.8%.

[0067] Comparative Example 2: Dehydration of glucose using the catalyst from Comparative Example 1

[0068] The reaction conditions were the same as in Example 3, except that the catalyst was replaced with AC-SO3H prepared in Comparative Example 1. The calculated yield of HMF was only 25.1%.

[0069] Example 5: Reusability of the catalyst

[0070] Using fructose dehydration as a model reaction (under the same conditions as in Example 2), after the reaction was completed, the catalyst prepared in Example 1 was recovered by centrifugation, washed several times with ethanol, dried at 80°C, and used for the next reaction. After being reused 6 times, the HMF yield remained above 85%, indicating that the catalyst has good stability (see Example 1). Figure 3 ).

[0071] As can be seen from the above embodiments, the present invention provides a method for preparing a carbon-based solid acid-base bifunctional catalyst, comprising the following steps: mixing activated carbon and a solution containing 3-mercaptopropyltrimethoxysilane for a first reaction, and after the reaction, performing solid-liquid separation and drying to obtain mercapto-modified activated carbon AC-SH; mixing the AC-SH with a solution containing 3-aminopropyltrimethoxysilane for a second reaction, and after the reaction, performing solid-liquid separation and drying to obtain amino and mercapto-modified bifunctional activated carbon NH2-AC-SH; mixing the NH2-AC-SH with an oxidant solution for a third reaction, and after the reaction, performing solid-liquid separation and drying to obtain a carbon-based solid acid-base bifunctional catalyst NH2-AC-SO3H with sulfonic acid groups and amino groups simultaneously bonded to its surface. This invention introduces sulfonic acid groups and amino groups simultaneously onto the surface of activated carbon. These two functional groups are linked to the activated carbon support via stable C-Si-OC covalent bonds, preventing the loss of active components and constructing a well-defined solid acid-base bifunctional catalyst. The acidic sites are responsible for the dehydration reaction of sugars, while the basic sites promote the isomerization of aldoses such as glucose to fructose, thereby achieving efficient conversion of various sugars (especially glucose) to 5-hydroxymethyl-2-furanaldehyde. Experimental results show that the yield of HMF catalyzed by glucose is 92.5%; the yield of HMF catalyzed by fructose is 78.3%; and the yield of HMF catalyzed by sucrose is 75.8%. Even after six reuses, the yield of HMF catalyzed by fructose remains above 85%.

[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon-based solid acid-base bifunctional catalyst, comprising the following steps: The activated carbon and a solution containing 3-mercaptopropyltrimethoxysilane were mixed to carry out the first reaction. After the reaction was completed, the solid-liquid separation and drying were performed to obtain thiolized activated carbon AC-SH. The AC-SH was mixed with a solution containing 3-aminopropyltrimethoxysilane to carry out a second reaction. After the reaction was completed, solid-liquid separation and drying were performed to obtain amino and mercapto bifunctional activated carbon NH2-AC-SH. The NH2-AC-SH was mixed with an oxidant solution to carry out a third reaction. After the reaction was completed, solid-liquid separation and drying were performed to obtain a carbon-based solid acid-base bifunctional catalyst NH2-AC-SO3H with sulfonic acid groups and amino groups bonded to its surface.

2. The production method according to claim 1, characterized by, Both the first and second reactions were carried out under an inert atmosphere. The temperature of both the first and second reactions is 30~120℃, and the reaction time is 6~24h.

3. The preparation method according to claim 1, characterized in that, The temperature of the third reaction is 20~80℃, and the time is 2~12h; The oxidant is a hydrogen peroxide solution with a mass fraction of 5-30%.

4. The preparation method according to claim 1, characterized in that, The solvent in the solution containing 3-mercaptopropyltrimethoxysilane is selected from ethyl acetate, ethanol, or toluene; The mass-to-volume ratio of the activated carbon to the solvent is 1g:(10~30)mL; The mass-to-volume ratio of the activated carbon and 3-mercaptopropyltrimethoxysilane is 1 g: (5~15) mL.

5. The preparation method according to claim 1, characterized in that, The solvent in the solution containing 3-aminopropyltrimethoxysilane is a 65%~85% aqueous ethanol solution; The mass-to-volume ratio of the thiolized activated carbon AC-SH to the solvent is 1 g:(10~30) mL; The mass-to-volume ratio of AC-SH to 3-aminopropyltrimethoxysilane is 1 g:(5~15) mL; The mass-to-volume ratio of NH2-AC-SH to the oxidant solution is 1 g:(10~30) mL.

6. A carbon-based solid acid-base bifunctional catalyst prepared by the preparation method according to any one of claims 1 to 5, characterized in that, The catalyst uses activated carbon as a support, and its surface is simultaneously modified with sulfonic acid groups and amino groups through chemical bonding.

7. The application of a carbon-based solid acid-base bifunctional catalyst prepared by the preparation method according to any one of claims 1 to 6 in the catalytic preparation of 5-hydroxymethyl-2-furan carbaldehyde from carbohydrate compounds.

8. The application according to claim 7, characterized in that, The carbohydrate compound is selected from at least one of fructose, glucose, sucrose, and cellulose.

9. The application according to claim 8, characterized in that, The preparation of 5-hydroxymethyl-2-furanaldehyde from catalytic carbohydrates was carried out in a polar aprotic solvent; The polar aprotic solvent is selected from one or more of dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone, γ-valerolactone, ethyl acetate, and ionic liquids.

10. The application according to claim 8, characterized in that, The temperature for preparing 5-hydroxymethyl-2-furanaldehyde from carbohydrate compounds is 80~180℃, and the time is 0.5~8h.

Images