Bifunctional carbon-based catalyst and use thereof

Abstract

The application discloses a kind of bifunctional carbon-based catalyst and its application, the bifunctional carbon-based catalyst of the particle size 1nm-7 μm boron-carbon-based microspheres, with furan boronic acid and methylglyoxal as raw material to prepare by hydrothermal co-carbonization reaction.It is with methylglyoxal and furan boronic acid mixture as composite functional carbon source, by one-step hydrothermal co-carbonization method synthesized with strong adsorption boron hydroxyl and in-situ carboxyl bifunctional carbon-based catalyst.Boron hydroxyl is adsorption site, by with cellulose form chemical bond force to improve the mass transfer efficiency of catalyst and cellulose;With in-situ carboxyl as catalytic site, break glycosidic bond, can realize cellulose to glucose efficient conversion in pure aqueous phase.In addition, the bifunctional carbon-based catalyst of the application has excellent hydrothermal stability and repeatability in catalyzing cellulose conversion, solvent system is water, more economical, green, safe.

Description

Technical Field

[0001] This invention belongs to the field of biomass high-value conversion and utilization technology, specifically relating to a bifunctional carbon-based catalyst and its application. Background Technology

[0002] Unlike finite fossil fuels, biomass is a renewable resource derived from plant photosynthesis. It is widely distributed, diverse, and abundant, making its development potential and application value a subject of considerable interest. In typical non-grain biomass, cellulose content is far higher than hemicellulose and lignin, but cellulose itself has limited uses. Glucose, on the other hand, has a wide range of applications and can be converted into valuable downstream chemicals and renewable biofuels. Therefore, the hydrolysis of cellulose into sugars is key to expanding cellulose applications and producing various chemicals and fuels. Researching how to efficiently convert cellulose into sugars is our primary focus.

[0003] However, cellulose itself has a high degree of crystallinity, making it insoluble in water and most organic solvents. Furthermore, cellulose undergoes recrystallization during hydrolysis, reducing its accessibility. These are key obstacles to the efficient hydrolysis of cellulose into sugars, and effectively breaking down the cellulose structure has been crucial for improving its hydrolysis efficiency.

[0004] To date, liquid acids have been used as catalysts for cellulose hydrolysis in the chemical industry due to their low cost. High-concentration liquid acids can catalyze the rapid decomposition of cellulose glycosidic bonds, but they also present many problems, such as sugar-acid separation, equipment corrosion, acid recovery and wastewater treatment, as well as the generation of a large number of byproducts.

[0005] Solid acid catalysts can overcome the shortcomings of liquid acid catalysts and have attracted increasing attention. A series of heterogeneous solid acids have been developed, such as those disclosed in patents CN112717953B, CN112264051B, CN110560087B, and CN107262149A.

[0006] However, most carbon-based solid acid catalysts developed in current technologies are synthesized from biomass and its derivatives through carbonization and sulfonation steps. The sulfonation step may generate some toxic gases and is difficult to separate the final product, which does not conform to the principles of green chemistry; moreover, the sulfonic acid group, as a strong acid catalytic site, has low selectivity for hydrolyzing cellulose, is prone to leaching and deactivation, and is hydrothermally unstable.

[0007] Furthermore, a significant heterogeneous interface exists between traditional solid acids and cellulose. The surface of solid acids lacks ideal cellulose binding sites, resulting in low accessibility and greatly weakening the contact catalytic effect. These factors limit the application of solid acid hydrolysis of cellulose. There is an urgent need to develop carbon-based solid acid catalysts containing other acidic functional groups to more stably and effectively form strong affinity with cellulose molecular chains, thereby enhancing the hydrolysis conversion rate of cellulose in the reaction system. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a bifunctional carbon-based catalyst. This invention uses a mixture of acetone aldehyde and furanoboric acid as a composite functional carbon source to increase carbon formation efficiency, and prepares the bifunctional carbon-based catalyst via a hydrothermal reaction. Based on the structural characteristics of acetone aldehyde and furanoboric acid and the properties of the hydrothermal reaction, the obtained bifunctional carbon-based catalyst has a large number of boron hydroxyl groups and oxygen-containing functional groups distributed on its surface, which can effectively promote the hydrolysis of cellulose.

[0009] A bifunctional carbon-based catalyst, wherein the bifunctional carbon-based catalyst is a boron-carbon-based microsphere with a particle size of 1 nm-7 μm, prepared by hydrothermal co-carbonization reaction using furan boric acid and acetone aldehyde as raw materials.

[0010] This invention utilizes acetone aldehyde and furan boronic acid as novel carbon sources, and synthesizes a bifunctional carbon-based catalyst with strong adsorption of boron hydroxyl groups and in-situ carboxyl groups through a one-step hydrothermal co-carbonization process. This invention simultaneously introduces a large number of boron hydroxyl, hydroxyl, and carboxyl groups in a relatively mild reaction environment. The synthesis mechanism lies in the hydrothermal co-carbonization process, which results in a large number of boron hydroxyl and oxygen-containing functional groups on the surface of the carbon material.

[0011] The steps for preparing a bifunctional carbon-based catalyst by hydrothermal co-carbonization reaction using furan boric acid and acetone aldehyde as raw materials are as follows: acetone aldehyde, furan boric acid and deionized water are mixed and placed in a hydrothermal synthesis reactor for hydrothermal reaction. After the reaction is completed, the reaction product is washed and dried to obtain the bifunctional carbon-based catalyst.

[0012] Preferably, the acetone aldehyde is a acetone aldehyde solution with a volume fraction of 30-70%.

[0013] Preferably, the mass-to-volume ratio of furanboric acid and acetone aldehyde solution is 1 kg: 1-10 L.

[0014] Preferably, the volume ratio of the acetone aldehyde solution to deionized water is 1:10-100.

[0015] Preferably, the hydrothermal reaction temperature is 160-200℃, and the reaction time is 6-10 hours. More preferably, the hydrothermal reaction temperature is 160℃, and the reaction time is 10 hours. Under these hydrothermal reaction conditions, the catalyst surface has a greater number of oxygen-containing functional groups.

[0016] This invention also provides an application of the aforementioned bifunctional carbon-based catalyst in the hydrolysis of cellulose into sugars in a pure aqueous phase. Specifically, the bifunctional carbon-based catalyst is mixed with cellulose raw materials in a pure aqueous system, and the cellulose is hydrolyzed and converted under high-temperature, closed conditions to obtain sugars and furan-like platform compounds, achieving high-value conversion and utilization of biomass.

[0017] The bifunctional carbon-based catalyst prepared in this invention contains a large number of boron hydroxyl, hydroxyl, and carboxyl groups. Using boron hydroxyl groups as adsorption sites, it enhances the mass transfer efficiency between the catalyst and cellulose by forming chemical bonds with cellulose. Compared to ordinary hydroxyl groups, boron hydroxyl groups can effectively break the aggregated structure of cellulose through strong interfacial adsorption interactions; using in-situ carboxyl groups as catalytic sites, it breaks glycosidic bonds, achieving efficient conversion of cellulose to glucose in a pure aqueous phase.

[0018] The bifunctional carbon-based catalyst of this invention can independently catalyze the hydrolysis of cellulose in a pure water system, avoiding the equipment corrosion problem caused by liquid acid, making it more economical, green, and safe, and the product separation is simple.

[0019] Preferably, the mass ratio of the bifunctional carbon-based catalyst to cellulose is 1:0.1-10.

[0020] Preferably, the cellulose includes one or more of microcrystalline cellulose, regenerated cellulose, corn cob cellulose, straw cellulose, viscose cellulose, cotton cellulose, and cuprammonium cellulose.

[0021] Preferably, the mass-to-volume ratio of the bifunctional carbon-based catalyst to deionized water is 1 kg: 100-500 L.

[0022] Preferably, the high-temperature sealed conditions involve hydrolysis in a high-pressure reactor at a temperature of 160-200°C for 2-8 hours. More preferably, the hydrolysis temperature is 200°C and the reaction time is 4 hours. Under these hydrothermal reaction conditions, the conversion rate of cellulose reaches as high as 98.90%, the yield of reducing sugars reaches 69.53%, and the yield of glucose reaches 43.89%.

[0023] Preferably, the furan platform compound includes furfural or 5-hydroxymethylfurfural.

[0024] Preferably, the cellulose raw material is pretreated before being mixed with the bifunctional carbon-based catalyst in a pure water system. The pretreatment involves dissolving dried cellulose in a phosphoric acid solution, heating and stirring, then adding ethanol to obtain a regenerated cellulose precipitate. The cellulose precipitate is then washed with deionized water, filtered, dried, and ground into powder for later use. Phosphoric acid pretreatment transforms the crystalline structure of cellulose from natural cellulose type I to cellulose type II, thereby reducing its crystallinity and degree of polymerization. This transformation is more conducive to the catalyst's hydrolysis of cellulose. The pretreated cellulose has a crystallinity between 0-70% and a degree of polymerization between 30-20000.

[0025] The bifunctional carbon-based catalyst prepared by this invention has higher stability and stronger adsorption and hydrolysis capabilities for cellulose. Its adsorption capacity is about 1.4 times that of undoped carbon-based microspheres, exhibiting a significant structural destruction effect. It can effectively break the aggregated structure on the surface of cellulose and destroy the dense hydrogen bond network. Boron hydroxyl groups work together with in-situ carboxyl groups on the surface to achieve high-value conversion and utilization of cellulose in the entire aqueous phase.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] (1) The preparation method of the bifunctional carbon-based catalyst in this invention is simple. A mixture of furan boronic acid and acetone aldehyde is used as a composite functional carbon source. A bifunctional carbon-based catalyst with strong adsorption boron hydroxyl and in-situ carboxyl groups is synthesized by hydrothermal co-carbonization in one step. The catalyst is in the form of microspheres with good sphericity and uniform size. There is no obvious adhesion between the microspheres.

[0028] (2) The bifunctional carbon-based catalyst of the present invention improves the surface activity of carbon materials through co-carbonization of furan boronic acid and acetone aldehyde, resulting in a catalyst containing more carboxyl and hydroxyl groups and exhibiting good water dispersibility. Compared to ordinary hydroxyl groups, boron hydroxyl groups effectively break the aggregate structure of cellulose through strong interfacial adsorption interactions, efficiently promoting the hydrolysis of cellulose into sugars in pure water systems. In addition, the catalyst exhibits excellent hydrothermal stability and reusability in catalytic cellulose conversion.

[0029] (3) The preparation method of the bifunctional carbon-based catalyst in this invention is simple to operate, green and environmentally friendly, and has low equipment requirements. It also overcomes the problems of poor reusability, unstable acid groups, low selectivity, and toxic solvents in the hydrolysis system of sulfonated carbon-based solid acids prepared by existing technologies in the catalysis of non-grain biomass conversion.

[0030] (4) The bifunctional carbon-based catalyst of the present invention can independently catalyze the hydrolysis of cellulose in a pure water system, thus constructing an acid-free, green and environmentally friendly cellulose hydrolysis system. This avoids the equipment corrosion problem caused by liquid acid, making it more economical, green and safe. Moreover, the water solvent system is the most ideal green solvent, and the product separation is simple. Attached Figure Description

[0031] Figure 1 The images show the microstructure of the catalysts prepared in the examples and comparative examples. Figure 1 (a) is a SEM image of the undoped furanboronic acid carbon spheres (P160-10) prepared in Comparative Example 1. Figure 1 (b) is a SEM image of the bifunctional carbon-based catalyst (FP160-10) prepared in Example 1.

[0032] Figure 2 The infrared spectra of the bifunctional carbon-based catalysts FP160-10, FP180-10 and FP200-10 prepared in Example 1 are shown.

[0033] Figure 3 The image shows a SEM image of the hydrolysis residue obtained after cellulose hydrolysis catalyzed by the bifunctional carbon-based catalyst FP160-10 prepared in Example 1. Figure 3 (a) and Figure 3 (b) SEM images of hydrolysis residues at different locations after hydrolysis reaction at 200℃ for 4 hours. Detailed Implementation

[0034] The present invention will be further illustrated below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0035] Example 1

[0036] In this embodiment, a bifunctional carbon-based catalyst is prepared by hydrothermal reaction of acetone aldehyde and furan boric acid with deionized water; cellulose is pretreated to prepare regenerated cellulose; then, the prepared bifunctional carbon-based catalyst and regenerated cellulose are mixed in deionized water and placed in a high-pressure reactor for hydrolysis. The specific steps are as follows:

[0037] (1) Dissolve 30g of dried cellulose in 200ml of 85% concentrated phosphoric acid and continuously stir mechanically at 50℃ to form a homogeneous cellulose solution. Then add ethanol to obtain regenerated cellulose precipitate. Pour the precipitate into deionized water, stir thoroughly, and filter. Repeat the washing, stirring, and filtering process until the filtrate is neutral. Finally, vacuum dry the precipitate for 12 hours and grind it into powder for later use.

[0038] (2) 3.36 g of furanylboric acid and 5.4 mL of 40% acetone aldehyde solution were mixed with 50 mL of deionized water and stirred for 12 h. The mixture was then transferred to a 100 mL polytetrafluoroethylene high-pressure reactor and hydrothermally reacted at 160 °C for 10 h. After cooling to room temperature, the product was washed five times each with deionized water and ethanol, dried for 24 h, and then ground into powder for later use. The prepared carbon material was named FP160-10. All FPs prepared at different reaction temperatures (160 °C, 180 °C, 200 °C) and different reaction times (6 h, 8 h, 10 h) were designated as FP160-6, FP160-8, FP160-10, FP180-6, FP180-8, FP180-10, FP200-6, FP200-8, and FP200-10, respectively.

[0039] (3) Add 0.1g of the pretreated cellulose in step (1), 0.1g of the bifunctional carbon-based catalyst FP160-10 prepared in step (2) and 20mL of deionized water to a 100mL polytetrafluoroethylene high-pressure reactor; after stirring thoroughly, the reactor is hydrolyzed at 180℃ for 6h at a speed of 30rpm. After the reaction is completed, the hydrolysis residue and hydrolysate are obtained by filtration.

[0040] Example 2

[0041] The difference between this embodiment and Example 1 is that the catalyst used in step (3) is a bifunctional carbon-based catalyst FP180-10.

[0042] Example 3

[0043] The difference between this embodiment and Example 1 is that the catalyst used in step (3) is a bifunctional carbon-based catalyst FP200-10.

[0044] Example 4

[0045] The difference between this embodiment and embodiment 1 is that the reaction vessel used in step (3) undergoes hydrolysis at 200°C for 4 hours.

[0046] Example 5

[0047] The difference between this embodiment and embodiment 4 is that the hydrolysis residue obtained in step (3) is dried and kept for later use in order to continuously test the recycling capacity of the bifunctional carbon-based catalyst FP160-10.

[0048] Example 6

[0049] The difference between this embodiment and embodiment 5 is that the hydrolysis residue added in step (3) is the hydrolysis catalyst used in this embodiment, in order to test the recycling capacity of the bifunctional carbon-based catalyst FP160-10.

[0050] Example 7

[0051] The difference between this embodiment and embodiment 6 is that the hydrolysis residue added in step (3) is the hydrolysis catalyst used in this embodiment, in order to test the recycling capacity of the bifunctional carbon-based catalyst FP160-10.

[0052] Example 8

[0053] The difference between this embodiment and embodiment 7 is that the hydrolysis residue added in step (3) is the hydrolysis catalyst used in this embodiment, in order to test the recycling capacity of the bifunctional carbon-based catalyst FP160-10.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is that acetone aldehyde carbon spheres without furanylboronic acid were hydrolyzed with regenerated cellulose in a high-pressure reactor. The specific preparation steps of the acetone aldehyde carbon spheres are as follows:

[0056] (1) Mix 5.4 mL of 40% acetone aldehyde solution with 50 mL of deionized water and stir for 12 h; then transfer the mixture to a 100 mL polytetrafluoroethylene high-pressure reactor and hydrothermally react at 160 °C for 10 h. After cooling to room temperature, wash the product five times each with deionized water and ethanol, then dry for 24 h and grind it into powder for later use. The prepared carbon material is named P160-10.

[0057] (2) Add 0.1g of cellulose pretreated in step (1) of Example 1, 0.1g of carbon material P160-10 obtained in step (1) of Comparative Example 1 and 20mL of deionized water to a 100mL polytetrafluoroethylene high-pressure reactor; after stirring thoroughly, the reactor is hydrolyzed at 180℃ for 6h at a speed of 30rpm. After the reaction is completed, the hydrolysis residue and hydrolysate are obtained by filtration.

[0058] Comparative Example 2

[0059] The difference between this comparative example and Example 1 is that the furan boronic acid raw material used in step (2) is changed to 1.86g of boric acid, and a carbon-based catalyst (BP160-10) is prepared by doping boric acid with acetone aldehyde, which is then applied to cellulose hydrolysis.

[0060] Test Result Analysis

[0061] The bifunctional carbon-based catalysts prepared in the above examples have particle sizes in the range of 1 nm to 7 μm. Specifically, the SEM image of the undoped furanboric acid carbon spheres (P160-10) prepared in Comparative Example 1 is shown below. Figure 1As shown in (a), the carbon material without furanoboric acid doping is in the form of microspheres with a small particle size and an average particle size of approximately 2.15 μm; while the SEM image of the bifunctional carbon-based catalyst (FP160-10) prepared in Example 1 is shown in Figure 1. Figure 1 As shown in (b), the carbon material is microspheres with good sphericity and large particle size, with an average particle size of approximately 5.67 μm.

[0062] Table 1 shows the carbon content of the catalysts and the boron hydroxyl content in the catalysts in the examples and comparative examples.

[0063] Example 1 Example 2 Example 3 Example 4 Example 5 Carbon content (g) 0.52 0.51 0.50 0.51 0.52 <![CDATA[ 1 Boron hydroxyl content (mg / kg) 1188.0 542.5 306.0 -- -- <![CDATA[ 2 Boron hydroxyl content (mmol / g) 0.110 0.050 0.028 -- -- Example 6 Example 7 Example 8 Comparative Example 1 Comparative Example 2 Carbon content (g) 0.51 0.53 0.53 0.42 0.40 <![CDATA[ 1 Boron hydroxyl content (mg / kg) -- -- -- 0.0 532.5 <![CDATA[ 2 Boron hydroxyl content (mmol / g) -- -- -- 0.000 0.049

[0064] Wherein, carbon content represents the mass of the catalysts prepared in the examples and comparative examples; 1 Boron hydroxyl content indicates the mass content of boron hydroxyl groups (B(OH)2) per kilogram of catalyst; 2 The boron hydroxyl content indicates the molar content of boron hydroxyl (B(OH)2) per gram of catalyst.

[0065] like Figure 2 As shown, the infrared spectrum of the bifunctional carbon-based catalyst prepared in Example 1 is in the range of 3000-3700 cm⁻¹. -1 The presence of a broad peak at 1160 cm⁻¹ indicates that the catalyst contains abundant hydroxyl groups. -1 The appearance of vibrational peaks belonging to B-OH indicates successful boron doping, with boron hydroxyl groups successfully introduced onto the catalyst surface. The boron content in the catalyst was further quantitatively measured using inductively coupled plasma atomic emission spectrometry (ICP-AES), as shown in Table 1. The boron hydroxyl content of the FP160-10 catalyst prepared in Example 1 was 0.110 mmol / g, while the boron hydroxyl content of the BP160-10 catalyst prepared in Comparative Example 2 was 0.049 mmol / g. The boron hydroxyl content of FP160-10 was twice that of BP160-10. This indicates that compared to boric acid doping, co-carbonization via a mixture of furanoboric acid and acetone aldehyde can introduce more boron hydroxyl groups, resulting in better catalysis of cellulose hydrolysis.

[0066] SEM images of the cellulose hydrolysis reaction process using the bifunctional carbon-based catalyst (FP160-10) in Example 4 are shown below. Figure 3 As shown. By Figure 3 As can be seen, the prepared bifunctional carbon-based catalyst (FP160-10) is tightly adsorbed onto the surface of cellulose, and even embedded inside it, thereby tearing large pieces of cellulose into fragments. Figure 3 As shown in b, the prepared bifunctional carbon-based catalyst stripped cellulose into strips. This indicates that the bifunctional carbon-based catalyst can effectively break down the surface structure of cellulose and improve its hydrolytic reactivity.

[0067] Based on adsorption experiments and calculations, the adsorption capacity of the bifunctional carbon-based catalyst (FP160-10) prepared in Example 1 to cotton cellulose was 528 mg / g, while the adsorption capacity of P160-10 prepared in Comparative Example 1 to cotton cellulose was 390 mg / g. The adsorption capacity of FP160-10 to cellulose was 1.4 times that of P160-10.

[0068] The hydrolysates obtained in the above examples and comparative examples were tested for reducing sugar concentration using the DNS method. The specific operating method is as follows:

[0069] Take 3 mL of hydrolysate and 3 mL of DNS reagent, mix them, and develop the color at 90 °C for 15 min. Measure the absorbance of the developed solution at 540 nm, and calculate the reducing sugar yield (Y) according to formula (I). TRS ):

[0070]

[0071] In formula (I), C TRS V represents the concentration of reducing sugar (g / L); V represents the volume of hydrolysate (L); m RC This indicates the initial mass (g) of cellulose before the reaction.

[0072] Cellulose conversion rate (X) con. Calculate according to formula (II):

[0073]

[0074] In formula (II), m RC Indicates the initial mass (g) of cellulose before the reaction; m rRC This indicates the mass (g) of cellulose after the reaction.

[0075] The glucose yield in the hydrolysate was determined by high-performance liquid chromatography (HPLC), under the following specific test conditions:

[0076] The glucose concentration in the hydrolysate was determined using an Agilent 1260 chromatographic column (HPX-87H), with a mobile phase of dilute sulfuric acid / water, a flow rate of 0.5 mL / min, and a column temperature of 26 °C. The glucose yield (Y) was also measured. Glu. Calculate according to formula (III):

[0077]

[0078] In formula (III), C glu. V represents the glucose concentration in the hydrolysate (g / L); V represents the volume of the hydrolysate (L); m RC This indicates the initial mass (g) of cellulose before the reaction.

[0079] The conversion rates of cellulose hydrolysis, the yields of reducing sugars and glucose in the examples and comparative examples calculated using formulas (I), (II), and (III) are shown in Table 1.

[0080] Table 2. Cellulose hydrolysis results in Examples 1-8 and Comparative Examples 1-2

[0081] Example 1 Example 2 Example 3 Example 4 Example 5 Cellulose conversion rate (%) 73.56 65.11 59.73 98.90 98.53 Reducing sugar yield (%) 46.27 41.12 37.25 69.53 68.57 Glucose yield (%) 30.94 27.56 24.61 43.89 42.30 Example 6 Example 7 Example 8 Comparative Example 1 Comparative Example 2 Cellulose conversion rate (%) 99.27 98.76 97.44 51.48 69.38 Reducing sugar yield (%) 69.20 68.45 66.92 37.01 43.45 Glucose yield (%) 43.55 42.78 42.02 24.51 27.52

[0082] Table 2 shows that, compared with P160-10 in Comparative Example 1, the bifunctional carbon-based catalyst (FP160-10) can greatly promote the hydrolysis and conversion of cellulose through the synergistic effect of boron hydroxyl and carboxyl groups. It can achieve efficient hydrolysis of cellulose independently in a pure water system, making it an economical and green hydrolysis method. Compared with BP160-10 in Comparative Example 2, the FP160-10 catalyst in Example 1 contains more boron hydroxyl groups and has better efficiency in catalytic hydrolysis of cellulose. Comparing Examples 1 and 2 and Example 3, the hydrolysis efficiency of the bifunctional carbon-based catalyst prepared at 160℃ is better than that of the bifunctional carbon-based catalysts prepared at 180℃ and 200℃. This indicates that 160℃ is the optimal preparation temperature for bifunctional carbon-based catalysts, as this temperature retains more oxygen-containing functional groups on the catalyst surface. Combining Examples 4 and 5-8, the bifunctional carbon-based catalyst (FP160-10) showed no decrease in catalytic efficiency after five cycles of hydrolysis, indicating that the catalyst maintained high catalytic activity and had excellent recyclability.

[0083] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A bifunctional carbon-based catalyst, characterized in that, The bifunctional carbon-based catalyst is a boron-carbon-based microsphere with a particle size of 1 nm-7 μm, which is prepared by hydrothermal co-carbonization reaction using furan boric acid and acetone aldehyde as raw materials; wherein the temperature of the hydrothermal co-carbonization reaction is 160-200℃ and the reaction time is 6-10 h.

2. The bifunctional carbon-based catalyst according to claim 1, characterized in that, The acetone aldehyde is a acetone aldehyde solution with a volume fraction of 30-70%, and the mass-to-volume ratio of furanboric acid to acetone aldehyde solution is 1 kg: 1-10 L.

3. The bifunctional carbon-based catalyst according to claim 2, characterized in that, The volume ratio of the acetone aldehyde solution to deionized water is 1:10-100.

4. The application of the bifunctional carbon-based catalyst according to any one of claims 1-3 in the hydrolysis of cellulose into sugar in a pure aqueous phase.

5. The application according to claim 4, characterized in that, In application, the bifunctional carbon-based catalyst is mixed with cellulose in a pure water system, and the cellulose is hydrolyzed and converted under high temperature and closed conditions to obtain sugars and furan platform compounds.

6. The application according to claim 5, characterized in that, The mass ratio of the bifunctional carbon-based catalyst to cellulose is 1:0.1-10.

7. The application according to claim 5 or 6, characterized in that, The cellulose mentioned includes one or more of microcrystalline cellulose, regenerated cellulose, corn cob cellulose, straw cellulose, viscose cellulose, cotton cellulose, and cuprammonium cellulose.

8. The application according to claim 7, characterized in that, Before mixing the bifunctional carbon-based catalyst with cellulose in a pure water system, the cellulose is pretreated. The pretreated cellulose has a crystallinity of 0-70% and a degree of polymerization of 30-20000.

9. The application according to claim 8, characterized in that, The high-temperature sealed conditions refer to the hydrolysis reaction being carried out in a high-pressure reactor at a temperature of 160-200℃ for a reaction time of 2-8 hours.

Images