A method for co-producing furfural and graphene from sugarcane

Abstract

The present invention discloses a method for co-producing furfural and graphene from sugarcane, which includes: drying, pulverizing, and sieving sugarcane bagasse to obtain sugarcane powder; mixing the sugarcane powder, water, γ-valerolactone solution, and CoCl2·6H2O to obtain a mixed solution; subjecting the mixed solution to hydrothermal reaction to obtain a filtrate and hydrothermal residue; mixing the filtrate with ethyl acetate, stirring, and performing phase separation to obtain an organic phase, and distilling and condensing the organic phase to obtain furfural; drying the hydrothermal residue and mixing it with carbon black in a mass ratio of 4-5:1, grinding to obtain a mixed powder, and performing Joule heat reaction on the mixed powder under vacuum conditions to obtain graphene. Using this method, furfural and graphene can be obtained from sugarcane.

Description

Technical Field

[0001] The invention relates to a biomass resource utilization technology, and in particular to a method for co-producing furfural and graphene from sugarcane. Background Art

[0002] Against the backdrop of growing global energy demand and increasing environmental protection pressure, the development of efficient renewable resource utilization technologies has become the key to resolving the contradiction between energy and the environment, and the comprehensive utilization of biomass has received extensive attention. Bagasse, as the main byproduct of the sugar industry, is usually regarded as low-value waste. However, bagasse is rich in organic components such as cellulose, hemicellulose and lignin, and has a high potential for reuse.

[0003] As an important thermochemical conversion pathway, hydrothermal method can efficiently convert biomass into high value-added chemicals through high temperature and high pressure hydrolysis reaction. Furfural is an important chemical raw material that can be used in a variety of products such as synthetic resins, solvents, medicines and fragrances. It has attracted much attention from researchers due to its wide range of industrial uses.

[0004] The production of furfural by hydrothermal method can not only effectively utilize waste biomass resources and reduce environmental burden, but also partially replace traditional petrochemical raw materials, promoting green chemistry and sustainable development. The traditional method of preparing furfural from sugarcane bagasse mainly produces pentose by acid-catalyzed hydrolysis of hemicellulose, and then forms furfural through dehydration reaction.

[0005] The invention patent with publication number CN107199028A discloses a solid acid catalyst and its preparation method and application and method for preparing furfural compounds. The solid acid catalyst has an amorphous structure and a chemical formula of Al x Si y O (3x+4y) / 2 , wherein y:x=0.25-200:1. The method for preparing a solid acid catalyst comprises preparing a silicon source and an aluminum source into a dry glue in the presence of a hydrolyzing agent, aging the dry glue, washing and roasting the aged material in sequence, and the molar ratio of the silicon source to the aluminum source is 0.25-200:1. The method for preparing a furfural compound comprises causing a biomass raw material to undergo an intramolecular dehydration reaction in the presence of a solid acid catalyst, a reaction medium and a selectively used promoter. The patent also discloses the use of a solid acid catalyst in catalyzing an intramolecular dehydration reaction.

[0006] However, the hydrothermal residues produced in the process disclosed in the above patents are often not fully utilized or even ignored. These hydrothermal residues contain unhydrolyzed cellulose, hemicellulose and other biomass components, and their potential value has not been fully explored. Although current technology has made certain progress in biomass conversion, it has failed to effectively utilize the full potential of sugarcane bagasse, and there are problems of high energy consumption and low resource utilization. Therefore, it is of great theoretical and practical significance to explore a method for efficiently utilizing hydrothermal residues and realize the comprehensive resource utilization of sugarcane bagasse.

[0007] At the same time, graphene has shown great application prospects in the fields of electronic devices, energy storage and composite materials due to its excellent electrical, mechanical and thermal properties. Joule heat rapid synthesis technology can efficiently convert precursor materials into high-quality graphene by adjusting the discharge voltage and reaction time, which not only improves production efficiency, but also saves energy and has the characteristics of low energy consumption.

[0008] Therefore, there is an urgent need to develop a technology for resource utilization of bagasse with high efficiency, low energy consumption and high value-added products, and a process for efficiently utilizing bagasse to simultaneously produce furfural and graphene, which can not only realize the resource utilization of agricultural waste, but also significantly improve its economic value and environmental benefits. Summary of the invention

[0009] The invention provides a method for co-producing furfural and graphene from sugarcane. The method can be used to obtain furfural and graphene from sugarcane.

[0010] The present invention provides a method for co-producing furfural and graphene from sugarcane, comprising:

[0011] (1) drying, crushing and screening bagasse to obtain sugarcane powder;

[0012] (2) mixing sugarcane powder, water, γ-valerolactone solution, and CoCl2·6H2O to obtain a mixed solution;

[0013] (3) subjecting the mixed solution to a hydrothermal reaction to obtain a filtrate and a hydrothermal residue;

[0014] (4) mixing the filtrate with ethyl acetate, stirring, and phase separation to obtain an organic phase, and distilling and condensing the organic phase to obtain furfural;

[0015] The hydrothermal residue is dried and mixed with carbon black in a mass ratio of 4 to 5:1, and ground to obtain a mixed powder, and the mixed powder is subjected to a Joule heat reaction under vacuum conditions to obtain graphene.

[0016] The present invention obtains a hydrothermal residue with a high degree of carbonization through catalyst catalysis and hydrothermal reaction. Since the hydrothermal residue provided by the present invention has a high degree of carbonization, a large amount of heat under the Joule heat reaction is used for the conversion of graphene, thereby obtaining graphene with better quality.

[0017] Preferably, the liquid-to-solid ratio of water to sugarcane powder is 3 to 15:1 L / kg;

[0018] The liquid-to-solid ratio of the γ-valerolactone solution to the sugarcane powder is 15-27:1 L / kg;

[0019] The concentration of the CoCl2·6H2O is 0.3-0.5M.

[0020] The present invention strengthens the Co by adding γ-valerolactone solution 2+ The Lewis acid properties can more effectively promote the hydrolysis and dehydration of hemicellulose, while obtaining a high yield of furfural and enhancing the carbonization degree of the hydrothermal residue.

[0021] Preferably, the temperature of the hydrothermal reaction is 170-185°C, and the insulation time is 15-60 minutes. The generation of furfural is mainly achieved through the dehydration reaction of hemicellulose. Studies have shown that within the temperature range of 170-185°C, the dehydration reaction rate of hemicellulose is high, and furfural can be effectively generated. Moreover, within this temperature range, the decomposition of furfural or the generation of by-products caused by high temperature can be avoided, thereby increasing the yield of furfural. The insulation time of 15-60 minutes not only ensures that the biomass is fully carbonized, but also provides sufficient reaction time for the pentose to dehydrate and generate furfural. Within this time range, the optimal balance point for the generation of furfural can be reached: too short may result in incomplete generation of furfural, and too long may result in degradation of furfural or instability of the reaction system.

[0022] Preferably, the cooling time of the hydrothermal reaction is 30 to 60 minutes, and the cooling method is ice-cooling. After furfural is generated, if the reactants continue to be kept at high temperature for a long time, furfural may degrade or participate in further reactions, resulting in a decrease in yield. Rapid cooling, especially using ice-cooling, can quickly reduce the temperature and avoid the decomposition of furfural at high temperature, thereby maximizing the preservation of the generated furfural. A cooling time of 30 to 60 minutes is sufficient to reduce the system temperature to a stable range, so that furfural remains in a stable dissolved state in the solution, which is convenient for subsequent extraction and separation operations.

[0023] Preferably, the volume ratio of the hydrothermal reactor volume to the mixed solution is 1.7 to 2:1. The appropriate ratio of the reactor volume to the solution volume ensures that the pentose has sufficient reaction space in the hydrothermal reaction, and the reaction efficiency will not be affected by too much or too little solution. This ratio range can ensure that the reactants react fully at an appropriate concentration and increase the production rate of furfural. The larger reactor volume provides sufficient space so that furfural can quickly diffuse into the solution after generation, reducing the possibility of further reaction with other reactants. This optimization ensures that furfural can achieve a higher yield in a shorter time without affecting the degree of carbonization of the carbonaceous material.

[0024] Preferably, the specific steps of step (1) are:

[0025] The sugarcane bagasse is dried at 60-80° C. for 10-12 hours, the dried sugarcane bagasse is crushed, and then sieved using a 40-80 mesh filter screen to obtain sugarcane powder.

[0026] Preferably, the stirring time of step (4) is 1 to 2 hours. By controlling the stirring time, the furfural in the filtrate is transferred from the aqueous phase to the organic phase.

[0027] Preferably, the distillation and condensation of the organic phase to obtain furfural comprises the following steps:

[0028] The organic phase is heated to the boiling point of furfural to evaporate the furfural, which is then collected by condensation.

[0029] Preferably, subjecting the mixed powder to a Joule heat reaction under vacuum conditions to obtain graphene comprises the following steps:

[0030] Put the mixed powder into a quartz tube, seal the two ends of the quartz tube with copper wire plugs and graphite plugs, then put the quartz tube into a Joule heat reaction box, and evacuate the reaction box to a vacuum degree of 0.008-0.01MPa;

[0031] Then, flash discharge is performed, wherein the voltage of the flash discharge is 160-170V, the capacitance of the capacitor bank is 90mF, and the discharge time is 2-3s.

[0032] Preferably, the mass of the mixed powder is 0.1-0.15 g, and the inner diameter of the quartz tube is 8-10 mm.

[0033] Preferably, the copper wire plug has a thickness of 1 to 1.5 cm.

[0034] Preferably, the resistance value during flash discharge is 1-10Ω.

[0035] Description of the invention principle:

[0036] The technical problem to be solved by the present invention is to obtain a higher furfural yield by regulating the hydrothermal conditions. At the same time, the hydrothermal conditions can regulate the material structure of the hydrothermal residue, so as to prepare higher quality graphene at the back end.

[0037] The technical principle of the present invention combining the hydrothermal method with the Joule heat rapid synthesis technology to generate furfural and graphene is as follows:

[0038] 1. Hydrothermal production of furfural and highly carbonized residues: First, under hydrothermal conditions, the hemicellulose contained in the bagasse is first hydrolyzed to generate five-carbon sugars such as xylose. Xylose removes three water molecules under high temperature and acidic conditions to form furfural. The incompletely converted carbohydrates are pyrolyzed at high temperature to gradually generate stable aromatic structures and finally form carbonized residues. The key to achieving high furfural yields and highly carbonized residues lies in the optimization of reaction conditions, including the control of solvents, temperature and reaction time.

[0039] Co 2+ As a Lewis acid, it can coordinate the hydroxyl groups in the hemicellulose molecules and reduce the dissociation energy of the CO bond by forming a coordination bond with the oxygen atom. In a mixed solution of γ-valerolactone solution and water, Co 2+ The Lewis acid performance of GVL is enhanced in the polar non-proton environment of GVL, thereby more effectively promoting the hydrolysis and dehydration of hemicellulose. This solution environment accelerates the dehydration and carbonization process of residual organic matter, making it easier for the residue to form a stable structure rich in carbon. Therefore, the present invention selects a reasonable mixed solution of γ-valerolactone and water, adds CoCl2·6H2O at the same time, and a suitable hydrothermal reaction temperature, which can effectively promote the hydrolysis and dehydration reaction of xylose, reduce the generation of by-products, and accelerate the pyrolysis and carbonization reaction of organic matter to form a dense carbon-based structure. The appropriate insulation time can ensure that xylose fully reacts to generate furfural, while avoiding further degradation of furfural due to too long a time, and also avoiding excessive degradation or insufficient carbonization of carbonized matter. Through the above steps, the hemicellulose in sugarcane bagasse is efficiently converted into furfural, and the generated furfural is extracted from the reaction mixture by separation techniques such as distillation, and its purity is improved by subsequent purification steps, realizing the high-value utilization of agricultural waste and producing residues with a high degree of carbonization. These hydrothermal residues with a high degree of carbonization absorb less heat when heated to the same temperature, thus providing an ideal precursor material for the subsequent generation of high-quality graphene by Joule heating treatment.

[0040] 2. Rapid synthesis of graphene by Joule heat: The hydrothermal residue is mainly composed of a high content of carbon substances. Through hydrothermal reaction under high temperature and high pressure conditions, these carbon residues have good structural characteristics and are suitable as graphene precursors. Mix the hydrothermal residue and carbon black in a suitable proportion and grind and mix them thoroughly. The amount of carbon black added is determined according to the optimization results of the previous experiments, which can significantly improve the yield and quality of graphene. In the Joule heat rapid synthesis technology, the copper wire plug is used to buffer the pressure of the gas volatiles released by the substance during the Joule heat process; the flash evaporation parameters are optimized according to the pyrolysis characteristics of the carbonaceous material and the formation mechanism of graphene to ensure that the carbon atoms have sufficient kinetic energy and activity to achieve atomic rearrangement and form sp 2 The hybrid carbon-carbon bond structure generates graphene sheets. The core advantage of this process lies in its extremely high heating rate and efficient synthesis of graphene in a short time. Compared with the traditional pyrolysis method, the Joule heat rapid synthesis technology has higher energy efficiency and time efficiency. By precisely controlling the current intensity and action time, the number and quality of graphene layers can be adjusted to prepare high-quality graphene materials. After the discharge is completed, wait for the quartz tube to cool to room temperature to obtain high-quality graphene.

[0041] Through the above technical route, the present invention realizes the comprehensive resource utilization of bagasse, efficiently converts organic matter into high-value-added furfural and high-quality graphene, has significant economic and environmental benefits, and provides a new technical path for the efficient utilization of renewable resources and the large-scale production of graphene.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The present invention utilizes a catalyst to hydrolyze bagasse to obtain furfural with a high yield and can also obtain a hydrothermal residue with a high carbonization degree. The present invention subjects the hydrothermal residue with a high carbonization degree to a Joule heat reaction. Compared with the existing method of directly subjecting biomass to a Joule heat reaction, the hydrothermal residue provided by the present invention has a high carbonization degree, which reduces the heat required for carbonization, so that a large amount of heat is used for graphitization, thereby obtaining graphene with higher quality. Compared with a comparative example of a catalytic system without adding gamma-valerolactone and CoCl2, the quality of graphene materials synthesized by Joule heat of hydrothermal catalytic conversion residue is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A flow chart of a method for co-producing furfural and graphene from sugarcane provided in a specific embodiment of the present invention.

[0045] Figure 2 This is a graph of furfural yields obtained in Example 1 and Examples 4 to 6 of the present invention;

[0046] Figure 3I is the graphene obtained in Example 1 of the present invention and Comparative Example 1 D / I G Raman statistics diagram;

[0047] Figure 4 I is the graphene obtained in Example 1 of the present invention and Comparative Example 1 2D / I G Raman statistics diagram;

[0048] Figure 5 The differential scanning calorimetry (DSC) diagrams of the hydrothermal residues obtained in Example 1 of the present invention and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0049] The present invention is further described below by way of embodiments in conjunction with the accompanying drawings, but the present invention is not limited thereto.

[0050] In order to co-produce high-yield furfural and high-quality graphene, a specific embodiment of the present invention provides a method for co-producing furfural and graphene from sugarcane, such as Figure 1 As shown, including:

[0051] (1) drying, crushing and screening bagasse to obtain sugarcane powder;

[0052] (2) mixing sugarcane powder, water, γ-valerolactone solution, and CoCl2·6H2O to obtain a mixed solution;

[0053] (3) subjecting the mixed solution to a hydrothermal reaction to obtain a filtrate and a hydrothermal residue;

[0054] (4) mixing the filtrate with ethyl acetate, stirring, and phase separation to obtain an organic phase, and distilling and condensing the organic phase to obtain furfural;

[0055] The hydrothermal residue is dried, mixed with carbon black in a mass ratio of 4 to 5:1, and ground to obtain a mixed powder, and the mixed powder is subjected to a Joule heat reaction under vacuum conditions to obtain graphene.

[0056] Example 1

[0057] (1) 2 g of bagasse was dried in an oven at 80° C. for 12 hours, the dried bagasse was pulverized, and then sieved using a 40-mesh filter.

[0058] (2) Pour bagasse into a temperature-controlled sealed reactor, add water at a liquid-solid ratio of 6:1 L / kg, add γ-valerolactone solution at a liquid-solid ratio of 24:1 L / kg, and add 0.5 M CoCl2·6H2O at the same time, and mix well.

[0059] (3) After the reactor was sealed, the insulation time was set to 30 min and the temperature was set to 170° C. After the reaction was completed, the hydrothermal reactor was taken out and cooled for 60 min.

[0060] (4) Open the hydrothermal reactor and filter the solution to obtain a filtrate and a hydrothermal residue. Mix the filtrate with ethyl acetate and stir for 2 h to allow furfural to migrate from the aqueous phase to the organic phase. Then use a separatory funnel to separate the phases and collect the organic phase.

[0061] (5) The extracted organic phase was added to a distillation flask, heated to the boiling point of furfural (about 161° C.) to evaporate the furfural, and then condensed to collect pure furfural. The yield of furfural was 65%.

[0062] (6) After the hydrothermal residue was dried at 105° C., the hydrothermal residue was subjected to XPS characterization, and the carbon content was 52%. Carbon black was added in a ratio of 5:1 between the hydrothermal residue and carbon black, and the two were fully ground and mixed.

[0063] (7) Weigh 0.1 g of the mixed substance and put it into a quartz tube with an inner diameter of 8 mm. Use copper wire plugs and graphite plugs to seal the two ends. The resistance value at this time is 7.5 Ω. Put the assembled quartz tube into the Joule heat reaction box, evacuate the reaction box, and ensure that the vacuum degree during the reaction is 0.008 MPa;

[0064] (8) The discharge mode of the Joule heat device is set to flash discharge, the flash discharge voltage is 170 V, the capacitor bank capacitance is 90 mF, and the discharge time is 3 s.

[0065] (9) After the discharge is completed, the quartz tube is cooled to room temperature to obtain graphene. The graphene is characterized by Raman spectroscopy to obtain I D / I G The average value is 0.64, I 2D / I G The average value is 0.62.

[0066] Example 2

[0067] (1) 2 g of bagasse was dried in an oven at 80° C. for 12 hours, the dried bagasse was crushed, and then sieved using a 40-mesh filter screen;

[0068] (2) Pour the bagasse into a temperature-controlled sealed reactor, add water at a liquid-solid ratio of 10:1 L / kg, add γ-valerolactone solution at a liquid-solid ratio of 20:1 L / kg, and add 0.3 M CoCl2·6H2O at the same time, and mix well;

[0069] (3) After the reactor was sealed, the insulation time was set to 30 min and the temperature was set to 170° C. After the reaction was completed, the hydrothermal reactor was taken out and cooled for 60 min.

[0070] (4) Open the hydrothermal reactor and filter the solution to obtain a filtrate and a hydrothermal residue. Mix the filtrate with ethyl acetate and stir for 2 h to allow furfural to migrate from the aqueous phase to the organic phase. Then use a separatory funnel to separate the phases and collect the organic phase.

[0071] (5) The extracted organic phase was added to a distillation flask and heated to the boiling point of furfural (about 161° C.) to evaporate the furfural, and then the pure furfural was collected by condensation. The yield of furfural was 60%.

[0072] (6) After the hydrothermal residue was dried at 105° C., the hydrothermal residue was subjected to XPS characterization, and the carbon content was 50%. Carbon black was added according to a ratio of 5:1 between the hydrothermal residue and carbon black, and the two were fully ground and mixed.

[0073] (7) Weigh 0.12 g of the mixed substance and put it into a quartz tube with an inner diameter of 8 mm. Use copper wire plugs and graphite plugs to seal the two ends. The resistance value at this time is 9.2 Ω. Put the assembled quartz tube into the Joule heat reaction box, evacuate the reaction box, and ensure that the vacuum degree during the reaction is 0.01 MPa;

[0074] (8) The discharge mode of the Joule heat device is set to flash discharge, the flash discharge voltage is 160 V, the capacitor bank capacitance is 90 mF, and the discharge time is 3 s.

[0075] (9) After the discharge is completed, the quartz tube is cooled to room temperature to obtain graphene. The graphene is characterized by Raman spectroscopy to obtain I D / I G The average value is 0.67, I 2D / I G The average value is 0.58.

[0076] Example 3

[0077] (1) 2 g of bagasse was dried in an oven at 80° C. for 12 hours, the dried bagasse was crushed, and then sieved using an 80-mesh filter screen;

[0078] (2) Pour the bagasse into a temperature-controlled sealed reactor, add water at a liquid-solid ratio of 3:1 L / kg, add γ-valerolactone solution at a liquid-solid ratio of 27:1 L / kg, and add 0.4 M CoCl2·6H2O at the same time, and mix well;

[0079] (3) After the reactor was sealed, the insulation time was set to 30 min and the temperature was set to 170° C. After the reaction was completed, the hydrothermal reactor was taken out and cooled for 60 min.

[0080] (4) Open the hydrothermal reactor and filter the solution to obtain a filtrate and a hydrothermal residue. Mix the filtrate with ethyl acetate and stir for 2 h to allow furfural to migrate from the aqueous phase to the organic phase. Then use a separatory funnel to separate the phases and collect the organic phase.

[0081] (5) The extracted organic phase was added to a distillation flask and heated to the boiling point of furfural (about 161° C.) to evaporate the furfural, and then the pure furfural was collected by condensation. The yield of furfural was 63%.

[0082] (6) After the hydrothermal residue was dried at 105° C., the hydrothermal residue was subjected to XPS characterization, and the carbon content was 48%. Carbon black was added in a ratio of 4:1 between the hydrothermal residue and carbon black, and the two were fully ground and mixed.

[0083] (7) Weigh 0.15 g of the mixed substance and put it into a quartz tube with an inner diameter of 8 mm. Use copper wire plugs and graphite plugs to seal the two ends. The resistance value at this time is 8.4 Ω. Put the assembled quartz tube into the Joule heat reaction box, evacuate the reaction box, and ensure that the vacuum degree during the reaction is 0.009 MPa;

[0084] (8) The discharge mode of the Joule heat device is set to flash discharge, the flash discharge voltage is 170 V, the capacitor bank capacitance is 90 mF, and the discharge time is 2 s.

[0085] (9) After the discharge is completed, the quartz tube is cooled to room temperature to obtain graphene. The graphene is characterized by Raman spectroscopy to obtain I D / I G The average value is 0.7, I 2D / I G The average value is 0.55.

[0086] Embodiment 4-embodiment 6:

[0087] The difference from Example 1 is that the hydrothermal time is 15 min, 45 min and 60 min respectively. Figure 2 As shown, the furfural yields of Examples 4 to 6 are all higher than 60%.

[0088] Comparative Example 1

[0089] (1) 2 g of bagasse was dried in an oven at 80° C. for 12 hours, the dried bagasse was crushed, and then sieved using an 80-mesh filter screen;

[0090] (2) Pour the bagasse into a temperature-controlled sealed reactor, add water at a liquid-to-solid ratio of 30:1 L / kg, and mix well;

[0091] (3) After the reactor was sealed, the insulation time was set to 30 min and the temperature was set to 170° C. After the reaction was completed, the hydrothermal reactor was taken out and cooled for 60 min.

[0092] (4) Open the hydrothermal reactor and filter the solution to obtain a filtrate and a hydrothermal residue. Mix the filtrate with ethyl acetate and stir for 2 h to allow furfural to migrate from the aqueous phase to the organic phase. Then use a separatory funnel to separate the phases and collect the organic phase.

[0093] (5) The extracted organic phase was added to a distillation flask, heated to the boiling point of furfural (about 161° C.) to evaporate the furfural, and then condensed to collect pure furfural. The yield of furfural was 15%.

[0094] (6) After the hydrothermal residue was dried at 105° C., the hydrothermal residue was subjected to XPS characterization, and the carbon content was 22%. Carbon black was added in a ratio of 4:1 between the hydrothermal residue and carbon black, and the two were fully ground and mixed.

[0095] (7) Weigh 0.15 g of the mixed substance and put it into a quartz tube with an inner diameter of 8 mm. Use copper wire plugs and graphite plugs to seal the two ends. The resistance value at this time is 25 Ω. Put the assembled quartz tube into the Joule heat reaction box, evacuate the reaction box, and ensure that the vacuum degree during the reaction is 0.009 MPa;

[0096] (8) The discharge mode of the Joule heat device is set to flash discharge, the flash discharge voltage is 170 V, the capacitor bank capacitance is 90 mF, and the discharge time is 2 s.

[0097] (9) After the discharge is completed, the quartz tube is cooled to room temperature to obtain graphene. The graphene is characterized by Raman spectroscopy to obtain I D / I G The average value is 0.92, I 2D / I G The average value is 0.3.

[0098] Compared with Example 1, the difference is that the bagasse is poured into the temperature-controlled sealed reactor, and the γ-valerolactone solution and CoCl2·6H2O are not added. Due to the lack of catalyst in the hydrothermal system, the furfural yield obtained is 15%, which is a low yield. At the same time, the carbonization degree of the hydrothermal residue obtained is low, and the quality of the graphene obtained when used as a Joule heat precursor is also worse.

[0099] Comparative Example 2

[0100] Compared with Example 1, the difference is that the bagasse is poured into a temperature-controlled sealed reactor, and a γ-valerolactone solution is added at a liquid-solid ratio of 30:1L / kg, and 0.1M CoCl2·6H2O is added at the same time and mixed evenly. Since the proportion of γ-valerolactone in the hydrothermal system is too high and the amount of CoCl2·6H2O is too small, the hydrolysis and catalytic effects of the system are weakened, so the yield of furfural obtained is reduced to 10%, and the carbonization degree of the hydrothermal residue obtained is low. The hydrothermal residue is subjected to XPS characterization, and the carbon content is 25%. The quality of the graphene obtained as a Joule heat precursor is also worse. The graphene is subjected to Raman characterization, and I D / I G The average value is 0.9, I 2D / I G The average value is 0.32.

[0101] Comparative Example 3

[0102] Compared with Example 1, the difference is that the bagasse is poured into a temperature-controlled sealed reactor. After the reactor is sealed, the insulation time is set to 120 minutes and the temperature is set to 190°C. After the reaction is completed. The yield of furfural is 30%. Because the reaction temperature is too high and the time is too long, furfural is further converted into other by-products, and the yield is greatly reduced. At the same time, the carbonization degree of the hydrothermal residue obtained is low. The hydrothermal residue is subjected to XPS characterization treatment, and the carbon content is 30%. The quality of graphene obtained as a precursor of Joule heat is also worse. The graphene is subjected to Raman characterization to obtain I D / I G The average value is 0.86, I 2D / I G The average value is 0.35.

[0103] Performance Analysis:

[0104] like Figure 2 As shown, the furfural yields corresponding to Examples 1, 4, 5, and 6 are relatively high, but when the hydrothermal time is 15 min and 60 min, the yields are all reduced. A hydrothermal time of 30-45 min is a further preferred range.

[0105] like Figure 3 As shown, the defect degree of graphene obtained in Example 1 (patented catalytic system) and Comparative Example 1 (pure water system) is characterized (I D / I G , the smaller the value, the lower the defect degree, indicating that compared with pure water, the graphene obtained in Example 1 is of higher quality).

[0106] like Figure 4 As shown, the number of layers of graphene obtained in Example 1 (patented catalytic system) and Comparative Example 1 (pure water system) is characterized (I 2D / IG , the larger the value, the fewer the number of graphene layers, indicating that compared with pure water, the quality of graphene prepared in Example 1 is better).

[0107] like Figure 5 As shown, the energy consumed during the heating process of the hydrothermal conversion residue in Example 1 (patented catalytic system) is compared with that in Comparative Example 1 (pure water system). It can be seen that the energy consumed during the heating process of the hydrothermal conversion residue in Example 1 is much less than that in Comparative Example 1. Therefore, its temperature rises higher in the subsequent process of synthesizing graphene, and the quality of graphene is better.

[0108] The specific embodiment of the present invention proposes an efficient method for simultaneously producing furfural and graphene using waste bagasse, combining the hydrothermal method and Joule heat rapid synthesis technology, and realizing efficient resource utilization of bagasse by precisely controlling the reaction conditions. Under hydrothermal conditions, the yield of furfural is significantly improved through the synergistic effect of Co2+ catalysis and γ-valerolactone solution, while promoting the hydrothermal carbonization of biomass, and using the hydrothermal residue as a precursor, the rapid synthesis of high-quality graphene is achieved through Joule heat technology. This method not only has the advantages of high efficiency and low energy consumption, but also effectively reduces environmental pollution, conforms to the principles of green chemistry, and significantly improves economic benefits, providing an innovative technical path for the comprehensive utilization of biomass resources and the large-scale production of graphene.

Claims

1. A method for co-producing furfural and graphene from sugarcane, characterized in that: include: (1) drying, crushing and screening bagasse to obtain sugarcane powder; (2) mixing sugarcane powder, water, γ-valerolactone solution, and CoCl2·6H2O to obtain a mixed solution; (3) subjecting the mixed solution to a hydrothermal reaction to obtain a filtrate and a hydrothermal residue; (4) mixing the filtrate with ethyl acetate, stirring, and phase separation to obtain an organic phase, and distilling and condensing the organic phase to obtain furfural; The hydrothermal residue is dried, mixed with carbon black in a mass ratio of 4 to 5:1, and ground to obtain a mixed powder, and the mixed powder is subjected to a Joule heat reaction under vacuum conditions to obtain graphene; The liquid-to-solid ratio of water to sugarcane powder is 3-15:1 L / kg; The liquid-to-solid ratio of the γ-valerolactone solution to the sugarcane powder is 15-27:1 L / kg; The concentration of the CoCl2·6H2O is 0.3-0.5M; The temperature of the hydrothermal reaction is 170-185° C., and the insulation time is 15-60 minutes.

2. The method for co-producing furfural and graphene from sugarcane according to claim 1, characterized in that: The cooling time of the hydrothermal reaction is 30 to 60 minutes, and the cooling method is ice cooling.

3. The method for co-producing furfural and graphene from sugarcane according to claim 1, characterized in that: The volume ratio of the hydrothermal reactor volume to the mixed solution is 1.7 to 2:

1.

4. The method for co-producing furfural and graphene from sugarcane according to claim 1, characterized in that: The specific steps of step (1) are: The sugarcane bagasse is dried at 60-80° C. for 10-12 hours, the dried sugarcane bagasse is crushed, and then sieved using a 40-80 mesh filter screen to obtain sugarcane powder.

5. The method for co-producing furfural and graphene from sugarcane according to claim 1, characterized in that: The stirring time of step (4) is 1 to 2 hours.

6. The method for co-producing furfural and graphene from sugarcane according to claim 1, characterized in that: The method of distilling and condensing the organic phase to obtain furfural comprises the following steps: heating the organic phase to the boiling point of furfural to evaporate the furfural, and then condensing and collecting the furfural.

7. The method for co-producing furfural and graphene from sugarcane according to claim 1, characterized in that: The step of subjecting the mixed powder to a Joule heat reaction under vacuum conditions to obtain graphene comprises the following steps: Put the mixed powder into a quartz tube, seal the two ends of the quartz tube with copper wire plugs and graphite plugs, then put the quartz tube into a Joule heat reaction box, and evacuate the reaction box to a vacuum degree of 0.008-0.01MPa; Then, flash discharge is performed, wherein the voltage of the flash discharge is 160-170V, the capacitance of the capacitor bank is 90mF, and the discharge time is 2-3s.

8. The method for co-producing furfural and graphene from sugarcane according to claim 1, characterized in that: The mass of the mixed powder is 0.1-0.15 g, and the inner diameter of the quartz tube is 8-10 mm.

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