A lignin-based sulfonated carbon catalyst, a preparation method and application thereof

Abstract

The present application relates to the technical field of high-value conversion and utilization of biomass, and particularly relates to a lignin-based sulfonated carbon catalyst, a preparation method and application thereof. The present application takes lignin sulfonate, a by-product of sulfite papermaking process, as raw material, and after carbonization and ion exchange, sulfonic acid functional groups in the structure of lignin sulfonate are fully retained, a strong-acid high-specific-surface-area sulfonated carbon catalyst is prepared, and cellulose is converted into levulinic acid product in one step in aqueous solvent, avoiding the use of traditional strong-corrosive sulfuric acid, hydrochloric acid and homogeneous catalysts such as ionic liquid, and the target product can be obtained in one step, compared with the use of strong-oxidizing liquid acid and acidic ionic liquid, the process is green and environmentally friendly, and the yield and conversion rate are excellent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-value conversion and utilization of biomass, and particularly relates to a lignin-based sulfonated carbon catalyst as well as a preparation method and application thereof. BACKGROUND

[0002] Lignin is one of the main components of plant cell walls, and its molecular structure is a three-dimensional macromolecular compound formed by the polymerization of phenylpropanoid structural units through C-C bonds and C-O bonds. As a natural renewable aromatic compound resource, lignin has the advantages of wide source and low price, and has great application value and potential in modern chemical industry. However, the renewable resource of lignin has not been fully developed and utilized at present, especially about 7000 tons of lignin is produced as a by-product in the paper industry every year, and only less than 2% of the lignin is effectively utilized, and the rest is directly burned as low-value fuel. This not only causes resource waste, but also causes certain environmental pollution.

[0003] Lignin sulfonate is a kind of lignin derivative by-produced in the sulfite pulping process, and its structure not only has phenylpropanoid structural units like natural lignin, but also includes 3-8% sulfonate groups, and weak ionization functional groups such as carboxylic acid and phenolic hydroxyl groups. Similar to the application of other lignin, the lignin sulfonate resource has not been effectively utilized at present, but in the combustion process, the sulfur element in its structure forms sulfur-containing acid gas, which further aggravates environmental pollution, and therefore the high-value utilization of lignin sulfonate is an important proposition in the paper industry.

[0004] Sulfonated carbon is a kind of porous carbon material with strong sulfonic acid functional groups and weak carboxylic acid and phenolic hydroxyl functional groups, and the sulfonic acid functional groups in its structure can be used as strong Bronsted acid active centers, while the carboxylic acid groups and phenolic hydroxyl groups can change the surface properties of the catalyst as weak acid centers or hydrophilic groups. Therefore, sulfonated carbon as a kind of efficient solid acid catalyst has many applications in plant polysaccharide hydrolysis, esterification, alkylation and other reactions. Generally, the preparation of sulfonated carbon takes biomass such as cellulose as a precursor, and reacts with fuming sulfuric acid or benzene sulfonic acid, chlorosulfonic acid and other sulfonic acid substances under high temperature conditions, in which the biomass such as cellulose is dehydrated into a porous carbon material, and the sulfonic acid substances provide sulfonic acid functional groups for the carbon material to obtain a sulfonated carbon material. However, the specific surface area of the sulfonated carbon material prepared by taking lignin sulfonate as a raw material is relatively small, and is usually not more than 350 m 2 / g, and the fuming sulfuric acid, sulfonic acid substances in this process will produce a large amount of toxic SO2, SO3 and other gases, which have great harm to the environment. The structure of lignin sulfonate itself contains sulfonic acid functional groups, but these sulfonic acid functional groups have poor thermal stability and are easily detached in the carbonization process. Therefore, effectively utilizing the sulfonic acid, carboxylic acid and phenolic hydroxyl groups in the structure of lignin sulfonate to convert lignin sulfonate into sulfonated carbon catalyst with high specific surface area has great significance for the high-value utilization of lignin in the paper industry.

[0005] Levulinic acid is a new type of platform compound with carbonyl and carboxyl groups. It can be directly used as a solvent, food additive, fine chemical and raw material for drug synthesis, and can also be used as an intermediate for fuel production to obtain fuel additives such as levulinic acid ester, gamma-valerolactone, 2-methyltetrahydrofuran, etc., which have wide applications in the fields of medicine, pesticide, petroleum chemical industry, etc. The preparation of levulinic acid from cellulose usually requires the use of strong acid catalysts. Under the action of strong acid catalysts, cellulose is hydrolyzed to obtain glucose, which is then isomerized to obtain fructose, and then undergoes dehydration to generate 5-hydroxymethylfurfural, and then continues to undergo rearrangement to obtain levulinic acid product. The main problem of producing levulinic acid from cellulose raw materials at present is that the existing catalytic reaction system has many shortcomings such as low efficiency and strong corrosion, which makes it difficult to efficiently prepare the target product of levulinic acid. Specifically, 1) the use of strong acid catalysts such as hydrochloric acid or sulfuric acid has problems such as corrosion of equipment, difficulty in separation and pollution of the environment; 2) the use of ionic liquid and other acidic catalysts has problems such as high cost and difficulty in separation of some intermediate products from ionic liquids; 3) cellulose preparation of levulinic acid needs to go through multiple steps, and the efficiency is relatively low.

[0006] Therefore, how to overcome the above technical problems and obtain a lignin-based sulfonated carbon catalyst which can not only realize the high-value utilization of lignin sulfonate, but also efficiently prepare levulinic acid product, is a problem to be solved at present. SUMMARY

[0007] The present application aims to provide a lignin-based sulfonated carbon catalyst and its preparation method and application, in order to solve the technical problems of low additional value of lignin sulfonate in the prior art sulfonated carbon catalyst, and low catalytic efficiency and strong corrosion in the preparation of levulinic acid product from cellulose raw materials.

[0008] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0009] The present application provides a preparation method of a lignin-based sulfonated carbon catalyst, comprising the following steps:

[0010] 1) dispersing lignin sulfonate and magnesium salt in water, and drying to obtain a gel-like solid;

[0011] 2) high-temperature carbonization treatment of the gel-like solid in a nitrogen atmosphere to obtain a sample;

[0012] 3) ion exchange of the sample in an inorganic acid solution, and drying to obtain a lignin-based sulfonated carbon catalyst.

[0013] Further, in the step 1), the lignin sulfonate comprises one or more of calcium lignosulfonate, sodium lignosulfonate and magnesium lignosulfonate by-produced in a sulfite pulping process.

[0014] The metal magnesium salt comprises one or more of magnesium nitrate, magnesium acetate and magnesium citrate.

[0015] Further, in the step 1), the mass ratio of the lignin sulfonate and the metal magnesium salt is 1:0.1-1, the concentration of the lignin sulfonate in water is 1-100 g / L, and the drying temperature is 60-120℃.

[0016] Further, in the step 2), the temperature of the high-temperature carbonization treatment is 250-650℃, and the time of the high-temperature carbonization treatment is 3-5 h.

[0017] Further, in the step 3), the inorganic acid solution is one or more of a sulfuric acid solution, a hydrochloric acid solution and a nitric acid solution, and the concentration of H + in the inorganic acid solution is 0.01-1 mol / L.

[0018] The application provides a lignin-based sulfonated carbon catalyst.

[0019] The application provides an application of the lignin-based sulfonated carbon catalyst in catalyzing preparation of levulinic acid from cellulose, comprising the following steps:

[0020] 1) dispersing cellulose and the lignin-based sulfonated carbon catalyst in water to obtain a mixed solution;

[0021] 2) after heating reaction of the mixed solution, filtering out the lignin-based sulfonated carbon catalyst to obtain the levulinic acid.

[0022] Further, the mass ratio of the cellulose and the lignin-based sulfonated carbon catalyst is 1:0.05-1, and the concentration of the cellulose in water is 1-50 g / L.

[0023] Further, in the step 2), the temperature of the heating reaction is 150-300℃, and the time of the heating reaction is 1.0-12 h.

[0024] The technical scheme of the application has the following advantages:

[0025] 1) The present application provides a method for preparing high specific surface area sulfonated carbon catalyst from lignin sulfonate, which uses inexpensive inorganic magnesium salt as a template agent, and can carbonize lignin sulfonate into high specific surface area sulfonated carbon material with specific surface area > 400 m 2 / g under mild conditions.

[0026] 2) The present application effectively utilizes the sulfonic acid functional group of lignin sulfonate, so that the sulfonic acid functional group density in the target product sulfonated carbon catalyst is > 0.5 mmol / g, which not only greatly provides the catalytic performance of the sulfonated carbon catalyst, but also avoids the use of fuming sulfuric acid, chlorosulfonic acid and other substances in the synthesis process of traditional sulfonated carbon materials, and avoids the release of toxic gases such as SO2 and SO3.

[0027] 3) The present application uses lignin-based sulfonated carbon material as catalyst to catalyze the preparation of levulinic acid from cellulose, and the target product is prepared in aqueous solvent. Not only avoids the use of strong corrosive substances such as sulfuric acid and hydrochloric acid and ionic liquid homogeneous catalysts, but also can obtain the target product in one step. Compared with the use of strong oxidizing liquid acid and acidic ionic liquid, the process is green and environmentally friendly, and the yield and conversion rate are excellent.

[0028] 4) The lignin-based sulfonated carbon catalyst and the levulinic acid product prepared by the present application use lignin and cellulose as raw materials, which are both renewable resources. The whole process not only improves the added value of the by-product lignin sulfonate in papermaking, but also provides a new path for the utilization of renewable resources such as lignocellulose. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is the nitrogen adsorption-desorption curve of the lignin-based sulfonated carbon catalyst prepared in the present application;

[0030] Figure 2 is the infrared spectrum of the lignin-based sulfonated carbon catalyst prepared in the present application. DETAILED DESCRIPTION

[0031] The present application provides a method for preparing lignin-based sulfonated carbon catalyst, which comprises the following steps:

[0032] 1) Disperse lignin sulfonate and magnesium salt in water, and dry to obtain a gel-like solid;

[0033] 2) Carbonize the gel-like solid at high temperature in a nitrogen atmosphere to obtain a sample;

[0034] 3) Disperse the sample in an inorganic acid solution for ion exchange, and dry to obtain the lignin-based sulfonated carbon catalyst.

[0035] In the present application, in the step 1), the mass ratio of the lignin sulfonate and the magnesium salt is 1:0.1-1, preferably 1:0.1-0.8, further preferably 1:0.1-0.5, and more preferably 1:0.3-0.4.

[0036] In the present application, in the step 1), the concentration of the lignin sulfonate in water is 1-100 g / L, preferably 30-80 g / L, and further preferably 50-60 g / L.

[0037] In the present application, in the step 1), the drying temperature is 60-120℃, preferably 80-110℃, and further preferably 90-100℃.

[0038] In the present application, in the step 3), the high-temperature carbonization treatment temperature is 250-650℃, preferably 350-590℃, and further preferably 400-500℃.

[0039] In the present application, in the step 3), the high-temperature carbonization treatment time is 3-5 h, and preferably 4 h.

[0040] In the present application, in the step 3), the H + concentration in the inorganic acid solution is 0.01-1 mol / L, preferably 0.05-0.95 mol / L, and further preferably 0.5 mol / L.

[0041] The present application provides a lignin-based sulfonated carbon catalyst.

[0042] The present application provides an application of a lignin-based sulfonated carbon catalyst in catalyzing the preparation of levulinic acid from cellulose, comprising the following steps:

[0043] 1) dispersing cellulose and the lignin-based sulfonated carbon catalyst in water to obtain a mixed solution;

[0044] 2) after heating and reacting the mixed solution, filtering out the lignin-based sulfonated carbon catalyst to obtain the levulinic acid.

[0045] In the present application, in the step 1), the mass ratio of the cellulose and the lignin-based sulfonated carbon catalyst is 1:0.05-1, preferably 1:0.3-0.9; and the concentration of the cellulose in water is 1-50 g / L, preferably 3-50 g / L, and further preferably 5-35 g / L.

[0046] In the present application, in the step 2), the heating reaction temperature is 150-300℃, preferably 150-250℃, and further preferably 200-220℃.

[0047] In the present application, the heating reaction in step 2) is performed for 1.0-12 h, preferably 4-10 h, and more preferably 5-8 h.

[0048] The technical solutions provided by the present application are described in detail below in conjunction with examples, but they should not be construed as limiting the scope of protection of the present application.

[0049] Examples 1-9

[0050] Examples 1-9 provide a preparation method of a lignin-based sulfonated carbon catalyst, comprising the following steps,

[0051] 1) dispersing lignin sulfonate and magnesium salt in water, and drying to obtain a gel-like solid;

[0052] 2) carbonizing the gel-like solid at high temperature in a nitrogen atmosphere to obtain a sample;

[0053] 3) dispersing the sample in an inorganic acid solution for ion exchange, and drying to obtain a lignin-based sulfonated carbon catalyst. Examples 1-9 differ in the types of lignin sulfonate and magnesium salt, the mass ratio of the two, the concentration of lignin sulfonate, the drying and carbonization temperature, and the concentration of the inorganic acid solution in the preparation of the sulfonated carbon catalyst. See Table 1 for details.

[0054] Table 1 Process parameters in Examples 1-9

[0055]

[0056]

[0057] The lignin-based sulfonated carbon catalysts prepared in Examples 1-9 are denoted as A-I, respectively.

[0058] Examples 10-20

[0059] Examples 10-20 each provide an application of a lignin-based sulfonated carbon catalyst in catalyzing the preparation of levulinic acid from cellulose, comprising the following steps:

[0060] Disperse cellulose and catalyst in 100 mL of water, then place in a 300 mL high-pressure reaction kettle, replace the air in the reaction kettle with nitrogen, heat to 150-300°C, and stir for 1.0-12 h. After the reaction is completed, remove the solid catalyst by filtration to obtain the levulinic acid product.

[0061] The difference between Examples 10-20 lies in the amount of cellulose and catalyst, the type of catalyst, the reaction temperature, and the reaction time. See Table 2 for the process parameters in Examples 10-20.

[0062] Table 2 Process parameters in Examples 10-20

[0063]

[0064] Comparative Example 1

[0065] This comparative example provides a method for preparing a lignin-based sulfonated carbon catalyst, which is different from Example 1 in that no magnesium salt template is added in the preparation process, and specifically comprises the following steps:

[0066] 5.0 g of sodium lignosulfonate was dispersed in 100 mL of deionized water, and after stirring evenly, it was placed in an 80°C oven to dry to constant weight. It was heated to 400°C in a nitrogen atmosphere for carbonization treatment for 4 h. After washing, drying, and ion exchange in a 0.50 mol / L hydrochloric acid solution, the sample was filtered, washed, and dried to obtain a sulfonated carbon material, which was denoted as C-1.

[0067] This comparative example also provides a method for preparing levulinic acid using the above lignin-based sulfonated carbon catalyst, which is different from Example 10 in that the catalyst used is C-1, and specifically comprises the following steps:

[0068] 10 g of cellulose and 3.5 g of the above catalyst C-1 were dispersed in 100 mL of water, and then placed in a 300 mL high-pressure reaction kettle. After replacing the air in the reaction kettle with nitrogen, it was heated to 250°C and stirred for 12 h. After the reaction was completed, the solvent was removed by filtration and rotary evaporation.

[0069] Comparative Example 2

[0070] This comparative example provides a method for preparing a lignin-based sulfonated carbon catalyst, which is different from Example 1 in that the carbonization temperature in the preparation process is 300°C, and specifically comprises the following steps:

[0071] 5.0 g of sodium lignosulfonate and 1.5 g of magnesium nitrate were dispersed in 100 mL of deionized water, and after stirring evenly, it was placed in an 80°C oven to dry to constant weight. It was heated to 300°C in a nitrogen atmosphere for carbonization treatment for 4 h. After washing, drying, and ion exchange in a 0.50 mol / L hydrochloric acid solution, the sample was filtered, washed, and dried to obtain a sulfonated carbon material, which was denoted as C-2.

[0072] This comparative example also provides a method for preparing levulinic acid using the above catalyst, which comprises the following steps:

[0073] 10 g cellulose and 3.5 g of the above catalyst C-2 were dispersed in 100 mL of water, and then placed in a 300 mL autoclave. After the air in the autoclave was replaced with nitrogen, the temperature was raised to 250°C, and the reaction was stirred for 12 h. After the reaction was completed, the product was filtered and the solvent was removed by rotary evaporation.

[0074] Comparative Example 3

[0075] The present comparative example provides a method for preparing a lignin-based sulfonated carbon catalyst, which is different from Example 1 in that the carbonization temperature of lignin in the preparation process is 700°C, and specifically comprises the following steps:

[0076] 5.0 g of sodium lignosulfonate and 1.5 g of magnesium chloride were dispersed in 100 mL of deionized water, and then placed in an 80°C oven for drying until the weight was constant. The sample was carbonized at 700°C for 4 h in a nitrogen atmosphere, and then washed, dried, and ion-exchanged in a 0.50 mol / L hydrochloric acid solution. Finally, the sample was filtered, washed, and dried to obtain a sulfonated carbon material, which was denoted as C-3.

[0077] The present comparative example also provides a method for preparing levulinic acid using the above catalyst, which comprises the following steps:

[0078] 10 g of cellulose and 3.5 g of the above catalyst C-3 were dispersed in 100 mL of water, and then placed in a 300 mL autoclave. After the air in the autoclave was replaced with nitrogen, the temperature was raised to 250°C, and the reaction was stirred for 12 h. After the reaction was completed, the product was filtered and the solvent was removed by rotary evaporation.

[0079] Comparative Example 4

[0080] The present comparative example provides a method for preparing a lignin-based sulfonated carbon catalyst, which is different from Example 1 in that the carbonized sulfonated carbon material is not ion-exchanged in an inorganic acid solution, and specifically comprises the following steps:

[0081] 5.0 g of sodium lignosulfonate and 1.5 g of magnesium chloride were dispersed in 100 mL of deionized water, and then placed in an 80°C oven for drying until the weight was constant. The sample was carbonized at 450°C for 4 h in a nitrogen atmosphere, and then washed, dried, and ion-exchanged in a 0.50 mol / L hydrochloric acid solution. Finally, the sample was filtered, washed, and dried to obtain a sulfonated carbon material, which was denoted as C-4.

[0082] The present comparative example also provides a method for preparing levulinic acid using the above catalyst, which comprises the following steps,

[0083] 10 g of cellulose and 3.5 g of the above catalyst C-4 were dispersed in 100 mL of water, and then placed in a 300 mL autoclave. After the air in the autoclave was replaced with nitrogen, the temperature was raised to 250°C, and the reaction was stirred for 12 h. After the reaction was completed, the product was filtered and the solvent was removed by rotary evaporation.

[0084] Comparative Example 5

[0085] This comparative example provides a method for preparing levulinic acid from cellulose. The difference from Example 2 is that concentrated sulfuric acid is used as a catalyst in this process, and specifically comprises the following steps:

[0086] 10 g of cellulose and 3.5 g of concentrated sulfuric acid were dispersed in 100 mL of water and then placed in a 300 mL high-pressure reactor. After the air in the reactor was replaced with nitrogen, the temperature was raised to 250°C and stirred for 12 h. After the reaction was completed, the mixture was filtered and the solvent was removed by rotary evaporation.

[0087] Effect Examples

[0088] 1. The specific surface area and sulfonic acid functional group density of the lignin-based sulfonated carbon catalysts obtained in Examples 1 to 9 were tested, wherein Figure 1 and Figure 2 They are respectively the N2 adsorption-desorption curve and S2p XPS spectrum of the lignin-based sulfonated carbon catalyst in Example 1.

[0089] 2. Table 3 shows the specific surface area and density of sulfonic acid functional groups of the lignin-based sulfonated carbons prepared in Examples 1 to 9 and Comparative Examples 1 to 4. Table 4 shows the levulinic acid yields of Examples 10 to 20 and Comparative Examples 1 to 5.

[0090] Specific surface area of ​​lignin-based sulfonated carbon (refer to Kiyotaka Nakajima, Michikazu Hara, Amorphous carbon with SO3H groups as a solid Acid catalyst,ACS Catalysis.2012,2,1296-1304.): The test was carried out using a physical adsorption instrument model ASAP2020 from Micromeritics, USA. The sample was first degassed at 150°C for 10 h in vacuum, and then the sample was placed at -196°C for N2 adsorption and desorption experiments. The N2 adsorption and desorption curves were obtained, and the specific surface area data (m 2 / g).

[0091] Determination of sulfonic acid functional group density of lignin sulfonated carbon (reference Lakhya Jyoti Konwara, Ajaikumar Samikannua, Dan Jyri-Pekka Mikkola, Lignosulfonate-based macro / mesoporous solid protonic acids for acetalization of glycerol to bio-additives, Applied Catalysis B: Environmental, 2018, 220. 314-323): The test was performed by using the X-ray photoelectron spectrometer of EX250i type from ThermoFisher Corporation, USA. The characterization was used to analyze the elemental composition, elemental valence, elemental content and other information of the sulfonated carbon sample. The sulfonic acid group density was calculated by combining the elemental scanning analysis and fitting the peak area ratio. The X-ray excitation source was Al Kα (1486.6 eV), and the vacuum condition was 5.0 x 10 -7 Pa. The binding energy of all elements was taken as the internal standard with C1s = 284.4 eV for point and compensation, so that the S element content (mmol / g) in the sulfonated carbon material could be quantitatively determined. At the same time, it could be known from the S2p XPS spectrum analysis that the existence form of S in the sulfonated carbon obtained in examples 1-9 was -SH and -SO3H. Then the sulfonic acid functional group density in the sulfonated carbon = A (-SO3H) / [A (-SO3H) +A (-SH) ] x I (S) , wherein A (-SO3H) , A (-SH) respectively represent the areas of -SO3H and -SH in the S2p XPS spectrum, and I(S) represents the S element content (mmol / g) in the sulfonated carbon material.

[0092] Method for calculating the yield of levulinic acid product (referring to Kui Wang, Jun Ye, Minghao Zhou, Peng Liu, Xinyu Liang, Junming Xu, Jianchun Jiang, Selective conversion of cellulose to levulinic acid and furfural in sulfolane / water solvent, Cellulose, 2017, 24, 1383-1394): The Agilent 8890 gas chromatograph was used for testing. The liquid products of each example and comparative example were collected and quantitatively analyzed in the gas chromatograph, the injection port temperature was 240℃, the column oven was kept at 40℃ for 5 minutes, then the temperature was raised to 240℃ at a rate of 7.5℃ / min and kept for 15 minutes, the chromatographic column used Restek RTX-VMS capillary column, the column length was 40m, the diameter was 0.18mm, the membrane thickness was 1.00um, the carrier gas of the chromatographic column was He, the column flow rate was 0.5mL / min, the detector was FID detector, and the detector temperature was 250℃. The yield of levulinic acid product = m(levulinic acid) / m(cellulose) x 100%, wherein m(levulinic acid) and m(cellulose) are the mass (g) of levulinic acid quantified in the gas chromatograph and the mass (g) of cellulose added before the reaction, respectively.

[0093] Table 3 Results of specific surface area and sulfonic acid functional group density of lignin-based sulfonated carbon in examples 1-9 and comparative examples 1-4

[0094]

[0095]

[0096] Table 4 Results of the yield of levulinic acid product in examples 10-20 and comparative examples 1-5

[0097] Levulinic acid product yield (%) Example 10 73 Example 11 68 Example 12 62 Example 13 64 Example 14 70 Example 15 66 Example 16 69 Example 17 71 Example 18 70 Example 19 63 Example 20 67 Comparative Example 1 - Comparative Example 2 3 Comparative Example 3 - Comparative Example 4 - Comparative Example 5 5

[0098] From examples 1-20 in Table 3 and Table 4, it can be seen that the types of lignin sulfonate and magnesium salt, the mass ratio of the two, the concentration of lignin sulfonate, the drying and carbonization temperature, and the concentration of inorganic acid solution during the preparation of the lignin-based sulfonated carbon catalyst all have an impact on the specific surface area and sulfonic acid functional group density of the sulfonated carbon material, which in turn affects the product yield of levulinic acid prepared by hydrolysis of cellulose; the concentration of cellulose, the amount of catalyst, the reaction temperature and the reaction time also have a certain influence on the yield of levulinic acid.

[0099] Comparing the comparative example 1 and the example 1, it is illustrated that the metal magnesium salt is used as the template agent, and the lignin sulfonate can be effectively prepared into the sulfonated carbon material with the high specific surface area and the high sulfonic acid functional group density, and then the sulfonated carbon material has the excellent catalytic performance in the reaction of the cellulose conversion into the levulinic acid.

[0100] Comparing the comparative example 2 and the example 1 and the example 10, it is illustrated that when the lower carbonization temperature is used, the specific surface area and the sulfonic acid functional group density of the sulfonated carbon material are both lower, and the cellulose cannot be converted into the levulinic acid product.

[0101] Comparing the comparative example 3 and the example 1 and the example 10, it is illustrated that when the higher carbonization temperature is used, the sulfonic acid functional group density of the sulfonated carbon material is too low, and the cellulose cannot be converted into the levulinic acid product.

[0102] Comparing the comparative example 4 and the example 1 and the example 10, it is illustrated that when the inorganic acid is not used for the ion exchange, the sulfonic acid functional group density of the sulfonated carbon material is lower, and the cellulose cannot be converted into the levulinic acid product.

[0103] Comparing the comparative example 5 and the example 10, it is illustrated that when the concentrated sulfuric acid is used as the catalyst, the product yield of the cellulose conversion into the levulinic acid is lower, and the catalytic reaction performance is lower than that of the sulfonated carbon material provided by the application.

[0104] The above only is the preferred embodiment of the application, and it should be pointed out that for the ordinary skilled in the art, without departing from the principles of the application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the application.

Claims

1. Use of a lignin-based sulfonated carbon catalyst in catalyzing the production of levulinic acid from cellulose, characterized in that, The method comprises the following steps: S1) dispersing cellulose and lignin sulfonated carbon catalyst in water to obtain a mixture; S2) after heating and reaction of the mixture, filtering out the lignin sulfonated carbon catalyst to obtain levulinic acid; The preparation method of the lignin-based sulfonated carbon catalyst comprises the following steps: 1) dispersing lignin sulfonate and magnesium salt in water, and drying to obtain a gel-like solid; 2) performing high-temperature carbonization treatment on the gel-like solid in a nitrogen atmosphere to obtain a sample; 3) dispersing the sample in an inorganic acid solution for ion exchange, and drying to obtain the lignin-based sulfonated carbon catalyst; The magnesium salt comprises one or more of magnesium nitrate, magnesium acetate and magnesium citrate; The magnesium salt is a template agent; In step 2), the temperature of the high-temperature carbonization treatment is 350-650°C, and the time of the high-temperature carbonization treatment is 3-5h.

2. Use of the lignin-based sulfonated carbon catalyst according to claim 1 for catalyzing the preparation of levulinic acid from cellulose, characterized in that, In step 1), the lignin sulfonate comprises one or more of calcium lignosulfonate, sodium lignosulfonate and magnesium lignosulfonate produced in a sulfite pulping process.

3. Use of the lignin-based sulfonated carbon catalyst according to claim 1 or 2 for catalyzing the production of levulinic acid from cellulose, characterized in that, In step 1), the mass ratio of the lignin sulfonate to the magnesium salt is 1:0.1-1, the concentration of the lignin sulfonate in water is 1-100g / L, and the drying temperature is 60-120°C.

4. Use of the lignin-based sulfonated carbon catalyst according to claim 3 for catalyzing the preparation of levulinic acid from cellulose, characterized in that, In the step 3), the inorganic acid solution is one or more of a sulfuric acid solution, a hydrochloric acid solution, and a nitric acid solution, and the H + concentration is 0.01-1 mol / L.

5. Use of the lignin-based sulfonated carbon catalyst according to claim 4 for catalyzing the production of levulinic acid from cellulose, characterized in that, In step S1), the mass ratio of the cellulose to the lignin sulfonated carbon catalyst is 1:0.05-1, and the concentration of the cellulose in water is 1-50g / L.

6. Use of the lignin-based sulfonated carbon catalyst according to claim 4 or 5 for catalyzing the production of levulinic acid from cellulose, characterized in that, In step S2), the temperature of the heating reaction is 150-300°C, and the time of the heating reaction is 1.0-12h.

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