Method for preparing levoglucosenone by utilizing sulfonated carbon to catalyze cellulose and application of levoglucosenone

Abstract

The invention relates to a method for preparing levoglucosenone by utilizing sulfonated carbon to catalyze cellulose and application of the levoglucosenone, and belongs to the technical field of biomass recycling and green catalysis. According to the method, microcrystalline cellulose or waste cellulose biomass is taken as a raw material, sulfonated carbon is taken as a catalyst, and efficient preparation of levoglucosenone is realized in an organic solvent system. By utilizing the synergistic effect of acidic active sites provided by sulfonated carbon and the organic solvent, directional dehydration of cellulose is promoted to generate the levoglucosenone, and side reactions such as hydrolysis, cracking and condensation are effectively reduced, so that the selectivity and yield of the levoglucosenone are improved, and the yield of the levoglucosenone is increased. And an efficient and green technical approach is provided for high-value conversion of cellulose biomass.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive utilization of high-value biomass resources, specifically relating to a method for preparing L-glucosamine from cellulose using sulfonated carbon catalysis and its application. More particularly, it relates to a method for preparing L-glucosamine from cellulose using sulfonated carbon catalysis in a heterogeneous system, and the application of this catalytic system in the catalytic conversion of waste biomass. Background Technology

[0002] Cellulose biomass is one of the most abundant renewable organic carbon resources in nature. As a widely available, renewable, and inexpensive biomass resource, the high-value utilization of cellulose and its derivative waste biomass is of great significance for alleviating dependence on fossil resources, reducing environmental burden, and promoting green chemistry and sustainable development. In particular, its efficient conversion into high-value-added platform compounds can provide an important raw material foundation for the green preparation of bio-based chemicals, fine chemicals, and functional materials.

[0003] L-glucanone is an important biomass platform compound. Its molecule simultaneously contains unsaturated double bonds, carbonyl groups, and chiral structural units, exhibiting high chemical reactivity and derivatization potential. It can be used to prepare fine chemicals, pharmaceutical intermediates, high-value-added material monomers, and green solvent precursors, thus attracting widespread attention. The targeted preparation of L-glucanone from cellulose raw materials is considered one of the important pathways to achieve high-value utilization of biomass.

[0004] In existing technologies, the conversion of cellulose to L-glucanone mainly employs pyrolysis, homogeneous acid catalysis, or specific solvent systems to promote dehydration. While pyrolysis can generate L-glucanone, it suffers from drawbacks such as high reaction temperatures, numerous side reactions, complex product distribution, and low selectivity for the target product. Homogeneous acid catalysis, although able to promote cellulose dehydration to some extent, typically suffers from equipment corrosion, difficulties in separation and recovery, complex post-processing, and significant environmental impact, hindering continuous and industrial applications. Therefore, developing a heterogeneous catalytic system that balances high catalytic activity, good target product selectivity, and easy catalyst separation and recovery is of great significance.

[0005] In recent years, solid acid catalysts have shown promising application prospects in the field of biomass catalytic conversion due to their advantages such as easy separation, recyclability, low corrosivity, and environmental friendliness. Among them, sulfonated carbon materials combine the stability of the carbon material framework with the acidic site characteristics of sulfonic acid groups, and have advantages such as relatively simple preparation, tunable acidity, good thermal stability, and suitability for heterogeneous catalytic reactions, making them a promising class of biomass conversion catalysts. However, existing research on the directional preparation of L-glucosamine from cellulose using sulfonated carbon is still relatively limited, especially in achieving high yields, high selectivity, and catalyst recycling in heterogeneous systems, where further optimization is still needed. In addition, existing studies mostly use model substrates such as microcrystalline cellulose as research objects, with relatively few studies on the direct use of actual waste cellulosic biomass for L-glucosamine preparation. Compared with model substrates, actual waste biomass usually has a more complex composition, containing hemicellulose, lignin, ash, and other impurities in addition to cellulose. Its mass transfer behavior, dehydration pathway, and product distribution during the reaction process may all differ significantly, thus limiting the applicability of existing technologies to actual raw materials and application effects. Therefore, it is necessary to construct corresponding catalytic conversion systems on actual waste biomass substrates to examine their application feasibility and technical effectiveness in the high-value utilization of real biomass resources.

[0006] Therefore, developing a heterogeneous catalytic conversion method suitable for cellulose and actual waste cellulose biomass to achieve the efficient preparation of L-glucanone has important research value and application prospects. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing L-glucosidone from cellulose using sulfonated carbon catalysis, which has relatively mild reaction conditions, easy catalyst separation and recovery, high selectivity of target product, and can be extended to practical waste cellulosic biomass conversion, and its application.

[0008] The present invention provides a method for preparing L-glucanone from cellulose using sulfonated carbon catalysis, which specifically includes the following steps:

[0009] (1) Mix cellulose, sulfonated carbon catalyst and organic solvent to obtain a reaction system; wherein the mass ratio of cellulose to sulfonated carbon catalyst is 1:1-1:10;

[0010] (2) Place the reaction system obtained in step (1) in a closed reactor and react at 150-300℃ for 1-120 min;

[0011] (3) After the reaction is completed, the reaction system obtained in step (2) is cooled and solid-liquid separation is performed to recover the sulfonated carbon catalyst and obtain the liquid phase product;

[0012] (4) Analyze or separate the liquid phase product obtained in step (3) to obtain L-glucose ketone.

[0013] In this invention, the organic solvent mentioned in step (1) is a polar aprotic solvent, which is selected from one or more of tetrahydrofuran, 1,4-dioxane, diethyl ether, isopropyl ether, tert-butyl methyl ether, acetonitrile, propionitrile, acetone, butanone, cyclohexanone, ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, dimethyl carbonate, diethyl carbonate, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, tetramethyl sulfoxide, or sulfolane.

[0014] In this invention, the cellulose biomass mentioned in step (1) includes microcrystalline cellulose and waste cellulose biomass. The waste cellulose biomass is selected from one or more of the following: wheat straw, corn straw, rice straw, sorghum straw, cotton straw, soybean straw, corn cob, peanut shell, rice shell, coconut shell, sawdust, wood chips, shavings, branches, bagasse, waste paper, corrugated paper, cardboard, cotton fiber waste, waste cotton cloth, hemp fiber waste, bamboo powder, bamboo chips, or wood powder.

[0015] In this invention, the reaction temperature in step (2) is 150-300℃ and the reaction time is 10-60 min.

[0016] In this invention, the preparation steps of the sulfonated carbon catalyst in step (1) are as follows: the carbon support and concentrated sulfuric acid are mixed in a reaction vessel and sulfonated at 80-100℃. Then, after solid-liquid separation, the solid product obtained is the sulfonated carbon catalyst.

[0017] In this invention, the carbon support is selected from one or more of activated carbon, mesoporous carbon, microporous carbon, ordered mesoporous carbon, or carbon molecular sieves.

[0018] Application of L-glucanone prepared using the method of this invention in the catalytic conversion of waste biomass.

[0019] This invention provides a method for preparing L-glucanone from cellulose using sulfonated carbon catalysis in a heterogeneous system. The method uses a carbon-based solid acid catalyst containing sulfuric acid functional groups as the catalytic material and a polar aprotic solvent as the reaction medium. Through synergistic regulation of the cellulose depolymerization, dehydration, and rearrangement processes, the efficient preparation of L-glucanone is achieved. This invention features easy catalyst separation and recovery, abundant acidic sites, a green reaction system, and a wide range of applicable solvents. It can improve the formation efficiency and selectivity of the target product under relatively mild and controllable conditions. Furthermore, this invention is applicable not only to model substrates such as microcrystalline cellulose but also to actual waste cellulosic biomass, exhibiting good raw material applicability and application scalability. It provides a new technical route for the high-value conversion of cellulosic biomass into platform compounds.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) This invention uses sulfonated carbon as a solid acid catalyst to realize the catalytic conversion of cellulose to L-glucose ketone in a heterogeneous system, avoiding the problems of equipment corrosion, complicated post-processing and difficulty in recovering acidic media in homogeneous acid systems. It has good process greenness and application feasibility.

[0022] (2) The present invention uses a polar aprotic solvent to construct the reaction system, which is beneficial to control the reaction microenvironment, promote the dehydration pathway of cellulose, and inhibit side reactions such as hydrolysis, cracking and condensation to a certain extent, thereby improving the selectivity of L-glucanone.

[0023] (3) This invention is not only applicable to model substrates such as microcrystalline cellulose, but can also be extended to actual waste cellulosic biomass. It can realize the high-value conversion of waste biomass such as cotton powder, sawdust, wheat straw, corn straw, corn cob, and bamboo powder, indicating that this invention has good practical application value.

[0024] (4) By synergistically controlling the acidity, pore structure and reaction conditions of the catalyst, this invention can achieve efficient preparation of L-glucanone at a reaction temperature of 150-300℃ and a reaction time of 10-60 min, with a yield of up to 40.37 mol%. Moreover, the process conditions are relatively controllable, providing a new technical path for the preparation of high-value-added platform compounds from cellulosic biomass. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the preparation of the catalyst and the catalytic reaction process of this invention.

[0026] Figure 2 The images shown are SEM images of the SAC-100 sulfonated carbon catalyst in Example 1 of this invention. (a) is a low-magnification image, and (b) is a high-magnification image.

[0027] Figure 3 This is a GC-MS image of the liquid phase products of the catalytic reaction. Detailed Implementation

[0028] The following examples are used to further illustrate the present invention and are not intended to limit the invention.

[0029] Example 1:

[0030] The preparation steps of SAC-80 catalyst are as follows:

[0031] (1) Weigh 1.0000 g of activated carbon and add it to a reaction vessel containing 10.0000 g of concentrated sulfuric acid with a mass fraction of 98 wt%, wherein the mass ratio of activated carbon to concentrated sulfuric acid is 1:10. Stir at room temperature for 10 min to obtain the first mixture.

[0032] (2) The first mixture obtained in step (1) is placed in an oil bath and subjected to sulfonation reaction at 80°C for 4.0 h to obtain the second mixture;

[0033] (3) After the reaction in step (2) is completed, the second mixture is naturally cooled to 25°C to obtain the sulfonation reaction solution;

[0034] (4) Transfer the sulfonation reaction solution obtained in step (3) to a centrifuge tube, centrifuge at 8000 rpm for 5 min, discard the supernatant, and collect the solid product;

[0035] (5) The washed solid product obtained in step (4) is placed in a vacuum drying oven and dried at 80°C for 12 h to obtain sulfonated carbon catalyst, denoted as SAC-80.

[0036] Example 2:

[0037] The preparation steps of the SAC-100 catalyst are as follows:

[0038] (1) Weigh 1.0000 g of activated carbon and add it to a reaction vessel containing 10.0000 g of concentrated sulfuric acid with a mass fraction of 98 wt%, wherein the mass ratio of activated carbon to concentrated sulfuric acid is 1:10. Stir at room temperature for 10 min to obtain the first mixture.

[0039] (2) The first mixture obtained in step (1) is placed in an oil bath and subjected to sulfonation at 100°C for 4.0 h to obtain the second mixture;

[0040] (3) After the reaction in step (2) is completed, the second mixture is naturally cooled to 25°C to obtain the sulfonation reaction solution;

[0041] (4) Transfer the sulfonation reaction solution obtained in step (3) to a centrifuge tube, centrifuge at 8000 rpm for 5 min, discard the supernatant, and collect the solid product;

[0042] (5) The washed solid product obtained in step (4) is placed in a vacuum drying oven and dried at 80°C for 12 h to obtain sulfonated carbon catalyst, denoted as SAC-100.

[0043] Example 3:

[0044] The steps for preparing L-glucanone from microcrystalline cellulose using SAC-80 catalysis are as follows:

[0045] (1) Weigh 0.1000 g of microcrystalline cellulose and 0.4000 g of sulfonated carbon catalyst SAC-80 prepared in Example 1 and add them to the polytetrafluoroethylene liner of a 50 mL high-pressure reactor;

[0046] (2) Add 30.0 mL of tetrahydrofuran to the polytetrafluoroethylene liner obtained in step (1), mix well, and obtain the reaction system;

[0047] (3) Load the reaction system obtained in step (2) into a high-pressure reactor and seal it;

[0048] (4) Place the high-pressure reactor obtained in step (3) into the reaction apparatus and heat it to 210°C under stirring at 600 rpm;

[0049] (5) After the reaction system obtained in step (4) reaches 210°C, maintain the temperature for 20 min to obtain the reaction mixture;

[0050] (6) After the reaction in step (5) is completed, stop heating and allow the reaction mixture obtained in step (5) to cool naturally to 25°C;

[0051] (7) Take out the reaction mixture after cooling in step (6), transfer it to a centrifuge tube, and centrifuge at 8000 rpm for 5 min to obtain solid product and liquid product;

[0052] (8) Take the liquid product obtained in step (7), add dodecane as an internal standard, mix well and take a sample to obtain the sample to be tested;

[0053] (9) The sample obtained in step (8) was analyzed by gas chromatography-mass spectrometry (GC-MS) to determine the content of L-glucanone and byproducts, and the yield of L-glucanone was calculated by internal standard method to be 40.37 mol.

[0054] Example 4:

[0055] The steps for preparing L-glucanone from microcrystalline cellulose using SAC-100 catalysis are as follows:

[0056] (1) Weigh 0.1000 g of microcrystalline cellulose and 0.4000 g of sulfonated carbon catalyst SAC-100 prepared in Example 2 and add them to the polytetrafluoroethylene liner of a 50 mL high-pressure reactor.

[0057] (2) Add 30.0 mL of tetrahydrofuran to the polytetrafluoroethylene liner obtained in step (1), mix well, and obtain the reaction system;

[0058] (3) Load the reaction system obtained in step (2) into a high-pressure reactor and seal it;

[0059] (4) Place the high-pressure reactor obtained in step (3) into the reaction apparatus and heat it to 210°C under stirring at 600 rpm;

[0060] (5) After the reaction system obtained in step (4) reaches 210℃, maintain the temperature for 50 min to obtain the reaction mixture;

[0061] (6) After the reaction in step (5) is completed, stop heating and allow the reaction mixture obtained in step (5) to cool naturally to 25°C;

[0062] (7) Take out the reaction mixture after cooling in step (6), transfer it to a centrifuge tube, and centrifuge at 8000 rpm for 5 min to obtain solid product and liquid product;

[0063] (8) Take the liquid product obtained in step (7), add dodecane as an internal standard, mix well and take a sample to obtain the sample to be tested;

[0064] (9) The sample to be tested obtained in step (8) was analyzed by gas chromatography-mass spectrometry (GC-MS) to determine the content of L-glucanone and by-products, and the yield of L-glucanone was calculated by internal standard method.

[0065] (10) The test results showed that under the above conditions, microcrystalline cellulose was catalytically converted into L-glucose ketone, and the yield of L-glucose ketone was 29.35 mol.

[0066] Example 5

[0067] The steps for preparing L-glucanone from cotton powder using SAC-100 catalysis are as follows:

[0068] (1) Select cotton powder as waste cellulose biomass raw material, place the cotton powder in a forced-air drying oven and dry it at 80℃ for 12 h;

[0069] (2) Grind the cotton powder dried in step (1) and pass it through a 100-mesh sieve. Collect the sample that passes through the sieve to obtain the pretreated cotton powder sample.

[0070] (3) Weigh 0.1000 g of the pretreated cotton powder sample obtained in step (2) and 0.4000 g of the sulfonated carbon catalyst SAC-100 prepared in Example 2, and add them to the polytetrafluoroethylene liner of a 50 mL high-pressure reactor.

[0071] (4) Add 30.0 mL of tetrahydrofuran to the polytetrafluoroethylene liner obtained in step (3), mix well, and obtain the reaction system;

[0072] (5) Load the reaction system obtained in step (4) into a high-pressure reactor and seal it;

[0073] (6) Place the high-pressure reactor obtained in step (5) into the reaction apparatus and heat it to 210°C under stirring at 600 rpm;

[0074] (7) After the reaction system obtained in step (6) reaches 210℃, maintain the temperature for 20 min to obtain the reaction mixture;

[0075] (8) After the reaction in step (7) is completed, stop heating and allow the reaction mixture to cool naturally to 25°C;

[0076] (9) Take out the reaction mixture after cooling in step (8), transfer it to a centrifuge tube, and centrifuge at 8000 rpm for 5 min to obtain solid product and liquid product;

[0077] (10) Add dodecane as an internal standard to the liquid product obtained in step (9), mix well, and take a sample to obtain the sample to be tested;

[0078] (11) The sample to be tested obtained in step (10) was analyzed by gas chromatography-mass spectrometry (GC-MS), and the yield of L-glucanone (21.56 mol%) was calculated by internal standard method.

Claims

1. A method for preparing L-glucosamine from cellulose using sulfonated carbon catalysis, characterized in that... Specifically, the steps include the following: (1) Mix cellulose, sulfonated carbon catalyst and organic solvent to obtain a reaction system; wherein the mass ratio of cellulose to sulfonated carbon catalyst is 1:1-1:10; (2) Place the reaction system obtained in step (1) in a closed reactor and react at 150-300℃ for 1-120 min; (3) After the reaction is completed, the reaction system obtained in step (2) is cooled and solid-liquid separation is performed to recover the sulfonated carbon catalyst and obtain the liquid phase product; (4) Analyze or separate the liquid phase product obtained in step (3) to obtain L-glucose ketone.

2. The method for preparing L-glucosamine ketone from cellulose using sulfonated carbon catalysis according to claim 1, characterized in that... The organic solvent mentioned in step (1) is a polar aprotic solvent, which is selected from one or more of tetrahydrofuran, 1,4-dioxane, diethyl ether, isopropyl ether, tert-butyl methyl ether, acetonitrile, propionitrile, acetone, butanone, cyclohexanone, ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, dimethyl carbonate, diethyl carbonate, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, tetramethyl sulfoxide, or sulfolane.

3. The method for preparing L-glucosamine ketone from cellulose using sulfonated carbon catalysis according to claim 1, characterized in that... The cellulose biomass mentioned in step (1) includes microcrystalline cellulose and waste cellulose biomass. The waste cellulose biomass is selected from one or more of the following: wheat straw, corn straw, rice straw, sorghum straw, cotton straw, soybean straw, corn cob, peanut shell, rice shell, coconut shell, sawdust, wood chips, shavings, branches, bagasse, waste paper, corrugated paper, cardboard, cotton fiber waste, waste cotton cloth, hemp fiber waste, bamboo powder, bamboo chips, or wood powder.

4. The method for preparing L-glucosamine ketone from cellulose using sulfonated carbon catalysis according to claim 1, characterized in that... The reaction temperature in step (2) is 150-300℃ and the reaction time is 10-60 min.

5. The method for preparing L-glucosamine ketone from cellulose using sulfonated carbon catalysis according to claim 1, characterized in that... The preparation steps of the sulfonated carbon catalyst in step (1) are as follows: the carbon support and concentrated sulfuric acid are mixed in a reaction vessel and sulfonated at 80-100℃. Then, after solid-liquid separation, the solid product obtained is the sulfonated carbon catalyst.

6. The method for preparing L-glucosamine ketone from cellulose using sulfonated carbon catalysis according to claim 5, characterized in that... The carbon support is selected from one or more of activated carbon, mesoporous carbon, microporous carbon, ordered mesoporous carbon, or carbon molecular sieves.

7. The application of L-glucanone obtained by the preparation method as described in claim 1 in the catalytic conversion of waste biomass.

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