A reagent for oxidatively degrading lignin and a method for efficiently removing lignin

Abstract

The application provides a reagent for oxidatively degrading lignin and a method for efficiently removing lignin, and belongs to the technical field of degradation and conversion of agricultural and forestry biomass. The reagent for oxidatively degrading lignin provided by the application is prepared from a preparation raw material including a hydrogen peroxide solution, an alkyl acetate and a hydrolysis catalyst; the concentration of the hydrogen peroxide solution is 8-15 wt%; the volume ratio of the hydrogen peroxide solution to the alkyl acetate is 4-6:6-4; and the volume of the hydrolysis catalyst accounts for 1.0-1.5% of the total volume of the hydrogen peroxide solution and the alkyl acetate. The hydrogen peroxide solution with a concentration of 8-15 wt% is used to establish a hydrogen peroxide-alkyl acetate system, peracetic acid can be generated in situ, the reaction system is free of pressure and safety hazards during oxidation, and wood lignin can be removed with high selectivity under the condition of ≥60 DEG C.

Description

Technical Field

[0001] This invention belongs to the field of agricultural and forestry biomass degradation and conversion technology, specifically relating to a reagent for oxidative degradation of lignin and a method for efficiently removing lignin. Background Technology

[0002] Currently, in the biorefining of lignocellulose, carbohydrate platforms of cellulose and hemicellulose can serve as raw materials for the preparation of bioenergy, pulp and paper, and nanocellulose. The biochemical conversion of cellulose raw materials can be used to synthesize ethanol, glycerol, propionic acid, and succinic acid. Furthermore, nanocellulose extracted from lignocellulose possesses attractive properties such as high strength, excellent stiffness, and high surface area. In addition, nanocellulose contains a large number of hydroxyl groups, which can be used for surface modification. However, lignin is considered a significant obstacle to biomass bioconversion, preventing enzymes or chemical reagents from approaching cellulose and causing inhibition during the bioconversion process. Biorefining technologies based on carbohydrate platforms require the preferential degradation of lignin components to break down the degradation barrier of lignocellulose. Moreover, in the pulp and paper industry, lignin is considered to have an adverse effect on paper durability. Therefore, lignin removal is necessary.

[0003] In existing technologies, lignin is removed through oxidative depolymerization, a method characterized by relatively mild reaction conditions (80°C) and high selectivity. Peracetic acid, acting as an electrophilic agent, reacts with lignin, leading to oxidation and subsequent degradation. Peracetic acid is considered environmentally friendly, possessing a high oxidation potential (1.748 V), and is a promising selective agent for delignification. Its principle involves peracetic acid-mediated lignin oxidation, which can cleave C / C and CO bonds linked to aromatic rings, as well as phenylpropane units linked to ethers. However, peracetic acid is expensive, extremely unstable, and prone to explosion at high concentrations, increasing storage and transportation costs. One technical solution uses a 30% hydrogen peroxide and acetic acid solution to synthesize peracetic acid in situ at 80°C to treat poplar wood, achieving a lignin removal rate of 86%. Although this system can synthesize peracetic acid in situ, the high concentrations of acetic acid and 30% hydrogen peroxide, along with the large dosages of hydrogen peroxide and acetic acid in the final hydrogen peroxide-acetic acid solution (12 wt% hydrogen peroxide and 40 wt% acetic acid), lead to high pressure and a high risk of explosion during the decomposition process of hydrogen peroxide and peracetic acid, posing a safety hazard. Summary of the Invention

[0004] The purpose of this invention is to provide a reagent for oxidative degradation of lignin and a method for efficient lignin removal. This invention uses a hydrogen peroxide solution with a concentration of 8-15 wt% to prepare a hydrogen peroxide-ethyl acetate system. This system has no pressure and no risk of explosion during oxidation treatment, and can achieve safe lignin removal.

[0005] To achieve the objectives of this invention, the following technical solutions are provided:

[0006] A reagent for the oxidative degradation of lignin, the raw materials for preparation include: hydrogen peroxide solution, alkyl acetate and hydrolysis catalyst;

[0007] The concentration of the hydrogen peroxide solution is 8-15 wt%; the volume ratio of the hydrogen peroxide solution to the alkyl acetate is 4-6:6-4.

[0008] The volume of the hydrolysis catalyst accounts for 1.0 to 1.5% of the total volume of the hydrogen peroxide solution and the alkyl acetate.

[0009] Preferably, the alkyl acetate includes one or more of methyl acetate, ethyl acetate, and propyl acetate.

[0010] Preferably, the hydrolysis catalyst comprises one or more of sulfuric acid, hydrochloric acid, and nitric acid.

[0011] This invention also provides a method for efficiently removing lignin, comprising the following steps:

[0012] The wood is mixed with the reagent for oxidative degradation of lignin described in the above technical solution, and subjected to oxidation treatment. After solid-liquid separation, lignin-free holocellulose residue is obtained.

[0013] The oxidation treatment temperature is ≥60℃.

[0014] Preferably, the solid-liquid ratio of the wood and the reagent used for oxidative degradation of lignin is 1g:5-12mL.

[0015] Preferably, the oxidation treatment time is 4 to 12 hours.

[0016] Preferably, the method further includes enzymatically hydrolyzing the holocellulose residue to obtain an enzymatic hydrolysate containing glucose.

[0017] Preferably, the enzyme reagent used for enzymatic hydrolysis is cellulase; the enzyme amount of the enzyme reagent is 5-20 FPU / g.

[0018] Preferably, the enzymatic hydrolysis is performed at a temperature of 40–60°C for 24–72 hours.

[0019] This invention provides a reagent for the oxidative degradation of lignin. The raw materials include: hydrogen peroxide solution, alkyl acetate, and a hydrolysis catalyst. The concentration of the hydrogen peroxide solution is 8–15 wt%. The volume ratio of the hydrogen peroxide solution to the alkyl acetate is 4–6:6–4. The volume of the hydrolysis catalyst accounts for 1.0–1.5% of the total volume of the hydrogen peroxide solution and the alkyl acetate. This invention establishes a hydrogen peroxide-alkyl acetate system using an 8–15 wt% hydrogen peroxide solution. The alkyl acetate is decomposed into acetic acid by the hydrolysis catalyst, and hydrogen peroxide and acetic acid are catalyzed to generate peracetic acid in situ. Peracetic acid is gradually synthesized. This reaction system is pressure-free and poses no safety hazards during oxidation, and can selectively remove lignin.

[0020] This invention also provides a highly efficient method for removing lignin, which can selectively remove lignin at ≥60℃. Furthermore, the holocellulose residue obtained after solid-liquid separation can be directly used to prepare bioenergy, chemicals, and chemical materials, or the lignin-removed holocellulose residue can be enzymatically hydrolyzed to obtain a glucose-containing hydrolysate. The liquid obtained from solid-liquid separation can be further separated to obtain quinone and carboxylic acid compounds such as 2,6-dimethoxy-1,4-benzoquinone, p-benzoquinone, malonic acid, maleic anhydride, and propionic acid, which can be used in the production of platform chemicals (such as phenobarbital) pharmaceutical intermediates. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart of the method for efficiently removing lignin according to the present invention. Detailed Implementation

[0023] This invention provides a reagent for the oxidative degradation of lignin, the raw materials for which include: hydrogen peroxide solution, alkyl acetate and hydrolysis catalyst;

[0024] The concentration of the hydrogen peroxide solution is 8-15 wt%; the volume ratio of the hydrogen peroxide solution to the alkyl acetate is 4-6:6-4.

[0025] The volume of the hydrolysis catalyst accounts for 1.0 to 1.5% of the total volume of the hydrogen peroxide solution and the alkyl acetate.

[0026] In this invention, unless otherwise specified, all raw materials are commercially available products well known to those skilled in the art.

[0027] In this invention, the concentration of the hydrogen peroxide solution is 8-15 wt%, and in specific embodiments, it can be 8 wt%, 10 wt%, or 15 wt%. The alkyl acetate includes one or more of methyl acetate, ethyl acetate, and propyl acetate, and in specific embodiments, it can be ethyl acetate. The volume ratio of the hydrogen peroxide solution to the alkyl acetate is 4-6:6-4, and in specific embodiments, it can be 5:5. This invention establishes a hydrogen peroxide-alkyl acetate system using a 5-15 wt% hydrogen peroxide solution, which can generate peracetic acid in situ. This reaction system is pressureless and poses no safety hazards during oxidation, and can selectively remove lignin from wood.

[0028] In this invention, the hydrolysis catalyst comprises one or more of sulfuric acid, hydrochloric acid, and nitric acid; in specific embodiments, it may be sulfuric acid. The concentration of the sulfuric acid is 50–98.3 wt%, and in specific embodiments, it may be 50 wt%, 70 wt%, or 98.3 wt%. The volume of the hydrolysis catalyst accounts for 1.0–1.5% of the total volume of the hydrogen peroxide solution and the alkyl acetate; in specific embodiments, it may be 1.0%, 1.2%, or 1.5%. In this invention, the hydrolysis catalyst serves as a bifunctional catalyst for the decomposition of ethyl acetate into acetic acid and for catalyzing the reaction of hydrogen peroxide and acetic acid to produce peracetic acid.

[0029] This invention also provides a method for efficiently removing lignin, comprising the following steps:

[0030] The wood is mixed with the reagent for oxidative degradation of lignin described in the above technical solution, and subjected to oxidation treatment. After solid-liquid separation, lignin-free holocellulose residue is obtained.

[0031] The oxidation treatment temperature is ≥60℃.

[0032] In this invention, the wood includes coniferous and / or broadleaf wood. In a specific embodiment, the broadleaf wood can be bamboo. The wood is also sieved before use. The mesh size of the sieve used for sieving is 40 to 80 mesh.

[0033] In this invention, the solid-liquid ratio of the wood and the reagent used for oxidative degradation of lignin is 1g:5-12mL. In specific embodiments, it can be 1g:6mL, 1g:8mL or 1g:10mL.

[0034] In this invention, the temperature of the oxidation treatment is ≥60℃, and in a specific embodiment, it can be 70℃ or 80℃; the time of the oxidation treatment is 4 to 12 hours, and in a specific embodiment, it can be 6 hours, 7 hours, 9 hours or 11 hours.

[0035] In this invention, the solid-liquid separation method can be vacuum filtration.

[0036] In this invention, after solid-liquid separation, a processed liquid is obtained; the processed liquid includes lignin oxidation products and acetic acid and ethanol solvents. The processed liquid can be further separated to obtain quinone and carboxylic acid compounds such as 2,6-dimethoxy-1,4-benzoquinone, p-benzoquinone, malonic acid, maleic anhydride, and propionic acid, which can be used in the production of platform chemicals (lumina, barbiturates) pharmaceutical intermediates; the subsequent separation methods of the processed liquid include: lipophilic organic solvent extraction: lipophilic organic solvents such as chloroform and benzene are used to extract quinone substances; alkaline extraction and acid precipitation: quinone substances are extracted with alkaline solution and then acidified to precipitate them; steam distillation: volatile small molecule benzoquinone compounds in lignin oxidation products are separated.

[0037] In this invention, the lignin-free holocellulose residue obtained after solid-liquid separation can be used to prepare bioenergy, chemicals and chemical materials.

[0038] In this invention, the lignin-free holocellulose residue can be hydrolyzed with organic acids to obtain xylooligosaccharides; or the lignin-free holocellulose residue can be modified and cross-linked with a chemical cross-linking agent to obtain a packaging film.

[0039] In this invention, the method further includes enzymatically hydrolyzing the holocellulose residue to obtain an enzymatic hydrolysate containing glucose; preferably, the enzyme reagent used for enzymatic hydrolysis is cellulase, and in a specific embodiment, it can be cellulase; the enzyme amount of the enzyme reagent is 5-20 FPU / g, and in a specific embodiment, it can be 10 FPU / g or 15 FPU / g; the enzyme amount mentioned in this invention refers to the amount of cellulase used to hydrolyze each gram of dry cellulose residue.

[0040] In this invention, the enzymatic hydrolysis temperature is 40–60°C, and in specific embodiments, it can be 40°C, 50°C, or 60°C; the time is 24–72 h, and in specific embodiments, it can be 48 h or 72 h; the enzymatic hydrolysis is carried out under stirring conditions; the stirring rate is 100–200 r / min, and in specific embodiments, it can be 150 r / min.

[0041] To further illustrate the present invention, the reagents for oxidative degradation of lignin and the method for efficiently removing lignin provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0042] Example 1

[0043] according to Figure 1 The flowchart shown illustrates the lignin removal process, with the following specific steps:

[0044] A 30 wt% hydrogen peroxide solution was diluted to a concentration of 15 wt%. The 15 wt% hydrogen peroxide solution was then mixed with ethyl acetate at a volume ratio of 5:5 to obtain a hydrogen peroxide-ethyl acetate system.

[0045] Weigh 1g of bamboo powder (cellulose content 35.4%, hemicellulose content 17.2%, lignin content 28.9%), mix it with the above 10mL hydrogen peroxide-ethyl acetate system and 0.1mL 98.3wt% sulfuric acid, and oxidize to remove lignin at 60℃ for 6h. After the removal is completed, filter to obtain holocellulose residue.

[0046] The composition of the treated holocellulose residue was analyzed using the NREL method. The results showed that the cellulose recovery rate was 90.3%, the hemicellulose recovery rate was 68.5%, and the lignin removal rate was 93.6%.

[0047] The above-mentioned holocellulose residue and cellulase were mixed according to an enzyme content of 10 FPU / g, and enzymatically hydrolyzed at 50℃ and 150 r / min for 72 h to obtain an enzymatic hydrolysate containing glucose; the glucose yield was 88.1%.

[0048] Example 2

[0049] A 30 wt% hydrogen peroxide solution was diluted to a concentration of 15 wt%. The 15 wt% hydrogen peroxide solution was then mixed with ethyl acetate at a volume ratio of 5:5 to obtain a hydrogen peroxide-ethyl acetate system.

[0050] Weigh 1g of bamboo powder, mix it with the above 10mL hydrogen peroxide-ethyl acetate system and 0.1mL of 98.3wt% sulfuric acid, and oxidize it at 60℃ for 4h to remove lignin. After the removal is completed, filter to obtain holocellulose residue.

[0051] The components of the treated holocellulose residue were analyzed using the NREL method. The results showed that the cellulose recovery rate was 92.4%, the hemicellulose recovery rate was 78.1%, and the lignin removal rate was 85.6%.

[0052] The above-mentioned holocellulose residue and cellulase were mixed according to an enzyme content of 10 FPU / g, and enzymatically hydrolyzed at 50℃ and 150 r / min for 72 h to obtain an enzymatic hydrolysate containing glucose; the glucose yield was 83.4%.

[0053] Example 3

[0054] A 30 wt% hydrogen peroxide solution was diluted to a concentration of 10 wt%. The 10 wt% hydrogen peroxide solution was then mixed with ethyl acetate at a volume ratio of 5:5 to obtain a hydrogen peroxide-ethyl acetate system.

[0055] Weigh 1g of bamboo powder, mix it with the above 10mL hydrogen peroxide-ethyl acetate system and 0.1mL of 98.3wt% sulfuric acid, and oxidize it at 60℃ for 6h to remove lignin. After the removal is completed, filter to obtain holocellulose residue.

[0056] The components of the treated holocellulose residue were analyzed using the NREL method. The results showed that the cellulose recovery rate was 91.2%, the hemicellulose recovery rate was 72.5%, and the lignin removal rate was 88.7%.

[0057] The above-mentioned holocellulose residue and cellulase were mixed according to an enzyme content of 10 FPU / g, and enzymatically hydrolyzed at 50℃ and 150 r / min for 72 h to obtain an enzymatic hydrolysate containing glucose; the glucose yield was 79.3%.

[0058] Example 4

[0059] A 30 wt% hydrogen peroxide solution was diluted to a concentration of 15 wt%. The 15 wt% hydrogen peroxide solution was then mixed with ethyl acetate at a volume ratio of 4:6 to obtain a hydrogen peroxide-ethyl acetate system.

[0060] Weigh 1g of bamboo powder, mix it with the above 10mL hydrogen peroxide-ethyl acetate system and 0.1mL of 98.3wt% sulfuric acid, and oxidize it at 60℃ for 6h to remove lignin. After the removal is completed, filter to obtain holocellulose residue.

[0061] The composition of the treated holocellulose residue was analyzed using the NREL method. The results showed that the cellulose recovery rate was 89.3%, the hemicellulose recovery rate was 71.2%, and the lignin removal rate was 87.0%.

[0062] The above-mentioned holocellulose residue and cellulase were mixed according to an enzyme content of 10 FPU / g, and enzymatically hydrolyzed at 50℃ and 150 r / min for 72 h to obtain an enzymatic hydrolysate containing glucose; the glucose yield was 88.1%.

[0063] Example 5

[0064] A 30 wt% hydrogen peroxide solution was diluted to a concentration of 10 wt%. The 10 wt% hydrogen peroxide solution was then mixed with ethyl acetate at a volume ratio of 5:5 to obtain a hydrogen peroxide-ethyl acetate system.

[0065] Weigh 1g of bamboo powder, mix it with the above 10mL hydrogen peroxide-ethyl acetate system and 0.15mL of 98.3wt% sulfuric acid, and oxidize it at 60℃ for 6h to remove lignin. After the removal is completed, filter to obtain holocellulose residue.

[0066] The composition of the treated holocellulose residue was analyzed using the NREL method. The results showed that the cellulose recovery rate was 90.5%, the hemicellulose recovery rate was 70.6%, and the lignin removal rate was 91.3%.

[0067] The above-mentioned holocellulose residue and cellulase were mixed according to an enzyme content of 10 FPU / g, and enzymatically hydrolyzed at 50℃ and 150 r / min for 72 h to obtain an enzymatic hydrolysate containing glucose; the glucose yield was 79.3%.

[0068] Example 6

[0069] A 30 wt% hydrogen peroxide solution was diluted to a concentration of 8 wt%. The 8 wt% hydrogen peroxide solution was then mixed with ethyl acetate at a volume ratio of 6:4 to obtain a hydrogen peroxide-ethyl acetate system.

[0070] Weigh 1g of bamboo powder, mix it with the above 10mL hydrogen peroxide-ethyl acetate system and 0.12mL of 98.3wt% sulfuric acid, and oxidize it at 70℃ for 8h to remove lignin. After the removal is completed, filter to obtain holocellulose residue.

[0071] The components of the treated holocellulose residue were analyzed using the NREL method. The results showed that the cellulose recovery rate was 91.3%, the hemicellulose recovery rate was 72.6%, and the lignin removal rate was 90.1%.

[0072] The above-mentioned holocellulose residue and cellulase were mixed according to an enzyme content of 10 FPU / g, and enzymatically hydrolyzed at 50℃ and 150 r / min for 72 h to obtain an enzymatic hydrolysate containing glucose; the glucose yield was 84.5%.

[0073] Comparative Example 1

[0074] A 30 wt% hydrogen peroxide solution was diluted to a concentration of 15 wt%. The 15 wt% hydrogen peroxide solution was then mixed with ethyl acetate at a volume ratio of 7:3 to obtain a hydrogen peroxide-ethyl acetate system.

[0075] Weigh 1g of bamboo powder and mix it with 10mL of the above hydrogen peroxide-ethyl acetate system and 0.1mL of 98.3wt% sulfuric acid. Oxidize and remove lignin at 50℃ for 8h. After the removal is completed, filter to obtain holocellulose residue.

[0076] The composition of the treated holocellulose residue was analyzed using the NREL method. The results showed that the cellulose recovery rate was 95.6%, the hemicellulose recovery rate was 94.7%, and the lignin removal rate was 37.5%.

[0077] The above-mentioned holocellulose residue and cellulase were mixed according to an enzyme content of 10 FPU / g, and enzymatically hydrolyzed at 50℃ and 150 r / min for 72 h to obtain an enzymatic hydrolysate containing glucose; the glucose yield was 69.3%.

[0078] Comparative Example 2

[0079] A 30 wt% hydrogen peroxide solution was diluted to a concentration of 15 wt%. The 15 wt% hydrogen peroxide solution was then mixed with ethyl acetate at a volume ratio of 5:5 to obtain a hydrogen peroxide-ethyl acetate system.

[0080] Weigh 1g of bamboo powder, mix it with the above 10mL hydrogen peroxide-ethyl acetate system and 0.1mL 98.3wt% sulfuric acid, and oxidize it at 50℃ for 4h to remove lignin. After the removal is completed, filter to obtain holocellulose residue.

[0081] The composition of the treated holocellulose residue was analyzed using the NREL method. The results showed that the cellulose recovery rate was 94.4%, the hemicellulose recovery rate was 92.2%, and the lignin removal rate was 42.6%.

[0082] The above-mentioned holocellulose residue and cellulase were mixed according to an enzyme content of 10 FPU / g, and enzymatically hydrolyzed at 50℃ and 150 r / min for 72 h to obtain an enzymatic hydrolysate containing glucose; the glucose yield was 72.5%.

[0083] Comparative Example 3

[0084] A 30 wt% hydrogen peroxide solution was diluted to a concentration of 15 wt%. The 15 wt% hydrogen peroxide solution was then mixed with ethyl acetate at a volume ratio of 5:5 to obtain a hydrogen peroxide-ethyl acetate system.

[0085] Weigh 1g of bamboo powder, mix it with the above 10mL hydrogen peroxide-ethyl acetate system and 0.05mL of 98.3wt% sulfuric acid, and oxidize it at 60℃ for 8h to remove lignin. After the removal is completed, filter to obtain holocellulose residue.

[0086] The components of the treated holocellulose residue were analyzed using the NREL method. The results showed that the cellulose recovery rate was 93.7%, the hemicellulose recovery rate was 83.5%, and the lignin removal rate was 65.3%.

[0087] The above-mentioned holocellulose residue and cellulase were mixed according to an enzyme content of 10 FPU / g, and enzymatically hydrolyzed at 50℃ and 150 r / min for 72 h to obtain an enzymatic hydrolysate containing glucose; the glucose yield was 79.5%.

[0088] Comparative Example 4

[0089] A 30 wt% hydrogen peroxide solution was diluted to a concentration of 5 wt%. The 5 wt% hydrogen peroxide solution was then mixed with ethyl acetate at a volume ratio of 5:5 to obtain a hydrogen peroxide-ethyl acetate system.

[0090] Weigh 1g of bamboo powder, mix it with the above 10mL hydrogen peroxide-ethyl acetate system and 0.1mL of 98.3wt% sulfuric acid, and oxidize it at 60℃ for 6h to remove lignin. After the removal is completed, filter to obtain holocellulose residue.

[0091] The composition of the treated holocellulose residue was analyzed using the NREL method. The results showed that the cellulose recovery rate was 95.6%, the hemicellulose recovery rate was 78.2%, and the lignin removal rate was 81.4%.

[0092] The above-mentioned holocellulose residue and cellulase were mixed according to an enzyme content of 10 FPU / g, and enzymatically hydrolyzed at 50℃ and 150 r / min for 72 h to obtain an enzymatic hydrolysate containing glucose; the glucose yield was 76.1%.

[0093] Based on the specific embodiments 1-6 and comparative examples 1-4 above, it can be seen that the hydrogen peroxide solution-ethyl acetate oxidation system provided by the present invention can efficiently and selectively remove lignin from bamboo. This is achieved when the hydrogen peroxide solution concentration is 8-15 wt%, the volume ratio of hydrogen peroxide solution to ethyl acetate is 4-6:6-4, the sulfuric acid catalyst dosage is 1.0-1.5% (v / v), and the reaction temperature is [not specified]. ≥ Under conditions of 60℃ and a treatment time of 4–12 h, the lignin removal rate in bamboo is as high as 85.6–93.6%, the cellulose recovery rate is 89.3–92.4%, the hemicellulose recovery rate is 68.5–78.1%, and the glucose yield from enzymatic hydrolysis is 79.3–88.1%.

[0094] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for efficiently removing lignin, characterized by, Includes the following steps: Wood and a reagent for oxidative degradation of lignin are mixed and subjected to oxidation treatment. After solid-liquid separation, lignin-free holocellulose residue is obtained. The oxidation treatment time is 4-12 hours. The solid-liquid ratio of the wood and the reagent for oxidative degradation of lignin is 1 g: 5-12 mL. The oxidation treatment temperature is ≥60℃; The reagent used for oxidative degradation of lignin is prepared from the following raw materials: hydrogen peroxide solution, alkyl acetate, and hydrolysis catalyst; The concentration of the hydrogen peroxide solution is 8-15 wt%; the volume ratio of the hydrogen peroxide solution to the alkyl acetate is 4-6:6-4. The volume of the hydrolysis catalyst accounts for 1.0 to 1.5% of the total volume of the hydrogen peroxide solution and the alkyl acetate.

2. The method of claim 1, wherein, The alkyl acetate includes one or more of methyl acetate, ethyl acetate, and propyl acetate.

3. The method of claim 1, wherein, The hydrolysis catalyst includes one or more of sulfuric acid, hydrochloric acid, and nitric acid.

4. The method of claim 1, wherein, It also includes enzymatically hydrolyzing the holocellulose residue to obtain an enzymatic hydrolysate containing glucose.

5. The method of claim 4, wherein, The enzyme reagent used for enzymatic hydrolysis is cellulase; the amount of enzyme reagent is 5~20 FPU / g.

6. The method of claim 4, wherein, The enzymatic hydrolysis is performed at a temperature of 40-60℃ for 24-72 hours.

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