High value-added utilization method of cellulosic ethanol vinasse
By dehydrating, cooking, and modifying cellulose ethanol lees, high-purity cellulose and lignin are separated, and lignin adhesives for papermaking are prepared. This solves the problem of high cost and low value in cellulose ethanol lees treatment, and achieves efficient utilization and improved economic benefits.
Patent Information
- Application Number
- CN202510870972.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-26
- Publication Date
- 2025-10-17
AI Technical Summary
The treatment of cellulosic ethanol lees is simple and crude, resulting in high costs and low value. It is difficult to effectively utilize lignin and cellulose, and traditional adhesives rely on petrochemical raw materials, which poses pollution problems.
Cellulose and lignin are separated by dehydrating cellulose ethanol lees and then mixing and cooking it with an alkali agent. The lignin adhesive is then modified and used with pure cellulose for papermaking. The reaction conditions and concentration process are controlled to improve the utilization rate of lignin.
It achieves efficient separation and utilization of high-purity cellulose and lignin adhesives, increases lignin utilization to over 99%, reduces energy consumption and costs, improves economic value, and enhances paper quality.
Smart Images
Figure SMS_1
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of distiller's grains recycling, and particularly relates to a high-value utilization method of cellulose ethanol distiller's grains. BACKGROUND
[0002] Cellulose ethanol, also known as fuel ethanol, as an important biomass liquid fuel, its large-scale promotion is always subject to high production cost. In addition to the technical and economic challenges of pretreatment and enzymatic saccharification and other production links, the low-value disposal of distiller's grains (distillation residues) is also one of the key technologies that restrict the overall process profitability and sustainability.
[0003] In a typical corn and straw type lignocellulosic fuel ethanol production process (see: Chen YJ, Dai J, Shan JQ, et al. Research progress and development trend of cellulose ethanol in China [J]. Chemical Industry Progress, 2025, 44(5): 2544), after distillation of the fermentation broth to extract ethanol, the remaining distiller's grains are mainly composed of undegraded cellulose, hemicellulose, and complex and difficult-to-degrade lignin, and contain residual microorganisms, inorganic salts and a large amount of water, etc. The current mainstream treatment method is to separate the distiller's grains into solid and liquid, and then send the solid with a water content of less than 45% directly to the boiler for incineration for heat supply. However, this treatment method has high energy consumption cost. Alternatively, the solid after centrifugation can be used to produce organic fertilizer or compound feed. Although this method realizes the resource utilization of waste and has certain environmental benefits, it has the defects of limited nutritional value, low economic benefit, high transportation and application cost, etc.
[0004] In addition, traditional adhesives (such as styrene-butadiene latex and SA latex) rely on petrochemical raw materials and have problems of high pollution and non-renewable. The existing lignin-based adhesives mostly use papermaking black liquor to extract lignin, which has high cost and low purity due to a large amount of water. The lignin-based adhesive belongs to biomass adhesive, and lignin is one of the main components in cellulose ethanol distiller's grains. Since the lignin in cellulose ethanol distiller's grains is combined with cellulose, the distiller's grains cannot be used as an adhesive.
[0005] Due to the existence of technical barriers, the current treatment scheme of distiller's grains in the cellulose ethanol industry is simple and rough, and faces the dilemma of high cost and low value, which needs to be solved urgently. SUMMARY
[0006] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is to provide a high-value utilization method of cellulose ethanol distiller's grains, which integrates the production of high-purity cellulose and lignin adhesive and is used for papermaking, thereby improving the utilization rate of lignin and alleviating the shortage of paper pulp raw materials and other problems.
[0007] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a cellulose ethanol vinasse high added value utilization method, comprising the following steps: (1) dewatering the cellulose ethanol vinasse to a solid content ≥ 30%; (2) mixing and cooking the dewatered vinasse with an alkali agent to obtain cellulose-containing solids and a lignin alkali solution by separation; (3) washing and dewatering the cellulose-containing solids to obtain pure cellulose and a washing liquid, and combining the washing liquid with the lignin alkali solution to obtain a combined liquid; (4) concentrating the combined liquid to a solid content ≥ 20% to obtain a concentrated liquid; (5) adding an epoxidation reagent dropwise to the concentrated liquid to perform a modification reaction to obtain a lignin-based adhesive; (6) slurry mixing the pure cellulose with papermaking auxiliaries, and preparing paper through papermaking; The lignin-based adhesive is used for surface sizing or coating of the paper.
[0008] Further, the alkali agent in step (2) is sodium hydroxide, the ratio of the addition amount of the alkali agent to the dry mass of lignin in the dewatered vinasse is (0.25-0.45):1, and the reaction end point pH value is 12.5-13.5.
[0009] Further, the cooking conditions in step (2) are temperature 180-220℃, pressure 0.8-2.5MPa, and time 30-45min.
[0010] Further, the water content of the pure cellulose obtained in step (3) is ≤ 15%.
[0011] Further, the epoxidation reagent in step (5) is epichlorohydrin, and the ratio of the addition amount of the epoxidation reagent to the dry mass of lignin is (0.20-0.35):1.
[0012] Further, the reaction in step (5) is performed at pH 8.5-9.5 and temperature 40-70℃ for 1.5-2h, and sodium hydroxide is used for pH adjustment.
[0013] Further, the pure cellulose obtained in step (3) is subjected to bleaching treatment to a whiteness ≥ 85%ISO before being used in step (6).
[0014] Compared with the prior art, the present application has the following beneficial effects: The present application provides a method for high-value utilization of cellulose ethanol vinasse, which integrates the production of high-purity cellulose and lignin adhesive, overcomes the technical difficulties of efficient separation of lignin and cellulose in cellulose ethanol vinasse, and uses the separated lignin to make lignin adhesive, which is used in papermaking together with the separated cellulose, thereby improving the utilization rate of lignin and alleviating the shortage of paper pulp raw materials. Compared with the conventional incineration method, organic fertilizer method or feed method, the utilization rate of lignin is increased to more than 99%, which can increase the economic value by more than 10 times; the cellulose yield is high, which can replace wood or part of imported wood pulp, help achieve the double carbon goal, and to some extent, alleviate the shortage of paper pulp raw materials.
[0015] The cellulose ethanol vinasse high added value utilization method of the application, first step (1) directly obtains cellulose ethanol vinasse after distillation ethanol, dehydration, into a process material, dehydration to solid content ≥ 30% required energy consumption is reduced by more than 50% than traditional centrifugation and drying. Secondly step (2) the dewatered vinasse and alkali agent are mixed and cooked, the cooking conditions are temperature 180-220℃, pressure 0.8-2.5MPa, time 30-45min, while controlling the alkali dosage and pH, the preferred alkali agent is sodium hydroxide (solid state), the ratio of its addition amount to the dry basis mass of lignin in the dewatered vinasse is (0.25-0.45) : 1, and the reaction endpoint pH value is 12.5-13.5, by controlling the appropriate alkali dosage and the pH of the reaction system, on the one hand, compared with the conventional sodium hydroxide solution, the wastewater discharge can be reduced, on the other hand, the reaction conditions are reasonably controlled, the lignin dissolution rate is improved, the cellulose damage is reduced, and the strength basis is provided for subsequent papermaking utilization. Then steps (3)-(4), the cellulose-containing solid obtained in the immediately preceding step is dewatered, the washing liquid is combined with the lignin alkali solution, closed loop circulation is realized, the effect of wastewater reduction is achieved, and the solid content of the concentrated liquid is ≥ 20%, the reaction concentration of the immediately subsequent step is improved. Then step (5) the concentrated liquid is modified by epoxidation to prepare a lignin adhesive, the epoxidation reagent is epichlorohydrin, the ratio of its addition amount to the dry basis mass of lignin is (0.20-0.35) : 1, the reaction is carried out at pH 8.5-9.5, temperature 40-70℃ for 1.5-2h, the epichlorohydrin is ring opened under alkaline conditions, forms ether bond with the active groups (phenolic hydroxyl) of lignin, removes HCl to form new epoxy groups, gives lignin crosslinking activity, the epoxidation reagent is introduced in a slow dropwise manner in the whole process, the amount is strictly controlled to control the reaction heat release rate, reduce the hydrolysis side reaction of the epoxidation reagent under alkaline conditions, avoid excessive crosslinking reaction, the obtained product has lignin skeleton and epoxy side chain, as a paper adhesive, the performance advantage is more significant, the bonding strength is improved, the formaldehyde release amount is as low as zero, and the environmental protection value is more excellent. Finally, the extracted pure cellulose and lignin adhesive are used in papermaking production, the pure cellulose can replace wood or part of conifer pulp, the raw material cost is reduced, the lignin adhesive is coated on paper, the paper strength is improved, the paper quality is improved, and higher grade art paper can be obtained. DETAILED DESCRIPTION
[0016] In order to better understand the present application, the content of the present application is further clarified below in combination with examples, but the protection content of the present application is not limited to the following examples only. In the following description, a large number of specific details are given in order to provide a more complete understanding of the present application. However, it is obvious to those skilled in the art that the present application can be implemented without one or more of these details.
[0017] All other embodiments obtained by a person of ordinary skill in the art without creative labor based on the embodiments of the present application shall fall within the scope of protection of the present application.
[0018] In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary, and not as a limitation. Thus, other examples of the exemplary embodiments can have different values.
[0019] All raw materials are commercially available unless otherwise specified, and contain no components other than the components explicitly identified, unless otherwise specified.
[0020] In the following examples, the cellulosic ethanol stillage is derived from corn stalks for cellulosic ethanol production.
[0021] Example 1: A method for high value-added utilization of cellulosic ethanol stillage, comprising the following steps: (1) Dehydrating the cellulosic ethanol stillage to a solid content of 31.3%; (2) Cooking the dehydrated stillage with an alkali agent to separate a cellulose-containing solid and a lignin alkali solution; (3) Washing and dehydrating the cellulose-containing solid to obtain pure cellulose and a washing liquid, and combining the washing liquid with the lignin alkali solution to obtain a combined liquid; (4) Concentrating the combined liquid to a solid content of 20.5% to obtain a concentrated liquid; (5) Adding an epoxidation reagent dropwise to the concentrated liquid to perform a modification reaction to obtain a lignin-based adhesive; (6) Slurrying the pure cellulose with papermaking aids, and preparing paper through papermaking; The lignin-based adhesive is used for surface sizing or coating of the paper.
[0022] The alkali agent in step (2) is sodium hydroxide, and the ratio of the amount of the alkali agent added to the dry mass of lignin in the dehydrated stillage is 0.25, and the reaction endpoint pH value is 12.5.
[0023] The cooking conditions in step (2) are a temperature of 180°C, a pressure of 1.2 MPa, and a time of 45 min.
[0024] The water content of the pure cellulose obtained in step (3) is 24.3%.
[0025] The epoxidation reagent in step (5) is epichlorohydrin, and the ratio of the amount of the epoxidation reagent added to the dry mass of lignin is 0.23:1.
[0026] The reaction in step (5) is performed at a pH of 9.0 and a temperature of 55°C for 1.5 h, and sodium hydroxide is used for pH adjustment.
[0027] The pure cellulose obtained in step (3) is bleached to a whiteness of 86.4% ISO and then used in step (6).
[0028] Example 2: A high value-added utilization method of cellulose ethanol vinasse, comprising the following steps: (1) dewatering the cellulose ethanol vinasse to a solid content of 37.5%; (2) cooking the dewatered vinasse with an alkali agent, and separating to obtain cellulose-containing solids and a lignin alkali solution; (3) washing and dewatering the cellulose-containing solids to obtain pure cellulose and a washing liquid, and combining the washing liquid with the lignin alkali solution to obtain a combined liquid; (4) concentrating the combined liquid to a solid content of 23.1% to obtain a concentrated liquid; (5) adding an epoxidation reagent dropwise to the concentrated liquid to perform a modification reaction, and obtaining a lignin-based adhesive; (6) slurrying the pure cellulose with papermaking auxiliaries, and preparing paper by papermaking; The lignin-based adhesive is used for surface sizing or coating of the paper.
[0029] In step (2), the alkali agent is sodium hydroxide, the ratio of the amount of the alkali agent to the dry mass of lignin in the dewatered vinasse is 0.30:1, and the reaction end point pH value is 12.8.
[0030] In step (2), the cooking conditions are a temperature of 190°C, a pressure of 0.8 MPa, and a time of 40 min.
[0031] The water content of the pure cellulose obtained in step (3) is 24.8%.
[0032] In step (5), the epoxidation reagent is epichlorohydrin, and the ratio of the amount of the epoxidation reagent to the dry mass of lignin is 0.25:1.
[0033] In step (5), the reaction is performed at a pH of 8.8 and a temperature of 60°C for 1.5 h, and sodium hydroxide is used for pH adjustment.
[0034] The pure cellulose obtained in step (3) is bleached to a whiteness of 89.2% ISO and then used in step (6).
[0035] Example 3: A high value-added utilization method of cellulose ethanol vinasse, comprising the following steps: (1) dewatering the cellulose ethanol vinasse to a solid content of 36.4%; (2) cooking the dewatered vinasse with an alkali agent, and separating to obtain cellulose-containing solids and a lignin alkali solution; (3) washing and dewatering the cellulose-containing solids to obtain pure cellulose and a washing liquid, and combining the washing liquid with the lignin alkali solution to obtain a combined liquid; (4) concentrating the combined solution to a solid content of 22.8% to obtain a concentrated solution; (5) adding an epoxidation reagent dropwise to the concentrated solution to perform a modification reaction to obtain a lignin-based adhesive; (6) preparing paper by mixing pure cellulose with papermaking additives; Among them, lignin-based adhesives are used for sizing or coating the surface of paper.
[0036] In step (2), the alkali agent is sodium hydroxide, and the ratio of the amount of sodium hydroxide added to the dry basis mass of lignin in the dehydrated vinasse is 0.40:1, and the pH value at the reaction endpoint is 13.0.
[0037] The cooking conditions in step (2) are temperature 200° C., pressure 2.0 MPa, and time 35 min.
[0038] The moisture content of the pure cellulose obtained in step (3) is 23.7%.
[0039] In step (5), the epoxidation reagent is epichlorohydrin, and the ratio of its addition amount to the dry basis mass of lignin is 0.30:1.
[0040] The reaction in step (5) was carried out at pH 8.5 and 40° C. for 2 h, and the pH was adjusted using sodium hydroxide.
[0041] The pure cellulose obtained in step (3) is bleached to a whiteness of 87.3% ISO before being used in step (6).
[0042] Example 4: A method for high value-added utilization of cellulosic ethanol distiller's grains, comprising the following steps: (1) dehydrating cellulosic ethanol lees to a solid content of 32.5%; (2) mixing the dehydrated vinasse with an alkali agent and steaming the mixture to separate and obtain a cellulose-containing solid and a lignin alkaline solution; (3) washing and dehydrating the cellulose-containing solid to obtain pure cellulose and a washing liquid, and combining the washing liquid with a lignin alkaline solution to obtain a combined liquid; (4) concentrating the combined solution to a solid content of 21.7% to obtain a concentrated solution; (5) adding an epoxidation reagent dropwise to the concentrated solution to perform a modification reaction to obtain a lignin-based adhesive; (6) preparing paper by mixing pure cellulose with papermaking additives; Among them, lignin-based adhesives are used for sizing or coating the surface of paper.
[0043] In step (2), the alkali agent is sodium hydroxide, and the ratio of the amount of sodium hydroxide added to the dry weight of lignin in the dehydrated vinasse is 0.45:1, and the pH value at the reaction endpoint is 13.5.
[0044] The cooking conditions in step (2) are temperature 210℃, pressure 2.3MPa, and time 32min.
[0045] The moisture content of the pure cellulose obtained in step (3) is 24.5%.
[0046] The epoxidation reagent in step (5) is epichlorohydrin, and the ratio of the addition amount to the dry mass of lignin is 0.20:1.
[0047] The reaction in step (5) is carried out at pH 9.2 and temperature 45℃ for 1.8h, and pH adjustment is performed using sodium hydroxide.
[0048] The pure cellulose obtained in step (3) is subjected to bleaching treatment to whiteness 90.5%ISO, and then used in step (6).
[0049] Embodiment 5: A method for high value-added utilization of cellulose ethanol vinasse, comprising the following steps: (1) Dehydrating the cellulose ethanol vinasse to solid content 34.2%; (2) Cooking the dehydrated vinasse with an alkali agent to separate cellulose-containing solids and a lignin alkali solution; (3) Washing and dehydrating the cellulose-containing solids to obtain pure cellulose and a washing liquid, and combining the washing liquid with the lignin alkali solution to obtain a combined liquid; (4) Concentrating the combined liquid to solid content 23.8% to obtain a concentrated liquid; (5) Adding an epoxidation reagent dropwise to the concentrated liquid to perform a modification reaction to obtain a lignin-based adhesive; (6) Slurrying the pure cellulose with papermaking auxiliaries to prepare paper by papermaking; The lignin-based adhesive is used for surface sizing or coating of the paper.
[0050] The alkali agent in step (2) is sodium hydroxide, and the ratio of the addition amount to the dry mass of lignin in the dehydrated vinasse is 0.35:1, and the reaction end point pH value is 12.9.
[0051] The cooking conditions in step (2) are temperature 220℃, pressure 2.5MPa, and time 30min.
[0052] The moisture content of the pure cellulose obtained in step (3) is 23.4%.
[0053] The epoxidation reagent in step (5) is epichlorohydrin, and the ratio of the addition amount to the dry mass of lignin is 0.35:1.
[0054] The reaction in step (5) is carried out at pH 9.5 and temperature 50℃ for 1.5h, and pH adjustment is performed using sodium hydroxide.
[0055] The pure cellulose obtained in step (3) is used in step (6) after being bleached to a whiteness of 85.6% ISO.
[0056] Example 6: A method for high value-added utilization of cellulose ethanol vinasse, comprising the following steps: (1) dewatering the cellulose ethanol vinasse to a solid content of 33.7%; (2) cooking the dewatered vinasse with an alkali agent to separate cellulose-containing solids and a lignin alkali solution; (3) washing and dewatering the cellulose-containing solids to obtain pure cellulose and a washing liquid, and combining the washing liquid with the lignin alkali solution to obtain a combined liquid; (4) concentrating the combined liquid to a solid content of 25.1% to obtain a concentrated liquid; (5) adding an epoxidation reagent dropwise to the concentrated liquid to perform a modification reaction to obtain a lignin-based adhesive; (6) slurrying the pure cellulose with papermaking auxiliaries to prepare paper by papermaking; The lignin-based adhesive is used for surface sizing or coating of the paper.
[0057] In step (2), the alkali agent is sodium hydroxide, the ratio of the amount of the alkali agent added to the dry mass of lignin in the dewatered vinasse is 0.32:1, and the reaction end point pH value is 13.1.
[0058] The cooking conditions in step (2) are a temperature of 210°C, a pressure of 1.3 MPa, and a time of 38 min.
[0059] The water content of the pure cellulose obtained in step (3) is 24.6%.
[0060] In step (5), the epoxidation reagent is epichlorohydrin, and the ratio of the amount of the epoxidation reagent added to the dry mass of lignin is 0.32:1.
[0061] The reaction in step (5) is performed at a pH of 9.2 and a temperature of 70°C for 1.6 h, and sodium hydroxide is used for pH adjustment.
[0062] The pure cellulose obtained in step (3) is used in step (6) after being bleached to a whiteness of 90.2% ISO.
[0063] Comparative Example 1: The comparative example differs from Example 1 in that the cooking time in step (2) is 50 min, the cooking end point pH is 11.2, and the other conditions are unchanged.
[0064] Comparative Example 2: The comparative example differs from Example 1 in that the ratio of the amount of the alkali agent added to the dry mass of lignin in the dewatered vinasse in step (2) is 0.20:1.
[0065] Comparative Example 3: The difference between this comparative example and Example 1 is that the reaction in step (5) was carried out at pH 9.0 and a temperature of 75°C for 2.3 h.
[0066] Example 7: A papermaking process based on the pure cellulose and lignin-based adhesive extracted from distiller's grains was used to make art paper, which included: (1) The pure cellulose was bleached and pulped, and the pulp had a degree of beating of 30-32°SR and a fiber length of 1.0-1.2 mm to obtain a pure cellulose pulp; (2) Calcium carbonate, polyacrylamide, and a defoaming agent were added to the pure cellulose pulp to prepare a pulp, wherein the mass ratio of the pure cellulose pulp, calcium carbonate, polyacrylamide, and defoaming agent was 100:20:0.1:0.02 based on the mass of the dry cellulose, and the pulp concentration was 3.0%; (3) The pulp was sequentially subjected to papermaking, pressing, dewatering, and drying to obtain a raw paper, and the thickness of the raw paper was 75 um; (4) The raw paper was sized on both sides, wherein: the sizing liquid formulation for the front side was: kaolin 70%, calcium carbonate 25%, lignin adhesive 5%, solid content 10%, and sizing amount 10 g / m 2 ; and the sizing liquid formulation for the back side was: kaolin 60%, calcium carbonate 35%, lignin adhesive 5%, solid content 10%, and sizing amount 8 g / m 2 ; (5) The sized raw paper was calendered, the front side was calendered at a temperature of 130°C, the back side was calendered at a temperature of 100°C, the calendering pressure was 200 kN / m 2 , to obtain the art paper.
[0067] The pure cellulose and lignin adhesive used above were the products prepared in Example 1.
[0068] Example 8: The pure cellulose and lignin adhesive prepared in Example 2 were used to make art paper, and the process was referred to Example 7.
[0069] Example 9: The pure cellulose and lignin adhesive prepared in Example 3 were used to make art paper, and the process was referred to Example 7.
[0070] Comparative Example 4: The difference between this comparative example and Example 7 is that a commercially available styrene-butadiene latex was used instead of the lignin adhesive, and the other conditions were unchanged.
[0071] Comparative Example 5: The pure cellulose and lignin adhesive prepared in Comparative Example 1 were used to make art paper, and the process was referred to Example 7.
[0072] Comparative Example 6: The pure cellulose and lignin adhesive prepared in Comparative Example 2 were used to make art paper, and the process was referred to Example 7.
[0073] Comparative Example 7: The copper printing paper was prepared by using the pure cellulose and lignin adhesive prepared in Comparative Example 3 according to the process of Example 7.
[0074] The performance of the copper printing paper prepared in Examples 7-9 and Comparative Examples 4-7 was detected according to the technical index of GB / T10335.1-2017, and the overall index evaluation results were as follows: The above results show that the pure cellulose and lignin adhesive extracted by the method of the present application can be used to prepare copper printing paper, and the prepared copper printing paper meets the technical index requirements of first-class products; at the same time, the performance of the lignin adhesive produced is basically the same as the effect achieved by the commercially available butyl rubber latex of Comparative Example 4; and it is also shown that the pure cellulose produced by the present application can be used in combination with the commercially available petroleum-based adhesive butyl rubber latex, and has good adaptability. The effects of the pure cellulose and lignin adhesive obtained by changing the parameter conditions of the key steps (2) or (5) in Comparative Examples 5-7 are not as good as or significantly worse than that of Example 7, indicating the scientificity and overall coordination of the control of the key step conditions of the cellulose ethanol vinasse high value-added utilization method of the present application, and the overall effect achieved is more significant.
[0075] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and not to limit it, and other modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art should be covered within the scope of the claims of the present application as long as they do not deviate from the spirit and scope of the technical solutions of the present application.
Claims
1. A method for high value-added utilization of cellulosic ethanol distiller's grains, characterized by: The following steps are involved: (1) dehydrating cellulosic ethanol lees to a solid content of ≥30%; (2) mixing the dehydrated vinasse with an alkali agent and steaming the mixture to separate and obtain a cellulose-containing solid and a lignin alkaline solution; (3) washing and dehydrating the cellulose-containing solid to obtain pure cellulose and a washing liquid, and combining the washing liquid with a lignin alkaline solution to obtain a combined liquid; (4) concentrating the combined solution to a solid content of ≥20% to obtain a concentrated solution; (5) adding an epoxidation reagent dropwise to the concentrated solution to perform a modification reaction to obtain a lignin-based adhesive; (6) preparing paper by mixing pure cellulose with papermaking additives; The lignin-based adhesive is used for sizing or coating the surface of paper.
2. The method for high value-added utilization of cellulosic ethanol distiller's grains according to claim 1, characterized in that: The alkali agent in step (2) is sodium hydroxide, and the ratio of the amount of sodium hydroxide added to the dry basis mass of lignin in the dehydrated vinasse is (0.25-0.45):1, and the pH value at the end point of the reaction is 12.5-13.
5.
3. The method for high value-added utilization of cellulosic ethanol distiller's grains according to claim 1, characterized in that: The cooking conditions in step (2) are temperature 180-220° C., pressure 0.8-2.5 MPa, and time 30-45 min.
4. The method for high value-added utilization of cellulosic ethanol distiller's grains according to claim 1, characterized in that: The moisture content of the pure cellulose obtained in step (3) is ≤15%.
5. The method for high value-added utilization of cellulosic ethanol distiller's grains according to claim 1, characterized in that: The epoxidation reagent in step (5) is epichlorohydrin, and the ratio of its addition amount to the dry weight of lignin is (0.20-0.35):
1.
6. The method for high value-added utilization of cellulosic ethanol distiller's grains according to claim 5, characterized in that: The reaction in step (5) is carried out at a pH of 8.5-9.5 and a temperature of 40-70° C. for 1.5-2 hours, and sodium hydroxide is used to adjust the pH.
7. The method for high value-added utilization of cellulosic ethanol distiller's grains according to any one of claims 1 to 6, characterized in that: The pure cellulose obtained in step (3) is bleached to a whiteness of ≥85% ISO before being used in step (6).