Method for co-producing cellulose, xylose and lignin from lignocellulose raw material and application of method

Abstract

The invention discloses a method for co-producing cellulose, xylose and lignin from a lignocellulose raw material. The method provided by the invention comprises the following steps: step 1, carrying out acid impregnation on a crushed lignocellulose raw material, removing an acid impregnation liquid, and treating by adopting a steam explosion method to obtain a pretreated material; 2, washing the pretreated material with water, and carrying out solid-liquid separation to obtain a liquid phase I containing xylose and a solid material I; 3, carrying out alkali treatment on the solid material I, and carrying out solid-liquid separation to obtain a liquid phase II and a solid material II; optionally, washing the solid material II in the step 4, and carrying out solid-liquid separation to obtain a wet cellulose material and a liquid phase III; optionally, 5, drying the wet cellulose material to obtain cellulose; step 6, combining the liquid phase 2 and the optional liquid phase 3, carrying out acid treatment, and carrying out solid-liquid separation to obtain a wet lignin material; and optionally, 7, drying the wet lignin material to obtain the lignin. The separation method provided by the invention has the advantages of few types of used chemical reagents, simple process and better separation effect.

Description

Technical Field

[0001] The present invention relates to the technical field of biochemical production, and more particularly to a method and application of co-producing cellulose, xylose and lignin from lignocellulose raw materials. Background Art

[0002] Lignocellulose is the most abundant renewable resource in the world, and its main components are cellulose (30% to 40% of dry weight), hemicellulose (15% to 25% of dry weight) and lignin (15% to 20% of dry weight).

[0003] Cellulose is a chain polymer compound composed of D-glucose linked by β-1,4 glycosidic bonds. It is currently an important raw material for pulp, paper, textile and chemical fiber. With the development of nanotechnology, cellulose has developed into the field of nanomaterials and can be used to prepare high value-added products such as nanocellulose.

[0004] Hemicellulose is a heteropolymer composed of several different types of monosaccharides. It is easy to hydrolyze and mainly produces xylose. Xylose can be mainly used to produce xylitol, which is also widely used in food processing and pharmaceutical industries.

[0005] Lignin can be widely used in the preparation of phenolic resins, polyurethanes and other materials, can be used as filler to modify rubber, etc., and can also be used in carbon fiber materials, surfactants, flocculants, etc., and has great application value.

[0006] It can be seen that the separation of the components of cellulose, hemicellulose and lignin (hereinafter referred to as "three elements") in lignocellulose becomes the key. Therefore, a method for completely separating cellulose, hemicellulose and lignin in lignocellulose is needed. Summary of the invention

[0007] In order to solve the problems in the prior art, the present invention proposes a method and application of co-producing cellulose, xylose and lignin from lignocellulose raw materials. The method of the present invention can completely separate cellulose, hemicellulose and lignin, and co-produce cellulose, xylose and lignin, creating conditions for high value-added utilization of each component in lignocellulose.

[0008] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0009] One of the objects of the present invention is to provide a method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials, comprising the following steps:

[0010] Step 1: After the lignocellulose raw material is crushed and impurities are removed, it is acid-impregnated, and after the acid-impregnation liquid is removed, it is treated by steam explosion to obtain a pretreated material, in which the hemicellulose is hydrolyzed to obtain xylose; the acid-impregnation liquid after removal can be recycled and used in the acid-impregnation step;

[0011] Step 2, washing the pretreated material with water, and then performing solid-liquid separation to obtain a liquid phase 1 containing xylose and a solid material 1 containing cellulose and lignin;

[0012] Step 3, adding the solid material 1 into an alkali solution for alkali treatment, and then separating the solid and the liquid to obtain a liquid phase 2 and a solid material 2 containing cellulose;

[0013] Optionally, in step 4, the solid material 2 is washed with water, and then the solid and liquid are separated to obtain a cellulose wet material and a liquid phase 3;

[0014] Optionally, in step five, drying the wet cellulose material to obtain cellulose;

[0015] Step 6, after combining the liquid phase 2 and the optional liquid phase 3, adding acid for acid treatment, solid-liquid separation, to obtain lignin wet material and waste liquid;

[0016] Optionally, in step seven, the wet lignin material is dried to obtain lignin.

[0017] In the present invention, the lignocellulose raw material is crushed to a size of 1 to 10 cm.

[0018] The present invention adopts a pretreatment method combining acid impregnation and steam explosion, so that the structures among cellulose, hemicellulose and lignin are destroyed without being excessively decomposed into other impurities, which is more conducive to separation.

[0019] In the method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials of the present invention, preferably,

[0020] The lignocellulose raw material is selected from at least one of corn straw, corn cob, rice straw, wheat straw, reed and bean straw.

[0021] In the method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials of the present invention, preferably,

[0022] In step one,

[0023] The acid impregnation solution is a sulfuric acid solution, preferably the concentration of the sulfuric acid solution is 0.5wt% to 4wt%; and / or,

[0024] The acid immersion time is 2 to 20 minutes; and / or,

[0025] The acid impregnation temperature is 10 to 90°C; and / or,

[0026] After the acid pickling solution is removed, the acid pickling solution is recovered and used for the next acid pickling treatment;

[0027] The temperature of steam explosion treatment is 120℃~230℃;

[0028] The pressure of steam explosion treatment is 0.3MPaG~1.5MPaG;

[0029] The steam explosion treatment time is 20 minutes to 60 minutes.

[0030] In the method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials of the present invention, preferably,

[0031] In step 2 and step 4, the solid-liquid ratio during water washing is independently selected from 1:5 to 1:10, and the number of water washings is independently 2 to 10 times.

[0032] In the method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials of the present invention, preferably,

[0033] In step 2, step 3, step 4 and step 6, the solid-liquid separation method is independently selected from at least one of plate and frame filtration, centrifugal separation, screw extrusion dehydration and vacuum belt filtration.

[0034] In the method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials of the present invention, preferably,

[0035] In step 3, the alkali solution is an aqueous solution of an inorganic strong base, more preferably an aqueous solution of at least one alkali selected from sodium hydroxide, potassium hydroxide, and calcium hydroxide;

[0036] In the alkali solution, the dry matter concentration of the solid material 1 is 5 to 15% (g / g); and / or,

[0037] The amount of alkali added is 5% to 20% of the dry matter in the solid material; and / or,

[0038] The temperature of the alkali treatment is 20°C to 80°C; and / or,

[0039] The alkali treatment time is 1h to 4h.

[0040] In the method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials of the present invention, preferably,

[0041] In step 5 and step 7, the drying methods are independently selected from at least one of tube bundle drying, rotary drying, drum drying, and air flow drying.

[0042] In the method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials of the present invention, preferably,

[0043] In step 6, the acid used in the acid treatment is selected from inorganic strong acids, preferably at least one selected from sulfuric acid, hydrochloric acid, phosphoric acid, and nitric acid;

[0044] The amount of acid added is 1 to 1.5 times the amount of alkali added in the alkali treatment in step 3; and / or,

[0045] The temperature of the acid treatment is 20 to 50°C; and / or,

[0046] The acid treatment time is 0.5 to 2 hours.

[0047] In the method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials of the present invention, preferably,

[0048] In step six, after the acid treatment, the mixture is heated and then the solid-liquid separation is performed; preferably, the heating temperature is 70 to 90° C. and the heating time is 0.5 to 2 h.

[0049] The heating treatment after the acid treatment of the present invention can make the wood agglomerate, which is more conducive to the precipitation and separation of lignin.

[0050] A second object of the present invention is to provide an application of the method described in any one of the objects of the present invention in straw resource recovery.

[0051] In the method for co-producing cellulose, xylose and lignin from lignocellulose raw materials provided by the present invention, the separation process of each component is as follows:

[0052] Step 1, pretreating the lignocellulose raw material to obtain a pretreated material, wherein the hemicellulose is hydrolyzed to obtain xylose;

[0053] Step 2, washing and solid-liquid separation of the pretreated material obtained in step 1 to obtain a liquid phase containing xylose and a solid material containing cellulose and lignin;

[0054] Step 3, subjecting the solid material containing cellulose and lignin obtained in step 2 to an alkali treatment to dissolve the lignin therein, and then subjecting the solid to liquid separation to obtain a liquid phase containing lignin and a solid material containing cellulose;

[0055] Optionally, in step 4, washing the cellulose-containing solid material obtained in step 3 and separating the solid material to obtain a cellulose wet material and a washing liquid containing lignin;

[0056] Optionally, in step 5, drying the wet cellulose obtained in step 4 to obtain cellulose;

[0057] Step 6, combining the lignin-containing liquid phase obtained in step 3 and the lignin-containing water washing liquid obtained in step 4, and then performing acid treatment to precipitate the lignin, and then heating and solid-liquid separation to obtain a lignin wet material, wherein the liquid phase is wastewater;

[0058] Optionally, in step seven, the wet lignin material obtained in step six is ​​dried to obtain lignin.

[0059] The endpoints and any values ​​of the scope disclosed in the present invention are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, the endpoint values ​​of each scope, the endpoint values ​​of each scope and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be regarded as specifically disclosed in this article.

[0060] Compared with the prior art, the present invention has the following advantages:

[0061] The present invention utilizes lignocellulose raw materials to co-produce cellulose, xylose and lignin, thereby achieving the separation of various components in lignocellulose, creating conditions for high value-added utilization of various components, being beneficial to ensuring food security, being beneficial to achieving green and low-carbon development, and having good social and environmental benefits.

[0062] The separation method of the invention uses fewer types of chemical reagents, has a simple process and has better separation effect. DETAILED DESCRIPTION

[0063] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0064] It should also be noted that the various specific technical features described in the following specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0065] In addition, the various embodiments of the present invention may be arbitrarily combined as long as they do not violate the concept of the present invention. The technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0066] The raw materials used in the examples and comparative examples, unless otherwise specified, are disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0067] In the present invention, the solid-liquid ratio refers to the mass ratio of solid to liquid.

[0068] Example 1

[0069] This embodiment provides a method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials, comprising the following steps:

[0070] Step 1, using corn stalks as raw materials, crushing and removing impurities from the corn stalks, acid impregnating, removing the acid impregnation liquid, and then pretreating the corn stalk raw materials by steam explosion. Specifically, the corn stalk raw materials are impregnated with 2.5wt% dilute sulfuric acid, the acid impregnation time is 10 minutes, and the acid impregnation temperature is 50°C; after acid impregnation, the acid liquid is removed by centrifugation, and then the pretreated material is treated at a temperature of 160°C and a pressure of 0.6MPaG for 30 minutes to obtain a pretreated material, in which the hemicellulose is hydrolyzed to obtain xylose.

[0071] Step 2: Wash the pretreated material with water at a solid-liquid ratio of 1:7 for 3 times, and then use plate and frame filter press to separate the solid and liquid to obtain a liquid phase containing xylose and a solid material containing cellulose and lignin; dry the liquid phase containing xylose to obtain xylose.

[0072] Step three, adding the solid material containing cellulose and lignin to an alkali solution for alkali treatment, the alkali treatment adopts sodium hydroxide solution treatment, the amount of sodium hydroxide added is 13% (g / g) of the dry matter weight of the solid material, the dry matter concentration of the solid material containing cellulose and lignin in the alkali solution is 9% (g / g), the alkali treatment temperature is 65°C, the alkali treatment time is 2h, the lignin therein is dissolved, and then centrifugation is used for solid-liquid separation to obtain a liquid phase containing lignin and a solid material containing cellulose.

[0073] Step 4: Wash the solid material containing cellulose with water at a solid-liquid ratio of 1:8 for 4 times, and then separate the solid and liquid by centrifugation to obtain a wet cellulose material and a washing liquid containing lignin.

[0074] Step 5: Tube drying the wet cellulose material obtained in step 4 to obtain cellulose.

[0075] Step 6: Combine the lignin-containing liquid phase obtained in step 3 and the lignin-containing water washing liquid obtained in step 4, and then perform acid treatment. The acid treatment uses a sulfuric acid solution (50wt%), and the amount of sulfuric acid added is 1.3 times the mass of sodium hydroxide added in step 3. The acid treatment temperature is 30°C and the time is 1h, so that the lignin precipitates, and then heats to 85°C and maintains for 1h, so that the precipitated lignin aggregates into large particles, and then vacuum belt filtration is used for solid-liquid separation to obtain a lignin wet material.

[0076] Step seven, performing air flow drying on the wet lignin material obtained in step six to obtain lignin.

[0077] Example 2

[0078] This embodiment provides a method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials, comprising the following steps:

[0079] Step 1, using wheat straw as raw material, crushing and removing impurities from the wheat straw, acid impregnating, removing the acid impregnation liquid, and then pretreating the wheat straw raw material by steam explosion. Specifically, the wheat straw raw material is impregnated with 2wt% dilute sulfuric acid, the acid impregnation time is 20 minutes, and the acid impregnation temperature is 10°C; after acid impregnation, the acid liquid is removed by centrifugation, and then the pretreated material is treated at a temperature of 170°C and a pressure of 0.7MPaG for 25 minutes to obtain a pretreated material, in which the hemicellulose is hydrolyzed to obtain xylose.

[0080] Step 2: Wash the pretreated material with water at a solid-liquid ratio of 1:8, and wash twice, then use plate and frame filter press to separate the solid and liquid to obtain a liquid phase containing xylose and a solid material containing cellulose and lignin; dry the liquid phase containing xylose to obtain xylose.

[0081] Step three, adding the solid material containing cellulose and lignin to an alkali solution for alkali treatment, wherein sodium hydroxide is used for alkali treatment, and the amount of sodium hydroxide added is 11% (g / g) of the dry matter weight of the solid material. In the alkali solution, the dry matter concentration of the solid material containing cellulose and lignin is 12%, the alkali treatment temperature is 75° C., and the alkali treatment time is 3 hours to dissolve the lignin therein, and then centrifugation is used for solid-liquid separation to obtain a liquid phase containing lignin and a solid material containing cellulose.

[0082] Step 4: Wash the solid material containing cellulose with water at a solid-liquid ratio of 1:9 for 3 times, and then separate the solid and liquid by centrifugation to obtain a wet cellulose material and a washing liquid containing lignin.

[0083] Step 5: Tube drying the wet cellulose material obtained in step 4 to obtain cellulose.

[0084] Step 6: Combine the lignin-containing liquid phase obtained in step 3 and the lignin-containing water washing liquid obtained in step 4, and then perform acid treatment. The acid treatment uses a sulfuric acid solution (50wt%), and the amount of sulfuric acid added is 1.3 times the mass of sodium hydroxide added in step 3. The acid treatment temperature is 30°C and the time is 1h, so that the lignin precipitates, and then heats to 85°C and maintains for 1h, so that the precipitated lignin aggregates into large particles, and then vacuum belt filtration is used for solid-liquid separation to obtain a lignin wet material.

[0085] Step seven, performing air flow drying on the wet lignin material obtained in step six to obtain lignin.

[0086] Example 3

[0087] This embodiment provides a method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials, comprising the following steps:

[0088] Step 1, using rice straw as raw material, crushing and removing impurities from the rice straw, acid-impregnating, removing the acid-impregnating liquid, and then pre-treating the rice straw raw material by steam explosion. Specifically, the rice straw raw material is impregnated with 3.5wt% dilute sulfuric acid, the acid-impregnating time is 2 minutes, and the acid-impregnating temperature is 90°C; after acid-impregnation, the acid liquid is removed by centrifugation, and then the pre-treated material is treated at a temperature of 190°C and a pressure of 1.0MPaG for 20 minutes to obtain a pre-treated material, in which the hemicellulose is hydrolyzed to obtain xylose.

[0089] Step 2: Wash the pretreated material with water at a solid-liquid ratio of 1:9 for 10 times, and then use plate and frame filter press to separate the solid and liquid to obtain a liquid phase containing xylose and a solid material containing cellulose and lignin; dry the liquid phase containing xylose to obtain xylose.

[0090] Step three, adding the solid material containing cellulose and lignin to an alkali solution for alkali treatment, wherein sodium hydroxide is used for alkali treatment, and the amount of sodium hydroxide added is 14% (g / g) of the dry matter weight of the solid material. In the alkali solution, the dry matter concentration of the solid material containing cellulose and lignin is 15%, the alkali treatment temperature is 80°C, and the alkali treatment time is 4 hours to dissolve the lignin therein, and then centrifugation is used for solid-liquid separation to obtain a liquid phase containing lignin and a solid material containing cellulose.

[0091] Step 4: Wash the solid material containing cellulose with water at a solid-liquid ratio of 1:8 for 5 times, and then separate the solid and liquid by centrifugation to obtain a wet cellulose material and a washing liquid containing lignin.

[0092] Step 5: Tube drying the wet cellulose material obtained in step 4 to obtain cellulose.

[0093] Step 6: Combine the lignin-containing liquid phase obtained in step 3 and the lignin-containing water washing liquid obtained in step 4, and then perform acid treatment. The acid treatment uses a sulfuric acid solution (50wt%), and the amount of sulfuric acid added is 1.1 times the amount of sodium hydroxide added in step 3. The temperature of the acid treatment is 40°C and the time is 1.5h, so that the lignin precipitates, and then heats to 80°C and maintains for 1.5h, so that the precipitated lignin aggregates into large particles, and then vacuum belt filtration is used for solid-liquid separation to obtain a lignin wet material.

[0094] Step seven, performing air flow drying on the wet lignin material obtained in step six to obtain lignin.

[0095] The yield and purity of cellulose, xylose and lignin co-produced using lignocellulose raw materials in the above examples are shown in Table 1.

[0096] Table 1

[0097]

[0098] It can be seen from the above results that the method of the present invention for co-producing cellulose, xylose and lignin using lignocellulose raw materials has high yield and purity of the co-produced cellulose, xylose and lignin through the coordination of various processes.

[0099] Comparative Example 1

[0100] The method is basically the same as that in Example 1, except that there are no steps 3 to 7 in step 1 of comparative example 1. As a result, only xylose can be obtained, but cellulose and lignin products cannot be obtained, and cellulose and lignin are mixed together.

[0101] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

[0102] All publications, patent applications, patents and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In the event of a conflict, the definition in this specification shall prevail.

[0103] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0104] In the context of the present specification, any matters or items not mentioned are directly applicable to those known in the art without any changes except those explicitly stated.

Claims

1. A method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials, characterized in that: The following steps are involved: Step 1, crushing and removing impurities from the lignocellulose raw material, acid impregnating, removing the acid impregnation liquid and then treating with steam explosion to obtain a pretreated material; Step 2, washing the pretreated material with water, and then performing solid-liquid separation to obtain a liquid phase 1 containing xylose and a solid material 1 containing cellulose and lignin; Step 3, adding the solid material 1 into an alkali solution for alkali treatment, and then separating the solid and the liquid to obtain a liquid phase 2 and a solid material 2 containing cellulose; Optionally, in step 4, the solid material 2 is washed with water, and then the solid and liquid are separated to obtain a cellulose wet material and a liquid phase 3; Optionally, in step five, drying the wet cellulose material to obtain cellulose; Step 6, after combining the liquid phase 2 and the optional liquid phase 3, adding acid for acid treatment, solid-liquid separation, to obtain lignin wet material and waste liquid; Optionally, in step seven, the wet lignin material is dried to obtain lignin.

2. The method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials according to claim 1, characterized in that: The lignocellulose raw material is selected from at least one of corn straw, corn cob, rice straw, wheat straw, reed and bean straw.

3. The method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials according to claim 1, characterized in that: In step one, The acid impregnation solution is a sulfuric acid solution, preferably the concentration of the sulfuric acid solution is 0.5wt% to 4wt%; and / or, The acid immersion time is 2 to 20 minutes; and / or, The acid impregnation temperature is 10 to 90°C; and / or, After the acid pickling solution is removed, the acid pickling solution is recovered and used for the next acid pickling treatment; The temperature of steam explosion treatment is 120℃~230℃; The pressure of steam explosion treatment is 0.3MPaG~1.5MPaG; The steam explosion treatment time is 20 minutes to 60 minutes.

4. The method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials according to claim 1, characterized in that: In step 2 and step 4, the solid-liquid ratio during water washing is independently selected from 1:5 to 1:10, and the number of water washings is independently 2 to 10 times.

5. The method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials according to claim 1, characterized in that: In step 2, step 3, step 4 and step 6, the solid-liquid separation method is independently selected from at least one of plate and frame filtration, centrifugal separation, screw extrusion dehydration and vacuum belt filtration.

6. The method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials according to claim 1, characterized in that: In step 3, the alkali solution is an aqueous solution of an inorganic strong base, more preferably an aqueous solution of at least one alkali selected from sodium hydroxide, potassium hydroxide, and calcium hydroxide; In the alkali solution, the dry matter concentration of the solid material 1 is 5 to 15% (g / g); and / or, The amount of alkali added is 5% to 20% of the dry matter in the solid material; and / or, The temperature of the alkali treatment is 20°C to 80°C; and / or, The alkali treatment time is 1h to 4h.

7. The method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials according to claim 1, characterized in that: In step 5 and step 7, the drying methods are independently selected from at least one of tube bundle drying, rotary drying, drum drying, and air flow drying.

8. The method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials according to claim 1, characterized in that: In step 6, the acid used in the acid treatment is selected from inorganic strong acids, preferably at least one selected from sulfuric acid, hydrochloric acid, phosphoric acid, and nitric acid; The amount of acid added is 1 to 1.5 times the amount of alkali added in the alkali treatment in step 3; and / or, The temperature of the acid treatment is 20 to 50°C; and / or, The acid treatment time is 0.5 to 2 hours.

9. The method for co-producing cellulose, xylose and lignin from lignocellulosic raw materials according to claim 1, characterized in that: Step six, after the acid treatment, heating, and then solid-liquid separation; preferably, the heating temperature is 70-90° C., and the heating time is 0.5-2 h.

10. Use of the method according to any one of claims 1 to 9 in straw resource recovery.

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