Preparation method of various high-valued bio-based products based on lignocellulose

Abstract

The invention relates to the technical field of plant extraction, in particular to a method for preparing various high-valued bio-based products based on lignocellulose. The method comprises the following steps: sequentially extracting a lignocellulose raw material by using a weak base extracting solution and a strong base extracting solution to obtain alkali lignin and a strong base extracted dealkalized suspension; separating the strong alkali extracted dealkalized suspension to obtain a dispersion liquid containing an arabinoxylan-lignin compound and water-insoluble arabinoxylan; adding organic acid into the arabinoxylan-lignin compound dispersion liquid, heating, hydrolyzing and then carrying out enzymolysis; and separating the enzymatic hydrolysate to prepare lignin, xylooligosaccharide, xylose and arabinose. According to the method, weak acid is used for assisting hydrolysis to destroy the structure of the arabinoxylan-lignin compound, so that the enzymolysis efficiency can be improved, the enzyme dosage can be reduced, the reaction activity of lignin components is protected, and the preparation of various high-valued bio-based products is realized.

Description

Technical Field

[0001] This invention relates to the field of plant extraction technology, and more specifically, to a method for preparing various high-value bio-based products based on lignocellulose. Background Technology

[0002] Lignocellulose is composed of three main components: lignin, hemicellulose, and cellulose. Lignin is an amorphous polymer of phenylpropane units cross-linked by carbon-carbon and ether bonds. Hemicellulose, a product of the Poaceae family, has arabinoxylan as the main chain and arabinose and glucuronic acid as branches. Cellulose is a linear dextran linked by β-1,4-glycosidic bonds. The three components are intertwined by ester bonds, anisole bonds, and phenyl glycosidic bonds, forming a recalcitrant structure. The unique chemical properties of these three components have broad application prospects in adhesives, new energy carbon materials, dietary fiber, pharmaceutical excipients, and bio-fermentation. However, due to separation and conversion costs and technological limitations, current applications are mainly limited to single-product routes such as cooking and pulping—black liquor lignin and pulp cellulose. The application of black liquor lignin is limited because it is degraded into complex small molecules by strong alkali and high temperature. The development of high-value products such as high-purity lignin, arabinoxylan, and xylooligosaccharides is insufficient.

[0003] Existing separation technologies—enzymatic, acidic, and alkaline methods—all have significant drawbacks: enzymatic methods are inefficient due to poor substrate accessibility; acidic methods produce large amounts of difficult-to-purify small-molecule degradation products, and the active groups of lignin are easily deactivated by condensation; traditional high-temperature, high-pressure NaOH pulping can dissolve lignin and hemicellulose, but both are deeply degraded into complex small molecules with low recovery value. Lowering the cooking intensity leads to the copolymerization of hemicellulose and lignin, making separation difficult and resulting in low product recovery rates. Therefore, a method is proposed that first, easily soluble lignin is dissolved under lower cooking conditions, preserving its reactivity and reducing the difficulty of subsequent separation of arabinoxylan (hemicellulose) from lignin, followed by extraction and separation to obtain arabinoxylan. However, during the extraction process, some arabinoxylan still forms complexes (aggregates) with lignin. After separating the water-insoluble arabinoxylan, these complexes have low application value due to insufficient purity. Although arabinoxylan can be directly degraded into xylooligosaccharides using xylanase and lignin products can be recovered, the enzyme dosage is relatively high and the production cost increases because xylanase is blocked by lignin and the efficiency of degradation of large arabinoxylan molecules by endonucleases is affected.

[0004] Controlling the conditions for weak acid and hydrothermal degradation of arabinoxylan disrupts the intermolecular forces of the complex, reduces the degree of polymerization of arabinoxylan, and fully exposes the sugar chain structure, which greatly improves the enzymatic hydrolysis efficiency of xylanase preparations and reduces production costs. Although weak acid and hydrothermal reactions can lead to condensation and degradation of lignin, the relatively weak reaction conditions have limited impact. The separation of higher-purity lignin after removing arabinoxylan still has application value. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a variety of high-value bio-based products based on lignocellulose.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: This invention provides a method for preparing various high-value bio-based products based on lignocellulose. The method involves sequentially extracting and separating lignocellulose raw materials using a weak alkali extract and a strong alkali extract to obtain alkali lignin and a strong alkali-extracted dealkali-suspended suspension. The strong alkali-extracted dealkali-suspended suspension is then separated to obtain an arabinoxylan-lignin complex dispersion and arabinoxylan. An organic acid is added to the arabinoxylan-lignin complex dispersion, followed by hydrolysis at elevated temperature and then enzymatic hydrolysis. The enzymatic hydrolysis products are then separated and purified to obtain lignin, xylooligosaccharides, xylose, and arabinose.

[0007] Furthermore, the organic acid is one or a combination of acetic acid, citric acid, malic acid, propionic acid, and formic acid; when the concentration of the organic acid in the arabinoxylan-lignin complex dispersion reaches 50-500 mM, hydrolysis is then carried out by heating.

[0008] Furthermore, the hydrolysis temperature is 120-200℃, the hydrolysis time is 20-90 min, and after the hydrolysis is completed, the solution is cooled to 55-65℃.

[0009] Furthermore, the enzyme used in the enzymatic hydrolysis is xylanase.

[0010] Furthermore, before enzymatic hydrolysis, the pH of the hydrolysate of the arabinoxylan-lignin complex is adjusted to 4.5-5.5; the amount of xylanase added is 2-100 U / g arabinoxylan; the enzymatic hydrolysis temperature is 60℃; and the time is 8-36 h.

[0011] Furthermore, the step of preparing the enzymatic hydrolysis products into lignin, xylooligosaccharides, xylose, and arabinose is as follows: The enzymatic hydrolysis product is filtered and the precipitate is washed. The precipitate after washing is lignin. The filtrate and washing solution are combined to obtain xylooligosaccharide solution. The xylooligosaccharide solution is then separated and purified to prepare xylooligosaccharide, xylose and arabinose.

[0012] Furthermore, the post-processing involves decolorizing and desalting the xylooligosaccharide solution, followed by chromatographic separation to obtain xylooligosaccharides, xylose, and arabinose, wherein the degree of polymerization of the xylooligosaccharides is 2-9 xylose units.

[0013] Furthermore, the step of separating the lignocellulose strong alkali extraction and dealkali removal suspension into an arabinoxylan-lignin complex dispersion and arabinoxylan is as follows: The strong alkali extraction and dealkali removal suspension is filtered using a fibrous material. Pressure is applied to the upper part of the fibrous material at 0.1-0.5 mPa to obtain a filter layer. The filter layer is washed with water, and the filtrate and washing liquid are combined to obtain the arabinoxylan-lignin complex dispersion. The solids in the filter layer are separated to obtain the arabinoxylan. The thickness of the filter layer is 3-8 cm.

[0014] Furthermore, the step of sequentially extracting the lignocellulose raw material with a weak alkali extract and a strong alkali extract to obtain alkali lignin and a strong alkali-extracted dealkali suspension is as follows: The lignocellulose raw material is mixed with the weak alkali extract and heated for extraction to obtain a first solid phase and a first liquid phase. The first liquid phase, after weak alkali recovery, is subjected to a first acid addition to adjust the pH, and a precipitate is obtained and prepared as the alkali lignin. The first solid phase is mixed with the strong alkali extract and heated for cooking to obtain a second solid phase and a second liquid phase. The second liquid phase is subjected to strong alkali recovery and a second acid addition to adjust the pH to obtain the strong alkali extract dealkali suspension. The weak alkaline extract of the raw material is a Na2CO3 solution with a mass percentage of 5-8%, and the strong alkaline extract of the raw material is a sodium hydroxide solution with a mass percentage of 4%-8%. The heating temperature is 70-100℃, and the extraction time is 80-120 min. The heating and cooking temperature is 80-90℃, and the extraction time is 70-90 min.

[0015] Furthermore, during the recovery of the weak alkali, the recovery is completed when the mass percentage of the weak alkali is 0.1-2%. During the recovery of the strong alkali, the recovery is completed when the mass percentage of the strong alkali is 0.5-2.5%. When adding acid for the first time to adjust the pH, the pH value is adjusted to 2-4. When adding acid for the second time to adjust the pH, the pH value is adjusted to 7-12.

[0016] The beneficial effects of this invention are as follows: (1) The preparation method of various high-value bio-based products based on lignocellulose of the present invention first uses a weak alkaline extract and then uses a strong alkaline extract. It makes full use of the degradation performance of the weak alkaline extract and the strong alkaline extract on the three-component chemical bonds in the raw material lignocellulose, and the difference in the solubility performance of lignin and arabinoxylan, to achieve the two-step preparation of alkali lignin and arabinoxylan. (2) The preparation method of various high-value bio-based products based on lignocellulose of the present invention, based on the two-step extraction process of weak alkali-strong alkali, performs organic acid-assisted hydrolysis and enzymatic hydrolysis on the obtained arabinoxylan-lignin complex dispersion so that it can be further prepared into lignin, xylooligosaccharide, xylose and arabinose, thereby realizing the reuse of arabinoxylan-lignin complex. (3) The preparation method of various high-value bio-based products based on lignocellulose of the present invention adds organic acid to assist hydrolysis, without increasing the external elements of the reaction system, and reduces the burden of subsequent purification.

[0017] (4) The preparation method of various high-value bio-based products based on lignocellulose in this invention, by adding organic acid to assist hydrolysis, can effectively destroy the weak non-covalent interactions of the arabinoxylan-lignin complex, reduce the degree of polymerization of arabinoxylan, improve the accessibility of the enzyme preparation to the substrate, reduce the amount of enzyme used, and improve the enzymatic hydrolysis efficiency. During the hydrolysis process, the organic acid hydrolysis conditions are mild, which can simultaneously take into account the reactivity of lignin, prevent lignin from being excessively condensed and degraded, reduce the destruction of active sites, and protect the application value of lignin; (5) The preparation method of various high-value bio-based products based on lignocellulose of the present invention has mild enzymatic hydrolysis conditions and subsequent separation treatment conditions, which reduces the impact on the chemical properties of each component during the separation process and improves the application of each component in downstream products; (6) The method for preparing various high-value bio-based products based on lignocellulose of the present invention uses thicker filamentous fiber material as filter material, which does not require complete solution circulation, but only needs to maintain the pressure of the cleaning liquid, thus saving power and energy and achieving high cleaning efficiency. (7) The method for preparing various high-value bio-based products based on lignocellulose of the present invention can obtain lignin, xylooligosaccharides, xylose and arabinose while preparing alkali lignin and arabinoxylan, providing a feasible path for large-scale, low-cost separation of lignocellulose and high-value utilization of its components. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the steps of treating the lignocellulose strong alkali extraction and dealkali removal suspension in the preparation method of various high-value bio-based products based on lignocellulose of the present invention. Figure 2 This is a complete flowchart of the preparation method of various high-value bio-based products based on lignocellulose according to the present invention. Detailed Implementation

[0019] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0020] like Figure 1-2 As shown, the method for preparing various high-value bio-based products based on lignocellulose according to the present invention includes the following steps: extracting and separating lignocellulose raw materials sequentially using a weak alkali extract and a strong alkali extract, adjusting the pH to obtain alkali lignin and a strong alkali-extracted dealkali suspension; separating the strong alkali-extracted dealkali suspension into an arabinoxylan-lignin complex dispersion and arabinoxylan; adding acetic acid to the arabinoxylan-lignin complex dispersion, followed by hydrolysis and enzymatic hydrolysis; and preparing the enzymatic hydrolysis products into lignin, xylooligosaccharides, xylose, and arabinose.

[0021] This invention employs a weak alkaline extract followed by a strong alkaline extract. It fully utilizes the difference in degradation properties of the weak and strong alkaline extracts on the three-component chemical bonds in the raw material lignocellulose, and their difference in solubility for lignin and arabinoxylan, to achieve a two-step preparation of alkali-treated lignin and arabinoxylan. Traditional strong alkaline extraction processes simultaneously dissolve lignin and hemicellulose. Although the bonds are broken, arabinoxylan and lignin still form difficult-to-separate complex aggregates. Furthermore, strong alkalinity itself easily degrades both into scattered small molecules, resulting in decreased yields and difficulty in improving purity of lignin and arabinoxylan. The steps of this invention first extract easily soluble lignin with a mild weak alkaline solution, resulting in mild system conditions and minimal degradation. Then, the partially "delignified" residue is treated with a strong alkaline solution, extracting arabinoxylan and the less soluble portion of lignin. Because the proportion of lignin is reduced, the formation of arabinoxylan-lignin complexes is decreased, improving separation efficiency.

[0022] The resulting strong alkali-extracted dealkali suspension, after separating water-insoluble arabinoxylan, still contains various components such as the arabinoxylan-lignin complex and other degradation products of lignocellulose. This portion of the solution has low utilization value and may even become waste liquid polluting the environment. This invention first hydrolyzes and enzymatically hydrolyzes the arabinoxylan-lignin complex dispersion, then further separates and purifies the enzymatic hydrolysis products, ultimately obtaining lignin, xylooligosaccharides, xylose, and arabinose, achieving the simultaneous preparation of multiple products.

[0023] The specific steps of this invention are as follows: S1. Mix the raw material with the weak alkali extract at a solid-liquid mass-volume ratio of 1:5-12 and heat to extract, obtaining a first solid phase and a first liquid phase. Mix the first solid phase with the strong alkali extract at a solid-liquid mass-volume ratio of 1:5-12 and heat to cook, obtaining a second solid phase and a second liquid phase. Recover the strong alkali from the second liquid phase and adjust the pH with acid to obtain a strong alkali extract dealkali suspension.

[0024] Preferably, the weakly alkaline extract is a Na2CO3 solution with a mass percentage of 5-8%, the heating temperature is 70-100℃, and the extraction time is 80-120 min.

[0025] The strong alkaline extract is a sodium hydroxide solution with a mass percentage of 4%-8%, and the heating and cooking temperature is 80-90℃, with an extraction time of 70-90 min.

[0026] Preferably, for the first liquid phase, alkali lignin can be obtained by adjusting the pH value with acid, and the second solid phase is the cellulose product, which can be used for pulping or further saccharification, and then fermented by microorganisms to produce fuel ethanol, etc.

[0027] Preferably, the method for recovering strong alkali is to perform electrodialysis or membrane filtration on the second liquid phase, and the recovery is completed when the mass percentage of strong alkali in the second liquid phase is 0.5-1.0%.

[0028] Preferably, the method of adjusting pH by adding acid is to add hydrochloric acid to the second liquid phase after the strong alkali recovery is completed, and adjust the pH value to 7-12.

[0029] S2. The alkali-extracted and dealkalized suspension of lignocellulose is separated into an arabinoxylan-lignin complex dispersion and arabinoxylan.

[0030] Specifically, the separation can be achieved through centrifugation or filtration.

[0031] In a further preferred embodiment, the suspension is first washed with a weak alkaline solution or pure water, and then the suspension is washed by centrifugation. The light phase is a dispersion of arabinoxylan-lignin complex, and the heavy phase is the arabinoxylan.

[0032] In a further preferred embodiment, a strong alkali extraction and dealkali-removing suspension is filtered using fibrous materials to obtain a filter layer. Then, arabinoxylan is separated from the filter layer after water washing. The arabinoxylan precipitate particles can be intercepted in the tortuous channels formed in the fibrous filter material. The gaps and channels of different sizes formed by the filter material and precipitate particles during the filtration process, through continuous solvent washing, can fully clean and filter out components such as arabinoxylan-lignin complex and lignin, effectively reducing the residue of arabinoxylan-lignin complex and thus improving the product recovery rate.

[0033] Preferably, the thickness of the filter layer is 3-8 cm, and the fibrous material includes pulp, cotton, and chemical fiber. The filtration method is to apply pressure of 0.1-0.5 MPa to the upper part of the fibrous material.

[0034] The use of filamentous fiber materials and the aforementioned separation conditions offer significant advantages for large-scale industrial production. Because the method of this invention can yield a variety of products, large-scale production has greater industrial value in practical applications. Furthermore, the filamentous fiber filter media itself is inexpensive, can be repeatedly washed and reused, and only requires maintaining a certain level of hydraulic pressure or vacuum to propel the liquid through the curved flow channel; the power consumption is far lower than the enormous energy consumption required for the high-speed rotation of a centrifuge.

[0035] There are many materials that can be used as filter aids, but most of them are granular filter media. If the target product needs to be recovered, granular filter aids are difficult to separate. This invention selects filamentous fiber filter media, which cleverly solves the problems of the difficulty in settling the components in the suspension and the easy clogging of the filter layer by gel. The filamentous fiber filter layer has the advantages of high sample carrying capacity, high separation efficiency, low filtration power consumption, and easy separation, recycling and reuse of filter media.

[0036] S3. Add acetic acid to the arabinoxylan-lignin complex dispersion, and then carry out hydrolysis and enzymatic hydrolysis.

[0037] Preferably, acetic acid is added to make the acid concentration in the solution 50-500mM before hydrolysis is carried out; the hydrolysis temperature is 120-200℃, the hydrolysis time is 20-90min, and after the hydrolysis is completed, the solution is cooled to 55-65℃.

[0038] S4. Before enzymatic hydrolysis, adjust the pH of the arabinoxylan-lignin complex hydrolysate to 4.5-5.5, and then use xylanase to enzymatically hydrolyze the arabinoxylan-lignin complex hydrolysate to obtain the enzymatic hydrolysis product.

[0039] The amount of xylanase added is 2-100 U / g arabinoxylan, the enzymatic hydrolysis temperature is 60℃, and the time is 8-36h; the enzymatic hydrolysis conditions are mild, which is conducive to the subsequent efficient separation of multiple products.

[0040] S5. Filter the enzymatic hydrolysis product and wash the precipitate. The precipitate after washing is lignin. Combine the filtrate and the washing solution to obtain xylooligosaccharide solution. The xylooligosaccharide solution is then post-processed to prepare xylooligosaccharide, xylose and arabinose.

[0041] Preferably, the post-processing involves decolorizing and desalting the xylooligosaccharide solution, followed by chromatographic separation to obtain xylooligosaccharide, xylose, and arabinose, wherein the degree of polymerization of the xylooligosaccharide is 2-9 xylose units.

[0042] Preferably, decolorization is carried out using activated carbon, and desalination is carried out using anion and cation exchange resins. Both of these methods can keep the chemical properties of the product stable during decolorization and desalination, further improving the diversity and application value of the final product.

[0043] Preferably, the purified mixed sugar solution is first passed through a cation exchange resin column, then sequentially through an anion exchange resin column and an activated carbon decolorization column at a flow rate of 2-5 times the column volume to desalt and decolorize, thereby purifying the enzymatically hydrolyzed mixed sugar solution.

[0044] Preferably, the desalted and decolorized mixed sugar solution is concentrated to a concentration of 50%-60% to obtain a mixed syrup. The mixed syrup is then separated by a calcium-type chromatographic separation resin column. The chromatographic separation column can be a single column with fractional sample loading or a simulated moving bed with continuous sample loading. The chromatographic separation resin elutes sequentially due to the different adsorption forces of xylooligosaccharides, arabinose, and xylose components in the mixed syrup, and each component is separated by receiving different fractions. Finally, xylooligosaccharide, arabinose, and xylose products are obtained respectively.

[0045] The hydrolysis, enzymatic hydrolysis, and post-treatment methods of the present invention can effectively separate lignin, xylooligosaccharides, xylose, and arabinose, reduce the impact on the chemical properties of each component during the separation process, and improve the application of each component in downstream products. Compared with the prior art, the above-mentioned method of the present invention can take into account the reactivity of lignin during the preparation of xylooligosaccharides, prevent lignin from being condensed and degraded, and prevent a large number of active sites from being destroyed, thus ensuring the application value of lignin.

[0046] The present invention will be illustrated by specific embodiments below.

[0047] Example 1 like Figure 1 As shown, the method of the present invention is used to prepare arabinoxylan, and the specific steps are as follows: (1) Take 120kg of absolutely dry corn cob raw material, first crush the raw material into small particles, wash it with water to remove impurities such as salts, microorganisms and their metabolites, and then perform spiral extrusion.

[0048] (2) Add 7 times the amount of weak alkali extract to the raw material after the above treatment. The weak alkali extract is a 5% Na2CO3 solution. Heat to 90°C and extract for 80 min. Then process with a screw extruder to separate the solid and liquid phases to obtain the first solid phase and the first liquid phase.

[0049] (3) Na2CO3 in the first liquid phase is recovered by electrodialysis or nanofiltration and ultrafiltration membrane filtration; hydrochloric acid is added to the first liquid phase to adjust the pH value to 2-4, and a precipitate is obtained. The precipitate is separated and dried to obtain alkali lignin.

[0050] (4) Add 6 times the amount of NaOH solution to the first solid phase and stir until homogeneous. The final concentration of the NaOH solution is 8%. The heating temperature is 90℃ and the holding time is 70min. After extraction, centrifuge to separate the solid and liquid phases to obtain the second solid phase and the second liquid phase.

[0051] (5) After washing the second solid phase with water, solid-liquid separation is performed again. The washed second solid phase is cellulose. The liquid phase obtained from washing is combined with the second liquid phase, and NaOH in the second liquid phase is recovered using an alkali-resistant membrane device. Hydrochloric acid is added to the second liquid phase after removing NaOH to adjust the pH to 9. As the pH value decreases, precipitation occurs in the solution, forming a precipitate suspension, which is the strong alkali extraction and dealkali removal suspension.

[0052] (6) The strong alkali extraction and dealkali-removed suspension was separated into arabinoxylan-lignin complex dispersion and arabinoxylan.

[0053] In this embodiment, pulp material is used for filtration to obtain a filter layer. Arabicaxylan is then separated from the filter layer after washing with water. The filter layer is 8 cm thick and pressurized at 0.3 MPa. The filter layer is repeatedly washed with water to dissolve lignin until the effluent is light-colored or colorless. The combined effluents are then used to obtain an arabinoxylan-lignin complex dispersion. The filter layer is then further dispersed with pure water, and the solid phase is separated using a twin-screw dehydrator. After concentration and drying, the arabinoxylan product is obtained.

[0054] Acetic acid was added directly to the arabinoxylan-lignin complex dispersion until the acid concentration of the solution was 300 mM. The mixture was then heated to 180 °C in a reactor and reacted for 60 min, followed by cooling to 60 °C.

[0055] (7) Adjust the pH of the hydrolysate to 5.0 and enzymatically hydrolyze it at 60℃ for 10 h. The amount of enzyme added is 20 U / g arabinoxylan. After filtration, the material is washed with water to remove the precipitate. The precipitate is lignin. Combine the washing liquid phases to obtain a mixed sugar solution. The mixed sugar solution is decolorized by activated carbon and desalted by anion and cation exchange resins.

[0056] (3) Vacuum concentration of decolorized and desalted mixed sugar solution, or direct separation of xylose and arabinose by chromatographic separation method to obtain xylooligosaccharides with a degree of polymerization of 2-9 xylose units.

[0057] The results showed that the yield of xylooligosaccharides in this embodiment was 79.81%, the yield of xylose was 0.96%, and the yield of arabinose was 0.33%.

[0058] Comparative Example 1 This comparative example is the same as Example 1, except that the arabinoxylan-lignin complex suspension is directly enzymatically hydrolyzed.

[0059] The test results showed that the yield of xylooligosaccharides in this comparative sample was 53.54%, the yield of xylose was 0.42%, and the yield of arabinose was 0.21%.

[0060] Compared with Example 1, it can be seen that the yields of xylooligosaccharides and xylose obtained by direct enzymatic hydrolysis are both low.

[0061] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing various high-value bio-based products based on lignocellulose, characterized in that, Lignocellulose raw materials were extracted and separated sequentially using a weak alkali extract and a strong alkali extract to obtain alkali lignin and a strong alkali-extracted dealkali suspension. The strong alkali-extracted dealkali suspension was separated to obtain an arabinoxylan-lignin complex dispersion and arabinoxylan. An organic acid was added to the arabinoxylan-lignin complex dispersion, followed by hydrolysis at elevated temperature and then enzymatic hydrolysis. The enzymatic hydrolysis products were separated and purified to obtain lignin, xylooligosaccharides, xylose, and arabinose.

2. The method for preparing various high-value bio-based products based on lignocellulose according to claim 1, characterized in that, The organic acid is one or a combination of acetic acid, citric acid, malic acid, propionic acid, and formic acid; hydrolysis is carried out by heating after the concentration of the organic acid in the arabinoxylan-lignin complex dispersion reaches 50-500 mM.

3. The method for preparing various high-value bio-based products based on lignocellulose according to claim 1, characterized in that, The hydrolysis temperature is 120-200℃, the hydrolysis time is 20-90 min, and after the hydrolysis is completed, the solution is cooled to 55-65℃.

4. The method for preparing various high-value bio-based products based on lignocellulose according to claim 1, characterized in that, The enzyme used in the enzymatic hydrolysis is xylanase.

5. The method for preparing various high-value bio-based products based on lignocellulose according to claim 4, characterized in that, Before enzymatic hydrolysis, the pH of the hydrolysate of the arabinoxylan-lignin complex is adjusted to 4.5-5.5; the amount of xylanase added is 2-100 U / g arabinoxylan; the enzymatic hydrolysis temperature is 60℃; and the time is 8-36 h.

6. A method for preparing various high-value bio-based products based on lignocellulose according to any one of claims 1-5, characterized in that, The step of preparing lignin, xylooligosaccharides, xylose, and arabinose from the enzymatic hydrolysis products is as follows: The enzymatic hydrolysis product is filtered and the precipitate is washed. The precipitate after washing is lignin. The filtrate and washing solution are combined to obtain xylooligosaccharide solution. The xylooligosaccharide solution is then separated and purified to prepare xylooligosaccharide, xylose and arabinose.

7. The method for preparing various high-value bio-based products based on lignocellulose according to claim 6, characterized in that, The separation and purification process involves decolorizing and desalting the xylooligosaccharide solution, followed by chromatographic separation to obtain xylooligosaccharides, xylose, and arabinose, wherein the degree of polymerization of the xylooligosaccharides is 2-9 xylose units.

8. A method for preparing various high-value bio-based products based on lignocellulose according to any one of claims 1-5, characterized in that, The step of separating the lignocellulose strong alkali extraction and dealkalization suspension into an arabinoxylan-lignin complex dispersion and arabinoxylan is as follows: The strong alkali extraction and dealkali removal suspension is filtered using a fibrous material. Pressure is applied to the upper part of the fibrous material at 0.1-0.5 mPa to obtain a filter layer. The filter layer is washed with water, and the filtrate and washing liquid are combined to obtain the arabinoxylan-lignin complex dispersion. The solids in the filter layer are separated to obtain the arabinoxylan. The thickness of the filter layer is 3-8 cm.

9. A method for preparing various high-value bio-based products based on lignocellulose according to any one of claims 1-5, characterized in that, The steps of sequentially extracting lignocellulose raw materials with weak alkali extract and strong alkali extract to obtain alkali lignin and strong alkali-extracted dealkali suspension are as follows: The lignocellulose raw material is mixed with the weak alkali extract and heated for extraction to obtain a first solid phase and a first liquid phase. The first liquid phase, after weak alkali recovery, is subjected to a first acid addition to adjust the pH, and a precipitate is obtained and prepared as the alkali lignin. The first solid phase is mixed with the strong alkali extract and heated for cooking to obtain a second solid phase and a second liquid phase. The second liquid phase is subjected to strong alkali recovery and a second acid addition to adjust the pH to obtain the strong alkali extract dealkali suspension. The weak alkaline extract is a Na2CO3 solution with a mass percentage of 5-8%, and the strong alkaline extract is a sodium hydroxide solution with a mass percentage of 4%-8%. The heating temperature is 70-100℃, and the extraction time is 80-120 min. The heating and cooking temperature is 80-90℃, and the extraction time is 70-90 min.

10. A method for preparing various high-value bio-based products based on lignocellulose according to claim 9, characterized in that, During the recovery of the weak alkali, the recovery is completed when the mass percentage of the weak alkali is 0.1-2%. During the recovery of the strong alkali, the recovery is completed when the mass percentage of the strong alkali is 0.5-2.5%. When adding acid for the first time to adjust the pH, the pH value is adjusted to 2-4. When adding acid for the second time to adjust the pH, the pH value is adjusted to 7-12.

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