Method for separating lignocellulose components through densification pretreatment of acidic organic solution

Abstract

The invention discloses a method for separating lignocellulose components through densification pretreatment of an acidic organic solution. The method comprises the following steps: firstly, infiltrating a lignocellulose raw material in an acidic organic solution, and then carrying out densification treatment to obtain a homogeneous densified raw material; stacking the densified raw materials at room temperature for a period of time to complete component disassembly and solvation lignin reaction; finally, holocellulose residues and light-color solvated lignin products are obtained through component extraction. According to the method, pretreatment component separation of lignocellulose biomass at the room temperature is achieved, the enzymolysis rate of holocellulose residues exceeds 90%, and light-color solvated lignin can be used as a sunscreen additive. The method has the advantages of low energy consumption, low cost and high efficiency, and is suitable for large-scale industrial application.

Description

Technical Field:

[0001] The present invention relates to the technical field of biomass energy conversion and utilization, and particularly to a method for separating lignocellulose components by densification pretreatment with an acidic organic solution. Background Art:

[0002] Pretreatment component separation is the basis for the efficient biorefining of lignocellulosic agricultural and forestry waste, aiming to purposefully separate cellulose, hemicellulose, and lignin components for fuel and chemical production. Although existing technologies (such as acid / alkali methods, steam explosion, deep eutectic solvent methods, etc.) can improve the component conversion efficiency, they generally have problems such as high energy consumption, difficult solvent recycling, and many inhibitors. Moreover, the storage problems caused by the loose nature of the raw materials and seasonal supply further restrict economic feasibility. Therefore, it is crucial to develop a pretreatment technology with the following characteristics: (1) high density of raw materials for processing and storage; (2) operation at normal temperature and pressure; (3) low liquid-solid ratio and reagent consumption; (4) direct conversion without washing residues; (5) high-value utilization of lignin; (6) avoidance of pretreatment liquid recovery and regeneration, etc.

[0003] Chemical densification technology destroys the lignocellulose structure by introducing reagents such as acids / alkalis / oxidants, simultaneously improving the density and processability of raw materials. Patent CN107475326A discloses a method suitable for the long-term storage of lignocellulose raw materials. Through dry dilute acid pretreatment, the bulk density of lignocellulose raw materials is increased, facilitating transportation and storage, and at the same time inhibiting the invasion of miscellaneous bacteria and microorganisms during storage. Patent CN112111540A discloses a method for pretreatment and biological conversion by adding an acidic reagent during the densification of lignocellulose raw materials. An acidic reagent is added during the densification process to destroy the lignocellulose structure and improve the enzymatic hydrolysis efficiency. Patent CN117265039A discloses a pretreatment and biological conversion method for densifying lignocellulose raw materials and Fenton's reagent together. The lignocellulose raw materials and Fenton's reagent are densified together, significantly reducing the usage amount of Fenton's reagent, increasing the bulk density of raw materials, destroying the lignocellulose structure, and improving the enzymatic hydrolysis sugar conversion efficiency and biological fermentation effect. Patent CN116590352A discloses a method for densifying lignocellulose raw materials, inorganic salts, and acidic reagents together. The lignocellulose raw materials, inorganic salts, and acidic reagents are densified into densified biomass, which can prevent raw material mildew during transportation and storage and effectively reduce the severity of reprocessing. Although the above chemical densification pretreatment technologies can effectively destroy the lignocellulose structure and achieve effective enzymatic hydrolysis and saccharification of raw materials, during the pretreatment process, the high concentration of acid solution corrodes equipment and is prone to generating inhibitors, the solution spraying method is not conducive to the uniform mixing of reagents and raw materials, the reagent consumption is large, and the separation and conversion of lignin components are ignored, etc., which still need to be optimized. Summary of the Invention:

[0004] The present invention solves the problems existing in the prior art and provides a method for separating lignocellulose components by densification pretreatment with an acidic organic solution, so as to effectively disassemble, separate and utilize the components of lignocellulose agricultural and forestry waste.

[0005] The object of the present invention is to provide a method for separating lignocellulose components by densification pretreatment with an acidic organic solution, comprising the following steps:

[0006] (1) Infiltration and densification: Immerse the lignocellulose raw material in the acidic organic solution. After the reagents in the acidic organic solution penetrate into the interior of the raw material, through the densification method, a densified lignocellulose raw material with homogeneous mixing of the reagents and the raw material and a recyclable press filtrate are obtained. The acidic organic solution is prepared by mixing an acidic catalyst and an organic solution. The organic solution is a homogeneous solution composed of a first lignin-solubilizing organic solvent, a co-solvent and water. The volume content of the lignin-solubilizing organic solvent in the organic solution is not less than 1%, the volume content of the co-solvent is not more than 40%, and the volume content of water is not less than 20%;

[0007] (2) Stacking treatment: Stack the densified lignocellulose raw material for a period of time to obtain a stacked densified raw material;

[0008] (3) Component extraction: Add the stacked densified raw material to the second lignin-solubilizing organic solvent for reaction, and perform solid-liquid separation to obtain holocellulose residue and an extraction reaction solution. Add an anti-solvent to the extraction reaction solution and perform solid-liquid separation to obtain a solvated lignin product and a recyclable filtration extraction solution;

[0009] (4) Conversion and utilization: Perform bioconversion and utilization on the stacked densified raw material and / or the holocellulose residue.

[0010] The present invention first immerses the raw material in the acidic organic solution to allow the reagents to fully penetrate into the internal structure of the raw material, and then through the densification method, a densified lignocellulose raw material with homogeneous mixing of the reagents and the raw material and a recyclable press filtrate are obtained; Subsequently, the densified lignocellulose raw material is stacked at room temperature for a period of time to effectively disassemble the components, realize the reaction of solvated components, and obtain a stacked densified raw material that can be directly enzymatically hydrolyzed; Finally, the disassembled components of the stacked densified raw material are extracted and separated to obtain holocellulose residue and solvated lignin, so as to complete the entire pretreatment component separation process.

[0011] The pretreatment component separation method proposed in the present invention cleverly utilizes the solvent effect of the organic solution. During the infiltration process, the solution is promoted to swell the raw material so that the reagent can penetrate deeply into the raw material. In the stacking stage, the acid catalysis is strengthened, the chemical bond breaking between the raw material components is accelerated, and the effective disassembly of the components is achieved. Combined with the good lignin solubility of the solution, efficient stripping of the disassembled lignin components is achieved. At the same time, the organic solvent and lignin undergo a solvation reaction, and the solvent is grafted into the lignin structure, which effectively inhibits the re-condensation of lignin and improves the anti-ultraviolet activity of lignin. After extraction and separation, a light-colored solvated lignin product can be obtained. In addition, the organic solution that dissolves lignin is usually difficult to dissolve sugar, which effectively inhibits the stripping of the disassembled hemicellulose, improves the limited retention of hemicellulose under acid pretreatment conditions, and overall increases the content of holocellulose (cellulose and hemicellulose) in the raw material, thereby improving the utilization efficiency of carbohydrates in the raw material.

[0012] The pretreatment stacking process proposed in the present invention is mild and does not produce obvious inhibitors. Therefore, the stacked densified raw materials do not need to be washed or detoxified and can be directly enzymatically hydrolyzed and utilized. By extracting and separating the stacked densified raw materials to disassemble the components, the enzymatic hydrolysis efficiency of the palm cellulose residue can be further improved to obtain a high-concentration sugar solution, and the solvated lignin product can be effectively recovered to achieve overall efficient utilization of raw material resources.

[0013] Preferably, the raw material used in the present invention has a particle size of no more than 5 mm and contains at least cellulose or hemicellulose components, including but not limited to pennisetum, miscanthus, wood chips, straw, bagasse, bamboo chips, furfural residues, agricultural and forestry wastes, and processing wastes of the above substances.

[0014] Preferably, the mass volume ratio of the acidic catalyst to the organic solution in the acidic organic solution of step (1) is less than or equal to 0.05 g / mL, and the acidic catalyst is selected from one or more of inorganic acids, organic acids, and strong acid weak base salts soluble in organic solutions. The acidic catalyst is one or more of acidic reagents such as inorganic acids, organic acids, or strong acid weak base salts soluble in organic solutions. Further preferably, the mass volume ratio of the acidic catalyst to the organic solution in the acidic organic solution of step (1) is less than or equal to 0.02 g / mL.

[0015] In step (1), the purpose of infiltration is to allow the reagent to effectively infiltrate the raw material. The amount of organic solution used is limited to the minimum volume of the raw material that can be immersed. The immersion time is not less than 30 minutes, and stirring, ultrasound, heating and other methods can be used to enhance mass transfer to improve the infiltration effect.

[0016] The densification process refers to the method of extruding the solution contained in the infiltrated raw material through pressure filtration, extrusion, granulation, briquetting or a combination thereof, so as to increase the density and uniformity of the pretreated raw material, and obtain a densified lignocellulosic raw material with homogeneous mixing of reagents and raw materials and recyclable press filtrate; the volume mass ratio of the organic solution to the raw material in the densified lignocellulosic raw material does not exceed 3.0 mL / g; the press filtrate is an acidic organic solution extruded and recovered during the densification process, which can be recycled for the infiltration process to effectively reduce the solution consumption.

[0017] Preferably, the dosage of the acidic catalyst does not exceed 0.10 grams per gram of raw material. Further preferably, the dosage of the acidic catalyst does not exceed 0.05 grams per gram of raw material.

[0018] Preferably, the first lignin-dissolving organic solvent in step (1) is selected from one or more of triethylene glycol, phenoxyethanol, glycerol formal, dihydrolevoglucosenone, tetrahydrofurfuryl alcohol and dimethyl isosorbide; the co-solvent is selected from one or more of ethanol, acetone, isobutanol, ethylene glycol, glycerol, triethylene glycol, phenoxyethanol, glycerol formal, dihydrolevoglucosenone, tetrahydrofurfuryl alcohol and dimethyl isosorbide.

[0019] The first lignin-dissolving organic solvent / second lignin-dissolving organic solvent is a non-volatile organic solvent with a boiling point usually greater than 100 °C, which can swell lignocellulose and dissolve lignin. The co-solvent refers to an organic solvent with a content less than that of the lignin-dissolving organic solvent in the organic solution and can strengthen the solvent effect during pretreatment, and can be one or more lignin-dissolving organic solvents.

[0020] Strengthening the solvent effect refers to the beneficial effects on pretreatment generated after adding the lignin-dissolving organic solvent and the co-solvent in the solution, including but not limited to strengthening the liquid-solid mass transfer between the solution and the raw material by reducing the solution viscosity, forming a homogeneous solution, etc.; the solvent grafting reaction occurs between the solvent and the raw material components to generate solvated components; adjusting the solubility parameter of the solution to improve the lignin-dissolving performance of the solution; enhancing the acid strength of the catalyst to promote the bond breaking and decomposition of components.

[0021] Further preferably, the volume ratio of the first lignin-dissolving organic solvent, co-solvent and water is (10 - 50):(0 - 30):(20 - 90).

[0022] Preferably, the stacking conditions in step (2) are: the stacking time is not less than 3 days, and the stacking temperature is not lower than 20 °C.

[0023] After being directly bioconverted and utilized or subjected to component extraction and then bioconverted and utilized, the stacked and densified raw materials proposed by the present invention. Direct bioconversion and utilization means that the residues of the stacked and densified lignocellulosic raw materials can be directly used as raw materials without reprocessing steps such as washing, detoxification, and heating, and chemicals and fuels can be prepared through biochemical conversion pathways, including but not limited to reducing sugars (such as glucose and xylose), ethanol, butanol, acetone, acetic acid, lactic acid, oils and fats, proteins, biogas, amino acids, etc.

[0024] The component extraction mentioned above refers to the process of separating holocellulose residues and solvated lignin by extracting lignin components from the stacked and densified raw materials with lignin-dissolving organic solvents. The reverse solvent is a solvent that is soluble in the lignin-dissolving organic solvent and difficult to dissolve lignin, including but not limited to water, dimethyl carbonate, isopropyl ether, dimethoxymethane, etc.

[0025] The solvated lignin refers to the lignin formed by the reaction of an organic solvent with lignin to generate a grafted solvent structure.

[0026] The filtered extraction solution can be recycled for use in the component extraction step, mixed with a second lignin-dissolving organic solvent for component extraction, or mixed with a reverse solvent for precipitation to separate lignin components.

[0027] Preferably, the second lignin-dissolving organic solvent in step (3) is selected from one or more of triethylene glycol, phenoxyethanol, glycerol formal, dihydrolevoglucosenone, tetrahydrofurfuryl alcohol, and dimethyl isosorbide; the reverse solvent is selected from one or more of water, dimethyl carbonate, isopropyl ether, and dimethoxymethane. The reaction temperature for component extraction does not exceed 50°C, and room temperature reaction is preferred.

[0028] Preferably, the mass ratio of the stacked and densified raw materials to the second lignin-dissolving organic solvent in step (3) is 1:4 - 6, and the volume ratio of the extraction reaction solution to the reverse solvent is 1:4 - 6.

[0029] Preferably, the bioconversion and utilization in step (4) is to prepare chemicals and / or fuels through biochemical conversion pathways, and the chemicals and / or fuels include but not limited to reducing sugars, ethanol, butanol, acetone, acetic acid, lactic acid, oils and fats, proteins, biogas, and amino acids.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] (1) The present invention adopts the method of first infiltrating with an organic solution and then homogenizing and densifying, realizing the effective homogeneous mixing of reagents and raw materials; in the stacking treatment stage, the solvent effect is strengthened, realizing the effective decomposition of raw material components and the solvation of the decomposed components at a low acid concentration; through the component extraction process, the raw material components are separated into holocellulose residues and solvated lignin products, effectively improving the component utilization efficiency.

[0032] (2) By adding an organic solution, the present invention effectively modulates the solvent effect of the pretreatment solution system, not only improving the infiltration efficiency of pre-impregnation, but also during the stacking process, as the moisture content of the solution decreases and the acidity increases, the solvation performance of the solution is improved, effectively promoting the catalytic bond-breaking disassembly and component solvation reactions, and realizing the effective disassembly of lignocellulose components and the value-added of disassembled lignin at room temperature with a low acid concentration.

[0033] (3) The pretreatment component separation method proposed by the present invention has low reagent consumption and low energy consumption, and can prepare holocellulose residues that are easily biotransformed and light-colored solvated lignin products.

[0034] (4) The present invention adopts an organic solvent-promoted densification pretreatment method. The densified raw material has a high density, strong antibacterial property, convenient transportation and storage, can effectively reduce the transportation and storage cost of the raw material, and can achieve pretreatment during storage, effectively alleviating the contradiction between seasonal collection of raw materials and stable supply in production.

[0035] (5) First, the lignocellulose raw material is infiltrated in an acidic organic solution, and then densification treatment is carried out to obtain a homogeneous densified raw material; then the densified raw material is stacked at room temperature for a period of time to complete component disassembly and solvated lignin reaction; finally, through component extraction, holocellulose residues and light-colored solvated lignin products are obtained. The present invention realizes the separation of pretreatment components of lignocellulose biomass at room temperature. The enzymatic hydrolysis rate of the holocellulose residue exceeds 90%, and the light-colored solvated lignin can be used as a sunscreen additive. The present invention has the advantages of low energy consumption, low cost and high efficiency, and is suitable for large-scale industrial applications. Specific embodiments:

[0036] The following examples are further illustrations of the present invention, rather than limitations of the present invention.

[0037] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention. Unless otherwise specified, the experimental materials and reagents in this article are all conventional commercially available products in this technical field.

[0038] Example 1

[0039] Using bagasse with a particle size of 5 mm (containing 41.5% cellulose, 23.2% hemicellulose, and 20.1% lignin) as the raw material, and using sulfuric acid and an organic solution containing an acidic catalyst composed of phenoxyethanol, acetone and water with a volume ratio of 50:25:25, and the mass-volume ratio of sulfuric acid and the organic solution is 0.02 g / mL, and the operation is carried out according to the following steps:

[0040] (1) Infiltration and densification: The mass-volume ratio of the raw material to the organic solution is 1:6 g / mL. After infiltrating the raw material in the acidic organic solution at room temperature for 30 minutes, the infiltrated raw material is subjected to pressure filtration and granulation densification treatment to obtain densified lignocellulose raw material and recyclable pressure filtrate;

[0041] (2) Stacking treatment: The densified lignocellulose raw material is placed at room temperature for 14 days to obtain stacked densified raw material;

[0042] (3) Component extraction: The stacked densified raw material is added to phenoxyethanol with a mass 5 times that of the stacked densified raw material, and stirred at 50 °C for 30 minutes. Solid-liquid separation is carried out to obtain holocellulose residue and extraction reaction solution. The extraction reaction solution is added dropwise to isopropyl ether with a volume 5 times that of the extraction reaction solution, and solid-liquid separation is carried out to obtain solvated lignin product and filtered extraction solution;

[0043] (4) Conversion and utilization: The stacked densified raw material and the holocellulose residue are respectively added to a citric acid-sodium citrate buffer solution with a pH of 4.8 at a substrate concentration of 5%, and enzymatically hydrolyzed at 50 °C for 72 h under CTec3 enzyme with 10 FPU / g cellulose to obtain reducing sugars (glucose, xylose).

[0044] In this example, the volume-mass ratio of the solution to the raw material in the obtained densified lignocellulose raw material is 1.7 mL / g, and the dosage of the acidic catalyst is 0.034 g / g raw material. The enzymatic hydrolysis rate of the stacked densified raw material is 82.3%, and the enzymatic hydrolysis rate of the holocellulose residue is 91.1%. 0.12 g / g raw material of a light-colored solvated lignin product containing a phenoxyethanol-based -O-lignin structure is recovered.

[0045] Comparative Example 1

[0046] This comparative example is to compare the pretreatment effects of acidic aqueous solution and basic organic solution (Example 1) under the same conditions. The specific process is the same as that of Example 1, except that no organic solvent is added to the acidic aqueous solution, that is, the acidic aqueous solution consists of an aqueous solution with a sulfuric acid concentration of 0.02 g / mL.

[0047] In this comparative example, the volume-mass ratio of the solution to the raw material in the obtained densified lignocellulose raw material is 1.5 mL / g, and the dosage of the acidic catalyst is 0.03 g / g raw material. After stacking for 5 days, obvious microbial growth marks appear on the stacked densified raw material. After stacking for 14 days, the enzymatic hydrolysis rate of the stacked densified raw material is 33.7%.

[0048] Comparative Example 2

[0049] Same as Example 1, the difference is that: in step (1), the infiltrated raw material is not subjected to pressure filtration and granulation densification treatment, and directly proceeds to step (2) stacking treatment.

[0050] In this comparative example, the volume-mass ratio of the solution to the raw material in the obtained non-densified lignocellulosic raw material was 6.0 mL / g, and the dosage of the acidic catalyst was 0.12 g / g of the raw material. The enzymatic hydrolysis rate of the stacked non-densified raw material was 19.3%, the enzymatic hydrolysis rate of the brown cellulose residue was 36.1%, and 0.05 g / g of the raw material of a light-colored solvated lignin product containing a phenoxyethanol-based -O-lignin structure was recovered.

[0051] When Example 1 was compared with Comparative Examples 1-2, the enzymatic hydrolysis rates of the raw materials obtained without adding an organic solution or by pressure filtration and granulation densification treatment were significantly lower than those of Example 1. The combined action of the acidic organic solution impregnation, pressure filtration, and granulation densification treatment proposed in the present invention realized the pretreatment component separation of lignocellulosic biomass at room temperature and greatly improved the enzymatic hydrolysis rate of the holocellulose residue.

[0052] Example 2

[0053] Using bagasse with a particle size of 5 mm (containing 41.5% cellulose, 23.2% hemicellulose, and 20.1% lignin) as the raw material, and an organic solution containing an acidic catalyst composed of sulfuric acid, phenoxyethanol and water with a volume ratio of 80:20, the mass-volume ratio of sulfuric acid to the organic solution was 0.02 g / mL, and the following steps were carried out:

[0054] (1) Infiltration and densification: The mass-volume ratio of the raw material to the organic solution was 1:6 g / mL. After infiltrating the raw material in the acidic organic solution at room temperature for 30 minutes, pressure filtration and granulation densification treatment were carried out on the infiltrated raw material to obtain a densified lignocellulosic raw material and a recyclable pressure filtrate;

[0055] (2) Stacking treatment: The densified lignocellulosic raw material was placed at room temperature for 14 days to obtain a stacked densified raw material;

[0056] (3) Component extraction: The stacked densified raw material was added to phenoxyethanol with a mass 5 times that of the stacked densified raw material, stirred at 50 °C for 30 minutes, and solid-liquid separation was carried out to obtain a holocellulose residue and an extraction reaction solution. The extraction reaction solution was added dropwise to isopropyl ether with a volume 5 times that of the extraction reaction solution, and solid-liquid separation was carried out to obtain a solvated lignin product and a filtered extraction solution;

[0057] (4) Conversion and utilization: The stacked densified raw material and the brown cellulose residue were respectively added to a citric acid-sodium citrate buffer solution with a pH of 4.8 at a substrate concentration of 5%, and were enzymatically hydrolyzed at 50 °C on a shaker for 72 h with CTec3 enzyme at 10 FPU / g of cellulose to obtain reducing sugars (glucose, xylose).

[0058] In this example, the volume-to-mass ratio of the solution to the raw material in the densified lignocellulose raw material is 2.0 mL / g, and the dosage of the acidic catalyst is 0.04 g / g of the raw material. The enzymatic hydrolysis rate of the stacked densified raw material is 60.3%, and the enzymatic hydrolysis rate of the brown cellulose residue is 80.4%. 0.10 g / g of the raw material of a light-colored solvated lignin product containing a phenoxyethanol-based -O-lignin structure is recovered.

[0059] Example 3

[0060] Using corn straw with a particle size of 2 mm (containing 32.3% cellulose, 21.0% hemicellulose, and 15.6% lignin) as the raw material, and an acidic organic solution composed of sulfuric acid, triethylene glycol and water with a volume ratio of 20:80, the mass-to-volume ratio of sulfuric acid to the organic solution is 0.02 g / mL, and the operation is carried out according to the following steps:

[0061] (1) Infiltration and densification: The mass-to-volume ratio of the raw material to the organic solution is 1:8 g / mL. The raw material is infiltrated in the acidic organic solution at room temperature. After mechanical stirring for 30 minutes, the infiltrated raw material is subjected to pressure filtration and granulation densification treatment to obtain a densified lignocellulose raw material and a filtrate.

[0062] (2) Stacking treatment: The densified lignocellulose raw material is placed at room temperature for 35 days to obtain a stacked densified raw material.

[0063] (3) Component extraction: The stacked densified raw material is added to triethylene glycol with a mass 5 times that of the stacked densified raw material, and stirred at 50 °C for 30 minutes. After solid-liquid separation, a holocellulose residue and an extraction reaction solution are obtained. The extraction reaction solution is added dropwise to water with a volume 5 times that of the extraction reaction solution, and after solid-liquid separation, a solvated lignin product and a filtered extraction solution are obtained.

[0064] (4) Conversion and utilization: The brown cellulose residue is subjected to high-solid enzymatic hydrolysis in a fed-batch manner. The substrate concentration is 20%, a citric acid-sodium citrate buffer solution with a pH of 4.8, CTec3 enzyme at 10 FPU / g of cellulose, and enzymatic hydrolysis is carried out on a shaker at 50 °C. At 12 h, 24 h, and 36 h of enzymatic hydrolysis, an equal amount of the residue and the corresponding CTec3 enzyme at 10 FPU / g of cellulose are added respectively to make the substrate concentration reach 38%, and enzymatic hydrolysis is carried out until 72 h.

[0065] In this example, the volume-to-mass ratio of the solution to the raw material in the densified lignocellulose raw material is 1.5 mL / g, and the dosage of the acidic catalyst is 0.03 g / g of the raw material. After fed-batch high-solid enzymatic hydrolysis, the glucose concentration in the hydrolysis solution is 132.6 g / L, and the xylose concentration is 69.8 g / L.

[0066] Example 4

[0067] Using bagasse with a particle size of 5 mm (containing 41.5% cellulose, 23.2% hemicellulose, and 20.1% lignin) as the raw material, and using the filtrate under pressure in Example 1 as the acidic organic solution, repeat the steps in Example 1 to test the recycling performance of the acidic organic solution. After 3 cycles of the acidic organic solution, the volume-to-mass ratios of the solution to the raw material in the densified lignocellulosic raw material obtained are 1.7 mL / g, 1.7 mL / g, and 1.8 mL / g respectively, and the enzymatic hydrolysis rates of the stacked densified raw materials obtained are 80.7%, 76.4%, and 74.1% respectively.

[0068] Example 5

[0069] Using bamboo chips with a particle size of 5 mm (containing 42.8% cellulose, 19.2% hemicellulose, and 20.8% lignin) as the raw material, and using p-toluenesulfonic acid and an acidic organic solution composed of triethylene glycol and water with a volume ratio of 10:90, and the mass-to-volume ratio of p-toluenesulfonic acid to the organic solution is 0.05 g / mL, operate according to the following steps:

[0070] (1) Infiltration and densification: The mass-to-volume ratio of the raw material to the organic solution is 1:8 g / mL. At room temperature, immerse the raw material in the acidic organic solution. After standing at room temperature for 60 minutes, perform pressure filtration on the infiltrated raw material to obtain densified lignocellulosic raw material and filtrate under pressure;

[0071] (2) Stacking treatment: Place the densified lignocellulosic raw material at room temperature for 7 days to obtain stacked densified raw material;

[0072] (3) Component extraction: Add the stacked densified raw material to 5 times the mass of the stacked densified raw material of triethylene glycol, stir at 50 °C for 30 minutes, and perform solid-liquid separation to obtain holocellulose residue and extraction reaction solution. Dropwise add the extraction reaction solution into 5 times the volume of water of the extraction reaction solution, and perform solid-liquid separation to obtain solvated lignin product and filtered extraction solution;

[0073] (4) Conversion and utilization: Add the stacked densified raw material and holocellulose residue respectively to a citric acid-sodium citrate buffer solution with a pH of 4.8 at a substrate concentration of 5%, and under CTec3 enzyme at 10 FPU / g cellulose, perform enzymatic hydrolysis on a shaker at 50 °C for 72 h.

[0074] In this example, the volume-to-mass ratio of the solution to the raw material in the densified lignocellulosic raw material obtained is 1.6 mL / g, and the dosage of the acidic catalyst is 0.08 g / g of the raw material. The enzymatic hydrolysis rate of the stacked densified raw material is 73.1%, the enzymatic hydrolysis rate of the holocellulose residue is 77.2%, and 0.08 g / g of the raw material of a light-colored solvated lignin product containing triethylene glycol-based -O-lignin structure is recovered.

[0075] The description of the above embodiments is only used to help understand the technical solution and its core idea of the present invention. It should be noted that for those skilled in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for separating lignocellulose components by acid organic solution densification pretreatment, characterized in that, It includes the following steps: (1) Impregnation and densification: Immerse the lignocellulosic raw material in an acidic organic solution. After the reagents in the acidic organic solution penetrate into the interior of the raw material, through the densification method, a densified lignocellulosic raw material with a homogeneous mixture of reagents and raw materials and a recyclable press filtrate are obtained. The acidic organic solution is prepared by mixing an acidic catalyst and an organic solution. The organic solution is a homogeneous solution composed of a first lignin-solubilizing organic solvent, a cosolvent, and water. The volume content of the lignin-solubilizing organic solvent in the organic solution is not less than 1%, the volume content of the cosolvent is not more than 40%, and the volume content of water is not less than 20%; (2) Stacking treatment: Stack the densified lignocellulosic raw material for a period of time to obtain a stacked densified raw material; (3) Component extraction: Add the stacked densified raw material to a second lignin-solubilizing organic solvent for reaction, perform solid-liquid separation to obtain holocellulose residue and an extraction reaction solution, add an anti-solvent to the extraction reaction solution, and perform solid-liquid separation to obtain a solvated lignin product and a recyclable filtered extraction solution; (4) Conversion and utilization: Perform bioconversion and utilization on the stacked densified raw material and / or holocellulose residue.

2. The method according to claim 1, wherein The raw materials in step (1) include pennisetum, miscanthus, wood chips, straw, bagasse, bamboo chips, furfural residue, agricultural and forestry waste, and processing waste of the above substances.

3. The method according to claim 1, wherein In the acidic organic solution in step (1), the mass-volume ratio of the acidic catalyst to the organic solution is less than or equal to 0.05 g / mL. The acidic catalyst is selected from one or more of inorganic acids, organic acids, and strong acidic weak base salts that are soluble in the organic solution.

4. The method according to claim 1 or 3, characterized in that, The dosage of the acidic catalyst in step (1) is no more than 0.10 grams added per gram of raw material.

5. The method according to claim 1, characterized in that The first lignin-solubilizing organic solvent in step (1) is selected from more than one of triethylene glycol, phenoxyethanol, glycerol formal, dihydrolevoglucosenone, tetrahydrofurfuryl alcohol, and dimethyl isosorbide; the cosolvent is selected from more than one of ethanol, acetone, isobutanol, ethylene glycol, glycerol, triethylene glycol, phenoxyethanol, glycerol formal, dihydrolevoglucosenone, tetrahydrofurfuryl alcohol, and dimethyl isosorbide.

6. The method according to claim 1 or 5, characterized in that The volume ratio of the first lignin-solubilizing organic solvent, cosolvent, and water is (10 - 50):(0 - 30):(20 - 90).

7. The method according to claim 1, wherein The stacking conditions in step (2) are: the stacking time is not less than 3 days, and the stacking temperature is not lower than 20 °C.

8. The method according to claim 1, characterized in that, The second lignin-solubilizing organic solvent in step (3) is selected from more than one of triethylene glycol, phenoxyethanol, glycerol formal, dihydrolevoglucosenone, tetrahydrofurfuryl alcohol, and dimethyl isosorbide; the anti-solvent is selected from more than one of water, dimethyl carbonate, isopropyl ether, and dimethoxymethane.

9. The method according to claim 1 or 8, characterized in that, The mass ratio of the stacked densified raw material to the second lignin-solubilizing organic solvent in step (3) is 1:4 - 6, and the volume ratio of the extraction reaction solution to the anti-solvent is 1:4 - 6.

10. The method according to claim 1, wherein The bioconversion and utilization in step (4) is to prepare chemicals and / or fuels through a biochemical conversion pathway. The chemicals and / or fuels include, but are not limited to, reducing sugars, ethanol, butanol, acetone, acetic acid, lactic acid, oils and fats, proteins, biogas, and amino acids.