CN116903881B - Method for separating non-condensed lignin and saccharide compounds from deconstructed lignocellulose - Google Patents
Method for separating non-condensed lignin and saccharide compounds from deconstructed lignocelluloseInfo
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- CN116903881B CN116903881B CN202310862175.2A CN202310862175A CN116903881B CN 116903881 B CN116903881 B CN 116903881B CN 202310862175 A CN202310862175 A CN 202310862175A CN 116903881 B CN116903881 B CN 116903881B
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
- C08H6/00—Macromolecular compounds derived from lignin, e.g. tannins, humic acids
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- C07—ORGANIC CHEMISTRY
- C07G—COMPOUNDS OF UNKNOWN CONSTITUTION
- C07G1/00—Lignin; Lignin derivatives
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- C—CHEMISTRY; METALLURGY
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- C07G99/00—Subject matter not provided for in other groups of this subclass
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- C13—SUGAR INDUSTRY
- C13K—SACCHARIDES OBTAINED FROM NATURAL SOURCES OR BY HYDROLYSIS OF NATURALLY OCCURRING DISACCHARIDES, OLIGOSACCHARIDES OR POLYSACCHARIDES
- C13K1/00—Glucose; Glucose-containing syrups
- C13K1/02—Glucose; Glucose-containing syrups obtained by saccharification of cellulosic materials
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- C13—SUGAR INDUSTRY
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- C13K1/00—Glucose; Glucose-containing syrups
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- C13K—SACCHARIDES OBTAINED FROM NATURAL SOURCES OR BY HYDROLYSIS OF NATURALLY OCCURRING DISACCHARIDES, OLIGOSACCHARIDES OR POLYSACCHARIDES
- C13K13/00—Sugars not otherwise provided for in this class
- C13K13/002—Xylose
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Abstract
The invention discloses a method for separating non-condensed lignin and saccharide compounds from deconstructed lignocellulose. The method comprises the steps of taking lignocellulose as a raw material, adding high-boiling alcohol aqueous solution such as dihydric alcohol or trihydric alcohol into acid molten salt hydrate to serve as a deconstructing reaction system, wherein the acid molten salt hydrate firstly hydrolyzes hemicellulose and cellulose in the lignocellulose into saccharide compounds, and meanwhile, the high-boiling alcohol in the system serves as a lignin dissolver and a structure protective agent, so that lignin is dissolved in the high-boiling alcohol, and then adding water to precipitate lignin, so that non-condensed lignin and saccharide compounds are separated. By adopting the biomass deconstructing method to extract non-condensed lignin and saccharide compounds, the full-component utilization of three components of lignocellulose can be effectively promoted, and the biomass deconstructing method has great industrial application potential.
Description
Technical Field
The invention belongs to the field of lignocellulose deconstruction, and particularly relates to a method for separating non-condensed lignin and saccharide compounds from deconstructed lignocellulose.
Background
The lignocellulose mainly comprises lignin, cellulose and hemicellulose, and three components of the lignocellulose are mutually entangled to form a compact structure due to complex chemical connection and physical coating among the three components. Wherein, lignin is a heterogeneous, amorphous and complex phenolic polymer formed by connecting three phenylpropane units (guaiacyl, syringyl and p-hydroxyphenyl) through C-O bond and C-C bond, and widely exists in the rootstocks of trees, grasses and other plants, and forms a skeleton structure of the plants together with cellulose and hemicellulose. Lignin is the second most renewable resource next to cellulose in nature, and is the natural polymer with the most abundant reserves and aromatic structures. The structural characteristics of lignin lead the lignin to have great application potential in the fields of construction, medicine, cosmetics, wastewater treatment and the like. At the same time, lignin can also break the linkage between structural units to degrade into small molecular aromatic and naphthenic compounds, which are used as a substitute for fossil resources for the preparation of liquid fuels or high-value chemicals.
Although lignin has a wide range of uses, separation of lignin is often required under more severe conditions due to the dense structure between the three components. At present, lignin separation methods can be mainly classified into three types, namely an alkaline treatment strategy, namely, lignin is dissolved in water by high-temperature digestion under alkaline conditions, and hemicellulose and cellulose are separated in a solid form. For example, paper making pulping processes make use of this separation principle. The beta-O-4 bond in the lignin structure is inevitably cracked and forms a firm C-C bond due to high-temperature and high-pressure digestion, so that subsequent degradation reaction of lignin is difficult to carry out due to condensation, and high-value utilization of the lignin is restricted. Secondly, the "hydrolysis" strategy, in which hemicellulose and cellulose are hydrolyzed to monosaccharides at higher temperatures or for prolonged periods of time by acid or enzyme catalysis, lignin is separated as an insoluble residue. Hemicellulose and cellulose are hydrolyzed to sugars, for example, by acidic pretreatment of wood, and lignin is separated out as a solid. The lignin obtained likewise undergoes more severe condensation, due to the higher temperatures or longer times of the separation process. Another is an "organic solvent dissolution" strategy, in which lignin is dissolved in an organic solvent, ionic liquid or eutectic solvent (DESs) at a lower temperature for a short period of time, wherein lignin is separated as a soluble component and other components as insoluble materials. Although the separated lignin is not easy to be condensed, the extraction rate of the lignin is low, and moreover, the method is not suitable for industrialization due to the high cost of the organic solvent and the negative influence of the organic solvent on the environment, and is commonly used for researching the lignin bulk structure. Therefore, the development of mild, clean and efficient non-condensed lignin separation technology can deconstruct complex entanglement under the condition of retaining three-component functional structures to the maximum extent, and has important significance for realizing high-value utilization of lignocellulose.
The inorganic fused salt hydrate is a concentrated inorganic salt solution with water molecules close to cationic coordination numbers, and the salt concentration is between the concentrated salt solution and the fused salt. The inorganic fused salt hydrate has the functions of dissolving cellulose, breaking hydrogen bonds and increasing solubility similar to the ionic liquid, and has the advantages of low viscosity, low cost, no toxicity and the like which are not possessed by the ionic liquid. It has been reported that Li et al (Green chem.,2016,18,5367-5376) can hydrolyze cellulose and hemicellulose into glucose and xylose by a one-step method to obtain lignin of high purity, and has the advantage of simple process, but Li et al (Green chem.,2020,22,7989) found that the acid salt-melted hydrate easily cracks beta-O-4, beta-5 and beta-beta bonds other than 4-O-5 bonds in lignin structure, and the destruction of beta-O-4 bonds leads to condensation of lignin structure, affecting the subsequent further high-value utilization of lignin. Although Liu et al (Green chem.,2022,24,8812) and Sadula et al (Green chem.,2021,23,1200) directly hydrolyze lignocellulose using inorganic melt salt hydrate without acid to obtain oligosaccharides and lignin residues, the process requires long reaction at high temperature, which also causes the beta-O-4 bond easily broken in lignin to condense into a C-C bond difficult to break, and non-condensed lignin cannot be obtained.
High boiling alcohol solvents, such as ethylene glycol, glycerol, and butylene glycol, are not volatile, have low operating pressure, and can capture reactive benzyl cations formed under acidic conditions, and prevent condensation reaction of lignin by alkoxylation of C α -OH in lignin phenylpropane structural units, thereby becoming a hot solvent for acid-catalyzed extraction of lignin. There are a number of literature reports that high boiling alcohols such as dihydric or trihydric alcohols effectively protect the benzyl groups of lignin during acid catalyzed treatment of hardwood and herbal lignocellulose, thereby effectively separating low condensation lignin, such as Dong et al (Green chem.,2019, 21:2788) using various high boiling alcohols in combination with dilute sulfuric acid to extract low condensation lignin from eucalyptus at 170 ℃. Jia et al (APPLIED MECHANICS AND MATERIALS,2013, 320:429-434) separated high-boiling alcohol lignin from pine nut shells by a high-boiling solvent method with 90% 1, 4-butanediol solution as a solvent, and the lignin yield can reach 70%.
However, it is difficult to achieve simultaneous separation of non-condensed lignin and carbohydrate by deconstructing lignocellulose in the prior art, and therefore, how to achieve simultaneous separation of non-condensed lignin and carbohydrate by deconstructing lignocellulose by a simple and mild process is a technical problem to be solved at present.
Disclosure of Invention
In order to solve the defects and shortcomings of the prior art, the invention aims to provide a method for separating non-condensed lignin and saccharide compounds from deconstructed lignocellulose.
The method of the invention is to hydrolyze lignocellulose by combining an acid molten salt hydrate with a high-boiling alcohol water solvent system. The method comprises the steps of taking lignocellulose as a raw material, adding high-boiling alcohol aqueous solution such as dihydric alcohol or trihydric alcohol into acid molten salt hydrate to serve as a deconstructing reaction system, wherein the acid molten salt hydrate firstly hydrolyzes hemicellulose and cellulose in the lignocellulose into saccharide compounds, and meanwhile, the high-boiling alcohol in the system serves as a lignin dissolver and a structure protective agent, so that lignin is dissolved in the high-boiling alcohol, and then adding water to precipitate lignin, so that non-condensed lignin and saccharide compounds are separated. The acid fused salt hydrate used in the hydrolysis process can break cellulose crystals at a lower temperature, catalyze and break beta-1, 4 glycosidic bonds, and hydrolyze lignocellulose to produce saccharide compounds. While the high boiling alcohol can trap the reactive benzyl cations formed under acidic conditions, and bind to the C α -OH in the lignin phenylpropane building block by alpha-alkoxylation to prevent polycondensation of lignin. The depolymerization effect of lignin is directly related to the structure, and essentially, the depolymerization of lignin is to realize the cleavage of the linkage between the phenylpropane structural units. The main linkage in lignin is ether bond (C-O) and carbon-carbon bond (C-C), the dissociation energy of C-C bond is higher than that of C-O bond, and the specific C-O and C-C bond energy is different. The three main C-O bonds are located in the α -O-4 linkage, the β -O-4 linkage, and the 4-O-5 linkage, respectively. The smaller the dissociation energy of the beta-O-4 bond, the more the linkage bonds in lignin, particularly the more the beta-O-4 bonds with lower bond energy and rich distribution, the higher the monophenol product obtained by depolymerization is believed to be.
The invention aims at realizing the following technical scheme:
a method for separating non-condensed lignin and saccharide compounds from deconstructed lignocellulose, comprising the steps of:
(1) Uniformly mixing inorganic fused salt, high-boiling alcohol and inorganic acid dilute solution with the concentration of 0.4-1.2wt% to form an acidic fused salt high-boiling alcohol-water system;
(2) Adding lignocellulose raw materials into the acidic molten salt high-boiling alcohol water system obtained in the step (1), uniformly mixing, heating for hydrolysis, adding water for precipitation, filtering, wherein filtrate is saccharide compound solution, and filter residues are non-condensed lignin.
Preferably, the inorganic molten salt in the step (1) is at least one of LiCl, liBr and ZnBr 2.
Preferably, the mass ratio of the inorganic molten salt to the inorganic acid diluted solution with the concentration of 0.4-1.2 wt% in the step (1) is (1-2.5): 1, more preferably (1-2.3): 1.
Preferably, the high-boiling alcohol in the step (1) is at least one of 1, 4-butanediol, glycerol and ethylene glycol.
Preferably, the mass ratio of the high-boiling alcohol to the inorganic acid dilute solution with the concentration of 0.4-1.2 wt% in the step (1) is 1 (1-1.5), and more preferably is 1:1.
Preferably, the inorganic acid in the dilute solution of inorganic acid with the concentration of 0.4-1.2 wt% in the step (1) is at least one of hydrochloric acid, sulfuric acid and phosphoric acid.
Preferably, the lignocellulose raw material in the step (2) is at least one of birch, straw and pine.
More preferably, the lignocellulosic feedstock is crushed and sieved using a 60 mesh sieve prior to use.
Preferably, the temperature of the heating hydrolysis in the step (2) is 110-130 ℃ and the time is 30-90 min.
More preferably, the time of the thermal hydrolysis in the step (2) is 45-60 min.
Most preferably, the temperature of the heated hydrolysis in step (2) is 110 ℃ and the time is 45min.
Preferably, the mass ratio of the lignocellulose raw material to the acidic molten salt high-boiling alcohol-water system in the step (2) is (1-10): 100.
Preferably, in the precipitation by adding water in the step (2), the volume ratio of the hydrolysis mixture to the added water is 1 (3-8), and more preferably 1:4.
The method adopted by the invention can convert hemicellulose and cellulose into saccharide compounds with high utilization value under milder conditions and separate out non-condensed lignin. Wherein, the coordination water of the cation of the fused salt hydrate replaces the hydroxyl in cellulose, and the anion forms hydrogen bond with the hydrogen in the hydroxyl of cellulose to break the intermolecular and intramolecular hydrogen bonds of cellulose, thereby breaking the crystal structure of cellulose and swelling and dissolving cellulose. Under the action of acid, the glycosidic bond between cellulose chains is broken, and thus hydrolyzed into saccharide compounds. The high-boiling alcohol can capture reactive benzyl cations formed under acidic conditions in the system, prevent polycondensation reaction through alkoxylation of C α -OH in lignin phenylpropane structural units, promote dissolution of lignin in lignocellulose raw materials, and facilitate further processing and utilization of lignin, so that comprehensive utilization of lignocellulose three components is realized. Compared with the traditional salt melting treatment process, the high-yield saccharide compound solution is obtained, the beta-O-4 bond of lignin and the extraction rate of lignin can be greatly reserved, and the consumption of inorganic acid in the process is reduced. Compared with the traditional high-boiling alcohol treatment process, the method can obtain high-yield saccharide compound solution while maintaining the extraction rate of beta-O-4 bond of lignin and lignin, and reduces the consumption of high-boiling alcohol in the process. By adopting the biomass deconstructing method to extract non-condensed lignin and saccharide compounds, the full-component utilization of three components of lignocellulose can be effectively promoted, and the biomass deconstructing method has great industrial application potential.
Compared with the prior art, the invention has the following advantages:
1. The method uses acid molten salt high-boiling alcohol water system full-component decomposition to construct biomass materials under mild conditions, wherein the coordination water of the molten salt hydrate cation replaces hydroxyl in cellulose, anions and hydrogen in cellulose hydroxyl form hydrogen bonds to damage intermolecular and intramolecular hydrogen bonds of cellulose, and further damage the crystal structure of cellulose to swell and dissolve cellulose. Under the action of acid, the glycosidic bond between cellulose chains is broken, and thus hydrolyzed into saccharide compounds. The high boiling alcohol can capture the reactive benzyl cations formed under acidic conditions in this system, and prevent polycondensation by alkoxylation of the C α -OH in the lignin phenylpropane building block.
2. In the process of hydrolyzing lignocellulose, the high-boiling alcohol, the molten salt and the inorganic acid used in the invention are cheap and easy to obtain, are easy to recycle, are easy to realize large-scale preparation, and can realize high-value utilization of lignocellulose.
3. The method can achieve 96.4 percent of xylose yield, 93.5 percent of glucose yield, 90.7 percent of non-condensed lignin extraction rate and 24.9 percent of monophenol yield after lignin hydrogenolysis under the treatment process, realizes the efficient deconstruction of three components, and can obviously reduce the consumption of high-boiling alcohol and inorganic acid.
4. Compared with other inorganic fused salt hydrate hydrolysis processes, the method can retain the beta-O-4 bond of lignin to a great extent, is free from dangerous chemicals or flammable and explosive products, has simple flow, and is safe, green and environment-friendly.
Drawings
FIG. 1 is a physical view of lignin obtained in example 1.
FIG. 2 is a physical view of lignin obtained in comparative example 1.
FIG. 3 is a 2D-HSQC NMR spectrum of lignin obtained in example 1 and comparative example 1.
FIG. 4 is a GCMS spectrum of the lignin hydrogenolysis product obtained in example 1 and comparative example 1.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but embodiments of the present invention are not limited thereto.
The specific conditions are not noted in the examples of the present invention, and are carried out according to conventional conditions or conditions suggested by the manufacturer. The raw materials, reagents, etc. used, which are not noted to the manufacturer, are conventional products commercially available.
The xylose yield, glucose yield, lignin extraction rate and monophenol yield after lignin hydrogenolysis are calculated as follows.
The structure of the wood-grinding lignin is considered to be closest to that of real lignin, and the lignin obtained by the method is subjected to hydrogenolysis, so that the beta-O-4 bond content of the lignin can be indirectly judged by comparing the yield of monophenol with that of the wood-grinding lignin, and the condensation degree of the lignin is judged.
The method for preparing the wood grinding lignin for comparing and judging whether the lignin in the examples and the comparative examples is condensed or not comprises the following steps:
about 30g of dewaxed birch wood flour was weighed into a planetary ball mill and ball-milled in a zirconia bottle at 400rpm using zirconia balls (20×20 mm). The total ball milling time was 5h, and was paused for 5min after each 5min of ball milling. The ball-milled wood flour was then extracted with dioxane/aqueous solution=9:1 (v/v), the ratio of feed to liquid was 20mL of solvent per 1g of sample, and the reaction mixture was filtered after heating in a 100 ℃ oil bath for 12h. The filtrate was evaporated to dryness in a rotary evaporator at 40 ℃ to give crude lignin. The crude lignin was then redissolved in acetic acid/water=9:1 (v/v) solution at a feed to liquid ratio of 1g of crude lignin sample dissolved per 25mL of solvent. This mixed liquid was then precipitated into cold water, the separated lignin was ground in an agate mortar by centrifugation, and then dissolved in a 1, 2-dichloroethane/ethanol=1:2 (v/v) solution, and the mixture was centrifuged to remove insoluble matters. Precipitating lignin in the supernatant with diethyl ether, and centrifuging for recovery. And after centrifugation, washing with petroleum ether, and freeze-drying to obtain the purified ground wood lignin.
The lignin hydrogenolysis methods in the examples and comparative examples of the present invention were as follows:
0.2g lignin, 40mg Ru/C (Ru content 5%, moisture content about 50%), and 20mL ethanol were added to a 100mL autoclave. The depolymerization reaction of lignin was carried out at 225 ℃ under H 2 at 2MPa for 240min. After the reaction, the autoclave was cooled to room temperature with cooling water. And carrying out qualitative and quantitative analysis on the depolymerized product by using gas chromatography.
Example 1
(1) Uniformly mixing 5g of LiCl, 5g of hydrochloric acid solution with the concentration of 1.2wt% and 5g of 1, 4-butanediol to form an acidic fused salt high-boiling alcohol water system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the high-boiling alcohol water system of the acid molten salt prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding the hydrolysis mixed solution into 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain non-condensed lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Example 2 (changing the kind of acid)
(1) Uniformly mixing 5g of LiCl, 5g of sulfuric acid solution with the concentration of 0.6wt% and 5g of 1, 4-butanediol to form an acidic fused salt high-boiling alcohol water system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the high-boiling alcohol water system of the acid molten salt prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding the hydrolysis mixed solution into 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain non-condensed lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Example 3 (changing the kind of acid)
(1) Uniformly mixing 5g of LiCl, 5g of phosphoric acid solution with the concentration of 0.4wt% and 5g of 1, 4-butanediol to form an acidic fused salt high-boiling alcohol water system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the high-boiling alcohol water system of the acid molten salt prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding the hydrolysis mixed solution into 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain non-condensed lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Example 4 (modification of high boiling alcohol type)
(1) Uniformly mixing 5g of LiCl, 5g of hydrochloric acid solution with the concentration of 1.2wt% and 5g of glycerol to form an acidic fused salt high-boiling alcohol-water system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the high-boiling alcohol water system of the acid molten salt prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding the hydrolysis mixed solution into 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain non-condensed lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Example 5 (modification of high boiling alcohol type)
(1) Uniformly mixing 5g of LiCl, 5g of hydrochloric acid solution with the concentration of 1.2wt% and 5g of ethylene glycol to form an acidic fused salt high-boiling alcohol-water system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the high-boiling alcohol water system of the acid molten salt prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding the hydrolysis mixed solution into 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain non-condensed lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Example 6 (LiCl concentration was varied)
(1) Uniformly mixing 7.5g of LiCl, 5g of hydrochloric acid solution with the concentration of 1.2wt% and 5g of 1, 4-butanediol to form an acidic fused salt high-boiling alcohol water system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the high-boiling alcohol water system of the acid molten salt prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding the hydrolysis mixed solution into 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain non-condensed lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Example 7 (varying the type, concentration and hydrochloric acid concentration of the molten salt)
(1) Uniformly mixing 7.5g of LiBr, 5g of hydrochloric acid solution with the concentration of 0.7wt% and 5g of 1, 4-butanediol to form an acidic fused salt high-boiling alcohol water system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the high-boiling alcohol water system of the acid molten salt prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding the hydrolysis mixed solution into 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain non-condensed lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Example 8 (varying the type, concentration and hydrochloric acid concentration of the molten salt)
(1) Uniformly mixing 11.6g of ZnBr 2, 5g of hydrochloric acid solution with the concentration of 0.8wt% and 5g of 1, 4-butanediol to form an acidic fused salt high-boiling alcohol-water system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the high-boiling alcohol water system of the acid molten salt prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding the hydrolysis mixed solution into 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain non-condensed lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Example 9 (modification of hydrolysis temperature)
(1) Uniformly mixing 5g of LiCl, 5g of hydrochloric acid solution with the concentration of 1.2wt% and 5g of 1, 4-butanediol to form an acidic fused salt high-boiling alcohol water system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the high-boiling alcohol water system of the acid molten salt prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 130 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain non-condensed lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Example 10 (modification of raw materials)
(1) Uniformly mixing 5g of LiCl, 5g of hydrochloric acid solution with the concentration of 1.2wt% and 5g of 1, 4-butanediol to form an acidic fused salt high-boiling alcohol water system;
(2) Adding 0.3g of corn stalk raw material into 10g of the acid molten salt high-boiling alcohol water system prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding the hydrolysis mixed solution into 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain non-condensed lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Example 11 (Change of raw materials)
(1) Uniformly mixing 5g of LiCl, 5g of hydrochloric acid solution with the concentration of 1.2wt% and 5g of 1, 4-butanediol to form an acidic fused salt high-boiling alcohol water system;
(2) Adding 0.3g of pine wood powder raw material into 10g of the acid molten salt high-boiling alcohol water system prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain non-condensed lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Comparative example 1 (compared with example 1, no higher boiling alcohol)
(1) 3.33G of LiCl and 6.67g of hydrochloric acid solution with the concentration of 0.6 weight percent are uniformly mixed to form an acid fused salt hydrate system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the acid melt salt hydrate system prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Filtering the hydrolysis mixed solution obtained in the step (2), wherein the filtrate is a sugar solution, washing and drying the obtained filter residues to obtain lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Comparative example 2 (compared with example 1, no molten salt was added)
(1) Uniformly mixing 6.67g of hydrochloric acid solution with the concentration of 0.6wt% and 3.33g of 1, 4-butanediol to form a high-boiling alcohol water system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the high-boiling alcohol-water system prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Filtering the hydrolysis mixed solution (mixture of lignin and residues) obtained in the step (2) to obtain lignin-containing filtrate, taking 5mL of filtrate which is unhydrolyzed hemicellulose and cellulose, adding the filtrate into 20mL of water to precipitate lignin, filtering, washing and drying the obtained precipitate to obtain lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the sugar solution in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing for 60min at 130 ℃, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Comparative example 3 (improvement of hydrochloric acid concentration compared to example 1)
(1) Uniformly mixing 5g of LiCl, 5g of hydrochloric acid solution with the concentration of 6.0wt% and 5g of 1, 4-butanediol to form an acidic fused salt high-boiling alcohol water system;
(2) Adding 10g of the acid molten salt high-boiling alcohol water system prepared in the step (1) into 0.3g of birch wood powder raw material, uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding the hydrolysis mixed solution into 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Comparative example 4 (increase in 1, 4-butanediol concentration compared to example 1)
(1) 3.33G of LiCl, 0.67g of hydrochloric acid solution with the concentration of 5.97wt% and 6.0g of 1, 4-butanediol are uniformly mixed to form an acidic fused salt high-boiling alcohol water system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the high-boiling alcohol water system of the acid molten salt prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 110 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding the hydrolysis mixed solution into 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Comparative example 5 (lower hydrolysis temperature compared to example 1)
(1) Uniformly mixing 5g of LiCl, 5g of hydrochloric acid solution with the concentration of 1.2wt% and 5g of 1, 4-butanediol to form an acidic fused salt high-boiling alcohol water system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the high-boiling alcohol water system of the acid molten salt prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 80 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding the hydrolysis mixed solution into 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
Comparative example 6 (increase in hydrolysis temperature compared to example 1)
(1) Uniformly mixing 5g of LiCl, 5g of hydrochloric acid solution with the concentration of 1.2wt% and 5g of 1, 4-butanediol to form an acidic fused salt high-boiling alcohol water system;
(2) Adding 0.3g of birch wood powder raw material into 10g of the high-boiling alcohol water system of the acid molten salt prepared in the step (1), uniformly mixing, and hydrolyzing for 45min at 220 ℃;
(3) Weighing 15mL of the hydrolysis mixed solution obtained in the step (2), adding the hydrolysis mixed solution into 60mL of water to precipitate lignin, filtering, taking filtrate as a sugar solution, washing and drying the obtained precipitate to obtain lignin, and carrying out hydrogenolysis on the lignin;
(4) Mixing the filtrate obtained in the step (3) with an equal volume of 8wt% sulfuric acid solution, hydrolyzing at 130 ℃ for 60min, hydrolyzing part of oligosaccharides into monosaccharides to obtain a completely hydrolyzed sugar solution, and measuring the xylose and glucose yields through high performance liquid chromatography test.
The results of the example and comparative example biomass deconstruction and the product yields are shown in Table 1.
TABLE 1 Biomass conversion and product yield
The results of the embodiment are shown in Table 1, which shows the results of the biomass deconstruction obtained in the examples of the present invention and the comparative examples and the product yield test data. It can be seen from table 1 that under the reaction system of the present invention, the effects of different concentrations and types of dilute acid solutions, different concentrations and types of molten salts, different concentrations and types of high boiling alcohol systems, and the treatment process on xylose yield, glucose yield, lignin extraction rate, and monophenol yield are different. The treatment process of example 1 allows for high yields of xylose and glucose while maximizing retention of the beta-O-4 structure of lignin, comparable to the monophenol yield of wood-milling lignin. Preferably, an acidic fused salt high-boiling alcohol water system is added into birch wood powder, the mixture is reacted for 45 minutes at 110 ℃, hemicellulose and cellulose are hydrolyzed to obtain saccharide compounds, water is added, suction filtration and separation are carried out to obtain non-condensed lignin, the xylose yield is 96.4%, the glucose yield is 93.5%, the lignin extraction rate is 90.7%, and the monophenol yield after lignin hydrogenolysis is 24.9%, so that the efficient development and utilization of biomass three components are realized.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
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