Method for acquiring lignin with high phenolic hydroxyl group content from residues after hemicelluloses degradation conversion

A technology of hemicellulose and high phenolic hydroxyl group is applied in the field of obtaining lignin with high phenolic hydroxyl group content, which can solve the problems of insufficient utilization of lignin resources, increase of process complexity and cost, weak selectivity of depolymerization and dissolution, and the like, Achieve the effect of easy recovery and recycling, improving quality and added value, and high extraction selectivity

Inactive Publication Date: 2019-09-10
NANJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

During this process, there is a risk of excessive supply of protons, leading to the degradation of hemicellulose, cellulose as well
Polar aprotic solvents are a class of organic solvents that do not self-deliver protons, reducing the risk of excessive proton supply. However, current research focuses on γ-valerolactone, γ-valerolactone, γ- - Polar aprotic solvents with high boiling points such as butyrolactone and dioxane, but these solvents are not very selective for the depolymerization and dissolution of lignin and cellulose, so it is not conducive to improving the purity of lignin
[0004] In order to solve the above drawbacks, currently the extracted lignin generally needs to be chemically modified to increase the phenolic hydroxyl content of lignin, such as phenolization modification, catalytic reduction, demethylation, ultrasonic and electrochemical methods, but These reactions add to the complexity and cost of the process, so increasing the phenolic hydroxyl content of lignin during extraction is of great value
[0005] Furfural, xylose, and xylo-oligosaccharides are typical hemicellulose degradation products. my country is the main producer of furfural, xylose, and xylo-oligosaccharides. The huge amount of residue is rich in lignin and cellulose, but at present it is mainly used as a raw material for the preparation of fuel or activated carbon, and the lignin resources are not fully utilized.

Method used

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  • Method for acquiring lignin with high phenolic hydroxyl group content from residues after hemicelluloses degradation conversion
  • Method for acquiring lignin with high phenolic hydroxyl group content from residues after hemicelluloses degradation conversion
  • Method for acquiring lignin with high phenolic hydroxyl group content from residues after hemicelluloses degradation conversion

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] The corn stalk residue after extracting xylooligosaccharide is used as raw material, the content of tetrahydrofuran in the extractant is 50wt%, the content of sodium hydroxide is 0-1wt%, and the rest is water. According to the solid-liquid mass volume ratio (kg / L) of 1:15, the two were mixed in a high-pressure reactor, the temperature was raised to 170 ° C, and the extraction was carried out for 150 minutes. After the extraction is completed, filter separately, collect the filtrate, and distill to recover the solvent. The remaining water phase is adjusted to pH 2.0 with sulfuric acid, and water is added to obtain lignin precipitation. Ready to serve after drying. The extraction rate of lignin, lignin content (dry dry) and phenolic hydroxyl content (dry dry) in the product were compared, and commercially available alkali lignin was used as a control, as shown in Table 1.

[0027] Table 1

[0028]

[0029] From the data in Table 1, it can be seen that after adding a ...

Embodiment 2

[0034] The wheat stalk residue after extracting xylooligosaccharide is used as raw material, the content of tetrahydrofuran in the extractant is 50wt%, the content of sodium hydroxide is 0.6wt%, and the rest is water. According to the solid-liquid mass volume ratio (kg / L) of 1:12, the two were mixed in a high-pressure reactor, heated to 160°C, and kept for extraction for 120 minutes. After the extraction, filter, collect the filtrate, distill and recover the solvent, adjust the remaining water phase to pH 3.0 with sulfuric acid, and add water to obtain lignin precipitation. Ready to serve after drying. The extraction rate of lignin, lignin content (dry dry) and phenolic hydroxyl content (dry dry) in the product were compared, and commercially available alkali lignin was used as a control, as shown in Table 3.

[0035] table 3

[0036]

[0037] It can be seen from the data in Table 3 that the lignin content in the product is ≥97% and the content of phenolic hydroxyl groups...

Embodiment 3

[0039]The bagasse residue after extracting xylooligosaccharide is used as raw material, the content of tetrahydrofuran in the extractant is 60wt%, the content of potassium hydroxide is 0.8wt%, and the rest is water. According to the solid-liquid mass volume ratio (kg / L) of 1:10, the two were mixed in a high-pressure reactor, heated to 160°C, and kept for extraction for 135 minutes. After the extraction is completed, filter, collect the filtrate, and distill to recover the solvent. The remaining water phase is adjusted to pH 2.5 with sulfuric acid, and water is added to obtain lignin precipitation. The product is filtered, washed with 3 times the volume of water, and dried at 80-100°C Get it later. The extraction rate of lignin, lignin content (dry dry) and phenolic hydroxyl content (dry dry) in the product were compared, and commercially available alkali lignin was used as a control, see Table 4.

[0040] Table 4

[0041]

[0042] It can be seen from Table 4 that the meth...

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Abstract

The invention discloses a method for acquiring lignin with a high phenolic hydroxyl group content from residues after hemicelluloses degradation conversion. The method comprises the following steps: uniformly mixing water, a polar aprotic solvent of a low melting point and a small amount of an alkali so as to obtain an extraction agent, mixing the extraction agent with lignocelluloses formed afterxylooligosaccharide and xylose are extracted or furfural is prepared, increasing the temperature to 150-180 DEG C, conducting a heat-preservation reaction to extract for 90-180 minutes, rapidly decreasing the temperature to 40 DEG C or lower after the reaction is completed, conducting filtration so as to obtain filtrate, washing filter residues twice to three times by using a same type of the polar aprotic solvent which is free of water or alkali and has a same low melting point, completely combining collected filtrate, recycling an organic solvent through distillation, adding 2-3 times of the volume of water into a residual water phase, adjusting the pH value of the solution to 2.0-3.0 by using sulfuric acid, leaving the solution to stand for 2-4 hours to enable lignin to settle down, and conducting filtration, washing and drying on the product, so as to obtain the lignin. By adopting the method, the extraction rate of the lignin in the residues is up to 75% or greater, the loss rateof cellulose in the residues is less than 17%, and high extraction selectivity is achieved for the lignin.

Description

technical field [0001] The invention belongs to the technical field of biochemical industry, and in particular relates to a method for obtaining lignin with high phenolic hydroxyl content from xylooligosaccharide / xylose extraction residue or furfural residue. Background technique [0002] Lignin is a macromolecular amorphous phenolic natural polymer, which can be divided into three basic structural units according to the position and content of methoxy groups in lignin: syringyl lignin, guaiacyl lignin and p-hydroxyl phenyl lignin. Since lignin is rich in active groups such as: phenolic hydroxyl group, carboxyl group, methoxyl group, etc., a variety of chemical reactions can occur, so lignin and its chemically modified products can be used in the fields of polymer materials, among which the content of phenolic hydroxyl group The level is directly related to its reactivity and is an important indicator for its application in the field of polymer materials. [0003] At prese...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08H7/00
CPCC08H6/00
Inventor 吴昊姜岷方艳储震宇李安陈欣陈英豪殷新冉谭媛媛赵莹
Owner NANJING UNIV OF TECH
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