阅读说明：本技术 从木质纤维素原料中分离木质素和纤维素的方法 (Method for separating lignin and cellulose from lignocellulose raw material ) 是由 范国枝 程群鹏 宋光森 李建芬 杨志强 吴祯祯 于 2019-09-12 设计创作，主要内容包括：本发明公开一种从木质纤维素原料中分离木质素和纤维素的方法,涉及农业废弃资源的高值化利用技术领域。所述从木质纤维素原料中分离木质素和纤维素的方法包括以下步骤：将木质纤维素原料和混合溶剂混合,加入硫酸,于130～160℃下搅拌加热至形成反应浆液,冷却后过滤,并用所述混合溶剂洗涤滤渣,干燥得纤维素；收集滤液和洗涤液并混合,加入硫酸至硫酸浓度为0.5～3.0wt％后,于170～190℃下反应形成反应液,冷却后加水沉析,过滤并用水洗涤滤渣,干燥得木质素；其中,所述混合溶剂为有机溶剂和水的混合物。本发明旨在提供一种分离纤维素和木质素的方法,该方法可以获得高纯度的纤维素和木质素并提高木质素的得率。(The invention discloses a method for separating lignin and cellulose from a lignocellulose raw material, and relates to the technical field of high-valued utilization of agricultural waste resources. The method for separating lignin and cellulose from a lignocellulosic feedstock comprises the steps of: mixing a lignocellulose raw material and a mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form reaction slurry, cooling, filtering, washing filter residue by using the mixed solvent, and drying to obtain cellulose; collecting and mixing the filtrate and the washing liquid, adding sulfuric acid until the concentration of the sulfuric acid is 0.5-3.0 wt%, reacting at 170-190 ℃ to form reaction liquid, cooling, adding water for precipitation, filtering, washing filter residue with water, and drying to obtain lignin; wherein the mixed solvent is a mixture of an organic solvent and water. The invention aims to provide a method for separating cellulose and lignin, which can obtain high-purity cellulose and lignin and improve the yield of the lignin.)

1. A method for separating lignin and cellulose from a lignocellulosic feedstock, comprising the steps of:

Mixing a lignocellulose raw material and a mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form reaction slurry, cooling, filtering, washing filter residue by using the mixed solvent, and drying to obtain cellulose;

Collecting and mixing the filtrate and the washing liquid, adding sulfuric acid until the concentration of the sulfuric acid is 0.5-3.0 wt%, reacting at 170-190 ℃ to form reaction liquid, cooling, adding water for precipitation, filtering, washing filter residue with water, and drying to obtain lignin;

Wherein the mixed solvent is a mixture of an organic solvent and water.

2. The method for separating lignin and cellulose from a lignocellulose raw material as claimed in claim 1, wherein the step of mixing the lignocellulose raw material with a mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form a reaction slurry, cooling, filtering, washing the filter residue with the mixed solvent, and drying to obtain cellulose is carried out, wherein the lignocellulose raw material comprises any one of wheat straw, rice straw, corn stalk, sorghum straw, rape straw, bamboo dust, wood dust, bagasse, rice hull, peanut shell, walnut shell and corn cob.

3. The method for separating lignin and cellulose from a lignocellulosic feedstock according to claim 1, wherein said organic solvent is ethanol or 1, 4-dioxane.

4. The method for separating lignin and cellulose from a lignocellulosic feedstock as claimed in claim 1, wherein the volume ratio of the organic solvent to water in the mixed solvent is (9-0.5): 1.

5. the method for separating lignin and cellulose from a lignocellulose raw material as recited in claim 1, wherein in the step of mixing the lignocellulose raw material with a mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form a reaction slurry, cooling, filtering, washing the filter residue with the mixed solvent, and drying to obtain cellulose, the weight-to-volume ratio of the lignocellulose raw material to the mixed solvent is 1 (4-20).

6. The method for separating lignin and cellulose from a lignocellulosic feedstock as claimed in claim 1, wherein the step of mixing the lignocellulosic feedstock with a mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form a reaction slurry, cooling, filtering, washing the filter residue with the mixed solvent, and drying to obtain cellulose, the amount of added sulfuric acid is that the sulfuric acid is added until the concentration of sulfuric acid is 0.3-1.5 wt%.

7. The method for separating lignin and cellulose from a lignocellulosic feedstock as claimed in claim 1, wherein the step of mixing the lignocellulosic feedstock with the mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form a reaction slurry, cooling, filtering, washing the filter residue with the mixed solvent, and drying to obtain cellulose, the heating time is 4-12 hours.

8. The method for separating lignin and cellulose from a lignocellulose raw material as recited in claim 1, wherein the step of collecting and mixing the filtrate and the washing solution, adding sulfuric acid until the concentration of sulfuric acid is 0.5-3.0 wt%, reacting at 170-190 ℃ to form a reaction solution, cooling, adding water for precipitation, filtering, washing the filter residue with water, and drying to obtain lignin, wherein the reaction time is 1-6 hours.

9. the method for separating lignin and cellulose from a lignocellulose raw material as recited in claim 1, wherein the filtrate and the washing liquid are collected and mixed, sulfuric acid is added until the sulfuric acid concentration is 0.5-3.0 wt%, the mixture is reacted at 170-190 ℃ to form a reaction liquid, water is added for precipitation after cooling, the filtration and the filter residue washing are carried out, and the lignin is obtained by drying, wherein the volume ratio of the added water to the reaction liquid is (5-1): 1 during the precipitation of the water.

10. The method for separating lignin and cellulose from a lignocellulosic feedstock as claimed in claim 1, wherein the method comprises the steps of mixing the lignocellulosic feedstock with a mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form a reaction slurry, cooling, filtering, washing the filter residue with the mixed solvent, and drying to obtain cellulose, and further comprises: sequentially washing, drying, crushing and sieving the lignocellulose raw material, and extracting the lignocellulose raw material by using a toluene-ethanol mixed solvent.

Technical Field

The invention relates to the technical field of resources and environment, in particular to high-value utilization of agricultural waste resources, and particularly relates to a method for separating lignin and cellulose from a lignocellulose raw material.

Background

With the rapid consumption of fossil fuels such as coal and petroleum and the increasing awareness of environmental protection, the search for renewable clean resources has become a focus of general attention of all countries in the world. The biomass resources have become a research hotspot due to the advantages of rich sources, high regeneration speed, low greenhouse gas emission and the like. The lignocellulose biomass raw material is the most abundant carbon-containing biomass resource in nature, mainly comprises three components of cellulose (22-42%), hemicellulose (12-27%) and lignin (11-30%), and the components can be converted into energy fuels and high-added-value chemicals and can also be used for obtaining various renewable bio-based materials through biological, physical or chemical methods.

among the three main components of biomass, cellulose has the simplest structure and the highest content, is polymerized by glucose units, can be directly hydrolyzed into D-glucose or converted into modified cellulose, and then further converted into other fine chemicals, and can be used for preparing chemical products with wide application, such as glucose, microcrystalline cellulose, nano-cellulose, cellulose acetate, 5-hydroxymethylfurfural, levulinic acid and the like; lignin is the second most abundant natural high molecular substance in the world and is also the only non-fossil resource providing renewable aryl compounds in nature, and is considered as a potential raw material for synthesizing aromatic compounds, and is expected to be widely applied to the aspects of oilfield chemicals, synthetic resins, rubber reinforcing agents, vanillin, building material auxiliaries and the like.

However, the structure of the lignocellulose biomass raw material is compact and complex, so that direct conversion and utilization are difficult, the product composition is complex, the post-treatment is complicated, the efficiency is extremely low, and the resource is greatly wasted. Efficient separation of the major components of lignocellulosic feedstocks is an important prerequisite for their full utilization. Because the lignocellulose raw material has strong biological degradation resistance, the separation difficulty is high, the separation difficulty becomes a technical bottleneck for restricting the resource utilization of the lignocellulose, and the separation of the components of the lignocellulose raw material becomes a key point in the research field of domestic and foreign biomass resources.

Common methods for separating the components of lignocellulosic feedstocks are acid-base and organic solvent processes. Wherein, the cellulose with higher purity can be obtained by an acid-base method, but alkali has certain destructiveness to the structure of lignin, so that the yield of the lignin and the quality of the product are lower; although the organic solvent method can simultaneously separate three main components of lignocellulose, the current research usually focuses on separating one of the components, mainly focuses on extracting cellulose or lignin, and is difficult to simultaneously obtain high-purity cellulose and lignin. Therefore, there is a need for a method for efficiently separating cellulose and lignin.

Disclosure of Invention

The invention mainly aims to provide a method for separating lignin and cellulose from a lignocellulose raw material, and aims to provide a method for separating cellulose and lignin, which can obtain high-purity cellulose and lignin and improve the yield of the lignin.

To achieve the above object, the present invention provides a method for separating lignin and cellulose from a lignocellulosic feedstock, the method for separating lignin and cellulose from a lignocellulosic feedstock comprising the steps of:

Mixing a lignocellulose raw material and a mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form reaction slurry, cooling, filtering, washing filter residue by using the mixed solvent, and drying to obtain cellulose;

Collecting and mixing the filtrate and the washing liquid, adding sulfuric acid until the concentration of the sulfuric acid is 0.5-3.0 wt%, reacting at 170-190 ℃ to form reaction liquid, cooling, adding water for precipitation, filtering, washing filter residue with water, and drying to obtain lignin;

wherein the mixed solvent is a mixture of an organic solvent and water.

Optionally, in the step of mixing the lignocellulose raw material with the mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form reaction slurry, cooling and filtering, washing the filter residue with the mixed solvent, and drying to obtain the cellulose, the lignocellulose raw material comprises any one of wheat straw, rice straw, corn stalk, sorghum straw, rape straw, bamboo dust, wood dust, bagasse, rice hull, peanut shell, walnut shell, and corn cob.

Optionally, the organic solvent is ethanol or 1, 4-dioxane.

Optionally, in the mixed solvent, the volume ratio of the organic solvent to the water is (9-0.5): 1.

Optionally, in the step of mixing the lignocellulose raw material and the mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form reaction slurry, cooling and filtering, washing filter residue with the mixed solvent, and drying to obtain cellulose, the weight-volume ratio of the lignocellulose raw material to the mixed solvent is 1 (4-20).

Optionally, in the step of mixing the lignocellulose raw material with the mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form reaction slurry, cooling and filtering, washing the filter residue with the mixed solvent, and drying to obtain the cellulose, the adding amount of the sulfuric acid is that the sulfuric acid is added until the concentration of the sulfuric acid is 0.3-1.5 wt%.

Optionally, in the step of mixing the lignocellulose raw material with the mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form reaction slurry, cooling and filtering, washing filter residue with the mixed solvent, and drying to obtain the cellulose, the heating time is 4-12 hours.

Optionally, the filtrate and the washing liquid are collected and mixed, sulfuric acid is added until the sulfuric acid concentration is 0.5-3.0 wt%, the mixture reacts at 170-190 ℃ to form a reaction liquid, water is added for precipitation after cooling, the filter residue is filtered and washed with water, and the lignin is obtained after drying, wherein the reaction time is 1-6 hours.

optionally, the filtrate and the washing liquid are collected and mixed, sulfuric acid is added until the sulfuric acid concentration is 0.5-3.0 wt%, the mixture reacts at 170-190 ℃ to form a reaction liquid, water is added for precipitation after cooling, the filter residue is filtered and washed with water, and the lignin is obtained by drying, wherein in the step of adding water for precipitation, the volume ratio of the added water to the reaction liquid is (5-1): 1.

Optionally, before the step of mixing the lignocellulose raw material with the mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form reaction slurry, cooling and filtering, washing the filter residue with the mixed solvent, and drying to obtain cellulose, the method further comprises: sequentially washing, drying, crushing and sieving the lignocellulose raw material, and extracting the lignocellulose raw material by using a toluene-ethanol mixed solvent.

According to the technical scheme provided by the invention, the lignocellulose raw material is placed in an acidic environment of an organic solvent-water mixed solvent, and is heated at 130-160 ℃ to separate cellulose from hemicellulose and lignin, the cellulose is retained in filter residue, and the hemicellulose and the lignin enter into filtrate, so that high-purity cellulose can be obtained through simple solid-liquid separation; by supplementing sulfuric acid and increasing the reaction temperature, a proper acid-base and temperature environment is created, so that part of lignin which is not damaged by the action force between the lignin and hemicellulose originally can be precipitated, and the yield of the lignin is increased. The method only needs two stages of operation steps, has simple flow and easy achievement of process conditions, not only effectively improves the yield of the lignin, but also can separate and obtain the high-purity lignin and cellulose, is easier for industrialized popularization, and improves the utilization rate and the value of agricultural waste resources.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other related drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a flow diagram of an embodiment of a method of separating lignin and cellulose from a lignocellulosic feedstock in accordance with the present invention.

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments.

It should be noted that those whose specific conditions are not specified in the examples were performed according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Common methods for separating the components of lignocellulosic feedstocks are acid-base and organic solvent processes. Wherein, the cellulose with higher purity can be obtained by an acid-base method, but alkali has certain destructiveness to the structure of lignin, so that the yield of the lignin and the quality of the product are lower; although the organic solvent method can simultaneously separate three main components of lignocellulose, the current research usually focuses on separating one of the components, mainly focuses on extracting cellulose or lignin, and is difficult to simultaneously obtain high-purity cellulose and lignin. Therefore, there is a need for a method for efficiently separating cellulose and lignin.

In view of this, the present invention proposes a method for separating lignin and cellulose from lignocellulosic feedstocks, which allows obtaining cellulose and lignin of high purity. FIG. 1 is an embodiment of the present invention of a method for separating lignin and cellulose from a lignocellulosic feedstock.

Referring to fig. 1, the method of the present embodiment includes the following steps:

And step S10, mixing the lignocellulose raw material with the mixed solvent, adding sulfuric acid, stirring and heating at 130-160 ℃ to form reaction slurry, cooling, filtering, washing filter residues with the mixed solvent, and drying to obtain cellulose.

In the embodiment, the lignocellulose raw material is placed in an acidic environment of an organic solvent-water mixed solvent, the low-temperature heating is utilized to separate the cellulose from the hemicellulose and the lignin, the cellulose is retained in filter residues, and the hemicellulose and the lignin enter the filtrate, so that the high-purity cellulose can be obtained through simple solid-liquid separation.

the lignocellulosic raw material may be any lignocellulosic biomass raw material, such as various plant straws, fruit shells, bamboo scraps, wood chips, bagasse, corn cobs and the like, which are common agricultural wastes. According to the invention, the lignocellulose raw material is treated, so that high-purity cellulose and lignin are separated, and the utilization value and the utilization rate of agricultural wastes are improved. In this embodiment, the lignocellulosic raw material includes, but is not limited to, any one of wheat straw, rice straw, corn straw, sorghum straw, rape straw, bamboo sawdust, wood chips, bagasse, rice hull, peanut shell, walnut shell, and corn cob, and preferably wheat straw, rice straw, corn stalk, bagasse, or rice hull.

The mixed solvent is a mixture of an organic solvent and water. In an acid solution, the hemicellulose is hydrolyzed, so that the interaction force among the cellulose, the hemicellulose and the lignin is broken, the hemicellulose, the hydrolysis products of the hemicellulose and the lignin are dissolved, the cellulose is not dissolved and is left in a solid phase, and the purposes of component separation and purification are achieved. Specifically, the organic solvent may include, but is not limited to, any one of methanol, ethanol, 1, 4-dioxane, N-methylpyrrolidone, and N, N-dimethylformamide, but in the present embodiment, the organic solvent is preferably ethanol or 1, 4-dioxane in view of product purity and yield. Further, in the mixed solvent, the volume ratio of the organic solvent to the water is (9-0.5): 1, and preferably 2: 1.

It should be noted that the mixed solvent described below is a mixture of an organic solvent and water, and will not be described in detail later.

In order to ensure sufficient separation of the components in the raw material, in step S10, the weight-to-volume ratio of the lignocellulosic raw material to the mixed solvent is 1 (4-20) (g: mL), preferably 1: 15.

In addition, the acid environment can promote the hydrolysis of hemicellulose, but the addition amount of sulfuric acid is moderate, otherwise the hydrolysis or carbonization of the hemicellulose can be caused, and the yield and the purity of the cellulose are further reduced, in the embodiment, the addition amount of the sulfuric acid is that the sulfuric acid is added until the concentration of the sulfuric acid is 0.3-1.5 wt%, preferably 1.0 wt%. And heating and stirring at 130-160 ℃, wherein the heating time is 4-12 h, preferably 5 h.

And S20, collecting the filtrate and the washing liquid, mixing, adding sulfuric acid until the sulfuric acid concentration is 0.5-3.0 wt%, reacting at 170-190 ℃ to form a reaction liquid, cooling, adding water for precipitation, filtering, washing the filter residue with water, and drying to obtain the lignin.

In the embodiment, the reaction temperature is increased by supplementing sulfuric acid to create a proper acid-base and temperature environment, so that part of lignin which is not damaged by the action force between the lignin and hemicellulose originally can be precipitated, and the yield of the lignin is increased.

After the cellulose is separated, the filtrate is directly added with water for precipitation, although the lignin with higher purity can be obtained, the yield of the lignin is lower, mostly about 5-13.5%, and the inventor finds that after a certain amount of sulfuric acid is added to enable the mass concentration of the sulfuric acid in the mixed solution to reach 0.5-3.0 wt%, the yield of the lignin is obviously improved, even can reach about 18%; meanwhile, the reaction temperature is properly increased, and the lignin yield can be effectively increased after the temperature is controlled to be 170-190 ℃. In addition, considering that the surface and the pore channels of the filter residue obtained in the step S10 still have residual solution of hemicellulose, hydrolysate thereof and lignin, in this embodiment, the washing solution after washing the filter residue is combined with the filtrate generated during filtration, and then sulfuric acid is supplemented until the concentration of sulfuric acid is 0.5-3.0 wt%, and the reaction solution is formed by reaction at 170-190 ℃, so that part of lignin which is not damaged by the interaction force between the hemicellulose originally can be precipitated, and the yield of lignin is improved. And multiple experiments show that after the sulfuric acid is supplemented, the mass concentration of the sulfuric acid in the mixed solution reaches 1.5 wt%, and the yield is improved most obviously when the reaction temperature is 180 ℃. In addition, the heating reaction time in the embodiment is 1-6 h, preferably 2.5 h.

In addition, when water is added for precipitation, the volume ratio of the added water to the reaction solution may be (5-1: 1), and is preferably 3: 1.

compared with the prior art, the method has the advantages of simple operation, high efficiency, good effect, easy industrialized popularization and improvement of the utilization rate and value of agricultural waste resources.

In addition, to further increase the yield of cellulose and lignin, the lignocellulosic feedstock may be pretreated prior to step S10:

And step S100, sequentially washing, drying, crushing and screening the lignocellulose raw material, and then extracting the lignocellulose raw material by using a toluene-ethanol mixed solvent.

In the embodiment, before the lignocellulose raw material is subjected to separation operation, the lignocellulose raw material is pretreated, and is crushed into powder so that the powder can be fully mixed with the mixed solvent and sulfuric acid, and meanwhile, the toluene-ethanol mixed solvent is adopted for extraction treatment, so that part of soluble impurities contained in the raw material are removed, the purity of cellulose and lignin in the raw material is improved, and the separation efficiency and the product purity are further improved.

Further, in this embodiment, step S100 may be implemented by: washing a lignocellulose raw material, drying, pulverizing into powder, sieving, and adding a toluene-ethanol (2:1, v/v) mixed solvent, wherein the weight-volume ratio of the raw material to the mixed solvent can be 1:15(g: mL). Then extracting for 24h at 100 ℃ to obtain an extract, and drying in vacuum at 80 ℃ to obtain the pretreated lignocellulose raw material for later use in step S10.

The technical solutions of the present invention are further described in detail below with reference to specific examples and drawings, it should be understood that the following examples are merely illustrative of the present invention and are not intended to limit the present invention.