CN117683244A - Method for separating biomass components by using ternary eutectic solvent - Google Patents

Abstract

The invention discloses a method for separating biomass components by using a ternary eutectic solvent, which comprises the following steps: first, preparing a ternary eutectic solvent: mixing quaternary ammonium salt, maleic acid and polyalcohol, heating and stirring until a uniform transparent mixture is formed, and stopping heating; secondly, mixing biomass with the ternary eutectic solvent obtained in the first step, and heating to obtain a mixed solution; and thirdly, treating the mixed solution obtained in the second step to obtain cellulose, hemicellulose and lignin respectively. The method has the advantages of high separation efficiency, low energy consumption, good environmental compatibility and recycling, has wide application prospect, and is beneficial to realizing the aims of separating all components of biomass and fully utilizing all the components.

Description

Method for separating biomass components by using ternary eutectic solvent

Technical Field

The invention belongs to the technical field of biomass component separation, and particularly relates to a method for separating biomass components by using a ternary eutectic solvent.

Background

The existing advantageous biomass component separation methods mainly comprise an organic solvent method, an ionic liquid method, a eutectic solvent method and the like. Wherein, the organic solvent method and the ionic liquid method have the defects of high cost, easy volatilization, difficult recovery and the like. The eutectic solvent is a eutectic mixture first reported by Abbott et al in 2003, formed by hydrogen bond interactions between a hydrogen bond acceptor and a hydrogen bond donor. The eutectic solvent has the advantages of easy synthesis, stability, low cost, good biocompatibility and the like, is widely focused in a plurality of fields of electrochemistry, biology, biomass energy conversion and the like, and is a novel green solvent with great potential. In the field of biomass energy conversion, related expert scholars have begun to study the separation of biomass components from eutectic solvents to prepare or produce cellulose nanocrystals, lignin, furfural and other biomass-based chemicals. For example, patent application publication No. CN105908550A discloses a method for separating lignin from eucalyptus by using benzyl triethyl ammonium chloride-lactic acid binary eutectic solvent, and separating lignin to obtain 77% lignin at 90 ℃ for 8 hours; patent application publication No. CN114108350A discloses a method for separating biomass components by using a binary eutectic solvent of a polyalcohol-organic acid, wherein 26.2% of hemicellulose and 50.7% of lignin can be obtained under the conditions of 100 ℃ and 24 hours; patent application publication No. CN115232176A discloses a method for treating bagasse with choline chloride, glycerol and oxalic acid dihydrate at 110 ℃ to obtain lignin, wherein the maximum lignin separation efficiency achieved within 6 hours is 80% and the lignin purity is 85%.

In the related research of the existing eutectic solvent method, in order to achieve higher biomass component separation efficiency, the separation reaction always needs higher reaction temperature and longer reaction time, which increases the energy consumption undoubtedly, does not accord with the biomass energy conversion concept of energy conservation and low carbon, and in addition, the eutectic solvent method also has the problems of large cellulose loss, low cellulose purity, serious lignin polycondensation and the like.

Disclosure of Invention

The invention aims to provide a method for separating biomass components by using a ternary eutectic solvent.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

the invention provides a method for separating biomass components by using a ternary eutectic solvent, which comprises the following steps:

the ternary eutectic solvent is prepared from quaternary ammonium salt, maleic acid and polyalcohol with a molar ratio of (0.5-1.5) (preferably 1:1:1);

the quaternary ammonium salt is at least one selected from benzyl triethyl ammonium chloride and choline chloride, and is preferably choline chloride;

the polyalcohol is at least one selected from ethylene glycol, 1, 2-propylene glycol and 1, 4-butanediol, and is preferably 1, 2-propylene glycol;

the biomass is lignocellulose biomass containing polymers such as cellulose, hemicellulose, lignin and the like. Preferably, the biomass is at least one selected from agriculture and forestry waste and industrial waste. More preferably, the agriculture and forestry waste is at least one selected from corn stalk, wheat stalk, corn cob, poplar wood chip and eucalyptus wood chip; the industrial waste is bagasse pith.

The biomass component is at least one of cellulose, hemicellulose and lignin;

first, preparing a ternary eutectic solvent: mixing quaternary ammonium salt, maleic acid and polyalcohol, heating and stirring for 0.5-2 h at 80-100 ℃ and stirring at 150-300 rpm until a uniform transparent mixture is formed, and cooling to room temperature for standby;

secondly, mixing the biomass with the ternary eutectic solvent obtained in the first step according to the mass ratio of 1 (10-20), heating to 100-130 ℃ and stirring for 0.5-3 h to obtain a mixed solution;

and thirdly, treating the mixed solution obtained in the second step to obtain cellulose, hemicellulose and lignin respectively.

The third step comprises the following steps:

filtering the mixed solution obtained in the second step to obtain a first liquid and a first solid, and drying the first solid residue to constant weight, wherein the first solid is cellulose; adding deionized water into the first liquid, wherein the volume ratio of the first liquid to the deionized water is 1:10, standing for precipitation, and centrifugally separating to obtain a second liquid and a second solid, and evaporating the second liquid to remove water to obtain a third liquid; the first liquid is a reaction liquid containing lignin and hemicellulose degradation products; drying a second solid to constant weight, wherein the second solid is lignin; the second liquid is a mixture containing hemicellulose degradation products, ternary eutectic solvent and water, the third liquid is distilled to obtain regenerated ternary eutectic solvent, and hemicellulose is remained in the ternary eutectic solvent in the form of degradation products.

The cellulose yield is more than 72%, and the cellulose purity is more than 60%.

The hemicellulose separation rate is above 75%.

The lignin separation rate is more than 50%.

In the separation of biomass components, the solid residue yield RY is calculated according to the formula:

wherein: RY is the solid residue yield; m is m _{Residues from the treatment of plant diseases} G, the quality of the residue; m is m _{Raw materials} Raw material mass g.

The cellulose yield:

wherein: RY is the solid residue yield, and CY is the cellulose yield; CC (CC) _{Residues from the treatment of plant diseases} The weight percent is the mass content of cellulose in the residue; CC (CC) _{Raw materials} The weight percent of the cellulose in the raw materials is calculated.

The lignin separation rate:

wherein: RY is the solid residue yield, LR is the lignin separation rate; LC (liquid Crystal) device _{Residues from the treatment of plant diseases} The weight percent of lignin in the residue is calculated; LC (liquid Crystal) device _{Raw materials} The lignin is the mass content of lignin in the raw materials, and the weight percent is given.

The hemicellulose separation ratio:

wherein: RY is the solid residue yield, HR is the hemicellulose separation rate; HC (HC) _{Residues from the treatment of plant diseases} Is the hemicellulose mass content in the residue, wt%; HC (HC) _{Raw materials} Is the mass content of hemicellulose in the raw materials, and the weight percent is given.

By adopting the technical scheme, the invention has the following advantages and beneficial effects:

the method has the advantages of high separation efficiency, low energy consumption, good environmental compatibility and recycling, has wide application prospect, and is beneficial to realizing the aims of separating all components of biomass and fully utilizing all the components.

In the method, the ternary eutectic solvent takes choline chloride as a hydrogen bond acceptor, maleic acid and polyalcohol as hydrogen bond donors, and the three components are biomass derivatives with good environmental compatibility. In the ternary system, the acidity of maleic acid provides good performance of breaking chemical bonds, while the introduction of the polyol reduces the viscosity of a solvent system, enhances the mass and heat transfer efficiency, improves the separation efficiency of biomass components, and can effectively inhibit the polycondensation of lignin in the separation process, and the lignin product has low molecular weight and polydispersity index. In addition, the ternary eutectic solvent provided by the invention has good recycling performance, the eutectic solvent can be regenerated after evaporation and water removal, and the regenerated ternary eutectic solvent still has good biomass component separation performance.

In the method, the ternary eutectic solvent is a novel ternary eutectic solvent and has the advantages of simple preparation, low cost and the like. The hydrogen bond acceptor choline chloride, the hydrogen bond donor maleic acid and the polyalcohol of the eutectic solvent are all biomass derivatives, have good biocompatibility, and realize the green chemical design of the whole process.

The method provided by the invention has the advantages that the reaction condition for separating the biomass component is mild, the reaction temperature is 100 ℃ at the minimum, the reaction time is 0.5h at the minimum, and the energy consumption of the separation process is low.

In the method, the ternary eutectic solvent can separate more than 90% of lignin and hemicellulose in biomass raw materials, and the obtained lignin has low polycondensation degree, small molecular weight and low polydispersity index. Almost no loss is caused to cellulose components in the separation process, and the maximum cellulose retention rate can reach 92.9 percent.

In the method, the ternary eutectic solvent has good recycling performance, the ternary eutectic solvent can be regenerated through rotary evaporation, the regenerated ternary eutectic solvent still has good biomass component separation performance, 91.1% of hemicellulose and 89% of lignin can be separated, and 85.3% of cellulose is obtained.

By combining the characteristics, the ternary eutectic solvent is applied to biomass component separation, has wide application prospect, and is favorable for realizing the aims of full component separation and high-value utilization of each component of biomass raw materials.

Detailed Description

In order to more clearly illustrate the present invention, the present invention will be further described with reference to preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and that this invention is not limited to the details given herein.

The analytical methods used in the following examples were as follows:

analysis of Biomass components before and after reaction

The biomass before and after the reaction is subjected to component analysis by adopting a paradigm washing method and using a crude fiber tester, and the biomass after default drying is determined to consist of neutral solubles, hemicellulose, cellulose, lignin and ash. Firstly, neutral detergent is used for extracting neutral soluble matters in the material to be detected, and the mass difference before and after the reaction is the content of the neutral soluble matters. Then, the neutral washed residue was treated with an acidic detergent to remove hemicellulose, and the mass difference before and after the reaction was the hemicellulose content. After the acid detergent treatment, the residue is hydrolyzed in 72% sulfuric acid for 3 hours, and the mass difference before and after the reaction is the cellulose content. Finally, the solid residue after 72% sulfuric acid treatment was calcined in a muffle furnace to determine ash content, and lignin content and ash content were calculated from mass difference before and after calcination.

The calculation method of the separation efficiency of the biomass components is as follows:

solid Residue Yield (RY) calculation formula:

wherein: RY is the solid residue yield; m is m _{Residues from the treatment of plant diseases} G, the quality of the residue; m is m _{Raw materials} Raw material mass g.

Cellulose yield:

wherein: RY is the solid residue yield, and CY is the cellulose yield; CC (CC) _{Residues from the treatment of plant diseases} The weight percent is the mass content of cellulose in the residue; CC (CC) _{Raw materials} The weight percent of the cellulose in the raw materials is calculated.

Lignin separation rate:

wherein: RY is the solid residue yield, LR is the lignin separation rate; LC (liquid Crystal) device _{Residues from the treatment of plant diseases} The weight percent of lignin in the residue is calculated; LC (liquid Crystal) device _{Raw materials} The lignin is the mass content of lignin in the raw materials, and the weight percent is given.

Hemicellulose separation rate:

wherein: RY is the solid residue yield, HR is the hemicellulose separation rate; HC (HC) _{Residues from the treatment of plant diseases} Is the hemicellulose mass content in the residue, wt%; HC (HC) _{Raw materials} Is the mass content of hemicellulose in the raw materials, and the weight percent is given.

Example 1

A method for separating biomass components using a ternary eutectic solvent, comprising the steps of:

first, preparing a ternary eutectic solvent: choline chloride, maleic acid and ethylene glycol are mixed according to a molar ratio of 1:1:1, heated and stirred for 1h at 90 ℃ at a stirring speed of 200rpm, heating is stopped until a uniform transparent mixture is formed, and the mixture is cooled to room temperature for standby. In the step, if the temperature is lower than 80 ℃ and the reaction cannot form a ternary eutectic solvent, maleic acid can be insoluble; if the reaction temperature is too high, for example, higher than 100 ℃, the energy consumption increases.

Secondly, mixing the bagasse pith with the particle size of 40-60 meshes with the ternary eutectic solvent obtained in the first step according to the following ratio of 1:20, heating the mixture to 100 ℃ in an oil bath at constant temperature, and stirring the mixture for 2 hours to obtain a mixed solution; in the step, the solid-liquid mass ratio is too low, which can cause the system to be sticky and influence the heat and mass transfer in the separation reaction, thereby influencing the separation efficiency; and the solid-liquid mass ratio is too high, which causes the cost to increase.

Third, the mixture is treated: filtering the mixed solution obtained in the second step to obtain a first liquid and a first solid, and drying the first solid residue to constant weight, wherein the first solid is cellulose; adding deionized water into the first liquid, wherein the volume ratio of the first liquid to the deionized water is 1:10, standing for precipitation, and centrifugally separating to obtain a second liquid and a second solid, and evaporating the second liquid to remove water to obtain a third liquid; the first liquid is a reaction liquid containing lignin and hemicellulose degradation products; drying a second solid to constant weight, wherein the second solid is lignin; the second liquid is a mixture containing hemicellulose degradation products, ternary eutectic solvent and water, the third liquid is distilled to obtain regenerated ternary eutectic solvent, and hemicellulose is remained in the ternary eutectic solvent in the form of degradation products.

Results: the yield of cellulose was 92.9%, the purity of cellulose was 71.1%, the hemicellulose separation rate was 76%, and the lignin separation rate was 50.3%.

Example 2

A method for separating biomass components using a ternary eutectic solvent, comprising the steps of:

first, preparing a ternary eutectic solvent: choline chloride, maleic acid and ethylene glycol are mixed according to a molar ratio of 1:1:1, heated and stirred for 1h at 90 ℃ at a stirring speed of 200rpm, heating is stopped until a uniform transparent mixture is formed, and the mixture is cooled to room temperature for standby.

Secondly, corn stalks with the grain size of 40-60 meshes are mixed with the ternary eutectic solvent obtained in the first step according to the following ratio of 1:20, heating the mixture to 130 ℃ in an oil bath at constant temperature, and stirring the mixture for 2 hours to obtain a mixed solution.

Third, the mixture is treated: filtering the mixed solution obtained in the second step to obtain a first liquid and a first solid, and drying the first solid residue to constant weight, wherein the first solid is cellulose; adding deionized water into the first liquid, wherein the volume ratio of the first liquid to the deionized water is 1:10, standing for precipitation, and centrifugally separating to obtain a second liquid and a second solid, and evaporating the second liquid to remove water to obtain a third liquid; the first liquid is a reaction liquid containing lignin and hemicellulose degradation products; drying a second solid to constant weight, wherein the second solid is lignin; the second liquid is a mixture containing hemicellulose degradation products, ternary eutectic solvent and water, the third liquid is distilled to obtain regenerated ternary eutectic solvent, and hemicellulose is remained in the ternary eutectic solvent in the form of degradation products.

Results: the cellulose yield was 82.27%, the cellulose purity was 69.43%, the hemicellulose separation rate was 81.00%, and the lignin separation rate was 73.3%.

Example 3

A method for separating biomass components using a ternary eutectic solvent, comprising the steps of:

first, preparing a ternary eutectic solvent: choline chloride, maleic acid and 1, 2-propylene glycol are mixed according to a molar ratio of 1:1:1, heated and stirred for 1h at 90 ℃, the stirring speed is 200rpm, heating is stopped until a uniform transparent mixture is formed, and the mixture is cooled to room temperature for standby.

Secondly, mixing the poplar wood chips with the particle size of 40-60 meshes with the ternary eutectic solvent obtained in the first step according to the following ratio of 1:20, heating to 120 ℃ in an oil bath at constant temperature, and stirring for 2 hours to obtain a mixed solution.

Third, the mixture is treated: filtering the mixed solution obtained in the second step to obtain a first liquid and a first solid, and drying the first solid residue to constant weight, wherein the first solid is cellulose; adding deionized water into the first liquid, wherein the volume ratio of the first liquid to the deionized water is 1:10, standing for precipitation, and centrifugally separating to obtain a second liquid and a second solid, and evaporating the second liquid to remove water to obtain a third liquid; the first liquid is a reaction liquid containing lignin and hemicellulose degradation products; drying a second solid to constant weight, wherein the second solid is lignin; the second liquid is a mixture containing hemicellulose degradation products, ternary eutectic solvent and water, the third liquid is distilled to obtain regenerated ternary eutectic solvent, and hemicellulose is remained in the ternary eutectic solvent in the form of degradation products.

Results: the cellulose yield was 87.3%, the cellulose purity was 62.9%, the hemicellulose separation rate was 83.7%, and the lignin separation rate was 89.1%.

Example 4

A method for separating biomass components using a ternary eutectic solvent, comprising the steps of:

first, preparing a ternary eutectic solvent: choline chloride, maleic acid and 1, 2-propylene glycol are mixed according to a molar ratio of 1:1:1, heated and stirred for 1h at 90 ℃, the stirring speed is 200rpm, heating is stopped until a uniform transparent mixture is formed, and the mixture is cooled to room temperature for standby.

Secondly, mixing the bagasse pith with the particle size of 40-60 meshes with the ternary eutectic solvent obtained in the first step according to the following ratio of 1:20, heating to 120 ℃ in an oil bath at constant temperature, and stirring for 2 hours to obtain a mixed solution.

Third, the mixture is treated: filtering the mixed solution obtained in the second step to obtain a first liquid and a first solid, and drying the first solid residue to constant weight, wherein the first solid is cellulose; adding deionized water into the first liquid, wherein the volume ratio of the first liquid to the deionized water is 1:10, standing for precipitation, and centrifugally separating to obtain a second liquid and a second solid, and evaporating the second liquid to remove water to obtain a third liquid; the first liquid is a reaction liquid containing lignin and hemicellulose degradation products; drying a second solid to constant weight, wherein the second solid is lignin; the second liquid is a mixture containing hemicellulose degradation products, ternary eutectic solvent and water, the third liquid is distilled to obtain regenerated ternary eutectic solvent, and hemicellulose is remained in the ternary eutectic solvent in the form of degradation products.

Results: the cellulose yield was 82.2%, the cellulose purity was 81.2%, the hemicellulose separation rate was 91.8%, and the lignin separation rate was 90.2%.

Example 5

A method for separating biomass components using a ternary eutectic solvent, comprising the steps of:

first, preparing a ternary eutectic solvent: choline chloride, maleic acid and 1, 2-propylene glycol are mixed according to a molar ratio of 1:1:1, heated and stirred for 1h at 90 ℃, the stirring speed is 200rpm, heating is stopped until a uniform transparent mixture is formed, and the mixture is cooled to room temperature for standby.

Secondly, mixing the bagasse pith with the particle size of 40-60 meshes with the ternary eutectic solvent obtained in the first step according to the following ratio of 1:20, heating the mixture to 130 ℃ in an oil bath at constant temperature, and stirring the mixture for 2 hours to obtain a mixed solution.

Third, the mixture is treated: filtering the mixed solution obtained in the second step to obtain a first liquid and a first solid, and drying the first solid residue to constant weight, wherein the first solid is cellulose; adding deionized water into the first liquid, wherein the volume ratio of the first liquid to the deionized water is 1:10, standing for precipitation, and centrifugally separating to obtain a second liquid and a second solid, and evaporating the second liquid to remove water to obtain a third liquid; the first liquid is a reaction liquid containing lignin and hemicellulose degradation products; drying a second solid to constant weight, wherein the second solid is lignin; the second liquid is a mixture containing hemicellulose degradation products, ternary eutectic solvent and water, the third liquid is distilled to obtain regenerated ternary eutectic solvent, and hemicellulose is remained in the ternary eutectic solvent in the form of degradation products.

Results: the cellulose yield was 82.5%, the cellulose purity was 82.5%, the hemicellulose separation rate was 91.9%, and the lignin removal rate was 92%.

Example 6

A method for separating biomass components using a ternary eutectic solvent, comprising the steps of:

first, preparing a ternary eutectic solvent: choline chloride, maleic acid and 1, 4-butanediol are mixed according to a molar ratio of 1:1:1, heated and stirred for 1h at 90 ℃ at a stirring speed of 200rpm, heating is stopped until a uniform transparent mixture is formed, and the mixture is cooled to room temperature for standby.

Secondly, mixing the bagasse pith with the particle size of 40-60 meshes with the ternary eutectic solvent obtained in the first step according to the following ratio of 1:20, heating the mixture to 100 ℃ in an oil bath at constant temperature, and stirring the mixture for 2 hours to obtain a mixed solution.

Third, the mixture is treated: filtering the mixed solution obtained in the second step to obtain a first liquid and a first solid, and drying the first solid residue to constant weight, wherein the first solid is cellulose; adding deionized water into the first liquid, wherein the volume ratio of the first liquid to the deionized water is 1:10, standing for precipitation, and centrifugally separating to obtain a second liquid and a second solid, and evaporating the second liquid to remove water to obtain a third liquid; the first liquid is a reaction liquid containing lignin and hemicellulose degradation products; drying a second solid to constant weight, wherein the second solid is lignin; the second liquid is a mixture containing hemicellulose degradation products, ternary eutectic solvent and water, the third liquid is distilled to obtain regenerated ternary eutectic solvent, and hemicellulose is remained in the ternary eutectic solvent in the form of degradation products.

Results: the cellulose yield was 82.9%, the cellulose purity was 66.0%, the hemicellulose separation rate was 87.5%, and the lignin separation rate was 89.5%.

Example 7

A method for separating biomass components using a ternary eutectic solvent, comprising the steps of:

first, preparing a ternary eutectic solvent: mixing benzyl triethyl ammonium chloride, maleic acid and 1, 2-propylene glycol according to a molar ratio of 1:1:1, heating and stirring for 1h at 90 ℃ at a stirring speed of 200rpm, stopping heating until a uniform transparent mixture is formed, and cooling to room temperature for standby.

Secondly, mixing the bagasse pith with the particle size of 40-60 meshes with the ternary eutectic solvent obtained in the first step according to the following ratio of 1:20, heating to 120 ℃ in an oil bath at constant temperature, and stirring for 2 hours to obtain a mixed solution.

Third, the mixture is treated: filtering the mixed solution obtained in the second step to obtain a first liquid and a first solid, and drying the first solid residue to constant weight, wherein the first solid is cellulose; adding deionized water into the first liquid, wherein the volume ratio of the first liquid to the deionized water is 1:10, standing for precipitation, and centrifugally separating to obtain a second liquid and a second solid, and evaporating the second liquid to remove water to obtain a third liquid; the first liquid is a reaction liquid containing lignin and hemicellulose degradation products; drying a second solid to constant weight, wherein the second solid is lignin; the second liquid is a mixture containing hemicellulose degradation products, ternary eutectic solvent and water, the third liquid is distilled to obtain regenerated ternary eutectic solvent, and hemicellulose is remained in the ternary eutectic solvent in the form of degradation products.

Results: the cellulose yield was 83.1%, the cellulose purity was 78.9%, the hemicellulose separation rate was 80.1%, and the lignin separation rate was 74.5%.

Example 8

A method for separating biomass components using a ternary eutectic solvent, comprising the steps of:

first, preparing a ternary eutectic solvent: choline chloride, maleic acid and 1, 2-propylene glycol are mixed according to a molar ratio of 1:1:1, heated and stirred for 1h at 90 ℃, the stirring speed is 200rpm, heating is stopped until a uniform transparent mixture is formed, and the mixture is cooled to room temperature for standby.

Secondly, mixing the bagasse pith with the particle size of 40-60 meshes with the ternary eutectic solvent obtained in the first step according to the following ratio of 1:20, heating the mixture to 120 ℃ in an oil bath at constant temperature, and stirring the mixture for 0.5h to obtain a mixed solution.

Third, the mixture is treated: filtering the mixed solution obtained in the second step to obtain a first liquid and a first solid, and drying the first solid residue to constant weight, wherein the first solid is cellulose; adding deionized water into the first liquid, wherein the volume ratio of the first liquid to the deionized water is 1:10, standing for precipitation, and centrifugally separating to obtain a second liquid and a second solid, and evaporating the second liquid to remove water to obtain a third liquid; the first liquid is a reaction liquid containing lignin and hemicellulose degradation products; drying a second solid to constant weight, wherein the second solid is lignin; the second liquid is a mixture containing hemicellulose degradation products, ternary eutectic solvent and water, the third liquid is distilled to obtain regenerated ternary eutectic solvent, and hemicellulose is remained in the ternary eutectic solvent in the form of degradation products.

Results: the cellulose yield was 85.2%, the cellulose purity was 75.7%, the hemicellulose separation rate was 95.2%, and the lignin separation rate was 61.9%.

Example 9

A method for separating biomass components using a ternary eutectic solvent, comprising the steps of:

first, preparing a ternary eutectic solvent: choline chloride, maleic acid and 1, 2-propylene glycol are mixed according to a molar ratio of 1:1:1, heated and stirred for 1h at 90 ℃, the stirring speed is 200rpm, heating is stopped until a uniform transparent mixture is formed, and the mixture is cooled to room temperature for standby.

Secondly, mixing the bagasse pith with the particle size of 40-60 meshes with the ternary eutectic solvent obtained in the first step according to the following ratio of 1:20, heating the mixture to 120 ℃ in an oil bath at constant temperature, and stirring the mixture for 2.5 hours to obtain a mixed solution.

Third, the mixture is treated: filtering the mixed solution obtained in the second step to obtain a first liquid and a first solid, and drying the first solid residue to constant weight, wherein the first solid is cellulose; adding deionized water into the first liquid, wherein the volume ratio of the first liquid to the deionized water is 1:10, standing for precipitation, and centrifugally separating to obtain a second liquid and a second solid, and evaporating the second liquid to remove water to obtain a third liquid; the first liquid is a reaction liquid containing lignin and hemicellulose degradation products; drying a second solid to constant weight, wherein the second solid is lignin; the second liquid is a mixture containing hemicellulose degradation products, ternary eutectic solvent and water, the third liquid is distilled to obtain regenerated ternary eutectic solvent, and hemicellulose is remained in the ternary eutectic solvent in the form of degradation products.

Results: the cellulose yield was 81.7%, the cellulose purity was 80.3%, the hemicellulose separation rate was 92.3%, and the lignin separation rate was 93.7%.

Example 10

A method for separating biomass components by recycling ternary eutectic solvents, comprising the following steps:

in the first step, the recovered and regenerated ternary eutectic solvent is used to separate the bagasse pith component.

Recovery of ternary eutectic solvents: and distilling the third liquid obtained in the embodiment 3 to obtain a regenerated ternary eutectic solvent, wherein the recovered ternary eutectic solvent is choline chloride-maleic acid-1, 2-propylene glycol, and the molar ratio is 1:1:1.

Secondly, mixing the bagasse pith with the particle size of 40-60 meshes with the ternary eutectic solvent obtained in the first step according to the following ratio of 1:20, heating to 120 ℃ by constant-temperature oil bath, and stirring for 2 hours to obtain a mixed solution, wherein the treatment step of the mixture is the same as that of the example 3.

Third, the above steps were repeated three times and the separation efficiency was measured.

Results: after three times of recycling, the yield of the cellulose is 85.7%, the purity of the cellulose is 80.1%, the separation rate of hemicellulose is 90.9%, and the separation rate of lignin is 87.8%, and the results show that the ternary eutectic solvent has good recycling performance.

Example 11

A method for separating biomass components using a ternary eutectic solvent, comprising the steps of:

first, preparing a ternary eutectic solvent: choline chloride, maleic acid and 1, 2-propylene glycol are mixed according to a molar ratio of 1:1:0.5, heated and stirred for 1h at 90 ℃ with a stirring speed of 200rpm, heating is stopped until a uniform transparent mixture is formed, and the mixture is cooled to room temperature for standby.

Secondly, mixing the bagasse pith with the particle size of 40-60 meshes with the ternary eutectic solvent obtained in the first step according to the following ratio of 1:20, heating to 120 ℃ in an oil bath at constant temperature, and stirring for 2 hours to obtain a mixed solution.

Third, the mixture is treated: filtering the mixed solution obtained in the second step to obtain a first liquid and a first solid, and drying the first solid residue to constant weight, wherein the first solid is cellulose; adding deionized water into the first liquid, wherein the volume ratio of the first liquid to the deionized water is 1:10, standing for precipitation, and centrifugally separating to obtain a second liquid and a second solid, and evaporating the second liquid to remove water to obtain a third liquid; the first liquid is a reaction liquid containing lignin and hemicellulose degradation products; drying a second solid to constant weight, wherein the second solid is lignin; the second liquid is a mixture containing hemicellulose degradation products, ternary eutectic solvent and water, the third liquid is distilled to obtain regenerated ternary eutectic solvent, and hemicellulose is remained in the ternary eutectic solvent in the form of degradation products.

Results: the cellulose yield was 74.7%, the cellulose purity was 74.6%, the hemicellulose separation rate was 93.1%, and the lignin separation rate was 79.3%.

Example 12

A method for separating biomass components using a ternary eutectic solvent, comprising the steps of:

first, preparing a ternary eutectic solvent: choline chloride, maleic acid and 1, 2-propylene glycol are mixed according to a molar ratio of 1:1:1.5, heated and stirred for 1h at 90 ℃ at a stirring speed of 200rpm, heating is stopped until a uniform transparent mixture is formed, and the mixture is cooled to room temperature for standby.

Secondly, mixing the bagasse pith with the particle size of 40-60 meshes with the ternary eutectic solvent obtained in the first step according to the following ratio of 1:20, heating to 120 ℃ in an oil bath at constant temperature, and stirring for 2 hours to obtain a mixed solution.

Third, the mixture is treated: filtering the mixed solution obtained in the second step to obtain a first liquid and a first solid, and drying the first solid residue to constant weight, wherein the first solid is cellulose; adding deionized water into the first liquid, wherein the volume ratio of the first liquid to the deionized water is 1:10, standing for precipitation, and centrifugally separating to obtain a second liquid and a second solid, and evaporating the second liquid to remove water to obtain a third liquid; the first liquid is a reaction liquid containing lignin and hemicellulose degradation products; drying a second solid to constant weight, wherein the second solid is lignin; the second liquid is a mixture containing hemicellulose degradation products, ternary eutectic solvent and water, the third liquid is distilled to obtain regenerated ternary eutectic solvent, and hemicellulose is remained in the ternary eutectic solvent in the form of degradation products.

Results: the cellulose yield was 81.2%, the cellulose purity was 78.5%, the hemicellulose separation rate was 92.4%, and the lignin separation rate was 84.1%.

Comparative example 1

Example 1 of the patent application publication No. CN105908550A is a comparative example of the present invention

1. A method for selectively separating lignin from eucalyptus comprises the following specific steps:

1) Pulverizing Eucalyptus tree trunk, sieving to obtain 40-60 mesh powder, and oven drying at 100+ -5deg.C and 0.01Mpa in vacuum drying oven;

2) Sequentially adding 1g of eucalyptus powder and 10g of DES (molar ratio of TEBA to LA 1:9) into a reaction kettle, and properly shaking to uniformly mix solid and liquid phases;

3) Starting the reaction kettle, controlling the reaction temperature to 90 ℃, and reacting for 8 hours at a fixed rotating speed of 100 rpm;

4) After the reaction is finished, cooling the reactant to room temperature, taking out a reaction product, carrying out reduced pressure suction filtration by adopting a Buchner funnel, washing residues by using ethanol, carrying out rotary evaporation on filtrate obtained by suction filtration at 70+/-5 ℃ and 0.02Mpa to obtain a concentrated solution, and recovering the ethanol;

5) Adding 50ml of deionized water into 10 g+/-1 g of the concentrated solution, and standing for 10 hours to obtain a mixed solution containing precipitate;

6) Centrifuging the mixed solution at 4000rpm/min for 15min, and then filtering and separating under reduced pressure by using a Buchner funnel;

7) Washing the solid phase obtained after solid-liquid separation by deionized water, and drying at 80+/-5 ℃ after washing to obtain a target product, namely the regenerated lignin.

8) And (3) carrying out reduced pressure distillation on the liquid phase product obtained after solid-liquid separation by a rotary evaporator under the water bath condition of 80 ℃ and 0.02Mpa to obtain concentrated solution, namely the recovered DES, and recycling.

The detection result shows that: the eucalyptus powder is subjected to DES pretreatment and subsequent extraction and separation, the obtained lignin has a yield of 77% +/-4% and a purity of 95+/-1%, and the lignin yield is the mass ratio of regenerated lignin to lignin in the eucalyptus powder. The DES is distilled and recovered by a rotary evaporator under reduced pressure under the water bath condition of 80 ℃ and 0.02Mpa, and the recovery rate is 93% +/-1%. The ethanol used for washing the residue in the experiment was recovered by distillation under reduced pressure at 70.+ -. 5 ℃ and 0.02Mpa water bath by a rotary evaporator, and the recovery rate was 99%.+ -. 1%.

Example 3 was compared with comparative example 1 and found that 89.1% lignin could be isolated from example 3 by reaction at 120℃for 2 h.

Comparative example 2

Example 1 of the patent application publication No. CN114108350A is a comparative example of the present invention

Preparing a eutectic solvent: mixing ethylene glycol and oxalic acid according to a molar ratio of 1:4, and placing the mixture in a sealed container, heating and stirring the mixture at 60 ℃ for 2 hours to obtain the uniform and transparent eutectic solvent.

Weighing 2g of air-dried and crushed corncob (40-60 meshes), mixing with the prepared eutectic solvent according to the solid-liquid weight ratio of 1:15, adding into a reaction kettle, heating at 70 ℃, and stirring for reaction for 24 hours. After the reaction is finished, adding 30mL of ethanol solution with the weight percentage concentration of 50%, fully mixing, centrifuging, and washing the obtained solid by using ethanol solution for several times to obtain the cellulose-rich component. The supernatant was concentrated to about 50mL by rotary evaporation, then 250mL deionized water was added thereto with stirring, and after precipitation overnight, the obtained solid was subjected to centrifugal separation, and after washing with water several times, lignin was obtained. Concentrating the supernatant by rotary evaporation to about 40mL, slowly dripping the concentrated supernatant into ethanol with the volume of 3 times, standing for precipitation, filtering, washing and drying to obtain hemicellulose. Concentrating the filtrate to remove ethanol and water, and recovering the eutectic solvent, wherein the recovered eutectic solvent can be reused.

The detection shows that the yield of the cellulose-rich component is 50.6 percent and the purity is 76.0 percent; the hemicellulose yield is 45.5% and the purity is 94.7%; the lignin yield is 40.8% and the purity is 96.3%; the recovery rate of the eutectic solvent is 98.0%.

The FT-IR of the ethylene glycol-oxalic acid and the single component compound used in this example showed that the 3372cm-1 of the pure ethylene glycol profile was a stretching vibration of-OH, while the absorption band at this position in the ethylene glycol-oxalic acid profile was broadened, indicating that highly associated hydrogen bonds were formed in the system. 1260cm-1 in the pure oxalic acid spectrogram is C-O stretching vibration, and the absorption peak in the ethylene glycol-oxalic acid spectrogram is subjected to red shift, which shows that O in the C-O in the oxalic acid structure participates in intermolecular interaction (hydrogen bond) with the ethylene glycol. Referring to the DSC curve of ethylene glycol-oxalic acid, the melting point of the solvent system formed was-95.4 ℃, which is significantly lower than the melting points of pure ethylene glycol (-12.9 ℃) and pure oxalic acid (101 ℃), demonstrating that a eutectic solvent was formed. The decomposition temperature of ethylene glycol-oxalic acid was above 120℃and thus the solvent system was stable at 70℃in this example.

The stretching vibration of-OH in cellulose-rich at 3395cm < -1 >, C-H stretching vibration at 2897cm < -1 > and C=O in acetyl or uronic acid on hemicellulose remained in cellulose-rich component at 1734cm < -1 > or C=O vibration of ester formed after esterification of cellulose hydroxyl groups during treatment of acid eutectic solvent, and low-intensity signals at 1603, 1512 and 1428cm < -1 > are characteristic absorption of lignin, which indicates that lignin is contained in a small amount. A wide vibration band in the range 1174-1051 cm-1 is mainly derived from the C-O-C stretching of cellulose.

3418cm-1 is stretching vibration of-OH in hemicellulose, 2930cm-1 is C-H stretching vibration, 1734cm-1 is characteristic absorption peak of acetyl in hemicellulose and C=O in uronic acid, 1640cm-1 is signal peak of hemicellulose adsorption water, 1251cm-1 is absorption peak of C-O vibration in glucuronic acid, 1046cm-1 is characteristic absorption peak of xylan, 899cm-1 is generated by C-1 group frequency vibration or ring frequency vibration, which indicates that hemicellulose glycosyl units separated by the eutectic solvent are connected by beta-glycosidic bond.

3412cm-1 is stretching vibration of-OH in lignin, 2938cm-1 is C-H stretching vibration, 1601, 1512 and 1425cm-1 are aromatic ring skeleton vibration of lignin component, 1459cm-1 is C-H deformation vibration and benzene ring vibration, and 1329cm-1 is C-O stretching vibration of syringyl benzene ring. 1169cm-1 is a characteristic absorption band of carbonyl groups in esters, and is an absorption peak specific to the structure of p-hydroxyphenyl groups in lignin of gramineae plants. 1040cm-1 is the absorption peak of guaiacyl benzene ring, and 834cm-1 is the absorption peak generated by C-H vibration on the benzene ring. Taken together, the eutectic solvent separated lignin is a typical GSH-type lignin.

Comparison of example 1 with comparative example 2 shows that example 1 reacted at 100 ℃ for 2 hours with a cellulose yield of 92.9% and a purity of 71.1%; hemicellulose separation rate is 76.0%, lignin separation rate is 50.3%.

Comparative example 3

Example 1 of the patent application publication No. CN115232176A is a comparative example of the present invention

A method for extracting lignin by using ternary eutectic solvent, comprising the following steps:

s1, crushing bagasse, sieving with a 40 mesh sieve and a 60 mesh sieve respectively, then drying for 6 hours at the temperature of 105 ℃, adding 2G of bagasse and 40G of DES (ChCl: G: OAd molar ratio is 1:1:0.5) into a reaction container, transferring the bagasse and the DES into a constant-temperature oil bath pot, setting the reaction temperature to be 110 ℃, setting the rotating speed to be 200rpm, reacting for 4 hours, and cooling to room temperature after the reaction is completed to obtain a reaction product;

s2, after reacting for 4 hours, cooling the reaction container to room temperature, adding 40mL of absolute ethyl alcohol, transferring the reaction container into a constant-temperature magnetic stirrer, setting the temperature to be 30 ℃ and the rotating speed to be 200r/min, stirring for 2 hours, cooling the reactant to room temperature, taking out the reactant for vacuum filtration, washing filter residues with the absolute ethyl alcohol, drying the filter residues at 105 ℃, carrying out rotary evaporation on the filtrate and recovering the ethanol, adding 595g of deionized water into 35g of concentrated solution after rotary evaporation at 50-65 ℃ and the pressure of 0.1Mpa, standing for 6 hours to obtain a precipitate containing lignin, carrying out reduced pressure suction filtration on the solid-liquid mixture after standing, repeatedly washing the filter residues with the deionized water, freezing and drying the filter residues, namely, regenerating lignin, carrying out rotary evaporation on the filtrate, wherein the rotary evaporation temperature is 65-75 ℃ and the pressure of 0.1Mpa, and recycling the obtained concentrated solution is DES.

The results show that: after bagasse is treated by the ternary eutectic solvent (mixed solvent of choline chloride, glycerol and oxalic acid dihydrate), the extraction rate of lignin is 74% +/-1%, wherein the purity of the extracted lignin is 80% +/-1%.

Example 4 was compared with comparative example 3 and it was found that 90.1% lignin could be isolated from example 4 by reaction at 120℃for 2 h.

The foregoing description is only illustrative of the preferred embodiment of the present invention, and is not to be construed as limiting the invention, but is to be construed as limiting the invention to any and all simple modifications, equivalent variations and adaptations of the embodiments described above, which are within the scope of the invention, may be made by those skilled in the art without departing from the scope of the invention.

Claims (8)

1. A method for separating biomass components using a ternary eutectic solvent, comprising the steps of:

the ternary eutectic solvent is prepared from quaternary ammonium salt, maleic acid and polyalcohol with the molar ratio of (0.5-1.5) being 1:1;

the quaternary ammonium salt is at least one selected from benzyl triethyl ammonium chloride and choline chloride;

the polyalcohol is at least one selected from ethylene glycol, 1, 2-propylene glycol and 1, 4-butanediol;

the biomass is lignocellulose biomass containing cellulose, hemicellulose and lignin;

the biomass component is at least one of cellulose, hemicellulose and lignin;

first, preparing a ternary eutectic solvent: mixing quaternary ammonium salt, maleic acid and polyalcohol, heating and stirring for 0.5-2 h at 80-100 ℃ and stirring at 150-300 rpm, and stopping heating until a uniform transparent mixture is formed;

secondly, mixing the biomass with the ternary eutectic solvent obtained in the first step according to the mass ratio of 1 (10-20), heating to 100-130 ℃ and stirring for 0.5-3 h to obtain a mixed solution;

and thirdly, treating the mixed solution obtained in the second step to obtain cellulose, hemicellulose and lignin respectively.

2. The method for separating biomass components using a ternary eutectic solvent according to claim 1, wherein the third step comprises the steps of:

filtering the mixed solution obtained in the second step to obtain a first liquid and a first solid, and drying the first solid residue to constant weight, wherein the first solid is cellulose; adding deionized water into the first liquid, wherein the volume ratio of the first liquid to the deionized water is 1:10, standing for precipitation, and centrifugally separating to obtain a second liquid and a second solid, and evaporating the second liquid to remove water to obtain a third liquid; the first liquid is a reaction liquid containing lignin and hemicellulose degradation products; drying a second solid to constant weight, wherein the second solid is lignin; the second liquid is a mixture containing hemicellulose degradation products, ternary eutectic solvent and water, the third liquid is distilled to obtain regenerated ternary eutectic solvent, and hemicellulose is remained in the ternary eutectic solvent in the form of degradation products.

3. The method for separating biomass components using ternary eutectic solvents according to claim 1, wherein the biomass is at least one selected from agriculture and forestry waste, industrial waste.

4. A method for separating biomass components using a ternary eutectic solvent according to claim 3, wherein the agroforestry waste is at least one selected from corn stover, wheat straw, corn cobs, poplar wood chips, eucalyptus wood chips; the industrial waste is bagasse pith.

5. The method for separating biomass components using ternary eutectic solvents according to claim 1, wherein the solid residue yield RY in separating biomass components is calculated as:

wherein: RY is the solid residue yield; m is m _{Residues from the treatment of plant diseases} G, the quality of the residue; m is m _{Raw materials} Raw material mass g.

6. The method for separating biomass components using ternary eutectic solvents according to claim 1, wherein the cellulose yield:

wherein: RY is the solid residue yield, and CY is the cellulose yield; CC (CC) _{Residues from the treatment of plant diseases} The weight percent is the mass content of cellulose in the residue; CC (CC) _{Raw materials} The weight percent of the cellulose in the raw materials is calculated.

7. The method for separating biomass components using a ternary eutectic solvent according to claim 1, wherein the lignin separation rate:

wherein: RY is the solid residue yield, LR is the lignin separation rate; LC (liquid Crystal) device _{Residues from the treatment of plant diseases} The weight percent of lignin in the residue is calculated; LC (liquid Crystal) device _{Raw materials} The lignin is the mass content of lignin in the raw materials, and the weight percent is given.

8. The method for separating biomass components using a ternary eutectic solvent according to claim 1, wherein the hemicellulose separation ratio:

wherein: RY is the solid residue yield, HR is the hemicellulose separation rate; HC (HC) _{Residues from the treatment of plant diseases} Is the hemicellulose mass content in the residue, wt%; HC (HC) _{Raw materials} Is the mass content of hemicellulose in the raw materials, and the weight percent is given.