A method for applying a eutectic solvent in biorefining

Abstract

This invention proposes a method for applying a eutectic solvent in biorefining. By designing and preparing a novel multi-site eutectic solvent, this solvent has the advantages of being green and environmentally friendly, low cost, and easy to prepare. It can gently, cleanly, and efficiently separate cellulose, lignin, and hemicellulose in one step and convert them into glucose, furfural, and nano-lignin with antioxidant properties.

Description

Technical Field

[0001] This invention belongs to the field of lignocellulose refining technology, and specifically relates to a method for gently, cleanly and efficiently separating cellulose, lignin and hemicellulose from lignocellulose, and converting them into glucose, furfural and preparing nano-lignin with antioxidant properties. Background Technology

[0002] In recent years, with the increasing demand for non-renewable resources such as oil and natural gas, the world is facing a severe resource crisis. As an abundant renewable resource on Earth, lignocellulose is crucial for solving the energy crisis; however, the existence of degradation barriers hinders its effective conversion. Lignocellulose biomass mainly consists of cellulose, hemicellulose, and lignin, and the key to its conversion lies in the clean and efficient separation of these three components.

[0003] Currently, the main separation methods include dilute acid methods, alkaline methods, organic solvent methods, and ionic liquid methods. However, these traditional methods corrode equipment, require harsh conditions such as high temperature and high pressure, or use volatile and toxic chemical reagents that pollute the environment. Furthermore, the volatility and non-recyclability of the solvents result in high product costs. Eutectic solvents, as a new type of solvent, not only have advantages such as being environmentally friendly, low-cost, and easy to prepare, but more importantly, they can effectively remove lignin and hemicellulose while better preserving cellulose, providing a prerequisite for clean and efficient separation of the three major lignins.

[0004] Chinese invention patent CN110258157A discloses a method for pretreating lignocellulose using betaine as a eutectic solvent. The lignocellulose to pretreatment solvent mass ratio is 1:30. The lignocellulose raw material and the pretreatment solvent are mixed evenly and stirred at 100 °C for 48 h to obtain pretreated solid cellulose residue with a glucose yield of 90%.

[0005] Chinese invention patent CN112899313A discloses an acidic eutectic solvent and its preparation and application in improving the enzymatic hydrolysis efficiency of pretreated straw. It is used for lignin extraction and enzymatic hydrolysis and saccharification of straw residue. The lignin removal rate of straw reaches 84%, the cellulose retention rate reaches 90%, and the enzymatic hydrolysis efficiency of straw residue reaches 89%.

[0006] Chinese invention patent CN113603889A discloses a method for pretreating lignocellulose using a Lewis base-assisted neutral eutectic solvent. The method involves heating a solid-liquid mixture for pretreatment, followed by vacuum filtration and washing with a washing liquid to obtain solid residue and liquid fraction. The enzymatic saccharification rate is 94.5%.

[0007] However, the existing technologies represented by the above patents all have the following shortcomings: the process conditions are relatively harsh, the temperature is too high or the process time is too long; in addition, the existing technologies can only separate and convert a single component in the preparation of lignocellulose, and cannot achieve efficient separation or conversion of the main components of lignocellulose for application. Summary of the Invention

[0008] This invention addresses the problem that existing technologies cannot efficiently separate and convert the main components of lignocellulose, and can only separate single components. To this end, this invention proposes a method for using a eutectic solvent in biorefining. This method uses a mild and clean eutectic solvent to efficiently separate cellulose, lignin, and hemicellulose, and converts the separated cellulose, lignin, and hemicellulose into glucose, furfural, and nano-lignin with antioxidant properties.

[0009] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0010] A method for using a eutectic solvent in biorefining includes the following steps:

[0011] Step 1: Crush one or more of the following materials into particles of 20-80 mesh using a pulverizer: bamboo, poplar, pine, and xylose residue; put the pulverized particles into a cloth bag and place it in a Soxhlet extractor; extract with a mixture of toluene and ethanol for 9 hours to obtain lignocellulose.

[0012] Step 2: Mix lignocellulose with a eutectic solvent and place the mixture in a reaction flask. Add a rotor to the reaction flask and then transfer the flask to a reaction vessel for heating and stirring. After the reaction is complete, the resulting mixture is obtained.

[0013] Step 3: Centrifuge the reaction mixture at 9000 rpm for 5 min to separate the solid and liquid. After centrifugation, the centrifuged liquid and centrifuged solid are obtained.

[0014] Lignin preparation: The centrifuged liquid was poured into a clean beaker and an appropriate amount of deionized water was added; then the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution; the centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin.

[0015] Furfural preparation: The pretreatment solution was subjected to vacuum rotary evaporation at 60 °C to remove deionized water. Then, a catalyst was added to the pretreatment solution to carry out a catalytic reaction. After the catalytic reaction was completed, furfural was obtained.

[0016] Glucose preparation: The centrifuged solid was washed with deionized water until the washing liquid was clear and transparent and the pH of the washing liquid reached neutral. The washed solid was dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose.

[0017] The eutectic solvent is prepared by the following method:

[0018] Mix the hydrogen bond acceptor and the hydrogen bond donor; react at a temperature of 30 ℃~60 ℃ and a stirring rate of 300 r / min~600 r / min until a homogeneous and transparent liquid is formed, which is the eutectic solvent; cool the eutectic solvent to room temperature and place it in a desiccator for later use.

[0019] The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:2~10;

[0020] The hydrogen bond acceptor is one or more of choline chloride, guanidine hydrochloride, betaine, tetramethylammonium chloride, and tetramethylammonium bromide; the hydrogen bond donor is one or more of formic acid, oxalic acid, lactic acid, malic acid, glycolic acid, and ethylene glycol.

[0021] The reaction time for preparing the eutectic solvent is 0.3 h to 2.0 h.

[0022] Preferably, in step one, the volume ratio of toluene to ethanol in the mixture is 2:1.

[0023] Preferably, in step two, the volume ratio of lignocellulose to eutectic solvent in the reaction flask is 1:5~15; the heating reaction conditions in the reactor are: temperature rise to 80 ℃~120 ℃, stirring speed is 400 r / min~600 r / min, and reaction time is 0.5 h~3.0 h.

[0024] Preferably, in step three, during the preparation of furfural, the catalyst for the catalytic reaction is sulfonated carbon-based, sulfuric acid, or sulfurized titanium oxide; the catalytic reaction conditions are 90 ℃~130 ℃ for 15 min~60 min; and the amount of catalyst added is 2% of the mass of the pretreatment liquid.

[0025] Preferably, in step three, the enzyme used in the enzymatic hydrolysis reaction during glucose preparation is cellulase, with a cellulase activity of 15 FPU / g.

[0026] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0027] 1. This invention provides a method for applying a eutectic solvent in biorefining. By designing and preparing a novel multi-site eutectic solvent, this solvent has the advantages of being green and environmentally friendly, low cost, and easy to prepare. It can gently, cleanly, and efficiently separate cellulose, lignin, and hemicellulose in one step in biorefining applications, and convert them into glucose, furfural, and nano-lignin with antioxidant properties.

[0028] 2. Experiments show that the enzymatic hydrolysis of cellulose in the method of this invention can achieve a glucose yield close to 100% within 48 hours, and the RSI value (free radical scavenging index (RSI) is defined as IC50) is [value missing]. 50 The reciprocal of the value can more intuitively represent the antioxidant results (a higher RSI value indicates higher antioxidant activity) up to 18%, and the yield of hemicellulose catalytically converted to furfural up to 80%. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart of this application. Detailed Implementation

[0031] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0032] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0033] like Figure 1 As shown in Example 1, the preparation of the eutectic solvent: 95.53 g of guanidine hydrochloride hydrogen bond acceptor and 186.20 g of ethylene glycol hydrogen bond donor were mixed in a beaker; the mixture was heated and stirred under sealed conditions at 60 °C and a stirring rate of 500 r / min until a homogeneous and transparent liquid was formed, which is the environmentally friendly eutectic solvent (DES); the environmentally friendly eutectic solvent was cooled to room temperature and placed in a desiccator for later use;

[0034] The application of a eutectic solvent in biorefining involves the following specific steps:

[0035] Step 1: Crush the pine wood to 40-60 mesh using a pulverizer; put the crushed pine wood into a cloth bag, place it in a Soxhlet extractor, and extract with a mixture of toluene and ethanol at a volume ratio of 2:1 for 9 hours;

[0036] Step 2: Take 3.0 g of extracted pine wood into a high-temperature pressure-resistant bottle, add a rotor, then add 45 ml of eutectic solvent, heat to 120 ℃ and react for 1 h with a stirring rate of 500 r / min; after the reaction is completed, cool to room temperature to obtain the reaction mixture.

[0037] Step 3: Transfer the reaction mixture to a 50 ml centrifuge tube and centrifuge at 9000 rpm for 5 min to separate the solid and liquid, obtaining the centrifuged liquid and the centrifuged solid.

[0038] Lignin preparation: The centrifuged liquid was poured into a clean beaker, and an appropriate amount of deionized water was added. Then, the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution. The centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin.

[0039] Furfural preparation: The pretreatment solution was vacuum rotary evaporated at 60 °C to remove deionized water. Then, 2% by weight of sulfonated carbon-based catalyst was added to the pretreatment solution as a catalyst for catalytic reaction. The catalytic reaction temperature was 120 °C and the reaction time was 30 min. After the catalytic reaction was completed, furfural was obtained.

[0040] Glucose preparation: The centrifuged solid was washed with deionized water until the washing liquid was clear and transparent and the pH of the washing liquid reached neutral. The washed solid was dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose.

[0041] Example 2, Preparation of eutectic solvent: 47.77 g of guanidine hydrochloride hydrogen bond acceptor and 186.20 g of ethylene glycol hydrogen bond donor were mixed in a beaker; the mixture was heated and stirred under sealed conditions at 60 °C and a stirring rate of 500 r / min until a homogeneous and transparent liquid was formed, which is the eutectic solvent (DES); the eutectic solvent was cooled to room temperature and placed in a desiccator for later use.

[0042] The application of a eutectic solvent in biorefining involves the following specific steps:

[0043] Step 1: Crush the pine wood to 40-60 mesh using a pulverizer; put the crushed pine wood into a cloth bag, place it in a Soxhlet extractor, and extract with a mixture of toluene and ethanol at a volume ratio of 2:1 for 9 hours;

[0044] Step 2: Take 3.0 g of extracted pine wood into a high-temperature pressure-resistant bottle, add a rotor, then add 45 ml of eutectic solvent, heat to 120 ℃ and react for 1 h with a stirring rate of 500 r / min; after the reaction is completed, cool to room temperature to obtain the reaction mixture.

[0045] Step 3: Transfer the reaction mixture to a 50 ml centrifuge tube and centrifuge at 9000 rpm for 5 min to separate the solid and liquid, obtaining the centrifuged liquid and the centrifuged solid.

[0046] Lignin preparation: The centrifuged liquid was poured into a clean beaker, and an appropriate amount of deionized water was added. Then, the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution. The centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin.

[0047] Furfural preparation: The pretreatment solution was vacuum rotary evaporated at 60 °C to remove deionized water. Then, 2% by weight of sulfonated carbon-based catalyst was added to the pretreatment solution as a catalyst for catalytic reaction. The catalytic reaction temperature was 120 °C and the reaction time was 30 min. After the catalytic reaction was completed, furfural was obtained.

[0048] Glucose preparation: The centrifuged solid was washed with deionized water until the washing liquid was clear and transparent and the pH of the washing liquid reached neutral. The washed solid was dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose.

[0049] Example 3, Preparation of eutectic solvent: 77.03 g of tetramethylammonium bromide hydrogen bond acceptor and 115.08 g of formic acid hydrogen bond donor were mixed in a beaker; the mixture was heated and stirred under sealed conditions at 60 °C and a stirring rate of 500 r / min until a homogeneous and transparent liquid was formed, which is the eutectic solvent (DES); the eutectic solvent was cooled to room temperature and placed in a desiccator for later use.

[0050] The application of a eutectic solvent in biorefining involves the following specific steps:

[0051] Step 1: Crush the poplar wood to 40-60 mesh using a pulverizer; put the crushed poplar wood into a cloth bag, place it in a Soxhlet extractor, and extract with a mixture of toluene and ethanol at a volume ratio of 2:1 for 9 hours;

[0052] Step 2: Take 3.0 g of extracted poplar wood into a high-temperature pressure-resistant bottle, add a rotor, then add 45 ml of eutectic solvent, heat to 100 ℃ and react for 1.5 h with a stirring rate of 500 r / min; after the reaction is completed, cool to room temperature to obtain the reaction mixture.

[0053] Step 3: Transfer the reaction mixture to a 50 ml centrifuge tube and centrifuge at 9000 rpm for 5 min to separate the solid and liquid, obtaining the centrifuged liquid and the centrifuged solid.

[0054] Lignin preparation: The centrifuged liquid was poured into a clean beaker, and an appropriate amount of deionized water was added. Then, the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution. The centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin.

[0055] Furfural preparation: The pretreatment solution was vacuum rotary evaporated at 60 °C to remove deionized water. Then, 2% by weight of sulfated titanium dioxide was added to the pretreatment solution as a catalyst for catalytic reaction. The catalytic reaction temperature was 120 °C and the reaction time was 30 min. After the catalytic reaction was completed, furfural was obtained.

[0056] Glucose preparation: The centrifuged solid was washed with deionized water until the washing liquid was clear and transparent and the pH of the washing liquid reached neutral. The washed solid was dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose.

[0057] Example 4, Preparation of eutectic solvent: 77.03 g of tetramethylammonium bromide hydrogen bond acceptor and 225.20 g of lactic acid hydrogen bond donor were mixed in a beaker; the mixture was heated and stirred under sealed conditions at 60 °C and a stirring rate of 500 r / min until a homogeneous and transparent liquid was formed, which is the eutectic solvent (DES); the eutectic solvent was cooled to room temperature and placed in a desiccator for later use.

[0058] The application of a eutectic solvent in biorefining involves the following specific steps:

[0059] Step 1: Crush the poplar wood to 40-60 mesh using a pulverizer; put the crushed poplar wood into a cloth bag, place it in a Soxhlet extractor, and extract with a mixture of toluene and ethanol at a volume ratio of 2:1 for 9 hours;

[0060] Step 2: Take 3.0 g of extracted poplar wood into a high-temperature pressure-resistant bottle, add a rotor, then add 45 ml of eutectic solvent, heat to 100 ℃ and react for 1.5 h with a stirring rate of 500 r / min; after the reaction is completed, cool to room temperature to obtain the reaction mixture.

[0061] Step 3: Transfer the reaction mixture to a 50 ml centrifuge tube and centrifuge at 9000 rpm for 5 min to separate the solid and liquid, obtaining the centrifuged liquid and the centrifuged solid.

[0062] Lignin preparation: The centrifuged liquid was poured into a clean beaker, and an appropriate amount of deionized water was added. Then, the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution. The centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin.

[0063] Furfural preparation: The pretreatment solution was vacuum rotary evaporated at 60 °C to remove deionized water. Then, 2% by weight of sulfated titanium dioxide was added to the pretreatment solution as a catalyst for catalytic reaction. The catalytic reaction temperature was 120 °C and the reaction time was 30 min. After the catalytic reaction was completed, furfural was obtained.

[0064] Glucose preparation: The centrifuged solid was washed with deionized water until the washing liquid was clear and transparent and the pH of the washing liquid reached neutral. The washed solid was dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose.

[0065] Example 5, Preparation of eutectic solvent: 77.03 g of tetramethylammonium bromide hydrogen bond acceptor and 270.24 g of lactic acid hydrogen bond donor were mixed in a beaker; the mixture was heated and stirred under sealed conditions at 60 °C and a stirring rate of 500 r / min until a homogeneous and transparent liquid was formed, which was the eutectic solvent (DES); the eutectic solvent was cooled to room temperature and placed in a desiccator for later use.

[0066] The application of a eutectic solvent in biorefining involves the following specific steps:

[0067] Step 1: Crush the xylose residue to 40-60 mesh using a pulverizer; put the crushed xylose residue into a cloth bag, place it in a Soxhlet extractor, and extract with a mixture of toluene and ethanol at a volume ratio of 2:1 for 9 hours;

[0068] Step 2: Take 3.0 g of the extracted xylose residue into a high-temperature pressure-resistant bottle, add a rotor, then add 45 ml of eutectic solvent, heat to 110 ℃ and react for 1 h with a stirring rate of 500 r / min; after the reaction is completed, cool to room temperature to obtain the reaction mixture.

[0069] Step 3: Transfer the reaction mixture to a 50 ml centrifuge tube and centrifuge at 9000 rpm for 5 min to separate the solid and liquid, obtaining the centrifuged liquid and the centrifuged solid.

[0070] Lignin preparation: The centrifuged liquid was poured into a clean beaker, and an appropriate amount of deionized water was added. Then, the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution. The centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin.

[0071] Furfural preparation: The pretreatment solution was vacuum rotary evaporated at 60 °C to remove deionized water. Then, 2% by weight of sulfonated carbon-based catalyst was added to the pretreatment solution as a catalyst for catalytic reaction. The catalytic reaction temperature was 120 °C and the reaction time was 30 min. After the catalytic reaction was completed, furfural was obtained.

[0072] Glucose preparation: The centrifuged solid was washed with deionized water until the washing liquid was clear and transparent and the pH of the washing liquid reached neutral. The washed solid was dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose.

[0073] Example 6, Preparation of eutectic solvent: 77.03 g of tetramethylammonium bromide hydrogen bond acceptor and 270.24 g of lactic acid hydrogen bond donor were mixed in a beaker; the mixture was heated and stirred under sealed conditions at 60 °C and a stirring rate of 500 r / min until a homogeneous and transparent liquid was formed, which is the eutectic solvent (DES); the eutectic solvent was cooled to room temperature and placed in a desiccator for later use;

[0074] The application of a eutectic solvent in biorefining involves the following specific steps:

[0075] Step 1: Crush the xylose residue to 40-60 mesh using a pulverizer; put the crushed xylose residue into a cloth bag, place it in a Soxhlet extractor, and extract with a mixture of toluene and ethanol at a volume ratio of 2:1 for 9 hours;

[0076] Step 2: Take 3.0 g of the extracted xylose residue into a high-temperature pressure-resistant bottle, add a rotor, then add 45 ml of eutectic solvent, heat to 110 ℃ and react for 1.5 h with a stirring rate of 500 r / min; after the reaction is completed, cool to room temperature to obtain the reaction mixture.

[0077] Step 3: Transfer the reaction mixture to a 50 ml centrifuge tube and centrifuge at 9000 rpm for 5 min to separate the solid and liquid, obtaining the centrifuged liquid and the centrifuged solid.

[0078] Lignin preparation: The centrifuged liquid was poured into a clean beaker, and an appropriate amount of deionized water was added. Then, the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution. The centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin.

[0079] Furfural preparation: The pretreatment solution was vacuum rotary evaporated at 60 °C to remove deionized water. Then, 2% by weight of sulfonated carbon-based catalyst was added to the pretreatment solution as a catalyst for catalytic reaction. The catalytic reaction temperature was 120 °C and the reaction time was 30 min. After the catalytic reaction was completed, furfural was obtained.

[0080] Glucose preparation: The centrifuged solid was washed with deionized water until the washing liquid was clear and transparent and the pH of the washing liquid reached neutral. The washed solid was dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose.

[0081] Example 7, Preparation of eutectic solvent: 77.03 g of tetramethylammonium bromide hydrogen bond acceptor and 270.24 g of lactic acid hydrogen bond donor were mixed in a beaker; the mixture was heated and stirred under sealed conditions at 60 °C and a stirring rate of 500 r / min until a homogeneous and transparent liquid was formed, which is the eutectic solvent (DES); the eutectic solvent was cooled to room temperature and placed in a desiccator for later use.

[0082] The application of a eutectic solvent in biorefining involves the following specific steps:

[0083] Step 1: Crush the xylose residue to 40-60 mesh using a pulverizer; put the crushed xylose residue into a cloth bag, place it in a Soxhlet extractor, and extract with a mixture of toluene and ethanol at a volume ratio of 2:1 for 9 hours;

[0084] Step 2: Take 3.0 g of the extracted xylose residue into a high-temperature pressure-resistant bottle, add a rotor, then add 45 ml of eutectic solvent, heat to 110 ℃ and react for 2 h with a stirring rate of 500 r / min; after the reaction is completed, cool to room temperature to obtain the reaction mixture.

[0085] Step 3: Transfer the reaction mixture to a 50 ml centrifuge tube and centrifuge at 9000 rpm for 5 min to separate the solid and liquid, obtaining the centrifuged liquid and the centrifuged solid.

[0086] Lignin preparation: The centrifuged liquid was poured into a clean beaker, and an appropriate amount of deionized water was added. Then, the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution. The centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin.

[0087] Furfural preparation: The pretreatment solution was vacuum rotary evaporated at 60 °C to remove deionized water. Then, 2% by weight of sulfonated carbon-based catalyst was added to the pretreatment solution as a catalyst for catalytic reaction. The catalytic reaction temperature was 120 °C and the reaction time was 30 min. After the catalytic reaction was completed, furfural was obtained.

[0088] Glucose preparation: The centrifuged solid was washed with deionized water until the washing liquid was clear and transparent and the pH of the washing liquid reached neutral. The washed solid was dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose.

[0089] Example 8, Preparation of eutectic solvent: 95.53 g of guanidine hydrochloride hydrogen bond acceptor and 276.18 g of formic acid hydrogen bond donor were mixed in a beaker; the mixture was heated and stirred under sealed conditions at 60 °C and a stirring rate of 500 r / min until a homogeneous and transparent liquid was formed, which is the eutectic solvent (DES); the eutectic solvent was cooled to room temperature and placed in a desiccator for later use.

[0090] The application of a eutectic solvent in biorefining involves the following specific steps:

[0091] Step 1: Crush the xylose residue to 40-60 mesh using a pulverizer; put the crushed xylose residue into a cloth bag, place it in a Soxhlet extractor, and extract with a mixture of toluene and ethanol at a volume ratio of 2:1 for 9 hours;

[0092] Step 2: Take 3.0 g of the extracted xylose residue into a high-temperature pressure-resistant bottle, add a rotor, then add 45 ml of eutectic solvent, heat to 100 ℃ and react for 2 h with a stirring rate of 500 r / min; after the reaction is completed, cool to room temperature to obtain the reaction mixture.

[0093] Step 3: Transfer the reaction mixture to a 50 ml centrifuge tube and centrifuge at 9000 rpm for 5 min to separate the solid and liquid, obtaining the centrifuged liquid and the centrifuged solid.

[0094] Lignin preparation: The centrifuged liquid was poured into a clean beaker, and an appropriate amount of deionized water was added. Then, the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution. The centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin.

[0095] Furfural preparation: The pretreatment solution was vacuum rotary evaporated at 60 °C to remove deionized water. Then, 2% by weight of sulfonated carbon-based catalyst was added to the pretreatment solution as a catalyst for catalytic reaction. The catalytic reaction temperature was 120 °C and the reaction time was 30 min. After the catalytic reaction was completed, furfural was obtained.

[0096] Glucose preparation: The centrifuged solid was washed with deionized water until the washing liquid was clear and transparent and the pH of the washing liquid reached neutral. The washed solid was dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose.

[0097] Example 9, Preparation of eutectic solvent: 95.53 g of guanidine tetrahydrochloride hydrogen bond acceptor and 276.18 g of formic acid hydrogen bond donor were mixed in a beaker; the mixture was heated and stirred under sealed conditions at 60 °C and a stirring rate of 500 r / min until a homogeneous and transparent liquid was formed, which is the eutectic solvent (DES); the eutectic solvent was cooled to room temperature and placed in a desiccator for later use;

[0098] The application of a eutectic solvent in biorefining involves the following specific steps:

[0099] Step 1: Crush the xylose residue to 40-60 mesh using a pulverizer; put the crushed xylose residue into a cloth bag, place it in a Soxhlet extractor, and extract with a mixture of toluene and ethanol at a volume ratio of 2:1 for 9 hours;

[0100] Step 2: Take 3.0 g of the extracted xylose residue into a high-temperature pressure-resistant bottle, add a rotor, then add 45 ml of eutectic solvent, heat to 120 ℃ and react for 2 h with a stirring rate of 500 r / min; after the reaction is completed, cool to room temperature to obtain the reaction mixture.

[0101] Step 3: Transfer the reaction mixture to a 50 ml centrifuge tube and centrifuge at 9000 rpm for 5 min to separate the solid and liquid, obtaining the centrifuged liquid and the centrifuged solid.

[0102] Lignin preparation: The centrifuged liquid was poured into a clean beaker, and an appropriate amount of deionized water was added. Then, the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution. The centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin.

[0103] Furfural preparation: The pretreatment solution was vacuum rotary evaporated at 60 °C to remove deionized water. Then, 2% by weight of sulfated titanium dioxide was added to the pretreatment solution as a catalyst for catalytic reaction. The catalytic reaction temperature was 120 °C and the reaction time was 30 min. After the catalytic reaction was completed, furfural was obtained.

[0104] Glucose preparation: The centrifuged solid was washed with deionized water until the washing liquid was clear and transparent and the pH of the washing liquid reached neutral. The washed solid was dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose.

[0105] Comparative Example 1: The preparation of lignin, furfural, and glucose using the ionic liquid method, with the following specific steps:

[0106] Step 1: Crush the xylose residue to 40-60 mesh using a pulverizer; put the crushed xylose residue into a cloth bag, place it in a Soxhlet extractor, and extract with a mixture of toluene and ethanol at a volume ratio of 2:1 for 9 hours;

[0107] Step 2: Take 3.0 g of the extracted xylose residue into a high-temperature pressure-resistant bottle, add a rotor, and then add 45 ml of ethanolamine acetate solution. Heat to 120 °C and react for 2 h with a stirring rate of 500 r / min. After the reaction is complete, cool to room temperature to obtain the reaction mixture.

[0108] Step 3: Transfer the reaction mixture to a 50 ml centrifuge tube and centrifuge at 9000 rpm for 5 min to separate the solid and liquid, obtaining the centrifuged liquid and the centrifuged solid.

[0109] Lignin preparation: The centrifuged liquid was poured into a clean beaker, and an appropriate amount of deionized water was added. Then, the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution. The centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin.

[0110] Furfural preparation: The pretreatment solution was vacuum rotary evaporated at 60 °C to remove deionized water. Then, 2% by weight of sulfated titanium dioxide was added to the pretreatment solution as a catalyst for catalytic reaction. The catalytic reaction temperature was 120 °C and the reaction time was 30 min. After the catalytic reaction was completed, furfural was obtained.

[0111] Glucose preparation: The centrifuged solid was washed with deionized water until the washing liquid was clear and transparent and the pH of the washing liquid reached neutral. The washed solid was dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose.

[0112] Comparative Example 2: The dilute acid hydrolysis method was used to prepare lignin, furfural, and glucose. The specific steps are as follows:

[0113] Step 1: Crush the bamboo to 40-60 mesh using a pulverizer; put the crushed bamboo into a cloth bag, place it in a Soxhlet extractor, and extract with a mixture of toluene and ethanol at a volume ratio of 2:1 for 9 hours.

[0114] Step 2: Take 3.0 g of extracted bamboo into a high-temperature pressure-resistant bottle, add a rotor, then add 45 ml of 1.5% H2SO4, heat to 120 ℃ and react for 2 h with a stirring rate of 500 r / min; after the reaction is completed, cool to room temperature to obtain the reaction mixture.

[0115] Step 3: Transfer the reaction mixture to a 50 ml centrifuge tube and centrifuge at 9000 rpm for 5 min to separate the solid and liquid, obtaining the centrifuged liquid and the centrifuged solid.

[0116] Lignin preparation: The centrifuged liquid was poured into a clean beaker, and an appropriate amount of deionized water was added. Then, the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution. The centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin.

[0117] Furfural preparation: The pretreatment solution was vacuum rotary evaporated at 60 °C to remove deionized water. Then, 2% by weight of sulfated titanium dioxide was added to the pretreatment solution as a catalyst for catalytic reaction. The catalytic reaction temperature was 120 °C and the reaction time was 30 min. After the catalytic reaction was completed, furfural was obtained.

[0118] Glucose preparation: The centrifuged solid was washed with deionized water until the washing liquid was clear and transparent and the pH of the washing liquid reached neutral. The washed solid was dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose.

[0119] Comparative Example 3: The organic solvent method was used to prepare lignin, furfural, and glucose. The specific steps are as follows:

[0120] Step 1: Crush the poplar wood to 40-60 mesh using a pulverizer; put the crushed poplar wood into a cloth bag, place it in a Soxhlet extractor, and extract with a mixture of toluene and ethanol at a volume ratio of 2:1 for 9 hours;

[0121] Step 2: Take 3.0 g of extracted poplar wood into a high-temperature pressure-resistant bottle, add a rotor, and then add 45 ml of organic solvent, including deionized water, acetone, formic acid and ethanol. Heat to 120 °C and react for 2 h with a stirring rate of 500 r / min. After the reaction is completed, cool to room temperature to obtain the reaction mixture.

[0122] Step 3: Transfer the reaction mixture to a 50 ml centrifuge tube and centrifuge at 9000 rpm for 5 min to separate the solid and liquid, obtaining the centrifuged liquid and the centrifuged solid.

[0123] Lignin preparation: The centrifuged liquid was poured into a clean beaker, and an appropriate amount of deionized water was added. Then, the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution. The centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin.

[0124] Furfural preparation: The pretreatment solution was vacuum rotary evaporated at 60 °C to remove deionized water. Then, 2% by weight of sulfated titanium dioxide was added to the pretreatment solution as a catalyst for catalytic reaction. The catalytic reaction temperature was 120 °C and the reaction time was 30 min. After the catalytic reaction was completed, furfural was obtained.

[0125] Glucose preparation: The centrifuged solid was washed with deionized water until the washing liquid was clear and transparent and the pH of the washing liquid reached neutral. The washed solid was dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose.

[0126] The purified DES lignin from Examples 1-9 and Comparative Examples 1-3 were subjected to DPPH antioxidant experiments. The antioxidant capacity of the lignin samples was quantitatively evaluated using the 2,2-biphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method, and their RSI values ​​were determined (the free radical scavenging index (RSI) is defined as IC50). 50 The reciprocal of the RSI value more intuitively represents the antioxidant results (a higher RSI value indicates higher antioxidant activity); the concentration of furfural in Examples 1-9 and Comparative Examples 1-3 was detected by high performance liquid chromatography, and the furfural yield was calculated; the glucose yield after enzymatic hydrolysis in Examples 1-9 and Comparative Examples 1-3 was determined; the RSI values, furfural yield, and glucose yield results of Examples 1-9 and Comparative Examples 1-3 are shown in Table 1.

[0127] Table 1. Results of RSI values, furfural yield, and glucose yield for Examples 1-9 and Comparative Examples 1-3

[0128]

[0129] By comparing Examples 1 to 9 and Comparative Examples 1 to 3, it can be found that the application method of the eutectic solvent in biorefining of this application has significantly higher RSI values ​​of lignin's antioxidant capacity, furfural yield, and glucose yield than those of Comparative Examples 1 to 3. In addition, the eutectic solvent used in the application method of the eutectic solvent in biorefining of this application has the advantages of being green and environmentally friendly, low cost, and easy to prepare. It can gently, cleanly, and efficiently separate cellulose, lignin, and hemicellulose and convert them into glucose, furfural, and nano-lignin with antioxidant properties.

[0130] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for applying a eutectic solvent in biorefining, characterized in that, Includes the following steps: Step 1: Crush one or more of the following materials—bamboo, poplar, pine, and xylose residue—into particles of 20-80 mesh using a pulverizer; place the pulverized particles into a cloth bag and put it into a Soxhlet extractor; extract with a mixture of toluene and ethanol for 9 hours to obtain lignocellulose. Step 2: Mix lignocellulose with a eutectic solvent and place the mixture in a reaction flask. Add a rotor to the reaction flask and then transfer the flask to a reaction vessel for heating and stirring. After the reaction is complete, the resulting mixture is obtained. Step 3: Centrifuge the reaction mixture at 9000 rpm for 5 min to separate the solid and liquid. After centrifugation, the centrifuged liquid and centrifuged solid are obtained. Lignin preparation: The centrifuged liquid was poured into a clean beaker, and an appropriate amount of deionized water was added. Then, the centrifuged liquid and deionized water were centrifuged at 9000 rpm for 5 min to obtain the centrifuged lignin and pretreatment solution. The centrifuged lignin was freeze-dried for 48 h to obtain purified DES lignin. Furfural preparation: The pretreatment solution was subjected to vacuum rotary evaporation at 60 °C to remove deionized water. Then, a catalyst was added to the pretreatment solution to carry out a catalytic reaction. After the catalytic reaction was completed, furfural was obtained. Glucose preparation: Wash the centrifuged solid with deionized water until the washing solution is clear and transparent and the pH of the washing solution reaches neutral. The washed solids were dried in an oven at 60 °C for 24 h, and then enzymatically hydrolyzed at 50 °C and 150 rpm for 48 h to obtain glucose. The eutectic solvent is prepared by the following method: Mix the hydrogen bond acceptor and the hydrogen bond donor; react at a temperature of 30 ℃~60 ℃ and a stirring rate of 300 r / min~600 r / min until a homogeneous and transparent liquid is formed, which is the eutectic solvent; cool the eutectic solvent to room temperature and place it in a desiccator for later use. The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:2~10; The hydrogen bond acceptor is one or more of guanidine hydrochloride and tetramethylammonium bromide; the hydrogen bond donor is one or more of formic acid, lactic acid and ethylene glycol; The reaction time for preparing the eutectic solvent is 0.3 h to 2.0 h; In step one, the volume ratio of toluene to ethanol in the mixture is 2:1; In step two, the volume ratio of lignocellulose to eutectic solvent in the reaction flask is 1:5~15; the heating conditions in the reactor are: temperature rise to 80 ℃~120 ℃, stirring speed of 400 r / min~600 r / min, and reaction time of 0.5 h~3.0 h. In step three, during furfural preparation, the catalyst for the catalytic reaction is either sulfonated carbon-based or sulfated titanium dioxide; the catalytic reaction conditions are 90 ℃~130 ℃ for 15 min~60 min; the catalyst addition amount is 2% of the mass of the pretreatment solution. In the preparation of glucose, the enzyme used in the enzymatic hydrolysis reaction is cellulase, and the cellulase activity is 15 FPU / g.

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