Method for pretreating lignocellulose by freeze-thaw cycle coupling and application thereof

Abstract

The present application relates to a kind of freeze-thaw cycle coupling pretreatment green disassembly lignocellulose method and its application.The present application is by using water or metal salt ion solution as medium to lignocellulose raw material is carried out freeze-thaw cycle pretreatment, coupling appropriate pretreatment method is carried out green disassembly, and the obtained solid material is carried out enzymolysis to complete the disassembly and conversion process of lignocellulose.The present application can effectively break the anti-degradation barrier of lignocellulose, reduce the pretreatment intensity, improve the utilization rate of component separation extraction, reduce the inhibitor generated by pretreatment, to promote enzymolysis and subsequent conversion and utilization, and the method can utilize regional cold resource advantage, with the advantages of simple process, energy saving, water saving, environmental protection, high sugar concentration and low cost.

Description

Technical Field

[0001] This invention belongs to the field of lignocellulose treatment technology, and relates to a method for green dismantling of lignocellulose through freeze-thaw cycle coupling pretreatment and its application. Background Technology

[0002] Lignocellulose, as an important renewable energy source, is characterized by its large reserves and clean, renewable nature, making it a crucial renewable resource. Lignocellulose is primarily composed of supramolecular structures such as cellulose, hemicellulose, and lignin. Compared to fossil resources like coal and petroleum, its structure is more complex, making efficient conversion and utilization difficult. Current technologies relying on single technologies or single-component utilization to convert lignocellulose into bio-based products are unlikely to succeed. For some products, this conversion method increases energy consumption and is not economically viable for raw material utilization. Furthermore, the conversion process becomes more complex and prone to high energy consumption and pollution depending on the type of lignocellulose raw material. Therefore, achieving economical conversion and high-value utilization of lignocellulose is both the key and the challenge for its industrial development.

[0003] Lignocellulose component resolution refers to the process of disrupting the highly crystalline structure of lignocellulose through specific techniques, making it easier for further degradation and utilization. This generally refers to pretreatment techniques. Pretreatment can break down the lignin and hemicellulose encapsulation of cellulose, removing lignin, degrading hemicellulose, and altering the crystal structure of cellulose. This increases the accessible internal surface area and looseness of cellulose, thus increasing the reaction area between enzymes and substrates, significantly improving subsequent enzymatic hydrolysis efficiency and sugar yield. Pretreatment is the entry point for high-value utilization of lignocellulose components and the foundation for component research. In the process of lignocellulose conversion and utilization, pretreatment is one of the most costly unit treatment steps. Therefore, addressing the problems of high cost, high energy consumption, low efficiency, and heavy pollution has become the dominant direction of pretreatment research.

[0004] CN110747236A discloses a pretreatment method for lignocellulose. The pretreatment method for lignocellulose includes the following steps: mechanically crushing lignocellulose, drying it at room temperature (20-25°C) for at least 24 hours, sieving it to obtain lignocellulose particles with a particle size of 0.18-0.85 mm, placing the lignocellulose particles in an inorganic salt solution with pH < 2.5 and keeping it at 100-160°C for 0.5-3 hours to obtain a solid-liquid mixture, separating the solid-liquid mixture to obtain a solid, washing the solid until neutral, and drying it for at least 24 hours to obtain pretreated lignocellulose.

[0005] CN107058424A discloses a method for pretreating lignocellulose. The method uses lignocellulose as raw material, which is crushed, ground, and sieved to form a suspension with a specific solid-liquid ratio. The suspension is then pretreated using dielectric barrier discharge low-temperature plasma technology. Solid-liquid separation is performed on the pretreated suspension, and the collected solid residue is washed with water until neutral, yielding the pretreated lignocellulose product. This dielectric barrier discharge low-temperature plasma pretreatment technology can effectively reduce the crystallinity and degree of polymerization of lignocellulose, significantly disrupting the hydrogen bond network structure of cellulose, thereby significantly improving the hydrolysis efficiency of lignocellulose and increasing its economic value.

[0006] Although the above methods are all pretreatment methods for lignocellulose, they are all traditional chemical pretreatment methods that involve mechanically crushing lignocellulose. However, the lignocellulose pretreatment process is a complex system involving non-uniform multi-scale structural interactions. Therefore, the above methods have shortcomings such as high intensity and energy consumption, and high inhibitory substances, which restrict the development of lignocellulose biorefining.

[0007] The inherent stubbornness of lignocellulose limits its comprehensive conversion and utilization. Therefore, it is necessary to research and develop various pretreatment technologies to overcome this limitation. Efficient pretreatment technologies can not only greatly improve the enzymatic hydrolysis effect of lignocellulose raw materials, but also facilitate the recycling of lignin and hemicellulose. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a method for green decomposition of lignocellulose through freeze-thaw cycle coupling pretreatment and its application.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for green dismantling of lignocellulose through freeze-thaw cycle coupling pretreatment. The method includes: rehydrating lignocellulose in a liquid medium, then performing freeze-thaw cycle treatment, followed by coupling pretreatment process to dismantle the lignocellulose, thereby obtaining the desired product.

[0011] Since the skeletal structure of lignocellulose is a typical porous material, the dense structure of lignocellulose can be disrupted by a freeze-thaw cycle mechanism. The method of this invention, by subjecting lignocellulose to freeze-thaw cycles before pretreatment, not only effectively breaks down the degradation barrier of lignocellulose and reduces the intensity of raw material pretreatment, but also improves the separation, extraction, and utilization rate of lignocellulose raw material components and reduces inhibitors generated during pretreatment, thereby promoting enzymatic hydrolysis and subsequent conversion efficiency. Furthermore, the freeze-thaw cycle process of this invention does not require high-temperature and high-pressure equipment, resulting in low equipment investment and further reducing process costs.

[0012] Preferably, the raw materials for the lignocellulose include any one or a combination of at least two of bagasse, corn cob, wood, bamboo or rattan.

[0013] Preferably, the wood includes any one or a combination of at least two of eucalyptus, poplar, pine, fir, or locust.

[0014] The green dismantling method involved in this invention has a wide range of applications and can be applied to the dismantling of lignocellulose, including bagasse, corn cobs, wood, bamboo, and rattan.

[0015] Preferably, the solid-liquid volume ratio of the lignocellulose to the liquid medium is 1:1 to 1:5, for example, it can be 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, etc. Other specific values ​​within the above range can be selected, and will not be elaborated here.

[0016] Preferably, the rehydration treatment time is 1-6 hours, for example, it can be 1.5 hours, 2 hours, 3 hours, 4 hours, 5 hours, 5.5 hours, etc. Other specific values ​​within the above range can be selected, and will not be elaborated here.

[0017] Preferably, the liquid medium comprises water and / or a metal salt solution.

[0018] Preferably, the metal salt solution includes any one or a combination of at least two of the following: ferric chloride solution, ferric sulfate solution, zinc chloride solution, zinc sulfate solution, sodium chloride solution, or sodium sulfate solution.

[0019] In this invention, water or a solution of common metal salt ions with a low concentration is used as the liquid medium for the rehydration treatment of lignocellulose. This allows the porous structure of lignocellulose to reach saturation more quickly, which is more conducive to freeze-thaw cycle treatment. Moreover, the medium used is inexpensive and recyclable, further reducing the cost of the lignocellulose pretreatment process.

[0020] Preferably, the concentration of the metal salt solution is 5%-20%, for example, it can be 7%, 10%, 12%, 15%, 17%, 19%, etc. Other specific values ​​within the above range can be selected, and will not be elaborated here.

[0021] In this invention, the concentration of metal salts during rehydration treatment is limited to 5%-20%. Within this range, the greater the stratification pressure generated during freeze-thaw cycles, the faster the ion diffusion, which has a certain destructive effect on the structure of lignocellulose, thus resulting in a better disintegration effect of components. When the concentration of metal salts is below 5%, the increase in stratification pressure is not significant, and the disintegration effect of lignocellulose after pretreatment is poor. When the concentration of metal salts is above 20%, the corrosion of the lignocellulose structure is severe, the loss of components is large, and raw materials are wasted.

[0022] Preferably, the freeze-thaw cycle includes freezing at -50 to -20°C (e.g., -45°C, -40°C, -35°C, -30°C, -25°C, etc.) and then thawing at 20-40°C (e.g., 25°C, 28°C, 30°C, 33°C, 35°C, 38°C, etc.), and the above steps are repeated.

[0023] Preferably, the freezing time is 2-8 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, etc.

[0024] Preferably, the thawing time is 4-12 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, etc.

[0025] Preferably, the number of cycles is 10-20 times, for example, 11 times, 13 times, 15 times, 17 times, 19 times, etc.

[0026] In this invention, selecting 10-20 freeze-thaw cycles ensures that the number of microcracks in the lignocellulose structure increases, the number of ion channels increases, and the diffusion coefficient increases after freeze-thaw cycles, thereby further enhancing the component disassembly effect. When the number of cycles is too small, the lignocellulose structure does not change much after freeze-thaw cycles, which affects the disassembly effect after pretreatment. When the number of cycles is too large, the increase in disassembly effect is not significant.

[0027] Preferably, during the freeze-thaw cycle treatment, a rehydration treatment is performed every 2-4 cycles (e.g., 2, 3, 4, etc.).

[0028] Preferably, the rehydration treatment time is 0.5-1 hour, for example, it can be 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours, etc.

[0029] Preferably, the pretreatment process includes any one or a combination of at least two of steam explosion, hydrothermal treatment, acid hydrolysis, alkaline hydrolysis, or white rot fungal biodegradation.

[0030] In this invention, before the lignocellulose undergoes pretreatment, i.e. after the raw material has undergone freeze-thaw cycle treatment, there is no need to wash the raw material, which greatly saves water resources and energy consumption, making the method characterized by high yield and no pollution.

[0031] Other specific point values ​​within the range of the above values ​​can be selected, and will not be elaborated on here.

[0032] Secondly, the present invention provides an application of the method for green decomposition of lignocellulose as described in the first aspect, using freeze-thaw cycle coupling pretreatment, in the degradation treatment of lignocellulose.

[0033] Thirdly, the present invention provides a lignocellulose enzymatic hydrolysis product, which is obtained by further enzymatic hydrolysis of lignocellulose obtained by the green dismantling of lignocellulose through the freeze-thaw cycle coupling pretreatment method described in the first aspect.

[0034] In this invention, the lignocellulose obtained by freeze-thaw cycle coupling pretreatment is enzymatically hydrolyzed, which can significantly reduce the amount of cellulase used, and effectively improve the hydrolysis efficiency, increase the sugar concentration, and reduce the cost of hydrolysis and subsequent fermentation.

[0035] Preferably, the solid content of the disintegration product in the enzymatic hydrolysis system is 15-60%, for example, it can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, etc.

[0036] Preferably, the amount of enzyme used in the enzymatic hydrolysis process is 5-20 FPU / g DM, for example, it can be 6 FPU / g DM, 8 FPU / g DM, 10 FPU / g DM, 12 FPU / g DM, 15 FPU / g DM, 17 FPU / g DM, 19 FPU / g DM, etc.

[0037] Preferably, the temperature of the enzymatic hydrolysis process is 45-55℃ (e.g., 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃, etc.), and the time is 24-96h (e.g., 30h, 36h, 42h, 48h, 54h, 60h, 72h, 84h, 90h, etc.).

[0038] Other specific point values ​​within the range of the above values ​​can be selected, and will not be elaborated on here.

[0039] Fourthly, the present invention provides the application of the lignocellulose enzymatic hydrolysis product as described in the third aspect in the preparation of bioethanol.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. Water or a solution of common metal salt ions with a low concentration is used as the freeze-thaw cycle medium. The medium used is inexpensive and can be recycled and reused.

[0042] 2. The method used can effectively reduce the degradation barrier of lignocellulose, thereby reducing the pretreatment intensity, reducing the generation of inhibitors, reducing energy consumption and saving costs.

[0043] 3. The raw materials do not need to be washed with water after the freeze-thaw cycle pretreatment, saving operating units and water consumption, thereby reducing costs and being environmentally friendly.

[0044] 4. The freeze-thaw cycle coupling pretreatment method reduces the amount of cellulase in the lignocellulose during enzymatic hydrolysis, effectively improves the hydrolysis efficiency and sugar concentration, and takes into account downstream processes, further reducing energy consumption and costs. Moreover, the reaction conditions are mild, the equipment requirements are low, and it is easy to carry out industrial production. Detailed Implementation

[0045] To further illustrate the technical means and effects of the present invention, the following describes the technical solution of the present invention in conjunction with preferred embodiments of the present invention. However, the present invention is not limited to the scope of the embodiments.

[0046] Example 1

[0047] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products, the method being as follows:

[0048] 1) The poplar wood chips are cut into 3cm×3cm×2cm chips;

[0049] 2) Mix the raw materials from step 1) with a 15% ferric chloride solution at a solid-liquid volume ratio of 1:3, and rehydrate for 4 hours;

[0050] 3) Place the raw material after rehydration treatment in step 2) in a -25℃ environment and freeze for 6 hours, then place it in a 25℃ environment and thaw for 6 hours. Repeat the freeze-thaw cycle 15 times. After every 2 cycles, add water to rehydrate for 0.5 hours. The amount of water added is 1 / 3 of the amount of water in step (1) to ensure that the raw material to be treated is completely soaked.

[0051] 4) The raw material after freeze-thaw cycle treatment in step 3) is coupled with a steam explosion pretreatment method. The steam explosion conditions are 1.0 MPa and the holding time is 20 min.

[0052] 5) Take 1g of the solid material after the pretreatment in step 4), add 15FPU / g DM cellulase and add citrate-sodium citrate buffer at pH 4.8. When the solid content reaches 40%, place it in a 50℃ water bath shaker and react at 120rpm for 72 hours. Collect the lignocellulose enzymatic hydrolysis product.

[0053] Example 2

[0054] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products, the method being as follows:

[0055] 1) Cut the pine wood chips into 3cm×3cm×2cm pieces;

[0056] 2) Mix the raw materials from step 1) with a 5% ferric chloride solution at a solid-liquid volume ratio of 1:1, and rehydrate for 6 hours;

[0057] 3) Place the raw material after rehydration treatment in step 2) in a -20℃ environment and freeze for 8 hours, then place it in a 20℃ environment to thaw for 12 hours. Repeat the freeze-thaw cycle 10 times. After every 3 cycles, add water to rehydrate for 1 hour. The amount of water added is the same as the amount added in step (1) to ensure that the raw material to be treated is completely soaked.

[0058] 4) The raw material after freeze-thaw cycle treatment in step 3) is coupled with a steam explosion pretreatment method. The steam explosion conditions are 1.0 MPa and the holding time is 15 min.

[0059] 5) Take 1g of the solid material after the pretreatment in step 4), add 5FPU / g DM cellulase and citrate-sodium citrate buffer at pH 4.8, the solid content is 15%, place it in a 45℃ water bath shaker, react at 120rpm for 96 hours, and collect the lignocellulose enzymatic hydrolysis product.

[0060] Example 3

[0061] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products, the method being as follows:

[0062] 1) The eucalyptus wood chips are cut into 3cm×3cm×2cm chips;

[0063] 2) Mix the raw materials from step 1) with a 20% ferric chloride solution at a solid-liquid volume ratio of 1:5, and rehydrate for 1 hour;

[0064] 3) Place the raw material after rehydration treatment in step 2) in a -50℃ environment for 2 hours, and then place it in a 40℃ environment for 4 hours to thaw. Repeat the freeze-thaw cycle 20 times. After every 3 cycles, add water for 0.5 hours to rehydrate. The amount of water added is 1 / 5 of the amount of water in step (1) to ensure that the raw material to be treated is completely soaked.

[0065] 4) The raw material after freeze-thaw cycle treatment in step 3) is coupled with a hydrothermal pretreatment method. The conditions for hydrothermal pretreatment are: the hydrothermal temperature of the autoclave is 140℃, the solid-liquid ratio is 1:10 (w / v), 1% glacial acetic acid solution is added, and the treatment time is 60 min.

[0066] 5) Take 1g of the solid material after the pretreatment in step 4), add 20FPU / g DM cellulase and citrate-sodium citrate buffer at pH 4.8, so that the solid content is 60%, place it in a 55℃ water bath shaker, and react at 120rpm for 48 hours to collect the lignocellulose enzymatic hydrolysis product.

[0067] Example 4

[0068] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products. The only difference between this method and Embodiment 1 is that the liquid medium used in the rehydration treatment in step 2) is water. The other steps and parameters are the same as in Embodiment 1.

[0069] Example 5

[0070] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products. The only difference between this method and Example 1 is that the liquid medium in step 2) during the rehydration treatment is a 3% ferric chloride solution. The other steps and parameters are the same as in Example 1.

[0071] Example 6

[0072] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products. The only difference between this method and that of Embodiment 1 is that the liquid medium used in the rehydration treatment in step 2) is a ferric chloride solution with a solute concentration of 25%. The other steps and parameters are the same as those in Embodiment 1.

[0073] Example 7

[0074] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products. The method differs from that in Embodiment 1 only in that the freezing temperature in step 3) is -60℃ and the time is 1h. The other steps and parameters are the same as in Embodiment 1.

[0075] Example 8

[0076] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products. The method differs from that in Embodiment 1 only in that the freezing temperature in step 3) is -10℃ and the time is 9h. The other steps and parameters are the same as in Embodiment 1.

[0077] Example 9

[0078] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products. The only difference between this method and Example 1 is that the thawing temperature in step 3) is 10°C and the thawing time is 13 hours. The other steps and parameters are the same as in Example 1.

[0079] Example 10

[0080] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products. The only difference between this method and Example 1 is that the thawing temperature in step 3) is 50°C and the thawing time is 3 hours. The other steps and parameters are the same as in Example 1.

[0081] Example 11

[0082] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products. The only difference between this method and that of Embodiment 1 is that the step of adding water for 0.5 hours after every 3 cycles is omitted in step 3). The other steps and parameters are the same as those of Embodiment 1.

[0083] Example 12

[0084] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products. The only difference between this method and that of Embodiment 1 is that the number of freeze-thaw cycles in step 3) is 20. The other steps and parameters are the same as those in Embodiment 1.

[0085] Example 13

[0086] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products. The only difference between this method and that of Embodiment 1 is that the number of freeze-thaw cycles in step 3) is 30. The other steps and parameters are the same as those in Embodiment 1.

[0087] Example 14

[0088] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products. The only difference between this method and that of Embodiment 1 is that the number of freeze-thaw cycles in step 3) is 10. The other steps and parameters are the same as those in Embodiment 1.

[0089] Example 15

[0090] This embodiment provides a method for preparing lignocellulose enzymatic hydrolysis products. The only difference between this method and that of Embodiment 1 is that the number of freeze-thaw cycles in step 3) is 4. The other steps and parameters are the same as those in Embodiment 1.

[0091] Comparative Example 1

[0092] This comparative example provides a method for preparing lignocellulose enzymatic hydrolysis products. The method differs from Example 1 only in that it does not include steps 2) and 3), that is, the raw material after step 1) is directly pretreated. The remaining steps and parameters are the same as in Example 1.

[0093] Comparative Example 2

[0094] This comparative example provides a method for preparing lignocellulose enzymatic hydrolysis products. The method differs from Example 1 in that it does not include steps 2) and 3), that is, the raw material after step 1) is directly pretreated. The pretreatment intensity is 3.0 MPa and the maintenance time is 50 min. The remaining steps and parameters are the same as in Example 1.

[0095] Comparative Example 3

[0096] This comparative example provides a method for preparing lignocellulose enzymatic hydrolysis products. The method differs from Example 3 in that it does not include steps 2) and 3), that is, the raw material after step 1) is directly pretreated. The pretreatment temperature is 200℃ and the treatment time is 90min. The remaining steps and parameters are the same as in Example 1.

[0097] The enzymatic hydrolysis rates of Examples 1-15 and Comparative Examples 1-3 are shown in Table 1. The enzymatic hydrolysis rate was calculated as follows:

[0098] Enzymatic hydrolysis rate (glucose yield) = Glucose production in enzymatic hydrolysis products (g) × 0.9 × 100% ÷ Mass of cellulose in raw materials (g)

[0099] Table 1: Lignocellulose enzymatic hydrolysis rate

[0100]

[0101]

[0102] The effect data from Examples 1-3 show that, in this invention, the freeze-thaw cycle treatment of lignocellulose before pretreatment significantly improves the enzymatic hydrolysis efficiency of pretreated lignocellulose at high solid concentrations. The results indicate that the glucose yield of pretreated lignocellulose obtained by the pretreatment method of this invention reaches 79.9-82.5% after enzymatic hydrolysis at high solid concentrations. In Examples 4-5, when the liquid medium during rehydration treatment is water or the concentration of the metal salt solution is too low, the glucose yield after enzymatic hydrolysis of lignocellulose is 74.3% or 75.2%. This is because when water or a low-concentration metal salt solution is used as the liquid medium, its corrosiveness to the lignocellulose structure is poor during freeze-thaw treatment, resulting in poor disintegration of the lignocellulose. In Example 6, when the concentration of the metal salt solution during rehydration treatment exceeds the range specified in this invention, the glucose yield after enzymatic hydrolysis of lignocellulose is 74.5%. This is because when the concentration of the metal salt solution is too high, it severely corrodes the lignocellulose structure, resulting in significant component loss and waste of raw materials, thus affecting the enzymatic hydrolysis efficiency. The data from Examples 7-10 show that, in this invention… When the freezing or thawing temperature and time during freeze-thaw cycles are outside the range of this invention, the glucose yield after enzymatic hydrolysis of lignocellulose is 78.4-79.7%, and the enzymatic hydrolysis efficiency decreases slightly, but the impact is not significant. In Example 11, when no rehydration treatment is performed during freeze-thaw cycles, the glucose yield after enzymatic hydrolysis of lignocellulose is 75.7%, and the enzymatic hydrolysis efficiency decreases significantly. This is because multiple rehydration treatments during freeze-thaw cycles can maintain the stratified freezing pressure, thereby improving the lignin disintegration effect. As shown in Examples 12-15, the number of freeze-thaw cycles also affects the yield. The disintegration effect of lignocellulose affects the final enzymatic hydrolysis rate. As shown in Comparative Example 1, when lignocellulose is not subjected to freeze-thaw cycles before pretreatment, the glucose yield after enzymatic hydrolysis is 55.2%, indicating that pretreatment alone has a poor disintegration effect of lignin, which leads to a significant decrease in enzymatic hydrolysis efficiency. As shown in Comparative Examples 2 and 3, although increasing the pretreatment intensity can improve the disintegration effect of lignocellulose and thus improve the enzymatic hydrolysis efficiency, the enzymatic hydrolysis effect is still worse and the energy consumption is higher compared with the method of using freeze-thaw cycle coupled pretreatment.

[0103] The applicant declares that this invention illustrates the method for pretreatment and dismantling of lignocellulose through the above embodiments and its application. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product, addition of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

[0104] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0105] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A method for green decomposition of lignocellulose through freeze-thaw cycle coupling pretreatment, characterized in that, The method for green dismantling of lignocellulose through freeze-thaw cycle coupling pretreatment includes: rehydrating lignocellulose in a liquid medium, then performing freeze-thaw cycle treatment, followed by coupling pretreatment process to dismantle the lignocellulose, thus obtaining the desired product. The liquid medium is selected from metal salt solutions with a concentration of 5%-20%; The freeze-thaw cycle is repeated 10-20 times; During the freeze-thaw cycle treatment, a rehydration treatment is performed once every 2-4 cycles. The pretreatment process is steam explosion; The metal salt solution is a ferric chloride solution; The freeze-thaw cycle operation includes freezing at -50~-20℃ for 2-8 hours, and then thawing at 20-40℃ for 4-12 hours.

2. The method for green disintegration of lignocellulose through freeze-thaw cycle coupling pretreatment according to claim 1, characterized in that, The raw materials for the lignocellulose include any one or a combination of at least two of the following: wood, bamboo, or rattan.

3. The method for green disintegration of lignocellulose through freeze-thaw cycle coupling pretreatment according to claim 2, characterized in that, The timber includes any one or a combination of at least two of eucalyptus, poplar, pine, fir, or locust.

4. The method for green disintegration of lignocellulose through freeze-thaw cycle coupling pretreatment according to claim 1, characterized in that, The solid-liquid volume ratio of the lignocellulose to the liquid medium is 1:1 to 1:

5.

5. The method for green disintegration of lignocellulose through freeze-thaw cycle coupling pretreatment according to claim 1, characterized in that, The rehydration treatment time is 1-6 hours.

6. The method for green disintegration of lignocellulose through freeze-thaw cycle coupling pretreatment according to claim 1, characterized in that, The rehydration treatment time is 0.5-1 hour.

7. The application of the freeze-thaw cycle coupled pretreatment method for green decomposition of lignocellulose according to any one of claims 1-6 in the degradation treatment of lignocellulose.

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