Electrochemically-driven lignocellulose pretreatment device and method

Abstract

The invention belongs to the technical field of biological fermentation hydrogen production, and relates to an electrochemically-driven lignocellulose pretreatment device and method. The lignocellulose pretreatment device comprises a sodium hypochlorite-hydrogen peroxide co-production electrolytic cell, the electrolytic cell adopts a diaphragm-free design, an anode is a chlorine evolution electrode, a dimensionally stable electrode of which the surface of an anode substrate is loaded with a catalyst containing rhodium, iridium and titanium metal is adopted, a cathode is an air self-breathing electrode, and a single-layer hydrophobic design is adopted; the cathode comprises a substrate, a hydrophobic layer and a non-hydrophobic layer. According to the method, the sodium hypochlorite-hydrogen peroxide co-production electrolytic cell is constructed, the lignocellulose is soaked in the electrolyte, lignin components in the lignocellulose are degraded through sodium hypochlorite, sodium hydroxide and hydrogen peroxide which are produced in situ under the external voltage, the firm structure of the lignocellulose is destroyed, and the lignocellulose co-production efficiency is improved. The degradation efficiency of the microorganisms on the lignocellulose is improved, and subsequent production of clean hydrogen from the lignocellulose through dark fermentation is facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of biological hydrogen production by fermentation, and particularly relates to an electrochemically driven lignocellulose pretreatment device and method. Background Art

[0002] Biomass represented by lignocellulose is of great significance in aspects such as global energy transformation and carbon emission reduction. It can not only supply green and clean energy, but also promote the development of agriculture and rural areas and increase farmers' income.

[0003] For example, under the action of strict anaerobic bacteria such as Clostridium and facultative anaerobic bacteria such as Escherichia coli, lignocellulose can produce clean hydrogen through dark fermentation. This dark fermentation process has mild conditions, a simple method, a wide range of raw material sources, is easy to industrialize, and has great development potential. However, limited by the inherent high molecular weight, amorphous state, and three-dimensional network structure characteristics of lignocellulose, it is difficult for microorganisms to directly utilize lignocellulose. Therefore, before dark fermentation, it is often necessary to pretreat lignocellulose to destroy its firm structure, dissolve lignin, and obtain cellulose and hemicellulose. Cellulose and hemicellulose are the main components of dark fermentation biological hydrogen production. They are degraded into fermentable monosaccharides through enzymatic hydrolysis, and the monosaccharides are then used for dark fermentation to produce hydrogen by Enterobacter aerogenes. Thus, pretreating lignocellulose can make it more easily utilized by microorganisms, thereby improving the degradation efficiency of microorganisms on lignocellulose. In addition, pretreating lignocellulose can destroy the crystal structure of lignocellulose, increase its specific surface area, which is conducive to the attachment and growth of microorganisms or enzymes. Pretreating lignocellulose can also improve the reaction activity of lignocellulose, thereby accelerating the biological conversion process. By adopting an efficient pretreatment technology, the amount of lignocellulose used can be reduced, while the hydrogen production can be increased, and the dark fermentation cost can be further reduced.

[0004] At present, the pretreatment of lignocellulose can be roughly divided into various treatment methods such as chemical pretreatment, physical pretreatment, biological pretreatment, and combined pretreatment. Chemical pretreatment uses sodium hydroxide, sulfuric acid, hydrogen peroxide, ozone, sodium hypochlorite, ethanol, ionic liquids, etc. to break the link between lignin and cellulose. This pretreatment has a good lignin removal effect, but it will also consume a large amount of chemical agents and has a high cost. Physical pretreatment uses physical means such as mechanical grinding, ultrasonic waves, or steam explosion to destroy the structure of lignocellulose, which can produce fewer fermentation inhibitors. However, the physical pretreatment has limited damage effect on the lignocellulose structure, often needs to be used in combination with other pretreatment methods, and has relatively high energy consumption. The biological pretreatment method mainly uses fungal microorganisms such as white rot fungi and the biological enzymes they produce, such as laccase and ligninase, to pretreat lignocellulose. Its treatment conditions are mild, the energy consumption is low, and it can effectively reduce the recalcitrance of lignocellulose. However, the biological pretreatment method often has a long treatment time, and is prone to problems such as contamination by miscellaneous bacteria or enzyme inactivation, which limits the large-scale application of this pretreatment method. The combined pretreatment is a pretreatment method obtained by combining two or more of the above-mentioned pretreatments. It can give full play to the synergistic effect between different pretreatment methods and achieve the effect of making the best use of advantages and avoiding disadvantages, but the treatment process and cost will also increase accordingly.

[0005] In addition, due to the fact that existing pretreatment methods either require the use of a large amount of chemical agents, or have a high cost, or have a long pretreatment time, or have harsh treatment conditions, this also leads to the high cost of hydrogen production by dark fermentation of biomass.

[0006] Therefore, there is an urgent need to further develop an efficient, low-cost and sustainable lignocellulose pretreatment method. Summary of the Invention

[0007] In view of this, the present invention provides an electrochemically driven lignocellulose pretreatment device and method to solve the problems of low efficiency and high cost in the process of hydrogen production in the prior art.

[0008] To achieve the above object, the present invention adopts the following technical solutions.

[0009] According to the first aspect of the present invention, there is provided an electrochemically driven lignocellulose pretreatment device, wherein the lignocellulose pretreatment device includes a sodium hypochlorite-hydrogen peroxide co-production electrolytic cell. The electrolytic cell adopts a diaphragmless design, the anode of the electrolytic cell is a chlorine evolution electrode, and the cathode is an air self-breathing electrode.

[0010] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the anode of the electrolytic cell adopts a dimensionally stable anode, and the surface of the anode substrate of the electrolytic cell is loaded with a catalyst capable of catalyzing the generation of chlorine.

[0011] The dimensionally stable anode is a new type of insoluble anode with long life, high catalytic performance, and no secondary pollution, generally known as DSA (Dimensionally Stable Anode) or DSE (Dimensionally Stable Electrode).

[0012] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the catalyst includes rhodium (Ru), iridium (Ir), and titanium (Ti) metal elements.

[0013] That is, in the present invention, the anode of the electrolytic cell uses a dimensionally stable anode (DSA) including three metal elements of rhodium, iridium, and titanium, which is beneficial to improving the chlorine evolution effect.

[0014] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the substrate material of the anode includes a Ti-based conductive material.

[0015] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the Ti-based conductive material includes any one of a Ti mesh and a Ti sheet.

[0016] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the cathode of the electrolytic cell is an oxygen reduction electrode.

[0017] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the cathode adopts a single-layer hydrophobic design, including a substrate, a hydrophobic layer, and a non-hydrophobic layer; wherein, the hydrophobic layer is located on the air side of the cathode of the electrolytic cell.

[0018] That is, the cathode of the electrolytic cell includes a cathode substrate, a hydrophobic layer located on one side of the surface of the cathode substrate, and a non-hydrophobic layer located on the other side of the surface of the cathode substrate; wherein, the hydrophobic layer is in contact with air outward, and the non-hydrophobic layer is in contact with the electrolyte solution.

[0019] According to the present invention, a self-breathing electrode is used on the cathode side of the electrolytic cell, that is, the cathode is used to separate the electrolyte solution from the air. In order to avoid the seepage of the electrolyte solution and at the same time ensure that oxygen in the air can smoothly diffuse to the cathode catalyst layer for reaction, the cathode according to the present invention adopts a single-sided hydrophobic design, and the hydrophobic layer must be located on the air side.

[0020] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the hydrophobic layer includes a PTFE coating. The function of the hydrophobic layer is to prevent the seepage of the electrolyte solution and at the same time ensure the effective infiltration of air.

[0021] For the above-mentioned electrochemically driven lignocellulose pretreatment device, no catalyst needs to be loaded on the hydrophobic layer.

[0022] In the present invention, the hydrophobic layer does not need to be loaded with a catalyst because the two-electron oxygen reduction reaction occurs at the gas-liquid-solid three-phase interface. Since the hydrophobic layer does not contact the electrolyte, there is no need to load a catalyst on the hydrophobic layer.

[0023] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the substrate of the cathode comprises a single-layer hydrophobic modified carbon paper.

[0024] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the oxygen-doped carbon material comprises at least one of oxidized porous biomass carbon, oxidized carbon nanotubes, oxidized graphene and oxidized MOF-derived carbon.

[0025] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the hydrophobic layer of the cathode of the electrolytic cell is a carbon paper with single-sided hydrophobic treatment.

[0026] For the above-mentioned electrochemically driven lignocellulose pretreatment device, a catalyst is loaded on the surface of the non-hydrophobic layer.

[0027] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the catalyst comprises at least one of oxidized carbon black, oxygen-doped carbon material, nitrogen-doped carbon material and S-doped carbon material.

[0028] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the non-hydrophobic layer is an oxidized carbon black layer loaded on the surface of the cathode substrate.

[0029] In the present invention, the non-hydrophobic layer or the oxidized carbon black layer can be used as a catalyst for two-electron oxygen reduction on the cathode side.

[0030] In the present invention, a catalyst capable of catalyzing two-electron oxygen reduction is loaded on the surface of the cathode of the electrolytic cell for catalyzing the formation of hydrogen peroxide.

[0031] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the electrolyte comprises any one of saturated NaCl solution and NaOH / NaCl mixed solution.

[0032] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the electrolyte is a NaOH / NaCl mixed solution.

[0033] In the present invention, during the electrolysis process, OH will be continuously produced on the cathode side - , thus, if the electrolysis time is long, it is easy to cause the alkalinity of the electrolyte to increase. The presence of NaOH helps the dissolution of lignin. Therefore, the present invention uses a NaOH / NaCl mixed solution as the electrolyte, and NaOH in the electrolyte serves as a dual function of electrolyte and pretreatment chemical reagent in the present invention.

[0034] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the electrolyte is a mixed solution of 0.1 - 1 mol / L (for example, 0.2 mol / L, 0.3 mol / L, 0.5 mol / L, 0.7 mol / L, 0.8 mol / L or 0.9 mol / L) NaCl solution and 0.1 - 1 mol / L (for example, 0.2 mol / L, 0.3 mol / L, 0.5 mol / L, 0.7 mol / L, 0.8 mol / L or 0.9 mol / L) NaOH solution.

[0035] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the electrolyte is a mixed solution of 1 mol / L NaCl - 0.1 mol / L NaOH.

[0036] For the above-mentioned electrochemically driven lignocellulose pretreatment device, the raw materials of the lignocellulose include at least one of wheat straw, corn straw, rice straw, reed, palm fiber, poplar wood and pine wood.

[0037] According to the second aspect of the present invention, there is provided an electrochemically driven lignocellulose pretreatment method, which uses the above-mentioned lignocellulose pretreatment device to pretreat lignocellulose.

[0038] In the above-mentioned electrochemically driven lignocellulose pretreatment method, the pretreatment method includes the following steps:

[0039] 1) Construct a sodium hypochlorite - hydrogen peroxide co-production electrolytic cell according to the above-mentioned lignocellulose pretreatment device;

[0040] 2) Prepare the lignocellulose raw materials;

[0041] 3) Use the electrolysis method to carry out electrochemical pretreatment on the lignocellulose raw materials;

[0042] 4) Carry out post-treatment on the electrochemically pretreated lignocellulose to obtain the pretreated lignocellulose.

[0043] For dark fermentation, microorganisms mainly utilize cellulose and hemicellulose, and do not use lignin. In the present invention, after pretreatment, the firm structure of lignocellulose is destroyed, and the fermentability is greatly improved. In addition, after pretreatment, the concentration of lignin in lignocellulose decreases, and the concentrations of cellulose and hemicellulose available for hydrolysis increase.

[0044] Therefore, using low-cost lignocellulose, pretreating it and then carrying out dark fermentation for hydrogen production is beneficial to reducing the cost of hydrogen production from biomass by the dark fermentation method.

[0045] In the above electrochemically driven lignocellulose pretreatment method, in step 1), a sodium hypochlorite-hydrogen peroxide co-production electrolytic cell is constructed. The anode of the electrolytic cell is a chlorine-evolving electrode, the cathode is an oxygen reduction electrode, and the electrolyte solution is a mixed solution of 0.1 - 1 mol / L (for example, 0.2 mol / L, 0.5 mol / L, 0.7 mol / L, or 0.9 mol / L) NaCl and 0.1 - 1 mol / L (for example, 0.2 mol / L, 0.5 mol / L, 0.7 mol / L, or 0.9 mol / L) NaOH.

[0046] In the above electrochemically driven lignocellulose pretreatment method, in step 1), the electrolyte solution is a mixed solution of 1 mol / L NaCl and 0.1 mol / L NaOH, that is, a 1 mol / L NaCl - 0.1 mol / L NaOH mixed solution.

[0047] In the above electrochemically driven lignocellulose pretreatment method, the cathode adopts a single-layer hydrophobic design, including a substrate, a hydrophobic layer, and a non-hydrophobic layer; wherein, the hydrophobic layer is located on the air side of the cathode of the electrolytic cell; the hydrophobic layer contacts the air outward, the non-hydrophobic layer contacts the electrolyte solution, and there is no catalyst on the hydrophobic layer.

[0048] In the above electrochemically driven lignocellulose pretreatment method, the substrate of the cathode includes a single-layer hydrophobically modified carbon paper.

[0049] In the above electrochemically driven lignocellulose pretreatment method, the oxygen-doped carbon material includes at least one of oxidized porous biomass carbon, oxidized carbon nanotubes, oxidized graphene, and oxidized MOF-derived carbon.

[0050] In the above electrochemically driven lignocellulose pretreatment method, the anode of the electrolytic cell adopts a dimensionally stable electrode with a catalyst capable of catalyzing chlorine production (such as a catalyst including metals such as rhodium, iridium, and titanium) loaded on the surface of the anode substrate.

[0051] In the above electrochemically driven lignocellulose pretreatment method, in step 2), the preparation of the lignocellulose raw material includes: soaking the lignocellulose raw material (such as wheat straw, corn straw, rice straw, reed, palm fiber, poplar wood, or pine wood, etc.) in the electrolyte solution of the electrolytic cell to make it fully wet.

[0052] In the above electrochemically driven lignocellulose pretreatment method, in step 2), the lignocellulose raw material is crushed and then soaked in the electrolyte solution of the electrolytic cell.

[0053] In the above electrochemically driven lignocellulose pretreatment method, the lignocellulose raw material is soaked in the electrolyte solution, and the soaking can be carried out in any container.

[0054] In the above-mentioned electrochemically-driven lignocellulose pretreatment method, in step 3), the steps of electrochemical pretreatment include: applying a voltage to the soaked lignocellulose raw material in step 2) for electrolysis.

[0055] In the above-mentioned electrochemically-driven lignocellulose pretreatment method, in step 3), the steps of electrochemical pretreatment include: applying a voltage to the soaked lignocellulose raw material in step 2) for electrolysis, and controlling the solid-liquid ratio to be 1:5 to 1:15 (for example, 1:5, 1:6, 1:8, 1:9, 1:10, 1:12, 1:13 or 1:14)

[0056] In the present invention, during the process of applying a voltage to the soaked lignocellulose raw material for electrolysis, controlling the solid-liquid ratio can enable the electrolyte to better contact the lignocellulose solid. If the solid-liquid ratio is too high, the electrolyte is wasted, and if it is too low, it is not conducive to the electrolyte well infiltrating the lignocellulose raw material.

[0057] In the above-mentioned electrochemically-driven lignocellulose pretreatment method, in step 3), the solid-liquid ratio is controlled to be 1:10.

[0058] In the above-mentioned electrochemically-driven lignocellulose pretreatment method, in step 3), during the electrochemical pretreatment process, the applied voltage is between 1 and 5 V (for example, 2 V, 3 V, 4 V or 4.5 V).

[0059] In the present invention, during the electrolysis process, if the voltage is too low, it is difficult to form hypochlorous acid and hydrogen peroxide, and the effect cannot be achieved; if the voltage is too high, it will lead to excessive energy consumption.

[0060] In the above-mentioned electrochemically-driven lignocellulose pretreatment method, in step 3), in the electrochemical pretreatment, the electrolysis time depends on the demand and is generally between 1 and 10 h (for example, 2 h, 3 h, 5 h, 6 h, 8 h or 9 h).

[0061] In the present invention, during the electrolysis process, a chlorine evolution reaction occurs on the anode side of the electrolytic cell, generating chlorine gas (Cl2), and the chlorine gas is absorbed by NaOH in situ to form sodium hypochlorite (NaClO) with strong oxidizing properties. At the same time, a two-electron oxygen reduction reaction occurs on the cathode side of the electrolytic cell, generating hydrogen peroxide (H2O2) and hydroxide ions (OH - )

[0062] In the above-mentioned electrochemically-driven lignocellulose pretreatment method, in step 4), the post-treatment includes: after the electrolysis treatment in step 3) is completed, separating the lignocellulose and the electrolyte solution in the electrolytic cell, then rinsing the lignocellulose with clear water to remove the residual electrolyte, and finally drying the rinsed lignocellulose to obtain the pretreated lignocellulose.

[0063] Preferably, the cathode surface is loaded with a catalyst capable of catalyzing two-electron oxygen reduction for catalyzing the production of hydrogen peroxide.

[0064] In the above-mentioned electrochemically-driven lignocellulose pretreatment method, the separation can use the suction filtration method.

[0065] According to the third aspect of the present invention, there is provided an application of the above-mentioned electrochemically-driven lignocellulose pretreatment device. The electrochemically-driven lignocellulose pretreatment device can be used for the pretreatment step of biomass dark fermentation for hydrogen production to pretreat lignocellulose, thereby realizing efficient and low-cost clean hydrogen production.

[0066] In the present invention, a sodium hypochlorite-hydrogen peroxide co-production electrolytic cell (or electrochemical cell) is constructed. At the anode side of the co-production electrolytic cell, a Cl - oxidation reaction occurs. The cathode uses a self-breathing electrode for oxygen reduction to produce hydrogen peroxide. A NaOH / NaCl mixed solution is used as the electrolyte of the system. At the same time, crushed wheat straw and other lignocelluloses are added to the electrolyte. Under an applied voltage, the lignin component in the lignocellulose is degraded by the in-situ produced sodium hypochlorite, sodium hydroxide, and hydrogen peroxide, breaking the firm structure of the lignocellulose and making it more easily utilized by microorganisms, thereby improving the degradation efficiency of microorganisms on lignocellulose and being beneficial to realizing the subsequent dark fermentation of lignocellulose to produce clean hydrogen. At the same time, by adopting the technical solution of the present invention, under the action of electrolysis (i.e., electric drive), the lignocellulose can be quickly pretreated without using a large amount of chemical reagents.

[0067] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0068] The present invention can achieve efficient lignocellulose pretreatment by using inexpensive sodium chloride and sodium hydroxide chemicals and clean electricity. Compared with the chemical pretreatment methods in the prior art, the cost of the consumed chemicals is significantly reduced. Compared with the physical treatment methods in the prior art, the lignocellulose pretreatment according to the present invention is carried out at room temperature and normal pressure, and the reaction conditions are mild, simple, and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The accompanying drawings here are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present invention, and are used together with the specification to explain the principles of the present invention.

[0070] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0071] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the figures in the drawings do not constitute a scale limitation.

[0072] Figure 1 It is a schematic diagram of a device for pretreating lignocellulose driven by electrochemistry provided by the present invention.

[0073] Figure 2 It is a graph showing the relationship between the concentrations of hydrogen peroxide and sodium hypochlorite and the electrolysis time in a diaphragmless electrolytic cell provided in Embodiment 1 of the present invention. Detailed implementation manners

[0074] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0075] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0076] To solve the technical problems of low production efficiency and high cost of clean hydrogen in the prior art, the present invention provides a device for pretreating lignocellulose driven by electrochemistry, which is used for the pretreatment step of hydrogen production by dark fermentation of biomass, so as to achieve high-efficiency and low-cost production of clean hydrogen.

[0077] According to some embodiments of the first aspect of the present invention, a device for pretreating lignocellulose driven by electrochemistry is provided. The lignocellulose pretreatment device includes a co-production electrolytic cell for sodium hypochlorite and hydrogen peroxide. The electrolytic cell adopts a diaphragmless design. The anode of the electrolytic cell is a chlorine evolution electrode, and the cathode is an air self-breathing electrode.

[0078] In some embodiments of the present invention, a dimensionally stable anode is used for the electrolytic cell, and a catalyst capable of catalyzing the generation of chlorine gas is loaded on the surface of the anode substrate of the electrolytic cell.

[0079] In some embodiments of the present invention, the catalyst includes ruthenium (Ru), iridium (Ir), and titanium (Ti) metal elements.

[0080] In some embodiments of the present invention, the substrate material of the anode includes a Ti-based conductive material. For example, the Ti-based conductive material includes any one of a Ti mesh and a Ti sheet.

[0081] In some embodiments of the present invention, the cathode adopts a single-layer hydrophobic design, including a substrate, a hydrophobic layer, and a non-hydrophobic layer; wherein, the hydrophobic layer is located on the air side of the cathode of the electrolytic cell.

[0082] In some embodiments of the present invention, the substrate of the cathode includes a single-layer hydrophobic modified carbon paper.

[0083] In some embodiments of the present invention, the oxygen-doped carbon material includes at least one of oxidized porous biomass carbon, oxidized carbon nanotubes, oxidized graphene, and oxidized MOF-derived carbon.

[0084] In some embodiments of the present invention, the hydrophobic layer includes a PTFE coating. The function of the hydrophobic layer is to prevent the leakage of the electrolyte while ensuring the effective infiltration of air.

[0085] In some embodiments of the present invention, a catalyst is loaded on the surface of the non-hydrophobic layer.

[0086] In some embodiments of the present invention, the catalyst includes at least one of oxidized carbon black, oxygen-doped carbon material, nitrogen-doped carbon material, and S-doped carbon material.

[0087] In some embodiments of the present invention, the non-hydrophobic layer is an oxidized carbon black layer loaded on the surface of the cathode substrate.

[0088] In some embodiments of the present invention, the electrolyte used in the electrolytic cell includes any one of a saturated NaCl solution and a NaOH / NaCl mixed solution.

[0089] In some embodiments of the present invention, the electrolyte is a NaOH / NaCl mixed solution.

[0090] In some embodiments of the present invention, the electrolyte is a mixed solution of 0.1 to 1 mol / L of NaCl and 0.1 to 1 mol / L of NaOH.

[0091] In some embodiments of the present invention, the electrolyte is a mixed solution of 1 mol / L NaCl to 0.1 mol / L NaOH.

[0092] In some embodiments of the present invention, the raw material of the lignocellulose includes at least one of wheat straw, corn straw, rice straw, reed, palm fiber, poplar wood, and pine wood.

[0093] As Figure 1 shown, according to an embodiment of the present invention, an electrochemically driven lignocellulose pretreatment device is provided, which includes a sodium hypochlorite-hydrogen peroxide co-production electrolytic cell and an electrolyte. The electrolytic cell adopts a diaphragm-free design, the anode is a chlorine evolution electrode, the cathode is an oxygen reduction electrode, and the electrolyte is a NaOH / NaCl mixed solution.

[0094] It Figure 1 can be seen that in the electrolytic cell with the diaphragm-free design, a chlorine evolution reaction occurs on the anode side to generate Cl2, and the generated Cl2 is in-situ absorbed by NaOH to produce highly oxidizing NaClO; the cathode side of the electrolytic cell is an oxygen reduction electrode, which belongs to a self-aspirating cathode (or self-breathing electrode) for oxygen reduction to produce hydrogen peroxide. The cathode includes a substrate, a non-hydrophobic layer on one side of the substrate surface, and a hydrophobic layer on the other side of the substrate surface. Among them, the non-hydrophobic layer is in contact with the electrolyte, and the hydrophobic layer is exposed to the air; a two-electron oxygen reduction reaction occurs on the cathode side to produce H2O2 and OH - .

[0095] According to some embodiments of the second aspect of the present invention, an electrochemically driven lignocellulose pretreatment method is provided. The electrochemically driven lignocellulose pretreatment device described above is used to pretreat the lignocellulose raw material (for example, crushed wheat straw), including soaking, electrolytic treatment, and post-treatment of the lignocellulose. Specifically, the crushed wheat straw is soaked in the electrolyte in the electrolytic cell, and electrolyzed for 1 to 10 h with an externally applied voltage of 1 to 5 V. Among them, the wheat straw is oxidized under the action of ClO - and H2O2, destroying its three-dimensional ordered structure, and degrading and dissolving lignin, cellulose, hemicellulose, etc. therein under the action of NaOH (as Figure 1 shown), thereby realizing the pretreatment of the lignocellulose. The lignocellulose after the destruction of the three-dimensional ordered structure is beneficial to subsequent high-efficiency and low-cost dark fermentation for hydrogen production.

[0096] Example 1

[0097] An electrochemically driven lignocellulose pretreatment device includes a diaphragm-free sodium hypochlorite-hydrogen peroxide co-production electrolytic cell and an electrolyte solution. The electrolyte solution is a mixed solution of 1 mol / L NaCl and 0.1 mol / L NaOH. The electrolytic cell uses a dimensionally stable anode (DSA) containing Ti, Ru, and Ir as the anode and a carbon paper with one-sided hydrophobic treatment as the cathode. Oxidized carbon black is loaded on the non-hydrophobic layer of the cathode as the cathode-side two-electron oxygen reduction catalyst.

[0098] Electrolytic treatment is carried out using the pretreatment device; with an applied cell voltage of 2 V, after electrolyzing for different times, the concentrations of hydrogen peroxide and sodium hypochlorite in the electrolyte are as Figure 2 shown.

[0099] It can be Figure 2 seen that the concentrations of hydrogen peroxide and hypochlorite ions in the electrolytic cell gradually increase with the prolongation of the electrolysis time. After electrolyzing for 10 h, the hydrogen peroxide concentration can reach about 0.5 mol / L (mass fraction about 2%), and the hypochlorite ion concentration can reach about 0.2 mol / L.

[0100] Example 2

[0101] Electrochemically driven pretreatment of lignocellulose is carried out using the electrochemically driven lignocellulose pretreatment device in Example 1, including the following steps:

[0102] Crushed wheat straw with a mesh size of 40 is added to the diaphragm-free electrolytic cell, and the solid-liquid ratio of wheat straw to the electrolyte is controlled to be 1:10. Under the condition of an applied cell voltage of 2 V, electrolyze for 10 h. After electrolysis, collect and wash the solid residue.

[0103] Compared with the original material, the residue yield is 80.81%, the residue lignin removal rate is 87.23%, the hemicellulose removal rate is 72.34%, and the cellulose retention rate is 95.63%.

[0104] Example 3

[0105] Electrochemically driven pretreatment of lignocellulose is carried out using the electrochemically driven lignocellulose pretreatment device in Example 1, including the following steps:

[0106] Crushed corn straw with a mesh size of 40 is added to the diaphragm-free electrolytic cell, and the solid-liquid ratio of corn straw to the electrolyte is controlled to be 1:10. Under the condition of an applied cell voltage of 2 V, electrolyze for 10 h. After electrolysis, collect and wash the solid residue.

[0107] Compared with the original material, the residue yield is 85.42%, the residue lignin removal rate is 82.19%, the hemicellulose removal rate is 80.26%, and the cellulose retention rate is 90.98%.

[0108] Comparative Example 1

[0109] The electrochemically driven pretreatment of lignocellulose was carried out using the electrochemically driven lignocellulose pretreatment device in Example 1, including the following steps:

[0110] Wheat straw crushed to 40 mesh was added to the diaphragmless electrolytic cell, and the solid-liquid ratio of wheat straw to electrolyte was controlled to be 1:10. Under the condition of no applied voltage, the wheat straw was pretreated, and the solid residue was collected and washed.

[0111] Compared with the original material, the residue yield was 98.90%, the residue lignin removal rate was 2.25%, the hemicellulose removal rate was 1.03%, and the cellulose retention rate was 99.05%.

[0112] Comparative Example 2

[0113] In this comparative example, the electrochemically driven pretreatment of lignocellulose was carried out using the electrochemically driven lignocellulose pretreatment device in Example 1. The difference between this and the lignocellulose pretreatment device in Example 1 was that the electrolyte in the lignocellulose pretreatment device was a 1 mol / L NaCl solution.

[0114] The electrochemically driven pretreatment of lignocellulose was carried out using the above electrochemically driven lignocellulose pretreatment device, and the steps were as follows:

[0115] Wheat straw crushed to 40 mesh was added to the diaphragmless electrolytic cell, and the solid-liquid ratio of wheat straw to electrolyte was controlled to be 1:10. Under the condition of an applied electrolytic cell voltage of 2 V, electrolysis was carried out for 10 h. After the electrolysis was completed, the solid residue was collected and washed.

[0116] Compared with the original material, the residue yield was 84.75%, the residue lignin removal rate was 77.17%, the hemicellulose removal rate was 75.76%, and the cellulose retention rate was 96.33%.

[0117] Comparative Example 3

[0118] In this comparative example, the electrochemically driven pretreatment of lignocellulose was carried out using the electrochemically driven lignocellulose pretreatment device in Example 1. The difference between this and the lignocellulose pretreatment device in Example 1 was that the electrolyte in the lignocellulose pretreatment device was a saturated NaCl solution.

[0119] The electrochemically driven pretreatment of lignocellulose was carried out using the above electrochemically driven lignocellulose pretreatment device, and the steps were as follows:

[0120] Add wheat straw crushed to 40 mesh into the diaphragm-free electrolytic cell, and control the solid-liquid ratio of wheat straw to electrolyte to be 1:10. Under the condition of an applied electrolytic cell voltage of 2 V, electrolyze for 10 h. After the electrolysis is completed, collect and wash the solid residue.

[0121] Compared with the original material, the residue yield is 83.54%, the lignin removal rate of the residue is 80.45%, the hemicellulose removal rate is 72.14%, and the cellulose retention rate is 94.22%.

[0122] It should be understood that the terms used herein are for the purpose of describing particular example embodiments only and are not intended to be limiting. Unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" as used herein may also include the plural forms. The terms "comprising", "including", "containing", and "having" are inclusive and thus specify the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the particular order described or illustrated, unless the order of performance is explicitly stated. It should also be understood that additional or alternative steps may be used.

[0123] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. An electrochemically driven lignocellulose pretreatment device, characterized in that, The lignocellulose pretreatment device includes a sodium hypochlorite - hydrogen peroxide co - production electrolytic cell. The electrolytic cell is designed without a diaphragm. The anode of the electrolytic cell is a chlorine - evolving electrode, and the cathode is an air - breathing electrode.

2. The electrochemically driven lignocellulose pretreatment device according to claim 1, wherein The anode of the electrolytic cell uses a dimensionally stable electrode with a catalyst capable of catalyzing chlorine generation loaded on the surface of the anode substrate.

3. The electrochemically driven lignocellulose pretreatment device according to claim 2, wherein The catalyst includes rhodium, iridium, and titanium metal elements.

4. The electrochemically driven lignocellulose pretreatment device according to claim 1, wherein, The substrate material of the anode includes a Ti - based conductive material.

5. The electrochemically driven lignocellulose pretreatment device according to claim 4, wherein, The Ti - based conductive material includes a Ti mesh and a Ti sheet.

6. The electrochemically driven lignocellulose pretreatment device according to claim 1, wherein The electrolyte includes at least one of a saturated NaCl solution and a NaOH / NaCl mixed solution.

7. The electrochemically-driven lignocellulose pretreatment device according to claim 6, characterized in that, The electrolyte is a NaOH / NaCl mixed solution.

8. The electrochemically driven lignocellulose pretreatment device according to claim 7, characterized in that The electrolyte is a mixed solution of 0.1 - 1 mol / L NaCl solution and 0.1 - 0.1 mol / L NaOH solution.

9. The electrochemically driven lignocellulose pretreatment device according to claim 1, wherein, The cathode adopts a single - layer hydrophobic design and includes a substrate, a hydrophobic layer, and a non - hydrophobic layer; wherein, the hydrophobic layer is located on the air side of the cathode of the electrolytic cell.

10. The electrochemically driven lignocellulose pretreatment device according to claim 9, wherein, The substrate of the cathode includes a single - layer hydrophobically modified carbon paper.

11. The electrochemically driven lignocellulose pretreatment device according to claim 10, characterized in that, The oxygen - doped carbon material includes at least one of oxidized porous biomass carbon, oxidized carbon nanotubes, oxidized graphene, and oxidized MOF - derived carbon.

12. The electrochemically-driven lignocellulose pretreatment device according to claim 9, wherein The hydrophobic layer includes a PTFE coating.

13. The electrochemically driven lignocellulose pretreatment device according to claim 9, wherein The surface of the non - hydrophobic layer is loaded with a catalyst, and the catalyst includes at least one of oxidized carbon black, oxygen - doped carbon material, nitrogen - doped carbon material, and S - doped carbon material.

14. The electrochemically driven lignocellulose pretreatment device according to claim 1, wherein The raw material of the lignocellulose includes at least one of wheat straw, corn straw, rice straw, reed, palm fiber, poplar wood, and pine wood.

15. An electrochemically driven method for lignocellulose pretreatment, characterized in that, The pretreatment method uses the lignocellulose pretreatment device according to any one of claims 1 - 14 to pretreat lignocellulose, and includes the following steps: 1) Construct a sodium hypochlorite - hydrogen peroxide co - production electrolytic cell according to the lignocellulose pretreatment device according to any one of claims 1 - 14; 2) Prepare the lignocellulose raw material; 3) Perform electrochemical pretreatment on the lignocellulose raw material; 4) Perform post - treatment on the lignocellulose raw material after electrochemical pretreatment to obtain pretreated lignocellulose.

16. The electrochemically-driven lignocellulose pretreatment method according to claim 15, characterized in that, In step 2), the preparation of the lignocellulose raw material includes: soaking the lignocellulose raw material in the electrolyte solution of the electrolytic cell to make it fully wet.

17. The electrochemically-driven lignocellulose pretreatment method according to claim 15, wherein, In step 3), the steps of the electrochemical pretreatment include: applying a voltage to the lignocellulose raw material soaked in step 2) for electrolysis, and the applied voltage is between 1 - 5 V.

18. The electrochemically-driven lignocellulose pretreatment method according to claim 15, characterized in that, In step 3), the steps of the electrochemical pretreatment include: applying a voltage to the lignocellulose raw material soaked in step 2) for electrolysis, and controlling the solid - liquid ratio to be 1:5 - 1:

15.

19. The electrochemically-driven lignocellulose pretreatment method according to claim 15, wherein In step 4), the post - treatment includes: after the electrochemical pretreatment in step 3) is completed, separating the lignocellulose and the electrolyte solution, then rinsing the lignocellulose with clean water to remove the residual electrolyte, and finally drying the rinsed lignocellulose to obtain pretreated lignocellulose.

20. The electrochemically-driven lignocellulose pretreatment method according to claim 19, wherein In step 4), the separation uses the suction filtration method.

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