Method for producing electricity and hydrogen peroxide by coupling aldehyde oxidation to generate acid

Abstract

The invention discloses a method for producing electric energy and hydrogen peroxide by coupling an aldehyde oxidation reaction, the method comprising: providing a liquid flow fuel cell; adding the anolyte containing aldehyde compounds in the anode reservoir to the anode discharge chamber; adding the catholyte in the cathode reservoir to the cathode discharge chamber; passing air into the cathode discharge chamber and the cathode reservoir; connecting the cathode and the anode to an external load to form a loop, while generating electric energy, the aldehyde compounds are oxidized to corresponding acids, while generating hydrogen peroxide; wherein, the cathode electron carrier includes at least one of anthraquinone, polyanthraquinone, anthraquinone 2 carboxylic acids, and 2 ethyl anthraquinone; or, the catholyte includes a redox electrolyte, and the redox electrolyte includes at least one of anthraquinone 2 sulfonic acid, anthraquinone 2,7 disulfonic acid. Thus, the present invention carries out the reaction of aldehyde generation acid in the form of a fuel cell, and the reaction conditions are mild, and while generating acid, the co-production of electric energy and hydrogen peroxide can be achieved.

Description

Technical Field

[0001] The invention belongs to the field of biomass chemical industry, and particularly relates to a method for producing electric energy and hydrogen peroxide by oxidizing aldehyde to generate acid and coupling. Background Art

[0002] Aldehyde oxidation is an important reaction in the field of organic chemistry. For example, furfural, benzaldehyde, and vanillin can be oxidized to produce furoic acid, benzoic acid, and vanillic acid, which can be used as pharmaceutical intermediates, flavorings, and bioplastic precursors, offering broad application prospects. For example, furfural oxidation can be performed using strong oxidants such as potassium permanganate, sodium hypochlorite, and quinoline dichromate to produce furoic acid. Alternatively, aldehyde precursors can undergo a Cannizzaro disproportionation reaction under strongly alkaline conditions to produce the acid and its corresponding alcohol, furoic acid and furfuryl alcohol. However, the use of strong oxidants inevitably produces numerous byproducts, which not only reduces the yield of the target product but also increases the difficulty of subsequent product isolation and purification. The Cannizzaro process produces both the acid and the alcohol, resulting in low raw material utilization and requiring strong alkaline conditions, making it difficult to commercialize. Therefore, there is an urgent need to find green and environmentally friendly oxidation methods. Oxidation using molecular oxygen or air is a green approach from an oxidant perspective, but due to the low solubility of oxygen in liquid phases, the oxidation rate of aldehydes is very slow at room temperature. In order to increase the oxidation rate, it is usually necessary to use a metal catalyst, and sometimes a precious metal catalyst is also required, and it is carried out at a higher pressure to increase the solubility of oxygen in the liquid phase. For example, Chinese invention patent application 202010207372.7 discloses a method for preparing furoic acid by oxidizing furfural, which is to mix furfural, an oxidation catalyst, a co-catalyst and a solvent, then fill an oxygen source, and react at a pressure of 0.1-2Mpa. According to the embodiment disclosed therein, the pressure of oxygen filled in the reactor can be as high as 4Mpa, and the furfural yield under different conditions is between 65-96%. In order to avoid the conversion of furfural into impurities such as humus under alkaline conditions, a solvent can also be introduced to reduce the residence time of furfural in the alkaline solution, thereby reducing the formation of humus, but the solvent used is usually a flammable substance, which increases safety hazards and increases the complexity of subsequent product separation and purification.

[0003] Therefore, it is necessary to improve the existing method of oxidizing aldehydes to generate acids. Summary of the Invention

[0004] The present invention aims to improve at least one of the above technical problems, at least to a certain extent.

[0005] The present invention provides a method for producing electricity and hydrogen peroxide by coupling aldehyde oxidation to acid, the method comprising:

[0006] A liquid flow fuel cell is provided, comprising an anode, a cathode, an ion exchange membrane, an anode graphite bipolar plate, a cathode graphite bipolar plate, an anode discharge chamber, a cathode discharge chamber, an anode liquid storage tank, a cathode liquid storage tank, and an external load;

[0007] The anolyte containing aldehyde compounds in the anode liquid storage tank is added to the anode discharge chamber and circulated back to the anode liquid storage tank; the cathode electrolyte in the cathode liquid storage tank is added to the cathode discharge chamber and circulated back to the cathode liquid storage tank; air is introduced into the cathode discharge chamber and the cathode liquid storage tank;

[0008] The cathode and the anode are connected to an external load to form a circuit, and while generating electrical energy, the aldehyde compound is oxidized into the corresponding acid and hydrogen peroxide is generated;

[0009] Wherein, the cathode is formed by a cathode electron carrier supported on a first conductive substrate, and the method satisfies any one of the following conditions:

[0010] The cathode electron carrier includes at least one of anthraquinone, polyanthraquinone, anthraquinone-2-carboxylic acid, and 2-ethylanthraquinone;

[0011] Alternatively, the catholyte comprises a redox electrolyte comprising at least one of anthraquinone-2-sulfonic acid and anthraquinone-2,7-disulfonic acid.

[0012] Thus, the present invention conducts the aldehyde oxidation reaction to generate acid in a fuel cell format, achieving mild reaction conditions. This overcomes the existing problem of requiring harsh reaction conditions such as high pressure and high temperature for the oxidation of aldehyde to generate acid using air or oxygen. Furthermore, the present method offers the advantage of easily controllable reaction rate. Furthermore, the present invention can simultaneously generate electricity and hydrogen peroxide while generating acid, improving the flexibility and cost-effectiveness of the reaction.

[0013] According to an embodiment of the present invention, the anode discharge chamber and the cathode discharge chamber are located on opposite sides of the ion exchange membrane; the ion exchange membrane is located between the anode graphite bipolar plate and the cathode graphite bipolar plate; the cathode graphite bipolar plate has a first groove on a side away from the ion exchange membrane, and the cathode is located in the first groove; the anode graphite bipolar plate has a second groove on a side away from the ion exchange membrane, and the anode is located in the second groove; the anode liquid reservoir is connected to the anode discharge chamber via a pipe, and the cathode liquid reservoir is connected to the cathode discharge chamber via a pipe; the anode and cathode are respectively connected to an external load, and the external load is located outside the liquid flow fuel cell. As a result, in the anode discharge chamber, aldehyde compounds undergo an oxidation reaction, losing electrons to form acid; in the cathode discharge chamber, oxygen in the air undergoes a reduction reaction to generate hydrogen peroxide. While generating acid and hydrogen peroxide, the directional flow of electrons can generate electrical energy.

[0014] According to an embodiment of the present invention, when the cathode electrolyte includes a redox electrolyte, the cathode electron carrier includes one of metal platinum, metal ruthenium, carbon black, heteropolyacid, iron oxide, ferrocene, iron phthalocyanine, iron-nitrogen-carbon complex, cobalt-nitrogen-carbon complex, graphene, ordered mesoporous carbon, oxidized carbon nanotubes, nitrogen-doped carbon, sulfur-doped carbon, and boron-doped carbon.

[0015] According to an embodiment of the present invention, the first conductive substrate is selected from one of foam copper, foam nickel, carbon felt, carbon paper, and carbon cloth; optionally, the loading amount of the cathode electron carrier is 0.001-10 mg / cm 2 Thus, abundant reaction sites can be provided for the loading and reaction of cathode electron carriers.

[0016] According to an embodiment of the present invention, the anode is formed by an anode electron carrier supported on a second conductive substrate; the anode electron carrier is selected from at least one of copper oxide, silver oxide, nickel oxide, manganese dioxide, cobalt oxide and iron oxide; the second conductive substrate is selected from one of foamed copper, foamed nickel, carbon felt, carbon paper and carbon cloth; optionally, the loading amount of the anode electron carrier is 0.001-10 mg / cm 2 Thus, in the anode discharge chamber, the anode electron carrier can oxidize the aldehyde compound to generate acid.

[0017] According to an embodiment of the present invention, the ion exchange membrane is selected from one of an anion exchange membrane and a cation exchange membrane.

[0018] According to an embodiment of the present invention, the method further includes controlling the temperature of the anolyte in the anode liquid storage tank and the temperature of the catholyte in the cathode liquid storage tank to 20-100° C. by a heating device. This ensures a faster reaction rate on the electrode surface, which is beneficial for the oxidation of aldehyde compounds.

[0019] According to an embodiment of the present invention, the aldehyde compound is one of glucose, xylose, furfural, benzaldehyde, p-hydroxybenzaldehyde, vanillin, and syringaldehyde; optionally, the concentration of the aldehyde compound is 0.001-5 mol / L. This allows for obtaining a higher product concentration while reducing the formation of byproducts such as humus.

[0020] According to an embodiment of the present invention, the cathode electrolyte further comprises a first supporting electrolyte, which is an inorganic acid or an inorganic base; the concentration of the first supporting electrolyte is 0.01-6 mol / L; thereby, the conductivity of the cathode electrolyte can be improved.

[0021] According to an embodiment of the present invention, the anolyte further comprises a second supporting electrolyte, which is an inorganic acid or an inorganic base; the concentration of the second supporting electrolyte is 0.01-6 mol / L; thereby, the conductivity of the solution can be improved and the reaction rate can be accelerated.

[0022] According to an embodiment of the present invention, the concentration of the redox electrolyte is 0.001-4 mol / L; thereby, the conductivity of the cathode electrolyte is increased and further electron transfer to oxygen in the air is promoted.

[0023] According to an embodiment of the present invention, the resistance of the external load is 0-2000 ohms; thereby, good power generation and aldehyde oxidation effects can be obtained.

[0024] According to an embodiment of the present invention, the aldehyde compound is added to the anode discharge chamber in a fed-batch manner, thereby increasing the product concentration and reducing the cost of product separation and purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of a liquid flow fuel cell in one embodiment of the present invention.

[0026] Description of Reference Numerals

[0027] 1- anode liquid storage tank, 2- anode discharge chamber, 3- anode graphite bipolar plate, 4- ion exchange membrane, 5- cathode graphite bipolar plate, 6- cathode discharge chamber, 7- external load, 8- cathode liquid storage tank. DETAILED DESCRIPTION

[0028] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0029] The present invention provides a method for producing electricity and hydrogen peroxide by coupling aldehyde oxidation to acid, the method comprising:

[0030] A liquid flow fuel cell is provided, comprising an anode, a cathode, an ion exchange membrane, an anode graphite bipolar plate, a cathode graphite bipolar plate, an anode discharge chamber, a cathode discharge chamber, an anode liquid storage tank, a cathode liquid storage tank, and an external load;

[0031] The anolyte containing aldehyde compounds in the anode liquid storage tank is added to the anode discharge chamber and circulated back to the anode liquid storage tank; the cathode electrolyte in the cathode liquid storage tank is added to the cathode discharge chamber and circulated back to the cathode liquid storage tank; air is introduced into the cathode discharge chamber and the cathode liquid storage tank;

[0032] The cathode and the anode are connected to an external load to form a circuit, and while generating electrical energy, the aldehyde compound is oxidized into the corresponding acid and hydrogen peroxide is generated;

[0033] Wherein, the cathode is formed by a cathode electron carrier supported on a first conductive substrate, and the method satisfies any one of the following conditions:

[0034] The cathode electron carrier includes at least one of anthraquinone, polyanthraquinone, anthraquinone-2-carboxylic acid, and 2-ethylanthraquinone;

[0035] Alternatively, the catholyte comprises a redox electrolyte comprising at least one of anthraquinone-2-sulfonic acid and anthraquinone-2,7-disulfonic acid.

[0036] Therefore, the present invention carries out the reaction of aldehyde oxidation to generate acid in the form of a fuel cell, the reaction conditions are mild, and the reaction rate of the method of the present invention is easy to adjust; and the present invention can achieve the co-production of electricity and hydrogen peroxide while generating acid.

[0037] For ease of understanding, the principles of the present invention are briefly described below:

[0038] The oxidation reaction of aldehydes involves electron transfer. Generally, the oxidation reaction will occur as long as the redox potential of the oxidant is higher than that of the aldehyde group, meaning the reaction is thermodynamically feasible. However, the reaction rate depends on the kinetics of electron transfer. To increase the electron transfer rate, electron carriers can be used to construct an electron transfer chain, achieving step-by-step electron transfer and thereby increasing the kinetic rate of electron transfer. Furthermore, the directional movement of electrons can form an electric current and generate electrical energy. Therefore, the electron carrier-mediated aldehyde oxidation reaction can be carried out in the form of a fuel cell. This not only allows the aldehyde to be oxidized to acid, but also allows the oxidation driving force and electron transfer rate to be controlled by adjusting the cathode electron carrier, redox electrolyte, and external load, thereby further regulating the oxidation process. Furthermore, by selecting the cathode electron carrier, it is possible to achieve two-electron reduction of oxygen, thereby adjusting the product to hydrogen peroxide.

[0039] The method of the present invention can control the oxidation rate of aldehyde compounds from multiple angles by screening anode electron carriers, adjusting the size of the external load, screening cathode electron carriers, etc., and simultaneously achieve the co-production of electricity, hydrogen peroxide and hydrogen.

[0040] According to an embodiment of the present invention, referring to Figure 1 The anode discharge chamber 2 and cathode discharge chamber 6 are located on opposite sides of the ion exchange membrane 4. The ion exchange membrane 4 is located between the anode graphite bipolar plate 3 and the cathode graphite bipolar plate 5. The cathode graphite bipolar plate 5 has a first groove on the side facing away from the ion exchange membrane 4, with the cathode located in the first groove. The anode graphite bipolar plate 3 has a second groove on the side facing away from the ion exchange membrane 4, with the anode located in the second groove. The anode liquid reservoir 1 is connected to the anode discharge chamber 2 by a pipe, and the cathode liquid reservoir 8 is connected to the cathode discharge chamber 6 by a pipe. The anode and cathode are each connected to an external load 7, which is located outside the flow fuel cell. This allows aldehyde compounds to undergo an oxidation reaction on the anode surface, losing electrons to form an acid. The electrons are transferred to the cathode through an external circuit and are received by the cathode electron carriers and / or redox electrolyte. Air is continuously introduced into both the cathode discharge chamber 6 and the cathode liquid reservoir 8 to regenerate the cathode electron carriers and / or redox electrolyte. By selecting the cathode electron carriers and redox electrolyte, oxygen in the air can be reduced to hydrogen peroxide. By adjusting the size of the external load 7, the battery output voltage and power can be adjusted, thereby adjusting the electron transfer rate. Therefore, the method provided by the present invention can oxidize aldehyde compounds to produce the corresponding acids, convert chemical energy into electrical energy, and simultaneously regulate the two-electron reduction of oxygen, achieving the co-production of electrical energy and hydrogen peroxide.

[0041] According to an embodiment of the present invention, when the cathode electrolyte includes a redox electrolyte, the cathode electron carrier includes one of metal platinum, metal ruthenium, carbon black, heteropolyacid, iron oxide, ferrocene, iron phthalocyanine, iron-nitrogen-carbon complex, cobalt-nitrogen-carbon complex, graphene, ordered mesoporous carbon, oxidized carbon nanotubes, nitrogen-doped carbon, sulfur-doped carbon, and boron-doped carbon. These electron carriers can promote electron transfer kinetics through changes in the valence state of active centers, thereby catalyzing the two-electron reduction of oxygen to produce hydrogen peroxide.

[0042] The cathode electron carriers and / or redox electrolyte reduced within the cathode discharge chamber are oxidized by the incoming air and then regenerated by further contact with incoming air in the cathode liquid reservoir. Therefore, oxygen serves as the final electron acceptor, and the overall reaction involves oxygen oxidizing aldehydes to produce acids. Under the mediation of a suitable cathode electron carrier, oxygen can undergo a two-electron reduction to produce hydrogen peroxide as a byproduct.

[0043] According to an embodiment of the present invention, the first conductive substrate is selected from one of copper foam, nickel foam, carbon felt, carbon paper, and carbon cloth. These substrate materials have excellent conductivity and porosity, providing abundant reaction sites for the loading and reaction of cathode electron carriers. Furthermore, the selection of the conductive substrate material must also take into account the acidity and alkalinity of the electrolyte. Using these materials as the first conductive substrate can also prevent dissolution and corrosion of the first conductive substrate.

[0044] According to an embodiment of the present invention, the loading amount of the cathode electron carrier is 0.001-10 mg / cm 2 This ensures a fast electron transfer rate, which is beneficial for the oxidation of aldehyde compounds and the production of electricity. If the loading is too small, the electron transfer rate will be too slow and the current will be too low, which is not conducive to the oxidation of aldehydes and the production of electricity. If the loading is too large, the raw materials will be wasted and there will be obvious shedding after long-term operation.

[0045] The present invention does not limit the loading method of the cathode electron carrier. Those skilled in the art can select it according to the loading amount of the cathode electron carrier. Exemplary loading methods include but are not limited to coating, electrodeposition, in-situ growth, etc.

[0046] According to an embodiment of the present invention, the anode is formed by an anode electron carrier supported on a second conductive substrate.

[0047] According to some embodiments of the present invention, the anode electron carrier is selected from at least one of copper oxide, silver oxide, nickel oxide, manganese dioxide, cobalt oxide and iron oxide; these metal oxides have a certain redox potential, can oxidize aldehyde groups, and are poorly soluble in water, which can avoid the problem of separation of products and catalysts.

[0048] In the anode discharge chamber of a flow fuel cell, the high-valent anode electron carrier oxidizes aldehyde compounds to form acid, which is then reduced and rapidly transfers electrons through an external circuit to the oxidized cathode electron carrier in the cathode discharge chamber, generating electricity. At this point, the anode electron carrier returns to a high-valent state and continues to participate in the catalytic cycle.

[0049] The second conductive substrate is selected from copper foam, nickel foam, carbon felt, carbon paper, and carbon cloth. These materials have excellent conductivity and porosity, and using them as the second conductive substrate provides abundant reaction sites for the loading and reaction of the anode electron carrier. Furthermore, the choice of the conductive substrate material must also take into account the acidity and alkalinity of the electrolyte. Using these materials as the second conductive substrate can also prevent dissolution and corrosion of the second conductive substrate.

[0050] In some embodiments of the present invention, the loading amount of the anode electron carrier is 0.001-10 mg / cm 2 This ensures a fast electron transfer rate, which is beneficial for the oxidation of aldehyde compounds and the production of electricity. If the loading is too small, the electron transfer rate will be too slow and the current will be too low, which is not conducive to the oxidation of aldehydes and the production of electricity. If the loading is too large, the raw materials will be wasted and there will be obvious shedding after long-term operation.

[0051] The present invention does not limit the loading method of the anode electron carrier. Those skilled in the art can select it according to the loading amount of the anode electron carrier. Exemplary loading methods include but are not limited to coating, electrodeposition, in-situ growth, etc.

[0052] According to an embodiment of the present invention, the ion exchange membrane is selected from one of an anion exchange membrane and a cation exchange membrane.

[0053] The type and ion permeability of the ion exchange membrane significantly affect the internal resistance of the battery, thereby affecting the electrode reaction rate. Those skilled in the art can select an ion exchange membrane that meets the requirements based on the use requirements, such as the catholyte, anolyte, and electrode reaction rate. Specifically, the cation exchange membrane includes but is not limited to a perfluorosulfonic acid membrane, and the anion exchange membrane includes but is not limited to a hydroxide ion exchange membrane.

[0054] According to an embodiment of the present invention, the method further includes: controlling the temperature of the anolyte in the anode reservoir and the temperature of the catholyte in the cathode reservoir to between 20°C and 100°C, for example, 20°C, 25°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C, using a heating device. Because electrode reactions are significantly affected by temperature, the inventors have discovered that controlling the temperature of the anolyte and catholyte within the above ranges can ensure a faster reaction rate on the electrode surface and a faster diffusion rate of active substances, thereby increasing the electron transfer rate and facilitating the oxidation of aldehyde compounds. If the temperature is too low, the reaction rate will be lower; aldehydes undergo various side reactions under alkaline conditions, such as condensation polymerization of furfural under base catalysis to produce substances such as humus. If the electrolyte temperature is too high, the generation rate of byproducts, including humus, will significantly increase, correspondingly reducing the acid yield and hindering the generation of aldehyde compound oxidation products.

[0055] According to some embodiments of the present invention, the temperature of the anolyte in the anode liquid storage tank and the temperature of the catholyte in the cathode liquid storage tank are preferably controlled at 20-60°C.

[0056] According to an embodiment of the present invention, the aldehyde compound is one of glucose, xylose, furfural, benzaldehyde, p-hydroxybenzaldehyde, vanillin, and syringaldehyde; these aldehydes are basic raw materials or platform chemicals derived from biomass. Under the reaction conditions of the present invention, the above-mentioned aldehyde compounds undergo an oxidation reaction and are converted into corresponding acids, such as gluconic acid, xylonic acid, furic acid, benzoic acid, p-hydroxybenzoic acid, vanillic acid, and syringic acid, which can be used as pharmaceutical intermediates, fine chemicals, etc.

[0057] According to some specific embodiments of the present invention, the concentration of the aldehyde compound is 0.001-5 mol / L, for example, 0.001 mol / L, 0.1 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, or 5 mol / L. This allows for a higher product concentration while reducing the formation of byproducts such as humus. If the concentration of the aldehyde compound is too low, the resulting acid product concentration is correspondingly low. If the concentration of the aldehyde compound is too high, the degree of side reactions such as aldehyde polycondensation or degradation to form humus increases, resulting in excessive byproducts such as humus and reducing the yield of the acid product.

[0058] According to some embodiments of the present invention, the concentration of the aldehyde compound is preferably 0.001-2 mol / L.

[0059] According to an embodiment of the present invention, the cathode electrolyte further comprises a first supporting electrolyte, which is an inorganic acid or an inorganic base, and the inorganic acid includes but is not limited to sulfuric acid. Thus, the conductivity of the anode electrolyte can be improved, and an acidic or alkaline environment can be provided for the electrode reaction.

[0060] According to some embodiments of the present invention, the concentration of the first supporting electrolyte is 0.01-6 mol / L, for example, 0.01 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, and 6 mol / L. If the concentration of the first supporting electrolyte is too low, the charge conduction rate of the electrolyte may be too low, resulting in a large internal resistance of the battery. If the concentration of the first supporting electrolyte is too high, side reactions may occur violently, reducing the yield of the target product. In addition, excessively high acid or base concentrations may increase electrode corrosion and shorten electrode life.

[0061] According to an embodiment of the present invention, the anolyte further comprises a second supporting electrolyte, which is an inorganic acid or an inorganic base. Exemplarily, the inorganic base includes but is not limited to potassium hydroxide. Thus, on the one hand, the conductivity of the solution can be improved, and on the other hand, a reaction environment can be provided for the oxidation reaction, thereby accelerating the reaction rate.

[0062] The concentration of the second supporting electrolyte is 0.01-6 mol / L, for example, 0.01 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, and 6 mol / L. If the concentration of the second supporting electrolyte is too low, the charge conduction rate of the electrolyte will be too low and the internal resistance of the battery will be large. If the concentration of the second supporting electrolyte is too high, side reactions will occur violently, reducing the yield of the target product. In addition, excessively high acid or base concentrations will increase electrode corrosion and shorten electrode life.

[0063] According to some embodiments of the present invention, the concentration of the second supporting electrolyte is preferably 0.01-4 mol / L.

[0064] According to an embodiment of the present invention, the concentration of the redox electrolyte is 0.001-4 mol / L, for example, 0.001 mol / L, 0.005 mol / L, 0.3 mol / L, 0.8 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 3 mol / L, or 4 mol / L. Thus, on the one hand, the redox electrolyte can increase the conductivity of the cathode electrolyte, and on the other hand, the redox electrolyte can also serve as a redox electron carrier, promoting further electron transfer to oxygen in the air. In the cathode discharge chamber, the cathode electron carrier and the redox electrolyte can be regenerated, and hydrogen peroxide can also be produced.

[0065] According to an embodiment of the present invention, the resistance of the external load is 0-2000 ohms; connecting the external load is a prerequisite for forming a circuit and realizing the transfer of electrons from aldehyde to oxygen in the air, otherwise the oxidation of aldehyde cannot proceed. The size of the external load directly determines the speed of electron transfer. When the external load is 0 ohms, the battery discharge is carried out in the form of a short circuit, and the electron transfer rate is the fastest at this time. When the external load resistance increases, the ohmic resistance of electron transfer increases, and the oxidation rate of aldehyde at the anode decreases. When the external load is infinite, that is, in an open circuit state, no current is generated, electrons cannot be transferred to the air, and the aldehyde oxidation reaction cannot proceed. According to a specific embodiment of the present invention, the external load is preferably 0-2000 ohms, at which time good power generation and aldehyde oxidation effects can be obtained.

[0066] According to embodiments of the present invention, the aldehyde compound is added to the anode discharge chamber in a fed-batch manner, i.e., the aldehyde compound feedstock is added to the anode over a period of time. This can, on the one hand, reduce the initial concentration of the aldehyde compound in the anolyte, thereby reducing the rate of humic substance formation, and on the other hand, increase the product concentration, thereby reducing the cost of product separation and purification. In some specific embodiments of the present invention, a second supporting electrolyte can be added to the anode discharge chamber as needed.

[0067] The present invention is described below with reference to specific examples. It should be noted that these examples are merely illustrative and do not limit the present invention in any way.

[0068] Example 1

[0069] Screening of anode electron carriers and comparison of their electricity generation characteristics in flow fuel cells.

[0070] Silver oxide, cobalt oxide, copper oxide, nickel oxide, ferric oxide, and manganese dioxide were prepared by coprecipitation and uniformly coated onto nickel foam to form the anode. The anolyte contained 1 mol / L potassium hydroxide as the second supporting electrolyte and 0.1 mol / L furfural as the aldehyde precursor. A carbon black-loaded carbon felt served as the cathode, 0.3 mol / L VO2(SO4)2 as the catholyte redox electrolyte, and 2 mol / L sulfuric acid as the first supporting electrolyte. Nafion 115 membrane served as the ion exchange membrane. After assembling the battery device, a circulation pump continuously pumped the anolyte and catholyte into the anode discharge chamber and cathode discharge chamber, respectively, and then back into the anode and cathode reservoirs, respectively. Discharge was performed at room temperature. The power generation characteristics, open-circuit voltage, and maximum output power of the cells with different anodic electron carriers are shown in Table 1. As shown in Table 1, the cell using silver oxide as the anodic electron carrier exhibited the highest maximum power density and furoic acid yield, significantly outperforming the other electrodes. This shows that silver oxide is an excellent electron carrier to promote the oxidation of aldehydes.

[0071] Table 1 Power generation characteristics of different anode electron carriers

[0072]

[0073] Example 2

[0074] Screen different cathode redox electrolytes and compare their electricity generation characteristics in flow fuel cells.

[0075] The experimental process was the same as in Example 1. Carbon black-loaded carbon felt was used as the cathode, and ferric nitrate, pentavalent vanadyl sulfate, and anthraquinone-2-sulfonic acid were selected as cathode redox electrolytes to compare power generation performance. The ferric nitrate electrolyte solution consisted of 0.8 mol / L ferric nitrate and contained 0.5 mol / L sulfuric acid as the first supporting electrolyte. The pentavalent vanadyl sulfate solution consisted of 0.3 mol / L pentavalent vanadyl sulfate and contained 2 mol / L sulfuric acid as the first supporting electrolyte. The anthraquinone-2-sulfonic acid solution consisted of 0.005 mol / L anthraquinone-2-sulfonic acid and contained 2 mol / L sulfuric acid as the first supporting electrolyte. The power generation characteristics, cell open circuit voltage, and maximum power when using different cathode redox electrolytes are shown in Table 2. As can be seen from Table 2, although the cell using pentavalent vanadyl sulfate as the cathode electron carrier has the highest power density and furoic acid yield, hydrogen peroxide is not generated when using pentavalent vanadyl sulfate and ferric nitrate as cathode electron carriers. When anthraquinone-2-sulfonic acid is used as the electrolyte, hydrogen peroxide can be co-produced at the cathode. Within the same discharge time, the yield of furoic acid is low, and extending the discharge time can also increase the yield of furoic acid.

[0076] Table 2 Power generation characteristics and furoic acid yield of the battery using different cathode redox electrolytes

[0077]

[0078] Example 3

[0079] Performance study of liquid flow fuel cells for electricity generation and co-production of hydrogen peroxide.

[0080] The selection of cathode electron carriers and redox electrolytes can achieve two-electron reduction of oxygen. When the cathode electron carrier and redox electrolyte can achieve two-electron reduction of oxygen, hydrogen peroxide can be co-produced at the cathode. The experimental process is the same as in Example 1. When carbon black-loaded carbon felt is used as the cathode and anthraquinone-2-sulfonic acid is used as the cathode redox electrolyte, the performance of aldehyde oxidation to generate acid, electricity generation and hydrogen peroxide production under different conditions is studied. The results are shown in Table 3. It can be seen that when anthraquinone-2-sulfonic acid is used as the cathode redox electrolyte, although the power density of the fuel cell is lower than that when vanadyl sulfate (pentavalent) is used as the cathode redox electrolyte, it can produce hydrogen peroxide at the same time and has higher economic value. By changing the reaction conditions, including the concentration of furfural precursor, the concentration of anthraquinone-2-sulfonic acid, the concentration of potassium hydroxide (second supporting electrolyte), the concentration of sulfuric acid (first supporting electrolyte) and the type of ion exchange membrane, the changes in the maximum power density of the battery, the yield of furfural acid and the concentration of hydrogen peroxide are studied. Table 3 shows that the battery's maximum power density first increases and then decreases with increasing furfural precursor concentration. Increasing potassium hydroxide and sulfuric acid concentrations can improve the battery's maximum power density. Compared to thicker Nafion 117 membranes, thinner Nafion 115 membranes are more beneficial for improving the battery's maximum power density. Furthermore, long-term discharge tests show that increasing both furfural and potassium hydroxide concentrations leads to a decrease in furoic acid yield.

[0081] Table 3 Performance of furfural oxidation, electricity generation and hydrogen peroxide generation using anthraquinone-2-sulfonic acid as cathode redox electrolyte under different conditions

[0082]

[0083]

[0084] Example 4

[0085] Study on the suitability of aldehyde substrates for liquid flow fuel cells using anthraquinone-2-sulfonic acid as cathode redox electrolyte.

[0086] Using carbon black-loaded carbon felt as the cathode, 0.005 mol / L anthraquinone-2-sulfonic acid as the cathode redox electrolyte, 2 mol / L sulfuric acid as the first supporting electrolyte, silver oxide as the anode electron carrier, and 2 mol / L potassium hydroxide as the second supporting electrolyte, the effects of different aldehyde substrates, including glucose, furfural, 5-hydroxymethylfurfural, benzaldehyde, vanillin, and p-hydroxybenzaldehyde, on the battery discharge characteristics were compared. The initial concentration of the above substrates was 0.1 mol / L. The relevant results are shown in Table 4. It can be seen that these aldehydes can be effectively converted into the corresponding acids, and hydrogen peroxide product is obtained at the cathode. It should be noted that when 5-hydroxymethylfurfural and furfural are used as aldehyde precursors, hydrogen gas generation is also detected on the anode side.

[0087] Table 4 Comparison of the performance of different aldehydes in generating acid, electricity and hydrogen peroxide when anthraquinone-2-sulfonic acid is used as the cathode redox electrolyte

[0088]

[0089] Example 5

[0090] Effects of different cathode electron carriers and redox electrolytes on furfural oxidation, electricity production, and hydrogen peroxide generation.

[0091] Using silver oxide as the anode electron carrier, 2 mol / L potassium hydroxide as the second supporting electrolyte, and 0.1 mol / L furfural as the aldehyde precursor, the effects of different cathode electron carriers and redox electrolytes on furfural oxidation, electricity generation, and hydrogen peroxide production were compared at 25°C. The results are shown in Table 5. The cathode electron carrier and redox electrolyte significantly influence the cell's power density, but the furoic acid yield is consistently greater than 90%. Furthermore, by selecting the cathode electron carrier and redox electrolyte, two-electron reduction of oxygen can be achieved, leading to the co-production of hydrogen peroxide.

[0092] Table 5 Effects of different cathode electron carriers and redox electrolytes on furfural oxidation, electricity production and hydrogen peroxide production

[0093]

[0094] Example 6

[0095] Effects of Fed-Batch Operation on Aldehyde Oxidation and Hydrogen Peroxide Production

[0096] The experimental process is the same as that of Example 3. Nickel foam loaded with silver oxide is used as the anode, 1 mol / L potassium hydroxide is used as the second supporting electrolyte, carbon felt loaded with carbon black is used as the cathode, 0.005 mol / L anthraquinone-2-sulfonic acid is used as the cathode redox electrolyte, and 2 mol / L sulfuric acid is used as the first supporting electrolyte. The initial furfural concentration at the anode is 0.1 mol / L, and discharge is performed under short circuit. In the anode discharge chamber, 0.1 mol / L of furfural is added every 90 minutes. The anode furfural yield and cathode hydrogen peroxide concentration measured at different times are shown in the following table. It is also found that hydrogen is produced at the anode, and the amount of hydrogen produced is measured. It can be seen that as the number of feedings increases, the furfural concentration and hydrogen peroxide concentration both increase. After feeding 6 times, the corresponding initial furfural concentration is 0.7 mol / L, and the furfural yield is 88.5%. Compared with the non-fed batch reaction (Example 3), the fed batch operation can significantly increase the furfural concentration and hydrogen peroxide concentration.

[0097] Table 6 Changes of furoic acid concentration at the anode and hydrogen peroxide concentration at the cathode over time in fed-batch operation

[0098]

[0099] It should be noted that, in this specification, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0100] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0101] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for producing electricity and hydrogen peroxide by oxidizing aldehyde to generate acid, characterized in that: The method comprises: A liquid flow fuel cell is provided, comprising an anode, a cathode, an ion exchange membrane, an anode graphite bipolar plate, a cathode graphite bipolar plate, an anode discharge chamber, a cathode discharge chamber, an anode liquid storage tank, a cathode liquid storage tank, and an external load; The anolyte containing aldehyde compounds in the anode liquid storage tank is added to the anode discharge chamber and circulated back to the anode liquid storage tank; the cathode electrolyte in the cathode liquid storage tank is added to the cathode discharge chamber and circulated back to the cathode liquid storage tank; air is introduced into the cathode discharge chamber and the cathode liquid storage tank; The cathode and the anode are connected to an external load to form a circuit, and while generating electrical energy, the aldehyde compound is oxidized into the corresponding acid and hydrogen peroxide is generated; The anode is formed by an anode electron carrier supported on a second conductive substrate, and the anode electron carrier is silver oxide; Wherein, the cathode is formed by a cathode electron carrier supported on a first conductive substrate, and the method satisfies any one of the following conditions: The cathode electron carrier includes at least one of anthraquinone, polyanthraquinone, anthraquinone-2-carboxylic acid, and 2-ethylanthraquinone; Alternatively, the catholyte comprises a redox electrolyte comprising at least one of anthraquinone-2-sulfonic acid and anthraquinone-2,7-disulfonic acid.

2. The method according to claim 1, characterized in that The anode discharge chamber and the cathode discharge chamber are located on opposite sides of the ion exchange membrane; The ion exchange membrane is located between the anode graphite bipolar plate and the cathode graphite bipolar plate; the cathode graphite bipolar plate is provided with a first groove on a side away from the ion exchange membrane, and the cathode is located in the first groove; the anode graphite bipolar plate is provided with a second groove on a side away from the ion exchange membrane, and the anode is located in the second groove; The anode liquid storage tank is connected to the anode discharge chamber via a pipeline, and the cathode liquid storage tank is connected to the cathode discharge chamber via a pipeline; The anode and the cathode are respectively connected to the external load, and the external load is arranged outside the liquid flow fuel cell.

3. The method according to claim 1, characterized in that When the cathode electrolyte includes a redox electrolyte, the cathode electron carrier includes one of metal platinum, metal ruthenium, carbon black, heteropoly acid, iron oxide, ferrocene, iron phthalocyanine, iron-nitrogen-carbon complex, cobalt-nitrogen-carbon complex, graphene, ordered mesoporous carbon, oxidized carbon nanotubes, nitrogen-doped carbon, sulfur-doped carbon, and boron-doped carbon.

4. The method according to claim 1, wherein The first conductive substrate is selected from one of foam copper, foam nickel, carbon felt, carbon paper, and carbon cloth.

5. The method according to claim 1, wherein The loading amount of the cathode electron carrier is 0.001-10 mg / cm 2 .

6. The method according to claim 1, wherein The second conductive substrate is selected from one of foam copper, foam nickel, carbon felt, carbon paper, and carbon cloth.

7. The method according to claim 1, characterized in that The loading amount of the anode electron carrier is 0.001-10 mg / cm 2 .

8. The method according to claim 1, characterized in that The ion exchange membrane is selected from an anion exchange membrane and a cation exchange membrane.

9. The method according to claim 1, characterized in that The method further comprises: controlling the temperature of the anolyte in the anode liquid storage tank and the temperature of the cathode liquid storage tank to be between 20 and 100°C by a heating device; o C.

10. The method according to claim 1, characterized in that The aldehyde compound is one of glucose, xylose, furfural, benzaldehyde, p-hydroxybenzaldehyde, vanillin and syringaldehyde.

11. The method according to claim 10, characterized in that The concentration of the aldehyde compound is 0.001-5 mol / L.

12. The method according to claim 1, characterized in that The cathode electrolyte further comprises a first supporting electrolyte, wherein the first supporting electrolyte is an inorganic acid or an inorganic base; The concentration of the first supporting electrolyte is 0.01-6 mol / L.

13. The method according to claim 1, wherein The anolyte further comprises a second supporting electrolyte, wherein the second supporting electrolyte is an inorganic acid or an inorganic base; The concentration of the second supporting electrolyte is 0.01-6 mol / L.

14. The method according to claim 1, wherein The concentration of the redox electrolyte is 0.001-4 mol / L.

15. The method according to claim 1, wherein The resistance of the external load is 0-2000 ohms.

16. The method according to claim 1, characterized in that The aldehyde compound is added into the anode discharge chamber in a fed batch manner.

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