A system and method for continuously producing hydrogen by coupling electrolysis of water with electro-oxidation of alcohol to produce formic acid

Abstract

The application relates to the technical field of electrochemical hydrogen production, and discloses an alcohol electrooxidation continuous formic acid preparation coupling water electrolysis hydrogen production system and method, which comprises a cathode side liquid storage device, an anode side liquid storage device, an electrochemical reactor, a hydrogen gas separator, a product separator and a bipolar membrane electro-osmosis reactor. Alkali liquor regeneration and recycling are realized and are coupled with a formic acid separation system in an integrated manner; on one hand, alkali liquor regeneration and recycling can reduce the raw materials of the whole system to only water and alcohol, and other alkali or salt substances do not need to be introduced subsequently; on the other hand, the hydrogen production system, the alkali liquor regeneration and recycling system and the formic acid separation system are coupled in an integrated manner, an integrated closed-loop system of'reaction-separation-regeneration' is constructed, the continuous operation of the system is facilitated, and the system has an industrial application prospect. The bipolar membrane electro-osmosis reactor is used to convert formate into formic acid, the conversion of formate into formic acid can be realized without the additional introduction of inorganic acid, and the alkali liquor can be recycled and reused.

Description

Technical Field

[0001] This invention relates to the field of electrochemical hydrogen production technology, and in particular to a system and method for continuous preparation of formic acid by electro-oxidation of alcohol coupled with water electrolysis. Background Technology

[0002] Hydrogen possesses advantages such as high energy density, cleanliness, and wide availability, making it an important secondary energy source for achieving energy structure transformation. Currently, industrial hydrogen production mainly relies on fossil fuel reforming, while water electrolysis, as a crucial pathway for green hydrogen production, has achieved some degree of industrial application. However, existing water electrolysis hydrogen production technologies still suffer from the following problems: High energy consumption: The theoretical voltage for water decomposition is 1.23 V, but the slow kinetics of the oxygen evolution reaction (OER) at the anolyte lead to higher actual operating voltages. Under industrial conditions, the electrolysis voltage typically needs to reach 1.6–1.8 V, resulting in high hydrogen production costs. Low added value of anode products: Oxygen is generated at the anode during water electrolysis, limiting its application scenarios and hindering overall economic efficiency. Furthermore, in alkaline electrolysis systems, insufficient membrane separation can lead to cross-mixing of hydrogen and oxygen, posing safety risks.

[0003] To overcome the above problems, an electrolytic hydrogen production scheme using the oxidation reaction of small organic molecules to replace the oxygen evolution reaction has been proposed. Among them, alcohols (such as methanol, ethanol, ethylene glycol, glycerol, etc.) have low electro-oxidation potentials under alkaline conditions, which can effectively reduce the overall electrolysis voltage and generate high-value-added products such as formic acid, thereby reducing hydrogen production costs and improving system economics.

[0004] However, this hydrogen production scheme still has the following technical defects: the alkaline electrolyte is difficult to recycle during the reaction process, and alkali or salt substances need to be continuously replenished; the electro-oxidation products of alcohols usually exist in the form of formate, and an additional inorganic acid needs to be introduced to convert them into formic acid; the system does not have the ability to operate continuously, which is not conducive to industrial application.

[0005] In view of this, how to provide a hydrogen production system that can overcome the above-mentioned technical defects is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a system and method for the continuous preparation of formic acid by electro-oxidation of alcohol coupled with water electrolysis to produce hydrogen, which realizes the circulation and continuous operation of alkaline solution during the electrolysis hydrogen production process, thereby solving the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides a continuous formic acid production system for alcohol electro-oxidation coupled with water electrolysis, comprising: A cathode-side electrolyte storage device for storing alkaline electrolyte; Anode-side electrolyte storage device for storing alkaline electrolyte and alcohols; An electrochemical reactor has a cathode chamber and an anode chamber, wherein the cathode chamber is connected to a cathode-side liquid storage device and the anode chamber is connected to an anode-side liquid storage device; in the cathode chamber of the electrochemical reactor, a hydrogen evolution reaction occurs to generate cathode products, and in the anode chamber, an alcohol electro-oxidation reaction occurs to generate anode products. The hydrogen separator is connected to the cathode chamber of the electrochemical reactor and is used to separate the cathode product into hydrogen and the first alkaline solution. The hydrogen is collected by the hydrogen collection device, and the first alkaline solution is made into an alkaline electrolyte and then returned to the cathode side storage device. The product separator is connected to the anode chamber of the electrochemical reactor and is used to separate the anode products into alcohols, formic acid, and a second alkaline solution. The formic acid is collected by a formic acid collection device, and the second alkaline solution is made into an alkaline electrolyte and then refluxed together with the alcohols to the anode-side storage device.

[0008] Furthermore, it also includes: A bipolar membrane electroosmosis reactor is connected to the product separator. The product separator separates the anode product into a mixture of alcohols and alkaline formate. The alkaline formate mixture is fed into the bipolar membrane electroosmosis reactor, where it is hydrolyzed under the action of an electric field to generate hydrogen ions and hydroxide ions. The hydrogen ions combine with formate ions to generate formic acid, and the hydroxide ions are used to regenerate the alkaline solution, resulting in the separation of a second alkaline solution and formic acid.

[0009] Furthermore, it also includes: The pure water supply device is connected to the hydrogen separator at one end and to the cathode-side liquid storage device at the other end. It is used to convert the first alkaline solution into an alkaline electrolyte and then return it to the cathode-side liquid storage device. The alcohol supply device has its input end connected to the product separator and the bipolar membrane electroosmosis reactor, respectively, and its output end connected to the anode-side storage device. It is used to prepare the second alkaline solution into an alkaline electrolyte and then return it to the anode-side storage device together with the alcohol. The alcohol and the alkaline electrolyte are returned to the anode-side storage device together.

[0010] This invention also provides a method for the continuous preparation of formic acid from alcohols via electro-oxidation coupled with water electrolysis to produce hydrogen. The method utilizes a system for the continuous preparation of formic acid from alcohols via electro-oxidation coupled with water electrolysis to produce hydrogen, and includes the following steps: S1: The alkaline electrolyte in the cathode-side storage device is heated by the heating device and then pumped into the cathode chamber of the electrochemical reactor. The alkaline electrolyte and alcohol in the anode-side storage device are heated by the heating device and then pumped into the anode chamber of the electrochemical reactor. The cathode chamber undergoes a hydrogen evolution reaction to generate cathode products, and the anode chamber undergoes an alcohol electro-oxidation reaction to generate anode products. S2: The hydrogen separator separates the cathode product into hydrogen and the first alkaline solution. The hydrogen is collected by the hydrogen collection device, and the first alkaline solution is filtered by the filter and then fed into the pure water supply device. The first alkaline solution is made into an alkaline electrolyte by the pure water supply device and then returned to the cathode side storage device. S3: The product separator separates the anode product into a mixture of alcohols and alkaline formate. The alcohols are filtered and then fed into the alcohol replenishment device, while the alkaline formate mixture is fed into the bipolar membrane electroosmosis reactor. Under the action of the electric field, hydrolysis is performed to generate hydrogen ions and hydroxide ions. Hydrogen ions combine with formate ions to generate formic acid, while hydroxide ions are used to regenerate the alkaline solution, separating the second alkaline solution and formic acid. The formic acid is collected by the formic acid collection device, and the second alkaline solution is filtered and then fed into the alcohol replenishment device. The alcohol replenishment device converts the second alkaline solution into an alkaline electrolyte, which is then refluxed together with the alcohol to the anode-side storage device. The alcohol and alkaline electrolyte are then refluxed together to the anode-side storage device.

[0011] Furthermore, the alcohols are one or more of methanol, ethanol, ethylene glycol, glycerol, and benzyl alcohol.

[0012] Furthermore, the alkaline electrolytes in both the cathode-side and anode-side storage devices are strong alkaline solutions.

[0013] Furthermore, the concentration of alkaline electrolyte in the cathode-side storage device is 0.1 mol / L-10 mol / L, and the concentration of alcohol in the anode-side storage device is 0.1 mol / L-10 mol / L.

[0014] Furthermore, the mass percentage concentration of formic acid is 1% to 30%, and the mass percentage concentration of hydrogen is >99%.

[0015] Furthermore, there are multiple electrochemical reactors connected in series or in parallel. The reaction pressure of the electrochemical reactors is 0.05 MPaG to 1 MPaG, and the reaction temperature is 10℃ to 100℃.

[0016] Furthermore, the reaction pressure of the bipolar membrane electroosmosis reactor is 0.05 MPaG to 1 MPaG, and the reaction temperature is 10℃ to 100℃.

[0017] The present invention discloses the following technical effects: This invention reduces energy consumption in the water electrolysis hydrogen production process by replacing the oxygen evolution reaction with alcohol electrooxidation; it transforms the anode product from low-value oxygen to high-value formic acid, improving the overall economic efficiency of the system; and through the synergistic action of a hydrogen separator, a product separator, and a bipolar membrane electroosmosis reactor, it achieves alkali regeneration and recycling, coupled with the formic acid separation system. On the one hand, the alkali regeneration and recycling system reduces the raw materials of the entire system to only water and alcohols, eliminating the need to introduce other alkalis or salts, resulting in cleaner production and higher economic benefits. On the other hand, the coupling of the hydrogen production system, the alkali regeneration and recycling system, and the formic acid separation system creates an integrated closed-loop system of "reaction-separation-regeneration," which is conducive to continuous system operation and has promising prospects for industrial application.

[0018] This invention uses a bipolar membrane electroosmosis reactor to convert formate into formic acid, achieving the conversion of formate to formic acid without the need for the introduction of additional inorganic acid, while simultaneously enabling the recovery and reuse of alkali solution. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the reaction principle of an electrochemical reactor; Figure 3 This is a schematic diagram of the reaction principle of a bipolar membrane electroosmosis reactor. The components include: 1. Cathode-side liquid storage device; 2. Anode-side liquid storage device; 3. Electrochemical reactor; 4. Hydrogen separator; 5. Product separator; 6. Hydrogen collection device; 7. Formic acid collection device; 8. Bipolar membrane electroosmosis reactor; 9. Pure water supply device; 10. Alcohol supply device; and 11. Heating device. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Those skilled in the art will understand that the term "comprising" as used in this application means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements present. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] like Figures 1 to 3 As shown, this embodiment of the invention provides a continuous formic acid production system for hydrogen production via alcohol electrooxidation coupled with water electrolysis, comprising: The cathode-side electrolyte storage device 1 is used to store alkaline electrolyte and has a built-in pH detector. Anode-side liquid storage device 2 is used to store alkaline electrolyte and alcohols, and has a built-in pH detector and alcohol concentration detector; Electrochemical reactor 3 has a cathode chamber and an anode chamber. Temperature sensors are installed at the outlets of the cathode chamber and the anode chamber. The cathode chamber is connected to the cathode-side liquid storage device 1, and the anode chamber is connected to the anode-side liquid storage device 2. The cathode chamber of electrochemical reactor 3 undergoes a hydrogen evolution reaction to generate cathode products, and the anode chamber undergoes an alcohol electro-oxidation reaction to generate anode products. The hydrogen separator 4 is connected to the cathode chamber of the electrochemical reactor 3 and is used to separate the cathode product into hydrogen and the first alkaline solution. The hydrogen is collected by the hydrogen collection device 6 (containing a hydrogen press), and the first alkaline solution is made into an alkaline electrolyte and then returned to the cathode side storage device 1. The product separator 5 is connected to the anode chamber of the electrochemical reactor 3 and is used to separate the anode product into alcohols, formic acid and a second alkaline solution. The formic acid is collected by the formic acid collection device 7, and the second alkaline solution is made into an alkaline electrolyte and then refluxed together with the alcohol to the anode side storage device 2.

[0025] In this embodiment, the electrochemical reactor 3 can be a two-chamber electrolytic cell, with a diaphragm or ion exchange membrane installed between the cathode chamber and the anode chamber to achieve effective isolation between the cathode and anode reaction systems.

[0026] In this embodiment, it also includes: The bipolar membrane electroosmosis reactor 8 is connected to the product separator 5. The product separator 5 separates the anode product into a mixture of alcohol and alkaline formate. The alkaline formate mixture is fed into the bipolar membrane electroosmosis reactor 8, where it is hydrolyzed under the action of an electric field to generate hydrogen ions and hydroxide ions. The hydrogen ions combine with formate ions to generate formic acid, and the hydroxide ions are used to regenerate the alkaline solution, separating the second alkaline solution and formic acid.

[0027] In this embodiment, it also includes: The pure water supply device 9 is connected at one end to the hydrogen separator 4 and at the other end to the cathode-side liquid storage device 1. It is used to convert the first alkaline solution into an alkaline electrolyte and then return it to the cathode-side liquid storage device 1. The alcohol supply device 10 has its input end connected to the product separator 5 and the bipolar membrane electroosmosis reactor 8, respectively, and its output end connected to the anode-side storage device 2. It is used to prepare the second alkaline solution into an alkaline electrolyte and then return it to the anode-side storage device 2 together with the alcohol.

[0028] This invention also provides a method for the continuous preparation of formic acid from alcohols via electro-oxidation coupled with water electrolysis to produce hydrogen. The method utilizes a system for the continuous preparation of formic acid from alcohols via electro-oxidation coupled with water electrolysis to produce hydrogen, and includes the following steps: S1: The alkaline electrolyte in the cathode-side storage device 1 is heated by the heating device 11 and then pumped into the cathode chamber of the electrochemical reactor 3. The alkaline electrolyte and alcohol in the anode-side storage device 2 are heated by the heating device 11 and then pumped into the anode chamber of the electrochemical reactor 3. The cathode chamber undergoes a hydrogen evolution reaction to generate cathode products, and the anode chamber undergoes an alcohol electro-oxidation reaction to generate anode products. S2: The hydrogen separator 4 separates the cathode product into hydrogen and the first alkaline solution. The hydrogen is collected by the hydrogen collection device 6. The first alkaline solution is filtered by the filter and then fed into the pure water supply device 9. The first alkaline solution is made into an alkaline electrolyte by the pure water supply device 9 and then returned to the cathode side storage device 1. S3: Product separator 5 separates the anode product into alcohols (this part of the alcohols is actually unreacted alcohols that can be used directly) and an alkaline solution / formate mixture. The alcohols are filtered and then fed into the alcohol supply device 10, while the alkaline solution / formate mixture is fed into the bipolar membrane electroosmosis reactor 8. Under the action of the electric field, hydrolysis is performed to generate hydrogen ions and hydroxide ions. Hydrogen ions combine with formate ions to generate formic acid, and hydroxide ions are used to regenerate the alkaline solution, separating the second alkaline solution and formic acid. The formic acid is collected by the formic acid collection device 7. The second alkaline solution is filtered and then fed into the alcohol supply device 10. The alcohol supply device 10 prepares the second alkaline solution into an alkaline electrolyte, which is then refluxed together with the alcohols to the anode-side storage device 2.

[0029] In this embodiment, an alkaline circulation system is adopted on the cathode side. On the one hand, alkaline conditions are beneficial to reducing the impedance of the hydrogen evolution reaction at the cathode and increasing the reaction rate. On the other hand, after the alkaline solution is separated from the hydrogen gas and refluxed, only an appropriate amount of water and liquid needs to be replenished according to the water consumption and entrainment loss (which can be ignored) during the operation, so as to maintain the stable operation of the system. There is basically no need to introduce other alkaline or salt substances, resulting in clean production and high economic benefits.

[0030] The anode side employs a circulating system containing alcohols and alkaline electrolytes. The alcohols undergo electro-oxidation under alkaline conditions, resulting in an anode potential lower than that of the conventional oxygen evolution reaction, which helps reduce cell voltage and electrolysis energy consumption. Simultaneously, the target product generated by the anodic oxidation reaction exists primarily as formate in the anode products, which can be converted into formic acid as the final product after treatment in the subsequent bipolar membrane electroosmosis reactor 8.

[0031] In this embodiment, the pure water supply device 9 adds pure water and mixes it with the first alkaline solution to form an alkaline electrolyte, which is then returned to the cathode-side storage device 1. The alcohol supply device 10 adds pure water and alcohol, and the pure water is mixed with the second alkaline solution to form an alkaline electrolyte. The added alcohol, the recovered alcohol (unreacted alcohol), and the prepared alkaline electrolyte are all returned to the anode-side storage device 2. The specific amounts of pure water and alcohol added by the pure water supply device 9 and the alcohol supply device 10 can be flexibly adjusted according to specific concentration requirements, and are not limited here.

[0032] In this embodiment, the filter is used to remove suspended particulate impurities from the liquid, thereby reducing membrane module fouling and improving system stability.

[0033] In this embodiment, the alcohol is one or more of methanol, ethanol, ethylene glycol, glycerol, and benzyl alcohol.

[0034] In this embodiment, the alkaline electrolytes in both the cathode-side storage device 1 and the anode-side storage device 2 are strong alkaline solutions, such as sodium hydroxide, potassium hydroxide, etc.

[0035] In this embodiment, the concentration of alkaline electrolyte in the cathode-side storage device 1 is 0.1 mol / L-10 mol / L, and the concentration of alcohol in the anode-side storage device 2 is 0.1 mol / L-10 mol / L.

[0036] In this embodiment, the mass percentage concentration of formic acid is 1% to 30%, and the mass percentage concentration of hydrogen is >99%.

[0037] In this embodiment, there are multiple electrochemical reactors 3, which are connected in series or in parallel. The reaction pressure of the electrochemical reactors 3 is 0.05 MPaG to 1 MPaG, and the reaction temperature is 10℃ to 100℃.

[0038] In this embodiment, the reaction pressure of the bipolar membrane electroosmosis reactor 8 is 0.05 MPaG to 1 MPaG, and the reaction temperature is 10℃ to 100℃.

[0039] In some other embodiments, a portion of the formic acid is collected by the formic acid collection device 7, while another portion can be returned to the bipolar membrane electroosmosis reactor 8 to adjust the acid-base environment, promote the conversion of some intermediate salts or by-product salts, and thus improve the purity of the formic acid product.

[0040] In some other embodiments, during the electro-oxidation of alcohols to formate on the anolyte side, small amounts of other small-molecule liquid products may also be generated. These byproducts can be further separated as needed through distillation, membrane separation, adsorption, filtration, or extraction. This embodiment does not impose any particular limitations on this, as long as it does not affect the continuous preparation of formic acid and the recycling of alkali.

[0041] In some other embodiments, the alkaline electrolyte obtained at the pure water supply device 9 can also be used to replenish the anode-side storage device 2.

[0042] The following comparative experiments were conducted on this embodiment: Experimental Example 1 Experimental conditions: A potassium hydroxide solution (1 mol / L) was introduced into the cathode-side storage device 1, and a potassium hydroxide solution (1 mol / L) and glycerol (1 mol / L) were introduced into the anode-side storage device 2. The heating temperature for both devices was 80 degrees Celsius, and the electrochemical reactor 3 was operated under constant current conditions at a current density of 250 mA / cm².

[0043] Experimental results: The hydrogen gas integral was greater than 99%, the formic acid mass percentage concentration was 30%, and only water and glycerol were consumed in the experiment.

[0044] Experimental Example 2 Experimental conditions: A potassium hydroxide solution (2 mol / L) was introduced into the cathode-side storage device 1, and a potassium hydroxide solution (2 mol / L) and ethylene glycol (2 mol / L) were introduced into the anode-side storage device 2. The heating temperature for both devices was 85 degrees Celsius, and the electrochemical reactor 3 was operated under constant current conditions at a current density of 200 mA / cm².

[0045] Experimental results: The hydrogen gas integral was greater than 99%, the formic acid mass percentage concentration was 15%, and the experiment consumed only water and ethylene glycol.

[0046] As can be seen from the above, this embodiment can achieve the coupling of hydrogen production, formic acid separation, and alkali recovery without the need to add alkali and inorganic acid solutions.

[0047] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A system for the continuous electro-oxidation of alcohols to produce formic acid coupled with water electrolysis to produce hydrogen, characterized in that, include; A cathode-side electrolyte storage device (1) is used to store alkaline electrolyte; Anode-side liquid storage device (2) is used to store alkaline electrolyte and alcohols; The electrochemical reactor (3) has a cathode chamber and an anode chamber. The cathode chamber is connected to the cathode-side liquid storage device (1), and the anode chamber is connected to the anode-side liquid storage device (2). The cathode chamber of the electrochemical reactor (3) undergoes a hydrogen evolution reaction to generate cathode products, and the anode chamber undergoes an alcohol electro-oxidation reaction to generate anode products. The hydrogen separator (4) is connected to the cathode chamber of the electrochemical reactor (3) and is used to separate the cathode product into hydrogen and the first alkaline solution. The hydrogen is collected by the hydrogen collection device (6) and the first alkaline solution is made into an alkaline electrolyte and then returned to the cathode side storage device (1). The product separator (5) is connected to the anode chamber of the electrochemical reactor (3) and is used to separate the anode products into alcohols, formic acid and a second alkali solution. Formic acid is collected by a formic acid collection device (7), and after the second alkaline solution is made into an alkaline electrolyte, it is refluxed together with alcohol to the anode side storage device (2).

2. The continuous electro-oxidation system for preparing formic acid from alcohols coupled with water electrolysis for hydrogen production according to claim 1, characterized in that, Also includes: The bipolar membrane electroosmosis reactor (8) is connected to the product separator (5). The product separator (5) separates the anode product into a mixture of alcohol and alkaline formate. The alkaline formate mixture is fed into the bipolar membrane electroosmosis reactor (8) and hydrolyzes under the action of an electric field to generate hydrogen ions and hydroxide ions. The hydrogen ions combine with formate ions to generate formic acid, and the hydroxide ions are used to regenerate the alkaline solution, separating the second alkaline solution and formic acid.

3. The continuous electro-oxidation system for preparing formic acid from alcohols coupled with water electrolysis for hydrogen production according to claim 2, characterized in that, Also includes: The pure water supply device (9) is connected to the hydrogen separator (4) at one end and to the cathode side liquid storage device (1) at the other end. It is used to convert the first alkaline solution into an alkaline electrolyte and then return it to the cathode side liquid storage device (1). The alcohol supply device (10) has its input end connected to the product separator (5) and the bipolar membrane electroosmosis reactor (8), and its output end connected to the anode side storage device (2). It is used to prepare the second alkaline solution into an alkaline electrolyte and then return it to the anode side storage device (2) together with the alcohol.

4. A method for the continuous preparation of formic acid from alcohols via electrooxidation coupled with water electrolysis to produce hydrogen, characterized in that, The continuous formic acid production system based on the electro-oxidation of alcohols coupled with water electrolysis as described in claim 3 includes the following steps: S1: The alkaline electrolyte in the cathode-side storage device (1) is heated by the heating device (11) and then pumped into the cathode chamber of the electrochemical reactor (3). The alkaline electrolyte and alcohol in the anode-side storage device (2) are heated by the heating device (11) and then pumped into the anode chamber of the electrochemical reactor (3). The cathode chamber undergoes a hydrogen evolution reaction to generate cathode products, and the anode chamber undergoes an alcohol electro-oxidation reaction to generate anode products. S2: The hydrogen separator (4) separates the cathode product into hydrogen and the first alkaline solution. The hydrogen is collected by the hydrogen collection device (6). The first alkaline solution is filtered by the filter and then fed into the pure water supply device (9). The first alkaline solution is made into an alkaline electrolyte by the pure water supply device (9) and then returned to the cathode side storage device (1). S3: The product separator (5) separates the anode product into a mixture of alcohol and alkaline formate. The alcohol is filtered and then fed into the alcohol supply device (10). The alkaline formate mixture is fed into the bipolar membrane electroosmosis reactor (8). Under the action of the electric field, hydrolysis is performed to generate hydrogen ions and hydroxide ions. Hydrogen ions combine with formate ions to generate formic acid. The hydroxide ions are used to regenerate the alkaline solution, and the second alkaline solution and formic acid are separated. The formic acid is collected by the formic acid collection device (7). The second alkaline solution is filtered and then fed into the alcohol supply device (10). The second alkaline solution is made into an alkaline electrolyte by the alcohol supply device (10) and then refluxed with the alcohol to the anode side storage device (2).

5. The method for continuous preparation of formic acid by electro-oxidation of alcohols coupled with water electrolysis to produce hydrogen according to claim 4, characterized in that, The alcohols are one or more of methanol, ethanol, ethylene glycol, glycerol, and benzyl alcohol.

6. The method for continuous preparation of formic acid by electro-oxidation of alcohols coupled with water electrolysis to produce hydrogen according to claim 4, characterized in that, The alkaline electrolytes in both the cathode-side storage device (1) and the anode-side storage device (2) are strong alkaline solutions.

7. The method for continuous preparation of formic acid by electro-oxidation of alcohols coupled with water electrolysis to produce hydrogen according to claim 4, characterized in that, The alkaline electrolyte concentration in the cathode-side storage device (1) is 0.1 mol / L-10 mol / L, and the alcohol concentration in the anode-side storage device (2) is 0.1 mol / L-10 mol / L.

8. The method for continuous preparation of formic acid by electro-oxidation of alcohols coupled with water electrolysis to produce hydrogen according to claim 4, characterized in that, The mass percentage concentration of formic acid is 1% to 30%, and the mass percentage concentration of hydrogen is >99%.

9. The method for continuous preparation of formic acid by electro-oxidation of alcohols coupled with water electrolysis to produce hydrogen according to claim 4, characterized in that, There are multiple electrochemical reactors (3), which are connected in series or in parallel. The reaction pressure of the electrochemical reactors (3) is 0.05 MPaG to 1 MPaG, and the reaction temperature is 10℃ to 100℃.

10. The method for continuous preparation of formic acid by electro-oxidation of alcohols coupled with water electrolysis to produce hydrogen according to claim 4, characterized in that, The reaction pressure of the bipolar membrane electroosmosis reactor (8) is 0.05 MPaG to 1 MPaG, and the reaction temperature is 10℃ to 100℃.

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