Coal water slurry electrolysis hydrogen production method based on pulse electrocatalysis

Abstract

The invention provides a method for producing hydrogen by electrolyzing coal water slurry based on pulse electrocatalysis, and belongs to the technical field of hydrogen energy production. The method comprises the following steps: S1, mixing pulverized coal with a first acid solution to obtain coal water slurry; s2, forming an electrolytic tank hydrogen production device by taking the coal water slurry as an anolyte and taking a second acid solution as a catholyte; s3, pulse power supply is conducted on the anode of the electrolytic tank hydrogen production device, and electrolytic hydrogen production is conducted under the condition that the temperature ranges from 60 DEG C to 80 DEG C; according to the pulse power supply method, the anode potential ranges from 1.4 V to 1.8 V, the resting potential is 0 V, the pulse frequency ranges from 0.4 Hz to 0.6 Hz, and the pulse duty ratio ranges from 40% to 60%. And a pulse power supply mode is adopted, so that the electrode polarization phenomenon can be effectively reduced, the electrolysis process is smoother, and the electrolysis efficiency is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen energy production, and specifically relates to a method for producing hydrogen by electrolysis of water-coal slurry based on pulse electrocatalysis. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Hydrogen energy has the advantages of high energy density and pollution-free combustion products. Hydrogen production by water electrolysis is currently one of the main ways to produce hydrogen, but traditional water electrolysis technology has problems such as high energy consumption and low efficiency. In recent years, water-coal slurry electrolysis technology, as an emerging hydrogen production method, has attracted much attention due to its low energy consumption, low carbon emissions and efficient use of traditional fossil energy. The basic principle of hydrogen production by water-coal slurry electrolysis is to add coal to the anode electrolyte, replace the oxygen evolution reaction of the anode of water electrolysis with coal organic matter oxidation, and generate hydrogen through the cathode electrolysis reaction. Studies have shown that the theoretical decomposition voltage of water-coal slurry electrolysis is only 0.21V, and the actual energy consumption is about 1 / 3 to 1 / 2 of that of water electrolysis for hydrogen production. In addition, this technology also has the advantages of low pollution, separation from coal and integration with fine chemical processes.

[0004] The Chinese invention patent application number 2022100011316 discloses a two-step method for producing hydrogen by electrolyzing water-coal slurry, wherein coal is reduced to Fe 3+ The function of the electrolytic water-coal slurry is decoupled to the hydrothermal system, simplifying the electrolyte composition of the electrolytic water-coal slurry hydrogen production system. This method can not only achieve low-power hydrogen production, but also effectively avoid the wear of coal particles on key components in the electrolyzer, thereby improving the safety of the system. However, this method drives the electrolysis reaction through a constant voltage. Although it achieves hydrogen production by electrolysis of coal slurry to a certain extent, the electrode polarization phenomenon during the electrolysis process is relatively serious. Since the constant voltage cannot be dynamically adjusted according to the actual needs of the electrolysis process, a large number of bubbles are easily generated on the electrode surface in the electrolyzer, which hinders the further progress of the electrolysis reaction and reduces the electrolysis efficiency. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for producing hydrogen by electrolysis of water-coal slurry based on pulse electrocatalysis, in which water-coal slurry is prepared by coal powder and acid solution, and pulse power supply is adopted during the electrolysis process, which can effectively reduce electrode polarization phenomenon and make the electrolysis process smoother, thereby significantly improving the electrolysis efficiency.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] In a first aspect, a method for producing hydrogen by electrolysis of water-coal slurry comprises the steps of:

[0008] S1, mixing coal powder and a first acid solution to obtain a water-coal slurry;

[0009] S2, using water-coal slurry as the anolyte and the second acid solution as the catholyte to form an electrolytic cell hydrogen production device;

[0010] S3. Pulse power supply is applied to the anode of the electrolytic cell hydrogen production device, and hydrogen is produced by electrolysis at a temperature of 60 to 80° C. The pulse power supply method is as follows: the anode potential is 1.4 to 1.8 V, the resting potential is 0 V, the pulse frequency is 0.4 to 0.6 Hz, and the pulse duty cycle is 40 to 60%.

[0011] In the second aspect, a water-coal slurry electrolysis hydrogen production device based on the above-mentioned water-coal slurry electrolysis hydrogen production method based on pulse electrocatalysis includes an anode electrolyte chamber and a cathode electrolyte chamber, the anode electrolyte chamber contains water-coal slurry, the cathode electrolyte chamber contains a second acid solution, the anode electrolyte chamber and the cathode electrolyte chamber are connected through a proton exchange membrane, the water-coal slurry is immersed in an anode, the second acid solution is immersed in a cathode, the anode and the cathode are connected to a pulse power supply to form a loop; a heating device is arranged around the anode electrolyte chamber and the cathode electrolyte chamber.

[0012] The beneficial effects of the present invention are:

[0013] 1. The present invention adopts a pulse power supply mode, which can effectively reduce the electrode polarization phenomenon, make the electrolysis process smoother, and thus significantly improve the electrolysis efficiency. Compared with the traditional coal slurry electrolysis hydrogen production method with constant potential power supply, the electrolysis efficiency can be increased by more than 40%. In addition, the pulse power supply can provide sufficient electrical energy in a shorter time, so that the electrolysis reaction proceeds quickly, thereby reducing the energy loss in the electrolysis process and reducing energy consumption by about 50%.

[0014] 2. The method of the present invention is simple to operate, and the corresponding device has a simple structure. The electrolysis process can be effectively controlled by adjusting the parameters of the pulse power supply, and it is easy to realize industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0016] Figure 1 This is a schematic diagram of the structure of the electrolytic cell hydrogen production device in Example 1.

[0017] Figure 2 It is a schematic diagram showing the difference between the pulse potential of Example 1 and the constant potential voltage application method of Comparative Example 1.

[0018] Figure 3 It is an it curve diagram of the electrolysis of water-coal slurry within 1000s by the pulse potential of Example 1 and the constant potential voltage application method of Comparative Example 1.

[0019] Among them, 1. heating device; 2. cathode; 3. anode; 4. pulse power supply; 5. proton exchange membrane; 6. cathode electrolyte chamber; 7. anode electrolyte chamber. DETAILED DESCRIPTION

[0020] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0021] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0022] In one or more specific embodiments provided by the present invention, a method for producing hydrogen by electrolysis of water-coal slurry based on pulse electrocatalysis is provided, comprising the steps of:

[0023] S1, mixing coal powder and a first acid solution to obtain a water-coal slurry;

[0024] S2, using water-coal slurry as the anolyte and the second acid solution as the catholyte to form an electrolytic cell hydrogen production device;

[0025] S3. Pulse power is supplied to the anode of the electrolytic cell hydrogen production device, and hydrogen is produced by electrolysis at a temperature of 60 to 80° C., wherein the anode potential is 1.4 to 1.8 V, the resting potential is 0 V, the pulse frequency is 0.4 to 0.6 Hz, and the pulse duty cycle is 40 to 60%.

[0026] In the above process, pulse power supply is used for electrolysis. Pulse power supply can reduce bubble coverage and polarization on the electrode surface by periodically changing the electrode potential, thereby reducing pulse polarization. The application of pulse electric field enables the electrode to quickly switch between high voltage and low voltage, which promotes mass transfer and diffusion of reactants, reduces electrochemical reaction resistance on the electrode surface, and thus improves electrolysis efficiency. In the electrolysis process, it can fully decompose and transform organic matter and inorganic minerals, specifically, organic matter such as dissolved organic acids, alcohols or biodegradable organic matter, and inorganic minerals such as carbonates or sulfates formed by metal ions such as calcium and magnesium, thereby reducing reaction resistance and achieving an increase in hydrogen production.

[0027] Optionally, in S1, the particle size of the coal powder is below 200 mesh, that is, the particle size is less than 74 μm.

[0028] Optionally, in S1, the raw material of the coal powder is selected from one or more of lignite, bituminous coal, and anthracite, that is, the method is applicable to all types of coal.

[0029] Optionally, in S1, the first acid solution is a sulfuric acid solution with a concentration of 1 to 1.5 mol / L, but is not limited to a sulfuric acid solution. Other strong acids such as hydrochloric acid, nitric acid, etc. can also be used as electrolytes as long as they can provide sufficient proton concentration to promote the electrolysis reaction and do not produce adverse chemical reactions with other components in the electrolysis system. Selecting different acid solutions may affect the electrolysis efficiency, electrode stability and purity of the final product, and therefore needs to be optimized according to the specific electrolysis process and target product.

[0030] Optionally, in S1, the coal powder content in the water-coal slurry is 25-50 g / L. This concentration range can ensure that sufficient current density can be provided while saving the cost of using coal samples. The specific concentration is related to the properties of the coal sample used.

[0031] Optionally, in S2, an inert electrode is used as the anode, including a platinum electrode, an iridium electrode, a ruthenium electrode or other precious metal electrodes, or other materials capable of undergoing hydrogen evolution reaction are selected.

[0032] Optionally, in S2, the second acid solution is a 1-1.5 mol / L sulfuric acid solution, and the second acid solution is of the same type and concentration as the first acid solution to avoid concentration polarization or other adverse effects caused by osmotic pressure differences.

[0033] Optionally, in S2, the electrolytic cell hydrogen production device is an H-type electrolytic cell, and a proton exchange membrane is used to separate the anode electrolyte and the cathode electrolyte.

[0034] Optionally, in S3, the water-coal slurry is stirred at 400 to 800 r / min during the electrolytic hydrogen production process. The stirring method includes one or more of magnetic stirring and mechanical stirring. Stirring can promote the contact between the electrolyte solution and the electrode surface, accelerate the mass transfer of reactants and products, and reduce the concentration gradient on the electrode surface, thereby reducing electrode polarization. Stirring can also help bubbles to quickly detach from the electrode surface, reduce the coverage of the bubble surface on the electrode surface, and further improve the electrolysis efficiency.

[0035] In one or more specific embodiments provided by the present invention, a water-coal slurry electrolysis hydrogen production device based on the above-mentioned water-coal slurry electrolysis hydrogen production method based on pulse electrocatalysis is provided, comprising: an anode electrolyte chamber and a cathode electrolyte chamber, the anode electrolyte chamber is filled with water-coal slurry, the cathode electrolyte chamber is filled with a second acid solution, the anode electrolyte chamber and the cathode electrolyte chamber are connected through a proton exchange membrane, the water-coal slurry is immersed in an anode, the second acid solution is immersed in a cathode, the anode and the cathode are connected to a pulse power supply to form a loop; a heating device is arranged on the periphery of the anode electrolyte chamber and the cathode electrolyte chamber.

[0036] Through the above device, the operator only needs to set the corresponding pulse voltage, pulse current, pulse frequency, pulse width, duty cycle and other parameters through the control panel of the pulse power supply according to the characteristics of the water-coal slurry and the electrolysis requirements to start the electrolysis process, and adjust the parameters according to the real-time monitoring data during the electrolysis process, without the need for complicated operating procedures and equipment maintenance.

[0037] Optionally, the anode electrolyte chamber is provided with a stirring device, and the stirring device includes one or more of a magnetic stirring device and a mechanical stirring device.

[0038] Optionally, the heating device includes water bath heating, tracing heating, oil bath heating or platform contact heating device.

[0039] Optionally, the proton exchange membrane is a Nafion 177 proton exchange membrane or other materials with similar proton conductivity, such as Nafion 212 and other series of proton exchange membranes, or a high-performance proton exchange membrane based on sulfonated polyetheretherketone (SPEEK), sulfonated polybenzimidazole (SPBI), etc.

[0040] Example 1

[0041] A method for producing hydrogen by electrolysis of water-coal slurry comprises the following steps:

[0042] S1. The raw coal (anthracite) is crushed, ground and sieved in sequence to obtain fine coal powder with a particle size of less than 200 mesh, and a sulfuric acid solution with a concentration of 1 mol / L is used as the first acid solution; 2.4 g of fine coal powder is dispersed in 80 ml of the first acid solution (the coal powder content in the water-coal slurry is 30 g / L), and ultrasonicated for 30 minutes to make the dispersion uniform, so as to obtain a water-coal slurry;

[0043] S2, using water-coal slurry as the anolyte and sulfuric acid solution with the same concentration as the first acid solution as the catholyte to form an electrolytic cell hydrogen production device; wherein the anolyte and the catholyte are separated by a Nafion 177 proton exchange membrane, and a 1×1 cm 2 The platinum electrode was used as the anode, 1×1 cm 2 The Cu2O sheet is used as the cathode, and the anode and cathode are connected to a pulse power supply respectively;

[0044] S3. Pulse power supply is applied to the anode of the electrolytic cell hydrogen production device, with the anode potential being 1.4V, the rest potential being 0V, the pulse frequency being 0.5Hz, and the pulse duty cycle being 50%, and the hydrogen produced at the cathode is collected; during the electrolytic hydrogen production process, a water bath heating method is used to carry out the electrolytic hydrogen production process at a temperature of 60 to 80°C; a magnetic stirring method is used to stir the water-coal slurry at 600r / min.

[0045] In this embodiment, the electrolytic cell hydrogen production device composed of step S2 is as follows Figure 1 As shown: it includes an anolyte chamber 7 and a catholyte chamber 6, the anolyte chamber 7 contains water-coal slurry, the catholyte chamber 6 contains a second acid solution, the anolyte chamber 7 and the catholyte chamber are connected through a proton exchange membrane 5, the anode 3 is immersed in the water-coal slurry, the cathode 2 is immersed in the second acid solution, the anode 3 and the cathode 2 are respectively connected to a pulse power supply 4 to form a loop; a heating device 1 is arranged on the periphery of the anolyte chamber 7 and the catholyte chamber 6; in addition, a magnetic stirring device is arranged in the anolyte chamber 7.

[0046] Comparative Example 1

[0047] The device in Example 1 and the same concentration of coal water slurry and acid solution are used, except that a constant voltage power supply is used, such as Figure 2 As shown, the anode potential of the constant voltage power supply and the pulse power supply is the same, both are 1.4V.

[0048] Example 1 and Comparative Example 1 were used to produce hydrogen by electrolysis, and the it curves within 1000s and the charge amount were compared. Figure 3 As shown, it can be seen that the current density of Example 1 is stable at 200 mA / cm 2, indicating that the electrode polarization phenomenon of Example 1 is weak. The electrode polarization phenomenon of Comparative Example 1 is obvious, resulting in the current density increasing from the initial 150 mA / cm 2 Rapidly reduce to 50mA / cm 2 The following. The charge of Comparative Example 1 is 62.2 mC (millicoulombs), and the charge of Example 1 is 89.2 mC, which shows that the amount of charge transfer during the electrolysis process in Example 1 has been significantly increased. The increase in charge means that more electrons are involved in the electrolysis reaction, thereby promoting the decomposition of water molecules in the water-coal slurry and the generation of hydrogen. Since the output of hydrogen is proportional to the charge, the increase in charge reflects the increase in hydrogen production. This not only increases the output of hydrogen, but also reflects the improvement in the efficiency of the electrolysis process.

[0049] In terms of electrolysis efficiency, under the same electrolysis time of 1000s, the charge of pulse power supply is 89.2mC, while that of traditional constant potential power supply is 62.2mC, and the electrolysis efficiency is improved by more than 40%; in terms of energy consumption, (the pulse power supply mode has a pulse duty cycle of 50%, which means that no voltage is output for half of the time, which means that the power consumption is reduced by about 50%.

[0050] On the other hand, the constant potential power supply method consumes a lot of energy in the process of coal slurry electrolysis to produce hydrogen. Since the resistivity of the coal slurry changes as the reaction proceeds during the electrolysis process, the constant voltage cannot adapt to this change, resulting in a waste of electrical energy. For example, when the coal slurry concentration is high or the electrolyte resistivity is large, the constant voltage needs to provide a larger current to maintain the electrolysis reaction, which increases energy consumption.

[0051] At the same time, constant potential power supply is difficult to fully stimulate the electrolytic activity of various components in the coal slurry. In addition to coal particles, the coal slurry also contains a certain amount of minerals and impurities. These components cannot effectively participate in the electrolysis reaction under constant voltage, resulting in low utilization of the coal slurry, which in turn affects the production of hydrogen.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for producing hydrogen by electrolysis of water-coal slurry based on pulse electrocatalysis, characterized in that: Includes steps: S1, mixing coal powder and a first acid solution to obtain a water-coal slurry; S2, using water-coal slurry as the anolyte and the second acid solution as the catholyte to form an electrolytic cell hydrogen production device; S3. Pulse power supply is applied to the anode of the electrolytic cell hydrogen production device, and hydrogen is produced by electrolysis at a temperature of 60 to 80° C. The pulse power supply method is as follows: the anode potential is 1.4 to 1.8 V, the resting potential is 0 V, the pulse frequency is 0.4 to 0.6 Hz, and the pulse duty cycle is 40 to 60%.

2. The method for producing hydrogen by electrolysis of water-coal slurry based on pulse electrocatalysis according to claim 1, characterized in that: In S1, the particle size of the coal powder is finer than 200 mesh.

3. The method for producing hydrogen by electrolysis of water-coal slurry based on pulse electrocatalysis according to claim 1, characterized in that: In S1, the first acid solution is a sulfuric acid solution with a concentration of 1 to 1.5 mol / L.

4. The method for producing hydrogen by electrolysis of water-coal slurry based on pulse electrocatalysis according to claim 1, characterized in that: In S1, the coal powder content in the water-coal slurry is 25-50 g / L.

5. The method for producing hydrogen by electrolysis of water-coal slurry based on pulse electrocatalysis according to claim 1, characterized in that: In S2, the inert electrode is used as the anode.

6. The method for producing hydrogen by electrolysis of water-coal slurry based on pulse electrocatalysis according to claim 1, characterized in that: The second acid solution is a 1-1.5 mol / L sulfuric acid solution.

7. The method for producing hydrogen by electrolysis of water-coal slurry based on pulse electrocatalysis according to claim 1, characterized in that: In S2, the electrolytic cell hydrogen production device is an H-type electrolytic cell, which uses a proton exchange membrane to separate the anolyte and the cathode electrolyte.

8. The method for producing hydrogen by electrolysis of water-coal slurry based on pulse electrocatalysis according to claim 1, characterized in that: In S3, the water-coal slurry is stirred at 400-800 r / min during the electrolytic hydrogen production process.

9. A water-coal slurry electrolysis hydrogen production device based on the water-coal slurry electrolysis hydrogen production method based on pulse electrocatalysis as described in any one of claims 1 to 8, characterized in that: The invention comprises an anolyte chamber and a cathode electrolyte chamber, wherein the anolyte chamber contains water-coal slurry, and the cathode electrolyte chamber contains a second acid solution, the anolyte chamber and the cathode electrolyte chamber are connected via a proton exchange membrane, an anode is immersed in the water-coal slurry, a cathode is immersed in the second acid solution, and a pulse power supply is connected between the anode and the cathode to form a loop; a heating device is arranged around the anolyte chamber and the cathode electrolyte chamber.

10. The water-coal slurry electrolysis hydrogen production device according to claim 9, characterized in that: The anode electrolyte chamber is provided with a stirring device.

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