Photoelectrocatalytic ammonia synthesis reactor and method based on high-low frequency sound wave combination

Abstract

The present invention discloses a photoelectrocatalytic ammonia synthesis reactor and method based on a combination of high-low frequency sound waves, including an anode pool and a cathode pool made of a light-transmitting material, an anode pool is provided with an anode and an anode electrolyte solution, a cathode pool is provided with a photocathode and a cathode electrolyte solution, the anode pool and the cathode pool are connected at the bottom, and a proton exchange membrane is provided at the connection point, the anode and the photocathode are respectively connected to a bias electric field device through a wire, an oxygen outlet pipeline is connected to the anode pool, and an ammonia and hydrogen outlet pipeline and a nitrogen inlet pipeline are connected to the cathode pool; a light source for providing light to the photocathode is provided outside the cathode pool, a high-frequency sound wave component is connected to the anode pool and the cathode pool, and a low-frequency sound resonance component is provided below the anode pool and the cathode pool. The present invention not only promotes the dispersion and uniform mixing of the reaction medium and strengthens the mass transfer process, but also can effectively improve the bubble separation ability and the ammonia production rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoelectrocatalytic ammonia synthesis, and in particular relates to a photoelectrocatalytic ammonia synthesis reactor and method based on a high-low frequency sound wave combination. Background Art

[0002] Photoelectrocatalytic ammonia synthesis technology uses solar energy and semiconductor photocatalysts to photocatalytically synthesize ammonia. It has many advantages such as low cost and mild reaction conditions. It is considered to be one of the most promising emerging ammonia synthesis technologies. At present, the photoelectrocatalytic ammonia synthesis reaction mostly occurs in a single chamber or a double chamber reaction system with a diaphragm. Under the action of the photocatalyst, ammonia will be produced on the cathode surface and oxygen will be produced on the anode surface. However, the ammonia produced in the process of photoelectrocatalytic ammonia synthesis will adhere to the electrode plate due to the adhesion between the bubbles and the electrode plate, which reduces the contact area between the electrode and the electrolyte and the active area of ​​the electrode, resulting in a decrease in the ammonia production rate and an increase in energy consumption.

[0003] Sound waves are mechanical waves generated by the vibration of a sound source. Based on the frequency of sound waves, sound waves can be divided into infrasound (less than 20Hz), audible sound waves (20Hz~20kHz), and ultrasonic waves (greater than 20kHz). High-frequency sound waves have high frequency, short wavelength, good directionality, and are accompanied by huge energy when propagated in the medium. On the contrary, low-frequency sound waves have low frequency, long wavelength, good diffraction, and strong penetration. High and low sound waves are widely used in music, construction, medical treatment, manufacturing, building materials, detection, military and other industries. However, whether the excellent industrial characteristics of high and low frequency sound waves can be used to promote the photoelectrocatalytic synthesis of ammonia technology has not yet been studied. Summary of the invention

[0004] The purpose of the present invention is to provide a photoelectrocatalytic ammonia synthesis reactor and method based on a high-low frequency sound wave combination to overcome the defects of the prior art. The present invention not only promotes the dispersion and uniform mixing of the reaction medium and strengthens the mass transfer process, but also can effectively improve the bubble separation ability and ammonia production rate.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A photoelectrocatalytic ammonia synthesis reactor based on a combination of high-low frequency sound waves, comprising an anode pool and a cathode pool made of light-transmitting materials, wherein the anode pool is provided with an anode and an anode electrolyte solution, and the cathode pool is provided with a photocathode and a cathode electrolyte solution, the anode pool and the cathode pool are connected at the lower part, and a proton exchange membrane is provided at the connection point, the anode and the photocathode are respectively connected to a bias electric field device through a wire, the anode pool is connected with an oxygen outlet pipeline, and the cathode pool is connected with an ammonia and hydrogen outlet pipeline and a nitrogen inlet pipeline;

[0007] A light source for providing light to the photocathode is arranged outside the cathode pool, a high-frequency sound wave component is connected to both the anode pool and the cathode pool, and a low-frequency sound resonance component is arranged below the anode pool and the cathode pool.

[0008] Furthermore, the high-frequency acoustic wave component includes a high-frequency acoustic wave vibrator arranged on the inner wall of the cathode pool or the anode pool, and a high-frequency acoustic wave generator arranged on the outside of the cathode pool or the anode pool. The power of the high-frequency acoustic wave generator is 300W, the acoustic wave frequency is 17kHz-300kHz, and the high-frequency acoustic wave vibrator is a pressed ceramic type or a probe type.

[0009] Furthermore, the straight-line distance between the high-frequency acoustic wave vibrator and the corresponding anode or photocathode does not exceed 3 cm.

[0010] Furthermore, the low-frequency acoustic resonance component includes a bottom plate arranged below the cathode pool and the anode pool, a plurality of springs are arranged between the bottom plate and the cathode pool and the anode pool, a connecting plate is connected between the springs, and a resonant power drive is arranged on the connecting plate.

[0011] Furthermore, the connecting plate is vertically fixedly connected to the spring, the resonant power drive is located at the exact center of the connecting plate, and the resonant frequency generated by the low-frequency acoustic resonance component is between 50-100 Hz.

[0012] Furthermore, the model of the proton exchange membrane is Nafion NR-211, and the proton exchange membrane is fixed at the connection between the anode pool and the cathode pool by a clamp.

[0013] Furthermore, the anode is a platinum electrode, the photocathode is a glassy carbon electrode with TiO2 coated on the surface, and the anode and the photocathode are arranged in parallel.

[0014] Furthermore, the anode electrolyte solution is a 0.10-2.0 mol / L KOH aqueous solution, and the cathode electrolyte solution is a 1.0 mol / L H2SO4 aqueous solution.

[0015] Furthermore, the light source is a xenon lamp with a power of 50W and a spectral range of 320-780nm; and the bias electric field device is a DC regulated power supply.

[0016] The method for using a photoelectrocatalytic ammonia synthesis reactor based on a high-low frequency sound wave combination is as follows: nitrogen enters the cathode pool through a nitrogen inlet pipeline, a photocathode in the cathode pool is connected to the positive electrode of a bias electric field device, an anode in an anode pool is inserted into an anode electrolyte solution, and is connected to the negative electrode of a bias electric field device for oxidation reaction, generating hydrogen protons and byproduct oxygen, the byproduct oxygen is led out through an oxygen outlet pipeline, and hydrogen protons are transferred into the cathode pool through a proton exchange membrane, in the cathode pool, a light source provides illumination for the photocathode, and under the action of a bias electric field device, photoelectrocatalytic ammonia synthesis is carried out on the surface of the photocathode, the generated ammonia and byproduct hydrogen are led out through ammonia and hydrogen outlet pipelines, during the reaction, a high-frequency sound wave vibrator is used to emit low-intensity ultrasonic waves to the anode pool and the cathode pool, so as to strengthen the mass transfer process of the photoelectrocatalytic ammonia synthesis process, promote the separation of bubbles attached to the photocathode, and improve the ammonia yield, and use a low-frequency sound resonance component to promote the dispersion and mutual dissolution of the intermediate medium in the photoelectrocatalytic ammonia synthesis, and at the same time strengthen the mass transfer process, so as to shorten the reaction time and increase the reaction speed.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects:

[0018] The present invention adopts low-frequency sound wave resonance to generate low-frequency high-acceleration vertical vibration to promote the dispersion and mutual dissolution of the reaction medium and improve the mixing efficiency; at the same time, the microscopic sound flow generated by the low-frequency sound wave resonance greatly enhances the mass transfer efficiency, shortens the reaction time of photoelectrocatalytic synthesis of ammonia, and improves the reaction speed.

[0019] The present invention combines high-frequency sound waves with a photoelectrocatalytic ammonia synthesis reactor. On the one hand, it can strengthen the mass transfer process of photoelectrocatalytic ammonia synthesis and enhance the natural convection and microconvection of the electrolyte. On the other hand, the cavitation effect of the ultrasonic wave will form a large number of small bubbles, which will continuously move, grow or suddenly burst with the vibration of the surrounding medium. When the bubbles burst, instantaneous high pressure is generated near the electrode, which promotes the escape of bubbles attached to the electrode surface and improves the separation effect. At the same time, the high-frequency sound wave will also reduce the surface coverage of the bubbles on the electrode, accelerate the reaction process, increase the reaction rate, and improve the ammonia production efficiency.

[0020] The present invention utilizes the sound fields generated by high and low frequency sound waves in the horizontal and vertical directions respectively to perform multi-sound field coupling, utilizes the coupled sound fields to improve the homogeneous mixing degree of the gas-liquid reaction, reduces the existence of dead zones in the electrolyte, breaks up the aggregation or agglomeration of substances in the original liquid, reduces the diameter of the polymer, increases the specific surface area of ​​the reaction, and enables the reaction to proceed fully.

[0021] The photoelectrocatalytic ammonia synthesis reactor based on the combination of high-low frequency sound waves has a simple structure, is scientific and effective, and is of great benefit to improving the efficiency of photoelectrocatalytic ammonia synthesis. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings in the specification are used to provide further understanding of the present invention and constitute a part of the present invention. The schematic 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.

[0023] Figure 1 It is a schematic diagram of the structure of the present invention;

[0024] Figure 2 It is a schematic diagram of the structure of a low-frequency acoustic resonance component.

[0025] Among them, 1. bias electric field device; 2. anode cell; 3. cathode cell; 4. anode electrolyte solution; 5. cathode electrolyte solution; 6. light source; 7. anode; 8. photocathode; 9. proton exchange membrane; 10. high-frequency sound wave generator; 11. high-frequency sound wave vibrator; 12. resonance power drive; 13. spring; 14. connecting plate; 15 bottom plate; 16. nitrogen inlet pipeline; 17. ammonia and hydrogen outlet pipelines; 18. oxygen outlet pipeline. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0028] like Figure 1-2As shown, a photoelectrocatalytic ammonia synthesis reactor based on a high-low frequency sound wave combination includes a photoelectrocatalytic reaction module, an illumination module, a membrane assembly, a high frequency sound wave assembly, a low frequency sound resonance vibration assembly and a circuit module. The photoelectrocatalytic reaction module includes an anode pool 2, a cathode pool 3, an anode 7 and a photocathode 8 made of light-transmitting quartz glass. The photoelectrocatalytic ammonia synthesis reactor is provided with a nitrogen inlet pipeline 16, an ammonia and hydrogen outlet pipeline 17 and an oxygen outlet pipeline 18. The illumination module includes a light source 6, which provides illumination for the photocathode 8; the membrane assembly includes a proton exchange membrane 9 and a fixture. The proton exchange membrane 9 is a proton exchange membrane Nafion NR-211, which is used to block the direct mixing of the reaction media on both sides and only conduct protons to avoid the occurrence of reverse reaction. The proton exchange membrane Nafion NR-211 is fixed by a clamp at the connecting position between the anode pool 2 and the cathode pool 3. The high-frequency sound wave component includes a high-frequency sound wave generator 10 and a high-frequency sound wave vibrator 11. The high-frequency sound wave vibrator 11 emits low-intensity high-frequency sound waves to improve the mass transfer efficiency and the bubble separation rate. The low-frequency sound resonance component includes a resonant power drive 12, a spring 13 and a connecting plate 14. The connecting plate 14 is vertically fixedly connected to the spring 13, and the resonant power drive 12 is located at the center of the connecting plate 14. The resonant power drive 12 converts the generated mechanical energy into the low-frequency vibration energy of the system through the connecting plate 13. The resonant frequency generated by the low-frequency sound resonance component is between 50-100Hz.

[0029] The circuit module includes a bias electric field device 1, the anode 7 and the photocathode 8 circuits connected to the bias electric field device 1, the high-frequency sound wave generator 10 and the high-frequency sound wave vibrator 11 connected to the circuit and the resonant power drive 12. The anode 7 and the photocathode 8 are connected to the bias electric field device 1 to form a closed loop.

[0030] As a preferred embodiment, the anode 7 is a platinum electrode; the photocathode 8 is a glassy carbon electrode coated with TiO2, and the anode 7 and the photocathode 9 are placed in parallel in the anode pool 2 and the cathode pool 3.

[0031] As a preferred embodiment, the anode pool 2 contains KOH aqueous solution, and the cathode pool 3 contains H2SO4 aqueous solution.

[0032] As a preferred embodiment, the high-frequency sound wave generator 10 and the high-frequency sound wave vibrator 11 are at least two groups, with a power of 300W and a sound wave frequency of 17kHz-300kHz. The selected high-frequency sound wave vibrator is a pressed ceramic type or a probe type. The high-frequency sound wave vibrator 11 is fixed on the side walls of the anode pool 2 and the cathode pool 3, and the straight-line distance between the anode 7 and the photocathode 8 does not exceed 3cm.

[0033] As a preferred embodiment, the resonance frequency generated by the low-frequency acoustic resonance module is between 50-100 Hz.

[0034] As a preferred embodiment, the number of the springs 13 is 4, all of which are metal compression springs. The springs 13 are fixed directly below the anode pool 2 and the cathode pool 3 and are fixedly connected to the bottom plate 15 .

[0035] As a preferred embodiment, the light source 6 is a xenon lamp with a power of 50W and a spectral range of 320 to 780nm.

[0036] As a preferred embodiment, the bias electric field device 1 is a DC regulated power supply.

[0037] When the photoelectrocatalytic ammonia synthesis reactor based on the high-low frequency sound wave combination is used to carry out an ammonia synthesis experiment, the following steps are included:

[0038] Nitrogen enters the cathode pool 3 through the nitrogen inlet pipeline 16. The cathode pool 3 uses a glassy carbon electrode coated with TiO2 as a photocathode 8 and is connected to the positive electrode of the bias electric field device 1. The anode pool 2 uses a platinum electrode as an anode 7 and is inserted into the anode electrolyte solution 4, and is connected to the negative electrode of the bias electric field device 1 for oxidation reaction, generating hydrogen protons and byproduct oxygen, which is drawn out by the oxygen outlet pipeline 18. The hydrogen protons are transferred into the cathode pool 3 through the proton exchange membrane 9. In the cathode pool 3, the light source 6 provides illumination for the photocathode 8, and under the action of the bias electric field device 1, photoelectrocatalytic synthesis of ammonia is carried out on the surface of the photocathode 8. Byproduct hydrogen is also produced during the reaction. The cathode pool 3 is filled with a dilute sulfuric acid solution to absorb the generated ammonia. The generated ammonia and byproduct hydrogen are drawn out through the ammonia and hydrogen outlet pipelines 17. The high-frequency acoustic vibrator 11 emits low-intensity ultrasonic waves to the anode pool 2 and the cathode pool 3, thereby strengthening the mass transfer process of the photoelectrocatalytic ammonia synthesis process, promoting the separation of bubbles attached to the photocathode, and improving the ammonia yield. The low-frequency acoustic resonance module is used to promote the dispersion and mutual dissolution of the medium in the photoelectrocatalytic ammonia synthesis, and at the same time strengthen the mass transfer process, so as to shorten the reaction time and increase the reaction speed.

[0039] Finally, it should be noted that the above embodiments are only preferred embodiments of the present invention to illustrate the technical solution of the present invention, rather than limiting it, and certainly not limiting the patent scope of the present invention; although the present invention has been described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention; that is to say, any changes or embellishments made to the main design concept and spirit of the present invention that have no substantive significance, and the technical problems they solve are still consistent with the present invention, should be included in the protection scope of the present invention; in addition, the direct or indirect application of the technical solution of the present invention in other related technical fields is also included in the patent protection scope of the present invention.

Claims

1. A photoelectrocatalytic ammonia synthesis reactor based on a combination of high- and low-frequency sound waves, characterized in that: The invention comprises an anode pool (2) and a cathode pool (3) made of a light-transmitting material, wherein the anode pool (2) is provided with an anode (7) and an anode electrolyte solution (4), and the cathode pool (3) is provided with a photocathode (8) and a cathode electrolyte solution (5). The anode pool (2) and the cathode pool (3) are connected at the bottom, and a proton exchange membrane (9) is provided at the connection point. The model of the proton exchange membrane (9) is Nafion. NR-211, and the proton exchange membrane (9) is fixed at the connection between the anode pool (2) and the cathode pool (3) by a clamp; the anode (7) and the photocathode (8) are respectively connected to the bias electric field device (1) by wires, the anode pool (2) is connected to an oxygen outlet pipeline (18), the anode (7) is a platinum electrode, the photocathode (8) is a glassy carbon electrode with TiO2 coated on the surface, and the anode (7) and the photocathode (8) are arranged in parallel; the cathode pool (3) is connected to an ammonia and hydrogen outlet pipeline (17) and a nitrogen inlet pipeline (16); A light source (6) for providing light to the photocathode (8) is arranged outside the cathode pool (3); a high-frequency sound wave component is connected to the anode pool (2) and the cathode pool (3); and a low-frequency sound resonance component is arranged below the anode pool (2) and the cathode pool (3); the low-frequency sound resonance component comprises a bottom plate (15) arranged below the cathode pool (3) and the anode pool (2); a plurality of springs (13) are arranged between the bottom plate (15) and the cathode pool (3) and the anode pool (2); a connecting plate (14) is connected between the springs (13); and a resonant power drive (12) is arranged on the connecting plate (14).

2. The photoelectrocatalytic ammonia synthesis reactor based on high-low frequency sound wave combination according to claim 1, characterized in that: The high-frequency sound wave component comprises a high-frequency sound wave vibrator (11) arranged on the inner wall of the cathode pool (3) or the anode pool (2), and a high-frequency sound wave generator (10) arranged on the outside of the cathode pool (3) or the anode pool (2). The power of the high-frequency sound wave generator (10) is 300W, and the sound wave frequency is 17kHz-300kHz. The high-frequency sound wave vibrator (11) is a pressed ceramic type or a probe type.

3. The photoelectrocatalytic ammonia synthesis reactor based on high-low frequency sound wave combination according to claim 2, characterized in that: The straight-line distance between the high-frequency acoustic wave vibrator (11) and the corresponding anode (7) or photocathode (8) does not exceed 3 cm.

4. The photoelectrocatalytic ammonia synthesis reactor based on high-low frequency sound wave combination according to claim 1, characterized in that: The connecting plate (14) is vertically fixedly connected to the spring (13), the resonant power drive (12) is located at the exact center of the connecting plate (14), and the resonant frequency generated by the low-frequency acoustic resonance component is between 50-100 Hz.

5. The photoelectrocatalytic ammonia synthesis reactor based on high-low frequency sound wave combination according to claim 1, characterized in that: The anode electrolyte solution (4) is a 0.10-2.0 mol / L KOH aqueous solution, and the cathode electrolyte solution (5) is a 1.0 mol / L H2SO4 aqueous solution.

6. The photoelectrocatalytic ammonia synthesis reactor based on high-low frequency sound wave combination according to claim 1, characterized in that: The light source (6) is a xenon lamp with a power of 50W and a spectrum range of 320-780nm; the bias electric field device (1) is a DC regulated power supply.

7. The method for using the photoelectrocatalytic ammonia synthesis reactor based on a combination of high-low frequency sound waves according to any one of claims 1 to 6, characterized in that: Nitrogen enters the cathode pool (3) through a nitrogen inlet pipeline (16); a photocathode (8) in the cathode pool (3) is connected to the positive electrode of a bias electric field device (1); an anode (7) in an anode pool (2) is inserted into an anode electrolyte solution (4) and connected to the negative electrode of a bias electric field device (1) to perform an oxidation reaction, thereby generating hydrogen protons and by-product oxygen. The by-product oxygen is led out through an oxygen outlet pipeline (18); hydrogen protons are transferred into the cathode pool (3) through a proton exchange membrane (9); in the cathode pool (3), a light source (6) provides illumination for the photocathode (8) and a light source (6) is provided in the bias electric field device. Under the action of (1), photoelectrocatalytic ammonia synthesis is carried out on the surface of the photocathode (8), and the generated ammonia and by-product hydrogen are led out through the ammonia and hydrogen outlet pipelines (17). During the reaction, low-intensity ultrasonic waves are emitted to the anode pool (2) and the cathode pool (3) through high-frequency acoustic oscillators (11), thereby strengthening the mass transfer process of the photoelectrocatalytic ammonia synthesis process, promoting the separation of bubbles attached to the photocathode, and improving the ammonia yield. The low-frequency acoustic resonance component is used to promote the dispersion and mutual dissolution of the intermediate medium in the photoelectrocatalytic ammonia synthesis, and at the same time strengthen the mass transfer process, so as to shorten the reaction time and increase the reaction speed.

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