System and method for electrocatalytic reduction of high pressure co2

Abstract

The application provides a system and method for electrocatalytic reduction of high-pressure CO2, wherein a pressure-resistant stainless steel container is arranged after a pressure-resistant electrocatalytic reactor, and gas products and liquid products from the pressure-resistant electrocatalytic reactor are both introduced into the pressure-resistant stainless steel container, that is, the cathode gas passage and the anode liquid passage of the pressure-resistant electrocatalytic reactor are communicated in the pressure-resistant stainless steel container, so that the pressure of the cathode gas passage and the anode liquid passage is equal, that is, the pressure balance on both sides of the gas diffusion electrode is achieved. Meanwhile, a check valve is arranged to avoid the electrolyte entering the cathode. The application does not need expensive high-pressure gas mass flow controllers, high-pressure back pressure valves and other accessories to adjust the pressure balance, and the high-precision pressure balance control is achieved through the low-cost check valve and the pressure-resistant stainless steel container, the overall cost and the subsequent maintenance cost are low, the structure is simple, and the daily maintenance and scale-up are facilitated.

Description

Technical Field

[0001] This invention belongs to the field of CO2 reduction technology and relates to a system and method for electrocatalytic reduction of high-pressure CO2. Background Technology

[0002] Coal, as a primary energy source for humankind, dictates that carbon emissions will continue for a considerable period. Therefore, achieving the "dual carbon" goal necessitates promoting innovation in green and low-carbon technologies. In this context, electrocatalytic CO2 reduction technology can reduce carbon emissions while simultaneously yielding high-value-added chemicals and fuels, such as carbon monoxide, methane, formic acid, methanol, ethylene, and ethanol. Coupled with wind and solar power generation, this technology can also convert low-energy-density, highly dispersed, unstable, and discontinuous renewable energy sources into clean, pollution-free, high-energy-density, easily stored, and easily transported high-value chemicals, playing a crucial role in ensuring energy security and achieving the "dual carbon" goal.

[0003] Currently, electrocatalytic CO2 reduction technology has evolved from early reactions under ambient temperature, atmospheric pressure, and neutral pH conditions with plate-plate electrodes as the core component to reaction systems under alkaline or acidic conditions with gas diffusion electrodes as the core component. However, existing technologies face serious salt and hydrogen evolution problems, preventing core indicators such as energy conversion efficiency, selectivity, current density, and stability from simultaneously meeting industrial application standards. Furthermore, most research in the field of electrocatalytic CO2 reduction technology focuses on electrocatalyst materials, theoretical foundations, and related basic applications under ambient pressure. However, the flue gas emitted in actual industrial production is mostly medium-to-high pressure gas at 2-3 MPa, making it difficult to directly connect existing reaction systems under ambient pressure conditions to industrial applications.

[0004] In recent years, some research teams have discovered that increasing the CO2 pressure on the gas supply side can increase the CO2 coverage on the catalyst surface and activate more CO2 reduction reaction sites on the catalyst surface. This provides a practical and effective approach for optimizing energy and mass transport within the three-phase interface microenvironment, and also allows for the direct application of high-pressure flue gas. Increasing the CO2 gas pressure can increase the solubility of CO2 in the electrolyte and improve the CO2 coverage on the catalyst surface, thereby enhancing product selectivity. In an alkaline electrolyte environment, increasing the CO2 pressure on the gas supply side can effectively promote the synthesis of multi-carbon products; in an acidic electrolyte environment, increasing the CO2 pressure on the gas supply side can also suppress hydrogen evolution without using methods such as metal cations.

[0005] Most existing electrocatalytic reduction high-pressure CO2 devices are based on H-type electrolyzers. While these devices are simple in structure and low in cost, their low current density and energy conversion efficiency, coupled with the inability to perform continuous reactions, limit their large-scale industrial application. High-pressure flow reactors, although capable of efficient mixing, improved mass transfer, and continuous operation, offer limited improvement in selectivity for target products and current density. Gas diffusion electrodes, however, can enhance mass transfer by constructing a three-phase interface near the catalyst, thereby significantly improving current density and energy conversion efficiency. In summary, high-pressure flow reactors coupled with gas diffusion electrodes represent the most promising technology for large-scale industrial application.

[0006] The challenge of coupling a gas diffusion electrode to a high-pressure flow reactor lies in the complex pressure control logic. When the reaction pressure is in the megapascal range, the pressure difference across the gas diffusion electrode must be controlled within 1% of the total pressure; otherwise, various problems such as electrode rupture and instability of the three-phase interface may occur. Existing pressure control logic mostly involves a high-pressure mass flow meter connected with multiple high-pressure constant flow pumps, multiple high-pressure back pressure valves, and pressure reducing valves to regulate the pressure across the gas diffusion electrode. However, this reaction system is overly complex and difficult to operate. Furthermore, the high-pressure mass flow meter, high-pressure constant flow pump, and high-pressure back pressure valve are too expensive, and daily maintenance is extremely complicated, limiting the large-scale promotion and industrial application of this reaction system. Therefore, developing a high-precision, low-cost high-pressure flow reactor coupled with a gas diffusion electrode is of great significance. Summary of the Invention

[0007] To overcome the limitations of existing high-pressure flow reactors coupled with gas diffusion electrodes, this invention provides a system and method for electrocatalytic reduction of high-pressure CO2. This system has high pressure control accuracy, no expensive components, low cost, and low operational complexity.

[0008] This invention is achieved through the following technical solution:

[0009] A system for electrocatalytic reduction of high-pressure CO2 includes: a high-pressure CO2 cylinder, a first pressure reducing valve, a check valve, a high-pressure constant flow pump, an electrochemical workstation, a pressure-resistant electrocatalytic reactor, and a pressure-resistant stainless steel container.

[0010] The high-pressure CO2 cylinder is connected to the inlet of the first pressure reducing valve, and the outlet of the first pressure reducing valve is connected to the cathode inlet of the pressure-resistant electrocatalytic reactor, and the cathode outlet of the pressure-resistant electrocatalytic reactor is connected to the gas inlet at the top of the pressure-resistant stainless steel container.

[0011] The outlet of the high-pressure constant flow pump is connected to the anode inlet of the pressure-resistant electrocatalytic reactor, and the anode outlet of the pressure-resistant electrocatalytic reactor is connected to the liquid inlet at the top of the pressure-resistant stainless steel container; the anode inlet of the pressure-resistant electrocatalytic reactor is connected to the cathode inlet of the pressure-resistant electrocatalytic reactor via a check valve.

[0012] The working electrode and counter electrode of the electrochemical workstation are connected to the cathode and anode of the pressure-resistant electrocatalytic reactor, respectively; the cathode of the pressure-resistant electrocatalytic reactor is a gas diffusion electrode loaded with an electrocatalytic CO2 reduction catalyst.

[0013] Preferably, the system for electrocatalytic reduction of high-pressure CO2 further includes a second pressure reducing valve and a gas chromatograph; the first gas outlet at the upper end of the pressure-resistant stainless steel container is connected to the inlet of the second pressure reducing valve; and the outlet of the second pressure reducing valve is connected to the gas chromatograph.

[0014] Furthermore, the electrocatalytic reduction system for high-pressure CO2 also includes a first needle valve, a storage tank, and a liquid chromatograph; the liquid outlet at the lower end of the pressure-resistant stainless steel container is connected to the inlet of the first needle valve, and the outlet of the first needle valve is connected to the storage tank.

[0015] Furthermore, the system for electrocatalytic reduction of high-pressure CO2 also includes a second needle valve and a vacuum pump; the second gas outlet at the lower end of the pressure-resistant stainless steel container is connected to the inlet of the second needle valve, and the outlet of the second needle valve is connected to the inlet of the vacuum pump.

[0016] Preferably, the system for electrocatalytic reduction of high-pressure CO2 further includes a first joint connector, a second joint connector, a third joint connector, and a fourth joint connector; the outlet of the first pressure reducing valve is connected to the cathode inlet of the pressure-resistant electrocatalytic reactor via the first joint connector; the cathode outlet of the pressure-resistant electrocatalytic reactor is connected to the upper gas inlet of the pressure-resistant stainless steel container via the fourth joint connector; the outlet of the high-pressure constant flow pump is connected to the anode inlet of the pressure-resistant electrocatalytic reactor via the second joint connector; the anode outlet of the pressure-resistant electrocatalytic reactor is connected to the upper liquid inlet of the pressure-resistant stainless steel container via the third joint connector; the working electrode clamp of the electrochemical workstation is connected to the stainless steel pipe between the first joint connector and the pressure-resistant electrocatalytic reactor, and the counter electrode clamp of the electrochemical workstation is connected to the stainless steel pipe between the third joint connector and the pressure-resistant electrocatalytic reactor; one end of the check valve is connected to the inlet of the first joint connector, and the other end is connected to the inlet of the second joint connector.

[0017] Furthermore, in the electrocatalytic reduction system for high-pressure CO2, a filter is connected between the first pressure reducing valve and the first joint connector, and a filter is connected between the high-pressure constant flow pump and the second joint connector.

[0018] A method for electrocatalytic reduction of high-pressure CO2, based on the system for electrocatalytic reduction of high-pressure CO2, includes:

[0019] S1. Open the valve of the high-pressure CO2 cylinder. The high-pressure CO2 gas in the high-pressure CO2 cylinder enters the pressure-resistant electrocatalytic reactor and the pressure-resistant stainless steel container in sequence through the first pressure reducing valve. Adjust the pressure gauge of the first pressure reducing valve to the pressure required for the operating point. After the pressure in the pressure-resistant stainless steel container is equal to the pressure of the first pressure reducing valve, turn on the high-pressure constant flow pump to pump the electrolyte into the pressure-resistant electrocatalytic reactor, and then into the pressure-resistant stainless steel container.

[0020] S2, turn on the electrochemical workstation and run it to the constant potential or constant current application stage. Run the high-voltage constant current pump to the reaction flow control stage to carry out the electrocatalytic reduction of high-pressure CO2.

[0021] A method for testing the electrocatalytic reduction of high-pressure CO2, based on the system for the electrocatalytic reduction of high-pressure CO2, includes:

[0022] S1. Open the valve of the high-pressure CO2 cylinder. The high-pressure CO2 gas in the high-pressure CO2 cylinder enters the pressure-resistant electrocatalytic reactor and the pressure-resistant stainless steel container in sequence through the first pressure reducing valve. Adjust the pressure reading of the first pressure reducing valve to the pressure required for the current operating point. After the total pressure reading of the second pressure reducing valve is the same as the pressure reading of the first pressure reducing valve, adjust the pressure reading of the second pressure reducing valve to atmospheric pressure. Turn on the high-pressure constant flow pump to pump the electrolyte into the pressure-resistant electrocatalytic reactor, and then into the pressure-resistant stainless steel container.

[0023] S2, turn on the electrochemical workstation and gas chromatograph, and run the electrochemical workstation to the constant potential or constant current application stage, while the high-pressure constant flow pump runs to the reaction flow control stage; after the constant potential or constant current application stage is completed, the high-pressure constant flow pump runs to the flushing flow stage, while the gas chromatograph runs to the chromatographic injection stage, and after the chromatographic injection stage is completed, the chromatographic analysis stage begins; after the flushing flow stage of the high-pressure constant flow pump is completed, close the valve of the high-pressure CO2 cylinder, and drain and collect all electrolyte in the pressure-resistant stainless steel container;

[0024] S3, return to S1, and proceed to the next working condition test, and so on, until all working condition tests are completed.

[0025] Preferably, in the method for testing the electrocatalytic reduction of high-pressure CO2, the system for electrocatalytic reduction of high-pressure CO2 further includes a first needle valve, a storage tank, and a liquid chromatograph; the liquid outlet at the lower end of the pressure-resistant stainless steel container is connected to the inlet of the first needle valve, and the outlet of the first needle valve is connected to the storage tank.

[0026] In S2, after the flushing flow stage of the high-pressure constant flow pump is completed, the valve of the high-pressure CO2 cylinder is closed, the first needle valve is opened, and all the electrolyte in the pressure-resistant stainless steel container is collected into the storage tank for liquid phase testing using liquid chromatography.

[0027] Furthermore, in the aforementioned test method for electrocatalytic reduction of high-pressure CO2, the system for electrocatalytic reduction of high-pressure CO2 further includes a second needle valve and a vacuum pump; the second gas outlet at the lower end of the pressure-resistant stainless steel container is connected to the inlet of the second needle valve, and the outlet of the second needle valve is connected to the inlet of the vacuum pump.

[0028] In step S2, after all the electrolyte in the pressure-resistant stainless steel container is collected into the storage tank, the second needle valve is opened and the vacuum pump is run to evacuate the pressure-resistant stainless steel container; after the pressure-resistant stainless steel container reaches the preset vacuum level, the vacuum pump is turned off, the first needle valve and the second needle valve are closed, and step S3 is executed.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] This invention relates to a system for the electrocatalytic reduction of high-pressure CO2. A pressure-resistant stainless steel container is installed after the pressure-resistant electrocatalytic reactor. Both the gaseous and liquid products from the reactor are introduced into this container, meaning the cathode gas path and anolyte liquid path of the reactor are connected within it. This ensures equal pressure in both paths, achieving pressure balance across the gas diffusion electrode. A check valve is also included to prevent electrolyte from entering the cathode. This invention eliminates the need for expensive high-pressure gas mass flow meters and back-pressure valves for pressure balance adjustment. High-precision pressure balance control is achieved through a low-cost check valve and pressure-resistant stainless steel container, resulting in lower overall cost and maintenance. The simple structure facilitates routine maintenance and scalability. Furthermore, this novel pressure balance logic achieves higher pressure control precision compared to high-pressure back-pressure valves and high-pressure mass flow meters. Under high-pressure conditions, this invention uses a gas diffusion electrode to create a three-phase interface near the catalyst, effectively improving CO2 mass transfer and significantly increasing the reaction current density. This invention enables electrocatalytic CO2 reduction within a pressure range of 0-5 MPa. High CO2 pressure effectively increases the solubility of CO2 in the electrolyte, thereby improving mass transfer and promoting the forward reaction. The system of this invention, through the setting of a high-pressure CO2 cylinder and a high-pressure constant flow pump, can carry out electrocatalytic CO2 reduction in a continuous flow reaction mode, thereby rapidly removing the liquid phase products on the catalyst surface, promoting product detachment, and timely replenishing pure electrolyte, thus accelerating the reaction from a kinetic perspective.

[0031] Furthermore, the pressure-resistant stainless steel container of this invention is connected to a gas chromatograph via a pressure-reducing valve and to a storage tank via a needle valve. Therefore, continuous testing under different operating conditions can be achieved without disassembling the reactor, integrating the acquisition and detection of gaseous products and the collection of liquid products. This simplifies operation and saves testing time, accurately evaluating the electrocatalytic CO2 reduction performance under high-pressure conditions. For continuous testing at multiple operating points, this invention avoids interference from unknown factors such as reactor disassembly and reassembly between different operating points in traditional systems, thus significantly improving the accuracy of catalyst performance evaluation. For multiple tests at a specific operating point, this invention employs a continuous flow reaction mode, ensuring that the catalyst interface is always covered by product-free electrolyte.

[0032] Furthermore, the present invention connects a vacuum pump after the pressure-resistant stainless steel container. After the test is completed, the vacuum pump can be used to evacuate the container, thereby avoiding the influence of residual gas on the next test.

[0033] Furthermore, the present invention provides insulating joints at the cathode inlet, cathode outlet, anode inlet, and anode outlet of the pressure-resistant electrocatalytic reactor, which can serve as insulation when the cathode and anode are pressurized at the electrochemical workstation.

[0034] Furthermore, the present invention includes filters in both the gas and liquid pathways to ensure the purity of the gas and electrolyte and prevent impurities from affecting the reaction. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of the electrocatalytic reduction system for high-pressure CO2 of the present invention.

[0037] Figure 2 This is a schematic diagram of the continuous test results obtained in Example 1 using pure Ag as a catalyst.

[0038] Figure 3 This is a schematic diagram of the continuous test results obtained in Example 2 using pure Ag as a catalyst. Detailed Implementation

[0039] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0040] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0041] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not intended to limit the order of the method steps or define the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0042] Furthermore, it should be noted that the terms "first," "second," etc., used in this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. The terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In addition, unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements.

[0043] like Figure 1As shown, the electrocatalytic reduction system for high-pressure CO2 of the present invention includes: a high-pressure CO2 cylinder 1, a first pressure reducing valve 2, a second pressure reducing valve 24, a first filter 3, a second filter 5, a high-pressure constant flow pump 4, a check valve 6, a first connecting joint 7, a second connecting joint 9, a third connecting joint 11, a fourth connecting joint 12, an electrochemical workstation 8, a pressure-resistant electrocatalytic reactor 10, a pressure-resistant stainless steel container 16, a first needle valve 19, a second needle valve 20, a storage tank 22, a liquid chromatograph 23, a gas chromatograph 25, and a vacuum pump 21. The computer contains control software for the electrochemical workstation 8, the liquid chromatograph 23, and the gas chromatograph 25. The pressure-resistant stainless steel container 16 has a gas inlet 13, a liquid inlet 14, and a first gas outlet 15 at its upper end, and a liquid outlet 18 and a second gas outlet 17 at its lower end. Each operating point corresponds to a storage tank 22.

[0044] The high-pressure CO2 cylinder 1 is connected to the inlet of the first pressure reducing valve 2. The inlet of the first filter 3 is connected to the outlet of the first pressure reducing valve 2. The outlet of the first filter 3 is connected to the inlet of the first combined connector 7. The outlet of the first combined connector 7 is connected to the cathode inlet of the pressure-resistant electrocatalytic reactor 10. The cathode outlet of the pressure-resistant electrocatalytic reactor 10 is connected to the inlet of the fourth combined connector 12. The outlet of the fourth combined connector 12 is connected to the upper gas inlet 13 of the pressure-resistant stainless steel container 16. The high-pressure CO2 cylinder 1, the first pressure reducing valve 2, the first filter 3, the first combined connector 7, the pressure-resistant electrocatalytic reactor 10, the fourth combined connector 12, and the pressure-resistant stainless steel container 16 are connected sequentially by stainless steel pipes.

[0045] The outlet of the high-pressure constant flow pump 4 is connected to the inlet of the second filter 5, the outlet of the second filter 5 is connected to the inlet of the second joint connector 9, and the outlet of the second joint connector 9 is connected to the anode inlet of the pressure-resistant electrocatalytic reactor 10. The anode outlet of the pressure-resistant electrocatalytic reactor 10 is connected to the inlet of the third joint connector 11. The outlet of the third joint connector 11 is connected to the liquid inlet 14 at the upper end of the pressure-resistant stainless steel container 16. The high-pressure constant flow pump 4, the second filter 5, the second joint connector 9, the pressure-resistant electrocatalytic reactor 10, the third joint connector 11, and the pressure-resistant stainless steel container 16 are all connected by stainless steel pipes. In addition, the outlet of the first filter 3 is also connected to the outlet of the second filter 5 via a check valve 6.

[0046] The working electrode clamp of the electrochemical workstation 8 is connected to the stainless steel pipe between the first joint 7 and the pressure-resistant electrocatalytic reactor 10, and the counter electrode clamp is connected to the stainless steel pipe between the third joint 11 and the pressure-resistant electrocatalytic reactor 10.

[0047] The upper gas outlet 15 of the pressure-resistant stainless steel container 16 is connected to the inlet of the second pressure-reducing valve 24, and the outlet of the second pressure-reducing valve 24 is connected to the gas chromatograph 25. The lower gas outlet 17 of the pressure-resistant stainless steel container 16 is connected to the inlet of the second needle valve 20, and the outlet of the second needle valve 20 is connected to the inlet of the vacuum pump 21. The lower liquid outlet 18 of the pressure-resistant stainless steel container 16 is connected to the inlet of the first needle valve 19, and the outlet of the first needle valve 19 is connected to the liquid storage tank 22. The liquid in the liquid storage tank 22 is sent to the liquid chromatograph 23 for product detection and analysis.

[0048] The pressure-resistant electrocatalytic reactor 10 includes a cathode plate, a polytetrafluoroethylene (PTFE) gasket, and an anode plate. A cathode is sealed between the cathode plate and the PTFE gasket, and an anode is installed between the anode plate and the PTFE gasket. The cathode plate is connected to the working electrode of an electrochemical workstation, and the anode plate is connected to the counter electrode of the electrochemical workstation. The cathode is a gas diffusion electrode loaded with an electrocatalytic CO2 reduction catalyst. A CO2 gas flow channel is provided on the side of the cathode plate opposite to the cathode, and a liquid chamber is provided on the side of the anode plate opposite to the anode. The CO2 gas flow channel and the liquid chamber are separated, allowing the use of a high-concentration, strongly alkaline solution as the electrolyte, thereby effectively improving the selectivity of the target product and the overall energy conversion efficiency of the device.

[0049] In this invention, the cathode inlet of the pressure-resistant electrocatalytic reactor 10 is connected to one end of the CO2 gas flow channel, and the cathode outlet of the pressure-resistant electrocatalytic reactor 10 is connected to the other end of the CO2 gas flow channel. The anode inlet of the pressure-resistant electrocatalytic reactor 10 is connected to one end of the liquid chamber, and the anode outlet of the pressure-resistant electrocatalytic reactor 10 is connected to the other end of the liquid chamber.

[0050] The electrochemical workstation 8, gas chromatograph 25, and liquid chromatograph 23 are all connected to the computer via data cables. The control software for the electrochemical workstation 8 is Nova 2.1.7, and the control software for the gas chromatograph 25 is OpenLAB ControlPanel.

[0051] The gas chromatograph 25 includes a TCD detector for detecting the hydrogen concentration in the gas, and two FID detectors for detecting the concentrations of methane, ethylene, and carbon monoxide in the gas. The gas chromatograph 25 is internally equipped with a ten-way valve to separate different types of products in the gas and direct them to their corresponding detectors.

[0052] The system described in this invention can be divided into an electrochemical module, a gas flow module, an electrolyte flow module, and a chromatographic sample analysis module.

[0053] The electrochemical module includes an electrochemical workstation 8, a pressure-resistant electrocatalytic reactor 10, a first connecting connector 7, a second connecting connector 9, a third connecting connector 11, and a fourth connecting connector 12. The electrochemical workstation 8 applies a constant potential or constant current for each test operating point, applying the corresponding constant potential or constant current between the cathode and anode of the pressure-resistant electrocatalytic reactor 10 and collecting data. The first connecting connector 7, the second connecting connector 9, the third connecting connector 11, and the fourth connecting connector 12 serve as insulation, ensuring that the potential or current is applied only to the pressure-resistant electrocatalytic reactor 10.

[0054] The gas flow module includes a high-pressure CO2 cylinder 1, a first pressure reducing valve 2, a second pressure reducing valve 24, a first filter 3, a first connecting joint 7, a fourth connecting joint 12, and a pressure-resistant stainless steel container 16. The outlet of the high-pressure CO2 cylinder 1 is connected to the first pressure reducing valve 2. After flowing out of the first pressure reducing valve 2, the high-pressure CO2 gas is filtered by the first filter 3 and then enters the cathode of the pressure-resistant electrocatalytic reactor 10 through the first connecting joint 7. The gaseous products generated after the electrocatalytic reduction reaction flow along with the CO2 gas through the fourth connecting joint 12 and the gas inlet 13 of the pressure-resistant stainless steel container 16 into the pressure-resistant stainless steel container 16. The first gas outlet 15 at the upper end of the pressure-resistant stainless steel container 16 is connected to the second pressure reducing valve 24. After the gas flows through the second pressure reducing valve 24, its partial pressure is reduced to atmospheric pressure, and then it is introduced into a gas chromatograph 25.

[0055] The electrolyte flow module includes a high-pressure constant flow pump 4, a second filter 5, a second connecting connector 9, a third connecting connector 11, a pressure-resistant stainless steel container 16, a first needle valve 19, and a storage tank 22. During the test, the electrolyte is pressurized by the high-pressure constant flow pump 4 and flows through the second filter 5. After filtration, it enters the anode of the pressure-resistant electrocatalytic reactor 10 through the second connecting connector 9. The liquid products generated by the reaction flow together with the electrolyte through the third connecting connector 11 and into the pressure-resistant stainless steel container 16. After passing through the first needle valve 19, it enters the storage tank 22 and is then sent to the liquid chromatography 23 for product detection and analysis. Specifically, during the test, the high-pressure constant flow pump 4 sequentially performs a reaction flow control process and a rinsing flow control process. The reaction flow control process is set when the electrochemical workstation 8 applies potential or current, and the first needle valve 19 is closed at the same time. After the high-pressure constant flow pump 4 finishes the rinsing flow control process, the first needle valve 19 is opened, and the electrolyte in the pressure-resistant stainless steel container 16 is collected in the storage tank 22.

[0056] The chromatographic sample analysis module mainly includes a gas chromatograph 25. During a single-set chromatographic test, the gas chromatograph 25 is divided into a chromatographic injection stage and a chromatographic analysis stage, with the analysis stage including product analysis and exhaust gas purging. The running time of the chromatographic test module must match the time of the electrochemical module. Specifically, after the electrochemical workstation 8 completes the potential or current application stage and the high-pressure constant flow pump 4 completes the reaction flow control stage, the gas chromatograph 25 is run to the chromatographic injection stage. Simultaneously, it is ensured that the sum of the potential or current application stage and the waiting stage of the electrochemical workstation 8 is equal to the sum of the chromatographic injection stage and the chromatographic analysis stage of the gas chromatograph 25. The chromatographic injection stage is very short, approximately tens of seconds, followed by the chromatographic analysis stage. The time corresponding to the chromatographic analysis stage at the first operating point is equal to the flow purging time of the high-pressure constant flow pump at the first operating point and the flow control time of the high-pressure constant flow pump at the second operating point, and so on.

[0057] In one specific embodiment of the present invention, the control software for the electrochemical module is Nova 2.1.7. By using the programming module of this software, the time t1 for constant potential or constant current of the electrochemical workstation 8 is set and the relevant electrochemical signals are collected.

[0058] In this invention, the pressure required for the test operating point is met by adjusting the pressure distribution of the first pressure reducing valve 2 in the gas flow module.

[0059] In one specific embodiment of the present invention, the reaction flow rate q1 and the flushing flow rate q2 are controlled by adjusting the flow rate of the high-pressure constant flow pump 4, wherein the time corresponding to the reaction flow rate q1 is t2 and the time corresponding to the flushing flow rate is t3.

[0060] In one specific embodiment of the present invention, the control software of the chromatographic sample analysis module is OpenLAB Control Panel, which is used to control the gas chromatography to continuously perform chromatographic injection and chromatographic analysis under different test conditions. The time corresponding to a single set of chromatographic test runs is t4. During continuous testing, the chromatographic sample analysis module is equipped with control program modules that are consistent with the number of test condition points. Each control program module corresponds one-to-one with a test condition point, and each control program module controls the single set of chromatographic test runs for the corresponding test condition point.

[0061] The system described above can continuously and quantitatively analyze gaseous product components under different test conditions. During the test at each test point, the high-pressure constant flow pump operates sequentially in the reaction flow control stage and the flushing flow control stage, while the gas chromatography operates sequentially in the chromatographic injection stage and the chromatographic analysis stage. The electrochemical workstation's constant potential or constant current application stage is synchronized with the high-pressure constant flow pump's reaction flow control stage; the chromatographic injection stage begins after the electrochemical workstation's constant potential or constant current application stage has ended.

[0062] This invention provides a test method for the continuous flow electrocatalytic reduction of high-pressure CO2, based on the system, comprising the following steps:

[0063] Step 1: After assembling the system described in this invention, close all valves. Open the valve of the high-pressure CO2 cylinder 1. After ensuring that the total pressure reading of the first pressure reducing valve 2 is stable, adjust the partial pressure reading of the first pressure reducing valve 2 to the pressure P1 required for the test condition. Once the total pressure reading of the second pressure reducing valve 24 is the same as the partial pressure reading of the first pressure reducing valve 2, adjust the partial pressure reading of the second pressure reducing valve 24 to atmospheric pressure and record its pressure as P0.

[0064] Step 2: Turn on the high-pressure constant flow pump 4 and set its flow rate to 8 mL / min. After running for 3 minutes, open the first needle valve 19 to drain all the electrolyte from the pressure-resistant stainless steel container 16, and then close the first needle valve 19. The purpose of this step is to check the tubing for patency, prevent leakage, and simultaneously fill the tubing with electrolyte.

[0065] Step 3: In the Nova 2.1.7 control software for the electrochemical module and the OpenLABControl Panel control software for the chromatographic sample analysis module, set up control program modules with the same number of test conditions as the test conditions, and control the single-group chromatographic test operation process of the corresponding conditions.

[0066] Step 4: Conduct the first operating point test. The electrochemical workstation 8 is run to the constant potential or constant current application stage, and the high-voltage constant flow pump 4 is run to the reaction flow rate q1 control stage, pumping fresh electrolyte into the pressure-resistant electrocatalytic reactor 10. After the running time t1 ends, the electrochemical workstation 8 adjusts the flow rate of the high-voltage constant flow pump 4 to the flushing flow rate q2, flushing the residual liquid phase products in the pressure-resistant electrocatalytic reactor 10 and connecting pipelines into the pressure-resistant stainless steel container 16. Simultaneously, the gas chromatograph 25 is run to the chromatographic injection stage, and chromatographic analysis is performed after injection. After flushing, the valve of the high-pressure CO2 cylinder 1 is closed, and the first needle valve 19 is opened to collect all the electrolyte in the pressure-resistant stainless steel container 16 into the storage tank 22, completing the first operating point test.

[0067] Step 5: After the first operating point test is completed, open the second needle valve 20 and run the vacuum pump 21 for a running time of m. The selection criterion for m is to ensure that all the gas in the pressure-resistant stainless steel container 16 is completely extracted to avoid affecting the gas phase product detection at the next operating point.

[0068] Step 6: Turn off vacuum pump 21, close first needle valve 19 and second needle valve 20, repeat step 1 to test the second operating point, and so on, to complete the test of all operating points.

[0069] In the specific embodiment, t1 = t2 = 3 min, t3 = 3 min, t4 = 6 min, m = 3 min, q1 = 10 mL / min, q2 = 8 mL / min.

[0070] Example 1

[0071] Carbon paper was cut into circles with a diameter of 15 cm, and then a 500 nm thick layer of pure Ag catalyst was sputtered onto its surface using an electron beam evaporation coating apparatus to obtain a gas diffusion electrode loaded with pure Ag. This Ag-loaded gas diffusion electrode was used as the cathode, and an 80 μm thick nickel mesh was selected as the anode. The prepared cathode and anode were assembled in a pressure-resistant electrocatalytic reactor 10, using a 1.5 M KOH solution as the electrolyte. All components were assembled and connected according to the above instructions. The partial pressure of the first pressure reducing valve 2 was adjusted to 1 MPa, and the test results are as follows. Figure 2 As shown, the system of the present invention can achieve good CO2 reduction performance over a wide current density range at a pressure of 1 MPa.

[0072] Example 2

[0073] Carbon paper was cut into circles with a diameter of 15 cm, and then a 500 nm thick layer of pure Ag catalyst was sputtered onto its surface using an electron beam evaporation coating apparatus to obtain a gas diffusion electrode loaded with pure Ag. The Ag-loaded gas diffusion electrode was used as the cathode, and an 80 μm thick nickel mesh was selected as the anode. The prepared cathode and anode were assembled in a pressure-resistant electrocatalytic reactor 10, using a 1.5 M KOH solution as the electrolyte. All devices were assembled and connected according to the above instructions. The partial pressure of the first pressure reducing valve 2 was adjusted to 3 MPa, and the test results are as follows. Figure 3 As shown, the system of the present invention can achieve good CO2 reduction performance over a wide current density range at a pressure of 3 MPa.

Claims

1. A system for the electrocatalytic reduction of high-pressure CO2, characterized in that, include: High-pressure CO2 cylinder (1), first pressure reducing valve (2), check valve (6), high-pressure constant flow pump (4), electrochemical workstation (8), pressure-resistant electrocatalytic reactor (10) and pressure-resistant stainless steel container (16). The high-pressure CO2 cylinder (1) is connected to the inlet of the first pressure reducing valve (2), the outlet of the first pressure reducing valve (2) is connected to the cathode inlet of the pressure-resistant electrocatalytic reactor (10), and the cathode outlet of the pressure-resistant electrocatalytic reactor (10) is connected to the gas inlet (13) at the top of the pressure-resistant stainless steel container (16). The outlet of the high-pressure constant flow pump (4) is connected to the anode inlet of the pressure-resistant electrocatalytic reactor (10), and the anode outlet of the pressure-resistant electrocatalytic reactor (10) is connected to the upper liquid inlet (14) of the pressure-resistant stainless steel container (16); the anode inlet of the pressure-resistant electrocatalytic reactor (10) is connected to the cathode inlet of the pressure-resistant electrocatalytic reactor (10) through a check valve (6); The working electrode and counter electrode of the electrochemical workstation (8) are respectively connected to the cathode and anode of the pressure-resistant electrocatalytic reactor; the cathode of the pressure-resistant electrocatalytic reactor is a gas diffusion electrode loaded with an electrocatalytic CO2 reduction catalyst.

2. The system for electrocatalytic reduction of high-pressure CO2 according to claim 1, characterized in that, It also includes a second pressure reducing valve (24) and a gas chromatograph (25); the first gas outlet (15) at the upper end of the pressure-resistant stainless steel container (16) is connected to the inlet of the second pressure reducing valve (24); the outlet of the second pressure reducing valve (24) is connected to the gas chromatograph (25).

3. The system for electrocatalytic reduction of high-pressure CO2 according to claim 2, characterized in that, It also includes a first needle valve (19), a storage tank (22) and a liquid chromatograph (23); the liquid outlet (18) at the lower end of the pressure-resistant stainless steel container (16) is connected to the inlet of the first needle valve (19), and the outlet of the first needle valve (19) is connected to the storage tank (22).

4. The system for electrocatalytic reduction of high-pressure CO2 according to claim 3, characterized in that, It also includes a second needle valve (20) and a vacuum pump (21); the second gas outlet (17) at the lower end of the pressure-resistant stainless steel container (16) is connected to the inlet of the second needle valve (20), and the outlet of the second needle valve (20) is connected to the inlet of the vacuum pump (21).

5. The system for electrocatalytic reduction of high-pressure CO2 according to claim 1, characterized in that, It also includes a first joint connector (7), a second joint connector (9), a third joint connector (11), and a fourth joint connector (12); the outlet of the first pressure reducing valve (2) is connected to the cathode inlet of the pressure-resistant electrocatalytic reactor (10) via the first joint connector (7); the cathode outlet of the pressure-resistant electrocatalytic reactor (10) is connected to the upper gas inlet (13) of the pressure-resistant stainless steel container (16) via the fourth joint connector (12); the outlet of the high-pressure constant flow pump (4) is connected to the anode inlet of the pressure-resistant electrocatalytic reactor (10) via the second joint connector (9); the pressure-resistant electrocatalytic reactor The anode outlet of the device (10) is connected to the liquid inlet (14) at the upper end of the pressure-resistant stainless steel container (16) via the third joint connector (11); the working electrode clamp of the electrochemical workstation (8) is connected to the stainless steel pipe between the first joint connector (7) and the pressure-resistant electrocatalytic reactor (10); the counter electrode clamp of the electrochemical workstation (8) is connected to the stainless steel pipe between the third joint connector (11) and the pressure-resistant electrocatalytic reactor (10); one end of the check valve (6) is connected to the inlet of the first joint connector (7), and the other end is connected to the inlet of the second joint connector (9).

6. The system for electrocatalytic reduction of high-pressure CO2 according to claim 5, characterized in that, A filter is connected between the first pressure reducing valve (2) and the first joint connector (7), and a filter is connected between the high-pressure constant flow pump (4) and the second joint connector (9).

7. A method for electrocatalytic reduction of high-pressure CO2, characterized in that, The system based on any one of claims 1-6 includes: S1, open the valve of the high-pressure CO2 cylinder (1), the high-pressure CO2 gas in the high-pressure CO2 cylinder (1) enters the pressure-resistant electrocatalytic reactor (10) and the pressure-resistant stainless steel container (16) in sequence through the first pressure reducing valve (2), adjust the pressure of the pressure gauge of the first pressure reducing valve (2) to the pressure required for the working point, after the pressure in the pressure-resistant stainless steel container (16) is equal to the pressure of the first pressure reducing valve (2), turn on the high-pressure constant flow pump (4) to pump the electrolyte into the pressure-resistant electrocatalytic reactor (10), and then into the pressure-resistant stainless steel container (16); S2, turn on the electrochemical workstation (8), run the electrochemical workstation (8) to the constant potential or constant current application stage, and run the high-pressure constant flow pump (4) to the reaction flow control stage to carry out the electrocatalytic reduction of high-pressure CO2.

8. A test method for the electrocatalytic reduction of high-pressure CO2, characterized in that, The system based on claim 2 includes: S1, open the valve of the high-pressure CO2 cylinder (1), and the high-pressure CO2 gas in the high-pressure CO2 cylinder (1) enters the pressure-resistant electrocatalytic reactor (10) and the pressure-resistant stainless steel container (16) in sequence through the first pressure reducing valve (2). Adjust the pressure reading of the partial pressure of the first pressure reducing valve (2) to the pressure required for the current operating point. After the total pressure reading of the second pressure reducing valve (24) is the same as the pressure reading of the partial pressure of the first pressure reducing valve (2), adjust the pressure reading of the second pressure reducing valve (24) to the normal pressure. Turn on the high-pressure constant flow pump (4) to pump the electrolyte into the pressure-resistant electrocatalytic reactor (10) and then into the pressure-resistant stainless steel container (16). S2, turn on the electrochemical workstation (8) and gas chromatograph, run the electrochemical workstation (8) to the constant potential or constant current application stage, and at the same time run the high-pressure constant flow pump (4) to the reaction flow control stage; after the constant potential or constant current application stage is completed, the high-pressure constant flow pump (4) runs to the flushing flow stage, and at the same time, the gas chromatograph (25) runs to the chromatographic injection stage. After the chromatographic injection stage is completed, the chromatographic analysis stage is entered; after the flushing flow stage of the high-pressure constant flow pump (4) is completed, close the valve of the high-pressure CO2 cylinder (1), and discharge and collect all the electrolyte in the pressure-resistant stainless steel container (16); S3, return to S1, and proceed to the next working condition test, and so on, until all working condition tests are completed.

9. The test method for electrocatalytic reduction of high-pressure CO2 according to claim 8, characterized in that, The electrocatalytic reduction system for high-pressure CO2 also includes a first needle valve (19), a storage tank (22), and a liquid chromatograph (23); the liquid outlet (18) at the lower end of the pressure-resistant stainless steel container (16) is connected to the inlet of the first needle valve (19), and the outlet of the first needle valve (19) is connected to the storage tank (22); In S2, after the flushing flow stage of the high-pressure constant flow pump (4) is completed, the valve of the high-pressure CO2 cylinder (1) is closed, the first needle valve (19) is opened, and all the electrolyte in the pressure-resistant stainless steel container (16) is collected into the storage tank (22) and liquid phase test is performed by liquid chromatography.

10. The test method for electrocatalytic reduction of high-pressure CO2 according to claim 9, characterized in that, The electrocatalytic reduction system for high-pressure CO2 also includes a second needle valve (20) and a vacuum pump (21); the second gas outlet (17) at the lower end of the pressure-resistant stainless steel container (16) is connected to the inlet of the second needle valve (20), and the outlet of the second needle valve (20) is connected to the inlet of the vacuum pump (21); In S2, after all the electrolyte in the pressure-resistant stainless steel container (16) is collected into the storage tank (22), the second needle valve (20) is opened and the vacuum pump (21) is run to evacuate the pressure-resistant stainless steel container (16); after the pressure-resistant stainless steel container (16) reaches the preset vacuum level, the vacuum pump (21) is turned off, the first needle valve (19) and the second needle valve (20) are closed, and S3 is executed.

Images