System and method for electrocatalytic reduction of high-pressure CO2

Abstract

The invention provides a system and a method for electrocatalytic reduction of high-pressure CO2, the system for electrocatalytic reduction of high-pressure CO2 is provided with a pressure-resistant stainless steel container behind a pressure-resistant electric catalytic reactor, and both a gas product and a liquid product led out from the pressure-resistant electric catalytic reactor are introduced into the pressure-resistant stainless steel container; namely, the cathode gas passage and the anode liquid passage of the pressure-resistant electric catalytic reactor are communicated in the pressure-resistant stainless steel container, so that the pressure of the cathode gas passage and the pressure of the anode liquid passage are equal, and the pressure balance of the two sides of the gas diffusion electrode is realized. Meanwhile, in order to prevent the electrolyte from entering the cathode, a check valve is arranged. According to the pressure balance control device, pressure balance is adjusted without expensive accessories such as a high-pressure gas mass flow control meter and a high-pressure back pressure valve, high-precision pressure balance control is achieved through the low-cost check valve and the pressure-resistant stainless steel container, the overall manufacturing cost and the follow-up maintenance cost are low, the structure is simple, and daily maintenance and scale amplification are facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of CO2 reduction, and relates to a system and method for electrocatalytic reduction of high-pressure CO2. Background Art

[0002] Coal, as the main energy source for mankind, determines that carbon emissions will continue for a considerable period of time. Therefore, in the process of achieving the "dual carbon" goal, it is necessary to promote green and low-carbon technology innovation. In this context, electrocatalytic CO2 reduction technology can obtain high value-added chemicals and fuels such as carbon monoxide, methane, formic acid, methanol, ethylene, ethanol, etc. while reducing carbon emissions. After coupling with wind power and photovoltaic power generation, this technology can also convert renewable energy with low energy density, strong dispersion, instability and discontinuity into clean, pollution-free, high energy density, easy to store and easy to transport high-value chemicals, which plays a vital role in ensuring energy security and achieving the "dual carbon" goal.

[0003] At present, electrocatalytic CO2 reduction technology has developed from the early reaction under normal temperature, normal pressure and neutral pH environment with flat plate electrodes as the core components to the reaction system under alkaline or acidic environment with gas diffusion electrodes as the core components. However, the existing technology faces serious problems of salt precipitation and hydrogen precipitation, so that the core indicators of the technology such as energy conversion efficiency, selectivity, current density and stability cannot meet the industrial application standards at the same time. Moreover, in the research in the field of electrocatalytic CO2 reduction technology, most of the research focuses on electrocatalyst materials, theoretical basis and related basic applications under normal pressure environment. However, the flue gas emitted in actual industrial production is mostly medium- and high-pressure gas of 2~3MPa, and the existing reaction system under normal pressure conditions is difficult to directly connect to industrial applications.

[0004] In recent years, some research teams have found 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, providing a practical and effective way to optimize the energy and mass transfer in the three-phase interface microenvironment. At the same time, high-pressure flue gas can be directly applied. Increasing the CO2 gas pressure can increase the solubility of CO2 in the electrolyte and increase the coverage of CO2 on the catalyst surface, thereby improving the selectivity of the product. 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 of the existing electrocatalytic reduction of high-pressure CO2 devices remain at the H-type electrolytic cell. This type of device has a simple structure and low cost, but the current density and energy conversion efficiency are low and it cannot react continuously, which limits its large-scale industrial application. Although the high-pressure flow-type reaction cell can efficiently mix, improve mass transfer, and operate continuously, its selectivity for the target product and improvement in current density are very limited. The gas diffusion electrode can enhance mass transfer by constructing a three-phase interface near the catalyst, thereby significantly improving the current density and energy conversion efficiency. Overall, the high-pressure flow-type reactor coupled with the gas diffusion electrode is the most promising technology for large-scale industrial application.

[0006] The difficulty of coupling high-pressure flow reactors with gas diffusion electrodes lies in the complex pressure control logic. When the reaction pressure is at the MPa level, the pressure difference on both sides of the gas diffusion electrode must be controlled within 1% of the total pressure, otherwise there will be a variety of problems such as electrode rupture and instability of the three-phase interface of the reaction. Most of the existing pressure control logics are high-pressure mass flow controllers combined with multiple high-pressure constant current pumps, multiple high-pressure back pressure valves, and pressure reducing valves to regulate the pressure on both sides of the gas diffusion electrode. However, this reaction system is too complicated and difficult to operate. At the same time, the cost of components such as high-pressure mass flow controllers, high-pressure constant current pumps, and high-pressure back pressure valves is too expensive, and daily repairs and maintenance are very complicated, which limits the large-scale promotion and industrial application of this reaction system. Therefore, it is of great significance to develop a high-precision, low-cost reaction device for coupling high-pressure flow reactors with gas diffusion electrodes. Summary of the invention

[0007] In order to overcome the limitations of existing high-pressure flow reactors coupled with gas diffusion electrodes, the present invention provides a system and method for electrocatalytic reduction of high-pressure CO2, which has high pressure control accuracy, no expensive components, low cost, and low operation complexity.

[0008] The present invention is achieved through the following technical solutions: A system for electrocatalytic reduction of high-pressure CO2, comprising: a high-pressure CO2 gas cylinder, a first pressure reducing valve, a check valve, a high-pressure constant-current pump, an electrochemical workstation, a pressure-resistant electrocatalytic reactor and a pressure-resistant stainless steel container; The high-pressure CO2 gas cylinder is connected to the inlet of the first pressure reducing valve, 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 upper end of the pressure-resistant stainless steel container; The outlet of the high-pressure constant-current 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 upper end 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 through a check valve; The working electrode and the counter electrode of the electrochemical workstation are respectively connected to the cathode and the 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.

[0009] 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.

[0010] Furthermore, the system for electrocatalytic reduction of high-pressure CO2 also includes a first needle valve, a liquid storage tank and a liquid chromatography; 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 liquid storage tank.

[0011] 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 second needle valve inlet, and the second needle valve outlet is connected to the vacuum pump inlet.

[0012] Preferably, the system for electrocatalytic reduction of high-pressure CO2 also includes a first joint, a second joint, a third joint, and a fourth joint; the outlet of the first pressure reducing valve is connected to the cathode inlet of the pressure-resistant electrocatalytic reactor via the first joint; 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; the outlet of the high-pressure constant current pump is connected to the anode inlet of the pressure-resistant electrocatalytic reactor via the second joint; 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; the working electrode electrode clamp of the electrochemical workstation is connected to the stainless steel pipe between the first joint and the pressure-resistant electrocatalytic reactor, and the counter electrode electrode clamp of the electrochemical workstation is connected to the stainless steel pipe between the third joint and the pressure-resistant electrocatalytic reactor; one end of the check valve is connected to the inlet of the first joint, and the other end is connected to the inlet of the second joint.

[0013] Furthermore, in the system for electrocatalytic reduction of 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-current pump and the second joint connector.

[0014] A method for electrocatalytic reduction of high-pressure CO2, based on a system for electrocatalytic reduction of high-pressure CO2, comprising: S1, open the valve of the high-pressure CO2 gas cylinder, the high-pressure CO2 gas in the high-pressure CO2 gas cylinder enters the pressure-resistant electrocatalytic reactor and the pressure-resistant stainless steel container in sequence through the first pressure reducing valve, adjust the partial pressure indication of the first pressure reducing valve to the pressure required by the operating point, and after the pressure in the pressure-resistant stainless steel container is equal to the partial pressure of the first pressure reducing valve, turn on the high-pressure constant current pump to pump the electrolyte into the pressure-resistant electrocatalytic reactor and then into the pressure-resistant stainless steel container; S2, turn on the electrochemical workstation, run the electrochemical workstation to the constant potential or constant current application stage, run the high-voltage constant current pump to the reaction flow control stage, and perform the electrocatalytic reduction of high-pressure CO2.

[0015] A method for testing electrocatalytic reduction of high-pressure CO2, based on a system for electrocatalytic reduction of high-pressure CO2, comprising: S1, open the valve of the high-pressure CO2 gas cylinder, the high-pressure CO2 gas in the high-pressure CO2 gas cylinder enters the pressure-resistant electrocatalytic reactor and the pressure-resistant stainless steel container in sequence through the first pressure reducing valve, adjust the partial pressure indication number of the first pressure reducing valve to the pressure required at the current operating point, and after the total pressure indication number of the second pressure reducing valve is the same as the partial pressure indication number of the first pressure reducing valve, adjust the partial pressure indication number of the second pressure reducing valve to normal pressure; turn on the high-pressure constant current pump to pump the electrolyte into the pressure-resistant electrocatalytic reactor, and then into the pressure-resistant stainless steel container; S2, turn on the electrochemical workstation and the gas chromatograph, run the electrochemical workstation to the constant potential or constant current application stage, and at the same time, run the high-voltage constant current pump to the reaction flow control stage; after the constant potential or constant current application stage is completed, the high-voltage constant current pump runs to the flushing flow stage, and at the same time, the gas chromatograph runs to the chromatographic injection stage, and after the chromatographic injection stage is completed, it enters the chromatographic analysis stage; after the flushing flow stage of the high-voltage constant current pump is completed, close the high-pressure CO2 gas cylinder valve, and discharge and collect all the electrolyte in the pressure-resistant stainless steel container; S3, return to S1, and test the next operating point, and so on, until the tests of all operating points are completed.

[0016] Preferably, in the test method for electrocatalytic reduction of high-pressure CO2, the system for electrocatalytic reduction of high-pressure CO2 further comprises a first needle valve, a liquid 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 liquid storage tank; In S2, after the flushing flow stage of the high-pressure constant-current pump is completed, the high-pressure CO2 cylinder valve is closed, the first needle valve is opened, all the electrolyte in the pressure-resistant stainless steel container is collected into the liquid storage tank, and liquid chromatography is used for liquid phase testing.

[0017] Furthermore, in the test method for electrocatalytic reduction of high-pressure CO2, 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; In S2, after all the electrolyte in the pressure-resistant stainless steel container is collected into the liquid storage tank, the second needle valve is opened and the vacuum pump is operated to evacuate the pressure-resistant stainless steel container; after the pressure-resistant stainless steel container reaches a preset vacuum degree, the vacuum pump is turned off, the first needle valve and the second needle valve are closed, and S3 is executed.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The system for electrocatalytic reduction of high-pressure CO2 of the present invention is provided with a pressure-resistant stainless steel container after the pressure-resistant electrocatalytic reactor, and the gaseous products and liquid products drawn from the pressure-resistant electrocatalytic reactor are both passed 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 connected in the pressure-resistant stainless steel container, so that the pressure of the cathode gas passage and the anode liquid passage are equal, that is, the pressure balance on both sides of the gas diffusion electrode is achieved. At the same time, in order to prevent the electrolyte from entering the cathode, a check valve is provided. The present invention does not require expensive high-pressure gas mass flow controllers, high-pressure back pressure valves and other accessories to adjust the pressure balance, and high-precision pressure balance control is achieved through low-cost check valves and pressure-resistant stainless steel containers. The overall cost and subsequent maintenance costs are low, the structure is simple, and it is convenient for daily maintenance and scale expansion. In addition, the new pressure balance logic of the present invention can achieve higher-precision pressure control compared to high-pressure back pressure valves and high-pressure mass flow. The present invention uses gas diffusion electrodes to construct a three-phase interface near the catalyst under high-pressure conditions, effectively improves CO2 mass transfer, and greatly increases the current density of the reaction. The present invention can realize electrocatalytic CO2 reduction in the pressure range of 0~5Mpa. High CO2 pressure can effectively increase the solubility of CO2 in the electrolyte, thereby effectively improving mass transfer and promoting the forward reaction. The system of the present invention can perform electrocatalytic CO2 reduction in the form of a continuous flow reaction through the arrangement of a high-pressure CO2 gas cylinder and a high-pressure constant-current pump, thereby quickly taking away the liquid phase products on the catalyst surface, promoting the detachment of the products, and timely replenishing the pure electrolyte, thereby accelerating the reaction from a kinetic point of view.

[0019] Furthermore, the pressure-resistant stainless steel container of the present invention is connected to a gas chromatograph via a pressure reducing valve and to a liquid storage tank via a needle valve. Therefore, continuous testing under different working conditions can be achieved without disassembling the reactor, and gas phase products can be collected and detected in an integrated manner and liquid phase products can be collected, thereby simplifying the operating difficulty and saving the testing time to the greatest extent, and accurately evaluating the electrocatalytic CO2 reduction performance under high-pressure working conditions. In view of the continuous testing requirements of multiple working points, the present invention can avoid the interference of unknown factors such as the disassembly and assembly of the reactor between the tests of different working points in the traditional system, thereby significantly improving the accuracy of the evaluation of the catalytic performance of the catalyst; in view of the multiple testing requirements of a specific working point, the present invention adopts a continuous flow reaction form to ensure that the catalyst interface is always covered by an electrolyte that does not contain products.

[0020] Furthermore, in the present invention, a vacuum pump is connected behind the pressure-resistant stainless steel container. After the test is completed, the pressure-resistant stainless steel container can be evacuated by the vacuum pump to avoid the influence of residual gas on the next test.

[0021] 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 play an insulating role when the cathode and anode are pressurized in the electrochemical workstation.

[0022] Furthermore, the present invention provides filters on the gas passage and the liquid passage respectively, which can ensure the purity of the gas and the electrolyte and avoid the influence of impurities on the reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a schematic diagram of the structure of the system for electrocatalytic reduction of high-pressure CO2 of the present invention.

[0025] Figure 2 It is a schematic diagram of the continuous test results obtained in Example 1 using pure Ag as a catalyst.

[0026] Figure 3 This is a schematic diagram of the continuous test results obtained in Example 2 using pure Ag as a catalyst. DETAILED DESCRIPTION

[0027] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0028] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0029] It should be noted that the terms "include" and "have" 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 clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0030] In addition, it should be noted that the terms "first", "second", etc. of the present invention 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 here can be implemented in an order other than those illustrated or described here. The orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention; in addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements.

[0031] like Figure 1As shown, the system for electrocatalytic reduction of high-pressure CO2 of the present invention comprises: 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 joint joint 7, a second joint joint 9, a third joint joint 11, a fourth joint 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 liquid storage tank 22, a liquid chromatograph 23, a gas chromatograph 25, and a vacuum pump 21. The computer has control software for the electrochemical workstation 8, the liquid chromatograph 23, and the gas chromatograph 25. The upper end of the pressure-resistant stainless steel container 16 is provided with a gas inlet 13, a liquid inlet 14, and a first gas outlet 15, and the lower end is provided with a liquid outlet 18 and a second gas outlet 17. Each operating point corresponds to a liquid storage tank 22.

[0032] 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 joint joint 7, and the outlet of the first joint joint 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 joint joint 12. The outlet of the fourth joint joint 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 joint joint 7, the pressure-resistant electrocatalytic reactor 10, the fourth joint joint 12 and the pressure-resistant stainless steel container 16 are connected in sequence through stainless steel pipes.

[0033] The outlet of the high-pressure constant-current 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 joint 9, and the outlet of the second joint joint 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 joint 11. The outlet of the third joint joint 11 is connected to the liquid inlet 14 at the upper end of the pressure-resistant stainless steel container 16. The high-pressure constant-current pump 4, the second filter 5, the second joint joint 9, the pressure-resistant electrocatalytic reactor 10, the third joint joint 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 through a check valve 6.

[0034] The working electrode electrode clamp of the electrochemical workstation 8 is connected to the stainless steel pipe between the first joint joint 7 and the pressure-resistant electrocatalytic reactor 10 , and the counter electrode electrode clamp is connected to the stainless steel pipe between the third joint joint 11 and the pressure-resistant electrocatalytic reactor 10 .

[0035] 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, and the outlet of the second pressure reducing valve 24 is connected to the gas chromatograph 25. 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. 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 liquid storage tank 22. The liquid in the liquid storage tank 22 is sent to the liquid chromatograph 23 for product detection and analysis.

[0036] The pressure-resistant electrocatalytic reactor 10 includes a cathode plate, a polytetrafluoro gasket, and an anode plate; a cathode is sealed between the cathode plate and the polytetrafluoro gasket, and an anode is installed between the anode plate and the polytetrafluoro gasket; the cathode plate is connected to the working electrode of the 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 is separated from the liquid chamber, and a high-concentration strong alkaline solution can be used as an electrolyte, thereby effectively improving the selectivity of the target product and the overall energy conversion efficiency of the device.

[0037] The cathode inlet of the pressure-resistant electrocatalytic reactor 10 of the present invention 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.

[0038] The electrochemical workstation 8, gas chromatograph 25 and liquid chromatograph 23 are all connected to the computer via data cables. The control software of the electrochemical workstation 8 is Nova 2.1.7, and the control software of the gas chromatograph 25 is OpenLAB ControlPanel.

[0039] The gas chromatograph 25 includes a TCD detector for detecting the concentration of hydrogen in the gas, and two FID detectors for detecting the concentrations of methane, ethylene, and carbon monoxide in the gas. A ten-way valve is provided inside the gas chromatograph 25 to separate different types of products in the gas into corresponding detectors.

[0040] The system of the present invention can be divided into an electrochemical module, a gas flow module, an electrolyte flow module, and a chromatographic sampling module.

[0041] The electrochemical module includes an electrochemical workstation 8, a pressure-resistant electrocatalytic reactor 10, a first joint joint 7, a second joint joint 9, a third joint joint 11, and a fourth joint joint 12. The electrochemical workstation 8 performs a constant potential or constant current application process corresponding to each operating point of the test, applies a corresponding constant potential or constant current between the cathode and anode of the pressure-resistant electrocatalytic reactor 10, and collects data. The first joint joint 7, the second joint joint 9, the third joint joint 11, and the fourth joint joint 12 play an insulating role to ensure that the potential or current is only applied to the pressure-resistant electrocatalytic reactor 10.

[0042] 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 joint 7, a fourth 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 the high-pressure CO2 gas flows out of the first pressure reducing valve 2, it is filtered by the first filter 3 and then enters the cathode of the pressure-resistant electrocatalytic reactor 10 through the first joint 7. The gaseous products produced after the electrocatalytic reduction reaction flow into the pressure-resistant stainless steel container 16 along with the CO2 gas through the fourth joint 12 and the gas inlet 13 of 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, the partial pressure is reduced to normal pressure, and then it is passed into the gas chromatograph 25.

[0043] The electrolyte flow module includes a high-pressure constant current pump 4, a second filter 5, a second joint 9, a third joint 11, a pressure-resistant stainless steel container 16, a first needle valve 19, and a liquid storage tank 22. During the test, the electrolyte flows through the second filter 5 after being pressurized by the high-pressure constant current pump 4, and enters the anode of the pressure-resistant electrocatalytic reactor 10 through the second joint 9 after filtration. The liquid phase product generated by the reaction flows through the third joint 11 with the electrolyte and enters the pressure-resistant stainless steel container 16, enters the liquid storage tank 22 after passing through the first needle valve 19, and then is sent to the liquid chromatography 23 for product detection and analysis. Specifically, during the test, the high-pressure constant current pump 4 sequentially performs the reaction flow control process and the flushing flow control process. During the process of applying potential or current to the above-mentioned electrochemical workstation 8, it is set to the reaction flow control process, and the first needle valve 19 is closed at the same time; after the flushing flow control process of the high-pressure constant current pump 4 is completed, the first needle valve 19 is opened, and the electrolyte in the pressure-resistant stainless steel container 16 is collected in the liquid storage tank 22.

[0044] The chromatographic sampling module mainly includes a gas chromatograph 25. The gas chromatograph 25 is divided into a chromatographic injection stage and a chromatographic analysis stage during the operation of a single set of chromatographic tests, wherein the chromatographic analysis stage includes product analysis and tail gas purging. The operation time of the chromatographic test module must match the time of the electrochemical module. Specifically, after the potential or current application stage of the electrochemical workstation 8 and the high-voltage constant current pump 4 are in the reaction flow control stage, the gas chromatograph 25 is operated to the chromatographic injection stage, and at the same time, it is ensured that the sum of the time of the potential or current application stage and the waiting stage of the electrochemical workstation 8 is equal to the sum of the time of the chromatographic injection stage and the chromatographic analysis stage of the gas chromatograph 25. The time of the chromatographic injection stage is very short, and the injection can be completed in about tens of seconds, and then the chromatographic analysis stage is executed; the time corresponding to the chromatographic analysis stage corresponding to the first operating point is the flow flushing time of the high-voltage constant current pump corresponding to the first operating point and the flow control time of the high-voltage constant current pump corresponding to the second operating point, and so on.

[0045] In a specific embodiment of the present invention, the control software of the electrochemical module is Nova 2.1.7, and the software programming module is used to set the constant potential or constant current time t1 of the electrochemical workstation 8 and collect relevant electrochemical signals.

[0046] In the gas flow module of the present invention, the partial pressure of the first pressure reducing valve 2 is adjusted to meet the pressure required by the test operating point.

[0047] In a specific embodiment of the present invention, the reaction flow q1 and the flushing flow q2 are controlled by adjusting the flow of the high-pressure constant flow pump 4, wherein the time corresponding to the reaction flow q1 is t2, and the time corresponding to the flushing flow is t3.

[0048] In a specific embodiment of the present invention, the control software of the chromatographic sampling module is OpenLAB Control Panel, which is used to control the gas chromatograph to continuously perform chromatographic sampling and chromatographic analysis in sequence under different test conditions. The time corresponding to the single group of chromatographic test operation process is t4. During the continuous test process, the chromatographic sampling module is provided with control program modules consistent with the number of test condition points. The control program modules correspond to the condition points one by one, and each control program module controls the single group of chromatographic test operation process of the corresponding condition point.

[0049] The above system of the present invention can continuously and quantitatively analyze the gas phase product components under different test conditions. During the test process of each working point, the high-voltage constant current pump operates in the reaction flow control stage and the flushing flow control stage in sequence, and the gas chromatograph operates in the chromatographic injection stage and the chromatographic analysis stage in sequence. The electrochemical workstation constant potential or constant current application stage is carried out synchronously with the high-voltage constant current pump reaction flow control stage; the chromatographic injection stage starts after the electrochemical workstation constant potential or constant current application stage ends.

[0050] The present invention provides a testing method for continuous flow electrocatalytic reduction of high pressure CO2, based on the system, comprising the following steps: Step 1: After the system of the present invention is assembled, all valves are closed. Open the valve of the high-pressure CO2 cylinder 1, and after ensuring that the total pressure indication of the first pressure reducing valve 2 is stable, adjust the partial pressure indication of the first pressure reducing valve 2 to the pressure P1 required at the test operating point. After the total pressure indication of the second pressure reducing valve 24 is the same as the partial pressure indication of the first pressure reducing valve 2, adjust the partial pressure indication of the second pressure reducing valve 24 to normal pressure, and record its pressure as P0.

[0051] Step 2: Turn on the high-pressure constant-current pump 4 and set its flow rate to 8 mL / min. After running for 3 minutes, open the first needle valve 19 to discharge all the electrolyte in the pressure-resistant stainless steel container 16, and close the first needle valve 19. The purpose of this step is to detect whether the pipeline is unobstructed and avoid leakage, and at the same time fill the pipeline with electrolyte.

[0052] Step 3: Set the same number of control program modules as the test operating points in the control software Nova 2.1.7 of the electrochemical module and the control software OpenLAB Control Panel of the chromatographic sampling module to control the running process of a single group of chromatographic tests at the corresponding operating points.

[0053] Step 4: Perform the test of the first operating point. The electrochemical workstation 8 runs to the constant potential or constant current application stage, and the high-voltage constant current pump 4 runs to the reaction flow q1 control stage, and pumps fresh electrolyte into the pressure-resistant electrocatalytic reactor 10. After the operation time t1 is completed, the electrochemical workstation 8 adjusts the flow of the high-voltage constant current pump 4 to the flushing flow q2, flushes the residual liquid products in the pressure-resistant electrocatalytic reactor 10 and the connecting pipeline into the pressure-resistant stainless steel container 16, and runs the gas chromatograph 25 to the chromatographic injection stage. After the injection is completed, perform chromatographic analysis. After the flushing is completed, close the valve of the high-pressure CO2 gas cylinder 1, open the first needle valve 19, collect all the electrolyte in the pressure-resistant stainless steel container 16 into the liquid storage tank 22, and complete the test of the first operating point.

[0054] Step 5: After the first operating point test is completed, the second needle valve 20 is opened and the vacuum pump 21 is operated for a running time of m. The selection criterion of m is that all the gas in the pressure-resistant stainless steel container 16 is completely extracted to avoid affecting the detection of the gas phase product at the next operating point.

[0055] Step 6: Turn off the vacuum pump 21, close the first needle valve 19 and the second needle valve 20, repeat step 1, and perform the test of the second operating point, and so on, to complete the test of all operating points.

[0056] 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.

[0057] Example 1 The carbon paper was cut into a circle with a diameter of 15 cm, and then a pure Ag catalyst with a thickness of 500 nm was sputtered on its surface by an electron beam evaporation coating apparatus to obtain a gas diffusion electrode loaded with pure Ag. The gas diffusion electrode loaded with pure Ag was used as the cathode, and a nickel mesh with a thickness of 80 μm was selected as the anode. The prepared cathode and anode were assembled in a pressure-resistant electrocatalytic reactor 10, and the electrolyte was a 1.5 M KOH solution. 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 were as follows. Figure 2 It can be seen that the system of the present invention can obtain good CO2 reduction performance in a wide current density range at a pressure of 1 MPa.

[0058] Example 2 The carbon paper was cut into a circle with a diameter of 15 cm, and then a pure Ag catalyst with a thickness of 500 nm was sputtered on its surface by an electron beam evaporation coating apparatus to obtain a gas diffusion electrode loaded with pure Ag. The gas diffusion electrode loaded with pure Ag was used as the cathode, and a nickel mesh with a thickness of 80 μm was selected as the anode. The prepared cathode and anode were assembled in a pressure-resistant electrocatalytic reactor 10, and the electrolyte was a 1.5M KOH solution. 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. The test results are as follows: Figure 3 It can be seen that the system of the present invention can obtain good CO2 reduction performance in a wide current density range at a pressure of 3 MPa.

Claims

1. A system for electrocatalytic reduction of high pressure CO2, characterized in that: include: A high-pressure CO2 gas cylinder (1), a first pressure reducing valve (2), a check valve (6), a high-pressure constant-flow pump (4), an electrochemical workstation (8), a pressure-resistant electrocatalytic reactor (10), and a pressure-resistant stainless steel container (16); The high-pressure CO2 gas 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 upper end of the pressure-resistant stainless steel container (16); The outlet of the high-pressure constant-current 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 liquid inlet (14) at the upper end 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 the counter electrode of the electrochemical workstation (8) are respectively connected to the cathode and the 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); and 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 liquid 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 liquid 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-current 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 (10) is connected to the cathode inlet of the pressure-resistant electrocatalytic reactor (10) via the fourth joint connector (12); 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 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 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-current pump (4) and the second joint connector (9).

7. A method for electrocatalytic reduction of high-pressure CO2, characterized in that: The system according to any one of claims 1 to 6, comprising: S1, open the valve of the high-pressure CO2 gas cylinder (1), the high-pressure CO2 gas in the high-pressure CO2 gas cylinder (1) passes through the first pressure reducing valve (2) and enters the pressure-resistant electrocatalytic reactor (10) and the pressure-resistant stainless steel container (16) in sequence, adjust the partial pressure indication of the first pressure reducing valve (2) to the pressure required by the operating point, and after the pressure in the pressure-resistant stainless steel container (16) is equal to the partial 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, turning on the electrochemical workstation (8), operating the electrochemical workstation (8) to the constant potential or constant current application stage, and operating the high-voltage constant current pump (4) to the reaction flow control stage to perform electrocatalytic reduction of high-pressure CO2.

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

9. The test method for electrocatalytic reduction of high pressure CO2 according to claim 8, characterized in that: The system for electrocatalytic reduction of high-pressure CO2 also includes a first needle valve (19), a liquid 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 liquid 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 liquid storage tank (22), and liquid chromatography is used to perform liquid phase testing.

10. The test method for electrocatalytic reduction of high pressure CO2 according to claim 9, characterized in that: The system for electrocatalytic reduction of high-pressure CO2 also includes a second needle valve (20) and a vacuum pump (21); a 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 in the liquid storage tank (22), the second needle valve (20) is opened, and the vacuum pump (21) is operated to evacuate the pressure-resistant stainless steel container (16); after the pressure-resistant stainless steel container (16) reaches a preset vacuum degree, the vacuum pump (21) is turned off, the first needle valve (19) and the second needle valve (20) are closed, and S3 is executed.

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