Solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system and method

Abstract

The invention provides a solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system and method. Solar energy is converted into electric energy through the photovoltaic panel to provide electric energy for electrocatalytic carbon dioxide reduction reaction, the solar radiation intensity and the working temperature of the surface of the photovoltaic panel are collected through the solar radiation sensor and the temperature sensor respectively, and the coupling controller is used for controlling connection and disconnection of the flowing electrolytic tank according to the solar radiation intensity and the working temperature. And the flowing electrolytic tank is subjected to electrochemical carbon dioxide reduction reaction in a preset current density range, so that the electrode drowning phenomenon is avoided, and stable synthesis of ethylene under variable environment working conditions is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar energy utilization, and relates to a system and method for dynamically coupling solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction, which can realize stable synthesis of specific hydrocarbon products under variable operating conditions. Background Art

[0002] With the continuous development of human civilization, human demand for energy is getting higher and higher. The storage and utilization of renewable energy has become a widely concerned issue in society. Among the known renewable energy sources, solar energy is the most widely distributed and abundant renewable energy. The solar energy supplied to the earth's surface is 9,600 times the current global energy consumption. About 10% of the solar energy received by 0.3% of the earth's surface is enough to meet the expected energy demand in 2050. Therefore, efficiently converting solar energy into fuel is currently a way to solve this problem, and it is also one of the hot topics studied in the energy industry for a long time. The technology that combines solar photovoltaic power generation with electrocatalytic carbon dioxide reduction has good development prospects. Electrocatalytic carbon dioxide reduction technology can realize the conversion of electrical energy and carbon dioxide into easily stored hydrocarbons, while reducing carbon dioxide emissions, it also provides raw materials for the chemical industry and fuel for the energy industry. Solar-driven electrocatalytic carbon dioxide reduction provides a solution to improving the greenhouse effect and solar energy storage and utilization.

[0003] In the past few decades, the research on solar-driven electrocatalytic carbon dioxide reduction has developed rapidly, and many solar-driven carbon dioxide reduction systems have been established. Commonly used systems include photocatalytic (PC) systems, photovoltaic-electrochemical (PV-EC) systems, and photoelectrochemical (PEC) systems. Among these production systems, photovoltaic-coupled electrochemical systems and photoelectrochemical systems show higher solar-to-fuel conversion efficiency (STF). From the perspective of a single indicator of energy conversion efficiency, photovoltaic-coupled electrochemistry is the most efficient of all technical routes.

[0004] At present, the research on electrochemical carbon dioxide reduction is mostly focused on catalytic materials, and the research on coupling and matching with photovoltaics is still insufficient. At present, photovoltaic and electrochemical systems mostly use indirect coupling of converter elements. Although the high energy conversion efficiency of photovoltaics is guaranteed, there is coupling energy loss. The carbon dioxide reduction reaction path is complex and the products are diverse. It is mainly affected by parameters such as current density and voltage during the reaction process. When the environmental parameters such as irradiation intensity and operating temperature of photovoltaic cells change, their current and voltage outputs will fluctuate, which will directly affect the current and voltage of the carbon dioxide reduction reaction system, and ultimately affect the selectivity of the product. In particular, at a current of more than 260mA·cm -2 Electrode flooding is prone to occur under current density. Electrode flooding is a commonly used term in the field of electrochemistry. It refers to the excessive penetration of electrolyte into or even filling the pores of the electrode, preventing the gas from reaching the catalytic active sites of the electrode. When flooding does not occur, the hydrophobic gas diffusion layer (GDL) is used to limit the invasion of electrolyte into the gas side to ensure CO2 flux. However, once the electrolyte infiltrates the GDL pores, the liquid diffusion length will increase to the extent that the CO2 flux cannot meet the current CO2 reduction requirements, hindering the reaction. And the wetted portion of the entire electrode will be conducive to HER, promoting the generation of H2, resulting in reduced selectivity for ethylene.

[0005] Therefore, it is necessary to explore new control strategies for direct coupling of photovoltaic and electrochemical systems to reduce coupling losses and avoid the problem of electrode drowning, so as to ensure the stable synthesis of specific hydrocarbon products under variable environmental conditions. Summary of the invention

[0006] In order to solve the current problems of high energy loss in photovoltaic-electrochemical coupling, drowning of high current density electrodes and inability to stably synthesize specific products, the present invention provides a system and method for dynamically coupling solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction.

[0007] The present invention is achieved through the following technical solutions:

[0008] The present invention provides a solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system, including a photovoltaic panel, a coupling controller, an electrocatalytic reactor, a solar radiation sensor and a temperature sensor;

[0009] The solar radiation sensor is used to collect the solar radiation intensity irradiated on the surface of the photovoltaic panel and transmit it to the coupling controller, and the temperature sensor is used to collect the working temperature of the surface of the photovoltaic panel and transmit it to the coupling controller;

[0010] An electrolytic cell group electrically connected to the photovoltaic panel is arranged in the electrocatalytic reactor, and the electrolytic cell group is composed of a number of identical flow electrolytic cells connected in parallel, and the flow electrolytic cells are used for electrocatalytic reduction of carbon dioxide to produce ethylene; the coupling controller calculates the number of flow electrolytic cells that need to be connected to the electrolytic cell group when the current density of the flow electrolytic cells is maintained within a preset current density range based on the received solar radiation intensity and the operating temperature, and controls the number of flow electrolytic cells connected to the electrolytic cell group based on the number of flow electrolytic cells that need to be connected.

[0011] Preferably, the flow electrolytic cell comprises, from one side to the other, an anode plate, an anode, a sealing gasket, an intermediate chamber, an ion exchange membrane, a sealing gasket, a cathode and a cathode plate; the positive pole of the photovoltaic panel is connected to the anode of the flow electrolytic cell through an electromagnetic relay, and the negative pole of the photovoltaic panel is connected to the cathode of the flow electrolytic cell through an electromagnetic relay; the coupling controller controls the electrical connection between the photovoltaic panel and the flow electrolytic cell through the electromagnetic relay.

[0012] Furthermore, the cathode is obtained by using Y30T carbon paper loaded with an electrocatalyst after hydrophobic pretreatment.

[0013] Furthermore, a first electrolyte solution inlet and a first drain port are provided on the anode plate, a second electrolyte solution inlet and a second drain port are provided on the middle chamber, and a carbon dioxide gas inlet and a mixed gas outlet are provided on the cathode plate; the flow electrolytic cells are arranged in sequence from front to back, the mixed gas outlet of the previous flow electrolytic cell is connected to the carbon dioxide gas inlet of the next flow electrolytic cell, the first drain port of the previous flow electrolytic cell is connected to the first electrolyte solution inlet of the next flow electrolytic cell, and the second drain port of the previous flow electrolytic cell is connected to the second electrolyte solution inlet of the next flow electrolytic cell.

[0014] Furthermore, the portion of the cathode plate opposite to the cathode is configured as a cavity structure, and the carbon dioxide gas inlet and the mixed gas outlet are both connected to the cavity structure.

[0015] Furthermore, the portion of the anode plate opposite to the anode is a flow channel, one end of the flow channel is connected to the first electrolyte solution inlet, and the other end of the flow channel is connected to the first drain port.

[0016] Furthermore, the carbon dioxide gas inlet of the first flow electrolytic cell is connected to the carbon dioxide gas tank through a hose and a carbon dioxide gas valve; the first electrolyte solution inlet and the second electrolyte solution inlet of the first flow electrolytic cell are both connected to the electrolyte solution pool through a peristaltic pump; the mixed gas outlet of the last flow electrolytic cell is connected to the gas chromatograph; the first drain port and the second drain port of the last flow electrolytic cell are both provided with drain valves.

[0017] Preferably, the solar radiation sensor is a photoelectric solar radiation sensor, and the temperature sensor is a Pt100 adhesive temperature sensor.

[0018] The present invention also provides a method for dynamically coupling solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction, based on the dynamically coupling system of solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction, comprising:

[0019] The solar radiation sensor collects the solar radiation intensity irradiated on the photovoltaic panel and transmits it to the coupling controller, and the temperature sensor collects the working temperature of the photovoltaic panel and transmits it to the coupling controller; the flow electrolysis cell electrocatalyzes the reduction of carbon dioxide to produce ethylene;

[0020] The coupling controller calculates the number of flowing electrolytic cells that need to be connected to the electrolytic cell group so that the current density of the flowing electrolytic cells is maintained within a preset current density range based on the received solar radiation intensity and the operating temperature, and controls the number of flowing electrolytic cells connected to the electrolytic cell group based on the number of flowing electrolytic cells that need to be connected.

[0021] Preferably, the coupling controller calculates the number of flowing electrolytic cells that need to be connected to the electrolytic cell group when the current density of the flowing electrolytic cells is maintained within a preset current density range according to the received solar radiation intensity and the operating temperature, specifically:

[0022] The photovoltaic model formula is as follows:

[0023]

[0024] Where: q is the electron charge number, C; k is the Boltzmann constant, m 2 kg s -2 ·K -1 ; N s is the number of electrolytic cell groups connected in series with the photovoltaic panel; A is the ideal factor of the semiconductor in the photovoltaic panel; I s is the reverse saturation current value; V OC,STC is the open circuit voltage under STC, V; K V is the voltage temperature coefficient, %·K -1 ;I SC,STC is the short-circuit current under STC, A; K I is the photocurrent temperature coefficient, %·K -1 ; V mp,STC is the maximum power point voltage under STC; I mp,STC is the maximum power point current under STC; V t is the thermal voltage of the PV module, V, which is defined as:

[0025] The battery stack model formula is as follows:

[0026]

[0027] Where Ns is the number of electrolytic cell groups connected in series with photovoltaic panels; N p is the number of flow electrolytic cells connected in parallel in the electrolytic cell group; e rev Reversible Potential, V, represents the minimum voltage required for electrochemical reaction to occur; R i is the heat loss resistance (Resistive Heat Loss), Ω, which represents the resistance heat loss term represented by the slope of the IV curve of the flow electrolytic cell; j is the current density, mA cm -2 ; S is the cathode reaction area of ​​the flow electrolytic cell participating in the reaction, cm 2 ;

[0028] Under the constraint of satisfying the preset current density range, equations (1) to (10) are solved together to obtain the number of flow electrolytic cells that need to be connected in parallel in the electrolytic cell group.

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

[0030] The present invention discloses a solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system. The solar energy is converted into electric energy through the photovoltaic panel to provide electric energy for the electrocatalytic carbon dioxide reduction reaction. The solar radiation intensity and the working temperature on the surface of the photovoltaic panel are respectively collected through the solar radiation sensor and the temperature sensor. The connection and disconnection of the flow electrolytic cell are controlled by the coupling controller according to the solar radiation intensity and the working temperature, so that the flow electrolytic cell performs the electrochemical carbon dioxide reduction reaction within the preset current density range, thereby avoiding the occurrence of the electrode drowning phenomenon and realizing the stable synthesis of ethylene under variable environmental conditions. The present invention realizes 35-40% ethylene (C2H2) selectivity stably under outdoor variable working conditions through the coupling of photovoltaic power generation and electrocatalysis. The main advantage of the present invention is that the efficient utilization of light energy is achieved through load regulation, thereby achieving high selectivity and obtaining high energy conversion efficiency. The solar energy is directly coupled with the electrocatalysis and introduced into the carbon dioxide reduction at the same time, so as to realize the purpose of stable synthesis of specific hydrocarbon products under variable working conditions. Therefore, the present invention solves the problem that single solar energy cannot stably synthesize ethylene under variable environmental conditions and the coupling energy loss is high, and provides a solution for the industrial application of photovoltaic direct coupling electrochemical carbon dioxide reduction technology.

[0031] Furthermore, the flow electrolytic cell of the present invention uses a cavity on the cathode plate side for gas-side mass transfer. Compared with the traditional flow channel structure, the cavity structure design can better avoid the phenomenon of electrode drowning. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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.

[0033] Figure 1 It is a schematic diagram of the dynamic coupling system of solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction involved in the present invention.

[0034] Figure 2 The diagram is a schematic diagram of the circuit and mass transfer route of the electrocatalytic reactor involved in the present invention.

[0035] Figure 3 The figure is a structural diagram of a single flow electrolytic cell in the electrocatalytic reactor of the present invention; (a) front view; (b) left view; (c) top view; (d) cross-sectional view of the anode and anode conductive sheet; (e) cross-sectional view of the cathode and cathode conductive sheet.

[0036] Figure 4 It is an operational logic diagram of a coupling controller involved in the structural diagram of a single flow electrolytic cell in the electrocatalytic reactor of the present invention.

[0037] Figure 5 It is a functional schematic diagram of the coupling control model involved in the present invention.

[0038] Serial numbers in the above figure: photovoltaic panel 1, solar radiation sensor 2, coupling controller 3, electrocatalytic reactor 4, negative electrode 5, positive electrode 6, carbon dioxide gas valve 7, carbon dioxide gas tank 8, peristaltic pump 9, electrolyte solution pool 10, gas chromatograph 11, drain valve 12, anode plate 13, anode 14-1, anode conductive sheet 14-2, sealing gasket 15, intermediate chamber 16, ion exchange membrane 17, cathode 18-1, cathode conductive sheet 18-2, cathode plate 19, carbon dioxide gas inlet 20, mixed gas outlet 21, second electrolyte solution inlet 22, second drain port 23, first electrolyte solution inlet 24, first drain port 25. DETAILED DESCRIPTION

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] See also Figure 1 The solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system of the present invention comprises a photovoltaic panel 1, a coupling controller 3, an electrocatalytic reactor 4, a solar radiation sensor 2 and a temperature sensor;

[0044] The solar radiation sensor 2 is used to collect the solar radiation intensity irradiated on the photovoltaic panel 1 and transmit it to the coupling controller 3, and the temperature sensor is used to collect the working temperature of the photovoltaic panel 1 and transmit it to the coupling controller 3;

[0045] A plurality of identical flow electrolytic cells (GDE) are arranged in the electrocatalytic reactor 4, and the flow electrolytic cells are used for electrocatalytic reduction of carbon dioxide to produce ethylene; the coupling controller 3 calculates the number of flow electrolytic cells required for the flow electrolytic cells to maintain a preset current density according to the received solar radiation intensity and the operating temperature, and controls the number of flow electrolytic cells connected to the photovoltaic panel 1 according to the required number of flow electrolytic cells, and the electrical connection between the flow electrolytic cells connected to the photovoltaic panel 1 is in parallel.

[0046] In some specific embodiments, the solar radiation sensor 2 is a photoelectric solar radiation sensor, and is disposed on the front side of the photovoltaic panel 1. The temperature sensor is preferably a Pt100 adhesive temperature sensor, and is disposed on the back side of the photovoltaic panel 1.

[0047] See also Figure 2 A plurality of flow electrolytic cells arranged inside the electrocatalytic reactor 4 are connected in parallel to form an electrolytic cell group. The circuits of the flow electrolytic cells are connected in parallel, and the gas-liquid transmission is connected in series by a hose.

[0048] See also Figure 3 , is a schematic diagram of the assembly structure of the flow electrolytic cell, which includes, from one side to the other side, an anode plate 13, an anode 14-1, a sealing gasket 15, an intermediate chamber 16, an ion exchange membrane 17, a sealing gasket 15, a cathode 18-1 and a cathode plate 19. One end of the anode 14-1 is connected to an anode conductive sheet 14-2, and one end of the cathode 18-1 is connected to a cathode conductive sheet 18-2.

[0049] The photovoltaic panel 1 is regarded as a power source, providing the electric energy required for the electrocatalytic reaction to the electrocatalytic reactor 4. Specifically, the positive pole 6 of the photovoltaic panel 1 is connected to the anode conductive sheet 14-2 on the upper part of the electrocatalytic reactor 4 through a wire, and the negative pole 5 of the photovoltaic panel 1 is connected to the cathode conductive sheet 18-2 on the upper part of the electrocatalytic reactor 4 through a wire.

[0050] The anode plate 13 is provided with a first electrolyte solution inlet 24 and a first drain port 25, the middle chamber 16 is provided with a second electrolyte solution inlet 22 and a second drain port 23, the cathode plate 19 is provided with a carbon dioxide gas inlet 20 and a mixed gas outlet 21, and the flow electrolytic cells are arranged in a front-to-back order, the mixed gas outlet 21 of the previous flow electrolytic cell is connected to the carbon dioxide gas inlet 20 of the next flow electrolytic cell, the first drain port 25 of the previous flow electrolytic cell is connected to the first electrolyte solution inlet 24 of the next flow electrolytic cell, and the second drain port 23 of the previous flow electrolytic cell is connected to the second electrolyte solution inlet 22 of the next flow electrolytic cell. The carbon dioxide gas inlet 20 of the first flow electrolytic cell is connected to the carbon dioxide gas tank 8 through a hose and a carbon dioxide gas valve 7; the first electrolyte solution inlet 24 and the second electrolyte solution inlet 22 of the first flow electrolytic cell are connected to the electrolyte solution cell 10 through a peristaltic pump 9; the mixed gas outlet 21 of the last flow electrolytic cell is connected to a gas chromatograph 11 to detect gas products; the first drain port 25 and the second drain port 23 of the last flow electrolytic cell are both provided with drain valves 12.

[0051] The portion of the cathode plate 19 opposite to the cathode 18 - 1 is set as a cavity structure, and the carbon dioxide gas inlet 20 and the mixed gas outlet 21 are both connected to the cavity structure, so as to avoid the phenomenon of electrode drowning.

[0052] The portion of the anode plate 13 facing the anode 14 - 1 is a flow channel, one end of the flow channel is connected to the first electrolyte solution inlet 24 , and the other end of the flow channel is connected to the first drain port 25 .

[0053] The working principle of the present invention is described in detail as follows:

[0054] The principle of photovoltaics is the photovoltaic effect of semiconductor materials. The structure of a photovoltaic cell is a semiconductor diode. When sunlight shines on the pn junction of a semiconductor diode, new hole-electron pairs are formed. Under the action of the electric field, holes flow from the n-type region to the p-type region, and electrons move in the opposite direction, thereby generating voltage. If an external circuit (such as a wire or a load) is connected to both ends of a photovoltaic cell, current will be generated.

[0055] In terms of electrocatalysis, solar energy is converted into electrical energy through the photovoltaic panel 1 containing photovoltaic cells, and the electrochemical reaction in the flow electrolysis cell is driven. The carbon dioxide in the flow electrolysis cell is reduced at the cathode 18-1 to generate carbon-containing products. The ion exchange membrane 17 limits the passage of specific charged ions to ensure the normal movement of charges in the electrolyte and prevent the cathode and anode products from diffusing to the counter electrode to cause reverse reaction.

[0056] See also Figure 4, the control signal of the coupling controller 3 is connected to the electromagnetic relay, and the electromagnetic relay is used to control the opening and closing of the electrical connection between the flow electrolytic cell and the photovoltaic panel 1, that is, the flow electrolytic cell and the photovoltaic panel 1 are electrically connected or disconnected. The coupling controller 3 selects the current density of the flow electrolytic cell as the control parameter, and within the preset current density range, by inputting the solar radiation intensity G and the operating temperature T into the single-chip microcomputer for iterative calculation, the number of flow electrolytic cells that make the current density of the flow electrolytic cell within the preset current density range is obtained, and the result is output to control the number of flow electrolytic cells connected to the photovoltaic panel 1 in the electrocatalytic reactor.

[0057] From an electrical point of view, changing the number of electrolytic cells in series or parallel in the electrolytic cell group can change the impedance of the electrolytic cell group as a whole, that is, change the volt-ampere characteristic curve of the electrolytic cell group. Thus, the corresponding electrolytic cell IV working characteristic curve moves along the voltage axis or current axis, changes the position of the working point, and realizes the change of the system current and voltage. The circuit design of the electrolytic cell group is set to be connected in parallel, and the working point can be kept stable within a certain range as the external conditions change.

[0058] See also Figure 5 By constructing a photovoltaic model and a battery stack model, equations (1) to (10) are solved jointly within the set control boundary, and the number of flow electrolytic cells is obtained through iterative calculation.

[0059] The formula for building a photovoltaic model is as follows:

[0060]

[0061] Photovoltaic panels can operate under normal atmospheric conditions, but the electrical parameters listed in the performance parameter table are obtained under standard test conditions (STC). The temperature T of STC STC At 25°C, the irradiation intensity is G STC 1000W·m -2 In formula (3), V OC ,I SC 、V mp and I mp The four parameters are mainly based on the solar radiation intensity G (unit / W·m -2 ) and the change in operating temperature T (unit / K) can be calculated by equations (4), (5), (6) and (7) respectively:

[0062]

[0063] Where: q is the electronic charge / C, which is 1.602×10 -19C; k is the Boltzmann constant, m 2 kg s -2 ·K -1 ; N s is the number of electrolytic cell groups connected in series with photovoltaic panels. In the embodiment of the present invention, N s Take 1; A is the ideality factor of the semiconductor in the photovoltaic panel; I s is the reverse saturation current value; V OC,STC is the open circuit voltage under STC, V; K V is the voltage temperature coefficient (Temperature Coefficient of Voltage), %·K -1 ;I SC,STC is the short-circuit current under STC, A; K I Temperature Coefficient of Photocurrent, %·K -1 ; V mp,STC is the maximum power point voltage under STC; I mp,STC is the maximum power point current under STC; V t is the thermal voltage of the photovoltaic module, V, which is defined as:

[0064]

[0065] V OC ,I SC 、V mp and I mp Substitute into formula (3) to calculate A, and substitute A into formula (2) to calculate the reverse saturation current value I s , then I s Substitute into equation (1) to obtain the output current I under different voltages.

[0066] The battery stack model is as follows:

[0067]

[0068] Where Ns is the number of electrolytic cell groups connected in series with photovoltaic panels; N p is the number of flow electrolytic cells connected in parallel in the electrolytic cell group, e rev R is the reversible potential, V, which represents the minimum voltage required for an electrochemical reaction to occur. i is the heat loss resistance (Resistive Heat Loss), Ω, which represents the resistance heat loss term represented by the slope of the IV curve of the flow electrolytic cell; j is the current density, mA cm-2 , S is the cathode reaction area of ​​the electrolytic cell group participating in the reaction, cm 2 .

[0069] In order to obtain R i and e rev The present invention uses cyclic voltammetry to test a single flow electrolytic cell and a group of electrolytic cells with different numbers of flow electrolytic cells connected and collects relevant data. The IV curve of the electrolytic cell group is fitted by fitting a polynomial curve using the least squares method, thereby obtaining the R under the electrocatalytic reaction system of the present invention. i and e rev . Thus, the final battery stack model is obtained.

[0070] The IV curve fitting formula of the electrolytic cell group of the reaction system in the embodiment of the present invention is specifically:

[0071]

[0072] In the preset current density range, by solving equations (1) to (10) simultaneously, the number of flow electrolytic cells that need to be connected in parallel in the electrolytic cell group can be obtained.

[0073] Under the constraint of satisfying the preset current density range, the iterative solution method is used to solve the simultaneous equations of equations (1) to (10). The solar radiation intensity G and the operating temperature T are obtained by the solar radiation sensor and the temperature sensor respectively. Given an initial voltage V, the current can be calculated according to the photovoltaic model. The initial voltage V and the current are substituted into the battery stack model to calculate the number of flowing electrolytic cells, and then the current density of the electrolytic cell group can be obtained. It is judged whether the current density meets the preset current density range. If it does, the result is output. If it does not, the voltage V is updated and recalculated until the current density obtained meets the preset current density range. The number of iterations will affect the sensitivity of the control system and the complexity of the algorithm. Therefore, in order to increase the iteration speed, the Newton method is used. The expression of this method is as follows:

[0074]

[0075] Where: x n is the value of the nth iteration; f(x n ) is the iterative calculation formula; f′(x n ) is f(x n ) is the derivative of .

[0076] The working process of the present invention is described as follows:

[0077] After the system is installed, the photovoltaic panel 1 fully absorbs sunlight to generate current. The positive electrode 6 and the negative electrode 5 of the photovoltaic panel 1 are respectively connected to the anode 14-1 and the cathode 18-1 of the flow electrolytic cell. The carbon dioxide gas valve 7 is opened to introduce carbon dioxide into the electrocatalytic reactor 4. At the same time, the peristaltic pump 9 and the drain valve 12 are opened to introduce the electrolyte solution into the electrocatalytic reactor 4. After fully contacting the catalyst on the surface of the cathode 18-1, the photovoltaic panel 1 transmits electrons to the cathode 18-1 in the flow electrolytic cell through the negative electrode 5, and a reduction reaction occurs with carbon dioxide on the catalyst surface to generate ethylene. At the same time, the coupling controller 3 determines and controls the number of flow electrolytic cells that should be connected to the system through the solar radiation intensity and the operating temperature on the surface of the photovoltaic panel 1, so that the current density of the flow electrolytic cell is maintained within the preset current density range. The mixed gas outlet 21 of the electrocatalytic reactor 4 is connected to the gas chromatograph 11 for analyzing and collecting products. Real-time monitoring data is realized through single-chip microcomputer programming, and remote real-time monitoring can be realized in combination with remote control software.

[0078] The electrolyte solution used in the embodiment of the present invention is a 1 mol / L potassium hydroxide solution, the anode is a Pt electrode, the anode material on the anode surface is nickel iron hydroxide synthesized by electrodeposition, and the cathode is a 1 mg·cm -2 The electrocatalyst loading is sprayed onto the Y30T carbon paper after hydrophobic pretreatment, and the electrocatalyst is potassium hydroxide mixed with 40 nanometer copper nanoparticles. In the embodiment of the present invention, the flow electrolytic cell adopts organic glass material, and the sealing gasket 15 adopts polytetrafluoro gasket. The photovoltaic panel 1 adopts a single crystal silicon solar panel with a maximum output power of 5W. The control element in the coupling controller 3 adopts an STM32F407 model single chip microcomputer, and the software used by the coupling controller 3 is Keil uVision5 produced by Keil Software of the United States.

[0079] Single flow electrolysis cell at 250-260 mA cm -2 The highest ethylene selectivity of about 41% can be obtained at a current density of 1.5 V or a voltage range of 3.5-3.6 V.

[0080] In the embodiment of the present invention, the number of connected flow electrolytic cells is controlled by the method of the present invention according to the two parameters of irradiation intensity and operating temperature, so as to control the current density of the entire electrocatalytic reactor 4. When the current density is set to 180-250 mA cm -2 In outdoor tests, the current density is always controlled at 200-260 mA cm -2 The outdoor radiation intensity during the test is 160-900W·m -2The photovoltaic operating temperature is 30-58℃. Through analysis, it is found that the selectivity of gas phase product ethylene is basically maintained at 35%-40%. The experimental results show that with the support of the control system, by continuously adjusting the number of connected flow electrolysis cells, the entire system finally achieved 200-260mA·cm in outdoor tests. -2 At a current density of 3.3-3.6 V, an ethylene selectivity of about 40% was achieved. Compared with the system without a control system, the ethylene selectivity in the reaction system with a control system was relatively high, and the electrode drowning phenomenon was also suppressed.

[0081] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system, characterized in that: It comprises a photovoltaic panel (1), a coupling controller (3), an electrocatalytic reactor (4), a solar radiation sensor (2) and a temperature sensor; The solar radiation sensor (2) is used to collect the solar radiation intensity irradiated on the surface of the photovoltaic panel (1) and transmit it to the coupling controller (3); the temperature sensor is used to collect the working temperature of the surface of the photovoltaic panel (1) and transmit it to the coupling controller (3); The electrocatalytic reactor (4) is provided with an electrolytic cell group electrically connected to the photovoltaic panel (1), wherein the electrolytic cell group is composed of a plurality of identical flow electrolytic cells connected in parallel, and the flow electrolytic cells are used for electrocatalytic reduction of carbon dioxide to produce ethylene; the coupling controller (3) calculates the number of flow electrolytic cells that need to be connected to the electrolytic cell group when the current density of the flow electrolytic cells is maintained within a preset current density range based on the received solar radiation intensity and the operating temperature, and controls the number of flow electrolytic cells connected to the electrolytic cell group based on the number of flow electrolytic cells that need to be connected.

2. The solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system according to claim 1 is characterized in that: The flowing electrolytic cell comprises, from one side to the other, an anode plate (13), an anode (14-1), a sealing gasket (15), an intermediate chamber (16), an ion exchange membrane (17), a sealing gasket (15), a cathode (18-1) and a cathode plate (19); the positive electrode (6) of the photovoltaic panel (1) is connected to the anode (14-1) of the flowing electrolytic cell via an electromagnetic relay, and the negative electrode (5) of the photovoltaic panel (1) is connected to the cathode (18-1) of the flowing electrolytic cell via an electromagnetic relay; and the coupling controller (3) controls the electrical connection between the photovoltaic panel (1) and the flowing electrolytic cell via the electromagnetic relay.

3. The solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system according to claim 2 is characterized in that: The cathode (18-1) is obtained by using Y30T carbon paper loaded with an electrocatalyst after hydrophobic pretreatment.

4. The solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system according to claim 2 is characterized in that: The anode plate (13) is provided with a first electrolyte solution inlet (24) and a first drain port (25), the middle chamber (16) is provided with a second electrolyte solution inlet (22) and a second drain port (23), and the cathode plate (19) is provided with a carbon dioxide gas inlet (20) and a mixed gas outlet (21); the flow electrolytic cells are arranged in a front-to-back order, the mixed gas outlet (21) of the previous flow electrolytic cell is connected to the carbon dioxide gas inlet (20) of the next flow electrolytic cell, the first drain port (25) of the previous flow electrolytic cell is connected to the first electrolyte solution inlet (24) of the next flow electrolytic cell, and the second drain port (23) of the previous flow electrolytic cell is connected to the second electrolyte solution inlet (22) of the next flow electrolytic cell.

5. The solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system according to claim 4 is characterized in that: The portion of the cathode plate (19) opposite to the cathode (18-1) is arranged as a cavity structure, and the carbon dioxide gas inlet (20) and the mixed gas outlet (21) are both connected to the cavity structure.

6. The solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system according to claim 4 is characterized in that: The portion of the anode plate (13) facing the anode (14-1) is a flow channel, one end of the flow channel is connected to the first electrolyte solution inlet (24), and the other end of the flow channel is connected to the first liquid discharge port (25).

7. The solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system according to claim 4 is characterized in that: The carbon dioxide gas inlet (20) of the first flowing electrolytic cell is connected to a carbon dioxide gas tank (8) via a hose and a carbon dioxide gas valve (7); the first electrolyte solution inlet (24) and the second electrolyte solution inlet (22) of the first flowing electrolytic cell are connected to an electrolyte solution cell (10) via a peristaltic pump (9); the mixed gas outlet (21) of the last flowing electrolytic cell is connected to a gas chromatograph (11); and the first drain outlet (25) and the second drain outlet (23) of the last flowing electrolytic cell are both provided with drain valves (12).

8. The solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system according to claim 1 is characterized in that: The solar radiation sensor (2) is a photoelectric solar radiation sensor, and the temperature sensor is a Pt100 adhesive temperature sensor.

9. A method for dynamically coupling solar photovoltaic power generation with electrocatalytic carbon dioxide reduction reaction, characterized in that: The solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction dynamic coupling system according to any one of claims 1 to 8 comprises: The solar radiation sensor (2) collects the solar radiation intensity irradiated on the photovoltaic panel (1) and transmits it to the coupling controller (3); the temperature sensor collects the working temperature of the photovoltaic panel (1) and transmits it to the coupling controller (3); the flowing electrolytic cell electrocatalyzes the reduction of carbon dioxide to produce ethylene; The coupling controller (3) calculates the number of flowing electrolytic cells that need to be connected to the electrolytic cell group when the current density of the flowing electrolytic cells is maintained within a preset current density range based on the received solar radiation intensity and the operating temperature, and controls the number of flowing electrolytic cells connected to the electrolytic cell group based on the number of flowing electrolytic cells that need to be connected.

10. The method for dynamically coupling solar photovoltaic power generation and electrocatalytic carbon dioxide reduction reaction according to claim 9, characterized in that: The coupling controller (3) calculates the number of flowing electrolytic cells that need to be connected to the electrolytic cell group when the current density of the flowing electrolytic cells is maintained within a preset current density range according to the received solar radiation intensity and the operating temperature, specifically: The photovoltaic model formula is as follows: Where: q is the electron charge number, C; k is the Boltzmann constant, m 2 kg s -2 ·K -1 ; N s is the number of electrolytic cell groups connected in series with the photovoltaic panel; A is the ideal factor of the semiconductor in the photovoltaic panel; I s is the reverse saturation current value; V OC,STC is the open circuit voltage under STC, V; K V is the voltage temperature coefficient, %·K -1 ;I SC,STC is the short-circuit current under STC, A; K I is the photocurrent temperature coefficient, %·K -1 ; V mp,STC is the maximum power point voltage under STC; I mp,STC is the maximum power point current under STC; V t is the thermal voltage of the PV module, V, which is defined as: The battery stack model formula is as follows: Where Ns is the number of electrolytic cell groups connected in series with photovoltaic panels; N p is the number of flow electrolytic cells connected in parallel in the electrolytic cell group; e rev Reversible Potential, V, represents the minimum voltage required for electrochemical reaction to occur; R i is the heat loss resistance (Resistive Heat Loss), Ω, which represents the resistance heat loss term represented by the slope of the IV curve of the flow electrolytic cell; j is the current density, mA cm -2 ; S is the cathode reaction area of ​​the flow electrolytic cell participating in the reaction, cm 2 ; Under the constraint of satisfying the preset current density range, equations (1) to (10) are solved together to obtain the number of flow electrolytic cells that need to be connected in parallel in the electrolytic cell group.

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