Simulation method and system for synthesis gas production by electrolysis of carbon dioxide using anion exchange membranes

Abstract

The application discloses a simulation method and system for synthesizing gas by electrolyzing carbon dioxide through an anion exchange membrane, and comprises the following steps: performing full-cell grid division on a three-dimensional structure model of an electrolytic cell, importing a grid division result into fluid simulation software, and setting simulation parameters, wherein the simulation parameters comprise anode and cathode parameters, gas attributes, working conditions and boundary conditions; loading a carbon dioxide electro-catalysis calculation program into a source term calculation module of each equation in a catalytic layer region of the anode and the cathode, performing coupling solution of fluid mechanics equations and electrochemistry equations, and simulating a working process of the three-dimensional structure model of the electrolytic cell; and performing iterative solution on the working process of the three-dimensional structure model of the electrolytic cell through a solver, and obtaining physical field parameter values; based on the simulation method established by the application, the flow channel structure of the carbon dioxide electrolytic cell can be simulated, analyzed and optimized, and the electrochemical performance of the electrolytic cell can be improved.

Description

Technical Field

[0001] This invention relates to the field of electrocatalysis technology, specifically to a simulation method and system for producing syngas by electrolyzing carbon dioxide using anion exchange membranes. Background Technology

[0002] To address climate change and achieve the "dual carbon" goal, catalytic reduction of carbon dioxide into carbon-based fuels is a promising solution. This approach enables the resource utilization of carbon dioxide and the effective storage of clean energy, significantly improving the absorption capacity of new energy power generation systems such as solar and wind power, and realizing a green carbon cycle. As a thermodynamically stable compound, carbon dioxide exhibits significant advantages over conventional photocatalytic and thermocatalytic reduction. Electrocatalytic reduction of carbon dioxide can be carried out in aqueous solutions at room temperature and pressure, eliminating the need for complex reaction apparatus. It can utilize renewable electricity to achieve the carbon dioxide reduction process under mild conditions, facilitating large-scale practical applications.

[0003] Currently, research on electrocatalytic carbon dioxide processes mainly focuses on catalyst improvement and preparation, while research on reactor design and the internal mass and energy transport processes is limited. Several technical challenges remain in the electrocatalytic production of hydrocarbon fuels from carbon dioxide, such as high overvoltage, low current density, and poor catalyst stability. This necessitates the design of improved, highly active catalytic reactors to achieve stable operation and large-scale application of electrocatalytic carbon dioxide systems. The operating characteristics of carbon dioxide electrolyzers are influenced by internal gas, water, heat, and electricity transport processes. Optimizing the design of carbon dioxide electrocatalytic reduction reactors requires elucidating the mechanisms of gas, water, heat, and electricity transport within the reactor and gaining a deeper understanding of the multi-scale physicochemical processes within the reactor.

[0004] With the improvement of computer computing power and the development of numerical calculation methods, numerical simulation has become an important tool in scientific research. For example, the literature "Research on the reaction characteristics and system of high temperature co-electrolysis of water and carbon dioxide to synthesize methane, Luo Yu, Tsinghua University" proposes to carry out the research on the reaction characteristics and system of CH4 synthesis by solid oxide electrolysis cell (SOEC) using a combination of experimental testing, kinetic calculation and numerical simulation. It focuses on high temperature solid oxide electrolysis cell, rather than low temperature anion membrane electrolysis cell.

[0005] Therefore, in order to simulate the working process of a carbon dioxide electrolyzer and improve its electrochemical performance, it is urgent to develop a high-precision numerical simulation program to conduct in-depth analysis of the multi-scale processes inside the reactor and to achieve coupled calculation of the multi-component flow heat transfer process and the electrochemical reaction process. Summary of the Invention

[0006] The technical problem to be solved by this invention is how to simulate and calculate the working process of a carbon dioxide electrolyzer and optimize the design of a carbon dioxide electrocatalytic reduction reactor.

[0007] The present invention solves the above-mentioned technical problems through the following technical means:

[0008] On the one hand, a simulation method for producing syngas by electrolysis of carbon dioxide using anion exchange membranes is proposed, the method comprising:

[0009] The three-dimensional structural model of the electrolytic cell is meshed, and the meshing results are imported into fluid simulation software and simulation parameters are set. The simulation parameters include anode and cathode parameters, carbon dioxide material properties, working conditions and boundary conditions.

[0010] The carbon dioxide electrocatalysis calculation program is loaded into the source term calculation module of each equation in the catalytic layer region of the anode and cathode, and the fluid dynamics equation and electrochemical equation are coupled and solved to simulate the working process of the three-dimensional structure model of the electrolytic cell.

[0011] The working process of the three-dimensional structural model of the electrolytic cell is iteratively solved by a solver to obtain the physical field parameter values.

[0012] Furthermore, the three-dimensional structural model of the electrolytic cell includes an anion exchange membrane, a cathode current collector, a cathode flow channel, a cathode gas diffusion layer, and a cathode current catalyst layer arranged sequentially from far to near on one side of the anion exchange membrane, and an anode current collector, an anode flow channel, an anode gas diffusion layer, and an anode current catalyst layer arranged sequentially from far to near on the other side of the anion exchange membrane.

[0013] Furthermore, the process of loading the carbon dioxide electrocatalysis calculation program into the source term calculation module of each equation in the catalytic layer region of the anode and cathode, and performing coupled solution of the hydrodynamic equations and electrochemical equations to simulate the working process of the three-dimensional structural model of the electrolytic cell includes:

[0014] Load the carbon dioxide electrocatalysis calculation program into the source term calculation module of each equation in the catalytic layer region of the anode and cathode;

[0015] The concentrations of each component in the catalyst layer region are obtained by solving the fluid dynamics equations.

[0016] Based on the concentration of each component, the reaction current density of each reaction in the catalyst layer region is obtained by solving the electrochemical reaction equation, and the hydrodynamic equation is solved based on each reaction current density to simulate the working process of the three-dimensional structural model of the electrolytic cell.

[0017] Furthermore, the fluid dynamics equations include:

[0018] mass conservation equation:

[0019]

[0020] Component conservation equation:

[0021]

[0022] Momentum equation:

[0023]

[0024] In the formula: ε is the porosity of the porous electrode; ρ is the velocity vector of the gas; ρ is the density of the reacting gas; s m For quality source items, S mi Let y be the mass source term of the i-th component; i D represents the mass fraction of component i; i p is the gas diffusivity; N is the number of component species; p, μ, S mom These represent the pressure, viscosity coefficient, and momentum source term within the porous electrode, respectively. This is the symbol for the gradient operator.

[0025] Furthermore, in the catalyst layer region, the formulas for calculating the gas consumption and generation per unit volume are as follows:

[0026] Cathode catalyst layer region:

[0027]

[0028]

[0029]

[0030]

[0031] Anode catalyst layer region:

[0032]

[0033]

[0034] Where: M O2 M H2O M CO2 M CO M H2 R represents the molar mass of oxygen, water, carbon dioxide, carbon monoxide, and hydrogen, respectively; an and R cat R represents the exchange current density at the anode and cathode, respectively. cat,CO and These represent the exchange current densities for the electrochemical reactions at the cathode that produce CO and H2, respectively; F is the Faraday constant; S CO2 S represents the source term in the CO2 component transport equation resulting from consumption due to electrochemical reactions; CO The source term in the CO component transport equation is the consumption resulting from electrochemical reactions; S H2 The source term in the component transport equation of H2 is the consumption resulting from the electrochemical reaction; S H2O The source term in the component transport equation of H2O is the consumption resulting from the electrochemical reaction; S O2 This is the source term in the component transport equation of O2 resulting from consumption due to electrochemical reactions.

[0035] Furthermore, the formula for calculating the momentum source term is:

[0036]

[0037] Where: K i This represents the permeability coefficient of the porous electrode.

[0038] Furthermore, the electrochemical reaction equation includes:

[0039] The equations for electron conduction in a solid conductor and ion conduction in a film phase are as follows:

[0040]

[0041]

[0042] The equation for calculating the current density on the anode side is:

[0043]

[0044] The formulas for calculating the current density corresponding to the carbon dioxide reduction reaction and hydrogen evolution reaction on the cathode side are as follows:

[0045]

[0046]

[0047] Where: σ sol and σ mem φ represents the conductivity of the solid phase and the film phase, respectively. sol and φ mem These represent the solid-state potential and the film-state potential, respectively; R sol R is the electron exchange current density. mem The membrane current density; ξ represents the reference current density at the anode and cathode, respectively; an ξ catand are the active specific surface areas of the anode and cathode, respectively; and These are the actual and reference concentrations of the local gas components, respectively; γ cat For concentration index; α an α cat η represents the transfer coefficient of the overpotential between the anode and cathode. an η cat These represent the overpotentials of the anode and cathode, respectively; F represents the Faraday constant; R represents the gas constant; and T represents the temperature. R is the gradient operator; an and R cat R represents the exchange current density at the anode and cathode, respectively. cat,CO and These represent the exchange current densities for the electrochemical reactions at the cathode that generate CO and H2, respectively.

[0048] Furthermore, the iterative solution process of the three-dimensional structural model of the electrolytic cell using a solver to obtain physical field parameter values ​​includes:

[0049] The iterative algorithm, iterative parameters, and monitoring parameters are set. The iterative algorithm adopts the SIMPLE algorithm, the iterative parameters are the relaxation factors of each solution variable, and the monitoring parameters are the residuals of each conservation equation.

[0050] The working process of the three-dimensional structural model of the electrolytic cell is iteratively solved by a solver, and the iteration number is incremented by 1.

[0051] When the set number of iterations is reached, the physical field parameter values ​​are output;

[0052] If the set number of iterations is not reached, the iterative solution will be repeated.

[0053] Furthermore, the fluid simulation software used is Fluent.

[0054] Secondly, the present invention also proposes a simulation system for producing syngas by electrolysis of carbon dioxide using anion exchange membranes, the system comprising:

[0055] The model processing module is used to perform full-cell mesh generation on the three-dimensional structural model of the electrolytic cell, import the mesh generation results into the fluid simulation software, and set the simulation parameters, including anode and cathode parameters, carbon dioxide material properties, working conditions, and boundary conditions.

[0056] The coupled solution module is used to load the carbon dioxide electrocatalysis calculation program into the source term calculation module of each equation in the catalytic layer region of the anode and cathode, and perform coupled solution of the hydrodynamic equation and electrochemical equation to simulate the working process of the three-dimensional structural model of the electrolytic cell.

[0057] The iterative solution module is used to iteratively solve the working process of the three-dimensional structural model of the electrolytic cell through a solver to obtain the physical field parameter values.

[0058] The advantages of this invention are:

[0059] (1) Based on the constructed three-dimensional numerical model, the present invention can couple the flow and component transport in the flow channel and porous medium with the electrochemical reaction in the electrolytic cell to realize the simulation calculation of the working process of the carbon dioxide electrolytic cell, and thus analyze the influence of flow and gas transport characteristics on the performance of carbon dioxide electrolysis. Based on the simulation method established by the present invention, it can be used to simulate, analyze and optimize the flow channel structure of the carbon dioxide electrolytic cell, thereby improving the electrochemical performance of the electrolytic cell.

[0060] (2) By predicting the electrochemical performance of the carbon dioxide electrolyzer and the internal flow field and component distribution, this invention can identify the different effects of parameters such as flow field on the carbon dioxide reduction reaction and the hydrogen evolution reaction.

[0061] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0062] Figure 1 This is a schematic flowchart of a simulation method for producing syngas by electrolysis of carbon dioxide using anion exchange membrane, as proposed in an embodiment of the present invention.

[0063] Figure 2 This is a structural diagram of the three-dimensional structural model of the electrolytic cell in an embodiment of the present invention;

[0064] Figure 3 This is a schematic diagram of the geometric model and mesh generation of a two-chamber electrolytic cell in an embodiment of the present invention, wherein (a) is the geometric model of the two-chamber electrolytic cell, and (b) is the mesh generation result;

[0065] Figure 4 This is a schematic diagram of the structure of a simulation system for producing syngas by electrolysis of carbon dioxide using anion exchange membrane, as proposed in an embodiment of the present invention.

[0066] Figure 5 This is a schematic diagram of the structure of the experimental platform for producing syngas by electrolysis of carbon dioxide constructed according to an embodiment of the present invention;

[0067] Figure 6 This is the curve showing the change of current over time measured at a voltage of 3.4V in this embodiment of the invention;

[0068] Figure 7 This is a comparison chart of current density and product gas concentration at the electrolytic cell outlet under different voltages in embodiments of the present invention;

[0069] Figure 8 This is a comparison chart of current densities obtained from experiments and numerical simulations at different voltages in embodiments of the present invention;

[0070] Figure 9 This is a schematic diagram of the current density distribution on the cathode side of the electrolytic cell according to an embodiment of the present invention;

[0071] Figure 10 This is a schematic diagram of the concentration field cloud of carbon monoxide and hydrogen, the cathode-side products of an embodiment of the present invention. (a) is the concentration field cloud of carbon monoxide, and (b) is the concentration field cloud of hydrogen.

[0072] Figure 11 This is a flowchart of the iterative algorithm in an embodiment of the present invention. Detailed Implementation

[0073] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0074] like Figure 1 As shown, the first embodiment of the present invention proposes a simulation method for producing syngas by electrolysis of carbon dioxide using anion exchange membranes. The method includes the following steps:

[0075] S10. Perform full-cell mesh generation on the three-dimensional structural model of the electrolytic cell, import the mesh generation results into the fluid simulation software and set the simulation parameters, including anode and cathode parameters, gas properties, working conditions and boundary conditions.

[0076] It should be noted that anode and cathode parameters include thermophysical properties such as density, specific heat, and thermal conductivity, as well as electrical conductivity and ionic conductivity. Gas properties include thermophysical properties such as density, specific heat, thermal conductivity, and component diffusion coefficient, as well as electrical conductivity. Boundary conditions include potential boundary conditions and temperature boundary conditions for the anode and cathode, and flow boundary conditions at the inlet and outlet of the flow channel.

[0077] It should be noted that in this embodiment, the constructed three-dimensional structure model of the electrolytic cell is meshed, the mesh is imported into the fluid simulation software, the fuel cell and electrolysis model module in the fluid simulation software is loaded, and the model parameters of the anode and cathode are set in the module; carbon dioxide, carbon monoxide and other materials are added to the mixed gas, new material properties are defined, and working conditions and boundary conditions are set.

[0078] S20. Load the carbon dioxide electrocatalysis calculation program into the source term calculation module of each equation in the catalytic layer region of the anode and cathode, perform coupled solution of fluid dynamics equation and electrochemical equation, and simulate the working process of the three-dimensional structure model of the electrolytic cell.

[0079] It should be noted that the carbon dioxide electrocatalysis calculation program edited in this embodiment is a UDF program.

[0080] S30. The working process of the three-dimensional structural model of the electrolytic cell is iteratively solved by the solver to obtain the physical field parameter values.

[0081] This embodiment establishes a simplified model of the electrolytic cell based on computational fluid dynamics, coupling the flow and component transport within the channel and porous medium with the electrochemical reactions within the electrolytic cell. This enables the simulation calculation of the working process of the carbon dioxide electrolytic cell, allowing for the analysis of the influence of flow and gas transport characteristics on the performance of carbon dioxide electrolysis. Based on the simulation method established in this invention, the distribution of pressure, velocity, component concentration, and current density inside the electrolytic cell can be simulated and analyzed. Furthermore, the distribution characteristics of current density and its influence by other variables can be analyzed, and the current distribution under different structures can be compared to optimize the flow channel structure of the carbon dioxide electrolytic cell, thereby improving the electrochemical performance of the electrolytic cell.

[0082] In one embodiment, such as Figure 2 As shown, the three-dimensional structural model of the electrolytic cell includes an anion exchange membrane, a cathode current collector, a cathode flow channel, a cathode gas diffusion layer, and a cathode current catalyst layer arranged sequentially from far to near on one side of the anion exchange membrane, and an anode current collector, an anode flow channel, an anode gas diffusion layer, and an anode current catalyst layer arranged sequentially from far to near on the other side of the anion exchange membrane; wherein, the constructed two-chamber electrolytic cell geometric model is as follows: Figure 3 As shown in (a) in 3, and (b) in 3, the result of mesh generation.

[0083] Specifically, the fluid domain of the anode in the full cell includes an anode current collector, an anode flow channel, an anode gas diffusion layer, and an anode current catalyst layer; the fluid domain of the cathode includes a cathode current collector, a cathode flow channel, a cathode gas diffusion layer, and a cathode current catalyst layer; both the anode and cathode porous electrodes include a diffusion layer and a catalyst layer; the electron transport section includes a catalyst layer, a diffusion layer, and an electrode plate. Carbon dioxide flows into the reactor through the cathode flow channel, reaches the cathode catalyst layer through the cathode gas diffusion layer, and anode water also reaches the anode catalyst layer through the anode diffusion layer, where cathode and anode reactions occur respectively.

[0084] It should be noted that in the electrolytic cell, reactant gases need to be continuously transported to the internal electrochemical reaction site through the flow fields of the anode and cathode. The gaseous reactants undergo electrochemical reactions in the catalyst layers of the anode and cathode, while anions are transported through the ion-exchange membrane. This complex system involves the coupling of numerous physical and chemical phenomena, which influence and constrain each other. Considering the complexity and feasibility of the problem, the following assumptions are made in the numerical calculations:

[0085] (1) The electrolytic cell operates under stable conditions;

[0086] (2) Since the fluid has a limited flow velocity in the flow channel, it is generally considered to be laminar flow and the gas is incompressible;

[0087] (3) The materials of the gas diffusion layer, ion exchange membrane and catalyst layer are isotropic and uniform;

[0088] (4) The effect of gravity is negligible, and it is assumed that water exists in the gaseous state;

[0089] (5) Ignore the heat generated by electrochemical reactions and the ohmic heat generated by current conduction.

[0090] In one embodiment, step S20: loading the carbon dioxide electrocatalysis calculation program into the source term calculation module of each equation in the catalytic layer region of the anode and cathode, performing coupled solution of the hydrodynamic equation and electrochemical equation, and simulating the working process of the three-dimensional structural model of the electrolytic cell, specifically includes the following steps:

[0091] S21. Load the carbon dioxide electrocatalysis calculation program into the source term calculation module of each equation in the catalytic layer region of the anode and cathode;

[0092] S22. The concentrations of each component in the catalyst layer region are obtained by solving the fluid dynamics equations.

[0093] S23. Based on the concentration of each component, the reaction current density of each reaction in the catalyst layer region is obtained by solving the electrochemical reaction equation, and the hydrodynamic equation is solved based on each reaction current density to simulate the working process of the three-dimensional structure model of the electrolytic cell.

[0094] It should be noted that in this embodiment, the concentration of each component in the catalyst layer region is obtained by solving the fluid dynamics equations, and the component concentrations are provided to the electrochemical reaction equations for current density calculation. The reaction current density in the catalyst layer region is obtained by solving the electrochemical reaction equations, and then the source terms of each fluid dynamics equation are obtained, thereby enabling the fluid dynamics equations to be solved and realizing the simulation of the carbon dioxide electrolysis reactor.

[0095] In one embodiment, the fluid dynamics equations include:

[0096] The mass conservation equations for reactant gases and products in an electrolytic cell are as follows:

[0097]

[0098] The electrolytic cell contains various gaseous components, and its composition conservation equation is as follows:

[0099]

[0100] Momentum equation:

[0101]

[0102] In the formula: ε is the porosity of the porous electrode, which is 1 in the flow channel; ρ is the velocity vector of the gas; ρ is the density of the reacting gas; s m For quality source items, S mi For the mass source term of the i-th component, since there is no electrochemical reaction in the gas diffusion layer, proton exchange membrane, and gas channel, the mass source term can be considered as 0; y i D represents the mass fraction of component i; i p is the gas diffusivity; N is the number of component species; p, μ, S mom These represent the pressure, viscosity coefficient, and momentum source term within the porous electrode, respectively. This is the symbol for the gradient operator.

[0103] In one embodiment, the formula for calculating the gas consumption and generation per unit volume in the catalyst layer region is as follows:

[0104] Cathode catalyst layer region:

[0105]

[0106]

[0107]

[0108]

[0109] Anode catalyst layer region:

[0110]

[0111]

[0112] Where: M O2 M H2O M CO2 M CO M H2R represents the molar mass of oxygen, water, carbon dioxide, carbon monoxide, and hydrogen, respectively; an and R cat R represents the exchange current density at the anode and cathode, respectively. cat,CO and These represent the exchange current densities for the electrochemical reactions at the cathode that produce CO and H2, respectively; F is the Faraday constant; S CO2 The source term in the CO2 component transport equation is the consumption due to electrochemical reactions; S CO The source term in the CO component transport equation is the consumption resulting from electrochemical reactions; S H2 The source term in the component transport equation of H2 is the consumption resulting from the electrochemical reaction; S H2O The source term in the component transport equation of H2O is the consumption resulting from the electrochemical reaction; S O2 This is the source term in the component transport equation of O2 resulting from consumption due to electrochemical reactions.

[0113] In one embodiment, the momentum source term within the gas channel and proton exchange membrane is neglected, and the momentum source within the catalyst layer is calculated using Darcy's rule. The formula for calculating the momentum source term is as follows:

[0114]

[0115] In the formula: K i This represents the permeability coefficient of the porous electrode.

[0116] In one embodiment, the key to the electrochemical mathematical model lies in calculating the battery output using the electrochemical reaction rates at the two electrodes, and the magnitude of the reaction rate is determined by the surface overpotential between the solid-phase potential and the film-phase potential. Therefore, this embodiment solves the electrochemical reaction by solving the two-phase overpotential balance equation.

[0117] The electrochemical reaction equations include:

[0118] The equations for electron conduction in solid conductors (such as current collectors and diffusers) and ion conduction in the film phase are as follows:

[0119]

[0120]

[0121] The anode-side current density can be calculated using the Tafel equation:

[0122]

[0123] On the cathode side, not only does the carbon dioxide reduction reaction occur, but the hydrogen evolution reaction also occurs. The current densities corresponding to the carbon dioxide reduction reaction and the hydrogen evolution reaction are respectively:

[0124]

[0125]

[0126] Where: σ sol and σ mem φ represents the conductivity of the solid phase and the film phase, respectively. sol and φ mem These represent the solid-state potential and the film-state potential, respectively; R sol R is the electron exchange current density. mem The membrane current density; ξ represents the reference current density at the anode and cathode, respectively; an ξ cat and are the active specific surface areas of the anode and cathode, respectively; and These represent the local gaseous component concentration and the reference concentration, respectively; γ cat For concentration index; for the transfer coefficient of overpotential between anode and cathode; η an η cat These represent the overpotentials of the anode and cathode, respectively; F represents the Faraday constant; R represents the gas constant; and T represents the temperature. R is the gradient operator; an and R cat R represents the exchange current density at the anode and cathode, respectively. cat,CO and These represent the exchange current densities for the electrochemical reactions at the cathode that generate CO and H2, respectively.

[0127] In one embodiment, the iterative solution process of the three-dimensional structural model of the electrolytic cell using a solver to obtain physical field parameter values ​​includes:

[0128] The iterative algorithm, iterative parameters, and monitoring parameters are set, wherein the iterative algorithm adopts the SIMPLE algorithm, the iterative parameters are the relaxation factors of each solution variable, and the monitoring parameters are the residuals of each conservation equation.

[0129] The working process of the three-dimensional structural model of the electrolytic cell is iteratively solved by a solver, and the number of iterations is incremented by 1.

[0130] When the set number of iterations is reached, the physical field parameter values ​​are output;

[0131] If the set number of iterations is not reached, the iterative solution will be repeated.

[0132] It should be noted that, as Figure 11 As shown, this embodiment, based on the SIMPLE algorithm for solving the pressure-velocity coupling problem, considers the coupling effect between the component concentration field and the potential field to solve for other scalar fields such as component and potential. Specifically, in the component equation, a source term representing the influence of the electrochemical reaction on component formation or consumption is added; in the potential equation, the calculation of the exchange current requires parameters such as the local component field.

[0133] In one embodiment, the fluid simulation software includes, but is not limited to, software developed based on Fluent software.

[0134] In addition, such as Figure 4 As shown, the second embodiment of the present invention proposes a simulation system for producing syngas by electrolysis of carbon dioxide using anion exchange membranes. The system includes:

[0135] Model processing module 10 is used to perform full cell mesh generation on the three-dimensional structural model of the electrolytic cell, import the mesh generation results into fluid simulation software and set simulation parameters, including anode and cathode parameters, gas properties, working conditions and boundary conditions.

[0136] The coupled solution module 20 is used to load the carbon dioxide electrocatalysis calculation program into the source term calculation module of each equation in the catalytic layer region of the anode and cathode, and to perform coupled solution of the hydrodynamic equation and the electrochemical equation to simulate the working process of the three-dimensional structural model of the electrolytic cell.

[0137] The iterative solution module 30 is used to iteratively solve the working process of the three-dimensional structural model of the electrolytic cell through a solver to obtain the physical field parameter values.

[0138] In one embodiment, the three-dimensional structural model of the electrolytic cell includes an anion exchange membrane, a cathode current collector, a cathode flow channel, a cathode gas diffusion layer, and a cathode current catalyst layer arranged sequentially from far to near on one side of the anion exchange membrane, and an anode current collector, an anode flow channel, an anode gas diffusion layer, and an anode current catalyst layer arranged sequentially from far to near on the other side of the anion exchange membrane.

[0139] In one embodiment, the coupled solution module 20 includes:

[0140] The loading unit is used to load the carbon dioxide electrocatalysis calculation program into the source term calculation module of each equation in the catalytic layer region of the anode and cathode;

[0141] The first solution unit is used to obtain the concentration of each component in the catalyst layer region by solving the fluid dynamics equations;

[0142] The second solution unit is used to obtain the reaction current density of each catalyst layer region by solving the electrochemical reaction equation based on the concentration of each component, and to solve the hydrodynamic equation based on each reaction current density to simulate the working process of the three-dimensional structural model of the electrolytic cell.

[0143] In one embodiment, the fluid dynamics equations include:

[0144] mass conservation equation:

[0145]

[0146] Component conservation equation:

[0147]

[0148] Momentum equation:

[0149]

[0150] In the formula: ε is the porosity of the porous electrode; ρ is the velocity vector of the gas; ρ is the density of the reacting gas; s m For quality source items, S mi Let y be the mass source term of the i-th component; i D represents the mass fraction of component i; i p is the gas diffusivity; N is the number of component species; p, μ, S mom These represent the pressure, viscosity coefficient, and momentum source term within the porous electrode, respectively. This is the symbol for the gradient operator.

[0151] Furthermore, in the catalyst layer region, the formulas for calculating the gas consumption and generation per unit volume are as follows:

[0152] Cathode catalyst layer region:

[0153]

[0154]

[0155]

[0156]

[0157] Anode catalyst layer region:

[0158]

[0159]

[0160] Where: M O2 MH2O M CO2 M CO M H2 R represents the molar mass of oxygen, water, carbon dioxide, carbon monoxide, and hydrogen, respectively; an and R cat R represents the exchange current density at the anode and cathode, respectively. cat,CO and These represent the exchange current densities for the electrochemical reactions at the cathode that produce CO and H2, respectively; F is the Faraday constant; S CO2 The source term in the CO2 component transport equation is the consumption due to electrochemical reactions; S CO The source term in the CO component transport equation is the consumption resulting from electrochemical reactions; S H2 The source term in the component transport equation of H2 is the consumption resulting from the electrochemical reaction; S H2O The source term in the component transport equation of H2O is the consumption resulting from the electrochemical reaction; S O2 This is the source term in the component transport equation of O2 resulting from consumption due to electrochemical reactions.

[0161] Furthermore, the formula for calculating the momentum source term is:

[0162]

[0163] Where: K i This represents the permeability coefficient of the porous electrode.

[0164] In one embodiment, the electrochemical reaction equation includes:

[0165] The equations for electron conduction in a solid conductor and ion conduction in a film phase are as follows:

[0166]

[0167]

[0168] The equation for calculating the current density on the anode side is:

[0169]

[0170] The formulas for calculating the current density corresponding to the carbon dioxide reduction reaction and hydrogen evolution reaction on the cathode side are as follows:

[0171]

[0172]

[0173] Where: σ sol and σ memφ represents the conductivity of the solid phase and the film phase, respectively. sol and φ mem These represent the solid-state potential and the film-state potential, respectively; R sol R is the electron exchange current density. mem The membrane current density; ξ represents the reference current density at the anode and cathode, respectively; an ξ cat and are the active specific surface areas of the anode and cathode, respectively; and These are the actual and reference concentrations of the local gas components, respectively; γ cat For concentration index; α an α cat The transfer coefficient representing the overpotential between the anode and cathode; η an η cat These represent the overpotentials of the anode and cathode, respectively; F represents the Faraday constant; R represents the gas constant; and T represents the temperature. R is the gradient operator; an and R cat R represents the exchange current density at the anode and cathode, respectively. cat,CO and These represent the exchange current densities for the electrochemical reactions at the cathode that generate CO and H2, respectively.

[0174] It should be noted that other embodiments or implementation methods of the simulation system for producing syngas by electrolysis of carbon dioxide using anion exchange membrane described in this invention can refer to the above-mentioned method embodiments, and will not be repeated here.

[0175] Furthermore, to verify the effectiveness of the simulation method proposed in this embodiment, a carbon dioxide electrolysis conversion test system was built. The basic working performance of the carbon dioxide reduction electrolyzer under different voltage conditions was tested, and the simulated current density was compared with the experimental results. The simulation results were close to the experimental measurement results, with a relative error of no more than 10% under all measurement conditions. The numerical simulation method proposed in this embodiment can accurately simulate and calculate the working process of the carbon dioxide electrocatalytic reduction reactor, and based on this, the internal working characteristics of the mobile phase carbon dioxide reduction electrolyzer can be analyzed.

[0176] Specifically, the experimental platform for producing syngas by electrolysis of carbon dioxide constructed in this embodiment is as follows: Figure 5 As shown, it mainly includes an air intake system, a liquid intake system, a voltage control system, an electrolytic synthesis gas reactor, and a supporting electrochemical workstation.

[0177] The gas inlet system consists of a carbon dioxide cylinder, a pressure reducing valve, and a mass flow controller; the liquid inlet system consists of an ultrapure water system, a water storage tank, and a peristaltic pump. The ultrapure water system employs pretreatment, reverse osmosis technology, ultrapure water treatment, and post-treatment methods to almost completely remove conductive media from the water, and also removes non-dissociated colloidal substances, gases, and organic matter to very low levels, reducing side reactions and improving the Faraday efficiency of carbon dioxide in the reaction. The voltage control system consists of a computer, an electrochemical workstation, and a current amplifier. The electrochemical workstation can perform measurements such as cyclic voltammetry, AC impedance spectroscopy, AC voltammetry, current titration, and potentiometric titration, and can simultaneously operate in two-electrode, three-electrode, and four-electrode modes. The four-electrode mode is mainly used for electrochemical measurements in this experiment, eliminating measurement errors caused by cable and contact resistance, and ensuring that the voltage remains at a constant value. The current amplifier can convert high resistance to low resistance and small current changes to large current changes, refining the current and better reflecting subtle changes in the reaction. The electrolytic synthesis gas reactor consists of electrode plates, a diffusion layer, a catalyst layer, an anion exchange membrane, and gaskets.

[0178] Anodized iridium ECP402 carbon paper, cathode film A40, and cathode nano-silver catalyst were sprayed onto Toray 50% hydrophobic carbon paper and dried using an electric heating platform. The voltage was controlled using an electrochemical workstation, and carbon dioxide flow rate was controlled at 30 sccm through a seven-star flow meter. A peristaltic pump was used to introduce 1 mol / L KOH solution into the anode, and the pump speed was adjusted to 2.0 rpm. Activation was performed at 3.0V for 15 minutes (the activation time varied depending on the reactor voltage). Afterward, pure water was used to continue the experiment and observe the phenomena.

[0179] This experiment measured the operating performance of the electrolytic cell within a voltage range of 3.0V-3.6V. For example... Figure 6 The figure shows the current-time curve measured at 3.4V. Initially, a 1 mol / L potassium hydroxide solution was introduced into the anode of the reactor, rapidly activating the reaction to 160 mA / cm². To prevent salting out, pure water was used to replace the potassium hydroxide solution, resulting in decreased reactor conductivity and a slow drop in current density to 140 mA / cm². After the replacement of the alkali solution with pure water, the electrochemical polarization resistance decreased over time, and the reaction current increased, reaching equilibrium at a current density of 150 mA / cm². Since there was no water on the cathode side, a concentration difference existed across the membrane. Water from the anode side diffused through the membrane to the cathode side; this process is called "reverse osmosis." As time progressed, the carbon paper on the cathode side became flooded, resulting in a loss of catalyst performance, and the reactor current density began to gradually decrease.

[0180] from Figure 7As can be seen, when the applied voltage increases from 3.0V to 3.6V, the current density increases almost linearly. Furthermore, as the voltage increases, the concentration of carbon monoxide products rises rapidly, while the concentration of hydrogen gas, a byproduct, initially decreases slightly and then increases with further voltage increases.

[0181] To verify the accuracy of the procedure, this embodiment calculated the electrolytic cell operating characteristics under different voltages between 3.0 and 3.6V, referring to the experimental measurement conditions. The average current density at different voltages was obtained by performing an area-weighted average of the current density at the electrodes. The simulated current density was compared with the experimental results, and the results are as follows: Figure 8 As shown, the simulation results are quite close to the experimental measurements, with a relative error of no more than 10% under all measurement conditions. It is normal for the simulation results to have some error compared to the experimental results, because the simulation calculations have been simplified to account for the complexity of the overall physicochemical process. For example, the presence of liquid water is not considered, and the effects of reaction heat and ohmic heat on temperature are ignored, all of which affect the accuracy of the calculation results. Therefore, the numerical simulation method proposed in this embodiment can accurately simulate the working process of the carbon dioxide electrocatalytic reduction reactor.

[0182] The basic operating characteristics of the electrolytic cell are analyzed below based on simulation results at 3.0V, such as... Figures 9 to 10 The diagram shows the current density distribution on the cathode side of the electrolytic cell. It can be seen that the current density is higher below the ribs compared to directly below the channel, especially at the corner where the channel contacts the diffusion layer, where the current flux density is even higher. This is because the gas flow channel is non-conductive, and the current must be transferred to the external circuit through the current collector.

[0183] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0184] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0185] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A simulation method for producing syngas by electrolysis of carbon dioxide using anion exchange membranes, characterized in that, The method includes: The three-dimensional structural model of the electrolytic cell is meshed, and the meshing results are imported into fluid simulation software and simulation parameters are set. The simulation parameters include anode and cathode parameters, gas properties, working conditions and boundary conditions. The carbon dioxide electrocatalysis calculation program is loaded into the source term calculation module of each equation in the catalytic layer region of the anode and cathode, and the fluid dynamics equation and electrochemical equation are coupled and solved to simulate the working process of the three-dimensional structure model of the electrolytic cell. The working process of the three-dimensional structural model of the electrolytic cell is iteratively solved by a solver to obtain the physical field parameter values. The fluid dynamics equations include: mass conservation equation: Component conservation equation: Momentum equation: In the formula: Porosity of the porous electrode; The velocity vector of the gas; The density of the reacting gas; For quality source items, , For the first The quality source items of the various components; Indicates components The mass fraction; This refers to the gas diffusivity. N The number of component types, , , These represent the pressure, viscosity coefficient, and momentum source term within the porous electrode, respectively. This is the gradient operator symbol; The electrochemical equations include: The equations for electron conduction in a solid conductor and ion conduction in a film phase are as follows: The equation for calculating the current density on the anode side is: The formulas for calculating the current density corresponding to the carbon dioxide reduction reaction and hydrogen evolution reaction on the cathode side are as follows: In the formula: and These represent the electrical conductivity of the solid phase and the film phase, respectively. and These represent the solid-state potential and the film-state potential, respectively. It is the electron exchange current density; The membrane current density; , These are the reference current densities for the anode and cathode, respectively. , and are the active specific surface areas of the anode and cathode, respectively; and These are the actual and reference concentrations of the local gas components, respectively. Concentration index; , The transfer coefficient representing the overpotential between the anode and cathode; , These represent the overpotentials at the anode and cathode, respectively. F Denotes Faraday's constant; R Represents the gas constant. T Indicates temperature; For gradient operators; and These represent the exchange current densities at the anode and cathode, respectively. and These represent the exchange current densities for the electrochemical reactions at the cathode that generate CO and H2, respectively.

2. The simulation method for producing syngas by electrolysis of carbon dioxide using anion exchange membranes as described in claim 1, characterized in that, The three-dimensional structural model of the electrolytic cell includes an anion exchange membrane, a cathode current collector, a cathode flow channel, a cathode gas diffusion layer, and a cathode current catalyst layer arranged sequentially from far to near on one side of the anion exchange membrane, and an anode current collector, an anode flow channel, an anode gas diffusion layer, and an anode current catalyst layer arranged sequentially from far to near on the other side of the anion exchange membrane.

3. The simulation method for producing syngas by electrolysis of carbon dioxide using anion exchange membranes as described in claim 1, characterized in that, The process of loading the carbon dioxide electrocatalysis calculation program into the source term calculation module of each equation in the catalytic layer region of the anode and cathode, performing coupled solution of the hydrodynamic equations and electrochemical equations, and simulating the working process of the three-dimensional structural model of the electrolytic cell includes: Load the carbon dioxide electrocatalysis calculation program into the source term calculation module of each equation in the catalytic layer region of the anode and cathode; The concentrations of each component in the catalyst layer region are obtained by solving the fluid dynamics equations. Based on the concentration of each component, the reaction current density of each region in the catalyst layer is obtained by solving the electrochemical equation, and the hydrodynamic equation is solved based on the reaction current density to simulate the working process of the three-dimensional structural model of the electrolytic cell.

4. The simulation method for producing syngas by electrolysis of carbon dioxide using anion exchange membrane as described in claim 1, characterized in that, In the catalyst layer region, the formulas for calculating the gas consumption and generation per unit volume are as follows: Cathode catalyst layer region: Anode catalyst layer region: In the formula: , , , , These represent the molar masses of oxygen, water, carbon dioxide, carbon monoxide, and hydrogen, respectively. and These represent the exchange current densities at the anode and cathode, respectively. and These represent the exchange current densities for the electrochemical reactions at the cathode that generate CO and H2, respectively. It is Faraday's constant; This refers to the source term in the CO2 component transport equation resulting from consumption due to electrochemical reactions; This is the source term in the component transport equation of CO resulting from consumption due to electrochemical reactions; This is the source term in the component transport equation of H2 resulting from consumption due to electrochemical reactions; This is the source term in the component transport equation of H2O, resulting from the consumption generated by the electrochemical reaction; This is the source term in the component transport equation of O2 resulting from consumption due to electrochemical reactions.

5. The simulation method for producing syngas by electrolysis of carbon dioxide using anion exchange membranes as described in claim 1, characterized in that, The formula for calculating the momentum source term is: In the formula: This represents the permeability coefficient of the porous electrode.

6. The simulation method for producing syngas by electrolysis of carbon dioxide using anion exchange membrane as described in claim 1, characterized in that, The iterative solution process of the three-dimensional structural model of the electrolytic cell using a solver to obtain physical field parameter values ​​includes: The iterative algorithm, iterative parameters, and monitoring parameters are set, wherein the iterative algorithm adopts the SIMPLE algorithm, the iterative parameters are the relaxation factors of each solution variable, and the monitoring parameters are the residuals of each conservation equation. The working process of the three-dimensional structural model of the electrolytic cell is iteratively solved by a solver, and the number of iterations is incremented by 1. When the set number of iterations is reached, the physical field parameter values ​​are output; If the set number of iterations is not reached, the iterative solution will be repeated.

7. The simulation method for producing syngas by electrolysis of carbon dioxide using anion exchange membrane as described in claim 1, characterized in that, The fluid simulation software used is Fluent.

8. A simulation system for producing syngas by electrolysis of carbon dioxide using anion exchange membranes, characterized in that, The system includes: The model processing module is used to perform full-cell mesh generation on the three-dimensional structural model of the electrolytic cell, import the mesh generation results into the fluid simulation software, and set the simulation parameters, including anode and cathode parameters, gas properties, working conditions, and boundary conditions. The coupled solution module is used to load the carbon dioxide electrocatalysis calculation program into the source term calculation module of each equation in the catalytic layer region of the anode and cathode, and perform coupled solution of the hydrodynamic equation and electrochemical equation to simulate the working process of the three-dimensional structural model of the electrolytic cell. The iterative solution module is used to iteratively solve the working process of the three-dimensional structural model of the electrolytic cell through a solver to obtain the physical field parameter values. The fluid dynamics equations include: mass conservation equation: Component conservation equation: Momentum equation: In the formula: Porosity of the porous electrode; The velocity vector of the gas; The density of the reacting gas; For quality source items, , For the first The quality source items of the various components; Indicates components The mass fraction; This refers to the gas diffusivity. N The number of component types, , , These represent the pressure, viscosity coefficient, and momentum source term within the porous electrode, respectively. This is the symbol for the gradient operator; The electrochemical equations include: The equations for electron conduction in a solid conductor and ion conduction in a film phase are as follows: The equation for calculating the current density on the anode side is: The formulas for calculating the current density corresponding to the carbon dioxide reduction reaction and hydrogen evolution reaction on the cathode side are as follows: In the formula: and These represent the electrical conductivity of the solid phase and the film phase, respectively. and These represent the solid-state potential and the film-state potential, respectively. It is the electron exchange current density; The membrane current density; , These are the reference current densities for the anode and cathode, respectively. , and are the active specific surface areas of the anode and cathode, respectively; and These are the actual and reference concentrations of the local gas components, respectively. Concentration index; , The transfer coefficient representing the overpotential between the anode and cathode; , These represent the overpotentials at the anode and cathode, respectively. F Denotes Faraday's constant; R Represents the gas constant. T Indicates temperature; For gradient operators; and These represent the exchange current densities at the anode and cathode, respectively. and These represent the exchange current densities for the electrochemical reactions at the cathode that generate CO and H2, respectively.

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