Method for simulating direct synthesis of hydrogen peroxide from hydrogen and oxygen in porous membrane reactor based on COMSOL simulation software

Abstract

The invention discloses a method for simulating direct synthesis of hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor based on COMSOL simulation software. The method comprises the following steps: inputting parameters of reaction kinetics; establishing a free fluid flow and porous medium flow physical field simulation model, establishing a surface chemical reaction physical field simulation model, and coupling a fluid equation with reaction kinetics; obtaining the H2 conversion rate of the reactor and the outlet concentration of hydrogen peroxide under different working conditions; the method comprises the following steps: simulating direct synthesis of hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor through COMSOL simulation software, and obtaining model information of hydrogen peroxide concentration in different time periods and different working conditions in the simulation process. According to the method, a multi-physical field coupling model integrating porous medium mass transfer, fluid dynamics and reaction kinetics is constructed in COMSOL simulation software, so that geometric parameters (pipe diameter and length), operation conditions (flow velocity and reaction temperature) and a global influence mechanism of solvent characteristics can be disclosed.

Description

Technical Field

[0001] This application relates to the technical field of hydrogen peroxide synthesis, and specifically relates to a method for directly synthesizing hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor simulated by COMSOL simulation software. Background Art

[0002] As a green oxidant, hydrogen peroxide (H2O2) is widely used in fields such as wastewater treatment and chemical synthesis, and the global demand continues to grow. However, currently 95% of H2O2 production relies on the traditional anthraquinone process, which has problems such as cumbersome steps, high energy consumption, and pollution by toxic solvents. The direct synthesis of hydrogen peroxide (DSHP) technology directly converts H2 and O2 into H2O2 through a catalytic reaction, with advantages such as a simple process and high safety, becoming a very promising alternative path.

[0003] The industrialization of DSHP still faces core challenges: the explosion risk of the H2 / O2 mixed gas (explosion limit 4%-94%), and the problem of the coordinated optimization of mass transfer efficiency and process parameters in the reactor. Although microchannel reactors suppress explosions through submillimeter structures, they are limited by the gas-liquid mass transfer bottleneck; porous membrane reactors achieve safe reactions by physically isolating the H2 / O2 gas flows, but it is difficult to precisely control gas permeation and catalyst structure. Existing research mostly relies on the experimental trial-and-error method, lacking a systematic quantitative analysis of multiphase transport mechanisms and reaction kinetics. Traditional CFD models overly simplify the heterogeneous adsorption process in porous media, resulting in insufficient prediction accuracy and being difficult to guide the design of reactor structures and the optimization of process parameters. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for simulating the direct synthesis of hydrogen peroxide in a porous membrane reactor based on COMSOL simulation software to at least solve one of the above technical problems.

[0005] One aspect of the present invention provides a method for simulating the direct synthesis of hydrogen peroxide in a porous membrane reactor based on COMSOL simulation software, which is used to study the kinetic process of the direct synthesis of hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor by a Pd-based catalyst. The method for simulating the direct synthesis of hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor based on COMSOL simulation software includes:

[0006] Inputting the parameters of reaction kinetics into the COMSOL simulation software;

[0007] Establishing a physical field simulation model of free fluid flow and porous medium flow and a physical field simulation model of surface chemical reaction in the COMSOL simulation software;

[0008] Coupling the control equations with the reaction kinetics in the COMSOL simulation software;

[0009] Obtain the H2 conversion rate of the reactor and the outlet concentration of hydrogen peroxide under different working conditions in the COMSOL simulation software;

[0010] According to the parameters of the reaction kinetics, couple the physical field simulation models of free fluid flow and porous media flow, obtain the physical field simulation model of surface chemical reaction, the control equations, the H2 conversion rate of the reactor under different working conditions, and the outlet concentration of hydrogen peroxide. Simulate the direct synthesis of hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor in the COMSOL simulation software and obtain the model information of the hydrogen peroxide concentration at different times and under different working conditions during the simulation process.

[0011] Optionally, the input of the reaction kinetics parameters in the COMSOL simulation software includes:

[0012] Obtain the reaction kinetics data in the experiment of direct synthesis of hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor under the condition that the catalyst is Pd / Al2O3; among them, the reaction kinetics data includes the pre-exponential factor, activation energy, reaction rate constant, and reaction rate expression.

[0013] Optionally, the establishment of the physical field simulation models of free fluid flow and porous media flow and the establishment of the physical field simulation model of surface chemical reaction in the COMSOL simulation software include:

[0014] Obtain the material properties of the catalytic channel and the internal fluid in the simulation state according to the material properties of the catalytic channel and the internal fluid in the direct synthesis of hydrogen peroxide from hydrogen and oxygen under the actual state;

[0015] According to the reactor channel and the catalytic layer of the direct synthesis of hydrogen peroxide from hydrogen and oxygen under the actual state, construct a two-dimensional axisymmetric structural model of the catalytic channel in the simulation state, and then apply the material properties to the two-dimensional structural model of the catalytic channel to construct the physical field simulation model of free fluid flow and porous media reaction flow.

[0016] Optionally, the control equations include the Navier-Stokes equation, the Brinkman equation, the convective diffusion equation, and the reaction kinetics equation of the power function type.

[0017] Optionally, the calculation domain of the coupled physical field simulation model of free fluid flow and porous media flow only includes the fine pore catalytic layer and the free fluid domain.

[0018] Optionally, the obtaining of the control equations in the COMSOL simulation software and the coupling with the parameters of the reaction kinetics include:

[0019] Couple the physical field simulation model of free fluid flow and porous media flow with the Brinkman equation in the COMSOL simulation software;

[0020] Add the parameters of reaction kinetics into the surface chemical reaction physical field simulation model in the COMSOL simulation software; among them, add the methanol parameters in the COMSOL simulation software, and set the type as solvent; set the mixture property type as dilute substance; in the substance matching, solve the substance coupling the dilute substance transfer in the porous medium;

[0021] Set the diffusion coefficient of the substances inside the fluid domain of each reactor in the methanol solvent in the COMSOL simulation software;

[0022] Set the effective diffusion coefficient of the substances inside the fine pore catalyst layer in the COMSOL simulation software.

[0023] Optionally, obtaining the H2 conversion rate of the reactor and the outlet concentration of hydrogen peroxide under different working conditions in the COMSOL simulation software includes:

[0024] Set the initial conditions and boundary conditions of the reaction in the simulation state;

[0025] Perform mesh generation on the free fluid flow and porous medium flow physical field simulation model;

[0026] Solve the control equations through the COMSOL simulation software to obtain the H2 conversion rate of the reactor and the outlet concentration of hydrogen peroxide under different working conditions.

[0027] Optionally, based on the parameters of the reaction kinetics, coupling the free fluid flow and porous medium flow physical field simulation model, obtaining the surface chemical reaction physical field simulation model, control equations, the H2 conversion rate of the reactor under different working conditions, and the outlet concentration of hydrogen peroxide, simulating the direct synthesis of hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor in the COMSOL simulation software and obtaining the model information of the hydrogen peroxide concentration at different times and under different working conditions during the simulation process includes:

[0028] Use the transient solver in the COMSOL simulation software, set the time step for solution, and obtain the substance distribution in the catalytic channel at different reaction times and the reaction situation of the direct synthesis of hydrogen peroxide from hydrogen and oxygen.

[0029] In this application, by constructing a multi-physics field coupling model integrating porous medium mass transfer, fluid dynamics, and reaction kinetics in the COMSOL simulation software, the global influence mechanisms of geometric parameters (pipe diameter, length), operating conditions (flow rate, reaction temperature), and solvent characteristics can be revealed. Such refined simulations can not only avoid experimental safety risks but also provide theoretical support for catalyst distribution optimization and mass transfer enhancement strategies, accelerating the engineering process of the DSHP technology. Description of the Drawings

[0030] Figure 1It is a schematic flow chart of a method for directly synthesizing hydrogen peroxide in a porous membrane reactor simulated by COMSOL simulation software according to an embodiment of the present application.

[0031] Figure 2 It is a schematic structural diagram of a porous membrane reactor according to an embodiment of the present invention;

[0032] Figure 3 It is a physical field simulation model coupling free fluid flow and porous medium flow according to an embodiment of the present invention; wherein, (a) is a view of a two-dimensional model, and (b) is a model mesh division diagram;

[0033] Figure 4 It is the hydrogen peroxide concentration distribution at different time points according to an embodiment of the present invention;

[0034] Figure 5 It is a comparison chart of the hydrogen peroxide outlet concentration of the model of the present application, experimental data, and other model simulation data according to an embodiment of the present invention. Detailed implementation manners

[0035] To make the purpose, technical solutions, and advantages of the implementation of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, of the embodiments of the present application. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application and should not be construed as limiting the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application. The embodiments of the present application will be described in detail below with reference to the drawings.

[0036] As Figure 1 shown, a method for directly synthesizing hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor simulated by COMSOL simulation software:

[0037] Step 1: Input the parameters of reaction kinetics in the COMSOL simulation software;

[0038] Step 2: Establish a physical field simulation model of free fluid flow and porous medium flow and a physical field simulation model of surface chemical reaction in the COMSOL simulation software;

[0039] Step 3: Couple the control equations with the reaction kinetics in the COMSOL simulation software;

[0040] Step 4: Obtain the H2 conversion rate and the hydrogen peroxide outlet concentration of the reactor under different working conditions in the COMSOL simulation software;

[0041] Step 5: According to the parameters of the reaction kinetics, the physical field simulation model coupling free fluid flow and porous medium flow, obtain the physical field simulation model of surface chemical reaction, the governing equations, the H2 conversion rate of the reactor under different working conditions, and the outlet concentration of hydrogen peroxide, and simulate the direct synthesis of hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor using COMSOL simulation software, and obtain the model information of the hydrogen peroxide concentration at different times and different working conditions during the simulation process.

[0042] By constructing a multi-physics coupling model integrating porous medium mass transfer, fluid dynamics, and reaction kinetics in COMSOL simulation software, this application can reveal the global influence mechanisms of geometric parameters (pipe diameter, length), operating conditions (flow rate, reaction temperature), and solvent properties. Such refined simulations can not only avoid experimental safety risks but also provide theoretical support for catalyst distribution optimization and mass transfer enhancement strategies, accelerating the engineering process of the DSHP technology.

[0043] In this embodiment, the parameters of the reaction kinetics input into the COMSOL simulation software include:

[0044] Obtain the reaction kinetics data in the experiment of directly synthesizing hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor under the condition that the catalyst is Pd / Al2O3; among them, the reaction kinetics data include the pre-exponential factor, activation energy, reaction rate constant, and reaction rate expression.

[0045] In this embodiment, establishing the physical field simulation model of free fluid flow and porous medium flow and establishing the physical field simulation model of surface chemical reaction in the COMSOL simulation software include:

[0046] Obtain the material properties of the catalytic channel and the internal fluid in the simulation state according to the material properties of the catalytic channel and the internal fluid for the direct synthesis of hydrogen peroxide from hydrogen and oxygen under the actual state.

[0047] According to the reactor channel and the catalytic layer for the direct synthesis of hydrogen peroxide from hydrogen and oxygen under the actual state, construct a two-dimensional axisymmetric structural model of the catalytic channel in the simulation state, and then apply the material properties to the two-dimensional structural model of the catalytic channel to construct the physical field simulation model of free fluid flow and porous medium reaction flow.

[0048] In this embodiment, the governing equations include the Navier-Stokes equation, the Brinkman equation, the convective diffusion equation, and the reaction kinetics equation of the power function type.

[0049] In this embodiment, the computational domain of the physical field simulation model coupling free fluid flow and porous medium flow only includes the microporous catalytic layer and the free fluid domain.

[0050] In this embodiment, obtaining the governing equations in the COMSOL simulation software and coupling them with the parameters of reaction kinetics includes:

[0051] Coupling the physical field simulation model of free fluid flow and porous medium flow with the Brinkman equation in the COMSOL simulation software;

[0052] Adding the parameters of reaction kinetics into the physical field simulation model of surface chemical reaction in the COMSOL simulation software; wherein, adding methanol parameters in the COMSOL simulation software, with the type set as solvent; the mixture property type is set as dilute substance; the substances solved in the substance matching couple the dilute substance transfer in the porous medium;

[0053] Setting the diffusion coefficient of the substances inside the fluid domain of each reactor in the methanol solvent in the COMSOL simulation software;

[0054] Setting the effective diffusion coefficient of the substances inside the fine pore catalyst layer in the COMSOL simulation software.

[0055] In this embodiment, obtaining the H2 conversion rate of the reactor and the outlet concentration of hydrogen peroxide under different working conditions in the COMSOL simulation software includes:

[0056] Setting the initial conditions and boundary conditions of the reaction in the simulation state;

[0057] Performing mesh generation on the physical field simulation model of free fluid flow and porous medium flow;

[0058] Obtaining the H2 conversion rate of the reactor and the outlet concentration of hydrogen peroxide under different working conditions through the governing equations.

[0059] In this embodiment, based on the parameters of the reaction kinetics, coupling the physical field simulation model of free fluid flow and porous medium flow, obtaining the physical field simulation model of surface chemical reaction, the governing equations, the H2 conversion rate of the reactor under different working conditions, and the outlet concentration of hydrogen peroxide, simulating the direct synthesis of hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor in the COMSOL simulation software and obtaining the model information of the hydrogen peroxide concentration at different times and under different working conditions during the simulation process includes:

[0060] Using the transient solver in the COMSOL simulation software, setting the time step for solution, and obtaining the substance distribution situation at different reaction times in the catalytic channel and the reaction situation of the direct synthesis of hydrogen peroxide from hydrogen and oxygen.

[0061] The following further elaborates on this application by way of examples. It can be understood that these examples do not constitute any limitation to this application.

[0062] Step 1: Input the parameters of reaction kinetics into the COMSOL simulation software.

[0063] In this embodiment, the kinetic parameters are the corresponding reaction kinetic data of the catalyst (Pd / Al2O3) obtained from previous experiments, and the reaction kinetic parameters are verified through the zero-dimensional reaction engineering module of the COMSOL simulation software.

[0064] The kinetic parameters include the pre-exponential factor, activation energy, reaction rate constant, and reaction rate expression (including the pre-exponential factors and activation energies of the forward and reverse reactions and the reaction equilibrium constants of each parallel reaction). Among them, the reaction rate uses a power function type expression. In this embodiment, during the reaction process of directly synthesizing hydrogen peroxide, the parallel reactions are R1 - R4, and the reaction expressions of R1 - R4 are shown in Table 1.

[0065] The parameters of the reaction model corresponding to the kinetic parameters in Table 1 at different temperatures are calculated through the Arrhenius equation. Table 1 Reaction kinetic parameters for directly synthesizing hydrogen peroxide

[0066]

[0067] In this embodiment, obtaining the physical field simulation model of coupling free fluid flow and porous medium flow and obtaining the physical field simulation model of surface chemical reaction in the COMSOL simulation software includes:

[0068] Based on the material properties of the catalytic channel and the internal fluid for directly synthesizing hydrogen peroxide under the actual state, determine the material properties of the catalytic channel and the internal fluid under the simulation state; in this embodiment, the catalytic channel is composed of a channel wall surface and a catalytic coating attached to the channel wall surface; the material of the catalytic coating is a Pd metal porous catalyst, the H2-saturated solvent is transported into the reactor from the inside of the tube, O2 enters the reactor from the outside of the tube, the gas-liquid interface is established on the outer side of the catalyst, and the reaction occurs in the porous catalyst region.

[0069] The internal fluid includes the solvent of hydrogen peroxide, H2, O2, and reaction products.

[0070] Specifically, the material properties include: the length of the reactor pipeline is 100 mm, and the pipe diameter is 7 mm. The thickness of the microporous catalytic layer is 0.04 mm. Among them Figure 3 (a) is the view of the two-dimensional model. Figure 3 In (b) is the model mesh division diagram.

[0071] In this embodiment, the material of the microporous catalytic layer is (Pd / Al2O3), and the internal fluid includes a solvent, reactants, and reaction products; the solvent is methanol, the reactants are O2 and H2, and the reaction products are water and hydrogen peroxide. Parameters related to the material type or fluid type are all called from the material library in the software according to the above substance types. The material property parameters of the catalytic coating are listed in Table 2. Without special instructions, the remaining relevant parameters all adopt the default values in the software.

[0072] Table 2 Material Properties of the Microporous Catalytic Layer

[0073] Name Property Material type <![CDATA[Pd / Al2O3]]> Particle size 500nm Porosity 0.3 Tortuosity 3

[0074] In this embodiment, a spatial correlation model of the reaction engineering is established, where the computational domain only includes: the microporous catalytic layer and the free fluid domain. Based on the actual state, the reactor channel and the catalytic layer for directly synthesizing hydrogen peroxide are constructed, and a two-dimensional axisymmetric structural model of the catalytic channel in the simulated state is built. Then, the material properties are applied to the two-dimensional structural model of the catalytic channel to construct a physical field (i.e., a coupled free fluid flow and porous medium fluid flow physical field simulation model).

[0075] In this embodiment, obtaining the control equations in the COMSOL simulation software and coupling them with the parameters of the reaction kinetics includes:

[0076] The physical field includes single physical fields and multi-physical fields. The interface of the single physical field is chemistry (i.e., the surface chemical reaction physical field simulation model); the multi-physical field interface is the coupling of chemical reaction and the Brinkman equation (the dilute mass transfer in the porous medium is used as the mass transfer interface, and the Brinkman equation interface is used as the fluid flow interface, and the above two interfaces are coupled).

[0077] In this embodiment, the kinetic parameters of the four parallel reactions R1 - R4 are added to the chemical interface component, the solvent is added as methanol, and the type is set as solvent; the mixture property type is set as dilute substance; the substances to be solved in the substance matching are coupled with the dilute mass transfer in the porous medium.

[0078] In this embodiment, the effective diffusion coefficients of the substances inside the fluid domain of the reactor are approximately calculated using the Wilke-Chang equation. The diffusion coefficients of each substance after the approximate calculation are shown in Table 3. It is assumed that the gas flow is stable, laminar, and incompressible. Since in the entire reaction system, the influence of the reaction itself on the system temperature is very small, it is assumed that the system is at a constant temperature.

[0079] Table 3 Diffusion Coefficients of Each Substance in Methanol Solvent

[0080] Name Value <![CDATA[Diffusion coefficient of H2 in methanol solvent]]> <![CDATA[4.3(10 -9 m 2 s -1 )]]> <![CDATA[Diffusion coefficient of O2 in methanol solvent]]> <![CDATA[4.2(10 -9 m 2 s -1 )]]> <![CDATA[Diffusion coefficient of H2O in methanol solvent]]> <![CDATA[2.1(10 -9 m 2 s -1 )]]> <![CDATA[Diffusion coefficient of H2O2 in methanol solvent]]> <![CDATA[4.5(10 -9 m 2 s -1 )]]>

[0081] In this embodiment, the effective diffusion coefficient of substances inside the microporous catalytic layer is approximately calculated using the following empirical equation

[0082]

[0083] where τ is the tortuosity of the microporous catalytic layer and ε is the porosity.

[0084] In this embodiment, after the components are set up, the governing equations are calculated by the built-in equations in the COMSOL simulation software for the calculation model.

[0085] In this embodiment, according to the reaction conditions for directly synthesizing hydrogen peroxide under actual conditions, the initial conditions and boundary conditions for the reaction in the simulation state are determined, and the two-dimensional structure model is meshed. The governing equations are solved to obtain the H2 conversion rate and the outlet concentration of hydrogen peroxide in the reactor under different operating conditions.

[0086] The boundary conditions and initial conditions include: the inlet concentration of H2 and the flow rate of the methanol solvent. Among them, the flow rate of methanol is fully developed and the flow rate is set to 2.5 mL / min. The inlet concentrations of H2 and O2 are calculated using Henry's law to obtain the inlet concentration of the reactor. Table 4 shows the Henry's constants of the gases at 298K. The no-slip boundary condition is applied to the entire channel wall, and the symmetry boundary condition is applied to the axis of symmetry.

[0087] Table 4 Henry's constants of gases at 298K

[0088]

[0089] In this embodiment, the governing equations are discretized using quadrilateral meshes, and the two-dimensional structure of the reaction channel is meshed. Since the reaction in the reactor occurs in the microporous catalytic layer and O2 enters the reactor through the outside of the reactor. Therefore, the mesh is refined between the free fluid domain and the microporous catalytic layer. This provides higher precision for the simulation and solution of the gas reaction in the inlet section. The specific mesh division is as shown in Figure 3 (b). During the entire simulation calculation process, a mesh sequence of 50,000 quadrilateral mesh elements provides reasonable calculation accuracy.

[0090] In this embodiment, based on the parameters of the reaction kinetics, coupling the physical field simulation models of free fluid flow and porous medium flow, obtaining the physical field simulation model of surface chemical reaction, the governing equations, the H2 conversion rate of the reactor under different operating conditions, and the outlet concentration of hydrogen peroxide, the simulation of directly synthesizing hydrogen peroxide in the porous membrane reactor using the COMSOL simulation software and obtaining the model information of the hydrogen peroxide concentration at different time periods during the simulation process includes:

[0091] The transient solver in the simulation software is used to solve the governing equations, and the time step is set for the solution to obtain the substance distribution in the catalytic channel at different reaction times, and the reaction of directly synthesizing hydrogen peroxide is analyzed. The output step is set to 20 seconds per step, and the situation of synthesizing hydrogen peroxide in the catalytic channel when the reaction lasts for 600 seconds is analyzed. Specifically, the model of hydrogen peroxide concentration at different time periods based on the COMSOL simulation software is shown as Figure 4 (a, b, c). The hydrogen peroxide concentration distributions at three time nodes of reaction time t = 200 s, 400 s, and 600 s are intercepted and analyzed. Among them, the hydrogen peroxide concentration distribution is close to the steady state at t = 400 s. Therefore, the steady-state solver can also be used for the calculations of other examples, and the relative tolerance is set to 0.001.

[0092] From Figure 5 it can be clearly seen that a rapid reaction occurs after H2 enters through the inlet at the beginning, and hydrogen peroxide is rapidly generated. In the experiment, the membrane reactor was directly synthesized using Pd / TiO2 (m Pd = 6.9 mg), and the tube was filled with inert glass beads with a diameter of 0.5 mm. The operating conditions are as follows: PO2 = 54 bar, P Saturator = 50 bar, and the ratio of H2 to N2 is 30 / 70. As Figure 5 shown, within the liquid flow rate range of 2.5 - 40 mL / min, the model accurately reproduces the experimental trend.

[0093] By combining the computational fluid dynamics model with experimental verification, this application avoids the explosion risk of the H2 and N2 mixture while significantly improving the problem of insufficient mass transfer efficiency; the proposed parameter optimization scheme can provide guidance for the efficient and safe operation of industrial reactors and provide a quantitative basis for the structural design of microreactors, greatly reducing the experimental development cost.

[0094] The method provided in this application can reduce some orthogonal experiments and condition explorations, reduce time and experimental costs, enable researchers to clearly observe the reaction situation in the reaction area of directly synthesizing hydrogen peroxide, evaluate the reaction performance and structural rationality of the catalyst through information such as the concentration distribution of reaction substances, and make it more convenient for researchers to analyze the process of directly synthesizing hydrogen peroxide, providing strong guidance for modifying experimental conditions or optimizing the structure of the catalyst in the next stage.

[0095] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of the present invention claimed.

Claims

1. A method for directly synthesizing hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor by simulation using COMSOL simulation software, characterized in that, The method for directly synthesizing hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor by simulation using COMSOL simulation software: Input the parameters of reaction kinetics into the COMSOL simulation software; Establish a physical field simulation model of free fluid flow and porous medium flow and a physical field simulation model of surface chemical reaction in the COMSOL simulation software; Couple the control equations with the reaction kinetics in the COMSOL simulation software; Obtain the H2 conversion rate of the reactor and the outlet concentration of hydrogen peroxide under different working conditions in the COMSOL simulation software; Based on the parameters of the reaction kinetics, the coupled physical field simulation model of free fluid flow and porous medium flow, the obtained physical field simulation model of surface chemical reaction, the control equations, the H2 conversion rate of the reactor under different working conditions, and the outlet concentration of hydrogen peroxide, simulate the direct synthesis of hydrogen peroxide from hydrogen and oxygen in the porous membrane reactor in the COMSOL simulation software and obtain the model information of the hydrogen peroxide concentration at different times and under different working conditions during the simulation process.

2. The method for directly synthesizing hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor by simulation using COMSOL simulation software according to claim 1, wherein, The input of the parameters of reaction kinetics into the COMSOL simulation software includes: Obtain the reaction kinetics data in the experiment of directly synthesizing hydrogen peroxide from hydrogen and oxygen in the porous membrane reactor under the condition that the catalyst is Pd / Al2O3; among them, the reaction kinetics data includes the pre-exponential factor, activation energy, reaction rate constant, and reaction rate expression.

3. The method for directly synthesizing hydrogen peroxide by hydrogen and oxygen in a porous membrane reactor based on COMSOL simulation software according to claim 2, characterized in that, The establishment of the physical field simulation model of free fluid flow and porous medium flow and the physical field simulation model of surface chemical reaction in the COMSOL simulation software includes: Obtain the material properties of the catalytic channel and the internal fluid in the simulation state according to the material properties of the catalytic channel and the internal fluid for the direct synthesis of hydrogen peroxide from hydrogen and oxygen in the actual state; According to the reactor channel and catalytic layer for the direct synthesis of hydrogen peroxide from hydrogen and oxygen in the actual state, construct a two-dimensional axisymmetric structural model of the catalytic channel in the simulation state, and then apply the material properties to the two-dimensional structural model of the catalytic channel to construct a physical field simulation model of free fluid flow and porous medium reaction flow.

4. The method for directly synthesizing hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor simulated by COMSOL simulation software according to claim 3, characterized in that, The control equations include the Navier-Stokes equation, Brinkman equation, convective diffusion equation, and power function type reaction kinetics equation.

5. The method for directly synthesizing hydrogen peroxide by hydrogen and oxygen in a porous membrane reactor simulated by COMSOL simulation software according to claim 4, wherein, The calculation domain of the coupled physical field simulation model of free fluid flow and porous medium flow only includes the fine pore catalytic layer and the free fluid domain.

6. The method for directly synthesizing hydrogen peroxide by hydrogen and oxygen in a porous membrane reactor based on COMSOL simulation software according to claim 5, wherein, The obtaining of the control equations in the COMSOL simulation software and the coupling with the parameters of reaction kinetics includes: Couple the physical field simulation model of free fluid flow and porous medium flow with the Brinkman equation in the COMSOL simulation software; Add the parameters of reaction kinetics into the physical field simulation model of surface chemical reaction in the COMSOL simulation software; among them, add methanol parameters in the COMSOL simulation software, the type is set as solvent; the mixture property type is set as dilute substance; in the substance matching, the substances to be solved are coupled with the dilute substance transfer in the porous medium; Set the diffusion coefficient of the substances inside the fluid domain of each reactor in the methanol solvent in the COMSOL simulation software; Set the effective diffusion coefficient of the substances inside the fine pore catalytic layer in the COMSOL simulation software.

7. The method for directly synthesizing hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor by simulation with COMSOL simulation software according to claim 6, characterized in that, Obtaining the H2 conversion rate of the reactor and the outlet concentration of hydrogen peroxide under different working conditions in the COMSOL simulation software includes: Setting the initial conditions and boundary conditions of the reaction in the simulation state; Performing mesh division on the physical field simulation model of free fluid flow and porous medium flow; Solving the control equations through the COMSOL simulation software to obtain the H2 conversion rate of the reactor and the outlet concentration of hydrogen peroxide under different working conditions.

8. The method for directly synthesizing hydrogen peroxide from hydrogen and oxygen in a porous membrane reactor simulated by COMSOL simulation software according to claim 7, characterized in that, According to the parameters of the reaction kinetics, coupling the physical field simulation model of free fluid flow and porous medium flow, obtaining the physical field simulation model of surface chemical reaction, the control equations, the H2 conversion rate of the reactor under different working conditions, and the outlet concentration of hydrogen peroxide, the model information of the hydrogen peroxide concentration at different times and different working conditions during the simulation of the direct synthesis of hydrogen peroxide from hydrogen and oxygen in the porous membrane reactor in the COMSOL simulation software includes: Using the transient solver in the COMSOL simulation software, setting the time step for solution, and obtaining the substance distribution in the catalytic channel at different reaction times and the reaction situation of the direct synthesis of hydrogen peroxide from hydrogen and oxygen.

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