Granular catalyst and preparation method thereof

Abstract

The invention discloses a granular catalyst and a preparation method thereof, and belongs to the technical field of chemical engineering. The preparation method of the granular catalyst comprises the following steps: S1, mixing raw materials containing a carbon material, an active metal material and a solvent to form slurry; s2, the slurry serves as a cathode in an electrode system and is subjected to pulse electrodeposition treatment, and active metal is deposited on the surface of a carbon material to form a particle catalyst; the electrode system is a two-electrode system; an anode in the two-electrode system comprises a dimensionally stable electrode, and an anode electrolyte is a sulfuric acid solution; and the two electrode systems are electrode systems in a flow battery stack structure. According to the preparation method, a flowing slurry and pulse electrodeposition combined method is adopted, so that metal particles are uniformly and stably loaded on a carbon material carrier, and gt is obtained within one-time preparation time of 1h; according to the method, laboratory-scale continuous synthesis of the granular catalyst is realized, and the method is simple in preparation process, mild in reaction condition and high in controllability.

Description

Technical Field

[0001] This application belongs to the field of chemical technology, and in particular relates to a particulate catalyst and its preparation method. Background Technology

[0002] With the rapid development of nanoscience, a new era of catalysis research—nanocatalysis—has been introduced and propelled. Studies have shown that catalyst performance can be determined by the size of the catalytic metal particles. By controlling the nucleation and growth processes at the nanoscale, nanoparticles with high surface-to-volume ratios can be obtained. Furthermore, the abundant coordinated unsaturated surface atoms at the edges, corners, and hierarchical levels of nanoparticles, as well as their specific morphology, significantly influence the adsorption, desorption, and activation processes of small-molecule reactants, thereby effectively regulating catalytic efficiency. To achieve higher atom utilization efficiency, the particle size of active metals is continuously shrinking from the nanoscale to the sub-nanometer and even atomic scale. With significant improvements in catalyst preparation technology, active metals can be dispersed on supports in the form of single atoms, nanoclusters (<2 nm), and nanoparticles (2-20 nm). Catalysts at different particle sizes have been shown to exhibit excellent activity in different reactions. Traditional synthesis methods for heterogeneous particulate catalysts include impregnation and high-temperature pyrolysis. These chemical methods are generally poorly controlled, and due to the high surface energy of metals, particle agglomeration is prone to occur, resulting in complex structures with wide particle size and compositional distributions in heterogeneous catalysts. The complexity of this structure significantly hinders the understanding of the structure-activity relationship and impedes progress in optimizing catalytic performance. Achieving high selectivity in the 21st century—the selective conversion of reaction substrates into specific products with minimal side reactions—remains highly desirable but challenging for many processes. Therefore, there is an urgent need to develop a precise catalyst synthesis method to improve the homogeneity of catalyst structures, thereby facilitating an atomic-level understanding of the structure-activity relationship and achieving high selectivity.

[0003] In recent years, with the rapid development of electrodeposition methods and the continuous exploration of their reaction mechanisms, electrodeposition has become a promising technology for the synthesis of particulate catalysts. Compared with traditional techniques such as ball milling and pyrolysis, electrochemical deposition can be carried out at room temperature and pressure, with mild reaction conditions and no need for complex post-treatment such as oxidants or reducing agents. Chinese patent ZL031177786 uses overpotential direct electrodeposition to selectively deposit Pt catalysts onto a support that is in direct contact with the proton exchange membrane and has electron and ion transport channels, achieving efficient utilization of the catalyst support. However, prolonged direct overpotential deposition leads to the continuous growth of metal particles, inevitably resulting in severe particle agglomeration. Compared with conventional overpotential deposition technology, Chinese patent 200810069271.7 discloses a two-step pulse electrodeposition method, which first deposits a transition metal onto a porous carbon electrode, and then forms a platinum monolayer on the porous carbon surface through a substitution reaction. This pulse method can solve the problem of coarse grains to some extent, but it does not take into account the influence of double-layer capacitance, which makes it difficult to control the effective contribution of transient current in pulse electrodeposition. This still leads to problems such as excessively large transition metal and platinum grains and difficulty in controlling their size.

[0004] On the other hand, conventional electrodeposition processes are currently performed on fixed electrodes, where the metal can only be anchored at the interface in contact with the electrolyte. This results in a limited number of atoms deposited on the electrode, hindering large-scale production. Furthermore, this method is limited by thermodynamic conditions, allowing metal deposition only within a very narrow electrochemical window, inevitably leading to drawbacks such as slow deposition rates, low production efficiency, and unsuitability for complex multiphase supports. In addition, during long-term electrochemical deposition, problems such as particle agglomeration, electrode poisoning, powder desorption, and depletion of precursors within the diffusion layer can occur on the fixed electrode surface—problems commonly encountered in electrochemical catalytic reactions. The aforementioned electrodeposition process, performed on fixed electrodes, results in a limited number of atoms deposited on the electrode, hindering large-scale production. It also presents challenges such as high energy consumption during nanoparticle catalyst preparation, easy particle aggregation, and the difficulty of mass production using most current fixed reactors. Summary of the Invention

[0005] In view of this, this application provides a particulate catalyst and its preparation method, the main purpose of which is to solve the technical problems of easy agglomeration of catalyst particles and low deposition of active atoms.

[0006] On the one hand, this application provides a method for preparing a particulate catalyst, the method comprising the following steps:

[0007] S1: Mix raw materials containing carbon materials, active metal materials and solvents to form a slurry;

[0008] S2: The slurry is used as the cathode of the flow reaction system. After the slurry is treated by pulse electrodeposition, the active metal in the slurry is deposited on the surface of the carbon material to form the particulate catalyst.

[0009] Optionally, in step S2, the flow reaction system includes a flow battery stack reaction system, wherein the anode includes a shape-stabilized electrode and the anode electrolyte is a sulfuric acid solution.

[0010] Optionally, in step S2, the pulse electrodeposition includes an electrodeposition process and an electrodeposition process;

[0011] During the electrodeposition process, the deposition voltage is -0.5 to -4V, and the deposition time is 0.1 to 10s.

[0012] During the electrodeposition process, the deposition voltage is 0–2V and the deposition time is 0.1–10s;

[0013] Deposition / precipitation time ratio t on / t off The range is 1 to 100, and the temperature is 25 to 35℃.

[0014] The total time for pulse electrodeposition is 300–7200 s.

[0015] Optionally, the deposition voltage is -1.5 to -3V, and the precipitation voltage is 0.5 to 2V;

[0016] The electrodeposition process and the electrodeposition process also include a buffer process with a voltage of 0V, which is maintained for 0.001 to 1 second.

[0017] Optionally, the deposition voltage is selected from any value or a range between any two of -0.5, -0.6, -0.7, -0.8, -0.9, -1.0, -1.1, -1.2, -1.3, -1.4, -1.5, -1.6, -1.7, -1.8, -1.9, -2.0, -2.1, -2.2, -2.3, -2.4, -2.5, -2.6, -2.7, -2.8, -2.9, -3.0, -3.1, -3.2, -3.3, -3.4, -3.5, -3.6, -3.7, -3.8, -3.9, and -4.0, in units of V.

[0018] Optionally, the deposition time is selected from any value or a range between any two of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.2, 3.5, 3.8, 4.0, 4.2, 4.5, 4.8, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, and 10, in seconds.

[0019] Optionally, the derived voltage is selected from any value or a range between any two of 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0, in units of V.

[0020] Optionally, the precipitation time is selected from any value or a range between any two of the following: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.2, 3.5, 3.8, 4.0, 4.2, 4.5, 4.8, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, and 10, in seconds.

[0021] Optionally, the deposition / precipitation time ratio t on / t off Select any value from 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 or a range between any two.

[0022] Optionally, the total time of the pulse electrodeposition is any value or a range between any two of 300, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, and 7200, in seconds.

[0023] Optionally, in step S1, the mass fraction of the carbon material in the slurry is 0.1 wt% to 50 wt%.

[0024] Optionally, the mass fraction of the carbon material in the slurry is selected from any value or a range between any two of 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, and 50, in wt%.

[0025] Optionally, in step S1, the mass ratio of the carbon material, the active metal material, and the solvent is (1-5):(0.1-0.5):(20-100).

[0026] Optionally, in step S1, the carbon material is selected from at least one of graphene, carbon nanotubes, porous carbon, and conductive carbon black.

[0027] Optionally, in step S1, the active metal material is selected from at least one of copper sulfate, chloroplatinic acid, silver nitrate, nickel nitrate, and cobalt acetate; preferably, the active metal material is a powder.

[0028] Optionally, the solvent is selected from sulfuric acid.

[0029] Optionally, the molar concentration of the sulfuric acid is 0.1 to 2 mol / L.

[0030] Optionally, in step S1, the carbon material is nitrogen-modified or oxygen-modified before being mixed into a slurry to form active metal anchoring points on the surface of the carbon material.

[0031] Optionally, the process of nitrogen modification of the carbon material includes: mixing aniline precursor, carbon material and sulfuric acid solvent into a slurry electrolyte, and growing polyaniline on the surface of the carbon material using cyclic voltammetry in a three-electrode system to form a polyaniline / carbon composite material;

[0032] Optionally, the potential window for the cyclic voltammetry test is set to -3V to 3V, the scan rate is 2 to 100mV / s, the cycle is 5 to 100 cycles, and after the reaction is completed, the polyaniline / carbon composite material is obtained by filtration and washing.

[0033] Optionally, the process of nitrogen- or oxygen-modifying the carbon material is carried out in the electrochemical reaction of the anode or cathode system in the flow battery stack.

[0034] Secondly, this application provides a particulate catalyst, which is prepared by the above-described preparation method.

[0035] Optionally, the active metal atoms supported in the particulate catalyst account for 0.1 wt% to 10 wt% of the total mass of the catalyst; the size of the particulate catalyst is 1 to 20 nm.

[0036] Optionally, the atomic mass of the active metal supported in the particulate catalyst is any value from 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 of the total mass of the catalyst, or a range between any two, in wt%.

[0037] Optionally, the size of the particulate catalyst is selected from any value or a range between any two of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, in nm.

[0038] Thirdly, this application provides an apparatus for preparing a particulate catalyst, the apparatus comprising a flow battery stack, a slurry storage unit, a positive electrode electrolyte storage unit, and a product processing unit;

[0039] The flow battery stack comprises, in sequence, a positive electrode plate, a positive electrode current collector, a positive electrode bipolar plate, a positive electrode plate, a proton exchange membrane, a negative electrode bipolar plate, a negative electrode current collector, and a negative electrode plate.

[0040] A slurry negative electrode is included between the proton exchange membrane and the negative electrode bipolar plate;

[0041] The negative electrode of the slurry is the slurry prepared by the above method;

[0042] Optionally, the outlet of the slurry storage unit is connected to the inlet of the negative electrode bipolar plate, and the slurry negative electrode is pumped into the serpentine flow channel of the negative electrode bipolar plate by a peristaltic pump; the negative electrode electrolyte outlet of the flow battery stack is connected to the inlet of the product processing unit. The slurry storage unit and the negative electrode electrolyte flow channel of the flow battery stack are connected in series, and the slurry contains carbon materials, sulfuric acid solvent, and active metal materials.

[0043] Optionally, the outlet of the slurry storage unit is connected to the positive electrolyte inlet I of the flow battery stack. The slurry contains carbon materials and solvents. The slurry enters the positive electrode channel, and the positive electrolyte outlet I of the flow battery stack is connected to the inlet of the slurry storage unit. At this time, the slurry contains carbon materials and sulfuric acid solvent. The slurry first goes to the positive electrode system of the flow battery stack for electrolysis, causing the carbon materials to undergo nitrogen or oxygen modification. After the carbon materials are modified, the slurry returns to the slurry storage unit, and then an active metal material is added to the slurry to form the final slurry, which then enters the negative electrolyte channel. Nitrogen modification is selected by adding a nitrogen-containing precursor, while oxygen modification does not require the addition of a modification precursor. When a voltage is applied, oxygen active sites are generated on the carbon surface.

[0044] Optionally, the positive electrode plate is a stabilizing electrode; the positive electrolyte is a sulfuric acid solution.

[0045] Optionally, the outlet of the positive electrolyte storage unit is connected to the positive electrolyte inlet II of the flow battery stack, and the positive electrolyte outlet II of the flow battery stack is connected to the inlet of the positive electrolyte storage unit. After the carbon material in the slurry has undergone nitrogen or oxygen modification in the positive electrode system, the slurry returns to the slurry storage unit, and the positive electrode system then supplies a positive electrolyte, such as sulfuric acid solution, which enters the positive electrolyte flow channel. Alternatively, the slurry can directly undergo nitrogen or oxygen modification of the carbon material in the negative electrode system. After modification, the slurry flows back to the slurry storage unit, and active metal materials are added to the slurry to form a slurry, which then re-enters the negative electrolyte flow channel for pulse electrodeposition.

[0046] This application employs a flowing slurry electrode instead of a traditional fixed electrode for electrochemical deposition. A flowing reactor suitable for slurry electrodeposition is constructed, comprising two stainless steel end plates, two gold-plated copper current collectors, two graphite plates with single- or double-sided open flow channels, a shape-stabilized counter electrode, a slurry working electrode, and an ion exchange membrane. Unlike traditional homogeneous systems, in this slurry system, all components are suspended in the electrolyte. The catalyst support (conductive carbon powder) forms a conductive threshold permeation network with the electrolyte, which, together with the electrode plates, constitutes the current collector. The reactor uses a peristaltic pump to control the slurry supply flow rate and an electrochemical workstation to provide the cell voltage, enabling slurry electrodeposition in a two-electrode system.

[0047] The most important aspect of the fluidized slurry system designed in this application is the formation of an effective conductive threshold permeation network. The formation of this complex conductive network mainly involves electron transfer between conductive particles, between particles and the electrolyte, and between the solution and the electrode sheet. All of these factors must be considered during the construction of the conductive network. Among these, the electron transfer related to the solid particles is the most critical; therefore, the solid particles themselves must possess good conductivity. In this application, carbon materials with good conductivity (graphene, carbon nanotubes, porous carbon, conductive carbon black, etc.) are selected as the substrate material. Considering that the substrate material needs to have a sufficient number of metal anchoring points, the surface of the highly conductive carbon material is modified with nitrogen. The modified carbon material serves as the solid component in the fluidized slurry.

[0048] Furthermore, the slurry with solid particles as the main component in this application must exhibit good conductivity. Under the premise of ensuring normal fluid flow, the overall conductive threshold permeation network can be optimized by adjusting the content of the solid component added to the slurry. The main principle is that increasing the solid content leads to an increase in the effective number of collisions between particles during flow, thereby promoting overall electron transfer and ion transport behavior, making the deposition reaction on the particles dominant. For example, controlling the mass fraction of the solid component to 0.1wt%–50wt% ensures normal flow of the slurry system within 3 hours, and the entire flow potential deposition inevitably leads to excessive particle growth and excessively large size. To achieve precise control of metal particle size in the flow synthesis system, this method, based on the reversible redox properties of metal ions, introduces a transient pulse deposition technique involving alternating deposition and stripping. This method introduces time resolution, enabling not only transient deposition control of the nucleation / growth process, but also a series of transient stripping processes to remove large aggregated particles, breaking the thermodynamic limitations of traditional electrochemical systems, and thus achieving precise control of the atomic-scale electrochemical deposition process. By directly adding a carbon-based support to an electrolyte solution to form a slurry electrode, and using the pulse mode of an electrochemical workstation to set different pulse electrodeposition voltages, deposition voltages, deposition / deposition voltage on / off time ratios, as well as process parameters such as slurry electrode concentration and precursor concentration, a uniformly dispersed particulate catalyst with adjustable metal size and loading is ultimately prepared on the carbon-based support. The combined method of flowing slurry and pulse electrodeposition employed in this application not only enables uniform and stable loading of metal particles onto the carbon material support, but also features a simple preparation process, mild reaction conditions, and strong controllability.

[0049] In a preferred embodiment of this application, to simplify the entire synthesis process, the synthesis reaction of nitrogen-modified carbon-based materials is switched from an H-type electrolytic cell to a flow reaction apparatus, achieving a fully fluidized process from support preparation to particulate catalyst synthesis. First, the flow reaction apparatus is used as the reactor to synthesize the polyaniline / carbon black composite material under a two-electrode system. After this step, a metal precursor salt is directly added to the slurry solution, mixed thoroughly, and then a transient electrodeposition experiment is conducted to prepare the particulate catalyst.

[0050] Compared with the prior art, this application has the following beneficial effects:

[0051] (1) This application introduces time resolution through transient pulse conditions, breaking the thermodynamic limitations of traditional electrochemical systems, and finely controls the electrochemical deposition process at the atomic scale to achieve broad-spectrum preparation of catalysts with adjustable metal morphology, loading and coordination environment; the synthesis process of this application can obtain >10g of particulate catalyst in a single preparation time of 1h, wherein the active metal loading is 0.1-10wt%, the metal particle size is controlled at 1-20nm, and the metal utilization rate in the precursor solution can reach more than 60%, which is a significant improvement compared with the existing electrodeposition technology;

[0052] (2) The slurry electrodeposition flow synthesis strategy proposed in this application explores the formation mechanism of the conductive network structure under the flow field and the influence of multi-scale physicochemical changes inside the reactor on the electrochemical deposition process through rheology and fluid dynamics, so as to realize the laboratory-scale continuous synthesis of particulate catalysts and solve the problem of large-scale scale-up in traditional fixed electrode electrodeposition.

[0053] (3) This application uses the support preparation reactor and the particulate catalyst synthesis reaction device in series, which reduces the support post-processing process, realizes efficient and controllable preparation of catalyst products, and saves operating costs. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the preparation process of an embodiment of this application;

[0055] Figure 2 This is a schematic diagram of the flow battery stack structure according to an embodiment of this application;

[0056] Figure 3 The XRD patterns of Cu-based particulate catalysts obtained under different slurry solid content conditions in Example 1 of this application are shown.

[0057] Figure 4 These are XRD patterns of Pt catalysts obtained under different deposition potential conditions in Example 2 of this application;

[0058] Figure 5 This is the XRD pattern of the Cu-based particulate catalyst synthesized in full flow in Example 3 of this application. Detailed Implementation

[0059] The present application is further illustrated below with reference to specific embodiments. The following descriptions are merely a few embodiments of the present application and are not intended to limit the present application in any way. Although the present application discloses preferred embodiments as follows, they are not intended to limit the present application. Any modifications or variations made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

[0060] Unless otherwise specified, the raw materials used in the embodiments of this application are all purchased commercially and used directly without any special treatment.

[0061] This application provides an apparatus for preparing particulate catalysts, such as... Figure 2 As shown, it includes a flow battery stack, a slurry storage unit, a positive electrolyte storage unit, and a product processing unit; the flow battery stack sequentially includes a positive terminal plate, a positive current collector, a positive bipolar plate, a positive electrode plate, a proton exchange membrane, a negative bipolar plate, a negative current collector, and a negative terminal plate; a slurry negative electrode is included between the proton exchange membrane and the negative bipolar plate.

[0062] In a preferred embodiment, the outlet of the slurry storage unit is connected to the inlet of the negative electrode bipolar plate, and the negative electrode slurry is pumped into the serpentine flow channel of the negative electrode bipolar plate by a peristaltic pump; the outlet of the negative electrode electrolyte of the flow battery stack is connected to the inlet of the product processing unit. The slurry storage unit and the negative electrode electrolyte flow channel of the flow battery stack are connected in series, and the slurry contains carbon materials, sulfuric acid solvent, and active metal materials.

[0063] In a preferred embodiment, the outlet of the slurry storage unit is connected to the positive electrolyte inlet I of the flow battery stack. The slurry contains carbon materials and solvents. The slurry enters the positive electrode channel, and the positive electrolyte outlet I of the flow battery stack is connected to the inlet of the slurry storage unit. At this time, the slurry contains carbon materials and sulfuric acid solvent. The slurry first goes to the positive electrode system of the flow battery stack for electrolysis, causing the carbon materials to undergo nitrogen or oxygen modification. After the carbon materials are modified, the slurry returns to the slurry storage unit. Then, an active metal material is added to the slurry to form the final slurry, which enters the negative electrolyte channel. Nitrogen modification is selected by adding a nitrogen-containing precursor, while oxygen modification does not require the addition of a modification precursor. When a voltage is applied, oxygen active sites are generated on the carbon surface (the nitrogen modification of carbon materials in Example 3 below is carried out in this device).

[0064] As a preferred embodiment of the above, the positive electrode plate is a stabilizing electrode; the positive electrolyte is a sulfuric acid solution.

[0065] In a preferred embodiment, the outlet of the positive electrolyte storage unit is connected to the positive electrolyte inlet II of the flow battery stack, and the outlet II of the positive electrolyte of the flow battery stack is connected to the inlet of the positive electrolyte storage unit. After the carbon material in the slurry has undergone nitrogen or oxygen modification in the positive electrode system, the slurry returns to the slurry storage unit, and the positive electrode system then supplies a positive electrolyte, such as sulfuric acid solution, which enters the positive electrolyte flow channel. Alternatively, the slurry can undergo nitrogen or oxygen modification of the carbon material directly in the negative electrode system. After modification, the slurry flows back to the slurry storage unit, where active metal materials are added to form a slurry, which then re-enters the negative electrolyte flow channel for pulse electrodeposition.

[0066] The preparation process of Examples 1-3 of this application can be carried out in any of the above-mentioned devices.

[0067] Example 1: Flow Synthesis of Cu-based Particulate Catalyst

[0068] Step 1: Preparation of nitrogen-containing carbon-based support (nitrogen modification of carbon materials is carried out in a three-electrode system)

[0069] 100 μL of aniline precursor was added to 50 mL of 0.01–2 M H₂SO₄ solution to form a homogeneous solution. Then, 5 g of commercial activated carbon black material was weighed and added to the solution to form a homogeneous slurry. Using a graphite rod as the working and counter electrode, and a silver / silver chloride standard electrode as the reference electrode, a three-electrode system was used to synthesize the polyaniline / carbon black composite material in an H-type cell. Specifically, cyclic voltammetry was used to uniformly grow the polyaniline material on the carbon black surface. The potential window for the cyclic voltammetry test was set to -3 V to 3 V, the scan rate was 50 mV / s, and the cycle was 20 times. After the reaction, the obtained polyaniline / carbon black composite material was washed with deionized water and dried at 60 °C for later use.

[0070] Step 2: Preparation of carbon-based slurry electrodes

[0071] Weigh a certain mass of the polyaniline / carbon black composite material prepared in the first step and add it to 20 mL of 1 M H2SO4 solution to form a uniform slurry electrode. The mass fraction of carbon material in the slurry is x wt% (x can be any value in the range of 0.1 to 50, such as 5, 10, 15, 20). The slurry needs to be continuously stirred with a magnetic stirrer to maintain good dispersibility. The stirring speed is 300 r / min.

[0072] Step 3: Pulsed electrochemical deposition in a flowing system (performed in the above-mentioned particulate catalyst device)

[0073] Slurry electrodeposition was performed using a two-electrode system, with the carbon slurry electrode prepared in the second step as the cathode and the stabilizing electrode as the anode, and 0.1M sulfuric acid as the anolyte. Before pulse electrodeposition, 0.1M CuSO4 powder was added to the solution to form a metal precursor solution, and argon gas was simultaneously introduced into the solution to eliminate the influence of dissolved oxygen. The pulse deposition voltage was set to -3V, the applied deposition voltage time was set to 5s, the deposition potential was set to 1V, the applied deposition voltage time was set to 0.1, and the deposition / deposition time ratio t was set to... on / t off The electrodeposition ratio was 50:1, the temperature was 25℃, and the total deposition time was 4000s. The electrodeposited metal catalyst was washed sequentially with anhydrous ethanol and distilled water, and then dried with cold air. The XRD results are shown in the attached figure. Figure 3 As shown, the process flow is as follows: Figure 1 and Figure 2 As shown.

[0074] In Example 1 of this application, the main control parameter is the slurry concentration. By controlling the slurry concentration, the conductive network of the slurry is optimized, thereby improving the electron transfer and ion transport behavior in the electrochemical process and ultimately obtaining a better electrochemical deposition effect. Figure 3 The results showed that the slurry system with a solid content of 15 wt% had the best electron transfer effect, the highest metal catalyst loading (up to 4 wt%), and a metal utilization rate of 60%. The particle catalyst had a structure in which copper material was wrapped in a single-atom form on the surface of a carbon-based support.

[0075] Example 2: Flow Synthesis of Pt-based Single-Atom Catalysts

[0076] The first step is the same as the first step in Example 1 (the nitrogen modification of the carbon material is carried out in a separate three-electrode system).

[0077] Step 2: Preparation of carbon-based slurry electrodes

[0078] Weigh a certain mass of the polyaniline / carbon black composite material prepared in the first step and add it to 20 mL of 1 mm H2SO4 solution to form a uniform slurry electrode. The mass fraction of carbon material in the slurry is 15 wt%. The slurry needs to be continuously stirred with a magnetic stirrer to maintain good dispersibility. The stirring speed is 300 r / min.

[0079] Step 3: Pulsed electrochemical deposition in a flowing system (performed in a particulate catalyst preparation apparatus)

[0080] Slurry electrodeposition was performed in a two-electrode system, using the carbon slurry electrode prepared in the second step as the cathode and the stabilizing electrode as the anode, with 0.1M sulfuric acid as the anolyte. Before pulse electrodeposition, 0.01 H₂PtCl₆ powder was added to the solution to form a metal precursor solution, and argon gas was simultaneously introduced into the solution to eliminate the influence of dissolved oxygen. The pulse deposition voltage was y V (y is any value in the range of -0.5 to -4, such as -1, -1.5, -2, -2.5, -3), the applied deposition voltage time was 5 s, the deposition potential was set to 1 V, the applied deposition voltage time was 0.1 s, and the deposition / deposition time ratio t was [value missing]. on / t off The deposition ratio was 50:1, the temperature was 25℃, and the total deposition time was 4000s. The electrodeposited metal catalyst was washed sequentially with anhydrous ethanol and distilled water, and then dried with cold air. The XRD crystal structure results are shown in the attached figure. Figure 3 .

[0081] In Embodiment 2 of this application, the main control parameters are deposition voltage and precipitation voltage. Deposition voltage mainly controls the metal nucleation-growth process, while precipitation voltage is used to remove large particles. The combination of the two achieves controllability of particle size. Figure 4The results show that a deposition voltage of less than -1.5V provides sufficient electronic breakdown current and metal deposition current, and a deposition voltage of 1V can remove large bulk metal particles deposited on the carbon support. The resulting catalyst product does not show obvious particle crystal structure and belongs to single-atom morphology. The structure of the particulate catalyst is that platinum material is supported on the surface of the carbon-based support in single-atom morphology.

[0082] Example 3: Fully Flow Synthesis of Cu-Based Particulate Catalysts

[0083] Step 1: Preparation of carbon-based slurry electrodes

[0084] Preparation of carbon slurry electrode: Commercially available activated carbon black material was added to a 1M H2SO4 solution to form a uniform slurry. The mass fraction of carbon material in the slurry was 15wt%. The slurry was continuously stirred with a magnetic stirrer at a speed of 3000r / min to maintain good dispersibility.

[0085] Step 2: Flow synthesis of nitrogen-doped / oxygen-vacancy carbon-based supports (the nitrogen modification process of the carbon material is carried out in the anode unit of the above-mentioned particulate catalyst preparation device).

[0086] A two-electrode flow system is adopted. The reactor controls the slurry supply flow rate to 20 mL / min through a peristaltic pump. Oxygen vacancies are generated on the carbon surface by anodic oxidation, or other nitrogen / oxygen precursors are introduced to grow and adhere to the carbon material surface in a flowing electric field. After the reaction is completed, the product is not taken out, but is transported to the negative electrode storage tank of the slurry and continuously stirred.

[0087] Step 3: Pulsed electrochemical deposition in a flowing system (performed in a particulate catalyst device)

[0088] Slurry electrodeposition was performed in a two-electrode system, using the carbon slurry electrode prepared in the second step as the cathode and the stabilizing electrode as the anode, with 0.1M sulfuric acid as the anolyte. Before pulse electrodeposition, 0.1M CuSO4 powder was added to the solution to form a metal precursor solution, and argon gas was simultaneously introduced into the solution to eliminate the influence of dissolved oxygen. The pulse deposition voltage was -3V, and the application time was 5s. The deposition potential range was 1V, and the application time was 0.1s. The deposition / deposition time ratio tg was [not specified]. on / t off The deposition ratio was 50:1, the temperature was 25℃, and the total deposition time was 4000s. The electrodeposited metal catalyst was washed sequentially with anhydrous ethanol and distilled water, and then dried with cold air. The XRD crystal structure results are shown in the attached figure. Figure 5 .

[0089] In Example 3 of this application, both the support preparation and catalyst synthesis processes are completed through a flow reactor, which reduces the post-processing of the support, achieves efficient and controllable preparation of catalyst products, and saves operating costs. Figure 4 The results show that the catalyst product obtained by using the full flow system in Example 3 did not exhibit obvious particle crystal structure and belonged to single-atom morphology; the structure of the particle catalyst is that copper material is supported on the surface of a carbon-based support in single-atom morphology.

[0090] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a particulate catalyst, characterized in that, The preparation method includes the following steps: S1: Mix raw materials containing carbon materials, active metal materials and solvents to form a slurry; S2: The slurry is used as the cathode of the flow reaction system. After the slurry is treated by pulse electrodeposition, the active metal in the slurry is deposited on the surface of the carbon material to form the particulate catalyst.

2. The method for preparing a particulate catalyst according to claim 1, characterized in that, In step S2, the flow reaction system includes a flow battery stack reaction system, the anode of which includes a shape-stabilized electrode and the anode electrolyte is a sulfuric acid solution.

3. The method for preparing a particulate catalyst according to claim 1, characterized in that, In step S2, the pulse electrodeposition includes an electrodeposition process and an electrodeposition process; During the electrodeposition process, the deposition voltage is -0.5 to -4V, and the deposition time is 0.1 to 10s. During the electrodeposition process, the deposition voltage is 0–2V and the deposition time is 0.1–10s; Deposition / precipitation time ratio t on / t off The range is 1 to 100, and the temperature is 25 to 35℃. The total time for pulse electrodeposition is 300–7200 s.

4. The method for preparing a particulate catalyst according to claim 3, characterized in that, The deposition voltage is -1.5 to -3V, and the precipitation voltage is 0.5 to 2V; The electrodeposition process and the electrodeposition process also include a buffer process with a voltage of 0V, which is maintained for 0.001 to 1 second.

5. The method for preparing a particulate catalyst according to claim 1, characterized in that, In step S1, the carbon material in the slurry has a mass fraction of 0.1 wt% to 50 wt%. Preferably, in step S1, the mass ratio of the carbon material, the active metal material, and the solvent is (1-5):(0.1-0.5):(20-100); Preferably, in step S1, the carbon material is selected from at least one of graphene, carbon nanotubes, porous carbon, and conductive carbon black; Preferably, in step S1, the active metal material is selected from at least one of copper sulfate, chloroplatinic acid, silver nitrate, nickel nitrate, and cobalt acetate; Preferably, the active metal material is a powder; Preferably, the solvent is selected from sulfuric acid and / or deionized water; Preferably, the molar concentration of the sulfuric acid is 0.1 to 2 mol / L.

6. The method for preparing a particulate catalyst according to claim 1, characterized in that, In step S1, the carbon material is modified with nitrogen or oxygen before being mixed into a slurry to form active metal anchoring points on the surface of the carbon material. Preferably, the process of nitrogen modification of the carbon material includes: mixing aniline precursor, carbon material and sulfuric acid solvent to form a slurry electrolyte, and growing polyaniline on the surface of the carbon material using cyclic voltammetry in a three-electrode system to form a polyaniline / carbon composite material; Preferably, the potential window for the cyclic voltammetry test is set to -3V to 3V, the scan rate is 2 to 100mV / s, the cycle is 5 to 100 cycles, and after the reaction is completed, the polyaniline / carbon composite material is obtained by filtration and washing. Preferably, the process of nitrogen-modifying or oxygen-modifying the carbon material is carried out in the electrochemical reaction of the anode or cathode unit in the flow battery stack reaction system.

7. A particulate catalyst, characterized in that, The particulate catalyst is prepared by the method described in any one of claims 1 to 6; Preferably, the active metal atoms supported in the particulate catalyst account for 0.1 wt% to 10 wt% of the total mass of the catalyst; the size of the particulate catalyst is 1 to 20 nm.

8. An apparatus for preparing a particulate catalyst, characterized in that, The preparation apparatus includes a flow battery stack, a slurry storage unit, a positive electrode electrolyte storage unit, and a product processing unit; wherein, the flow battery stack sequentially includes a positive end plate, a positive current collector, a positive bipolar plate, a positive electrode plate, a proton exchange membrane, a negative bipolar plate, a negative current collector, and a negative end plate. A slurry negative electrode is included between the proton exchange membrane and the negative electrode bipolar plate; The negative electrode of the slurry is the slurry prepared by the method described in any one of claims 1 to 6.

9. The apparatus for preparing a particulate catalyst according to claim 8, characterized in that, The outlet of the slurry storage unit is connected to the inlet of the negative electrode bipolar plate, and the slurry negative electrode is pumped into the serpentine flow channel of the negative electrode bipolar plate by a peristaltic pump; the negative electrode electrolyte outlet of the flow battery stack is connected to the inlet of the product processing unit. Preferably, the outlet of the slurry storage unit is connected to the positive electrolyte inlet I of the flow battery stack, the slurry contains carbon materials and solvents, the slurry enters the positive electrode channel, and the positive electrolyte outlet I of the flow battery stack is connected to the inlet of the slurry storage unit.

10. The apparatus for preparing a particulate catalyst according to claim 8, characterized in that, The positive electrode plate is a stabilizing electrode; the positive electrolyte is a sulfuric acid solution. The outlet of the positive electrolyte storage unit is connected to the positive electrolyte inlet II of the flow battery stack, and the positive electrolyte outlet II of the flow battery stack is connected to the inlet of the positive electrolyte storage unit.

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