A process for in-situ loading of hydrogen generation catalysts by laser in additive manufacturing processes

Abstract

The application discloses a process for in-situ loading of hydrogen production catalyst by laser in an additive manufacturing process. Aerosol particles containing catalyst precursors are sprayed to the surface of the newly formed substrate material while the layer-by-layer fused deposition modeling is being carried out, and then laser scanning irradiation is carried out on the area where the catalyst precursors are deposited, so that the active catalyst components are generated and fixed in-situ. The application breaks through the deposition bottleneck that is prone to occur in complex three-dimensional channels in the traditional impregnation method, and can realize integrated manufacturing of structure and function. The process is simple, efficient and high in loading precision, and is suitable for integrated application of hydrogen production micro-reactors and fuel cell systems.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of additive manufacturing (3D printing) and high-temperature functional device fabrication, and specifically relates to a process method for simultaneously achieving in-situ loading of hydrogen production catalyst during 3D printing to manufacture a high-temperature resistant structure-function integrated microreactor. Background Technology

[0002] Currently, methanol reforming for hydrogen production is widely used in fuel cell hydrogen supply systems as a highly efficient and miniaturized method. Its core lies in the loading and activity maintenance of the catalyst on the reaction support. However, existing catalyst loading technologies mostly employ traditional processes such as impregnation, dip coating, co-precipitation, or sol-gel methods. While these methods have a certain degree of maturity on conventional particulate supports or planar structures, they have significant limitations when dealing with reactors with complex spatial structures or microscale channels.

[0003] In practical applications, as hydrogen production microreactors develop towards integrated, miniaturized, and complex structures, the support is typically fabricated using metal or polymer 3D printing technologies, such as fused deposition modeling (FDM), and contains complex flow channel structures including multi-scale pores, meshes, honeycombs, or TPMS. These structures offer unique advantages in increasing specific surface area and enhancing heat and mass transfer. For FDM-formed microreactors, catalyst loading is usually achieved through post-processing methods such as impregnation or coating. However, when the support has a complex three-dimensional internal structure (such as microchannels, honeycombs, porous structures, or topology-optimized components), traditional impregnation processes present the following prominent problems:

[0004] 1. The catalyst has difficulty fully penetrating the complex internal structure, and the liquid wettability is limited, resulting in the catalyst being concentrated and deposited only in the outer layer or edge region;

[0005] 2. Uneven loading distribution and significant differences in catalyst content between the inside and outside of the channel cause uneven local reactions and reduced conversion efficiency;

[0006] 3. During the drying and calcination process, the pores are easily blocked, the material falls off, or a thick layer is formed, which seriously affects the heat transfer and fluid characteristics of the microchannel reactor;

[0007] 4. The process is complicated and time-consuming, making it difficult to be compatible with metal or high-temperature polymer 3D printing processes, and thus unable to achieve integrated manufacturing.

[0008] Therefore, there is an urgent need to develop a novel catalyst-supported technology that can be closely integrated with the additive manufacturing process of complex structures to overcome the inherent defects of traditional methods. Summary of the Invention

[0009] To address the problems of uneven catalyst penetration, pore blockage, poor adhesion of the supported layer, and inability to achieve integrated manufacturing and function in complex structures using traditional impregnation methods, this invention provides a laser-supported in-situ hydrogen production catalyst process during additive manufacturing. This process utilizes the synergistic effect of aerosol spraying and laser scanning during 3D printing to achieve simultaneous deposition, in-situ fixation, and local transformation of the catalyst precursor, thereby enabling the in-situ construction of a uniform, highly adherent catalyst layer on the inner and outer surfaces of complex three-dimensional structures.

[0010] The technical solution of the present invention is as follows:

[0011] A process for laser-supported in-situ hydrogen production catalysts during additive manufacturing involves printing microreactor components with internal microchannels layer by layer according to a pre-set model, wherein at least a portion of the fabrication includes:

[0012] (1) A layer of substrate is deposited using a 3D printing nozzle;

[0013] (2) After a substrate layer is deposited, the catalyst precursor solution is sprayed in the form of an aerosol onto the surface of the newly formed substrate using an aerosol spray nozzle; the catalyst precursor is a metal catalyst precursor.

[0014] (3) The area of ​​the deposited catalyst precursor is irradiated by laser scanning; the laser scanning causes micro-melting on the surface of the substrate, and at the same time causes the catalyst precursor to decompose and crystallize in situ, forming a catalyst active layer that is bonded to the substrate.

[0015] (4) Repeat steps (1) to (3).

[0016] Optionally, the aerosol jetting nozzle is arranged coaxially or adjacent to the 3D printing nozzle, wherein the adjacent-axis arrangement means that the aerosol jetting nozzle and the 3D printing nozzle are parallel to the central axis and maintain a fixed distance.

[0017] Optionally, the microchannels are periodic arrays or topology-optimized structures, with the width of a single microchannel being 0.8–1.5 mm; the catalyst active layer is disposed on at least a portion of the surface of the microchannels.

[0018] Optionally, the aerosol spray nozzle has a spray flow rate of 0.05–0.3 mL / s, a spray particle size of 10–50 μm, and a spray pressure of 0.1–0.3 MPa.

[0019] Optionally, the laser scanning uses an ultraviolet pulsed laser and is equipped with a laser processing head with five-axis linkage control.

[0020] Optionally, the laser scanning spot diameter is 10-30 μm, the repetition frequency is 10-40 kHz, the scanning speed is 200-600 mm / s, the power is 5-30 W, and the scanning path adopts a grid pattern.

[0021] Optionally, the heat resistance temperature of the substrate exceeds 300°C, such as high-temperature resistant high-performance thermoplastic materials like PEEK and PEI.

[0022] Optionally, in step (1), a high-temperature FDM printer is used, the temperature of the FDM printhead is 380-420 ℃, the working platform temperature is 100-140 ℃, and the thickness of the printed substrate layer is 0.1-0.3 mm; the total thickness of the microreactor component is 3-10 mm.

[0023] Optionally, the catalyst precursor solution contains a soluble salt of at least one of copper, zinc, aluminum, and zirconium, and the solvent is deionized water or a mixture of water and a low-carbon alcohol.

[0024] Optionally, the preparation of the catalyst precursor solution includes: dissolving a nitrate hydrate of at least one of copper, zinc, aluminum, and zirconium in deionized water to obtain a precursor solution; adding aluminum isopropoxide (Al[OCH(CH3)2]3) to a mixed solvent composed of deionized water, isopropanol, and concentrated nitric acid, and obtaining aluminum sol through a hydrolysis-condensation reaction; and mixing the precursor solution with the aluminum sol to obtain a catalyst precursor solution for aerosol spraying.

[0025] The catalyst precursor solution is ultrasonically atomized and sprayed onto the surface of the substrate using nitrogen as a carrier.

[0026] The beneficial effects of this invention are as follows:

[0027] 1. Catalyst loading with complex internal structures: The good atomization of aerosols and the reachability of lasers make it possible to load catalysts in complex internal channels and cavities formed in 3D, overcoming the disadvantage of difficult penetration by impregnation method.

[0028] 2. High catalyst bonding strength: The laser-induced micro-melting effect of the matrix enables the catalyst particles to form an "anchored" structure with the matrix, and the bonding strength is far superior to physical adsorption or simple coating.

[0029] 3. High process integration and simplified process: The catalyst loading process is integrated into the additive manufacturing process, realizing integrated structure-function manufacturing and eliminating cumbersome post-processing steps.

[0030] 4. Uniform and controllable catalyst distribution: By precisely controlling the aerosol injection amount and laser scanning path, the catalyst can be loaded uniformly and on demand in three-dimensional space.

[0031] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the process in the embodiment;

[0033] Figure 2 Surface morphology images of catalysts supported on different TPMS structures;

[0034] Figure 3 Here is a SEM image of the carrier surface after laser loading;

[0035] Figure 4 The distribution of EDS elements on the carrier surface after laser loading;

[0036] Figure 5 The methanol conversion rate of the carrier in Example 1 at different reaction space velocities is shown. Detailed Implementation

[0037] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0038] The embodiments present a process for in-situ loading of methanol reforming hydrogen production catalysts using a combination of laser and aerosol spraying in additive manufacturing. For example... Figure 1 As shown, the equipment used integrates an FDM printer, an aerosol jetting device, and a laser. On the printing platform, an FDM printhead is used to print the substrate layer by layer. After each substrate layer is deposited, an aerosol jetting nozzle directionally sprays a catalyst precursor solution in aerosol form onto the newly formed substrate surface. The area where the catalyst precursor has been deposited is then irradiated with a laser. Utilizing the instantaneous heating and localized ablation effect of the laser beam, in-situ transformation and uniform adhesion of the catalyst are achieved on the surface of the printed component. This method can achieve in-situ deposition and alloying transformation of the catalyst layer while the printed component is being formed layer by layer, effectively avoiding problems such as uneven catalyst penetration, pore blockage, and poor adhesion existing in traditional impregnation methods, thus achieving the integration of structural manufacturing and functional load.

[0039] Specifically, the aerosol jet nozzle is parallel to and maintains a fixed distance from the central axis of the FDM printing nozzle, ensuring that the aerosol spray can accurately cover the newly deposited material layer while avoiding interference with the already deposited material layer. The laser is equipped with a five-axis linkage control laser processing head, including X, Y, and Z linear axes to control the precise linear movement of the laser processing head in three-dimensional space and determine the spatial position of the processing point; and two rotational axes, V and U, where the V-axis rotates around the Y-axis and the U-axis rotates around the X-axis, thereby adjusting the beam irradiation angle to achieve multi-angle processing to adapt to the processing of curved microchannel surfaces; comprehensively realizing precise scanning of complex three-dimensional shaped surfaces at different angles.

[0040] Example 1: Pulsed laser-supported catalyst

[0041] 1. Preparation of catalyst precursor solution

[0042] (1) Weigh out 25.52 g of copper, zinc, aluminum and zirconium nitrate salt hydrates in molar ratio Cu:Zn:Al:Zr = 11:6:4:1, add them to 150 mL of deionized water, stir thoroughly until completely dissolved, and obtain a homogeneous and clear precursor solution.

[0043] (2) Weigh 20.4 g of aluminum isopropoxide (Al[OCH(CH3)2]3) and add it to a mixed solvent consisting of 90 mL of deionized water, 10 mL of isopropanol and 1.5 mL of concentrated nitric acid. Stir the mixture in a water bath at 60 °C for 6 h using a magnetic stirrer to obtain a stable aluminum sol through hydrolysis and polycondensation reaction.

[0044] (3) Take 13.12 mL of the precursor solution from step (1) and 2 mL of the aluminum sol from step (2) and mix them evenly to obtain the catalyst precursor solution for subsequent aerosol spraying.

[0045] 2. FDM Additive Manufacturing of High-Temperature Resistant Microreactor Substrates

[0046] (4) Substrate Printing: Polyetheretherketone (PEEK), with a heat resistance exceeding 300°C, was selected as the printing material. A high-temperature FDM printer was used, with the extruder temperature set to 400°C, the working platform temperature to 120°C, and the substrate layer thickness to 0.2 mm. Based on the preset 3D model, the microreactor substrate with complex internal microchannels was printed layer by layer. During the printing process, the surface of each layer was ensured to be flat to provide a good substrate for subsequent catalyst loading.

[0047] 3. In-situ loading of catalysts and laser curing

[0048] (5) Aerosol Jetting: After the printer completes the deposition of a substrate layer (e.g., including the layer forming the inner wall of the microchannels), an aerosol jetting nozzle working in conjunction with the FDM printhead sprays the catalyst onto a specific area (e.g., the area forming the inner wall of the microchannels) on the newly formed substrate layer. The catalyst precursor solution prepared in step (3) is ultrasonically atomized and uniformly sprayed onto the still-warm PEEK substrate surface using nitrogen as a carrier. The spraying flow rate is controlled at 0.05–0.3 mL / s, the spray particle size is 10–50 μm, and the spraying pressure is 0.1–0.3 MPa to ensure uniform deposition of the precursor on the printed layer surface. The residual heat of the substrate helps the solvent to initially evaporate, allowing the catalyst precursor to initially adhere.

[0049] (6) In-situ laser conversion: Immediately following aerosol spraying, a laser processing head equipped with five-axis linkage control immediately performs a precise scan on the area covered with the precursor. The laser used is a 355 nm ultraviolet pulsed laser with a spot diameter of 22.4 μm, a repetition frequency of 40 kHz, a scanning speed of 200–600 mm / s, and a power of 5–30 W. The scanning path is grid-like and scans along the curved surface of the microchannel inner wall to ensure uniform heating of the catalyst layer and avoid excessive ablation. Preferably, a suitable energy is used for single or multiple repeated scans, with no more than 5 repetitions. The localized instantaneous heating effect of the laser causes micro-melting on the substrate surface, promoting the embedding and anchoring of the catalyst precursor; on the other hand, it causes thermal decomposition and preliminary alloying reactions in the catalyst precursor, forming a catalyst active layer with an active metal phase or metal oxide phase, which is firmly bonded to the micro-melted substrate.

[0050] 4. Iteration and Post-processing

[0051] (7) Iterative cycle: Repeat steps (4) to (6), namely “print a substrate layer → spray catalyst precursor → laser curing”, until the printing of the entire microreactor component and the catalyst loading are completed simultaneously.

[0052] Figure 2 The images show the surface morphology of catalysts loaded with different TPMS structures. The above process can be used to load catalysts with complex flow channel structures such as multi-scale pores, grids, honeycombs or TPMS.

[0053] The prepared integrated microreactor was characterized. For example... Figure 3 Scanning electron microscopy (SEM) observations showed that the catalyst was uniformly distributed on the inner wall of the PEEK microchannels, with particle sizes mainly concentrated in the range of 2-5 μm. Figure 4Energy dispersive spectroscopy (EDS) analysis showed that elements such as Cu, Zn, Al, and Zr were uniformly dispersed in the catalyst particles. The catalyst layer was tightly bonded to the substrate, with no large-area detachment, demonstrating the excellent adhesion of this process.

[0054] The performance of the methanol steam reforming reaction was tested using the microreactor prepared in Example 1. An aqueous methanol solution (molar ratio 1.3:1) was introduced under normal pressure at a space velocity (GHSV) of 2500 mL·g⁻¹. -1 ·h -1 The reaction temperature was 280℃. The reaction products were analyzed online using gas chromatography to monitor the methanol conversion rate in real time. The experimental results are as follows: Figure 5 The results indicate that the energy input and the number of repetitions of laser treatment jointly determine the structural integrity and reactivity of the catalyst layer. Comprehensive comparison revealed that moderate energy input and multiple repeated scans (10W, 200 mm / s, 2 scans) contribute to the densification and phase transformation of the catalyst layer, achieving a methanol conversion rate of approximately 91%. These results validate the feasibility of using lasers to achieve rapid conversion of catalyst precursors within a short time and provide quantitative evidence for energy control and parameter optimization in laser in-situ loading processes.

[0055] Based on a similar mechanism, other catalysts can also be loaded efficiently using the above-mentioned in-situ catalyst loading process.

[0056] Compared with traditional post-treatment methods such as impregnation, spraying, and calcination loading, the present invention has the following significant advantages:

[0057] 1. Integration of structural fabrication and functional loading: This method completes in-situ catalyst loading while FDM printing, eliminating the need for additional impregnation and calcination steps, which significantly simplifies the preparation process.

[0058] 2. Improve the uniformity of load inside complex structures: The combination of aerosol spraying and local laser heating enables the catalyst to effectively enter complex internal cavities and microchannel structures, overcoming the defect of difficult wetting of the inner layer in traditional methods.

[0059] 3. Enhanced bonding strength between the catalyst layer and the carrier: Laser heating achieves a local melting-re-solidification process within microseconds, forming a tight interfacial bonding layer, which significantly improves the adhesion and durability of the catalyst layer.

[0060] 4. Controllable catalyst layer structure and active phase formation: By adjusting the laser power, scanning speed and aerosol flow rate, the controllable transformation of catalyst layer grain size, phase composition and surface microstructure can be achieved, thereby improving the activity and stability of methanol reforming reaction.

[0061] 5. Adaptable to multiple material systems: This process is applicable to various matrices such as metals, ceramics, and high-temperature polymers for FDM printing, and can be extended to the preparation of structural-functional integrated reactors.

[0062] In summary, this invention is the first to deeply integrate laser in-situ loading technology with FDM additive manufacturing process. Through the synergistic control of laser-fluid-thermal processes, it successfully achieves the synchronous deposition and in-situ conversion of catalysts on the surface of three-dimensional printed components, providing a new technical path and process foundation for the preparation of methanol reforming hydrogen production microreactors with integrated structure and function.

[0063] The above embodiments are only used to further illustrate a process for laser-supported in-situ hydrogen production catalyst in additive manufacturing according to the present invention. However, the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A process for laser-supported in-situ hydrogen production catalyst during additive manufacturing, characterized in that, Based on a pre-designed model, a microreactor component with internal microchannels is printed layer by layer, wherein at least part of the fabrication includes: (1) A layer of substrate is deposited using a 3D printing nozzle; (2) After a substrate layer is deposited, the catalyst precursor solution is sprayed in the form of an aerosol onto the surface of the newly formed substrate using an aerosol spray nozzle; the catalyst precursor is a metal catalyst precursor. (3) The area of ​​the deposited catalyst precursor is irradiated by laser scanning; the laser scanning causes micro-melting on the surface of the substrate, and at the same time causes the catalyst precursor to decompose and crystallize in situ, forming a catalyst active layer that is bonded to the substrate. (4) Repeat steps (1) to (3).

2. The process for laser-supported in-situ hydrogen production catalyst during additive manufacturing according to claim 1, characterized in that: The aerosol jetting nozzle is arranged coaxially or adjacent to the 3D printing nozzle, wherein the adjacent-axis arrangement means that the aerosol jetting nozzle and the 3D printing nozzle are parallel to the central axis and maintain a fixed distance.

3. The process for laser-supported in-situ hydrogen production catalyst during additive manufacturing according to claim 1, characterized in that: The microchannels are periodic arrays or topology-optimized structures, with the width of a single microchannel being 0.8–1.5 mm; the catalyst active layer is disposed on at least a portion of the surface of the microchannels.

4. The process for laser-supported in-situ hydrogen production catalyst during additive manufacturing according to claim 1, characterized in that: The aerosol spray nozzle has a spray flow rate of 0.05–0.3 mL / s, a spray particle size of 10–50 μm, and a spray pressure of 0.1–0.3 MPa.

5. The process for laser-supported in-situ hydrogen production catalyst during additive manufacturing according to claim 1, characterized in that: The laser scanning uses an ultraviolet pulsed laser and is equipped with a laser processing head with five-axis linkage control.

6. The process for laser-supported in-situ hydrogen production catalyst during additive manufacturing according to claim 5, characterized in that: The laser scanning spot diameter is 10-30 μm, the repetition frequency is 10-40 kHz, the scanning speed is 200-600 mm / s, the power is 5-30 W, and the scanning path adopts a grid pattern.

7. The process for laser-supported in-situ hydrogen production catalyst during additive manufacturing according to claim 1, characterized in that: The heat resistance temperature of the substrate exceeds 300°C.

8. The process for laser-supported in-situ hydrogen production catalyst during additive manufacturing according to claim 7, characterized in that: In step (1), a high-temperature FDM printer is used. The temperature of the FDM printhead is 380-420 ℃, the temperature of the working platform is 100-140 ℃, and the thickness of the printed substrate layer is 0.1-0.3 mm. The total thickness of the microreactor component is 3-10 mm.

9. The process for laser-supported in-situ hydrogen production catalyst during additive manufacturing according to claim 1, characterized in that: The catalyst precursor solution contains a soluble salt of at least one of copper, zinc, aluminum, and zirconium, and the solvent is deionized water or a mixture of water and low-carbon alcohols.

10. The process for laser-supported in-situ hydrogen production catalyst during additive manufacturing according to claim 9, characterized in that, The preparation of the catalyst precursor solution includes: dissolving a nitrate hydrate of at least one of copper, zinc, aluminum, and zirconium in deionized water to obtain a precursor solution; adding aluminum isopropoxide to a mixed solvent composed of deionized water, isopropanol, and concentrated nitric acid, and obtaining aluminum sol through a hydrolysis-condensation reaction; and mixing the precursor solution with the aluminum sol to obtain a catalyst precursor solution for aerosol spraying. The catalyst precursor solution is ultrasonically atomized and sprayed onto the surface of the substrate using nitrogen as a carrier.

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