Structural catalyst of composite porous metal matrix as well as preparation method and application of structural catalyst

Abstract

The invention relates to a structural catalyst of a composite porous metal matrix as well as a preparation method and application thereof, and the technical steps are as follows: (1) manufacturing macroscopic porous metal by adopting a metal 3D printing technology, and then cleaning; (2) soaking the macroscopic porous metal in the step (1) in corrosive liquid for a period of time, and then cleaning; (3) calcining the corrosion porous metal in the step (2) to obtain a composite porous metal matrix; and (4) loading a coating and an active component by adopting the composite porous metal matrix obtained in the step (3). The method has the advantages that the macroscopic flow field is controllable, the diffusion distance is short, and the heat conductivity coefficient is high; the metal matrix with high porosity has strong capillary force, so that the dispersity of active components in the coating is effectively improved; secondly, the high-porosity metal matrix can load the active component, so that the active component loading upper limit of the structure catalyst is improved, and the defect of low loading capacity of the structure catalyst is overcome; and finally, the binding force of the coating of the matrix is effectively improved through the high-roughness surface of the metal matrix.

Description

Technical field

[0001] The present invention relates to the technical field of structured catalysts, in particular to a structured catalyst based on a composite porous metal matrix and a preparation method and application thereof. [Background Technology]

[0002] Metal-based monolithic catalysts are primarily suitable for high-vibration, high-endothermic and high-exothermic reactions with high throughput, such as Fischer-Tropsch synthesis, ammonia synthesis, and catalytic combustion. Industrial production uses fixed-bed reactors filled with granular catalysts, which present problems such as high pressure drop, poor mass and heat transfer, and low catalyst utilization. Researchers have developed metal-based monolithic catalysts to enhance heat and mass transfer. Chinese Patent Publication No. CN104028280 uses FeCrAl alloy to load carriers and active components such as Fe2O3 and NiO for methane synthesis gas production. Chinese Patent Publication No. CN116422334 uses foamed metal to load active components through electrodeposition for methane cracking to produce hydrogen. The structure of this catalyst is limited by traditional processing methods, and the loading of active components is relatively low.

[0003] 3D printing, due to its strong designability and ability to achieve complex geometric structures, has been applied to the field of monolithic catalysts. One approach uses non-metallic 3D printing technologies such as photocuring (DLP) and direct ink writing (DIW) to prepare a non-metallic carrier, followed by impregnation of the active component, as shown in Chinese Patent Publication Nos. CN112121865 and CN113426464. However, these catalysts have low mechanical strength and thermal conductivity, making them unsuitable for highly exothermic and endothermic reactions. Another approach uses metal 3D printing and dealloying techniques to mix the active component metal with the metal powder to be corroded, printing and forming the mixture. The metal powder to be corroded is then corroded with alkaline or acidic solutions to obtain a structured catalyst composed of the active component metal, as shown in Chinese Patent Publication No. CN111229231. Currently available catalysts have low active component utilization rates and high manufacturing costs, making them unsuitable for precious metal catalysts. [Summary of the invention]

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a composite porous metal matrix structure catalyst and its preparation method and application. The composite porous metal matrix structure catalyst has strong heat transfer performance and high catalyst activity.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] A method for preparing a structured catalyst of a composite porous metal matrix, comprising the following technical steps:

[0007] (1) Using metal 3D printing technology to manufacture macroporous metals, followed by cleaning;

[0008] (2) immersing the macroporous metal in step (1) in a corrosive solution for etching, and then cleaning;

[0009] (3) calcining the corroded porous metal in step (2) to obtain a composite porous metal matrix;

[0010] (4) using the composite porous metal substrate obtained in step (3) to load the coating and active components;

[0011] In step (1),

[0012] Metal 3D printing technologies include but are not limited to selective laser melting (SLM), selective laser sintering (SLS), and fused deposition modeling (FDM).

[0013] Metal materials include but are not limited to aluminum alloys, nickel alloys, iron alloys, and copper alloys.

[0014] The macrostructure of the porous metal matrix is ​​composed of a multi-layer pore structure with a pore diameter of 100 microns to 5 mm, for example, it can be 100 microns, 200 microns, 500 microns, 1 mm, 2 mm, 5 mm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also suitable.

[0015] The surface of the porous metal substrate has a roughness of 0 to 1 mm, for example, 100 microns, 200 microns, 500 microns, 1 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also suitable.

[0016] In step (2),

[0017] Corrosion can be done by acid or alkaline etching.

[0018] The acid solution includes but is not limited to hydrochloric acid solution and nitric acid solution, with a concentration of 0.0001 to 1 mol / L.

[0019] The alkaline solution includes but is not limited to KOH solution and NaOH solution, with a solubility of 0.0001 to 1 mol / L, for example, 0.0001 mol / L, 0.001 mol / L, 0.01 mol / L, 0.1 mol / L, 1 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also suitable.

[0020] The corrosion temperature is 10-80°C, for example, 10°C, 20°C, 40°C, 80°C, but is not limited to the listed values. Other values ​​not listed within the numerical range are also suitable.

[0021] The corrosion time is 5 to 60 minutes.

[0022] In step (3),

[0023] The calcination temperature is 200-800°C and the calcination time is 2-10 hours.

[0024] In step (4),

[0025] The coating material includes but is not limited to a composite material of one or more of alumina, molecular sieve, and activated carbon, and the coating loading is 10 to 40 wt%.

[0026] Active components include but are not limited to Co, Pt, Pd, Ru, and the loading amount is 20 to 80 wt%.

[0027] The monolithic catalyst with a composite porous metal matrix is ​​used in Fischer-Tropsch synthesis, ammonia synthesis, and catalytic combustion.

[0028] This invention designs a structured catalyst with a composite porous metal matrix. The metal matrix prepared in this invention has a controllable microscopic pore structure. Compared with traditional particle catalysts, this invention has advantages such as a controllable macroscopic flow field, a short diffusion distance, and a high thermal conductivity.

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

[0030] Compared with commercial structured catalysts, the advantage of the structured catalyst of the present invention is that the high-porosity metal matrix has a strong capillary force, which effectively improves the dispersion of the active components in the coating; secondly, the high-porosity metal matrix can load the active components, increase the upper limit of the active component loading of the structured catalyst, and solve the problem of low loading of the structured catalyst; finally, the high-roughness surface of the metal matrix effectively improves the bonding strength of the coating of the matrix.

Brief Description of the Drawings

[0031] Figure 1 This is a macroscopic structure diagram of the porous metal after step (1) in Example 1;

[0032] Figure 2 The microstructure of the porous metal after step (1) in Example 1;

[0033] Figure 3a This is a microscopic morphology image of the composite porous structure matrix after steps (1), (2) and (3) in Example 1 at a magnification of 10,000.

[0034] Figure 3b This is a microscopic morphology image of the composite porous structure matrix after steps (1), (2) and (3) in Example 1 at a magnification of 20,000.

[0035] Figure 3c This is a microscopic morphology image of the composite porous structure matrix after steps (1), (2) and (3) in Example 1 at a magnification of 30,000.

[0036] Figure 4a is the contact angle before steps (1), (2) and (3) in Comparative Example 1,

[0037] Figure 4b is the contact angle after steps (1), (2) and (3) in Comparative Example 1,

[0038] Figure 4c The contact angle of Example 1 before steps (1), (2) and (3) is shown.

[0039] Figure 4d The contact angle of Example 1 after steps (1), (2) and (3).

[0040] Figure 5 This is the EDS graph of the composite porous structure matrix after steps (1), (2), (3) and (4) in Example 1.

[0041] Figure 6 The XRD patterns of the aluminum oxide coatings of Example 1 and Comparative Example 1 after steps (1), (2), (3) and (4) are shown. [Specific implementation method]

[0042] The following provides a specific embodiment of a structured catalyst of a composite porous metal matrix, a preparation method, and an application of the present invention.

[0043] Example 1

[0044] This embodiment provides a method for preparing a composite porous metal matrix, and a method for preparing an integral catalyst using the composite porous metal matrix.

[0045] (1) Manufacturing macroporous metal: A porous structure matrix was obtained by metal 3D printing using aluminum-silicon-magnesium alloy powder (aluminum: 88-92%, silicon: 8-12%, magnesium: balance). The porous structure matrix was placed in deionized water and ultrasonically cleaned for 30 minutes.

[0046] (2) Corrosion: Place the porous substrate in a 0.0001 mol / L hydrochloric acid solution for 5 minutes and rinse with deionized water. Then place the porous substrate in a 0.0001 mol / L NaOH solution for 5 minutes and rinse with deionized water.

[0047] (3) Calcination: Finally, calcination is carried out at 800°C for 10 hours.

[0048] (4) Preparation of the surface coating on the porous aluminum-silicon-magnesium substrate: A 10 wt% alumina coating was prepared using a slurry method. γ-Al2O3 powder, deionized water, and a dispersant were mixed in appropriate proportions and stirred for 12 h to obtain an alumina slurry. The porous aluminum-silicon-magnesium substrate was immersed in the alumina slurry. Excess slurry was then blown off. Finally, the substrate was calcined at 450°C for 4 h.

[0049] Preparation of the active component Co: A 40 wt% Co active component loading was prepared using an impregnation method. A precursor solution was prepared by mixing 200 g of Co(NO₃)₂·6H₂O with 100 g of deionized water and stirring until completely dissolved. A porous aluminum-silicon-magnesium substrate coated with an alumina coating was immersed in the precursor solution for 2 hours. Finally, the substrate was calcined at 300°C for 4 hours.

[0050] Figure 1 This is the macroscopic structure of the porous metal after step (1) in Example 1. It can be seen that the porous metal is a three-dimensional periodic open-pore structure;

[0051] Figure 2 The microstructure of the porous metal after step (1) in Example 1. It can be seen that there are microstructures on the surface of the porous metal caused by the molten pool and unmelted alloy powder;

[0052] Figure 3 shows the microscopic morphology of the composite porous structure matrix after steps (1), (2), and (3) in Example 1, with (a) at a magnification of 10,000, (b) at a magnification of 20,000, and (c) at a magnification of 30,000. It can be seen that the composite porous structure matrix has a rich microscopic pore structure.

[0053] Figures 4(a) and (b) show the contact angles before and after steps (1), (2), and (3) in Comparative Example 1, and Figures 4(c) and (d) show the contact angles before and after steps (1), (2), and (3) in Example 1. It can be seen that after corrosion, the hydrophilicity of both substrates is improved. However, the hydrophilicity of the composite porous structure substrate in Example 1 is more pronounced, and the water droplet is completely immersed in the substrate.

[0054] Figure 5 This is the EDS image of the composite porous structure matrix after steps (1), (2), (3) and (4) in Example 1. It can be seen that the matrix contains not only matrix elements (Al, Si, Mg) but also the active component Co, indicating that the composite porous structure matrix can load the active component.

[0055] Figure 6 The XRD patterns of the alumina coatings after steps (1), (2), (3) and (4) of Example 1 and Comparative Example 1 are shown. The half-peak width of Co3O4 in Example 1 is smaller than that in Comparative Example 1, indicating that the alumina coating of Example 1 has better dispersion of Co3O4.

[0056] The present invention designs a structured catalyst having a composite porous metal matrix. The metal matrix prepared by the present invention has a controllable microscopic pore structure. Compared with traditional particulate catalysts, the advantages of the present invention are: a controllable macroscopic flow field, a short diffusion distance, and a high thermal conductivity. Compared with commercial structured catalysts, the advantages of the structured catalyst of the present invention are that the high-porosity metal matrix has a strong capillary force, which effectively improves the dispersion of the active components in the coating; secondly, the high-porosity metal matrix can load the active components, increasing the upper limit of the active component loading of the structured catalyst and solving the problem of low loading of the structured catalyst; finally, the high-roughness surface of the metal matrix effectively improves the bonding strength of the coating of the matrix.

[0057] Example 2

[0058] Steps (2) and (3) were omitted, the active ingredient was 20 wt%, and the rest was the same as in Example 1.

[0059] Example 3

[0060] Steps (2) and (3) were omitted, the active ingredient was 40 wt%, and the rest was the same as in Example 1.

[0061] Example 4

[0062] Steps (2) and (3) were omitted, the active component was 60 wt%, and the rest was the same as in Example 1.

[0063] Example 5

[0064] The same treatment method as in Example 1 was used, with 20 wt% active ingredient, and the rest was the same as in Example 1.

[0065] Example 6

[0066] The same treatment method as in Example 1 was used, with 60 wt% active ingredient, and the rest was the same as in Example 1.

[0067] Example 7

[0068] The same treatment method as in Example 1 was used, with 80 wt% active ingredient, and the rest was the same as in Example 1.

[0069] Example 8

[0070] The treatment method of step (2) in Example 1 was modified by placing the porous substrate in a 0.1 mol / L hydrochloric acid solution for 5 minutes and then rinsing it with deionized water. The porous substrate was then placed in a 0.1 mol / L NaOH solution for 5 minutes and then rinsed with deionized water.

[0071] Example 9

[0072] The treatment method of step (3) in Example 1 was changed, and the product was finally calcined at 300° C. for 2 h.

[0073] Comparative Example 1

[0074] A commercial iron-chromium-aluminum alloy honeycomb was used as the substrate and ultrasonically cleaned for 30 minutes. The porous substrate was placed in a 1 mol / L hydrochloric acid solution for 5 minutes and then rinsed with deionized water. The porous substrate was then placed in a 1 mol / L NaOH solution for 5 minutes and rinsed with deionized water. Finally, the porous substrate was calcined at 950°C for 10 hours. The coating and active component loading were consistent with those in Example 1.

[0075] The embodiment was applied to Fischer-Tropsch synthesis, with a reaction temperature of 230°C, a pressure of 2 MPa, and a space velocity of 4000 h -1 , inlet gas composition CO:H2=1:2.

[0076] Table 1

[0077] This application Alumina coating shedding rate CO conversion rate CH4 selectivity C5+ selectivity Example 1 0.21％ 59.3％ 9.2％ 82.5％ Example 2 0.57％ 45.2％ 7.5％ 86.4％ Example 3 0.69％ 55.2％ 12.3％ 78.2％ Example 4 0.54％ 46.7％ 14.1％ 72.3％ Example 5 0.31％ 40.3％ 5.2％ 91.6％ Example 6 0.13％ 62.9％ 10.3％ 83.8％ Example 7 0.19％ 63.5％ 13.5％ 75.8％ Example 8 0.44％ 55.6％ 8.7％ 84.5％ Example 9 0.36％ 58.2％ 7.7％ 89.3％ Comparative Example 1 1.65％ 32.2％ 10.4％ 81.9％

[0078] The coating adhesion and reaction performance of Examples 1 to 9 are better than those of Comparative Example 1.

[0079] The coating adhesion of Examples 1 and 5 to 9, which were subjected to etching and baking treatments, was better than that of Examples 2 to 4, which were not subjected to etching and baking treatments.

[0080] The Co loading of Examples 1 and 5 to 7, which were subjected to etching and calcination, was preferably 60 wt %, which was higher than 40 wt % of Examples 2 to 4, which were not subjected to etching and calcination.

[0081] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the concept of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a structured catalyst of a composite porous metal matrix, characterized in that: The technical steps involved are: (1) Using metal 3D printing technology to manufacture macroporous metals, followed by cleaning; (2) immersing the macroporous metal in step (1) in a corrosive solution for etching, and then cleaning; (3) calcining the corroded porous metal in step (2) to obtain a composite porous metal matrix; (4) Using the composite porous metal substrate obtained in step (3) to load the coating and active components.

2. The method for preparing a structured catalyst of a composite porous metal matrix according to claim 1, characterized in that: In step (1), metal 3D printing technologies include but are not limited to selective laser melting (SLM), selective laser sintering (SLS), and fused deposition modeling (FDM).

3. The method for preparing a structured catalyst of a composite porous metal matrix according to claim 1, characterized in that: In step (1), the metal material includes but is not limited to aluminum alloy, nickel alloy, and iron alloy.

4. The method for preparing a structured catalyst of a composite porous metal matrix according to claim 1, wherein: In step (1), the macroscopic structure of the porous metal matrix is ​​composed of a multi-layer pore structure with a pore diameter of 100 μm to 5 mm; The surface of the porous metal substrate has roughness, and the surface roughness is 0 to 1 mm.

5. The method for preparing a structured catalyst of a composite porous metal matrix according to claim 1, wherein: In step (2), the etching is carried out by acid etching or alkaline etching.

6. The method for preparing a structured catalyst of a composite porous metal matrix according to claim 1, wherein: In step (2), the etching temperature is 10 to 80° C., and the etching time is 5 to 60 minutes.

7. The method for preparing a structured catalyst of a composite porous metal matrix according to claim 1, wherein: In step (3), the calcination temperature is 200-800° C. and the calcination time is 2-10 hours.

8. The method for preparing a structured catalyst of a composite porous metal matrix according to claim 1, characterized in that: In step (4), the coating material includes but is not limited to a composite material of one or more of alumina, molecular sieve, and activated carbon, and the coating loading is 10 to 40 wt%.

9. The method for preparing a structured catalyst of a composite porous metal matrix according to claim 1, wherein: In step (4), the active components include but are not limited to Co, Pt, Pd, and Ru, and the loading amount is 20 to 80 wt%.

10. Use of the structured catalyst of the composite porous metal matrix as claimed in claim 1 in Fischer-Tropsch synthesis, ammonia synthesis, and catalytic combustion.

Images