Monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen: preparation method and application

Abstract

This invention relates to the field of solid oxide fuel cell technology, specifically to a monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen, its preparation method, and its application. The monolithic honeycomb ceramic catalyst is obtained by coating a catalyst slurry onto the pore walls of a silicon carbide honeycomb ceramic support under negative pressure, followed by drying and calcination. The catalyst slurry includes a noble metal precursor and a composite support; the noble metal precursor includes platinum and palladium, and the composite support includes nano-cerium oxide and γ-alumina. This invention uses a microchannel-type monolithic honeycomb ceramic as a support, which can significantly increase the specific surface area, facilitating the uniform distribution of active material sites in the composite active catalyst layer, and improving the conversion rate and reaction rate of the propane partial oxidation reforming reaction.

Description

Technical Field

[0001] This invention relates to the field of solid oxide fuel cell technology, and more specifically, to a monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen, its preparation method, and its application. Background Technology

[0002] Solid oxide fuel cells (SOFCs) hold great promise for distributed power generation, transportation, and portable power sources. Their anodes typically require high-purity hydrogen or hydrogen-rich syngas as fuel, with low carbon buildup risk. Propane, due to its high energy density and ease of liquefaction and storage, is considered an ideal hydrocarbon feedstock for on-site hydrogen production in SOFCs. However, propane partial oxidation reforming (POR) is a complex reaction system involving multiple strongly exothermic / endothermic coupling steps, including C–H bond breaking, C–C bond breaking, oxygen activation, and water-gas shift reaction. Acceptable conversion rates and hydrogen yields can only be achieved under conditions of 600–800℃ and 0.1–1.0 MPa.

[0003] Currently, the POR catalysts commonly used in industry and laboratories still use powdered or millimeter-sized particulate active components as carriers. Their preparation process usually includes multiple steps such as: impregnation of active metal precursors, drying, calcination, reduction, tableting / granulation, and sieving. The process chain is long, the batch consistency is poor, and additional binders and pore-forming agents are required, resulting in low utilization of precious metals and high costs.

[0004] More importantly, in the SOFC thermally integrated environment, traditional particle beds have the following inherent defects: millimeter-sized particles accumulate to form tortuous channels, and the pressure drop can reach 20–50 kPa when the gas linear velocity is high. This not only increases the power consumption of the blower but also leads to uneven fuel supply on the SOFC anode side, reducing the reactor efficiency; the particles have point contact, and the effective thermal conductivity is less than 1 W / m². -1 K -1 Local hot spots can easily induce metal sintering, carbon deposition and deactivation; after long-term thermal cycling, particles are prone to pulverization, producing fine powder that blocks the flow channels; limited by Knudsen / molecular diffusion resistance, the utilization rate of active sites on the outer surface and inner pores is less than 30%, and high amounts of precious metals are difficult to further improve apparent activity.

[0005] In recent years, researchers have attempted to prepare monolithic catalysts using sol-gel, 3D printing, or electrospinning techniques. However, these methods suffer from common problems such as low slurry solid content (less than 15 wt%), drying shrinkage and cracking, and insufficient support strength, making it impossible to simultaneously achieve high loading, high specific surface area, and low thermal stress. Therefore, developing a propane POR catalytic structure with a simple preparation process, low pressure drop, high heat / mass transfer efficiency, and deep coupling with the SOFC thermal environment has become a pressing technical bottleneck in this field. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen, its preparation method and application.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0008] This invention provides a method for preparing a monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen. The method involves coating a catalyst slurry onto the pore walls of a silicon carbide honeycomb ceramic support under negative pressure, followed by drying and calcination to obtain the monolithic honeycomb ceramic catalyst. The catalyst slurry includes a noble metal precursor and a composite support. The noble metal precursor includes platinum and palladium, and the composite support includes nano-cerium oxide and γ-alumina.

[0009] Furthermore, the silicon carbide honeycomb ceramic carrier has a mesh size of 300-600 mesh.

[0010] Furthermore, the catalyst slurry also includes a binder.

[0011] Further, the noble metal precursor and water are mixed in a mass ratio of 3:2 to obtain a mixed solution. 40% wt of the composite carrier and 1% wt of the binder are added to the mixed solution, which is then mixed and ball-milled to obtain the catalyst slurry.

[0012] Furthermore, the following steps are included:

[0013] S1. Prepare the silicon carbide honeycomb ceramic carrier by using the raw material of the honeycomb ceramic carrier. The raw material of the honeycomb ceramic carrier includes coarse SiC particles, fine SiC particles, aluminum silicate reinforcing agent, sintering aid, binder forming agent and water.

[0014] S2. Prepare the catalyst slurry;

[0015] S3. Spray the catalyst slurry onto one end face of the silicon carbide honeycomb ceramic carrier, and drive the catalyst slurry into the pores of the honeycomb ceramic carrier and adhere it to the pore wall by negative pressure at the other end face of the silicon carbide honeycomb ceramic carrier.

[0016] S4. Dry and calcine to obtain the monolithic honeycomb ceramic catalyst.

[0017] Furthermore, the particle size range of the coarse SiC particles is 25-50 μm, and the particle size range of the fine SiC particles is 0.5-10 μm.

[0018] Furthermore, in the cellular ceramic carrier raw material, the mass percentage of the coarse SiC particles is 72%, and the mass percentage of the fine SiC particles is 15%.

[0019] Furthermore, the pressure value of the negative pressure drive is 10 MPa.

[0020] The present invention also provides a monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen, which is prepared by the method described above.

[0021] This invention also provides the application of the monolithic honeycomb ceramic catalyst described above in the propane partial oxidation reforming reaction for hydrogen production in SOFCs, under atmospheric pressure, at a reaction temperature of 650°C and a space velocity of 5000-20000 h⁻¹. -1 The reaction takes place under specific conditions.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) The method for preparing the monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen in this invention uses microchannel monolithic honeycomb ceramic as a carrier, which can significantly increase the specific surface area, which is beneficial to the uniform distribution of active material sites in the composite active catalyst layer, and improves the conversion rate and reaction rate of propane partial oxidation reforming reaction.

[0024] (2) The method for preparing the monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen of the present invention uses platinum and palladium together in the catalyst slurry, which has the advantages of low temperature and high activity, anti-carbon deposition, high selectivity, easy dispersion, and resistance to poisoning and sintering, and is particularly suitable for use in conjunction with honeycomb ceramic carriers.

[0025] (3) The method for preparing the monolithic honeycomb ceramic catalyst for propane partial oxidation reforming hydrogen production of the present invention replaces the traditional multi-step loading with a single coating, which significantly improves the preparation efficiency.

[0026] (4) The monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen of the present invention has high activity and selectivity: the propane conversion rate is greater than or equal to 90% at 650℃, and the output power density is greater than 0.4 W / cm³. 2 . Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen according to the present invention.

[0028] Figure 2 This is a schematic diagram of the negative pressure-driven coating of catalyst slurry in the preparation method of the present invention. Detailed Implementation

[0029] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0030] The method for preparing the monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen according to the present invention is characterized in that a catalyst slurry is coated on the pore wall of a silicon carbide honeycomb ceramic support by negative pressure driving, and the monolithic honeycomb ceramic catalyst is obtained after drying and calcination; the catalyst slurry includes a noble metal precursor and a composite support, the noble metal precursor includes platinum and palladium, and the composite support includes nano-cerium oxide and γ-alumina.

[0031] The preparation method of the monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to hydrogen production of the present invention uses a microchannel monolithic honeycomb ceramic as a support, which can significantly increase the specific surface area, which is beneficial to the uniform distribution of active material sites in the composite active catalyst layer, and improves the conversion rate and reaction rate of propane partial oxidation reforming reaction. In the composition of the catalyst slurry, platinum and palladium are used in combination, which has the advantages of low temperature and high activity, anti-carbon deposition, high selectivity, easy dispersion, and resistance to poisoning and sintering. It is particularly suitable for use in combination with honeycomb ceramic support. At the same time, nano-cerium oxide and γ-alumina are added, and CeO2 passes through Ce 3+ / Ce 4+ Reversible regulation maintains reaction equilibrium while inhibiting carbon deposition and extending catalyst lifespan; alumina has a high specific surface area, which helps disperse active components and prevents agglomeration.

[0032] The monolithic honeycomb ceramic catalyst preparation method of the present invention can solve the problems of low reforming efficiency, large bed pressure drop and complicated preparation process of existing propane partial oxidation reforming hydrogen production catalysts. The preparation steps are simple, effectively improving the dispersion and utilization rate of noble metal active components, improving the catalytic activity and hydrogen yield of propane partial oxidation reforming, inhibiting the generation of by-product CO, and reducing the risk of SOFC anode poisoning.

[0033] Preferably, the silicon carbide honeycomb ceramic carrier has a mesh size of 300-600 mesh.

[0034] Preferably, the preparation method of the present invention includes the following steps:

[0035] S1. Prepare the silicon carbide honeycomb ceramic carrier raw material into the honeycomb ceramic carrier. The components of the honeycomb ceramic carrier raw material include coarse SiC particles, fine SiC particles, aluminum silicate reinforcing agent, sintering aid, binder forming agent and water.

[0036] Preferably, the particle size range of coarse SiC particles is 25-50 μm, and the particle size range of fine SiC particles is 0.5-10 μm.

[0037] Preferably, in the cellular ceramic carrier raw material, the mass percentage of coarse SiC particles is 72%, and the mass percentage of fine SiC particles is 15%.

[0038] S2. Prepare catalyst slurry;

[0039] Preferably, the catalyst slurry is prepared by mixing a precious metal precursor with water at a mass ratio of 3:2 to obtain a mixed solution, adding 40% wt of composite carrier and 1% wt of binder to 100% of the mass of the mixed solution, mixing and ball milling to obtain the catalyst slurry; the solid content of the catalyst slurry is 40%.

[0040] Preferably, the catalyst slurry also includes a binder, specifically silica sol and aluminum sol.

[0041] S3, such as Figure 2 As shown, a catalyst slurry is sprayed onto one end face of a silicon carbide honeycomb ceramic carrier, and the catalyst slurry is driven into the pores of the honeycomb ceramic carrier by negative pressure and adheres to the pore wall.

[0042] The pressure value for negative pressure drive is 10 MPa.

[0043] S4. Dry and calcine to obtain the monolithic honeycomb ceramic catalyst.

[0044] The monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen of the present invention was prepared by the method described above, and its structure is as follows: Figure 1 As shown.

[0045] The application of the monolithic honeycomb ceramic catalyst of the present invention in the propane partial oxidation reforming hydrogen production reaction of SOFC, under atmospheric pressure, reaction temperature of 650°C, and space velocity (GHSV) of 5000–20000 h⁻¹. -1 The reaction takes place under specific conditions.

[0046] After being preheated in the preheater, the propane mixture enters the monolithic honeycomb ceramic catalyst and undergoes the following reaction:

[0047]

[0048] The products after the reaction are passed through a condenser and a dryer in sequence to obtain hydrogen, carbon dioxide and carbon monoxide.

[0049] The present invention will be illustrated by specific embodiments below.

[0050] Example 1

[0051] Using a 300-mesh monolithic honeycomb ceramic catalyst, at a temperature of 650℃ and a space velocity of 5000 h⁻¹, -1 An integrated SOFC experiment was conducted under operating conditions with a water-to-carbon ratio of 0.8. After stable operation, the propane conversion rate was measured.

[0052] Examples 2-4 are all based on Example 1, the difference being the feed gas space velocity used in the SOFC integration performance test. The test parameters and performance evaluation indicators for Examples 1-4 are shown in Table 1.

[0053] Table 1. Test parameters and performance evaluation indicators for Examples 1-4

[0054]

[0055] Examples 5-9 are all based on Examples 1-4, the difference being that the monolithic honeycomb ceramic catalyst used in the SOFC experiments was 400 mesh. The test parameters and performance evaluation indicators for Examples 5-9 are shown in Table 2.

[0056] Table 2 Test parameters and performance evaluation indicators for Examples 5-8

[0057]

[0058] Examples 9-12 are all based on Examples 1-4, the difference being that the monolithic honeycomb ceramic catalyst used in the SOFC experiments was 600 mesh. The test parameters and performance indicators of Examples 9-12 are shown in Table 3.

[0059] Table 3 Test parameters and performance indicators for Examples 9-12

[0060]

[0061] Performance testing: After running for a certain period of time, test results showed that the propane conversion rate reached 90-97%, and the stack output power density was greater than 0.4 W / cm³. 2 .

[0062] Comparative Example 1

[0063] Referring to Example 1, the difference is that the catalyst used in the SOFC experiment was a single-component Pt catalyst.

[0064] Comparative Example 2

[0065] Referring to Example 1, the difference is that the catalyst used in the SOFC experiment was a single-component Pd catalyst.

[0066] Comparative Example 3

[0067] Referring to Example 1, the difference is that the catalyst support used in the SOFC experiment was γ-alumina.

[0068] Comparative Example 4

[0069] Referring to Example 1, the difference lies in the use of a 200-mesh monolithic honeycomb ceramic catalyst in the SOFC experiment. Currently, it is not possible to prepare honeycomb ceramic supports with higher pore density, making comparison impossible.

[0070] Comparative Example 5 is the same as Example 1, except that the monolithic honeycomb ceramic catalyst used in the SOFC experiment was prepared by impregnation, with a lower loading and uneven coating.

[0071] The test parameters and performance indicators of Comparative Examples 1-5 are shown in Table 4.

[0072] Table 4 shows the test parameters and performance indicators for Comparative Examples 1-5.

[0073]

[0074] The results of Examples 1-12 show that increasing pore density can simultaneously improve conversion efficiency and power density at high space velocities.

[0075] Comparative Examples 1-2 used Pt and Pd single-component catalysts at 5000h -1 At space speed, a conversion efficiency of 91.8% and an output power density of 0.45 W / cm³ were achieved. 2 With a conversion rate of 92.1% and an output power density of 0.47 W / cm³, 2 The conversion rate was 92.3% and the output power density was 0.45 W / cm³ compared to Example 1 (300 mesh). 2 The near-equal figures demonstrate that single precious metals offer no significant advantages, but rather have significant disadvantages due to their high cost.

[0076] Comparative Example 3, using γ-alumina as a support, yielded a conversion rate of only 88.6% and an output power density of 0.43 W / cm³. 2 The efficiency was lower than all honeycomb ceramic systems, highlighting the key role of three-dimensional regular channels in enhancing mass transfer and suppressing hot spots; the 200-mesh low-density carrier in Comparative Example 4 further reduced the conversion rate to 85.7% and the output power density to 0.42 W / cm³. 2 This indicates that insufficient pore density directly limits the active surface area and diffusion efficiency; the impregnation method in Comparative Example 5, due to low loading and uneven distribution, only achieved a conversion rate of 84.1% and an output power density of 0.41 W / cm³. 2 This demonstrates the importance of uniform coating in maintaining the integrity of the catalytic-electrochemical reaction interface.

[0077] In summary, 600-mesh honeycomb ceramics at 15000h -1 At a space velocity of 96.3% propane conversion and 0.59 W / cm², the propane conversion was achieved. 2 The output power density achieves peak performance, breaking through the traditional limits of 200-mesh carrier preparation while avoiding the high cost of precious metals.

[0078] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen, characterized in that, A catalyst slurry is coated on the pore walls of a silicon carbide honeycomb ceramic support, and the catalyst slurry is driven into the pores of the silicon carbide honeycomb ceramic support by negative pressure. After drying and calcination, the monolithic honeycomb ceramic catalyst is obtained. The catalyst slurry includes a noble metal precursor and a composite support. The noble metal precursor includes platinum and palladium, and the composite support includes nano-cerium oxide and γ-alumina. The preparation method specifically includes the following steps: S1. Prepare the silicon carbide honeycomb ceramic carrier by using the raw material of the honeycomb ceramic carrier. The raw material of the honeycomb ceramic carrier includes coarse SiC particles, fine SiC particles, aluminum silicate reinforcing agent, sintering aid, binder, forming agent and water. S2. Prepare the catalyst slurry; S3. The catalyst slurry is sprayed onto one end face of the silicon carbide honeycomb ceramic carrier, and the catalyst slurry is driven into the pores of the silicon carbide honeycomb ceramic carrier by negative pressure and adheres to the pore wall; the pressure value of the negative pressure driving is 10 MPa. S4. Dry and calcine to obtain the monolithic honeycomb ceramic catalyst; The particle size range of the coarse SiC particles is 25-50 μm, and the particle size range of the fine SiC particles is 0.5-10 μm. In the honeycomb ceramic carrier raw material, the mass percentage of coarse SiC particles is 72%, and the mass percentage of fine SiC particles is 15%. The silicon carbide honeycomb ceramic carrier has a mesh size of 300-600.

2. The method for preparing a monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen according to claim 1, characterized in that, The catalyst slurry also includes a binder.

3. The method for preparing a monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen according to claim 2, characterized in that, The catalyst slurry is prepared by mixing the noble metal precursor with water at a mass ratio of 3:2 to obtain a mixed solution. Based on the mass of the mixed solution as 100%, 40%wt of the composite carrier and 1%wt of the binder are added, mixed and ball-milled to obtain the catalyst slurry.

4. A monolithic honeycomb ceramic catalyst for propane partial oxidation reforming to produce hydrogen, characterized in that, It is prepared by the method described in any one of claims 1-3.

5. The application of the monolithic honeycomb ceramic catalyst as described in claim 4 in the propane partial oxidation reforming reaction for hydrogen production in SOFCs, characterized in that, At normal pressure, reaction temperature 650℃, and space velocity 5000~20000h⁻¹ -1 The reaction takes place under specific conditions.

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