A method for preparing porous catalysts for solid oxide fuel cells using a bio-template method and its application

Abstract

A method and application of preparing a porous catalyst for a solid oxide fuel cell by a bio-template method, which relates to preparing a solid oxide fuel cell catalyst by a bio-template method. The purpose of the present invention is to solve the problems that the electrocatalytic performance and low oxygen reduction activation energy of existing medium-temperature solid oxide fuel cells are poor and that sunflower seed shells have no commercial value, resulting in waste of resources and occupying a large amount of storage space. Method: 1. Pretreatment of sunflower seed shells; 2. Preparation of a mixed solution; 3. Immersing the pretreated sunflower seed shells in the mixed solution for a period of time, taking them out and drying them, and then calcining them to obtain a porous catalyst for a solid oxide fuel cell. The porous catalyst for a solid oxide fuel cell is used to prepare a symmetrical cell. The present invention utilizes the unique layered porous structure of sunflower seed shells and innovatively uses sunflower seed shells as a template to prepare perovskite materials to achieve a new structure, thereby improving the electrocatalytic performance of the catalyst and being suitable for industrial production.

Description

Technical Field

[0001] The invention relates to a bio-template method for preparing a solid oxide fuel cell catalyst. Background Art

[0002] Solid oxide fuel cells belong to the third generation of fuel cells. They are all-solid-state chemical power generation devices that directly convert the chemical energy stored in fuel and oxidant into electrical energy in an efficient and environmentally friendly manner at medium and high temperatures. They are recognized as the green energy technology of the 21st century. They also have the following outstanding advantages: (1) High energy efficiency. The energy conversion rate of solid oxide fuel cells reaches 65%. If combined heat and power is used, its efficiency can reach more than 80%. (2) Easy to install and maintain. Solid oxide fuel cells have a simple structure and can be installed in a modular manner. The scale and location of installation can be flexibly selected and the service life is long. The current development trend of solid oxide fuel cells is to medium temperature. The great advantage is that medium temperature can increase the selectivity of materials and reduce the cost of solid oxide fuel cells. However, as the temperature of solid oxide fuel cells decreases, the conductivity and catalytic performance of the materials will decrease. Therefore, it is currently necessary to explore solid oxide fuel cell catalysts with better catalytic activity.

[0003] Sunflower seeds are one of the most common oilseeds in the world and are widely grown worldwide. Every year, sunflower seed processing produces a large amount of low-density sunflower hulls, which are mostly of no commercial value and result in a waste of resources and take up a lot of storage space. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems that the electrocatalytic performance and low oxygen reduction activation energy of existing medium-temperature solid oxide fuel cells are poor and sunflower seed shells have no commercial value, resulting in waste of resources and occupying a large amount of storage space, and to provide a method and application of preparing porous catalysts for solid oxide fuel cells using a bio-template method.

[0005] A method for preparing a porous catalyst for a solid oxide fuel cell using a bio-template method is specifically completed by the following steps:

[0006] 1. Pretreatment of sunflower seed shells:

[0007] First, the sunflower seed shells are repeatedly washed with deionized water, then reflux-washed with an ammonia solution at 240° C. to 260° C., then soaked in a hydrochloric acid solution, and finally taken out and dried to obtain pretreated sunflower seed shells;

[0008] 2. Prepare mixed solution:

[0009] Sr(NO3)2, Bi(NO3)3·5H2O and Fe(NO3)3·9H2O were dissolved in deionized water and stirred to obtain a mixed solution;

[0010] 3. Immerse the pretreated sunflower seed shells in the mixed solution for a period of time, take them out, dry them, and then calcine them to obtain a porous catalyst for a solid oxide fuel cell.

[0011] The porous catalyst for solid oxide fuel cells is used to prepare symmetrical cells, and the specific preparation method is as follows:

[0012] The solid oxide fuel cell porous catalyst is mixed with pineol to obtain a cathode slurry; the cathode slurry is symmetrically brushed on the GDC solid electrolyte, and then placed in a high-temperature furnace for calcination to obtain a solid oxide fuel cell porous catalyst symmetrical cell.

[0013] Beneficial effects of the present invention:

[0014] 1. The present invention utilizes the unique layered porous structure of sunflower seed shells and innovatively uses sunflower seed shells as templates to prepare perovskite materials to achieve a new structure, thereby improving the electrocatalytic performance of the catalyst;

[0015] Second, the present invention adopts the impregnation method to prepare Sr 2.9 Bi 0.1 Fe2O 7-δ Porous catalysts: First, the materials obtained by this impregnation method can select suitable carriers and provide the physical structural properties required by the catalyst, such as specific surface area, pore radius, mechanical strength, thermal conductivity, etc. At the same time, the components loaded by the impregnation method are mostly distributed only on the surface of the carrier, with high utilization rate, small dosage and low cost. And precisely because of these characteristics, the impregnation method can make the sample material have a porous structure, thereby improving the electrochemical performance of porous catalysts in solid oxide fuel cells.

[0016] 3. Sr prepared by the present invention 2.9 Bi 0.1 Fe2O 7-δ The porous catalyst has a polarization resistance of 0.25Ωcm in the temperature range of 500-700℃ and in air at 700℃. 2 , the activation energy is 131.6 kJ mol -1 , compared to Sr 2.9 Bi 0.1 Fe2O 7-δ Powder catalysts and porous catalysts have better high-temperature chemical stability and electrocatalytic performance;

[0017] Fourth, the method of the present invention is simple, easy to operate, and suitable for industrial production.

[0018] The present invention can obtain a porous catalyst for a solid oxide fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Sr prepared in Example 1 2.9 Bi 0.1 Fe2O 7-δ The porous catalyst and the Sr prepared in Comparative Example 1 2.9 Bi 0.1 Fe2O 7-δ X-ray diffraction pattern of powdered catalyst;

[0020] Figure 2 Sr prepared in Comparative Example 1 2.9 Bi 0.1 Fe2O 7-δ SEM image of the powdered catalyst;

[0021] Figure 3 Sr prepared in Example 1 2.9 Bi 0.1 Fe2O 7-δ SEM images of porous catalysts;

[0022] Figure 4 For the Sr prepared in Example 1 using Comparative Example 1 2.9 Bi 0.1 Fe2O 7-δ SEM image of a symmetrical cell prepared with powder catalyst;

[0023] Figure 5 In Example 2, the Sr prepared in Example 1 is used 2.9 Bi 0.1 Fe2O 7-δ SEM image of a symmetrical cell prepared with porous catalyst;

[0024] Figure 6 Sr prepared in Example 1 2.9 Bi 0.1 Fe2O 7-δ The porous catalyst and the Sr prepared in Comparative Example 1 2.9 Bi 0.1 Fe2O 7-δ Thermogravimetric analysis of the powdered catalyst;

[0025] Figure 7 The AC impedance spectrum tested at 700℃ in air, ▲ in the figure indicates that Sr prepared in Example 1 2.9 Bi 0.1 Fe2O 7-δ Symmetrical cell of powder catalyst, ○ represents Sr prepared in Example 2 2.9 Bi 0.1 Fe2O7-δ porous catalyst symmetric cell;

[0026] Figure 8 is an Arrhenius curve diagram, where -▲- represents the Sr prepared in Example 1. 2.9 Bi 0.1 Fe2O 7-δ Symmetrical cell of powder catalyst, -○- indicates Sr prepared in Example 2 2.9 Bi 0.1 Fe2O 7-δ Porous catalyst symmetric cell. DETAILED DESCRIPTION

[0027] Specific embodiment 1: This embodiment is a method for preparing a porous catalyst for a solid oxide fuel cell using a bio-template method, which is specifically completed by the following steps:

[0028] 1. Pretreatment of sunflower seed shells:

[0029] First, the sunflower seed shells are repeatedly washed with deionized water, then reflux-washed with an ammonia solution at 240° C. to 260° C., then soaked in a hydrochloric acid solution, and finally taken out and dried to obtain pretreated sunflower seed shells;

[0030] 2. Prepare mixed solution:

[0031] Sr(NO3)2, Bi(NO3)3·5H2O and Fe(NO3)3·9H2O were dissolved in deionized water and stirred to obtain a mixed solution;

[0032] 3. Immersing the pretreated sunflower seed shells in the mixed solution for a period of time, taking them out, drying them, and then calcining them to obtain a porous catalyst for a solid oxide fuel cell.

[0033] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that: in step 1, the sunflower seed shells are first washed with deionized water 3 to 5 times; the volume fraction of the ammonia solution in step 1 is 5% to 6%; and the mass fraction of the hydrochloric acid in step 1 is 6% to 6.3%. The other steps are the same as specific embodiment 1.

[0034] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that the soaking time in the hydrochloric acid solution in step 1 is 20 to 24 hours and the drying temperature in step 1 is 60° C. to 80° C. The other steps are the same as those in specific embodiment 1 or 2.

[0035] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the volume ratio of the mass of Sr(NO3)2 and deionized water in step 2 is (1.5g-2.5g):100mL. The other steps are the same as specific embodiments 1 to 3.

[0036] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the mass ratio of Bi(NO3)3·5H2O to deionized water in step 2 is (0.1 g to 0.2 g):100 mL. The other steps are the same as specific embodiments 1 to 4.

[0037] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the mass ratio of Fe(NO₃)₃·9H₂O to deionized water in step 2 is (2g-3g):100mL; and a magnetic stirrer is used in step 2 to achieve uniform stirring. The other steps are the same as specific embodiments 1 to 5.

[0038] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the volume ratio of the pretreated sunflower seed hulls to the mixed solution in step 3 is (4 g to 5 g):100 mL; and the pretreated sunflower seed hulls are immersed in the mixed solution for 8 to 12 hours in step 3. The other steps are the same as specific embodiments 1 to 6.

[0039] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the drying temperature in step 3 is 60°C to 80°C and the drying time is 10 to 12 hours; the calcination temperature in step 3 is 1000°C to 1100°C and the calcination time is 2 to 4 hours. The other steps are the same as specific embodiments 1 to 7.

[0040] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the porous catalyst of the solid oxide fuel cell is used to prepare a symmetrical cell. The specific preparation method is as follows:

[0041] Mixing a porous solid oxide fuel cell catalyst with terpineol to produce a cathode slurry; symmetrically applying the cathode slurry to a GDC solid electrolyte, followed by calcination in a high-temperature furnace to produce a symmetrical cell containing porous solid oxide fuel cells. The remaining steps are identical to those in Specific Embodiments 1 to 8.

[0042] Specific Embodiment 10: This embodiment differs from Specific Embodiments 1 to 9 in that the mass ratio of the solid oxide fuel cell porous catalyst to the volume of terpineol is 0.1 g:(0.05 mL to 0.1 mL); and the calcination is first performed at 400°C to 500°C for 2 to 4 hours, and then at 950°C to 1000°C for 15 to 30 minutes. The other steps are the same as Specific Embodiments 1 to 9.

[0043] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0044] Example 1: Sr 2.9 Bi 0.1 Fe2O 7-δ The preparation method of the porous catalyst is specifically completed according to the following steps:

[0045] 1. Pretreatment of sunflower seed shells:

[0046] First, the sunflower seed shells were washed three times with deionized water to remove impurities, then reflux-cleaned with a 5% ammonia solution at 250°C for 14 hours, then soaked in a 6% hydrochloric acid solution for 24 hours, and finally taken out and dried at 60°C for 12 hours to obtain pretreated sunflower seed shells;

[0047] 2. Prepare mixed solution:

[0048] 1.84 g of Sr(NO3)2, 0.14 g of Bi(NO3)3·5H2O, and 2.4 g of Fe(NO3)3·9H2O were dissolved in 100 mL of deionized water and stirred with a magnetic stirrer to obtain a mixed solution;

[0049] 3. Immerse the pretreated sunflower seed shells in the mixed solution for 12 hours, take them out and dry them at 60℃ for 12 hours, and then calcine them at 1000℃ for 3 hours to obtain Sr 2.9 Bi 0.1 Fe2O 7-δ porous catalysts;

[0050] The volume ratio of the mass of the pretreated sunflower seed shells described in step 3 to the mixed solution is 4g:100mL.

[0051] Comparative Example 1: Sr 2.9 Bi 0.1 Fe2O 7-δ The preparation method of the powder catalyst is specifically completed according to the following steps:

[0052] 1. Dissolve 1.84 g of Sr(NO3)2, 0.14 g of Bi(NO3)3·5H2O, and 2.4 g of Fe(NO3)3·9H2O in 100 mL of deionized water, and stir evenly at 80°C. Then, add 4.38 g of ethylenediaminetetraacetic acid and 6.3 g of citric acid, respectively, and adjust the pH value of the solution to 7-8 after stirring. Then, stir at 80°C for 2 h to obtain a mixed solution.

[0053] 2. The mixed solution was heated at 80℃ for 2h to obtain dry gel, and the dry gel was calcined at 1100℃ for 24h to obtain Sr 2.9 Bi 0.1 Fe2O 7-δ Powder catalyst.

[0054] Figure 1 Sr prepared in Example 1 2.9 Bi 0.1 Fe2O 7-δ The porous catalyst and the Sr prepared in Comparative Example 1 2.9 Bi 0.1 Fe2O 7-δ X-ray diffraction pattern of powdered catalyst;

[0055] from Figure 1 It can be seen that the Sr prepared in Comparative Example 1 2.9 Bi 0.1 Fe2O 7-δ Powder catalyst and Sr prepared in Example 1 2.9 Bi 0.1 Fe2O 7-δ The porous catalysts are all typical Ruddlesden-Popper layered structure oxides.

[0056] Figure 2 Sr prepared in Comparative Example 1 2.9 Bi 0.1 Fe2O 7-δ SEM image of the powdered catalyst;

[0057] Figure 3 Sr prepared in Example 1 2.9 Bi 0.1 Fe2O 7-δ SEM images of porous catalysts;

[0058] The test results show that: Sr prepared in control example 1 2.9 Bi 0.1 Fe2O 7-δThe powder catalyst is composed of a large number of aggregates assembled from irregular nanoparticles, which is a typical morphology produced by the traditional sol-gel method. From the figure, it can be seen that the surface of these nanostructures is obviously very dense, with only a small amount of pores, which is not conducive to the diffusion of the catalyst and will affect its catalytic effect. 2.9 Bi 0.1 Fe2O 7-δ Porous catalysts have a clear porous structure with a large number of irregular holes and gaps on the surface, which is conducive to the diffusion of reactants into the catalyst and provides good conditions for it to serve as a biological template.

[0059] Application Example 1: Using Sr prepared in Comparative Example 1 2.9 Bi 0.1 Fe2O 7-δ The symmetrical cell prepared by powder catalyst is completed in the following steps:

[0060] 0.1 g of Sr prepared in Control Example 1 was added 2.9 Bi 0.1 Fe2O 7-δ The powdered catalyst was mixed with 0.05 mL of terpineol to obtain a cathode slurry. The cathode slurry was symmetrically brushed on a GDC solid electrolyte (purchased from Ningbo Suofer Energy Technology Co., Ltd.), and then placed in a high-temperature furnace at 950 ° C for 4 h to obtain Sr 2.9 Bi 0.1 Fe2O 7-δ Powder catalyst symmetric cell.

[0061] Application Example 2: Using the Sr prepared in Example 1 2.9 Bi 0.1 Fe2O 7-δ The porous catalyst is used to prepare a symmetrical cell, which is completed in the following steps:

[0062] 0.1 g of Sr prepared in Example 1 was added 2.9 Bi 0.1 Fe2O 7-δ The porous catalyst was mixed with 0.05 mL of terpineol to obtain a cathode slurry. The cathode slurry was symmetrically brushed on a GDC solid electrolyte (purchased from Ningbo Suofuren Energy Technology Co., Ltd.), and then placed in a high-temperature furnace, first heated at 400 ° C for 2 h to eliminate the organic binder, and then calcined in air at 950 ° C for 15 min to obtain Sr 2.9 Bi 0.1 Fe2O 7-δ Porous catalyst symmetric cell.

[0063] Figure 4 For the Sr prepared in Example 1 using Comparative Example 1 2.9 Bi0.1 Fe2O 7-δ SEM image of a symmetrical cell prepared with powder catalyst;

[0064] Figure 5 In Example 2, the Sr prepared in Example 1 is used 2.9 Bi 0.1 Fe2O 7-δ SEM image of a symmetrical cell prepared with porous catalyst;

[0065] The test results show that: 2.9 Bi 0.1 Fe2O 7-δ The powder catalyst has serious agglomeration phenomenon and only a small amount of pores, which is not conducive to the diffusion of the catalyst and will affect its catalytic effect. 2.9 Bi 0.1 Fe2O 7-δ The porous catalyst still has a porous structure on the electrode surface after calcination, which provides good conditions for the biomass template. It can not only provide more active sites for gas adsorption in active catalysis, but also promote the diffusion of reactant molecules, thereby improving its gas reaction to a certain extent.

[0066] Figure 6 Sr prepared in Example 1 2.9 Bi 0.1 Fe2O 7-δ The porous catalyst and the Sr prepared in Comparative Example 1 2.9 Bi 0.1 Fe2O 7-δ Thermogravimetric analysis of the powdered catalyst;

[0067] The test results show that: from room temperature to 300℃, the two samples will have a slight weight loss, which is attributed to dehydration and surface oxygen desorption. At about 400℃, the weight of the two samples suddenly drops, which is caused by the release of lattice oxygen and the formation of oxygen vacancies. The formation of oxygen vacancies is conducive to the transport of oxygen ions. It can be seen from the figure that Sr 2.9 Bi 0.1 Fe2O 7-δ The weight loss rate of the porous catalyst was 2.95%, and Sr 2.9 Bi 0.1 Fe2O 7-δ The weight loss rate of the powder catalyst is 1.42%, and the weight loss rate of the porous catalyst is greater than that of the powder catalyst, indicating that the porous catalyst has a higher oxygen vacancy concentration at high temperature, which is the reason for its enhanced oxygen reduction activity.

[0068] Figure 7 The AC impedance spectrum tested at 700℃ in air, ▲ in the figure indicates that Sr prepared in Example 1 2.9Bi 0.1 Fe2O 7-δ Symmetrical cell of powder catalyst, ○ represents Sr prepared in Example 2 2.9 Bi 0.1 Fe2O 7-δ porous catalyst symmetric cell;

[0069] The test results show that the Sr prepared in Example 2 2.9 Bi 0.1 Fe2O 7-δ The polarization resistance of the symmetrical cell of the porous catalyst is 0.25Ωcm 2 , which is lower than that of Sr prepared in Example 1. 2.9 Bi 0.1 Fe2O 7-δ Polarization resistance of the powder catalyst (0.37Ωcm 2 ), which shows that Sr 2.9 Bi 0.1 Fe2O 7-δ Porous catalysts can improve the electrocatalytic activity of solid oxide fuel cell catalysts.

[0070] Figure 8 is an Arrhenius curve diagram, where -▲- represents the Sr prepared in Example 1. 2.9 Bi 0.1 Fe2O 7-δ Symmetrical cell of powder catalyst, -○- indicates Sr prepared in Example 2 2.9 Bi 0.1 Fe2O 7-δ Porous catalyst symmetric cell.

[0071] The test results show that the Sr prepared in Example 2 2.9 Bi 0.1 Fe2O 7-δ The activation energy of the porous catalyst symmetric cell is 131.6 kJ mol -1 , which is lower than that of Sr prepared in Example 1. 2.9 Bi 0.1 Fe2O 7-δ The activation energy of the powder catalyst is 2(147.4kJmol -1 ), the activation energy of the electrode is significantly reduced, indicating that the electrocatalytic performance of the oxygen reduction reaction is enhanced.

Claims

1. A method for preparing a porous catalyst for a solid oxide fuel cell using a bio-template method, characterized in that The method is specifically completed according to the following steps:

1. Pretreatment of sunflower seed shells: First, the sunflower seed shells are repeatedly washed with deionized water, then reflux-washed with an ammonia solution at 240° C. to 260° C., then soaked in a hydrochloric acid solution, and finally taken out and dried to obtain pretreated sunflower seed shells; 2. Prepare mixed solution: Sr(NO3)2, Bi(NO3)3·5H2O and Fe(NO3)3·9H2O were dissolved in deionized water and stirred to obtain a mixed solution; The mass ratio of Sr(NO3)2 described in step 2 to the volume ratio of deionized water is (1.5g-2.5g):100mL; The mass ratio of Bi(NO3)3·5H2O to deionized water in step 2 is (0.1g-0.2g):100mL; The mass ratio of Fe(NO3)3·9H2O to deionized water in step 2 is (2g-3g):100mL; in step 2, a magnetic stirrer is used to stir the mixture evenly; 3. Immersing the pretreated sunflower seed shells in the mixed solution for 8 to 12 hours, taking them out and drying them, and then calcining them at 1000 to 1100 degrees Celsius for 2 to 4 hours to obtain a porous catalyst for a solid oxide fuel cell; The volume ratio of the mass of the pretreated sunflower seed shells described in step 3 to the mixed solution is (4g-5g):100mL.

2. The method for preparing a porous catalyst for a solid oxide fuel cell using a bio-template method according to claim 1, characterized in that In step one, the sunflower seed shells are first washed with deionized water 3 to 5 times; the volume fraction of the ammonia solution in step one is 5% to 6%; and the mass fraction of the hydrochloric acid in step one is 6% to 6.3%.

3. The method for preparing a porous catalyst for a solid oxide fuel cell using a bio-template method according to claim 1, characterized in that The soaking time in the hydrochloric acid solution in step 1 is 20 hours to 24 hours; the drying temperature in step 1 is 60° C. to 80° C.

4. The method for preparing a porous catalyst for solid oxide fuel cells using a bio-template method according to claim 1, characterized in that The drying temperature in step 3 is 60° C. to 80° C., and the drying time is 10 h to 12 h.

5. Application of the porous catalyst for solid oxide fuel cells prepared by the preparation method according to claim 1, characterized in that The porous catalyst of the solid oxide fuel cell is used to prepare a symmetrical cell, and the specific preparation method is as follows: The solid oxide fuel cell porous catalyst is mixed with pineol to obtain a cathode slurry; the cathode slurry is symmetrically brushed on the GDC solid electrolyte, and then placed in a high-temperature furnace for calcination to obtain a solid oxide fuel cell porous catalyst symmetrical cell.

6. The use of the porous catalyst for solid oxide fuel cells according to claim 5, characterized in that The mass ratio of the solid oxide fuel cell porous catalyst to the volume ratio of terpineol is 0.1g:(0.05mL-0.1mL); the calcination is first calcined at 400℃-500℃ for 2h-4h, and then calcined at 950℃-1000℃ for 15min-30min.

Images