Tubular ammonia fuel cell stack and preparation method of catalyst thereof

Abstract

The invention relates to a tubular ammonia fuel cell stack and a preparation method of a catalyst thereof. The tubular ammonia fuel cell stack comprises a gas inlet pipe, a gas inlet and collection cavity, a ruthenium-based catalyst, a fuel cell pipe group and a gas outlet assembly, the ruthenium-based catalyst is positioned in the inlet gas collecting cavity, and a gas outlet of the gas inlet pipe is communicated with the inlet gas collecting cavity and is positioned at one end part of the ruthenium-based catalyst; a gas inlet of the fuel cell tube group is communicated with the inlet gas collection cavity and is positioned at the other end part of the ruthenium-based catalyst; and the gas outlet assembly is mounted at a gas outlet of the fuel cell tube stack. The method has the advantages that a heating device does not need to be additionally arranged to activate the catalyst, and the ammonia cracking efficiency is improved; the carbon neutralization target is met.

Description

Technical Field

[0001] The present invention relates to a tubular ammonia fuel cell stack and a method for manufacturing a catalyst thereof. Background Art

[0002] Currently, in the prior art, the gas after ammonia thermal cracking and reforming is often passed into the fuel cell stack through an externally arranged catalyst device, which results in a relatively high energy consumption cost; the existing catalysts for cracking ammonia are basically supported on carbon black or noble metal substrates. The carbon black has fewer attachment sites as a carrier, and the overall catalytic efficiency is lower compared with that of single-walled carbon nanotubes at the same temperature. The noble metal-based catalyst has a high cost. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a tubular ammonia fuel cell stack and a method for manufacturing a catalyst thereof. The device of the present invention is an integrated device of an ammonia catalyst and a fuel cell stack. Considering that high temperature is required during the operation of the fuel cell stack, this temperature can also activate the ruthenium-based catalyst, which can be used for cracking ammonia in the fuel cell stack without the need for an additional heating device to activate the catalyst; the catalyst uses single-walled carbon nanotubes as a carrier, which can increase the specific surface area and provide more sites for the ruthenium-based catalyst to crack ammonia, thereby improving the cracking efficiency of ammonia; the device uses honeycomb ceramics as a carrier with a honeycomb-like porous structure, which can quickly conduct out the reaction heat and avoid local overheating leading to catalyst sintering; the catalyst carrier uses a carbon-based carrier instead of a noble metal substrate, and the ruthenium loading only needs to be 0.1-10 wt%, reducing the cost by more than 50% compared with the traditional Pt-based catalyst; the hydrogen by-product of the reactor can be directly used for cracking ammonia, and the fuel cell conversion rate is increased to more than 90%, meeting the goal of carbon neutrality.

[0004] To achieve the above object, the first technical solution of the present invention is implemented as follows. It is a tubular ammonia fuel cell stack, which is characterized by comprising: An inlet pipe, an inlet gas collecting chamber and a ruthenium-based catalyst; the ruthenium-based catalyst is located in the inlet gas collecting chamber, the outlet of the inlet pipe is communicated with the inlet gas collecting chamber, and the outlet of the inlet pipe is located at one end of the ruthenium-based catalyst; A fuel cell tube group; the inlet of the fuel cell tube group is communicated with the inlet gas collecting chamber, and the inlet of the fuel cell tube group is located at the other end of the ruthenium-based catalyst; and An outlet assembly; the outlet assembly is installed at the outlet of the fuel cell tube group.

[0005] In this technical solution, the outlet assembly includes an outlet gas collecting chamber and an outlet pipe; the outlet of the fuel cell tube group is communicated with the outlet gas collecting chamber, and the inlet of the outlet pipe is communicated with the outlet gas collecting chamber.

[0006] In this technical solution, the fuel cell tube group includes more than one row of fuel cell tubes. Each row of fuel cell tubes is horizontally arranged, and the distance between two adjacent fuel cell tubes on the left and right is 6 ± 2 mm. Each row of fuel cell tubes is vertically arranged, and the distance between two adjacent fuel cell tubes above and below is 4 ± 2 mm.

[0007] To achieve the above object, the second technical solution of the present invention is implemented as follows. It is a method for preparing a catalyst for a tubular ammonia fuel cell stack, which is characterized by the following steps: Step 1 The catalyst support includes single-walled carbon nanotubes or honeycomb ceramics or carbon-based supports. The support is acidified and treated with a mixed acid of concentrated nitric acid or sulfuric acid to introduce carboxyl or hydroxyl functional groups. Step 2 After Step 1, annealing treatment is carried out: high-temperature annealing in an inert atmosphere. Step 3 After dispersing the support of Step 2 in a mixed solution of ruthenium trichloride and nickel nitrate, it is dissolved in deionized water, and absolute ethanol is added. The ratio of deionized water to absolute ethanol is 70 - 95 to 5 - 30. In the above mixed solution, ultrasonic treatment is carried out for 30 min ± 5 min. Step 4 The support of Step 3 is dispersed in deionized water. For every 100 mL of deionized water, 0.1 g ± 0.05 g of SDS is added, and magnetic stirring is carried out for 6 h ± 0.5 h at a stirring temperature of 40 to 60 °C to ensure the formation of a uniform suspension. The support is added for impregnation, and the impregnated mixed solution and support are obtained. Step 5 The product of Step 4 is transferred to a rotary evaporator and evaporated under reduced pressure until it becomes a paste. The paste is placed in a vacuum drying oven. The drying temperature is 80 °C ± 5 °C, and the drying time is 12 hours ± 2 h to remove residual moisture. Step 6 The product dried in Step 5 is placed in an inert atmosphere. At a temperature of 300 °C ± 50 °C, it is calcined for 2 h ± 0.5 h. A reducing gas hydrogen is introduced, and it is heated to 400 °C at a rate of 5 °C / min ± 3 and then kept at a constant temperature for 2 h. It is cooled to room temperature in a hydrogen atmosphere, taken out and sealed and stored in a desiccator. At this time, Ru:Ni is 3 ± 0.5:1 ± 0.5, and based on the mass of the support, the total metal loading is 5 - 20 wt%.

[0008] In this technical solution, the honeycomb ceramic material is: silicon carbide or boron nitride or zirconia. The pore density of the honeycomb ceramic is 200 - 600 CPSI, and the wall thickness is 0.1 - 0.3 mm.

[0009] In this technical solution, the loading amount of the honeycomb ceramic volume-based catalyst is about 0.1 - 0.2 g / L.

[0010] The advantages of the present invention compared with the prior art are as follows: This device is an integrated device of an ammonia catalyst and an electric stack. Considering that high temperature is required during the operation of the electric stack, this temperature can also activate the catalyst. The ruthenium-based catalyst can be cracked and used in the electric stack, eliminating the need for an additional heating device to activate the catalyst; the catalyst uses single-walled carbon nanotubes as a carrier, which can increase the specific surface area and provide more sites for the ruthenium-based catalyst to crack ammonia, thereby improving the cracking efficiency of ammonia; the device uses honeycomb ceramics as a carrier with a honeycomb-like porous structure, which can quickly conduct out the reaction heat and prevent local overheating from causing catalyst sintering; the catalyst carrier uses a carbon-based carrier instead of a noble metal substrate, and the ruthenium loading only needs to be 0.1-10 wt%, reducing the cost by more than 50% compared with traditional Pt-based catalysts; the by-product hydrogen of the reactor can be directly used to crack ammonia, and the conversion rate of the fuel cell can be increased to more than 90%, meeting the goal of carbon neutrality. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic structural diagram of the present invention; Figure 2 is a top view of the present invention; Figure 3 is Figure 2 the A-A cross-sectional view of Figure 4 is Figure 3 the partial cross-sectional view of B of Figure 5 is a TEM example of the ruthenium-based catalyst Figure 1 ; Figure 6 is a TEM example of the ruthenium-based catalyst Figure 2 ; Figure 7 is a TEM example of the ruthenium-based catalyst Figure 3 . DETAILED DESCRIPTION OF THE EMBODIMENTS

[0012] The following further describes the specific embodiments of the present invention with reference to the accompanying drawings. It should be noted here that the description of these embodiments is for helping to understand the present invention, but does not constitute a limitation to the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Embodiment

[0013] As Figures 1 to 7 shown, it is a tubular ammonia fuel cell stack, including: An intake pipe 1, an intake air collecting chamber 2 and a ruthenium-based catalyst 6; the ruthenium-based catalyst 6 is located in the intake air collecting chamber 2, the outlet of the intake pipe 1 is communicated with the intake air collecting chamber 2, and the outlet of the intake pipe 1 is located at one end of the ruthenium-based catalyst 6; A fuel cell tube group; the air inlet of the fuel cell tube group is communicated with the air inlet gas collecting chamber 2 and the air inlet of the fuel cell tube group is located at the other end of the ruthenium-based catalyst 6; and An air outlet assembly; the air outlet assembly is installed at the air outlet of the fuel cell tube group.

[0014] During operation, the production method of the ruthenium-based catalyst 6 is as follows: Step 1 The catalyst carrier includes single-walled carbon nanotubes or honeycomb ceramics or carbon-based carriers. The carrier is acidified, oxidized using a mixed acid of concentrated nitric acid or sulfuric acid to introduce carboxyl or hydroxyl functional groups; Step 2 After step 1, annealing treatment is carried out: high-temperature annealing in an inert atmosphere; Step 3 After dispersing the carrier of step 2 in a mixed solution of ruthenium trichloride and nickel nitrate, it is dissolved in deionized water, and absolute ethanol is added. The ratio of deionized water to absolute ethanol is 70:30 or 80:20 or 90:10 or 95:5; in the above mixed solution, ultrasonic treatment is carried out for 25 min or 30 min or 35 min; Step 4 Disperse the carrier of step 3 in deionized water. Add 0.095 g or 0.1 g or 0.15 g of SDS to every 100 mL of deionized water, and stir magnetically for 5.5 h or 6 h or 6.5 h. The stirring temperature is 40 °C or 50 °C or 60 °C to ensure the formation of a uniform suspension. Add the carrier for impregnation. The structure of the carrier after impregnation is porous and has a high specific surface area. Such a structure is beneficial to the dispersion of the catalyst and the diffusion of reactants; Step 5 Transfer the product of step 4 to a rotary evaporator and evaporate under reduced pressure until it becomes a paste. Place the paste in a vacuum drying oven. The drying temperature is 75 °C or 80 °C or 85 °C, and the drying time is 10 h or 12 h or 14 h to remove residual moisture; Step 6 Put the product dried in step 5 into an inert atmosphere. At a temperature of 250 °C or 300 °C or 350 °C, calcine for 1.5 h or 2 h or 2.5 h. Pass in a reducing gas, hydrogen, and heat up to 400 °C at a rate of 2 °C / min or 5 °C / min or 8 °C / min, then keep the temperature constant for 2 h, cool to room temperature in a hydrogen atmosphere, take out and seal and store in a desiccator. At this time, Ru:Ni is 3 ± 0.5:1 ± 0.5. Calculated based on the mass of the carrier, the total metal loading is 5 wt% or 10 wt% or 15 wt% or 20 wt%.

[0015] In this embodiment, the gas outlet assembly includes a gas outlet collecting cavity 4 and a gas outlet pipe 5; the gas outlet of the fuel cell tube group is communicated with the gas outlet collecting cavity 4, and the gas inlet of the gas outlet pipe 5 is communicated with the gas outlet collecting cavity 4.

[0016] In this embodiment, the fuel cell tube group includes more than one row of fuel cell tubes. Each row of fuel cell tubes is horizontally arranged, and the distance between two adjacent fuel cell tubes on the left and right is 4 mm, 6 mm or 8 mm. Each row of fuel cell tubes is longitudinally arranged, and the distance between two adjacent fuel cell tubes above and below is 2 mm, 4 mm or 6 mm. Embodiment

[0017] As Figures 1 to 7 shown, it is a method for manufacturing a catalyst of a tubular ammonia fuel cell stack, which is characterized by the following steps: Step 1 The catalyst carrier includes single-walled carbon nanotubes, honeycomb ceramics or carbon-based carriers. The carrier is acidified and treated with a mixed acid of concentrated nitric acid or sulfuric acid to introduce carboxyl or hydroxyl functional groups. Step 2 After Step 1, annealing treatment is carried out: high-temperature annealing in an inert atmosphere. Step 3 After dispersing the carrier of Step 2 in a mixed solution of ruthenium trichloride and nickel nitrate, it is dissolved in deionized water, and absolute ethanol is added. The ratio of deionized water to absolute ethanol is 70:30, 80:20, 90:10 or 95:5. In the above mixed solution, ultrasonic treatment is carried out for 25 min, 30 min or 35 min. Step 4 The carrier of Step 3 is dispersed in deionized water. For every 100 mL of deionized water, 0.095 g, 0.1 g or 0.15 g of SDS is added, and magnetic stirring is carried out for 5.5 h, 6 h or 6.5 h at a stirring temperature of 40 °C, 50 °C or 60 °C to ensure the formation of a uniform suspension, and the carrier is added for impregnation, including the impregnated mixed solution and the carrier. Step 5 The product of Step 4 is transferred to a rotary evaporator and evaporated under reduced pressure to a paste state. The paste is placed in a vacuum drying oven, and the drying temperature is 75 °C, 80 °C or 85 °C, and the drying time is 10 h, 12 h or 14 h to remove residual moisture. Step 6 The product dried in Step 5 is placed in an inert atmosphere, calcined at a temperature of 250 °C, 300 °C or 350 °C for 1.5 h, 2 h or 2.5 h, and a reducing gas hydrogen is introduced. It is heated to 400 °C at a rate of 2 °C / min, 5 °C / min or 8 °C / min and then kept at a constant temperature for 2 h to ensure Ru³⁺→Ru 0 , Ni²⁺→Ni 0Completely restore, cool to room temperature in a hydrogen atmosphere, take out and seal for storage in a desiccator. At this time, Ru:Ni is 3±0.5:1±0.5. Calculated based on the mass of the carrier, the total metal loading is 5 wt% or 10 wt% or 15 wt% or 20 wt%.

[0018] When the coating thickness > 50 μm, the internal diffusion resistance causes the apparent activation energy E a to increase by > 20%.

[0019] Thermal stress failure: When the loading > 15 wt%, the CTE difference between the coating and the honeycomb ceramic easily causes microcracks (CTE mismatch > 1.5×10⁻ 6 / K), Cost - benefit: For every 0.1 g / L increase in the noble metal loading, the catalyst cost increases by about 8 - 12%.

[0020] In this embodiment, the honeycomb ceramic material: silicon carbide or boron nitride or zirconia, the pore density of the honeycomb ceramic: 200 - 600 CPSI, and the wall thickness is 0.1 - 0.3 mm.

[0021] In this embodiment, the loading of the honeycomb ceramic volume - based catalyst is about 0.1 - 0.2 g / L.

[0022] The above - mentioned embodiments of the present invention have been described in detail in conjunction with the accompanying drawings, but the present invention is not limited to the described embodiments. For those of ordinary skill in the art, various changes, modifications, substitutions, and deformations of these embodiments still fall within the protection scope of the present invention without departing from the principles and purposes of the present invention.

Claims

1. A tubular ammonia fuel cell stack, characterized in that Comprising: An intake pipe (1), an intake air collecting chamber (2), and a ruthenium-based catalyst (6); the ruthenium-based catalyst (6) is located in the intake air collecting chamber (2), the outlet of the intake pipe (1) is communicated with the intake air collecting chamber (2), and the outlet of the intake pipe (1) is located at one end of the ruthenium-based catalyst (6); A fuel cell tube group; the intake port of the fuel cell tube group is communicated with the intake air collecting chamber (2), and the intake port of the fuel cell tube group is located at the other end of the ruthenium-based catalyst (6); and An air outlet assembly; the air outlet assembly is installed at the air outlet of the fuel cell tube group.

2. The tubular ammonia fuel cell stack according to claim 1, wherein The air outlet assembly includes an air outlet collecting chamber (4) and an air outlet pipe (5); the air outlet of the fuel cell tube group is communicated with the air outlet collecting chamber (4), and the intake port of the air outlet pipe (5) is communicated with the air outlet collecting chamber (4).

3. The tubular ammonia fuel cell stack according to claim 1 or 2, characterized in that The fuel cell tube group includes one or more rows of fuel cell tubes. Each row of fuel cell tubes is horizontally arranged, and the distance between adjacent fuel cell tubes on the left and right is 6±2 mm. Each row of fuel cell tubes is vertically arranged, and the distance between adjacent fuel cell tubes above and below is 4±2 mm.

4. The method for fabricating the catalyst of the tubular ammonia fuel cell stack according to claim 1, wherein The following steps: Step 1 The catalyst support includes single-walled carbon nanotubes or honeycomb ceramics or carbon-based supports. The support is acidified by treatment with a mixed acid of concentrated nitric acid or sulfuric acid to introduce carboxyl or hydroxyl functional groups; Step 2 After Step 1, annealing treatment is carried out: high-temperature annealing in an inert atmosphere; Step 3 The support obtained in Step 2 is dispersed in a mixed solution of ruthenium trichloride and nickel nitrate, dissolved in deionized water, and anhydrous ethanol is added. The ratio of deionized water to anhydrous ethanol is 70-95 to 5-30. In the above mixed solution, ultrasonic treatment is carried out for 30 min±5 min. Step 4 The support obtained in Step 3 is dispersed in deionized water. 0.1 g±0.05 g SDS is added to every 100 mL of deionized water, and magnetic stirring is carried out for 6 h±0.5 h at a stirring temperature of 40 to 60 °C to ensure the formation of a uniform suspension. The support is added for impregnation, and the impregnated mixed solution and support are obtained; Step 5 The product obtained in Step 4 is transferred to a rotary evaporator and evaporated under reduced pressure to a paste state. The paste is placed in a vacuum drying oven. The drying temperature is 80 °C±5 °C, and the drying time is 12 hours±2 h to remove residual moisture; Step 6 The product dried in Step 5 is placed in an inert atmosphere at a temperature of 300 °C±50 °C and calcined for 2 h±0.5 h. Reducing gas hydrogen is introduced, and the temperature is raised to 400 °C at a rate of 5 °C / min±3 and then held at a constant temperature for 2 h. It is cooled to room temperature in a hydrogen atmosphere, taken out and sealed and stored in a desiccator. At this time, Ru:Ni is 3±0.5:1±0.5, and based on the mass of the support, the total metal loading is 5-20 wt%.

5. The method for fabricating a catalyst of the tubular ammonia fuel cell stack according to claim 1, wherein The honeycomb ceramic material: silicon carbide or boron nitride or zirconia. The pore density of the honeycomb ceramic: 200-600 CPSI, and the wall thickness is 0.1-0.3 mm.

6. The method for fabricating a catalyst of the tubular ammonia fuel cell stack according to claim 1, wherein The loading amount of the catalyst based on the volume of the honeycomb ceramic is about 0.1-0.2 g / L.

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