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KR-20260066022-A - Method for manufacturing ammonia thermal decomposition catalyst with a nanofiber structure

KR20260066022AKR 20260066022 AKR20260066022 AKR 20260066022AKR-20260066022-A

Abstract

The present invention relates to a method for manufacturing an ammonia pyrolysis catalyst, wherein a nano metal fiber carrier sheet having excellent specific surface area and low back pressure with uniform pores is manufactured using electrospinning, and a nano catalyst fiber with a concentric structure is electrospun onto the substrate using a 3-axis electrospinning nozzle, wherein the catalyst support having excellent thermal durability is the central layer, a main catalyst having excellent ammonia pyrolysis performance is the middle layer, and a co-catalyst improving performance and durability is the outer layer, thereby manufacturing a catalyst with a continuous 1D nanofiber structure having excellent durability and performance.

Inventors

  • 손건석
  • 윤혜쟁

Assignees

  • 주식회사 아이디어뱅크

Dates

Publication Date
20260512
Application Date
20260423

Claims (7)

  1. In the manufacture of ammonia decomposition catalysts, (a) a step of preparing an electrospinning solution comprising a polymer for matching electrospinning conditions such as viscosity and electrical conductivity, a solvent for dissolving the polymer, and a carrier precursor; (b) an electrospinning step in which a direct current high voltage is applied to the spinning solution prepared above to spin a carrier precursor with a diameter of tens of nanometers, and the spun fibers are aligned and densely collected in a designed area of a collecting plate by electric field distortion using an insulator; (c) A step of calcining the collected carrier precursor sheet in an air atmosphere; (d) a step of preparing a support electrospinning solution comprising a polymer for matching electrospinning conditions such as viscosity and electrical conductivity, a solvent for dissolving the polymer, and a catalyst support precursor; (e) a step of preparing a main catalyst electrospinning solution comprising a polymer for matching electrospinning conditions such as viscosity and electrical conductivity, a solvent for dissolving the polymer, and a main catalyst precursor; (f) a step of preparing a co-catalyst electrospinning solution comprising a polymer for matching electrospinning conditions such as viscosity and electrical conductivity, a solvent for dissolving the polymer, and a co-catalyst precursor; (g) A triaxial electrospinning step in which each independently controllable electrospinning syringe filled with each of the above-prepared spinning solutions is connected to a triaxial electrospinning nozzle, and a DC high voltage is applied to spin nanofibers in which a support precursor layer is arranged in a concentric structure in the center of the cross-section, a catalyst precursor layer in the middle, and a co-catalyst precursor layer on the outer edge, and the spun fibers are densely collected by aligning them to a designed area of the above-prepared calcined nano metal fiber carrier by electric field distortion using an insulator; (h) a step of calcining the triaxially spun support, main catalyst, and co-catalyst precursor sheets on the nano metal fiber carrier; (i) a step of continuously reducing a nano metal fiber support, a catalyst, and a co-catalyst in a reducing atmosphere; characterized by a method for preparing an ammonia pyrolysis catalyst
  2. In paragraph 1, A process for manufacturing an ammonia pyrolysis catalyst comprising: a process of preparing a homogeneous support electrospinning solution by dissolving 7 wt% to 9 wt% of PVP (polyvinylpyrrolidone) relative to DMF in a dimethylformamide (DMF) solvent while stirring at room temperature for at least 6 hours as a polymer for supporting material transport and controlling electrospinning viscosity and electrical conductivity, followed by adding 3 wt% to 35 wt% of gamma alumina powder or lanthanum-doped gamma alumina and stirring for at least 10 hours.
  3. In paragraph 1, A process for manufacturing an ammonia pyrolysis catalyst comprising the step of preparing a homogeneous main catalyst electrospinning solution by dissolving polyvinylpyrrolidone (PVP) at a concentration of 6 wt% to 12 wt% relative to DMF in a dimethylformamide (DMF) solvent while stirring at room temperature for at least 6 hours as a polymer for transporting the main catalyst precursor and controlling electrospinning viscosity and electrical conductivity, followed by adding 10 wt% to 40 wt% of nickel nitrate hydroxide and stirring for at least 5 hours.
  4. A process for manufacturing an ammonia pyrolysis catalyst comprising: a process of preparing a homogeneous co-catalyst electrospinning solution by dissolving polyvinylpyrrolidone (PVP) in an amount of 4 wt% to 10 wt% relative to DMF in a dimethylformamide (DMF) solvent as a polymer for transporting a co-catalyst precursor and controlling electrospinning viscosity and electrical conductivity, while stirring at room temperature for at least 6 hours; adding magnesium nitrate in an amount of 1 wt% to 8 wt% relative to the support and stirring for at least 6 hours; adding iron nitrate in an amount of 5 wt% to 40 wt% relative to the main catalyst and stirring for at least 6 hours; and adding ceria nitrate in an amount of 0.1 wt% to 3 wt% relative to the main catalyst and stirring for at least 10 hours.
  5. In paragraph 1, Connect the support precursor electrospinning solution to the center tube of the 3-axis electrospinning nozzle, and Connect the main catalyst precursor electrospinning solution to the intermediate tube of the 3-axis electrospinning nozzle, and By connecting a co-catalyst precursor electrospinning solution to the outer tube of a 3-axis electrospinning nozzle, A process for manufacturing an ammonia pyrolysis catalyst comprising the electrospinning of nanofibers in which a support layer is positioned in the center, a main catalyst layer in the middle, and a co-catalyst layer on the outer edge in a concentric structure.
  6. In paragraph 4, Potassium nitrate is used to replace 0% to 100% of magnesium nitrate, and Calcium nitrate is additionally added at 0.1 wt% to 1 wt% relative to the support material, Process for preparing a co-catalyst electrospinning solution that replaces 0% to 100% of ceria nitrate with zirconium nitrate
  7. In paragraph 3, A process for preparing a main catalyst electrospinning solution using distilled water as a solvent, PVA (polyvinyl alcohol) as a nickel precursor carrier polymer at 10 to 14 wt% relative to distilled water, and nickel acetate as a nickel precursor at 8 to 34 wt%.

Description

Method for manufacturing ammonia thermal decomposition catalyst with a nanofiber structure The present invention relates to a method for manufacturing an ammonia pyrolysis catalyst, wherein a nano metal fiber carrier sheet having excellent specific surface area and low back pressure with uniform pores is manufactured using electrospinning, and a nano catalyst fiber with a concentric structure is electrospun onto the substrate using a 3-axis electrospinning nozzle, wherein the catalyst support having excellent thermal durability is the central layer, a main catalyst having excellent ammonia pyrolysis performance is the middle layer, and a co-catalyst improving performance and durability is the outer layer, thereby manufacturing a catalyst with a continuous 1D nanofiber structure having excellent durability and performance. As hydrogen energy begins to establish itself as a means to replace fossil fuels, ammonia is attracting attention as a medium for storing and transporting hydrogen due to its excellent storability and transportability, as well as the well-established global infrastructure already in place. Although ammonia is sometimes used as an energy source by directly burning it in internal combustion engines, its widespread industrial application is limited due to the slow flame propagation speed and nitrogen oxide emissions during combustion. Consequently, an industrial structure is widely adopted in which ammonia is decomposed into hydrogen for use in hydrogen-fueled energy sources, such as fuel cells. Technologies for producing hydrogen by decomposing ammonia include plasma, photocatalysis, electrochemistry, membrane, and pyrolysis. Among these, pyrolysis technology is dominant due to its high technological maturity and suitability for continuous processes ranging from small to large scales, and in particular, methods that reduce energy consumption and increase efficiency by using catalysts are being adopted as a priority. Ruthenium (Ru), a transition metal belonging to the platinum group, is a catalyst that can achieve a decomposition rate of nearly 100% even at low temperatures as an ammonia pyrolysis catalyst. However, it is a precious metal and a rare material, so it is very expensive, and in the region exceeding 500 degrees Celsius, the durability decreases rapidly due to the accelerated sintering of ruthenium catalyst particles, so it is evaluated as not suitable for long-term/large-scale operation. Nickel (Ni) is a transition metal abundant in the Earth's crust with excellent ammonia decomposition capabilities. Although it operates at higher temperatures than ruthenium, it is recognized as a proven material for catalysts with the highest potential for industrialization due to its superior durability and stability; however, it is still necessary to increase the decomposition rate at lower temperatures and improve long-term operational durability. Methods for manufacturing catalysts include impregnation, precipitation-deposition, and coprecipitation methods, which involve coating nano-catalyst particles as a thin film on felt, mesh, or honeycomb structures. However, high-temperature sintering processes of over 1000 degrees Celsius are still required, and problems remain regarding interfacial delamination stemming from the limitations of controlling the interface between the catalyst particles and the support, as well as performance degradation due to the sintering and growth of catalyst particles at high temperatures. Figure 1 is a flowchart of the ammonia pyrolysis catalyst manufacturing process of the present invention. Figure 2 is a schematic diagram of the ammonia pyrolysis catalyst manufacturing process of the present invention. FIG. 3 is a schematic diagram of the 3-axis electrospinning nozzle and a simulation of the electrospinning fiber of the present invention. The following description merely illustrates the principles of the present invention. Therefore, those skilled in the art may invent various devices that embody the principles of the present invention and are included within the concept and scope of the present invention, even though they are not explicitly described or illustrated in this specification. Furthermore, all conditional terms and embodiments listed in this specification are, in principle, explicitly intended only for the purpose of enabling an understanding of the concept of the present invention and should be understood not as being limited to the embodiments and conditions specifically listed as such. Furthermore, it should be understood that all detailed descriptions enumerating specific embodiments, as well as the principles, aspects, and embodiments of the present invention, are intended to include structural and functional equivalents thereof. In addition, it should be understood that such equivalents include not only currently known equivalents but also equivalents to be developed in the future, that is, all elements invented to perform the same function reg