Spray Pyrolysis Catalyst Preparation for Carbon Nanotube Synthesis
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Solution Overview
Problem
Existing methods for preparing catalyst compositions for carbon nanotube synthesis via spray pyrolysis face challenges such as non-uniform dispersion of metal catalysts on support materials and nozzle clogging due to solid oxide supports or ammonia water reactions, limiting high-yield commercial production.
Innovation Solution
A process involving dissolving multi-component metal precursors in de-ionized water, spraying the solution into a high-temperature reactor by gas atomization, and forming catalyst composition powder through pyrolysis at controlled temperatures and pressures, using Fe or Co as main catalysts with Al and optional co-catalysts like Ni, Cu, and Mg as support, to achieve high yields and low apparent density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spray pyrolysis method is used to prepare catalyst composition, then high production yield of carbon nanotube can be achieved, but nozzle clogging occurs due to solid oxide supports or ammonia water reactions
Solution Approach 1:
The patent extracts and removes the problematic solid oxide support material from the spray solution formulation. Instead of using solid oxide supports that cause nozzle clogging, the invention uses soluble salt precursors (nitrates, sulfates, or halides) of metal catalysts and support materials that remain in solution during spraying, eliminating the clogging issue while maintaining high productivity through subsequent pyrolysis conversion.
Solution Approach 2:
The patent changes the chemical state of support materials from solid oxide form to soluble salt form (nitrates, sulfates, or halides). This parameter change allows the support materials to be dissolved in water or alcohol-based solutions, enabling smooth spray delivery without nozzle clogging, while the pyrolysis process converts these salts into the desired oxide support structures in-situ.
2Quantity of substance
If solid oxide support is used in spray pyrolysis, then catalyst support function is provided, but non-uniform dispersion of metal catalysts on support material occurs
Solution Approach 1:
The patent merges the catalyst metal precursors and support material precursors into a single homogeneous liquid solution containing all necessary components. By dissolving both metal catalyst salts and support material salts in the same solvent system, the invention ensures uniform distribution of all components before pyrolysis, achieving homogeneous catalyst dispersion on the support material after thermal treatment.
Solution Approach 2:
The patent introduces a liquid solvent (water or alcohol-based solution) as an intermediary medium that carries both catalyst metal precursors and support material precursors uniformly. This liquid intermediary enables homogeneous mixing and distribution of all components, which would be difficult to achieve with solid-solid mixing, and ensures uniform deposition during the spray pyrolysis process.
3Ease of manufacture
If ammonia water is used as solvent for catalyst preparation, then metal precursors can be dissolved, but nozzle clogging occurs due to chemical reactions
Solution Approach 1:
The patent replaces ammonia water with more stable and less reactive solvents such as water or alcohol-based solutions. These alternative solvents provide sufficient dissolution capability for metal precursor salts without causing the problematic chemical reactions that lead to nozzle clogging. The solvents are simple, inexpensive, and do not require complex handling or create unwanted byproducts.
Solution Approach 2:
The patent converts the potential harm of using reactive solvents like ammonia water into a benefit by selecting solvents that provide adequate dissolution without causing harmful reactions. The chosen solvents (water or alcohols) offer a balance between dissolution capability and chemical stability, preventing precipitation and clogging while still enabling effective precursor delivery to the substrate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables uniform catalyst dispersion, prevents nozzle clogging, and achieves high production yields of carbon nanotubes with low apparent density, facilitating economical mass production and wide-ranging applications.
Implementation Method 1
spraying obtained catalytic metal precursor solution into the high temperature reactor by gas atomization method
Implementation Method 2
forming the catalyst composition powder by pyrolysis of gas atomized material
Data Source
AI summary
The present invention relates to a process for preparing catalyst composition for the synthesis of carbon nanotube with high yields using the spray pyrolysis method. More particularly, this invention relates to a process for preparing catalyst composition for the synthesis of carbon nanotube comprising the steps of i) dissolving multi-component metal precursors of catalyst composition in de-ionized water; ii) spraying obtained catalytic metal precursor solution into the high temperature reactor by gas atomization method; iii) forming the catalyst composition powder by pyrolysis of gas atomized material; and iv) obtaining the catalyst composition powder, wherein said catalyst composition comprises i) main catalyst selected from Fe or Co, ii) Al, iii) optional co-catalyst at least one selected from Ni, Cu, Sn, Mo, Cr, Mn, V, W, Ti, Si, Zr or Y, iv) inactive support of Mg. Further, the catalyst composition prepared by this invention has a very low apparent density of 0.01˜0.50 g/ml as well as the catalyst composition affords high production yield (1,000˜1,800%) of carbon nanotube.