Carbon Nanotube Aggregate Bulk Density Control
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Solution Overview
Problem
Current methods for producing carbon nanotubes face challenges in controlling their diameter and length for industrial applications, with limited scalability and high production costs, and existing catalysts struggle to achieve a consistent bulk density suitable for composite materials.
Innovation Solution
A method involving calcining aluminum hydroxide to form a support, supporting a catalytic metal precursor, and controlling calcination temperatures and reaction times to produce a carbon nanotube aggregate with a bulk density of 10 kg/m3 or more, using a supported catalyst with Co and V, and adjusting the organic acid ratio to enhance dispersibility and miscibility with polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chemical vapor deposition using a substrate-supported catalyst is used, then carbon nanotubes can be produced, but the efficiency in utilizing reactor space is very low
Solution Approach 1:
The patent replaces the conventional substrate-supported catalyst mechanical system with a fluidized bed reactor system where catalyst particles are suspended and fluidized by gas flow. This substitution allows three-dimensional utilization of reactor space, transforming the production from a surface-limited process to a volume-efficient process, thereby resolving the contradiction between productivity and device complexity.
Solution Approach 2:
The patent changes the physical state and flow parameters of the catalyst from stationary substrate-bound to fluidized particle form. By controlling gas flow rate, particle size distribution, and fluidization velocity, the system achieves optimal reactor space utilization while maintaining high carbon nanotube production efficiency, thus resolving the technical contradiction.
2Reliability
If arc discharge or laser ablation is used to produce carbon nanotubes, then high quality carbon nanotubes can be obtained, but the production cost is high and mass production is not appropriate
Solution Approach 1:
The patent employs disposable catalyst particles in a fluidized bed reactor that can be continuously replenished. These catalyst particles, while individually short-lived, enable continuous mass production when supplied in bulk. This approach replaces the expensive and low-throughput arc discharge and laser ablation methods, achieving both cost-effectiveness and high productivity while maintaining carbon nanotube quality.
Solution Approach 2:
The patent implements continuous carbon nanotube production through a fluidized bed reactor where catalyst particles continuously generate carbon nanotubes as gas flows through the bed. This continuous process, as opposed to batch processes in arc discharge or laser ablation, enables mass production while maintaining consistent quality, thereby resolving the contradiction between reliability and productivity.
3Ease of operation
If carbon nanotubes are produced with small diameter for bundle type structure, then dispersibility in polymers is improved, but controlling diameter and length to industrially applicable dimensions is limited
Solution Approach 1:
The patent utilizes parameter changes in catalyst particle size, gas flow rate, and reaction temperature to control the diameter and length of carbon nanotubes. By optimizing these parameters, the process produces bundle-type structures with controlled dimensions that maintain small enough diameter for good polymer dispersibility while achieving industrially applicable length specifications, thus resolving the contradiction between ease of operation and manufacturing precision.
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 the production of a bundle-type carbon nanotube aggregate with controlled bulk density, facilitating its use in composite materials with improved physical properties, suitable for various applications such as energy materials, semiconductors, and pharmaceuticals.
Implementation Method 1
bringing the supported catalyst into contact with a carbon-containing compound under heating to react with each other
Implementation Method 2
calcining aluminum hydroxide at a primary calcination temperature of 300°C to 500°C to form a support comprising 30 wt% or more of AIO(OH)
Data Source
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AI summary
The present invention relates to a method for producing a carbon nanotube aggregate whose bulk density is easily controllable. Therefore, the present invention provides a carbon nanotube aggregate suitable for use in various fields.