Multi-Metal Catalyst for Controlled CNT Morphology
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Solution Overview
Problem
Existing methods for producing carbon nanotubes (CNT) with controlled morphology, such as bulk density and tube diameter, face challenges in scalability and yield, particularly with binary oxide supported multi-metal catalysts, which are not viable for large-scale production with tunable morphology.
Innovation Solution
A catalyst composition represented by the formula [(MxMny)Moz] [binary metal oxide](100−(x+y+z)), where M is a Group VIII metal, structural promoters like manganese or molybdenum are used in combination with binary metal oxides like magnesium, calcium, or silicon as textural promoters, prepared through precipitation methods, and applied in a CVD process to achieve controlled CNT production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pre-synthesized nano-silicon powder is used as oxide support, then CNT morphology control is improved, but catalyst preparation complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by pre-synthesizing nano-silicon powder with controlled particle size before using it as oxide support in the catalyst. This pre-preparation of the support material with specific morphological properties enables better control over the final CNT morphology, while the complex preparation steps are performed in advance during catalyst manufacturing rather than during the CNT production process itself.
2Ease of manufacture
If conventional catalyst preparation methods are used, then ease of manufacture is improved, but CNT yield is reduced
Solution Approach 1:
The patent applies parameter changes by modifying the catalyst composition parameters, specifically incorporating pre-synthesized nano-silicon powder with controlled particle size as the oxide support. This parameter change in the support material's physical properties (particle size, morphology) enhances the catalyst's ability to produce high yields of CNT (2400-3300%) while maintaining feasibility for scale-up, resolving the contradiction between ease of manufacture and productivity.
3Reliability
If binary oxide supported multi-metal catalysts are used, then catalytic activity is improved, but scalability is reduced
Solution Approach 1:
The patent applies composite materials by creating a multi-component catalyst system that combines Group VIII metals (Fe, Co, Ni) with pre-synthesized nano-silicon powder as oxide support. This composite structure integrates the high catalytic activity of multi-metal combinations with the controlled morphology properties of nano-silicon, achieving both high catalytic performance (2400-3300% yield) and scalability for large-scale production.
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
The solution yields CNT with bulk density ranging from 0.01 to 0.2 g/cc and tube diameters between 5 to 30 nm, achieving purity greater than 95 wt%, suitable for various applications and scalable for large-scale production with tailored morphology.
Implementation Method 1
catalytic chemical vapor deposition (CVD) attempt to produce the CNT in the mass scale
Implementation Method 2
CVD is considered to be the promising method due to low cost, ease of operation and tunable CNT growth control
Implementation Method 3
prepared through precipitation methods
Data Source
AI summary
A catalyst composition for the production of carbon nanotubes (CNT) with controlled morphology is disclosed. The catalyst is represented by formula [(MxMny)Moz][binary metal oxide](100−(x+y+z)), where x is in the range 1 to 25 wt %, y is in the range 0.1 to 20 wt %, and z is in the range 0.0 to 10 wt %. Further M represents either iron or cobalt or nickel along with manganese and molybdenum supported on binary metal oxides comprising of boron, magnesium, aluminum, silicon, calcium, barium, and combination thereof. The CNT morphology can be tailor-made with the plural combination of nature of metal and promoters in appropriate proportions. The process yields the CNT with bulk density in the range of 0.01 to 0.20 g/cc, diameter in the range of 5 to 30 nm and purity greater than 95 wt %.