Flaky Nanocrystal Composite to Prevent Catalyst Agglomeration
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Solution Overview
Problem
Nanoparticles used in catalytic converters agglomerate at high temperatures, reducing the surface area and catalytic activity, leading to inefficient conversion of harmful gases like CO and NO in automobile exhaust.
Innovation Solution
A nanocrystal composite comprising a connected aggregate of flaky nanocrystal fragments with gaps between them, supporting nanoparticles of a different metal oxide, such as cerium oxide, to maintain high catalytic activity by acting as a buffer for oxygen release and preventing agglomeration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nanoparticles are used to increase surface area and enhance catalytic activity, then catalytic activity is improved, but nanoparticles agglomerate and coarsen at high temperatures causing surface area reduction
Solution Approach 1:
The patent introduces a mediator substance that forms a protective layer between the nanoparticles and each other, preventing direct contact and agglomeration. This intermediary layer allows the nanoparticles to maintain their dispersed state and high surface area even at high temperatures, while still permitting catalytic reactions to occur.
Solution Approach 2:
The patent creates a composite structure combining nanoparticles with a supporting matrix or coating material. This composite approach allows the nanoparticles to retain their high surface area and catalytic activity while the supporting material provides thermal stability and prevents particle coarsening at elevated temperatures.
2Stability of the object's composition
If nanoparticles are dispersed on a particulate base to prevent agglomeration, then particle dispersion is improved, but nanoparticles still move and diffuse into coarse particles at high temperature
Solution Approach 1:
The patent employs a thin film or shell structure that envelops the nanoparticles or forms a surface layer on the particulate base. This flexible yet stable film prevents nanoparticle migration and diffusion at high temperatures while maintaining the dispersed configuration and allowing catalytic functionality.
Solution Approach 2:
The patent modifies physical or chemical parameters of the supporting base or nanoparticle interface, such as surface energy, thermal expansion coefficients, or chemical bonding characteristics, to create stronger anchoring effects that prevent nanoparticle movement and diffusion at high operating temperatures.
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 nanocrystal composite maintains high catalytic activity even after repeated exposure to high temperatures, ensuring efficient conversion of CO and NO into harmless gases like CO2 and N2.
Implementation Method 1
the nanoparticles act as a buffer to maintain catalytic activity by controlling the surface area and preventing particle agglomeration
Implementation Method 2
the nanocrystal composite maintains high catalytic activity and structural integrity during repeated exposure to high temperatures, enhancing the efficiency of harmful gas purification by preventing surface area reduction and particle coarsening
Data Source
AI summary
The present disclosure relates to a nanocrystal composite includes a connected aggregate including a plurality of nanocrystal fragments connected to one another, each nanocrystal fragment having a main surface and an end surface, and nanoparticles supported on the connected aggregate. The plurality of nanocrystal fragments each have a flaky shape; the plurality of nanocrystal fragments have gaps between the main surfaces; and the gaps G are arranged so as to open to the outside of the connected aggregate. The nanoparticles have a metallic element different from that of the plurality of nanocrystal fragments; and a proportion of a visual field area of the nanoparticles with respect to a visual field area of the plurality of nanocrystal fragments is 2% or more and 50% or less.