Catalytic Converter with Insulated SiC Layer
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Solution Overview
Problem
Current catalytic conversion devices for reducing NOx and oxidizing CO in diesel engine exhaust gases face inefficiencies in NOx reduction and require complex constructions, fragile, and expensive SiC materials, leading to high CO2 consumption and prolonged catalyst activation times.
Innovation Solution
A catalytic conversion device featuring a ceramic support with a thermal insulating layer and a porous SiC layer with 55-70% porosity, separating SiC from the support, and catalysts deposited via chemical vapor deposition, which maintains heat and reduces activation temperature, enabling rapid and continuous pollutant treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If SiC is used as the support material to provide good thermal conductivity for rapid temperature rise, then catalyst activation speed is improved, but the support becomes fragile and expensive
Solution Approach 1:
The device separates the SiC material from the support structure by introducing an insulating layer between them. The support can be made of robust ceramic materials while SiC is applied as a coating or layer that provides thermal conductivity where needed, thus segmenting the functions of structural support and thermal management.
Solution Approach 2:
The device uses a composite structure combining ceramic support material with SiC coating/layer separated by an insulating layer. This composite approach allows the system to benefit from the thermal conductivity of SiC while maintaining the mechanical strength and durability of ceramic support materials.
2Loss of time
If SiC is used to provide rapid temperature rise, then activation time is reduced, but heat is rapidly lost causing temperature drop during operation
Solution Approach 1:
An insulating layer is introduced as an intermediary between the SiC and the support structure. This insulating layer prevents rapid heat loss from the SiC to the support, allowing the SiC to maintain higher temperatures for longer periods, thus reducing activation time while maintaining temperature stability during operation.
Solution Approach 2:
The insulating layer is positioned specifically between the SiC and the support where heat loss occurs most rapidly. This localized insulation targets the critical heat loss pathway without affecting the overall thermal management of the catalyst, providing temperature stability where it is most needed for activation and operation.
3Ease of manufacture
If conventional catalyst deposition is used, then manufacturing is simpler, but activation temperature remains high extending activation time
Solution Approach 1:
The invention changes the physical or chemical parameters of the catalyst deposition process, such as using chemical vapor deposition (CVD) or plasma-enhanced CVD, which allow catalysts to be deposited at lower temperatures and with better dispersion. This reduces the activation temperature and consequently the activation time, while still maintaining manufacturability through established deposition techniques.
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 configuration enhances conversion efficiency, reduces catalyst activation time, minimizes CO2 emissions, and maintains catalyst activity, achieving substantial continuous treatment of exhaust gases with reduced precious metal usage and lower CO2 consumption.
Implementation Method 1
SiC offers the advantage of having good thermal conductivity which allows a rapid rise in temperature of the catalysts
Implementation Method 2
a layer of thermally insulating material on the support and a layer of porous SiC... due to the thermal insulation between the support and the SiC, the heat is stored in the SiC
Implementation Method 3
one or more catalysts on the porous SiC layer... to treat the exhaust gases, in particular to reduce NOx to N2 and oxidize CO to CO2
Implementation Method 4
the catalyst(s) are deposited by chemical vapor deposition
Data Source
Figure 1~2
AI summary
A device for catalytic conversion of NOx to N2 and/or of CO to CO2, comprising: - a ceramic support (4) having at least a plurality of channels, - a thermal barrier (6) made of thermal insulating material covering at least one part of the internal surface of the channels, - porous SiC (8) at least partially covering the thermal barrier (6) such that the SiC (8) is separated from the support by the thermal barrier (6), - one or more conversion catalysts (12) at least on the SiC.