SiC Exhaust Catalyst Intermediate Layer for PGM Migration Control
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Solution Overview
Problem
Platinum group metal migration from the catalyst layer to the base material during high temperature duration leads to a decrease in exhaust gas purification performance and deteriorates the high temperature durability of electrically heated catalysts.
Innovation Solution
Incorporating an intermediate layer between the base material and the catalyst layer, with a specific thickness and surface area, to act as a physical barrier and suppress platinum group metal migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If an electrically heated catalyst uses a base material containing SiC and a catalyst layer containing platinum group metal, then the catalyst can be activated quickly by electric heating, but the platinum group metal migrates to the base material during high temperature duration
Solution Approach 1:
An intermediate layer is introduced between the base material and the catalyst layer to act as a barrier that prevents platinum group metal migration while allowing the electric heating function to operate effectively. This intermediary layer resolves the contradiction by blocking the harmful migration path without interfering with the desired electric heating and catalysis functions.
Solution Approach 2:
The catalyst structure is divided into three distinct layers: base material, intermediate layer, and catalyst layer. This segmentation separates the functions of each layer, with the intermediate layer specifically dedicated to preventing metal migration, thereby maintaining both quick activation capability and high temperature durability.
2Reliability
If the intermediate layer thickness is increased to suppress platinum group metal migration, then the barrier function is enhanced, but the specific surface area decreases
Solution Approach 1:
The thickness of the intermediate layer is optimized within a specific range (5-50 μm) to achieve the desired balance. By controlling this parameter, the layer provides sufficient barrier function to prevent platinum group metal migration while maintaining adequate surface area for heat and mass transfer, thus resolving the contradiction between migration resistance and surface area.
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 intermediate layer effectively prevents platinum group metal migration, enhancing the high temperature durability and purification performance of the exhaust gas catalyst.
Implementation Method 1
The intermediate layer has an appropriate thickness and an appropriate specific surface area, thereby exhibiting a high function as a physical barrier that obstructs platinum group metal migration
Implementation Method 2
the base material contains SiC serving as a resistance heating element
Data Source
AI summary
The present invention provides an exhaust gas purification catalyst in which platinum group metal migration from a catalyst layer to a base material during high temperature duration is suppressed. The exhaust gas purification catalyst disclosed herein includes a base material, a catalyst layer, and an intermediate layer arranged between the base material and the catalyst layer. The base material contains SiC. The catalyst layer contains a platinum group metal as a catalyst component. The intermediate layer contains substantially no platinum group metal. A product of a thickness of the intermediate layer (μm) and a specific surface area (m2/g) of the intermediate layer is 1100 or more.