Wall-Flow Catalyst with Localized Catalytic Layers
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Solution Overview
Problem
Conventional wall-flow exhaust gas purification catalysts experience excessive pressure loss due to the location of catalytic layers, which affects their purification efficiency.
Innovation Solution
The catalyst design features a first catalytic layer predominantly located within the partition walls and a second catalytic layer on the surface of the partition walls, with specific length and thickness configurations to minimize pressure loss while maintaining high purification performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second catalytic layer is formed entirely over the first catalytic layer covering the surface of entrance cells, then exhaust gas purification efficiency is improved, but pressure loss increases excessively
Solution Approach 1:
The patent applies local quality by forming the second catalytic layer selectively only in specific regions (exit cells and predetermined axial positions) rather than uniformly across the entire partition wall surface. This localized approach ensures catalytic activity where exhaust gas flows through exit cells while avoiding excessive pressure loss that would result from complete surface coverage.
Solution Approach 2:
The patent implements partial action by forming the second catalytic layer only in predetermined axial positions and specific regions of the partition walls, rather than covering the entire surface. This partial coverage is sufficient to maintain purification efficiency while significantly reducing the pressure loss associated with complete coverage.
2Area of stationary object
If the catalytic layer is formed throughout the entire partition wall surface, then contact area with exhaust gas is increased, but flow resistance increases
Solution Approach 1:
The patent applies local quality by concentrating the second catalytic layer in specific regions where exhaust gas flows through exit cells, rather than distributing it uniformly across the entire partition wall surface. This localized placement optimizes the contact area between catalytic layer and exhaust gas while minimizing flow resistance.
Solution Approach 2:
The patent utilizes the axial dimension of the partition walls to strategically position the second catalytic layer at predetermined axial positions. This dimensional approach allows optimization of catalytic contact area while controlling flow resistance by placing catalysts where they are most effective in the exhaust flow path.
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 reduces pressure loss while maintaining or enhancing exhaust gas purification efficiency, as the first catalytic layer effectively purifies exhaust gas within the partition walls and the second layer efficiently contacts exhaust gas flowing through exit cells.
Implementation Method 1
When the exhaust is in contact with the catalytic layer (catalytic metal), the exhaust components are purified (detoxified).
Implementation Method 2
Exhaust gas emitted from the internal combustion system flows via the exhaust inlet-side ends into the entrance cells, passes through micro pores of the porous partition walls, and flows out of the exhaust outlet-side ends of the exit cells.
Data Source
Figure 1~2
Figure 3~4
AI summary
This invention provides an exhaust gas purification catalyst having an excellent exhaust gas purification ability while reducing the increase in pressure loss. Exhaust gas purification catalyst 10 comprises entrance cell 24, exit cell 25, and a wall-flow substrate having partition wall 26 to separate these cell, a catalytic layer 261 formed from exhaust inlet-side ends 24a in the extending direction in sections of the interior of partition wall 26 facing entrance cell 24, and a catalytic layer 262 formed on the surface of partition wall 26 facing exit cell 25 from exhaust outlet-side ends 25a in the extending direction of partition wall 26, having a length shorter than the entire partition wall length Lw.