Wall-Flow Catalyst Coating Strategy for Pressure Loss Reduction
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Solution Overview
Problem
Conventional wall-flow exhaust gas purification catalysts experience increased pressure loss due to the location of catalytic metal, which is not optimal for vehicles with hybrid or start-stop engines that have varying exhaust temperatures.
Innovation Solution
The catalyst features upstream and downstream coating sections on the partition walls, with the catalytic metal concentrated in the surface layer of the downstream sections and distributed throughout the upstream sections, reducing pressure loss while maintaining high exhaust partition performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the catalytic layer covers the entire surface of entrance cells in conventional wall-flow catalysts, then the exhaust partition ability is improved, but the pressure loss increases excessively
Solution Approach 1:
The patent applies local quality by creating different catalytic layer configurations in different regions: the upstream catalytic layer is formed only in the interior of partition walls facing entrance cells, while the downstream catalytic layer is formed on the surface facing exit cells. This localized approach ensures adequate exhaust partitioning at the upstream side while reducing pressure loss by avoiding complete surface coverage at the downstream side where exhaust flows more directly.
Solution Approach 2:
The patent segments the catalytic layers into distinct upstream and downstream sections with different configurations. The upstream catalytic layer is confined to partition wall interiors, while the downstream catalytic layer is positioned on partition wall surfaces. This segmentation allows each region to be optimized for its specific function, resolving the contradiction between partitioning efficiency and pressure loss.
2Reliability
If a complete catalytic layer is formed on partition walls, then catalytic performance is improved, but the complexity of the catalyst structure increases
Solution Approach 1:
The patent simplifies the overall catalyst structure by applying catalytic layers only where needed for specific functions. The upstream region receives catalytic treatment in partition wall interiors for effective exhaust partitioning, while the downstream region receives catalytic treatment only on surfaces. This selective approach maintains catalytic performance while reducing structural complexity compared to complete surface coverage.
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 effectively reduces pressure loss while enhancing exhaust partition ability, particularly in vehicles with energy-saving systems, by optimizing the distribution and location of catalytic metal within the catalyst.
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 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
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AI summary
This invention provides an exhaust gas purification catalyst having an excellent exhaust partition ability while reducing the increase in pressure loss. Exhaust gas purification catalyst 10 comprises a substrate having a wall-flow structure with partition wall 12, upstream coating section formed in portions of partition wall 12 facing entrance cell 24, from exhaust inlet-side end 24a in the extending direction of partition wall 12, and downstream coating section formed in portions of partition wall 12 facing exit cell 25, from exhaust outlet-side end 25a in the extending direction, having a length shorter than the entire length Lw of the partition wall. In downstream coating section 28, a catalytic metal is concentrated in the surface layer in contact with exit cell 25.