Segmented Exhaust Catalyst Layers Reduce Pressure Loss
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Solution Overview
Problem
Existing exhaust gas purification catalysts of the wall flow type face challenges in reducing pressure loss while maintaining effective purification performance, particularly in meeting stringent emission regulations and fuel consumption standards.
Innovation Solution
The catalyst configuration includes two separate catalyst layers, one containing an oxidation catalyst and the other a reduction catalyst, disposed within the partition wall of the exhaust gas purification device, with varying lengths on either side to optimize contact frequency and flow path, reducing pressure loss while enhancing purification efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Rh-containing layer is disposed to cover the whole surface of the partition wall, then the purification performance on harmful components is enhanced, but the pressure loss increases causing the output of the internal combustion engine to drop
Solution Approach 1:
The catalyst layer is segmented into two distinct regions: a first catalyst layer containing Pd for oxidation of HC and CO, and a second catalyst layer containing Rh for reduction of NOx. This segmentation allows each region to be optimized for its specific function, with the Rh-containing region extending further downstream where NOx reduction is most effective, while maintaining adequate coverage for pressure loss management.
Solution Approach 2:
Different sections of the partition wall are assigned different catalyst compositions tailored to local requirements. The upstream region has higher Pd concentration for oxidation, while the downstream region has higher Rh concentration for reduction. This local quality differentiation enables optimal purification performance without requiring uniform catalyst coverage that would maximize pressure loss.
2Reliability
If the catalyst layer is provided throughout the interior of the partition wall, then the contact frequency with exhaust gas is increased, but the pressure loss increases
Solution Approach 1:
The catalyst layer is divided into two segmented regions with different compositions and extensions. The first Pd-containing layer extends from the upstream end, while the second Rh-containing layer extends from the downstream end. This segmentation allows exhaust gas to contact both catalyst types along its flow path without requiring continuous coverage throughout the entire partition wall, thereby reducing pressure loss while maintaining effective contact frequency.
Solution Approach 2:
Instead of providing uniform catalyst coverage in the thickness direction throughout the entire partition wall length, the invention extends catalyst layers in the flow direction (longitudinal dimension) from opposite ends. This dimensional approach allows the catalyst to be present where exhaust gas actually flows through the partition wall, maximizing contact efficiency while minimizing unnecessary catalyst material that would increase pressure loss.
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 and enhances the purification of harmful components such as NOx, HC, and CO, achieving higher purification performance compared to conventional designs where catalyst layers are on the surface or not in contact with all cells.
Implementation Method 1
Either one of the first catalyst layer and the second catalyst layer contains an oxidation catalyst
Implementation Method 2
the other one contains a reduction catalyst but does not contain an oxidation catalyst
Implementation Method 3
a first catalyst layer disposed in the interior of the partition wall... a second catalyst layer disposed in the interior of the partition wall
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The present invention provides to an exhaust gas purification that has: a base 11 of wall flow structure having inlet side cells 12 in which an end 13 on the exhaust gas inflow side is open and outlet side cells 14 in which an end 15 on the exhaust gas outflow side is open, and a porous partition wall that partitions the inlet side cell and the outlet side cell; and a first catalyst layer 20 and a second catalyst layer 30 disposed in the interior of the porous partition wall 16 so as to be in contact with the inlet side cells 12 and the outlet side cells 14, wherein either one of the first catalyst layer 20 and the second catalyst layer 30 contains an oxidation catalyst but does not contain a reduction catalyst, and the other one contains the reduction catalyst but does not contain the oxidation catalyst; and a ratio of the lengths of the first catalyst layer 20 and the second catalyst layer 30 differs between a surface of the porous partition wall 16 on the side in contact with the inlet side cells 12 and a surface on the side in contact with the outlet side cells 14.