Multi-Layer Exhaust Catalyst Reducing Noble Metal via Segmentation
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Solution Overview
Problem
Conventional exhaust gas purification catalysts face challenges in reducing noble metal amounts while maintaining performance, as reducing noble metal usage leads to degradation of exhaust gas purification, warm-up, and OSC performance, and noble metal particles aggregate during catalytic reactions, compromising durability.
Innovation Solution
An exhaust gas purification catalyst with a multi-layered structure, specifically comprising a first, second, and third catalyst coating layer with controlled compositions and coat widths, using palladium and rhodium as catalyst metals, and incorporating oxygen storage capacity materials to optimize noble metal distribution and activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of noble metals is reduced in conventional exhaust gas purification catalysts, then resource risk and cost are reduced, but exhaust gas purification performance, warm-up performance, and OSC performance deteriorate
Solution Approach 1:
The catalyst coating layer is divided into multiple layers (first catalyst coating layer containing Pd, second catalyst coating layer containing Rh, third catalyst coating layer containing Pd) with different compositions and functions. This segmentation allows each layer to perform specific catalytic functions optimally, enabling reduced overall noble metal content while maintaining total catalytic performance through coordinated action of multiple specialized layers
Solution Approach 2:
Different regions of the catalyst coating have different compositions and properties. The first layer has high Pd content for oxidation reactions, the second layer has Rh for reduction reactions, and the third layer has Pd for additional oxidation capacity. This local differentiation of quality allows each region to contribute maximally to overall performance with minimal total noble metal usage
2Length of moving object
If noble metal particles are controlled to small sizes to reduce aggregation, then particle size is reduced, but durability during catalytic reaction becomes insufficient
Solution Approach 1:
The catalyst structure is segmented into multiple layers that physically separate and stabilize noble metal particles. The multi-layer configuration prevents particles from aggregating by providing physical barriers and distributing particles across different spatial zones, thereby maintaining small particle sizes while ensuring long-term durability through structural stabilization
Solution Approach 2:
Carrier materials and support structures act as intermediaries between noble metal particles and the exhaust gas environment. These intermediary materials prevent direct contact and aggregation of noble metal particles while still allowing catalytic reactions to occur, thus maintaining small particle sizes and preventing degradation over time
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 multi-layered catalyst design allows for reduced noble metal usage while maintaining or improving catalytic performance, enhancing durability and activity by controlling particle sizes and distributions, particularly for Rh, thereby improving warm-up, catalytic, and OSC performance.
Implementation Method 1
a three-way catalyst that simultaneously performs oxidation of CO and HC and reduction of NOx is used as the exhaust gas purification catalyst
Implementation Method 2
oxidation of CO and HC
Implementation Method 3
reduction of NOx
Implementation Method 4
there has been known a method to use the noble metal by supporting the noble metal as fine particles on a carrier
Data Source
AI summary
Provided is an exhaust gas purification catalyst capable of reducing a noble metal amount while maintaining a catalyst performance, which comprises a substrate and at least three catalyst coating layers formed on the substrate, the first and third catalyst coating layers contain Pd as a catalyst metal and are formed in a range of a predetermined length from an upstream end surface in an exhaust gas flow direction, and the second catalyst coating layer contains Rh as a catalyst metal and is formed in a range of a predetermined length from a downstream end surface in the exhaust gas flow direction.