Wall-Flow Catalyst Layering for PM Capture and Low Pressure Loss
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Solution Overview
Problem
Existing exhaust gas purification systems face a challenge in balancing the improvement of particulate matter (PM) collection performance with the suppression of pressure loss increase, as increasing pore sizes in the catalyst layer and partition wall improve PM collection but increase pressure loss, while decreasing pore sizes reduce pressure loss but deteriorate PM collection.
Innovation Solution
The exhaust gas purification catalyst employs a substrate with a first and second catalyst layer, each with specific pore diameter and gas permeability ranges, and includes materials like Ce-based oxides and Ce-Zr-based complex oxides, to achieve improved PM collection and reduced pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pore sizes in the catalyst layer and partition wall are decreased to improve PM collection performance, then PM collection performance is improved, but pressure loss increases
Solution Approach 1:
The catalyst layer is divided into multiple layers with different pore sizes arranged in sequence. The first catalyst layer has larger pores to reduce pressure loss, while the second catalyst layer has smaller pores to improve PM collection performance. This segmentation allows each layer to perform its specific function optimally without compromising the other.
Solution Approach 2:
Different regions of the catalyst layer are assigned different pore sizes based on their functional requirements. The upstream region (first catalyst layer) has larger pores to facilitate gas flow and reduce pressure loss, while the downstream region (second catalyst layer) has smaller pores to enhance PM collection efficiency.
2Loss of energy
If pore sizes in the catalyst layer and partition wall are increased to suppress pressure loss, then pressure loss is suppressed, but PM collection performance declines
Solution Approach 1:
The catalyst layer is segmented into multiple layers with different pore sizes. The first catalyst layer has larger pores to suppress pressure loss, while the second catalyst layer has smaller pores to maintain PM collection performance. This resolves the contradiction by distributing different pore size requirements to different segments.
Solution Approach 2:
Different pore sizes are assigned to different locations within the catalyst layer structure. The region closer to the exhaust gas inlet has larger pores for low pressure loss, while the region closer to the outlet has smaller pores for high PM collection efficiency.
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 catalyst system effectively enhances PM collection performance while minimizing pressure loss, optimizing both functions simultaneously.
Implementation Method 1
PM in the exhaust gas is trapped in pores of the catalyst layer and the partition wall
Implementation Method 2
A catalyst containing noble metal elements, such as Pt, Pd, and Rh, is used as the three-way catalyst
Data Source
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AI summary
An object of the present invention is to provide an exhaust gas purification catalyst capable of achieving both improvement of PM collection performance and suppression of pressure loss increase, and the present invention provides an exhaust gas purification catalyst (1) including: a wall-flow substrate; and at least one of a first catalyst layer (20) and a second catalyst layer (30), wherein the exhaust gas purification catalyst (1) satisfies the following formulae 1a and 2a: 1.30×10−3≤Ra Xa×Ya≤8.00 and/or satisfies the following formulae 1b and 2b: 1.30×10−3≤Rb Xb×Yb≤8.00