Layered Exhaust Gas Catalyst Composition for Faster Warm-Up
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Solution Overview
Problem
Existing exhaust gas purification catalysts face challenges in achieving optimal performance across varying temperature environments and oxygen concentration fluctuations, particularly in the upstream and downstream catalyst layers.
Innovation Solution
The catalyst design includes a first catalyst layer with a Ce-Zr-based complex oxide and a second catalyst layer with Al2O3, with specific mass content ratios and noble metal elements like Pd and/or Pt, to enhance warm-up efficiency and stability under different operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the first catalyst layer contains Al2O3 to improve structural stability, then the catalyst layer stability is improved, but the warm-up efficiency deteriorates due to Al2O3's low specific heat capacity
Solution Approach 1:
The patent applies local quality by differentiating the composition of the first and second catalyst layers. The first catalyst layer uses Ce-Zr-based complex oxide with low Al content (≤12%) to prioritize warm-up efficiency, while the second catalyst layer uses Al2O3-based material to prioritize structural stability. This spatial differentiation of material properties resolves the contradiction between warm-up efficiency and stability.
Solution Approach 2:
The patent segments the catalyst into two distinct layers with different compositional characteristics. The first catalyst layer (upstream) is optimized for warm-up performance with Ce-Zr complex oxide, while the second catalyst layer (downstream) is optimized for thermal stability with Al2O3. This segmentation allows each layer to specialize in its strength, resolving the overall system contradiction.
2Loss of time
If the first catalyst layer uses Ce-Zr-based complex oxide to improve warm-up efficiency, then the warm-up efficiency is improved, but the oxygen concentration fluctuation resistance deteriorates
Solution Approach 1:
The patent divides the catalyst function between two layers: the first layer (Ce-Zr based) handles warm-up efficiency while the second layer (Al2O3 based) handles oxygen concentration fluctuation resistance. This functional segmentation allows each layer to optimize for its specific role without compromising the other.
Solution Approach 2:
The patent uses composite material strategies by combining Ce-Zr-based complex oxide in the first layer with Al2O3 in the second layer. Each material is selected for its specific properties: Ce-Zr complex oxide for warm-up efficiency and Al2O3 for stability and oxygen concentration resistance, creating a composite catalyst system that achieves multiple objectives simultaneously.
3Stability of the object's composition
If the mass content of Al in the first catalyst layer is increased to improve structural stability, then the catalyst layer stability is improved, but the warm-up efficiency deteriorates
Solution Approach 1:
The patent applies local quality by restricting Al content to ≤12% in the first catalyst layer while allowing higher Al content in the second catalyst layer. This localized compositional control ensures the first layer maintains warm-up efficiency while the second layer provides structural stability, resolving the contradiction through spatial differentiation.
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 achieves improved exhaust gas purification performance by optimizing warm-up efficiency in low-temperature conditions and maintaining active site dispersion under high-temperature conditions, while mitigating oxygen concentration fluctuations.
Implementation Method 1
mitigating oxygen concentration fluctuations
Implementation Method 2
Pt and Pd are mainly involved in oxidative purification of HC and CO
Implementation Method 3
oxidative purification of HC and CO
Implementation Method 4
Rh is mainly involved in reductive purification of NOx
Implementation Method 5
reductive purification of NOx
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An object of the present invention is to provide an exhaust gas purification catalyst with excellent exhaust gas purification performance, and the present invention provides an exhaust gas purification catalyst (1), including a substrate (10), a first catalyst layer (20) provided on an upstream side of the substrate (10), and a second catalyst layer (30) provided on a downstream side of the substrate (10), wherein the first catalyst layer (20) contains a noble metal element and a Ce-Zr-based complex oxide, wherein the second catalyst layer (30) contains a noble metal element and Al2O3, wherein a mass content of Al in terms of Al2O3 in the first catalyst layer (20) is 12% by mass or less, and wherein a ratio of the mass content of Al in terms of Al2O3 in the first catalyst layer (20) to a mass content of Al in terms of Al2O3 in the second catalyst layer (30) is 0 or more and 0.65 or less.