Three-Layer Exhaust Catalyst Layout for Phosphorus Poisoning
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Solution Overview
Problem
Exhaust gas purification catalysts are susceptible to phosphorus poisoning, which reduces their purification performance and increases costs due to the need for noble metals, especially in the upstream portions that are more likely to contact exhaust gases.
Innovation Solution
A three-layer catalytic structure is employed, with a Ce-free Ba-containing first layer on the upstream surface to capture phosphorus, a Ce-based oxygen storage/release layer in the middle, and a Pd-containing layer divided into front and rear portions with varying noble metal concentrations to enhance purification efficiency while minimizing phosphorus poisoning and noble metal usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the ratio of noble metal is increased in the upstream portion to improve purification efficiency, then the purification performance is improved, but the cost increases due to increased noble metal usage
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where different layers have different noble metal concentrations. The first layer (upstream) has high noble metal concentration for efficient purification, while subsequent layers have progressively lower concentrations, optimizing the balance between purification efficiency and cost.
2Productivity
If the Ce-based oxygen storage/release material is used to improve the A/F window and purification performance, then the purification capability is improved, but the phosphorus poisoning occurs more easily in the upstream portion
Solution Approach 1:
The patent segments the catalyst into multiple layers with different compositions. The first layer uses Ce-free Ba-containing material to resist phosphorus poisoning, while the second layer uses Ce-based OSC material to provide oxygen storage/release capability. This segmentation allows each layer to perform its specific function without being adversely affected by phosphorus.
Solution Approach 2:
The patent introduces a Ce-free Ba-containing first layer as an intermediary between the exhaust gas and the Ce-based OSC material. This intermediary layer captures phosphorus compounds before they can reach and poison the Ce-based catalyst in the second layer, protecting the oxygen storage/release functionality.
3Ease of manufacture
If the single-layer catalyst structure is used to simplify the device, then the manufacturing is easier, but the ability to simultaneously achieve high purification efficiency and phosphorus resistance is reduced
Solution Approach 1:
The catalyst is segmented into multiple functional layers, each with specific compositions optimized for different functions. This segmentation enables the simultaneous achievement of high purification efficiency and phosphorus resistance while maintaining reasonable manufacturing complexity through a systematic multi-layer structure.
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 configuration improves purification performance for hydrocarbons, carbon monoxide, and nitrogen oxides by reducing phosphorus poisoning and optimizing noble metal distribution, thereby enhancing catalyst efficiency and reducing costs.
Implementation Method 1
The OSC material stores oxygen in a lean atmosphere with high oxygen concentration in the exhaust gas, and releases active oxygen in a stoichiometric or rich atmosphere with low oxygen concentration in the exhaust gas
Implementation Method 2
The Ce-containing OSC material stores oxygen in the exhaust gas and releases the oxygen as active oxygen by the reversible progress of a reaction accompanied by a change in the valence of Ce
Implementation Method 3
a catalyst for purifying harmful components such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) in exhaust gas
Implementation Method 4
a considerable amount of phosphorus compounds is deposited in the upstream and intermediate portions (space portion) of the third catalytic layer
Data Source
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AI summary
An exhaust gas purification catalyst 1 includes a support 2 and a catalytic layer 3. The catalytic layer 3 includes a first catalytic layer 6, a second catalytic layer 7, and a third catalytic layer 8. The first catalytic layer 6 contains a first catalyst material including Rh supported on a Ce-free support material and Ba, but does not contain Ce. The second catalytic layer 7 contains a second catalyst material including Rh supported on a support material containing a Ce-based oxygen storage/release material. A ratio C2/C1 is more than 1.0, where C1 represents a Rh concentration in the first catalyst material, and C2 represents a Rh concentration in the second catalyst material. The third catalytic layer 8 includes a front portion 81 including an upstream catalyst material containing Pd supported on an upstream support material and a rear portion 82 including a downstream catalyst material containing Pd supported on a downstream support material. A ratio D2/D1 is more than 1.0, where D1 represents a Pd concentration in the upstream catalyst material, and D2 represents a Pd concentration in the downstream catalyst material.