Three-Way Catalyst Zonal PGM Distribution for Poison Resistance
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Solution Overview
Problem
Three-way catalysts for combustion engines face challenges due to high costs of platinum group metals and poisoning by contaminants, which deactivates the catalyst, especially when these metals are concentrated at the inlet region, leading to reduced performance and shorter catalyst life.
Innovation Solution
A catalyst design with three washcoat zones along the monolith substrate, where the high platinum group metal concentration is strategically placed away from the inlet, specifically one to four inches back, to minimize poisoning and deactivation while maintaining improved light-off performance, using a carrier substrate with distinct zones for different platinum group metals to optimize distribution and longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If platinum group metals are concentrated at the inlet region to improve light-off performance, then cold start performance is improved, but the catalyst is more susceptible to poisoning by contaminants
Solution Approach 1:
The patent applies local quality by creating distinct washcoat zones with different platinum group metal concentrations and compositions at different positions along the monolith. Zone 1 (inlet) has lower PGM concentration to resist poisoning, while Zone 2 (downstream) has higher PGM concentration for catalytic activity, with each zone having tailored properties for its specific function
Solution Approach 2:
The catalyst is segmented into multiple washcoat zones along the monolith length, with each zone containing different platinum group metals or different concentrations. This segmentation allows the inlet zone to be optimized for poison resistance while downstream zones are optimized for catalytic conversion, resolving the contradiction between light-off performance and durability
2Reliability
If homogeneous distribution of platinum group metals is used to ensure consistent performance, then catalytic activity is maintained throughout, but cost increases due to higher overall PGM loading
Solution Approach 1:
Instead of homogeneous distribution, the patent implements local quality by varying PGM concentration and composition across different zones. The inlet zone uses lower PGM loading with specific metals resistant to poisoning, while downstream zones use higher loading for maximum conversion, reducing total PGM quantity while maintaining performance consistency through zonal optimization
Solution Approach 2:
The patent changes the parameters of PGM concentration and composition along the monolith length. By gradually changing these parameters from zone to zone, the catalyst achieves consistent catalytic performance throughout while using less total PGM, as each zone is optimized for its specific operating conditions rather than using uniform high loading throughout
3Temperature
If high concentrations of platinum group metals are used to improve conversion efficiency, then light-off temperature decreases, but cost increases significantly
Solution Approach 1:
The patent applies local quality by placing high PGM concentrations only in downstream zones where they are most needed for conversion, while using lower concentrations at the inlet where poison resistance is prioritized. This reduces total PGM amount while maintaining low light-off temperature through strategic placement in the downstream zones
Solution Approach 2:
The catalyst is segmented into zones with different PGM concentrations, allowing high concentrations to be used only where they provide maximum benefit (downstream zones for conversion) rather than throughout the entire monolith. This segmentation reduces total PGM quantity while achieving the desired light-off performance through the combined effect of all zones
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 design enhances cold start performance and extends catalyst life by reducing exposure to contaminants, achieving better conversion efficiency and durability compared to homogeneous distribution or inlet zoning, while maintaining cost-effectiveness through strategic placement of platinum group metals.
Implementation Method 1
such catalysts contain catalytically active material consisting of one or more platinum group metals, in particular platinum, palladium and/or rhodium
Implementation Method 2
CO and HC are catalytically oxidized to carbon dioxide and water
Implementation Method 3
mainly NOx is reduced to nitrogen using e.g. CO as a reducing agent
Implementation Method 4
mainly NOx is reduced to nitrogen using e.g. CO as a reducing agent
Implementation Method 5
oxygen storage components ((FSCs) in the form of cerium-zirconium mixed oxides are included in its formulation
Data Source
AI summary
The present invention relates to a catalyst comprising a carrier substrate of the length L extending between substrate ends a and b and three washcoat zones A, B and C wherein washcoat zone A comprises one or more first platinum group metals and extends starting from substrate end a over a part of the length L,washcoat zone C comprises one or more first platinum group metals and extends starting from substrate end b over a part of the length L, and washcoat zone B comprises the same components as washcoat zone A and in addition, one or more second platinum group metals and extends between washcoat zones A and C, wherein L=LA+LB+LC, wherein LA is the length of washcoat zone A, LB is the length of substrate length B and LC is the length of substrate length C.