PGM-Gradient Washcoat Architecture for Three-Way Emission Catalysts
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Solution Overview
Problem
Existing three-way conversion catalysts for internal combustion engines require improvements in washcoat architecture, platinum group metal type and loading, and coating strategies to enhance the reduction of pollutants such as NOx, HC, and CO.
Innovation Solution
The catalyst article features a platinum group metal (PGM) gradient within the washcoat layers, with higher PGM concentration in the top-most portion compared to the bottom-most portion, and a substrate with a bottom and top washcoat layer covering 60 to 100% of the substrate length, ensuring at least 20-100% of the PGM is deposited with a gradient, and a ratio of uniformly deposited PGM to gradient-deposited PGM ranging from 10:1 to 1:10.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If platinum group metals are coated uniformly on the substrate, then the coating process is simple, but the pollutant reduction efficiency is insufficient
Solution Approach 1:
The patent applies local quality by creating a non-uniform PGM distribution within the washcoat layer. The PGM concentration varies through the layer thickness, with higher concentration at specific depths (e.g., 20-80% from the outer surface) to optimize catalytic activity for different pollutant conversion reactions while maintaining a relatively simple dual-layer coating process.
Solution Approach 2:
The patent transitions from two-dimensional uniform surface coating to three-dimensional gradient distribution within the washcoat layer. By controlling PGM concentration as a function of depth through the washcoat layer, the invention creates a volumetric gradient structure that enhances pollutant reduction efficiency without significantly complicating the coating methodology.
2Reliability
If platinum group metal loading is increased, then pollutant reduction efficiency improves, but manufacturing cost increases
Solution Approach 1:
The patent concentrates PGM at specific locations within the washcoat layer (e.g., 20-80% depth from outer surface) rather than uniform distribution. This localized concentration strategy achieves high pollutant reduction efficiency in critical zones while reducing overall PGM loading, thereby lowering material costs while maintaining or enhancing catalytic performance.
Solution Approach 2:
The patent optimizes PGM distribution by changing the concentration parameter through the washcoat layer depth. By controlling the gradient profile and peak concentration position, the invention achieves efficient pollutant conversion with reduced total PGM quantity, balancing performance and cost-effectiveness.
3Device complexity
If a single-layer washcoat structure is used, then the catalyst structure is simple, but the pollutant reduction performance is limited
Solution Approach 1:
The patent divides the washcoat into functional zones with different PGM concentrations. The gradient structure creates distinct regions: an outer zone for certain catalytic functions, a middle zone (20-80% depth) with peak PGM concentration for primary conversion reactions, and an inner zone for support functions. This segmentation enhances overall pollutant reduction performance while maintaining a relatively simple dual-layer architecture.
Solution Approach 2:
The patent creates a composite washcoat structure combining washcoat material with gradient-distributed PGM. This composite architecture integrates the structural support function of the washcoat with the catalytic function of PGM in a spatially optimized manner, achieving superior pollutant reduction performance compared to single-layer uniform structures.
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 significantly enhances the reduction of NOx, HC, and CO emissions by optimizing the PGM distribution, achieving improved pollutant removal efficiency.
Implementation Method 1
a platinum group metal deposited within the washcoat layer(s) with a platinum group metal gradient such that the PGM concentration in a top-most portion of the washcoat layer is at least two times higher compared to the PGM concentration in a bottom-most portion of the washcoat layer
Implementation Method 2
The three-way conversion catalyst is typically known to oxidize unburnt hydrocarbon and carbon monoxide and reduce nitrogen oxides
Implementation Method 3
The three-way conversion catalyst is typically known to oxidize unburnt hydrocarbon and carbon monoxide
Implementation Method 4
The three-way conversion catalyst is typically known to oxidize unburnt hydrocarbon and carbon monoxide and reduce nitrogen oxides
Data Source
AI summary
The presently invention provides an emission control catalyst article comprising a substrate, a bottom washcoat layer comprising a platinum group metal coated on the 60 to 100% length of the substrate, and a top washcoat layer comprising a platinum group metal coated on the 60 to 100% length of the substrate such that the top coat covers at least 60% of the length of the bottom washcoat layer, wherein at least a portion of the top washcoat layer, the bottom washcoat layer or both washcoat layers comprises a platinum group metal deposited within the said washcoat layer(s) with a platinum group metal gradient such that the PGM concentration in a top-most portion of the said washcoat layer is at least two time higher compared to the PGM concentration in a bottom-most portion of the said washcoat layer.