Three-Way Catalyst Pt Partitioning for Faster Exhaust Light-Off
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Solution Overview
Problem
Conventional three-way catalysts (TWCs) face limitations in controlling the structure and composition of catalytically active species, leading to suboptimal performance and high precious group metal (PGM) usage, which is costly and inefficient under stringent emissions regulations.
Innovation Solution
A catalyst article with a ceria-zirconia support material preferentially supporting Pt, while minimizing Pt on non-ceria-zirconia support material, enhancing metal-support interaction and maintaining low PGM content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional washcoat slurry preparation with inorganic PGM precursor is used, then PGM can be deposited onto metal oxide support, but control over structure of catalytically active species is limited due to metal migration and grain growth during high temperature calcination
Solution Approach 1:
The invention changes the chemical form of PGM from inorganic precursors to organic metal-β-diketonate complexes, which decompose at lower temperatures without causing metal migration and grain growth. This parameter change in the chemical composition and decomposition behavior of the PGM source enables precise control over the structure of catalytically active species while maintaining performance consistency.
Solution Approach 2:
The invention discards the conventional high-temperature calcination step that causes metal migration and grain growth. Instead, it uses a low-temperature decomposition process of organic metal-β-diketonate complexes, thereby recovering the ability to control metal nanoparticle structure without the harmful effects of high-temperature processing.
2Reliability
If higher PGM loading is used to improve TWC performance, then emissions abatement efficiency increases, but cost increases significantly
Solution Approach 1:
The invention changes the decomposition temperature parameter of the PGM source by using organic metal-β-diketonate complexes instead of inorganic precursors. This enables effective PGM utilization at lower loadings because the organic complexes decompose cleanly at lower temperatures, preventing metal aggregation and maintaining high catalytic activity per unit mass of PGM.
Solution Approach 2:
The invention uses composite organic-inorganic structures where PGM is coordinated with β-diketonate ligands. This composite material approach allows for controlled decomposition and formation of highly dispersed metal nanoparticles, improving the efficiency of PGM usage and reducing the total quantity of PGM needed for effective catalysis.
3Ease of manufacture
If Pt is distributed uniformly on all support materials, then manufacturing is simple, but metal-support interaction cannot be optimized for specific catalytic functions
Solution Approach 1:
The invention applies local quality by creating different Pt loadings on different support materials within the same catalyst. The ceria-zirconia support receives higher Pt loading (0.1-3 wt.%) optimized for specific catalytic functions, while the non-ceria-zirconia support receives lower Pt loading (<0.1 wt.%). This localized optimization of metal-support interaction enhances overall catalytic performance while maintaining a relatively simple manufacturing process using a slurry formulation approach.
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
Improves light-off performance for NOx, THC, and CO conversion, reducing PGM usage and maintaining catalytic activity under harsh engine conditions.
Implementation Method 1
A better control of the metal-support interaction is also essential in optimizing the TWC performance
Data Source
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AI summary
The present invention relates to a catalyst article for treating exhaust gas, the catalyst article comprising a substrate and at least a first catalytic region disposed on the substrate, wherein the first catalytic region comprises a ceria-zirconia support material and a non-ceria-zirconia support material; wherein from 0.1 to 3 wt.% Pt is supported on the ceria-zirconia support material, based on the total weight of the Pt supported on the ceria-zirconia support material and the ceria-zirconia support material; wherein less than 0.1 wt.% Pt is supported on the non-ceria-zirconia support material, based on the total weight of the Pt supported on the non-ceria-zirconia support material and the non-ceria-zirconia support material; and wherein the first catalytic region comprises from 0.1 to 50 g/ft3 Pt, based on the total volume of the substrate.