PGM Nanoparticle TWC Catalysts for Gasoline Exhaust
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Solution Overview
Problem
Existing three-way catalysts (TWCs) for gasoline engines face challenges in maintaining the dispersion and thermostability of platinum group metal (PGM) nanoparticles under aging conditions, especially at lower temperatures, which affects their performance in reducing NOx, CO, and HC emissions.
Innovation Solution
The use of PGM nanoparticles with a mean size of 1 nm to 10 nm and a standard deviation of no more than 1 nm, specifically platinum clusters with no more than 100 atoms, supported on inorganic oxides like alumina, which exhibit improved thermostability and activity after harsh hydrothermal aging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional impregnation methods are used to produce PGM catalysts, then the catalyst can be manufactured with standard procedures, but the PGM nanoparticles exhibit wide size distribution and poor dispersion stability under aging conditions
Solution Approach 1:
The patent applies preliminary action by pre-synthesizing PGM nanoparticles with controlled sizes (1-10 nm) and specific crystal structures (fcc or non-fcc) before incorporating them into the catalyst support. This pre-preparation ensures uniform size distribution and desired structural properties are achieved before the catalytic application, resolving the size control issue while maintaining manufacturing feasibility through established nanoparticle synthesis techniques.
Solution Approach 2:
The patent employs parameter changes by precisely controlling nanoparticle size (1-10 nm range) and crystal structure (fcc vs. non-fcc) as key parameters. These parameter specifications directly influence the dispersion stability and catalytic performance under aging conditions. By defining specific size ranges and structural characteristics, the patent achieves improved manufacturing precision without excessive complexity.
2Productivity
If non-fcc PGM clusters with below 100 atoms are used, then unique chemical properties and lower-temperature activity are achieved, but thermostability under high-temperature operation conditions is insufficient
Solution Approach 1:
The patent applies local quality by creating spatial and structural differentiation between the PGM nanoparticle cores and their surface structures. Specifically, it utilizes nanoparticles with 1-10 nm sizes that can exhibit core-shell structures or surface modifications where the interior maintains the unique chemical properties of small clusters while the surface provides enhanced thermal stability. This local differentiation allows simultaneous achievement of high catalytic activity and thermostability.
Solution Approach 2:
The patent employs composite materials by combining PGM nanoparticles with support materials (such as alumina, ceria, or other oxides) to create a composite catalyst system. The PGM nanoparticles provide unique chemical properties and high activity, while the support materials contribute thermal stability and structural integrity under operating conditions. This composite approach resolves the contradiction between activity and thermostability.
3Quantity of substance
If PGM nanoparticle size is reduced to below 100 atoms, then the amount of PGM required is reduced and cost is lowered, but maintaining dispersion and preventing aggregation under aging conditions becomes difficult
Solution Approach 1:
The patent applies the intermediary principle by introducing support materials and dispersants as mediators between the PGM nanoparticles. These intermediaries prevent direct contact and aggregation between small PGM particles while providing a stable dispersion medium. The support materials (such as high-surface-area oxides) act as carriers that physically separate and stabilize the nanoparticles, enabling cost reduction through lower PGM loading while maintaining dispersion stability during aging.
Solution Approach 2:
The patent employs porous materials as support structures with high surface area and controlled pore sizes. These porous supports provide numerous anchoring sites for PGM nanoparticles, preventing aggregation while maximizing the dispersion of small particle quantities. The porous structure allows efficient utilization of minimal PGM loading by distributing particles across a large surface area, thereby maintaining both cost-effectiveness and compositional stability.
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 approach enhances the catalytic performance by maintaining the size and distribution of PGM nanoparticles, leading to improved conversion of NOx, CO, and HC emissions while potentially reducing the amount of PGM required and lowering costs.
Implementation Method 1
platinum group metals (PGMs) (e.g., Pt, Pd, and Rh) have been widely used as active site of catalytic conversion
Implementation Method 2
oxidation of CO
Implementation Method 3
oxidation of unburnt HCs
Implementation Method 4
oxidation of unburnt HCs
Implementation Method 5
reduction of NOx to N2
Implementation Method 6
reduction of NOx to N2
Data Source
AI summary
A three-way catalyst article, and its use in an exhaust system for internal combustion engines, is disclosed. The catalyst article for treating exhaust gas comprising: a substrate; and a first catalytic region on the substrate; wherein the first catalytic region comprises a first platinum group metal (PGM) component and a first inorganic oxide, wherein the first PGM component comprises PGM nanoparticles, wherein the PGM nanoparticles have no more than 100 PGM atoms, and wherein the PGM nanoparticles have a mean particle size of 1 nm to 10 nm with a standard deviation (SD) no more than 1 nm.