Tin-Modified Catalyst for Exhaust Emission Control
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Solution Overview
Problem
Current three-way catalysts (TWCs) for gasoline engine exhausts face challenges in improving performance during cold start and hot transient stages, as well as oxygen storage capacity (OSC) performance across a wide range of temperatures, while also being cost-effective.
Innovation Solution
A catalytic composition comprising a platinum group metal (PGM) component and a PGM support material with up to 5 wt. % Sn, which enhances the catalytic properties by improving PGM dispersion and stabilization, and incorporating Sn into the TWC catalyst compositions to promote better thermal durability and emission control performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional TWC catalysts are used, then basic emission control is achieved, but performance during cold start and hot transient stages is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst by incorporating tin (Sn) at 0.1-5 wt% and adjusting the PGM to support material ratios. This compositional parameter change improves catalytic activity during cold start and hot transient stages while maintaining thermal durability, directly resolving the performance insufficiency in critical operating conditions.
Solution Approach 2:
The patent creates a composite catalyst system combining platinum group metals (Pd, Pt, Rh) with tin-modified support materials (ceria-zirconia mixed oxide, alumina, or titania). This composite structure leverages the synergistic effects of different materials: PGMs provide catalytic activity, while Sn-modified supports enhance oxygen storage capacity and thermal stability, collectively improving both reliability and productivity across all operating conditions.
2Reliability
If PGM loading is increased to improve catalytic activity, then emission control performance improves, but cost increases
Solution Approach 1:
The patent replaces a portion of expensive platinum group metals with cheaper tin-modified support materials that provide oxygen storage and catalytic functions. By using Sn-doped ceria-zirconia or alumina-titania composite supports, the catalyst achieves comparable or superior performance to high-PGM formulations at lower cost, directly addressing the cost-performance trade-off.
Solution Approach 2:
The patent optimizes the PGM to support material ratio parameter, reducing PGM content while compensating with Sn-modified supports containing 0.1-5 wt% Sn. This parameter change maintains or improves emission control performance through enhanced oxygen storage capacity and catalytic activity from Sn, thereby reducing the quantity of expensive PGMs required.
3Productivity
If catalyst composition is modified to improve cold start performance, then light-off performance improves, but OSC performance across wide temperature range may deteriorate
Solution Approach 1:
The patent applies local quality by creating distinct functional zones within the catalyst structure: Sn-modified support materials provide enhanced oxygen storage capacity for improved light-off performance, while PGM components distributed throughout provide consistent catalytic activity across the full temperature range. This localized functional differentiation allows simultaneous optimization of cold start and wide-temperature OSC performance.
Solution Approach 2:
The patent uses composite materials combining Sn-doped ceria-zirconia mixed oxide or alumina-titania with PGMs to achieve both improved light-off performance and broad-temperature OSC stability. The composite structure provides complementary functions: Sn-enhanced supports improve low-temperature oxygen storage for better light-off, while the stable PGM-component provides consistent catalytic activity across the full operating temperature range, maintaining adaptability.
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 solution significantly reduces emissions of THC/NMHC, CO, and NOx, improves light-off performance, and enhances OSC functions across various temperature ranges, resulting in improved catalytic converter performance and reduced costs.
Implementation Method 1
improving PGM dispersion and stabilization
Implementation Method 2
improving PGM dispersion and stabilization
Implementation Method 3
enhances OSC functions across various temperature ranges
Implementation Method 4
oxidation of CO; oxidation of unburnt HCs
Implementation Method 5
reduction of NOx
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 comprising an inlet end and an outlet end with an axial length L; a first catalytic region comprising a first platinum group metal (PGM) component and a first PGM support material, wherein the first catalytic region comprises up to 5 wt. % Sn.