Rhodium-Only TWC Catalyzed Particulate Filter for Gasoline Emissions
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Solution Overview
Problem
Current emission treatment systems for gasoline engines face challenges in achieving effective conversion of hydrocarbons, carbon monoxide, and nitrogen oxides while managing particulate matter emissions without increasing backpressure, especially in meeting stringent Euro 6 standards for gasoline direct injection engines.
Innovation Solution
A catalyzed particulate filter system is introduced, featuring a close-coupled three-way conversion (TWC) catalyst with a second TWC catalytic material permeating the walls of a particulate filter, utilizing rhodium as the only platinum group metal, which maintains porosity and backpressure levels, ensuring efficient filtration and emission conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional multi-metal TWC catalyst is used, then conversion effectiveness is achieved, but cost increases
Solution Approach 1:
The patent extracts and removes palladium from the traditional multi-metal TWC catalyst formulation, retaining only rhodium as the platinum group metal. This extraction is achieved through selective catalyst formulation that eliminates unnecessary metals while maintaining the three-way conversion functionality for treating hydrocarbons, carbon monoxide, and nitrogen oxides.
Solution Approach 2:
The patent replaces expensive multi-metal catalyst formulations with a more economical single-metal rhodium-based catalyst. By using rhodium as the only platinum group metal, the system achieves cost reduction while maintaining adequate conversion effectiveness for emission treatment.
2Reliability
If catalytic material is applied to the particulate filter walls, then emission conversion is improved, but backpressure increases
Solution Approach 1:
The patent utilizes the porous structure of the particulate filter walls as a three-dimensional catalyst carrier. The catalytic material is applied within the porous matrix rather than forming a dense coating, allowing exhaust gases to flow through the porous structure while accessing catalytic sites. This approach maintains porosity and minimizes backpressure increase.
Solution Approach 2:
The catalytic material is selectively applied to specific regions within the particulate filter walls rather than uniformly coating the entire surface. The washcoat is applied to create localized catalytic zones within the porous structure, providing emission conversion functionality while preserving the overall flow characteristics and porosity of the filter.
3Reliability
If the particulate filter porosity is reduced to improve filtration, then particulate matter capture is improved, but backpressure increases
Solution Approach 1:
The patent merges the filtration function and catalytic conversion function into a single integrated particulate filter component. The catalytic material is applied within the porous walls of the filter, combining particulate matter capture and emission conversion in one device. This integration allows the system to achieve both filtration and conversion without requiring separate components that would increase overall backpressure.
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 system achieves full TWC functionality, effectively converting hydrocarbons, carbon monoxide, and nitrogen oxides while maintaining low backpressure, thus meeting regulatory standards for particulate matter emissions with reduced costs by using only rhodium as the platinum group metal.
Implementation Method 1
Such catalysts promote the oxidation by oxygen in the exhaust gas stream of unburned hydrocarbons and carbon monoxide
Implementation Method 2
Catalytic converters containing a three-way conversion (TWC) catalyst are accordingly located in the exhaust gas line of internal combustion engines
Implementation Method 3
the reduction of nitrogen oxides to nitrogen
Implementation Method 4
Such catalysts promote the oxidation by oxygen in the exhaust gas stream of unburned hydrocarbons and carbon monoxide as well as the reduction of nitrogen oxides to nitrogen
Implementation Method 5
a second TWC catalytic material that permeates walls of a particulate filter
Data Source
AI summary
Catalyzed particulate filters comprise three-way conversion (TWC) catalytic material, which comprises rhodium as the only platinum group metal, that permeates walls of a particulate filter. Such catalyzed particulate filters may be located downstream of close-coupled three-way conversion (TWC) composites in an emission treatment system downstream of a gasoline direct injection engine for treatment of an exhaust stream comprising hydrocarbons, carbon monoxide, nitrogen oxides, and particulates.