TWC Catalyst Coated Particulate Trap for GDI Emissions
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Solution Overview
Problem
Existing emission treatment systems for gasoline direct injection engines are inadequate for capturing particulates and treating gaseous emissions such as hydrocarbons, nitrogen oxides, and carbon monoxide, particularly during cold start conditions, and face challenges with backpressure and system crowding due to stringent particulate standards.
Innovation Solution
The implementation of a three-way conversion (TWC) catalyst integrated with a particulate trap, where the TWC catalyst is coated onto the particulate trap, either uncoated or with soot burning aids, to facilitate regeneration, and additional treatment components like NOx traps and SCR catalysts can be added downstream, with the TWC catalyst being strategically located upstream or coated on both sides of the particulate trap to optimize emissions treatment without excessive backpressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a TWC catalyst is coated onto a particulate trap to treat gaseous emissions and capture particulates, then emissions treatment effectiveness is improved, but backpressure increases
Solution Approach 1:
The patent combines the TWC catalyst and particulate trap into a single integrated component, where the catalyst is coated onto the particulate trap substrate. This merging allows simultaneous particulate capture and gaseous emission treatment in one device, improving overall emissions treatment effectiveness while avoiding the need for separate components that would increase backpressure
Solution Approach 2:
The catalyst coating is applied locally on the particulate trap surface, creating zones with different functional properties. The washcoat distribution and PGM zoning create local catalytic activity centers that maximize treatment effectiveness while minimizing the overall material loading and associated backpressure
2Reliability
If additional treatment components (NOx traps, SCR catalysts) are added downstream of the particulate trap, then emissions treatment coverage is improved, but device complexity increases
Solution Approach 1:
The emissions treatment system is segmented into functional zones: upstream TWC catalyst for hydrocarbons and carbon monoxide, particulate trap for soot capture, and downstream NOx traps with SCR catalysts for nitrogen oxide treatment. Each segment handles specific emissions, allowing comprehensive coverage while maintaining modular complexity that can be managed through zoned functionality
Solution Approach 2:
The integrated particulate trap serves multiple functions: it acts as a physical filter for particulates, provides a substrate for TWC catalyst coating for gaseous treatment, and can be positioned in the exhaust stream to facilitate thermal management. This multi-functionality reduces the need for additional separate components
3Productivity
If a sufficient loading of catalyst is applied to achieve treatment goals, then emissions conversion efficiency is improved, but backpressure increases
Solution Approach 1:
The catalyst loading parameters are optimized by controlling washcoat thickness and PGM distribution. By adjusting these parameters, the system achieves sufficient catalytic activity for effective emissions conversion while minimizing the total catalyst mass that would otherwise increase backpressure. The washcoat application parameters are specifically controlled to balance activity and pressure drop
4Productivity
If the TWC catalyst is located upstream of the particulate trap, then gaseous emission treatment is improved, but particulate capture during cold start is reduced
Solution Approach 1:
By coating the TWC catalyst directly onto the particulate trap substrate, the system merges gaseous treatment and particulate capture functions at the same location. This ensures that during cold start conditions, both functions occur simultaneously in the same thermal environment, eliminating the timing mismatch that would occur with separate upstream and downstream components
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 configuration effectively captures particulates and treats gaseous emissions while maintaining low backpressure, ensuring compliance with stringent emission standards and extending catalyst life through PGM zoning and optimized washcoat distribution, thereby enhancing the overall efficiency of the emissions treatment system.
Implementation Method 1
Such catalysts promote the oxidation by oxygen in the exhaust gas stream of unburned hydrocarbons and carbon monoxide
Implementation Method 2
the reduction of nitrogen oxides to nitrogen
Implementation Method 3
capture particulates
Implementation Method 4
soot burning catalysts that facilitate passive regeneration of soot
Data Source
Figure 1A~1B
Figure 1C~2
Figure 3~4
AI summary
Provided are exhaust systems and components suitable for use in conjunction with gasoline direct injection (GDI) engines to capture particulates in addition to reducing gaseous emission such as hydrocarbons, nitrogen oxides, and carbon monoxides. Exhaust treatment systems comprising a three-way conversion (TWC) catalyst located on a particulate trap are provided. An exemplary particulate trap is a soot filter. Additional treatment components can be added downstream of the particulate trap, including NOx traps and SCR catalysts. The TWC catalyst can be coated on both the inlet side and the outlet side of the particulate trap. Alternatively, an oxidation catalyst can be deposited on a particulate trap. Methods of making and using the same are also provided.