Wall-Flow Filter Coating for Sub-23 Nm Nanoparticle Emissions
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Solution Overview
Problem
Existing exhaust aftertreatment systems struggle to effectively inhibit the emission of very fine nano-particles smaller than 23 nanometers, particularly as regulations tighten to include smaller particle sizes, such as PN10-based emissions standards.
Innovation Solution
A wall-flow filter with a mixed metal oxide particle deposition comprising ceria, zirconia, and optionally alumina, applied on or within the filter walls, inhibits the formation and emission of nano-particles by interacting with gaseous hydrocarbon species to prevent nucleation, without using precious metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precious metals are used in particle deposition to inhibit nano-particle emission, then emissions control effectiveness is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent replaces expensive precious metals with inexpensive mixed metal oxide particles (ceria, zirconia, alumina) that can be applied as a coating on the filter walls. This substitution dramatically reduces manufacturing cost while maintaining the functional capability to inhibit nano-particle formation through catalytic interaction with hydrocarbon species.
Solution Approach 2:
The patent changes the chemical composition parameters of the particle deposition material from traditional precious metals to a specific mixture of metal oxides (ceria-containing material combined with zirconia and/or alumina). This parameter change enables cost reduction while preserving the catalytic function needed for emissions control.
2Reliability
If precious metals are used in particle deposition to inhibit nano-particle emission, then emissions control effectiveness is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive precious metals with inexpensive inexpensive mixed metal oxide particles (ceria, zirconia, alumina) that can be applied as a coating on the filter walls. This substitution dramatically reduces manufacturing cost while maintaining the functional capability to inhibit nano-particle formation through catalytic interaction with hydrocarbon species.
Solution Approach 2:
The patent extracts and removes the precious metal component from the particle deposition formulation, retaining only the essential metal oxide particles needed for catalytic function. This extraction eliminates the cost burden of precious metals while preserving the core emissions control mechanism.
3Quantity of substance
If traditional filtration methods are used, then larger particulate matter is captured, but very fine nano-particles smaller than 23 nanometers are not effectively inhibited
Solution Approach 1:
The patent employs a composite particle deposition material consisting of multiple metal oxides (ceria-containing material combined with zirconia and/or alumina) applied on the filter walls. This composite structure provides both physical filtration of larger particles and catalytic inhibition of nano-particle formation, addressing both size ranges effectively.
Solution Approach 2:
The patent applies different functional properties to different locations: the bulk filter material provides physical filtration for larger particles, while the mixed metal oxide coating on the inner surface provides catalytic inhibition specifically for nano-particle formation. This local differentiation of function solves the multi-scale particle control problem.
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 effectively reduces the release of nano-particles smaller than 23 nanometers, achieving compliance with stringent emissions standards without the need for precious metals, thereby enhancing filtration efficiency and reducing emissions.
Implementation Method 1
interacting at least some of the gaseous hydrocarbon species collected in the filter with particles of a mixed metal oxide particle deposition at or downstream of the filter to inhibit creation of very fine nanoparticles
Data Source
AI summary
A wall-flow filter for inhibiting the emission of very fine nano-particles. The wall-flow filter includes a honeycomb body including an intersecting array of filter walls formed of a porous material and defining channels extending through the honeycomb body between an inlet face and an outlet face of the filter. The channels comprise a plurality of inlet channels that are open at the inlet face and plugged at the outlet face and a plurality of outlet channels that are open at the outlet face and plugged at the inlet face. A mixed metal oxide particle deposition is located on and/or in the filter walls of the wall-flow filter. The mixed metal oxide particle deposition comprises precious metals in an amount of less than 0.1 wt %.