Catalyzed Particulate Filter Support for Catalyst Loading
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Solution Overview
Problem
Catalyzed particulate filters face challenges in minimizing back pressure while ensuring sufficient catalyst contact time and loading for efficient catalytic reactions, as increased cell density reduces wall thickness and filter performance.
Innovation Solution
The design incorporates a support within the channels of a catalyzed particulate filter, with different catalysts coated on the walls and supports, allowing for a longer contact time and increased catalyst loading without significantly increasing back pressure by maintaining wall thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a thick catalyst coating is applied on the porous wall, then the catalyst loading is increased, but the micropores are blocked and back pressure increases
Solution Approach 1:
The catalyst coating is divided into multiple layers with different functions: a first catalyst layer (e.g., Pt) applied to the porous wall for initial catalytic activity, and a second catalyst layer (e.g., Pd) applied over it for additional catalytic function. This segmentation allows sufficient catalyst loading without excessive thickness in any single layer, preventing complete pore blockage while maintaining low back pressure.
2Quantity of substance
If the cell density is increased to increase the surface area for catalyst coating, then the catalyst loading is increased, but the wall thickness is reduced and filter performance deteriorates
Solution Approach 1:
Instead of increasing cell density (two-dimensional approach), the patent applies catalyst coating in multiple layers (three-dimensional approach) on the existing wall surface. This allows increased catalyst loading volume without changing the wall thickness or cell density, thereby maintaining filter performance while achieving sufficient catalyst quantity.
3Stress or pressure
If the fluid passes fast through the porous wall due to pressure difference, then the back pressure is minimized, but the contact time between catalyst and fluid is short and catalytic reaction efficiency is reduced
Solution Approach 1:
The patent changes the chemical parameters of the catalyst coating by applying multiple catalyst layers with different compositions and properties. The first layer (e.g., Pt) and second layer (e.g., Pd) have different catalytic activities and affinities for reactants, which modifies the fluid-catalyst interaction dynamics. This allows sufficient contact time for efficient catalytic reactions even with fast fluid flow through the porous wall, maintaining low back pressure.
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 enhances filter and catalyst performance by providing a larger contact area and extended NOx conversion temperature range while minimizing back pressure, achieving efficient catalytic reactions and NOx conversion efficiency.
Implementation Method 1
at least two kinds of catalysts are coated on at least one inside wall of the inlet channel, at least one inside wall of the outlet channel or both surfaces of the support
Data Source
AI summary
A catalyzed particulate filter may include at least one inlet channel extending in a longitudinal direction, and having a first end into which fluid flows and a second end which is blocked; at least one outlet channel extending in a longitudinal direction, and having a first end which is blocked and a second end through which the fluid flows out; at least one wall that defines the boundary between adjacent inlet and outlet channels and that extends in a longitudinal direction; and at least one support positioned within at least one of the at least one inlet channel and the at least one outlet channel.