Catalyzed Particulate Filter Coating Density for PM Capture
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing particulate filters face a significant increase in pressure loss due to the reduction in pore diameters required for high PM capturing rates, which existing technologies fail to adequately address.
Innovation Solution
A catalyzed particulate filter with a porous support and a catalytic layer having a density of 2.0 g/cm3 or higher, combined with a catalyst material containing Ce-containing Zr-based or Ce-free Zr-based composite oxides, and optionally an alumina-based composite oxide, to maintain a sufficient catalyst amount while suppressing pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pore diameters in the partitions are reduced to achieve high PM capturing rates, then the PM capturing rate is improved, but the pressure loss increases significantly
Solution Approach 1:
The patent utilizes a porous support structure with controlled pore diameters (5-15 μm) to capture PM while maintaining acceptable pressure loss. The porous material allows selective filtration based on pore size, achieving high capturing rates without excessive pressure drop across the filter.
Solution Approach 2:
The patent optimizes multiple parameters including pore diameter (5-15 μm), cell diameter (150-300 μm), and wall thickness (30-60 μm) of the honeycomb structure to balance PM capturing performance with pressure loss characteristics. By carefully selecting and combining these parameters, the filter achieves high efficiency while minimizing energy loss.
2Reliability
If a catalyst coating layer is provided on the filter to promote PM combustion and exhaust gas purification, then the combustion and purification functions are improved, but the pressure loss increases due to reduction in flow path
Solution Approach 1:
The catalyst coating is applied selectively on the inner walls of the honeycomb cells and partition pores where exhaust gas flows, rather than uniformly across the entire filter surface. This localized application provides catalytic function exactly where needed for PM combustion while minimizing the overall coating thickness and its impact on flow resistance.
Solution Approach 2:
The catalyst coating layer serves multiple functions simultaneously: it promotes PM combustion, purifies harmful exhaust gas components (HC, CO, NOx), and maintains structural integrity of the filter. This multi-functionality reduces the need for separate components that would increase pressure loss.
3Reliability
If the catalyst coating layer is made thicker to ensure sufficient catalyst amount, then the catalytic performance is improved, but the pressure loss increases
Solution Approach 1:
The catalyst coating utilizes a porous structure with high surface area to volume ratio, allowing sufficient catalytic active sites to be packed into a thin layer. This porous catalyst layer provides high catalytic performance while maintaining thin thickness to minimize pressure drop across the filter.
Solution Approach 2:
The catalyst coating is formulated as a composite material combining catalyst particles with a porous support matrix, creating a structure that maximizes catalytic activity per unit thickness. This composite structure allows achieving sufficient catalyst amount in a thin layer, reducing the impact on exhaust gas flow and pressure loss.
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 achieves both high particulate capturing rates and effective suppression of pressure loss, ensuring efficient PM combustion and exhaust gas purification.
Implementation Method 1
a filter body on which a PM combustion catalyst for promoting combustion of the PM is supported
Implementation Method 2
When the amount of the PM captured by the filter increases, the PM is removed by combusting the PM to regenerate the filter
Implementation Method 3
a support that is porous; and a catalytic layer provided on an exhaust gas passage wall of the support
Data Source
AI summary
A catalyzed particulate filter is a filter that is arranged in an exhaust passage of an engine and captures particulate matter in exhaust gas, and includes a support that is porous, and a catalytic layer provided on a wall surface of the support, and the catalytic layer has a density of 2.0 g/cm3 or higher.