Honeycomb Catalyst Coating for Low Pressure-Loss PM Filtration
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Solution Overview
Problem
Exhaust gas purification filters experience high resistance and pressure loss due to the accumulation of particulate matter (PM), leading to poor mileage and increased pressure loss over time.
Innovation Solution
The exhaust gas purification catalyst device features a honeycomb substrate with porous partition walls and an inlet side coat layer that is only present on the surface sides of inlet side cells, extending to a depth of 70% of the substrate length and 30% of the partition wall thickness, with through-pores having a diameter of 4 µm to 9 µm, ensuring efficient PM collection and reduced pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a honeycomb structure with porous partition walls is used for exhaust gas purification, then PM collection efficiency is improved, but pressure loss increases due to PM accumulation
Solution Approach 1:
The patent applies local quality by creating a coat layer with specific pore size distribution (4-9 μm through-pores) only in the inlet side cells, while the outlet side cells maintain the original partition wall structure. This localized modification optimizes PM collection at the inlet without compromising overall flow characteristics, achieving high PM collection efficiency while controlling pressure loss.
Solution Approach 2:
The patent utilizes porous materials by forming a coat layer with controlled porosity and specific through-pore diameter (4-9 μm) on the partition walls. The porous structure allows selective PM trapping while maintaining gas permeability, resolving the contradiction between PM collection efficiency and pressure loss by optimizing the pore size distribution.
2Reliability
If the coat layer extends deeper into the partition wall, then PM collection efficiency improves, but pressure loss increases
Solution Approach 1:
The patent specifies that the coat layer should extend to a depth of 30% or more but 70% or less of the partition wall thickness. This controlled depth creates local quality optimization where sufficient PM collection occurs in the region where PM concentration is highest (near the inlet), while maintaining adequate flow paths deeper in the wall to prevent excessive pressure loss.
Solution Approach 2:
The patent applies partial action by limiting the coat layer depth to 30-70% of partition wall thickness rather than extending through the entire wall. This partial penetration is sufficient to capture PM in the critical inlet region while leaving the deeper regions open for gas flow, balancing PM collection efficiency with pressure loss control.
3Reliability
If through-pores with diameter of 4 µm to 9 µm are provided, then PM collection efficiency is improved, but catalyst surface area is reduced
Solution Approach 1:
The patent applies local quality by concentrating the through-pore structure (4-9 μm) specifically in the inlet side cells where PM collection is most critical, while maintaining catalyst coating on the outlet side cells and deeper regions of the partition walls. This spatial differentiation allows optimized PM collection at the inlet without significantly compromising overall catalyst surface area.
Solution Approach 2:
The patent segments the honeycomb structure into inlet side cells and outlet side cells with different functional characteristics. The inlet side cells feature the through-pore coat layer for PM collection, while the outlet side cells maintain the traditional catalyst-coated structure, allowing each segment to optimize its specific function without compromising the other.
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 device maintains low pressure loss and inhibits increases in pressure loss even after prolonged use by effectively trapping PM, allowing for continuous operation without significant blockage of pores.
Implementation Method 1
a plurality of cells partitioned by porous partition walls... exhaust gas that has flowed into the inlet side cells passes through the partition walls
Implementation Method 2
an inlet side coat layer that is only present in the surface sides of the partition walls of the inlet side cells... effectively trapping PM
Data Source
Figure 1~2(c)
Figure 3
Figure 4(a)~4(d)
AI summary
An exhaust gas purification catalyst device 100 includes a honeycomb base material 10 and an inlet-side coat layer 20, wherein: the honeycomb base material 10 includes a plurality of cells 30 partitioned by porous partition walls, the plurality of cells 30 including inlet-side cells 31 and outlet-side cells 32 and being configured such that exhaust gas that has flowed into the inlet-side cells 31 passes through the partition walls and is exhausted from the outlet-side cells 32; and the inlet-side coat layer 20 is present on the surface sides of the partition walls of the inlet-side cells 31, with the proportion of 4-9 µm through-pores in the through-pore diameter distribution of the partition walls being at least 80 vol%, and the peak pore diameter measured using a mercury porosimeter being at least 3.0µm greater than the peak through-pore diameter measured using a perm porometer.