Porous Catalyst Layer in Exhaust Gas Filters for Low Pressure Loss
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Solution Overview
Problem
The formation of a catalyst layer on an exhaust gas purification filter leads to reduced gas permeability and increased pressure loss, affecting fuel economy, while the need for improved PM burning reactivity requires a higher catalyst layer coating, creating a trade-off between these two factors.
Innovation Solution
The catalyst layer is designed with a high ratio of large pores, enhancing gas permeability and suppressing pressure loss, while also functioning as a filtration layer to promote PM collection and improve burning quality, with a multiple pore structure for precise PM collection estimation and reduced pressure loss hysteresis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coating amount of the catalyst layer per unit volume is increased to improve PM burning reactivity, then the burning reactivity of PM is improved, but the gas permeability of the catalyst layer is reduced and pressure loss increases
Solution Approach 1:
The catalyst layer is designed with a porous structure containing both large pores (first pores) and small pores (second pores). The large pores constitute the framework and provide excellent gas permeability to reduce pressure loss, while the small pores distributed within the framework increase the surface area for PM-catalyst contact, improving burning reactivity without significantly increasing pressure loss.
Solution Approach 2:
The catalyst layer combines two types of pores with different functions: large pores for gas flow and small pores for PM collection and catalytic reaction. This composite pore structure allows the catalyst layer to simultaneously achieve high gas permeability and high PM burning efficiency.
2Loss of energy
If the coating amount of the catalyst layer per unit volume is reduced to suppress pressure loss, then the pressure loss is reduced, but the burning reactivity of PM deteriorates
Solution Approach 1:
The catalyst layer is designed with a porous structure containing both large pores (first pores) and small pores (second pores). The large pores constitute the framework and provide excellent gas permeability to reduce pressure loss, while the small pores distributed within the framework increase the surface area for PM-catalyst contact, improving burning reactivity without significantly increasing pressure loss.
Solution Approach 2:
The catalyst layer combines two types of pores with different functions: large pores for gas flow and small pores for PM collection and catalytic reaction. This composite pore structure allows the catalyst layer to simultaneously achieve high gas permeability and high PM burning efficiency.
3Reliability
If a catalyst layer is formed on the base to improve PM collection, then PM burning quality is improved, but the gas permeability of the catalyst layer is reduced
Solution Approach 1:
The catalyst layer is designed with a porous structure containing both large pores (first pores) and small pores (second pores). The large pores constitute the framework and provide excellent gas permeability to reduce pressure loss, while the small pores distributed within the framework increase the surface area for PM-catalyst contact, improving burning reactivity without significantly increasing pressure loss.
Solution Approach 2:
The catalyst layer combines two types of pores with different functions: large pores for gas flow and small pores for PM collection and catalytic reaction. This composite pore structure allows the catalyst layer to simultaneously achieve high gas permeability and high PM burning efficiency.
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 design ensures excellent gas flow path, reduced pressure loss, improved PM collection efficiency, and enhanced PM burning quality, allowing precise regeneration control and balanced suppression of pressure loss and PM collection.
Implementation Method 1
The catalyst layer has first pores and second pores, in which an average pore size of the first pores is 0.1 μm or more and a pore volume of the first pores is four times or more of a pore volume of the second pores
Implementation Method 2
the catalyst layer functions as a filtration layer in the exhaust gas purification filter. That is, the intrusion of PM into the pores of the filter is suppressed since the catalyst layer exhibits a PM collection function
Implementation Method 3
the contact between PM and the metal catalyst is improved with the formation of pores having a prescribed size in the catalyst layer to increase PM purification efficiency
Data Source
Figure 1~2
Figure 3
Figure 4(a)~4(d)
AI summary
Provided is an exhaust gas purification filter that suppresses an increase in pressure loss associated with the formation of a catalyst layer and is excellent in PM burning quality. The exhaust gas purification filter according to the present invention includes a base and a catalyst layer provided on the base. The catalyst layer contains a carrier and a metal catalyst. Large pores having a circle equivalent diameter greater than 5μιη occupy, when an area of the catalyst layer is 100% in an electron microscope observation image of a cross section of the catalyst layer, 45% or more of the area.