Exhaust Catalyst Coating High-Aspect-Ratio Pores
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Solution Overview
Problem
In dual catalyst systems for exhaust gas purification, there is a trade-off between heat resistance and purification performance due to reduced gas diffusivity caused by increased catalyst coating, particularly under high intake air mass conditions, leading to reduced NOx conversion efficiency.
Innovation Solution
A catalyst coating with high-aspect-ratio pores, oriented at specific angles, and a porosity range of 50-80% is used in the startup catalyst, enhancing gas diffusivity while maintaining sufficient heat resistance and purification performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the amount of catalyst coating is increased to improve heat resistance, then heat resistance is improved, but gas diffusivity deteriorates leading to reduced purification performance
Solution Approach 1:
The patent applies porous materials by forming a catalyst coating layer with controlled porosity (50-80%) containing high-aspect-ratio pores (aspect ratio ≥5). These pores create efficient gas diffusion pathways that maintain high gas diffusivity even when the coating layer has sufficient thickness for heat resistance, thus resolving the contradiction between heat resistance and purification performance
Solution Approach 2:
The patent changes physical parameters by controlling the porosity range (50-80%) and the aspect ratio of pores (≥5), as well as the orientation distribution of pores. These parameter changes enable the catalyst coating to achieve both sufficient heat resistance through adequate thickness and maintained gas diffusivity through optimized pore structure
2Temperature
If the catalyst coating thickness is increased to improve heat resistance, then heat resistance is improved, but pressure loss increases leading to reduced engine output power and fuel efficiency
Solution Approach 1:
By incorporating high-aspect-ratio pores with aspect ratio of 5 or more into the catalyst coating layer, the patent creates efficient gas transport channels that reduce flow resistance. This allows the coating to maintain sufficient thickness for heat resistance while minimizing pressure loss and associated energy losses in fuel efficiency
3Reliability
If conventional void formation methods are used to enhance gas diffusivity, then gas diffusivity is improved, but catalyst layer strength decreases and void linkage is poor
Solution Approach 1:
The patent employs porous materials with specifically controlled pore characteristics (high aspect ratio ≥5, porosity 50-80%) that provide both excellent gas diffusivity and structural integrity. The high-aspect-ratio pores create effective diffusion pathways while their controlled distribution and morphology maintain catalyst layer strength and improve void linkage, overcoming the limitations of conventional void formation methods
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 significantly enhances gas diffusivity and maintains NOx conversion efficiency even under high intake air mass conditions, balancing heat resistance and purification performance.
Implementation Method 1
enhance diffusivity of exhaust gas in the catalyst coating layer
Data Source
Figure 1(A)~1(C)
Figure 2
Figure 3
AI summary
The present invention is directed to address the following problem: in an exhaust gas purification catalyst comprising a dual catalyst of a combination of a startup catalyst and an underfloor catalyst, reduction in the gas diffusivity of the startup catalyst results in reduction in the use efficiency of a catalytic active site, resulting in reduction in purification performance. The present invention relates to an exhaust gas purification catalyst comprising a dual catalyst of a combination of a startup catalyst having a catalyst coating where a large number of voids are included and an underfloor catalyst, wherein high-aspect-ratio pores having an aspect ratio of 5 or more account for a certain rate or more of the whole volume of the voids, to thereby enhance the purification performance of the catalyst.