Honeycomb Filter Catalyst Distribution for NOx Purification
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Solution Overview
Problem
Existing honeycomb filters require excessive noble metal catalysts to effectively remove nitrogen compounds (NOx), unburned gases (HC), and particulate matter (PM) from exhaust gases, which is inefficient and costly due to the scarcity of these resources.
Innovation Solution
A honeycomb filter design where the catalyst is loaded such that the amount at partition-intersecting portions is smaller than at partition central portions, and the trapping layers have optimized catalyst distribution, allowing for efficient removal of target substances with a decreased overall catalyst amount, while preventing catalyst degradation and poisoning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amount of catalyst is loaded on the partition portions to remove target substances, then the exhaust gas purification performance is improved, but the cost increases and the catalyst degradation accelerates
Solution Approach 1:
The patent applies local quality by creating non-uniform catalyst distribution on the partition portions. Specifically, the catalyst amount is made smaller at partition-intersecting portions (where multiple partition walls meet) and larger at partition central portions (center of each partition wall). This localized differentiation optimizes catalyst usage by placing more catalyst where it is most needed for purification while reducing it where flow resistance is already high, thereby improving overall purification performance per unit of catalyst.
Solution Approach 2:
The patent segments the partition portions into distinct regions: partition-intersecting portions and partition central portions. By dividing the partition surface into these functional zones with different catalyst loading densities, the system achieves more efficient catalyst utilization. The segmentation allows each region to contribute optimally to target substance removal based on its local flow characteristics.
2Reliability
If uniform catalyst distribution is used on partition portions, then the manufacturing process is simple, but the exhaust gas purification efficiency is suboptimal
Solution Approach 1:
The patent implements local quality through differentiated catalyst distribution patterns. The catalyst amount is specifically controlled to be smaller at partition-intersecting portions and larger at partition central portions. This local differentiation enhances purification efficiency by matching catalyst density to local flow characteristics, creating a more effective purification system without requiring complex overall structural changes.
3Reliability
If catalyst is loaded on partition-intersecting portions with high permeation resistance, then the target substance removal is improved, but the pressure loss increases
Solution Approach 1:
The patent applies local quality by creating non-uniform catalyst distribution on the partition portions. Specifically, the catalyst amount is made smaller at partition-intersecting portions (where multiple partition walls meet) and larger at partition central portions (center of each partition wall). This localized differentiation optimizes catalyst usage by placing more catalyst where it is most needed for purification while reducing it where flow resistance is already high, thereby improving overall purification performance per unit of catalyst.
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 design enables efficient removal of NOx, HC, and PM with reduced catalyst usage, maintaining high purification performance and reducing catalyst degradation, thus aligning with future emission controls and smaller exhaust-gas purification systems.
Implementation Method 1
combustion of solid components deposited on a partition central portion, and solid components deposited on a partition-intersecting portion are burnt by utilizing high-temperature gas generated by the combustion
Implementation Method 2
catalysts for promoting combustion of trapped solid components
Implementation Method 3
catalysts for oxidizing unburned gases contained in exhaust gases
Implementation Method 4
catalysts for decomposing NOx contained in exhaust gases
Implementation Method 5
a trapping layer formed on a partition portion can prevent solid components in a fluid from entering the partition portion
Data Source
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AI summary
In a honeycomb filter 20, a catalyst is loaded on partition portions 22 and trapping layers 24 such that the catalyst amount A at a partition-intersecting portion 32 is smaller than the catalyst amount B at a partition central portion 34. The ratio A/B of the catalyst amount A to the catalyst amount B is preferably 0.30 or more and 0.90 or less. The catalyst is loaded such that the catalyst amount C at a trapping layer corner 36 is smaller than the catalyst amount D at a trapping layer central portion 38. The ratio C/D of the catalyst amount C to the catalyst amount D is preferably 0.80 or more and 0.95 or less.