Honeycomb Filter Catalyst Distribution for Regeneration Efficiency
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Solution Overview
Problem
Catalyst deposition and aggregation in the outer peripheral coat layer and on partition walls of honeycomb filters during regeneration can lead to catalyst deterioration, crack generation, and reduced regeneration efficiency in diesel particulate filters.
Innovation Solution
A honeycomb filter manufacturing process where a catalyst is loaded on the partition walls after grinding the outer peripheral portion, with a minimal catalyst amount in the outer peripheral coat layer, and a method to fix the catalyst using an outer peripheral coat layer, ensuring the catalyst is primarily retained on the partition walls, reducing deposition and aggregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a catalyst is loaded on the whole partition wall to effectively combust PM, then regeneration efficiency is improved, but catalyst deterioration and crack generation occur in the vicinity of the outlet side end portion due to excessive temperature rise
Solution Approach 1:
The patent applies local quality by creating distinct catalyst loading zones: the inlet side end portion has a first catalyst loading amount for effective PM combustion, while the outlet side end portion has a second catalyst loading amount that is smaller than the first. This spatial differentiation of catalyst distribution prevents excessive temperature rise and catalyst deterioration in the outlet region while maintaining high regeneration efficiency in the inlet region.
2Reliability
If the amount of catalyst is reduced to prevent catalyst deterioration and crack generation, then reliability is improved, but regeneration efficiency becomes insufficient
Solution Approach 1:
The patent resolves this contradiction by implementing non-uniform catalyst distribution where the inlet side end portion maintains a higher catalyst loading amount (first catalyst loading amount) to ensure sufficient regeneration efficiency, while the outlet side end portion uses a reduced catalyst loading amount (second catalyst loading amount) to prevent catalyst deterioration and crack generation. This localized optimization allows both high reliability and adequate productivity.
3Ease of manufacture
If a conventional manufacturing process is used where catalyst is loaded after outer peripheral coat layer is disposed, then catalyst can be loaded on partition walls, but catalyst deposits in the outer peripheral coat layer and aggregates on partition walls of outermost peripheral cells
Solution Approach 1:
The patent applies preliminary action by reversing the conventional manufacturing sequence: the outer peripheral coat layer is disposed on the outer peripheral face of the honeycomb filter BEFORE the catalyst is loaded on the partition walls. This preliminary coating prevents catalyst deposition in the outer peripheral coat layer and aggregation on the partition walls of outermost peripheral cells during the subsequent catalyst loading process, thereby improving manufacturing precision while maintaining ease of manufacture.
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
Inhibits catalyst deposition and aggregation, preventing crack generation and enhancing regeneration efficiency while minimizing production costs by maintaining a low catalyst load.
Implementation Method 1
a catalyst hardly deposits in the outer peripheral coat layer
Implementation Method 2
an oxidation type catalyst is loaded to effectively combust PM
Data Source
AI summary
A honeycomb filter including a catalyst-carrying article, and an outer peripheral coat layer disposed on an outer peripheral face of the catalyst carrying article, wherein an amount of the catalyst loaded in the outer peripheral coat layer at a position 50 μm or more apart from a boundary face between the catalyst-carrying article and the outer peripheral coat layer is 5 mass % or less when a measurement piece having a cross section where a boundary portion between the catalyst-carrying article and the outer peripheral coat layer can be observed and being obtained by embedding a resin in the boundary portion in the cross section is measured by an energy dispersive fluorescent X-ray analysis using a scanning electron microscope.