Wall-Flow Catalyst Layer Layout for Low Pressure Loss Purification
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Solution Overview
Problem
Existing wall flow type exhaust gas purifying catalysts face a trade-off between noxious gas purifying performance and pressure loss suppressing performance, as increasing the catalyst layer to enhance purification can lead to pore blockage and increased pressure loss.
Innovation Solution
The catalyst layer is configured with a first catalyst region on the entry side cell surface, a second catalyst region on the exit side cell surface, and an unformed region between them, allowing efficient PM removal and prevention of pore blockage, while maintaining high noxious gas purifying performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of catalyst layer formed in the pore of the partition wall is increased to improve noxious gas purification performance, then the contact frequency between catalyst layer and noxious gas component increases, but the pore may be blocked resulting in sharp increase in pressure loss
Solution Approach 1:
The patent applies local quality by creating different catalyst layer configurations in different regions of the partition wall. The first region has a catalyst layer formed on the wall surface with pores, the second region has a catalyst layer formed in the pores, and the third region has no catalyst layer. This spatial differentiation allows the pore region to provide high purification performance while the pore-free region maintains low pressure loss by preventing blockage.
2Reliability
If the catalyst layer is formed on the wall surface of the pore to increase contact frequency with noxious gas, then purification performance improves, but the pore narrows which may lead to blockage during PM collection
Solution Approach 1:
The patent segments the partition wall into three distinct regions with different catalyst layer configurations. The first region has catalyst on the wall surface for PM collection, the second region has catalyst in the pores for purification, and the third region has no catalyst to maintain open pores and prevent blockage. This segmentation allows each region to perform its specific function optimally.
Solution Approach 2:
Different regions of the partition wall are given different local qualities: the first region has wall surface catalyst for PM collection, the second region has pore-filled catalyst for purification, and the third region has no catalyst to remain pore-open. This local differentiation resolves the contradiction between purification performance and pore blockage prevention.
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 configuration ensures compatibility between high noxious gas purifying performance and low pressure loss by effectively collecting PMs in the first and unformed regions, preventing pore blockage in the second region, and maintaining catalyst contact frequency.
Implementation Method 1
a catalyst layer formed on the base material... the catalyst layer formed on the partition wall purifies the noxious gas components
Implementation Method 2
The exhaust gas fed to the exhaust gas purifying catalyst of such a structure flows into the entry side cell, and passes through the partition wall, and then is exhausted from the exit side cell. At this step, the PMs are collected to the porous partition wall
Data Source
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AI summary
The technology herein disclosed provides a wall flow type exhaust gas purifying catalyst capable of establishing the compatibility between the noxious gas purifying performance and the pressure loss suppressing performance at a high level. The exhaust gas purifying catalyst herein disclosed includes a base material 11 and a catalyst layer 20. Then, a first catalyst region 22 including the catalyst layer 20 formed therein is provided on an entry side surface 16a of a partition wall 16 of the base material 11. A second catalyst region 24 including the catalyst layer 20 formed on a wall surface 18a of a pore 18 is provided in a prescribed region from an exit side surface 16b of the partition wall toward an entry side cell 12. Further, a catalyst unformed region 30 in which a catalyst layer is substantially not formed is provided between the first catalyst region 22 and the second catalyst region 24 in the thickness direction Y of the partition wall 16. As a result of this, it is possible to prevent the deposition of PMs in the second catalyst region 24 including the catalyst layer 20 formed in the pore 18, and to establish the compatibility between the noxious gas purifying performance and the pressure loss suppressing performance at a high level.