Honeycomb Substrate Inflow Cell Side Catalyst Layer for Pressure Loss
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Solution Overview
Problem
The existing exhaust gas purification devices with catalysts in wall flow filters experience a degradation in gas permeability, leading to increased pressure loss due to the presence of catalysts in the porous partition walls of honeycomb substrates.
Innovation Solution
The implementation of an exhaust gas purification device with an inflow cell side catalyst layer disposed on the surface of the inflow cell side from the inflow side end to a position close to the outflow side end of the partition wall, where the gas permeability of the outflow side partition wall region is higher than that of the catalyst-disposed partition wall portion, reducing pressure loss and enhancing purification performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a catalyst is provided in the porous partition wall of the honeycomb substrate, then the purification performance is improved, but the gas permeability of the partition wall is degraded, leading to increased pressure loss
Solution Approach 1:
The partition wall is divided into two distinct regions: a catalyst-disposed region containing the catalyst layer for purification, and a catalyst-free region maintaining high gas permeability. This segmentation allows each region to perform its specific function optimally without compromising the other, resolving the contradiction between purification performance and gas permeability.
Solution Approach 2:
Different regions of the partition wall are assigned different properties: the catalyst-disposed region has catalytic activity for harmful component removal, while the catalyst-free region has enhanced porosity and gas permeability. This local differentiation enables the partition wall to simultaneously achieve purification function and maintain low pressure loss.
2Object-affected harmful factors
If a catalyst layer is disposed on the partition wall surface, then harmful components are removed from exhaust gas, but the pressure loss increases due to reduced gas permeability
Solution Approach 1:
The partition wall is segmented into a catalyst-disposed region for harmful component removal and a catalyst-free region with higher gas permeability. By spatially separating the catalytic function from the flow path, the system achieves purification without excessive pressure loss.
Solution Approach 2:
The gas permeability parameter is changed spatially across the partition wall by creating a catalyst-free region with higher porosity. This parameter variation allows the system to optimize both purification (in the catalyst region) and pressure loss (in the catalyst-free region).
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 effectively suppresses the increase in pressure loss and improves the purification performance by optimizing gas flow and catalyst interaction, while also reducing catalyst costs by minimizing the need for catalyst layers in the outflow cell side regions.
Implementation Method 1
The harmful components can be removed from the exhaust gas by a filter over which a catalyst, such as a noble metal catalyst, is applied
Implementation Method 2
When the exhaust gas passes through the partition wall, the PM is trapped inside pores of the partition wall
Data Source
AI summary
An exhaust gas purification device that allows suppressing an increase in pressure loss is provided. The exhaust gas purification device of the present disclosure includes a honeycomb substrate and an inflow cell side catalyst layer. The substrate includes a porous partition wall which defines inflow cells and outflow cells extending from an inflow side end to an outflow side end. The inflow cell side catalyst layer is disposed on a surface on the inflow cell side in an inflow cell side catalyst region from an inflow side end to a position close to an outflow side end of the partition wall. The permeability of a portion including an outflow side region from the position to the outflow side end of the partition wall is higher than a gas permeability of a portion including the inflow cell side catalyst region of the partition wall and the inflow cell side catalyst layer.