Catalytic Converter with Variable Cell Density Substrate
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Solution Overview
Problem
Existing catalytic converters with uniform cell density struggle to efficiently utilize catalyst layers due to varying exhaust gas flow rates, leading to inadequate purification performance and excessive hydrogen sulfide emission.
Innovation Solution
A catalytic converter with a substrate having a center region of higher cell density and a peripheral region of lower cell density, where the catalyst layer lengths are optimized to ensure equal or shorter lengths in the longitudinal direction, utilizing a two-layer structure with noble metal catalysts like Pd, Pt, and Rh, to enhance purification performance while reducing hydrogen sulfide emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform cell density substrate is used, then the structure is simple and easy to manufacture, but the catalyst layers cannot be sufficiently utilized due to varying exhaust gas flow rates
Solution Approach 1:
The substrate is designed with different cell densities in different regions: a first cell density in the center region and a second cell density in the peripheral region. This local differentiation allows the center region (with higher cell density) to handle the higher exhaust gas flow rate, while the peripheral region (with lower cell density) handles the lower flow rate, thereby optimizing catalyst layer utilization across the entire substrate surface.
2Reliability
If the amount of noble metal catalyst is increased to improve purification performance, then exhaust gas purification performance is improved, but hydrogen sulfide emission increases
Solution Approach 1:
The catalyst layer is designed with different lengths in different regions: a first length in the center region and a second length in the peripheral region. By optimizing the catalyst layer length distribution rather than uniformly increasing the amount of noble metal catalyst throughout, the patent achieves improved purification performance while controlling hydrogen sulfide emission. The longer catalyst layer in the center region (where flow rate is higher) provides sufficient purification, while the shorter length in the peripheral region reduces overall noble metal usage and hydrogen sulfide production.
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 efficiently utilizes catalyst layers for superior exhaust gas purification and effectively suppresses hydrogen sulfide emission, balancing purification performance and emission control.
Implementation Method 1
catalyst layers formed of a noble metal catalyst such as palladium or platinum are formed on cell wall surfaces of a substrate including plural cells
Implementation Method 2
CO is converted into CO2, NOx is converted into N2 and O2, and VOC is burned to produce CO2 and H2O
Implementation Method 3
VOC is burned to produce CO2 and H2O
Data Source
AI summary
Provided is a catalytic converter in which the entire catalyst constituting the catalytic converter can be efficiently utilized to purify exhaust gas, and the emission of hydrogen sulfide can be suppressed.A catalytic converter 10 includes catalyst layers 2A, 2B formed of a noble metal catalyst that are formed on cell wall surfaces of a substrate 1 having a cell structure in a longitudinal direction of the substrate 1 in which gas flows, in which the substrate 1 has a center region 1A having a relatively high cell density and a peripheral region 1B having a relatively low cell density, and lengths of the catalyst layers 2A, 2B of the center region 1A and the peripheral region 1B in the longitudinal direction are the same as each other, or the length of the catalyst layer 2B in the longitudinal direction is shorter than that of the catalyst layer 2A.