Wall-Flow Exhaust Catalyst Layers for Heat-Resistant Purification
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Solution Overview
Problem
Existing exhaust gas purification catalysts for gasoline engines, particularly those used in GDI engines, face challenges in achieving high heat resistance and sufficient exhaust gas purification performance during high-speed driving conditions.
Innovation Solution
A wall flow structure catalyst design with specific catalyst layer configurations, including a first catalyst layer on the upstream side and a second catalyst layer on the downstream side, where the first catalyst layer has a greater pore volume and peak pore size within a specific range, and the catalyst layers contain different noble metals, enhancing heat resistance and purification efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional filter catalyst design for diesel engines is used, then PM collection function is achieved, but heat resistance is insufficient for gasoline engine combustion temperatures exceeding 1000°C
Solution Approach 1:
The patent applies local quality by creating different catalyst layer structures in different regions of the filter catalyst. Specifically, it forms a first catalyst layer on the upstream side with different pore characteristics than the second catalyst layer on the downstream side. This regional differentiation allows optimization for both high-temperature resistance (upstream) and purification efficiency (downstream), resolving the contradiction between heat resistance and purification performance.
Solution Approach 2:
The patent uses composite materials by combining multiple catalyst layers with different compositions and pore structures. The first catalyst layer contains different components than the second catalyst layer, creating a composite structure that simultaneously provides high-temperature stability and effective exhaust gas purification, thereby resolving the contradiction between heat resistance and purification performance.
2Productivity
If a single catalyst layer structure is used, then manufacturing is simplified, but exhaust gas purification performance during high-speed driving is insufficient
Solution Approach 1:
The patent applies segmentation by dividing the catalyst structure into multiple distinct layers: a first catalyst layer on the upstream side and a second catalyst layer on the downstream side. Each layer has specific pore volume characteristics optimized for different flow conditions. This segmentation enables the catalyst to effectively handle both normal and high-speed driving conditions, resolving the contradiction between purification performance and structural complexity.
3Loss of energy
If uniform pore distribution is used throughout the catalyst, then manufacturing is easier, but pressure loss increases during high-speed driving
Solution Approach 1:
The patent applies local quality by creating non-uniform pore distributions in different catalyst layers. The first catalyst layer has different pore volume characteristics than the second catalyst layer, with each layer optimized for its specific position in the exhaust flow path. This local optimization reduces pressure loss while maintaining high exhaust gas flow throughput during high-speed driving, resolving the contradiction between energy loss and productivity.
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
The design achieves improved heat resistance and exhaust gas purification performance during high-speed driving by ensuring effective contact of exhaust gases with both catalyst layers, reducing pressure loss, and optimizing pore volumes and metal distributions.
Implementation Method 1
a first catalyst layer formed on a surface of the cell partition wall that faces the inflow cell, and a second catalyst layer formed in an inner part of the cell partition wall... the first catalyst layer has a greater pore volume and exhibits a main peak of pore size within a specific range
Data Source
Figure 1~2
Figure 3~4
AI summary
A substrate (11) of an exhaust gas purification catalyst (10) includes inflow-side cells (21), outflow-side cells (22), and porous partition walls (23), each porous partition wall separating the cells (21, 22) from each other. A first catalyst portions (14) is provided at least on a portion of a side of the partition wall (23) that faces the inflow-side cell (21), the portion being located on an upstream side in an exhaust gas flow direction, and a second catalyst portion (15) is provided at least on a portion of a side of the partition wall that faces the outflow-side cell, the portion being located on a downstream side in the exhaust gas flow direction. A first pore volume is greater than a second pore volume, where the first pore volume is a pore volume of pores with a pore size of 10 µm to 18 µm, as measured on the first catalyst portions (14) and the partition walls (23) within a region where the first catalyst portions (14) are provided, and the second pore volume is a pore volume of pores with a pore size of 10 µm to 18 µm, as measured on the second catalyst portions (15) and the partition walls (23) within a region where the second catalyst portions (15) are provided. The first catalyst portion (14) exhibits the peak top of the pore size at between 20 nm and 500 nm.