Wall Flow Catalyst Pore Distribution for PM Collection
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Solution Overview
Problem
Existing exhaust gas purification catalysts with a wall flow structure face challenges in maintaining particulate matter (PM) collection performance while improving purification efficiency, as the catalyst layer can block pores and reduce PM collection rates when not optimally distributed.
Innovation Solution
The catalyst layer is strategically placed in large pores, with specific filling rates in different pore diameter ranges, ensuring that at least 50% of the partition wall thickness is coated, and the slurry viscosity is adjusted to preferentially enter large pores, maintaining PM collection performance while enhancing exhaust gas purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a catalyst layer is provided in pores of the partition walls, then exhaust gas purification performance is improved, but PM collection performance is adversely influenced due to pore blocking
Solution Approach 1:
The patent applies local quality by creating different catalyst layer filling rates in different pore diameter ranges. Small pores (5-10 μm) have a filling rate of 30-70%, medium pores (10-20 μm) have a filling rate of 10-50%, and large pores (20 μm or more) have a filling rate of 0-30%. This non-uniform distribution optimizes both PM collection and exhaust gas purification by preserving small pores for particle filtration while providing sufficient catalyst surface area in larger pores for chemical reactions.
2Productivity
If the catalyst layer is disposed preferentially in large pores, then exhaust gas purification performance is improved, but PM collection performance must be maintained
Solution Approach 1:
The patent applies parameter changes by controlling the filling rate of the catalyst layer in different pore diameter ranges. Specifically, small pores (5-10 μm) maintain a filling rate of 30-70%, medium pores (10-20 μm) maintain a filling rate of 10-50%, and large pores (20 μm or more) maintain a filling rate of 0-30%. This parameter optimization ensures that small pores remain available for PM collection while large pores provide sufficient catalyst surface area for exhaust gas purification.
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 improves both PM collection and exhaust gas purification performance by optimizing catalyst distribution, reducing pressure loss, and increasing the volume of small pores effective for PM collection, resulting in higher overall filtration efficiency.
Implementation Method 1
a catalyst layer that is formed in a region of at least 50% of the thickness of the partition wall from a surface of the partition wall that is in contact with at least one cell of the inlet side cell and the outlet side cell, and held on the surface of internal pores in the partition wall in the region
Implementation Method 2
exhaust gas flowing from the cell inlets passes through porous cell partition walls while moving in the cells and is discharged to the cell outlets. Thus, while exhaust gas passes through the porous cell partition walls, particulate matter is collected in the pores in the partition walls
Data Source
AI summary
Provided is an exhaust gas purification catalyst body that can improve exhaust gas purification performance while maintaining favorable PM collection performance. The exhaust gas purification catalyst body includes a base of a wall flow structure having an inlet side cell, an outlet side cell, and porous partition wall, and a catalyst layer that is formed in the partition wall that is in contact with the inlet side cell or the outlet side cell. The catalyst layer is formed in a region of at least 50% of the thickness of the partition wall from a surface of the partition wall, and held on the surface of internal pores in the partition wall in the region.