Graded Noble Metal Catalytic Coating for Exhaust Treatment
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Solution Overview
Problem
Current catalysts for treating internal combustion engine exhaust gases are not sufficiently efficient in reducing pollutants like hydrocarbons, carbon monoxide, and nitrogen oxides, which necessitate the development of more effective catalytic solutions.
Innovation Solution
A catalytic article with a graded noble metal component distribution, where the concentration of noble metals like platinum or palladium is higher towards the outer surface, is applied to a substrate using a combination of micron-scaled and nano-scaled support particles, creating a bimodal particle size distribution and optimized pH treatment for enhanced catalytic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts with uniform noble metal distribution are used, then the catalyst structure is simple and easy to manufacture, but the catalytic efficiency in reducing pollutants is insufficient
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of noble metals within the catalytic coating, specifically concentrating them in the outer region where they directly contact exhaust gases. This gradient distribution optimizes catalytic activity at the gas-coating interface while maintaining structural integrity throughout the coating depth.
Solution Approach 2:
The patent transitions from a uniform two-dimensional distribution to a three-dimensional gradient distribution of noble metals within the catalytic coating. By varying the concentration of noble metals through the thickness of the coating (from inner surface to outer surface), the invention creates a depth-dependent composition that enhances overall catalytic performance.
2Productivity
If noble metal concentration is increased throughout the entire catalytic coating, then catalytic performance improves, but the cost of the catalyst increases significantly
Solution Approach 1:
The patent concentrates noble metals specifically in the outer region of the catalytic coating where they are most needed for catalytic reactions with exhaust gases. The inner region contains lower noble metal concentration, reducing overall noble metal content while maintaining high catalytic efficiency at the active surface.
Solution Approach 2:
The patent applies noble metals partially and strategically only where they provide maximum catalytic benefit - specifically in the outer region of the coating that contacts exhaust gases. This partial concentration approach avoids the excessive use of noble metals throughout the entire coating thickness, optimizing the balance between performance and cost.
3Productivity
If a gradient distribution of noble metals is implemented, then catalytic efficiency is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent implements a gradient distribution of noble metals by controlling and varying the concentration parameter through the thickness of the catalytic coating. This parameter change creates a continuous or stepwise gradient from the inner surface to the outer surface, optimizing catalytic performance while using standard coating techniques.
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 catalytic article demonstrates improved conversion of CO and reduced NOx emissions, outperforming standard coatings by concentrating noble metals on the surface exposed to exhaust gases, thereby enhancing the treatment efficiency of engine exhaust pollutants.
Implementation Method 1
Catalysts useful in treating exhaust gases of internal combustion engines include platinum group metals (PGM), for instance via oxidation of hydrocarbons and carbon monoxide
Implementation Method 2
the catalytic layer comprises a noble metal component on support particles where the concentration of the noble metal component towards the outer surface is greater than the concentration towards the inner surface
Implementation Method 3
applying the second mixture to the micro-particle layer and calcining the substrate
Data Source
AI summary
Catalytic articles comprising a substrate having a catalytic coating thereon, the catalytic coating comprising a catalytic layer having a thickness and an inner surface proximate to the substrate and an outer surface distal to the substrate; where the catalytic layer comprises a noble metal component on support particles and where the concentration of the noble metal component towards the outer surface is greater than the concentration towards the inner surface are highly effective towards treating exhaust gas streams of internal combustion engines. The articles are prepared via a method comprising providing a first mixture comprising micron-scaled support particles and applying the first mixture to a substrate to form a micro-particle layer; providing a second mixture comprising nano-scaled support particles and a noble metal component having an initial pH and applying the second mixture to the micro-particle layer and calcining the substrate.