Multi-Layer Catalyst Composition for Wide Lambda Range Exhaust Treatment
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Solution Overview
Problem
Existing catalytic converters struggle to effectively reduce emissions of CO, HC, and NOx across a wide lambda range (0.8<λ<1.2), particularly in motorcycles, where lambda fluctuations are greater, and fail to maintain high conversion rates in both rich and lean engine operations.
Innovation Solution
A catalytically active composition for a multilayer catalytic converter comprising an oxygen storage material with rare earth metals, noble metals like platinum, rhodium, and palladium, and aluminum oxide, with specific particle size distributions and a cerium-zirconium oxide base, is introduced. This composition is created by mixing the materials in a slurry with noble metal salts and adjusting the pH value, allowing for improved oxygen storage and catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional catalytic converters are used, then they can treat exhaust gases under stoichiometric conditions, but they fail to maintain high conversion rates across a wide lambda range including rich and lean operations
Solution Approach 1:
The patent applies parameter changes by optimizing the particle size distribution of the catalytic composition with specific d10, d50, and d90 values. This parameter optimization enables the catalyst to maintain high conversion rates across a wide lambda range from 0.8 to 1.2, resolving the contradiction between adaptability and reliability by tuning the physical parameters of the catalyst material.
Solution Approach 2:
The patent uses composite materials by combining oxygen storage material, aluminum oxide, and precious metals (platinum, rhodium, palladium) in a multi-layer structure. This composite approach enhances both the adaptability to different lambda conditions and the reliability of conversion rates, as each component contributes specific properties that work synergistically across rich and lean operations.
2Productivity
If the catalyst uses smaller particle sizes to increase surface area, then catalytic activity improves, but thermal stability decreases
Solution Approach 1:
The patent resolves this contradiction by optimizing the particle size distribution parameters (d10, d50, d90) to specific ranges. This parameter optimization balances the surface area available for catalytic reactions with the thermal stability of the material, achieving both high catalytic activity and resistance to sintering at elevated temperatures.
Solution Approach 2:
The patent applies local quality by creating a multi-layer structure with different materials and properties in different regions. The composition includes oxygen storage material, aluminum oxide, and precious metals distributed in specific layers, where each layer provides localized functions that collectively enhance both catalytic activity and thermal stability.
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 composition significantly reduces emissions of CO, HC, and NOx under lean conditions and maintains low CO2 emissions, even when the engine is running rich, with improved thermal stability and catalytic activity across varying lambda conditions.
Implementation Method 1
Three-way catalysts typically contain an oxygen reservoir that is charged with oxygen under oxidative conditions and can release oxygen again under reducing conditions.
Implementation Method 2
2 CO + O2 → 2 CO2; 2 C2H6 + 7 O2 → 4 CO2 + 6 H2O
Implementation Method 3
2 NO + 2 CO → N2 + 2 CO2
Implementation Method 4
The catalyst's function is to convert the pollutants produced during combustion—hydrocarbons (C6H6N2), carbon monoxide (CO), and nitrogen oxides (NOx)—into the non-toxic substances carbon dioxide (CO2), water (H2O), and nitrogen (N2)
Data Source
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AI summary
The present invention relates to a catalytically active composition for a multi-layer catalyst for exhaust gas aftertreatment of combustion plants and a multi-layer catalyst comprising the catalytically active composition, characterized in that the composition has a particle size d90 in the range of 10 µm to 35 µm, preferably from 15 µm to 30 µm, particularly preferably from 19 µm to 24 µm.