Single-Layer Oxidation Catalyst with Palladium Gradient
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Solution Overview
Problem
Existing diesel oxidation catalysts with layered arrangements are costly and complex to produce, increasing the likelihood of errors and production costs, while aiming to achieve efficient conversion of pollutants like CO, HCs, and NOx in exhaust gases.
Innovation Solution
A single-layer oxidation catalyst with a non-uniform distribution of palladium through its thickness, where at least 60% of the palladium is distributed between the surface and halfway through the layer, utilizing a refractory oxide support material and platinum, allows for efficient conversion of pollutants without the complexity and cost of multi-layered catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-layered catalyst arrangements are used to optimize reactivity and minimize degradation, then catalytic performance is improved, but production cost and device complexity increase
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of palladium within a single catalyst layer. The palladium concentration varies through the thickness of the layer, with higher concentration at the exposed surface and lower concentration near the substrate. This gradient structure provides different regions with optimized properties: the surface region offers high reactivity for CO oxidation, while the deeper regions provide structural support and reduce overall noble metal content, thereby achieving improved catalytic performance without multi-layer complexity
Solution Approach 2:
The patent changes the concentration parameter of palladium distribution within the catalyst layer. Instead of uniform distribution, the palladium concentration is varied through the thickness of the layer, creating a gradient from high concentration at the surface to low concentration at the substrate interface. This parameter change optimizes the balance between reactivity (requiring high Pd content) and cost/complexity (reducing total Pd and eliminating multi-layer structures)
2Productivity
If multi-layered catalyst arrangements are used to optimize reactivity, then catalytic activity is improved, but production cost increases
Solution Approach 1:
The patent merges the functions of multiple catalyst layers into a single layer with non-uniform composition. Instead of stacking separate layers with different noble metal compositions, the invention combines these functions into one integrated layer where palladium concentration varies through the thickness. This merging maintains the catalytic activity benefits of multi-layer designs while simplifying the manufacturing process and reducing production costs associated with multiple deposition steps and quality control
3Device complexity
If non-uniform distribution of palladium is used in a single layer, then production complexity is reduced, but achieving optimal reactivity distribution becomes more difficult
Solution Approach 1:
The patent applies preliminary action by incorporating palladium into the washcoat slurry before application to the substrate. The palladium is pre-mixed with the washcoat material at controlled concentrations, ensuring uniform distribution within the washcoat matrix before drying and calcination. This preliminary mixing approach simplifies the manufacturing process compared to post-application metal deposition methods, as it achieves the desired non-uniform distribution through single-step slurry preparation rather than requiring complex multi-step deposition and sintering processes
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 single-layer catalyst achieves improved performance in converting CO, HCs, and NOx, with a low CO T50, maintaining the benefits of multi-layered catalysts while simplifying production and reducing costs.
Implementation Method 1
an oxidation catalyst having a single catalyst layer... the catalyst layer has a non-uniform distribution of the first noble metal, which is palladium... able to oxidise carbon monoxide (CO) to carbon dioxide (CO2) and hydrocarbons (HCs) to water (H2O) and carbon dioxide (CO2)
Implementation Method 2
an oxidation catalyst for treating an exhaust gas from the engine... oxidise nitrogen monoxide (NO) to nitrogen dioxide (NO2)
Data Source
Figure 1
Figure 2~3
AI summary
An oxidation catalyst for treating an exhaust gas produced by a combustion engine, wherein the oxidation catalyst comprises a substrate and a catalyst layer, wherein the catalyst layer comprises: a first support material; a first noble metal; and a second noble metal; wherein the catalyst layer is disposed on a surface of the substrate, and the catalyst layer has a non-uniform distribution of the first noble metal in a direction perpendicular to the surface of the substrate. The oxidation catalyst can be used to oxidise carbon monoxide (CO), hydrocarbons (HCs) and also oxides of nitrogen (NOx) in such an exhaust gas.