Ammonia Oxidation Catalyst Platinum Migration Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ammonia oxidation catalysts in diesel engine aftertreatment systems degrade over time, leading to reduced operability and ammonia slip, as they are not configured to resist operational factors that cause migration and sintering of platinum, resulting in incomplete conversion of excess ammonia.
Innovation Solution
The system includes a second oxidation catalyst layer with a platinum coating and a palladium additive, forming a bimetallic phase that stabilizes platinum and prevents its migration to the first layer, and an additional Al2O3 additive that secures platinum within the second layer, preventing sintering and maintaining catalytic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a platinum coating is applied to the oxidation catalyst support to convert excess NH3, then catalytic efficiency is improved, but platinum migrates to the first layer over time causing catalyst degradation
Solution Approach 1:
A palladium-based additive is introduced as an intermediary substance between the platinum coating and the oxidation catalyst support. This additive acts as a barrier that prevents platinum atoms from migrating to the first layer while still allowing the platinum to maintain its catalytic function for NH3 conversion. The palladium additive effectively mediates the interaction between platinum and the support structure, stabilizing the platinum in place.
Solution Approach 2:
The invention creates a composite catalyst structure combining platinum, palladium, and oxidation catalyst support materials. The bimetallic phase formed by platinum and palladium, along with the aluminum oxide support, creates a stable composite material where platinum is anchored to the support through the palladium intermediate layer, preventing migration while maintaining high catalytic activity.
2Productivity
If platinum is used to convert excess NH3, then ammonia oxidation efficiency is improved, but platinum sinters over time reducing catalyst operability
Solution Approach 1:
The palladium-based additive serves as a protective intermediary that prevents direct contact and thermal interaction between platinum particles and the oxidation catalyst support during high-temperature operation. This intermediary layer reduces thermal diffusion and sintering of platinum particles, maintaining their dispersed state and catalytic surface area throughout the catalyst's operational life.
Solution Approach 2:
The invention changes the physical and chemical parameters of the catalyst system by introducing the palladium additive, which modifies the thermal and structural properties of the platinum-coated support. This parameter change creates a more thermally stable structure that resists sintering at operating temperatures, extending the catalyst's useful life while maintaining ammonia oxidation efficiency.
3Object-generated harmful factors
If the catalyst is designed to convert all excess NH3, then emissions control is improved, but catalyst aging causes incomplete conversion leading to ammonia slip
Solution Approach 1:
The palladium-based additive acts as a stable intermediary that maintains the structural integrity of the platinum coating throughout the catalyst's life. By preventing platinum migration and sintering, the additive ensures that the catalyst maintains its complete NH3 conversion capability over time, preventing ammonia slip even as other catalyst components age.
Solution Approach 2:
The palladium additive is incorporated in advance into the catalyst structure as a protective cushion against aging effects. This pre-established protective layer anticipates and prevents the degradation mechanisms that would otherwise cause incomplete NH3 conversion, ensuring reliable performance throughout the catalyst's operational lifespan.
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 extends the usable life of the ammonia oxidation catalyst, reduces emissions, and enhances efficiency by preventing platinum migration and sintering, resulting in a durable and cost-effective exhaust treatment system.
Implementation Method 1
The second layer may catalytically oxidize at least a portion of the exhaust at the second layer
Implementation Method 2
The second layer includes an oxidation catalyst support... The oxidized portion of the exhaust may be directed from the second layer to the first layer
Implementation Method 3
a palladium additive, forming a bimetallic phase that stabilizes platinum and prevents its migration to the first layer
Implementation Method 4
an additional Al2O3 additive that secures platinum within the second layer, preventing sintering and maintaining catalytic efficiency
Data Source
AI summary
A treatment device configured to receive a flow of exhaust from a power source is disclosed. The treatment device may have a first layer, a second layer, and a substrate layer. The first layer may include a selective catalytic reduction layer, and the second layer may be disposed downstream of the first layer and include an oxidation catalyst support. The substrate layer may be disposed adjacent to the second layer. Additionally, an additive may be disposed downstream of the first layer. The additive may be operative to substantially prohibit migration of a component of the second layer to the first layer upon treatment of the flow of exhaust by the oxidation catalyst support.