Segmented Nitrogen Oxide Storage Catalyst Zones
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Solution Overview
Problem
Current nitrogen oxide removal technologies, such as SCR catalysts, are ineffective at low temperatures and require a change to rich engine operation for regeneration, leading to inefficiencies and increased fuel consumption, while passive nitrogen oxide storage catalysts need optimization for temperature-dependent storage and release.
Innovation Solution
A catalyst with catalytically active material zones of different compositions, including palladium and platinum with cerium oxide, arranged in specific layers on a carrier substrate, enabling nitrogen oxide storage at low temperatures and release at higher temperatures without the need for a change in engine operation, and also converting hydrocarbons and carbon monoxide effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SCR catalysts are used for nitrogen oxide removal, then nitrogen oxide conversion is effective at high temperatures, but they are ineffective at low temperatures and require a change to rich engine operation for regeneration
Solution Approach 1:
The catalyst is divided into three distinct material zones (A, B, and C) with different compositions and functions. Zone A contains palladium or palladium-platinum with cerium oxide for low-temperature storage. Zone B contains platinum or platinum-palladium with cerium oxide and/or cerium-zirconium mixed oxide for intermediate temperature conversion. Zone C contains platinum or platinum-palladium with carrier oxide for high-temperature operation. This segmentation allows each zone to operate effectively in its optimal temperature range without requiring engine operation changes.
Solution Approach 2:
Each material zone is designed with specific local properties tailored to its temperature range. Zone A has high palladium content for low-temperature activity. Zone B has balanced platinum and palladium with cerium-based materials for intermediate temperatures. Zone C has high platinum content for high-temperature stability. This local quality optimization ensures effective nitrogen oxide conversion across the entire temperature spectrum while maintaining consistent engine operation.
2Reliability
If nitrogen oxide storage catalysts are used to store and release nitrogen oxides, then complete conversion over wide temperature range is achieved, but the catalyst structure becomes complex with multiple material zones
Solution Approach 1:
The catalyst is segmented into three functional zones with progressive temperature optimization. Zone A (low temperature) uses Pd or Pd-Pt with CeO2 for storage. Zone B (intermediate temperature) uses Pt or Pt-Pd with CeO2 and/or Ce-Zr mixed oxide for transition. Zone C (high temperature) uses Pt or Pt-Pd with carrier oxide for release and conversion. This segmentation achieves complete conversion across wide temperature ranges while maintaining a systematic rather than random complex structure.
Solution Approach 2:
The catalyst employs composite material compositions in each zone. Zone A combines Pd/Pd-Pt with cerium oxide. Zone B combines Pt/Pt-Pd with cerium oxide and/or cerium-zirconium mixed oxide. Zone C combines Pt/Pt-Pd with carrier oxide. These composite materials provide synergistic effects that enhance performance while consolidating multiple functions into integrated material systems, reducing overall structural complexity.
3Reliability
If palladium and platinum are used in specific ratios with cerium oxide, then low-temperature storage and high-temperature release are optimized, but the manufacturing precision requirements increase
Solution Approach 1:
Each zone has locally optimized material compositions: Zone A uses Pd or Pd-Pt (weight ratio Pd:Pt>1) with cerium oxide for low-temperature storage. Zone B uses Pt or Pt-Pd (weight ratio Pt:Pd>1) with cerium oxide and/or cerium-zirconium mixed oxide for intermediate temperature transition. Zone C uses Pt or Pt-Pd (weight ratio Pt:Pd>1) with carrier oxide for high-temperature release. These localized compositions are designed to work together as an integrated system, where the progressive transition between zones compensates for variations in individual zone performance, thereby reducing overall manufacturing precision requirements compared to uniform high-precision specifications throughout.
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 catalyst effectively stores nitrogen oxides below 160°C and releases them above 160°C, facilitating complete nitrogen oxide conversion over a wide temperature range, improving conversion efficiency and reducing fuel consumption by avoiding rich operation changes.
Implementation Method 1
material zone A comprises palladium or palladium and platinum with a weight ratio of Pd:Pt>1, and cerium oxide
Implementation Method 2
converting hydrocarbons and carbon monoxide effectively
Implementation Method 3
material zone A comprises palladium or palladium and platinum with a weight ratio of Pd:Pt>1, and cerium oxide
Implementation Method 4
The catalyst effectively stores nitrogen oxides below 160°C and releases them above 160°C
Data Source
AI summary
The present invention relates to a catalyst which comprises a carrier substrate of length L, which extends between a first end face a and a second end face b, and catalytically active material zones A, B and C of different composition, wherein—material zone A comprises palladium or palladium and platinum with a weight ratio of Pd:Pt>1, and cerium oxide, —material zone B comprises platinum or platinum and palladium with a weight ratio of Pt:Pd>1, and cerium oxide and/or cerium/zirconium mixed oxide, and—material zone C comprises platinum or platinum and palladium with a weight ratio of Pt:Pd>1, and a carrier oxide, and wherein—material zone B is arranged above material zone A, and—material zone C is arranged above material zone B, and, starting from the second end face b of the carrier substrate, extends over a length of up to 60% of the length L. The invention also relates to a catalyst arrangement containing said catalyst.