Mixed Phase Oxide Catalysts for NOx Oxidation
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Solution Overview
Problem
Current emission control catalysts for lean burn engines, such as diesel engines, rely heavily on platinum-based materials, which are costly, necessitating the development of alternative non-precious metal catalysts that can effectively oxidize nitrogen oxides (NOx) and promote denitration reactions.
Innovation Solution
Mixed phase oxide catalysts comprising a spinel phase, a fluorite phase, and a mullite phase, incorporating metal oxides like cobalt, manganese, and dopants like alkali and alkaline earth metals, are used in engine exhaust systems to enhance NOx oxidation performance while reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If platinum-based catalysts are used to oxidize NOx, then NOx oxidation performance is improved, but cost increases
Solution Approach 1:
The patent replaces expensive platinum-based catalysts with affordable non-precious metal oxide catalysts comprising spinel phase, fluorite phase, and mullite phase. These alternative materials achieve comparable NOx oxidation performance while significantly reducing material cost, effectively substituting expensive resources with economical ones.
Solution Approach 2:
The patent employs a composite catalyst system combining three distinct phases: spinel phase (providing catalytic activity), fluorite phase (providing structural stability and oxygen storage), and mullite phase (providing thermal stability). This composite structure achieves superior NOx oxidation performance comparable to platinum catalysts while using non-precious metals, thus resolving the contradiction between performance and cost.
2Quantity of substance
If non-precious metal catalysts are used, then cost is reduced, but NOx oxidation performance may deteriorate
Solution Approach 1:
The patent creates a composite catalyst system where the spinel phase provides catalytic activity for NOx oxidation, the fluorite phase provides structural stability and oxygen storage capacity, and the mullite phase provides thermal stability. This synergistic combination enables non-precious metal catalysts to achieve NOx oxidation performance comparable to platinum-based catalysts, effectively resolving the performance-cost contradiction.
Solution Approach 2:
The patent optimizes the compositional parameters of the catalyst phases, specifically controlling the ratios of spinel phase, fluorite phase, and mullite phase, as well as the metal content within each phase. By carefully adjusting these parameters, the catalyst achieves optimal NOx oxidation performance while maintaining cost-effectiveness, demonstrating that performance can be maintained or improved through parameter optimization rather than relying on precious metals.
3Ease of manufacture
If single phase catalysts are used, then manufacturing is simpler, but oxidation catalyzing behavior and stability are insufficient
Solution Approach 1:
The patent employs a three-phase composite catalyst system where each phase contributes specific functional properties: spinel phase for catalytic activity, fluorite phase for structural stability and oxygen storage, and mullite phase for thermal stability. This composite structure achieves superior oxidation catalyzing behavior and stability compared to single-phase catalysts, while the manufacturing process remains feasible through conventional ceramic synthesis methods, balancing complexity and performance.
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 mixed phase oxide catalysts demonstrate comparable or superior NOx oxidation performance to platinum-based catalysts at high temperatures, offering a cost-effective alternative with improved stability and oxidation catalyzing behavior, and can be integrated into multi-layered systems for enhanced emission control.
Implementation Method 1
embodiments of the present invention are directed to emission control catalysts containing a mixed phase oxide compound... provide mixed phase catalysts containing at least two phases selected from a fluorite phase containing a cerium oxide, a spinel phase containing a metal oxide, and a mullite phase containing a metal oxide
Implementation Method 2
a fluorite phase containing a cerium oxide... Ce1−xAx+aBy+bMz−yOs
Implementation Method 3
a spinel phase containing a metal oxide... a mullite phase containing a metal oxide... improved stability and oxidation catalyzing behavior
Data Source
AI summary
An emission control catalyst for treating an engine exhaust includes non-precious metal group (“NPGM”) mixed phase oxide catalyst having a mullite phase containing optionally in close contact with other metal oxides. The mixed phase catalyst may be included in one or more layers or zones of a multi-layered or multi-zoned emission control catalyst and optionally in combination with precious metal catalysts such as Pt, Pd and Au.