High-Entropy Rare Earth Oxides for High-Temperature Emissions Control
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Solution Overview
Problem
Conventional oxygen storage materials in three-way catalysts degrade over time due to exposure to high temperatures, leading to a decrease in oxygen storage capacity and reaction efficiency, especially when subjected to fluctuations in air-fuel ratio (AFR) in internal combustion engines.
Innovation Solution
Incorporation of a high entropy oxygen storage material composed of at least five metal oxides in equal stoichiometric proportions, including rare earth metals, to enhance thermodynamic stability and maintain oxygen storage capacity and reactivity under harsh conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional oxygen storage materials (ceria-zirconia mixed oxides) are used in three-way catalysts, then the catalyst can perform redox reactions to treat emissions, but the oxygen storage material degrades over time due to high temperature exposure, leading to decreased oxygen storage capacity and reaction efficiency
Solution Approach 1:
The patent employs a composite oxygen storage material comprising ceria, zirconia, and rare earth oxides (lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium) in specific weight ratios. This composite structure combines the oxygen storage capacity of ceria, the structural stability of zirconia, and the thermal stability enhancement from rare earth oxides, creating a material that maintains performance over extended service life in high-temperature exhaust environments
Solution Approach 2:
The patent modifies the compositional parameters of conventional ceria-zirconia oxygen storage materials by incorporating rare earth oxides at controlled weight percentages (0.1-10% for individual rare earths, with total rare earth content of 1-20%). This parameter change optimizes the balance between oxygen storage capacity and thermal stability, preventing degradation while maintaining redox reaction efficiency throughout the catalyst's service life
2Adaptability or versatility
If the air-fuel ratio fluctuates during vehicle operation to accommodate changes in operating conditions, then the catalyst can adapt to different driving scenarios, but the oxygen storage material must continuously adjust, accelerating its degradation and performance loss
Solution Approach 1:
The multi-component composite oxygen storage material with rare earth oxides provides enhanced buffer capacity and chemical stability during air-fuel ratio fluctuations. The rare earth components (particularly gadolinium, terbium, and dysprosium) maintain structural integrity during repeated oxidation-reduction cycles, allowing the material to accommodate AFR changes without accelerating degradation
Solution Approach 2:
The oxygen storage material is designed with excess oxygen storage capacity and enhanced structural stability from rare earth oxides to cushion against the stresses of AFR fluctuations. This pre-engineered resilience allows the material to absorb and withstand repeated cycling between rich and lean conditions without losing performance, effectively cushioning the catalyst system from degradation
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 high entropy oxygen storage material increases the longevity and efficiency of three-way catalytic converters by maintaining oxygen storage and reaction performance despite exposure to high temperatures and AFR fluctuations, facilitating improved CO oxidation and water gas shift reactions.
Implementation Method 1
ceria, as well as zirconia. The rare earth oxides may be incorporated at between 2% to 15% by weight resulting in unequal molar amounts of rare earth metals forming the rare earth oxides of the oxygen storage material
Implementation Method 2
A water gas shift reaction may be facilitated by the high entropy oxygen storage material, which may enhance oxidation of CO
Implementation Method 3
The three-way catalyst may facilitate reduction and oxidation reactions, thereby oxidizing carbon monoxide (CO) and hydrocarbons (HC) to carbon dioxide (CO2) and water
Implementation Method 4
The three-way catalyst may facilitate reduction and oxidation reactions, thereby oxidizing carbon monoxide (CO) and hydrocarbons (HC) to carbon dioxide (CO2) and water, as well as reducing nitrogen oxides (NOx) to nitrogen gas (N2)
Data Source
AI summary
Methods and systems are provided for an emissions aftertreatment device. In one example, the emissions aftertreatment device may include a catalyst and a high entropy oxygen storage material formed of at least five metal oxides in equal molar proportions. The at least five metal oxides includes one or more rare earth metals as well as other metals with similar chemical properties as the rare earth metals.