Transition Metal Mixed Oxides for Oxygen Storage
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Solution Overview
Problem
Current oxygen storage materials based on CeO2/ZrO2 face challenges in efficiently operating under oscillating lean and rich conditions in gasoline engines, leading to suboptimal pollutant conversion and potential supply shortages, necessitating the development of alternative oxygen storage components that are cost-effective and offer improved oxygen storage capabilities.
Innovation Solution
The use of binary, ternary, or higher mixed oxides of specific transition metals like Fe, Mn, V, Nb, Ta, Mo, combined with catalytically active precious metals and a high surface area refractory metal oxide support, which can store oxygen efficiently and release it at lower temperatures, replacing Ce-based oxygen storage components in three-way catalytic converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If CeO2/ZrO2 based oxygen storage materials are used in three-way catalytic converters, then oxygen storage capacity is provided, but the materials face supply shortages and high costs
Solution Approach 1:
The patent replaces expensive and supply-constrained CeO2/ZrO2 oxygen storage materials with alternative mixed oxides based on abundant transition metals such as Fe, Mn, V, Nb, Ta, Mo. These alternative materials provide comparable oxygen storage capacity while being more cost-effective and readily available, eliminating dependency on rare earth metals.
Solution Approach 2:
The invention changes the chemical composition parameters of the oxygen storage material from Ce-Zr-based to transition metal-based mixed oxides. By adjusting the oxidation states and combining different transition metals, the patent achieves optimal oxygen storage performance using abundant, low-cost materials that substitute for expensive rare earth metals.
2Reliability
If traditional Ce-based oxygen storage components are used, then oxygen buffering is achieved, but pollutant conversion efficiency drops under oscillating lean and rich conditions
Solution Approach 1:
The patent employs composite mixed oxide structures combining multiple transition metals (Fe, Mn, V, Nb, Ta, Mo) in specific ratios. These composite materials exhibit enhanced oxygen storage and release characteristics that maintain effective pollutant conversion across oscillating lean and rich conditions, outperforming traditional single-component Ce-based materials.
Solution Approach 2:
The invention optimizes the local chemical environment by selecting specific transition metal combinations and their oxidation states. Different transition metals contribute different properties: Fe and Mn provide oxygen storage, while V, Nb, Ta, and Mo enhance oxygen mobility and release at lower temperatures, creating a synergistic composite with superior overall performance.
3Quantity of substance
If CeO2 is used to buffer catalyst from air/fuel ratio variations, then oxygen availability is maintained, but the release temperature is relatively high
Solution Approach 1:
The patent changes the thermal properties of the oxygen storage material by replacing CeO2 with transition metal mixed oxides. These alternative materials exhibit lower oxygen release temperatures due to their different crystal structures and oxygen binding energies, enabling more efficient oxygen release at lower exhaust temperatures.
Solution Approach 2:
The invention utilizes the porous structure and high surface area of transition metal mixed oxides to enhance oxygen release kinetics. The porous morphology provides numerous active sites and shorter diffusion paths for oxygen release, reducing the temperature required for effective oxygen release compared to dense CeO2 structures.
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
These alternative oxygen storage components demonstrate enhanced oxygen storage capacity and efficiency, with relative and absolute capacities exceeding those of traditional Ce-based materials, allowing for effective pollutant conversion across a broader operational range while reducing costs associated with Ce-based components.
Implementation Method 1
This activity is attributed to the reducibility and oxidability (reduction-oxidation or redox activity) of CeO2 via the 2Ce4+↔2Ce3+ [O2] reaction
Implementation Method 2
They achieve this by 'releasing' active oxygen from their 3-D structure in a rapid and reproducible manner under oxygen-depleted transients
Implementation Method 3
thereby enhancing the ability of the solid solution to buffer the air fuel transients occurring in the exhaust stream
Data Source
AI summary
The present invention is concerned with the use of certain oxygen storage components. In particular, the use of special mixed oxides as oxygen storage components in exhaust catalysis is disclosed.