Perovskite Oxide Oxygen Storage Capacity and Release Speed
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Solution Overview
Problem
Current oxygen storage materials, such as ceria-zirconia and ceria-lanthana, have limitations in oxygen storage capacity and release speed, particularly under varying fuel-to-air ratios in three-way catalytic converters, necessitating the development of materials with enhanced oxygen storage characteristics for efficient catalytic reactions.
Innovation Solution
A method for preparing perovskite-based oxide compounds of the formula BaLnMn2O5+δ, where Ln represents rare-earth elements, using a sol-gel method followed by high-energy milling and isothermal oxidation/reduction cycles, to enhance oxygen storage capacity and release speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional oxygen storage materials like ceria-zirconia or ceria-lanthana are used, then the catalyst can maintain basic oxygen storage function, but the oxygen storage capacity and release speed are limited under varying fuel-to-air ratios
Solution Approach 1:
The patent modifies the chemical composition parameters of perovskite-based oxides by incorporating specific rare-earth elements (lanthanides) and adjusting the A/B site cation ratios. This compositional parameter change enables the material to achieve both high oxygen storage capacity (exceeding 500 μmol-O/g) and fast oxygen release kinetics, resolving the contradiction between storage capacity and release speed that plagues conventional ceria-based materials.
Solution Approach 2:
The patent creates composite perovskite structures combining multiple elements (e.g., Ba-Ln-Mn-O systems) where different components contribute complementary properties. The composite nature allows simultaneous optimization of oxygen storage capacity (from the perovskite structure) and oxygen release speed (enhanced by specific rare-earth element incorporation), overcoming the limitations of single-component conventional materials.
2Quantity of substance
If the oxygen storage capacity is increased to handle excess fuel conditions, then the catalyst performance under lean conditions may be compromised due to depleted OSM unable to adsorb oxygen back
Solution Approach 1:
The patent designs perovskite-based oxides with dynamic oxygen non-stoichiometry (δ in ABO3-δ) that can adapt to changing oxygen partial pressures. The material structure allows reversible oxygen incorporation and release, enabling the catalyst to dynamically adjust its oxygen storage state between rich and lean conditions, thus maintaining high adaptability across varying air-to-fuel ratios while preserving high storage capacity.
Solution Approach 2:
By adjusting the oxygen content parameter (δ) through controlled synthesis and reduction treatments, the patent creates perovskite materials with optimized initial oxygen deficiency that enhances both storage capacity and reversibility. This parameter optimization ensures the material can effectively cycle between oxygen-rich and oxygen-deficient states, maintaining versatility under different combustion conditions.
3Ease of manufacture
If perovskite materials are synthesized using conventional methods, then the production process is simpler, but the oxygen storage capacity and catalytic activity are insufficient
Solution Approach 1:
The patent employs a multi-step synthesis methodology where preliminary steps (such as precursor preparation, controlled drying, and staged heating) are designed to ensure uniform composition and phase formation. This preliminary structuring of the synthesis process, while adding steps, actually simplifies the overall manufacturing by preventing defects and ensuring reproducible high oxygen storage capacity without requiring complex post-processing or specialized equipment.
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 treated perovskite-based materials exhibit improved oxygen storage capacity and faster oxygen release, exceeding the performance of commercial materials like ceria-zirconia and ceria-lanthana, with increased oxygen storage capacity and reduced reduction times, suitable for a wide range of temperatures.
Implementation Method 1
perovskite-based oxide compounds having enhanced properties of oxygen reversible absorption (incorporation) and release
Implementation Method 2
This reaction utilizes ability of cerium for a reversible change of its oxidation state in the fluorite-type structure
Implementation Method 3
evaporating water to obtain a perovskite precursor
Data Source
Figure 1~2A
Figure 2B~3A
Figure 3B~3C
AI summary
A method for preparation of a perovskite-based oxide of the chemical formula: BaLnMn2O5+δ, where Ln represents at least one element selected from the group consisting of: Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu or a mixture of elements from the group consisting of: Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y, the method comprising synthesizing a perovskite precursor by a sol-gel method comprising the steps of: dissolving nitrates of respective elements in water, evaporating water to obtain a perovskite precursor, decompose excessive nitrates and oxidize carbon residues, grinding the perovskite precursor to a powdered perovskite precursor, annealing the powdered perovskite precursor in an atmosphere of 1vol.% of H2 in Ar, at a temperature range from 1000 to 1100°C and cooling the obtained perovskite of the formula BaLaMn2O5+δ. The method further comprises the following steps: high energy milling of the obtained perovskite of the formula BaLaMn2O5+δ for 5 to 30 minutes, and activating of the material by consecutive isothermal oxidation/reduction at the temperature of 500°C in a reducing atmosphere of H2 in Ar and in an oxidizing atmosphere of air.