Cerium Oxide Catalyst with Tunable Ce3+/Ce4+ Ratio
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Solution Overview
Problem
Current cerium oxide catalysts face limitations in maintaining catalytic performance at high temperatures and achieving optimal ratios of Ce3+ and Ce4+ valence states for efficient catalytic reactions.
Innovation Solution
Development of cerium oxide catalysts with a fluorite lattice structure, featuring mixed valence states of Ce3+ and Ce4+, and surface decoration with small particles like gold or palladium, activated in low-pressure environments to achieve a reversible ratio of Ce3+/(Ce3++Ce4+) ranging from 40% to 90%, maintaining catalytic ability up to 450°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cerium oxide catalysts are used to achieve catalytic reactions, then catalytic activity is improved, but maintaining catalytic performance at high temperatures deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Ce3+/(Ce3++Ce4+) ratio in the cerium oxide lattice to fall within 40%-90%, and by controlling the particle size of cerium oxide to 1-100 nm. These parameter optimizations enable the catalyst to maintain high catalytic activity while achieving thermal stability up to 450°C, resolving the contradiction between catalytic activity and high-temperature performance stability.
Solution Approach 2:
The patent creates a composite catalyst system by combining cerium oxide with other metals or metal oxides to form bimetallic or composite catalysts. This composite approach allows the catalyst to leverage the high catalytic activity of cerium oxide while the composite structure provides enhanced thermal stability and resistance to sintering at high temperatures, thus resolving the contradiction between productivity and reliability.
2Productivity
If cerium oxide catalysts are used to achieve catalytic reactions, then catalytic activity is improved, but achieving optimal Ce3+ and Ce4+ valence state ratios deteriorates
Solution Approach 1:
The patent employs parameter changes by optimizing the Ce3+/(Ce3++Ce4+) ratio to a specific range of 40%-90% and controlling particle size parameters. These parameter optimizations directly address the manufacturing precision challenge by providing clear target ranges for valence state ratio control, enabling consistent reproduction of optimal catalytic performance.
Solution Approach 2:
The patent applies preliminary action by pre-establishing the optimal Ce3+/(Ce3++Ce4+) ratio and particle size distribution during the synthesis process before the catalyst is put into service. This preliminary optimization of valence state ratios and physical parameters ensures that the catalyst achieves optimal performance from the outset, avoiding the need for post-production adjustments and simplifying manufacturing control.
3Productivity
If small particles are decorated on cerium oxide surface to enhance catalytic activity, then catalytic activity is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by decorating only the surface region of cerium oxide particles with small metal particles or metal oxides, rather than uniformly distributing materials throughout the entire structure. This localized decoration approach enhances catalytic activity at the active sites while keeping the overall catalyst structure relatively simple, avoiding the complexity of multi-phase or core-shell structures.
Solution Approach 2:
The patent utilizes porous or high-surface-area cerium oxide structures (such as nanotubes, nanowires, or porous particles) that provide abundant surface sites for catalysis. This approach enhances catalytic activity through increased surface area without requiring complex multi-component structures, as the porosity itself provides the necessary surface for active sites.
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 solution enhances catalytic activity and stability, achieving higher carbon monoxide conversion efficiency and maintaining long-term catalytic performance, with tunable Ce3+/Ce4+ ratios for specific applications.
Implementation Method 1
Cerium(IV) oxide can be reduced by carbon monoxide to cerium(III) oxide: 2CeO2+CO→Ce2O3+CO2, and cerium(III) oxide can be oxidized to cerium(IV) oxide: 2Ce2O3+O2→4CeO2
Implementation Method 2
the high mobility and storage capacity of oxygen within the lattice
Implementation Method 3
Cerium exists in both trivalent state (+3) and tetravalent (+4) state and may switch between the two in reduction and oxidation reactions
Data Source
AI summary
A catalyst that includes cerium oxide having a fluorite lattice structure is provided. The cerium oxide includes cerium atoms in mixed valence states of Ce3+/Ce4+, in which the ratio of Ce3+/(Ce3++Ce4+) in the lattice ranges from 40% to 90% at 20° C. The valence states Ce3+ and Ce4+ are reversible in reduction and oxidation reactions, and the cerium oxide maintains catalytic ability at temperatures at least up to 450° C.