Cerium Oxide Nanoparticle Synthesis via Stabilizer Additive
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Solution Overview
Problem
Current methods for preparing cerium oxide nanoparticles face challenges in achieving small particle sizes and maintaining dispersion stability, particularly in aqueous preparations, which affects their compatibility with hydrocarbon fuels and efficiency in reducing emissions and improving fuel efficiency.
Innovation Solution
A process involving an aqueous reaction mixture with a cerous ion source, a monoether carboxylic acid nanoparticle stabilizer, and an oxidant at controlled temperatures to produce cerium oxide nanoparticles with a mean hydrodynamic diameter of 1-50 nm, and optionally doped with metals like zirconium or iron, using a molar ratio of stabilizer to metal ions greater than 0.2 to enhance stability and compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional aqueous precipitation methods are used to produce cerium oxide nanoparticles, then high through-put production is achieved, but the particles aggregate and dispersion stability is poor
Solution Approach 1:
The patent introduces a stabilizer additive as an intermediary substance that adsorbs onto the surface of cerium oxide nanoparticles during precipitation. This stabilizer creates steric or electrostatic repulsion between particles, preventing aggregation and maintaining dispersion stability throughout the high-volume production process while allowing continuous precipitation to occur
2Manufacturing precision
If multiple processing steps (isolation, washing, drying, calcination, grinding, milling, classification) are used to produce cerium oxide nanoparticles, then particle size control and purity are improved, but production time and cost increase
Solution Approach 1:
The patent incorporates the stabilizer additive at the beginning of the precipitation process, before particle formation is complete. This preliminary action of stabilizing the particle surface during nucleation and growth allows the particles to maintain their size and prevent aggregation throughout subsequent handling and processing steps, eliminating or reducing the need for extensive grinding, milling, and classification operations later
Solution Approach 2:
The patent combines multiple functions into the single precipitation step: particle formation, size control, and stability maintenance all occur simultaneously in one process operation. The stabilizer additive performs multiple roles including preventing aggregation, controlling particle size during growth, and ensuring long-term dispersion stability, thereby consolidating what would traditionally require multiple separate processing steps
3Reliability
If particle size is reduced to increase surface area and reactivity, then catalytic efficiency is improved, but dispersion stability becomes more difficult to maintain
Solution Approach 1:
The patent changes the chemical parameter of the system by introducing the stabilizer additive, which fundamentally alters the interaction between nanoparticles. The stabilizer modifies the surface properties and inter-particle forces, allowing ultrafine particles with high surface area to remain individually dispersed rather than aggregating, thus maintaining both high reactivity and dispersion stability
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 process achieves robust, cost-effective production of cerium oxide nanoparticles with improved dispersion stability and compatibility with hydrocarbon fuels, leading to enhanced fuel efficiency and reduced emissions.
Implementation Method 1
oxidation of cerous ion to ceric ion
Implementation Method 2
oxidation of cerous ion to ceric ion
Implementation Method 3
at least one monoether carboxylic acid nanoparticle stabilizer, wherein the molar ratio of the monoether carboxylic acid nanoparticle stabilizers to total metal ions is greater than 0.2
Implementation Method 4
converting the cerium (III) salt into a ceria (CeO2) precipitate
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A process for making cerium-containing oxide nanoparticles includes providing an aqueous reaction mixture containing a source of cerous ion, optionally a source of one or more metal ions (M) other than cerium, a source of hydroxide ion, at least one monoether carboxylic acid nanoparticle stabilizer wherein the molar ratio of said monoether carboxylic acid nanoparticle stabilizers to total metal ions is greater than 0.2, and an oxidant at an initial temperature in the range of about 20°C to about 95°C. Temperature conditions are provided effective to enable oxidation of cerous ion to ceric ion, thereby forming a product dispersion of cerium-containing oxide nanoparticles, optionally containing one or more metal ions (M), Ce1-xMxO2-δ, wherein "x" has a value from about 0.0 to about 0.95. The nanoparticles may have a mean hydrodynamic diameter from about 1 nm to about 50 nm, and a geometric diameter of less than about 45 nm.