Cerium Oxide Suspension Stabilized for Basic pH Catalysis
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Solution Overview
Problem
Existing suspensions of cerium compounds exhibit unsatisfactory stability and catalytic properties, particularly at varying pH levels, limiting their effectiveness in catalytic applications and other uses.
Innovation Solution
A suspension of oxygenated cerium compound particles with specific size distribution, stability, and composition, stabilized by carboxylic acids, which maintains particle size integrity even at basic pH levels, enhancing flexibility and applicability in catalyst preparation and other uses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cerium compound suspensions are used, then catalytic applications can be pursued, but stability and catalytic properties are unsatisfactory
Solution Approach 1:
The patent changes the chemical parameters of the suspension by introducing specific carboxylic acids (citric acid, succinic acid, malonic acid) as stabilizing agents and controlling pH levels. This transforms the suspension from unstable to stable, enabling reliable catalytic applications while maintaining good catalytic properties.
Solution Approach 2:
The carboxylic acids act as intermediary substances that mediate between the cerium compound particles and the suspension medium. These intermediaries stabilize the particles through surface complexation, preventing aggregation and maintaining stability without compromising catalytic activity.
2Adaptability or versatility
If pH is increased to basic levels, then flexibility in applications is improved, but particle size stability deteriorates
Solution Approach 1:
The patent employs carboxylic acids that can operate effectively across a wide pH range. These acids maintain particle size stability even when pH is increased to basic levels (up to pH 10-11), thereby providing flexibility for different applications while preserving composition stability.
Solution Approach 2:
The suspension is formulated as a composite system combining cerium compounds with specific carboxylic acids. This composite structure enables the suspension to maintain stability across varying pH conditions, providing both flexibility and compositional stability simultaneously.
3Area of stationary object
If particle size is reduced, then surface area and porosity are increased, but manufacturing precision becomes more difficult to control
Solution Approach 1:
The carboxylic acids serve as intermediary stabilizing agents that control particle size during the formation process. They prevent uncontrolled aggregation and fragmentation, thereby maintaining manufacturing precision while achieving the desired reduced particle size with high surface area and porosity.
Solution Approach 2:
The patent optimizes parameters such as pH, carboxylic acid concentration, and processing conditions to control particle size distribution. By carefully adjusting these parameters, the suspension achieves precise control over particle size while maximizing surface area and porosity for catalytic applications.
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 suspension demonstrates excellent stability and flexibility, allowing for effective use in catalyst preparation and other applications, including automotive exhaust gas depollution and abrasive compositions, with reduced particle size variation and increased surface area and porosity.
Implementation Method 1
The suspension displays an excellent stability when its pH is increased to basic pH
Implementation Method 2
the catalyst is reducing the amount of pollutants emitted from internal fuel combustion, namely carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx) and particulate matter (PM)
Implementation Method 3
Cerium compounds are oxygen buffers facilitating the conversion of the CO, HC and NOx around the stoichiometry
Implementation Method 4
Cerium compounds are considered in that case as oxygen booster to facilitate oxidation reaction
Data Source
AI summary
The present invention relates to a suspension of oxygenated cerium compound particles, said particles having a D50 of from 10 to 200 nm and a D90 below 1000 nm, determined by laser particle size analysis, in a liquid medium, preferably an aqueous liquid medium, including at least one carboxylic acid containing from 3 to 9 carbon atoms, or at least one functionalized carboxylic acid having 2 carbon atoms or any mixture thereof. The present invention also relates to the process for preparing such a suspension.