Stable Sub-micron Titania Sols via Organic Base Dispersants
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Solution Overview
Problem
Conventional titania sols, such as S5-300B®, have low solids content, high flammability, and high surface tension, which limits their effectiveness and safety in catalytic applications, while existing peptization methods require severe conditions that are not optimal for producing high solids content sols with low viscosity and low surface tension.
Innovation Solution
A process using media milling with a combination of strong and weak organic bases as dispersants to stabilize titania sols, incorporating silica and tungsta to maintain the anatase phase and enhance surface area, resulting in high solids content, low viscosity, low surface tension, and low flammability sols with minimal odor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional peptization methods are used to prepare titania sols, then stable sols can be obtained, but severe conditions of time, temperature and pH are required and solids content remains low
Solution Approach 1:
The patent changes the chemical parameters of the peptization process by using organic carboxylic acids (formic, acetic, propionic acid) instead of conventional strong bases, operating at milder pH (4-6) and temperature (25-80°C) conditions to achieve both sol stability and improved manufacturing ease
Solution Approach 2:
Organic carboxylic acids serve as intermediary peptizing agents that bridge the titania particles, providing steric and electrostatic stabilization while operating under milder conditions than conventional strong bases, thus improving both stability and manufacturing conditions
2Quantity of substance
If high solids content is achieved in titania sols, then freight costs and processing efficiency improve, but viscosity increases making infiltration difficult
Solution Approach 1:
The patent achieves high solids content (20-40 wt%) with low viscosity by changing the peptization mechanism to use organic carboxylic acids, which provide effective steric stabilization that prevents particle aggregation even at high concentrations, maintaining low viscosity throughout
Solution Approach 2:
The patent creates a composite stabilization system using organic carboxylic acids that provide both electrostatic repulsion and steric hindrance, allowing high solids content to be maintained with low viscosity by combining multiple stabilization mechanisms
3Force
If conventional dispersants like diethylamine are used, then low viscosity and low surface tension are achieved, but flammability increases significantly
Solution Approach 1:
The patent replaces volatile, flammable amine dispersants with less volatile organic carboxylic acids that provide equivalent or superior dispersion performance without the flammability hazard, effectively substituting a harmful dispersant with a safer alternative
Solution Approach 2:
The patent converts the potential harm of using strong peptizing agents into a benefit by selecting organic carboxylic acids that provide sufficient peptization power while having inherently lower flammability and better environmental profiles than conventional amine-based dispersants
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 produces stable, high-solids titania sols with improved catalytic functionality, reduced flammability, and low viscosity, suitable for applications in SCR catalysts and photocatalysis, while maintaining the anatase phase stability and reducing operational risks.
Implementation Method 1
media milling of titania precursor materials using small, high density milling media to efficiently produce the ultrafine titania particles
Implementation Method 2
compositions of the present invention include, for example, mixtures of strong and weak organic bases used as dispersants to stabilize the titania sols
Implementation Method 3
incorporating silica and tungsta to maintain the anatase phase and enhance surface area
Data Source
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AI summary
The present invention is directed to compositions and processes for the production of stable, alkaline, high solids, low viscosity, low surface tension, low flammability, sub-micron titania sols that have minimal offensive odor and methods of their use. Compositions of the present invention include, for example, mixtures of strong and weak organic bases used as dispersants to stabilize the titania sols. The dispersant mixtures have been found to result in relatively high titania solids content, low surface tension, low viscosity suspensions that are low in flammability. Sols produced according to the present invention can be used, for example, in catalytic applications such as catalyst supports for diesel emission control, or in pollutant photocatalyst applications in which it is desirable to have the titania in sol form.