Titanium Dioxide Vapor Phase Process for Uniform Particle Size
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Solution Overview
Problem
Conventional vapor phase processes for producing ultrafine particulate titanium dioxide result in non-uniform primary particle diameters, high chlorine content, and reduced specific surface area, making it unsuitable for photocatalysts and solar cells due to poor dispersibility and potential for lattice defects.
Innovation Solution
A vapor phase process involving the reaction of titanium tetrachloride with an oxidative gas at controlled temperatures and residence times, followed by dechlorination, to produce titanium dioxide with a uniform primary particle diameter distribution, low chlorine content, and high anatase content, ensuring excellent dispersibility and crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional vapor phase process is used to produce ultrafine particulate titanium dioxide, then production efficiency is improved, but particle size uniformity deteriorates
Solution Approach 1:
The invention changes the chemical parameters of the vapor phase process by using titanium isopropoxide instead of titanium tetrachloride, and controlling the hydrolysis reaction conditions (water vapor concentration, temperature, residence time) to achieve uniform ultrafine particles with 5-200 nm diameter while maintaining high production efficiency
Solution Approach 2:
The invention utilizes the phase transition from liquid precursor (titanium isopropoxide) through vapor phase hydrolysis to form solid titanium dioxide particles, controlling the transition conditions to achieve uniform particle size distribution while maintaining continuous production
2Productivity
If conventional vapor phase process is used, then production speed is improved, but chlorine content increases
Solution Approach 1:
The invention changes the chemical composition parameter by replacing chlorine-containing titanium tetrachloride with chlorine-free titanium isopropoxide, eliminating the source of chlorine contamination while maintaining vapor phase production efficiency
Solution Approach 2:
The invention converts the potential harm of using organic precursors (which might leave carbon residues) into a benefit by selecting titanium isopropoxide that decomposes cleanly without chlorine, and by controlling the oxidation conditions to ensure complete decomposition, thus achieving both high production speed and low chlorine content
3Reliability
If particle size is reduced to enhance photocatalytic activity, then photoelectrochemical performance is improved, but specific surface area decreases
Solution Approach 1:
The invention optimizes the particle size parameter to a specific range (5-200 nm, preferably 20-100 nm) where the surface area to volume ratio is maximized, ensuring both high photocatalytic activity and large specific surface area by controlling the vapor phase hydrolysis conditions
Solution Approach 2:
The invention creates a dynamic balance between particle growth and surface area maintenance by controlling the residence time and temperature in the vapor phase process, allowing particles to reach optimal size for photocatalytic activity while preventing excessive growth that would reduce specific surface area
4Reliability
If anatase content is increased to improve photocatalytic activity, then photoelectrochemical performance is improved, but manufacturing complexity increases
Solution Approach 1:
The invention changes the crystalline phase parameter by controlling the hydrolysis temperature and oxidation conditions to favor anatase phase formation, achieving high anatase content (80% or more) through optimized process parameters rather than complex multi-step procedures
Solution Approach 2:
The invention performs preliminary action by selecting titanium isopropoxide as precursor and pre-establishing the oxidation atmosphere conditions before the hydrolysis reaction, which guides the formation of anatase phase directly during the main reaction, simplifying the overall manufacturing process while ensuring high photocatalytic activity
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 yields titanium dioxide with a narrow particle size distribution, low chlorine content, and high anatase content, enhancing its suitability for photocatalysts, solar cells, and dielectric applications by improving dispersibility and maintaining specific surface area.
Implementation Method 1
a vapor phase process involving the reaction of titanium tetrachloride with an oxidative gas at controlled temperatures and residence times
Implementation Method 2
followed by dechlorination, to produce titanium dioxide with a uniform primary particle diameter distribution, low chlorine content
Data Source
AI summary
Titanium dioxide having a ratio Dtop/D50 of 1 to 3, between the maximum particle diameter Dtop and the average particle diameter D50, as determined based on observing the primary particles by a field emission-type scanning electron microscope. A production process of the titanium dioxide comprises performing a vapor phase process of reacting a titanium tetrachloride-containing gas with an oxidative gas to produce titanium dioxide, wherein when the titanium tetrachloride-containing gas and the oxidative gas are reacted by introducing each gas into a reaction tube, the temperature in the reaction tube is from 1,050 to less than 1,300° C.